Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * fs/dcache.c |
| 3 | * |
| 4 | * Complete reimplementation |
| 5 | * (C) 1997 Thomas Schoebel-Theuer, |
| 6 | * with heavy changes by Linus Torvalds |
| 7 | */ |
| 8 | |
| 9 | /* |
| 10 | * Notes on the allocation strategy: |
| 11 | * |
| 12 | * The dcache is a master of the icache - whenever a dcache entry |
| 13 | * exists, the inode will always exist. "iput()" is done either when |
| 14 | * the dcache entry is deleted or garbage collected. |
| 15 | */ |
| 16 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | #include <linux/syscalls.h> |
| 18 | #include <linux/string.h> |
| 19 | #include <linux/mm.h> |
| 20 | #include <linux/fs.h> |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 21 | #include <linux/fsnotify.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 22 | #include <linux/slab.h> |
| 23 | #include <linux/init.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #include <linux/hash.h> |
| 25 | #include <linux/cache.h> |
Paul Gortmaker | 630d9c4 | 2011-11-16 23:57:37 -0500 | [diff] [blame] | 26 | #include <linux/export.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | #include <linux/mount.h> |
| 28 | #include <linux/file.h> |
| 29 | #include <asm/uaccess.h> |
| 30 | #include <linux/security.h> |
| 31 | #include <linux/seqlock.h> |
| 32 | #include <linux/swap.h> |
| 33 | #include <linux/bootmem.h> |
Al Viro | 5ad4e53 | 2009-03-29 19:50:06 -0400 | [diff] [blame] | 34 | #include <linux/fs_struct.h> |
Frederic Weisbecker | 613afbf | 2009-07-16 15:44:29 +0200 | [diff] [blame] | 35 | #include <linux/hardirq.h> |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 36 | #include <linux/bit_spinlock.h> |
| 37 | #include <linux/rculist_bl.h> |
Linus Torvalds | 268bb0c | 2011-05-20 12:50:29 -0700 | [diff] [blame] | 38 | #include <linux/prefetch.h> |
David Howells | dd17994 | 2011-08-16 15:31:30 +0100 | [diff] [blame] | 39 | #include <linux/ratelimit.h> |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 40 | #include <linux/list_lru.h> |
Andrey Ryabinin | df4c0e3 | 2015-02-13 14:39:45 -0800 | [diff] [blame] | 41 | #include <linux/kasan.h> |
| 42 | |
David Howells | 07f3f05 | 2006-09-30 20:52:18 +0200 | [diff] [blame] | 43 | #include "internal.h" |
Al Viro | b2dba1a | 2011-11-23 19:26:23 -0500 | [diff] [blame] | 44 | #include "mount.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 46 | /* |
| 47 | * Usage: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 48 | * dcache->d_inode->i_lock protects: |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 49 | * - i_dentry, d_u.d_alias, d_inode of aliases |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 50 | * dcache_hash_bucket lock protects: |
| 51 | * - the dcache hash table |
| 52 | * s_anon bl list spinlock protects: |
| 53 | * - the s_anon list (see __d_drop) |
Dave Chinner | 1915684 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 54 | * dentry->d_sb->s_dentry_lru_lock protects: |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 55 | * - the dcache lru lists and counters |
| 56 | * d_lock protects: |
| 57 | * - d_flags |
| 58 | * - d_name |
| 59 | * - d_lru |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 60 | * - d_count |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 61 | * - d_unhashed() |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 62 | * - d_parent and d_subdirs |
| 63 | * - childrens' d_child and d_parent |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 64 | * - d_u.d_alias, d_inode |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 65 | * |
| 66 | * Ordering: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 67 | * dentry->d_inode->i_lock |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 68 | * dentry->d_lock |
Dave Chinner | 1915684 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 69 | * dentry->d_sb->s_dentry_lru_lock |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 70 | * dcache_hash_bucket lock |
| 71 | * s_anon lock |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 72 | * |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 73 | * If there is an ancestor relationship: |
| 74 | * dentry->d_parent->...->d_parent->d_lock |
| 75 | * ... |
| 76 | * dentry->d_parent->d_lock |
| 77 | * dentry->d_lock |
| 78 | * |
| 79 | * If no ancestor relationship: |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 80 | * if (dentry1 < dentry2) |
| 81 | * dentry1->d_lock |
| 82 | * dentry2->d_lock |
| 83 | */ |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 84 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
| 86 | |
Al Viro | 74c3cbe | 2007-07-22 08:04:18 -0400 | [diff] [blame] | 87 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 89 | EXPORT_SYMBOL(rename_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 91 | static struct kmem_cache *dentry_cache __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 93 | /* |
| 94 | * This is the single most critical data structure when it comes |
| 95 | * to the dcache: the hashtable for lookups. Somebody should try |
| 96 | * to make this good - I've just made it work. |
| 97 | * |
| 98 | * This hash-function tries to avoid losing too many bits of hash |
| 99 | * information, yet avoid using a prime hash-size or similar. |
| 100 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 102 | static unsigned int d_hash_mask __read_mostly; |
| 103 | static unsigned int d_hash_shift __read_mostly; |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 104 | |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 105 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 106 | |
Linus Torvalds | 8966be9 | 2012-03-02 14:23:30 -0800 | [diff] [blame] | 107 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
Linus Torvalds | 6d7d1a0 | 2012-03-19 16:19:53 -0700 | [diff] [blame] | 108 | unsigned int hash) |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 109 | { |
Linus Torvalds | 6d7d1a0 | 2012-03-19 16:19:53 -0700 | [diff] [blame] | 110 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
Linus Torvalds | 99d263d | 2014-09-13 11:30:10 -0700 | [diff] [blame] | 111 | return dentry_hashtable + hash_32(hash, d_hash_shift); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 112 | } |
| 113 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | /* Statistics gathering. */ |
| 115 | struct dentry_stat_t dentry_stat = { |
| 116 | .age_limit = 45, |
| 117 | }; |
| 118 | |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 119 | static DEFINE_PER_CPU(long, nr_dentry); |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 120 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 121 | |
| 122 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 123 | |
| 124 | /* |
| 125 | * Here we resort to our own counters instead of using generic per-cpu counters |
| 126 | * for consistency with what the vfs inode code does. We are expected to harvest |
| 127 | * better code and performance by having our own specialized counters. |
| 128 | * |
| 129 | * Please note that the loop is done over all possible CPUs, not over all online |
| 130 | * CPUs. The reason for this is that we don't want to play games with CPUs going |
| 131 | * on and off. If one of them goes off, we will just keep their counters. |
| 132 | * |
| 133 | * glommer: See cffbc8a for details, and if you ever intend to change this, |
| 134 | * please update all vfs counters to match. |
| 135 | */ |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 136 | static long get_nr_dentry(void) |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 137 | { |
| 138 | int i; |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 139 | long sum = 0; |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 140 | for_each_possible_cpu(i) |
| 141 | sum += per_cpu(nr_dentry, i); |
| 142 | return sum < 0 ? 0 : sum; |
| 143 | } |
| 144 | |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 145 | static long get_nr_dentry_unused(void) |
| 146 | { |
| 147 | int i; |
| 148 | long sum = 0; |
| 149 | for_each_possible_cpu(i) |
| 150 | sum += per_cpu(nr_dentry_unused, i); |
| 151 | return sum < 0 ? 0 : sum; |
| 152 | } |
| 153 | |
Joe Perches | 1f7e061 | 2014-06-06 14:38:05 -0700 | [diff] [blame] | 154 | int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer, |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 155 | size_t *lenp, loff_t *ppos) |
| 156 | { |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 157 | dentry_stat.nr_dentry = get_nr_dentry(); |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 158 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 159 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 160 | } |
| 161 | #endif |
| 162 | |
Linus Torvalds | 5483f18 | 2012-03-04 15:51:42 -0800 | [diff] [blame] | 163 | /* |
| 164 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. |
| 165 | * The strings are both count bytes long, and count is non-zero. |
| 166 | */ |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 167 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
| 168 | |
| 169 | #include <asm/word-at-a-time.h> |
| 170 | /* |
| 171 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a |
| 172 | * aligned allocation for this particular component. We don't |
| 173 | * strictly need the load_unaligned_zeropad() safety, but it |
| 174 | * doesn't hurt either. |
| 175 | * |
| 176 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do |
| 177 | * need the careful unaligned handling. |
| 178 | */ |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 179 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
Linus Torvalds | 5483f18 | 2012-03-04 15:51:42 -0800 | [diff] [blame] | 180 | { |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 181 | unsigned long a,b,mask; |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 182 | |
| 183 | for (;;) { |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 184 | a = *(unsigned long *)cs; |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 185 | b = load_unaligned_zeropad(ct); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 186 | if (tcount < sizeof(unsigned long)) |
| 187 | break; |
| 188 | if (unlikely(a != b)) |
| 189 | return 1; |
| 190 | cs += sizeof(unsigned long); |
| 191 | ct += sizeof(unsigned long); |
| 192 | tcount -= sizeof(unsigned long); |
| 193 | if (!tcount) |
| 194 | return 0; |
| 195 | } |
Will Deacon | a5c21dc | 2013-12-12 17:40:21 +0000 | [diff] [blame] | 196 | mask = bytemask_from_count(tcount); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 197 | return unlikely(!!((a ^ b) & mask)); |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 198 | } |
| 199 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 200 | #else |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 201 | |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 202 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 203 | { |
Linus Torvalds | 5483f18 | 2012-03-04 15:51:42 -0800 | [diff] [blame] | 204 | do { |
| 205 | if (*cs != *ct) |
| 206 | return 1; |
| 207 | cs++; |
| 208 | ct++; |
| 209 | tcount--; |
| 210 | } while (tcount); |
| 211 | return 0; |
| 212 | } |
| 213 | |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 214 | #endif |
| 215 | |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 216 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
| 217 | { |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 218 | const unsigned char *cs; |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 219 | /* |
| 220 | * Be careful about RCU walk racing with rename: |
| 221 | * use ACCESS_ONCE to fetch the name pointer. |
| 222 | * |
| 223 | * NOTE! Even if a rename will mean that the length |
| 224 | * was not loaded atomically, we don't care. The |
| 225 | * RCU walk will check the sequence count eventually, |
| 226 | * and catch it. And we won't overrun the buffer, |
| 227 | * because we're reading the name pointer atomically, |
| 228 | * and a dentry name is guaranteed to be properly |
| 229 | * terminated with a NUL byte. |
| 230 | * |
| 231 | * End result: even if 'len' is wrong, we'll exit |
| 232 | * early because the data cannot match (there can |
| 233 | * be no NUL in the ct/tcount data) |
| 234 | */ |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 235 | cs = ACCESS_ONCE(dentry->d_name.name); |
| 236 | smp_read_barrier_depends(); |
| 237 | return dentry_string_cmp(cs, ct, tcount); |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 238 | } |
| 239 | |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 240 | struct external_name { |
| 241 | union { |
| 242 | atomic_t count; |
| 243 | struct rcu_head head; |
| 244 | } u; |
| 245 | unsigned char name[]; |
| 246 | }; |
| 247 | |
| 248 | static inline struct external_name *external_name(struct dentry *dentry) |
| 249 | { |
| 250 | return container_of(dentry->d_name.name, struct external_name, name[0]); |
| 251 | } |
| 252 | |
Christoph Hellwig | 9c82ab9 | 2010-10-10 05:36:22 -0400 | [diff] [blame] | 253 | static void __d_free(struct rcu_head *head) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 254 | { |
Christoph Hellwig | 9c82ab9 | 2010-10-10 05:36:22 -0400 | [diff] [blame] | 255 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
| 256 | |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 257 | kmem_cache_free(dentry_cache, dentry); |
| 258 | } |
| 259 | |
| 260 | static void __d_free_external(struct rcu_head *head) |
| 261 | { |
| 262 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 263 | kfree(external_name(dentry)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 264 | kmem_cache_free(dentry_cache, dentry); |
| 265 | } |
| 266 | |
Al Viro | 810bb17 | 2014-10-12 12:45:37 -0400 | [diff] [blame] | 267 | static inline int dname_external(const struct dentry *dentry) |
| 268 | { |
| 269 | return dentry->d_name.name != dentry->d_iname; |
| 270 | } |
| 271 | |
David Howells | 4bf46a2 | 2015-03-05 14:09:22 +0000 | [diff] [blame] | 272 | /* |
| 273 | * Make sure other CPUs see the inode attached before the type is set. |
| 274 | */ |
| 275 | static inline void __d_set_inode_and_type(struct dentry *dentry, |
| 276 | struct inode *inode, |
| 277 | unsigned type_flags) |
| 278 | { |
| 279 | unsigned flags; |
| 280 | |
| 281 | dentry->d_inode = inode; |
| 282 | smp_wmb(); |
| 283 | flags = READ_ONCE(dentry->d_flags); |
| 284 | flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); |
| 285 | flags |= type_flags; |
| 286 | WRITE_ONCE(dentry->d_flags, flags); |
| 287 | } |
| 288 | |
| 289 | /* |
| 290 | * Ideally, we want to make sure that other CPUs see the flags cleared before |
| 291 | * the inode is detached, but this is really a violation of RCU principles |
| 292 | * since the ordering suggests we should always set inode before flags. |
| 293 | * |
| 294 | * We should instead replace or discard the entire dentry - but that sucks |
| 295 | * performancewise on mass deletion/rename. |
| 296 | */ |
| 297 | static inline void __d_clear_type_and_inode(struct dentry *dentry) |
| 298 | { |
| 299 | unsigned flags = READ_ONCE(dentry->d_flags); |
| 300 | |
| 301 | flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); |
| 302 | WRITE_ONCE(dentry->d_flags, flags); |
| 303 | smp_wmb(); |
| 304 | dentry->d_inode = NULL; |
| 305 | } |
| 306 | |
Al Viro | b4f0354 | 2014-04-29 23:40:14 -0400 | [diff] [blame] | 307 | static void dentry_free(struct dentry *dentry) |
| 308 | { |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 309 | WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias)); |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 310 | if (unlikely(dname_external(dentry))) { |
| 311 | struct external_name *p = external_name(dentry); |
| 312 | if (likely(atomic_dec_and_test(&p->u.count))) { |
| 313 | call_rcu(&dentry->d_u.d_rcu, __d_free_external); |
| 314 | return; |
| 315 | } |
| 316 | } |
Al Viro | b4f0354 | 2014-04-29 23:40:14 -0400 | [diff] [blame] | 317 | /* if dentry was never visible to RCU, immediate free is OK */ |
| 318 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) |
| 319 | __d_free(&dentry->d_u.d_rcu); |
| 320 | else |
| 321 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
| 322 | } |
| 323 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 324 | /** |
Peter Zijlstra | a7c6f57 | 2015-06-11 14:46:46 +0200 | [diff] [blame] | 325 | * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups |
Randy Dunlap | ff5fdb6 | 2011-01-22 20:16:06 -0800 | [diff] [blame] | 326 | * @dentry: the target dentry |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 327 | * After this call, in-progress rcu-walk path lookup will fail. This |
| 328 | * should be called after unhashing, and after changing d_inode (if |
| 329 | * the dentry has not already been unhashed). |
| 330 | */ |
Peter Zijlstra | a7c6f57 | 2015-06-11 14:46:46 +0200 | [diff] [blame] | 331 | static inline void dentry_rcuwalk_invalidate(struct dentry *dentry) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 332 | { |
Peter Zijlstra | a7c6f57 | 2015-06-11 14:46:46 +0200 | [diff] [blame] | 333 | lockdep_assert_held(&dentry->d_lock); |
| 334 | /* Go through am invalidation barrier */ |
| 335 | write_seqcount_invalidate(&dentry->d_seq); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 336 | } |
| 337 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 338 | /* |
| 339 | * Release the dentry's inode, using the filesystem |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 340 | * d_iput() operation if defined. Dentry has no refcount |
| 341 | * and is unhashed. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 342 | */ |
Arjan van de Ven | 858119e | 2006-01-14 13:20:43 -0800 | [diff] [blame] | 343 | static void dentry_iput(struct dentry * dentry) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 344 | __releases(dentry->d_lock) |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 345 | __releases(dentry->d_inode->i_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 346 | { |
| 347 | struct inode *inode = dentry->d_inode; |
| 348 | if (inode) { |
David Howells | 4bf46a2 | 2015-03-05 14:09:22 +0000 | [diff] [blame] | 349 | __d_clear_type_and_inode(dentry); |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 350 | hlist_del_init(&dentry->d_u.d_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 351 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 352 | spin_unlock(&inode->i_lock); |
Linus Torvalds | f805fbd | 2005-09-19 19:54:29 -0700 | [diff] [blame] | 353 | if (!inode->i_nlink) |
| 354 | fsnotify_inoderemove(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 355 | if (dentry->d_op && dentry->d_op->d_iput) |
| 356 | dentry->d_op->d_iput(dentry, inode); |
| 357 | else |
| 358 | iput(inode); |
| 359 | } else { |
| 360 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 361 | } |
| 362 | } |
| 363 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 364 | /* |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 365 | * Release the dentry's inode, using the filesystem |
| 366 | * d_iput() operation if defined. dentry remains in-use. |
| 367 | */ |
| 368 | static void dentry_unlink_inode(struct dentry * dentry) |
| 369 | __releases(dentry->d_lock) |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 370 | __releases(dentry->d_inode->i_lock) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 371 | { |
| 372 | struct inode *inode = dentry->d_inode; |
David Howells | 4bf46a2 | 2015-03-05 14:09:22 +0000 | [diff] [blame] | 373 | __d_clear_type_and_inode(dentry); |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 374 | hlist_del_init(&dentry->d_u.d_alias); |
Peter Zijlstra | a7c6f57 | 2015-06-11 14:46:46 +0200 | [diff] [blame] | 375 | dentry_rcuwalk_invalidate(dentry); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 376 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 377 | spin_unlock(&inode->i_lock); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 378 | if (!inode->i_nlink) |
| 379 | fsnotify_inoderemove(inode); |
| 380 | if (dentry->d_op && dentry->d_op->d_iput) |
| 381 | dentry->d_op->d_iput(dentry, inode); |
| 382 | else |
| 383 | iput(inode); |
| 384 | } |
| 385 | |
| 386 | /* |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 387 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry |
| 388 | * is in use - which includes both the "real" per-superblock |
| 389 | * LRU list _and_ the DCACHE_SHRINK_LIST use. |
| 390 | * |
| 391 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is |
| 392 | * on the shrink list (ie not on the superblock LRU list). |
| 393 | * |
| 394 | * The per-cpu "nr_dentry_unused" counters are updated with |
| 395 | * the DCACHE_LRU_LIST bit. |
| 396 | * |
| 397 | * These helper functions make sure we always follow the |
| 398 | * rules. d_lock must be held by the caller. |
| 399 | */ |
| 400 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) |
| 401 | static void d_lru_add(struct dentry *dentry) |
| 402 | { |
| 403 | D_FLAG_VERIFY(dentry, 0); |
| 404 | dentry->d_flags |= DCACHE_LRU_LIST; |
| 405 | this_cpu_inc(nr_dentry_unused); |
| 406 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); |
| 407 | } |
| 408 | |
| 409 | static void d_lru_del(struct dentry *dentry) |
| 410 | { |
| 411 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 412 | dentry->d_flags &= ~DCACHE_LRU_LIST; |
| 413 | this_cpu_dec(nr_dentry_unused); |
| 414 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); |
| 415 | } |
| 416 | |
| 417 | static void d_shrink_del(struct dentry *dentry) |
| 418 | { |
| 419 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); |
| 420 | list_del_init(&dentry->d_lru); |
| 421 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); |
| 422 | this_cpu_dec(nr_dentry_unused); |
| 423 | } |
| 424 | |
| 425 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) |
| 426 | { |
| 427 | D_FLAG_VERIFY(dentry, 0); |
| 428 | list_add(&dentry->d_lru, list); |
| 429 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; |
| 430 | this_cpu_inc(nr_dentry_unused); |
| 431 | } |
| 432 | |
| 433 | /* |
| 434 | * These can only be called under the global LRU lock, ie during the |
| 435 | * callback for freeing the LRU list. "isolate" removes it from the |
| 436 | * LRU lists entirely, while shrink_move moves it to the indicated |
| 437 | * private list. |
| 438 | */ |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 439 | static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry) |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 440 | { |
| 441 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 442 | dentry->d_flags &= ~DCACHE_LRU_LIST; |
| 443 | this_cpu_dec(nr_dentry_unused); |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 444 | list_lru_isolate(lru, &dentry->d_lru); |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 445 | } |
| 446 | |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 447 | static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry, |
| 448 | struct list_head *list) |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 449 | { |
| 450 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 451 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 452 | list_lru_isolate_move(lru, &dentry->d_lru, list); |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 453 | } |
| 454 | |
| 455 | /* |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 456 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 457 | */ |
| 458 | static void dentry_lru_add(struct dentry *dentry) |
| 459 | { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 460 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
| 461 | d_lru_add(dentry); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 462 | } |
| 463 | |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 464 | /** |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 465 | * d_drop - drop a dentry |
| 466 | * @dentry: dentry to drop |
| 467 | * |
| 468 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't |
| 469 | * be found through a VFS lookup any more. Note that this is different from |
| 470 | * deleting the dentry - d_delete will try to mark the dentry negative if |
| 471 | * possible, giving a successful _negative_ lookup, while d_drop will |
| 472 | * just make the cache lookup fail. |
| 473 | * |
| 474 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some |
| 475 | * reason (NFS timeouts or autofs deletes). |
| 476 | * |
| 477 | * __d_drop requires dentry->d_lock. |
| 478 | */ |
| 479 | void __d_drop(struct dentry *dentry) |
| 480 | { |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 481 | if (!d_unhashed(dentry)) { |
Al Viro | b61625d | 2013-10-04 11:09:01 -0400 | [diff] [blame] | 482 | struct hlist_bl_head *b; |
J. Bruce Fields | 7632e46 | 2012-06-28 12:10:55 -0400 | [diff] [blame] | 483 | /* |
| 484 | * Hashed dentries are normally on the dentry hashtable, |
| 485 | * with the exception of those newly allocated by |
| 486 | * d_obtain_alias, which are always IS_ROOT: |
| 487 | */ |
| 488 | if (unlikely(IS_ROOT(dentry))) |
Al Viro | b61625d | 2013-10-04 11:09:01 -0400 | [diff] [blame] | 489 | b = &dentry->d_sb->s_anon; |
| 490 | else |
| 491 | b = d_hash(dentry->d_parent, dentry->d_name.hash); |
| 492 | |
| 493 | hlist_bl_lock(b); |
| 494 | __hlist_bl_del(&dentry->d_hash); |
| 495 | dentry->d_hash.pprev = NULL; |
| 496 | hlist_bl_unlock(b); |
Peter Zijlstra | a7c6f57 | 2015-06-11 14:46:46 +0200 | [diff] [blame] | 497 | dentry_rcuwalk_invalidate(dentry); |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 498 | } |
| 499 | } |
| 500 | EXPORT_SYMBOL(__d_drop); |
| 501 | |
| 502 | void d_drop(struct dentry *dentry) |
| 503 | { |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 504 | spin_lock(&dentry->d_lock); |
| 505 | __d_drop(dentry); |
| 506 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 507 | } |
| 508 | EXPORT_SYMBOL(d_drop); |
| 509 | |
Al Viro | e55fd01 | 2014-05-28 13:51:12 -0400 | [diff] [blame] | 510 | static void __dentry_kill(struct dentry *dentry) |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 511 | { |
Al Viro | 41edf27 | 2014-05-01 10:30:00 -0400 | [diff] [blame] | 512 | struct dentry *parent = NULL; |
| 513 | bool can_free = true; |
Al Viro | 41edf27 | 2014-05-01 10:30:00 -0400 | [diff] [blame] | 514 | if (!IS_ROOT(dentry)) |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 515 | parent = dentry->d_parent; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 516 | |
Linus Torvalds | 0d98439 | 2013-09-08 13:46:52 -0700 | [diff] [blame] | 517 | /* |
| 518 | * The dentry is now unrecoverably dead to the world. |
| 519 | */ |
| 520 | lockref_mark_dead(&dentry->d_lockref); |
| 521 | |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 522 | /* |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 523 | * inform the fs via d_prune that this dentry is about to be |
| 524 | * unhashed and destroyed. |
| 525 | */ |
Al Viro | 2926620 | 2014-05-30 11:39:02 -0400 | [diff] [blame] | 526 | if (dentry->d_flags & DCACHE_OP_PRUNE) |
Yan, Zheng | 61572bb | 2013-04-15 14:13:21 +0800 | [diff] [blame] | 527 | dentry->d_op->d_prune(dentry); |
| 528 | |
Al Viro | 01b6035 | 2014-04-29 23:42:52 -0400 | [diff] [blame] | 529 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
| 530 | if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) |
| 531 | d_lru_del(dentry); |
Al Viro | 01b6035 | 2014-04-29 23:42:52 -0400 | [diff] [blame] | 532 | } |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 533 | /* if it was on the hash then remove it */ |
| 534 | __d_drop(dentry); |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 535 | __list_del_entry(&dentry->d_child); |
Al Viro | 03b3b88 | 2014-04-29 15:45:28 -0400 | [diff] [blame] | 536 | /* |
| 537 | * Inform d_walk() that we are no longer attached to the |
| 538 | * dentry tree |
| 539 | */ |
| 540 | dentry->d_flags |= DCACHE_DENTRY_KILLED; |
| 541 | if (parent) |
| 542 | spin_unlock(&parent->d_lock); |
| 543 | dentry_iput(dentry); |
| 544 | /* |
| 545 | * dentry_iput drops the locks, at which point nobody (except |
| 546 | * transient RCU lookups) can reach this dentry. |
| 547 | */ |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 548 | BUG_ON(dentry->d_lockref.count > 0); |
Al Viro | 03b3b88 | 2014-04-29 15:45:28 -0400 | [diff] [blame] | 549 | this_cpu_dec(nr_dentry); |
| 550 | if (dentry->d_op && dentry->d_op->d_release) |
| 551 | dentry->d_op->d_release(dentry); |
| 552 | |
Al Viro | 41edf27 | 2014-05-01 10:30:00 -0400 | [diff] [blame] | 553 | spin_lock(&dentry->d_lock); |
| 554 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
| 555 | dentry->d_flags |= DCACHE_MAY_FREE; |
| 556 | can_free = false; |
| 557 | } |
| 558 | spin_unlock(&dentry->d_lock); |
Al Viro | 41edf27 | 2014-05-01 10:30:00 -0400 | [diff] [blame] | 559 | if (likely(can_free)) |
| 560 | dentry_free(dentry); |
Al Viro | e55fd01 | 2014-05-28 13:51:12 -0400 | [diff] [blame] | 561 | } |
| 562 | |
| 563 | /* |
| 564 | * Finish off a dentry we've decided to kill. |
| 565 | * dentry->d_lock must be held, returns with it unlocked. |
| 566 | * If ref is non-zero, then decrement the refcount too. |
| 567 | * Returns dentry requiring refcount drop, or NULL if we're done. |
| 568 | */ |
Al Viro | 8cbf74d | 2014-05-29 09:18:26 -0400 | [diff] [blame] | 569 | static struct dentry *dentry_kill(struct dentry *dentry) |
Al Viro | e55fd01 | 2014-05-28 13:51:12 -0400 | [diff] [blame] | 570 | __releases(dentry->d_lock) |
| 571 | { |
| 572 | struct inode *inode = dentry->d_inode; |
| 573 | struct dentry *parent = NULL; |
| 574 | |
| 575 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) |
| 576 | goto failed; |
| 577 | |
| 578 | if (!IS_ROOT(dentry)) { |
| 579 | parent = dentry->d_parent; |
| 580 | if (unlikely(!spin_trylock(&parent->d_lock))) { |
| 581 | if (inode) |
| 582 | spin_unlock(&inode->i_lock); |
| 583 | goto failed; |
| 584 | } |
| 585 | } |
| 586 | |
| 587 | __dentry_kill(dentry); |
Al Viro | 03b3b88 | 2014-04-29 15:45:28 -0400 | [diff] [blame] | 588 | return parent; |
Al Viro | e55fd01 | 2014-05-28 13:51:12 -0400 | [diff] [blame] | 589 | |
| 590 | failed: |
Al Viro | 8cbf74d | 2014-05-29 09:18:26 -0400 | [diff] [blame] | 591 | spin_unlock(&dentry->d_lock); |
| 592 | cpu_relax(); |
Al Viro | e55fd01 | 2014-05-28 13:51:12 -0400 | [diff] [blame] | 593 | return dentry; /* try again with same dentry */ |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 594 | } |
| 595 | |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 596 | static inline struct dentry *lock_parent(struct dentry *dentry) |
| 597 | { |
| 598 | struct dentry *parent = dentry->d_parent; |
| 599 | if (IS_ROOT(dentry)) |
| 600 | return NULL; |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 601 | if (unlikely(dentry->d_lockref.count < 0)) |
Al Viro | c2338f2 | 2014-06-12 00:29:13 -0400 | [diff] [blame] | 602 | return NULL; |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 603 | if (likely(spin_trylock(&parent->d_lock))) |
| 604 | return parent; |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 605 | rcu_read_lock(); |
Al Viro | c2338f2 | 2014-06-12 00:29:13 -0400 | [diff] [blame] | 606 | spin_unlock(&dentry->d_lock); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 607 | again: |
| 608 | parent = ACCESS_ONCE(dentry->d_parent); |
| 609 | spin_lock(&parent->d_lock); |
| 610 | /* |
| 611 | * We can't blindly lock dentry until we are sure |
| 612 | * that we won't violate the locking order. |
| 613 | * Any changes of dentry->d_parent must have |
| 614 | * been done with parent->d_lock held, so |
| 615 | * spin_lock() above is enough of a barrier |
| 616 | * for checking if it's still our child. |
| 617 | */ |
| 618 | if (unlikely(parent != dentry->d_parent)) { |
| 619 | spin_unlock(&parent->d_lock); |
| 620 | goto again; |
| 621 | } |
| 622 | rcu_read_unlock(); |
| 623 | if (parent != dentry) |
Linus Torvalds | 9f12600 | 2014-05-31 09:13:21 -0700 | [diff] [blame] | 624 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 625 | else |
| 626 | parent = NULL; |
| 627 | return parent; |
| 628 | } |
| 629 | |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 630 | /* |
| 631 | * Try to do a lockless dput(), and return whether that was successful. |
| 632 | * |
| 633 | * If unsuccessful, we return false, having already taken the dentry lock. |
| 634 | * |
| 635 | * The caller needs to hold the RCU read lock, so that the dentry is |
| 636 | * guaranteed to stay around even if the refcount goes down to zero! |
| 637 | */ |
| 638 | static inline bool fast_dput(struct dentry *dentry) |
| 639 | { |
| 640 | int ret; |
| 641 | unsigned int d_flags; |
| 642 | |
| 643 | /* |
| 644 | * If we have a d_op->d_delete() operation, we sould not |
Al Viro | 75a6f82 | 2015-07-08 02:42:38 +0100 | [diff] [blame] | 645 | * let the dentry count go to zero, so use "put_or_lock". |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 646 | */ |
| 647 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) |
| 648 | return lockref_put_or_lock(&dentry->d_lockref); |
| 649 | |
| 650 | /* |
| 651 | * .. otherwise, we can try to just decrement the |
| 652 | * lockref optimistically. |
| 653 | */ |
| 654 | ret = lockref_put_return(&dentry->d_lockref); |
| 655 | |
| 656 | /* |
| 657 | * If the lockref_put_return() failed due to the lock being held |
| 658 | * by somebody else, the fast path has failed. We will need to |
| 659 | * get the lock, and then check the count again. |
| 660 | */ |
| 661 | if (unlikely(ret < 0)) { |
| 662 | spin_lock(&dentry->d_lock); |
| 663 | if (dentry->d_lockref.count > 1) { |
| 664 | dentry->d_lockref.count--; |
| 665 | spin_unlock(&dentry->d_lock); |
| 666 | return 1; |
| 667 | } |
| 668 | return 0; |
| 669 | } |
| 670 | |
| 671 | /* |
| 672 | * If we weren't the last ref, we're done. |
| 673 | */ |
| 674 | if (ret) |
| 675 | return 1; |
| 676 | |
| 677 | /* |
| 678 | * Careful, careful. The reference count went down |
| 679 | * to zero, but we don't hold the dentry lock, so |
| 680 | * somebody else could get it again, and do another |
| 681 | * dput(), and we need to not race with that. |
| 682 | * |
| 683 | * However, there is a very special and common case |
| 684 | * where we don't care, because there is nothing to |
| 685 | * do: the dentry is still hashed, it does not have |
| 686 | * a 'delete' op, and it's referenced and already on |
| 687 | * the LRU list. |
| 688 | * |
| 689 | * NOTE! Since we aren't locked, these values are |
| 690 | * not "stable". However, it is sufficient that at |
| 691 | * some point after we dropped the reference the |
| 692 | * dentry was hashed and the flags had the proper |
| 693 | * value. Other dentry users may have re-gotten |
| 694 | * a reference to the dentry and change that, but |
| 695 | * our work is done - we can leave the dentry |
| 696 | * around with a zero refcount. |
| 697 | */ |
| 698 | smp_rmb(); |
| 699 | d_flags = ACCESS_ONCE(dentry->d_flags); |
Al Viro | 75a6f82 | 2015-07-08 02:42:38 +0100 | [diff] [blame] | 700 | d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED; |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 701 | |
| 702 | /* Nothing to do? Dropping the reference was all we needed? */ |
| 703 | if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry)) |
| 704 | return 1; |
| 705 | |
| 706 | /* |
| 707 | * Not the fast normal case? Get the lock. We've already decremented |
| 708 | * the refcount, but we'll need to re-check the situation after |
| 709 | * getting the lock. |
| 710 | */ |
| 711 | spin_lock(&dentry->d_lock); |
| 712 | |
| 713 | /* |
| 714 | * Did somebody else grab a reference to it in the meantime, and |
| 715 | * we're no longer the last user after all? Alternatively, somebody |
| 716 | * else could have killed it and marked it dead. Either way, we |
| 717 | * don't need to do anything else. |
| 718 | */ |
| 719 | if (dentry->d_lockref.count) { |
| 720 | spin_unlock(&dentry->d_lock); |
| 721 | return 1; |
| 722 | } |
| 723 | |
| 724 | /* |
| 725 | * Re-get the reference we optimistically dropped. We hold the |
| 726 | * lock, and we just tested that it was zero, so we can just |
| 727 | * set it to 1. |
| 728 | */ |
| 729 | dentry->d_lockref.count = 1; |
| 730 | return 0; |
| 731 | } |
| 732 | |
| 733 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 734 | /* |
| 735 | * This is dput |
| 736 | * |
| 737 | * This is complicated by the fact that we do not want to put |
| 738 | * dentries that are no longer on any hash chain on the unused |
| 739 | * list: we'd much rather just get rid of them immediately. |
| 740 | * |
| 741 | * However, that implies that we have to traverse the dentry |
| 742 | * tree upwards to the parents which might _also_ now be |
| 743 | * scheduled for deletion (it may have been only waiting for |
| 744 | * its last child to go away). |
| 745 | * |
| 746 | * This tail recursion is done by hand as we don't want to depend |
| 747 | * on the compiler to always get this right (gcc generally doesn't). |
| 748 | * Real recursion would eat up our stack space. |
| 749 | */ |
| 750 | |
| 751 | /* |
| 752 | * dput - release a dentry |
| 753 | * @dentry: dentry to release |
| 754 | * |
| 755 | * Release a dentry. This will drop the usage count and if appropriate |
| 756 | * call the dentry unlink method as well as removing it from the queues and |
| 757 | * releasing its resources. If the parent dentries were scheduled for release |
| 758 | * they too may now get deleted. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 759 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 760 | void dput(struct dentry *dentry) |
| 761 | { |
Linus Torvalds | 8aab6a2 | 2013-09-08 13:26:18 -0700 | [diff] [blame] | 762 | if (unlikely(!dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 763 | return; |
| 764 | |
| 765 | repeat: |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 766 | rcu_read_lock(); |
| 767 | if (likely(fast_dput(dentry))) { |
| 768 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 769 | return; |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 770 | } |
| 771 | |
| 772 | /* Slow case: now with the dentry lock held */ |
| 773 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 774 | |
Linus Torvalds | 8aab6a2 | 2013-09-08 13:26:18 -0700 | [diff] [blame] | 775 | /* Unreachable? Get rid of it */ |
| 776 | if (unlikely(d_unhashed(dentry))) |
| 777 | goto kill_it; |
| 778 | |
Al Viro | 75a6f82 | 2015-07-08 02:42:38 +0100 | [diff] [blame] | 779 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) |
| 780 | goto kill_it; |
| 781 | |
Linus Torvalds | 8aab6a2 | 2013-09-08 13:26:18 -0700 | [diff] [blame] | 782 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 783 | if (dentry->d_op->d_delete(dentry)) |
Nick Piggin | 61f3dee | 2011-01-07 17:49:40 +1100 | [diff] [blame] | 784 | goto kill_it; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 785 | } |
Nick Piggin | 265ac90 | 2010-10-10 05:36:24 -0400 | [diff] [blame] | 786 | |
Linus Torvalds | 358eec1 | 2013-10-31 15:43:02 -0700 | [diff] [blame] | 787 | if (!(dentry->d_flags & DCACHE_REFERENCED)) |
| 788 | dentry->d_flags |= DCACHE_REFERENCED; |
Christoph Hellwig | a463335 | 2010-10-10 05:36:26 -0400 | [diff] [blame] | 789 | dentry_lru_add(dentry); |
Nick Piggin | 265ac90 | 2010-10-10 05:36:24 -0400 | [diff] [blame] | 790 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 791 | dentry->d_lockref.count--; |
Nick Piggin | 61f3dee | 2011-01-07 17:49:40 +1100 | [diff] [blame] | 792 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 793 | return; |
| 794 | |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 795 | kill_it: |
Al Viro | 8cbf74d | 2014-05-29 09:18:26 -0400 | [diff] [blame] | 796 | dentry = dentry_kill(dentry); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 797 | if (dentry) |
| 798 | goto repeat; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 799 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 800 | EXPORT_SYMBOL(dput); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 801 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 802 | |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 803 | /* This must be called with d_lock held */ |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 804 | static inline void __dget_dlock(struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 805 | { |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 806 | dentry->d_lockref.count++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 807 | } |
| 808 | |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 809 | static inline void __dget(struct dentry *dentry) |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 810 | { |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 811 | lockref_get(&dentry->d_lockref); |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 812 | } |
| 813 | |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 814 | struct dentry *dget_parent(struct dentry *dentry) |
| 815 | { |
Waiman Long | df3d0bb | 2013-09-02 11:29:22 -0700 | [diff] [blame] | 816 | int gotref; |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 817 | struct dentry *ret; |
| 818 | |
Waiman Long | df3d0bb | 2013-09-02 11:29:22 -0700 | [diff] [blame] | 819 | /* |
| 820 | * Do optimistic parent lookup without any |
| 821 | * locking. |
| 822 | */ |
| 823 | rcu_read_lock(); |
| 824 | ret = ACCESS_ONCE(dentry->d_parent); |
| 825 | gotref = lockref_get_not_zero(&ret->d_lockref); |
| 826 | rcu_read_unlock(); |
| 827 | if (likely(gotref)) { |
| 828 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) |
| 829 | return ret; |
| 830 | dput(ret); |
| 831 | } |
| 832 | |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 833 | repeat: |
Nick Piggin | a734eb4 | 2011-01-07 17:49:44 +1100 | [diff] [blame] | 834 | /* |
| 835 | * Don't need rcu_dereference because we re-check it was correct under |
| 836 | * the lock. |
| 837 | */ |
| 838 | rcu_read_lock(); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 839 | ret = dentry->d_parent; |
Nick Piggin | a734eb4 | 2011-01-07 17:49:44 +1100 | [diff] [blame] | 840 | spin_lock(&ret->d_lock); |
| 841 | if (unlikely(ret != dentry->d_parent)) { |
| 842 | spin_unlock(&ret->d_lock); |
| 843 | rcu_read_unlock(); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 844 | goto repeat; |
| 845 | } |
Nick Piggin | a734eb4 | 2011-01-07 17:49:44 +1100 | [diff] [blame] | 846 | rcu_read_unlock(); |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 847 | BUG_ON(!ret->d_lockref.count); |
| 848 | ret->d_lockref.count++; |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 849 | spin_unlock(&ret->d_lock); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 850 | return ret; |
| 851 | } |
| 852 | EXPORT_SYMBOL(dget_parent); |
| 853 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 854 | /** |
| 855 | * d_find_alias - grab a hashed alias of inode |
| 856 | * @inode: inode in question |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 857 | * |
| 858 | * If inode has a hashed alias, or is a directory and has any alias, |
| 859 | * acquire the reference to alias and return it. Otherwise return NULL. |
| 860 | * Notice that if inode is a directory there can be only one alias and |
| 861 | * it can be unhashed only if it has no children, or if it is the root |
Eric W. Biederman | 3ccb354 | 2014-02-12 16:08:06 -0800 | [diff] [blame] | 862 | * of a filesystem, or if the directory was renamed and d_revalidate |
| 863 | * was the first vfs operation to notice. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 864 | * |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 865 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
J. Bruce Fields | 52ed46f | 2014-01-16 11:15:51 -0500 | [diff] [blame] | 866 | * any other hashed alias over that one. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 867 | */ |
J. Bruce Fields | 52ed46f | 2014-01-16 11:15:51 -0500 | [diff] [blame] | 868 | static struct dentry *__d_find_alias(struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 869 | { |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 870 | struct dentry *alias, *discon_alias; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 871 | |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 872 | again: |
| 873 | discon_alias = NULL; |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 874 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 875 | spin_lock(&alias->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 876 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 877 | if (IS_ROOT(alias) && |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 878 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 879 | discon_alias = alias; |
J. Bruce Fields | 52ed46f | 2014-01-16 11:15:51 -0500 | [diff] [blame] | 880 | } else { |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 881 | __dget_dlock(alias); |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 882 | spin_unlock(&alias->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 883 | return alias; |
| 884 | } |
| 885 | } |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 886 | spin_unlock(&alias->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 887 | } |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 888 | if (discon_alias) { |
| 889 | alias = discon_alias; |
| 890 | spin_lock(&alias->d_lock); |
| 891 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
J. Bruce Fields | 8d80d7d | 2014-01-16 17:17:31 -0500 | [diff] [blame] | 892 | __dget_dlock(alias); |
| 893 | spin_unlock(&alias->d_lock); |
| 894 | return alias; |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 895 | } |
| 896 | spin_unlock(&alias->d_lock); |
| 897 | goto again; |
| 898 | } |
| 899 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 900 | } |
| 901 | |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 902 | struct dentry *d_find_alias(struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 903 | { |
David Howells | 214fda1 | 2006-03-25 03:06:36 -0800 | [diff] [blame] | 904 | struct dentry *de = NULL; |
| 905 | |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 906 | if (!hlist_empty(&inode->i_dentry)) { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 907 | spin_lock(&inode->i_lock); |
J. Bruce Fields | 52ed46f | 2014-01-16 11:15:51 -0500 | [diff] [blame] | 908 | de = __d_find_alias(inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 909 | spin_unlock(&inode->i_lock); |
David Howells | 214fda1 | 2006-03-25 03:06:36 -0800 | [diff] [blame] | 910 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 911 | return de; |
| 912 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 913 | EXPORT_SYMBOL(d_find_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 914 | |
| 915 | /* |
| 916 | * Try to kill dentries associated with this inode. |
| 917 | * WARNING: you must own a reference to inode. |
| 918 | */ |
| 919 | void d_prune_aliases(struct inode *inode) |
| 920 | { |
Domen Puncer | 0cdca3f | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 921 | struct dentry *dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 922 | restart: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 923 | spin_lock(&inode->i_lock); |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 924 | hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 925 | spin_lock(&dentry->d_lock); |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 926 | if (!dentry->d_lockref.count) { |
Al Viro | 29355c3 | 2014-05-30 11:25:30 -0400 | [diff] [blame] | 927 | struct dentry *parent = lock_parent(dentry); |
| 928 | if (likely(!dentry->d_lockref.count)) { |
| 929 | __dentry_kill(dentry); |
Yan, Zheng | 4a7795d | 2014-11-19 15:50:34 +0800 | [diff] [blame] | 930 | dput(parent); |
Al Viro | 29355c3 | 2014-05-30 11:25:30 -0400 | [diff] [blame] | 931 | goto restart; |
| 932 | } |
| 933 | if (parent) |
| 934 | spin_unlock(&parent->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 935 | } |
| 936 | spin_unlock(&dentry->d_lock); |
| 937 | } |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 938 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 939 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 940 | EXPORT_SYMBOL(d_prune_aliases); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 941 | |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 942 | static void shrink_dentry_list(struct list_head *list) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 943 | { |
Al Viro | 5c47e6d | 2014-04-29 16:13:18 -0400 | [diff] [blame] | 944 | struct dentry *dentry, *parent; |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 945 | |
Miklos Szeredi | 60942f2 | 2014-05-02 15:38:39 -0400 | [diff] [blame] | 946 | while (!list_empty(list)) { |
Al Viro | ff2fde9 | 2014-05-28 13:59:13 -0400 | [diff] [blame] | 947 | struct inode *inode; |
Miklos Szeredi | 60942f2 | 2014-05-02 15:38:39 -0400 | [diff] [blame] | 948 | dentry = list_entry(list->prev, struct dentry, d_lru); |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 949 | spin_lock(&dentry->d_lock); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 950 | parent = lock_parent(dentry); |
| 951 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 952 | /* |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 953 | * The dispose list is isolated and dentries are not accounted |
| 954 | * to the LRU here, so we can simply remove it from the list |
| 955 | * here regardless of whether it is referenced or not. |
| 956 | */ |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 957 | d_shrink_del(dentry); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 958 | |
| 959 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 960 | * We found an inuse dentry which was not removed from |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 961 | * the LRU because of laziness during lookup. Do not free it. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 962 | */ |
Linus Torvalds | 360f547 | 2015-01-09 15:19:03 -0800 | [diff] [blame] | 963 | if (dentry->d_lockref.count > 0) { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 964 | spin_unlock(&dentry->d_lock); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 965 | if (parent) |
| 966 | spin_unlock(&parent->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 967 | continue; |
| 968 | } |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 969 | |
Al Viro | 64fd72e | 2014-05-28 09:48:44 -0400 | [diff] [blame] | 970 | |
| 971 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) { |
| 972 | bool can_free = dentry->d_flags & DCACHE_MAY_FREE; |
| 973 | spin_unlock(&dentry->d_lock); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 974 | if (parent) |
| 975 | spin_unlock(&parent->d_lock); |
Al Viro | 64fd72e | 2014-05-28 09:48:44 -0400 | [diff] [blame] | 976 | if (can_free) |
| 977 | dentry_free(dentry); |
| 978 | continue; |
| 979 | } |
| 980 | |
Al Viro | ff2fde9 | 2014-05-28 13:59:13 -0400 | [diff] [blame] | 981 | inode = dentry->d_inode; |
| 982 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 983 | d_shrink_add(dentry, list); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 984 | spin_unlock(&dentry->d_lock); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 985 | if (parent) |
| 986 | spin_unlock(&parent->d_lock); |
Al Viro | 5c47e6d | 2014-04-29 16:13:18 -0400 | [diff] [blame] | 987 | continue; |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 988 | } |
Al Viro | ff2fde9 | 2014-05-28 13:59:13 -0400 | [diff] [blame] | 989 | |
Al Viro | ff2fde9 | 2014-05-28 13:59:13 -0400 | [diff] [blame] | 990 | __dentry_kill(dentry); |
Al Viro | 046b961 | 2014-05-29 08:54:52 -0400 | [diff] [blame] | 991 | |
Al Viro | 5c47e6d | 2014-04-29 16:13:18 -0400 | [diff] [blame] | 992 | /* |
| 993 | * We need to prune ancestors too. This is necessary to prevent |
| 994 | * quadratic behavior of shrink_dcache_parent(), but is also |
| 995 | * expected to be beneficial in reducing dentry cache |
| 996 | * fragmentation. |
| 997 | */ |
| 998 | dentry = parent; |
Al Viro | b2b8019 | 2014-05-29 09:11:45 -0400 | [diff] [blame] | 999 | while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { |
| 1000 | parent = lock_parent(dentry); |
| 1001 | if (dentry->d_lockref.count != 1) { |
| 1002 | dentry->d_lockref.count--; |
| 1003 | spin_unlock(&dentry->d_lock); |
| 1004 | if (parent) |
| 1005 | spin_unlock(&parent->d_lock); |
| 1006 | break; |
| 1007 | } |
| 1008 | inode = dentry->d_inode; /* can't be NULL */ |
| 1009 | if (unlikely(!spin_trylock(&inode->i_lock))) { |
| 1010 | spin_unlock(&dentry->d_lock); |
| 1011 | if (parent) |
| 1012 | spin_unlock(&parent->d_lock); |
| 1013 | cpu_relax(); |
| 1014 | continue; |
| 1015 | } |
| 1016 | __dentry_kill(dentry); |
| 1017 | dentry = parent; |
| 1018 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1019 | } |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1020 | } |
| 1021 | |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 1022 | static enum lru_status dentry_lru_isolate(struct list_head *item, |
| 1023 | struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1024 | { |
| 1025 | struct list_head *freeable = arg; |
| 1026 | struct dentry *dentry = container_of(item, struct dentry, d_lru); |
| 1027 | |
| 1028 | |
| 1029 | /* |
| 1030 | * we are inverting the lru lock/dentry->d_lock here, |
| 1031 | * so use a trylock. If we fail to get the lock, just skip |
| 1032 | * it |
| 1033 | */ |
| 1034 | if (!spin_trylock(&dentry->d_lock)) |
| 1035 | return LRU_SKIP; |
| 1036 | |
| 1037 | /* |
| 1038 | * Referenced dentries are still in use. If they have active |
| 1039 | * counts, just remove them from the LRU. Otherwise give them |
| 1040 | * another pass through the LRU. |
| 1041 | */ |
| 1042 | if (dentry->d_lockref.count) { |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 1043 | d_lru_isolate(lru, dentry); |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1044 | spin_unlock(&dentry->d_lock); |
| 1045 | return LRU_REMOVED; |
| 1046 | } |
| 1047 | |
| 1048 | if (dentry->d_flags & DCACHE_REFERENCED) { |
| 1049 | dentry->d_flags &= ~DCACHE_REFERENCED; |
| 1050 | spin_unlock(&dentry->d_lock); |
| 1051 | |
| 1052 | /* |
| 1053 | * The list move itself will be made by the common LRU code. At |
| 1054 | * this point, we've dropped the dentry->d_lock but keep the |
| 1055 | * lru lock. This is safe to do, since every list movement is |
| 1056 | * protected by the lru lock even if both locks are held. |
| 1057 | * |
| 1058 | * This is guaranteed by the fact that all LRU management |
| 1059 | * functions are intermediated by the LRU API calls like |
| 1060 | * list_lru_add and list_lru_del. List movement in this file |
| 1061 | * only ever occur through this functions or through callbacks |
| 1062 | * like this one, that are called from the LRU API. |
| 1063 | * |
| 1064 | * The only exceptions to this are functions like |
| 1065 | * shrink_dentry_list, and code that first checks for the |
| 1066 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be |
| 1067 | * operating only with stack provided lists after they are |
| 1068 | * properly isolated from the main list. It is thus, always a |
| 1069 | * local access. |
| 1070 | */ |
| 1071 | return LRU_ROTATE; |
| 1072 | } |
| 1073 | |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 1074 | d_lru_shrink_move(lru, dentry, freeable); |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1075 | spin_unlock(&dentry->d_lock); |
| 1076 | |
| 1077 | return LRU_REMOVED; |
| 1078 | } |
| 1079 | |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1080 | /** |
Dave Chinner | b48f03b | 2011-08-23 18:56:24 +1000 | [diff] [blame] | 1081 | * prune_dcache_sb - shrink the dcache |
| 1082 | * @sb: superblock |
Vladimir Davydov | 503c358 | 2015-02-12 14:58:47 -0800 | [diff] [blame] | 1083 | * @sc: shrink control, passed to list_lru_shrink_walk() |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1084 | * |
Vladimir Davydov | 503c358 | 2015-02-12 14:58:47 -0800 | [diff] [blame] | 1085 | * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This |
| 1086 | * is done when we need more memory and called from the superblock shrinker |
Dave Chinner | b48f03b | 2011-08-23 18:56:24 +1000 | [diff] [blame] | 1087 | * function. |
| 1088 | * |
| 1089 | * This function may fail to free any resources if all the dentries are in |
| 1090 | * use. |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1091 | */ |
Vladimir Davydov | 503c358 | 2015-02-12 14:58:47 -0800 | [diff] [blame] | 1092 | long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc) |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1093 | { |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1094 | LIST_HEAD(dispose); |
| 1095 | long freed; |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1096 | |
Vladimir Davydov | 503c358 | 2015-02-12 14:58:47 -0800 | [diff] [blame] | 1097 | freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc, |
| 1098 | dentry_lru_isolate, &dispose); |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1099 | shrink_dentry_list(&dispose); |
Dave Chinner | 0a234c6 | 2013-08-28 10:17:57 +1000 | [diff] [blame] | 1100 | return freed; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1101 | } |
| 1102 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1103 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 1104 | struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 1105 | { |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1106 | struct list_head *freeable = arg; |
| 1107 | struct dentry *dentry = container_of(item, struct dentry, d_lru); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 1108 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1109 | /* |
| 1110 | * we are inverting the lru lock/dentry->d_lock here, |
| 1111 | * so use a trylock. If we fail to get the lock, just skip |
| 1112 | * it |
| 1113 | */ |
| 1114 | if (!spin_trylock(&dentry->d_lock)) |
| 1115 | return LRU_SKIP; |
| 1116 | |
Vladimir Davydov | 3f97b16 | 2015-02-12 14:59:35 -0800 | [diff] [blame] | 1117 | d_lru_shrink_move(lru, dentry, freeable); |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1118 | spin_unlock(&dentry->d_lock); |
| 1119 | |
| 1120 | return LRU_REMOVED; |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 1121 | } |
| 1122 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1123 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 1124 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1125 | * shrink_dcache_sb - shrink dcache for a superblock |
| 1126 | * @sb: superblock |
| 1127 | * |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1128 | * Shrink the dcache for the specified super block. This is used to free |
| 1129 | * the dcache before unmounting a file system. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1130 | */ |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1131 | void shrink_dcache_sb(struct super_block *sb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1132 | { |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1133 | long freed; |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1134 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1135 | do { |
| 1136 | LIST_HEAD(dispose); |
| 1137 | |
| 1138 | freed = list_lru_walk(&sb->s_dentry_lru, |
| 1139 | dentry_lru_isolate_shrink, &dispose, UINT_MAX); |
| 1140 | |
| 1141 | this_cpu_sub(nr_dentry_unused, freed); |
| 1142 | shrink_dentry_list(&dispose); |
| 1143 | } while (freed > 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1144 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1145 | EXPORT_SYMBOL(shrink_dcache_sb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1146 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1147 | /** |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1148 | * enum d_walk_ret - action to talke during tree walk |
| 1149 | * @D_WALK_CONTINUE: contrinue walk |
| 1150 | * @D_WALK_QUIT: quit walk |
| 1151 | * @D_WALK_NORETRY: quit when retry is needed |
| 1152 | * @D_WALK_SKIP: skip this dentry and its children |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1153 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1154 | enum d_walk_ret { |
| 1155 | D_WALK_CONTINUE, |
| 1156 | D_WALK_QUIT, |
| 1157 | D_WALK_NORETRY, |
| 1158 | D_WALK_SKIP, |
| 1159 | }; |
| 1160 | |
| 1161 | /** |
| 1162 | * d_walk - walk the dentry tree |
| 1163 | * @parent: start of walk |
| 1164 | * @data: data passed to @enter() and @finish() |
| 1165 | * @enter: callback when first entering the dentry |
| 1166 | * @finish: callback when successfully finished the walk |
| 1167 | * |
| 1168 | * The @enter() and @finish() callbacks are called with d_lock held. |
| 1169 | */ |
| 1170 | static void d_walk(struct dentry *parent, void *data, |
| 1171 | enum d_walk_ret (*enter)(void *, struct dentry *), |
| 1172 | void (*finish)(void *)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1173 | { |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1174 | struct dentry *this_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1175 | struct list_head *next; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1176 | unsigned seq = 0; |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1177 | enum d_walk_ret ret; |
| 1178 | bool retry = true; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1179 | |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1180 | again: |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1181 | read_seqbegin_or_lock(&rename_lock, &seq); |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1182 | this_parent = parent; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1183 | spin_lock(&this_parent->d_lock); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1184 | |
| 1185 | ret = enter(data, this_parent); |
| 1186 | switch (ret) { |
| 1187 | case D_WALK_CONTINUE: |
| 1188 | break; |
| 1189 | case D_WALK_QUIT: |
| 1190 | case D_WALK_SKIP: |
| 1191 | goto out_unlock; |
| 1192 | case D_WALK_NORETRY: |
| 1193 | retry = false; |
| 1194 | break; |
| 1195 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1196 | repeat: |
| 1197 | next = this_parent->d_subdirs.next; |
| 1198 | resume: |
| 1199 | while (next != &this_parent->d_subdirs) { |
| 1200 | struct list_head *tmp = next; |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1201 | struct dentry *dentry = list_entry(tmp, struct dentry, d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1202 | next = tmp->next; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1203 | |
| 1204 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1205 | |
| 1206 | ret = enter(data, dentry); |
| 1207 | switch (ret) { |
| 1208 | case D_WALK_CONTINUE: |
| 1209 | break; |
| 1210 | case D_WALK_QUIT: |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1211 | spin_unlock(&dentry->d_lock); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1212 | goto out_unlock; |
| 1213 | case D_WALK_NORETRY: |
| 1214 | retry = false; |
| 1215 | break; |
| 1216 | case D_WALK_SKIP: |
| 1217 | spin_unlock(&dentry->d_lock); |
| 1218 | continue; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1219 | } |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1220 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1221 | if (!list_empty(&dentry->d_subdirs)) { |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1222 | spin_unlock(&this_parent->d_lock); |
| 1223 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1224 | this_parent = dentry; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1225 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1226 | goto repeat; |
| 1227 | } |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1228 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1229 | } |
| 1230 | /* |
| 1231 | * All done at this level ... ascend and resume the search. |
| 1232 | */ |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 1233 | rcu_read_lock(); |
| 1234 | ascend: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1235 | if (this_parent != parent) { |
Linus Torvalds | c826cb7 | 2011-03-15 15:29:21 -0700 | [diff] [blame] | 1236 | struct dentry *child = this_parent; |
Al Viro | 31dec13 | 2013-10-25 17:04:27 -0400 | [diff] [blame] | 1237 | this_parent = child->d_parent; |
| 1238 | |
Al Viro | 31dec13 | 2013-10-25 17:04:27 -0400 | [diff] [blame] | 1239 | spin_unlock(&child->d_lock); |
| 1240 | spin_lock(&this_parent->d_lock); |
| 1241 | |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 1242 | /* might go back up the wrong parent if we have had a rename. */ |
| 1243 | if (need_seqretry(&rename_lock, seq)) |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1244 | goto rename_retry; |
Al Viro | 2159184 | 2015-05-28 23:09:19 -0400 | [diff] [blame] | 1245 | /* go into the first sibling still alive */ |
| 1246 | do { |
| 1247 | next = child->d_child.next; |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 1248 | if (next == &this_parent->d_subdirs) |
| 1249 | goto ascend; |
| 1250 | child = list_entry(next, struct dentry, d_child); |
Al Viro | 2159184 | 2015-05-28 23:09:19 -0400 | [diff] [blame] | 1251 | } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); |
Al Viro | 31dec13 | 2013-10-25 17:04:27 -0400 | [diff] [blame] | 1252 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1253 | goto resume; |
| 1254 | } |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 1255 | if (need_seqretry(&rename_lock, seq)) |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1256 | goto rename_retry; |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 1257 | rcu_read_unlock(); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1258 | if (finish) |
| 1259 | finish(data); |
| 1260 | |
| 1261 | out_unlock: |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1262 | spin_unlock(&this_parent->d_lock); |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1263 | done_seqretry(&rename_lock, seq); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1264 | return; |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1265 | |
| 1266 | rename_retry: |
Al Viro | ca5358e | 2014-10-26 19:31:10 -0400 | [diff] [blame] | 1267 | spin_unlock(&this_parent->d_lock); |
| 1268 | rcu_read_unlock(); |
| 1269 | BUG_ON(seq & 1); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1270 | if (!retry) |
| 1271 | return; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1272 | seq = 1; |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1273 | goto again; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1274 | } |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1275 | |
| 1276 | /* |
| 1277 | * Search for at least 1 mount point in the dentry's subdirs. |
| 1278 | * We descend to the next level whenever the d_subdirs |
| 1279 | * list is non-empty and continue searching. |
| 1280 | */ |
| 1281 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1282 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
| 1283 | { |
| 1284 | int *ret = data; |
| 1285 | if (d_mountpoint(dentry)) { |
| 1286 | *ret = 1; |
| 1287 | return D_WALK_QUIT; |
| 1288 | } |
| 1289 | return D_WALK_CONTINUE; |
| 1290 | } |
| 1291 | |
Randy Dunlap | 69c88dc | 2013-10-19 14:57:07 -0700 | [diff] [blame] | 1292 | /** |
| 1293 | * have_submounts - check for mounts over a dentry |
| 1294 | * @parent: dentry to check. |
| 1295 | * |
| 1296 | * Return true if the parent or its subdirectories contain |
| 1297 | * a mount point |
| 1298 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1299 | int have_submounts(struct dentry *parent) |
| 1300 | { |
| 1301 | int ret = 0; |
| 1302 | |
| 1303 | d_walk(parent, &ret, check_mount, NULL); |
| 1304 | |
| 1305 | return ret; |
| 1306 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1307 | EXPORT_SYMBOL(have_submounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1308 | |
| 1309 | /* |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 1310 | * Called by mount code to set a mountpoint and check if the mountpoint is |
| 1311 | * reachable (e.g. NFS can unhash a directory dentry and then the complete |
| 1312 | * subtree can become unreachable). |
| 1313 | * |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1314 | * Only one of d_invalidate() and d_set_mounted() must succeed. For |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 1315 | * this reason take rename_lock and d_lock on dentry and ancestors. |
| 1316 | */ |
| 1317 | int d_set_mounted(struct dentry *dentry) |
| 1318 | { |
| 1319 | struct dentry *p; |
| 1320 | int ret = -ENOENT; |
| 1321 | write_seqlock(&rename_lock); |
| 1322 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1323 | /* Need exclusion wrt. d_invalidate() */ |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 1324 | spin_lock(&p->d_lock); |
| 1325 | if (unlikely(d_unhashed(p))) { |
| 1326 | spin_unlock(&p->d_lock); |
| 1327 | goto out; |
| 1328 | } |
| 1329 | spin_unlock(&p->d_lock); |
| 1330 | } |
| 1331 | spin_lock(&dentry->d_lock); |
| 1332 | if (!d_unlinked(dentry)) { |
| 1333 | dentry->d_flags |= DCACHE_MOUNTED; |
| 1334 | ret = 0; |
| 1335 | } |
| 1336 | spin_unlock(&dentry->d_lock); |
| 1337 | out: |
| 1338 | write_sequnlock(&rename_lock); |
| 1339 | return ret; |
| 1340 | } |
| 1341 | |
| 1342 | /* |
J. Bruce Fields | fd51790 | 2012-09-18 16:35:51 -0400 | [diff] [blame] | 1343 | * Search the dentry child list of the specified parent, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1344 | * and move any unused dentries to the end of the unused |
| 1345 | * list for prune_dcache(). We descend to the next level |
| 1346 | * whenever the d_subdirs list is non-empty and continue |
| 1347 | * searching. |
| 1348 | * |
| 1349 | * It returns zero iff there are no unused children, |
| 1350 | * otherwise it returns the number of children moved to |
| 1351 | * the end of the unused list. This may not be the total |
| 1352 | * number of unused children, because select_parent can |
| 1353 | * drop the lock and return early due to latency |
| 1354 | * constraints. |
| 1355 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1356 | |
| 1357 | struct select_data { |
| 1358 | struct dentry *start; |
| 1359 | struct list_head dispose; |
| 1360 | int found; |
| 1361 | }; |
| 1362 | |
| 1363 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1364 | { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1365 | struct select_data *data = _data; |
| 1366 | enum d_walk_ret ret = D_WALK_CONTINUE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1367 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1368 | if (data->start == dentry) |
| 1369 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1370 | |
Al Viro | fe91522 | 2014-05-03 00:02:25 -0400 | [diff] [blame] | 1371 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1372 | data->found++; |
Al Viro | fe91522 | 2014-05-03 00:02:25 -0400 | [diff] [blame] | 1373 | } else { |
| 1374 | if (dentry->d_flags & DCACHE_LRU_LIST) |
| 1375 | d_lru_del(dentry); |
| 1376 | if (!dentry->d_lockref.count) { |
| 1377 | d_shrink_add(dentry, &data->dispose); |
| 1378 | data->found++; |
| 1379 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1380 | } |
| 1381 | /* |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1382 | * We can return to the caller if we have found some (this |
| 1383 | * ensures forward progress). We'll be coming back to find |
| 1384 | * the rest. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1385 | */ |
Al Viro | fe91522 | 2014-05-03 00:02:25 -0400 | [diff] [blame] | 1386 | if (!list_empty(&data->dispose)) |
| 1387 | ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1388 | out: |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1389 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1390 | } |
| 1391 | |
| 1392 | /** |
| 1393 | * shrink_dcache_parent - prune dcache |
| 1394 | * @parent: parent of entries to prune |
| 1395 | * |
| 1396 | * Prune the dcache to remove unused children of the parent dentry. |
| 1397 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1398 | void shrink_dcache_parent(struct dentry *parent) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1399 | { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1400 | for (;;) { |
| 1401 | struct select_data data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1402 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1403 | INIT_LIST_HEAD(&data.dispose); |
| 1404 | data.start = parent; |
| 1405 | data.found = 0; |
| 1406 | |
| 1407 | d_walk(parent, &data, select_collect, NULL); |
| 1408 | if (!data.found) |
| 1409 | break; |
| 1410 | |
| 1411 | shrink_dentry_list(&data.dispose); |
Greg Thelen | 421348f | 2013-04-30 15:26:48 -0700 | [diff] [blame] | 1412 | cond_resched(); |
| 1413 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1414 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1415 | EXPORT_SYMBOL(shrink_dcache_parent); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1416 | |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1417 | static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1418 | { |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1419 | /* it has busy descendents; complain about those instead */ |
| 1420 | if (!list_empty(&dentry->d_subdirs)) |
| 1421 | return D_WALK_CONTINUE; |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1422 | |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1423 | /* root with refcount 1 is fine */ |
| 1424 | if (dentry == _data && dentry->d_lockref.count == 1) |
| 1425 | return D_WALK_CONTINUE; |
| 1426 | |
| 1427 | printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} " |
| 1428 | " still in use (%d) [unmount of %s %s]\n", |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1429 | dentry, |
| 1430 | dentry->d_inode ? |
| 1431 | dentry->d_inode->i_ino : 0UL, |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1432 | dentry, |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1433 | dentry->d_lockref.count, |
| 1434 | dentry->d_sb->s_type->name, |
| 1435 | dentry->d_sb->s_id); |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1436 | WARN_ON(1); |
| 1437 | return D_WALK_CONTINUE; |
| 1438 | } |
| 1439 | |
| 1440 | static void do_one_tree(struct dentry *dentry) |
| 1441 | { |
| 1442 | shrink_dcache_parent(dentry); |
| 1443 | d_walk(dentry, dentry, umount_check, NULL); |
| 1444 | d_drop(dentry); |
| 1445 | dput(dentry); |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1446 | } |
| 1447 | |
| 1448 | /* |
| 1449 | * destroy the dentries attached to a superblock on unmounting |
| 1450 | */ |
| 1451 | void shrink_dcache_for_umount(struct super_block *sb) |
| 1452 | { |
| 1453 | struct dentry *dentry; |
| 1454 | |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1455 | WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked"); |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1456 | |
| 1457 | dentry = sb->s_root; |
| 1458 | sb->s_root = NULL; |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1459 | do_one_tree(dentry); |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1460 | |
| 1461 | while (!hlist_bl_empty(&sb->s_anon)) { |
Al Viro | 9c8c10e | 2014-05-02 20:36:10 -0400 | [diff] [blame] | 1462 | dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash)); |
| 1463 | do_one_tree(dentry); |
Al Viro | 42c3260 | 2013-11-08 12:31:16 -0500 | [diff] [blame] | 1464 | } |
| 1465 | } |
| 1466 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1467 | struct detach_data { |
| 1468 | struct select_data select; |
| 1469 | struct dentry *mountpoint; |
| 1470 | }; |
| 1471 | static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry) |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1472 | { |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1473 | struct detach_data *data = _data; |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1474 | |
| 1475 | if (d_mountpoint(dentry)) { |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1476 | __dget_dlock(dentry); |
| 1477 | data->mountpoint = dentry; |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1478 | return D_WALK_QUIT; |
| 1479 | } |
| 1480 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1481 | return select_collect(&data->select, dentry); |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1482 | } |
| 1483 | |
| 1484 | static void check_and_drop(void *_data) |
| 1485 | { |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1486 | struct detach_data *data = _data; |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1487 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1488 | if (!data->mountpoint && !data->select.found) |
| 1489 | __d_drop(data->select.start); |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1490 | } |
| 1491 | |
| 1492 | /** |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1493 | * d_invalidate - detach submounts, prune dcache, and drop |
| 1494 | * @dentry: dentry to invalidate (aka detach, prune and drop) |
| 1495 | * |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1496 | * no dcache lock. |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1497 | * |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1498 | * The final d_drop is done as an atomic operation relative to |
| 1499 | * rename_lock ensuring there are no races with d_set_mounted. This |
| 1500 | * ensures there are no unhashed dentries on the path to a mountpoint. |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1501 | */ |
Eric W. Biederman | 5542aa2 | 2014-02-13 09:46:25 -0800 | [diff] [blame] | 1502 | void d_invalidate(struct dentry *dentry) |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1503 | { |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1504 | /* |
| 1505 | * If it's already been dropped, return OK. |
| 1506 | */ |
| 1507 | spin_lock(&dentry->d_lock); |
| 1508 | if (d_unhashed(dentry)) { |
| 1509 | spin_unlock(&dentry->d_lock); |
Eric W. Biederman | 5542aa2 | 2014-02-13 09:46:25 -0800 | [diff] [blame] | 1510 | return; |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1511 | } |
| 1512 | spin_unlock(&dentry->d_lock); |
| 1513 | |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1514 | /* Negative dentries can be dropped without further checks */ |
| 1515 | if (!dentry->d_inode) { |
| 1516 | d_drop(dentry); |
Eric W. Biederman | 5542aa2 | 2014-02-13 09:46:25 -0800 | [diff] [blame] | 1517 | return; |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1518 | } |
| 1519 | |
| 1520 | for (;;) { |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1521 | struct detach_data data; |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1522 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1523 | data.mountpoint = NULL; |
| 1524 | INIT_LIST_HEAD(&data.select.dispose); |
| 1525 | data.select.start = dentry; |
| 1526 | data.select.found = 0; |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1527 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1528 | d_walk(dentry, &data, detach_and_collect, check_and_drop); |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1529 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1530 | if (data.select.found) |
| 1531 | shrink_dentry_list(&data.select.dispose); |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1532 | |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 1533 | if (data.mountpoint) { |
| 1534 | detach_mounts(data.mountpoint); |
| 1535 | dput(data.mountpoint); |
| 1536 | } |
| 1537 | |
| 1538 | if (!data.mountpoint && !data.select.found) |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1539 | break; |
| 1540 | |
| 1541 | cond_resched(); |
| 1542 | } |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1543 | } |
Eric W. Biederman | 1ffe46d | 2014-02-13 09:39:37 -0800 | [diff] [blame] | 1544 | EXPORT_SYMBOL(d_invalidate); |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1545 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1546 | /** |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1547 | * __d_alloc - allocate a dcache entry |
| 1548 | * @sb: filesystem it will belong to |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1549 | * @name: qstr of the name |
| 1550 | * |
| 1551 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 1552 | * available. On a success the dentry is returned. The name passed in is |
| 1553 | * copied and the copy passed in may be reused after this call. |
| 1554 | */ |
| 1555 | |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1556 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1557 | { |
| 1558 | struct dentry *dentry; |
| 1559 | char *dname; |
| 1560 | |
Mel Gorman | e12ba74 | 2007-10-16 01:25:52 -0700 | [diff] [blame] | 1561 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1562 | if (!dentry) |
| 1563 | return NULL; |
| 1564 | |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 1565 | /* |
| 1566 | * We guarantee that the inline name is always NUL-terminated. |
| 1567 | * This way the memcpy() done by the name switching in rename |
| 1568 | * will still always have a NUL at the end, even if we might |
| 1569 | * be overwriting an internal NUL character |
| 1570 | */ |
| 1571 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1572 | if (name->len > DNAME_INLINE_LEN-1) { |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 1573 | size_t size = offsetof(struct external_name, name[1]); |
| 1574 | struct external_name *p = kmalloc(size + name->len, GFP_KERNEL); |
| 1575 | if (!p) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1576 | kmem_cache_free(dentry_cache, dentry); |
| 1577 | return NULL; |
| 1578 | } |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 1579 | atomic_set(&p->u.count, 1); |
| 1580 | dname = p->name; |
Andrey Ryabinin | df4c0e3 | 2015-02-13 14:39:45 -0800 | [diff] [blame] | 1581 | if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS)) |
| 1582 | kasan_unpoison_shadow(dname, |
| 1583 | round_up(name->len + 1, sizeof(unsigned long))); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1584 | } else { |
| 1585 | dname = dentry->d_iname; |
| 1586 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1587 | |
| 1588 | dentry->d_name.len = name->len; |
| 1589 | dentry->d_name.hash = name->hash; |
| 1590 | memcpy(dname, name->name, name->len); |
| 1591 | dname[name->len] = 0; |
| 1592 | |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 1593 | /* Make sure we always see the terminating NUL character */ |
| 1594 | smp_wmb(); |
| 1595 | dentry->d_name.name = dname; |
| 1596 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 1597 | dentry->d_lockref.count = 1; |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 1598 | dentry->d_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1599 | spin_lock_init(&dentry->d_lock); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1600 | seqcount_init(&dentry->d_seq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1601 | dentry->d_inode = NULL; |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1602 | dentry->d_parent = dentry; |
| 1603 | dentry->d_sb = sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1604 | dentry->d_op = NULL; |
| 1605 | dentry->d_fsdata = NULL; |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 1606 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1607 | INIT_LIST_HEAD(&dentry->d_lru); |
| 1608 | INIT_LIST_HEAD(&dentry->d_subdirs); |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1609 | INIT_HLIST_NODE(&dentry->d_u.d_alias); |
| 1610 | INIT_LIST_HEAD(&dentry->d_child); |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1611 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1612 | |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 1613 | this_cpu_inc(nr_dentry); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 1614 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1615 | return dentry; |
| 1616 | } |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1617 | |
| 1618 | /** |
| 1619 | * d_alloc - allocate a dcache entry |
| 1620 | * @parent: parent of entry to allocate |
| 1621 | * @name: qstr of the name |
| 1622 | * |
| 1623 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 1624 | * available. On a success the dentry is returned. The name passed in is |
| 1625 | * copied and the copy passed in may be reused after this call. |
| 1626 | */ |
| 1627 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
| 1628 | { |
| 1629 | struct dentry *dentry = __d_alloc(parent->d_sb, name); |
| 1630 | if (!dentry) |
| 1631 | return NULL; |
| 1632 | |
| 1633 | spin_lock(&parent->d_lock); |
| 1634 | /* |
| 1635 | * don't need child lock because it is not subject |
| 1636 | * to concurrency here |
| 1637 | */ |
| 1638 | __dget_dlock(parent); |
| 1639 | dentry->d_parent = parent; |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1640 | list_add(&dentry->d_child, &parent->d_subdirs); |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1641 | spin_unlock(&parent->d_lock); |
| 1642 | |
| 1643 | return dentry; |
| 1644 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1645 | EXPORT_SYMBOL(d_alloc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1646 | |
J. Bruce Fields | e1a24bb | 2012-06-29 16:20:47 -0400 | [diff] [blame] | 1647 | /** |
| 1648 | * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) |
| 1649 | * @sb: the superblock |
| 1650 | * @name: qstr of the name |
| 1651 | * |
| 1652 | * For a filesystem that just pins its dentries in memory and never |
| 1653 | * performs lookups at all, return an unhashed IS_ROOT dentry. |
| 1654 | */ |
Nick Piggin | 4b93688 | 2011-01-07 17:50:07 +1100 | [diff] [blame] | 1655 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
| 1656 | { |
J. Bruce Fields | e1a24bb | 2012-06-29 16:20:47 -0400 | [diff] [blame] | 1657 | return __d_alloc(sb, name); |
Nick Piggin | 4b93688 | 2011-01-07 17:50:07 +1100 | [diff] [blame] | 1658 | } |
| 1659 | EXPORT_SYMBOL(d_alloc_pseudo); |
| 1660 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1661 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
| 1662 | { |
| 1663 | struct qstr q; |
| 1664 | |
| 1665 | q.name = name; |
| 1666 | q.len = strlen(name); |
| 1667 | q.hash = full_name_hash(q.name, q.len); |
| 1668 | return d_alloc(parent, &q); |
| 1669 | } |
H Hartley Sweeten | ef26ca9 | 2009-09-29 20:09:42 -0400 | [diff] [blame] | 1670 | EXPORT_SYMBOL(d_alloc_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1671 | |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1672 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
| 1673 | { |
Linus Torvalds | 6f7f7ca | 2011-01-14 13:26:18 -0800 | [diff] [blame] | 1674 | WARN_ON_ONCE(dentry->d_op); |
| 1675 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1676 | DCACHE_OP_COMPARE | |
| 1677 | DCACHE_OP_REVALIDATE | |
Jeff Layton | ecf3d1f | 2013-02-20 11:19:05 -0500 | [diff] [blame] | 1678 | DCACHE_OP_WEAK_REVALIDATE | |
David Howells | 4bacc9c | 2015-06-18 14:32:31 +0100 | [diff] [blame] | 1679 | DCACHE_OP_DELETE | |
| 1680 | DCACHE_OP_SELECT_INODE)); |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1681 | dentry->d_op = op; |
| 1682 | if (!op) |
| 1683 | return; |
| 1684 | if (op->d_hash) |
| 1685 | dentry->d_flags |= DCACHE_OP_HASH; |
| 1686 | if (op->d_compare) |
| 1687 | dentry->d_flags |= DCACHE_OP_COMPARE; |
| 1688 | if (op->d_revalidate) |
| 1689 | dentry->d_flags |= DCACHE_OP_REVALIDATE; |
Jeff Layton | ecf3d1f | 2013-02-20 11:19:05 -0500 | [diff] [blame] | 1690 | if (op->d_weak_revalidate) |
| 1691 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1692 | if (op->d_delete) |
| 1693 | dentry->d_flags |= DCACHE_OP_DELETE; |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 1694 | if (op->d_prune) |
| 1695 | dentry->d_flags |= DCACHE_OP_PRUNE; |
David Howells | 4bacc9c | 2015-06-18 14:32:31 +0100 | [diff] [blame] | 1696 | if (op->d_select_inode) |
| 1697 | dentry->d_flags |= DCACHE_OP_SELECT_INODE; |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1698 | |
| 1699 | } |
| 1700 | EXPORT_SYMBOL(d_set_d_op); |
| 1701 | |
David Howells | df1a085 | 2015-01-29 12:02:28 +0000 | [diff] [blame] | 1702 | |
| 1703 | /* |
| 1704 | * d_set_fallthru - Mark a dentry as falling through to a lower layer |
| 1705 | * @dentry - The dentry to mark |
| 1706 | * |
| 1707 | * Mark a dentry as falling through to the lower layer (as set with |
| 1708 | * d_pin_lower()). This flag may be recorded on the medium. |
| 1709 | */ |
| 1710 | void d_set_fallthru(struct dentry *dentry) |
| 1711 | { |
| 1712 | spin_lock(&dentry->d_lock); |
| 1713 | dentry->d_flags |= DCACHE_FALLTHRU; |
| 1714 | spin_unlock(&dentry->d_lock); |
| 1715 | } |
| 1716 | EXPORT_SYMBOL(d_set_fallthru); |
| 1717 | |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1718 | static unsigned d_flags_for_inode(struct inode *inode) |
| 1719 | { |
David Howells | 44bdb5e | 2015-01-29 12:02:29 +0000 | [diff] [blame] | 1720 | unsigned add_flags = DCACHE_REGULAR_TYPE; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1721 | |
| 1722 | if (!inode) |
| 1723 | return DCACHE_MISS_TYPE; |
| 1724 | |
| 1725 | if (S_ISDIR(inode->i_mode)) { |
| 1726 | add_flags = DCACHE_DIRECTORY_TYPE; |
| 1727 | if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { |
| 1728 | if (unlikely(!inode->i_op->lookup)) |
| 1729 | add_flags = DCACHE_AUTODIR_TYPE; |
| 1730 | else |
| 1731 | inode->i_opflags |= IOP_LOOKUP; |
| 1732 | } |
David Howells | 44bdb5e | 2015-01-29 12:02:29 +0000 | [diff] [blame] | 1733 | goto type_determined; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1734 | } |
| 1735 | |
David Howells | 44bdb5e | 2015-01-29 12:02:29 +0000 | [diff] [blame] | 1736 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 1737 | if (unlikely(inode->i_op->get_link)) { |
David Howells | 44bdb5e | 2015-01-29 12:02:29 +0000 | [diff] [blame] | 1738 | add_flags = DCACHE_SYMLINK_TYPE; |
| 1739 | goto type_determined; |
| 1740 | } |
| 1741 | inode->i_opflags |= IOP_NOFOLLOW; |
| 1742 | } |
| 1743 | |
| 1744 | if (unlikely(!S_ISREG(inode->i_mode))) |
| 1745 | add_flags = DCACHE_SPECIAL_TYPE; |
| 1746 | |
| 1747 | type_determined: |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1748 | if (unlikely(IS_AUTOMOUNT(inode))) |
| 1749 | add_flags |= DCACHE_NEED_AUTOMOUNT; |
| 1750 | return add_flags; |
| 1751 | } |
| 1752 | |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1753 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
| 1754 | { |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1755 | unsigned add_flags = d_flags_for_inode(inode); |
| 1756 | |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 1757 | spin_lock(&dentry->d_lock); |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1758 | if (inode) |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1759 | hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); |
David Howells | 4bf46a2 | 2015-03-05 14:09:22 +0000 | [diff] [blame] | 1760 | __d_set_inode_and_type(dentry, inode, add_flags); |
Peter Zijlstra | a7c6f57 | 2015-06-11 14:46:46 +0200 | [diff] [blame] | 1761 | dentry_rcuwalk_invalidate(dentry); |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 1762 | spin_unlock(&dentry->d_lock); |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1763 | fsnotify_d_instantiate(dentry, inode); |
| 1764 | } |
| 1765 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1766 | /** |
| 1767 | * d_instantiate - fill in inode information for a dentry |
| 1768 | * @entry: dentry to complete |
| 1769 | * @inode: inode to attach to this dentry |
| 1770 | * |
| 1771 | * Fill in inode information in the entry. |
| 1772 | * |
| 1773 | * This turns negative dentries into productive full members |
| 1774 | * of society. |
| 1775 | * |
| 1776 | * NOTE! This assumes that the inode count has been incremented |
| 1777 | * (or otherwise set) by the caller to indicate that it is now |
| 1778 | * in use by the dcache. |
| 1779 | */ |
| 1780 | |
| 1781 | void d_instantiate(struct dentry *entry, struct inode * inode) |
| 1782 | { |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1783 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1784 | if (inode) |
| 1785 | spin_lock(&inode->i_lock); |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1786 | __d_instantiate(entry, inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1787 | if (inode) |
| 1788 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1789 | security_d_instantiate(entry, inode); |
| 1790 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1791 | EXPORT_SYMBOL(d_instantiate); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1792 | |
| 1793 | /** |
| 1794 | * d_instantiate_unique - instantiate a non-aliased dentry |
| 1795 | * @entry: dentry to instantiate |
| 1796 | * @inode: inode to attach to this dentry |
| 1797 | * |
| 1798 | * Fill in inode information in the entry. On success, it returns NULL. |
| 1799 | * If an unhashed alias of "entry" already exists, then we return the |
Oleg Drokin | e866cfa | 2006-01-09 20:52:51 -0800 | [diff] [blame] | 1800 | * aliased dentry instead and drop one reference to inode. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1801 | * |
| 1802 | * Note that in order to avoid conflicts with rename() etc, the caller |
| 1803 | * had better be holding the parent directory semaphore. |
Oleg Drokin | e866cfa | 2006-01-09 20:52:51 -0800 | [diff] [blame] | 1804 | * |
| 1805 | * This also assumes that the inode count has been incremented |
| 1806 | * (or otherwise set) by the caller to indicate that it is now |
| 1807 | * in use by the dcache. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1808 | */ |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1809 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
| 1810 | struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1811 | { |
| 1812 | struct dentry *alias; |
| 1813 | int len = entry->d_name.len; |
| 1814 | const char *name = entry->d_name.name; |
| 1815 | unsigned int hash = entry->d_name.hash; |
| 1816 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1817 | if (!inode) { |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1818 | __d_instantiate(entry, NULL); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1819 | return NULL; |
| 1820 | } |
| 1821 | |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1822 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
Nick Piggin | 9abca36 | 2011-01-07 17:49:36 +1100 | [diff] [blame] | 1823 | /* |
| 1824 | * Don't need alias->d_lock here, because aliases with |
| 1825 | * d_parent == entry->d_parent are not subject to name or |
| 1826 | * parent changes, because the parent inode i_mutex is held. |
| 1827 | */ |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 1828 | if (alias->d_name.hash != hash) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1829 | continue; |
| 1830 | if (alias->d_parent != entry->d_parent) |
| 1831 | continue; |
Linus Torvalds | ee983e8 | 2012-05-10 12:37:10 -0700 | [diff] [blame] | 1832 | if (alias->d_name.len != len) |
| 1833 | continue; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 1834 | if (dentry_cmp(alias, name, len)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1835 | continue; |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 1836 | __dget(alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1837 | return alias; |
| 1838 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1839 | |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1840 | __d_instantiate(entry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1841 | return NULL; |
| 1842 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1843 | |
| 1844 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
| 1845 | { |
| 1846 | struct dentry *result; |
| 1847 | |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1848 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1849 | |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1850 | if (inode) |
| 1851 | spin_lock(&inode->i_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1852 | result = __d_instantiate_unique(entry, inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1853 | if (inode) |
| 1854 | spin_unlock(&inode->i_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1855 | |
| 1856 | if (!result) { |
| 1857 | security_d_instantiate(entry, inode); |
| 1858 | return NULL; |
| 1859 | } |
| 1860 | |
| 1861 | BUG_ON(!d_unhashed(result)); |
| 1862 | iput(inode); |
| 1863 | return result; |
| 1864 | } |
| 1865 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1866 | EXPORT_SYMBOL(d_instantiate_unique); |
| 1867 | |
Miklos Szeredi | b70a80e | 2013-10-01 16:44:54 +0200 | [diff] [blame] | 1868 | /** |
| 1869 | * d_instantiate_no_diralias - instantiate a non-aliased dentry |
| 1870 | * @entry: dentry to complete |
| 1871 | * @inode: inode to attach to this dentry |
| 1872 | * |
| 1873 | * Fill in inode information in the entry. If a directory alias is found, then |
| 1874 | * return an error (and drop inode). Together with d_materialise_unique() this |
| 1875 | * guarantees that a directory inode may never have more than one alias. |
| 1876 | */ |
| 1877 | int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) |
| 1878 | { |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1879 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
Miklos Szeredi | b70a80e | 2013-10-01 16:44:54 +0200 | [diff] [blame] | 1880 | |
| 1881 | spin_lock(&inode->i_lock); |
| 1882 | if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { |
| 1883 | spin_unlock(&inode->i_lock); |
| 1884 | iput(inode); |
| 1885 | return -EBUSY; |
| 1886 | } |
| 1887 | __d_instantiate(entry, inode); |
| 1888 | spin_unlock(&inode->i_lock); |
| 1889 | security_d_instantiate(entry, inode); |
| 1890 | |
| 1891 | return 0; |
| 1892 | } |
| 1893 | EXPORT_SYMBOL(d_instantiate_no_diralias); |
| 1894 | |
Al Viro | adc0e91 | 2012-01-08 16:49:21 -0500 | [diff] [blame] | 1895 | struct dentry *d_make_root(struct inode *root_inode) |
| 1896 | { |
| 1897 | struct dentry *res = NULL; |
| 1898 | |
| 1899 | if (root_inode) { |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 1900 | static const struct qstr name = QSTR_INIT("/", 1); |
Al Viro | adc0e91 | 2012-01-08 16:49:21 -0500 | [diff] [blame] | 1901 | |
| 1902 | res = __d_alloc(root_inode->i_sb, &name); |
| 1903 | if (res) |
| 1904 | d_instantiate(res, root_inode); |
| 1905 | else |
| 1906 | iput(root_inode); |
| 1907 | } |
| 1908 | return res; |
| 1909 | } |
| 1910 | EXPORT_SYMBOL(d_make_root); |
| 1911 | |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1912 | static struct dentry * __d_find_any_alias(struct inode *inode) |
| 1913 | { |
| 1914 | struct dentry *alias; |
| 1915 | |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1916 | if (hlist_empty(&inode->i_dentry)) |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1917 | return NULL; |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1918 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1919 | __dget(alias); |
| 1920 | return alias; |
| 1921 | } |
| 1922 | |
Sage Weil | 46f72b3 | 2012-01-10 09:04:37 -0800 | [diff] [blame] | 1923 | /** |
| 1924 | * d_find_any_alias - find any alias for a given inode |
| 1925 | * @inode: inode to find an alias for |
| 1926 | * |
| 1927 | * If any aliases exist for the given inode, take and return a |
| 1928 | * reference for one of them. If no aliases exist, return %NULL. |
| 1929 | */ |
| 1930 | struct dentry *d_find_any_alias(struct inode *inode) |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1931 | { |
| 1932 | struct dentry *de; |
| 1933 | |
| 1934 | spin_lock(&inode->i_lock); |
| 1935 | de = __d_find_any_alias(inode); |
| 1936 | spin_unlock(&inode->i_lock); |
| 1937 | return de; |
| 1938 | } |
Sage Weil | 46f72b3 | 2012-01-10 09:04:37 -0800 | [diff] [blame] | 1939 | EXPORT_SYMBOL(d_find_any_alias); |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1940 | |
Fengguang Wu | 49c7dd2 | 2014-07-31 17:59:02 -0400 | [diff] [blame] | 1941 | static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1942 | { |
NeilBrown | b911a6b | 2012-11-08 16:09:37 -0800 | [diff] [blame] | 1943 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1944 | struct dentry *tmp; |
| 1945 | struct dentry *res; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1946 | unsigned add_flags; |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1947 | |
| 1948 | if (!inode) |
Christoph Hellwig | 4400372 | 2008-08-11 15:49:04 +0200 | [diff] [blame] | 1949 | return ERR_PTR(-ESTALE); |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1950 | if (IS_ERR(inode)) |
| 1951 | return ERR_CAST(inode); |
| 1952 | |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1953 | res = d_find_any_alias(inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1954 | if (res) |
| 1955 | goto out_iput; |
| 1956 | |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1957 | tmp = __d_alloc(inode->i_sb, &anonstring); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1958 | if (!tmp) { |
| 1959 | res = ERR_PTR(-ENOMEM); |
| 1960 | goto out_iput; |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1961 | } |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 1962 | |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1963 | spin_lock(&inode->i_lock); |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1964 | res = __d_find_any_alias(inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1965 | if (res) { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1966 | spin_unlock(&inode->i_lock); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1967 | dput(tmp); |
| 1968 | goto out_iput; |
| 1969 | } |
| 1970 | |
| 1971 | /* attach a disconnected dentry */ |
J. Bruce Fields | 1a0a397 | 2014-02-14 17:35:37 -0500 | [diff] [blame] | 1972 | add_flags = d_flags_for_inode(inode); |
| 1973 | |
| 1974 | if (disconnected) |
| 1975 | add_flags |= DCACHE_DISCONNECTED; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 1976 | |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1977 | spin_lock(&tmp->d_lock); |
David Howells | 4bf46a2 | 2015-03-05 14:09:22 +0000 | [diff] [blame] | 1978 | __d_set_inode_and_type(tmp, inode, add_flags); |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 1979 | hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 1980 | hlist_bl_lock(&tmp->d_sb->s_anon); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 1981 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 1982 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1983 | spin_unlock(&tmp->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1984 | spin_unlock(&inode->i_lock); |
Josef Bacik | 24ff666 | 2010-11-18 20:52:55 -0500 | [diff] [blame] | 1985 | security_d_instantiate(tmp, inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1986 | |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1987 | return tmp; |
| 1988 | |
| 1989 | out_iput: |
Josef Bacik | 24ff666 | 2010-11-18 20:52:55 -0500 | [diff] [blame] | 1990 | if (res && !IS_ERR(res)) |
| 1991 | security_d_instantiate(res, inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1992 | iput(inode); |
| 1993 | return res; |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1994 | } |
J. Bruce Fields | 1a0a397 | 2014-02-14 17:35:37 -0500 | [diff] [blame] | 1995 | |
| 1996 | /** |
| 1997 | * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode |
| 1998 | * @inode: inode to allocate the dentry for |
| 1999 | * |
| 2000 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
| 2001 | * similar open by handle operations. The returned dentry may be anonymous, |
| 2002 | * or may have a full name (if the inode was already in the cache). |
| 2003 | * |
| 2004 | * When called on a directory inode, we must ensure that the inode only ever |
| 2005 | * has one dentry. If a dentry is found, that is returned instead of |
| 2006 | * allocating a new one. |
| 2007 | * |
| 2008 | * On successful return, the reference to the inode has been transferred |
| 2009 | * to the dentry. In case of an error the reference on the inode is released. |
| 2010 | * To make it easier to use in export operations a %NULL or IS_ERR inode may |
| 2011 | * be passed in and the error will be propagated to the return value, |
| 2012 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
| 2013 | */ |
| 2014 | struct dentry *d_obtain_alias(struct inode *inode) |
| 2015 | { |
| 2016 | return __d_obtain_alias(inode, 1); |
| 2017 | } |
Benny Halevy | adc4872 | 2009-02-27 14:02:59 -0800 | [diff] [blame] | 2018 | EXPORT_SYMBOL(d_obtain_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2019 | |
| 2020 | /** |
J. Bruce Fields | 1a0a397 | 2014-02-14 17:35:37 -0500 | [diff] [blame] | 2021 | * d_obtain_root - find or allocate a dentry for a given inode |
| 2022 | * @inode: inode to allocate the dentry for |
| 2023 | * |
| 2024 | * Obtain an IS_ROOT dentry for the root of a filesystem. |
| 2025 | * |
| 2026 | * We must ensure that directory inodes only ever have one dentry. If a |
| 2027 | * dentry is found, that is returned instead of allocating a new one. |
| 2028 | * |
| 2029 | * On successful return, the reference to the inode has been transferred |
| 2030 | * to the dentry. In case of an error the reference on the inode is |
| 2031 | * released. A %NULL or IS_ERR inode may be passed in and will be the |
| 2032 | * error will be propagate to the return value, with a %NULL @inode |
| 2033 | * replaced by ERR_PTR(-ESTALE). |
| 2034 | */ |
| 2035 | struct dentry *d_obtain_root(struct inode *inode) |
| 2036 | { |
| 2037 | return __d_obtain_alias(inode, 0); |
| 2038 | } |
| 2039 | EXPORT_SYMBOL(d_obtain_root); |
| 2040 | |
| 2041 | /** |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2042 | * d_add_ci - lookup or allocate new dentry with case-exact name |
| 2043 | * @inode: the inode case-insensitive lookup has found |
| 2044 | * @dentry: the negative dentry that was passed to the parent's lookup func |
| 2045 | * @name: the case-exact name to be associated with the returned dentry |
| 2046 | * |
| 2047 | * This is to avoid filling the dcache with case-insensitive names to the |
| 2048 | * same inode, only the actual correct case is stored in the dcache for |
| 2049 | * case-insensitive filesystems. |
| 2050 | * |
| 2051 | * For a case-insensitive lookup match and if the the case-exact dentry |
| 2052 | * already exists in in the dcache, use it and return it. |
| 2053 | * |
| 2054 | * If no entry exists with the exact case name, allocate new dentry with |
| 2055 | * the exact case, and return the spliced entry. |
| 2056 | */ |
Christoph Hellwig | e45b590 | 2008-08-07 23:49:07 +0200 | [diff] [blame] | 2057 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2058 | struct qstr *name) |
| 2059 | { |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2060 | struct dentry *found; |
| 2061 | struct dentry *new; |
| 2062 | |
Christoph Hellwig | b6520c8 | 2009-01-05 19:10:37 +0100 | [diff] [blame] | 2063 | /* |
| 2064 | * First check if a dentry matching the name already exists, |
| 2065 | * if not go ahead and create it now. |
| 2066 | */ |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2067 | found = d_hash_and_lookup(dentry->d_parent, name); |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2068 | if (!found) { |
| 2069 | new = d_alloc(dentry->d_parent, name); |
| 2070 | if (!new) { |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2071 | found = ERR_PTR(-ENOMEM); |
Al Viro | 427c77d | 2014-10-12 18:46:26 -0400 | [diff] [blame] | 2072 | } else { |
| 2073 | found = d_splice_alias(inode, new); |
| 2074 | if (found) { |
| 2075 | dput(new); |
| 2076 | return found; |
| 2077 | } |
| 2078 | return new; |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2079 | } |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2080 | } |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2081 | iput(inode); |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2082 | return found; |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2083 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2084 | EXPORT_SYMBOL(d_add_ci); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2085 | |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2086 | /* |
| 2087 | * Do the slow-case of the dentry name compare. |
| 2088 | * |
| 2089 | * Unlike the dentry_cmp() function, we need to atomically |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2090 | * load the name and length information, so that the |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2091 | * filesystem can rely on them, and can use the 'name' and |
| 2092 | * 'len' information without worrying about walking off the |
| 2093 | * end of memory etc. |
| 2094 | * |
| 2095 | * Thus the read_seqcount_retry() and the "duplicate" info |
| 2096 | * in arguments (the low-level filesystem should not look |
| 2097 | * at the dentry inode or name contents directly, since |
| 2098 | * rename can change them while we're in RCU mode). |
| 2099 | */ |
| 2100 | enum slow_d_compare { |
| 2101 | D_COMP_OK, |
| 2102 | D_COMP_NOMATCH, |
| 2103 | D_COMP_SEQRETRY, |
| 2104 | }; |
| 2105 | |
| 2106 | static noinline enum slow_d_compare slow_dentry_cmp( |
| 2107 | const struct dentry *parent, |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2108 | struct dentry *dentry, |
| 2109 | unsigned int seq, |
| 2110 | const struct qstr *name) |
| 2111 | { |
| 2112 | int tlen = dentry->d_name.len; |
| 2113 | const char *tname = dentry->d_name.name; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2114 | |
| 2115 | if (read_seqcount_retry(&dentry->d_seq, seq)) { |
| 2116 | cpu_relax(); |
| 2117 | return D_COMP_SEQRETRY; |
| 2118 | } |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2119 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2120 | return D_COMP_NOMATCH; |
| 2121 | return D_COMP_OK; |
| 2122 | } |
| 2123 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2124 | /** |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2125 | * __d_lookup_rcu - search for a dentry (racy, store-free) |
| 2126 | * @parent: parent dentry |
| 2127 | * @name: qstr of name we wish to find |
Randy Dunlap | 1f1e6e5 | 2012-03-18 21:23:05 -0700 | [diff] [blame] | 2128 | * @seqp: returns d_seq value at the point where the dentry was found |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2129 | * Returns: dentry, or NULL |
| 2130 | * |
| 2131 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name |
| 2132 | * resolution (store-free path walking) design described in |
| 2133 | * Documentation/filesystems/path-lookup.txt. |
| 2134 | * |
| 2135 | * This is not to be used outside core vfs. |
| 2136 | * |
| 2137 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock |
| 2138 | * held, and rcu_read_lock held. The returned dentry must not be stored into |
| 2139 | * without taking d_lock and checking d_seq sequence count against @seq |
| 2140 | * returned here. |
| 2141 | * |
Linus Torvalds | 1557008 | 2013-09-02 11:38:06 -0700 | [diff] [blame] | 2142 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2143 | * function. |
| 2144 | * |
| 2145 | * Alternatively, __d_lookup_rcu may be called again to look up the child of |
| 2146 | * the returned dentry, so long as its parent's seqlock is checked after the |
| 2147 | * child is looked up. Thus, an interlocking stepping of sequence lock checks |
| 2148 | * is formed, giving integrity down the path walk. |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2149 | * |
| 2150 | * NOTE! The caller *has* to check the resulting dentry against the sequence |
| 2151 | * number we've returned before using any of the resulting dentry state! |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2152 | */ |
Linus Torvalds | 8966be9 | 2012-03-02 14:23:30 -0800 | [diff] [blame] | 2153 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
| 2154 | const struct qstr *name, |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2155 | unsigned *seqp) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2156 | { |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2157 | u64 hashlen = name->hash_len; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2158 | const unsigned char *str = name->name; |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2159 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2160 | struct hlist_bl_node *node; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2161 | struct dentry *dentry; |
| 2162 | |
| 2163 | /* |
| 2164 | * Note: There is significant duplication with __d_lookup_rcu which is |
| 2165 | * required to prevent single threaded performance regressions |
| 2166 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
| 2167 | * Keep the two functions in sync. |
| 2168 | */ |
| 2169 | |
| 2170 | /* |
| 2171 | * The hash list is protected using RCU. |
| 2172 | * |
| 2173 | * Carefully use d_seq when comparing a candidate dentry, to avoid |
| 2174 | * races with d_move(). |
| 2175 | * |
| 2176 | * It is possible that concurrent renames can mess up our list |
| 2177 | * walk here and result in missing our dentry, resulting in the |
| 2178 | * false-negative result. d_lookup() protects against concurrent |
| 2179 | * renames using rename_lock seqlock. |
| 2180 | * |
Namhyung Kim | b0a4bb8 | 2011-01-22 15:31:32 +0900 | [diff] [blame] | 2181 | * See Documentation/filesystems/path-lookup.txt for more details. |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2182 | */ |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2183 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
Linus Torvalds | 8966be9 | 2012-03-02 14:23:30 -0800 | [diff] [blame] | 2184 | unsigned seq; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2185 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2186 | seqretry: |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2187 | /* |
| 2188 | * The dentry sequence count protects us from concurrent |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2189 | * renames, and thus protects parent and name fields. |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2190 | * |
| 2191 | * The caller must perform a seqcount check in order |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2192 | * to do anything useful with the returned dentry. |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2193 | * |
| 2194 | * NOTE! We do a "raw" seqcount_begin here. That means that |
| 2195 | * we don't wait for the sequence count to stabilize if it |
| 2196 | * is in the middle of a sequence change. If we do the slow |
| 2197 | * dentry compare, we will do seqretries until it is stable, |
| 2198 | * and if we end up with a successful lookup, we actually |
| 2199 | * want to exit RCU lookup anyway. |
| 2200 | */ |
| 2201 | seq = raw_seqcount_begin(&dentry->d_seq); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2202 | if (dentry->d_parent != parent) |
| 2203 | continue; |
Linus Torvalds | 2e32180 | 2012-05-21 18:48:10 -0700 | [diff] [blame] | 2204 | if (d_unhashed(dentry)) |
| 2205 | continue; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2206 | |
| 2207 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2208 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
| 2209 | continue; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2210 | *seqp = seq; |
| 2211 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2212 | case D_COMP_OK: |
| 2213 | return dentry; |
| 2214 | case D_COMP_NOMATCH: |
| 2215 | continue; |
| 2216 | default: |
| 2217 | goto seqretry; |
| 2218 | } |
| 2219 | } |
| 2220 | |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2221 | if (dentry->d_name.hash_len != hashlen) |
Linus Torvalds | ee983e8 | 2012-05-10 12:37:10 -0700 | [diff] [blame] | 2222 | continue; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2223 | *seqp = seq; |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2224 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2225 | return dentry; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2226 | } |
| 2227 | return NULL; |
| 2228 | } |
| 2229 | |
| 2230 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2231 | * d_lookup - search for a dentry |
| 2232 | * @parent: parent dentry |
| 2233 | * @name: qstr of name we wish to find |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2234 | * Returns: dentry, or NULL |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2235 | * |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2236 | * d_lookup searches the children of the parent dentry for the name in |
| 2237 | * question. If the dentry is found its reference count is incremented and the |
| 2238 | * dentry is returned. The caller must use dput to free the entry when it has |
| 2239 | * finished using it. %NULL is returned if the dentry does not exist. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2240 | */ |
Al Viro | da2d845 | 2013-01-24 18:29:34 -0500 | [diff] [blame] | 2241 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2242 | { |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2243 | struct dentry *dentry; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 2244 | unsigned seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2245 | |
Daeseok Youn | b8314f9 | 2014-08-11 11:46:53 +0900 | [diff] [blame] | 2246 | do { |
| 2247 | seq = read_seqbegin(&rename_lock); |
| 2248 | dentry = __d_lookup(parent, name); |
| 2249 | if (dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2250 | break; |
| 2251 | } while (read_seqretry(&rename_lock, seq)); |
| 2252 | return dentry; |
| 2253 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2254 | EXPORT_SYMBOL(d_lookup); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2255 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2256 | /** |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2257 | * __d_lookup - search for a dentry (racy) |
| 2258 | * @parent: parent dentry |
| 2259 | * @name: qstr of name we wish to find |
| 2260 | * Returns: dentry, or NULL |
| 2261 | * |
| 2262 | * __d_lookup is like d_lookup, however it may (rarely) return a |
| 2263 | * false-negative result due to unrelated rename activity. |
| 2264 | * |
| 2265 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
| 2266 | * however it must be used carefully, eg. with a following d_lookup in |
| 2267 | * the case of failure. |
| 2268 | * |
| 2269 | * __d_lookup callers must be commented. |
| 2270 | */ |
Al Viro | a713ca2 | 2013-01-24 18:27:00 -0500 | [diff] [blame] | 2271 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2272 | { |
| 2273 | unsigned int len = name->len; |
| 2274 | unsigned int hash = name->hash; |
| 2275 | const unsigned char *str = name->name; |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2276 | struct hlist_bl_head *b = d_hash(parent, hash); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2277 | struct hlist_bl_node *node; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2278 | struct dentry *found = NULL; |
Paul E. McKenney | 665a758 | 2005-11-07 00:59:17 -0800 | [diff] [blame] | 2279 | struct dentry *dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2280 | |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2281 | /* |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2282 | * Note: There is significant duplication with __d_lookup_rcu which is |
| 2283 | * required to prevent single threaded performance regressions |
| 2284 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
| 2285 | * Keep the two functions in sync. |
| 2286 | */ |
| 2287 | |
| 2288 | /* |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2289 | * The hash list is protected using RCU. |
| 2290 | * |
| 2291 | * Take d_lock when comparing a candidate dentry, to avoid races |
| 2292 | * with d_move(). |
| 2293 | * |
| 2294 | * It is possible that concurrent renames can mess up our list |
| 2295 | * walk here and result in missing our dentry, resulting in the |
| 2296 | * false-negative result. d_lookup() protects against concurrent |
| 2297 | * renames using rename_lock seqlock. |
| 2298 | * |
Namhyung Kim | b0a4bb8 | 2011-01-22 15:31:32 +0900 | [diff] [blame] | 2299 | * See Documentation/filesystems/path-lookup.txt for more details. |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2300 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2301 | rcu_read_lock(); |
| 2302 | |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2303 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2304 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2305 | if (dentry->d_name.hash != hash) |
| 2306 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2307 | |
| 2308 | spin_lock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2309 | if (dentry->d_parent != parent) |
| 2310 | goto next; |
Linus Torvalds | d0185c0 | 2008-09-29 07:42:57 -0700 | [diff] [blame] | 2311 | if (d_unhashed(dentry)) |
| 2312 | goto next; |
| 2313 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2314 | /* |
| 2315 | * It is safe to compare names since d_move() cannot |
| 2316 | * change the qstr (protected by d_lock). |
| 2317 | */ |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 2318 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2319 | int tlen = dentry->d_name.len; |
| 2320 | const char *tname = dentry->d_name.name; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2321 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2322 | goto next; |
| 2323 | } else { |
Linus Torvalds | ee983e8 | 2012-05-10 12:37:10 -0700 | [diff] [blame] | 2324 | if (dentry->d_name.len != len) |
| 2325 | goto next; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2326 | if (dentry_cmp(dentry, str, len)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2327 | goto next; |
| 2328 | } |
| 2329 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 2330 | dentry->d_lockref.count++; |
Linus Torvalds | d0185c0 | 2008-09-29 07:42:57 -0700 | [diff] [blame] | 2331 | found = dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2332 | spin_unlock(&dentry->d_lock); |
| 2333 | break; |
| 2334 | next: |
| 2335 | spin_unlock(&dentry->d_lock); |
| 2336 | } |
| 2337 | rcu_read_unlock(); |
| 2338 | |
| 2339 | return found; |
| 2340 | } |
| 2341 | |
| 2342 | /** |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2343 | * d_hash_and_lookup - hash the qstr then search for a dentry |
| 2344 | * @dir: Directory to search in |
| 2345 | * @name: qstr of name we wish to find |
| 2346 | * |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2347 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2348 | */ |
| 2349 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
| 2350 | { |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2351 | /* |
| 2352 | * Check for a fs-specific hash function. Note that we must |
| 2353 | * calculate the standard hash first, as the d_op->d_hash() |
| 2354 | * routine may choose to leave the hash value unchanged. |
| 2355 | */ |
| 2356 | name->hash = full_name_hash(name->name, name->len); |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 2357 | if (dir->d_flags & DCACHE_OP_HASH) { |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2358 | int err = dir->d_op->d_hash(dir, name); |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2359 | if (unlikely(err < 0)) |
| 2360 | return ERR_PTR(err); |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2361 | } |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2362 | return d_lookup(dir, name); |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2363 | } |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2364 | EXPORT_SYMBOL(d_hash_and_lookup); |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2365 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2366 | /* |
| 2367 | * When a file is deleted, we have two options: |
| 2368 | * - turn this dentry into a negative dentry |
| 2369 | * - unhash this dentry and free it. |
| 2370 | * |
| 2371 | * Usually, we want to just turn this into |
| 2372 | * a negative dentry, but if anybody else is |
| 2373 | * currently using the dentry or the inode |
| 2374 | * we can't do that and we fall back on removing |
| 2375 | * it from the hash queues and waiting for |
| 2376 | * it to be deleted later when it has no users |
| 2377 | */ |
| 2378 | |
| 2379 | /** |
| 2380 | * d_delete - delete a dentry |
| 2381 | * @dentry: The dentry to delete |
| 2382 | * |
| 2383 | * Turn the dentry into a negative dentry if possible, otherwise |
| 2384 | * remove it from the hash queues so it can be deleted later |
| 2385 | */ |
| 2386 | |
| 2387 | void d_delete(struct dentry * dentry) |
| 2388 | { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2389 | struct inode *inode; |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 2390 | int isdir = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2391 | /* |
| 2392 | * Are we the only user? |
| 2393 | */ |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2394 | again: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2395 | spin_lock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2396 | inode = dentry->d_inode; |
| 2397 | isdir = S_ISDIR(inode->i_mode); |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 2398 | if (dentry->d_lockref.count == 1) { |
Alan Cox | 1fe0c02 | 2012-09-19 15:49:51 +0100 | [diff] [blame] | 2399 | if (!spin_trylock(&inode->i_lock)) { |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2400 | spin_unlock(&dentry->d_lock); |
| 2401 | cpu_relax(); |
| 2402 | goto again; |
| 2403 | } |
Al Viro | 13e3c5e | 2010-05-21 16:11:04 -0400 | [diff] [blame] | 2404 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2405 | dentry_unlink_inode(dentry); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 2406 | fsnotify_nameremove(dentry, isdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2407 | return; |
| 2408 | } |
| 2409 | |
| 2410 | if (!d_unhashed(dentry)) |
| 2411 | __d_drop(dentry); |
| 2412 | |
| 2413 | spin_unlock(&dentry->d_lock); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 2414 | |
| 2415 | fsnotify_nameremove(dentry, isdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2416 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2417 | EXPORT_SYMBOL(d_delete); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2418 | |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2419 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2420 | { |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2421 | BUG_ON(!d_unhashed(entry)); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 2422 | hlist_bl_lock(b); |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 2423 | entry->d_flags |= DCACHE_RCUACCESS; |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2424 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 2425 | hlist_bl_unlock(b); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2426 | } |
| 2427 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2428 | static void _d_rehash(struct dentry * entry) |
| 2429 | { |
| 2430 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
| 2431 | } |
| 2432 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2433 | /** |
| 2434 | * d_rehash - add an entry back to the hash |
| 2435 | * @entry: dentry to add to the hash |
| 2436 | * |
| 2437 | * Adds a dentry to the hash according to its name. |
| 2438 | */ |
| 2439 | |
| 2440 | void d_rehash(struct dentry * entry) |
| 2441 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2442 | spin_lock(&entry->d_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2443 | _d_rehash(entry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2444 | spin_unlock(&entry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2445 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2446 | EXPORT_SYMBOL(d_rehash); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2447 | |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2448 | /** |
| 2449 | * dentry_update_name_case - update case insensitive dentry with a new name |
| 2450 | * @dentry: dentry to be updated |
| 2451 | * @name: new name |
| 2452 | * |
| 2453 | * Update a case insensitive dentry with new case of name. |
| 2454 | * |
| 2455 | * dentry must have been returned by d_lookup with name @name. Old and new |
| 2456 | * name lengths must match (ie. no d_compare which allows mismatched name |
| 2457 | * lengths). |
| 2458 | * |
| 2459 | * Parent inode i_mutex must be held over d_lookup and into this call (to |
| 2460 | * keep renames and concurrent inserts, and readdir(2) away). |
| 2461 | */ |
| 2462 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
| 2463 | { |
Linus Torvalds | 7ebfa57 | 2011-04-15 07:34:26 -0700 | [diff] [blame] | 2464 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2465 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
| 2466 | |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2467 | spin_lock(&dentry->d_lock); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2468 | write_seqcount_begin(&dentry->d_seq); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2469 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2470 | write_seqcount_end(&dentry->d_seq); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2471 | spin_unlock(&dentry->d_lock); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2472 | } |
| 2473 | EXPORT_SYMBOL(dentry_update_name_case); |
| 2474 | |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 2475 | static void swap_names(struct dentry *dentry, struct dentry *target) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2476 | { |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 2477 | if (unlikely(dname_external(target))) { |
| 2478 | if (unlikely(dname_external(dentry))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2479 | /* |
| 2480 | * Both external: swap the pointers |
| 2481 | */ |
Wu Fengguang | 9a8d5bb | 2009-01-07 18:09:14 -0800 | [diff] [blame] | 2482 | swap(target->d_name.name, dentry->d_name.name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2483 | } else { |
| 2484 | /* |
| 2485 | * dentry:internal, target:external. Steal target's |
| 2486 | * storage and make target internal. |
| 2487 | */ |
J. Bruce Fields | 321bcf9 | 2007-10-21 16:41:38 -0700 | [diff] [blame] | 2488 | memcpy(target->d_iname, dentry->d_name.name, |
| 2489 | dentry->d_name.len + 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2490 | dentry->d_name.name = target->d_name.name; |
| 2491 | target->d_name.name = target->d_iname; |
| 2492 | } |
| 2493 | } else { |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 2494 | if (unlikely(dname_external(dentry))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2495 | /* |
| 2496 | * dentry:external, target:internal. Give dentry's |
| 2497 | * storage to target and make dentry internal |
| 2498 | */ |
| 2499 | memcpy(dentry->d_iname, target->d_name.name, |
| 2500 | target->d_name.len + 1); |
| 2501 | target->d_name.name = dentry->d_name.name; |
| 2502 | dentry->d_name.name = dentry->d_iname; |
| 2503 | } else { |
| 2504 | /* |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2505 | * Both are internal. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2506 | */ |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2507 | unsigned int i; |
| 2508 | BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); |
Mikulas Patocka | 08d4f77 | 2014-09-05 12:16:01 -0400 | [diff] [blame] | 2509 | kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN); |
| 2510 | kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN); |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2511 | for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { |
| 2512 | swap(((long *) &dentry->d_iname)[i], |
| 2513 | ((long *) &target->d_iname)[i]); |
| 2514 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2515 | } |
| 2516 | } |
Linus Torvalds | a28ddb8 | 2014-09-24 12:27:39 -0700 | [diff] [blame] | 2517 | swap(dentry->d_name.hash_len, target->d_name.hash_len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2518 | } |
| 2519 | |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 2520 | static void copy_name(struct dentry *dentry, struct dentry *target) |
| 2521 | { |
| 2522 | struct external_name *old_name = NULL; |
| 2523 | if (unlikely(dname_external(dentry))) |
| 2524 | old_name = external_name(dentry); |
| 2525 | if (unlikely(dname_external(target))) { |
| 2526 | atomic_inc(&external_name(target)->u.count); |
| 2527 | dentry->d_name = target->d_name; |
| 2528 | } else { |
| 2529 | memcpy(dentry->d_iname, target->d_name.name, |
| 2530 | target->d_name.len + 1); |
| 2531 | dentry->d_name.name = dentry->d_iname; |
| 2532 | dentry->d_name.hash_len = target->d_name.hash_len; |
| 2533 | } |
| 2534 | if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) |
| 2535 | kfree_rcu(old_name, u.head); |
| 2536 | } |
| 2537 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2538 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
| 2539 | { |
| 2540 | /* |
| 2541 | * XXXX: do we really need to take target->d_lock? |
| 2542 | */ |
| 2543 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) |
| 2544 | spin_lock(&target->d_parent->d_lock); |
| 2545 | else { |
| 2546 | if (d_ancestor(dentry->d_parent, target->d_parent)) { |
| 2547 | spin_lock(&dentry->d_parent->d_lock); |
| 2548 | spin_lock_nested(&target->d_parent->d_lock, |
| 2549 | DENTRY_D_LOCK_NESTED); |
| 2550 | } else { |
| 2551 | spin_lock(&target->d_parent->d_lock); |
| 2552 | spin_lock_nested(&dentry->d_parent->d_lock, |
| 2553 | DENTRY_D_LOCK_NESTED); |
| 2554 | } |
| 2555 | } |
| 2556 | if (target < dentry) { |
| 2557 | spin_lock_nested(&target->d_lock, 2); |
| 2558 | spin_lock_nested(&dentry->d_lock, 3); |
| 2559 | } else { |
| 2560 | spin_lock_nested(&dentry->d_lock, 2); |
| 2561 | spin_lock_nested(&target->d_lock, 3); |
| 2562 | } |
| 2563 | } |
| 2564 | |
Al Viro | 986c019 | 2014-09-26 23:11:15 -0400 | [diff] [blame] | 2565 | static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target) |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2566 | { |
| 2567 | if (target->d_parent != dentry->d_parent) |
| 2568 | spin_unlock(&dentry->d_parent->d_lock); |
| 2569 | if (target->d_parent != target) |
| 2570 | spin_unlock(&target->d_parent->d_lock); |
Al Viro | 986c019 | 2014-09-26 23:11:15 -0400 | [diff] [blame] | 2571 | spin_unlock(&target->d_lock); |
| 2572 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2573 | } |
| 2574 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2575 | /* |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2576 | * When switching names, the actual string doesn't strictly have to |
| 2577 | * be preserved in the target - because we're dropping the target |
| 2578 | * anyway. As such, we can just do a simple memcpy() to copy over |
Mikhail Efremov | d2fa4a8 | 2014-09-24 22:14:33 +0400 | [diff] [blame] | 2579 | * the new name before we switch, unless we are going to rehash |
| 2580 | * it. Note that if we *do* unhash the target, we are not allowed |
| 2581 | * to rehash it without giving it a new name/hash key - whether |
| 2582 | * we swap or overwrite the names here, resulting name won't match |
| 2583 | * the reality in filesystem; it's only there for d_path() purposes. |
| 2584 | * Note that all of this is happening under rename_lock, so the |
| 2585 | * any hash lookup seeing it in the middle of manipulations will |
| 2586 | * be discarded anyway. So we do not care what happens to the hash |
| 2587 | * key in that case. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2588 | */ |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2589 | /* |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2590 | * __d_move - move a dentry |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2591 | * @dentry: entry to move |
| 2592 | * @target: new dentry |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2593 | * @exchange: exchange the two dentries |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2594 | * |
| 2595 | * Update the dcache to reflect the move of a file name. Negative |
Jeff Layton | c46c887 | 2011-07-26 13:33:16 -0400 | [diff] [blame] | 2596 | * dcache entries should not be moved in this way. Caller must hold |
| 2597 | * rename_lock, the i_mutex of the source and target directories, |
| 2598 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2599 | */ |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2600 | static void __d_move(struct dentry *dentry, struct dentry *target, |
| 2601 | bool exchange) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2602 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2603 | if (!dentry->d_inode) |
| 2604 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
| 2605 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2606 | BUG_ON(d_ancestor(dentry, target)); |
| 2607 | BUG_ON(d_ancestor(target, dentry)); |
| 2608 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2609 | dentry_lock_for_move(dentry, target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2610 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2611 | write_seqcount_begin(&dentry->d_seq); |
John Stultz | 1ca7d67 | 2013-10-07 15:51:59 -0700 | [diff] [blame] | 2612 | write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2613 | |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2614 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
| 2615 | |
| 2616 | /* |
| 2617 | * Move the dentry to the target hash queue. Don't bother checking |
| 2618 | * for the same hash queue because of how unlikely it is. |
| 2619 | */ |
| 2620 | __d_drop(dentry); |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 2621 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2622 | |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2623 | /* |
| 2624 | * Unhash the target (d_delete() is not usable here). If exchanging |
| 2625 | * the two dentries, then rehash onto the other's hash queue. |
| 2626 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2627 | __d_drop(target); |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2628 | if (exchange) { |
| 2629 | __d_rehash(target, |
| 2630 | d_hash(dentry->d_parent, dentry->d_name.hash)); |
| 2631 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2632 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2633 | /* Switch the names.. */ |
Al Viro | 8d85b48 | 2014-09-29 14:54:27 -0400 | [diff] [blame] | 2634 | if (exchange) |
| 2635 | swap_names(dentry, target); |
| 2636 | else |
| 2637 | copy_name(dentry, target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2638 | |
Al Viro | 63cf427 | 2014-09-26 23:06:14 -0400 | [diff] [blame] | 2639 | /* ... and switch them in the tree */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2640 | if (IS_ROOT(dentry)) { |
Al Viro | 63cf427 | 2014-09-26 23:06:14 -0400 | [diff] [blame] | 2641 | /* splicing a tree */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2642 | dentry->d_parent = target->d_parent; |
| 2643 | target->d_parent = target; |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 2644 | list_del_init(&target->d_child); |
| 2645 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2646 | } else { |
Al Viro | 63cf427 | 2014-09-26 23:06:14 -0400 | [diff] [blame] | 2647 | /* swapping two dentries */ |
Wu Fengguang | 9a8d5bb | 2009-01-07 18:09:14 -0800 | [diff] [blame] | 2648 | swap(dentry->d_parent, target->d_parent); |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 2649 | list_move(&target->d_child, &target->d_parent->d_subdirs); |
| 2650 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); |
Al Viro | 63cf427 | 2014-09-26 23:06:14 -0400 | [diff] [blame] | 2651 | if (exchange) |
| 2652 | fsnotify_d_move(target); |
| 2653 | fsnotify_d_move(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2654 | } |
| 2655 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2656 | write_seqcount_end(&target->d_seq); |
| 2657 | write_seqcount_end(&dentry->d_seq); |
| 2658 | |
Al Viro | 986c019 | 2014-09-26 23:11:15 -0400 | [diff] [blame] | 2659 | dentry_unlock_for_move(dentry, target); |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2660 | } |
| 2661 | |
| 2662 | /* |
| 2663 | * d_move - move a dentry |
| 2664 | * @dentry: entry to move |
| 2665 | * @target: new dentry |
| 2666 | * |
| 2667 | * Update the dcache to reflect the move of a file name. Negative |
Jeff Layton | c46c887 | 2011-07-26 13:33:16 -0400 | [diff] [blame] | 2668 | * dcache entries should not be moved in this way. See the locking |
| 2669 | * requirements for __d_move. |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2670 | */ |
| 2671 | void d_move(struct dentry *dentry, struct dentry *target) |
| 2672 | { |
| 2673 | write_seqlock(&rename_lock); |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2674 | __d_move(dentry, target, false); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2675 | write_sequnlock(&rename_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2676 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2677 | EXPORT_SYMBOL(d_move); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2678 | |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 2679 | /* |
| 2680 | * d_exchange - exchange two dentries |
| 2681 | * @dentry1: first dentry |
| 2682 | * @dentry2: second dentry |
| 2683 | */ |
| 2684 | void d_exchange(struct dentry *dentry1, struct dentry *dentry2) |
| 2685 | { |
| 2686 | write_seqlock(&rename_lock); |
| 2687 | |
| 2688 | WARN_ON(!dentry1->d_inode); |
| 2689 | WARN_ON(!dentry2->d_inode); |
| 2690 | WARN_ON(IS_ROOT(dentry1)); |
| 2691 | WARN_ON(IS_ROOT(dentry2)); |
| 2692 | |
| 2693 | __d_move(dentry1, dentry2, true); |
| 2694 | |
| 2695 | write_sequnlock(&rename_lock); |
| 2696 | } |
| 2697 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2698 | /** |
| 2699 | * d_ancestor - search for an ancestor |
| 2700 | * @p1: ancestor dentry |
| 2701 | * @p2: child dentry |
| 2702 | * |
| 2703 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
| 2704 | * an ancestor of p2, else NULL. |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2705 | */ |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2706 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2707 | { |
| 2708 | struct dentry *p; |
| 2709 | |
OGAWA Hirofumi | 871c006 | 2008-10-16 07:50:27 +0900 | [diff] [blame] | 2710 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2711 | if (p->d_parent == p1) |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2712 | return p; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2713 | } |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2714 | return NULL; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2715 | } |
| 2716 | |
| 2717 | /* |
| 2718 | * This helper attempts to cope with remotely renamed directories |
| 2719 | * |
| 2720 | * It assumes that the caller is already holding |
Eric W. Biederman | a03e283 | 2015-08-15 13:36:41 -0500 | [diff] [blame] | 2721 | * dentry->d_parent->d_inode->i_mutex, and rename_lock |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2722 | * |
| 2723 | * Note: If ever the locking in lock_rename() changes, then please |
| 2724 | * remember to update this too... |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2725 | */ |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2726 | static int __d_unalias(struct inode *inode, |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2727 | struct dentry *dentry, struct dentry *alias) |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2728 | { |
| 2729 | struct mutex *m1 = NULL, *m2 = NULL; |
J. Bruce Fields | 3d330dc | 2015-02-10 10:55:53 -0500 | [diff] [blame] | 2730 | int ret = -ESTALE; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2731 | |
| 2732 | /* If alias and dentry share a parent, then no extra locks required */ |
| 2733 | if (alias->d_parent == dentry->d_parent) |
| 2734 | goto out_unalias; |
| 2735 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2736 | /* See lock_rename() */ |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2737 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
| 2738 | goto out_err; |
| 2739 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
| 2740 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
| 2741 | goto out_err; |
| 2742 | m2 = &alias->d_parent->d_inode->i_mutex; |
| 2743 | out_unalias: |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 2744 | __d_move(alias, dentry, false); |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2745 | ret = 0; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2746 | out_err: |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2747 | if (m2) |
| 2748 | mutex_unlock(m2); |
| 2749 | if (m1) |
| 2750 | mutex_unlock(m1); |
| 2751 | return ret; |
| 2752 | } |
| 2753 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2754 | /** |
J. Bruce Fields | 3f70bd5 | 2014-02-18 14:11:26 -0500 | [diff] [blame] | 2755 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
| 2756 | * @inode: the inode which may have a disconnected dentry |
| 2757 | * @dentry: a negative dentry which we want to point to the inode. |
| 2758 | * |
J. Bruce Fields | da093a9 | 2014-02-17 18:03:57 -0500 | [diff] [blame] | 2759 | * If inode is a directory and has an IS_ROOT alias, then d_move that in |
| 2760 | * place of the given dentry and return it, else simply d_add the inode |
| 2761 | * to the dentry and return NULL. |
J. Bruce Fields | 3f70bd5 | 2014-02-18 14:11:26 -0500 | [diff] [blame] | 2762 | * |
J. Bruce Fields | 908790f | 2014-02-17 17:58:42 -0500 | [diff] [blame] | 2763 | * If a non-IS_ROOT directory is found, the filesystem is corrupt, and |
| 2764 | * we should error out: directories can't have multiple aliases. |
| 2765 | * |
J. Bruce Fields | 3f70bd5 | 2014-02-18 14:11:26 -0500 | [diff] [blame] | 2766 | * This is needed in the lookup routine of any filesystem that is exportable |
| 2767 | * (via knfsd) so that we can build dcache paths to directories effectively. |
| 2768 | * |
| 2769 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
| 2770 | * is returned. This matches the expected return value of ->lookup. |
| 2771 | * |
| 2772 | * Cluster filesystems may call this function with a negative, hashed dentry. |
| 2773 | * In that case, we know that the inode will be a regular file, and also this |
| 2774 | * will only occur during atomic_open. So we need to check for the dentry |
| 2775 | * being already hashed only in the final case. |
| 2776 | */ |
| 2777 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
| 2778 | { |
J. Bruce Fields | 3f70bd5 | 2014-02-18 14:11:26 -0500 | [diff] [blame] | 2779 | if (IS_ERR(inode)) |
| 2780 | return ERR_CAST(inode); |
| 2781 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2782 | BUG_ON(!d_unhashed(dentry)); |
| 2783 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2784 | if (!inode) { |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2785 | __d_instantiate(dentry, NULL); |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2786 | goto out; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2787 | } |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2788 | spin_lock(&inode->i_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2789 | if (S_ISDIR(inode->i_mode)) { |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2790 | struct dentry *new = __d_find_any_alias(inode); |
| 2791 | if (unlikely(new)) { |
Eric W. Biederman | a03e283 | 2015-08-15 13:36:41 -0500 | [diff] [blame] | 2792 | /* The reference to new ensures it remains an alias */ |
| 2793 | spin_unlock(&inode->i_lock); |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2794 | write_seqlock(&rename_lock); |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2795 | if (unlikely(d_ancestor(new, dentry))) { |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2796 | write_sequnlock(&rename_lock); |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2797 | dput(new); |
| 2798 | new = ERR_PTR(-ELOOP); |
| 2799 | pr_warn_ratelimited( |
| 2800 | "VFS: Lookup of '%s' in %s %s" |
| 2801 | " would have caused loop\n", |
| 2802 | dentry->d_name.name, |
| 2803 | inode->i_sb->s_type->name, |
| 2804 | inode->i_sb->s_id); |
| 2805 | } else if (!IS_ROOT(new)) { |
| 2806 | int err = __d_unalias(inode, dentry, new); |
| 2807 | write_sequnlock(&rename_lock); |
| 2808 | if (err) { |
| 2809 | dput(new); |
| 2810 | new = ERR_PTR(err); |
| 2811 | } |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2812 | } else { |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2813 | __d_move(new, dentry, false); |
| 2814 | write_sequnlock(&rename_lock); |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2815 | security_d_instantiate(new, inode); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2816 | } |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2817 | iput(inode); |
| 2818 | return new; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2819 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2820 | } |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2821 | /* already taking inode->i_lock, so d_add() by hand */ |
| 2822 | __d_instantiate(dentry, inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2823 | spin_unlock(&inode->i_lock); |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2824 | out: |
| 2825 | security_d_instantiate(dentry, inode); |
| 2826 | d_rehash(dentry); |
| 2827 | return NULL; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2828 | } |
Al Viro | b5ae6b1 | 2014-10-12 22:16:02 -0400 | [diff] [blame] | 2829 | EXPORT_SYMBOL(d_splice_alias); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2830 | |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2831 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 2832 | { |
| 2833 | *buflen -= namelen; |
| 2834 | if (*buflen < 0) |
| 2835 | return -ENAMETOOLONG; |
| 2836 | *buffer -= namelen; |
| 2837 | memcpy(*buffer, str, namelen); |
| 2838 | return 0; |
| 2839 | } |
| 2840 | |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2841 | /** |
| 2842 | * prepend_name - prepend a pathname in front of current buffer pointer |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 2843 | * @buffer: buffer pointer |
| 2844 | * @buflen: allocated length of the buffer |
| 2845 | * @name: name string and length qstr structure |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2846 | * |
| 2847 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to |
| 2848 | * make sure that either the old or the new name pointer and length are |
| 2849 | * fetched. However, there may be mismatch between length and pointer. |
| 2850 | * The length cannot be trusted, we need to copy it byte-by-byte until |
| 2851 | * the length is reached or a null byte is found. It also prepends "/" at |
| 2852 | * the beginning of the name. The sequence number check at the caller will |
| 2853 | * retry it again when a d_move() does happen. So any garbage in the buffer |
| 2854 | * due to mismatched pointer and length will be discarded. |
Al Viro | 6d13f69 | 2014-09-29 14:46:30 -0400 | [diff] [blame] | 2855 | * |
| 2856 | * Data dependency barrier is needed to make sure that we see that terminating |
| 2857 | * NUL. Alpha strikes again, film at 11... |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2858 | */ |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2859 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
| 2860 | { |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2861 | const char *dname = ACCESS_ONCE(name->name); |
| 2862 | u32 dlen = ACCESS_ONCE(name->len); |
| 2863 | char *p; |
| 2864 | |
Al Viro | 6d13f69 | 2014-09-29 14:46:30 -0400 | [diff] [blame] | 2865 | smp_read_barrier_depends(); |
| 2866 | |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2867 | *buflen -= dlen + 1; |
Al Viro | e825196 | 2014-03-23 00:28:40 -0400 | [diff] [blame] | 2868 | if (*buflen < 0) |
| 2869 | return -ENAMETOOLONG; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2870 | p = *buffer -= dlen + 1; |
| 2871 | *p++ = '/'; |
| 2872 | while (dlen--) { |
| 2873 | char c = *dname++; |
| 2874 | if (!c) |
| 2875 | break; |
| 2876 | *p++ = c; |
| 2877 | } |
| 2878 | return 0; |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2879 | } |
| 2880 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2881 | /** |
Randy Dunlap | 208898c | 2010-11-18 15:02:49 -0800 | [diff] [blame] | 2882 | * prepend_path - Prepend path string to a buffer |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2883 | * @path: the dentry/vfsmount to report |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2884 | * @root: root vfsmnt/dentry |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2885 | * @buffer: pointer to the end of the buffer |
| 2886 | * @buflen: pointer to buffer length |
| 2887 | * |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 2888 | * The function will first try to write out the pathname without taking any |
| 2889 | * lock other than the RCU read lock to make sure that dentries won't go away. |
| 2890 | * It only checks the sequence number of the global rename_lock as any change |
| 2891 | * in the dentry's d_seq will be preceded by changes in the rename_lock |
| 2892 | * sequence number. If the sequence number had been changed, it will restart |
| 2893 | * the whole pathname back-tracing sequence again by taking the rename_lock. |
| 2894 | * In this case, there is no need to take the RCU read lock as the recursive |
| 2895 | * parent pointer references will keep the dentry chain alive as long as no |
| 2896 | * rename operation is performed. |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2897 | */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2898 | static int prepend_path(const struct path *path, |
| 2899 | const struct path *root, |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2900 | char **buffer, int *buflen) |
| 2901 | { |
Al Viro | ede4ceb | 2013-11-13 07:45:40 -0500 | [diff] [blame] | 2902 | struct dentry *dentry; |
| 2903 | struct vfsmount *vfsmnt; |
| 2904 | struct mount *mnt; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2905 | int error = 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2906 | unsigned seq, m_seq = 0; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2907 | char *bptr; |
| 2908 | int blen; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2909 | |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 2910 | rcu_read_lock(); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2911 | restart_mnt: |
| 2912 | read_seqbegin_or_lock(&mount_lock, &m_seq); |
| 2913 | seq = 0; |
Li Zhong | 4ec6c2a | 2013-11-13 15:21:51 +0800 | [diff] [blame] | 2914 | rcu_read_lock(); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2915 | restart: |
| 2916 | bptr = *buffer; |
| 2917 | blen = *buflen; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2918 | error = 0; |
Al Viro | ede4ceb | 2013-11-13 07:45:40 -0500 | [diff] [blame] | 2919 | dentry = path->dentry; |
| 2920 | vfsmnt = path->mnt; |
| 2921 | mnt = real_mount(vfsmnt); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2922 | read_seqbegin_or_lock(&rename_lock, &seq); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2923 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
| 2924 | struct dentry * parent; |
| 2925 | |
| 2926 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2927 | struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); |
Eric W. Biederman | cde93be | 2015-08-15 13:36:12 -0500 | [diff] [blame] | 2928 | /* Escaped? */ |
| 2929 | if (dentry != vfsmnt->mnt_root) { |
| 2930 | bptr = *buffer; |
| 2931 | blen = *buflen; |
| 2932 | error = 3; |
| 2933 | break; |
| 2934 | } |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2935 | /* Global root? */ |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2936 | if (mnt != parent) { |
| 2937 | dentry = ACCESS_ONCE(mnt->mnt_mountpoint); |
| 2938 | mnt = parent; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2939 | vfsmnt = &mnt->mnt; |
| 2940 | continue; |
| 2941 | } |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2942 | if (!error) |
| 2943 | error = is_mounted(vfsmnt) ? 1 : 2; |
| 2944 | break; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2945 | } |
| 2946 | parent = dentry->d_parent; |
| 2947 | prefetch(parent); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2948 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2949 | if (error) |
| 2950 | break; |
| 2951 | |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2952 | dentry = parent; |
| 2953 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 2954 | if (!(seq & 1)) |
| 2955 | rcu_read_unlock(); |
| 2956 | if (need_seqretry(&rename_lock, seq)) { |
| 2957 | seq = 1; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2958 | goto restart; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2959 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 2960 | done_seqretry(&rename_lock, seq); |
Li Zhong | 4ec6c2a | 2013-11-13 15:21:51 +0800 | [diff] [blame] | 2961 | |
| 2962 | if (!(m_seq & 1)) |
| 2963 | rcu_read_unlock(); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2964 | if (need_seqretry(&mount_lock, m_seq)) { |
| 2965 | m_seq = 1; |
| 2966 | goto restart_mnt; |
| 2967 | } |
| 2968 | done_seqretry(&mount_lock, m_seq); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2969 | |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2970 | if (error >= 0 && bptr == *buffer) { |
| 2971 | if (--blen < 0) |
| 2972 | error = -ENAMETOOLONG; |
| 2973 | else |
| 2974 | *--bptr = '/'; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2975 | } |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2976 | *buffer = bptr; |
| 2977 | *buflen = blen; |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 2978 | return error; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2979 | } |
| 2980 | |
| 2981 | /** |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 2982 | * __d_path - return the path of a dentry |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 2983 | * @path: the dentry/vfsmount to report |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2984 | * @root: root vfsmnt/dentry |
Randy Dunlap | cd956a1 | 2010-08-14 13:05:31 -0700 | [diff] [blame] | 2985 | * @buf: buffer to return value in |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2986 | * @buflen: buffer length |
| 2987 | * |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 2988 | * Convert a dentry into an ASCII path name. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2989 | * |
Arjan van de Ven | 52afeef | 2008-12-01 14:35:00 -0800 | [diff] [blame] | 2990 | * Returns a pointer into the buffer or an error code if the |
| 2991 | * path was too long. |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 2992 | * |
Christoph Hellwig | be14824 | 2010-10-10 05:36:21 -0400 | [diff] [blame] | 2993 | * "buflen" should be positive. |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 2994 | * |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2995 | * If the path is not reachable from the supplied root, return %NULL. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2996 | */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2997 | char *__d_path(const struct path *path, |
| 2998 | const struct path *root, |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2999 | char *buf, int buflen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3000 | { |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 3001 | char *res = buf + buflen; |
| 3002 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3003 | |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 3004 | prepend(&res, &buflen, "\0", 1); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 3005 | error = prepend_path(path, root, &res, &buflen); |
Christoph Hellwig | be14824 | 2010-10-10 05:36:21 -0400 | [diff] [blame] | 3006 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3007 | if (error < 0) |
| 3008 | return ERR_PTR(error); |
| 3009 | if (error > 0) |
| 3010 | return NULL; |
| 3011 | return res; |
| 3012 | } |
| 3013 | |
| 3014 | char *d_absolute_path(const struct path *path, |
| 3015 | char *buf, int buflen) |
| 3016 | { |
| 3017 | struct path root = {}; |
| 3018 | char *res = buf + buflen; |
| 3019 | int error; |
| 3020 | |
| 3021 | prepend(&res, &buflen, "\0", 1); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3022 | error = prepend_path(path, &root, &res, &buflen); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3023 | |
| 3024 | if (error > 1) |
| 3025 | error = -EINVAL; |
| 3026 | if (error < 0) |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 3027 | return ERR_PTR(error); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 3028 | return res; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3029 | } |
| 3030 | |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3031 | /* |
| 3032 | * same as __d_path but appends "(deleted)" for unlinked files. |
| 3033 | */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3034 | static int path_with_deleted(const struct path *path, |
| 3035 | const struct path *root, |
| 3036 | char **buf, int *buflen) |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3037 | { |
| 3038 | prepend(buf, buflen, "\0", 1); |
| 3039 | if (d_unlinked(path->dentry)) { |
| 3040 | int error = prepend(buf, buflen, " (deleted)", 10); |
| 3041 | if (error) |
| 3042 | return error; |
| 3043 | } |
| 3044 | |
| 3045 | return prepend_path(path, root, buf, buflen); |
| 3046 | } |
| 3047 | |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3048 | static int prepend_unreachable(char **buffer, int *buflen) |
| 3049 | { |
| 3050 | return prepend(buffer, buflen, "(unreachable)", 13); |
| 3051 | } |
| 3052 | |
Linus Torvalds | 68f0d9d | 2013-09-12 13:24:55 -0700 | [diff] [blame] | 3053 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
| 3054 | { |
| 3055 | unsigned seq; |
| 3056 | |
| 3057 | do { |
| 3058 | seq = read_seqcount_begin(&fs->seq); |
| 3059 | *root = fs->root; |
| 3060 | } while (read_seqcount_retry(&fs->seq, seq)); |
| 3061 | } |
| 3062 | |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3063 | /** |
| 3064 | * d_path - return the path of a dentry |
Jan Blunck | cf28b48 | 2008-02-14 19:38:44 -0800 | [diff] [blame] | 3065 | * @path: path to report |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3066 | * @buf: buffer to return value in |
| 3067 | * @buflen: buffer length |
| 3068 | * |
| 3069 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
| 3070 | * the string " (deleted)" is appended. Note that this is ambiguous. |
| 3071 | * |
Arjan van de Ven | 52afeef | 2008-12-01 14:35:00 -0800 | [diff] [blame] | 3072 | * Returns a pointer into the buffer or an error code if the path was |
| 3073 | * too long. Note: Callers should use the returned pointer, not the passed |
| 3074 | * in buffer, to use the name! The implementation often starts at an offset |
| 3075 | * into the buffer, and may leave 0 bytes at the start. |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3076 | * |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 3077 | * "buflen" should be positive. |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3078 | */ |
Jan Engelhardt | 20d4fdc | 2008-06-09 16:40:36 -0700 | [diff] [blame] | 3079 | char *d_path(const struct path *path, char *buf, int buflen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3080 | { |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3081 | char *res = buf + buflen; |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 3082 | struct path root; |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3083 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3084 | |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3085 | /* |
| 3086 | * We have various synthetic filesystems that never get mounted. On |
| 3087 | * these filesystems dentries are never used for lookup purposes, and |
| 3088 | * thus don't need to be hashed. They also don't need a name until a |
| 3089 | * user wants to identify the object in /proc/pid/fd/. The little hack |
| 3090 | * below allows us to generate a name for these objects on demand: |
Eric W. Biederman | f48cfdd | 2013-11-08 16:31:29 -0800 | [diff] [blame] | 3091 | * |
| 3092 | * Some pseudo inodes are mountable. When they are mounted |
| 3093 | * path->dentry == path->mnt->mnt_root. In that case don't call d_dname |
| 3094 | * and instead have d_path return the mounted path. |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3095 | */ |
Eric W. Biederman | f48cfdd | 2013-11-08 16:31:29 -0800 | [diff] [blame] | 3096 | if (path->dentry->d_op && path->dentry->d_op->d_dname && |
| 3097 | (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root)) |
Jan Blunck | cf28b48 | 2008-02-14 19:38:44 -0800 | [diff] [blame] | 3098 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3099 | |
Linus Torvalds | 68f0d9d | 2013-09-12 13:24:55 -0700 | [diff] [blame] | 3100 | rcu_read_lock(); |
| 3101 | get_fs_root_rcu(current->fs, &root); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3102 | error = path_with_deleted(path, &root, &res, &buflen); |
Linus Torvalds | 68f0d9d | 2013-09-12 13:24:55 -0700 | [diff] [blame] | 3103 | rcu_read_unlock(); |
| 3104 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3105 | if (error < 0) |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3106 | res = ERR_PTR(error); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3107 | return res; |
| 3108 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 3109 | EXPORT_SYMBOL(d_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3110 | |
| 3111 | /* |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3112 | * Helper function for dentry_operations.d_dname() members |
| 3113 | */ |
| 3114 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
| 3115 | const char *fmt, ...) |
| 3116 | { |
| 3117 | va_list args; |
| 3118 | char temp[64]; |
| 3119 | int sz; |
| 3120 | |
| 3121 | va_start(args, fmt); |
| 3122 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
| 3123 | va_end(args); |
| 3124 | |
| 3125 | if (sz > sizeof(temp) || sz > buflen) |
| 3126 | return ERR_PTR(-ENAMETOOLONG); |
| 3127 | |
| 3128 | buffer += buflen - sz; |
| 3129 | return memcpy(buffer, temp, sz); |
| 3130 | } |
| 3131 | |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3132 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
| 3133 | { |
| 3134 | char *end = buffer + buflen; |
| 3135 | /* these dentries are never renamed, so d_lock is not needed */ |
| 3136 | if (prepend(&end, &buflen, " (deleted)", 11) || |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3137 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3138 | prepend(&end, &buflen, "/", 1)) |
| 3139 | end = ERR_PTR(-ENAMETOOLONG); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3140 | return end; |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3141 | } |
David Herrmann | 31bbe16 | 2014-01-03 14:09:47 +0100 | [diff] [blame] | 3142 | EXPORT_SYMBOL(simple_dname); |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3143 | |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3144 | /* |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3145 | * Write full pathname from the root of the filesystem into the buffer. |
| 3146 | */ |
Al Viro | f650080 | 2014-01-26 12:37:55 -0500 | [diff] [blame] | 3147 | static char *__dentry_path(struct dentry *d, char *buf, int buflen) |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3148 | { |
Al Viro | f650080 | 2014-01-26 12:37:55 -0500 | [diff] [blame] | 3149 | struct dentry *dentry; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3150 | char *end, *retval; |
| 3151 | int len, seq = 0; |
| 3152 | int error = 0; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3153 | |
Al Viro | f650080 | 2014-01-26 12:37:55 -0500 | [diff] [blame] | 3154 | if (buflen < 2) |
| 3155 | goto Elong; |
| 3156 | |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 3157 | rcu_read_lock(); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3158 | restart: |
Al Viro | f650080 | 2014-01-26 12:37:55 -0500 | [diff] [blame] | 3159 | dentry = d; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3160 | end = buf + buflen; |
| 3161 | len = buflen; |
| 3162 | prepend(&end, &len, "\0", 1); |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3163 | /* Get '/' right */ |
| 3164 | retval = end-1; |
| 3165 | *retval = '/'; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3166 | read_seqbegin_or_lock(&rename_lock, &seq); |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 3167 | while (!IS_ROOT(dentry)) { |
| 3168 | struct dentry *parent = dentry->d_parent; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3169 | |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3170 | prefetch(parent); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3171 | error = prepend_name(&end, &len, &dentry->d_name); |
| 3172 | if (error) |
| 3173 | break; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3174 | |
| 3175 | retval = end; |
| 3176 | dentry = parent; |
| 3177 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 3178 | if (!(seq & 1)) |
| 3179 | rcu_read_unlock(); |
| 3180 | if (need_seqretry(&rename_lock, seq)) { |
| 3181 | seq = 1; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3182 | goto restart; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 3183 | } |
| 3184 | done_seqretry(&rename_lock, seq); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3185 | if (error) |
| 3186 | goto Elong; |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3187 | return retval; |
| 3188 | Elong: |
| 3189 | return ERR_PTR(-ENAMETOOLONG); |
| 3190 | } |
Nick Piggin | ec2447c | 2011-01-07 17:49:29 +1100 | [diff] [blame] | 3191 | |
| 3192 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
| 3193 | { |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3194 | return __dentry_path(dentry, buf, buflen); |
Nick Piggin | ec2447c | 2011-01-07 17:49:29 +1100 | [diff] [blame] | 3195 | } |
| 3196 | EXPORT_SYMBOL(dentry_path_raw); |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3197 | |
| 3198 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
| 3199 | { |
| 3200 | char *p = NULL; |
| 3201 | char *retval; |
| 3202 | |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3203 | if (d_unlinked(dentry)) { |
| 3204 | p = buf + buflen; |
| 3205 | if (prepend(&p, &buflen, "//deleted", 10) != 0) |
| 3206 | goto Elong; |
| 3207 | buflen++; |
| 3208 | } |
| 3209 | retval = __dentry_path(dentry, buf, buflen); |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3210 | if (!IS_ERR(retval) && p) |
| 3211 | *p = '/'; /* restore '/' overriden with '\0' */ |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3212 | return retval; |
| 3213 | Elong: |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3214 | return ERR_PTR(-ENAMETOOLONG); |
| 3215 | } |
| 3216 | |
Linus Torvalds | 8b19e34 | 2013-09-12 10:35:47 -0700 | [diff] [blame] | 3217 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
| 3218 | struct path *pwd) |
Linus Torvalds | 5762482 | 2013-09-12 10:12:47 -0700 | [diff] [blame] | 3219 | { |
Linus Torvalds | 8b19e34 | 2013-09-12 10:35:47 -0700 | [diff] [blame] | 3220 | unsigned seq; |
| 3221 | |
| 3222 | do { |
| 3223 | seq = read_seqcount_begin(&fs->seq); |
| 3224 | *root = fs->root; |
| 3225 | *pwd = fs->pwd; |
| 3226 | } while (read_seqcount_retry(&fs->seq, seq)); |
Linus Torvalds | 5762482 | 2013-09-12 10:12:47 -0700 | [diff] [blame] | 3227 | } |
| 3228 | |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3229 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3230 | * NOTE! The user-level library version returns a |
| 3231 | * character pointer. The kernel system call just |
| 3232 | * returns the length of the buffer filled (which |
| 3233 | * includes the ending '\0' character), or a negative |
| 3234 | * error value. So libc would do something like |
| 3235 | * |
| 3236 | * char *getcwd(char * buf, size_t size) |
| 3237 | * { |
| 3238 | * int retval; |
| 3239 | * |
| 3240 | * retval = sys_getcwd(buf, size); |
| 3241 | * if (retval >= 0) |
| 3242 | * return buf; |
| 3243 | * errno = -retval; |
| 3244 | * return NULL; |
| 3245 | * } |
| 3246 | */ |
Heiko Carstens | 3cdad42 | 2009-01-14 14:14:22 +0100 | [diff] [blame] | 3247 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3248 | { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3249 | int error; |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 3250 | struct path pwd, root; |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3251 | char *page = __getname(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3252 | |
| 3253 | if (!page) |
| 3254 | return -ENOMEM; |
| 3255 | |
Linus Torvalds | 8b19e34 | 2013-09-12 10:35:47 -0700 | [diff] [blame] | 3256 | rcu_read_lock(); |
| 3257 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3258 | |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3259 | error = -ENOENT; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 3260 | if (!d_unlinked(pwd.dentry)) { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3261 | unsigned long len; |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3262 | char *cwd = page + PATH_MAX; |
| 3263 | int buflen = PATH_MAX; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3264 | |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3265 | prepend(&cwd, &buflen, "\0", 1); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3266 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
Linus Torvalds | ff812d7 | 2013-09-12 11:57:01 -0700 | [diff] [blame] | 3267 | rcu_read_unlock(); |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3268 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3269 | if (error < 0) |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3270 | goto out; |
| 3271 | |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3272 | /* Unreachable from current root */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3273 | if (error > 0) { |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3274 | error = prepend_unreachable(&cwd, &buflen); |
| 3275 | if (error) |
| 3276 | goto out; |
| 3277 | } |
| 3278 | |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3279 | error = -ERANGE; |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3280 | len = PATH_MAX + page - cwd; |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3281 | if (len <= size) { |
| 3282 | error = len; |
| 3283 | if (copy_to_user(buf, cwd, len)) |
| 3284 | error = -EFAULT; |
| 3285 | } |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3286 | } else { |
Linus Torvalds | ff812d7 | 2013-09-12 11:57:01 -0700 | [diff] [blame] | 3287 | rcu_read_unlock(); |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3288 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3289 | |
| 3290 | out: |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3291 | __putname(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3292 | return error; |
| 3293 | } |
| 3294 | |
| 3295 | /* |
| 3296 | * Test whether new_dentry is a subdirectory of old_dentry. |
| 3297 | * |
| 3298 | * Trivially implemented using the dcache structure |
| 3299 | */ |
| 3300 | |
| 3301 | /** |
| 3302 | * is_subdir - is new dentry a subdirectory of old_dentry |
| 3303 | * @new_dentry: new dentry |
| 3304 | * @old_dentry: old dentry |
| 3305 | * |
Yaowei Bai | a6e5787 | 2015-11-17 14:40:11 +0800 | [diff] [blame] | 3306 | * Returns true if new_dentry is a subdirectory of the parent (at any depth). |
| 3307 | * Returns false otherwise. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3308 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
| 3309 | */ |
| 3310 | |
Yaowei Bai | a6e5787 | 2015-11-17 14:40:11 +0800 | [diff] [blame] | 3311 | bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3312 | { |
Yaowei Bai | a6e5787 | 2015-11-17 14:40:11 +0800 | [diff] [blame] | 3313 | bool result; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3314 | unsigned seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3315 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3316 | if (new_dentry == old_dentry) |
Yaowei Bai | a6e5787 | 2015-11-17 14:40:11 +0800 | [diff] [blame] | 3317 | return true; |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3318 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3319 | do { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3320 | /* for restarting inner loop in case of seq retry */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3321 | seq = read_seqbegin(&rename_lock); |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3322 | /* |
| 3323 | * Need rcu_readlock to protect against the d_parent trashing |
| 3324 | * due to d_move |
| 3325 | */ |
| 3326 | rcu_read_lock(); |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3327 | if (d_ancestor(old_dentry, new_dentry)) |
Yaowei Bai | a6e5787 | 2015-11-17 14:40:11 +0800 | [diff] [blame] | 3328 | result = true; |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3329 | else |
Yaowei Bai | a6e5787 | 2015-11-17 14:40:11 +0800 | [diff] [blame] | 3330 | result = false; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3331 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3332 | } while (read_seqretry(&rename_lock, seq)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3333 | |
| 3334 | return result; |
| 3335 | } |
| 3336 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3337 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3338 | { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3339 | struct dentry *root = data; |
| 3340 | if (dentry != root) { |
| 3341 | if (d_unhashed(dentry) || !dentry->d_inode) |
| 3342 | return D_WALK_SKIP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3343 | |
Miklos Szeredi | 01ddc4e | 2013-09-05 11:44:34 +0200 | [diff] [blame] | 3344 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
| 3345 | dentry->d_flags |= DCACHE_GENOCIDE; |
| 3346 | dentry->d_lockref.count--; |
| 3347 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3348 | } |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3349 | return D_WALK_CONTINUE; |
| 3350 | } |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 3351 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3352 | void d_genocide(struct dentry *parent) |
| 3353 | { |
| 3354 | d_walk(parent, parent, d_genocide_kill, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3355 | } |
| 3356 | |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3357 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3358 | { |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3359 | inode_dec_link_count(inode); |
| 3360 | BUG_ON(dentry->d_name.name != dentry->d_iname || |
Al Viro | 946e51f | 2014-10-26 19:19:16 -0400 | [diff] [blame] | 3361 | !hlist_unhashed(&dentry->d_u.d_alias) || |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3362 | !d_unlinked(dentry)); |
| 3363 | spin_lock(&dentry->d_parent->d_lock); |
| 3364 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| 3365 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", |
| 3366 | (unsigned long long)inode->i_ino); |
| 3367 | spin_unlock(&dentry->d_lock); |
| 3368 | spin_unlock(&dentry->d_parent->d_lock); |
| 3369 | d_instantiate(dentry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3370 | } |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3371 | EXPORT_SYMBOL(d_tmpfile); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3372 | |
| 3373 | static __initdata unsigned long dhash_entries; |
| 3374 | static int __init set_dhash_entries(char *str) |
| 3375 | { |
| 3376 | if (!str) |
| 3377 | return 0; |
| 3378 | dhash_entries = simple_strtoul(str, &str, 0); |
| 3379 | return 1; |
| 3380 | } |
| 3381 | __setup("dhash_entries=", set_dhash_entries); |
| 3382 | |
| 3383 | static void __init dcache_init_early(void) |
| 3384 | { |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3385 | unsigned int loop; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3386 | |
| 3387 | /* If hashes are distributed across NUMA nodes, defer |
| 3388 | * hash allocation until vmalloc space is available. |
| 3389 | */ |
| 3390 | if (hashdist) |
| 3391 | return; |
| 3392 | |
| 3393 | dentry_hashtable = |
| 3394 | alloc_large_system_hash("Dentry cache", |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 3395 | sizeof(struct hlist_bl_head), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3396 | dhash_entries, |
| 3397 | 13, |
| 3398 | HASH_EARLY, |
| 3399 | &d_hash_shift, |
| 3400 | &d_hash_mask, |
Tim Bird | 31fe62b | 2012-05-23 13:33:35 +0000 | [diff] [blame] | 3401 | 0, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3402 | 0); |
| 3403 | |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3404 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 3405 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3406 | } |
| 3407 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3408 | static void __init dcache_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3409 | { |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3410 | unsigned int loop; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3411 | |
| 3412 | /* |
| 3413 | * A constructor could be added for stable state like the lists, |
| 3414 | * but it is probably not worth it because of the cache nature |
| 3415 | * of the dcache. |
| 3416 | */ |
Christoph Lameter | 0a31bd5 | 2007-05-06 14:49:57 -0700 | [diff] [blame] | 3417 | dentry_cache = KMEM_CACHE(dentry, |
| 3418 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3419 | |
| 3420 | /* Hash may have been set up in dcache_init_early */ |
| 3421 | if (!hashdist) |
| 3422 | return; |
| 3423 | |
| 3424 | dentry_hashtable = |
| 3425 | alloc_large_system_hash("Dentry cache", |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 3426 | sizeof(struct hlist_bl_head), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3427 | dhash_entries, |
| 3428 | 13, |
| 3429 | 0, |
| 3430 | &d_hash_shift, |
| 3431 | &d_hash_mask, |
Tim Bird | 31fe62b | 2012-05-23 13:33:35 +0000 | [diff] [blame] | 3432 | 0, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3433 | 0); |
| 3434 | |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3435 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 3436 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3437 | } |
| 3438 | |
| 3439 | /* SLAB cache for __getname() consumers */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 3440 | struct kmem_cache *names_cachep __read_mostly; |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 3441 | EXPORT_SYMBOL(names_cachep); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3442 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3443 | EXPORT_SYMBOL(d_genocide); |
| 3444 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3445 | void __init vfs_caches_init_early(void) |
| 3446 | { |
| 3447 | dcache_init_early(); |
| 3448 | inode_init_early(); |
| 3449 | } |
| 3450 | |
Mel Gorman | 4248b0d | 2015-08-06 15:46:20 -0700 | [diff] [blame] | 3451 | void __init vfs_caches_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3452 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3453 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 3454 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3455 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3456 | dcache_init(); |
| 3457 | inode_init(); |
Mel Gorman | 4248b0d | 2015-08-06 15:46:20 -0700 | [diff] [blame] | 3458 | files_init(); |
| 3459 | files_maxfiles_init(); |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3460 | mnt_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3461 | bdev_cache_init(); |
| 3462 | chrdev_init(); |
| 3463 | } |