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> |
David Howells | 07f3f05c | 2006-09-30 20:52:18 +0200 | [diff] [blame] | 41 | #include "internal.h" |
Al Viro | b2dba1a | 2011-11-23 19:26:23 -0500 | [diff] [blame] | 42 | #include "mount.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 44 | /* |
| 45 | * Usage: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 46 | * dcache->d_inode->i_lock protects: |
| 47 | * - i_dentry, d_alias, d_inode of aliases |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 48 | * dcache_hash_bucket lock protects: |
| 49 | * - the dcache hash table |
| 50 | * s_anon bl list spinlock protects: |
| 51 | * - the s_anon list (see __d_drop) |
Dave Chinner | 1915684 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 52 | * dentry->d_sb->s_dentry_lru_lock protects: |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 53 | * - the dcache lru lists and counters |
| 54 | * d_lock protects: |
| 55 | * - d_flags |
| 56 | * - d_name |
| 57 | * - d_lru |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 58 | * - d_count |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 59 | * - d_unhashed() |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 60 | * - d_parent and d_subdirs |
| 61 | * - childrens' d_child and d_parent |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 62 | * - d_alias, d_inode |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 63 | * |
| 64 | * Ordering: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 65 | * dentry->d_inode->i_lock |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 66 | * dentry->d_lock |
Dave Chinner | 1915684 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 67 | * dentry->d_sb->s_dentry_lru_lock |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 68 | * dcache_hash_bucket lock |
| 69 | * s_anon lock |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 70 | * |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 71 | * If there is an ancestor relationship: |
| 72 | * dentry->d_parent->...->d_parent->d_lock |
| 73 | * ... |
| 74 | * dentry->d_parent->d_lock |
| 75 | * dentry->d_lock |
| 76 | * |
| 77 | * If no ancestor relationship: |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 78 | * if (dentry1 < dentry2) |
| 79 | * dentry1->d_lock |
| 80 | * dentry2->d_lock |
| 81 | */ |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 82 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
| 84 | |
Al Viro | 74c3cbe | 2007-07-22 08:04:18 -0400 | [diff] [blame] | 85 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 87 | EXPORT_SYMBOL(rename_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 89 | static struct kmem_cache *dentry_cache __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 91 | /** |
| 92 | * read_seqbegin_or_lock - begin a sequence number check or locking block |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 93 | * @lock: sequence lock |
| 94 | * @seq : sequence number to be checked |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 95 | * |
| 96 | * First try it once optimistically without taking the lock. If that fails, |
| 97 | * take the lock. The sequence number is also used as a marker for deciding |
| 98 | * whether to be a reader (even) or writer (odd). |
| 99 | * N.B. seq must be initialized to an even number to begin with. |
| 100 | */ |
| 101 | static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq) |
| 102 | { |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 103 | if (!(*seq & 1)) /* Even */ |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 104 | *seq = read_seqbegin(lock); |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 105 | else /* Odd */ |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 106 | read_seqlock_excl(lock); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 107 | } |
| 108 | |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 109 | static inline int need_seqretry(seqlock_t *lock, int seq) |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 110 | { |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 111 | return !(seq & 1) && read_seqretry(lock, seq); |
| 112 | } |
| 113 | |
| 114 | static inline void done_seqretry(seqlock_t *lock, int seq) |
| 115 | { |
| 116 | if (seq & 1) |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 117 | read_sequnlock_excl(lock); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 118 | } |
| 119 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | /* |
| 121 | * This is the single most critical data structure when it comes |
| 122 | * to the dcache: the hashtable for lookups. Somebody should try |
| 123 | * to make this good - I've just made it work. |
| 124 | * |
| 125 | * This hash-function tries to avoid losing too many bits of hash |
| 126 | * information, yet avoid using a prime hash-size or similar. |
| 127 | */ |
| 128 | #define D_HASHBITS d_hash_shift |
| 129 | #define D_HASHMASK d_hash_mask |
| 130 | |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 131 | static unsigned int d_hash_mask __read_mostly; |
| 132 | static unsigned int d_hash_shift __read_mostly; |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 133 | |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 134 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 135 | |
Linus Torvalds | 8966be9 | 2012-03-02 14:23:30 -0800 | [diff] [blame] | 136 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
Linus Torvalds | 6d7d1a0 | 2012-03-19 16:19:53 -0700 | [diff] [blame] | 137 | unsigned int hash) |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 138 | { |
Linus Torvalds | 6d7d1a0 | 2012-03-19 16:19:53 -0700 | [diff] [blame] | 139 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
| 140 | hash = hash + (hash >> D_HASHBITS); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 141 | return dentry_hashtable + (hash & D_HASHMASK); |
| 142 | } |
| 143 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 144 | /* Statistics gathering. */ |
| 145 | struct dentry_stat_t dentry_stat = { |
| 146 | .age_limit = 45, |
| 147 | }; |
| 148 | |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 149 | static DEFINE_PER_CPU(long, nr_dentry); |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 150 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 151 | |
| 152 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 153 | |
| 154 | /* |
| 155 | * Here we resort to our own counters instead of using generic per-cpu counters |
| 156 | * for consistency with what the vfs inode code does. We are expected to harvest |
| 157 | * better code and performance by having our own specialized counters. |
| 158 | * |
| 159 | * Please note that the loop is done over all possible CPUs, not over all online |
| 160 | * CPUs. The reason for this is that we don't want to play games with CPUs going |
| 161 | * on and off. If one of them goes off, we will just keep their counters. |
| 162 | * |
| 163 | * glommer: See cffbc8a for details, and if you ever intend to change this, |
| 164 | * please update all vfs counters to match. |
| 165 | */ |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 166 | static long get_nr_dentry(void) |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 167 | { |
| 168 | int i; |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 169 | long sum = 0; |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 170 | for_each_possible_cpu(i) |
| 171 | sum += per_cpu(nr_dentry, i); |
| 172 | return sum < 0 ? 0 : sum; |
| 173 | } |
| 174 | |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 175 | static long get_nr_dentry_unused(void) |
| 176 | { |
| 177 | int i; |
| 178 | long sum = 0; |
| 179 | for_each_possible_cpu(i) |
| 180 | sum += per_cpu(nr_dentry_unused, i); |
| 181 | return sum < 0 ? 0 : sum; |
| 182 | } |
| 183 | |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 184 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
| 185 | size_t *lenp, loff_t *ppos) |
| 186 | { |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 187 | dentry_stat.nr_dentry = get_nr_dentry(); |
Dave Chinner | 62d36c7 | 2013-08-28 10:17:54 +1000 | [diff] [blame] | 188 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
Glauber Costa | 3942c07 | 2013-08-28 10:17:53 +1000 | [diff] [blame] | 189 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 190 | } |
| 191 | #endif |
| 192 | |
Linus Torvalds | 5483f18 | 2012-03-04 15:51:42 -0800 | [diff] [blame] | 193 | /* |
| 194 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. |
| 195 | * The strings are both count bytes long, and count is non-zero. |
| 196 | */ |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 197 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
| 198 | |
| 199 | #include <asm/word-at-a-time.h> |
| 200 | /* |
| 201 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a |
| 202 | * aligned allocation for this particular component. We don't |
| 203 | * strictly need the load_unaligned_zeropad() safety, but it |
| 204 | * doesn't hurt either. |
| 205 | * |
| 206 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do |
| 207 | * need the careful unaligned handling. |
| 208 | */ |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 209 | 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] | 210 | { |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 211 | unsigned long a,b,mask; |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 212 | |
| 213 | for (;;) { |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 214 | a = *(unsigned long *)cs; |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 215 | b = load_unaligned_zeropad(ct); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 216 | if (tcount < sizeof(unsigned long)) |
| 217 | break; |
| 218 | if (unlikely(a != b)) |
| 219 | return 1; |
| 220 | cs += sizeof(unsigned long); |
| 221 | ct += sizeof(unsigned long); |
| 222 | tcount -= sizeof(unsigned long); |
| 223 | if (!tcount) |
| 224 | return 0; |
| 225 | } |
| 226 | mask = ~(~0ul << tcount*8); |
| 227 | return unlikely(!!((a ^ b) & mask)); |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 228 | } |
| 229 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 230 | #else |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 231 | |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 232 | 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] | 233 | { |
Linus Torvalds | 5483f18 | 2012-03-04 15:51:42 -0800 | [diff] [blame] | 234 | do { |
| 235 | if (*cs != *ct) |
| 236 | return 1; |
| 237 | cs++; |
| 238 | ct++; |
| 239 | tcount--; |
| 240 | } while (tcount); |
| 241 | return 0; |
| 242 | } |
| 243 | |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 244 | #endif |
| 245 | |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 246 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
| 247 | { |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 248 | const unsigned char *cs; |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 249 | /* |
| 250 | * Be careful about RCU walk racing with rename: |
| 251 | * use ACCESS_ONCE to fetch the name pointer. |
| 252 | * |
| 253 | * NOTE! Even if a rename will mean that the length |
| 254 | * was not loaded atomically, we don't care. The |
| 255 | * RCU walk will check the sequence count eventually, |
| 256 | * and catch it. And we won't overrun the buffer, |
| 257 | * because we're reading the name pointer atomically, |
| 258 | * and a dentry name is guaranteed to be properly |
| 259 | * terminated with a NUL byte. |
| 260 | * |
| 261 | * End result: even if 'len' is wrong, we'll exit |
| 262 | * early because the data cannot match (there can |
| 263 | * be no NUL in the ct/tcount data) |
| 264 | */ |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 265 | cs = ACCESS_ONCE(dentry->d_name.name); |
| 266 | smp_read_barrier_depends(); |
| 267 | return dentry_string_cmp(cs, ct, tcount); |
Linus Torvalds | 94753db5 | 2012-05-10 12:19:19 -0700 | [diff] [blame] | 268 | } |
| 269 | |
Christoph Hellwig | 9c82ab9 | 2010-10-10 05:36:22 -0400 | [diff] [blame] | 270 | static void __d_free(struct rcu_head *head) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 271 | { |
Christoph Hellwig | 9c82ab9 | 2010-10-10 05:36:22 -0400 | [diff] [blame] | 272 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
| 273 | |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 274 | WARN_ON(!hlist_unhashed(&dentry->d_alias)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | if (dname_external(dentry)) |
| 276 | kfree(dentry->d_name.name); |
| 277 | kmem_cache_free(dentry_cache, dentry); |
| 278 | } |
| 279 | |
| 280 | /* |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 281 | * no locks, please. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 282 | */ |
| 283 | static void d_free(struct dentry *dentry) |
| 284 | { |
Linus Torvalds | 0d98439 | 2013-09-08 13:46:52 -0700 | [diff] [blame] | 285 | BUG_ON((int)dentry->d_lockref.count > 0); |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 286 | this_cpu_dec(nr_dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 287 | if (dentry->d_op && dentry->d_op->d_release) |
| 288 | dentry->d_op->d_release(dentry); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 289 | |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 290 | /* if dentry was never visible to RCU, immediate free is OK */ |
| 291 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) |
Christoph Hellwig | 9c82ab9 | 2010-10-10 05:36:22 -0400 | [diff] [blame] | 292 | __d_free(&dentry->d_u.d_rcu); |
Eric Dumazet | b342341 | 2006-12-06 20:38:48 -0800 | [diff] [blame] | 293 | else |
Christoph Hellwig | 9c82ab9 | 2010-10-10 05:36:22 -0400 | [diff] [blame] | 294 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | } |
| 296 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 297 | /** |
| 298 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups |
Randy Dunlap | ff5fdb6 | 2011-01-22 20:16:06 -0800 | [diff] [blame] | 299 | * @dentry: the target dentry |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 300 | * After this call, in-progress rcu-walk path lookup will fail. This |
| 301 | * should be called after unhashing, and after changing d_inode (if |
| 302 | * the dentry has not already been unhashed). |
| 303 | */ |
| 304 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) |
| 305 | { |
| 306 | assert_spin_locked(&dentry->d_lock); |
| 307 | /* Go through a barrier */ |
| 308 | write_seqcount_barrier(&dentry->d_seq); |
| 309 | } |
| 310 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 311 | /* |
| 312 | * Release the dentry's inode, using the filesystem |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 313 | * d_iput() operation if defined. Dentry has no refcount |
| 314 | * and is unhashed. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 315 | */ |
Arjan van de Ven | 858119e | 2006-01-14 13:20:43 -0800 | [diff] [blame] | 316 | static void dentry_iput(struct dentry * dentry) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 317 | __releases(dentry->d_lock) |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 318 | __releases(dentry->d_inode->i_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 319 | { |
| 320 | struct inode *inode = dentry->d_inode; |
| 321 | if (inode) { |
| 322 | dentry->d_inode = NULL; |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 323 | hlist_del_init(&dentry->d_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 324 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 325 | spin_unlock(&inode->i_lock); |
Linus Torvalds | f805fbd | 2005-09-19 19:54:29 -0700 | [diff] [blame] | 326 | if (!inode->i_nlink) |
| 327 | fsnotify_inoderemove(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 328 | if (dentry->d_op && dentry->d_op->d_iput) |
| 329 | dentry->d_op->d_iput(dentry, inode); |
| 330 | else |
| 331 | iput(inode); |
| 332 | } else { |
| 333 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 334 | } |
| 335 | } |
| 336 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 337 | /* |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 338 | * Release the dentry's inode, using the filesystem |
| 339 | * d_iput() operation if defined. dentry remains in-use. |
| 340 | */ |
| 341 | static void dentry_unlink_inode(struct dentry * dentry) |
| 342 | __releases(dentry->d_lock) |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 343 | __releases(dentry->d_inode->i_lock) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 344 | { |
| 345 | struct inode *inode = dentry->d_inode; |
| 346 | dentry->d_inode = NULL; |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 347 | hlist_del_init(&dentry->d_alias); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 348 | dentry_rcuwalk_barrier(dentry); |
| 349 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 350 | spin_unlock(&inode->i_lock); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 351 | if (!inode->i_nlink) |
| 352 | fsnotify_inoderemove(inode); |
| 353 | if (dentry->d_op && dentry->d_op->d_iput) |
| 354 | dentry->d_op->d_iput(dentry, inode); |
| 355 | else |
| 356 | iput(inode); |
| 357 | } |
| 358 | |
| 359 | /* |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 360 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry |
| 361 | * is in use - which includes both the "real" per-superblock |
| 362 | * LRU list _and_ the DCACHE_SHRINK_LIST use. |
| 363 | * |
| 364 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is |
| 365 | * on the shrink list (ie not on the superblock LRU list). |
| 366 | * |
| 367 | * The per-cpu "nr_dentry_unused" counters are updated with |
| 368 | * the DCACHE_LRU_LIST bit. |
| 369 | * |
| 370 | * These helper functions make sure we always follow the |
| 371 | * rules. d_lock must be held by the caller. |
| 372 | */ |
| 373 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) |
| 374 | static void d_lru_add(struct dentry *dentry) |
| 375 | { |
| 376 | D_FLAG_VERIFY(dentry, 0); |
| 377 | dentry->d_flags |= DCACHE_LRU_LIST; |
| 378 | this_cpu_inc(nr_dentry_unused); |
| 379 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); |
| 380 | } |
| 381 | |
| 382 | static void d_lru_del(struct dentry *dentry) |
| 383 | { |
| 384 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 385 | dentry->d_flags &= ~DCACHE_LRU_LIST; |
| 386 | this_cpu_dec(nr_dentry_unused); |
| 387 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); |
| 388 | } |
| 389 | |
| 390 | static void d_shrink_del(struct dentry *dentry) |
| 391 | { |
| 392 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); |
| 393 | list_del_init(&dentry->d_lru); |
| 394 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); |
| 395 | this_cpu_dec(nr_dentry_unused); |
| 396 | } |
| 397 | |
| 398 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) |
| 399 | { |
| 400 | D_FLAG_VERIFY(dentry, 0); |
| 401 | list_add(&dentry->d_lru, list); |
| 402 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; |
| 403 | this_cpu_inc(nr_dentry_unused); |
| 404 | } |
| 405 | |
| 406 | /* |
| 407 | * These can only be called under the global LRU lock, ie during the |
| 408 | * callback for freeing the LRU list. "isolate" removes it from the |
| 409 | * LRU lists entirely, while shrink_move moves it to the indicated |
| 410 | * private list. |
| 411 | */ |
| 412 | static void d_lru_isolate(struct dentry *dentry) |
| 413 | { |
| 414 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 415 | dentry->d_flags &= ~DCACHE_LRU_LIST; |
| 416 | this_cpu_dec(nr_dentry_unused); |
| 417 | list_del_init(&dentry->d_lru); |
| 418 | } |
| 419 | |
| 420 | static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list) |
| 421 | { |
| 422 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 423 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
| 424 | list_move_tail(&dentry->d_lru, list); |
| 425 | } |
| 426 | |
| 427 | /* |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 428 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 429 | */ |
| 430 | static void dentry_lru_add(struct dentry *dentry) |
| 431 | { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 432 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
| 433 | d_lru_add(dentry); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 434 | } |
| 435 | |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 436 | /* |
| 437 | * Remove a dentry with references from the LRU. |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 438 | * |
| 439 | * If we are on the shrink list, then we can get to try_prune_one_dentry() and |
| 440 | * lose our last reference through the parent walk. In this case, we need to |
| 441 | * remove ourselves from the shrink list, not the LRU. |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 442 | */ |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 443 | static void dentry_lru_del(struct dentry *dentry) |
| 444 | { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 445 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
| 446 | if (dentry->d_flags & DCACHE_SHRINK_LIST) |
| 447 | return d_shrink_del(dentry); |
| 448 | d_lru_del(dentry); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 449 | } |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 450 | } |
| 451 | |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 452 | /** |
| 453 | * d_kill - kill dentry and return parent |
| 454 | * @dentry: dentry to kill |
Randy Dunlap | ff5fdb6 | 2011-01-22 20:16:06 -0800 | [diff] [blame] | 455 | * @parent: parent dentry |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 456 | * |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 457 | * The dentry must already be unhashed and removed from the LRU. |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 458 | * |
| 459 | * If this is the root of the dentry tree, return NULL. |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 460 | * |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 461 | * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by |
| 462 | * d_kill. |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 463 | */ |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 464 | static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 465 | __releases(dentry->d_lock) |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 466 | __releases(parent->d_lock) |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 467 | __releases(dentry->d_inode->i_lock) |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 468 | { |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 469 | list_del(&dentry->d_u.d_child); |
Trond Myklebust | c83ce98 | 2011-03-15 13:36:43 -0400 | [diff] [blame] | 470 | /* |
| 471 | * Inform try_to_ascend() that we are no longer attached to the |
| 472 | * dentry tree |
| 473 | */ |
Miklos Szeredi | b161dfa6 | 2012-09-17 22:31:38 +0200 | [diff] [blame] | 474 | dentry->d_flags |= DCACHE_DENTRY_KILLED; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 475 | if (parent) |
| 476 | spin_unlock(&parent->d_lock); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 477 | dentry_iput(dentry); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 478 | /* |
| 479 | * dentry_iput drops the locks, at which point nobody (except |
| 480 | * transient RCU lookups) can reach this dentry. |
| 481 | */ |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 482 | d_free(dentry); |
OGAWA Hirofumi | 871c006 | 2008-10-16 07:50:27 +0900 | [diff] [blame] | 483 | return parent; |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 484 | } |
| 485 | |
David Howells | c6627c6 | 2011-06-07 14:09:20 +0100 | [diff] [blame] | 486 | /* |
| 487 | * Unhash a dentry without inserting an RCU walk barrier or checking that |
| 488 | * dentry->d_lock is locked. The caller must take care of that, if |
| 489 | * appropriate. |
| 490 | */ |
| 491 | static void __d_shrink(struct dentry *dentry) |
| 492 | { |
| 493 | if (!d_unhashed(dentry)) { |
| 494 | struct hlist_bl_head *b; |
| 495 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) |
| 496 | b = &dentry->d_sb->s_anon; |
| 497 | else |
| 498 | b = d_hash(dentry->d_parent, dentry->d_name.hash); |
| 499 | |
| 500 | hlist_bl_lock(b); |
| 501 | __hlist_bl_del(&dentry->d_hash); |
| 502 | dentry->d_hash.pprev = NULL; |
| 503 | hlist_bl_unlock(b); |
| 504 | } |
| 505 | } |
| 506 | |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 507 | /** |
| 508 | * d_drop - drop a dentry |
| 509 | * @dentry: dentry to drop |
| 510 | * |
| 511 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't |
| 512 | * be found through a VFS lookup any more. Note that this is different from |
| 513 | * deleting the dentry - d_delete will try to mark the dentry negative if |
| 514 | * possible, giving a successful _negative_ lookup, while d_drop will |
| 515 | * just make the cache lookup fail. |
| 516 | * |
| 517 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some |
| 518 | * reason (NFS timeouts or autofs deletes). |
| 519 | * |
| 520 | * __d_drop requires dentry->d_lock. |
| 521 | */ |
| 522 | void __d_drop(struct dentry *dentry) |
| 523 | { |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 524 | if (!d_unhashed(dentry)) { |
David Howells | c6627c6 | 2011-06-07 14:09:20 +0100 | [diff] [blame] | 525 | __d_shrink(dentry); |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 526 | dentry_rcuwalk_barrier(dentry); |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 527 | } |
| 528 | } |
| 529 | EXPORT_SYMBOL(__d_drop); |
| 530 | |
| 531 | void d_drop(struct dentry *dentry) |
| 532 | { |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 533 | spin_lock(&dentry->d_lock); |
| 534 | __d_drop(dentry); |
| 535 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 536 | } |
| 537 | EXPORT_SYMBOL(d_drop); |
| 538 | |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 539 | /* |
| 540 | * Finish off a dentry we've decided to kill. |
| 541 | * dentry->d_lock must be held, returns with it unlocked. |
| 542 | * If ref is non-zero, then decrement the refcount too. |
| 543 | * Returns dentry requiring refcount drop, or NULL if we're done. |
| 544 | */ |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 545 | static inline struct dentry * |
| 546 | dentry_kill(struct dentry *dentry, int unlock_on_failure) |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 547 | __releases(dentry->d_lock) |
| 548 | { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 549 | struct inode *inode; |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 550 | struct dentry *parent; |
| 551 | |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 552 | inode = dentry->d_inode; |
| 553 | if (inode && !spin_trylock(&inode->i_lock)) { |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 554 | relock: |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 555 | if (unlock_on_failure) { |
| 556 | spin_unlock(&dentry->d_lock); |
| 557 | cpu_relax(); |
| 558 | } |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 559 | return dentry; /* try again with same dentry */ |
| 560 | } |
| 561 | if (IS_ROOT(dentry)) |
| 562 | parent = NULL; |
| 563 | else |
| 564 | parent = dentry->d_parent; |
| 565 | if (parent && !spin_trylock(&parent->d_lock)) { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 566 | if (inode) |
| 567 | spin_unlock(&inode->i_lock); |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 568 | goto relock; |
| 569 | } |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 570 | |
Linus Torvalds | 0d98439 | 2013-09-08 13:46:52 -0700 | [diff] [blame] | 571 | /* |
| 572 | * The dentry is now unrecoverably dead to the world. |
| 573 | */ |
| 574 | lockref_mark_dead(&dentry->d_lockref); |
| 575 | |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 576 | /* |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 577 | * inform the fs via d_prune that this dentry is about to be |
| 578 | * unhashed and destroyed. |
| 579 | */ |
Yan, Zheng | 590fb51 | 2013-08-13 15:42:02 +0800 | [diff] [blame] | 580 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry)) |
Yan, Zheng | 61572bb | 2013-04-15 14:13:21 +0800 | [diff] [blame] | 581 | dentry->d_op->d_prune(dentry); |
| 582 | |
| 583 | dentry_lru_del(dentry); |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 584 | /* if it was on the hash then remove it */ |
| 585 | __d_drop(dentry); |
| 586 | return d_kill(dentry, parent); |
| 587 | } |
| 588 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 589 | /* |
| 590 | * This is dput |
| 591 | * |
| 592 | * This is complicated by the fact that we do not want to put |
| 593 | * dentries that are no longer on any hash chain on the unused |
| 594 | * list: we'd much rather just get rid of them immediately. |
| 595 | * |
| 596 | * However, that implies that we have to traverse the dentry |
| 597 | * tree upwards to the parents which might _also_ now be |
| 598 | * scheduled for deletion (it may have been only waiting for |
| 599 | * its last child to go away). |
| 600 | * |
| 601 | * This tail recursion is done by hand as we don't want to depend |
| 602 | * on the compiler to always get this right (gcc generally doesn't). |
| 603 | * Real recursion would eat up our stack space. |
| 604 | */ |
| 605 | |
| 606 | /* |
| 607 | * dput - release a dentry |
| 608 | * @dentry: dentry to release |
| 609 | * |
| 610 | * Release a dentry. This will drop the usage count and if appropriate |
| 611 | * call the dentry unlink method as well as removing it from the queues and |
| 612 | * releasing its resources. If the parent dentries were scheduled for release |
| 613 | * they too may now get deleted. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 614 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 615 | void dput(struct dentry *dentry) |
| 616 | { |
Linus Torvalds | 8aab6a2 | 2013-09-08 13:26:18 -0700 | [diff] [blame] | 617 | if (unlikely(!dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 618 | return; |
| 619 | |
| 620 | repeat: |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 621 | if (lockref_put_or_lock(&dentry->d_lockref)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 622 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 623 | |
Linus Torvalds | 8aab6a2 | 2013-09-08 13:26:18 -0700 | [diff] [blame] | 624 | /* Unreachable? Get rid of it */ |
| 625 | if (unlikely(d_unhashed(dentry))) |
| 626 | goto kill_it; |
| 627 | |
| 628 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 629 | if (dentry->d_op->d_delete(dentry)) |
Nick Piggin | 61f3dee | 2011-01-07 17:49:40 +1100 | [diff] [blame] | 630 | goto kill_it; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 631 | } |
Nick Piggin | 265ac90 | 2010-10-10 05:36:24 -0400 | [diff] [blame] | 632 | |
Jeff Layton | 39e3c95 | 2012-11-28 11:30:53 -0500 | [diff] [blame] | 633 | dentry->d_flags |= DCACHE_REFERENCED; |
Christoph Hellwig | a463335 | 2010-10-10 05:36:26 -0400 | [diff] [blame] | 634 | dentry_lru_add(dentry); |
Nick Piggin | 265ac90 | 2010-10-10 05:36:24 -0400 | [diff] [blame] | 635 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 636 | dentry->d_lockref.count--; |
Nick Piggin | 61f3dee | 2011-01-07 17:49:40 +1100 | [diff] [blame] | 637 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 638 | return; |
| 639 | |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 640 | kill_it: |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 641 | dentry = dentry_kill(dentry, 1); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 642 | if (dentry) |
| 643 | goto repeat; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 644 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 645 | EXPORT_SYMBOL(dput); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 646 | |
| 647 | /** |
| 648 | * d_invalidate - invalidate a dentry |
| 649 | * @dentry: dentry to invalidate |
| 650 | * |
| 651 | * Try to invalidate the dentry if it turns out to be |
| 652 | * possible. If there are other dentries that can be |
| 653 | * reached through this one we can't delete it and we |
| 654 | * return -EBUSY. On success we return 0. |
| 655 | * |
| 656 | * no dcache lock. |
| 657 | */ |
| 658 | |
| 659 | int d_invalidate(struct dentry * dentry) |
| 660 | { |
| 661 | /* |
| 662 | * If it's already been dropped, return OK. |
| 663 | */ |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 664 | spin_lock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 665 | if (d_unhashed(dentry)) { |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 666 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 667 | return 0; |
| 668 | } |
| 669 | /* |
| 670 | * Check whether to do a partial shrink_dcache |
| 671 | * to get rid of unused child entries. |
| 672 | */ |
| 673 | if (!list_empty(&dentry->d_subdirs)) { |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 674 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 675 | shrink_dcache_parent(dentry); |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 676 | spin_lock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 677 | } |
| 678 | |
| 679 | /* |
| 680 | * Somebody else still using it? |
| 681 | * |
| 682 | * If it's a directory, we can't drop it |
| 683 | * for fear of somebody re-populating it |
| 684 | * with children (even though dropping it |
| 685 | * would make it unreachable from the root, |
| 686 | * we might still populate it if it was a |
| 687 | * working directory or similar). |
Al Viro | 50e6963 | 2011-11-07 16:39:57 +0000 | [diff] [blame] | 688 | * We also need to leave mountpoints alone, |
| 689 | * directory or not. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 690 | */ |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 691 | if (dentry->d_lockref.count > 1 && dentry->d_inode) { |
Al Viro | 50e6963 | 2011-11-07 16:39:57 +0000 | [diff] [blame] | 692 | if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 693 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 694 | return -EBUSY; |
| 695 | } |
| 696 | } |
| 697 | |
| 698 | __d_drop(dentry); |
| 699 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 700 | return 0; |
| 701 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 702 | EXPORT_SYMBOL(d_invalidate); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 703 | |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 704 | /* This must be called with d_lock held */ |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 705 | static inline void __dget_dlock(struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 706 | { |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 707 | dentry->d_lockref.count++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 708 | } |
| 709 | |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 710 | static inline void __dget(struct dentry *dentry) |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 711 | { |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 712 | lockref_get(&dentry->d_lockref); |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 713 | } |
| 714 | |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 715 | struct dentry *dget_parent(struct dentry *dentry) |
| 716 | { |
Waiman Long | df3d0bb | 2013-09-02 11:29:22 -0700 | [diff] [blame] | 717 | int gotref; |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 718 | struct dentry *ret; |
| 719 | |
Waiman Long | df3d0bb | 2013-09-02 11:29:22 -0700 | [diff] [blame] | 720 | /* |
| 721 | * Do optimistic parent lookup without any |
| 722 | * locking. |
| 723 | */ |
| 724 | rcu_read_lock(); |
| 725 | ret = ACCESS_ONCE(dentry->d_parent); |
| 726 | gotref = lockref_get_not_zero(&ret->d_lockref); |
| 727 | rcu_read_unlock(); |
| 728 | if (likely(gotref)) { |
| 729 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) |
| 730 | return ret; |
| 731 | dput(ret); |
| 732 | } |
| 733 | |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 734 | repeat: |
Nick Piggin | a734eb4 | 2011-01-07 17:49:44 +1100 | [diff] [blame] | 735 | /* |
| 736 | * Don't need rcu_dereference because we re-check it was correct under |
| 737 | * the lock. |
| 738 | */ |
| 739 | rcu_read_lock(); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 740 | ret = dentry->d_parent; |
Nick Piggin | a734eb4 | 2011-01-07 17:49:44 +1100 | [diff] [blame] | 741 | spin_lock(&ret->d_lock); |
| 742 | if (unlikely(ret != dentry->d_parent)) { |
| 743 | spin_unlock(&ret->d_lock); |
| 744 | rcu_read_unlock(); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 745 | goto repeat; |
| 746 | } |
Nick Piggin | a734eb4 | 2011-01-07 17:49:44 +1100 | [diff] [blame] | 747 | rcu_read_unlock(); |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 748 | BUG_ON(!ret->d_lockref.count); |
| 749 | ret->d_lockref.count++; |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 750 | spin_unlock(&ret->d_lock); |
Nick Piggin | b7ab39f | 2011-01-07 17:49:32 +1100 | [diff] [blame] | 751 | return ret; |
| 752 | } |
| 753 | EXPORT_SYMBOL(dget_parent); |
| 754 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 755 | /** |
| 756 | * d_find_alias - grab a hashed alias of inode |
| 757 | * @inode: inode in question |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 758 | * @want_discon: flag, used by d_splice_alias, to request |
| 759 | * that only a DISCONNECTED alias be returned. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 760 | * |
| 761 | * If inode has a hashed alias, or is a directory and has any alias, |
| 762 | * acquire the reference to alias and return it. Otherwise return NULL. |
| 763 | * Notice that if inode is a directory there can be only one alias and |
| 764 | * it can be unhashed only if it has no children, or if it is the root |
| 765 | * of a filesystem. |
| 766 | * |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 767 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 768 | * any other hashed alias over that one unless @want_discon is set, |
| 769 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 770 | */ |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 771 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 772 | { |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 773 | struct dentry *alias, *discon_alias; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 774 | |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 775 | again: |
| 776 | discon_alias = NULL; |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 777 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 778 | spin_lock(&alias->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 779 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 780 | if (IS_ROOT(alias) && |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 781 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 782 | discon_alias = alias; |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 783 | } else if (!want_discon) { |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 784 | __dget_dlock(alias); |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 785 | spin_unlock(&alias->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 786 | return alias; |
| 787 | } |
| 788 | } |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 789 | spin_unlock(&alias->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 790 | } |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 791 | if (discon_alias) { |
| 792 | alias = discon_alias; |
| 793 | spin_lock(&alias->d_lock); |
| 794 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
| 795 | if (IS_ROOT(alias) && |
| 796 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 797 | __dget_dlock(alias); |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 798 | spin_unlock(&alias->d_lock); |
| 799 | return alias; |
| 800 | } |
| 801 | } |
| 802 | spin_unlock(&alias->d_lock); |
| 803 | goto again; |
| 804 | } |
| 805 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 806 | } |
| 807 | |
Nick Piggin | da50295 | 2011-01-07 17:49:33 +1100 | [diff] [blame] | 808 | struct dentry *d_find_alias(struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 809 | { |
David Howells | 214fda1 | 2006-03-25 03:06:36 -0800 | [diff] [blame] | 810 | struct dentry *de = NULL; |
| 811 | |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 812 | if (!hlist_empty(&inode->i_dentry)) { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 813 | spin_lock(&inode->i_lock); |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 814 | de = __d_find_alias(inode, 0); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 815 | spin_unlock(&inode->i_lock); |
David Howells | 214fda1 | 2006-03-25 03:06:36 -0800 | [diff] [blame] | 816 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 817 | return de; |
| 818 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 819 | EXPORT_SYMBOL(d_find_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 820 | |
| 821 | /* |
| 822 | * Try to kill dentries associated with this inode. |
| 823 | * WARNING: you must own a reference to inode. |
| 824 | */ |
| 825 | void d_prune_aliases(struct inode *inode) |
| 826 | { |
Domen Puncer | 0cdca3f | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 827 | struct dentry *dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 828 | restart: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 829 | spin_lock(&inode->i_lock); |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 830 | hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 831 | spin_lock(&dentry->d_lock); |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 832 | if (!dentry->d_lockref.count) { |
Yan, Zheng | 590fb51 | 2013-08-13 15:42:02 +0800 | [diff] [blame] | 833 | /* |
| 834 | * inform the fs via d_prune that this dentry |
| 835 | * is about to be unhashed and destroyed. |
| 836 | */ |
| 837 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && |
| 838 | !d_unhashed(dentry)) |
| 839 | dentry->d_op->d_prune(dentry); |
| 840 | |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 841 | __dget_dlock(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 842 | __d_drop(dentry); |
| 843 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 844 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 845 | dput(dentry); |
| 846 | goto restart; |
| 847 | } |
| 848 | spin_unlock(&dentry->d_lock); |
| 849 | } |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 850 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 851 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 852 | EXPORT_SYMBOL(d_prune_aliases); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 853 | |
| 854 | /* |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 855 | * Try to throw away a dentry - free the inode, dput the parent. |
| 856 | * Requires dentry->d_lock is held, and dentry->d_count == 0. |
| 857 | * Releases dentry->d_lock. |
Andrew Morton | d702ccb | 2006-06-22 14:47:31 -0700 | [diff] [blame] | 858 | * |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 859 | * This may fail if locks cannot be acquired no problem, just try again. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 860 | */ |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 861 | static struct dentry * try_prune_one_dentry(struct dentry *dentry) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 862 | __releases(dentry->d_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 863 | { |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 864 | struct dentry *parent; |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 865 | |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 866 | parent = dentry_kill(dentry, 0); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 867 | /* |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 868 | * If dentry_kill returns NULL, we have nothing more to do. |
| 869 | * if it returns the same dentry, trylocks failed. In either |
| 870 | * case, just loop again. |
| 871 | * |
| 872 | * Otherwise, we need to prune ancestors too. This is necessary |
| 873 | * to prevent quadratic behavior of shrink_dcache_parent(), but |
| 874 | * is also expected to be beneficial in reducing dentry cache |
| 875 | * fragmentation. |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 876 | */ |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 877 | if (!parent) |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 878 | return NULL; |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 879 | if (parent == dentry) |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 880 | return dentry; |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 881 | |
| 882 | /* Prune ancestors. */ |
| 883 | dentry = parent; |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 884 | while (dentry) { |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 885 | if (lockref_put_or_lock(&dentry->d_lockref)) |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 886 | return NULL; |
| 887 | dentry = dentry_kill(dentry, 1); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 888 | } |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 889 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 890 | } |
| 891 | |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 892 | static void shrink_dentry_list(struct list_head *list) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 893 | { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 894 | struct dentry *dentry; |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 895 | |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 896 | rcu_read_lock(); |
| 897 | for (;;) { |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 898 | dentry = list_entry_rcu(list->prev, struct dentry, d_lru); |
| 899 | if (&dentry->d_lru == list) |
| 900 | break; /* empty */ |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 901 | |
| 902 | /* |
| 903 | * Get the dentry lock, and re-verify that the dentry is |
| 904 | * this on the shrinking list. If it is, we know that |
| 905 | * DCACHE_SHRINK_LIST and DCACHE_LRU_LIST are set. |
| 906 | */ |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 907 | spin_lock(&dentry->d_lock); |
| 908 | if (dentry != list_entry(list->prev, struct dentry, d_lru)) { |
| 909 | spin_unlock(&dentry->d_lock); |
Nick Piggin | 2304450 | 2011-01-07 17:49:31 +1100 | [diff] [blame] | 910 | continue; |
| 911 | } |
| 912 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 913 | /* |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 914 | * The dispose list is isolated and dentries are not accounted |
| 915 | * to the LRU here, so we can simply remove it from the list |
| 916 | * here regardless of whether it is referenced or not. |
| 917 | */ |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 918 | d_shrink_del(dentry); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 919 | |
| 920 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 921 | * We found an inuse dentry which was not removed from |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 922 | * the LRU because of laziness during lookup. Do not free it. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 923 | */ |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 924 | if (dentry->d_lockref.count) { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 925 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 926 | continue; |
| 927 | } |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 928 | rcu_read_unlock(); |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 929 | |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 930 | /* |
| 931 | * If 'try_to_prune()' returns a dentry, it will |
| 932 | * be the same one we passed in, and d_lock will |
| 933 | * have been held the whole time, so it will not |
| 934 | * have been added to any other lists. We failed |
| 935 | * to get the inode lock. |
| 936 | * |
| 937 | * We just add it back to the shrink list. |
| 938 | */ |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 939 | dentry = try_prune_one_dentry(dentry); |
Nick Piggin | 77812a1 | 2011-01-07 17:49:48 +1100 | [diff] [blame] | 940 | |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 941 | rcu_read_lock(); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 942 | if (dentry) { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 943 | d_shrink_add(dentry, list); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 944 | spin_unlock(&dentry->d_lock); |
| 945 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 946 | } |
Nick Piggin | ec33679 | 2011-01-07 17:49:47 +1100 | [diff] [blame] | 947 | rcu_read_unlock(); |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 948 | } |
| 949 | |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 950 | static enum lru_status |
| 951 | dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) |
| 952 | { |
| 953 | struct list_head *freeable = arg; |
| 954 | struct dentry *dentry = container_of(item, struct dentry, d_lru); |
| 955 | |
| 956 | |
| 957 | /* |
| 958 | * we are inverting the lru lock/dentry->d_lock here, |
| 959 | * so use a trylock. If we fail to get the lock, just skip |
| 960 | * it |
| 961 | */ |
| 962 | if (!spin_trylock(&dentry->d_lock)) |
| 963 | return LRU_SKIP; |
| 964 | |
| 965 | /* |
| 966 | * Referenced dentries are still in use. If they have active |
| 967 | * counts, just remove them from the LRU. Otherwise give them |
| 968 | * another pass through the LRU. |
| 969 | */ |
| 970 | if (dentry->d_lockref.count) { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 971 | d_lru_isolate(dentry); |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 972 | spin_unlock(&dentry->d_lock); |
| 973 | return LRU_REMOVED; |
| 974 | } |
| 975 | |
| 976 | if (dentry->d_flags & DCACHE_REFERENCED) { |
| 977 | dentry->d_flags &= ~DCACHE_REFERENCED; |
| 978 | spin_unlock(&dentry->d_lock); |
| 979 | |
| 980 | /* |
| 981 | * The list move itself will be made by the common LRU code. At |
| 982 | * this point, we've dropped the dentry->d_lock but keep the |
| 983 | * lru lock. This is safe to do, since every list movement is |
| 984 | * protected by the lru lock even if both locks are held. |
| 985 | * |
| 986 | * This is guaranteed by the fact that all LRU management |
| 987 | * functions are intermediated by the LRU API calls like |
| 988 | * list_lru_add and list_lru_del. List movement in this file |
| 989 | * only ever occur through this functions or through callbacks |
| 990 | * like this one, that are called from the LRU API. |
| 991 | * |
| 992 | * The only exceptions to this are functions like |
| 993 | * shrink_dentry_list, and code that first checks for the |
| 994 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be |
| 995 | * operating only with stack provided lists after they are |
| 996 | * properly isolated from the main list. It is thus, always a |
| 997 | * local access. |
| 998 | */ |
| 999 | return LRU_ROTATE; |
| 1000 | } |
| 1001 | |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 1002 | d_lru_shrink_move(dentry, freeable); |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1003 | spin_unlock(&dentry->d_lock); |
| 1004 | |
| 1005 | return LRU_REMOVED; |
| 1006 | } |
| 1007 | |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1008 | /** |
Dave Chinner | b48f03b | 2011-08-23 18:56:24 +1000 | [diff] [blame] | 1009 | * prune_dcache_sb - shrink the dcache |
| 1010 | * @sb: superblock |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1011 | * @nr_to_scan : number of entries to try to free |
Dave Chinner | 9b17c62 | 2013-08-28 10:18:05 +1000 | [diff] [blame] | 1012 | * @nid: which node to scan for freeable entities |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1013 | * |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1014 | * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is |
Dave Chinner | b48f03b | 2011-08-23 18:56:24 +1000 | [diff] [blame] | 1015 | * done when we need more memory an called from the superblock shrinker |
| 1016 | * function. |
| 1017 | * |
| 1018 | * This function may fail to free any resources if all the dentries are in |
| 1019 | * use. |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1020 | */ |
Dave Chinner | 9b17c62 | 2013-08-28 10:18:05 +1000 | [diff] [blame] | 1021 | long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan, |
| 1022 | int nid) |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1023 | { |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1024 | LIST_HEAD(dispose); |
| 1025 | long freed; |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1026 | |
Dave Chinner | 9b17c62 | 2013-08-28 10:18:05 +1000 | [diff] [blame] | 1027 | freed = list_lru_walk_node(&sb->s_dentry_lru, nid, dentry_lru_isolate, |
| 1028 | &dispose, &nr_to_scan); |
Dave Chinner | f604156 | 2013-08-28 10:18:00 +1000 | [diff] [blame] | 1029 | shrink_dentry_list(&dispose); |
Dave Chinner | 0a234c6 | 2013-08-28 10:17:57 +1000 | [diff] [blame] | 1030 | return freed; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1031 | } |
| 1032 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1033 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
| 1034 | spinlock_t *lru_lock, void *arg) |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 1035 | { |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1036 | struct list_head *freeable = arg; |
| 1037 | struct dentry *dentry = container_of(item, struct dentry, d_lru); |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 1038 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1039 | /* |
| 1040 | * we are inverting the lru lock/dentry->d_lock here, |
| 1041 | * so use a trylock. If we fail to get the lock, just skip |
| 1042 | * it |
| 1043 | */ |
| 1044 | if (!spin_trylock(&dentry->d_lock)) |
| 1045 | return LRU_SKIP; |
| 1046 | |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 1047 | d_lru_shrink_move(dentry, freeable); |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1048 | spin_unlock(&dentry->d_lock); |
| 1049 | |
| 1050 | return LRU_REMOVED; |
Dave Chinner | dd1f6b2 | 2013-08-28 10:17:55 +1000 | [diff] [blame] | 1051 | } |
| 1052 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1053 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame] | 1054 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1055 | * shrink_dcache_sb - shrink dcache for a superblock |
| 1056 | * @sb: superblock |
| 1057 | * |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1058 | * Shrink the dcache for the specified super block. This is used to free |
| 1059 | * the dcache before unmounting a file system. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1060 | */ |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1061 | void shrink_dcache_sb(struct super_block *sb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1062 | { |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1063 | long freed; |
Christoph Hellwig | 3049cfe | 2010-10-10 05:36:25 -0400 | [diff] [blame] | 1064 | |
Glauber Costa | 4e717f5 | 2013-08-28 10:18:03 +1000 | [diff] [blame] | 1065 | do { |
| 1066 | LIST_HEAD(dispose); |
| 1067 | |
| 1068 | freed = list_lru_walk(&sb->s_dentry_lru, |
| 1069 | dentry_lru_isolate_shrink, &dispose, UINT_MAX); |
| 1070 | |
| 1071 | this_cpu_sub(nr_dentry_unused, freed); |
| 1072 | shrink_dentry_list(&dispose); |
| 1073 | } while (freed > 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1074 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1075 | EXPORT_SYMBOL(shrink_dcache_sb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1076 | |
| 1077 | /* |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1078 | * destroy a single subtree of dentries for unmount |
| 1079 | * - see the comments on shrink_dcache_for_umount() for a description of the |
| 1080 | * locking |
| 1081 | */ |
| 1082 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) |
| 1083 | { |
| 1084 | struct dentry *parent; |
| 1085 | |
| 1086 | BUG_ON(!IS_ROOT(dentry)); |
| 1087 | |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1088 | for (;;) { |
| 1089 | /* descend to the first leaf in the current subtree */ |
David Howells | 43c1c9c | 2011-06-07 14:09:30 +0100 | [diff] [blame] | 1090 | while (!list_empty(&dentry->d_subdirs)) |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1091 | dentry = list_entry(dentry->d_subdirs.next, |
| 1092 | struct dentry, d_u.d_child); |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1093 | |
| 1094 | /* consume the dentries from this leaf up through its parents |
| 1095 | * until we find one with children or run out altogether */ |
| 1096 | do { |
| 1097 | struct inode *inode; |
| 1098 | |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 1099 | /* |
Yan, Zheng | 61572bb | 2013-04-15 14:13:21 +0800 | [diff] [blame] | 1100 | * inform the fs that this dentry is about to be |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 1101 | * unhashed and destroyed. |
| 1102 | */ |
Yan, Zheng | 590fb51 | 2013-08-13 15:42:02 +0800 | [diff] [blame] | 1103 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && |
| 1104 | !d_unhashed(dentry)) |
Yan, Zheng | 61572bb | 2013-04-15 14:13:21 +0800 | [diff] [blame] | 1105 | dentry->d_op->d_prune(dentry); |
| 1106 | |
| 1107 | dentry_lru_del(dentry); |
David Howells | 43c1c9c | 2011-06-07 14:09:30 +0100 | [diff] [blame] | 1108 | __d_shrink(dentry); |
| 1109 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 1110 | if (dentry->d_lockref.count != 0) { |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1111 | printk(KERN_ERR |
| 1112 | "BUG: Dentry %p{i=%lx,n=%s}" |
| 1113 | " still in use (%d)" |
| 1114 | " [unmount of %s %s]\n", |
| 1115 | dentry, |
| 1116 | dentry->d_inode ? |
| 1117 | dentry->d_inode->i_ino : 0UL, |
| 1118 | dentry->d_name.name, |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 1119 | dentry->d_lockref.count, |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1120 | dentry->d_sb->s_type->name, |
| 1121 | dentry->d_sb->s_id); |
| 1122 | BUG(); |
| 1123 | } |
| 1124 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1125 | if (IS_ROOT(dentry)) { |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1126 | parent = NULL; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1127 | list_del(&dentry->d_u.d_child); |
| 1128 | } else { |
OGAWA Hirofumi | 871c006 | 2008-10-16 07:50:27 +0900 | [diff] [blame] | 1129 | parent = dentry->d_parent; |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 1130 | parent->d_lockref.count--; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1131 | list_del(&dentry->d_u.d_child); |
OGAWA Hirofumi | 871c006 | 2008-10-16 07:50:27 +0900 | [diff] [blame] | 1132 | } |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1133 | |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1134 | inode = dentry->d_inode; |
| 1135 | if (inode) { |
| 1136 | dentry->d_inode = NULL; |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1137 | hlist_del_init(&dentry->d_alias); |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1138 | if (dentry->d_op && dentry->d_op->d_iput) |
| 1139 | dentry->d_op->d_iput(dentry, inode); |
| 1140 | else |
| 1141 | iput(inode); |
| 1142 | } |
| 1143 | |
| 1144 | d_free(dentry); |
| 1145 | |
| 1146 | /* finished when we fall off the top of the tree, |
| 1147 | * otherwise we ascend to the parent and move to the |
| 1148 | * next sibling if there is one */ |
| 1149 | if (!parent) |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 1150 | return; |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1151 | dentry = parent; |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1152 | } while (list_empty(&dentry->d_subdirs)); |
| 1153 | |
| 1154 | dentry = list_entry(dentry->d_subdirs.next, |
| 1155 | struct dentry, d_u.d_child); |
| 1156 | } |
| 1157 | } |
| 1158 | |
| 1159 | /* |
| 1160 | * destroy the dentries attached to a superblock on unmounting |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 1161 | * - we don't need to use dentry->d_lock because: |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1162 | * - the superblock is detached from all mountings and open files, so the |
| 1163 | * dentry trees will not be rearranged by the VFS |
| 1164 | * - s_umount is write-locked, so the memory pressure shrinker will ignore |
| 1165 | * any dentries belonging to this superblock that it comes across |
| 1166 | * - the filesystem itself is no longer permitted to rearrange the dentries |
| 1167 | * in this superblock |
| 1168 | */ |
| 1169 | void shrink_dcache_for_umount(struct super_block *sb) |
| 1170 | { |
| 1171 | struct dentry *dentry; |
| 1172 | |
| 1173 | if (down_read_trylock(&sb->s_umount)) |
| 1174 | BUG(); |
| 1175 | |
| 1176 | dentry = sb->s_root; |
| 1177 | sb->s_root = NULL; |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 1178 | dentry->d_lockref.count--; |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1179 | shrink_dcache_for_umount_subtree(dentry); |
| 1180 | |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 1181 | while (!hlist_bl_empty(&sb->s_anon)) { |
| 1182 | dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 1183 | shrink_dcache_for_umount_subtree(dentry); |
| 1184 | } |
| 1185 | } |
| 1186 | |
| 1187 | /* |
Linus Torvalds | c826cb7 | 2011-03-15 15:29:21 -0700 | [diff] [blame] | 1188 | * This tries to ascend one level of parenthood, but |
| 1189 | * we can race with renaming, so we need to re-check |
| 1190 | * the parenthood after dropping the lock and check |
| 1191 | * that the sequence number still matches. |
| 1192 | */ |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1193 | static struct dentry *try_to_ascend(struct dentry *old, unsigned seq) |
Linus Torvalds | c826cb7 | 2011-03-15 15:29:21 -0700 | [diff] [blame] | 1194 | { |
| 1195 | struct dentry *new = old->d_parent; |
| 1196 | |
| 1197 | rcu_read_lock(); |
| 1198 | spin_unlock(&old->d_lock); |
| 1199 | spin_lock(&new->d_lock); |
| 1200 | |
| 1201 | /* |
| 1202 | * might go back up the wrong parent if we have had a rename |
| 1203 | * or deletion |
| 1204 | */ |
| 1205 | if (new != old->d_parent || |
Miklos Szeredi | b161dfa6 | 2012-09-17 22:31:38 +0200 | [diff] [blame] | 1206 | (old->d_flags & DCACHE_DENTRY_KILLED) || |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1207 | need_seqretry(&rename_lock, seq)) { |
Linus Torvalds | c826cb7 | 2011-03-15 15:29:21 -0700 | [diff] [blame] | 1208 | spin_unlock(&new->d_lock); |
| 1209 | new = NULL; |
| 1210 | } |
| 1211 | rcu_read_unlock(); |
| 1212 | return new; |
| 1213 | } |
| 1214 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1215 | /** |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1216 | * enum d_walk_ret - action to talke during tree walk |
| 1217 | * @D_WALK_CONTINUE: contrinue walk |
| 1218 | * @D_WALK_QUIT: quit walk |
| 1219 | * @D_WALK_NORETRY: quit when retry is needed |
| 1220 | * @D_WALK_SKIP: skip this dentry and its children |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1221 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1222 | enum d_walk_ret { |
| 1223 | D_WALK_CONTINUE, |
| 1224 | D_WALK_QUIT, |
| 1225 | D_WALK_NORETRY, |
| 1226 | D_WALK_SKIP, |
| 1227 | }; |
| 1228 | |
| 1229 | /** |
| 1230 | * d_walk - walk the dentry tree |
| 1231 | * @parent: start of walk |
| 1232 | * @data: data passed to @enter() and @finish() |
| 1233 | * @enter: callback when first entering the dentry |
| 1234 | * @finish: callback when successfully finished the walk |
| 1235 | * |
| 1236 | * The @enter() and @finish() callbacks are called with d_lock held. |
| 1237 | */ |
| 1238 | static void d_walk(struct dentry *parent, void *data, |
| 1239 | enum d_walk_ret (*enter)(void *, struct dentry *), |
| 1240 | void (*finish)(void *)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1241 | { |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1242 | struct dentry *this_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1243 | struct list_head *next; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1244 | unsigned seq = 0; |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1245 | enum d_walk_ret ret; |
| 1246 | bool retry = true; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1247 | |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1248 | again: |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1249 | read_seqbegin_or_lock(&rename_lock, &seq); |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1250 | this_parent = parent; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1251 | spin_lock(&this_parent->d_lock); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1252 | |
| 1253 | ret = enter(data, this_parent); |
| 1254 | switch (ret) { |
| 1255 | case D_WALK_CONTINUE: |
| 1256 | break; |
| 1257 | case D_WALK_QUIT: |
| 1258 | case D_WALK_SKIP: |
| 1259 | goto out_unlock; |
| 1260 | case D_WALK_NORETRY: |
| 1261 | retry = false; |
| 1262 | break; |
| 1263 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1264 | repeat: |
| 1265 | next = this_parent->d_subdirs.next; |
| 1266 | resume: |
| 1267 | while (next != &this_parent->d_subdirs) { |
| 1268 | struct list_head *tmp = next; |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 1269 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1270 | next = tmp->next; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1271 | |
| 1272 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1273 | |
| 1274 | ret = enter(data, dentry); |
| 1275 | switch (ret) { |
| 1276 | case D_WALK_CONTINUE: |
| 1277 | break; |
| 1278 | case D_WALK_QUIT: |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1279 | spin_unlock(&dentry->d_lock); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1280 | goto out_unlock; |
| 1281 | case D_WALK_NORETRY: |
| 1282 | retry = false; |
| 1283 | break; |
| 1284 | case D_WALK_SKIP: |
| 1285 | spin_unlock(&dentry->d_lock); |
| 1286 | continue; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1287 | } |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1288 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1289 | if (!list_empty(&dentry->d_subdirs)) { |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1290 | spin_unlock(&this_parent->d_lock); |
| 1291 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1292 | this_parent = dentry; |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1293 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1294 | goto repeat; |
| 1295 | } |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1296 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1297 | } |
| 1298 | /* |
| 1299 | * All done at this level ... ascend and resume the search. |
| 1300 | */ |
| 1301 | if (this_parent != parent) { |
Linus Torvalds | c826cb7 | 2011-03-15 15:29:21 -0700 | [diff] [blame] | 1302 | struct dentry *child = this_parent; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1303 | this_parent = try_to_ascend(this_parent, seq); |
Linus Torvalds | c826cb7 | 2011-03-15 15:29:21 -0700 | [diff] [blame] | 1304 | if (!this_parent) |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1305 | goto rename_retry; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 1306 | next = child->d_u.d_child.next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1307 | goto resume; |
| 1308 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1309 | if (need_seqretry(&rename_lock, seq)) { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1310 | spin_unlock(&this_parent->d_lock); |
| 1311 | goto rename_retry; |
| 1312 | } |
| 1313 | if (finish) |
| 1314 | finish(data); |
| 1315 | |
| 1316 | out_unlock: |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1317 | spin_unlock(&this_parent->d_lock); |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1318 | done_seqretry(&rename_lock, seq); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1319 | return; |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1320 | |
| 1321 | rename_retry: |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1322 | if (!retry) |
| 1323 | return; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 1324 | seq = 1; |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 1325 | goto again; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1326 | } |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1327 | |
| 1328 | /* |
| 1329 | * Search for at least 1 mount point in the dentry's subdirs. |
| 1330 | * We descend to the next level whenever the d_subdirs |
| 1331 | * list is non-empty and continue searching. |
| 1332 | */ |
| 1333 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1334 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
| 1335 | { |
| 1336 | int *ret = data; |
| 1337 | if (d_mountpoint(dentry)) { |
| 1338 | *ret = 1; |
| 1339 | return D_WALK_QUIT; |
| 1340 | } |
| 1341 | return D_WALK_CONTINUE; |
| 1342 | } |
| 1343 | |
Randy Dunlap | 69c88dc | 2013-10-19 14:57:07 -0700 | [diff] [blame] | 1344 | /** |
| 1345 | * have_submounts - check for mounts over a dentry |
| 1346 | * @parent: dentry to check. |
| 1347 | * |
| 1348 | * Return true if the parent or its subdirectories contain |
| 1349 | * a mount point |
| 1350 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1351 | int have_submounts(struct dentry *parent) |
| 1352 | { |
| 1353 | int ret = 0; |
| 1354 | |
| 1355 | d_walk(parent, &ret, check_mount, NULL); |
| 1356 | |
| 1357 | return ret; |
| 1358 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1359 | EXPORT_SYMBOL(have_submounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1360 | |
| 1361 | /* |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 1362 | * Called by mount code to set a mountpoint and check if the mountpoint is |
| 1363 | * reachable (e.g. NFS can unhash a directory dentry and then the complete |
| 1364 | * subtree can become unreachable). |
| 1365 | * |
| 1366 | * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For |
| 1367 | * this reason take rename_lock and d_lock on dentry and ancestors. |
| 1368 | */ |
| 1369 | int d_set_mounted(struct dentry *dentry) |
| 1370 | { |
| 1371 | struct dentry *p; |
| 1372 | int ret = -ENOENT; |
| 1373 | write_seqlock(&rename_lock); |
| 1374 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { |
| 1375 | /* Need exclusion wrt. check_submounts_and_drop() */ |
| 1376 | spin_lock(&p->d_lock); |
| 1377 | if (unlikely(d_unhashed(p))) { |
| 1378 | spin_unlock(&p->d_lock); |
| 1379 | goto out; |
| 1380 | } |
| 1381 | spin_unlock(&p->d_lock); |
| 1382 | } |
| 1383 | spin_lock(&dentry->d_lock); |
| 1384 | if (!d_unlinked(dentry)) { |
| 1385 | dentry->d_flags |= DCACHE_MOUNTED; |
| 1386 | ret = 0; |
| 1387 | } |
| 1388 | spin_unlock(&dentry->d_lock); |
| 1389 | out: |
| 1390 | write_sequnlock(&rename_lock); |
| 1391 | return ret; |
| 1392 | } |
| 1393 | |
| 1394 | /* |
J. Bruce Fields | fd51790 | 2012-09-18 16:35:51 -0400 | [diff] [blame] | 1395 | * Search the dentry child list of the specified parent, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1396 | * and move any unused dentries to the end of the unused |
| 1397 | * list for prune_dcache(). We descend to the next level |
| 1398 | * whenever the d_subdirs list is non-empty and continue |
| 1399 | * searching. |
| 1400 | * |
| 1401 | * It returns zero iff there are no unused children, |
| 1402 | * otherwise it returns the number of children moved to |
| 1403 | * the end of the unused list. This may not be the total |
| 1404 | * number of unused children, because select_parent can |
| 1405 | * drop the lock and return early due to latency |
| 1406 | * constraints. |
| 1407 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1408 | |
| 1409 | struct select_data { |
| 1410 | struct dentry *start; |
| 1411 | struct list_head dispose; |
| 1412 | int found; |
| 1413 | }; |
| 1414 | |
| 1415 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1416 | { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1417 | struct select_data *data = _data; |
| 1418 | enum d_walk_ret ret = D_WALK_CONTINUE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1419 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1420 | if (data->start == dentry) |
| 1421 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1422 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1423 | /* |
| 1424 | * move only zero ref count dentries to the dispose list. |
| 1425 | * |
| 1426 | * Those which are presently on the shrink list, being processed |
| 1427 | * by shrink_dentry_list(), shouldn't be moved. Otherwise the |
| 1428 | * loop in shrink_dcache_parent() might not make any progress |
| 1429 | * and loop forever. |
| 1430 | */ |
| 1431 | if (dentry->d_lockref.count) { |
| 1432 | dentry_lru_del(dentry); |
| 1433 | } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 1434 | /* |
| 1435 | * We can't use d_lru_shrink_move() because we |
| 1436 | * need to get the global LRU lock and do the |
Linus Torvalds | 05a8252 | 2013-09-15 07:11:01 -0400 | [diff] [blame] | 1437 | * LRU accounting. |
Linus Torvalds | 89dc77b | 2013-09-13 22:55:10 -0400 | [diff] [blame] | 1438 | */ |
| 1439 | d_lru_del(dentry); |
| 1440 | d_shrink_add(dentry, &data->dispose); |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1441 | data->found++; |
| 1442 | ret = D_WALK_NORETRY; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1443 | } |
| 1444 | /* |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1445 | * We can return to the caller if we have found some (this |
| 1446 | * ensures forward progress). We'll be coming back to find |
| 1447 | * the rest. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1448 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1449 | if (data->found && need_resched()) |
| 1450 | ret = D_WALK_QUIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1451 | out: |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1452 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1453 | } |
| 1454 | |
| 1455 | /** |
| 1456 | * shrink_dcache_parent - prune dcache |
| 1457 | * @parent: parent of entries to prune |
| 1458 | * |
| 1459 | * Prune the dcache to remove unused children of the parent dentry. |
| 1460 | */ |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1461 | void shrink_dcache_parent(struct dentry *parent) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1462 | { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1463 | for (;;) { |
| 1464 | struct select_data data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1465 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 1466 | INIT_LIST_HEAD(&data.dispose); |
| 1467 | data.start = parent; |
| 1468 | data.found = 0; |
| 1469 | |
| 1470 | d_walk(parent, &data, select_collect, NULL); |
| 1471 | if (!data.found) |
| 1472 | break; |
| 1473 | |
| 1474 | shrink_dentry_list(&data.dispose); |
Greg Thelen | 421348f | 2013-04-30 15:26:48 -0700 | [diff] [blame] | 1475 | cond_resched(); |
| 1476 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1477 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1478 | EXPORT_SYMBOL(shrink_dcache_parent); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1479 | |
Miklos Szeredi | 848ac114 | 2013-09-05 11:44:36 +0200 | [diff] [blame] | 1480 | static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry) |
| 1481 | { |
| 1482 | struct select_data *data = _data; |
| 1483 | |
| 1484 | if (d_mountpoint(dentry)) { |
| 1485 | data->found = -EBUSY; |
| 1486 | return D_WALK_QUIT; |
| 1487 | } |
| 1488 | |
| 1489 | return select_collect(_data, dentry); |
| 1490 | } |
| 1491 | |
| 1492 | static void check_and_drop(void *_data) |
| 1493 | { |
| 1494 | struct select_data *data = _data; |
| 1495 | |
| 1496 | if (d_mountpoint(data->start)) |
| 1497 | data->found = -EBUSY; |
| 1498 | if (!data->found) |
| 1499 | __d_drop(data->start); |
| 1500 | } |
| 1501 | |
| 1502 | /** |
| 1503 | * check_submounts_and_drop - prune dcache, check for submounts and drop |
| 1504 | * |
| 1505 | * All done as a single atomic operation relative to has_unlinked_ancestor(). |
| 1506 | * Returns 0 if successfully unhashed @parent. If there were submounts then |
| 1507 | * return -EBUSY. |
| 1508 | * |
| 1509 | * @dentry: dentry to prune and drop |
| 1510 | */ |
| 1511 | int check_submounts_and_drop(struct dentry *dentry) |
| 1512 | { |
| 1513 | int ret = 0; |
| 1514 | |
| 1515 | /* Negative dentries can be dropped without further checks */ |
| 1516 | if (!dentry->d_inode) { |
| 1517 | d_drop(dentry); |
| 1518 | goto out; |
| 1519 | } |
| 1520 | |
| 1521 | for (;;) { |
| 1522 | struct select_data data; |
| 1523 | |
| 1524 | INIT_LIST_HEAD(&data.dispose); |
| 1525 | data.start = dentry; |
| 1526 | data.found = 0; |
| 1527 | |
| 1528 | d_walk(dentry, &data, check_and_collect, check_and_drop); |
| 1529 | ret = data.found; |
| 1530 | |
| 1531 | if (!list_empty(&data.dispose)) |
| 1532 | shrink_dentry_list(&data.dispose); |
| 1533 | |
| 1534 | if (ret <= 0) |
| 1535 | break; |
| 1536 | |
| 1537 | cond_resched(); |
| 1538 | } |
| 1539 | |
| 1540 | out: |
| 1541 | return ret; |
| 1542 | } |
| 1543 | EXPORT_SYMBOL(check_submounts_and_drop); |
| 1544 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1545 | /** |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1546 | * __d_alloc - allocate a dcache entry |
| 1547 | * @sb: filesystem it will belong to |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1548 | * @name: qstr of the name |
| 1549 | * |
| 1550 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 1551 | * available. On a success the dentry is returned. The name passed in is |
| 1552 | * copied and the copy passed in may be reused after this call. |
| 1553 | */ |
| 1554 | |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1555 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1556 | { |
| 1557 | struct dentry *dentry; |
| 1558 | char *dname; |
| 1559 | |
Mel Gorman | e12ba74 | 2007-10-16 01:25:52 -0700 | [diff] [blame] | 1560 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1561 | if (!dentry) |
| 1562 | return NULL; |
| 1563 | |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 1564 | /* |
| 1565 | * We guarantee that the inline name is always NUL-terminated. |
| 1566 | * This way the memcpy() done by the name switching in rename |
| 1567 | * will still always have a NUL at the end, even if we might |
| 1568 | * be overwriting an internal NUL character |
| 1569 | */ |
| 1570 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1571 | if (name->len > DNAME_INLINE_LEN-1) { |
| 1572 | dname = kmalloc(name->len + 1, GFP_KERNEL); |
| 1573 | if (!dname) { |
| 1574 | kmem_cache_free(dentry_cache, dentry); |
| 1575 | return NULL; |
| 1576 | } |
| 1577 | } else { |
| 1578 | dname = dentry->d_iname; |
| 1579 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1580 | |
| 1581 | dentry->d_name.len = name->len; |
| 1582 | dentry->d_name.hash = name->hash; |
| 1583 | memcpy(dname, name->name, name->len); |
| 1584 | dname[name->len] = 0; |
| 1585 | |
Linus Torvalds | 6326c71 | 2012-05-21 16:14:04 -0700 | [diff] [blame] | 1586 | /* Make sure we always see the terminating NUL character */ |
| 1587 | smp_wmb(); |
| 1588 | dentry->d_name.name = dname; |
| 1589 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 1590 | dentry->d_lockref.count = 1; |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 1591 | dentry->d_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1592 | spin_lock_init(&dentry->d_lock); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1593 | seqcount_init(&dentry->d_seq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1594 | dentry->d_inode = NULL; |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1595 | dentry->d_parent = dentry; |
| 1596 | dentry->d_sb = sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1597 | dentry->d_op = NULL; |
| 1598 | dentry->d_fsdata = NULL; |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 1599 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1600 | INIT_LIST_HEAD(&dentry->d_lru); |
| 1601 | INIT_LIST_HEAD(&dentry->d_subdirs); |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1602 | INIT_HLIST_NODE(&dentry->d_alias); |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 1603 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1604 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1605 | |
Nick Piggin | 3e880fb | 2011-01-07 17:49:19 +1100 | [diff] [blame] | 1606 | this_cpu_inc(nr_dentry); |
Christoph Hellwig | 312d3ca | 2010-10-10 05:36:23 -0400 | [diff] [blame] | 1607 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1608 | return dentry; |
| 1609 | } |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1610 | |
| 1611 | /** |
| 1612 | * d_alloc - allocate a dcache entry |
| 1613 | * @parent: parent of entry to allocate |
| 1614 | * @name: qstr of the name |
| 1615 | * |
| 1616 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 1617 | * available. On a success the dentry is returned. The name passed in is |
| 1618 | * copied and the copy passed in may be reused after this call. |
| 1619 | */ |
| 1620 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
| 1621 | { |
| 1622 | struct dentry *dentry = __d_alloc(parent->d_sb, name); |
| 1623 | if (!dentry) |
| 1624 | return NULL; |
| 1625 | |
| 1626 | spin_lock(&parent->d_lock); |
| 1627 | /* |
| 1628 | * don't need child lock because it is not subject |
| 1629 | * to concurrency here |
| 1630 | */ |
| 1631 | __dget_dlock(parent); |
| 1632 | dentry->d_parent = parent; |
| 1633 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
| 1634 | spin_unlock(&parent->d_lock); |
| 1635 | |
| 1636 | return dentry; |
| 1637 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1638 | EXPORT_SYMBOL(d_alloc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1639 | |
Nick Piggin | 4b93688 | 2011-01-07 17:50:07 +1100 | [diff] [blame] | 1640 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
| 1641 | { |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1642 | struct dentry *dentry = __d_alloc(sb, name); |
| 1643 | if (dentry) |
Nick Piggin | 4b93688 | 2011-01-07 17:50:07 +1100 | [diff] [blame] | 1644 | dentry->d_flags |= DCACHE_DISCONNECTED; |
Nick Piggin | 4b93688 | 2011-01-07 17:50:07 +1100 | [diff] [blame] | 1645 | return dentry; |
| 1646 | } |
| 1647 | EXPORT_SYMBOL(d_alloc_pseudo); |
| 1648 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1649 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
| 1650 | { |
| 1651 | struct qstr q; |
| 1652 | |
| 1653 | q.name = name; |
| 1654 | q.len = strlen(name); |
| 1655 | q.hash = full_name_hash(q.name, q.len); |
| 1656 | return d_alloc(parent, &q); |
| 1657 | } |
H Hartley Sweeten | ef26ca9 | 2009-09-29 20:09:42 -0400 | [diff] [blame] | 1658 | EXPORT_SYMBOL(d_alloc_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1659 | |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1660 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
| 1661 | { |
Linus Torvalds | 6f7f7ca | 2011-01-14 13:26:18 -0800 | [diff] [blame] | 1662 | WARN_ON_ONCE(dentry->d_op); |
| 1663 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1664 | DCACHE_OP_COMPARE | |
| 1665 | DCACHE_OP_REVALIDATE | |
Jeff Layton | ecf3d1f | 2013-02-20 11:19:05 -0500 | [diff] [blame] | 1666 | DCACHE_OP_WEAK_REVALIDATE | |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1667 | DCACHE_OP_DELETE )); |
| 1668 | dentry->d_op = op; |
| 1669 | if (!op) |
| 1670 | return; |
| 1671 | if (op->d_hash) |
| 1672 | dentry->d_flags |= DCACHE_OP_HASH; |
| 1673 | if (op->d_compare) |
| 1674 | dentry->d_flags |= DCACHE_OP_COMPARE; |
| 1675 | if (op->d_revalidate) |
| 1676 | dentry->d_flags |= DCACHE_OP_REVALIDATE; |
Jeff Layton | ecf3d1f | 2013-02-20 11:19:05 -0500 | [diff] [blame] | 1677 | if (op->d_weak_revalidate) |
| 1678 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1679 | if (op->d_delete) |
| 1680 | dentry->d_flags |= DCACHE_OP_DELETE; |
Sage Weil | f0023bc | 2011-10-28 10:02:42 -0700 | [diff] [blame] | 1681 | if (op->d_prune) |
| 1682 | dentry->d_flags |= DCACHE_OP_PRUNE; |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 1683 | |
| 1684 | } |
| 1685 | EXPORT_SYMBOL(d_set_d_op); |
| 1686 | |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1687 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
| 1688 | { |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 1689 | spin_lock(&dentry->d_lock); |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1690 | if (inode) { |
| 1691 | if (unlikely(IS_AUTOMOUNT(inode))) |
| 1692 | dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1693 | hlist_add_head(&dentry->d_alias, &inode->i_dentry); |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1694 | } |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1695 | dentry->d_inode = inode; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1696 | dentry_rcuwalk_barrier(dentry); |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 1697 | spin_unlock(&dentry->d_lock); |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1698 | fsnotify_d_instantiate(dentry, inode); |
| 1699 | } |
| 1700 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1701 | /** |
| 1702 | * d_instantiate - fill in inode information for a dentry |
| 1703 | * @entry: dentry to complete |
| 1704 | * @inode: inode to attach to this dentry |
| 1705 | * |
| 1706 | * Fill in inode information in the entry. |
| 1707 | * |
| 1708 | * This turns negative dentries into productive full members |
| 1709 | * of society. |
| 1710 | * |
| 1711 | * NOTE! This assumes that the inode count has been incremented |
| 1712 | * (or otherwise set) by the caller to indicate that it is now |
| 1713 | * in use by the dcache. |
| 1714 | */ |
| 1715 | |
| 1716 | void d_instantiate(struct dentry *entry, struct inode * inode) |
| 1717 | { |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1718 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1719 | if (inode) |
| 1720 | spin_lock(&inode->i_lock); |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1721 | __d_instantiate(entry, inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1722 | if (inode) |
| 1723 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1724 | security_d_instantiate(entry, inode); |
| 1725 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1726 | EXPORT_SYMBOL(d_instantiate); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1727 | |
| 1728 | /** |
| 1729 | * d_instantiate_unique - instantiate a non-aliased dentry |
| 1730 | * @entry: dentry to instantiate |
| 1731 | * @inode: inode to attach to this dentry |
| 1732 | * |
| 1733 | * Fill in inode information in the entry. On success, it returns NULL. |
| 1734 | * If an unhashed alias of "entry" already exists, then we return the |
Oleg Drokin | e866cfa | 2006-01-09 20:52:51 -0800 | [diff] [blame] | 1735 | * aliased dentry instead and drop one reference to inode. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1736 | * |
| 1737 | * Note that in order to avoid conflicts with rename() etc, the caller |
| 1738 | * had better be holding the parent directory semaphore. |
Oleg Drokin | e866cfa | 2006-01-09 20:52:51 -0800 | [diff] [blame] | 1739 | * |
| 1740 | * This also assumes that the inode count has been incremented |
| 1741 | * (or otherwise set) by the caller to indicate that it is now |
| 1742 | * in use by the dcache. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1743 | */ |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1744 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
| 1745 | struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1746 | { |
| 1747 | struct dentry *alias; |
| 1748 | int len = entry->d_name.len; |
| 1749 | const char *name = entry->d_name.name; |
| 1750 | unsigned int hash = entry->d_name.hash; |
| 1751 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1752 | if (!inode) { |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1753 | __d_instantiate(entry, NULL); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1754 | return NULL; |
| 1755 | } |
| 1756 | |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 1757 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
Nick Piggin | 9abca36 | 2011-01-07 17:49:36 +1100 | [diff] [blame] | 1758 | /* |
| 1759 | * Don't need alias->d_lock here, because aliases with |
| 1760 | * d_parent == entry->d_parent are not subject to name or |
| 1761 | * parent changes, because the parent inode i_mutex is held. |
| 1762 | */ |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 1763 | if (alias->d_name.hash != hash) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1764 | continue; |
| 1765 | if (alias->d_parent != entry->d_parent) |
| 1766 | continue; |
Linus Torvalds | ee983e8 | 2012-05-10 12:37:10 -0700 | [diff] [blame] | 1767 | if (alias->d_name.len != len) |
| 1768 | continue; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 1769 | if (dentry_cmp(alias, name, len)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1770 | continue; |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 1771 | __dget(alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1772 | return alias; |
| 1773 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1774 | |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1775 | __d_instantiate(entry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1776 | return NULL; |
| 1777 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1778 | |
| 1779 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
| 1780 | { |
| 1781 | struct dentry *result; |
| 1782 | |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1783 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1784 | |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1785 | if (inode) |
| 1786 | spin_lock(&inode->i_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1787 | result = __d_instantiate_unique(entry, inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1788 | if (inode) |
| 1789 | spin_unlock(&inode->i_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1790 | |
| 1791 | if (!result) { |
| 1792 | security_d_instantiate(entry, inode); |
| 1793 | return NULL; |
| 1794 | } |
| 1795 | |
| 1796 | BUG_ON(!d_unhashed(result)); |
| 1797 | iput(inode); |
| 1798 | return result; |
| 1799 | } |
| 1800 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1801 | EXPORT_SYMBOL(d_instantiate_unique); |
| 1802 | |
Al Viro | adc0e91 | 2012-01-08 16:49:21 -0500 | [diff] [blame] | 1803 | struct dentry *d_make_root(struct inode *root_inode) |
| 1804 | { |
| 1805 | struct dentry *res = NULL; |
| 1806 | |
| 1807 | if (root_inode) { |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 1808 | static const struct qstr name = QSTR_INIT("/", 1); |
Al Viro | adc0e91 | 2012-01-08 16:49:21 -0500 | [diff] [blame] | 1809 | |
| 1810 | res = __d_alloc(root_inode->i_sb, &name); |
| 1811 | if (res) |
| 1812 | d_instantiate(res, root_inode); |
| 1813 | else |
| 1814 | iput(root_inode); |
| 1815 | } |
| 1816 | return res; |
| 1817 | } |
| 1818 | EXPORT_SYMBOL(d_make_root); |
| 1819 | |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1820 | static struct dentry * __d_find_any_alias(struct inode *inode) |
| 1821 | { |
| 1822 | struct dentry *alias; |
| 1823 | |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1824 | if (hlist_empty(&inode->i_dentry)) |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1825 | return NULL; |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1826 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias); |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1827 | __dget(alias); |
| 1828 | return alias; |
| 1829 | } |
| 1830 | |
Sage Weil | 46f72b3 | 2012-01-10 09:04:37 -0800 | [diff] [blame] | 1831 | /** |
| 1832 | * d_find_any_alias - find any alias for a given inode |
| 1833 | * @inode: inode to find an alias for |
| 1834 | * |
| 1835 | * If any aliases exist for the given inode, take and return a |
| 1836 | * reference for one of them. If no aliases exist, return %NULL. |
| 1837 | */ |
| 1838 | struct dentry *d_find_any_alias(struct inode *inode) |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1839 | { |
| 1840 | struct dentry *de; |
| 1841 | |
| 1842 | spin_lock(&inode->i_lock); |
| 1843 | de = __d_find_any_alias(inode); |
| 1844 | spin_unlock(&inode->i_lock); |
| 1845 | return de; |
| 1846 | } |
Sage Weil | 46f72b3 | 2012-01-10 09:04:37 -0800 | [diff] [blame] | 1847 | EXPORT_SYMBOL(d_find_any_alias); |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1848 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1849 | /** |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1850 | * d_obtain_alias - find or allocate a dentry for a given inode |
| 1851 | * @inode: inode to allocate the dentry for |
| 1852 | * |
| 1853 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
| 1854 | * similar open by handle operations. The returned dentry may be anonymous, |
| 1855 | * or may have a full name (if the inode was already in the cache). |
| 1856 | * |
| 1857 | * When called on a directory inode, we must ensure that the inode only ever |
| 1858 | * has one dentry. If a dentry is found, that is returned instead of |
| 1859 | * allocating a new one. |
| 1860 | * |
| 1861 | * On successful return, the reference to the inode has been transferred |
Christoph Hellwig | 4400372 | 2008-08-11 15:49:04 +0200 | [diff] [blame] | 1862 | * to the dentry. In case of an error the reference on the inode is released. |
| 1863 | * To make it easier to use in export operations a %NULL or IS_ERR inode may |
| 1864 | * be passed in and will be the error will be propagate to the return value, |
| 1865 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1866 | */ |
| 1867 | struct dentry *d_obtain_alias(struct inode *inode) |
| 1868 | { |
NeilBrown | b911a6b | 2012-11-08 16:09:37 -0800 | [diff] [blame] | 1869 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1870 | struct dentry *tmp; |
| 1871 | struct dentry *res; |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1872 | |
| 1873 | if (!inode) |
Christoph Hellwig | 4400372 | 2008-08-11 15:49:04 +0200 | [diff] [blame] | 1874 | return ERR_PTR(-ESTALE); |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1875 | if (IS_ERR(inode)) |
| 1876 | return ERR_CAST(inode); |
| 1877 | |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1878 | res = d_find_any_alias(inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1879 | if (res) |
| 1880 | goto out_iput; |
| 1881 | |
Al Viro | a4464db | 2011-07-07 15:03:58 -0400 | [diff] [blame] | 1882 | tmp = __d_alloc(inode->i_sb, &anonstring); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1883 | if (!tmp) { |
| 1884 | res = ERR_PTR(-ENOMEM); |
| 1885 | goto out_iput; |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1886 | } |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 1887 | |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1888 | spin_lock(&inode->i_lock); |
J. Bruce Fields | d891eed | 2011-01-18 15:45:09 -0500 | [diff] [blame] | 1889 | res = __d_find_any_alias(inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1890 | if (res) { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1891 | spin_unlock(&inode->i_lock); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1892 | dput(tmp); |
| 1893 | goto out_iput; |
| 1894 | } |
| 1895 | |
| 1896 | /* attach a disconnected dentry */ |
| 1897 | spin_lock(&tmp->d_lock); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1898 | tmp->d_inode = inode; |
| 1899 | tmp->d_flags |= DCACHE_DISCONNECTED; |
Al Viro | b3d9b7a | 2012-06-09 13:51:19 -0400 | [diff] [blame] | 1900 | hlist_add_head(&tmp->d_alias, &inode->i_dentry); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 1901 | hlist_bl_lock(&tmp->d_sb->s_anon); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 1902 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 1903 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1904 | spin_unlock(&tmp->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1905 | spin_unlock(&inode->i_lock); |
Josef Bacik | 24ff666 | 2010-11-18 20:52:55 -0500 | [diff] [blame] | 1906 | security_d_instantiate(tmp, inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1907 | |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1908 | return tmp; |
| 1909 | |
| 1910 | out_iput: |
Josef Bacik | 24ff666 | 2010-11-18 20:52:55 -0500 | [diff] [blame] | 1911 | if (res && !IS_ERR(res)) |
| 1912 | security_d_instantiate(res, inode); |
Christoph Hellwig | 9308a61 | 2008-08-11 15:49:12 +0200 | [diff] [blame] | 1913 | iput(inode); |
| 1914 | return res; |
Christoph Hellwig | 4ea3ada | 2008-08-11 15:48:57 +0200 | [diff] [blame] | 1915 | } |
Benny Halevy | adc4872 | 2009-02-27 14:02:59 -0800 | [diff] [blame] | 1916 | EXPORT_SYMBOL(d_obtain_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1917 | |
| 1918 | /** |
| 1919 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
| 1920 | * @inode: the inode which may have a disconnected dentry |
| 1921 | * @dentry: a negative dentry which we want to point to the inode. |
| 1922 | * |
| 1923 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and |
| 1924 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry |
| 1925 | * and return it, else simply d_add the inode to the dentry and return NULL. |
| 1926 | * |
| 1927 | * This is needed in the lookup routine of any filesystem that is exportable |
| 1928 | * (via knfsd) so that we can build dcache paths to directories effectively. |
| 1929 | * |
| 1930 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
| 1931 | * is returned. This matches the expected return value of ->lookup. |
| 1932 | * |
Steven Whitehouse | 6d4ade9 | 2013-06-14 11:17:15 +0100 | [diff] [blame] | 1933 | * Cluster filesystems may call this function with a negative, hashed dentry. |
| 1934 | * In that case, we know that the inode will be a regular file, and also this |
| 1935 | * will only occur during atomic_open. So we need to check for the dentry |
| 1936 | * being already hashed only in the final case. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1937 | */ |
| 1938 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
| 1939 | { |
| 1940 | struct dentry *new = NULL; |
| 1941 | |
Al Viro | a904937 | 2011-07-08 21:20:11 -0400 | [diff] [blame] | 1942 | if (IS_ERR(inode)) |
| 1943 | return ERR_CAST(inode); |
| 1944 | |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 1945 | if (inode && S_ISDIR(inode->i_mode)) { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1946 | spin_lock(&inode->i_lock); |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 1947 | new = __d_find_alias(inode, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1948 | if (new) { |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 1949 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1950 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1951 | security_d_instantiate(new, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1952 | d_move(new, dentry); |
| 1953 | iput(inode); |
| 1954 | } else { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1955 | /* already taking inode->i_lock, so d_add() by hand */ |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 1956 | __d_instantiate(dentry, inode); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 1957 | spin_unlock(&inode->i_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1958 | security_d_instantiate(dentry, inode); |
| 1959 | d_rehash(dentry); |
| 1960 | } |
Steven Whitehouse | 6d4ade9 | 2013-06-14 11:17:15 +0100 | [diff] [blame] | 1961 | } else { |
| 1962 | d_instantiate(dentry, inode); |
| 1963 | if (d_unhashed(dentry)) |
| 1964 | d_rehash(dentry); |
| 1965 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1966 | return new; |
| 1967 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 1968 | EXPORT_SYMBOL(d_splice_alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1969 | |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 1970 | /** |
| 1971 | * d_add_ci - lookup or allocate new dentry with case-exact name |
| 1972 | * @inode: the inode case-insensitive lookup has found |
| 1973 | * @dentry: the negative dentry that was passed to the parent's lookup func |
| 1974 | * @name: the case-exact name to be associated with the returned dentry |
| 1975 | * |
| 1976 | * This is to avoid filling the dcache with case-insensitive names to the |
| 1977 | * same inode, only the actual correct case is stored in the dcache for |
| 1978 | * case-insensitive filesystems. |
| 1979 | * |
| 1980 | * For a case-insensitive lookup match and if the the case-exact dentry |
| 1981 | * already exists in in the dcache, use it and return it. |
| 1982 | * |
| 1983 | * If no entry exists with the exact case name, allocate new dentry with |
| 1984 | * the exact case, and return the spliced entry. |
| 1985 | */ |
Christoph Hellwig | e45b590 | 2008-08-07 23:49:07 +0200 | [diff] [blame] | 1986 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 1987 | struct qstr *name) |
| 1988 | { |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 1989 | struct dentry *found; |
| 1990 | struct dentry *new; |
| 1991 | |
Christoph Hellwig | b6520c8 | 2009-01-05 19:10:37 +0100 | [diff] [blame] | 1992 | /* |
| 1993 | * First check if a dentry matching the name already exists, |
| 1994 | * if not go ahead and create it now. |
| 1995 | */ |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 1996 | found = d_hash_and_lookup(dentry->d_parent, name); |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 1997 | if (unlikely(IS_ERR(found))) |
| 1998 | goto err_out; |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 1999 | if (!found) { |
| 2000 | new = d_alloc(dentry->d_parent, name); |
| 2001 | if (!new) { |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2002 | found = ERR_PTR(-ENOMEM); |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2003 | goto err_out; |
| 2004 | } |
Christoph Hellwig | b6520c8 | 2009-01-05 19:10:37 +0100 | [diff] [blame] | 2005 | |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2006 | found = d_splice_alias(inode, new); |
| 2007 | if (found) { |
| 2008 | dput(new); |
| 2009 | return found; |
| 2010 | } |
| 2011 | return new; |
| 2012 | } |
Christoph Hellwig | b6520c8 | 2009-01-05 19:10:37 +0100 | [diff] [blame] | 2013 | |
| 2014 | /* |
| 2015 | * If a matching dentry exists, and it's not negative use it. |
| 2016 | * |
| 2017 | * Decrement the reference count to balance the iget() done |
| 2018 | * earlier on. |
| 2019 | */ |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2020 | if (found->d_inode) { |
| 2021 | if (unlikely(found->d_inode != inode)) { |
| 2022 | /* This can't happen because bad inodes are unhashed. */ |
| 2023 | BUG_ON(!is_bad_inode(inode)); |
| 2024 | BUG_ON(!is_bad_inode(found->d_inode)); |
| 2025 | } |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2026 | iput(inode); |
| 2027 | return found; |
| 2028 | } |
Christoph Hellwig | b6520c8 | 2009-01-05 19:10:37 +0100 | [diff] [blame] | 2029 | |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2030 | /* |
| 2031 | * Negative dentry: instantiate it unless the inode is a directory and |
Christoph Hellwig | b6520c8 | 2009-01-05 19:10:37 +0100 | [diff] [blame] | 2032 | * already has a dentry. |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2033 | */ |
Al Viro | 4513d89 | 2011-07-17 10:52:14 -0400 | [diff] [blame] | 2034 | new = d_splice_alias(inode, found); |
| 2035 | if (new) { |
| 2036 | dput(found); |
| 2037 | found = new; |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2038 | } |
Al Viro | 4513d89 | 2011-07-17 10:52:14 -0400 | [diff] [blame] | 2039 | return found; |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2040 | |
| 2041 | err_out: |
| 2042 | iput(inode); |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2043 | return found; |
Barry Naujok | 9403540 | 2008-05-21 16:50:46 +1000 | [diff] [blame] | 2044 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2045 | EXPORT_SYMBOL(d_add_ci); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2046 | |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2047 | /* |
| 2048 | * Do the slow-case of the dentry name compare. |
| 2049 | * |
| 2050 | * Unlike the dentry_cmp() function, we need to atomically |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2051 | * load the name and length information, so that the |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2052 | * filesystem can rely on them, and can use the 'name' and |
| 2053 | * 'len' information without worrying about walking off the |
| 2054 | * end of memory etc. |
| 2055 | * |
| 2056 | * Thus the read_seqcount_retry() and the "duplicate" info |
| 2057 | * in arguments (the low-level filesystem should not look |
| 2058 | * at the dentry inode or name contents directly, since |
| 2059 | * rename can change them while we're in RCU mode). |
| 2060 | */ |
| 2061 | enum slow_d_compare { |
| 2062 | D_COMP_OK, |
| 2063 | D_COMP_NOMATCH, |
| 2064 | D_COMP_SEQRETRY, |
| 2065 | }; |
| 2066 | |
| 2067 | static noinline enum slow_d_compare slow_dentry_cmp( |
| 2068 | const struct dentry *parent, |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2069 | struct dentry *dentry, |
| 2070 | unsigned int seq, |
| 2071 | const struct qstr *name) |
| 2072 | { |
| 2073 | int tlen = dentry->d_name.len; |
| 2074 | const char *tname = dentry->d_name.name; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2075 | |
| 2076 | if (read_seqcount_retry(&dentry->d_seq, seq)) { |
| 2077 | cpu_relax(); |
| 2078 | return D_COMP_SEQRETRY; |
| 2079 | } |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2080 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2081 | return D_COMP_NOMATCH; |
| 2082 | return D_COMP_OK; |
| 2083 | } |
| 2084 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2085 | /** |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2086 | * __d_lookup_rcu - search for a dentry (racy, store-free) |
| 2087 | * @parent: parent dentry |
| 2088 | * @name: qstr of name we wish to find |
Randy Dunlap | 1f1e6e5 | 2012-03-18 21:23:05 -0700 | [diff] [blame] | 2089 | * @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] | 2090 | * Returns: dentry, or NULL |
| 2091 | * |
| 2092 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name |
| 2093 | * resolution (store-free path walking) design described in |
| 2094 | * Documentation/filesystems/path-lookup.txt. |
| 2095 | * |
| 2096 | * This is not to be used outside core vfs. |
| 2097 | * |
| 2098 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock |
| 2099 | * held, and rcu_read_lock held. The returned dentry must not be stored into |
| 2100 | * without taking d_lock and checking d_seq sequence count against @seq |
| 2101 | * returned here. |
| 2102 | * |
Linus Torvalds | 1557008 | 2013-09-02 11:38:06 -0700 | [diff] [blame] | 2103 | * 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] | 2104 | * function. |
| 2105 | * |
| 2106 | * Alternatively, __d_lookup_rcu may be called again to look up the child of |
| 2107 | * the returned dentry, so long as its parent's seqlock is checked after the |
| 2108 | * child is looked up. Thus, an interlocking stepping of sequence lock checks |
| 2109 | * is formed, giving integrity down the path walk. |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2110 | * |
| 2111 | * NOTE! The caller *has* to check the resulting dentry against the sequence |
| 2112 | * number we've returned before using any of the resulting dentry state! |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2113 | */ |
Linus Torvalds | 8966be9 | 2012-03-02 14:23:30 -0800 | [diff] [blame] | 2114 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
| 2115 | const struct qstr *name, |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2116 | unsigned *seqp) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2117 | { |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2118 | u64 hashlen = name->hash_len; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2119 | const unsigned char *str = name->name; |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2120 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2121 | struct hlist_bl_node *node; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2122 | struct dentry *dentry; |
| 2123 | |
| 2124 | /* |
| 2125 | * Note: There is significant duplication with __d_lookup_rcu which is |
| 2126 | * required to prevent single threaded performance regressions |
| 2127 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
| 2128 | * Keep the two functions in sync. |
| 2129 | */ |
| 2130 | |
| 2131 | /* |
| 2132 | * The hash list is protected using RCU. |
| 2133 | * |
| 2134 | * Carefully use d_seq when comparing a candidate dentry, to avoid |
| 2135 | * races with d_move(). |
| 2136 | * |
| 2137 | * It is possible that concurrent renames can mess up our list |
| 2138 | * walk here and result in missing our dentry, resulting in the |
| 2139 | * false-negative result. d_lookup() protects against concurrent |
| 2140 | * renames using rename_lock seqlock. |
| 2141 | * |
Namhyung Kim | b0a4bb8 | 2011-01-22 15:31:32 +0900 | [diff] [blame] | 2142 | * See Documentation/filesystems/path-lookup.txt for more details. |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2143 | */ |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2144 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
Linus Torvalds | 8966be9 | 2012-03-02 14:23:30 -0800 | [diff] [blame] | 2145 | unsigned seq; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2146 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2147 | seqretry: |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2148 | /* |
| 2149 | * The dentry sequence count protects us from concurrent |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2150 | * renames, and thus protects parent and name fields. |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2151 | * |
| 2152 | * The caller must perform a seqcount check in order |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2153 | * to do anything useful with the returned dentry. |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2154 | * |
| 2155 | * NOTE! We do a "raw" seqcount_begin here. That means that |
| 2156 | * we don't wait for the sequence count to stabilize if it |
| 2157 | * is in the middle of a sequence change. If we do the slow |
| 2158 | * dentry compare, we will do seqretries until it is stable, |
| 2159 | * and if we end up with a successful lookup, we actually |
| 2160 | * want to exit RCU lookup anyway. |
| 2161 | */ |
| 2162 | seq = raw_seqcount_begin(&dentry->d_seq); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2163 | if (dentry->d_parent != parent) |
| 2164 | continue; |
Linus Torvalds | 2e32180 | 2012-05-21 18:48:10 -0700 | [diff] [blame] | 2165 | if (d_unhashed(dentry)) |
| 2166 | continue; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2167 | |
| 2168 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2169 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
| 2170 | continue; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2171 | *seqp = seq; |
| 2172 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2173 | case D_COMP_OK: |
| 2174 | return dentry; |
| 2175 | case D_COMP_NOMATCH: |
| 2176 | continue; |
| 2177 | default: |
| 2178 | goto seqretry; |
| 2179 | } |
| 2180 | } |
| 2181 | |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2182 | if (dentry->d_name.hash_len != hashlen) |
Linus Torvalds | ee983e8 | 2012-05-10 12:37:10 -0700 | [diff] [blame] | 2183 | continue; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2184 | *seqp = seq; |
Linus Torvalds | 26fe575 | 2012-05-10 13:14:12 -0700 | [diff] [blame] | 2185 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2186 | return dentry; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2187 | } |
| 2188 | return NULL; |
| 2189 | } |
| 2190 | |
| 2191 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2192 | * d_lookup - search for a dentry |
| 2193 | * @parent: parent dentry |
| 2194 | * @name: qstr of name we wish to find |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2195 | * Returns: dentry, or NULL |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2196 | * |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2197 | * d_lookup searches the children of the parent dentry for the name in |
| 2198 | * question. If the dentry is found its reference count is incremented and the |
| 2199 | * dentry is returned. The caller must use dput to free the entry when it has |
| 2200 | * finished using it. %NULL is returned if the dentry does not exist. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2201 | */ |
Al Viro | da2d845 | 2013-01-24 18:29:34 -0500 | [diff] [blame] | 2202 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2203 | { |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2204 | struct dentry *dentry; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 2205 | unsigned seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2206 | |
| 2207 | do { |
| 2208 | seq = read_seqbegin(&rename_lock); |
| 2209 | dentry = __d_lookup(parent, name); |
| 2210 | if (dentry) |
| 2211 | break; |
| 2212 | } while (read_seqretry(&rename_lock, seq)); |
| 2213 | return dentry; |
| 2214 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2215 | EXPORT_SYMBOL(d_lookup); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2216 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2217 | /** |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2218 | * __d_lookup - search for a dentry (racy) |
| 2219 | * @parent: parent dentry |
| 2220 | * @name: qstr of name we wish to find |
| 2221 | * Returns: dentry, or NULL |
| 2222 | * |
| 2223 | * __d_lookup is like d_lookup, however it may (rarely) return a |
| 2224 | * false-negative result due to unrelated rename activity. |
| 2225 | * |
| 2226 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
| 2227 | * however it must be used carefully, eg. with a following d_lookup in |
| 2228 | * the case of failure. |
| 2229 | * |
| 2230 | * __d_lookup callers must be commented. |
| 2231 | */ |
Al Viro | a713ca2 | 2013-01-24 18:27:00 -0500 | [diff] [blame] | 2232 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2233 | { |
| 2234 | unsigned int len = name->len; |
| 2235 | unsigned int hash = name->hash; |
| 2236 | const unsigned char *str = name->name; |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2237 | struct hlist_bl_head *b = d_hash(parent, hash); |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2238 | struct hlist_bl_node *node; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2239 | struct dentry *found = NULL; |
Paul E. McKenney | 665a758 | 2005-11-07 00:59:17 -0800 | [diff] [blame] | 2240 | struct dentry *dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2241 | |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2242 | /* |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2243 | * Note: There is significant duplication with __d_lookup_rcu which is |
| 2244 | * required to prevent single threaded performance regressions |
| 2245 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
| 2246 | * Keep the two functions in sync. |
| 2247 | */ |
| 2248 | |
| 2249 | /* |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2250 | * The hash list is protected using RCU. |
| 2251 | * |
| 2252 | * Take d_lock when comparing a candidate dentry, to avoid races |
| 2253 | * with d_move(). |
| 2254 | * |
| 2255 | * It is possible that concurrent renames can mess up our list |
| 2256 | * walk here and result in missing our dentry, resulting in the |
| 2257 | * false-negative result. d_lookup() protects against concurrent |
| 2258 | * renames using rename_lock seqlock. |
| 2259 | * |
Namhyung Kim | b0a4bb8 | 2011-01-22 15:31:32 +0900 | [diff] [blame] | 2260 | * See Documentation/filesystems/path-lookup.txt for more details. |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 2261 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2262 | rcu_read_lock(); |
| 2263 | |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2264 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2265 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2266 | if (dentry->d_name.hash != hash) |
| 2267 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2268 | |
| 2269 | spin_lock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2270 | if (dentry->d_parent != parent) |
| 2271 | goto next; |
Linus Torvalds | d0185c0 | 2008-09-29 07:42:57 -0700 | [diff] [blame] | 2272 | if (d_unhashed(dentry)) |
| 2273 | goto next; |
| 2274 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2275 | /* |
| 2276 | * It is safe to compare names since d_move() cannot |
| 2277 | * change the qstr (protected by d_lock). |
| 2278 | */ |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 2279 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2280 | int tlen = dentry->d_name.len; |
| 2281 | const char *tname = dentry->d_name.name; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2282 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2283 | goto next; |
| 2284 | } else { |
Linus Torvalds | ee983e8 | 2012-05-10 12:37:10 -0700 | [diff] [blame] | 2285 | if (dentry->d_name.len != len) |
| 2286 | goto next; |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 2287 | if (dentry_cmp(dentry, str, len)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2288 | goto next; |
| 2289 | } |
| 2290 | |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 2291 | dentry->d_lockref.count++; |
Linus Torvalds | d0185c0 | 2008-09-29 07:42:57 -0700 | [diff] [blame] | 2292 | found = dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2293 | spin_unlock(&dentry->d_lock); |
| 2294 | break; |
| 2295 | next: |
| 2296 | spin_unlock(&dentry->d_lock); |
| 2297 | } |
| 2298 | rcu_read_unlock(); |
| 2299 | |
| 2300 | return found; |
| 2301 | } |
| 2302 | |
| 2303 | /** |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2304 | * d_hash_and_lookup - hash the qstr then search for a dentry |
| 2305 | * @dir: Directory to search in |
| 2306 | * @name: qstr of name we wish to find |
| 2307 | * |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2308 | * 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] | 2309 | */ |
| 2310 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
| 2311 | { |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2312 | /* |
| 2313 | * Check for a fs-specific hash function. Note that we must |
| 2314 | * calculate the standard hash first, as the d_op->d_hash() |
| 2315 | * routine may choose to leave the hash value unchanged. |
| 2316 | */ |
| 2317 | name->hash = full_name_hash(name->name, name->len); |
Nick Piggin | fb045ad | 2011-01-07 17:49:55 +1100 | [diff] [blame] | 2318 | if (dir->d_flags & DCACHE_OP_HASH) { |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2319 | int err = dir->d_op->d_hash(dir, name); |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2320 | if (unlikely(err < 0)) |
| 2321 | return ERR_PTR(err); |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2322 | } |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2323 | return d_lookup(dir, name); |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2324 | } |
Al Viro | 4f522a2 | 2013-02-11 23:20:37 -0500 | [diff] [blame] | 2325 | EXPORT_SYMBOL(d_hash_and_lookup); |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2326 | |
| 2327 | /** |
Nick Piggin | 786a5e1 | 2011-01-07 17:49:16 +1100 | [diff] [blame] | 2328 | * d_validate - verify dentry provided from insecure source (deprecated) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2329 | * @dentry: The dentry alleged to be valid child of @dparent |
Randy Dunlap | ff5fdb6 | 2011-01-22 20:16:06 -0800 | [diff] [blame] | 2330 | * @dparent: The parent dentry (known to be valid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2331 | * |
| 2332 | * An insecure source has sent us a dentry, here we verify it and dget() it. |
| 2333 | * This is used by ncpfs in its readdir implementation. |
| 2334 | * Zero is returned in the dentry is invalid. |
Nick Piggin | 786a5e1 | 2011-01-07 17:49:16 +1100 | [diff] [blame] | 2335 | * |
| 2336 | * This function is slow for big directories, and deprecated, do not use it. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2337 | */ |
Nick Piggin | d3a23e1 | 2011-01-05 20:01:21 +1100 | [diff] [blame] | 2338 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2339 | { |
Nick Piggin | 786a5e1 | 2011-01-07 17:49:16 +1100 | [diff] [blame] | 2340 | struct dentry *child; |
Nick Piggin | d3a23e1 | 2011-01-05 20:01:21 +1100 | [diff] [blame] | 2341 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2342 | spin_lock(&dparent->d_lock); |
Nick Piggin | 786a5e1 | 2011-01-07 17:49:16 +1100 | [diff] [blame] | 2343 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
| 2344 | if (dentry == child) { |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2345 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 2346 | __dget_dlock(dentry); |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2347 | spin_unlock(&dentry->d_lock); |
| 2348 | spin_unlock(&dparent->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2349 | return 1; |
| 2350 | } |
| 2351 | } |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2352 | spin_unlock(&dparent->d_lock); |
Nick Piggin | 786a5e1 | 2011-01-07 17:49:16 +1100 | [diff] [blame] | 2353 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2354 | return 0; |
| 2355 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2356 | EXPORT_SYMBOL(d_validate); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2357 | |
| 2358 | /* |
| 2359 | * When a file is deleted, we have two options: |
| 2360 | * - turn this dentry into a negative dentry |
| 2361 | * - unhash this dentry and free it. |
| 2362 | * |
| 2363 | * Usually, we want to just turn this into |
| 2364 | * a negative dentry, but if anybody else is |
| 2365 | * currently using the dentry or the inode |
| 2366 | * we can't do that and we fall back on removing |
| 2367 | * it from the hash queues and waiting for |
| 2368 | * it to be deleted later when it has no users |
| 2369 | */ |
| 2370 | |
| 2371 | /** |
| 2372 | * d_delete - delete a dentry |
| 2373 | * @dentry: The dentry to delete |
| 2374 | * |
| 2375 | * Turn the dentry into a negative dentry if possible, otherwise |
| 2376 | * remove it from the hash queues so it can be deleted later |
| 2377 | */ |
| 2378 | |
| 2379 | void d_delete(struct dentry * dentry) |
| 2380 | { |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2381 | struct inode *inode; |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 2382 | int isdir = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2383 | /* |
| 2384 | * Are we the only user? |
| 2385 | */ |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2386 | again: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2387 | spin_lock(&dentry->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2388 | inode = dentry->d_inode; |
| 2389 | isdir = S_ISDIR(inode->i_mode); |
Waiman Long | 9847423 | 2013-08-28 18:24:59 -0700 | [diff] [blame] | 2390 | if (dentry->d_lockref.count == 1) { |
Alan Cox | 1fe0c02 | 2012-09-19 15:49:51 +0100 | [diff] [blame] | 2391 | if (!spin_trylock(&inode->i_lock)) { |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2392 | spin_unlock(&dentry->d_lock); |
| 2393 | cpu_relax(); |
| 2394 | goto again; |
| 2395 | } |
Al Viro | 13e3c5e | 2010-05-21 16:11:04 -0400 | [diff] [blame] | 2396 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2397 | dentry_unlink_inode(dentry); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 2398 | fsnotify_nameremove(dentry, isdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2399 | return; |
| 2400 | } |
| 2401 | |
| 2402 | if (!d_unhashed(dentry)) |
| 2403 | __d_drop(dentry); |
| 2404 | |
| 2405 | spin_unlock(&dentry->d_lock); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 2406 | |
| 2407 | fsnotify_nameremove(dentry, isdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2408 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2409 | EXPORT_SYMBOL(d_delete); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2410 | |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2411 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2412 | { |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2413 | BUG_ON(!d_unhashed(entry)); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 2414 | hlist_bl_lock(b); |
Linus Torvalds | dea3667 | 2011-04-24 07:58:46 -0700 | [diff] [blame] | 2415 | entry->d_flags |= DCACHE_RCUACCESS; |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 2416 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
Christoph Hellwig | 1879fd6 | 2011-04-25 14:01:36 -0400 | [diff] [blame] | 2417 | hlist_bl_unlock(b); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2418 | } |
| 2419 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2420 | static void _d_rehash(struct dentry * entry) |
| 2421 | { |
| 2422 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
| 2423 | } |
| 2424 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2425 | /** |
| 2426 | * d_rehash - add an entry back to the hash |
| 2427 | * @entry: dentry to add to the hash |
| 2428 | * |
| 2429 | * Adds a dentry to the hash according to its name. |
| 2430 | */ |
| 2431 | |
| 2432 | void d_rehash(struct dentry * entry) |
| 2433 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2434 | spin_lock(&entry->d_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2435 | _d_rehash(entry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2436 | spin_unlock(&entry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2437 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2438 | EXPORT_SYMBOL(d_rehash); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2439 | |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2440 | /** |
| 2441 | * dentry_update_name_case - update case insensitive dentry with a new name |
| 2442 | * @dentry: dentry to be updated |
| 2443 | * @name: new name |
| 2444 | * |
| 2445 | * Update a case insensitive dentry with new case of name. |
| 2446 | * |
| 2447 | * dentry must have been returned by d_lookup with name @name. Old and new |
| 2448 | * name lengths must match (ie. no d_compare which allows mismatched name |
| 2449 | * lengths). |
| 2450 | * |
| 2451 | * Parent inode i_mutex must be held over d_lookup and into this call (to |
| 2452 | * keep renames and concurrent inserts, and readdir(2) away). |
| 2453 | */ |
| 2454 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
| 2455 | { |
Linus Torvalds | 7ebfa57 | 2011-04-15 07:34:26 -0700 | [diff] [blame] | 2456 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2457 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
| 2458 | |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2459 | spin_lock(&dentry->d_lock); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2460 | write_seqcount_begin(&dentry->d_seq); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2461 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2462 | write_seqcount_end(&dentry->d_seq); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2463 | spin_unlock(&dentry->d_lock); |
Nick Piggin | fb2d5b8 | 2011-01-07 17:49:26 +1100 | [diff] [blame] | 2464 | } |
| 2465 | EXPORT_SYMBOL(dentry_update_name_case); |
| 2466 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2467 | static void switch_names(struct dentry *dentry, struct dentry *target) |
| 2468 | { |
| 2469 | if (dname_external(target)) { |
| 2470 | if (dname_external(dentry)) { |
| 2471 | /* |
| 2472 | * Both external: swap the pointers |
| 2473 | */ |
Wu Fengguang | 9a8d5bb | 2009-01-07 18:09:14 -0800 | [diff] [blame] | 2474 | swap(target->d_name.name, dentry->d_name.name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2475 | } else { |
| 2476 | /* |
| 2477 | * dentry:internal, target:external. Steal target's |
| 2478 | * storage and make target internal. |
| 2479 | */ |
J. Bruce Fields | 321bcf9 | 2007-10-21 16:41:38 -0700 | [diff] [blame] | 2480 | memcpy(target->d_iname, dentry->d_name.name, |
| 2481 | dentry->d_name.len + 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2482 | dentry->d_name.name = target->d_name.name; |
| 2483 | target->d_name.name = target->d_iname; |
| 2484 | } |
| 2485 | } else { |
| 2486 | if (dname_external(dentry)) { |
| 2487 | /* |
| 2488 | * dentry:external, target:internal. Give dentry's |
| 2489 | * storage to target and make dentry internal |
| 2490 | */ |
| 2491 | memcpy(dentry->d_iname, target->d_name.name, |
| 2492 | target->d_name.len + 1); |
| 2493 | target->d_name.name = dentry->d_name.name; |
| 2494 | dentry->d_name.name = dentry->d_iname; |
| 2495 | } else { |
| 2496 | /* |
| 2497 | * Both are internal. Just copy target to dentry |
| 2498 | */ |
| 2499 | memcpy(dentry->d_iname, target->d_name.name, |
| 2500 | target->d_name.len + 1); |
Al Viro | dc711ca | 2008-11-03 15:03:50 -0500 | [diff] [blame] | 2501 | dentry->d_name.len = target->d_name.len; |
| 2502 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2503 | } |
| 2504 | } |
Wu Fengguang | 9a8d5bb | 2009-01-07 18:09:14 -0800 | [diff] [blame] | 2505 | swap(dentry->d_name.len, target->d_name.len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2506 | } |
| 2507 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2508 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
| 2509 | { |
| 2510 | /* |
| 2511 | * XXXX: do we really need to take target->d_lock? |
| 2512 | */ |
| 2513 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) |
| 2514 | spin_lock(&target->d_parent->d_lock); |
| 2515 | else { |
| 2516 | if (d_ancestor(dentry->d_parent, target->d_parent)) { |
| 2517 | spin_lock(&dentry->d_parent->d_lock); |
| 2518 | spin_lock_nested(&target->d_parent->d_lock, |
| 2519 | DENTRY_D_LOCK_NESTED); |
| 2520 | } else { |
| 2521 | spin_lock(&target->d_parent->d_lock); |
| 2522 | spin_lock_nested(&dentry->d_parent->d_lock, |
| 2523 | DENTRY_D_LOCK_NESTED); |
| 2524 | } |
| 2525 | } |
| 2526 | if (target < dentry) { |
| 2527 | spin_lock_nested(&target->d_lock, 2); |
| 2528 | spin_lock_nested(&dentry->d_lock, 3); |
| 2529 | } else { |
| 2530 | spin_lock_nested(&dentry->d_lock, 2); |
| 2531 | spin_lock_nested(&target->d_lock, 3); |
| 2532 | } |
| 2533 | } |
| 2534 | |
| 2535 | static void dentry_unlock_parents_for_move(struct dentry *dentry, |
| 2536 | struct dentry *target) |
| 2537 | { |
| 2538 | if (target->d_parent != dentry->d_parent) |
| 2539 | spin_unlock(&dentry->d_parent->d_lock); |
| 2540 | if (target->d_parent != target) |
| 2541 | spin_unlock(&target->d_parent->d_lock); |
| 2542 | } |
| 2543 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2544 | /* |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2545 | * When switching names, the actual string doesn't strictly have to |
| 2546 | * be preserved in the target - because we're dropping the target |
| 2547 | * anyway. As such, we can just do a simple memcpy() to copy over |
| 2548 | * the new name before we switch. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2549 | * |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2550 | * Note that we have to be a lot more careful about getting the hash |
| 2551 | * switched - we have to switch the hash value properly even if it |
| 2552 | * then no longer matches the actual (corrupted) string of the target. |
| 2553 | * The hash value has to match the hash queue that the dentry is on.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2554 | */ |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2555 | /* |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2556 | * __d_move - move a dentry |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2557 | * @dentry: entry to move |
| 2558 | * @target: new dentry |
| 2559 | * |
| 2560 | * Update the dcache to reflect the move of a file name. Negative |
Jeff Layton | c46c887 | 2011-07-26 13:33:16 -0400 | [diff] [blame] | 2561 | * dcache entries should not be moved in this way. Caller must hold |
| 2562 | * rename_lock, the i_mutex of the source and target directories, |
| 2563 | * 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] | 2564 | */ |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2565 | static void __d_move(struct dentry * dentry, struct dentry * target) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2566 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2567 | if (!dentry->d_inode) |
| 2568 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
| 2569 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2570 | BUG_ON(d_ancestor(dentry, target)); |
| 2571 | BUG_ON(d_ancestor(target, dentry)); |
| 2572 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2573 | dentry_lock_for_move(dentry, target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2574 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2575 | write_seqcount_begin(&dentry->d_seq); |
| 2576 | write_seqcount_begin(&target->d_seq); |
| 2577 | |
Nick Piggin | ceb5bdc | 2011-01-07 17:50:05 +1100 | [diff] [blame] | 2578 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
| 2579 | |
| 2580 | /* |
| 2581 | * Move the dentry to the target hash queue. Don't bother checking |
| 2582 | * for the same hash queue because of how unlikely it is. |
| 2583 | */ |
| 2584 | __d_drop(dentry); |
Nick Piggin | 789680d | 2011-01-07 17:49:30 +1100 | [diff] [blame] | 2585 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2586 | |
| 2587 | /* Unhash the target: dput() will then get rid of it */ |
| 2588 | __d_drop(target); |
| 2589 | |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 2590 | list_del(&dentry->d_u.d_child); |
| 2591 | list_del(&target->d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2592 | |
| 2593 | /* Switch the names.. */ |
| 2594 | switch_names(dentry, target); |
Wu Fengguang | 9a8d5bb | 2009-01-07 18:09:14 -0800 | [diff] [blame] | 2595 | swap(dentry->d_name.hash, target->d_name.hash); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2596 | |
| 2597 | /* ... and switch the parents */ |
| 2598 | if (IS_ROOT(dentry)) { |
| 2599 | dentry->d_parent = target->d_parent; |
| 2600 | target->d_parent = target; |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 2601 | INIT_LIST_HEAD(&target->d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2602 | } else { |
Wu Fengguang | 9a8d5bb | 2009-01-07 18:09:14 -0800 | [diff] [blame] | 2603 | swap(dentry->d_parent, target->d_parent); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2604 | |
| 2605 | /* And add them back to the (new) parent lists */ |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 2606 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2607 | } |
| 2608 | |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 2609 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2610 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2611 | write_seqcount_end(&target->d_seq); |
| 2612 | write_seqcount_end(&dentry->d_seq); |
| 2613 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2614 | dentry_unlock_parents_for_move(dentry, target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2615 | spin_unlock(&target->d_lock); |
Nick Piggin | c32ccd8 | 2006-03-25 03:07:09 -0800 | [diff] [blame] | 2616 | fsnotify_d_move(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2617 | spin_unlock(&dentry->d_lock); |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2618 | } |
| 2619 | |
| 2620 | /* |
| 2621 | * d_move - move a dentry |
| 2622 | * @dentry: entry to move |
| 2623 | * @target: new dentry |
| 2624 | * |
| 2625 | * Update the dcache to reflect the move of a file name. Negative |
Jeff Layton | c46c887 | 2011-07-26 13:33:16 -0400 | [diff] [blame] | 2626 | * dcache entries should not be moved in this way. See the locking |
| 2627 | * requirements for __d_move. |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2628 | */ |
| 2629 | void d_move(struct dentry *dentry, struct dentry *target) |
| 2630 | { |
| 2631 | write_seqlock(&rename_lock); |
| 2632 | __d_move(dentry, target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2633 | write_sequnlock(&rename_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2634 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2635 | EXPORT_SYMBOL(d_move); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2636 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2637 | /** |
| 2638 | * d_ancestor - search for an ancestor |
| 2639 | * @p1: ancestor dentry |
| 2640 | * @p2: child dentry |
| 2641 | * |
| 2642 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
| 2643 | * an ancestor of p2, else NULL. |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2644 | */ |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2645 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2646 | { |
| 2647 | struct dentry *p; |
| 2648 | |
OGAWA Hirofumi | 871c006 | 2008-10-16 07:50:27 +0900 | [diff] [blame] | 2649 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2650 | if (p->d_parent == p1) |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2651 | return p; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2652 | } |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2653 | return NULL; |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2654 | } |
| 2655 | |
| 2656 | /* |
| 2657 | * This helper attempts to cope with remotely renamed directories |
| 2658 | * |
| 2659 | * It assumes that the caller is already holding |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2660 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2661 | * |
| 2662 | * Note: If ever the locking in lock_rename() changes, then please |
| 2663 | * remember to update this too... |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2664 | */ |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2665 | static struct dentry *__d_unalias(struct inode *inode, |
| 2666 | struct dentry *dentry, struct dentry *alias) |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2667 | { |
| 2668 | struct mutex *m1 = NULL, *m2 = NULL; |
Al Viro | ee3efa9 | 2012-06-08 15:59:33 -0400 | [diff] [blame] | 2669 | struct dentry *ret = ERR_PTR(-EBUSY); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2670 | |
| 2671 | /* If alias and dentry share a parent, then no extra locks required */ |
| 2672 | if (alias->d_parent == dentry->d_parent) |
| 2673 | goto out_unalias; |
| 2674 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2675 | /* See lock_rename() */ |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2676 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
| 2677 | goto out_err; |
| 2678 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
| 2679 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
| 2680 | goto out_err; |
| 2681 | m2 = &alias->d_parent->d_inode->i_mutex; |
| 2682 | out_unalias: |
Al Viro | ee3efa9 | 2012-06-08 15:59:33 -0400 | [diff] [blame] | 2683 | if (likely(!d_mountpoint(alias))) { |
| 2684 | __d_move(alias, dentry); |
| 2685 | ret = alias; |
| 2686 | } |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2687 | out_err: |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2688 | spin_unlock(&inode->i_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2689 | if (m2) |
| 2690 | mutex_unlock(m2); |
| 2691 | if (m1) |
| 2692 | mutex_unlock(m1); |
| 2693 | return ret; |
| 2694 | } |
| 2695 | |
| 2696 | /* |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2697 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a |
| 2698 | * named dentry in place of the dentry to be replaced. |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2699 | * returns with anon->d_lock held! |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2700 | */ |
| 2701 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) |
| 2702 | { |
Al Viro | 740da42 | 2013-01-30 10:13:38 -0500 | [diff] [blame] | 2703 | struct dentry *dparent; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2704 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2705 | dentry_lock_for_move(anon, dentry); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2706 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2707 | write_seqcount_begin(&dentry->d_seq); |
| 2708 | write_seqcount_begin(&anon->d_seq); |
| 2709 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2710 | dparent = dentry->d_parent; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2711 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2712 | switch_names(dentry, anon); |
| 2713 | swap(dentry->d_name.hash, anon->d_name.hash); |
| 2714 | |
Al Viro | 740da42 | 2013-01-30 10:13:38 -0500 | [diff] [blame] | 2715 | dentry->d_parent = dentry; |
| 2716 | list_del_init(&dentry->d_u.d_child); |
| 2717 | anon->d_parent = dparent; |
Wei Yongjun | 9ed53b1 | 2013-03-12 00:10:50 +0800 | [diff] [blame] | 2718 | list_move(&anon->d_u.d_child, &dparent->d_subdirs); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2719 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2720 | write_seqcount_end(&dentry->d_seq); |
| 2721 | write_seqcount_end(&anon->d_seq); |
| 2722 | |
Nick Piggin | 2fd6b7f | 2011-01-07 17:49:34 +1100 | [diff] [blame] | 2723 | dentry_unlock_parents_for_move(anon, dentry); |
| 2724 | spin_unlock(&dentry->d_lock); |
| 2725 | |
| 2726 | /* anon->d_lock still locked, returns locked */ |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2727 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
| 2728 | } |
| 2729 | |
| 2730 | /** |
| 2731 | * d_materialise_unique - introduce an inode into the tree |
| 2732 | * @dentry: candidate dentry |
| 2733 | * @inode: inode to bind to the dentry, to which aliases may be attached |
| 2734 | * |
| 2735 | * Introduces an dentry into the tree, substituting an extant disconnected |
Jeff Layton | c46c887 | 2011-07-26 13:33:16 -0400 | [diff] [blame] | 2736 | * root directory alias in its place if there is one. Caller must hold the |
| 2737 | * i_mutex of the parent directory. |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2738 | */ |
| 2739 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) |
| 2740 | { |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2741 | struct dentry *actual; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2742 | |
| 2743 | BUG_ON(!d_unhashed(dentry)); |
| 2744 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2745 | if (!inode) { |
| 2746 | actual = dentry; |
OGAWA Hirofumi | 360da90 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2747 | __d_instantiate(dentry, NULL); |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2748 | d_rehash(actual); |
| 2749 | goto out_nolock; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2750 | } |
| 2751 | |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2752 | spin_lock(&inode->i_lock); |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2753 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2754 | if (S_ISDIR(inode->i_mode)) { |
| 2755 | struct dentry *alias; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2756 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2757 | /* Does an aliased dentry already exist? */ |
Linus Torvalds | 32ba9c3 | 2012-06-08 10:34:03 -0700 | [diff] [blame] | 2758 | alias = __d_find_alias(inode, 0); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2759 | if (alias) { |
| 2760 | actual = alias; |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2761 | write_seqlock(&rename_lock); |
| 2762 | |
| 2763 | if (d_ancestor(alias, dentry)) { |
| 2764 | /* Check for loops */ |
| 2765 | actual = ERR_PTR(-ELOOP); |
Michel Lespinasse | b18dafc | 2012-03-26 17:32:44 -0700 | [diff] [blame] | 2766 | spin_unlock(&inode->i_lock); |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2767 | } else if (IS_ROOT(alias)) { |
| 2768 | /* Is this an anonymous mountpoint that we |
| 2769 | * could splice into our tree? */ |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2770 | __d_materialise_dentry(dentry, alias); |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2771 | write_sequnlock(&rename_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2772 | __d_drop(alias); |
| 2773 | goto found; |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2774 | } else { |
| 2775 | /* Nope, but we must(!) avoid directory |
Michel Lespinasse | b18dafc | 2012-03-26 17:32:44 -0700 | [diff] [blame] | 2776 | * aliasing. This drops inode->i_lock */ |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2777 | actual = __d_unalias(inode, dentry, alias); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2778 | } |
Al Viro | 1836750 | 2011-07-12 21:42:24 -0400 | [diff] [blame] | 2779 | write_sequnlock(&rename_lock); |
David Howells | dd17994 | 2011-08-16 15:31:30 +0100 | [diff] [blame] | 2780 | if (IS_ERR(actual)) { |
| 2781 | if (PTR_ERR(actual) == -ELOOP) |
| 2782 | pr_warn_ratelimited( |
| 2783 | "VFS: Lookup of '%s' in %s %s" |
| 2784 | " would have caused loop\n", |
| 2785 | dentry->d_name.name, |
| 2786 | inode->i_sb->s_type->name, |
| 2787 | inode->i_sb->s_id); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2788 | dput(alias); |
David Howells | dd17994 | 2011-08-16 15:31:30 +0100 | [diff] [blame] | 2789 | } |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2790 | goto out_nolock; |
| 2791 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2792 | } |
| 2793 | |
| 2794 | /* Add a unique reference */ |
| 2795 | actual = __d_instantiate_unique(dentry, inode); |
| 2796 | if (!actual) |
| 2797 | actual = dentry; |
Nick Piggin | 357f8e6 | 2011-01-07 17:49:42 +1100 | [diff] [blame] | 2798 | else |
| 2799 | BUG_ON(!d_unhashed(actual)); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2800 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2801 | spin_lock(&actual->d_lock); |
| 2802 | found: |
| 2803 | _d_rehash(actual); |
| 2804 | spin_unlock(&actual->d_lock); |
Nick Piggin | 873feea | 2011-01-07 17:50:06 +1100 | [diff] [blame] | 2805 | spin_unlock(&inode->i_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 2806 | out_nolock: |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2807 | if (actual == dentry) { |
| 2808 | security_d_instantiate(dentry, inode); |
| 2809 | return NULL; |
| 2810 | } |
| 2811 | |
| 2812 | iput(inode); |
| 2813 | return actual; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2814 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 2815 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2816 | |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2817 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 2818 | { |
| 2819 | *buflen -= namelen; |
| 2820 | if (*buflen < 0) |
| 2821 | return -ENAMETOOLONG; |
| 2822 | *buffer -= namelen; |
| 2823 | memcpy(*buffer, str, namelen); |
| 2824 | return 0; |
| 2825 | } |
| 2826 | |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2827 | /** |
| 2828 | * prepend_name - prepend a pathname in front of current buffer pointer |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 2829 | * @buffer: buffer pointer |
| 2830 | * @buflen: allocated length of the buffer |
| 2831 | * @name: name string and length qstr structure |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2832 | * |
| 2833 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to |
| 2834 | * make sure that either the old or the new name pointer and length are |
| 2835 | * fetched. However, there may be mismatch between length and pointer. |
| 2836 | * The length cannot be trusted, we need to copy it byte-by-byte until |
| 2837 | * the length is reached or a null byte is found. It also prepends "/" at |
| 2838 | * the beginning of the name. The sequence number check at the caller will |
| 2839 | * retry it again when a d_move() does happen. So any garbage in the buffer |
| 2840 | * due to mismatched pointer and length will be discarded. |
| 2841 | */ |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2842 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
| 2843 | { |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2844 | const char *dname = ACCESS_ONCE(name->name); |
| 2845 | u32 dlen = ACCESS_ONCE(name->len); |
| 2846 | char *p; |
| 2847 | |
| 2848 | if (*buflen < dlen + 1) |
| 2849 | return -ENAMETOOLONG; |
| 2850 | *buflen -= dlen + 1; |
| 2851 | p = *buffer -= dlen + 1; |
| 2852 | *p++ = '/'; |
| 2853 | while (dlen--) { |
| 2854 | char c = *dname++; |
| 2855 | if (!c) |
| 2856 | break; |
| 2857 | *p++ = c; |
| 2858 | } |
| 2859 | return 0; |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2860 | } |
| 2861 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2862 | /** |
Randy Dunlap | 208898c | 2010-11-18 15:02:49 -0800 | [diff] [blame] | 2863 | * prepend_path - Prepend path string to a buffer |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2864 | * @path: the dentry/vfsmount to report |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2865 | * @root: root vfsmnt/dentry |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2866 | * @buffer: pointer to the end of the buffer |
| 2867 | * @buflen: pointer to buffer length |
| 2868 | * |
Waiman Long | 1812997 | 2013-09-12 10:55:35 -0400 | [diff] [blame] | 2869 | * The function will first try to write out the pathname without taking any |
| 2870 | * lock other than the RCU read lock to make sure that dentries won't go away. |
| 2871 | * It only checks the sequence number of the global rename_lock as any change |
| 2872 | * in the dentry's d_seq will be preceded by changes in the rename_lock |
| 2873 | * sequence number. If the sequence number had been changed, it will restart |
| 2874 | * the whole pathname back-tracing sequence again by taking the rename_lock. |
| 2875 | * In this case, there is no need to take the RCU read lock as the recursive |
| 2876 | * parent pointer references will keep the dentry chain alive as long as no |
| 2877 | * rename operation is performed. |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2878 | */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2879 | static int prepend_path(const struct path *path, |
| 2880 | const struct path *root, |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2881 | char **buffer, int *buflen) |
| 2882 | { |
| 2883 | struct dentry *dentry = path->dentry; |
| 2884 | struct vfsmount *vfsmnt = path->mnt; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 2885 | struct mount *mnt = real_mount(vfsmnt); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2886 | int error = 0; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2887 | unsigned seq = 0; |
| 2888 | char *bptr; |
| 2889 | int blen; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2890 | |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 2891 | rcu_read_lock(); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2892 | restart: |
| 2893 | bptr = *buffer; |
| 2894 | blen = *buflen; |
| 2895 | read_seqbegin_or_lock(&rename_lock, &seq); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2896 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
| 2897 | struct dentry * parent; |
| 2898 | |
| 2899 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
| 2900 | /* Global root? */ |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2901 | if (mnt_has_parent(mnt)) { |
| 2902 | dentry = mnt->mnt_mountpoint; |
| 2903 | mnt = mnt->mnt_parent; |
| 2904 | vfsmnt = &mnt->mnt; |
| 2905 | continue; |
| 2906 | } |
| 2907 | /* |
| 2908 | * Filesystems needing to implement special "root names" |
| 2909 | * should do so with ->d_dname() |
| 2910 | */ |
| 2911 | if (IS_ROOT(dentry) && |
| 2912 | (dentry->d_name.len != 1 || |
| 2913 | dentry->d_name.name[0] != '/')) { |
| 2914 | WARN(1, "Root dentry has weird name <%.*s>\n", |
| 2915 | (int) dentry->d_name.len, |
| 2916 | dentry->d_name.name); |
| 2917 | } |
| 2918 | if (!error) |
| 2919 | error = is_mounted(vfsmnt) ? 1 : 2; |
| 2920 | break; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2921 | } |
| 2922 | parent = dentry->d_parent; |
| 2923 | prefetch(parent); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2924 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2925 | if (error) |
| 2926 | break; |
| 2927 | |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2928 | dentry = parent; |
| 2929 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 2930 | if (!(seq & 1)) |
| 2931 | rcu_read_unlock(); |
| 2932 | if (need_seqretry(&rename_lock, seq)) { |
| 2933 | seq = 1; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2934 | goto restart; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2935 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 2936 | done_seqretry(&rename_lock, seq); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2937 | |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2938 | if (error >= 0 && bptr == *buffer) { |
| 2939 | if (--blen < 0) |
| 2940 | error = -ENAMETOOLONG; |
| 2941 | else |
| 2942 | *--bptr = '/'; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2943 | } |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 2944 | *buffer = bptr; |
| 2945 | *buflen = blen; |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 2946 | return error; |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2947 | } |
| 2948 | |
| 2949 | /** |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 2950 | * __d_path - return the path of a dentry |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 2951 | * @path: the dentry/vfsmount to report |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2952 | * @root: root vfsmnt/dentry |
Randy Dunlap | cd956a1 | 2010-08-14 13:05:31 -0700 | [diff] [blame] | 2953 | * @buf: buffer to return value in |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2954 | * @buflen: buffer length |
| 2955 | * |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 2956 | * Convert a dentry into an ASCII path name. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2957 | * |
Arjan van de Ven | 52afeef | 2008-12-01 14:35:00 -0800 | [diff] [blame] | 2958 | * Returns a pointer into the buffer or an error code if the |
| 2959 | * path was too long. |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 2960 | * |
Christoph Hellwig | be14824 | 2010-10-10 05:36:21 -0400 | [diff] [blame] | 2961 | * "buflen" should be positive. |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 2962 | * |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2963 | * If the path is not reachable from the supplied root, return %NULL. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2964 | */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2965 | char *__d_path(const struct path *path, |
| 2966 | const struct path *root, |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2967 | char *buf, int buflen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2968 | { |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2969 | char *res = buf + buflen; |
| 2970 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2971 | |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2972 | prepend(&res, &buflen, "\0", 1); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 2973 | br_read_lock(&vfsmount_lock); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2974 | error = prepend_path(path, root, &res, &buflen); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 2975 | br_read_unlock(&vfsmount_lock); |
Christoph Hellwig | be14824 | 2010-10-10 05:36:21 -0400 | [diff] [blame] | 2976 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2977 | if (error < 0) |
| 2978 | return ERR_PTR(error); |
| 2979 | if (error > 0) |
| 2980 | return NULL; |
| 2981 | return res; |
| 2982 | } |
| 2983 | |
| 2984 | char *d_absolute_path(const struct path *path, |
| 2985 | char *buf, int buflen) |
| 2986 | { |
| 2987 | struct path root = {}; |
| 2988 | char *res = buf + buflen; |
| 2989 | int error; |
| 2990 | |
| 2991 | prepend(&res, &buflen, "\0", 1); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 2992 | br_read_lock(&vfsmount_lock); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2993 | error = prepend_path(path, &root, &res, &buflen); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 2994 | br_read_unlock(&vfsmount_lock); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2995 | |
| 2996 | if (error > 1) |
| 2997 | error = -EINVAL; |
| 2998 | if (error < 0) |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 2999 | return ERR_PTR(error); |
Miklos Szeredi | f2eb657 | 2010-08-10 11:41:39 +0200 | [diff] [blame] | 3000 | return res; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3001 | } |
| 3002 | |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3003 | /* |
| 3004 | * same as __d_path but appends "(deleted)" for unlinked files. |
| 3005 | */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3006 | static int path_with_deleted(const struct path *path, |
| 3007 | const struct path *root, |
| 3008 | char **buf, int *buflen) |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3009 | { |
| 3010 | prepend(buf, buflen, "\0", 1); |
| 3011 | if (d_unlinked(path->dentry)) { |
| 3012 | int error = prepend(buf, buflen, " (deleted)", 10); |
| 3013 | if (error) |
| 3014 | return error; |
| 3015 | } |
| 3016 | |
| 3017 | return prepend_path(path, root, buf, buflen); |
| 3018 | } |
| 3019 | |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3020 | static int prepend_unreachable(char **buffer, int *buflen) |
| 3021 | { |
| 3022 | return prepend(buffer, buflen, "(unreachable)", 13); |
| 3023 | } |
| 3024 | |
Linus Torvalds | 68f0d9d | 2013-09-12 13:24:55 -0700 | [diff] [blame] | 3025 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
| 3026 | { |
| 3027 | unsigned seq; |
| 3028 | |
| 3029 | do { |
| 3030 | seq = read_seqcount_begin(&fs->seq); |
| 3031 | *root = fs->root; |
| 3032 | } while (read_seqcount_retry(&fs->seq, seq)); |
| 3033 | } |
| 3034 | |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3035 | /** |
| 3036 | * d_path - return the path of a dentry |
Jan Blunck | cf28b48 | 2008-02-14 19:38:44 -0800 | [diff] [blame] | 3037 | * @path: path to report |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3038 | * @buf: buffer to return value in |
| 3039 | * @buflen: buffer length |
| 3040 | * |
| 3041 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
| 3042 | * the string " (deleted)" is appended. Note that this is ambiguous. |
| 3043 | * |
Arjan van de Ven | 52afeef | 2008-12-01 14:35:00 -0800 | [diff] [blame] | 3044 | * Returns a pointer into the buffer or an error code if the path was |
| 3045 | * too long. Note: Callers should use the returned pointer, not the passed |
| 3046 | * in buffer, to use the name! The implementation often starts at an offset |
| 3047 | * into the buffer, and may leave 0 bytes at the start. |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3048 | * |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 3049 | * "buflen" should be positive. |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 3050 | */ |
Jan Engelhardt | 20d4fdc | 2008-06-09 16:40:36 -0700 | [diff] [blame] | 3051 | char *d_path(const struct path *path, char *buf, int buflen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3052 | { |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3053 | char *res = buf + buflen; |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 3054 | struct path root; |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3055 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3056 | |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3057 | /* |
| 3058 | * We have various synthetic filesystems that never get mounted. On |
| 3059 | * these filesystems dentries are never used for lookup purposes, and |
| 3060 | * thus don't need to be hashed. They also don't need a name until a |
| 3061 | * user wants to identify the object in /proc/pid/fd/. The little hack |
| 3062 | * below allows us to generate a name for these objects on demand: |
| 3063 | */ |
Jan Blunck | cf28b48 | 2008-02-14 19:38:44 -0800 | [diff] [blame] | 3064 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
| 3065 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3066 | |
Linus Torvalds | 68f0d9d | 2013-09-12 13:24:55 -0700 | [diff] [blame] | 3067 | rcu_read_lock(); |
| 3068 | get_fs_root_rcu(current->fs, &root); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 3069 | br_read_lock(&vfsmount_lock); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3070 | error = path_with_deleted(path, &root, &res, &buflen); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 3071 | br_read_unlock(&vfsmount_lock); |
Linus Torvalds | 68f0d9d | 2013-09-12 13:24:55 -0700 | [diff] [blame] | 3072 | rcu_read_unlock(); |
| 3073 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3074 | if (error < 0) |
Miklos Szeredi | ffd1f4e | 2010-08-10 11:41:40 +0200 | [diff] [blame] | 3075 | res = ERR_PTR(error); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3076 | return res; |
| 3077 | } |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 3078 | EXPORT_SYMBOL(d_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3079 | |
| 3080 | /* |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3081 | * Helper function for dentry_operations.d_dname() members |
| 3082 | */ |
| 3083 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
| 3084 | const char *fmt, ...) |
| 3085 | { |
| 3086 | va_list args; |
| 3087 | char temp[64]; |
| 3088 | int sz; |
| 3089 | |
| 3090 | va_start(args, fmt); |
| 3091 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
| 3092 | va_end(args); |
| 3093 | |
| 3094 | if (sz > sizeof(temp) || sz > buflen) |
| 3095 | return ERR_PTR(-ENAMETOOLONG); |
| 3096 | |
| 3097 | buffer += buflen - sz; |
| 3098 | return memcpy(buffer, temp, sz); |
| 3099 | } |
| 3100 | |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3101 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
| 3102 | { |
| 3103 | char *end = buffer + buflen; |
| 3104 | /* these dentries are never renamed, so d_lock is not needed */ |
| 3105 | if (prepend(&end, &buflen, " (deleted)", 11) || |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3106 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3107 | prepend(&end, &buflen, "/", 1)) |
| 3108 | end = ERR_PTR(-ENAMETOOLONG); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3109 | return end; |
Al Viro | 118b230 | 2013-08-24 12:08:17 -0400 | [diff] [blame] | 3110 | } |
| 3111 | |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 3112 | /* |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3113 | * Write full pathname from the root of the filesystem into the buffer. |
| 3114 | */ |
Nick Piggin | ec2447c | 2011-01-07 17:49:29 +1100 | [diff] [blame] | 3115 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3116 | { |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3117 | char *end, *retval; |
| 3118 | int len, seq = 0; |
| 3119 | int error = 0; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3120 | |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 3121 | rcu_read_lock(); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3122 | restart: |
| 3123 | end = buf + buflen; |
| 3124 | len = buflen; |
| 3125 | prepend(&end, &len, "\0", 1); |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3126 | if (buflen < 1) |
| 3127 | goto Elong; |
| 3128 | /* Get '/' right */ |
| 3129 | retval = end-1; |
| 3130 | *retval = '/'; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3131 | read_seqbegin_or_lock(&rename_lock, &seq); |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 3132 | while (!IS_ROOT(dentry)) { |
| 3133 | struct dentry *parent = dentry->d_parent; |
Nick Piggin | 9abca36 | 2011-01-07 17:49:36 +1100 | [diff] [blame] | 3134 | int error; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3135 | |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3136 | prefetch(parent); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3137 | error = prepend_name(&end, &len, &dentry->d_name); |
| 3138 | if (error) |
| 3139 | break; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3140 | |
| 3141 | retval = end; |
| 3142 | dentry = parent; |
| 3143 | } |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 3144 | if (!(seq & 1)) |
| 3145 | rcu_read_unlock(); |
| 3146 | if (need_seqretry(&rename_lock, seq)) { |
| 3147 | seq = 1; |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3148 | goto restart; |
Al Viro | 48f5ec2 | 2013-09-09 15:22:25 -0400 | [diff] [blame] | 3149 | } |
| 3150 | done_seqretry(&rename_lock, seq); |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3151 | if (error) |
| 3152 | goto Elong; |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3153 | return retval; |
| 3154 | Elong: |
| 3155 | return ERR_PTR(-ENAMETOOLONG); |
| 3156 | } |
Nick Piggin | ec2447c | 2011-01-07 17:49:29 +1100 | [diff] [blame] | 3157 | |
| 3158 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
| 3159 | { |
Waiman Long | 232d2d6 | 2013-09-09 12:18:13 -0400 | [diff] [blame] | 3160 | return __dentry_path(dentry, buf, buflen); |
Nick Piggin | ec2447c | 2011-01-07 17:49:29 +1100 | [diff] [blame] | 3161 | } |
| 3162 | EXPORT_SYMBOL(dentry_path_raw); |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3163 | |
| 3164 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
| 3165 | { |
| 3166 | char *p = NULL; |
| 3167 | char *retval; |
| 3168 | |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3169 | if (d_unlinked(dentry)) { |
| 3170 | p = buf + buflen; |
| 3171 | if (prepend(&p, &buflen, "//deleted", 10) != 0) |
| 3172 | goto Elong; |
| 3173 | buflen++; |
| 3174 | } |
| 3175 | retval = __dentry_path(dentry, buf, buflen); |
Al Viro | c103135 | 2010-06-06 22:31:14 -0400 | [diff] [blame] | 3176 | if (!IS_ERR(retval) && p) |
| 3177 | *p = '/'; /* restore '/' overriden with '\0' */ |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3178 | return retval; |
| 3179 | Elong: |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3180 | return ERR_PTR(-ENAMETOOLONG); |
| 3181 | } |
| 3182 | |
Linus Torvalds | 8b19e34 | 2013-09-12 10:35:47 -0700 | [diff] [blame] | 3183 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
| 3184 | struct path *pwd) |
Linus Torvalds | 5762482 | 2013-09-12 10:12:47 -0700 | [diff] [blame] | 3185 | { |
Linus Torvalds | 8b19e34 | 2013-09-12 10:35:47 -0700 | [diff] [blame] | 3186 | unsigned seq; |
| 3187 | |
| 3188 | do { |
| 3189 | seq = read_seqcount_begin(&fs->seq); |
| 3190 | *root = fs->root; |
| 3191 | *pwd = fs->pwd; |
| 3192 | } while (read_seqcount_retry(&fs->seq, seq)); |
Linus Torvalds | 5762482 | 2013-09-12 10:12:47 -0700 | [diff] [blame] | 3193 | } |
| 3194 | |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 3195 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3196 | * NOTE! The user-level library version returns a |
| 3197 | * character pointer. The kernel system call just |
| 3198 | * returns the length of the buffer filled (which |
| 3199 | * includes the ending '\0' character), or a negative |
| 3200 | * error value. So libc would do something like |
| 3201 | * |
| 3202 | * char *getcwd(char * buf, size_t size) |
| 3203 | * { |
| 3204 | * int retval; |
| 3205 | * |
| 3206 | * retval = sys_getcwd(buf, size); |
| 3207 | * if (retval >= 0) |
| 3208 | * return buf; |
| 3209 | * errno = -retval; |
| 3210 | * return NULL; |
| 3211 | * } |
| 3212 | */ |
Heiko Carstens | 3cdad42 | 2009-01-14 14:14:22 +0100 | [diff] [blame] | 3213 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3214 | { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3215 | int error; |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 3216 | struct path pwd, root; |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3217 | char *page = __getname(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3218 | |
| 3219 | if (!page) |
| 3220 | return -ENOMEM; |
| 3221 | |
Linus Torvalds | 8b19e34 | 2013-09-12 10:35:47 -0700 | [diff] [blame] | 3222 | rcu_read_lock(); |
| 3223 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3224 | |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3225 | error = -ENOENT; |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 3226 | br_read_lock(&vfsmount_lock); |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 3227 | if (!d_unlinked(pwd.dentry)) { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3228 | unsigned long len; |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3229 | char *cwd = page + PATH_MAX; |
| 3230 | int buflen = PATH_MAX; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3231 | |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3232 | prepend(&cwd, &buflen, "\0", 1); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3233 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 3234 | br_read_unlock(&vfsmount_lock); |
Linus Torvalds | ff812d7 | 2013-09-12 11:57:01 -0700 | [diff] [blame] | 3235 | rcu_read_unlock(); |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3236 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3237 | if (error < 0) |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3238 | goto out; |
| 3239 | |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3240 | /* Unreachable from current root */ |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3241 | if (error > 0) { |
Miklos Szeredi | 8df9d1a | 2010-08-10 11:41:41 +0200 | [diff] [blame] | 3242 | error = prepend_unreachable(&cwd, &buflen); |
| 3243 | if (error) |
| 3244 | goto out; |
| 3245 | } |
| 3246 | |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3247 | error = -ERANGE; |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3248 | len = PATH_MAX + page - cwd; |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 3249 | if (len <= size) { |
| 3250 | error = len; |
| 3251 | if (copy_to_user(buf, cwd, len)) |
| 3252 | error = -EFAULT; |
| 3253 | } |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3254 | } else { |
Al Viro | 7ea600b | 2013-03-26 18:25:57 -0400 | [diff] [blame] | 3255 | br_read_unlock(&vfsmount_lock); |
Linus Torvalds | ff812d7 | 2013-09-12 11:57:01 -0700 | [diff] [blame] | 3256 | rcu_read_unlock(); |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3257 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3258 | |
| 3259 | out: |
Linus Torvalds | 3272c54 | 2013-09-12 12:40:15 -0700 | [diff] [blame] | 3260 | __putname(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3261 | return error; |
| 3262 | } |
| 3263 | |
| 3264 | /* |
| 3265 | * Test whether new_dentry is a subdirectory of old_dentry. |
| 3266 | * |
| 3267 | * Trivially implemented using the dcache structure |
| 3268 | */ |
| 3269 | |
| 3270 | /** |
| 3271 | * is_subdir - is new dentry a subdirectory of old_dentry |
| 3272 | * @new_dentry: new dentry |
| 3273 | * @old_dentry: old dentry |
| 3274 | * |
| 3275 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
| 3276 | * Returns 0 otherwise. |
| 3277 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
| 3278 | */ |
| 3279 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3280 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3281 | { |
| 3282 | int result; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3283 | unsigned seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3284 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3285 | if (new_dentry == old_dentry) |
| 3286 | return 1; |
| 3287 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3288 | do { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3289 | /* for restarting inner loop in case of seq retry */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3290 | seq = read_seqbegin(&rename_lock); |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3291 | /* |
| 3292 | * Need rcu_readlock to protect against the d_parent trashing |
| 3293 | * due to d_move |
| 3294 | */ |
| 3295 | rcu_read_lock(); |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3296 | if (d_ancestor(old_dentry, new_dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3297 | result = 1; |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 3298 | else |
| 3299 | result = 0; |
Nick Piggin | 949854d | 2011-01-07 17:49:37 +1100 | [diff] [blame] | 3300 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3301 | } while (read_seqretry(&rename_lock, seq)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3302 | |
| 3303 | return result; |
| 3304 | } |
| 3305 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3306 | 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] | 3307 | { |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3308 | struct dentry *root = data; |
| 3309 | if (dentry != root) { |
| 3310 | if (d_unhashed(dentry) || !dentry->d_inode) |
| 3311 | return D_WALK_SKIP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3312 | |
Miklos Szeredi | 01ddc4e | 2013-09-05 11:44:34 +0200 | [diff] [blame] | 3313 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
| 3314 | dentry->d_flags |= DCACHE_GENOCIDE; |
| 3315 | dentry->d_lockref.count--; |
| 3316 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3317 | } |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3318 | return D_WALK_CONTINUE; |
| 3319 | } |
Nick Piggin | 58db63d | 2011-01-07 17:49:39 +1100 | [diff] [blame] | 3320 | |
Miklos Szeredi | db14fc3 | 2013-09-05 11:44:35 +0200 | [diff] [blame] | 3321 | void d_genocide(struct dentry *parent) |
| 3322 | { |
| 3323 | d_walk(parent, parent, d_genocide_kill, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3324 | } |
| 3325 | |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3326 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3327 | { |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3328 | inode_dec_link_count(inode); |
| 3329 | BUG_ON(dentry->d_name.name != dentry->d_iname || |
| 3330 | !hlist_unhashed(&dentry->d_alias) || |
| 3331 | !d_unlinked(dentry)); |
| 3332 | spin_lock(&dentry->d_parent->d_lock); |
| 3333 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| 3334 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", |
| 3335 | (unsigned long long)inode->i_ino); |
| 3336 | spin_unlock(&dentry->d_lock); |
| 3337 | spin_unlock(&dentry->d_parent->d_lock); |
| 3338 | d_instantiate(dentry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3339 | } |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3340 | EXPORT_SYMBOL(d_tmpfile); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3341 | |
| 3342 | static __initdata unsigned long dhash_entries; |
| 3343 | static int __init set_dhash_entries(char *str) |
| 3344 | { |
| 3345 | if (!str) |
| 3346 | return 0; |
| 3347 | dhash_entries = simple_strtoul(str, &str, 0); |
| 3348 | return 1; |
| 3349 | } |
| 3350 | __setup("dhash_entries=", set_dhash_entries); |
| 3351 | |
| 3352 | static void __init dcache_init_early(void) |
| 3353 | { |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3354 | unsigned int loop; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3355 | |
| 3356 | /* If hashes are distributed across NUMA nodes, defer |
| 3357 | * hash allocation until vmalloc space is available. |
| 3358 | */ |
| 3359 | if (hashdist) |
| 3360 | return; |
| 3361 | |
| 3362 | dentry_hashtable = |
| 3363 | alloc_large_system_hash("Dentry cache", |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 3364 | sizeof(struct hlist_bl_head), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3365 | dhash_entries, |
| 3366 | 13, |
| 3367 | HASH_EARLY, |
| 3368 | &d_hash_shift, |
| 3369 | &d_hash_mask, |
Tim Bird | 31fe62b | 2012-05-23 13:33:35 +0000 | [diff] [blame] | 3370 | 0, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3371 | 0); |
| 3372 | |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3373 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
Linus Torvalds | b07ad99 | 2011-04-23 22:32:03 -0700 | [diff] [blame] | 3374 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3375 | } |
| 3376 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3377 | static void __init dcache_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3378 | { |
Dimitri Sivanich | 074b851 | 2012-02-08 12:39:07 -0800 | [diff] [blame] | 3379 | unsigned int loop; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3380 | |
| 3381 | /* |
| 3382 | * A constructor could be added for stable state like the lists, |
| 3383 | * but it is probably not worth it because of the cache nature |
| 3384 | * of the dcache. |
| 3385 | */ |
Christoph Lameter | 0a31bd5 | 2007-05-06 14:49:57 -0700 | [diff] [blame] | 3386 | dentry_cache = KMEM_CACHE(dentry, |
| 3387 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3388 | |
| 3389 | /* Hash may have been set up in dcache_init_early */ |
| 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 | 0, |
| 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 | |
| 3408 | /* SLAB cache for __getname() consumers */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 3409 | struct kmem_cache *names_cachep __read_mostly; |
H Hartley Sweeten | ec4f860 | 2010-01-05 13:45:18 -0700 | [diff] [blame] | 3410 | EXPORT_SYMBOL(names_cachep); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3411 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3412 | EXPORT_SYMBOL(d_genocide); |
| 3413 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3414 | void __init vfs_caches_init_early(void) |
| 3415 | { |
| 3416 | dcache_init_early(); |
| 3417 | inode_init_early(); |
| 3418 | } |
| 3419 | |
| 3420 | void __init vfs_caches_init(unsigned long mempages) |
| 3421 | { |
| 3422 | unsigned long reserve; |
| 3423 | |
| 3424 | /* Base hash sizes on available memory, with a reserve equal to |
| 3425 | 150% of current kernel size */ |
| 3426 | |
| 3427 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); |
| 3428 | mempages -= reserve; |
| 3429 | |
| 3430 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 3431 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3432 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3433 | dcache_init(); |
| 3434 | inode_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3435 | files_init(mempages); |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3436 | mnt_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3437 | bdev_cache_init(); |
| 3438 | chrdev_init(); |
| 3439 | } |