blob: 11828de68dceec56f90409a52dfbf29dc83b68fa [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/syscalls.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/fs.h>
John McCutchan7a91bf72005-08-08 13:52:16 -040021#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/slab.h>
23#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/hash.h>
25#include <linux/cache.h>
26#include <linux/module.h>
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 Viro5ad4e532009-03-29 19:50:06 -040034#include <linux/fs_struct.h>
Frederic Weisbecker613afbf2009-07-16 15:44:29 +020035#include <linux/hardirq.h>
Nick Pigginceb5bdc2011-01-07 17:50:05 +110036#include <linux/bit_spinlock.h>
37#include <linux/rculist_bl.h>
Linus Torvalds268bb0c2011-05-20 12:50:29 -070038#include <linux/prefetch.h>
David Howellsdd179942011-08-16 15:31:30 +010039#include <linux/ratelimit.h>
David Howells07f3f052006-09-30 20:52:18 +020040#include "internal.h"
Al Virob2dba1a2011-11-23 19:26:23 -050041#include "mount.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Nick Piggin789680d2011-01-07 17:49:30 +110043/*
44 * Usage:
Nick Piggin873feea2011-01-07 17:50:06 +110045 * dcache->d_inode->i_lock protects:
46 * - i_dentry, d_alias, d_inode of aliases
Nick Pigginceb5bdc2011-01-07 17:50:05 +110047 * dcache_hash_bucket lock protects:
48 * - the dcache hash table
49 * s_anon bl list spinlock protects:
50 * - the s_anon list (see __d_drop)
Nick Piggin23044502011-01-07 17:49:31 +110051 * dcache_lru_lock protects:
52 * - the dcache lru lists and counters
53 * d_lock protects:
54 * - d_flags
55 * - d_name
56 * - d_lru
Nick Pigginb7ab39f2011-01-07 17:49:32 +110057 * - d_count
Nick Pigginda502952011-01-07 17:49:33 +110058 * - d_unhashed()
Nick Piggin2fd6b7f2011-01-07 17:49:34 +110059 * - d_parent and d_subdirs
60 * - childrens' d_child and d_parent
Nick Pigginb23fb0a2011-01-07 17:49:35 +110061 * - d_alias, d_inode
Nick Piggin789680d2011-01-07 17:49:30 +110062 *
63 * Ordering:
Nick Piggin873feea2011-01-07 17:50:06 +110064 * dentry->d_inode->i_lock
Nick Pigginb5c84bf2011-01-07 17:49:38 +110065 * dentry->d_lock
66 * dcache_lru_lock
Nick Pigginceb5bdc2011-01-07 17:50:05 +110067 * dcache_hash_bucket lock
68 * s_anon lock
Nick Piggin789680d2011-01-07 17:49:30 +110069 *
Nick Pigginda502952011-01-07 17:49:33 +110070 * If there is an ancestor relationship:
71 * dentry->d_parent->...->d_parent->d_lock
72 * ...
73 * dentry->d_parent->d_lock
74 * dentry->d_lock
75 *
76 * If no ancestor relationship:
Nick Piggin789680d2011-01-07 17:49:30 +110077 * if (dentry1 < dentry2)
78 * dentry1->d_lock
79 * dentry2->d_lock
80 */
Eric Dumazetfa3536c2006-03-26 01:37:24 -080081int sysctl_vfs_cache_pressure __read_mostly = 100;
Linus Torvalds1da177e2005-04-16 15:20:36 -070082EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
83
Nick Piggin23044502011-01-07 17:49:31 +110084static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
Al Viro74c3cbe2007-07-22 08:04:18 -040085__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
Nick Piggin949854d2011-01-07 17:49:37 +110087EXPORT_SYMBOL(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
Christoph Lametere18b8902006-12-06 20:33:20 -080089static struct kmem_cache *dentry_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Linus Torvalds1da177e2005-04-16 15:20:36 -070091/*
92 * This is the single most critical data structure when it comes
93 * to the dcache: the hashtable for lookups. Somebody should try
94 * to make this good - I've just made it work.
95 *
96 * This hash-function tries to avoid losing too many bits of hash
97 * information, yet avoid using a prime hash-size or similar.
98 */
99#define D_HASHBITS d_hash_shift
100#define D_HASHMASK d_hash_mask
101
Eric Dumazetfa3536c2006-03-26 01:37:24 -0800102static unsigned int d_hash_mask __read_mostly;
103static unsigned int d_hash_shift __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100104
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700105static struct hlist_bl_head *dentry_hashtable __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100106
Linus Torvalds8966be92012-03-02 14:23:30 -0800107static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
Linus Torvalds6d7d1a02012-03-19 16:19:53 -0700108 unsigned int hash)
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100109{
Linus Torvalds6d7d1a02012-03-19 16:19:53 -0700110 hash += (unsigned long) parent / L1_CACHE_BYTES;
111 hash = hash + (hash >> D_HASHBITS);
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100112 return dentry_hashtable + (hash & D_HASHMASK);
113}
114
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115/* Statistics gathering. */
116struct dentry_stat_t dentry_stat = {
117 .age_limit = 45,
118};
119
Nick Piggin3e880fb2011-01-07 17:49:19 +1100120static DEFINE_PER_CPU(unsigned int, nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400121
122#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Nick Piggin3e880fb2011-01-07 17:49:19 +1100123static int get_nr_dentry(void)
124{
125 int i;
126 int sum = 0;
127 for_each_possible_cpu(i)
128 sum += per_cpu(nr_dentry, i);
129 return sum < 0 ? 0 : sum;
130}
131
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400132int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
133 size_t *lenp, loff_t *ppos)
134{
Nick Piggin3e880fb2011-01-07 17:49:19 +1100135 dentry_stat.nr_dentry = get_nr_dentry();
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400136 return proc_dointvec(table, write, buffer, lenp, ppos);
137}
138#endif
139
Linus Torvalds5483f182012-03-04 15:51:42 -0800140/*
141 * Compare 2 name strings, return 0 if they match, otherwise non-zero.
142 * The strings are both count bytes long, and count is non-zero.
143 */
144static inline int dentry_cmp(const unsigned char *cs, size_t scount,
145 const unsigned char *ct, size_t tcount)
146{
Linus Torvaldsbfcfaa72012-03-06 11:16:17 -0800147#ifdef CONFIG_DCACHE_WORD_ACCESS
148 unsigned long a,b,mask;
149
150 if (unlikely(scount != tcount))
151 return 1;
152
153 for (;;) {
154 a = *(unsigned long *)cs;
155 b = *(unsigned long *)ct;
156 if (tcount < sizeof(unsigned long))
157 break;
158 if (unlikely(a != b))
159 return 1;
160 cs += sizeof(unsigned long);
161 ct += sizeof(unsigned long);
162 tcount -= sizeof(unsigned long);
163 if (!tcount)
164 return 0;
165 }
166 mask = ~(~0ul << tcount*8);
167 return unlikely(!!((a ^ b) & mask));
168#else
Linus Torvalds5483f182012-03-04 15:51:42 -0800169 if (scount != tcount)
170 return 1;
171
172 do {
173 if (*cs != *ct)
174 return 1;
175 cs++;
176 ct++;
177 tcount--;
178 } while (tcount);
179 return 0;
Linus Torvaldsbfcfaa72012-03-06 11:16:17 -0800180#endif
Linus Torvalds5483f182012-03-04 15:51:42 -0800181}
182
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400183static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400185 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
186
Arjan van de Venfd217f42008-10-21 06:47:33 -0700187 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 if (dname_external(dentry))
189 kfree(dentry->d_name.name);
190 kmem_cache_free(dentry_cache, dentry);
191}
192
193/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100194 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 */
196static void d_free(struct dentry *dentry)
197{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100198 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100199 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 if (dentry->d_op && dentry->d_op->d_release)
201 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400202
Linus Torvaldsdea36672011-04-24 07:58:46 -0700203 /* if dentry was never visible to RCU, immediate free is OK */
204 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400205 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800206 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400207 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208}
209
Nick Piggin31e6b012011-01-07 17:49:52 +1100210/**
211 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800212 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100213 * After this call, in-progress rcu-walk path lookup will fail. This
214 * should be called after unhashing, and after changing d_inode (if
215 * the dentry has not already been unhashed).
216 */
217static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
218{
219 assert_spin_locked(&dentry->d_lock);
220 /* Go through a barrier */
221 write_seqcount_barrier(&dentry->d_seq);
222}
223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224/*
225 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100226 * d_iput() operation if defined. Dentry has no refcount
227 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800229static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200230 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100231 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232{
233 struct inode *inode = dentry->d_inode;
234 if (inode) {
235 dentry->d_inode = NULL;
236 list_del_init(&dentry->d_alias);
237 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100238 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700239 if (!inode->i_nlink)
240 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 if (dentry->d_op && dentry->d_op->d_iput)
242 dentry->d_op->d_iput(dentry, inode);
243 else
244 iput(inode);
245 } else {
246 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 }
248}
249
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700250/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100251 * Release the dentry's inode, using the filesystem
252 * d_iput() operation if defined. dentry remains in-use.
253 */
254static void dentry_unlink_inode(struct dentry * dentry)
255 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100256 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100257{
258 struct inode *inode = dentry->d_inode;
259 dentry->d_inode = NULL;
260 list_del_init(&dentry->d_alias);
261 dentry_rcuwalk_barrier(dentry);
262 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100263 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100264 if (!inode->i_nlink)
265 fsnotify_inoderemove(inode);
266 if (dentry->d_op && dentry->d_op->d_iput)
267 dentry->d_op->d_iput(dentry, inode);
268 else
269 iput(inode);
270}
271
272/*
Sage Weilf0023bc2011-10-28 10:02:42 -0700273 * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700274 */
275static void dentry_lru_add(struct dentry *dentry)
276{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400277 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100278 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400279 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
280 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100281 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100282 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400283 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700284}
285
Nick Piggin23044502011-01-07 17:49:31 +1100286static void __dentry_lru_del(struct dentry *dentry)
287{
288 list_del_init(&dentry->d_lru);
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100289 dentry->d_flags &= ~DCACHE_SHRINK_LIST;
Nick Piggin23044502011-01-07 17:49:31 +1100290 dentry->d_sb->s_nr_dentry_unused--;
291 dentry_stat.nr_unused--;
292}
293
Sage Weilf0023bc2011-10-28 10:02:42 -0700294/*
295 * Remove a dentry with references from the LRU.
296 */
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700297static void dentry_lru_del(struct dentry *dentry)
298{
299 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100300 spin_lock(&dcache_lru_lock);
301 __dentry_lru_del(dentry);
302 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700303 }
304}
305
Sage Weilf0023bc2011-10-28 10:02:42 -0700306/*
307 * Remove a dentry that is unreferenced and about to be pruned
308 * (unhashed and destroyed) from the LRU, and inform the file system.
309 * This wrapper should be called _prior_ to unhashing a victim dentry.
310 */
311static void dentry_lru_prune(struct dentry *dentry)
312{
313 if (!list_empty(&dentry->d_lru)) {
314 if (dentry->d_flags & DCACHE_OP_PRUNE)
315 dentry->d_op->d_prune(dentry);
316
317 spin_lock(&dcache_lru_lock);
318 __dentry_lru_del(dentry);
319 spin_unlock(&dcache_lru_lock);
320 }
321}
322
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000323static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700324{
Nick Piggin23044502011-01-07 17:49:31 +1100325 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400326 if (list_empty(&dentry->d_lru)) {
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000327 list_add_tail(&dentry->d_lru, list);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400328 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100329 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400330 } else {
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000331 list_move_tail(&dentry->d_lru, list);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700332 }
Nick Piggin23044502011-01-07 17:49:31 +1100333 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700334}
335
Miklos Szeredid52b9082007-05-08 00:23:46 -0700336/**
337 * d_kill - kill dentry and return parent
338 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800339 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700340 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200341 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700342 *
343 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100344 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100345 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
346 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700347 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100348static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200349 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100350 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100351 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700352{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700353 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400354 /*
355 * Inform try_to_ascend() that we are no longer attached to the
356 * dentry tree
357 */
358 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100359 if (parent)
360 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700361 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100362 /*
363 * dentry_iput drops the locks, at which point nobody (except
364 * transient RCU lookups) can reach this dentry.
365 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700366 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900367 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700368}
369
David Howellsc6627c62011-06-07 14:09:20 +0100370/*
371 * Unhash a dentry without inserting an RCU walk barrier or checking that
372 * dentry->d_lock is locked. The caller must take care of that, if
373 * appropriate.
374 */
375static void __d_shrink(struct dentry *dentry)
376{
377 if (!d_unhashed(dentry)) {
378 struct hlist_bl_head *b;
379 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
380 b = &dentry->d_sb->s_anon;
381 else
382 b = d_hash(dentry->d_parent, dentry->d_name.hash);
383
384 hlist_bl_lock(b);
385 __hlist_bl_del(&dentry->d_hash);
386 dentry->d_hash.pprev = NULL;
387 hlist_bl_unlock(b);
388 }
389}
390
Nick Piggin789680d2011-01-07 17:49:30 +1100391/**
392 * d_drop - drop a dentry
393 * @dentry: dentry to drop
394 *
395 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
396 * be found through a VFS lookup any more. Note that this is different from
397 * deleting the dentry - d_delete will try to mark the dentry negative if
398 * possible, giving a successful _negative_ lookup, while d_drop will
399 * just make the cache lookup fail.
400 *
401 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
402 * reason (NFS timeouts or autofs deletes).
403 *
404 * __d_drop requires dentry->d_lock.
405 */
406void __d_drop(struct dentry *dentry)
407{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700408 if (!d_unhashed(dentry)) {
David Howellsc6627c62011-06-07 14:09:20 +0100409 __d_shrink(dentry);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700410 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100411 }
412}
413EXPORT_SYMBOL(__d_drop);
414
415void d_drop(struct dentry *dentry)
416{
Nick Piggin789680d2011-01-07 17:49:30 +1100417 spin_lock(&dentry->d_lock);
418 __d_drop(dentry);
419 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100420}
421EXPORT_SYMBOL(d_drop);
422
Nick Piggin77812a12011-01-07 17:49:48 +1100423/*
Josef Bacik44396f42011-05-31 11:58:49 -0400424 * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag
425 * @dentry: dentry to drop
426 *
427 * This is called when we do a lookup on a placeholder dentry that needed to be
428 * looked up. The dentry should have been hashed in order for it to be found by
429 * the lookup code, but now needs to be unhashed while we do the actual lookup
430 * and clear the DCACHE_NEED_LOOKUP flag.
431 */
432void d_clear_need_lookup(struct dentry *dentry)
433{
434 spin_lock(&dentry->d_lock);
435 __d_drop(dentry);
436 dentry->d_flags &= ~DCACHE_NEED_LOOKUP;
437 spin_unlock(&dentry->d_lock);
438}
439EXPORT_SYMBOL(d_clear_need_lookup);
440
441/*
Nick Piggin77812a12011-01-07 17:49:48 +1100442 * Finish off a dentry we've decided to kill.
443 * dentry->d_lock must be held, returns with it unlocked.
444 * If ref is non-zero, then decrement the refcount too.
445 * Returns dentry requiring refcount drop, or NULL if we're done.
446 */
447static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
448 __releases(dentry->d_lock)
449{
Nick Piggin873feea2011-01-07 17:50:06 +1100450 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100451 struct dentry *parent;
452
Nick Piggin873feea2011-01-07 17:50:06 +1100453 inode = dentry->d_inode;
454 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100455relock:
456 spin_unlock(&dentry->d_lock);
457 cpu_relax();
458 return dentry; /* try again with same dentry */
459 }
460 if (IS_ROOT(dentry))
461 parent = NULL;
462 else
463 parent = dentry->d_parent;
464 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100465 if (inode)
466 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100467 goto relock;
468 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100469
Nick Piggin77812a12011-01-07 17:49:48 +1100470 if (ref)
471 dentry->d_count--;
Sage Weilf0023bc2011-10-28 10:02:42 -0700472 /*
473 * if dentry was on the d_lru list delete it from there.
474 * inform the fs via d_prune that this dentry is about to be
475 * unhashed and destroyed.
476 */
477 dentry_lru_prune(dentry);
Nick Piggin77812a12011-01-07 17:49:48 +1100478 /* if it was on the hash then remove it */
479 __d_drop(dentry);
480 return d_kill(dentry, parent);
481}
482
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483/*
484 * This is dput
485 *
486 * This is complicated by the fact that we do not want to put
487 * dentries that are no longer on any hash chain on the unused
488 * list: we'd much rather just get rid of them immediately.
489 *
490 * However, that implies that we have to traverse the dentry
491 * tree upwards to the parents which might _also_ now be
492 * scheduled for deletion (it may have been only waiting for
493 * its last child to go away).
494 *
495 * This tail recursion is done by hand as we don't want to depend
496 * on the compiler to always get this right (gcc generally doesn't).
497 * Real recursion would eat up our stack space.
498 */
499
500/*
501 * dput - release a dentry
502 * @dentry: dentry to release
503 *
504 * Release a dentry. This will drop the usage count and if appropriate
505 * call the dentry unlink method as well as removing it from the queues and
506 * releasing its resources. If the parent dentries were scheduled for release
507 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509void dput(struct dentry *dentry)
510{
511 if (!dentry)
512 return;
513
514repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100515 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100518 BUG_ON(!dentry->d_count);
519 if (dentry->d_count > 1) {
520 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 return;
523 }
524
Nick Pigginfb045ad2011-01-07 17:49:55 +1100525 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100527 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 }
Nick Piggin265ac902010-10-10 05:36:24 -0400529
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 /* Unreachable? Get rid of it */
531 if (d_unhashed(dentry))
532 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400533
Josef Bacik44396f42011-05-31 11:58:49 -0400534 /*
535 * If this dentry needs lookup, don't set the referenced flag so that it
536 * is more likely to be cleaned up by the dcache shrinker in case of
537 * memory pressure.
538 */
539 if (!d_need_lookup(dentry))
540 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400541 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400542
Nick Piggin61f3dee2011-01-07 17:49:40 +1100543 dentry->d_count--;
544 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 return;
546
Miklos Szeredid52b9082007-05-08 00:23:46 -0700547kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100548 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700549 if (dentry)
550 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700552EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553
554/**
555 * d_invalidate - invalidate a dentry
556 * @dentry: dentry to invalidate
557 *
558 * Try to invalidate the dentry if it turns out to be
559 * possible. If there are other dentries that can be
560 * reached through this one we can't delete it and we
561 * return -EBUSY. On success we return 0.
562 *
563 * no dcache lock.
564 */
565
566int d_invalidate(struct dentry * dentry)
567{
568 /*
569 * If it's already been dropped, return OK.
570 */
Nick Pigginda502952011-01-07 17:49:33 +1100571 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100573 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 return 0;
575 }
576 /*
577 * Check whether to do a partial shrink_dcache
578 * to get rid of unused child entries.
579 */
580 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100581 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100583 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 }
585
586 /*
587 * Somebody else still using it?
588 *
589 * If it's a directory, we can't drop it
590 * for fear of somebody re-populating it
591 * with children (even though dropping it
592 * would make it unreachable from the root,
593 * we might still populate it if it was a
594 * working directory or similar).
Al Viro50e69632011-11-07 16:39:57 +0000595 * We also need to leave mountpoints alone,
596 * directory or not.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 */
Al Viro50e69632011-11-07 16:39:57 +0000598 if (dentry->d_count > 1 && dentry->d_inode) {
599 if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 return -EBUSY;
602 }
603 }
604
605 __d_drop(dentry);
606 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 return 0;
608}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700609EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100611/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100612static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100614 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615}
616
Nick Piggindc0474b2011-01-07 17:49:43 +1100617static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100618{
Nick Piggin23044502011-01-07 17:49:31 +1100619 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100620 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100621 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100622}
623
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100624struct dentry *dget_parent(struct dentry *dentry)
625{
626 struct dentry *ret;
627
628repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100629 /*
630 * Don't need rcu_dereference because we re-check it was correct under
631 * the lock.
632 */
633 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100634 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100635 spin_lock(&ret->d_lock);
636 if (unlikely(ret != dentry->d_parent)) {
637 spin_unlock(&ret->d_lock);
638 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100639 goto repeat;
640 }
Nick Piggina734eb42011-01-07 17:49:44 +1100641 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100642 BUG_ON(!ret->d_count);
643 ret->d_count++;
644 spin_unlock(&ret->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100645 return ret;
646}
647EXPORT_SYMBOL(dget_parent);
648
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649/**
650 * d_find_alias - grab a hashed alias of inode
651 * @inode: inode in question
652 * @want_discon: flag, used by d_splice_alias, to request
653 * that only a DISCONNECTED alias be returned.
654 *
655 * If inode has a hashed alias, or is a directory and has any alias,
656 * acquire the reference to alias and return it. Otherwise return NULL.
657 * Notice that if inode is a directory there can be only one alias and
658 * it can be unhashed only if it has no children, or if it is the root
659 * of a filesystem.
660 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700661 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700663 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 */
Nick Pigginda502952011-01-07 17:49:33 +1100665static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666{
Nick Pigginda502952011-01-07 17:49:33 +1100667 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668
Nick Pigginda502952011-01-07 17:49:33 +1100669again:
670 discon_alias = NULL;
671 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
672 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700674 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100675 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100677 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100678 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100679 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 return alias;
681 }
682 }
Nick Pigginda502952011-01-07 17:49:33 +1100683 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 }
Nick Pigginda502952011-01-07 17:49:33 +1100685 if (discon_alias) {
686 alias = discon_alias;
687 spin_lock(&alias->d_lock);
688 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
689 if (IS_ROOT(alias) &&
690 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100691 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100692 spin_unlock(&alias->d_lock);
693 return alias;
694 }
695 }
696 spin_unlock(&alias->d_lock);
697 goto again;
698 }
699 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700}
701
Nick Pigginda502952011-01-07 17:49:33 +1100702struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703{
David Howells214fda12006-03-25 03:06:36 -0800704 struct dentry *de = NULL;
705
706 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100707 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800708 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100709 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800710 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 return de;
712}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700713EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714
715/*
716 * Try to kill dentries associated with this inode.
717 * WARNING: you must own a reference to inode.
718 */
719void d_prune_aliases(struct inode *inode)
720{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700721 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100723 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700724 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100726 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100727 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 __d_drop(dentry);
729 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100730 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 dput(dentry);
732 goto restart;
733 }
734 spin_unlock(&dentry->d_lock);
735 }
Nick Piggin873feea2011-01-07 17:50:06 +1100736 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700738EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739
740/*
Nick Piggin77812a12011-01-07 17:49:48 +1100741 * Try to throw away a dentry - free the inode, dput the parent.
742 * Requires dentry->d_lock is held, and dentry->d_count == 0.
743 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700744 *
Nick Piggin77812a12011-01-07 17:49:48 +1100745 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 */
Nick Piggin77812a12011-01-07 17:49:48 +1100747static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200748 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749{
Nick Piggin77812a12011-01-07 17:49:48 +1100750 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700751
Nick Piggin77812a12011-01-07 17:49:48 +1100752 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700753 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100754 * If dentry_kill returns NULL, we have nothing more to do.
755 * if it returns the same dentry, trylocks failed. In either
756 * case, just loop again.
757 *
758 * Otherwise, we need to prune ancestors too. This is necessary
759 * to prevent quadratic behavior of shrink_dcache_parent(), but
760 * is also expected to be beneficial in reducing dentry cache
761 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700762 */
Nick Piggin77812a12011-01-07 17:49:48 +1100763 if (!parent)
764 return;
765 if (parent == dentry)
766 return;
767
768 /* Prune ancestors. */
769 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700770 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100771 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100772 if (dentry->d_count > 1) {
773 dentry->d_count--;
774 spin_unlock(&dentry->d_lock);
775 return;
776 }
Nick Piggin77812a12011-01-07 17:49:48 +1100777 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700778 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779}
780
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400781static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700783 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700784
Nick Pigginec336792011-01-07 17:49:47 +1100785 rcu_read_lock();
786 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100787 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
788 if (&dentry->d_lru == list)
789 break; /* empty */
790 spin_lock(&dentry->d_lock);
791 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
792 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100793 continue;
794 }
795
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 /*
797 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700798 * the LRU because of laziness during lookup. Do not free
799 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100801 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100802 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700803 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 continue;
805 }
Nick Pigginec336792011-01-07 17:49:47 +1100806
Nick Pigginec336792011-01-07 17:49:47 +1100807 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100808
809 try_prune_one_dentry(dentry);
810
Nick Pigginec336792011-01-07 17:49:47 +1100811 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 }
Nick Pigginec336792011-01-07 17:49:47 +1100813 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400814}
815
816/**
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000817 * prune_dcache_sb - shrink the dcache
818 * @sb: superblock
819 * @count: number of entries to try to free
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400820 *
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000821 * Attempt to shrink the superblock dcache LRU by @count entries. This is
822 * done when we need more memory an called from the superblock shrinker
823 * function.
824 *
825 * This function may fail to free any resources if all the dentries are in
826 * use.
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400827 */
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000828void prune_dcache_sb(struct super_block *sb, int count)
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400829{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400830 struct dentry *dentry;
831 LIST_HEAD(referenced);
832 LIST_HEAD(tmp);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400833
Nick Piggin23044502011-01-07 17:49:31 +1100834relock:
835 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400836 while (!list_empty(&sb->s_dentry_lru)) {
837 dentry = list_entry(sb->s_dentry_lru.prev,
838 struct dentry, d_lru);
839 BUG_ON(dentry->d_sb != sb);
840
Nick Piggin23044502011-01-07 17:49:31 +1100841 if (!spin_trylock(&dentry->d_lock)) {
842 spin_unlock(&dcache_lru_lock);
843 cpu_relax();
844 goto relock;
845 }
846
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000847 if (dentry->d_flags & DCACHE_REFERENCED) {
Nick Piggin23044502011-01-07 17:49:31 +1100848 dentry->d_flags &= ~DCACHE_REFERENCED;
849 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400850 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100851 } else {
852 list_move_tail(&dentry->d_lru, &tmp);
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100853 dentry->d_flags |= DCACHE_SHRINK_LIST;
Nick Piggin23044502011-01-07 17:49:31 +1100854 spin_unlock(&dentry->d_lock);
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000855 if (!--count)
Nick Piggin23044502011-01-07 17:49:31 +1100856 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400857 }
Nick Pigginec336792011-01-07 17:49:47 +1100858 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400859 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700860 if (!list_empty(&referenced))
861 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100862 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100863
864 shrink_dentry_list(&tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865}
866
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700867/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 * shrink_dcache_sb - shrink dcache for a superblock
869 * @sb: superblock
870 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400871 * Shrink the dcache for the specified super block. This is used to free
872 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400874void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400876 LIST_HEAD(tmp);
877
Nick Piggin23044502011-01-07 17:49:31 +1100878 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400879 while (!list_empty(&sb->s_dentry_lru)) {
880 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100881 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400882 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100883 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400884 }
Nick Piggin23044502011-01-07 17:49:31 +1100885 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700887EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888
889/*
David Howellsc636ebd2006-10-11 01:22:19 -0700890 * destroy a single subtree of dentries for unmount
891 * - see the comments on shrink_dcache_for_umount() for a description of the
892 * locking
893 */
894static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
895{
896 struct dentry *parent;
897
898 BUG_ON(!IS_ROOT(dentry));
899
David Howellsc636ebd2006-10-11 01:22:19 -0700900 for (;;) {
901 /* descend to the first leaf in the current subtree */
David Howells43c1c9c2011-06-07 14:09:30 +0100902 while (!list_empty(&dentry->d_subdirs))
David Howellsc636ebd2006-10-11 01:22:19 -0700903 dentry = list_entry(dentry->d_subdirs.next,
904 struct dentry, d_u.d_child);
David Howellsc636ebd2006-10-11 01:22:19 -0700905
906 /* consume the dentries from this leaf up through its parents
907 * until we find one with children or run out altogether */
908 do {
909 struct inode *inode;
910
Sage Weilf0023bc2011-10-28 10:02:42 -0700911 /*
912 * remove the dentry from the lru, and inform
913 * the fs that this dentry is about to be
914 * unhashed and destroyed.
915 */
916 dentry_lru_prune(dentry);
David Howells43c1c9c2011-06-07 14:09:30 +0100917 __d_shrink(dentry);
918
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100919 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700920 printk(KERN_ERR
921 "BUG: Dentry %p{i=%lx,n=%s}"
922 " still in use (%d)"
923 " [unmount of %s %s]\n",
924 dentry,
925 dentry->d_inode ?
926 dentry->d_inode->i_ino : 0UL,
927 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100928 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700929 dentry->d_sb->s_type->name,
930 dentry->d_sb->s_id);
931 BUG();
932 }
933
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100934 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700935 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100936 list_del(&dentry->d_u.d_child);
937 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900938 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100939 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100940 list_del(&dentry->d_u.d_child);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900941 }
David Howellsc636ebd2006-10-11 01:22:19 -0700942
David Howellsc636ebd2006-10-11 01:22:19 -0700943 inode = dentry->d_inode;
944 if (inode) {
945 dentry->d_inode = NULL;
946 list_del_init(&dentry->d_alias);
947 if (dentry->d_op && dentry->d_op->d_iput)
948 dentry->d_op->d_iput(dentry, inode);
949 else
950 iput(inode);
951 }
952
953 d_free(dentry);
954
955 /* finished when we fall off the top of the tree,
956 * otherwise we ascend to the parent and move to the
957 * next sibling if there is one */
958 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400959 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700960 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700961 } while (list_empty(&dentry->d_subdirs));
962
963 dentry = list_entry(dentry->d_subdirs.next,
964 struct dentry, d_u.d_child);
965 }
966}
967
968/*
969 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100970 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700971 * - the superblock is detached from all mountings and open files, so the
972 * dentry trees will not be rearranged by the VFS
973 * - s_umount is write-locked, so the memory pressure shrinker will ignore
974 * any dentries belonging to this superblock that it comes across
975 * - the filesystem itself is no longer permitted to rearrange the dentries
976 * in this superblock
977 */
978void shrink_dcache_for_umount(struct super_block *sb)
979{
980 struct dentry *dentry;
981
982 if (down_read_trylock(&sb->s_umount))
983 BUG();
984
985 dentry = sb->s_root;
986 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100987 dentry->d_count--;
David Howellsc636ebd2006-10-11 01:22:19 -0700988 shrink_dcache_for_umount_subtree(dentry);
989
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100990 while (!hlist_bl_empty(&sb->s_anon)) {
991 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700992 shrink_dcache_for_umount_subtree(dentry);
993 }
994}
995
996/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700997 * This tries to ascend one level of parenthood, but
998 * we can race with renaming, so we need to re-check
999 * the parenthood after dropping the lock and check
1000 * that the sequence number still matches.
1001 */
1002static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
1003{
1004 struct dentry *new = old->d_parent;
1005
1006 rcu_read_lock();
1007 spin_unlock(&old->d_lock);
1008 spin_lock(&new->d_lock);
1009
1010 /*
1011 * might go back up the wrong parent if we have had a rename
1012 * or deletion
1013 */
1014 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -04001015 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001016 (!locked && read_seqretry(&rename_lock, seq))) {
1017 spin_unlock(&new->d_lock);
1018 new = NULL;
1019 }
1020 rcu_read_unlock();
1021 return new;
1022}
1023
1024
1025/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 * Search for at least 1 mount point in the dentry's subdirs.
1027 * We descend to the next level whenever the d_subdirs
1028 * list is non-empty and continue searching.
1029 */
1030
1031/**
1032 * have_submounts - check for mounts over a dentry
1033 * @parent: dentry to check.
1034 *
1035 * Return true if the parent or its subdirectories contain
1036 * a mount point
1037 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038int have_submounts(struct dentry *parent)
1039{
Nick Piggin949854d2011-01-07 17:49:37 +11001040 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001042 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11001043 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001044
Nick Piggin949854d2011-01-07 17:49:37 +11001045 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001046again:
1047 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 if (d_mountpoint(parent))
1050 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001051 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052repeat:
1053 next = this_parent->d_subdirs.next;
1054resume:
1055 while (next != &this_parent->d_subdirs) {
1056 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001057 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001059
1060 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001062 if (d_mountpoint(dentry)) {
1063 spin_unlock(&dentry->d_lock);
1064 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001066 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001068 spin_unlock(&this_parent->d_lock);
1069 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001071 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 goto repeat;
1073 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001074 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 }
1076 /*
1077 * All done at this level ... ascend and resume the search.
1078 */
1079 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001080 struct dentry *child = this_parent;
1081 this_parent = try_to_ascend(this_parent, locked, seq);
1082 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001083 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001084 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 goto resume;
1086 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001087 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001088 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001089 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001090 if (locked)
1091 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 return 0; /* No mount points found in tree */
1093positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001094 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001095 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001096 if (locked)
1097 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001099
1100rename_retry:
1101 locked = 1;
1102 write_seqlock(&rename_lock);
1103 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001105EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106
1107/*
1108 * Search the dentry child list for the specified parent,
1109 * and move any unused dentries to the end of the unused
1110 * list for prune_dcache(). We descend to the next level
1111 * whenever the d_subdirs list is non-empty and continue
1112 * searching.
1113 *
1114 * It returns zero iff there are no unused children,
1115 * otherwise it returns the number of children moved to
1116 * the end of the unused list. This may not be the total
1117 * number of unused children, because select_parent can
1118 * drop the lock and return early due to latency
1119 * constraints.
1120 */
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001121static int select_parent(struct dentry *parent, struct list_head *dispose)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122{
Nick Piggin949854d2011-01-07 17:49:37 +11001123 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001125 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001127 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
Nick Piggin949854d2011-01-07 17:49:37 +11001129 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001130again:
1131 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001132 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133repeat:
1134 next = this_parent->d_subdirs.next;
1135resume:
1136 while (next != &this_parent->d_subdirs) {
1137 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001138 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 next = tmp->next;
1140
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001141 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001142
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001143 /*
1144 * move only zero ref count dentries to the dispose list.
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001145 *
1146 * Those which are presently on the shrink list, being processed
1147 * by shrink_dentry_list(), shouldn't be moved. Otherwise the
1148 * loop in shrink_dcache_parent() might not make any progress
1149 * and loop forever.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150 */
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001151 if (dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001152 dentry_lru_del(dentry);
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001153 } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
1154 dentry_lru_move_list(dentry, dispose);
1155 dentry->d_flags |= DCACHE_SHRINK_LIST;
1156 found++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 /*
1159 * We can return to the caller if we have found some (this
1160 * ensures forward progress). We'll be coming back to find
1161 * the rest.
1162 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001163 if (found && need_resched()) {
1164 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 goto out;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167
1168 /*
1169 * Descend a level if the d_subdirs list is non-empty.
1170 */
1171 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001172 spin_unlock(&this_parent->d_lock);
1173 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001175 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 goto repeat;
1177 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001178
1179 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 }
1181 /*
1182 * All done at this level ... ascend and resume the search.
1183 */
1184 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001185 struct dentry *child = this_parent;
1186 this_parent = try_to_ascend(this_parent, locked, seq);
1187 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001188 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001189 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 goto resume;
1191 }
1192out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001193 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001194 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001195 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001196 if (locked)
1197 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 return found;
Nick Piggin58db63d2011-01-07 17:49:39 +11001199
1200rename_retry:
1201 if (found)
1202 return found;
1203 locked = 1;
1204 write_seqlock(&rename_lock);
1205 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206}
1207
1208/**
1209 * shrink_dcache_parent - prune dcache
1210 * @parent: parent of entries to prune
1211 *
1212 * Prune the dcache to remove unused children of the parent dentry.
1213 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214void shrink_dcache_parent(struct dentry * parent)
1215{
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001216 LIST_HEAD(dispose);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 int found;
1218
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001219 while ((found = select_parent(parent, &dispose)) != 0)
1220 shrink_dentry_list(&dispose);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001222EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224/**
Al Viroa4464db2011-07-07 15:03:58 -04001225 * __d_alloc - allocate a dcache entry
1226 * @sb: filesystem it will belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 * @name: qstr of the name
1228 *
1229 * Allocates a dentry. It returns %NULL if there is insufficient memory
1230 * available. On a success the dentry is returned. The name passed in is
1231 * copied and the copy passed in may be reused after this call.
1232 */
1233
Al Viroa4464db2011-07-07 15:03:58 -04001234struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235{
1236 struct dentry *dentry;
1237 char *dname;
1238
Mel Gormane12ba742007-10-16 01:25:52 -07001239 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240 if (!dentry)
1241 return NULL;
1242
1243 if (name->len > DNAME_INLINE_LEN-1) {
1244 dname = kmalloc(name->len + 1, GFP_KERNEL);
1245 if (!dname) {
1246 kmem_cache_free(dentry_cache, dentry);
1247 return NULL;
1248 }
1249 } else {
1250 dname = dentry->d_iname;
1251 }
1252 dentry->d_name.name = dname;
1253
1254 dentry->d_name.len = name->len;
1255 dentry->d_name.hash = name->hash;
1256 memcpy(dname, name->name, name->len);
1257 dname[name->len] = 0;
1258
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001259 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001260 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001262 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 dentry->d_inode = NULL;
Al Viroa4464db2011-07-07 15:03:58 -04001264 dentry->d_parent = dentry;
1265 dentry->d_sb = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 dentry->d_op = NULL;
1267 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001268 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 INIT_LIST_HEAD(&dentry->d_lru);
1270 INIT_LIST_HEAD(&dentry->d_subdirs);
1271 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001272 INIT_LIST_HEAD(&dentry->d_u.d_child);
Al Viroa4464db2011-07-07 15:03:58 -04001273 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274
Nick Piggin3e880fb2011-01-07 17:49:19 +11001275 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001276
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277 return dentry;
1278}
Al Viroa4464db2011-07-07 15:03:58 -04001279
1280/**
1281 * d_alloc - allocate a dcache entry
1282 * @parent: parent of entry to allocate
1283 * @name: qstr of the name
1284 *
1285 * Allocates a dentry. It returns %NULL if there is insufficient memory
1286 * available. On a success the dentry is returned. The name passed in is
1287 * copied and the copy passed in may be reused after this call.
1288 */
1289struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1290{
1291 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1292 if (!dentry)
1293 return NULL;
1294
1295 spin_lock(&parent->d_lock);
1296 /*
1297 * don't need child lock because it is not subject
1298 * to concurrency here
1299 */
1300 __dget_dlock(parent);
1301 dentry->d_parent = parent;
1302 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
1303 spin_unlock(&parent->d_lock);
1304
1305 return dentry;
1306}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001307EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308
Nick Piggin4b936882011-01-07 17:50:07 +11001309struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1310{
Al Viroa4464db2011-07-07 15:03:58 -04001311 struct dentry *dentry = __d_alloc(sb, name);
1312 if (dentry)
Nick Piggin4b936882011-01-07 17:50:07 +11001313 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin4b936882011-01-07 17:50:07 +11001314 return dentry;
1315}
1316EXPORT_SYMBOL(d_alloc_pseudo);
1317
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1319{
1320 struct qstr q;
1321
1322 q.name = name;
1323 q.len = strlen(name);
1324 q.hash = full_name_hash(q.name, q.len);
1325 return d_alloc(parent, &q);
1326}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001327EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328
Nick Pigginfb045ad2011-01-07 17:49:55 +11001329void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1330{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001331 WARN_ON_ONCE(dentry->d_op);
1332 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001333 DCACHE_OP_COMPARE |
1334 DCACHE_OP_REVALIDATE |
1335 DCACHE_OP_DELETE ));
1336 dentry->d_op = op;
1337 if (!op)
1338 return;
1339 if (op->d_hash)
1340 dentry->d_flags |= DCACHE_OP_HASH;
1341 if (op->d_compare)
1342 dentry->d_flags |= DCACHE_OP_COMPARE;
1343 if (op->d_revalidate)
1344 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1345 if (op->d_delete)
1346 dentry->d_flags |= DCACHE_OP_DELETE;
Sage Weilf0023bc2011-10-28 10:02:42 -07001347 if (op->d_prune)
1348 dentry->d_flags |= DCACHE_OP_PRUNE;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001349
1350}
1351EXPORT_SYMBOL(d_set_d_op);
1352
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001353static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1354{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001355 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001356 if (inode) {
1357 if (unlikely(IS_AUTOMOUNT(inode)))
1358 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001359 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001360 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001361 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001362 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001363 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001364 fsnotify_d_instantiate(dentry, inode);
1365}
1366
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367/**
1368 * d_instantiate - fill in inode information for a dentry
1369 * @entry: dentry to complete
1370 * @inode: inode to attach to this dentry
1371 *
1372 * Fill in inode information in the entry.
1373 *
1374 * This turns negative dentries into productive full members
1375 * of society.
1376 *
1377 * NOTE! This assumes that the inode count has been incremented
1378 * (or otherwise set) by the caller to indicate that it is now
1379 * in use by the dcache.
1380 */
1381
1382void d_instantiate(struct dentry *entry, struct inode * inode)
1383{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001384 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001385 if (inode)
1386 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001387 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001388 if (inode)
1389 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 security_d_instantiate(entry, inode);
1391}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001392EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393
1394/**
1395 * d_instantiate_unique - instantiate a non-aliased dentry
1396 * @entry: dentry to instantiate
1397 * @inode: inode to attach to this dentry
1398 *
1399 * Fill in inode information in the entry. On success, it returns NULL.
1400 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001401 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 *
1403 * Note that in order to avoid conflicts with rename() etc, the caller
1404 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001405 *
1406 * This also assumes that the inode count has been incremented
1407 * (or otherwise set) by the caller to indicate that it is now
1408 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 */
David Howells770bfad2006-08-22 20:06:07 -04001410static struct dentry *__d_instantiate_unique(struct dentry *entry,
1411 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412{
1413 struct dentry *alias;
1414 int len = entry->d_name.len;
1415 const char *name = entry->d_name.name;
1416 unsigned int hash = entry->d_name.hash;
1417
David Howells770bfad2006-08-22 20:06:07 -04001418 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001419 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001420 return NULL;
1421 }
1422
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1424 struct qstr *qstr = &alias->d_name;
1425
Nick Piggin9abca362011-01-07 17:49:36 +11001426 /*
1427 * Don't need alias->d_lock here, because aliases with
1428 * d_parent == entry->d_parent are not subject to name or
1429 * parent changes, because the parent inode i_mutex is held.
1430 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 if (qstr->hash != hash)
1432 continue;
1433 if (alias->d_parent != entry->d_parent)
1434 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001435 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001437 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 return alias;
1439 }
David Howells770bfad2006-08-22 20:06:07 -04001440
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001441 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 return NULL;
1443}
David Howells770bfad2006-08-22 20:06:07 -04001444
1445struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1446{
1447 struct dentry *result;
1448
1449 BUG_ON(!list_empty(&entry->d_alias));
1450
Nick Piggin873feea2011-01-07 17:50:06 +11001451 if (inode)
1452 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001453 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001454 if (inode)
1455 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001456
1457 if (!result) {
1458 security_d_instantiate(entry, inode);
1459 return NULL;
1460 }
1461
1462 BUG_ON(!d_unhashed(result));
1463 iput(inode);
1464 return result;
1465}
1466
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467EXPORT_SYMBOL(d_instantiate_unique);
1468
1469/**
1470 * d_alloc_root - allocate root dentry
1471 * @root_inode: inode to allocate the root for
1472 *
1473 * Allocate a root ("/") dentry for the inode given. The inode is
1474 * instantiated and returned. %NULL is returned if there is insufficient
1475 * memory or the inode passed is %NULL.
1476 */
1477
1478struct dentry * d_alloc_root(struct inode * root_inode)
1479{
1480 struct dentry *res = NULL;
1481
1482 if (root_inode) {
1483 static const struct qstr name = { .name = "/", .len = 1 };
1484
Al Viroa4464db2011-07-07 15:03:58 -04001485 res = __d_alloc(root_inode->i_sb, &name);
1486 if (res)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 d_instantiate(res, root_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 }
1489 return res;
1490}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001491EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492
Al Viroadc0e912012-01-08 16:49:21 -05001493struct dentry *d_make_root(struct inode *root_inode)
1494{
1495 struct dentry *res = NULL;
1496
1497 if (root_inode) {
1498 static const struct qstr name = { .name = "/", .len = 1 };
1499
1500 res = __d_alloc(root_inode->i_sb, &name);
1501 if (res)
1502 d_instantiate(res, root_inode);
1503 else
1504 iput(root_inode);
1505 }
1506 return res;
1507}
1508EXPORT_SYMBOL(d_make_root);
1509
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001510static struct dentry * __d_find_any_alias(struct inode *inode)
1511{
1512 struct dentry *alias;
1513
1514 if (list_empty(&inode->i_dentry))
1515 return NULL;
1516 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1517 __dget(alias);
1518 return alias;
1519}
1520
Sage Weil46f72b32012-01-10 09:04:37 -08001521/**
1522 * d_find_any_alias - find any alias for a given inode
1523 * @inode: inode to find an alias for
1524 *
1525 * If any aliases exist for the given inode, take and return a
1526 * reference for one of them. If no aliases exist, return %NULL.
1527 */
1528struct dentry *d_find_any_alias(struct inode *inode)
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001529{
1530 struct dentry *de;
1531
1532 spin_lock(&inode->i_lock);
1533 de = __d_find_any_alias(inode);
1534 spin_unlock(&inode->i_lock);
1535 return de;
1536}
Sage Weil46f72b32012-01-10 09:04:37 -08001537EXPORT_SYMBOL(d_find_any_alias);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001538
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001540 * d_obtain_alias - find or allocate a dentry for a given inode
1541 * @inode: inode to allocate the dentry for
1542 *
1543 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1544 * similar open by handle operations. The returned dentry may be anonymous,
1545 * or may have a full name (if the inode was already in the cache).
1546 *
1547 * When called on a directory inode, we must ensure that the inode only ever
1548 * has one dentry. If a dentry is found, that is returned instead of
1549 * allocating a new one.
1550 *
1551 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001552 * to the dentry. In case of an error the reference on the inode is released.
1553 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1554 * be passed in and will be the error will be propagate to the return value,
1555 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001556 */
1557struct dentry *d_obtain_alias(struct inode *inode)
1558{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001559 static const struct qstr anonstring = { .name = "" };
1560 struct dentry *tmp;
1561 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001562
1563 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001564 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001565 if (IS_ERR(inode))
1566 return ERR_CAST(inode);
1567
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001568 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001569 if (res)
1570 goto out_iput;
1571
Al Viroa4464db2011-07-07 15:03:58 -04001572 tmp = __d_alloc(inode->i_sb, &anonstring);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001573 if (!tmp) {
1574 res = ERR_PTR(-ENOMEM);
1575 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001576 }
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001577
Nick Piggin873feea2011-01-07 17:50:06 +11001578 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001579 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001580 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001581 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001582 dput(tmp);
1583 goto out_iput;
1584 }
1585
1586 /* attach a disconnected dentry */
1587 spin_lock(&tmp->d_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001588 tmp->d_inode = inode;
1589 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001590 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001591 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001592 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001593 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001594 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001595 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001596 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001597
Christoph Hellwig9308a612008-08-11 15:49:12 +02001598 return tmp;
1599
1600 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001601 if (res && !IS_ERR(res))
1602 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001603 iput(inode);
1604 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001605}
Benny Halevyadc48722009-02-27 14:02:59 -08001606EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607
1608/**
1609 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1610 * @inode: the inode which may have a disconnected dentry
1611 * @dentry: a negative dentry which we want to point to the inode.
1612 *
1613 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1614 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1615 * and return it, else simply d_add the inode to the dentry and return NULL.
1616 *
1617 * This is needed in the lookup routine of any filesystem that is exportable
1618 * (via knfsd) so that we can build dcache paths to directories effectively.
1619 *
1620 * If a dentry was found and moved, then it is returned. Otherwise NULL
1621 * is returned. This matches the expected return value of ->lookup.
1622 *
1623 */
1624struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1625{
1626 struct dentry *new = NULL;
1627
Al Viroa9049372011-07-08 21:20:11 -04001628 if (IS_ERR(inode))
1629 return ERR_CAST(inode);
1630
NeilBrown21c0d8f2006-10-04 02:16:16 -07001631 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001632 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 new = __d_find_alias(inode, 1);
1634 if (new) {
1635 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001636 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 d_move(new, dentry);
1639 iput(inode);
1640 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001641 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001642 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001643 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 security_d_instantiate(dentry, inode);
1645 d_rehash(dentry);
1646 }
1647 } else
1648 d_add(dentry, inode);
1649 return new;
1650}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001651EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652
Barry Naujok94035402008-05-21 16:50:46 +10001653/**
1654 * d_add_ci - lookup or allocate new dentry with case-exact name
1655 * @inode: the inode case-insensitive lookup has found
1656 * @dentry: the negative dentry that was passed to the parent's lookup func
1657 * @name: the case-exact name to be associated with the returned dentry
1658 *
1659 * This is to avoid filling the dcache with case-insensitive names to the
1660 * same inode, only the actual correct case is stored in the dcache for
1661 * case-insensitive filesystems.
1662 *
1663 * For a case-insensitive lookup match and if the the case-exact dentry
1664 * already exists in in the dcache, use it and return it.
1665 *
1666 * If no entry exists with the exact case name, allocate new dentry with
1667 * the exact case, and return the spliced entry.
1668 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001669struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001670 struct qstr *name)
1671{
1672 int error;
1673 struct dentry *found;
1674 struct dentry *new;
1675
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001676 /*
1677 * First check if a dentry matching the name already exists,
1678 * if not go ahead and create it now.
1679 */
Barry Naujok94035402008-05-21 16:50:46 +10001680 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001681 if (!found) {
1682 new = d_alloc(dentry->d_parent, name);
1683 if (!new) {
1684 error = -ENOMEM;
1685 goto err_out;
1686 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001687
Barry Naujok94035402008-05-21 16:50:46 +10001688 found = d_splice_alias(inode, new);
1689 if (found) {
1690 dput(new);
1691 return found;
1692 }
1693 return new;
1694 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001695
1696 /*
1697 * If a matching dentry exists, and it's not negative use it.
1698 *
1699 * Decrement the reference count to balance the iget() done
1700 * earlier on.
1701 */
Barry Naujok94035402008-05-21 16:50:46 +10001702 if (found->d_inode) {
1703 if (unlikely(found->d_inode != inode)) {
1704 /* This can't happen because bad inodes are unhashed. */
1705 BUG_ON(!is_bad_inode(inode));
1706 BUG_ON(!is_bad_inode(found->d_inode));
1707 }
Barry Naujok94035402008-05-21 16:50:46 +10001708 iput(inode);
1709 return found;
1710 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001711
Barry Naujok94035402008-05-21 16:50:46 +10001712 /*
Josef Bacik44396f42011-05-31 11:58:49 -04001713 * We are going to instantiate this dentry, unhash it and clear the
1714 * lookup flag so we can do that.
1715 */
1716 if (unlikely(d_need_lookup(found)))
1717 d_clear_need_lookup(found);
1718
1719 /*
Barry Naujok94035402008-05-21 16:50:46 +10001720 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001721 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001722 */
Al Viro4513d892011-07-17 10:52:14 -04001723 new = d_splice_alias(inode, found);
1724 if (new) {
1725 dput(found);
1726 found = new;
Barry Naujok94035402008-05-21 16:50:46 +10001727 }
Al Viro4513d892011-07-17 10:52:14 -04001728 return found;
Barry Naujok94035402008-05-21 16:50:46 +10001729
1730err_out:
1731 iput(inode);
1732 return ERR_PTR(error);
1733}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001734EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735
1736/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001737 * __d_lookup_rcu - search for a dentry (racy, store-free)
1738 * @parent: parent dentry
1739 * @name: qstr of name we wish to find
1740 * @seq: returns d_seq value at the point where the dentry was found
1741 * @inode: returns dentry->d_inode when the inode was found valid.
1742 * Returns: dentry, or NULL
1743 *
1744 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1745 * resolution (store-free path walking) design described in
1746 * Documentation/filesystems/path-lookup.txt.
1747 *
1748 * This is not to be used outside core vfs.
1749 *
1750 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1751 * held, and rcu_read_lock held. The returned dentry must not be stored into
1752 * without taking d_lock and checking d_seq sequence count against @seq
1753 * returned here.
1754 *
1755 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1756 * function.
1757 *
1758 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1759 * the returned dentry, so long as its parent's seqlock is checked after the
1760 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1761 * is formed, giving integrity down the path walk.
1762 */
Linus Torvalds8966be92012-03-02 14:23:30 -08001763struct dentry *__d_lookup_rcu(const struct dentry *parent,
1764 const struct qstr *name,
1765 unsigned *seqp, struct inode **inode)
Nick Piggin31e6b012011-01-07 17:49:52 +11001766{
1767 unsigned int len = name->len;
1768 unsigned int hash = name->hash;
1769 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001770 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001771 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001772 struct dentry *dentry;
1773
1774 /*
1775 * Note: There is significant duplication with __d_lookup_rcu which is
1776 * required to prevent single threaded performance regressions
1777 * especially on architectures where smp_rmb (in seqcounts) are costly.
1778 * Keep the two functions in sync.
1779 */
1780
1781 /*
1782 * The hash list is protected using RCU.
1783 *
1784 * Carefully use d_seq when comparing a candidate dentry, to avoid
1785 * races with d_move().
1786 *
1787 * It is possible that concurrent renames can mess up our list
1788 * walk here and result in missing our dentry, resulting in the
1789 * false-negative result. d_lookup() protects against concurrent
1790 * renames using rename_lock seqlock.
1791 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001792 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001793 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001794 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Linus Torvalds8966be92012-03-02 14:23:30 -08001795 unsigned seq;
Nick Piggin31e6b012011-01-07 17:49:52 +11001796 struct inode *i;
1797 const char *tname;
1798 int tlen;
1799
1800 if (dentry->d_name.hash != hash)
1801 continue;
1802
1803seqretry:
Linus Torvalds8966be92012-03-02 14:23:30 -08001804 seq = read_seqcount_begin(&dentry->d_seq);
Nick Piggin31e6b012011-01-07 17:49:52 +11001805 if (dentry->d_parent != parent)
1806 continue;
1807 if (d_unhashed(dentry))
1808 continue;
1809 tlen = dentry->d_name.len;
1810 tname = dentry->d_name.name;
1811 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001812 prefetch(tname);
Nick Piggin31e6b012011-01-07 17:49:52 +11001813 /*
1814 * This seqcount check is required to ensure name and
1815 * len are loaded atomically, so as not to walk off the
1816 * edge of memory when walking. If we could load this
1817 * atomically some other way, we could drop this check.
1818 */
Linus Torvalds8966be92012-03-02 14:23:30 -08001819 if (read_seqcount_retry(&dentry->d_seq, seq))
Nick Piggin31e6b012011-01-07 17:49:52 +11001820 goto seqretry;
Linus Torvalds830c0f02011-08-06 22:41:50 -07001821 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001822 if (parent->d_op->d_compare(parent, *inode,
1823 dentry, i,
1824 tlen, tname, name))
1825 continue;
1826 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001827 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001828 continue;
1829 }
1830 /*
1831 * No extra seqcount check is required after the name
1832 * compare. The caller must perform a seqcount check in
1833 * order to do anything useful with the returned dentry
1834 * anyway.
1835 */
Linus Torvalds8966be92012-03-02 14:23:30 -08001836 *seqp = seq;
Nick Piggin31e6b012011-01-07 17:49:52 +11001837 *inode = i;
1838 return dentry;
1839 }
1840 return NULL;
1841}
1842
1843/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 * d_lookup - search for a dentry
1845 * @parent: parent dentry
1846 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001847 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001849 * d_lookup searches the children of the parent dentry for the name in
1850 * question. If the dentry is found its reference count is incremented and the
1851 * dentry is returned. The caller must use dput to free the entry when it has
1852 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001854struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855{
Nick Piggin31e6b012011-01-07 17:49:52 +11001856 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001857 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858
1859 do {
1860 seq = read_seqbegin(&rename_lock);
1861 dentry = __d_lookup(parent, name);
1862 if (dentry)
1863 break;
1864 } while (read_seqretry(&rename_lock, seq));
1865 return dentry;
1866}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001867EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868
Nick Piggin31e6b012011-01-07 17:49:52 +11001869/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001870 * __d_lookup - search for a dentry (racy)
1871 * @parent: parent dentry
1872 * @name: qstr of name we wish to find
1873 * Returns: dentry, or NULL
1874 *
1875 * __d_lookup is like d_lookup, however it may (rarely) return a
1876 * false-negative result due to unrelated rename activity.
1877 *
1878 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1879 * however it must be used carefully, eg. with a following d_lookup in
1880 * the case of failure.
1881 *
1882 * __d_lookup callers must be commented.
1883 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001884struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885{
1886 unsigned int len = name->len;
1887 unsigned int hash = name->hash;
1888 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001889 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001890 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001891 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001892 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
Nick Pigginb04f7842010-08-18 04:37:34 +10001894 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001895 * Note: There is significant duplication with __d_lookup_rcu which is
1896 * required to prevent single threaded performance regressions
1897 * especially on architectures where smp_rmb (in seqcounts) are costly.
1898 * Keep the two functions in sync.
1899 */
1900
1901 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001902 * The hash list is protected using RCU.
1903 *
1904 * Take d_lock when comparing a candidate dentry, to avoid races
1905 * with d_move().
1906 *
1907 * It is possible that concurrent renames can mess up our list
1908 * walk here and result in missing our dentry, resulting in the
1909 * false-negative result. d_lookup() protects against concurrent
1910 * renames using rename_lock seqlock.
1911 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001912 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001913 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 rcu_read_lock();
1915
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001916 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001917 const char *tname;
1918 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920 if (dentry->d_name.hash != hash)
1921 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922
1923 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 if (dentry->d_parent != parent)
1925 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001926 if (d_unhashed(dentry))
1927 goto next;
1928
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 /*
1930 * It is safe to compare names since d_move() cannot
1931 * change the qstr (protected by d_lock).
1932 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001933 tlen = dentry->d_name.len;
1934 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001935 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001936 if (parent->d_op->d_compare(parent, parent->d_inode,
1937 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001938 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 goto next;
1940 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001941 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942 goto next;
1943 }
1944
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001945 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001946 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947 spin_unlock(&dentry->d_lock);
1948 break;
1949next:
1950 spin_unlock(&dentry->d_lock);
1951 }
1952 rcu_read_unlock();
1953
1954 return found;
1955}
1956
1957/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001958 * d_hash_and_lookup - hash the qstr then search for a dentry
1959 * @dir: Directory to search in
1960 * @name: qstr of name we wish to find
1961 *
1962 * On hash failure or on lookup failure NULL is returned.
1963 */
1964struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1965{
1966 struct dentry *dentry = NULL;
1967
1968 /*
1969 * Check for a fs-specific hash function. Note that we must
1970 * calculate the standard hash first, as the d_op->d_hash()
1971 * routine may choose to leave the hash value unchanged.
1972 */
1973 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001974 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001975 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001976 goto out;
1977 }
1978 dentry = d_lookup(dir, name);
1979out:
1980 return dentry;
1981}
1982
1983/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001984 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001986 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 *
1988 * An insecure source has sent us a dentry, here we verify it and dget() it.
1989 * This is used by ncpfs in its readdir implementation.
1990 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001991 *
1992 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001994int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995{
Nick Piggin786a5e12011-01-07 17:49:16 +11001996 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001997
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001998 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001999 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
2000 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002001 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11002002 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002003 spin_unlock(&dentry->d_lock);
2004 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005 return 1;
2006 }
2007 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002008 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11002009
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 return 0;
2011}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002012EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013
2014/*
2015 * When a file is deleted, we have two options:
2016 * - turn this dentry into a negative dentry
2017 * - unhash this dentry and free it.
2018 *
2019 * Usually, we want to just turn this into
2020 * a negative dentry, but if anybody else is
2021 * currently using the dentry or the inode
2022 * we can't do that and we fall back on removing
2023 * it from the hash queues and waiting for
2024 * it to be deleted later when it has no users
2025 */
2026
2027/**
2028 * d_delete - delete a dentry
2029 * @dentry: The dentry to delete
2030 *
2031 * Turn the dentry into a negative dentry if possible, otherwise
2032 * remove it from the hash queues so it can be deleted later
2033 */
2034
2035void d_delete(struct dentry * dentry)
2036{
Nick Piggin873feea2011-01-07 17:50:06 +11002037 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04002038 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 /*
2040 * Are we the only user?
2041 */
Nick Piggin357f8e62011-01-07 17:49:42 +11002042again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002044 inode = dentry->d_inode;
2045 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002046 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11002047 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11002048 spin_unlock(&dentry->d_lock);
2049 cpu_relax();
2050 goto again;
2051 }
Al Viro13e3c5e2010-05-21 16:11:04 -04002052 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11002053 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04002054 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055 return;
2056 }
2057
2058 if (!d_unhashed(dentry))
2059 __d_drop(dentry);
2060
2061 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04002062
2063 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002064}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002065EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002067static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002069 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002070 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07002071 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002072 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002073 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002074}
2075
David Howells770bfad2006-08-22 20:06:07 -04002076static void _d_rehash(struct dentry * entry)
2077{
2078 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2079}
2080
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081/**
2082 * d_rehash - add an entry back to the hash
2083 * @entry: dentry to add to the hash
2084 *
2085 * Adds a dentry to the hash according to its name.
2086 */
2087
2088void d_rehash(struct dentry * entry)
2089{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002091 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002093}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002094EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002096/**
2097 * dentry_update_name_case - update case insensitive dentry with a new name
2098 * @dentry: dentry to be updated
2099 * @name: new name
2100 *
2101 * Update a case insensitive dentry with new case of name.
2102 *
2103 * dentry must have been returned by d_lookup with name @name. Old and new
2104 * name lengths must match (ie. no d_compare which allows mismatched name
2105 * lengths).
2106 *
2107 * Parent inode i_mutex must be held over d_lookup and into this call (to
2108 * keep renames and concurrent inserts, and readdir(2) away).
2109 */
2110void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2111{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002112 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002113 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2114
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002115 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002116 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002117 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002118 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002119 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002120}
2121EXPORT_SYMBOL(dentry_update_name_case);
2122
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123static void switch_names(struct dentry *dentry, struct dentry *target)
2124{
2125 if (dname_external(target)) {
2126 if (dname_external(dentry)) {
2127 /*
2128 * Both external: swap the pointers
2129 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002130 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131 } else {
2132 /*
2133 * dentry:internal, target:external. Steal target's
2134 * storage and make target internal.
2135 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002136 memcpy(target->d_iname, dentry->d_name.name,
2137 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002138 dentry->d_name.name = target->d_name.name;
2139 target->d_name.name = target->d_iname;
2140 }
2141 } else {
2142 if (dname_external(dentry)) {
2143 /*
2144 * dentry:external, target:internal. Give dentry's
2145 * storage to target and make dentry internal
2146 */
2147 memcpy(dentry->d_iname, target->d_name.name,
2148 target->d_name.len + 1);
2149 target->d_name.name = dentry->d_name.name;
2150 dentry->d_name.name = dentry->d_iname;
2151 } else {
2152 /*
2153 * Both are internal. Just copy target to dentry
2154 */
2155 memcpy(dentry->d_iname, target->d_name.name,
2156 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002157 dentry->d_name.len = target->d_name.len;
2158 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159 }
2160 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002161 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162}
2163
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002164static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2165{
2166 /*
2167 * XXXX: do we really need to take target->d_lock?
2168 */
2169 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2170 spin_lock(&target->d_parent->d_lock);
2171 else {
2172 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2173 spin_lock(&dentry->d_parent->d_lock);
2174 spin_lock_nested(&target->d_parent->d_lock,
2175 DENTRY_D_LOCK_NESTED);
2176 } else {
2177 spin_lock(&target->d_parent->d_lock);
2178 spin_lock_nested(&dentry->d_parent->d_lock,
2179 DENTRY_D_LOCK_NESTED);
2180 }
2181 }
2182 if (target < dentry) {
2183 spin_lock_nested(&target->d_lock, 2);
2184 spin_lock_nested(&dentry->d_lock, 3);
2185 } else {
2186 spin_lock_nested(&dentry->d_lock, 2);
2187 spin_lock_nested(&target->d_lock, 3);
2188 }
2189}
2190
2191static void dentry_unlock_parents_for_move(struct dentry *dentry,
2192 struct dentry *target)
2193{
2194 if (target->d_parent != dentry->d_parent)
2195 spin_unlock(&dentry->d_parent->d_lock);
2196 if (target->d_parent != target)
2197 spin_unlock(&target->d_parent->d_lock);
2198}
2199
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002201 * When switching names, the actual string doesn't strictly have to
2202 * be preserved in the target - because we're dropping the target
2203 * anyway. As such, we can just do a simple memcpy() to copy over
2204 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002206 * Note that we have to be a lot more careful about getting the hash
2207 * switched - we have to switch the hash value properly even if it
2208 * then no longer matches the actual (corrupted) string of the target.
2209 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002211/*
Al Viro18367502011-07-12 21:42:24 -04002212 * __d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213 * @dentry: entry to move
2214 * @target: new dentry
2215 *
2216 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002217 * dcache entries should not be moved in this way. Caller must hold
2218 * rename_lock, the i_mutex of the source and target directories,
2219 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 */
Al Viro18367502011-07-12 21:42:24 -04002221static void __d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223 if (!dentry->d_inode)
2224 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2225
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002226 BUG_ON(d_ancestor(dentry, target));
2227 BUG_ON(d_ancestor(target, dentry));
2228
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002229 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002230
Nick Piggin31e6b012011-01-07 17:49:52 +11002231 write_seqcount_begin(&dentry->d_seq);
2232 write_seqcount_begin(&target->d_seq);
2233
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002234 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2235
2236 /*
2237 * Move the dentry to the target hash queue. Don't bother checking
2238 * for the same hash queue because of how unlikely it is.
2239 */
2240 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002241 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002242
2243 /* Unhash the target: dput() will then get rid of it */
2244 __d_drop(target);
2245
Eric Dumazet5160ee62006-01-08 01:03:32 -08002246 list_del(&dentry->d_u.d_child);
2247 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248
2249 /* Switch the names.. */
2250 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002251 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252
2253 /* ... and switch the parents */
2254 if (IS_ROOT(dentry)) {
2255 dentry->d_parent = target->d_parent;
2256 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002257 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002259 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260
2261 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002262 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 }
2264
Eric Dumazet5160ee62006-01-08 01:03:32 -08002265 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002266
Nick Piggin31e6b012011-01-07 17:49:52 +11002267 write_seqcount_end(&target->d_seq);
2268 write_seqcount_end(&dentry->d_seq);
2269
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002270 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002271 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002272 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273 spin_unlock(&dentry->d_lock);
Al Viro18367502011-07-12 21:42:24 -04002274}
2275
2276/*
2277 * d_move - move a dentry
2278 * @dentry: entry to move
2279 * @target: new dentry
2280 *
2281 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002282 * dcache entries should not be moved in this way. See the locking
2283 * requirements for __d_move.
Al Viro18367502011-07-12 21:42:24 -04002284 */
2285void d_move(struct dentry *dentry, struct dentry *target)
2286{
2287 write_seqlock(&rename_lock);
2288 __d_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002289 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002290}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002291EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002293/**
2294 * d_ancestor - search for an ancestor
2295 * @p1: ancestor dentry
2296 * @p2: child dentry
2297 *
2298 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2299 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002300 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002301struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002302{
2303 struct dentry *p;
2304
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002305 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002306 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002307 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002308 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002309 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002310}
2311
2312/*
2313 * This helper attempts to cope with remotely renamed directories
2314 *
2315 * It assumes that the caller is already holding
Al Viro18367502011-07-12 21:42:24 -04002316 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002317 *
2318 * Note: If ever the locking in lock_rename() changes, then please
2319 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002320 */
Nick Piggin873feea2011-01-07 17:50:06 +11002321static struct dentry *__d_unalias(struct inode *inode,
2322 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002323{
2324 struct mutex *m1 = NULL, *m2 = NULL;
2325 struct dentry *ret;
2326
2327 /* If alias and dentry share a parent, then no extra locks required */
2328 if (alias->d_parent == dentry->d_parent)
2329 goto out_unalias;
2330
Trond Myklebust9eaef272006-10-21 10:24:20 -07002331 /* See lock_rename() */
2332 ret = ERR_PTR(-EBUSY);
2333 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2334 goto out_err;
2335 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2336 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2337 goto out_err;
2338 m2 = &alias->d_parent->d_inode->i_mutex;
2339out_unalias:
Al Viro18367502011-07-12 21:42:24 -04002340 __d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002341 ret = alias;
2342out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002343 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002344 if (m2)
2345 mutex_unlock(m2);
2346 if (m1)
2347 mutex_unlock(m1);
2348 return ret;
2349}
2350
2351/*
David Howells770bfad2006-08-22 20:06:07 -04002352 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2353 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002354 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002355 */
2356static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2357{
2358 struct dentry *dparent, *aparent;
2359
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002360 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002361
Nick Piggin31e6b012011-01-07 17:49:52 +11002362 write_seqcount_begin(&dentry->d_seq);
2363 write_seqcount_begin(&anon->d_seq);
2364
David Howells770bfad2006-08-22 20:06:07 -04002365 dparent = dentry->d_parent;
2366 aparent = anon->d_parent;
2367
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002368 switch_names(dentry, anon);
2369 swap(dentry->d_name.hash, anon->d_name.hash);
2370
David Howells770bfad2006-08-22 20:06:07 -04002371 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2372 list_del(&dentry->d_u.d_child);
2373 if (!IS_ROOT(dentry))
2374 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2375 else
2376 INIT_LIST_HEAD(&dentry->d_u.d_child);
2377
2378 anon->d_parent = (dparent == dentry) ? anon : dparent;
2379 list_del(&anon->d_u.d_child);
2380 if (!IS_ROOT(anon))
2381 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2382 else
2383 INIT_LIST_HEAD(&anon->d_u.d_child);
2384
Nick Piggin31e6b012011-01-07 17:49:52 +11002385 write_seqcount_end(&dentry->d_seq);
2386 write_seqcount_end(&anon->d_seq);
2387
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002388 dentry_unlock_parents_for_move(anon, dentry);
2389 spin_unlock(&dentry->d_lock);
2390
2391 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002392 anon->d_flags &= ~DCACHE_DISCONNECTED;
2393}
2394
2395/**
2396 * d_materialise_unique - introduce an inode into the tree
2397 * @dentry: candidate dentry
2398 * @inode: inode to bind to the dentry, to which aliases may be attached
2399 *
2400 * Introduces an dentry into the tree, substituting an extant disconnected
Jeff Laytonc46c8872011-07-26 13:33:16 -04002401 * root directory alias in its place if there is one. Caller must hold the
2402 * i_mutex of the parent directory.
David Howells770bfad2006-08-22 20:06:07 -04002403 */
2404struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2405{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002406 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002407
2408 BUG_ON(!d_unhashed(dentry));
2409
David Howells770bfad2006-08-22 20:06:07 -04002410 if (!inode) {
2411 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002412 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002413 d_rehash(actual);
2414 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002415 }
2416
Nick Piggin873feea2011-01-07 17:50:06 +11002417 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002418
Trond Myklebust9eaef272006-10-21 10:24:20 -07002419 if (S_ISDIR(inode->i_mode)) {
2420 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002421
Trond Myklebust9eaef272006-10-21 10:24:20 -07002422 /* Does an aliased dentry already exist? */
2423 alias = __d_find_alias(inode, 0);
2424 if (alias) {
2425 actual = alias;
Al Viro18367502011-07-12 21:42:24 -04002426 write_seqlock(&rename_lock);
2427
2428 if (d_ancestor(alias, dentry)) {
2429 /* Check for loops */
2430 actual = ERR_PTR(-ELOOP);
2431 } else if (IS_ROOT(alias)) {
2432 /* Is this an anonymous mountpoint that we
2433 * could splice into our tree? */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002434 __d_materialise_dentry(dentry, alias);
Al Viro18367502011-07-12 21:42:24 -04002435 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002436 __d_drop(alias);
2437 goto found;
Al Viro18367502011-07-12 21:42:24 -04002438 } else {
2439 /* Nope, but we must(!) avoid directory
2440 * aliasing */
2441 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002442 }
Al Viro18367502011-07-12 21:42:24 -04002443 write_sequnlock(&rename_lock);
David Howellsdd179942011-08-16 15:31:30 +01002444 if (IS_ERR(actual)) {
2445 if (PTR_ERR(actual) == -ELOOP)
2446 pr_warn_ratelimited(
2447 "VFS: Lookup of '%s' in %s %s"
2448 " would have caused loop\n",
2449 dentry->d_name.name,
2450 inode->i_sb->s_type->name,
2451 inode->i_sb->s_id);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002452 dput(alias);
David Howellsdd179942011-08-16 15:31:30 +01002453 }
Trond Myklebust9eaef272006-10-21 10:24:20 -07002454 goto out_nolock;
2455 }
David Howells770bfad2006-08-22 20:06:07 -04002456 }
2457
2458 /* Add a unique reference */
2459 actual = __d_instantiate_unique(dentry, inode);
2460 if (!actual)
2461 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002462 else
2463 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002464
David Howells770bfad2006-08-22 20:06:07 -04002465 spin_lock(&actual->d_lock);
2466found:
2467 _d_rehash(actual);
2468 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002469 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002470out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002471 if (actual == dentry) {
2472 security_d_instantiate(dentry, inode);
2473 return NULL;
2474 }
2475
2476 iput(inode);
2477 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002478}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002479EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002480
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002481static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002482{
2483 *buflen -= namelen;
2484 if (*buflen < 0)
2485 return -ENAMETOOLONG;
2486 *buffer -= namelen;
2487 memcpy(*buffer, str, namelen);
2488 return 0;
2489}
2490
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002491static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2492{
2493 return prepend(buffer, buflen, name->name, name->len);
2494}
2495
Linus Torvalds1da177e2005-04-16 15:20:36 -07002496/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002497 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002498 * @path: the dentry/vfsmount to report
Al Viro02125a82011-12-05 08:43:34 -05002499 * @root: root vfsmnt/dentry
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002500 * @buffer: pointer to the end of the buffer
2501 * @buflen: pointer to buffer length
2502 *
Nick Piggin949854d2011-01-07 17:49:37 +11002503 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002504 */
Al Viro02125a82011-12-05 08:43:34 -05002505static int prepend_path(const struct path *path,
2506 const struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002507 char **buffer, int *buflen)
2508{
2509 struct dentry *dentry = path->dentry;
2510 struct vfsmount *vfsmnt = path->mnt;
Al Viro0714a532011-11-24 22:19:58 -05002511 struct mount *mnt = real_mount(vfsmnt);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002512 bool slash = false;
2513 int error = 0;
2514
Nick Piggin99b7db72010-08-18 04:37:39 +10002515 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002516 while (dentry != root->dentry || vfsmnt != root->mnt) {
2517 struct dentry * parent;
2518
2519 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2520 /* Global root? */
Al Viro676da582011-11-24 21:47:05 -05002521 if (!mnt_has_parent(mnt))
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002522 goto global_root;
Al Viroa73324d2011-11-24 22:25:07 -05002523 dentry = mnt->mnt_mountpoint;
Al Viro0714a532011-11-24 22:19:58 -05002524 mnt = mnt->mnt_parent;
2525 vfsmnt = &mnt->mnt;
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002526 continue;
2527 }
2528 parent = dentry->d_parent;
2529 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002530 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002531 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002532 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002533 if (!error)
2534 error = prepend(buffer, buflen, "/", 1);
2535 if (error)
2536 break;
2537
2538 slash = true;
2539 dentry = parent;
2540 }
2541
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002542 if (!error && !slash)
2543 error = prepend(buffer, buflen, "/", 1);
2544
Al Viro02125a82011-12-05 08:43:34 -05002545out:
Nick Piggin99b7db72010-08-18 04:37:39 +10002546 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002547 return error;
2548
2549global_root:
2550 /*
2551 * Filesystems needing to implement special "root names"
2552 * should do so with ->d_dname()
2553 */
2554 if (IS_ROOT(dentry) &&
2555 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2556 WARN(1, "Root dentry has weird name <%.*s>\n",
2557 (int) dentry->d_name.len, dentry->d_name.name);
2558 }
Al Viro02125a82011-12-05 08:43:34 -05002559 if (!slash)
2560 error = prepend(buffer, buflen, "/", 1);
2561 if (!error)
Al Viro143c8c92011-11-25 00:46:35 -05002562 error = real_mount(vfsmnt)->mnt_ns ? 1 : 2;
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002563 goto out;
2564}
2565
2566/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002567 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002568 * @path: the dentry/vfsmount to report
Al Viro02125a82011-12-05 08:43:34 -05002569 * @root: root vfsmnt/dentry
Randy Dunlapcd956a12010-08-14 13:05:31 -07002570 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571 * @buflen: buffer length
2572 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002573 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002575 * Returns a pointer into the buffer or an error code if the
2576 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002577 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002578 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002579 *
Al Viro02125a82011-12-05 08:43:34 -05002580 * If the path is not reachable from the supplied root, return %NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581 */
Al Viro02125a82011-12-05 08:43:34 -05002582char *__d_path(const struct path *path,
2583 const struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002584 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002585{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002586 char *res = buf + buflen;
2587 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002588
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002589 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002590 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002591 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002592 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002593
Al Viro02125a82011-12-05 08:43:34 -05002594 if (error < 0)
2595 return ERR_PTR(error);
2596 if (error > 0)
2597 return NULL;
2598 return res;
2599}
2600
2601char *d_absolute_path(const struct path *path,
2602 char *buf, int buflen)
2603{
2604 struct path root = {};
2605 char *res = buf + buflen;
2606 int error;
2607
2608 prepend(&res, &buflen, "\0", 1);
2609 write_seqlock(&rename_lock);
2610 error = prepend_path(path, &root, &res, &buflen);
2611 write_sequnlock(&rename_lock);
2612
2613 if (error > 1)
2614 error = -EINVAL;
2615 if (error < 0)
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002616 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002617 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002618}
2619
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002620/*
2621 * same as __d_path but appends "(deleted)" for unlinked files.
2622 */
Al Viro02125a82011-12-05 08:43:34 -05002623static int path_with_deleted(const struct path *path,
2624 const struct path *root,
2625 char **buf, int *buflen)
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002626{
2627 prepend(buf, buflen, "\0", 1);
2628 if (d_unlinked(path->dentry)) {
2629 int error = prepend(buf, buflen, " (deleted)", 10);
2630 if (error)
2631 return error;
2632 }
2633
2634 return prepend_path(path, root, buf, buflen);
2635}
2636
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002637static int prepend_unreachable(char **buffer, int *buflen)
2638{
2639 return prepend(buffer, buflen, "(unreachable)", 13);
2640}
2641
Jan Bluncka03a8a702008-02-14 19:38:32 -08002642/**
2643 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002644 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002645 * @buf: buffer to return value in
2646 * @buflen: buffer length
2647 *
2648 * Convert a dentry into an ASCII path name. If the entry has been deleted
2649 * the string " (deleted)" is appended. Note that this is ambiguous.
2650 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002651 * Returns a pointer into the buffer or an error code if the path was
2652 * too long. Note: Callers should use the returned pointer, not the passed
2653 * in buffer, to use the name! The implementation often starts at an offset
2654 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002655 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002656 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002657 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002658char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002659{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002660 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002661 struct path root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002662 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002664 /*
2665 * We have various synthetic filesystems that never get mounted. On
2666 * these filesystems dentries are never used for lookup purposes, and
2667 * thus don't need to be hashed. They also don't need a name until a
2668 * user wants to identify the object in /proc/pid/fd/. The little hack
2669 * below allows us to generate a name for these objects on demand:
2670 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002671 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2672 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002673
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002674 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002675 write_seqlock(&rename_lock);
Al Viro02125a82011-12-05 08:43:34 -05002676 error = path_with_deleted(path, &root, &res, &buflen);
2677 if (error < 0)
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002678 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002679 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002680 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002681 return res;
2682}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002683EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002684
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002685/**
2686 * d_path_with_unreachable - return the path of a dentry
2687 * @path: path to report
2688 * @buf: buffer to return value in
2689 * @buflen: buffer length
2690 *
2691 * The difference from d_path() is that this prepends "(unreachable)"
2692 * to paths which are unreachable from the current process' root.
2693 */
2694char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2695{
2696 char *res = buf + buflen;
2697 struct path root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002698 int error;
2699
2700 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2701 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2702
2703 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002704 write_seqlock(&rename_lock);
Al Viro02125a82011-12-05 08:43:34 -05002705 error = path_with_deleted(path, &root, &res, &buflen);
2706 if (error > 0)
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002707 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002708 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002709 path_put(&root);
2710 if (error)
2711 res = ERR_PTR(error);
2712
2713 return res;
2714}
2715
Linus Torvalds1da177e2005-04-16 15:20:36 -07002716/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002717 * Helper function for dentry_operations.d_dname() members
2718 */
2719char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2720 const char *fmt, ...)
2721{
2722 va_list args;
2723 char temp[64];
2724 int sz;
2725
2726 va_start(args, fmt);
2727 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2728 va_end(args);
2729
2730 if (sz > sizeof(temp) || sz > buflen)
2731 return ERR_PTR(-ENAMETOOLONG);
2732
2733 buffer += buflen - sz;
2734 return memcpy(buffer, temp, sz);
2735}
2736
2737/*
Ram Pai6092d042008-03-27 13:06:20 +01002738 * Write full pathname from the root of the filesystem into the buffer.
2739 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002740static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002741{
2742 char *end = buf + buflen;
2743 char *retval;
2744
Ram Pai6092d042008-03-27 13:06:20 +01002745 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002746 if (buflen < 1)
2747 goto Elong;
2748 /* Get '/' right */
2749 retval = end-1;
2750 *retval = '/';
2751
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002752 while (!IS_ROOT(dentry)) {
2753 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002754 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002755
Ram Pai6092d042008-03-27 13:06:20 +01002756 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002757 spin_lock(&dentry->d_lock);
2758 error = prepend_name(&end, &buflen, &dentry->d_name);
2759 spin_unlock(&dentry->d_lock);
2760 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002761 goto Elong;
2762
2763 retval = end;
2764 dentry = parent;
2765 }
Al Viroc1031352010-06-06 22:31:14 -04002766 return retval;
2767Elong:
2768 return ERR_PTR(-ENAMETOOLONG);
2769}
Nick Pigginec2447c2011-01-07 17:49:29 +11002770
2771char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2772{
2773 char *retval;
2774
Nick Piggin949854d2011-01-07 17:49:37 +11002775 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002776 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002777 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002778
2779 return retval;
2780}
2781EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002782
2783char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2784{
2785 char *p = NULL;
2786 char *retval;
2787
Nick Piggin949854d2011-01-07 17:49:37 +11002788 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002789 if (d_unlinked(dentry)) {
2790 p = buf + buflen;
2791 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2792 goto Elong;
2793 buflen++;
2794 }
2795 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002796 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002797 if (!IS_ERR(retval) && p)
2798 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002799 return retval;
2800Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002801 return ERR_PTR(-ENAMETOOLONG);
2802}
2803
2804/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002805 * NOTE! The user-level library version returns a
2806 * character pointer. The kernel system call just
2807 * returns the length of the buffer filled (which
2808 * includes the ending '\0' character), or a negative
2809 * error value. So libc would do something like
2810 *
2811 * char *getcwd(char * buf, size_t size)
2812 * {
2813 * int retval;
2814 *
2815 * retval = sys_getcwd(buf, size);
2816 * if (retval >= 0)
2817 * return buf;
2818 * errno = -retval;
2819 * return NULL;
2820 * }
2821 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002822SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823{
Linus Torvalds552ce542007-02-13 12:08:18 -08002824 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002825 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002826 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002827
2828 if (!page)
2829 return -ENOMEM;
2830
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002831 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002832
Linus Torvalds552ce542007-02-13 12:08:18 -08002833 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002834 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002835 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002836 unsigned long len;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002837 char *cwd = page + PAGE_SIZE;
2838 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002839
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002840 prepend(&cwd, &buflen, "\0", 1);
Al Viro02125a82011-12-05 08:43:34 -05002841 error = prepend_path(&pwd, &root, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002842 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002843
Al Viro02125a82011-12-05 08:43:34 -05002844 if (error < 0)
Linus Torvalds552ce542007-02-13 12:08:18 -08002845 goto out;
2846
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002847 /* Unreachable from current root */
Al Viro02125a82011-12-05 08:43:34 -05002848 if (error > 0) {
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002849 error = prepend_unreachable(&cwd, &buflen);
2850 if (error)
2851 goto out;
2852 }
2853
Linus Torvalds552ce542007-02-13 12:08:18 -08002854 error = -ERANGE;
2855 len = PAGE_SIZE + page - cwd;
2856 if (len <= size) {
2857 error = len;
2858 if (copy_to_user(buf, cwd, len))
2859 error = -EFAULT;
2860 }
Nick Piggin949854d2011-01-07 17:49:37 +11002861 } else {
2862 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002863 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002864
2865out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002866 path_put(&pwd);
2867 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002868 free_page((unsigned long) page);
2869 return error;
2870}
2871
2872/*
2873 * Test whether new_dentry is a subdirectory of old_dentry.
2874 *
2875 * Trivially implemented using the dcache structure
2876 */
2877
2878/**
2879 * is_subdir - is new dentry a subdirectory of old_dentry
2880 * @new_dentry: new dentry
2881 * @old_dentry: old dentry
2882 *
2883 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2884 * Returns 0 otherwise.
2885 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2886 */
2887
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002888int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002889{
2890 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002891 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002892
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002893 if (new_dentry == old_dentry)
2894 return 1;
2895
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002896 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002897 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002898 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002899 /*
2900 * Need rcu_readlock to protect against the d_parent trashing
2901 * due to d_move
2902 */
2903 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002904 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002905 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002906 else
2907 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002908 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002909 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002910
2911 return result;
2912}
2913
2914void d_genocide(struct dentry *root)
2915{
Nick Piggin949854d2011-01-07 17:49:37 +11002916 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002917 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002918 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002919 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920
Nick Piggin949854d2011-01-07 17:49:37 +11002921 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002922again:
2923 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002924 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002925repeat:
2926 next = this_parent->d_subdirs.next;
2927resume:
2928 while (next != &this_parent->d_subdirs) {
2929 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002930 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002931 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002932
Nick Pigginda502952011-01-07 17:49:33 +11002933 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2934 if (d_unhashed(dentry) || !dentry->d_inode) {
2935 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002936 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002937 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002939 spin_unlock(&this_parent->d_lock);
2940 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002941 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002942 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002943 goto repeat;
2944 }
Nick Piggin949854d2011-01-07 17:49:37 +11002945 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2946 dentry->d_flags |= DCACHE_GENOCIDE;
2947 dentry->d_count--;
2948 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002949 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950 }
2951 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002952 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002953 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2954 this_parent->d_flags |= DCACHE_GENOCIDE;
2955 this_parent->d_count--;
2956 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002957 this_parent = try_to_ascend(this_parent, locked, seq);
2958 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002959 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002960 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002961 goto resume;
2962 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002963 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002964 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002965 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002966 if (locked)
2967 write_sequnlock(&rename_lock);
2968 return;
2969
2970rename_retry:
2971 locked = 1;
2972 write_seqlock(&rename_lock);
2973 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002974}
2975
2976/**
2977 * find_inode_number - check for dentry with name
2978 * @dir: directory to check
2979 * @name: Name to find.
2980 *
2981 * Check whether a dentry already exists for the given name,
2982 * and return the inode number if it has an inode. Otherwise
2983 * 0 is returned.
2984 *
2985 * This routine is used to post-process directory listings for
2986 * filesystems using synthetic inode numbers, and is necessary
2987 * to keep getcwd() working.
2988 */
2989
2990ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2991{
2992 struct dentry * dentry;
2993 ino_t ino = 0;
2994
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002995 dentry = d_hash_and_lookup(dir, name);
2996 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002997 if (dentry->d_inode)
2998 ino = dentry->d_inode->i_ino;
2999 dput(dentry);
3000 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003001 return ino;
3002}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003003EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003004
3005static __initdata unsigned long dhash_entries;
3006static int __init set_dhash_entries(char *str)
3007{
3008 if (!str)
3009 return 0;
3010 dhash_entries = simple_strtoul(str, &str, 0);
3011 return 1;
3012}
3013__setup("dhash_entries=", set_dhash_entries);
3014
3015static void __init dcache_init_early(void)
3016{
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003017 unsigned int loop;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003018
3019 /* If hashes are distributed across NUMA nodes, defer
3020 * hash allocation until vmalloc space is available.
3021 */
3022 if (hashdist)
3023 return;
3024
3025 dentry_hashtable =
3026 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003027 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003028 dhash_entries,
3029 13,
3030 HASH_EARLY,
3031 &d_hash_shift,
3032 &d_hash_mask,
3033 0);
3034
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003035 for (loop = 0; loop < (1U << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003036 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003037}
3038
Denis Cheng74bf17c2007-10-16 23:26:30 -07003039static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003040{
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003041 unsigned int loop;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003042
3043 /*
3044 * A constructor could be added for stable state like the lists,
3045 * but it is probably not worth it because of the cache nature
3046 * of the dcache.
3047 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07003048 dentry_cache = KMEM_CACHE(dentry,
3049 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003050
3051 /* Hash may have been set up in dcache_init_early */
3052 if (!hashdist)
3053 return;
3054
3055 dentry_hashtable =
3056 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003057 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003058 dhash_entries,
3059 13,
3060 0,
3061 &d_hash_shift,
3062 &d_hash_mask,
3063 0);
3064
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003065 for (loop = 0; loop < (1U << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003066 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003067}
3068
3069/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08003070struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003071EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003072
Linus Torvalds1da177e2005-04-16 15:20:36 -07003073EXPORT_SYMBOL(d_genocide);
3074
Linus Torvalds1da177e2005-04-16 15:20:36 -07003075void __init vfs_caches_init_early(void)
3076{
3077 dcache_init_early();
3078 inode_init_early();
3079}
3080
3081void __init vfs_caches_init(unsigned long mempages)
3082{
3083 unsigned long reserve;
3084
3085 /* Base hash sizes on available memory, with a reserve equal to
3086 150% of current kernel size */
3087
3088 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3089 mempages -= reserve;
3090
3091 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003092 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003093
Denis Cheng74bf17c2007-10-16 23:26:30 -07003094 dcache_init();
3095 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003096 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003097 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003098 bdev_cache_init();
3099 chrdev_init();
3100}