blob: 5f00a6f63c9e32851ace3d6a45b792d6fe43ab20 [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{
147 if (scount != tcount)
148 return 1;
149
150 do {
151 if (*cs != *ct)
152 return 1;
153 cs++;
154 ct++;
155 tcount--;
156 } while (tcount);
157 return 0;
158}
159
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400160static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400162 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
163
Arjan van de Venfd217f42008-10-21 06:47:33 -0700164 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 if (dname_external(dentry))
166 kfree(dentry->d_name.name);
167 kmem_cache_free(dentry_cache, dentry);
168}
169
170/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100171 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 */
173static void d_free(struct dentry *dentry)
174{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100175 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100176 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 if (dentry->d_op && dentry->d_op->d_release)
178 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400179
Linus Torvaldsdea36672011-04-24 07:58:46 -0700180 /* if dentry was never visible to RCU, immediate free is OK */
181 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400182 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800183 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400184 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185}
186
Nick Piggin31e6b012011-01-07 17:49:52 +1100187/**
188 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800189 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100190 * After this call, in-progress rcu-walk path lookup will fail. This
191 * should be called after unhashing, and after changing d_inode (if
192 * the dentry has not already been unhashed).
193 */
194static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
195{
196 assert_spin_locked(&dentry->d_lock);
197 /* Go through a barrier */
198 write_seqcount_barrier(&dentry->d_seq);
199}
200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201/*
202 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100203 * d_iput() operation if defined. Dentry has no refcount
204 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800206static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200207 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100208 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209{
210 struct inode *inode = dentry->d_inode;
211 if (inode) {
212 dentry->d_inode = NULL;
213 list_del_init(&dentry->d_alias);
214 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100215 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700216 if (!inode->i_nlink)
217 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 if (dentry->d_op && dentry->d_op->d_iput)
219 dentry->d_op->d_iput(dentry, inode);
220 else
221 iput(inode);
222 } else {
223 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 }
225}
226
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700227/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100228 * Release the dentry's inode, using the filesystem
229 * d_iput() operation if defined. dentry remains in-use.
230 */
231static void dentry_unlink_inode(struct dentry * dentry)
232 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100233 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100234{
235 struct inode *inode = dentry->d_inode;
236 dentry->d_inode = NULL;
237 list_del_init(&dentry->d_alias);
238 dentry_rcuwalk_barrier(dentry);
239 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100240 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100241 if (!inode->i_nlink)
242 fsnotify_inoderemove(inode);
243 if (dentry->d_op && dentry->d_op->d_iput)
244 dentry->d_op->d_iput(dentry, inode);
245 else
246 iput(inode);
247}
248
249/*
Sage Weilf0023bc2011-10-28 10:02:42 -0700250 * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700251 */
252static void dentry_lru_add(struct dentry *dentry)
253{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400254 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100255 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400256 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
257 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100258 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100259 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400260 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700261}
262
Nick Piggin23044502011-01-07 17:49:31 +1100263static void __dentry_lru_del(struct dentry *dentry)
264{
265 list_del_init(&dentry->d_lru);
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100266 dentry->d_flags &= ~DCACHE_SHRINK_LIST;
Nick Piggin23044502011-01-07 17:49:31 +1100267 dentry->d_sb->s_nr_dentry_unused--;
268 dentry_stat.nr_unused--;
269}
270
Sage Weilf0023bc2011-10-28 10:02:42 -0700271/*
272 * Remove a dentry with references from the LRU.
273 */
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700274static void dentry_lru_del(struct dentry *dentry)
275{
276 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100277 spin_lock(&dcache_lru_lock);
278 __dentry_lru_del(dentry);
279 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700280 }
281}
282
Sage Weilf0023bc2011-10-28 10:02:42 -0700283/*
284 * Remove a dentry that is unreferenced and about to be pruned
285 * (unhashed and destroyed) from the LRU, and inform the file system.
286 * This wrapper should be called _prior_ to unhashing a victim dentry.
287 */
288static void dentry_lru_prune(struct dentry *dentry)
289{
290 if (!list_empty(&dentry->d_lru)) {
291 if (dentry->d_flags & DCACHE_OP_PRUNE)
292 dentry->d_op->d_prune(dentry);
293
294 spin_lock(&dcache_lru_lock);
295 __dentry_lru_del(dentry);
296 spin_unlock(&dcache_lru_lock);
297 }
298}
299
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000300static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700301{
Nick Piggin23044502011-01-07 17:49:31 +1100302 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400303 if (list_empty(&dentry->d_lru)) {
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000304 list_add_tail(&dentry->d_lru, list);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400305 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100306 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400307 } else {
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000308 list_move_tail(&dentry->d_lru, list);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700309 }
Nick Piggin23044502011-01-07 17:49:31 +1100310 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700311}
312
Miklos Szeredid52b9082007-05-08 00:23:46 -0700313/**
314 * d_kill - kill dentry and return parent
315 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800316 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700317 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200318 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700319 *
320 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100321 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100322 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
323 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700324 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100325static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200326 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100327 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100328 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700329{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700330 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400331 /*
332 * Inform try_to_ascend() that we are no longer attached to the
333 * dentry tree
334 */
335 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100336 if (parent)
337 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700338 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100339 /*
340 * dentry_iput drops the locks, at which point nobody (except
341 * transient RCU lookups) can reach this dentry.
342 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700343 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900344 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700345}
346
David Howellsc6627c62011-06-07 14:09:20 +0100347/*
348 * Unhash a dentry without inserting an RCU walk barrier or checking that
349 * dentry->d_lock is locked. The caller must take care of that, if
350 * appropriate.
351 */
352static void __d_shrink(struct dentry *dentry)
353{
354 if (!d_unhashed(dentry)) {
355 struct hlist_bl_head *b;
356 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
357 b = &dentry->d_sb->s_anon;
358 else
359 b = d_hash(dentry->d_parent, dentry->d_name.hash);
360
361 hlist_bl_lock(b);
362 __hlist_bl_del(&dentry->d_hash);
363 dentry->d_hash.pprev = NULL;
364 hlist_bl_unlock(b);
365 }
366}
367
Nick Piggin789680d2011-01-07 17:49:30 +1100368/**
369 * d_drop - drop a dentry
370 * @dentry: dentry to drop
371 *
372 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
373 * be found through a VFS lookup any more. Note that this is different from
374 * deleting the dentry - d_delete will try to mark the dentry negative if
375 * possible, giving a successful _negative_ lookup, while d_drop will
376 * just make the cache lookup fail.
377 *
378 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
379 * reason (NFS timeouts or autofs deletes).
380 *
381 * __d_drop requires dentry->d_lock.
382 */
383void __d_drop(struct dentry *dentry)
384{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700385 if (!d_unhashed(dentry)) {
David Howellsc6627c62011-06-07 14:09:20 +0100386 __d_shrink(dentry);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700387 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100388 }
389}
390EXPORT_SYMBOL(__d_drop);
391
392void d_drop(struct dentry *dentry)
393{
Nick Piggin789680d2011-01-07 17:49:30 +1100394 spin_lock(&dentry->d_lock);
395 __d_drop(dentry);
396 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100397}
398EXPORT_SYMBOL(d_drop);
399
Nick Piggin77812a12011-01-07 17:49:48 +1100400/*
Josef Bacik44396f42011-05-31 11:58:49 -0400401 * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag
402 * @dentry: dentry to drop
403 *
404 * This is called when we do a lookup on a placeholder dentry that needed to be
405 * looked up. The dentry should have been hashed in order for it to be found by
406 * the lookup code, but now needs to be unhashed while we do the actual lookup
407 * and clear the DCACHE_NEED_LOOKUP flag.
408 */
409void d_clear_need_lookup(struct dentry *dentry)
410{
411 spin_lock(&dentry->d_lock);
412 __d_drop(dentry);
413 dentry->d_flags &= ~DCACHE_NEED_LOOKUP;
414 spin_unlock(&dentry->d_lock);
415}
416EXPORT_SYMBOL(d_clear_need_lookup);
417
418/*
Nick Piggin77812a12011-01-07 17:49:48 +1100419 * Finish off a dentry we've decided to kill.
420 * dentry->d_lock must be held, returns with it unlocked.
421 * If ref is non-zero, then decrement the refcount too.
422 * Returns dentry requiring refcount drop, or NULL if we're done.
423 */
424static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
425 __releases(dentry->d_lock)
426{
Nick Piggin873feea2011-01-07 17:50:06 +1100427 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100428 struct dentry *parent;
429
Nick Piggin873feea2011-01-07 17:50:06 +1100430 inode = dentry->d_inode;
431 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100432relock:
433 spin_unlock(&dentry->d_lock);
434 cpu_relax();
435 return dentry; /* try again with same dentry */
436 }
437 if (IS_ROOT(dentry))
438 parent = NULL;
439 else
440 parent = dentry->d_parent;
441 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100442 if (inode)
443 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100444 goto relock;
445 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100446
Nick Piggin77812a12011-01-07 17:49:48 +1100447 if (ref)
448 dentry->d_count--;
Sage Weilf0023bc2011-10-28 10:02:42 -0700449 /*
450 * if dentry was on the d_lru list delete it from there.
451 * inform the fs via d_prune that this dentry is about to be
452 * unhashed and destroyed.
453 */
454 dentry_lru_prune(dentry);
Nick Piggin77812a12011-01-07 17:49:48 +1100455 /* if it was on the hash then remove it */
456 __d_drop(dentry);
457 return d_kill(dentry, parent);
458}
459
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460/*
461 * This is dput
462 *
463 * This is complicated by the fact that we do not want to put
464 * dentries that are no longer on any hash chain on the unused
465 * list: we'd much rather just get rid of them immediately.
466 *
467 * However, that implies that we have to traverse the dentry
468 * tree upwards to the parents which might _also_ now be
469 * scheduled for deletion (it may have been only waiting for
470 * its last child to go away).
471 *
472 * This tail recursion is done by hand as we don't want to depend
473 * on the compiler to always get this right (gcc generally doesn't).
474 * Real recursion would eat up our stack space.
475 */
476
477/*
478 * dput - release a dentry
479 * @dentry: dentry to release
480 *
481 * Release a dentry. This will drop the usage count and if appropriate
482 * call the dentry unlink method as well as removing it from the queues and
483 * releasing its resources. If the parent dentries were scheduled for release
484 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486void dput(struct dentry *dentry)
487{
488 if (!dentry)
489 return;
490
491repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100492 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100495 BUG_ON(!dentry->d_count);
496 if (dentry->d_count > 1) {
497 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 return;
500 }
501
Nick Pigginfb045ad2011-01-07 17:49:55 +1100502 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100504 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 }
Nick Piggin265ac902010-10-10 05:36:24 -0400506
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 /* Unreachable? Get rid of it */
508 if (d_unhashed(dentry))
509 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400510
Josef Bacik44396f42011-05-31 11:58:49 -0400511 /*
512 * If this dentry needs lookup, don't set the referenced flag so that it
513 * is more likely to be cleaned up by the dcache shrinker in case of
514 * memory pressure.
515 */
516 if (!d_need_lookup(dentry))
517 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400518 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400519
Nick Piggin61f3dee2011-01-07 17:49:40 +1100520 dentry->d_count--;
521 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 return;
523
Miklos Szeredid52b9082007-05-08 00:23:46 -0700524kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100525 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700526 if (dentry)
527 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700529EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530
531/**
532 * d_invalidate - invalidate a dentry
533 * @dentry: dentry to invalidate
534 *
535 * Try to invalidate the dentry if it turns out to be
536 * possible. If there are other dentries that can be
537 * reached through this one we can't delete it and we
538 * return -EBUSY. On success we return 0.
539 *
540 * no dcache lock.
541 */
542
543int d_invalidate(struct dentry * dentry)
544{
545 /*
546 * If it's already been dropped, return OK.
547 */
Nick Pigginda502952011-01-07 17:49:33 +1100548 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100550 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 return 0;
552 }
553 /*
554 * Check whether to do a partial shrink_dcache
555 * to get rid of unused child entries.
556 */
557 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100558 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100560 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 }
562
563 /*
564 * Somebody else still using it?
565 *
566 * If it's a directory, we can't drop it
567 * for fear of somebody re-populating it
568 * with children (even though dropping it
569 * would make it unreachable from the root,
570 * we might still populate it if it was a
571 * working directory or similar).
Al Viro50e69632011-11-07 16:39:57 +0000572 * We also need to leave mountpoints alone,
573 * directory or not.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 */
Al Viro50e69632011-11-07 16:39:57 +0000575 if (dentry->d_count > 1 && dentry->d_inode) {
576 if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 return -EBUSY;
579 }
580 }
581
582 __d_drop(dentry);
583 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 return 0;
585}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700586EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100588/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100589static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100591 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592}
593
Nick Piggindc0474b2011-01-07 17:49:43 +1100594static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100595{
Nick Piggin23044502011-01-07 17:49:31 +1100596 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100597 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100598 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100599}
600
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100601struct dentry *dget_parent(struct dentry *dentry)
602{
603 struct dentry *ret;
604
605repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100606 /*
607 * Don't need rcu_dereference because we re-check it was correct under
608 * the lock.
609 */
610 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100611 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100612 spin_lock(&ret->d_lock);
613 if (unlikely(ret != dentry->d_parent)) {
614 spin_unlock(&ret->d_lock);
615 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100616 goto repeat;
617 }
Nick Piggina734eb42011-01-07 17:49:44 +1100618 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100619 BUG_ON(!ret->d_count);
620 ret->d_count++;
621 spin_unlock(&ret->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100622 return ret;
623}
624EXPORT_SYMBOL(dget_parent);
625
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626/**
627 * d_find_alias - grab a hashed alias of inode
628 * @inode: inode in question
629 * @want_discon: flag, used by d_splice_alias, to request
630 * that only a DISCONNECTED alias be returned.
631 *
632 * If inode has a hashed alias, or is a directory and has any alias,
633 * acquire the reference to alias and return it. Otherwise return NULL.
634 * Notice that if inode is a directory there can be only one alias and
635 * it can be unhashed only if it has no children, or if it is the root
636 * of a filesystem.
637 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700638 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700640 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 */
Nick Pigginda502952011-01-07 17:49:33 +1100642static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643{
Nick Pigginda502952011-01-07 17:49:33 +1100644 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645
Nick Pigginda502952011-01-07 17:49:33 +1100646again:
647 discon_alias = NULL;
648 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
649 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700651 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100652 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100654 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100655 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100656 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 return alias;
658 }
659 }
Nick Pigginda502952011-01-07 17:49:33 +1100660 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 }
Nick Pigginda502952011-01-07 17:49:33 +1100662 if (discon_alias) {
663 alias = discon_alias;
664 spin_lock(&alias->d_lock);
665 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
666 if (IS_ROOT(alias) &&
667 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100668 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100669 spin_unlock(&alias->d_lock);
670 return alias;
671 }
672 }
673 spin_unlock(&alias->d_lock);
674 goto again;
675 }
676 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677}
678
Nick Pigginda502952011-01-07 17:49:33 +1100679struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680{
David Howells214fda12006-03-25 03:06:36 -0800681 struct dentry *de = NULL;
682
683 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100684 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800685 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100686 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800687 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 return de;
689}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700690EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691
692/*
693 * Try to kill dentries associated with this inode.
694 * WARNING: you must own a reference to inode.
695 */
696void d_prune_aliases(struct inode *inode)
697{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700698 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100700 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700701 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100703 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100704 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 __d_drop(dentry);
706 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100707 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 dput(dentry);
709 goto restart;
710 }
711 spin_unlock(&dentry->d_lock);
712 }
Nick Piggin873feea2011-01-07 17:50:06 +1100713 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700715EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716
717/*
Nick Piggin77812a12011-01-07 17:49:48 +1100718 * Try to throw away a dentry - free the inode, dput the parent.
719 * Requires dentry->d_lock is held, and dentry->d_count == 0.
720 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700721 *
Nick Piggin77812a12011-01-07 17:49:48 +1100722 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 */
Nick Piggin77812a12011-01-07 17:49:48 +1100724static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200725 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726{
Nick Piggin77812a12011-01-07 17:49:48 +1100727 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700728
Nick Piggin77812a12011-01-07 17:49:48 +1100729 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700730 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100731 * If dentry_kill returns NULL, we have nothing more to do.
732 * if it returns the same dentry, trylocks failed. In either
733 * case, just loop again.
734 *
735 * Otherwise, we need to prune ancestors too. This is necessary
736 * to prevent quadratic behavior of shrink_dcache_parent(), but
737 * is also expected to be beneficial in reducing dentry cache
738 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700739 */
Nick Piggin77812a12011-01-07 17:49:48 +1100740 if (!parent)
741 return;
742 if (parent == dentry)
743 return;
744
745 /* Prune ancestors. */
746 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700747 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100748 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100749 if (dentry->d_count > 1) {
750 dentry->d_count--;
751 spin_unlock(&dentry->d_lock);
752 return;
753 }
Nick Piggin77812a12011-01-07 17:49:48 +1100754 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700755 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756}
757
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400758static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700760 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700761
Nick Pigginec336792011-01-07 17:49:47 +1100762 rcu_read_lock();
763 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100764 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
765 if (&dentry->d_lru == list)
766 break; /* empty */
767 spin_lock(&dentry->d_lock);
768 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
769 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100770 continue;
771 }
772
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 /*
774 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700775 * the LRU because of laziness during lookup. Do not free
776 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100778 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100779 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700780 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 continue;
782 }
Nick Pigginec336792011-01-07 17:49:47 +1100783
Nick Pigginec336792011-01-07 17:49:47 +1100784 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100785
786 try_prune_one_dentry(dentry);
787
Nick Pigginec336792011-01-07 17:49:47 +1100788 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 }
Nick Pigginec336792011-01-07 17:49:47 +1100790 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400791}
792
793/**
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000794 * prune_dcache_sb - shrink the dcache
795 * @sb: superblock
796 * @count: number of entries to try to free
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400797 *
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000798 * Attempt to shrink the superblock dcache LRU by @count entries. This is
799 * done when we need more memory an called from the superblock shrinker
800 * function.
801 *
802 * This function may fail to free any resources if all the dentries are in
803 * use.
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400804 */
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000805void prune_dcache_sb(struct super_block *sb, int count)
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400806{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400807 struct dentry *dentry;
808 LIST_HEAD(referenced);
809 LIST_HEAD(tmp);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400810
Nick Piggin23044502011-01-07 17:49:31 +1100811relock:
812 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400813 while (!list_empty(&sb->s_dentry_lru)) {
814 dentry = list_entry(sb->s_dentry_lru.prev,
815 struct dentry, d_lru);
816 BUG_ON(dentry->d_sb != sb);
817
Nick Piggin23044502011-01-07 17:49:31 +1100818 if (!spin_trylock(&dentry->d_lock)) {
819 spin_unlock(&dcache_lru_lock);
820 cpu_relax();
821 goto relock;
822 }
823
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000824 if (dentry->d_flags & DCACHE_REFERENCED) {
Nick Piggin23044502011-01-07 17:49:31 +1100825 dentry->d_flags &= ~DCACHE_REFERENCED;
826 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400827 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100828 } else {
829 list_move_tail(&dentry->d_lru, &tmp);
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100830 dentry->d_flags |= DCACHE_SHRINK_LIST;
Nick Piggin23044502011-01-07 17:49:31 +1100831 spin_unlock(&dentry->d_lock);
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000832 if (!--count)
Nick Piggin23044502011-01-07 17:49:31 +1100833 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400834 }
Nick Pigginec336792011-01-07 17:49:47 +1100835 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400836 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700837 if (!list_empty(&referenced))
838 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100839 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100840
841 shrink_dentry_list(&tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842}
843
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700844/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845 * shrink_dcache_sb - shrink dcache for a superblock
846 * @sb: superblock
847 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400848 * Shrink the dcache for the specified super block. This is used to free
849 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400851void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400853 LIST_HEAD(tmp);
854
Nick Piggin23044502011-01-07 17:49:31 +1100855 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400856 while (!list_empty(&sb->s_dentry_lru)) {
857 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100858 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400859 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100860 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400861 }
Nick Piggin23044502011-01-07 17:49:31 +1100862 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700864EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865
866/*
David Howellsc636ebd2006-10-11 01:22:19 -0700867 * destroy a single subtree of dentries for unmount
868 * - see the comments on shrink_dcache_for_umount() for a description of the
869 * locking
870 */
871static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
872{
873 struct dentry *parent;
874
875 BUG_ON(!IS_ROOT(dentry));
876
David Howellsc636ebd2006-10-11 01:22:19 -0700877 for (;;) {
878 /* descend to the first leaf in the current subtree */
David Howells43c1c9c2011-06-07 14:09:30 +0100879 while (!list_empty(&dentry->d_subdirs))
David Howellsc636ebd2006-10-11 01:22:19 -0700880 dentry = list_entry(dentry->d_subdirs.next,
881 struct dentry, d_u.d_child);
David Howellsc636ebd2006-10-11 01:22:19 -0700882
883 /* consume the dentries from this leaf up through its parents
884 * until we find one with children or run out altogether */
885 do {
886 struct inode *inode;
887
Sage Weilf0023bc2011-10-28 10:02:42 -0700888 /*
889 * remove the dentry from the lru, and inform
890 * the fs that this dentry is about to be
891 * unhashed and destroyed.
892 */
893 dentry_lru_prune(dentry);
David Howells43c1c9c2011-06-07 14:09:30 +0100894 __d_shrink(dentry);
895
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100896 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700897 printk(KERN_ERR
898 "BUG: Dentry %p{i=%lx,n=%s}"
899 " still in use (%d)"
900 " [unmount of %s %s]\n",
901 dentry,
902 dentry->d_inode ?
903 dentry->d_inode->i_ino : 0UL,
904 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100905 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700906 dentry->d_sb->s_type->name,
907 dentry->d_sb->s_id);
908 BUG();
909 }
910
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100911 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700912 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100913 list_del(&dentry->d_u.d_child);
914 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900915 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100916 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100917 list_del(&dentry->d_u.d_child);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900918 }
David Howellsc636ebd2006-10-11 01:22:19 -0700919
David Howellsc636ebd2006-10-11 01:22:19 -0700920 inode = dentry->d_inode;
921 if (inode) {
922 dentry->d_inode = NULL;
923 list_del_init(&dentry->d_alias);
924 if (dentry->d_op && dentry->d_op->d_iput)
925 dentry->d_op->d_iput(dentry, inode);
926 else
927 iput(inode);
928 }
929
930 d_free(dentry);
931
932 /* finished when we fall off the top of the tree,
933 * otherwise we ascend to the parent and move to the
934 * next sibling if there is one */
935 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400936 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700937 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700938 } while (list_empty(&dentry->d_subdirs));
939
940 dentry = list_entry(dentry->d_subdirs.next,
941 struct dentry, d_u.d_child);
942 }
943}
944
945/*
946 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100947 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700948 * - the superblock is detached from all mountings and open files, so the
949 * dentry trees will not be rearranged by the VFS
950 * - s_umount is write-locked, so the memory pressure shrinker will ignore
951 * any dentries belonging to this superblock that it comes across
952 * - the filesystem itself is no longer permitted to rearrange the dentries
953 * in this superblock
954 */
955void shrink_dcache_for_umount(struct super_block *sb)
956{
957 struct dentry *dentry;
958
959 if (down_read_trylock(&sb->s_umount))
960 BUG();
961
962 dentry = sb->s_root;
963 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100964 dentry->d_count--;
David Howellsc636ebd2006-10-11 01:22:19 -0700965 shrink_dcache_for_umount_subtree(dentry);
966
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100967 while (!hlist_bl_empty(&sb->s_anon)) {
968 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700969 shrink_dcache_for_umount_subtree(dentry);
970 }
971}
972
973/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700974 * This tries to ascend one level of parenthood, but
975 * we can race with renaming, so we need to re-check
976 * the parenthood after dropping the lock and check
977 * that the sequence number still matches.
978 */
979static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
980{
981 struct dentry *new = old->d_parent;
982
983 rcu_read_lock();
984 spin_unlock(&old->d_lock);
985 spin_lock(&new->d_lock);
986
987 /*
988 * might go back up the wrong parent if we have had a rename
989 * or deletion
990 */
991 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -0400992 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700993 (!locked && read_seqretry(&rename_lock, seq))) {
994 spin_unlock(&new->d_lock);
995 new = NULL;
996 }
997 rcu_read_unlock();
998 return new;
999}
1000
1001
1002/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 * Search for at least 1 mount point in the dentry's subdirs.
1004 * We descend to the next level whenever the d_subdirs
1005 * list is non-empty and continue searching.
1006 */
1007
1008/**
1009 * have_submounts - check for mounts over a dentry
1010 * @parent: dentry to check.
1011 *
1012 * Return true if the parent or its subdirectories contain
1013 * a mount point
1014 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015int have_submounts(struct dentry *parent)
1016{
Nick Piggin949854d2011-01-07 17:49:37 +11001017 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001019 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11001020 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001021
Nick Piggin949854d2011-01-07 17:49:37 +11001022 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001023again:
1024 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 if (d_mountpoint(parent))
1027 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001028 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029repeat:
1030 next = this_parent->d_subdirs.next;
1031resume:
1032 while (next != &this_parent->d_subdirs) {
1033 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001034 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001036
1037 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001039 if (d_mountpoint(dentry)) {
1040 spin_unlock(&dentry->d_lock);
1041 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001043 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001045 spin_unlock(&this_parent->d_lock);
1046 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001048 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 goto repeat;
1050 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001051 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 }
1053 /*
1054 * All done at this level ... ascend and resume the search.
1055 */
1056 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001057 struct dentry *child = this_parent;
1058 this_parent = try_to_ascend(this_parent, locked, seq);
1059 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001060 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001061 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 goto resume;
1063 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001064 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001065 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001066 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001067 if (locked)
1068 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 return 0; /* No mount points found in tree */
1070positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001071 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001072 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001073 if (locked)
1074 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001076
1077rename_retry:
1078 locked = 1;
1079 write_seqlock(&rename_lock);
1080 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001082EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083
1084/*
1085 * Search the dentry child list for the specified parent,
1086 * and move any unused dentries to the end of the unused
1087 * list for prune_dcache(). We descend to the next level
1088 * whenever the d_subdirs list is non-empty and continue
1089 * searching.
1090 *
1091 * It returns zero iff there are no unused children,
1092 * otherwise it returns the number of children moved to
1093 * the end of the unused list. This may not be the total
1094 * number of unused children, because select_parent can
1095 * drop the lock and return early due to latency
1096 * constraints.
1097 */
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001098static int select_parent(struct dentry *parent, struct list_head *dispose)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099{
Nick Piggin949854d2011-01-07 17:49:37 +11001100 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001102 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001104 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105
Nick Piggin949854d2011-01-07 17:49:37 +11001106 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001107again:
1108 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001109 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110repeat:
1111 next = this_parent->d_subdirs.next;
1112resume:
1113 while (next != &this_parent->d_subdirs) {
1114 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001115 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 next = tmp->next;
1117
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001118 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001119
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001120 /*
1121 * move only zero ref count dentries to the dispose list.
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001122 *
1123 * Those which are presently on the shrink list, being processed
1124 * by shrink_dentry_list(), shouldn't be moved. Otherwise the
1125 * loop in shrink_dcache_parent() might not make any progress
1126 * and loop forever.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 */
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001128 if (dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001129 dentry_lru_del(dentry);
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001130 } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
1131 dentry_lru_move_list(dentry, dispose);
1132 dentry->d_flags |= DCACHE_SHRINK_LIST;
1133 found++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135 /*
1136 * We can return to the caller if we have found some (this
1137 * ensures forward progress). We'll be coming back to find
1138 * the rest.
1139 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001140 if (found && need_resched()) {
1141 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 goto out;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001143 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144
1145 /*
1146 * Descend a level if the d_subdirs list is non-empty.
1147 */
1148 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001149 spin_unlock(&this_parent->d_lock);
1150 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001152 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 goto repeat;
1154 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001155
1156 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157 }
1158 /*
1159 * All done at this level ... ascend and resume the search.
1160 */
1161 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001162 struct dentry *child = this_parent;
1163 this_parent = try_to_ascend(this_parent, locked, seq);
1164 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001165 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001166 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167 goto resume;
1168 }
1169out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001170 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001171 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001172 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001173 if (locked)
1174 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 return found;
Nick Piggin58db63d2011-01-07 17:49:39 +11001176
1177rename_retry:
1178 if (found)
1179 return found;
1180 locked = 1;
1181 write_seqlock(&rename_lock);
1182 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183}
1184
1185/**
1186 * shrink_dcache_parent - prune dcache
1187 * @parent: parent of entries to prune
1188 *
1189 * Prune the dcache to remove unused children of the parent dentry.
1190 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191void shrink_dcache_parent(struct dentry * parent)
1192{
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001193 LIST_HEAD(dispose);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 int found;
1195
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001196 while ((found = select_parent(parent, &dispose)) != 0)
1197 shrink_dentry_list(&dispose);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001199EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201/**
Al Viroa4464db2011-07-07 15:03:58 -04001202 * __d_alloc - allocate a dcache entry
1203 * @sb: filesystem it will belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204 * @name: qstr of the name
1205 *
1206 * Allocates a dentry. It returns %NULL if there is insufficient memory
1207 * available. On a success the dentry is returned. The name passed in is
1208 * copied and the copy passed in may be reused after this call.
1209 */
1210
Al Viroa4464db2011-07-07 15:03:58 -04001211struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212{
1213 struct dentry *dentry;
1214 char *dname;
1215
Mel Gormane12ba742007-10-16 01:25:52 -07001216 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 if (!dentry)
1218 return NULL;
1219
1220 if (name->len > DNAME_INLINE_LEN-1) {
1221 dname = kmalloc(name->len + 1, GFP_KERNEL);
1222 if (!dname) {
1223 kmem_cache_free(dentry_cache, dentry);
1224 return NULL;
1225 }
1226 } else {
1227 dname = dentry->d_iname;
1228 }
1229 dentry->d_name.name = dname;
1230
1231 dentry->d_name.len = name->len;
1232 dentry->d_name.hash = name->hash;
1233 memcpy(dname, name->name, name->len);
1234 dname[name->len] = 0;
1235
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001236 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001237 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001239 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240 dentry->d_inode = NULL;
Al Viroa4464db2011-07-07 15:03:58 -04001241 dentry->d_parent = dentry;
1242 dentry->d_sb = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243 dentry->d_op = NULL;
1244 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001245 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246 INIT_LIST_HEAD(&dentry->d_lru);
1247 INIT_LIST_HEAD(&dentry->d_subdirs);
1248 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001249 INIT_LIST_HEAD(&dentry->d_u.d_child);
Al Viroa4464db2011-07-07 15:03:58 -04001250 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251
Nick Piggin3e880fb2011-01-07 17:49:19 +11001252 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001253
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 return dentry;
1255}
Al Viroa4464db2011-07-07 15:03:58 -04001256
1257/**
1258 * d_alloc - allocate a dcache entry
1259 * @parent: parent of entry to allocate
1260 * @name: qstr of the name
1261 *
1262 * Allocates a dentry. It returns %NULL if there is insufficient memory
1263 * available. On a success the dentry is returned. The name passed in is
1264 * copied and the copy passed in may be reused after this call.
1265 */
1266struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1267{
1268 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1269 if (!dentry)
1270 return NULL;
1271
1272 spin_lock(&parent->d_lock);
1273 /*
1274 * don't need child lock because it is not subject
1275 * to concurrency here
1276 */
1277 __dget_dlock(parent);
1278 dentry->d_parent = parent;
1279 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
1280 spin_unlock(&parent->d_lock);
1281
1282 return dentry;
1283}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001284EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
Nick Piggin4b936882011-01-07 17:50:07 +11001286struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1287{
Al Viroa4464db2011-07-07 15:03:58 -04001288 struct dentry *dentry = __d_alloc(sb, name);
1289 if (dentry)
Nick Piggin4b936882011-01-07 17:50:07 +11001290 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin4b936882011-01-07 17:50:07 +11001291 return dentry;
1292}
1293EXPORT_SYMBOL(d_alloc_pseudo);
1294
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1296{
1297 struct qstr q;
1298
1299 q.name = name;
1300 q.len = strlen(name);
1301 q.hash = full_name_hash(q.name, q.len);
1302 return d_alloc(parent, &q);
1303}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001304EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305
Nick Pigginfb045ad2011-01-07 17:49:55 +11001306void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1307{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001308 WARN_ON_ONCE(dentry->d_op);
1309 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001310 DCACHE_OP_COMPARE |
1311 DCACHE_OP_REVALIDATE |
1312 DCACHE_OP_DELETE ));
1313 dentry->d_op = op;
1314 if (!op)
1315 return;
1316 if (op->d_hash)
1317 dentry->d_flags |= DCACHE_OP_HASH;
1318 if (op->d_compare)
1319 dentry->d_flags |= DCACHE_OP_COMPARE;
1320 if (op->d_revalidate)
1321 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1322 if (op->d_delete)
1323 dentry->d_flags |= DCACHE_OP_DELETE;
Sage Weilf0023bc2011-10-28 10:02:42 -07001324 if (op->d_prune)
1325 dentry->d_flags |= DCACHE_OP_PRUNE;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001326
1327}
1328EXPORT_SYMBOL(d_set_d_op);
1329
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001330static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1331{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001332 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001333 if (inode) {
1334 if (unlikely(IS_AUTOMOUNT(inode)))
1335 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001336 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001337 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001338 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001339 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001340 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001341 fsnotify_d_instantiate(dentry, inode);
1342}
1343
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344/**
1345 * d_instantiate - fill in inode information for a dentry
1346 * @entry: dentry to complete
1347 * @inode: inode to attach to this dentry
1348 *
1349 * Fill in inode information in the entry.
1350 *
1351 * This turns negative dentries into productive full members
1352 * of society.
1353 *
1354 * NOTE! This assumes that the inode count has been incremented
1355 * (or otherwise set) by the caller to indicate that it is now
1356 * in use by the dcache.
1357 */
1358
1359void d_instantiate(struct dentry *entry, struct inode * inode)
1360{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001361 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001362 if (inode)
1363 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001364 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001365 if (inode)
1366 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 security_d_instantiate(entry, inode);
1368}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001369EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370
1371/**
1372 * d_instantiate_unique - instantiate a non-aliased dentry
1373 * @entry: dentry to instantiate
1374 * @inode: inode to attach to this dentry
1375 *
1376 * Fill in inode information in the entry. On success, it returns NULL.
1377 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001378 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 *
1380 * Note that in order to avoid conflicts with rename() etc, the caller
1381 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001382 *
1383 * This also assumes that the inode count has been incremented
1384 * (or otherwise set) by the caller to indicate that it is now
1385 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 */
David Howells770bfad2006-08-22 20:06:07 -04001387static struct dentry *__d_instantiate_unique(struct dentry *entry,
1388 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389{
1390 struct dentry *alias;
1391 int len = entry->d_name.len;
1392 const char *name = entry->d_name.name;
1393 unsigned int hash = entry->d_name.hash;
1394
David Howells770bfad2006-08-22 20:06:07 -04001395 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001396 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001397 return NULL;
1398 }
1399
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1401 struct qstr *qstr = &alias->d_name;
1402
Nick Piggin9abca362011-01-07 17:49:36 +11001403 /*
1404 * Don't need alias->d_lock here, because aliases with
1405 * d_parent == entry->d_parent are not subject to name or
1406 * parent changes, because the parent inode i_mutex is held.
1407 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 if (qstr->hash != hash)
1409 continue;
1410 if (alias->d_parent != entry->d_parent)
1411 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001412 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001414 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 return alias;
1416 }
David Howells770bfad2006-08-22 20:06:07 -04001417
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001418 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 return NULL;
1420}
David Howells770bfad2006-08-22 20:06:07 -04001421
1422struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1423{
1424 struct dentry *result;
1425
1426 BUG_ON(!list_empty(&entry->d_alias));
1427
Nick Piggin873feea2011-01-07 17:50:06 +11001428 if (inode)
1429 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001430 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001431 if (inode)
1432 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001433
1434 if (!result) {
1435 security_d_instantiate(entry, inode);
1436 return NULL;
1437 }
1438
1439 BUG_ON(!d_unhashed(result));
1440 iput(inode);
1441 return result;
1442}
1443
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444EXPORT_SYMBOL(d_instantiate_unique);
1445
1446/**
1447 * d_alloc_root - allocate root dentry
1448 * @root_inode: inode to allocate the root for
1449 *
1450 * Allocate a root ("/") dentry for the inode given. The inode is
1451 * instantiated and returned. %NULL is returned if there is insufficient
1452 * memory or the inode passed is %NULL.
1453 */
1454
1455struct dentry * d_alloc_root(struct inode * root_inode)
1456{
1457 struct dentry *res = NULL;
1458
1459 if (root_inode) {
1460 static const struct qstr name = { .name = "/", .len = 1 };
1461
Al Viroa4464db2011-07-07 15:03:58 -04001462 res = __d_alloc(root_inode->i_sb, &name);
1463 if (res)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 d_instantiate(res, root_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 }
1466 return res;
1467}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001468EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469
Al Viroadc0e912012-01-08 16:49:21 -05001470struct dentry *d_make_root(struct inode *root_inode)
1471{
1472 struct dentry *res = NULL;
1473
1474 if (root_inode) {
1475 static const struct qstr name = { .name = "/", .len = 1 };
1476
1477 res = __d_alloc(root_inode->i_sb, &name);
1478 if (res)
1479 d_instantiate(res, root_inode);
1480 else
1481 iput(root_inode);
1482 }
1483 return res;
1484}
1485EXPORT_SYMBOL(d_make_root);
1486
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001487static struct dentry * __d_find_any_alias(struct inode *inode)
1488{
1489 struct dentry *alias;
1490
1491 if (list_empty(&inode->i_dentry))
1492 return NULL;
1493 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1494 __dget(alias);
1495 return alias;
1496}
1497
Sage Weil46f72b32012-01-10 09:04:37 -08001498/**
1499 * d_find_any_alias - find any alias for a given inode
1500 * @inode: inode to find an alias for
1501 *
1502 * If any aliases exist for the given inode, take and return a
1503 * reference for one of them. If no aliases exist, return %NULL.
1504 */
1505struct dentry *d_find_any_alias(struct inode *inode)
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001506{
1507 struct dentry *de;
1508
1509 spin_lock(&inode->i_lock);
1510 de = __d_find_any_alias(inode);
1511 spin_unlock(&inode->i_lock);
1512 return de;
1513}
Sage Weil46f72b32012-01-10 09:04:37 -08001514EXPORT_SYMBOL(d_find_any_alias);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001515
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001517 * d_obtain_alias - find or allocate a dentry for a given inode
1518 * @inode: inode to allocate the dentry for
1519 *
1520 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1521 * similar open by handle operations. The returned dentry may be anonymous,
1522 * or may have a full name (if the inode was already in the cache).
1523 *
1524 * When called on a directory inode, we must ensure that the inode only ever
1525 * has one dentry. If a dentry is found, that is returned instead of
1526 * allocating a new one.
1527 *
1528 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001529 * to the dentry. In case of an error the reference on the inode is released.
1530 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1531 * be passed in and will be the error will be propagate to the return value,
1532 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001533 */
1534struct dentry *d_obtain_alias(struct inode *inode)
1535{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001536 static const struct qstr anonstring = { .name = "" };
1537 struct dentry *tmp;
1538 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001539
1540 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001541 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001542 if (IS_ERR(inode))
1543 return ERR_CAST(inode);
1544
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001545 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001546 if (res)
1547 goto out_iput;
1548
Al Viroa4464db2011-07-07 15:03:58 -04001549 tmp = __d_alloc(inode->i_sb, &anonstring);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001550 if (!tmp) {
1551 res = ERR_PTR(-ENOMEM);
1552 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001553 }
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001554
Nick Piggin873feea2011-01-07 17:50:06 +11001555 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001556 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001557 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001558 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001559 dput(tmp);
1560 goto out_iput;
1561 }
1562
1563 /* attach a disconnected dentry */
1564 spin_lock(&tmp->d_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001565 tmp->d_inode = inode;
1566 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001567 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001568 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001569 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001570 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001571 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001572 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001573 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001574
Christoph Hellwig9308a612008-08-11 15:49:12 +02001575 return tmp;
1576
1577 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001578 if (res && !IS_ERR(res))
1579 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001580 iput(inode);
1581 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001582}
Benny Halevyadc48722009-02-27 14:02:59 -08001583EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584
1585/**
1586 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1587 * @inode: the inode which may have a disconnected dentry
1588 * @dentry: a negative dentry which we want to point to the inode.
1589 *
1590 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1591 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1592 * and return it, else simply d_add the inode to the dentry and return NULL.
1593 *
1594 * This is needed in the lookup routine of any filesystem that is exportable
1595 * (via knfsd) so that we can build dcache paths to directories effectively.
1596 *
1597 * If a dentry was found and moved, then it is returned. Otherwise NULL
1598 * is returned. This matches the expected return value of ->lookup.
1599 *
1600 */
1601struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1602{
1603 struct dentry *new = NULL;
1604
Al Viroa9049372011-07-08 21:20:11 -04001605 if (IS_ERR(inode))
1606 return ERR_CAST(inode);
1607
NeilBrown21c0d8f2006-10-04 02:16:16 -07001608 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001609 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610 new = __d_find_alias(inode, 1);
1611 if (new) {
1612 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001613 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615 d_move(new, dentry);
1616 iput(inode);
1617 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001618 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001619 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001620 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621 security_d_instantiate(dentry, inode);
1622 d_rehash(dentry);
1623 }
1624 } else
1625 d_add(dentry, inode);
1626 return new;
1627}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001628EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629
Barry Naujok94035402008-05-21 16:50:46 +10001630/**
1631 * d_add_ci - lookup or allocate new dentry with case-exact name
1632 * @inode: the inode case-insensitive lookup has found
1633 * @dentry: the negative dentry that was passed to the parent's lookup func
1634 * @name: the case-exact name to be associated with the returned dentry
1635 *
1636 * This is to avoid filling the dcache with case-insensitive names to the
1637 * same inode, only the actual correct case is stored in the dcache for
1638 * case-insensitive filesystems.
1639 *
1640 * For a case-insensitive lookup match and if the the case-exact dentry
1641 * already exists in in the dcache, use it and return it.
1642 *
1643 * If no entry exists with the exact case name, allocate new dentry with
1644 * the exact case, and return the spliced entry.
1645 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001646struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001647 struct qstr *name)
1648{
1649 int error;
1650 struct dentry *found;
1651 struct dentry *new;
1652
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001653 /*
1654 * First check if a dentry matching the name already exists,
1655 * if not go ahead and create it now.
1656 */
Barry Naujok94035402008-05-21 16:50:46 +10001657 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001658 if (!found) {
1659 new = d_alloc(dentry->d_parent, name);
1660 if (!new) {
1661 error = -ENOMEM;
1662 goto err_out;
1663 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001664
Barry Naujok94035402008-05-21 16:50:46 +10001665 found = d_splice_alias(inode, new);
1666 if (found) {
1667 dput(new);
1668 return found;
1669 }
1670 return new;
1671 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001672
1673 /*
1674 * If a matching dentry exists, and it's not negative use it.
1675 *
1676 * Decrement the reference count to balance the iget() done
1677 * earlier on.
1678 */
Barry Naujok94035402008-05-21 16:50:46 +10001679 if (found->d_inode) {
1680 if (unlikely(found->d_inode != inode)) {
1681 /* This can't happen because bad inodes are unhashed. */
1682 BUG_ON(!is_bad_inode(inode));
1683 BUG_ON(!is_bad_inode(found->d_inode));
1684 }
Barry Naujok94035402008-05-21 16:50:46 +10001685 iput(inode);
1686 return found;
1687 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001688
Barry Naujok94035402008-05-21 16:50:46 +10001689 /*
Josef Bacik44396f42011-05-31 11:58:49 -04001690 * We are going to instantiate this dentry, unhash it and clear the
1691 * lookup flag so we can do that.
1692 */
1693 if (unlikely(d_need_lookup(found)))
1694 d_clear_need_lookup(found);
1695
1696 /*
Barry Naujok94035402008-05-21 16:50:46 +10001697 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001698 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001699 */
Al Viro4513d892011-07-17 10:52:14 -04001700 new = d_splice_alias(inode, found);
1701 if (new) {
1702 dput(found);
1703 found = new;
Barry Naujok94035402008-05-21 16:50:46 +10001704 }
Al Viro4513d892011-07-17 10:52:14 -04001705 return found;
Barry Naujok94035402008-05-21 16:50:46 +10001706
1707err_out:
1708 iput(inode);
1709 return ERR_PTR(error);
1710}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001711EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
1713/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001714 * __d_lookup_rcu - search for a dentry (racy, store-free)
1715 * @parent: parent dentry
1716 * @name: qstr of name we wish to find
1717 * @seq: returns d_seq value at the point where the dentry was found
1718 * @inode: returns dentry->d_inode when the inode was found valid.
1719 * Returns: dentry, or NULL
1720 *
1721 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1722 * resolution (store-free path walking) design described in
1723 * Documentation/filesystems/path-lookup.txt.
1724 *
1725 * This is not to be used outside core vfs.
1726 *
1727 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1728 * held, and rcu_read_lock held. The returned dentry must not be stored into
1729 * without taking d_lock and checking d_seq sequence count against @seq
1730 * returned here.
1731 *
1732 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1733 * function.
1734 *
1735 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1736 * the returned dentry, so long as its parent's seqlock is checked after the
1737 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1738 * is formed, giving integrity down the path walk.
1739 */
Linus Torvalds8966be92012-03-02 14:23:30 -08001740struct dentry *__d_lookup_rcu(const struct dentry *parent,
1741 const struct qstr *name,
1742 unsigned *seqp, struct inode **inode)
Nick Piggin31e6b012011-01-07 17:49:52 +11001743{
1744 unsigned int len = name->len;
1745 unsigned int hash = name->hash;
1746 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001747 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001748 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001749 struct dentry *dentry;
1750
1751 /*
1752 * Note: There is significant duplication with __d_lookup_rcu which is
1753 * required to prevent single threaded performance regressions
1754 * especially on architectures where smp_rmb (in seqcounts) are costly.
1755 * Keep the two functions in sync.
1756 */
1757
1758 /*
1759 * The hash list is protected using RCU.
1760 *
1761 * Carefully use d_seq when comparing a candidate dentry, to avoid
1762 * races with d_move().
1763 *
1764 * It is possible that concurrent renames can mess up our list
1765 * walk here and result in missing our dentry, resulting in the
1766 * false-negative result. d_lookup() protects against concurrent
1767 * renames using rename_lock seqlock.
1768 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001769 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001770 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001771 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Linus Torvalds8966be92012-03-02 14:23:30 -08001772 unsigned seq;
Nick Piggin31e6b012011-01-07 17:49:52 +11001773 struct inode *i;
1774 const char *tname;
1775 int tlen;
1776
1777 if (dentry->d_name.hash != hash)
1778 continue;
1779
1780seqretry:
Linus Torvalds8966be92012-03-02 14:23:30 -08001781 seq = read_seqcount_begin(&dentry->d_seq);
Nick Piggin31e6b012011-01-07 17:49:52 +11001782 if (dentry->d_parent != parent)
1783 continue;
1784 if (d_unhashed(dentry))
1785 continue;
1786 tlen = dentry->d_name.len;
1787 tname = dentry->d_name.name;
1788 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001789 prefetch(tname);
Nick Piggin31e6b012011-01-07 17:49:52 +11001790 /*
1791 * This seqcount check is required to ensure name and
1792 * len are loaded atomically, so as not to walk off the
1793 * edge of memory when walking. If we could load this
1794 * atomically some other way, we could drop this check.
1795 */
Linus Torvalds8966be92012-03-02 14:23:30 -08001796 if (read_seqcount_retry(&dentry->d_seq, seq))
Nick Piggin31e6b012011-01-07 17:49:52 +11001797 goto seqretry;
Linus Torvalds830c0f02011-08-06 22:41:50 -07001798 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001799 if (parent->d_op->d_compare(parent, *inode,
1800 dentry, i,
1801 tlen, tname, name))
1802 continue;
1803 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001804 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001805 continue;
1806 }
1807 /*
1808 * No extra seqcount check is required after the name
1809 * compare. The caller must perform a seqcount check in
1810 * order to do anything useful with the returned dentry
1811 * anyway.
1812 */
Linus Torvalds8966be92012-03-02 14:23:30 -08001813 *seqp = seq;
Nick Piggin31e6b012011-01-07 17:49:52 +11001814 *inode = i;
1815 return dentry;
1816 }
1817 return NULL;
1818}
1819
1820/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 * d_lookup - search for a dentry
1822 * @parent: parent dentry
1823 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001824 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001826 * d_lookup searches the children of the parent dentry for the name in
1827 * question. If the dentry is found its reference count is incremented and the
1828 * dentry is returned. The caller must use dput to free the entry when it has
1829 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001831struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832{
Nick Piggin31e6b012011-01-07 17:49:52 +11001833 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001834 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001835
1836 do {
1837 seq = read_seqbegin(&rename_lock);
1838 dentry = __d_lookup(parent, name);
1839 if (dentry)
1840 break;
1841 } while (read_seqretry(&rename_lock, seq));
1842 return dentry;
1843}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001844EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001845
Nick Piggin31e6b012011-01-07 17:49:52 +11001846/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001847 * __d_lookup - search for a dentry (racy)
1848 * @parent: parent dentry
1849 * @name: qstr of name we wish to find
1850 * Returns: dentry, or NULL
1851 *
1852 * __d_lookup is like d_lookup, however it may (rarely) return a
1853 * false-negative result due to unrelated rename activity.
1854 *
1855 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1856 * however it must be used carefully, eg. with a following d_lookup in
1857 * the case of failure.
1858 *
1859 * __d_lookup callers must be commented.
1860 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001861struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862{
1863 unsigned int len = name->len;
1864 unsigned int hash = name->hash;
1865 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001866 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001867 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001868 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001869 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870
Nick Pigginb04f7842010-08-18 04:37:34 +10001871 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001872 * Note: There is significant duplication with __d_lookup_rcu which is
1873 * required to prevent single threaded performance regressions
1874 * especially on architectures where smp_rmb (in seqcounts) are costly.
1875 * Keep the two functions in sync.
1876 */
1877
1878 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001879 * The hash list is protected using RCU.
1880 *
1881 * Take d_lock when comparing a candidate dentry, to avoid races
1882 * with d_move().
1883 *
1884 * It is possible that concurrent renames can mess up our list
1885 * walk here and result in missing our dentry, resulting in the
1886 * false-negative result. d_lookup() protects against concurrent
1887 * renames using rename_lock seqlock.
1888 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001889 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001890 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891 rcu_read_lock();
1892
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001893 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001894 const char *tname;
1895 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896
Linus Torvalds1da177e2005-04-16 15:20:36 -07001897 if (dentry->d_name.hash != hash)
1898 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899
1900 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 if (dentry->d_parent != parent)
1902 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001903 if (d_unhashed(dentry))
1904 goto next;
1905
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906 /*
1907 * It is safe to compare names since d_move() cannot
1908 * change the qstr (protected by d_lock).
1909 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001910 tlen = dentry->d_name.len;
1911 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001912 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001913 if (parent->d_op->d_compare(parent, parent->d_inode,
1914 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001915 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916 goto next;
1917 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001918 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 goto next;
1920 }
1921
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001922 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001923 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 spin_unlock(&dentry->d_lock);
1925 break;
1926next:
1927 spin_unlock(&dentry->d_lock);
1928 }
1929 rcu_read_unlock();
1930
1931 return found;
1932}
1933
1934/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001935 * d_hash_and_lookup - hash the qstr then search for a dentry
1936 * @dir: Directory to search in
1937 * @name: qstr of name we wish to find
1938 *
1939 * On hash failure or on lookup failure NULL is returned.
1940 */
1941struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1942{
1943 struct dentry *dentry = NULL;
1944
1945 /*
1946 * Check for a fs-specific hash function. Note that we must
1947 * calculate the standard hash first, as the d_op->d_hash()
1948 * routine may choose to leave the hash value unchanged.
1949 */
1950 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001951 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001952 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001953 goto out;
1954 }
1955 dentry = d_lookup(dir, name);
1956out:
1957 return dentry;
1958}
1959
1960/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001961 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001962 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001963 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964 *
1965 * An insecure source has sent us a dentry, here we verify it and dget() it.
1966 * This is used by ncpfs in its readdir implementation.
1967 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001968 *
1969 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001971int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001972{
Nick Piggin786a5e12011-01-07 17:49:16 +11001973 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001974
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001975 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001976 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
1977 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001978 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11001979 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001980 spin_unlock(&dentry->d_lock);
1981 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 return 1;
1983 }
1984 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001985 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001986
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 return 0;
1988}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001989EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990
1991/*
1992 * When a file is deleted, we have two options:
1993 * - turn this dentry into a negative dentry
1994 * - unhash this dentry and free it.
1995 *
1996 * Usually, we want to just turn this into
1997 * a negative dentry, but if anybody else is
1998 * currently using the dentry or the inode
1999 * we can't do that and we fall back on removing
2000 * it from the hash queues and waiting for
2001 * it to be deleted later when it has no users
2002 */
2003
2004/**
2005 * d_delete - delete a dentry
2006 * @dentry: The dentry to delete
2007 *
2008 * Turn the dentry into a negative dentry if possible, otherwise
2009 * remove it from the hash queues so it can be deleted later
2010 */
2011
2012void d_delete(struct dentry * dentry)
2013{
Nick Piggin873feea2011-01-07 17:50:06 +11002014 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04002015 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 /*
2017 * Are we the only user?
2018 */
Nick Piggin357f8e62011-01-07 17:49:42 +11002019again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002021 inode = dentry->d_inode;
2022 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002023 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11002024 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11002025 spin_unlock(&dentry->d_lock);
2026 cpu_relax();
2027 goto again;
2028 }
Al Viro13e3c5e2010-05-21 16:11:04 -04002029 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11002030 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04002031 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 return;
2033 }
2034
2035 if (!d_unhashed(dentry))
2036 __d_drop(dentry);
2037
2038 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04002039
2040 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002041}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002042EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002044static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002046 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002047 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07002048 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002049 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002050 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051}
2052
David Howells770bfad2006-08-22 20:06:07 -04002053static void _d_rehash(struct dentry * entry)
2054{
2055 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2056}
2057
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058/**
2059 * d_rehash - add an entry back to the hash
2060 * @entry: dentry to add to the hash
2061 *
2062 * Adds a dentry to the hash according to its name.
2063 */
2064
2065void d_rehash(struct dentry * entry)
2066{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002068 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002069 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002071EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002072
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002073/**
2074 * dentry_update_name_case - update case insensitive dentry with a new name
2075 * @dentry: dentry to be updated
2076 * @name: new name
2077 *
2078 * Update a case insensitive dentry with new case of name.
2079 *
2080 * dentry must have been returned by d_lookup with name @name. Old and new
2081 * name lengths must match (ie. no d_compare which allows mismatched name
2082 * lengths).
2083 *
2084 * Parent inode i_mutex must be held over d_lookup and into this call (to
2085 * keep renames and concurrent inserts, and readdir(2) away).
2086 */
2087void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2088{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002089 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002090 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2091
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002092 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002093 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002094 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002095 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002096 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002097}
2098EXPORT_SYMBOL(dentry_update_name_case);
2099
Linus Torvalds1da177e2005-04-16 15:20:36 -07002100static void switch_names(struct dentry *dentry, struct dentry *target)
2101{
2102 if (dname_external(target)) {
2103 if (dname_external(dentry)) {
2104 /*
2105 * Both external: swap the pointers
2106 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002107 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108 } else {
2109 /*
2110 * dentry:internal, target:external. Steal target's
2111 * storage and make target internal.
2112 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002113 memcpy(target->d_iname, dentry->d_name.name,
2114 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 dentry->d_name.name = target->d_name.name;
2116 target->d_name.name = target->d_iname;
2117 }
2118 } else {
2119 if (dname_external(dentry)) {
2120 /*
2121 * dentry:external, target:internal. Give dentry's
2122 * storage to target and make dentry internal
2123 */
2124 memcpy(dentry->d_iname, target->d_name.name,
2125 target->d_name.len + 1);
2126 target->d_name.name = dentry->d_name.name;
2127 dentry->d_name.name = dentry->d_iname;
2128 } else {
2129 /*
2130 * Both are internal. Just copy target to dentry
2131 */
2132 memcpy(dentry->d_iname, target->d_name.name,
2133 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002134 dentry->d_name.len = target->d_name.len;
2135 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002136 }
2137 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002138 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139}
2140
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002141static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2142{
2143 /*
2144 * XXXX: do we really need to take target->d_lock?
2145 */
2146 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2147 spin_lock(&target->d_parent->d_lock);
2148 else {
2149 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2150 spin_lock(&dentry->d_parent->d_lock);
2151 spin_lock_nested(&target->d_parent->d_lock,
2152 DENTRY_D_LOCK_NESTED);
2153 } else {
2154 spin_lock(&target->d_parent->d_lock);
2155 spin_lock_nested(&dentry->d_parent->d_lock,
2156 DENTRY_D_LOCK_NESTED);
2157 }
2158 }
2159 if (target < dentry) {
2160 spin_lock_nested(&target->d_lock, 2);
2161 spin_lock_nested(&dentry->d_lock, 3);
2162 } else {
2163 spin_lock_nested(&dentry->d_lock, 2);
2164 spin_lock_nested(&target->d_lock, 3);
2165 }
2166}
2167
2168static void dentry_unlock_parents_for_move(struct dentry *dentry,
2169 struct dentry *target)
2170{
2171 if (target->d_parent != dentry->d_parent)
2172 spin_unlock(&dentry->d_parent->d_lock);
2173 if (target->d_parent != target)
2174 spin_unlock(&target->d_parent->d_lock);
2175}
2176
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002178 * When switching names, the actual string doesn't strictly have to
2179 * be preserved in the target - because we're dropping the target
2180 * anyway. As such, we can just do a simple memcpy() to copy over
2181 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002183 * Note that we have to be a lot more careful about getting the hash
2184 * switched - we have to switch the hash value properly even if it
2185 * then no longer matches the actual (corrupted) string of the target.
2186 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002187 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002188/*
Al Viro18367502011-07-12 21:42:24 -04002189 * __d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002190 * @dentry: entry to move
2191 * @target: new dentry
2192 *
2193 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002194 * dcache entries should not be moved in this way. Caller must hold
2195 * rename_lock, the i_mutex of the source and target directories,
2196 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197 */
Al Viro18367502011-07-12 21:42:24 -04002198static void __d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200 if (!dentry->d_inode)
2201 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2202
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002203 BUG_ON(d_ancestor(dentry, target));
2204 BUG_ON(d_ancestor(target, dentry));
2205
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002206 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207
Nick Piggin31e6b012011-01-07 17:49:52 +11002208 write_seqcount_begin(&dentry->d_seq);
2209 write_seqcount_begin(&target->d_seq);
2210
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002211 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2212
2213 /*
2214 * Move the dentry to the target hash queue. Don't bother checking
2215 * for the same hash queue because of how unlikely it is.
2216 */
2217 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002218 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219
2220 /* Unhash the target: dput() will then get rid of it */
2221 __d_drop(target);
2222
Eric Dumazet5160ee62006-01-08 01:03:32 -08002223 list_del(&dentry->d_u.d_child);
2224 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002225
2226 /* Switch the names.. */
2227 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002228 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229
2230 /* ... and switch the parents */
2231 if (IS_ROOT(dentry)) {
2232 dentry->d_parent = target->d_parent;
2233 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002234 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002236 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237
2238 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002239 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002240 }
2241
Eric Dumazet5160ee62006-01-08 01:03:32 -08002242 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002243
Nick Piggin31e6b012011-01-07 17:49:52 +11002244 write_seqcount_end(&target->d_seq);
2245 write_seqcount_end(&dentry->d_seq);
2246
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002247 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002249 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250 spin_unlock(&dentry->d_lock);
Al Viro18367502011-07-12 21:42:24 -04002251}
2252
2253/*
2254 * d_move - move a dentry
2255 * @dentry: entry to move
2256 * @target: new dentry
2257 *
2258 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002259 * dcache entries should not be moved in this way. See the locking
2260 * requirements for __d_move.
Al Viro18367502011-07-12 21:42:24 -04002261 */
2262void d_move(struct dentry *dentry, struct dentry *target)
2263{
2264 write_seqlock(&rename_lock);
2265 __d_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002267}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002268EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002270/**
2271 * d_ancestor - search for an ancestor
2272 * @p1: ancestor dentry
2273 * @p2: child dentry
2274 *
2275 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2276 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002277 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002278struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002279{
2280 struct dentry *p;
2281
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002282 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002283 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002284 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002285 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002286 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002287}
2288
2289/*
2290 * This helper attempts to cope with remotely renamed directories
2291 *
2292 * It assumes that the caller is already holding
Al Viro18367502011-07-12 21:42:24 -04002293 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002294 *
2295 * Note: If ever the locking in lock_rename() changes, then please
2296 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002297 */
Nick Piggin873feea2011-01-07 17:50:06 +11002298static struct dentry *__d_unalias(struct inode *inode,
2299 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002300{
2301 struct mutex *m1 = NULL, *m2 = NULL;
2302 struct dentry *ret;
2303
2304 /* If alias and dentry share a parent, then no extra locks required */
2305 if (alias->d_parent == dentry->d_parent)
2306 goto out_unalias;
2307
Trond Myklebust9eaef272006-10-21 10:24:20 -07002308 /* See lock_rename() */
2309 ret = ERR_PTR(-EBUSY);
2310 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2311 goto out_err;
2312 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2313 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2314 goto out_err;
2315 m2 = &alias->d_parent->d_inode->i_mutex;
2316out_unalias:
Al Viro18367502011-07-12 21:42:24 -04002317 __d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002318 ret = alias;
2319out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002320 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002321 if (m2)
2322 mutex_unlock(m2);
2323 if (m1)
2324 mutex_unlock(m1);
2325 return ret;
2326}
2327
2328/*
David Howells770bfad2006-08-22 20:06:07 -04002329 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2330 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002331 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002332 */
2333static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2334{
2335 struct dentry *dparent, *aparent;
2336
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002337 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002338
Nick Piggin31e6b012011-01-07 17:49:52 +11002339 write_seqcount_begin(&dentry->d_seq);
2340 write_seqcount_begin(&anon->d_seq);
2341
David Howells770bfad2006-08-22 20:06:07 -04002342 dparent = dentry->d_parent;
2343 aparent = anon->d_parent;
2344
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002345 switch_names(dentry, anon);
2346 swap(dentry->d_name.hash, anon->d_name.hash);
2347
David Howells770bfad2006-08-22 20:06:07 -04002348 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2349 list_del(&dentry->d_u.d_child);
2350 if (!IS_ROOT(dentry))
2351 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2352 else
2353 INIT_LIST_HEAD(&dentry->d_u.d_child);
2354
2355 anon->d_parent = (dparent == dentry) ? anon : dparent;
2356 list_del(&anon->d_u.d_child);
2357 if (!IS_ROOT(anon))
2358 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2359 else
2360 INIT_LIST_HEAD(&anon->d_u.d_child);
2361
Nick Piggin31e6b012011-01-07 17:49:52 +11002362 write_seqcount_end(&dentry->d_seq);
2363 write_seqcount_end(&anon->d_seq);
2364
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002365 dentry_unlock_parents_for_move(anon, dentry);
2366 spin_unlock(&dentry->d_lock);
2367
2368 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002369 anon->d_flags &= ~DCACHE_DISCONNECTED;
2370}
2371
2372/**
2373 * d_materialise_unique - introduce an inode into the tree
2374 * @dentry: candidate dentry
2375 * @inode: inode to bind to the dentry, to which aliases may be attached
2376 *
2377 * Introduces an dentry into the tree, substituting an extant disconnected
Jeff Laytonc46c8872011-07-26 13:33:16 -04002378 * root directory alias in its place if there is one. Caller must hold the
2379 * i_mutex of the parent directory.
David Howells770bfad2006-08-22 20:06:07 -04002380 */
2381struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2382{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002383 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002384
2385 BUG_ON(!d_unhashed(dentry));
2386
David Howells770bfad2006-08-22 20:06:07 -04002387 if (!inode) {
2388 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002389 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002390 d_rehash(actual);
2391 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002392 }
2393
Nick Piggin873feea2011-01-07 17:50:06 +11002394 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002395
Trond Myklebust9eaef272006-10-21 10:24:20 -07002396 if (S_ISDIR(inode->i_mode)) {
2397 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002398
Trond Myklebust9eaef272006-10-21 10:24:20 -07002399 /* Does an aliased dentry already exist? */
2400 alias = __d_find_alias(inode, 0);
2401 if (alias) {
2402 actual = alias;
Al Viro18367502011-07-12 21:42:24 -04002403 write_seqlock(&rename_lock);
2404
2405 if (d_ancestor(alias, dentry)) {
2406 /* Check for loops */
2407 actual = ERR_PTR(-ELOOP);
2408 } else if (IS_ROOT(alias)) {
2409 /* Is this an anonymous mountpoint that we
2410 * could splice into our tree? */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002411 __d_materialise_dentry(dentry, alias);
Al Viro18367502011-07-12 21:42:24 -04002412 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002413 __d_drop(alias);
2414 goto found;
Al Viro18367502011-07-12 21:42:24 -04002415 } else {
2416 /* Nope, but we must(!) avoid directory
2417 * aliasing */
2418 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002419 }
Al Viro18367502011-07-12 21:42:24 -04002420 write_sequnlock(&rename_lock);
David Howellsdd179942011-08-16 15:31:30 +01002421 if (IS_ERR(actual)) {
2422 if (PTR_ERR(actual) == -ELOOP)
2423 pr_warn_ratelimited(
2424 "VFS: Lookup of '%s' in %s %s"
2425 " would have caused loop\n",
2426 dentry->d_name.name,
2427 inode->i_sb->s_type->name,
2428 inode->i_sb->s_id);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002429 dput(alias);
David Howellsdd179942011-08-16 15:31:30 +01002430 }
Trond Myklebust9eaef272006-10-21 10:24:20 -07002431 goto out_nolock;
2432 }
David Howells770bfad2006-08-22 20:06:07 -04002433 }
2434
2435 /* Add a unique reference */
2436 actual = __d_instantiate_unique(dentry, inode);
2437 if (!actual)
2438 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002439 else
2440 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002441
David Howells770bfad2006-08-22 20:06:07 -04002442 spin_lock(&actual->d_lock);
2443found:
2444 _d_rehash(actual);
2445 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002446 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002447out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002448 if (actual == dentry) {
2449 security_d_instantiate(dentry, inode);
2450 return NULL;
2451 }
2452
2453 iput(inode);
2454 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002455}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002456EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002457
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002458static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002459{
2460 *buflen -= namelen;
2461 if (*buflen < 0)
2462 return -ENAMETOOLONG;
2463 *buffer -= namelen;
2464 memcpy(*buffer, str, namelen);
2465 return 0;
2466}
2467
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002468static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2469{
2470 return prepend(buffer, buflen, name->name, name->len);
2471}
2472
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002474 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002475 * @path: the dentry/vfsmount to report
Al Viro02125a82011-12-05 08:43:34 -05002476 * @root: root vfsmnt/dentry
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002477 * @buffer: pointer to the end of the buffer
2478 * @buflen: pointer to buffer length
2479 *
Nick Piggin949854d2011-01-07 17:49:37 +11002480 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002481 */
Al Viro02125a82011-12-05 08:43:34 -05002482static int prepend_path(const struct path *path,
2483 const struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002484 char **buffer, int *buflen)
2485{
2486 struct dentry *dentry = path->dentry;
2487 struct vfsmount *vfsmnt = path->mnt;
Al Viro0714a532011-11-24 22:19:58 -05002488 struct mount *mnt = real_mount(vfsmnt);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002489 bool slash = false;
2490 int error = 0;
2491
Nick Piggin99b7db72010-08-18 04:37:39 +10002492 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002493 while (dentry != root->dentry || vfsmnt != root->mnt) {
2494 struct dentry * parent;
2495
2496 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2497 /* Global root? */
Al Viro676da582011-11-24 21:47:05 -05002498 if (!mnt_has_parent(mnt))
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002499 goto global_root;
Al Viroa73324d2011-11-24 22:25:07 -05002500 dentry = mnt->mnt_mountpoint;
Al Viro0714a532011-11-24 22:19:58 -05002501 mnt = mnt->mnt_parent;
2502 vfsmnt = &mnt->mnt;
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002503 continue;
2504 }
2505 parent = dentry->d_parent;
2506 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002507 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002508 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002509 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002510 if (!error)
2511 error = prepend(buffer, buflen, "/", 1);
2512 if (error)
2513 break;
2514
2515 slash = true;
2516 dentry = parent;
2517 }
2518
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002519 if (!error && !slash)
2520 error = prepend(buffer, buflen, "/", 1);
2521
Al Viro02125a82011-12-05 08:43:34 -05002522out:
Nick Piggin99b7db72010-08-18 04:37:39 +10002523 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002524 return error;
2525
2526global_root:
2527 /*
2528 * Filesystems needing to implement special "root names"
2529 * should do so with ->d_dname()
2530 */
2531 if (IS_ROOT(dentry) &&
2532 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2533 WARN(1, "Root dentry has weird name <%.*s>\n",
2534 (int) dentry->d_name.len, dentry->d_name.name);
2535 }
Al Viro02125a82011-12-05 08:43:34 -05002536 if (!slash)
2537 error = prepend(buffer, buflen, "/", 1);
2538 if (!error)
Al Viro143c8c92011-11-25 00:46:35 -05002539 error = real_mount(vfsmnt)->mnt_ns ? 1 : 2;
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002540 goto out;
2541}
2542
2543/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002544 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002545 * @path: the dentry/vfsmount to report
Al Viro02125a82011-12-05 08:43:34 -05002546 * @root: root vfsmnt/dentry
Randy Dunlapcd956a12010-08-14 13:05:31 -07002547 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002548 * @buflen: buffer length
2549 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002550 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002551 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002552 * Returns a pointer into the buffer or an error code if the
2553 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002554 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002555 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002556 *
Al Viro02125a82011-12-05 08:43:34 -05002557 * If the path is not reachable from the supplied root, return %NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002558 */
Al Viro02125a82011-12-05 08:43:34 -05002559char *__d_path(const struct path *path,
2560 const struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002561 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002563 char *res = buf + buflen;
2564 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002566 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002567 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002568 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002569 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002570
Al Viro02125a82011-12-05 08:43:34 -05002571 if (error < 0)
2572 return ERR_PTR(error);
2573 if (error > 0)
2574 return NULL;
2575 return res;
2576}
2577
2578char *d_absolute_path(const struct path *path,
2579 char *buf, int buflen)
2580{
2581 struct path root = {};
2582 char *res = buf + buflen;
2583 int error;
2584
2585 prepend(&res, &buflen, "\0", 1);
2586 write_seqlock(&rename_lock);
2587 error = prepend_path(path, &root, &res, &buflen);
2588 write_sequnlock(&rename_lock);
2589
2590 if (error > 1)
2591 error = -EINVAL;
2592 if (error < 0)
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002593 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002594 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595}
2596
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002597/*
2598 * same as __d_path but appends "(deleted)" for unlinked files.
2599 */
Al Viro02125a82011-12-05 08:43:34 -05002600static int path_with_deleted(const struct path *path,
2601 const struct path *root,
2602 char **buf, int *buflen)
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002603{
2604 prepend(buf, buflen, "\0", 1);
2605 if (d_unlinked(path->dentry)) {
2606 int error = prepend(buf, buflen, " (deleted)", 10);
2607 if (error)
2608 return error;
2609 }
2610
2611 return prepend_path(path, root, buf, buflen);
2612}
2613
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002614static int prepend_unreachable(char **buffer, int *buflen)
2615{
2616 return prepend(buffer, buflen, "(unreachable)", 13);
2617}
2618
Jan Bluncka03a8a702008-02-14 19:38:32 -08002619/**
2620 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002621 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002622 * @buf: buffer to return value in
2623 * @buflen: buffer length
2624 *
2625 * Convert a dentry into an ASCII path name. If the entry has been deleted
2626 * the string " (deleted)" is appended. Note that this is ambiguous.
2627 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002628 * Returns a pointer into the buffer or an error code if the path was
2629 * too long. Note: Callers should use the returned pointer, not the passed
2630 * in buffer, to use the name! The implementation often starts at an offset
2631 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002632 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002633 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002634 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002635char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002636{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002637 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002638 struct path root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002639 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002640
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002641 /*
2642 * We have various synthetic filesystems that never get mounted. On
2643 * these filesystems dentries are never used for lookup purposes, and
2644 * thus don't need to be hashed. They also don't need a name until a
2645 * user wants to identify the object in /proc/pid/fd/. The little hack
2646 * below allows us to generate a name for these objects on demand:
2647 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002648 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2649 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002650
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002651 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002652 write_seqlock(&rename_lock);
Al Viro02125a82011-12-05 08:43:34 -05002653 error = path_with_deleted(path, &root, &res, &buflen);
2654 if (error < 0)
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002655 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002656 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002657 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002658 return res;
2659}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002660EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002662/**
2663 * d_path_with_unreachable - return the path of a dentry
2664 * @path: path to report
2665 * @buf: buffer to return value in
2666 * @buflen: buffer length
2667 *
2668 * The difference from d_path() is that this prepends "(unreachable)"
2669 * to paths which are unreachable from the current process' root.
2670 */
2671char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2672{
2673 char *res = buf + buflen;
2674 struct path root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002675 int error;
2676
2677 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2678 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2679
2680 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002681 write_seqlock(&rename_lock);
Al Viro02125a82011-12-05 08:43:34 -05002682 error = path_with_deleted(path, &root, &res, &buflen);
2683 if (error > 0)
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002684 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002685 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002686 path_put(&root);
2687 if (error)
2688 res = ERR_PTR(error);
2689
2690 return res;
2691}
2692
Linus Torvalds1da177e2005-04-16 15:20:36 -07002693/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002694 * Helper function for dentry_operations.d_dname() members
2695 */
2696char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2697 const char *fmt, ...)
2698{
2699 va_list args;
2700 char temp[64];
2701 int sz;
2702
2703 va_start(args, fmt);
2704 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2705 va_end(args);
2706
2707 if (sz > sizeof(temp) || sz > buflen)
2708 return ERR_PTR(-ENAMETOOLONG);
2709
2710 buffer += buflen - sz;
2711 return memcpy(buffer, temp, sz);
2712}
2713
2714/*
Ram Pai6092d042008-03-27 13:06:20 +01002715 * Write full pathname from the root of the filesystem into the buffer.
2716 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002717static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002718{
2719 char *end = buf + buflen;
2720 char *retval;
2721
Ram Pai6092d042008-03-27 13:06:20 +01002722 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002723 if (buflen < 1)
2724 goto Elong;
2725 /* Get '/' right */
2726 retval = end-1;
2727 *retval = '/';
2728
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002729 while (!IS_ROOT(dentry)) {
2730 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002731 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002732
Ram Pai6092d042008-03-27 13:06:20 +01002733 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002734 spin_lock(&dentry->d_lock);
2735 error = prepend_name(&end, &buflen, &dentry->d_name);
2736 spin_unlock(&dentry->d_lock);
2737 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002738 goto Elong;
2739
2740 retval = end;
2741 dentry = parent;
2742 }
Al Viroc1031352010-06-06 22:31:14 -04002743 return retval;
2744Elong:
2745 return ERR_PTR(-ENAMETOOLONG);
2746}
Nick Pigginec2447c2011-01-07 17:49:29 +11002747
2748char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2749{
2750 char *retval;
2751
Nick Piggin949854d2011-01-07 17:49:37 +11002752 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002753 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002754 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002755
2756 return retval;
2757}
2758EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002759
2760char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2761{
2762 char *p = NULL;
2763 char *retval;
2764
Nick Piggin949854d2011-01-07 17:49:37 +11002765 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002766 if (d_unlinked(dentry)) {
2767 p = buf + buflen;
2768 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2769 goto Elong;
2770 buflen++;
2771 }
2772 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002773 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002774 if (!IS_ERR(retval) && p)
2775 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002776 return retval;
2777Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002778 return ERR_PTR(-ENAMETOOLONG);
2779}
2780
2781/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002782 * NOTE! The user-level library version returns a
2783 * character pointer. The kernel system call just
2784 * returns the length of the buffer filled (which
2785 * includes the ending '\0' character), or a negative
2786 * error value. So libc would do something like
2787 *
2788 * char *getcwd(char * buf, size_t size)
2789 * {
2790 * int retval;
2791 *
2792 * retval = sys_getcwd(buf, size);
2793 * if (retval >= 0)
2794 * return buf;
2795 * errno = -retval;
2796 * return NULL;
2797 * }
2798 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002799SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800{
Linus Torvalds552ce542007-02-13 12:08:18 -08002801 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002802 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002803 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002804
2805 if (!page)
2806 return -ENOMEM;
2807
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002808 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809
Linus Torvalds552ce542007-02-13 12:08:18 -08002810 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002811 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002812 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002813 unsigned long len;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002814 char *cwd = page + PAGE_SIZE;
2815 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002816
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002817 prepend(&cwd, &buflen, "\0", 1);
Al Viro02125a82011-12-05 08:43:34 -05002818 error = prepend_path(&pwd, &root, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002819 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002820
Al Viro02125a82011-12-05 08:43:34 -05002821 if (error < 0)
Linus Torvalds552ce542007-02-13 12:08:18 -08002822 goto out;
2823
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002824 /* Unreachable from current root */
Al Viro02125a82011-12-05 08:43:34 -05002825 if (error > 0) {
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002826 error = prepend_unreachable(&cwd, &buflen);
2827 if (error)
2828 goto out;
2829 }
2830
Linus Torvalds552ce542007-02-13 12:08:18 -08002831 error = -ERANGE;
2832 len = PAGE_SIZE + page - cwd;
2833 if (len <= size) {
2834 error = len;
2835 if (copy_to_user(buf, cwd, len))
2836 error = -EFAULT;
2837 }
Nick Piggin949854d2011-01-07 17:49:37 +11002838 } else {
2839 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002840 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002841
2842out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002843 path_put(&pwd);
2844 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845 free_page((unsigned long) page);
2846 return error;
2847}
2848
2849/*
2850 * Test whether new_dentry is a subdirectory of old_dentry.
2851 *
2852 * Trivially implemented using the dcache structure
2853 */
2854
2855/**
2856 * is_subdir - is new dentry a subdirectory of old_dentry
2857 * @new_dentry: new dentry
2858 * @old_dentry: old dentry
2859 *
2860 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2861 * Returns 0 otherwise.
2862 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2863 */
2864
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002865int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002866{
2867 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002868 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002870 if (new_dentry == old_dentry)
2871 return 1;
2872
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002873 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002874 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002875 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002876 /*
2877 * Need rcu_readlock to protect against the d_parent trashing
2878 * due to d_move
2879 */
2880 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002881 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002882 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002883 else
2884 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002885 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002886 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002887
2888 return result;
2889}
2890
2891void d_genocide(struct dentry *root)
2892{
Nick Piggin949854d2011-01-07 17:49:37 +11002893 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002894 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002895 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002896 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002897
Nick Piggin949854d2011-01-07 17:49:37 +11002898 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002899again:
2900 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002901 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002902repeat:
2903 next = this_parent->d_subdirs.next;
2904resume:
2905 while (next != &this_parent->d_subdirs) {
2906 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002907 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002908 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002909
Nick Pigginda502952011-01-07 17:49:33 +11002910 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2911 if (d_unhashed(dentry) || !dentry->d_inode) {
2912 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002913 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002914 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002915 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002916 spin_unlock(&this_parent->d_lock);
2917 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002918 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002919 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920 goto repeat;
2921 }
Nick Piggin949854d2011-01-07 17:49:37 +11002922 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2923 dentry->d_flags |= DCACHE_GENOCIDE;
2924 dentry->d_count--;
2925 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002926 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002927 }
2928 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002929 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002930 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2931 this_parent->d_flags |= DCACHE_GENOCIDE;
2932 this_parent->d_count--;
2933 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002934 this_parent = try_to_ascend(this_parent, locked, seq);
2935 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002936 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002937 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938 goto resume;
2939 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002940 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002941 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002942 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002943 if (locked)
2944 write_sequnlock(&rename_lock);
2945 return;
2946
2947rename_retry:
2948 locked = 1;
2949 write_seqlock(&rename_lock);
2950 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002951}
2952
2953/**
2954 * find_inode_number - check for dentry with name
2955 * @dir: directory to check
2956 * @name: Name to find.
2957 *
2958 * Check whether a dentry already exists for the given name,
2959 * and return the inode number if it has an inode. Otherwise
2960 * 0 is returned.
2961 *
2962 * This routine is used to post-process directory listings for
2963 * filesystems using synthetic inode numbers, and is necessary
2964 * to keep getcwd() working.
2965 */
2966
2967ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2968{
2969 struct dentry * dentry;
2970 ino_t ino = 0;
2971
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002972 dentry = d_hash_and_lookup(dir, name);
2973 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002974 if (dentry->d_inode)
2975 ino = dentry->d_inode->i_ino;
2976 dput(dentry);
2977 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978 return ino;
2979}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002980EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002981
2982static __initdata unsigned long dhash_entries;
2983static int __init set_dhash_entries(char *str)
2984{
2985 if (!str)
2986 return 0;
2987 dhash_entries = simple_strtoul(str, &str, 0);
2988 return 1;
2989}
2990__setup("dhash_entries=", set_dhash_entries);
2991
2992static void __init dcache_init_early(void)
2993{
Dimitri Sivanich074b8512012-02-08 12:39:07 -08002994 unsigned int loop;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002995
2996 /* If hashes are distributed across NUMA nodes, defer
2997 * hash allocation until vmalloc space is available.
2998 */
2999 if (hashdist)
3000 return;
3001
3002 dentry_hashtable =
3003 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003004 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003005 dhash_entries,
3006 13,
3007 HASH_EARLY,
3008 &d_hash_shift,
3009 &d_hash_mask,
3010 0);
3011
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003012 for (loop = 0; loop < (1U << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003013 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003014}
3015
Denis Cheng74bf17c2007-10-16 23:26:30 -07003016static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003017{
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003018 unsigned int loop;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003019
3020 /*
3021 * A constructor could be added for stable state like the lists,
3022 * but it is probably not worth it because of the cache nature
3023 * of the dcache.
3024 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07003025 dentry_cache = KMEM_CACHE(dentry,
3026 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003027
3028 /* Hash may have been set up in dcache_init_early */
3029 if (!hashdist)
3030 return;
3031
3032 dentry_hashtable =
3033 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003034 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003035 dhash_entries,
3036 13,
3037 0,
3038 &d_hash_shift,
3039 &d_hash_mask,
3040 0);
3041
Dimitri Sivanich074b8512012-02-08 12:39:07 -08003042 for (loop = 0; loop < (1U << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003043 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003044}
3045
3046/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08003047struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003048EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003049
Linus Torvalds1da177e2005-04-16 15:20:36 -07003050EXPORT_SYMBOL(d_genocide);
3051
Linus Torvalds1da177e2005-04-16 15:20:36 -07003052void __init vfs_caches_init_early(void)
3053{
3054 dcache_init_early();
3055 inode_init_early();
3056}
3057
3058void __init vfs_caches_init(unsigned long mempages)
3059{
3060 unsigned long reserve;
3061
3062 /* Base hash sizes on available memory, with a reserve equal to
3063 150% of current kernel size */
3064
3065 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3066 mempages -= reserve;
3067
3068 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003069 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003070
Denis Cheng74bf17c2007-10-16 23:26:30 -07003071 dcache_init();
3072 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003073 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003074 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003075 bdev_cache_init();
3076 chrdev_init();
3077}