blob: 10ba92def3f675985871f0fc72e9c6d7126357a3 [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"
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
Nick Piggin789680d2011-01-07 17:49:30 +110042/*
43 * Usage:
Nick Piggin873feea2011-01-07 17:50:06 +110044 * dcache->d_inode->i_lock protects:
45 * - i_dentry, d_alias, d_inode of aliases
Nick Pigginceb5bdc2011-01-07 17:50:05 +110046 * dcache_hash_bucket lock protects:
47 * - the dcache hash table
48 * s_anon bl list spinlock protects:
49 * - the s_anon list (see __d_drop)
Nick Piggin23044502011-01-07 17:49:31 +110050 * dcache_lru_lock protects:
51 * - the dcache lru lists and counters
52 * d_lock protects:
53 * - d_flags
54 * - d_name
55 * - d_lru
Nick Pigginb7ab39f2011-01-07 17:49:32 +110056 * - d_count
Nick Pigginda502952011-01-07 17:49:33 +110057 * - d_unhashed()
Nick Piggin2fd6b7f2011-01-07 17:49:34 +110058 * - d_parent and d_subdirs
59 * - childrens' d_child and d_parent
Nick Pigginb23fb0a2011-01-07 17:49:35 +110060 * - d_alias, d_inode
Nick Piggin789680d2011-01-07 17:49:30 +110061 *
62 * Ordering:
Nick Piggin873feea2011-01-07 17:50:06 +110063 * dentry->d_inode->i_lock
Nick Pigginb5c84bf2011-01-07 17:49:38 +110064 * dentry->d_lock
65 * dcache_lru_lock
Nick Pigginceb5bdc2011-01-07 17:50:05 +110066 * dcache_hash_bucket lock
67 * s_anon lock
Nick Piggin789680d2011-01-07 17:49:30 +110068 *
Nick Pigginda502952011-01-07 17:49:33 +110069 * If there is an ancestor relationship:
70 * dentry->d_parent->...->d_parent->d_lock
71 * ...
72 * dentry->d_parent->d_lock
73 * dentry->d_lock
74 *
75 * If no ancestor relationship:
Nick Piggin789680d2011-01-07 17:49:30 +110076 * if (dentry1 < dentry2)
77 * dentry1->d_lock
78 * dentry2->d_lock
79 */
Eric Dumazetfa3536c2006-03-26 01:37:24 -080080int sysctl_vfs_cache_pressure __read_mostly = 100;
Linus Torvalds1da177e2005-04-16 15:20:36 -070081EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
82
Nick Piggin23044502011-01-07 17:49:31 +110083static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
Al Viro74c3cbe2007-07-22 08:04:18 -040084__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
Nick Piggin949854d2011-01-07 17:49:37 +110086EXPORT_SYMBOL(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
Christoph Lametere18b8902006-12-06 20:33:20 -080088static struct kmem_cache *dentry_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070089
Linus Torvalds1da177e2005-04-16 15:20:36 -070090/*
91 * This is the single most critical data structure when it comes
92 * to the dcache: the hashtable for lookups. Somebody should try
93 * to make this good - I've just made it work.
94 *
95 * This hash-function tries to avoid losing too many bits of hash
96 * information, yet avoid using a prime hash-size or similar.
97 */
98#define D_HASHBITS d_hash_shift
99#define D_HASHMASK d_hash_mask
100
Eric Dumazetfa3536c2006-03-26 01:37:24 -0800101static unsigned int d_hash_mask __read_mostly;
102static unsigned int d_hash_shift __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100103
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700104static struct hlist_bl_head *dentry_hashtable __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100105
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700106static inline struct hlist_bl_head *d_hash(struct dentry *parent,
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100107 unsigned long hash)
108{
109 hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
110 hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
111 return dentry_hashtable + (hash & D_HASHMASK);
112}
113
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114/* Statistics gathering. */
115struct dentry_stat_t dentry_stat = {
116 .age_limit = 45,
117};
118
Nick Piggin3e880fb2011-01-07 17:49:19 +1100119static DEFINE_PER_CPU(unsigned int, nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400120
121#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Nick Piggin3e880fb2011-01-07 17:49:19 +1100122static int get_nr_dentry(void)
123{
124 int i;
125 int sum = 0;
126 for_each_possible_cpu(i)
127 sum += per_cpu(nr_dentry, i);
128 return sum < 0 ? 0 : sum;
129}
130
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400131int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
132 size_t *lenp, loff_t *ppos)
133{
Nick Piggin3e880fb2011-01-07 17:49:19 +1100134 dentry_stat.nr_dentry = get_nr_dentry();
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400135 return proc_dointvec(table, write, buffer, lenp, ppos);
136}
137#endif
138
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400139static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400141 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
142
Arjan van de Venfd217f42008-10-21 06:47:33 -0700143 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 if (dname_external(dentry))
145 kfree(dentry->d_name.name);
146 kmem_cache_free(dentry_cache, dentry);
147}
148
149/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100150 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 */
152static void d_free(struct dentry *dentry)
153{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100154 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100155 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 if (dentry->d_op && dentry->d_op->d_release)
157 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400158
Linus Torvaldsdea36672011-04-24 07:58:46 -0700159 /* if dentry was never visible to RCU, immediate free is OK */
160 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400161 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800162 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400163 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164}
165
Nick Piggin31e6b012011-01-07 17:49:52 +1100166/**
167 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800168 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100169 * After this call, in-progress rcu-walk path lookup will fail. This
170 * should be called after unhashing, and after changing d_inode (if
171 * the dentry has not already been unhashed).
172 */
173static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
174{
175 assert_spin_locked(&dentry->d_lock);
176 /* Go through a barrier */
177 write_seqcount_barrier(&dentry->d_seq);
178}
179
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180/*
181 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100182 * d_iput() operation if defined. Dentry has no refcount
183 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800185static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200186 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100187 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188{
189 struct inode *inode = dentry->d_inode;
190 if (inode) {
191 dentry->d_inode = NULL;
192 list_del_init(&dentry->d_alias);
193 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100194 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700195 if (!inode->i_nlink)
196 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 if (dentry->d_op && dentry->d_op->d_iput)
198 dentry->d_op->d_iput(dentry, inode);
199 else
200 iput(inode);
201 } else {
202 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 }
204}
205
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700206/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100207 * Release the dentry's inode, using the filesystem
208 * d_iput() operation if defined. dentry remains in-use.
209 */
210static void dentry_unlink_inode(struct dentry * dentry)
211 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100212 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100213{
214 struct inode *inode = dentry->d_inode;
215 dentry->d_inode = NULL;
216 list_del_init(&dentry->d_alias);
217 dentry_rcuwalk_barrier(dentry);
218 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100219 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100220 if (!inode->i_nlink)
221 fsnotify_inoderemove(inode);
222 if (dentry->d_op && dentry->d_op->d_iput)
223 dentry->d_op->d_iput(dentry, inode);
224 else
225 iput(inode);
226}
227
228/*
Sage Weilf0023bc2011-10-28 10:02:42 -0700229 * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700230 */
231static void dentry_lru_add(struct dentry *dentry)
232{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400233 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100234 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400235 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
236 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100237 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100238 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400239 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700240}
241
Nick Piggin23044502011-01-07 17:49:31 +1100242static void __dentry_lru_del(struct dentry *dentry)
243{
244 list_del_init(&dentry->d_lru);
245 dentry->d_sb->s_nr_dentry_unused--;
246 dentry_stat.nr_unused--;
247}
248
Sage Weilf0023bc2011-10-28 10:02:42 -0700249/*
250 * Remove a dentry with references from the LRU.
251 */
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700252static void dentry_lru_del(struct dentry *dentry)
253{
254 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100255 spin_lock(&dcache_lru_lock);
256 __dentry_lru_del(dentry);
257 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700258 }
259}
260
Sage Weilf0023bc2011-10-28 10:02:42 -0700261/*
262 * Remove a dentry that is unreferenced and about to be pruned
263 * (unhashed and destroyed) from the LRU, and inform the file system.
264 * This wrapper should be called _prior_ to unhashing a victim dentry.
265 */
266static void dentry_lru_prune(struct dentry *dentry)
267{
268 if (!list_empty(&dentry->d_lru)) {
269 if (dentry->d_flags & DCACHE_OP_PRUNE)
270 dentry->d_op->d_prune(dentry);
271
272 spin_lock(&dcache_lru_lock);
273 __dentry_lru_del(dentry);
274 spin_unlock(&dcache_lru_lock);
275 }
276}
277
Christoph Hellwiga4633352010-10-10 05:36:26 -0400278static void dentry_lru_move_tail(struct dentry *dentry)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700279{
Nick Piggin23044502011-01-07 17:49:31 +1100280 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400281 if (list_empty(&dentry->d_lru)) {
282 list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
283 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100284 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400285 } else {
286 list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700287 }
Nick Piggin23044502011-01-07 17:49:31 +1100288 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700289}
290
Miklos Szeredid52b9082007-05-08 00:23:46 -0700291/**
292 * d_kill - kill dentry and return parent
293 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800294 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700295 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200296 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700297 *
298 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100299 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100300 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
301 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700302 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100303static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200304 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100305 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100306 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700307{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700308 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400309 /*
310 * Inform try_to_ascend() that we are no longer attached to the
311 * dentry tree
312 */
313 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100314 if (parent)
315 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700316 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100317 /*
318 * dentry_iput drops the locks, at which point nobody (except
319 * transient RCU lookups) can reach this dentry.
320 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700321 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900322 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700323}
324
David Howellsc6627c62011-06-07 14:09:20 +0100325/*
326 * Unhash a dentry without inserting an RCU walk barrier or checking that
327 * dentry->d_lock is locked. The caller must take care of that, if
328 * appropriate.
329 */
330static void __d_shrink(struct dentry *dentry)
331{
332 if (!d_unhashed(dentry)) {
333 struct hlist_bl_head *b;
334 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
335 b = &dentry->d_sb->s_anon;
336 else
337 b = d_hash(dentry->d_parent, dentry->d_name.hash);
338
339 hlist_bl_lock(b);
340 __hlist_bl_del(&dentry->d_hash);
341 dentry->d_hash.pprev = NULL;
342 hlist_bl_unlock(b);
343 }
344}
345
Nick Piggin789680d2011-01-07 17:49:30 +1100346/**
347 * d_drop - drop a dentry
348 * @dentry: dentry to drop
349 *
350 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
351 * be found through a VFS lookup any more. Note that this is different from
352 * deleting the dentry - d_delete will try to mark the dentry negative if
353 * possible, giving a successful _negative_ lookup, while d_drop will
354 * just make the cache lookup fail.
355 *
356 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
357 * reason (NFS timeouts or autofs deletes).
358 *
359 * __d_drop requires dentry->d_lock.
360 */
361void __d_drop(struct dentry *dentry)
362{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700363 if (!d_unhashed(dentry)) {
David Howellsc6627c62011-06-07 14:09:20 +0100364 __d_shrink(dentry);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700365 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100366 }
367}
368EXPORT_SYMBOL(__d_drop);
369
370void d_drop(struct dentry *dentry)
371{
Nick Piggin789680d2011-01-07 17:49:30 +1100372 spin_lock(&dentry->d_lock);
373 __d_drop(dentry);
374 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100375}
376EXPORT_SYMBOL(d_drop);
377
Nick Piggin77812a12011-01-07 17:49:48 +1100378/*
Josef Bacik44396f42011-05-31 11:58:49 -0400379 * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag
380 * @dentry: dentry to drop
381 *
382 * This is called when we do a lookup on a placeholder dentry that needed to be
383 * looked up. The dentry should have been hashed in order for it to be found by
384 * the lookup code, but now needs to be unhashed while we do the actual lookup
385 * and clear the DCACHE_NEED_LOOKUP flag.
386 */
387void d_clear_need_lookup(struct dentry *dentry)
388{
389 spin_lock(&dentry->d_lock);
390 __d_drop(dentry);
391 dentry->d_flags &= ~DCACHE_NEED_LOOKUP;
392 spin_unlock(&dentry->d_lock);
393}
394EXPORT_SYMBOL(d_clear_need_lookup);
395
396/*
Nick Piggin77812a12011-01-07 17:49:48 +1100397 * Finish off a dentry we've decided to kill.
398 * dentry->d_lock must be held, returns with it unlocked.
399 * If ref is non-zero, then decrement the refcount too.
400 * Returns dentry requiring refcount drop, or NULL if we're done.
401 */
402static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
403 __releases(dentry->d_lock)
404{
Nick Piggin873feea2011-01-07 17:50:06 +1100405 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100406 struct dentry *parent;
407
Nick Piggin873feea2011-01-07 17:50:06 +1100408 inode = dentry->d_inode;
409 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100410relock:
411 spin_unlock(&dentry->d_lock);
412 cpu_relax();
413 return dentry; /* try again with same dentry */
414 }
415 if (IS_ROOT(dentry))
416 parent = NULL;
417 else
418 parent = dentry->d_parent;
419 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100420 if (inode)
421 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100422 goto relock;
423 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100424
Nick Piggin77812a12011-01-07 17:49:48 +1100425 if (ref)
426 dentry->d_count--;
Sage Weilf0023bc2011-10-28 10:02:42 -0700427 /*
428 * if dentry was on the d_lru list delete it from there.
429 * inform the fs via d_prune that this dentry is about to be
430 * unhashed and destroyed.
431 */
432 dentry_lru_prune(dentry);
Nick Piggin77812a12011-01-07 17:49:48 +1100433 /* if it was on the hash then remove it */
434 __d_drop(dentry);
435 return d_kill(dentry, parent);
436}
437
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438/*
439 * This is dput
440 *
441 * This is complicated by the fact that we do not want to put
442 * dentries that are no longer on any hash chain on the unused
443 * list: we'd much rather just get rid of them immediately.
444 *
445 * However, that implies that we have to traverse the dentry
446 * tree upwards to the parents which might _also_ now be
447 * scheduled for deletion (it may have been only waiting for
448 * its last child to go away).
449 *
450 * This tail recursion is done by hand as we don't want to depend
451 * on the compiler to always get this right (gcc generally doesn't).
452 * Real recursion would eat up our stack space.
453 */
454
455/*
456 * dput - release a dentry
457 * @dentry: dentry to release
458 *
459 * Release a dentry. This will drop the usage count and if appropriate
460 * call the dentry unlink method as well as removing it from the queues and
461 * releasing its resources. If the parent dentries were scheduled for release
462 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464void dput(struct dentry *dentry)
465{
466 if (!dentry)
467 return;
468
469repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100470 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100473 BUG_ON(!dentry->d_count);
474 if (dentry->d_count > 1) {
475 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 return;
478 }
479
Nick Pigginfb045ad2011-01-07 17:49:55 +1100480 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100482 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 }
Nick Piggin265ac902010-10-10 05:36:24 -0400484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 /* Unreachable? Get rid of it */
486 if (d_unhashed(dentry))
487 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400488
Josef Bacik44396f42011-05-31 11:58:49 -0400489 /*
490 * If this dentry needs lookup, don't set the referenced flag so that it
491 * is more likely to be cleaned up by the dcache shrinker in case of
492 * memory pressure.
493 */
494 if (!d_need_lookup(dentry))
495 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400496 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400497
Nick Piggin61f3dee2011-01-07 17:49:40 +1100498 dentry->d_count--;
499 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 return;
501
Miklos Szeredid52b9082007-05-08 00:23:46 -0700502kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100503 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700504 if (dentry)
505 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700507EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508
509/**
510 * d_invalidate - invalidate a dentry
511 * @dentry: dentry to invalidate
512 *
513 * Try to invalidate the dentry if it turns out to be
514 * possible. If there are other dentries that can be
515 * reached through this one we can't delete it and we
516 * return -EBUSY. On success we return 0.
517 *
518 * no dcache lock.
519 */
520
521int d_invalidate(struct dentry * dentry)
522{
523 /*
524 * If it's already been dropped, return OK.
525 */
Nick Pigginda502952011-01-07 17:49:33 +1100526 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100528 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 return 0;
530 }
531 /*
532 * Check whether to do a partial shrink_dcache
533 * to get rid of unused child entries.
534 */
535 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100536 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100538 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 }
540
541 /*
542 * Somebody else still using it?
543 *
544 * If it's a directory, we can't drop it
545 * for fear of somebody re-populating it
546 * with children (even though dropping it
547 * would make it unreachable from the root,
548 * we might still populate it if it was a
549 * working directory or similar).
Al Viro50e69632011-11-07 16:39:57 +0000550 * We also need to leave mountpoints alone,
551 * directory or not.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 */
Al Viro50e69632011-11-07 16:39:57 +0000553 if (dentry->d_count > 1 && dentry->d_inode) {
554 if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 return -EBUSY;
557 }
558 }
559
560 __d_drop(dentry);
561 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 return 0;
563}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700564EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100566/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100567static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100569 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570}
571
Nick Piggindc0474b2011-01-07 17:49:43 +1100572static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100573{
Nick Piggin23044502011-01-07 17:49:31 +1100574 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100575 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100576 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100577}
578
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100579struct dentry *dget_parent(struct dentry *dentry)
580{
581 struct dentry *ret;
582
583repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100584 /*
585 * Don't need rcu_dereference because we re-check it was correct under
586 * the lock.
587 */
588 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100589 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100590 spin_lock(&ret->d_lock);
591 if (unlikely(ret != dentry->d_parent)) {
592 spin_unlock(&ret->d_lock);
593 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100594 goto repeat;
595 }
Nick Piggina734eb42011-01-07 17:49:44 +1100596 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100597 BUG_ON(!ret->d_count);
598 ret->d_count++;
599 spin_unlock(&ret->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100600 return ret;
601}
602EXPORT_SYMBOL(dget_parent);
603
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604/**
605 * d_find_alias - grab a hashed alias of inode
606 * @inode: inode in question
607 * @want_discon: flag, used by d_splice_alias, to request
608 * that only a DISCONNECTED alias be returned.
609 *
610 * If inode has a hashed alias, or is a directory and has any alias,
611 * acquire the reference to alias and return it. Otherwise return NULL.
612 * Notice that if inode is a directory there can be only one alias and
613 * it can be unhashed only if it has no children, or if it is the root
614 * of a filesystem.
615 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700616 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700618 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 */
Nick Pigginda502952011-01-07 17:49:33 +1100620static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621{
Nick Pigginda502952011-01-07 17:49:33 +1100622 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623
Nick Pigginda502952011-01-07 17:49:33 +1100624again:
625 discon_alias = NULL;
626 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
627 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700629 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100630 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100632 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100633 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100634 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 return alias;
636 }
637 }
Nick Pigginda502952011-01-07 17:49:33 +1100638 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 }
Nick Pigginda502952011-01-07 17:49:33 +1100640 if (discon_alias) {
641 alias = discon_alias;
642 spin_lock(&alias->d_lock);
643 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
644 if (IS_ROOT(alias) &&
645 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100646 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100647 spin_unlock(&alias->d_lock);
648 return alias;
649 }
650 }
651 spin_unlock(&alias->d_lock);
652 goto again;
653 }
654 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655}
656
Nick Pigginda502952011-01-07 17:49:33 +1100657struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658{
David Howells214fda12006-03-25 03:06:36 -0800659 struct dentry *de = NULL;
660
661 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100662 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800663 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100664 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800665 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 return de;
667}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700668EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669
670/*
671 * Try to kill dentries associated with this inode.
672 * WARNING: you must own a reference to inode.
673 */
674void d_prune_aliases(struct inode *inode)
675{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700676 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100678 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700679 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100681 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100682 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 __d_drop(dentry);
684 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100685 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 dput(dentry);
687 goto restart;
688 }
689 spin_unlock(&dentry->d_lock);
690 }
Nick Piggin873feea2011-01-07 17:50:06 +1100691 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700693EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694
695/*
Nick Piggin77812a12011-01-07 17:49:48 +1100696 * Try to throw away a dentry - free the inode, dput the parent.
697 * Requires dentry->d_lock is held, and dentry->d_count == 0.
698 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700699 *
Nick Piggin77812a12011-01-07 17:49:48 +1100700 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 */
Nick Piggin77812a12011-01-07 17:49:48 +1100702static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200703 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704{
Nick Piggin77812a12011-01-07 17:49:48 +1100705 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700706
Nick Piggin77812a12011-01-07 17:49:48 +1100707 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700708 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100709 * If dentry_kill returns NULL, we have nothing more to do.
710 * if it returns the same dentry, trylocks failed. In either
711 * case, just loop again.
712 *
713 * Otherwise, we need to prune ancestors too. This is necessary
714 * to prevent quadratic behavior of shrink_dcache_parent(), but
715 * is also expected to be beneficial in reducing dentry cache
716 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700717 */
Nick Piggin77812a12011-01-07 17:49:48 +1100718 if (!parent)
719 return;
720 if (parent == dentry)
721 return;
722
723 /* Prune ancestors. */
724 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700725 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100726 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100727 if (dentry->d_count > 1) {
728 dentry->d_count--;
729 spin_unlock(&dentry->d_lock);
730 return;
731 }
Nick Piggin77812a12011-01-07 17:49:48 +1100732 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700733 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734}
735
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400736static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700738 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700739
Nick Pigginec336792011-01-07 17:49:47 +1100740 rcu_read_lock();
741 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100742 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
743 if (&dentry->d_lru == list)
744 break; /* empty */
745 spin_lock(&dentry->d_lock);
746 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
747 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100748 continue;
749 }
750
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 /*
752 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700753 * the LRU because of laziness during lookup. Do not free
754 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100756 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100757 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700758 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 continue;
760 }
Nick Pigginec336792011-01-07 17:49:47 +1100761
Nick Pigginec336792011-01-07 17:49:47 +1100762 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100763
764 try_prune_one_dentry(dentry);
765
Nick Pigginec336792011-01-07 17:49:47 +1100766 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 }
Nick Pigginec336792011-01-07 17:49:47 +1100768 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400769}
770
771/**
772 * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
773 * @sb: superblock to shrink dentry LRU.
774 * @count: number of entries to prune
775 * @flags: flags to control the dentry processing
776 *
777 * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
778 */
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000779static void __shrink_dcache_sb(struct super_block *sb, int count, int flags)
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400780{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400781 struct dentry *dentry;
782 LIST_HEAD(referenced);
783 LIST_HEAD(tmp);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400784
Nick Piggin23044502011-01-07 17:49:31 +1100785relock:
786 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400787 while (!list_empty(&sb->s_dentry_lru)) {
788 dentry = list_entry(sb->s_dentry_lru.prev,
789 struct dentry, d_lru);
790 BUG_ON(dentry->d_sb != sb);
791
Nick Piggin23044502011-01-07 17:49:31 +1100792 if (!spin_trylock(&dentry->d_lock)) {
793 spin_unlock(&dcache_lru_lock);
794 cpu_relax();
795 goto relock;
796 }
797
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400798 /*
799 * If we are honouring the DCACHE_REFERENCED flag and the
800 * dentry has this flag set, don't free it. Clear the flag
801 * and put it back on the LRU.
802 */
Nick Piggin23044502011-01-07 17:49:31 +1100803 if (flags & DCACHE_REFERENCED &&
804 dentry->d_flags & DCACHE_REFERENCED) {
805 dentry->d_flags &= ~DCACHE_REFERENCED;
806 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400807 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100808 } else {
809 list_move_tail(&dentry->d_lru, &tmp);
810 spin_unlock(&dentry->d_lock);
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000811 if (!--count)
Nick Piggin23044502011-01-07 17:49:31 +1100812 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400813 }
Nick Pigginec336792011-01-07 17:49:47 +1100814 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400815 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700816 if (!list_empty(&referenced))
817 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100818 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100819
820 shrink_dentry_list(&tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821}
822
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700823/**
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000824 * prune_dcache_sb - shrink the dcache
Randy Dunlap2af14162011-08-03 16:21:07 -0700825 * @sb: superblock
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000826 * @nr_to_scan: number of entries to try to free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 *
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000828 * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
829 * done when we need more memory an called from the superblock shrinker
830 * function.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700831 *
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000832 * This function may fail to free any resources if all the dentries are in
833 * use.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 */
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000835void prune_dcache_sb(struct super_block *sb, int nr_to_scan)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700836{
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000837 __shrink_dcache_sb(sb, nr_to_scan, DCACHE_REFERENCED);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700838}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839
840/**
841 * shrink_dcache_sb - shrink dcache for a superblock
842 * @sb: superblock
843 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400844 * Shrink the dcache for the specified super block. This is used to free
845 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400847void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400849 LIST_HEAD(tmp);
850
Nick Piggin23044502011-01-07 17:49:31 +1100851 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400852 while (!list_empty(&sb->s_dentry_lru)) {
853 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100854 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400855 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100856 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400857 }
Nick Piggin23044502011-01-07 17:49:31 +1100858 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700860EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861
862/*
David Howellsc636ebd2006-10-11 01:22:19 -0700863 * destroy a single subtree of dentries for unmount
864 * - see the comments on shrink_dcache_for_umount() for a description of the
865 * locking
866 */
867static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
868{
869 struct dentry *parent;
870
871 BUG_ON(!IS_ROOT(dentry));
872
David Howellsc636ebd2006-10-11 01:22:19 -0700873 for (;;) {
874 /* descend to the first leaf in the current subtree */
David Howells43c1c9c2011-06-07 14:09:30 +0100875 while (!list_empty(&dentry->d_subdirs))
David Howellsc636ebd2006-10-11 01:22:19 -0700876 dentry = list_entry(dentry->d_subdirs.next,
877 struct dentry, d_u.d_child);
David Howellsc636ebd2006-10-11 01:22:19 -0700878
879 /* consume the dentries from this leaf up through its parents
880 * until we find one with children or run out altogether */
881 do {
882 struct inode *inode;
883
Sage Weilf0023bc2011-10-28 10:02:42 -0700884 /*
885 * remove the dentry from the lru, and inform
886 * the fs that this dentry is about to be
887 * unhashed and destroyed.
888 */
889 dentry_lru_prune(dentry);
David Howells43c1c9c2011-06-07 14:09:30 +0100890 __d_shrink(dentry);
891
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100892 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700893 printk(KERN_ERR
894 "BUG: Dentry %p{i=%lx,n=%s}"
895 " still in use (%d)"
896 " [unmount of %s %s]\n",
897 dentry,
898 dentry->d_inode ?
899 dentry->d_inode->i_ino : 0UL,
900 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100901 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700902 dentry->d_sb->s_type->name,
903 dentry->d_sb->s_id);
904 BUG();
905 }
906
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100907 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700908 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100909 list_del(&dentry->d_u.d_child);
910 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900911 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100912 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100913 list_del(&dentry->d_u.d_child);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900914 }
David Howellsc636ebd2006-10-11 01:22:19 -0700915
David Howellsc636ebd2006-10-11 01:22:19 -0700916 inode = dentry->d_inode;
917 if (inode) {
918 dentry->d_inode = NULL;
919 list_del_init(&dentry->d_alias);
920 if (dentry->d_op && dentry->d_op->d_iput)
921 dentry->d_op->d_iput(dentry, inode);
922 else
923 iput(inode);
924 }
925
926 d_free(dentry);
927
928 /* finished when we fall off the top of the tree,
929 * otherwise we ascend to the parent and move to the
930 * next sibling if there is one */
931 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400932 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700933 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700934 } while (list_empty(&dentry->d_subdirs));
935
936 dentry = list_entry(dentry->d_subdirs.next,
937 struct dentry, d_u.d_child);
938 }
939}
940
941/*
942 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100943 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700944 * - the superblock is detached from all mountings and open files, so the
945 * dentry trees will not be rearranged by the VFS
946 * - s_umount is write-locked, so the memory pressure shrinker will ignore
947 * any dentries belonging to this superblock that it comes across
948 * - the filesystem itself is no longer permitted to rearrange the dentries
949 * in this superblock
950 */
951void shrink_dcache_for_umount(struct super_block *sb)
952{
953 struct dentry *dentry;
954
955 if (down_read_trylock(&sb->s_umount))
956 BUG();
957
958 dentry = sb->s_root;
959 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100960 dentry->d_count--;
David Howellsc636ebd2006-10-11 01:22:19 -0700961 shrink_dcache_for_umount_subtree(dentry);
962
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100963 while (!hlist_bl_empty(&sb->s_anon)) {
964 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700965 shrink_dcache_for_umount_subtree(dentry);
966 }
967}
968
969/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700970 * This tries to ascend one level of parenthood, but
971 * we can race with renaming, so we need to re-check
972 * the parenthood after dropping the lock and check
973 * that the sequence number still matches.
974 */
975static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
976{
977 struct dentry *new = old->d_parent;
978
979 rcu_read_lock();
980 spin_unlock(&old->d_lock);
981 spin_lock(&new->d_lock);
982
983 /*
984 * might go back up the wrong parent if we have had a rename
985 * or deletion
986 */
987 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -0400988 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700989 (!locked && read_seqretry(&rename_lock, seq))) {
990 spin_unlock(&new->d_lock);
991 new = NULL;
992 }
993 rcu_read_unlock();
994 return new;
995}
996
997
998/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 * Search for at least 1 mount point in the dentry's subdirs.
1000 * We descend to the next level whenever the d_subdirs
1001 * list is non-empty and continue searching.
1002 */
1003
1004/**
1005 * have_submounts - check for mounts over a dentry
1006 * @parent: dentry to check.
1007 *
1008 * Return true if the parent or its subdirectories contain
1009 * a mount point
1010 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011int have_submounts(struct dentry *parent)
1012{
Nick Piggin949854d2011-01-07 17:49:37 +11001013 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001015 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11001016 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001017
Nick Piggin949854d2011-01-07 17:49:37 +11001018 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001019again:
1020 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 if (d_mountpoint(parent))
1023 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001024 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025repeat:
1026 next = this_parent->d_subdirs.next;
1027resume:
1028 while (next != &this_parent->d_subdirs) {
1029 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001030 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001032
1033 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001035 if (d_mountpoint(dentry)) {
1036 spin_unlock(&dentry->d_lock);
1037 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001039 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001041 spin_unlock(&this_parent->d_lock);
1042 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001044 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045 goto repeat;
1046 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001047 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 }
1049 /*
1050 * All done at this level ... ascend and resume the search.
1051 */
1052 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001053 struct dentry *child = this_parent;
1054 this_parent = try_to_ascend(this_parent, locked, seq);
1055 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001056 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001057 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 goto resume;
1059 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001060 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001061 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001062 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001063 if (locked)
1064 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 return 0; /* No mount points found in tree */
1066positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001067 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001068 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001069 if (locked)
1070 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001072
1073rename_retry:
1074 locked = 1;
1075 write_seqlock(&rename_lock);
1076 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001078EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079
1080/*
1081 * Search the dentry child list for the specified parent,
1082 * and move any unused dentries to the end of the unused
1083 * list for prune_dcache(). We descend to the next level
1084 * whenever the d_subdirs list is non-empty and continue
1085 * searching.
1086 *
1087 * It returns zero iff there are no unused children,
1088 * otherwise it returns the number of children moved to
1089 * the end of the unused list. This may not be the total
1090 * number of unused children, because select_parent can
1091 * drop the lock and return early due to latency
1092 * constraints.
1093 */
1094static int select_parent(struct dentry * parent)
1095{
Nick Piggin949854d2011-01-07 17:49:37 +11001096 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001098 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001100 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101
Nick Piggin949854d2011-01-07 17:49:37 +11001102 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001103again:
1104 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001105 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106repeat:
1107 next = this_parent->d_subdirs.next;
1108resume:
1109 while (next != &this_parent->d_subdirs) {
1110 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001111 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112 next = tmp->next;
1113
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001114 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001115
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 /*
1117 * move only zero ref count dentries to the end
1118 * of the unused list for prune_dcache
1119 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001120 if (!dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001121 dentry_lru_move_tail(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 found++;
Christoph Hellwiga4633352010-10-10 05:36:26 -04001123 } else {
1124 dentry_lru_del(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 }
1126
1127 /*
1128 * We can return to the caller if we have found some (this
1129 * ensures forward progress). We'll be coming back to find
1130 * the rest.
1131 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001132 if (found && need_resched()) {
1133 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 goto out;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001135 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136
1137 /*
1138 * Descend a level if the d_subdirs list is non-empty.
1139 */
1140 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001141 spin_unlock(&this_parent->d_lock);
1142 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001144 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 goto repeat;
1146 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001147
1148 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 }
1150 /*
1151 * All done at this level ... ascend and resume the search.
1152 */
1153 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001154 struct dentry *child = this_parent;
1155 this_parent = try_to_ascend(this_parent, locked, seq);
1156 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001157 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001158 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 goto resume;
1160 }
1161out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001162 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001163 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001164 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001165 if (locked)
1166 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167 return found;
Nick Piggin58db63d2011-01-07 17:49:39 +11001168
1169rename_retry:
1170 if (found)
1171 return found;
1172 locked = 1;
1173 write_seqlock(&rename_lock);
1174 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175}
1176
1177/**
1178 * shrink_dcache_parent - prune dcache
1179 * @parent: parent of entries to prune
1180 *
1181 * Prune the dcache to remove unused children of the parent dentry.
1182 */
1183
1184void shrink_dcache_parent(struct dentry * parent)
1185{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -07001186 struct super_block *sb = parent->d_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187 int found;
1188
1189 while ((found = select_parent(parent)) != 0)
Dave Chinnerb0d40c92011-07-08 14:14:42 +10001190 __shrink_dcache_sb(sb, found, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001192EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194/**
Al Viroa4464db2011-07-07 15:03:58 -04001195 * __d_alloc - allocate a dcache entry
1196 * @sb: filesystem it will belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 * @name: qstr of the name
1198 *
1199 * Allocates a dentry. It returns %NULL if there is insufficient memory
1200 * available. On a success the dentry is returned. The name passed in is
1201 * copied and the copy passed in may be reused after this call.
1202 */
1203
Al Viroa4464db2011-07-07 15:03:58 -04001204struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205{
1206 struct dentry *dentry;
1207 char *dname;
1208
Mel Gormane12ba742007-10-16 01:25:52 -07001209 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 if (!dentry)
1211 return NULL;
1212
1213 if (name->len > DNAME_INLINE_LEN-1) {
1214 dname = kmalloc(name->len + 1, GFP_KERNEL);
1215 if (!dname) {
1216 kmem_cache_free(dentry_cache, dentry);
1217 return NULL;
1218 }
1219 } else {
1220 dname = dentry->d_iname;
1221 }
1222 dentry->d_name.name = dname;
1223
1224 dentry->d_name.len = name->len;
1225 dentry->d_name.hash = name->hash;
1226 memcpy(dname, name->name, name->len);
1227 dname[name->len] = 0;
1228
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001229 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001230 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001232 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 dentry->d_inode = NULL;
Al Viroa4464db2011-07-07 15:03:58 -04001234 dentry->d_parent = dentry;
1235 dentry->d_sb = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236 dentry->d_op = NULL;
1237 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001238 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 INIT_LIST_HEAD(&dentry->d_lru);
1240 INIT_LIST_HEAD(&dentry->d_subdirs);
1241 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001242 INIT_LIST_HEAD(&dentry->d_u.d_child);
Al Viroa4464db2011-07-07 15:03:58 -04001243 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244
Nick Piggin3e880fb2011-01-07 17:49:19 +11001245 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001246
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247 return dentry;
1248}
Al Viroa4464db2011-07-07 15:03:58 -04001249
1250/**
1251 * d_alloc - allocate a dcache entry
1252 * @parent: parent of entry to allocate
1253 * @name: qstr of the name
1254 *
1255 * Allocates a dentry. It returns %NULL if there is insufficient memory
1256 * available. On a success the dentry is returned. The name passed in is
1257 * copied and the copy passed in may be reused after this call.
1258 */
1259struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1260{
1261 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1262 if (!dentry)
1263 return NULL;
1264
1265 spin_lock(&parent->d_lock);
1266 /*
1267 * don't need child lock because it is not subject
1268 * to concurrency here
1269 */
1270 __dget_dlock(parent);
1271 dentry->d_parent = parent;
1272 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
1273 spin_unlock(&parent->d_lock);
1274
1275 return dentry;
1276}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001277EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278
Nick Piggin4b936882011-01-07 17:50:07 +11001279struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1280{
Al Viroa4464db2011-07-07 15:03:58 -04001281 struct dentry *dentry = __d_alloc(sb, name);
1282 if (dentry)
Nick Piggin4b936882011-01-07 17:50:07 +11001283 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin4b936882011-01-07 17:50:07 +11001284 return dentry;
1285}
1286EXPORT_SYMBOL(d_alloc_pseudo);
1287
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1289{
1290 struct qstr q;
1291
1292 q.name = name;
1293 q.len = strlen(name);
1294 q.hash = full_name_hash(q.name, q.len);
1295 return d_alloc(parent, &q);
1296}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001297EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298
Nick Pigginfb045ad2011-01-07 17:49:55 +11001299void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1300{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001301 WARN_ON_ONCE(dentry->d_op);
1302 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001303 DCACHE_OP_COMPARE |
1304 DCACHE_OP_REVALIDATE |
1305 DCACHE_OP_DELETE ));
1306 dentry->d_op = op;
1307 if (!op)
1308 return;
1309 if (op->d_hash)
1310 dentry->d_flags |= DCACHE_OP_HASH;
1311 if (op->d_compare)
1312 dentry->d_flags |= DCACHE_OP_COMPARE;
1313 if (op->d_revalidate)
1314 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1315 if (op->d_delete)
1316 dentry->d_flags |= DCACHE_OP_DELETE;
Sage Weilf0023bc2011-10-28 10:02:42 -07001317 if (op->d_prune)
1318 dentry->d_flags |= DCACHE_OP_PRUNE;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001319
1320}
1321EXPORT_SYMBOL(d_set_d_op);
1322
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001323static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1324{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001325 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001326 if (inode) {
1327 if (unlikely(IS_AUTOMOUNT(inode)))
1328 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001329 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001330 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001331 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001332 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001333 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001334 fsnotify_d_instantiate(dentry, inode);
1335}
1336
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337/**
1338 * d_instantiate - fill in inode information for a dentry
1339 * @entry: dentry to complete
1340 * @inode: inode to attach to this dentry
1341 *
1342 * Fill in inode information in the entry.
1343 *
1344 * This turns negative dentries into productive full members
1345 * of society.
1346 *
1347 * NOTE! This assumes that the inode count has been incremented
1348 * (or otherwise set) by the caller to indicate that it is now
1349 * in use by the dcache.
1350 */
1351
1352void d_instantiate(struct dentry *entry, struct inode * inode)
1353{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001354 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001355 if (inode)
1356 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001357 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001358 if (inode)
1359 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 security_d_instantiate(entry, inode);
1361}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001362EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363
1364/**
1365 * d_instantiate_unique - instantiate a non-aliased dentry
1366 * @entry: dentry to instantiate
1367 * @inode: inode to attach to this dentry
1368 *
1369 * Fill in inode information in the entry. On success, it returns NULL.
1370 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001371 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 *
1373 * Note that in order to avoid conflicts with rename() etc, the caller
1374 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001375 *
1376 * This also assumes that the inode count has been incremented
1377 * (or otherwise set) by the caller to indicate that it is now
1378 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 */
David Howells770bfad2006-08-22 20:06:07 -04001380static struct dentry *__d_instantiate_unique(struct dentry *entry,
1381 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382{
1383 struct dentry *alias;
1384 int len = entry->d_name.len;
1385 const char *name = entry->d_name.name;
1386 unsigned int hash = entry->d_name.hash;
1387
David Howells770bfad2006-08-22 20:06:07 -04001388 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001389 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001390 return NULL;
1391 }
1392
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1394 struct qstr *qstr = &alias->d_name;
1395
Nick Piggin9abca362011-01-07 17:49:36 +11001396 /*
1397 * Don't need alias->d_lock here, because aliases with
1398 * d_parent == entry->d_parent are not subject to name or
1399 * parent changes, because the parent inode i_mutex is held.
1400 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 if (qstr->hash != hash)
1402 continue;
1403 if (alias->d_parent != entry->d_parent)
1404 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001405 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001407 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 return alias;
1409 }
David Howells770bfad2006-08-22 20:06:07 -04001410
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001411 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 return NULL;
1413}
David Howells770bfad2006-08-22 20:06:07 -04001414
1415struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1416{
1417 struct dentry *result;
1418
1419 BUG_ON(!list_empty(&entry->d_alias));
1420
Nick Piggin873feea2011-01-07 17:50:06 +11001421 if (inode)
1422 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001423 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001424 if (inode)
1425 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001426
1427 if (!result) {
1428 security_d_instantiate(entry, inode);
1429 return NULL;
1430 }
1431
1432 BUG_ON(!d_unhashed(result));
1433 iput(inode);
1434 return result;
1435}
1436
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437EXPORT_SYMBOL(d_instantiate_unique);
1438
1439/**
1440 * d_alloc_root - allocate root dentry
1441 * @root_inode: inode to allocate the root for
1442 *
1443 * Allocate a root ("/") dentry for the inode given. The inode is
1444 * instantiated and returned. %NULL is returned if there is insufficient
1445 * memory or the inode passed is %NULL.
1446 */
1447
1448struct dentry * d_alloc_root(struct inode * root_inode)
1449{
1450 struct dentry *res = NULL;
1451
1452 if (root_inode) {
1453 static const struct qstr name = { .name = "/", .len = 1 };
1454
Al Viroa4464db2011-07-07 15:03:58 -04001455 res = __d_alloc(root_inode->i_sb, &name);
1456 if (res)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457 d_instantiate(res, root_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 }
1459 return res;
1460}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001461EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001463static struct dentry * __d_find_any_alias(struct inode *inode)
1464{
1465 struct dentry *alias;
1466
1467 if (list_empty(&inode->i_dentry))
1468 return NULL;
1469 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1470 __dget(alias);
1471 return alias;
1472}
1473
1474static struct dentry * d_find_any_alias(struct inode *inode)
1475{
1476 struct dentry *de;
1477
1478 spin_lock(&inode->i_lock);
1479 de = __d_find_any_alias(inode);
1480 spin_unlock(&inode->i_lock);
1481 return de;
1482}
1483
1484
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001486 * d_obtain_alias - find or allocate a dentry for a given inode
1487 * @inode: inode to allocate the dentry for
1488 *
1489 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1490 * similar open by handle operations. The returned dentry may be anonymous,
1491 * or may have a full name (if the inode was already in the cache).
1492 *
1493 * When called on a directory inode, we must ensure that the inode only ever
1494 * has one dentry. If a dentry is found, that is returned instead of
1495 * allocating a new one.
1496 *
1497 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001498 * to the dentry. In case of an error the reference on the inode is released.
1499 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1500 * be passed in and will be the error will be propagate to the return value,
1501 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001502 */
1503struct dentry *d_obtain_alias(struct inode *inode)
1504{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001505 static const struct qstr anonstring = { .name = "" };
1506 struct dentry *tmp;
1507 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001508
1509 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001510 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001511 if (IS_ERR(inode))
1512 return ERR_CAST(inode);
1513
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001514 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001515 if (res)
1516 goto out_iput;
1517
Al Viroa4464db2011-07-07 15:03:58 -04001518 tmp = __d_alloc(inode->i_sb, &anonstring);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001519 if (!tmp) {
1520 res = ERR_PTR(-ENOMEM);
1521 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001522 }
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001523
Nick Piggin873feea2011-01-07 17:50:06 +11001524 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001525 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001526 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001527 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001528 dput(tmp);
1529 goto out_iput;
1530 }
1531
1532 /* attach a disconnected dentry */
1533 spin_lock(&tmp->d_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001534 tmp->d_inode = inode;
1535 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001536 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001537 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001538 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001539 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001540 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001541 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001542 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001543
Christoph Hellwig9308a612008-08-11 15:49:12 +02001544 return tmp;
1545
1546 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001547 if (res && !IS_ERR(res))
1548 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001549 iput(inode);
1550 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001551}
Benny Halevyadc48722009-02-27 14:02:59 -08001552EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553
1554/**
1555 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1556 * @inode: the inode which may have a disconnected dentry
1557 * @dentry: a negative dentry which we want to point to the inode.
1558 *
1559 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1560 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1561 * and return it, else simply d_add the inode to the dentry and return NULL.
1562 *
1563 * This is needed in the lookup routine of any filesystem that is exportable
1564 * (via knfsd) so that we can build dcache paths to directories effectively.
1565 *
1566 * If a dentry was found and moved, then it is returned. Otherwise NULL
1567 * is returned. This matches the expected return value of ->lookup.
1568 *
1569 */
1570struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1571{
1572 struct dentry *new = NULL;
1573
Al Viroa9049372011-07-08 21:20:11 -04001574 if (IS_ERR(inode))
1575 return ERR_CAST(inode);
1576
NeilBrown21c0d8f2006-10-04 02:16:16 -07001577 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001578 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579 new = __d_find_alias(inode, 1);
1580 if (new) {
1581 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001582 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 d_move(new, dentry);
1585 iput(inode);
1586 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001587 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001588 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001589 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 security_d_instantiate(dentry, inode);
1591 d_rehash(dentry);
1592 }
1593 } else
1594 d_add(dentry, inode);
1595 return new;
1596}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001597EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598
Barry Naujok94035402008-05-21 16:50:46 +10001599/**
1600 * d_add_ci - lookup or allocate new dentry with case-exact name
1601 * @inode: the inode case-insensitive lookup has found
1602 * @dentry: the negative dentry that was passed to the parent's lookup func
1603 * @name: the case-exact name to be associated with the returned dentry
1604 *
1605 * This is to avoid filling the dcache with case-insensitive names to the
1606 * same inode, only the actual correct case is stored in the dcache for
1607 * case-insensitive filesystems.
1608 *
1609 * For a case-insensitive lookup match and if the the case-exact dentry
1610 * already exists in in the dcache, use it and return it.
1611 *
1612 * If no entry exists with the exact case name, allocate new dentry with
1613 * the exact case, and return the spliced entry.
1614 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001615struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001616 struct qstr *name)
1617{
1618 int error;
1619 struct dentry *found;
1620 struct dentry *new;
1621
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001622 /*
1623 * First check if a dentry matching the name already exists,
1624 * if not go ahead and create it now.
1625 */
Barry Naujok94035402008-05-21 16:50:46 +10001626 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001627 if (!found) {
1628 new = d_alloc(dentry->d_parent, name);
1629 if (!new) {
1630 error = -ENOMEM;
1631 goto err_out;
1632 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001633
Barry Naujok94035402008-05-21 16:50:46 +10001634 found = d_splice_alias(inode, new);
1635 if (found) {
1636 dput(new);
1637 return found;
1638 }
1639 return new;
1640 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001641
1642 /*
1643 * If a matching dentry exists, and it's not negative use it.
1644 *
1645 * Decrement the reference count to balance the iget() done
1646 * earlier on.
1647 */
Barry Naujok94035402008-05-21 16:50:46 +10001648 if (found->d_inode) {
1649 if (unlikely(found->d_inode != inode)) {
1650 /* This can't happen because bad inodes are unhashed. */
1651 BUG_ON(!is_bad_inode(inode));
1652 BUG_ON(!is_bad_inode(found->d_inode));
1653 }
Barry Naujok94035402008-05-21 16:50:46 +10001654 iput(inode);
1655 return found;
1656 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001657
Barry Naujok94035402008-05-21 16:50:46 +10001658 /*
Josef Bacik44396f42011-05-31 11:58:49 -04001659 * We are going to instantiate this dentry, unhash it and clear the
1660 * lookup flag so we can do that.
1661 */
1662 if (unlikely(d_need_lookup(found)))
1663 d_clear_need_lookup(found);
1664
1665 /*
Barry Naujok94035402008-05-21 16:50:46 +10001666 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001667 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001668 */
Al Viro4513d892011-07-17 10:52:14 -04001669 new = d_splice_alias(inode, found);
1670 if (new) {
1671 dput(found);
1672 found = new;
Barry Naujok94035402008-05-21 16:50:46 +10001673 }
Al Viro4513d892011-07-17 10:52:14 -04001674 return found;
Barry Naujok94035402008-05-21 16:50:46 +10001675
1676err_out:
1677 iput(inode);
1678 return ERR_PTR(error);
1679}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001680EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681
1682/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001683 * __d_lookup_rcu - search for a dentry (racy, store-free)
1684 * @parent: parent dentry
1685 * @name: qstr of name we wish to find
1686 * @seq: returns d_seq value at the point where the dentry was found
1687 * @inode: returns dentry->d_inode when the inode was found valid.
1688 * Returns: dentry, or NULL
1689 *
1690 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1691 * resolution (store-free path walking) design described in
1692 * Documentation/filesystems/path-lookup.txt.
1693 *
1694 * This is not to be used outside core vfs.
1695 *
1696 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1697 * held, and rcu_read_lock held. The returned dentry must not be stored into
1698 * without taking d_lock and checking d_seq sequence count against @seq
1699 * returned here.
1700 *
1701 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1702 * function.
1703 *
1704 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1705 * the returned dentry, so long as its parent's seqlock is checked after the
1706 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1707 * is formed, giving integrity down the path walk.
1708 */
1709struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
1710 unsigned *seq, struct inode **inode)
1711{
1712 unsigned int len = name->len;
1713 unsigned int hash = name->hash;
1714 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001715 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001716 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001717 struct dentry *dentry;
1718
1719 /*
1720 * Note: There is significant duplication with __d_lookup_rcu which is
1721 * required to prevent single threaded performance regressions
1722 * especially on architectures where smp_rmb (in seqcounts) are costly.
1723 * Keep the two functions in sync.
1724 */
1725
1726 /*
1727 * The hash list is protected using RCU.
1728 *
1729 * Carefully use d_seq when comparing a candidate dentry, to avoid
1730 * races with d_move().
1731 *
1732 * It is possible that concurrent renames can mess up our list
1733 * walk here and result in missing our dentry, resulting in the
1734 * false-negative result. d_lookup() protects against concurrent
1735 * renames using rename_lock seqlock.
1736 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001737 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001738 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001739 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001740 struct inode *i;
1741 const char *tname;
1742 int tlen;
1743
1744 if (dentry->d_name.hash != hash)
1745 continue;
1746
1747seqretry:
1748 *seq = read_seqcount_begin(&dentry->d_seq);
1749 if (dentry->d_parent != parent)
1750 continue;
1751 if (d_unhashed(dentry))
1752 continue;
1753 tlen = dentry->d_name.len;
1754 tname = dentry->d_name.name;
1755 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001756 prefetch(tname);
Nick Piggin31e6b012011-01-07 17:49:52 +11001757 /*
1758 * This seqcount check is required to ensure name and
1759 * len are loaded atomically, so as not to walk off the
1760 * edge of memory when walking. If we could load this
1761 * atomically some other way, we could drop this check.
1762 */
1763 if (read_seqcount_retry(&dentry->d_seq, *seq))
1764 goto seqretry;
Linus Torvalds830c0f02011-08-06 22:41:50 -07001765 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001766 if (parent->d_op->d_compare(parent, *inode,
1767 dentry, i,
1768 tlen, tname, name))
1769 continue;
1770 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001771 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001772 continue;
1773 }
1774 /*
1775 * No extra seqcount check is required after the name
1776 * compare. The caller must perform a seqcount check in
1777 * order to do anything useful with the returned dentry
1778 * anyway.
1779 */
1780 *inode = i;
1781 return dentry;
1782 }
1783 return NULL;
1784}
1785
1786/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 * d_lookup - search for a dentry
1788 * @parent: parent dentry
1789 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001790 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001792 * d_lookup searches the children of the parent dentry for the name in
1793 * question. If the dentry is found its reference count is incremented and the
1794 * dentry is returned. The caller must use dput to free the entry when it has
1795 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001797struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798{
Nick Piggin31e6b012011-01-07 17:49:52 +11001799 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001800 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801
1802 do {
1803 seq = read_seqbegin(&rename_lock);
1804 dentry = __d_lookup(parent, name);
1805 if (dentry)
1806 break;
1807 } while (read_seqretry(&rename_lock, seq));
1808 return dentry;
1809}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001810EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811
Nick Piggin31e6b012011-01-07 17:49:52 +11001812/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001813 * __d_lookup - search for a dentry (racy)
1814 * @parent: parent dentry
1815 * @name: qstr of name we wish to find
1816 * Returns: dentry, or NULL
1817 *
1818 * __d_lookup is like d_lookup, however it may (rarely) return a
1819 * false-negative result due to unrelated rename activity.
1820 *
1821 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1822 * however it must be used carefully, eg. with a following d_lookup in
1823 * the case of failure.
1824 *
1825 * __d_lookup callers must be commented.
1826 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001827struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001828{
1829 unsigned int len = name->len;
1830 unsigned int hash = name->hash;
1831 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001832 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001833 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001834 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001835 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836
Nick Pigginb04f7842010-08-18 04:37:34 +10001837 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001838 * Note: There is significant duplication with __d_lookup_rcu which is
1839 * required to prevent single threaded performance regressions
1840 * especially on architectures where smp_rmb (in seqcounts) are costly.
1841 * Keep the two functions in sync.
1842 */
1843
1844 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001845 * The hash list is protected using RCU.
1846 *
1847 * Take d_lock when comparing a candidate dentry, to avoid races
1848 * with d_move().
1849 *
1850 * It is possible that concurrent renames can mess up our list
1851 * walk here and result in missing our dentry, resulting in the
1852 * false-negative result. d_lookup() protects against concurrent
1853 * renames using rename_lock seqlock.
1854 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001855 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001856 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 rcu_read_lock();
1858
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001859 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001860 const char *tname;
1861 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 if (dentry->d_name.hash != hash)
1864 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865
1866 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867 if (dentry->d_parent != parent)
1868 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001869 if (d_unhashed(dentry))
1870 goto next;
1871
Linus Torvalds1da177e2005-04-16 15:20:36 -07001872 /*
1873 * It is safe to compare names since d_move() cannot
1874 * change the qstr (protected by d_lock).
1875 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001876 tlen = dentry->d_name.len;
1877 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001878 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001879 if (parent->d_op->d_compare(parent, parent->d_inode,
1880 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001881 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 goto next;
1883 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001884 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885 goto next;
1886 }
1887
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001888 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001889 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890 spin_unlock(&dentry->d_lock);
1891 break;
1892next:
1893 spin_unlock(&dentry->d_lock);
1894 }
1895 rcu_read_unlock();
1896
1897 return found;
1898}
1899
1900/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001901 * d_hash_and_lookup - hash the qstr then search for a dentry
1902 * @dir: Directory to search in
1903 * @name: qstr of name we wish to find
1904 *
1905 * On hash failure or on lookup failure NULL is returned.
1906 */
1907struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1908{
1909 struct dentry *dentry = NULL;
1910
1911 /*
1912 * Check for a fs-specific hash function. Note that we must
1913 * calculate the standard hash first, as the d_op->d_hash()
1914 * routine may choose to leave the hash value unchanged.
1915 */
1916 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001917 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001918 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001919 goto out;
1920 }
1921 dentry = d_lookup(dir, name);
1922out:
1923 return dentry;
1924}
1925
1926/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001927 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001929 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 *
1931 * An insecure source has sent us a dentry, here we verify it and dget() it.
1932 * This is used by ncpfs in its readdir implementation.
1933 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001934 *
1935 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001937int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938{
Nick Piggin786a5e12011-01-07 17:49:16 +11001939 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001940
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001941 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001942 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
1943 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001944 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11001945 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001946 spin_unlock(&dentry->d_lock);
1947 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 return 1;
1949 }
1950 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001951 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001952
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953 return 0;
1954}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001955EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956
1957/*
1958 * When a file is deleted, we have two options:
1959 * - turn this dentry into a negative dentry
1960 * - unhash this dentry and free it.
1961 *
1962 * Usually, we want to just turn this into
1963 * a negative dentry, but if anybody else is
1964 * currently using the dentry or the inode
1965 * we can't do that and we fall back on removing
1966 * it from the hash queues and waiting for
1967 * it to be deleted later when it has no users
1968 */
1969
1970/**
1971 * d_delete - delete a dentry
1972 * @dentry: The dentry to delete
1973 *
1974 * Turn the dentry into a negative dentry if possible, otherwise
1975 * remove it from the hash queues so it can be deleted later
1976 */
1977
1978void d_delete(struct dentry * dentry)
1979{
Nick Piggin873feea2011-01-07 17:50:06 +11001980 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04001981 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 /*
1983 * Are we the only user?
1984 */
Nick Piggin357f8e62011-01-07 17:49:42 +11001985again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001987 inode = dentry->d_inode;
1988 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001989 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11001990 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11001991 spin_unlock(&dentry->d_lock);
1992 cpu_relax();
1993 goto again;
1994 }
Al Viro13e3c5e2010-05-21 16:11:04 -04001995 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11001996 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04001997 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001998 return;
1999 }
2000
2001 if (!d_unhashed(dentry))
2002 __d_drop(dentry);
2003
2004 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04002005
2006 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002008EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002010static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002012 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002013 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07002014 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002015 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002016 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017}
2018
David Howells770bfad2006-08-22 20:06:07 -04002019static void _d_rehash(struct dentry * entry)
2020{
2021 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2022}
2023
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024/**
2025 * d_rehash - add an entry back to the hash
2026 * @entry: dentry to add to the hash
2027 *
2028 * Adds a dentry to the hash according to its name.
2029 */
2030
2031void d_rehash(struct dentry * entry)
2032{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002034 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002037EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002039/**
2040 * dentry_update_name_case - update case insensitive dentry with a new name
2041 * @dentry: dentry to be updated
2042 * @name: new name
2043 *
2044 * Update a case insensitive dentry with new case of name.
2045 *
2046 * dentry must have been returned by d_lookup with name @name. Old and new
2047 * name lengths must match (ie. no d_compare which allows mismatched name
2048 * lengths).
2049 *
2050 * Parent inode i_mutex must be held over d_lookup and into this call (to
2051 * keep renames and concurrent inserts, and readdir(2) away).
2052 */
2053void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2054{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002055 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002056 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2057
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002058 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002059 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002060 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002061 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002062 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002063}
2064EXPORT_SYMBOL(dentry_update_name_case);
2065
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066static void switch_names(struct dentry *dentry, struct dentry *target)
2067{
2068 if (dname_external(target)) {
2069 if (dname_external(dentry)) {
2070 /*
2071 * Both external: swap the pointers
2072 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002073 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002074 } else {
2075 /*
2076 * dentry:internal, target:external. Steal target's
2077 * storage and make target internal.
2078 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002079 memcpy(target->d_iname, dentry->d_name.name,
2080 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 dentry->d_name.name = target->d_name.name;
2082 target->d_name.name = target->d_iname;
2083 }
2084 } else {
2085 if (dname_external(dentry)) {
2086 /*
2087 * dentry:external, target:internal. Give dentry's
2088 * storage to target and make dentry internal
2089 */
2090 memcpy(dentry->d_iname, target->d_name.name,
2091 target->d_name.len + 1);
2092 target->d_name.name = dentry->d_name.name;
2093 dentry->d_name.name = dentry->d_iname;
2094 } else {
2095 /*
2096 * Both are internal. Just copy target to dentry
2097 */
2098 memcpy(dentry->d_iname, target->d_name.name,
2099 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002100 dentry->d_name.len = target->d_name.len;
2101 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102 }
2103 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002104 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105}
2106
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002107static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2108{
2109 /*
2110 * XXXX: do we really need to take target->d_lock?
2111 */
2112 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2113 spin_lock(&target->d_parent->d_lock);
2114 else {
2115 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2116 spin_lock(&dentry->d_parent->d_lock);
2117 spin_lock_nested(&target->d_parent->d_lock,
2118 DENTRY_D_LOCK_NESTED);
2119 } else {
2120 spin_lock(&target->d_parent->d_lock);
2121 spin_lock_nested(&dentry->d_parent->d_lock,
2122 DENTRY_D_LOCK_NESTED);
2123 }
2124 }
2125 if (target < dentry) {
2126 spin_lock_nested(&target->d_lock, 2);
2127 spin_lock_nested(&dentry->d_lock, 3);
2128 } else {
2129 spin_lock_nested(&dentry->d_lock, 2);
2130 spin_lock_nested(&target->d_lock, 3);
2131 }
2132}
2133
2134static void dentry_unlock_parents_for_move(struct dentry *dentry,
2135 struct dentry *target)
2136{
2137 if (target->d_parent != dentry->d_parent)
2138 spin_unlock(&dentry->d_parent->d_lock);
2139 if (target->d_parent != target)
2140 spin_unlock(&target->d_parent->d_lock);
2141}
2142
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002144 * When switching names, the actual string doesn't strictly have to
2145 * be preserved in the target - because we're dropping the target
2146 * anyway. As such, we can just do a simple memcpy() to copy over
2147 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002149 * Note that we have to be a lot more careful about getting the hash
2150 * switched - we have to switch the hash value properly even if it
2151 * then no longer matches the actual (corrupted) string of the target.
2152 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002154/*
Al Viro18367502011-07-12 21:42:24 -04002155 * __d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 * @dentry: entry to move
2157 * @target: new dentry
2158 *
2159 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002160 * dcache entries should not be moved in this way. Caller must hold
2161 * rename_lock, the i_mutex of the source and target directories,
2162 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 */
Al Viro18367502011-07-12 21:42:24 -04002164static void __d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 if (!dentry->d_inode)
2167 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2168
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002169 BUG_ON(d_ancestor(dentry, target));
2170 BUG_ON(d_ancestor(target, dentry));
2171
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002172 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173
Nick Piggin31e6b012011-01-07 17:49:52 +11002174 write_seqcount_begin(&dentry->d_seq);
2175 write_seqcount_begin(&target->d_seq);
2176
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002177 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2178
2179 /*
2180 * Move the dentry to the target hash queue. Don't bother checking
2181 * for the same hash queue because of how unlikely it is.
2182 */
2183 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002184 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185
2186 /* Unhash the target: dput() will then get rid of it */
2187 __d_drop(target);
2188
Eric Dumazet5160ee62006-01-08 01:03:32 -08002189 list_del(&dentry->d_u.d_child);
2190 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191
2192 /* Switch the names.. */
2193 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002194 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195
2196 /* ... and switch the parents */
2197 if (IS_ROOT(dentry)) {
2198 dentry->d_parent = target->d_parent;
2199 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002200 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002202 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203
2204 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002205 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206 }
2207
Eric Dumazet5160ee62006-01-08 01:03:32 -08002208 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002209
Nick Piggin31e6b012011-01-07 17:49:52 +11002210 write_seqcount_end(&target->d_seq);
2211 write_seqcount_end(&dentry->d_seq);
2212
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002213 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002215 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216 spin_unlock(&dentry->d_lock);
Al Viro18367502011-07-12 21:42:24 -04002217}
2218
2219/*
2220 * d_move - move a dentry
2221 * @dentry: entry to move
2222 * @target: new dentry
2223 *
2224 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002225 * dcache entries should not be moved in this way. See the locking
2226 * requirements for __d_move.
Al Viro18367502011-07-12 21:42:24 -04002227 */
2228void d_move(struct dentry *dentry, struct dentry *target)
2229{
2230 write_seqlock(&rename_lock);
2231 __d_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002233}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002234EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002236/**
2237 * d_ancestor - search for an ancestor
2238 * @p1: ancestor dentry
2239 * @p2: child dentry
2240 *
2241 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2242 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002243 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002244struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002245{
2246 struct dentry *p;
2247
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002248 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002249 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002250 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002251 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002252 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002253}
2254
2255/*
2256 * This helper attempts to cope with remotely renamed directories
2257 *
2258 * It assumes that the caller is already holding
Al Viro18367502011-07-12 21:42:24 -04002259 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002260 *
2261 * Note: If ever the locking in lock_rename() changes, then please
2262 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002263 */
Nick Piggin873feea2011-01-07 17:50:06 +11002264static struct dentry *__d_unalias(struct inode *inode,
2265 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002266{
2267 struct mutex *m1 = NULL, *m2 = NULL;
2268 struct dentry *ret;
2269
2270 /* If alias and dentry share a parent, then no extra locks required */
2271 if (alias->d_parent == dentry->d_parent)
2272 goto out_unalias;
2273
Trond Myklebust9eaef272006-10-21 10:24:20 -07002274 /* See lock_rename() */
2275 ret = ERR_PTR(-EBUSY);
2276 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2277 goto out_err;
2278 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2279 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2280 goto out_err;
2281 m2 = &alias->d_parent->d_inode->i_mutex;
2282out_unalias:
Al Viro18367502011-07-12 21:42:24 -04002283 __d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002284 ret = alias;
2285out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002286 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002287 if (m2)
2288 mutex_unlock(m2);
2289 if (m1)
2290 mutex_unlock(m1);
2291 return ret;
2292}
2293
2294/*
David Howells770bfad2006-08-22 20:06:07 -04002295 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2296 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002297 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002298 */
2299static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2300{
2301 struct dentry *dparent, *aparent;
2302
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002303 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002304
Nick Piggin31e6b012011-01-07 17:49:52 +11002305 write_seqcount_begin(&dentry->d_seq);
2306 write_seqcount_begin(&anon->d_seq);
2307
David Howells770bfad2006-08-22 20:06:07 -04002308 dparent = dentry->d_parent;
2309 aparent = anon->d_parent;
2310
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002311 switch_names(dentry, anon);
2312 swap(dentry->d_name.hash, anon->d_name.hash);
2313
David Howells770bfad2006-08-22 20:06:07 -04002314 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2315 list_del(&dentry->d_u.d_child);
2316 if (!IS_ROOT(dentry))
2317 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2318 else
2319 INIT_LIST_HEAD(&dentry->d_u.d_child);
2320
2321 anon->d_parent = (dparent == dentry) ? anon : dparent;
2322 list_del(&anon->d_u.d_child);
2323 if (!IS_ROOT(anon))
2324 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2325 else
2326 INIT_LIST_HEAD(&anon->d_u.d_child);
2327
Nick Piggin31e6b012011-01-07 17:49:52 +11002328 write_seqcount_end(&dentry->d_seq);
2329 write_seqcount_end(&anon->d_seq);
2330
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002331 dentry_unlock_parents_for_move(anon, dentry);
2332 spin_unlock(&dentry->d_lock);
2333
2334 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002335 anon->d_flags &= ~DCACHE_DISCONNECTED;
2336}
2337
2338/**
2339 * d_materialise_unique - introduce an inode into the tree
2340 * @dentry: candidate dentry
2341 * @inode: inode to bind to the dentry, to which aliases may be attached
2342 *
2343 * Introduces an dentry into the tree, substituting an extant disconnected
Jeff Laytonc46c8872011-07-26 13:33:16 -04002344 * root directory alias in its place if there is one. Caller must hold the
2345 * i_mutex of the parent directory.
David Howells770bfad2006-08-22 20:06:07 -04002346 */
2347struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2348{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002349 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002350
2351 BUG_ON(!d_unhashed(dentry));
2352
David Howells770bfad2006-08-22 20:06:07 -04002353 if (!inode) {
2354 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002355 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002356 d_rehash(actual);
2357 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002358 }
2359
Nick Piggin873feea2011-01-07 17:50:06 +11002360 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002361
Trond Myklebust9eaef272006-10-21 10:24:20 -07002362 if (S_ISDIR(inode->i_mode)) {
2363 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002364
Trond Myklebust9eaef272006-10-21 10:24:20 -07002365 /* Does an aliased dentry already exist? */
2366 alias = __d_find_alias(inode, 0);
2367 if (alias) {
2368 actual = alias;
Al Viro18367502011-07-12 21:42:24 -04002369 write_seqlock(&rename_lock);
2370
2371 if (d_ancestor(alias, dentry)) {
2372 /* Check for loops */
2373 actual = ERR_PTR(-ELOOP);
2374 } else if (IS_ROOT(alias)) {
2375 /* Is this an anonymous mountpoint that we
2376 * could splice into our tree? */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002377 __d_materialise_dentry(dentry, alias);
Al Viro18367502011-07-12 21:42:24 -04002378 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002379 __d_drop(alias);
2380 goto found;
Al Viro18367502011-07-12 21:42:24 -04002381 } else {
2382 /* Nope, but we must(!) avoid directory
2383 * aliasing */
2384 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002385 }
Al Viro18367502011-07-12 21:42:24 -04002386 write_sequnlock(&rename_lock);
David Howellsdd179942011-08-16 15:31:30 +01002387 if (IS_ERR(actual)) {
2388 if (PTR_ERR(actual) == -ELOOP)
2389 pr_warn_ratelimited(
2390 "VFS: Lookup of '%s' in %s %s"
2391 " would have caused loop\n",
2392 dentry->d_name.name,
2393 inode->i_sb->s_type->name,
2394 inode->i_sb->s_id);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002395 dput(alias);
David Howellsdd179942011-08-16 15:31:30 +01002396 }
Trond Myklebust9eaef272006-10-21 10:24:20 -07002397 goto out_nolock;
2398 }
David Howells770bfad2006-08-22 20:06:07 -04002399 }
2400
2401 /* Add a unique reference */
2402 actual = __d_instantiate_unique(dentry, inode);
2403 if (!actual)
2404 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002405 else
2406 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002407
David Howells770bfad2006-08-22 20:06:07 -04002408 spin_lock(&actual->d_lock);
2409found:
2410 _d_rehash(actual);
2411 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002412 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002413out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002414 if (actual == dentry) {
2415 security_d_instantiate(dentry, inode);
2416 return NULL;
2417 }
2418
2419 iput(inode);
2420 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002421}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002422EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002423
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002424static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002425{
2426 *buflen -= namelen;
2427 if (*buflen < 0)
2428 return -ENAMETOOLONG;
2429 *buffer -= namelen;
2430 memcpy(*buffer, str, namelen);
2431 return 0;
2432}
2433
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002434static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2435{
2436 return prepend(buffer, buflen, name->name, name->len);
2437}
2438
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002440 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002441 * @path: the dentry/vfsmount to report
2442 * @root: root vfsmnt/dentry (may be modified by this function)
2443 * @buffer: pointer to the end of the buffer
2444 * @buflen: pointer to buffer length
2445 *
Nick Piggin949854d2011-01-07 17:49:37 +11002446 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002447 *
2448 * If path is not reachable from the supplied root, then the value of
2449 * root is changed (without modifying refcounts).
2450 */
2451static int prepend_path(const struct path *path, struct path *root,
2452 char **buffer, int *buflen)
2453{
2454 struct dentry *dentry = path->dentry;
2455 struct vfsmount *vfsmnt = path->mnt;
2456 bool slash = false;
2457 int error = 0;
2458
Nick Piggin99b7db72010-08-18 04:37:39 +10002459 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002460 while (dentry != root->dentry || vfsmnt != root->mnt) {
2461 struct dentry * parent;
2462
2463 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2464 /* Global root? */
2465 if (vfsmnt->mnt_parent == vfsmnt) {
2466 goto global_root;
2467 }
2468 dentry = vfsmnt->mnt_mountpoint;
2469 vfsmnt = vfsmnt->mnt_parent;
2470 continue;
2471 }
2472 parent = dentry->d_parent;
2473 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002474 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002475 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002476 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002477 if (!error)
2478 error = prepend(buffer, buflen, "/", 1);
2479 if (error)
2480 break;
2481
2482 slash = true;
2483 dentry = parent;
2484 }
2485
2486out:
2487 if (!error && !slash)
2488 error = prepend(buffer, buflen, "/", 1);
2489
Nick Piggin99b7db72010-08-18 04:37:39 +10002490 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002491 return error;
2492
2493global_root:
2494 /*
2495 * Filesystems needing to implement special "root names"
2496 * should do so with ->d_dname()
2497 */
2498 if (IS_ROOT(dentry) &&
2499 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2500 WARN(1, "Root dentry has weird name <%.*s>\n",
2501 (int) dentry->d_name.len, dentry->d_name.name);
2502 }
2503 root->mnt = vfsmnt;
2504 root->dentry = dentry;
2505 goto out;
2506}
2507
2508/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002509 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002510 * @path: the dentry/vfsmount to report
2511 * @root: root vfsmnt/dentry (may be modified by this function)
Randy Dunlapcd956a12010-08-14 13:05:31 -07002512 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002513 * @buflen: buffer length
2514 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002515 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002517 * Returns a pointer into the buffer or an error code if the
2518 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002519 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002520 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002521 *
2522 * If path is not reachable from the supplied root, then the value of
2523 * root is changed (without modifying refcounts).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002524 */
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002525char *__d_path(const struct path *path, struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002526 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002527{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002528 char *res = buf + buflen;
2529 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002531 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002532 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002533 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002534 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002535
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002536 if (error)
2537 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002538 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002539}
2540
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002541/*
2542 * same as __d_path but appends "(deleted)" for unlinked files.
2543 */
2544static int path_with_deleted(const struct path *path, struct path *root,
2545 char **buf, int *buflen)
2546{
2547 prepend(buf, buflen, "\0", 1);
2548 if (d_unlinked(path->dentry)) {
2549 int error = prepend(buf, buflen, " (deleted)", 10);
2550 if (error)
2551 return error;
2552 }
2553
2554 return prepend_path(path, root, buf, buflen);
2555}
2556
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002557static int prepend_unreachable(char **buffer, int *buflen)
2558{
2559 return prepend(buffer, buflen, "(unreachable)", 13);
2560}
2561
Jan Bluncka03a8a702008-02-14 19:38:32 -08002562/**
2563 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002564 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002565 * @buf: buffer to return value in
2566 * @buflen: buffer length
2567 *
2568 * Convert a dentry into an ASCII path name. If the entry has been deleted
2569 * the string " (deleted)" is appended. Note that this is ambiguous.
2570 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002571 * Returns a pointer into the buffer or an error code if the path was
2572 * too long. Note: Callers should use the returned pointer, not the passed
2573 * in buffer, to use the name! The implementation often starts at an offset
2574 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002575 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002576 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002577 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002578char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002580 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002581 struct path root;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002582 struct path tmp;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002583 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002584
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002585 /*
2586 * We have various synthetic filesystems that never get mounted. On
2587 * these filesystems dentries are never used for lookup purposes, and
2588 * thus don't need to be hashed. They also don't need a name until a
2589 * user wants to identify the object in /proc/pid/fd/. The little hack
2590 * below allows us to generate a name for these objects on demand:
2591 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002592 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2593 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002594
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002595 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002596 write_seqlock(&rename_lock);
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002597 tmp = root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002598 error = path_with_deleted(path, &tmp, &res, &buflen);
2599 if (error)
2600 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002601 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002602 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002603 return res;
2604}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002605EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002606
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002607/**
2608 * d_path_with_unreachable - return the path of a dentry
2609 * @path: path to report
2610 * @buf: buffer to return value in
2611 * @buflen: buffer length
2612 *
2613 * The difference from d_path() is that this prepends "(unreachable)"
2614 * to paths which are unreachable from the current process' root.
2615 */
2616char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2617{
2618 char *res = buf + buflen;
2619 struct path root;
2620 struct path tmp;
2621 int error;
2622
2623 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2624 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2625
2626 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002627 write_seqlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002628 tmp = root;
2629 error = path_with_deleted(path, &tmp, &res, &buflen);
2630 if (!error && !path_equal(&tmp, &root))
2631 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002632 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002633 path_put(&root);
2634 if (error)
2635 res = ERR_PTR(error);
2636
2637 return res;
2638}
2639
Linus Torvalds1da177e2005-04-16 15:20:36 -07002640/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002641 * Helper function for dentry_operations.d_dname() members
2642 */
2643char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2644 const char *fmt, ...)
2645{
2646 va_list args;
2647 char temp[64];
2648 int sz;
2649
2650 va_start(args, fmt);
2651 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2652 va_end(args);
2653
2654 if (sz > sizeof(temp) || sz > buflen)
2655 return ERR_PTR(-ENAMETOOLONG);
2656
2657 buffer += buflen - sz;
2658 return memcpy(buffer, temp, sz);
2659}
2660
2661/*
Ram Pai6092d042008-03-27 13:06:20 +01002662 * Write full pathname from the root of the filesystem into the buffer.
2663 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002664static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002665{
2666 char *end = buf + buflen;
2667 char *retval;
2668
Ram Pai6092d042008-03-27 13:06:20 +01002669 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002670 if (buflen < 1)
2671 goto Elong;
2672 /* Get '/' right */
2673 retval = end-1;
2674 *retval = '/';
2675
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002676 while (!IS_ROOT(dentry)) {
2677 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002678 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002679
Ram Pai6092d042008-03-27 13:06:20 +01002680 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002681 spin_lock(&dentry->d_lock);
2682 error = prepend_name(&end, &buflen, &dentry->d_name);
2683 spin_unlock(&dentry->d_lock);
2684 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002685 goto Elong;
2686
2687 retval = end;
2688 dentry = parent;
2689 }
Al Viroc1031352010-06-06 22:31:14 -04002690 return retval;
2691Elong:
2692 return ERR_PTR(-ENAMETOOLONG);
2693}
Nick Pigginec2447c2011-01-07 17:49:29 +11002694
2695char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2696{
2697 char *retval;
2698
Nick Piggin949854d2011-01-07 17:49:37 +11002699 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002700 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002701 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002702
2703 return retval;
2704}
2705EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002706
2707char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2708{
2709 char *p = NULL;
2710 char *retval;
2711
Nick Piggin949854d2011-01-07 17:49:37 +11002712 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002713 if (d_unlinked(dentry)) {
2714 p = buf + buflen;
2715 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2716 goto Elong;
2717 buflen++;
2718 }
2719 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002720 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002721 if (!IS_ERR(retval) && p)
2722 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002723 return retval;
2724Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002725 return ERR_PTR(-ENAMETOOLONG);
2726}
2727
2728/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002729 * NOTE! The user-level library version returns a
2730 * character pointer. The kernel system call just
2731 * returns the length of the buffer filled (which
2732 * includes the ending '\0' character), or a negative
2733 * error value. So libc would do something like
2734 *
2735 * char *getcwd(char * buf, size_t size)
2736 * {
2737 * int retval;
2738 *
2739 * retval = sys_getcwd(buf, size);
2740 * if (retval >= 0)
2741 * return buf;
2742 * errno = -retval;
2743 * return NULL;
2744 * }
2745 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002746SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747{
Linus Torvalds552ce542007-02-13 12:08:18 -08002748 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002749 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002750 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751
2752 if (!page)
2753 return -ENOMEM;
2754
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002755 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002756
Linus Torvalds552ce542007-02-13 12:08:18 -08002757 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002758 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002759 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002760 unsigned long len;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002761 struct path tmp = root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002762 char *cwd = page + PAGE_SIZE;
2763 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002764
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002765 prepend(&cwd, &buflen, "\0", 1);
2766 error = prepend_path(&pwd, &tmp, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002767 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002768
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002769 if (error)
Linus Torvalds552ce542007-02-13 12:08:18 -08002770 goto out;
2771
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002772 /* Unreachable from current root */
2773 if (!path_equal(&tmp, &root)) {
2774 error = prepend_unreachable(&cwd, &buflen);
2775 if (error)
2776 goto out;
2777 }
2778
Linus Torvalds552ce542007-02-13 12:08:18 -08002779 error = -ERANGE;
2780 len = PAGE_SIZE + page - cwd;
2781 if (len <= size) {
2782 error = len;
2783 if (copy_to_user(buf, cwd, len))
2784 error = -EFAULT;
2785 }
Nick Piggin949854d2011-01-07 17:49:37 +11002786 } else {
2787 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002788 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002789
2790out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002791 path_put(&pwd);
2792 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002793 free_page((unsigned long) page);
2794 return error;
2795}
2796
2797/*
2798 * Test whether new_dentry is a subdirectory of old_dentry.
2799 *
2800 * Trivially implemented using the dcache structure
2801 */
2802
2803/**
2804 * is_subdir - is new dentry a subdirectory of old_dentry
2805 * @new_dentry: new dentry
2806 * @old_dentry: old dentry
2807 *
2808 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2809 * Returns 0 otherwise.
2810 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2811 */
2812
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002813int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002814{
2815 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002816 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002817
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002818 if (new_dentry == old_dentry)
2819 return 1;
2820
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002821 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002822 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002824 /*
2825 * Need rcu_readlock to protect against the d_parent trashing
2826 * due to d_move
2827 */
2828 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002829 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002830 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002831 else
2832 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002833 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002834 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002835
2836 return result;
2837}
2838
Al Viro2096f752010-01-30 13:16:21 -05002839int path_is_under(struct path *path1, struct path *path2)
2840{
2841 struct vfsmount *mnt = path1->mnt;
2842 struct dentry *dentry = path1->dentry;
2843 int res;
Nick Piggin99b7db72010-08-18 04:37:39 +10002844
2845 br_read_lock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002846 if (mnt != path2->mnt) {
2847 for (;;) {
2848 if (mnt->mnt_parent == mnt) {
Nick Piggin99b7db72010-08-18 04:37:39 +10002849 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002850 return 0;
2851 }
2852 if (mnt->mnt_parent == path2->mnt)
2853 break;
2854 mnt = mnt->mnt_parent;
2855 }
2856 dentry = mnt->mnt_mountpoint;
2857 }
2858 res = is_subdir(dentry, path2->dentry);
Nick Piggin99b7db72010-08-18 04:37:39 +10002859 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002860 return res;
2861}
2862EXPORT_SYMBOL(path_is_under);
2863
Linus Torvalds1da177e2005-04-16 15:20:36 -07002864void d_genocide(struct dentry *root)
2865{
Nick Piggin949854d2011-01-07 17:49:37 +11002866 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002868 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002869 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002870
Nick Piggin949854d2011-01-07 17:49:37 +11002871 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002872again:
2873 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002874 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002875repeat:
2876 next = this_parent->d_subdirs.next;
2877resume:
2878 while (next != &this_parent->d_subdirs) {
2879 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002880 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002881 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002882
Nick Pigginda502952011-01-07 17:49:33 +11002883 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2884 if (d_unhashed(dentry) || !dentry->d_inode) {
2885 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002886 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002887 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002888 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002889 spin_unlock(&this_parent->d_lock);
2890 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002891 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002892 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002893 goto repeat;
2894 }
Nick Piggin949854d2011-01-07 17:49:37 +11002895 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2896 dentry->d_flags |= DCACHE_GENOCIDE;
2897 dentry->d_count--;
2898 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002899 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002900 }
2901 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002902 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002903 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2904 this_parent->d_flags |= DCACHE_GENOCIDE;
2905 this_parent->d_count--;
2906 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002907 this_parent = try_to_ascend(this_parent, locked, seq);
2908 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002909 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002910 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002911 goto resume;
2912 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002913 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002914 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002915 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002916 if (locked)
2917 write_sequnlock(&rename_lock);
2918 return;
2919
2920rename_retry:
2921 locked = 1;
2922 write_seqlock(&rename_lock);
2923 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002924}
2925
2926/**
2927 * find_inode_number - check for dentry with name
2928 * @dir: directory to check
2929 * @name: Name to find.
2930 *
2931 * Check whether a dentry already exists for the given name,
2932 * and return the inode number if it has an inode. Otherwise
2933 * 0 is returned.
2934 *
2935 * This routine is used to post-process directory listings for
2936 * filesystems using synthetic inode numbers, and is necessary
2937 * to keep getcwd() working.
2938 */
2939
2940ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2941{
2942 struct dentry * dentry;
2943 ino_t ino = 0;
2944
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002945 dentry = d_hash_and_lookup(dir, name);
2946 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002947 if (dentry->d_inode)
2948 ino = dentry->d_inode->i_ino;
2949 dput(dentry);
2950 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002951 return ino;
2952}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002953EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002954
2955static __initdata unsigned long dhash_entries;
2956static int __init set_dhash_entries(char *str)
2957{
2958 if (!str)
2959 return 0;
2960 dhash_entries = simple_strtoul(str, &str, 0);
2961 return 1;
2962}
2963__setup("dhash_entries=", set_dhash_entries);
2964
2965static void __init dcache_init_early(void)
2966{
2967 int loop;
2968
2969 /* If hashes are distributed across NUMA nodes, defer
2970 * hash allocation until vmalloc space is available.
2971 */
2972 if (hashdist)
2973 return;
2974
2975 dentry_hashtable =
2976 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002977 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978 dhash_entries,
2979 13,
2980 HASH_EARLY,
2981 &d_hash_shift,
2982 &d_hash_mask,
2983 0);
2984
2985 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002986 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002987}
2988
Denis Cheng74bf17c2007-10-16 23:26:30 -07002989static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002990{
2991 int loop;
2992
2993 /*
2994 * A constructor could be added for stable state like the lists,
2995 * but it is probably not worth it because of the cache nature
2996 * of the dcache.
2997 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07002998 dentry_cache = KMEM_CACHE(dentry,
2999 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003000
3001 /* Hash may have been set up in dcache_init_early */
3002 if (!hashdist)
3003 return;
3004
3005 dentry_hashtable =
3006 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003007 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003008 dhash_entries,
3009 13,
3010 0,
3011 &d_hash_shift,
3012 &d_hash_mask,
3013 0);
3014
3015 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003016 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003017}
3018
3019/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08003020struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003021EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003022
Linus Torvalds1da177e2005-04-16 15:20:36 -07003023EXPORT_SYMBOL(d_genocide);
3024
Linus Torvalds1da177e2005-04-16 15:20:36 -07003025void __init vfs_caches_init_early(void)
3026{
3027 dcache_init_early();
3028 inode_init_early();
3029}
3030
3031void __init vfs_caches_init(unsigned long mempages)
3032{
3033 unsigned long reserve;
3034
3035 /* Base hash sizes on available memory, with a reserve equal to
3036 150% of current kernel size */
3037
3038 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3039 mempages -= reserve;
3040
3041 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003042 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003043
Denis Cheng74bf17c2007-10-16 23:26:30 -07003044 dcache_init();
3045 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003046 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003047 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003048 bdev_cache_init();
3049 chrdev_init();
3050}