blob: 22a0ef41bad1b1cd17fc6ce84023d52f65096ba5 [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>
David Howells07f3f05c2006-09-30 20:52:18 +020038#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
Nick Piggin789680d2011-01-07 17:49:30 +110040/*
41 * Usage:
Nick Piggin873feea2011-01-07 17:50:06 +110042 * dcache->d_inode->i_lock protects:
43 * - i_dentry, d_alias, d_inode of aliases
Nick Pigginceb5bdc2011-01-07 17:50:05 +110044 * dcache_hash_bucket lock protects:
45 * - the dcache hash table
46 * s_anon bl list spinlock protects:
47 * - the s_anon list (see __d_drop)
Nick Piggin23044502011-01-07 17:49:31 +110048 * dcache_lru_lock protects:
49 * - the dcache lru lists and counters
50 * d_lock protects:
51 * - d_flags
52 * - d_name
53 * - d_lru
Nick Pigginb7ab39f2011-01-07 17:49:32 +110054 * - d_count
Nick Pigginda502952011-01-07 17:49:33 +110055 * - d_unhashed()
Nick Piggin2fd6b7f2011-01-07 17:49:34 +110056 * - d_parent and d_subdirs
57 * - childrens' d_child and d_parent
Nick Pigginb23fb0a2011-01-07 17:49:35 +110058 * - d_alias, d_inode
Nick Piggin789680d2011-01-07 17:49:30 +110059 *
60 * Ordering:
Nick Piggin873feea2011-01-07 17:50:06 +110061 * dentry->d_inode->i_lock
Nick Pigginb5c84bf2011-01-07 17:49:38 +110062 * dentry->d_lock
63 * dcache_lru_lock
Nick Pigginceb5bdc2011-01-07 17:50:05 +110064 * dcache_hash_bucket lock
65 * s_anon lock
Nick Piggin789680d2011-01-07 17:49:30 +110066 *
Nick Pigginda502952011-01-07 17:49:33 +110067 * If there is an ancestor relationship:
68 * dentry->d_parent->...->d_parent->d_lock
69 * ...
70 * dentry->d_parent->d_lock
71 * dentry->d_lock
72 *
73 * If no ancestor relationship:
Nick Piggin789680d2011-01-07 17:49:30 +110074 * if (dentry1 < dentry2)
75 * dentry1->d_lock
76 * dentry2->d_lock
77 */
Eric Dumazetfa3536c2006-03-26 01:37:24 -080078int sysctl_vfs_cache_pressure __read_mostly = 100;
Linus Torvalds1da177e2005-04-16 15:20:36 -070079EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
80
Nick Piggin23044502011-01-07 17:49:31 +110081static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
Al Viro74c3cbe2007-07-22 08:04:18 -040082__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
Nick Piggin949854d2011-01-07 17:49:37 +110084EXPORT_SYMBOL(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
Christoph Lametere18b8902006-12-06 20:33:20 -080086static struct kmem_cache *dentry_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
Linus Torvalds1da177e2005-04-16 15:20:36 -070088/*
89 * This is the single most critical data structure when it comes
90 * to the dcache: the hashtable for lookups. Somebody should try
91 * to make this good - I've just made it work.
92 *
93 * This hash-function tries to avoid losing too many bits of hash
94 * information, yet avoid using a prime hash-size or similar.
95 */
96#define D_HASHBITS d_hash_shift
97#define D_HASHMASK d_hash_mask
98
Eric Dumazetfa3536c2006-03-26 01:37:24 -080099static unsigned int d_hash_mask __read_mostly;
100static unsigned int d_hash_shift __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100101
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700102static struct hlist_bl_head *dentry_hashtable __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100103
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700104static inline struct hlist_bl_head *d_hash(struct dentry *parent,
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100105 unsigned long hash)
106{
107 hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
108 hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
109 return dentry_hashtable + (hash & D_HASHMASK);
110}
111
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112/* Statistics gathering. */
113struct dentry_stat_t dentry_stat = {
114 .age_limit = 45,
115};
116
Nick Piggin3e880fb2011-01-07 17:49:19 +1100117static DEFINE_PER_CPU(unsigned int, nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400118
119#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Nick Piggin3e880fb2011-01-07 17:49:19 +1100120static int get_nr_dentry(void)
121{
122 int i;
123 int sum = 0;
124 for_each_possible_cpu(i)
125 sum += per_cpu(nr_dentry, i);
126 return sum < 0 ? 0 : sum;
127}
128
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400129int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
130 size_t *lenp, loff_t *ppos)
131{
Nick Piggin3e880fb2011-01-07 17:49:19 +1100132 dentry_stat.nr_dentry = get_nr_dentry();
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400133 return proc_dointvec(table, write, buffer, lenp, ppos);
134}
135#endif
136
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400137static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400139 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
140
Arjan van de Venfd217f42008-10-21 06:47:33 -0700141 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 if (dname_external(dentry))
143 kfree(dentry->d_name.name);
144 kmem_cache_free(dentry_cache, dentry);
145}
146
147/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100148 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 */
150static void d_free(struct dentry *dentry)
151{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100152 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100153 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 if (dentry->d_op && dentry->d_op->d_release)
155 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400156
Linus Torvaldsdea36672011-04-24 07:58:46 -0700157 /* if dentry was never visible to RCU, immediate free is OK */
158 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400159 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800160 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400161 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162}
163
Nick Piggin31e6b012011-01-07 17:49:52 +1100164/**
165 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800166 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100167 * After this call, in-progress rcu-walk path lookup will fail. This
168 * should be called after unhashing, and after changing d_inode (if
169 * the dentry has not already been unhashed).
170 */
171static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
172{
173 assert_spin_locked(&dentry->d_lock);
174 /* Go through a barrier */
175 write_seqcount_barrier(&dentry->d_seq);
176}
177
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178/*
179 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100180 * d_iput() operation if defined. Dentry has no refcount
181 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800183static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200184 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100185 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186{
187 struct inode *inode = dentry->d_inode;
188 if (inode) {
189 dentry->d_inode = NULL;
190 list_del_init(&dentry->d_alias);
191 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100192 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700193 if (!inode->i_nlink)
194 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 if (dentry->d_op && dentry->d_op->d_iput)
196 dentry->d_op->d_iput(dentry, inode);
197 else
198 iput(inode);
199 } else {
200 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 }
202}
203
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700204/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100205 * Release the dentry's inode, using the filesystem
206 * d_iput() operation if defined. dentry remains in-use.
207 */
208static void dentry_unlink_inode(struct dentry * dentry)
209 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100210 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100211{
212 struct inode *inode = dentry->d_inode;
213 dentry->d_inode = NULL;
214 list_del_init(&dentry->d_alias);
215 dentry_rcuwalk_barrier(dentry);
216 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100217 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100218 if (!inode->i_nlink)
219 fsnotify_inoderemove(inode);
220 if (dentry->d_op && dentry->d_op->d_iput)
221 dentry->d_op->d_iput(dentry, inode);
222 else
223 iput(inode);
224}
225
226/*
Nick Piggin23044502011-01-07 17:49:31 +1100227 * dentry_lru_(add|del|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700228 */
229static void dentry_lru_add(struct dentry *dentry)
230{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400231 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100232 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400233 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
234 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100235 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100236 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400237 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700238}
239
Nick Piggin23044502011-01-07 17:49:31 +1100240static void __dentry_lru_del(struct dentry *dentry)
241{
242 list_del_init(&dentry->d_lru);
243 dentry->d_sb->s_nr_dentry_unused--;
244 dentry_stat.nr_unused--;
245}
246
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700247static void dentry_lru_del(struct dentry *dentry)
248{
249 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100250 spin_lock(&dcache_lru_lock);
251 __dentry_lru_del(dentry);
252 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700253 }
254}
255
Christoph Hellwiga4633352010-10-10 05:36:26 -0400256static void dentry_lru_move_tail(struct dentry *dentry)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700257{
Nick Piggin23044502011-01-07 17:49:31 +1100258 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400259 if (list_empty(&dentry->d_lru)) {
260 list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
261 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100262 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400263 } else {
264 list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700265 }
Nick Piggin23044502011-01-07 17:49:31 +1100266 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700267}
268
Miklos Szeredid52b9082007-05-08 00:23:46 -0700269/**
270 * d_kill - kill dentry and return parent
271 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800272 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700273 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200274 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700275 *
276 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100277 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100278 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
279 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700280 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100281static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200282 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100283 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100284 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700285{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700286 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400287 /*
288 * Inform try_to_ascend() that we are no longer attached to the
289 * dentry tree
290 */
291 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100292 if (parent)
293 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700294 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100295 /*
296 * dentry_iput drops the locks, at which point nobody (except
297 * transient RCU lookups) can reach this dentry.
298 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700299 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900300 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700301}
302
Nick Piggin789680d2011-01-07 17:49:30 +1100303/**
304 * d_drop - drop a dentry
305 * @dentry: dentry to drop
306 *
307 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
308 * be found through a VFS lookup any more. Note that this is different from
309 * deleting the dentry - d_delete will try to mark the dentry negative if
310 * possible, giving a successful _negative_ lookup, while d_drop will
311 * just make the cache lookup fail.
312 *
313 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
314 * reason (NFS timeouts or autofs deletes).
315 *
316 * __d_drop requires dentry->d_lock.
317 */
318void __d_drop(struct dentry *dentry)
319{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700320 if (!d_unhashed(dentry)) {
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700321 struct hlist_bl_head *b;
Linus Torvaldsdea36672011-04-24 07:58:46 -0700322 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700323 b = &dentry->d_sb->s_anon;
Linus Torvaldsdea36672011-04-24 07:58:46 -0700324 else
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100325 b = d_hash(dentry->d_parent, dentry->d_name.hash);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700326
Christoph Hellwig1879fd62011-04-25 14:01:36 -0400327 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700328 __hlist_bl_del(&dentry->d_hash);
329 dentry->d_hash.pprev = NULL;
Christoph Hellwig1879fd62011-04-25 14:01:36 -0400330 hlist_bl_unlock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700331
332 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100333 }
334}
335EXPORT_SYMBOL(__d_drop);
336
337void d_drop(struct dentry *dentry)
338{
Nick Piggin789680d2011-01-07 17:49:30 +1100339 spin_lock(&dentry->d_lock);
340 __d_drop(dentry);
341 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100342}
343EXPORT_SYMBOL(d_drop);
344
Nick Piggin77812a12011-01-07 17:49:48 +1100345/*
346 * Finish off a dentry we've decided to kill.
347 * dentry->d_lock must be held, returns with it unlocked.
348 * If ref is non-zero, then decrement the refcount too.
349 * Returns dentry requiring refcount drop, or NULL if we're done.
350 */
351static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
352 __releases(dentry->d_lock)
353{
Nick Piggin873feea2011-01-07 17:50:06 +1100354 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100355 struct dentry *parent;
356
Nick Piggin873feea2011-01-07 17:50:06 +1100357 inode = dentry->d_inode;
358 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100359relock:
360 spin_unlock(&dentry->d_lock);
361 cpu_relax();
362 return dentry; /* try again with same dentry */
363 }
364 if (IS_ROOT(dentry))
365 parent = NULL;
366 else
367 parent = dentry->d_parent;
368 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100369 if (inode)
370 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100371 goto relock;
372 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100373
Nick Piggin77812a12011-01-07 17:49:48 +1100374 if (ref)
375 dentry->d_count--;
376 /* if dentry was on the d_lru list delete it from there */
377 dentry_lru_del(dentry);
378 /* if it was on the hash then remove it */
379 __d_drop(dentry);
380 return d_kill(dentry, parent);
381}
382
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383/*
384 * This is dput
385 *
386 * This is complicated by the fact that we do not want to put
387 * dentries that are no longer on any hash chain on the unused
388 * list: we'd much rather just get rid of them immediately.
389 *
390 * However, that implies that we have to traverse the dentry
391 * tree upwards to the parents which might _also_ now be
392 * scheduled for deletion (it may have been only waiting for
393 * its last child to go away).
394 *
395 * This tail recursion is done by hand as we don't want to depend
396 * on the compiler to always get this right (gcc generally doesn't).
397 * Real recursion would eat up our stack space.
398 */
399
400/*
401 * dput - release a dentry
402 * @dentry: dentry to release
403 *
404 * Release a dentry. This will drop the usage count and if appropriate
405 * call the dentry unlink method as well as removing it from the queues and
406 * releasing its resources. If the parent dentries were scheduled for release
407 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409void dput(struct dentry *dentry)
410{
411 if (!dentry)
412 return;
413
414repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100415 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100418 BUG_ON(!dentry->d_count);
419 if (dentry->d_count > 1) {
420 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 return;
423 }
424
Nick Pigginfb045ad2011-01-07 17:49:55 +1100425 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100427 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 }
Nick Piggin265ac902010-10-10 05:36:24 -0400429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 /* Unreachable? Get rid of it */
431 if (d_unhashed(dentry))
432 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400433
434 /* Otherwise leave it cached and ensure it's on the LRU */
435 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400436 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400437
Nick Piggin61f3dee2011-01-07 17:49:40 +1100438 dentry->d_count--;
439 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 return;
441
Miklos Szeredid52b9082007-05-08 00:23:46 -0700442kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100443 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700444 if (dentry)
445 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700447EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
449/**
450 * d_invalidate - invalidate a dentry
451 * @dentry: dentry to invalidate
452 *
453 * Try to invalidate the dentry if it turns out to be
454 * possible. If there are other dentries that can be
455 * reached through this one we can't delete it and we
456 * return -EBUSY. On success we return 0.
457 *
458 * no dcache lock.
459 */
460
461int d_invalidate(struct dentry * dentry)
462{
463 /*
464 * If it's already been dropped, return OK.
465 */
Nick Pigginda502952011-01-07 17:49:33 +1100466 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100468 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 return 0;
470 }
471 /*
472 * Check whether to do a partial shrink_dcache
473 * to get rid of unused child entries.
474 */
475 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100476 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100478 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 }
480
481 /*
482 * Somebody else still using it?
483 *
484 * If it's a directory, we can't drop it
485 * for fear of somebody re-populating it
486 * with children (even though dropping it
487 * would make it unreachable from the root,
488 * we might still populate it if it was a
489 * working directory or similar).
490 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100491 if (dentry->d_count > 1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) {
493 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 return -EBUSY;
495 }
496 }
497
498 __d_drop(dentry);
499 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 return 0;
501}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700502EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100504/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100505static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100507 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508}
509
Nick Piggindc0474b2011-01-07 17:49:43 +1100510static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100511{
Nick Piggin23044502011-01-07 17:49:31 +1100512 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100513 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100514 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100515}
516
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100517struct dentry *dget_parent(struct dentry *dentry)
518{
519 struct dentry *ret;
520
521repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100522 /*
523 * Don't need rcu_dereference because we re-check it was correct under
524 * the lock.
525 */
526 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100527 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100528 if (!ret) {
529 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100530 goto out;
531 }
Nick Piggina734eb42011-01-07 17:49:44 +1100532 spin_lock(&ret->d_lock);
533 if (unlikely(ret != dentry->d_parent)) {
534 spin_unlock(&ret->d_lock);
535 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100536 goto repeat;
537 }
Nick Piggina734eb42011-01-07 17:49:44 +1100538 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100539 BUG_ON(!ret->d_count);
540 ret->d_count++;
541 spin_unlock(&ret->d_lock);
542out:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100543 return ret;
544}
545EXPORT_SYMBOL(dget_parent);
546
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547/**
548 * d_find_alias - grab a hashed alias of inode
549 * @inode: inode in question
550 * @want_discon: flag, used by d_splice_alias, to request
551 * that only a DISCONNECTED alias be returned.
552 *
553 * If inode has a hashed alias, or is a directory and has any alias,
554 * acquire the reference to alias and return it. Otherwise return NULL.
555 * Notice that if inode is a directory there can be only one alias and
556 * it can be unhashed only if it has no children, or if it is the root
557 * of a filesystem.
558 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700559 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700561 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 */
Nick Pigginda502952011-01-07 17:49:33 +1100563static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564{
Nick Pigginda502952011-01-07 17:49:33 +1100565 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566
Nick Pigginda502952011-01-07 17:49:33 +1100567again:
568 discon_alias = NULL;
569 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
570 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700572 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100573 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100575 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100576 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100577 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 return alias;
579 }
580 }
Nick Pigginda502952011-01-07 17:49:33 +1100581 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 }
Nick Pigginda502952011-01-07 17:49:33 +1100583 if (discon_alias) {
584 alias = discon_alias;
585 spin_lock(&alias->d_lock);
586 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
587 if (IS_ROOT(alias) &&
588 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100589 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100590 spin_unlock(&alias->d_lock);
591 return alias;
592 }
593 }
594 spin_unlock(&alias->d_lock);
595 goto again;
596 }
597 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598}
599
Nick Pigginda502952011-01-07 17:49:33 +1100600struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601{
David Howells214fda12006-03-25 03:06:36 -0800602 struct dentry *de = NULL;
603
604 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100605 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800606 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100607 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800608 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 return de;
610}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700611EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612
613/*
614 * Try to kill dentries associated with this inode.
615 * WARNING: you must own a reference to inode.
616 */
617void d_prune_aliases(struct inode *inode)
618{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700619 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100621 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700622 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100624 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100625 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626 __d_drop(dentry);
627 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100628 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 dput(dentry);
630 goto restart;
631 }
632 spin_unlock(&dentry->d_lock);
633 }
Nick Piggin873feea2011-01-07 17:50:06 +1100634 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700636EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
638/*
Nick Piggin77812a12011-01-07 17:49:48 +1100639 * Try to throw away a dentry - free the inode, dput the parent.
640 * Requires dentry->d_lock is held, and dentry->d_count == 0.
641 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700642 *
Nick Piggin77812a12011-01-07 17:49:48 +1100643 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 */
Nick Piggin77812a12011-01-07 17:49:48 +1100645static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200646 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647{
Nick Piggin77812a12011-01-07 17:49:48 +1100648 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700649
Nick Piggin77812a12011-01-07 17:49:48 +1100650 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700651 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100652 * If dentry_kill returns NULL, we have nothing more to do.
653 * if it returns the same dentry, trylocks failed. In either
654 * case, just loop again.
655 *
656 * Otherwise, we need to prune ancestors too. This is necessary
657 * to prevent quadratic behavior of shrink_dcache_parent(), but
658 * is also expected to be beneficial in reducing dentry cache
659 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700660 */
Nick Piggin77812a12011-01-07 17:49:48 +1100661 if (!parent)
662 return;
663 if (parent == dentry)
664 return;
665
666 /* Prune ancestors. */
667 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700668 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100669 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100670 if (dentry->d_count > 1) {
671 dentry->d_count--;
672 spin_unlock(&dentry->d_lock);
673 return;
674 }
Nick Piggin77812a12011-01-07 17:49:48 +1100675 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700676 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677}
678
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400679static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700681 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700682
Nick Pigginec336792011-01-07 17:49:47 +1100683 rcu_read_lock();
684 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100685 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
686 if (&dentry->d_lru == list)
687 break; /* empty */
688 spin_lock(&dentry->d_lock);
689 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
690 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100691 continue;
692 }
693
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 /*
695 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700696 * the LRU because of laziness during lookup. Do not free
697 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100699 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100700 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700701 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 continue;
703 }
Nick Pigginec336792011-01-07 17:49:47 +1100704
Nick Pigginec336792011-01-07 17:49:47 +1100705 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100706
707 try_prune_one_dentry(dentry);
708
Nick Pigginec336792011-01-07 17:49:47 +1100709 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 }
Nick Pigginec336792011-01-07 17:49:47 +1100711 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400712}
713
714/**
715 * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
716 * @sb: superblock to shrink dentry LRU.
717 * @count: number of entries to prune
718 * @flags: flags to control the dentry processing
719 *
720 * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
721 */
722static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
723{
724 /* called from prune_dcache() and shrink_dcache_parent() */
725 struct dentry *dentry;
726 LIST_HEAD(referenced);
727 LIST_HEAD(tmp);
728 int cnt = *count;
729
Nick Piggin23044502011-01-07 17:49:31 +1100730relock:
731 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400732 while (!list_empty(&sb->s_dentry_lru)) {
733 dentry = list_entry(sb->s_dentry_lru.prev,
734 struct dentry, d_lru);
735 BUG_ON(dentry->d_sb != sb);
736
Nick Piggin23044502011-01-07 17:49:31 +1100737 if (!spin_trylock(&dentry->d_lock)) {
738 spin_unlock(&dcache_lru_lock);
739 cpu_relax();
740 goto relock;
741 }
742
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400743 /*
744 * If we are honouring the DCACHE_REFERENCED flag and the
745 * dentry has this flag set, don't free it. Clear the flag
746 * and put it back on the LRU.
747 */
Nick Piggin23044502011-01-07 17:49:31 +1100748 if (flags & DCACHE_REFERENCED &&
749 dentry->d_flags & DCACHE_REFERENCED) {
750 dentry->d_flags &= ~DCACHE_REFERENCED;
751 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400752 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100753 } else {
754 list_move_tail(&dentry->d_lru, &tmp);
755 spin_unlock(&dentry->d_lock);
756 if (!--cnt)
757 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400758 }
Nick Pigginec336792011-01-07 17:49:47 +1100759 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400760 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700761 if (!list_empty(&referenced))
762 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100763 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100764
765 shrink_dentry_list(&tmp);
766
767 *count = cnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768}
769
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700770/**
771 * prune_dcache - shrink the dcache
772 * @count: number of entries to try to free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 *
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700774 * Shrink the dcache. This is done when we need more memory, or simply when we
775 * need to unmount something (at which point we need to unuse all dentries).
776 *
777 * This function may fail to free any resources if all the dentries are in use.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 */
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700779static void prune_dcache(int count)
780{
Al Virodca33252010-07-25 02:31:46 +0400781 struct super_block *sb, *p = NULL;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700782 int w_count;
Nick Piggin86c87492011-01-07 17:49:18 +1100783 int unused = dentry_stat.nr_unused;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700784 int prune_ratio;
785 int pruned;
786
787 if (unused == 0 || count == 0)
788 return;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700789 if (count >= unused)
790 prune_ratio = 1;
791 else
792 prune_ratio = unused / count;
793 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400794 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400795 if (list_empty(&sb->s_instances))
796 continue;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700797 if (sb->s_nr_dentry_unused == 0)
798 continue;
799 sb->s_count++;
800 /* Now, we reclaim unused dentrins with fairness.
801 * We reclaim them same percentage from each superblock.
802 * We calculate number of dentries to scan on this sb
803 * as follows, but the implementation is arranged to avoid
804 * overflows:
805 * number of dentries to scan on this sb =
806 * count * (number of dentries on this sb /
807 * number of dentries in the machine)
808 */
809 spin_unlock(&sb_lock);
810 if (prune_ratio != 1)
811 w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1;
812 else
813 w_count = sb->s_nr_dentry_unused;
814 pruned = w_count;
815 /*
816 * We need to be sure this filesystem isn't being unmounted,
817 * otherwise we could race with generic_shutdown_super(), and
818 * end up holding a reference to an inode while the filesystem
819 * is unmounted. So we try to get s_umount, and make sure
820 * s_root isn't NULL.
821 */
822 if (down_read_trylock(&sb->s_umount)) {
823 if ((sb->s_root != NULL) &&
824 (!list_empty(&sb->s_dentry_lru))) {
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700825 __shrink_dcache_sb(sb, &w_count,
826 DCACHE_REFERENCED);
827 pruned -= w_count;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700828 }
829 up_read(&sb->s_umount);
830 }
831 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400832 if (p)
833 __put_super(p);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700834 count -= pruned;
Al Virodca33252010-07-25 02:31:46 +0400835 p = sb;
Al Viro79893c12010-03-22 20:27:55 -0400836 /* more work left to do? */
837 if (count <= 0)
838 break;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700839 }
Al Virodca33252010-07-25 02:31:46 +0400840 if (p)
841 __put_super(p);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700842 spin_unlock(&sb_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700843}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844
845/**
846 * shrink_dcache_sb - shrink dcache for a superblock
847 * @sb: superblock
848 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400849 * Shrink the dcache for the specified super block. This is used to free
850 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400852void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400854 LIST_HEAD(tmp);
855
Nick Piggin23044502011-01-07 17:49:31 +1100856 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400857 while (!list_empty(&sb->s_dentry_lru)) {
858 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100859 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400860 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100861 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400862 }
Nick Piggin23044502011-01-07 17:49:31 +1100863 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700865EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866
867/*
David Howellsc636ebd2006-10-11 01:22:19 -0700868 * destroy a single subtree of dentries for unmount
869 * - see the comments on shrink_dcache_for_umount() for a description of the
870 * locking
871 */
872static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
873{
874 struct dentry *parent;
David Howellsf8713572006-10-28 10:38:46 -0700875 unsigned detached = 0;
David Howellsc636ebd2006-10-11 01:22:19 -0700876
877 BUG_ON(!IS_ROOT(dentry));
878
879 /* detach this root from the system */
Nick Piggin23044502011-01-07 17:49:31 +1100880 spin_lock(&dentry->d_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400881 dentry_lru_del(dentry);
David Howellsc636ebd2006-10-11 01:22:19 -0700882 __d_drop(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100883 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700884
885 for (;;) {
886 /* descend to the first leaf in the current subtree */
887 while (!list_empty(&dentry->d_subdirs)) {
888 struct dentry *loop;
889
890 /* this is a branch with children - detach all of them
891 * from the system in one go */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100892 spin_lock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700893 list_for_each_entry(loop, &dentry->d_subdirs,
894 d_u.d_child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100895 spin_lock_nested(&loop->d_lock,
896 DENTRY_D_LOCK_NESTED);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400897 dentry_lru_del(loop);
David Howellsc636ebd2006-10-11 01:22:19 -0700898 __d_drop(loop);
Nick Pigginda502952011-01-07 17:49:33 +1100899 spin_unlock(&loop->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700900 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100901 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700902
903 /* move to the first child */
904 dentry = list_entry(dentry->d_subdirs.next,
905 struct dentry, d_u.d_child);
906 }
907
908 /* consume the dentries from this leaf up through its parents
909 * until we find one with children or run out altogether */
910 do {
911 struct inode *inode;
912
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100913 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700914 printk(KERN_ERR
915 "BUG: Dentry %p{i=%lx,n=%s}"
916 " still in use (%d)"
917 " [unmount of %s %s]\n",
918 dentry,
919 dentry->d_inode ?
920 dentry->d_inode->i_ino : 0UL,
921 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100922 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700923 dentry->d_sb->s_type->name,
924 dentry->d_sb->s_id);
925 BUG();
926 }
927
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100928 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700929 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100930 list_del(&dentry->d_u.d_child);
931 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900932 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100933 spin_lock(&parent->d_lock);
934 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100935 list_del(&dentry->d_u.d_child);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100936 spin_unlock(&parent->d_lock);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900937 }
David Howellsc636ebd2006-10-11 01:22:19 -0700938
David Howellsf8713572006-10-28 10:38:46 -0700939 detached++;
David Howellsc636ebd2006-10-11 01:22:19 -0700940
941 inode = dentry->d_inode;
942 if (inode) {
943 dentry->d_inode = NULL;
944 list_del_init(&dentry->d_alias);
945 if (dentry->d_op && dentry->d_op->d_iput)
946 dentry->d_op->d_iput(dentry, inode);
947 else
948 iput(inode);
949 }
950
951 d_free(dentry);
952
953 /* finished when we fall off the top of the tree,
954 * otherwise we ascend to the parent and move to the
955 * next sibling if there is one */
956 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400957 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700958 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700959 } while (list_empty(&dentry->d_subdirs));
960
961 dentry = list_entry(dentry->d_subdirs.next,
962 struct dentry, d_u.d_child);
963 }
964}
965
966/*
967 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100968 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700969 * - the superblock is detached from all mountings and open files, so the
970 * dentry trees will not be rearranged by the VFS
971 * - s_umount is write-locked, so the memory pressure shrinker will ignore
972 * any dentries belonging to this superblock that it comes across
973 * - the filesystem itself is no longer permitted to rearrange the dentries
974 * in this superblock
975 */
976void shrink_dcache_for_umount(struct super_block *sb)
977{
978 struct dentry *dentry;
979
980 if (down_read_trylock(&sb->s_umount))
981 BUG();
982
983 dentry = sb->s_root;
984 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100985 spin_lock(&dentry->d_lock);
986 dentry->d_count--;
987 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700988 shrink_dcache_for_umount_subtree(dentry);
989
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100990 while (!hlist_bl_empty(&sb->s_anon)) {
991 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700992 shrink_dcache_for_umount_subtree(dentry);
993 }
994}
995
996/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700997 * This tries to ascend one level of parenthood, but
998 * we can race with renaming, so we need to re-check
999 * the parenthood after dropping the lock and check
1000 * that the sequence number still matches.
1001 */
1002static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
1003{
1004 struct dentry *new = old->d_parent;
1005
1006 rcu_read_lock();
1007 spin_unlock(&old->d_lock);
1008 spin_lock(&new->d_lock);
1009
1010 /*
1011 * might go back up the wrong parent if we have had a rename
1012 * or deletion
1013 */
1014 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -04001015 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001016 (!locked && read_seqretry(&rename_lock, seq))) {
1017 spin_unlock(&new->d_lock);
1018 new = NULL;
1019 }
1020 rcu_read_unlock();
1021 return new;
1022}
1023
1024
1025/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 * Search for at least 1 mount point in the dentry's subdirs.
1027 * We descend to the next level whenever the d_subdirs
1028 * list is non-empty and continue searching.
1029 */
1030
1031/**
1032 * have_submounts - check for mounts over a dentry
1033 * @parent: dentry to check.
1034 *
1035 * Return true if the parent or its subdirectories contain
1036 * a mount point
1037 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038int have_submounts(struct dentry *parent)
1039{
Nick Piggin949854d2011-01-07 17:49:37 +11001040 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001042 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11001043 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001044
Nick Piggin949854d2011-01-07 17:49:37 +11001045 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001046again:
1047 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 if (d_mountpoint(parent))
1050 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001051 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052repeat:
1053 next = this_parent->d_subdirs.next;
1054resume:
1055 while (next != &this_parent->d_subdirs) {
1056 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001057 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001059
1060 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001062 if (d_mountpoint(dentry)) {
1063 spin_unlock(&dentry->d_lock);
1064 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001066 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001068 spin_unlock(&this_parent->d_lock);
1069 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001071 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 goto repeat;
1073 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001074 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 }
1076 /*
1077 * All done at this level ... ascend and resume the search.
1078 */
1079 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001080 struct dentry *child = this_parent;
1081 this_parent = try_to_ascend(this_parent, locked, seq);
1082 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001083 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001084 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 goto resume;
1086 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001087 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001088 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001089 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001090 if (locked)
1091 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 return 0; /* No mount points found in tree */
1093positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001094 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001095 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001096 if (locked)
1097 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001099
1100rename_retry:
1101 locked = 1;
1102 write_seqlock(&rename_lock);
1103 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001105EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106
1107/*
1108 * Search the dentry child list for the specified parent,
1109 * and move any unused dentries to the end of the unused
1110 * list for prune_dcache(). We descend to the next level
1111 * whenever the d_subdirs list is non-empty and continue
1112 * searching.
1113 *
1114 * It returns zero iff there are no unused children,
1115 * otherwise it returns the number of children moved to
1116 * the end of the unused list. This may not be the total
1117 * number of unused children, because select_parent can
1118 * drop the lock and return early due to latency
1119 * constraints.
1120 */
1121static int select_parent(struct dentry * parent)
1122{
Nick Piggin949854d2011-01-07 17:49:37 +11001123 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001125 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001127 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
Nick Piggin949854d2011-01-07 17:49:37 +11001129 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001130again:
1131 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001132 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133repeat:
1134 next = this_parent->d_subdirs.next;
1135resume:
1136 while (next != &this_parent->d_subdirs) {
1137 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001138 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 next = tmp->next;
1140
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001141 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001142
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 /*
1144 * move only zero ref count dentries to the end
1145 * of the unused list for prune_dcache
1146 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001147 if (!dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001148 dentry_lru_move_tail(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 found++;
Christoph Hellwiga4633352010-10-10 05:36:26 -04001150 } else {
1151 dentry_lru_del(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152 }
1153
1154 /*
1155 * We can return to the caller if we have found some (this
1156 * ensures forward progress). We'll be coming back to find
1157 * the rest.
1158 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001159 if (found && need_resched()) {
1160 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 goto out;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001162 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163
1164 /*
1165 * Descend a level if the d_subdirs list is non-empty.
1166 */
1167 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001168 spin_unlock(&this_parent->d_lock);
1169 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001171 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 goto repeat;
1173 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001174
1175 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 }
1177 /*
1178 * All done at this level ... ascend and resume the search.
1179 */
1180 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001181 struct dentry *child = this_parent;
1182 this_parent = try_to_ascend(this_parent, locked, seq);
1183 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001184 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001185 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 goto resume;
1187 }
1188out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001189 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001190 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001191 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001192 if (locked)
1193 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 return found;
Nick Piggin58db63d2011-01-07 17:49:39 +11001195
1196rename_retry:
1197 if (found)
1198 return found;
1199 locked = 1;
1200 write_seqlock(&rename_lock);
1201 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202}
1203
1204/**
1205 * shrink_dcache_parent - prune dcache
1206 * @parent: parent of entries to prune
1207 *
1208 * Prune the dcache to remove unused children of the parent dentry.
1209 */
1210
1211void shrink_dcache_parent(struct dentry * parent)
1212{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -07001213 struct super_block *sb = parent->d_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 int found;
1215
1216 while ((found = select_parent(parent)) != 0)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -07001217 __shrink_dcache_sb(sb, &found, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001219EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221/*
1222 * Scan `nr' dentries and return the number which remain.
1223 *
1224 * We need to avoid reentering the filesystem if the caller is performing a
1225 * GFP_NOFS allocation attempt. One example deadlock is:
1226 *
1227 * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache->
1228 * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode->
1229 * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK.
1230 *
1231 * In this case we return -1 to tell the caller that we baled.
1232 */
Dave Chinner7f8275d2010-07-19 14:56:17 +10001233static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234{
1235 if (nr) {
1236 if (!(gfp_mask & __GFP_FS))
1237 return -1;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -07001238 prune_dcache(nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 }
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001240
Nick Piggin86c87492011-01-07 17:49:18 +11001241 return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242}
1243
Rusty Russell8e1f9362007-07-17 04:03:17 -07001244static struct shrinker dcache_shrinker = {
1245 .shrink = shrink_dcache_memory,
1246 .seeks = DEFAULT_SEEKS,
1247};
1248
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249/**
1250 * d_alloc - allocate a dcache entry
1251 * @parent: parent of entry to allocate
1252 * @name: qstr of the name
1253 *
1254 * Allocates a dentry. It returns %NULL if there is insufficient memory
1255 * available. On a success the dentry is returned. The name passed in is
1256 * copied and the copy passed in may be reused after this call.
1257 */
1258
1259struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1260{
1261 struct dentry *dentry;
1262 char *dname;
1263
Mel Gormane12ba742007-10-16 01:25:52 -07001264 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 if (!dentry)
1266 return NULL;
1267
1268 if (name->len > DNAME_INLINE_LEN-1) {
1269 dname = kmalloc(name->len + 1, GFP_KERNEL);
1270 if (!dname) {
1271 kmem_cache_free(dentry_cache, dentry);
1272 return NULL;
1273 }
1274 } else {
1275 dname = dentry->d_iname;
1276 }
1277 dentry->d_name.name = dname;
1278
1279 dentry->d_name.len = name->len;
1280 dentry->d_name.hash = name->hash;
1281 memcpy(dname, name->name, name->len);
1282 dname[name->len] = 0;
1283
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001284 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001285 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001287 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 dentry->d_inode = NULL;
1289 dentry->d_parent = NULL;
1290 dentry->d_sb = NULL;
1291 dentry->d_op = NULL;
1292 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001293 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 INIT_LIST_HEAD(&dentry->d_lru);
1295 INIT_LIST_HEAD(&dentry->d_subdirs);
1296 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001297 INIT_LIST_HEAD(&dentry->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298
1299 if (parent) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001300 spin_lock(&parent->d_lock);
Nick Piggin89ad4852011-01-07 17:49:41 +11001301 /*
1302 * don't need child lock because it is not subject
1303 * to concurrency here
1304 */
Nick Piggindc0474b2011-01-07 17:49:43 +11001305 __dget_dlock(parent);
1306 dentry->d_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 dentry->d_sb = parent->d_sb;
Al Viroc8aebb02010-12-18 10:22:30 -05001308 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Eric Dumazet5160ee62006-01-08 01:03:32 -08001309 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001310 spin_unlock(&parent->d_lock);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001311 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312
Nick Piggin3e880fb2011-01-07 17:49:19 +11001313 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001314
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 return dentry;
1316}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001317EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318
Nick Piggin4b936882011-01-07 17:50:07 +11001319struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1320{
1321 struct dentry *dentry = d_alloc(NULL, name);
1322 if (dentry) {
1323 dentry->d_sb = sb;
Al Viroc8aebb02010-12-18 10:22:30 -05001324 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Nick Piggin4b936882011-01-07 17:50:07 +11001325 dentry->d_parent = dentry;
1326 dentry->d_flags |= DCACHE_DISCONNECTED;
1327 }
1328 return dentry;
1329}
1330EXPORT_SYMBOL(d_alloc_pseudo);
1331
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1333{
1334 struct qstr q;
1335
1336 q.name = name;
1337 q.len = strlen(name);
1338 q.hash = full_name_hash(q.name, q.len);
1339 return d_alloc(parent, &q);
1340}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001341EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342
Nick Pigginfb045ad2011-01-07 17:49:55 +11001343void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1344{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001345 WARN_ON_ONCE(dentry->d_op);
1346 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001347 DCACHE_OP_COMPARE |
1348 DCACHE_OP_REVALIDATE |
1349 DCACHE_OP_DELETE ));
1350 dentry->d_op = op;
1351 if (!op)
1352 return;
1353 if (op->d_hash)
1354 dentry->d_flags |= DCACHE_OP_HASH;
1355 if (op->d_compare)
1356 dentry->d_flags |= DCACHE_OP_COMPARE;
1357 if (op->d_revalidate)
1358 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1359 if (op->d_delete)
1360 dentry->d_flags |= DCACHE_OP_DELETE;
1361
1362}
1363EXPORT_SYMBOL(d_set_d_op);
1364
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001365static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1366{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001367 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001368 if (inode) {
1369 if (unlikely(IS_AUTOMOUNT(inode)))
1370 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001371 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001372 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001373 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001374 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001375 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001376 fsnotify_d_instantiate(dentry, inode);
1377}
1378
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379/**
1380 * d_instantiate - fill in inode information for a dentry
1381 * @entry: dentry to complete
1382 * @inode: inode to attach to this dentry
1383 *
1384 * Fill in inode information in the entry.
1385 *
1386 * This turns negative dentries into productive full members
1387 * of society.
1388 *
1389 * NOTE! This assumes that the inode count has been incremented
1390 * (or otherwise set) by the caller to indicate that it is now
1391 * in use by the dcache.
1392 */
1393
1394void d_instantiate(struct dentry *entry, struct inode * inode)
1395{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001396 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001397 if (inode)
1398 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001399 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001400 if (inode)
1401 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 security_d_instantiate(entry, inode);
1403}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001404EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405
1406/**
1407 * d_instantiate_unique - instantiate a non-aliased dentry
1408 * @entry: dentry to instantiate
1409 * @inode: inode to attach to this dentry
1410 *
1411 * Fill in inode information in the entry. On success, it returns NULL.
1412 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001413 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 *
1415 * Note that in order to avoid conflicts with rename() etc, the caller
1416 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001417 *
1418 * This also assumes that the inode count has been incremented
1419 * (or otherwise set) by the caller to indicate that it is now
1420 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421 */
David Howells770bfad2006-08-22 20:06:07 -04001422static struct dentry *__d_instantiate_unique(struct dentry *entry,
1423 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424{
1425 struct dentry *alias;
1426 int len = entry->d_name.len;
1427 const char *name = entry->d_name.name;
1428 unsigned int hash = entry->d_name.hash;
1429
David Howells770bfad2006-08-22 20:06:07 -04001430 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001431 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001432 return NULL;
1433 }
1434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1436 struct qstr *qstr = &alias->d_name;
1437
Nick Piggin9abca362011-01-07 17:49:36 +11001438 /*
1439 * Don't need alias->d_lock here, because aliases with
1440 * d_parent == entry->d_parent are not subject to name or
1441 * parent changes, because the parent inode i_mutex is held.
1442 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 if (qstr->hash != hash)
1444 continue;
1445 if (alias->d_parent != entry->d_parent)
1446 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001447 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001449 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 return alias;
1451 }
David Howells770bfad2006-08-22 20:06:07 -04001452
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001453 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454 return NULL;
1455}
David Howells770bfad2006-08-22 20:06:07 -04001456
1457struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1458{
1459 struct dentry *result;
1460
1461 BUG_ON(!list_empty(&entry->d_alias));
1462
Nick Piggin873feea2011-01-07 17:50:06 +11001463 if (inode)
1464 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001465 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001466 if (inode)
1467 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001468
1469 if (!result) {
1470 security_d_instantiate(entry, inode);
1471 return NULL;
1472 }
1473
1474 BUG_ON(!d_unhashed(result));
1475 iput(inode);
1476 return result;
1477}
1478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479EXPORT_SYMBOL(d_instantiate_unique);
1480
1481/**
1482 * d_alloc_root - allocate root dentry
1483 * @root_inode: inode to allocate the root for
1484 *
1485 * Allocate a root ("/") dentry for the inode given. The inode is
1486 * instantiated and returned. %NULL is returned if there is insufficient
1487 * memory or the inode passed is %NULL.
1488 */
1489
1490struct dentry * d_alloc_root(struct inode * root_inode)
1491{
1492 struct dentry *res = NULL;
1493
1494 if (root_inode) {
1495 static const struct qstr name = { .name = "/", .len = 1 };
1496
1497 res = d_alloc(NULL, &name);
1498 if (res) {
1499 res->d_sb = root_inode->i_sb;
Al Viroc8aebb02010-12-18 10:22:30 -05001500 d_set_d_op(res, res->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501 res->d_parent = res;
1502 d_instantiate(res, root_inode);
1503 }
1504 }
1505 return res;
1506}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001507EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001509static struct dentry * __d_find_any_alias(struct inode *inode)
1510{
1511 struct dentry *alias;
1512
1513 if (list_empty(&inode->i_dentry))
1514 return NULL;
1515 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1516 __dget(alias);
1517 return alias;
1518}
1519
1520static struct dentry * d_find_any_alias(struct inode *inode)
1521{
1522 struct dentry *de;
1523
1524 spin_lock(&inode->i_lock);
1525 de = __d_find_any_alias(inode);
1526 spin_unlock(&inode->i_lock);
1527 return de;
1528}
1529
1530
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001532 * d_obtain_alias - find or allocate a dentry for a given inode
1533 * @inode: inode to allocate the dentry for
1534 *
1535 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1536 * similar open by handle operations. The returned dentry may be anonymous,
1537 * or may have a full name (if the inode was already in the cache).
1538 *
1539 * When called on a directory inode, we must ensure that the inode only ever
1540 * has one dentry. If a dentry is found, that is returned instead of
1541 * allocating a new one.
1542 *
1543 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001544 * to the dentry. In case of an error the reference on the inode is released.
1545 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1546 * be passed in and will be the error will be propagate to the return value,
1547 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001548 */
1549struct dentry *d_obtain_alias(struct inode *inode)
1550{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001551 static const struct qstr anonstring = { .name = "" };
1552 struct dentry *tmp;
1553 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001554
1555 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001556 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001557 if (IS_ERR(inode))
1558 return ERR_CAST(inode);
1559
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001560 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001561 if (res)
1562 goto out_iput;
1563
1564 tmp = d_alloc(NULL, &anonstring);
1565 if (!tmp) {
1566 res = ERR_PTR(-ENOMEM);
1567 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001568 }
Christoph Hellwig9308a612008-08-11 15:49:12 +02001569 tmp->d_parent = tmp; /* make sure dput doesn't croak */
1570
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001571
Nick Piggin873feea2011-01-07 17:50:06 +11001572 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001573 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001574 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001575 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001576 dput(tmp);
1577 goto out_iput;
1578 }
1579
1580 /* attach a disconnected dentry */
1581 spin_lock(&tmp->d_lock);
1582 tmp->d_sb = inode->i_sb;
Al Viroc8aebb02010-12-18 10:22:30 -05001583 d_set_d_op(tmp, tmp->d_sb->s_d_op);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001584 tmp->d_inode = inode;
1585 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001586 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001587 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001588 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001589 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001590 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001591 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001592 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001593
Christoph Hellwig9308a612008-08-11 15:49:12 +02001594 return tmp;
1595
1596 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001597 if (res && !IS_ERR(res))
1598 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001599 iput(inode);
1600 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001601}
Benny Halevyadc48722009-02-27 14:02:59 -08001602EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603
1604/**
1605 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1606 * @inode: the inode which may have a disconnected dentry
1607 * @dentry: a negative dentry which we want to point to the inode.
1608 *
1609 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1610 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1611 * and return it, else simply d_add the inode to the dentry and return NULL.
1612 *
1613 * This is needed in the lookup routine of any filesystem that is exportable
1614 * (via knfsd) so that we can build dcache paths to directories effectively.
1615 *
1616 * If a dentry was found and moved, then it is returned. Otherwise NULL
1617 * is returned. This matches the expected return value of ->lookup.
1618 *
1619 */
1620struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1621{
1622 struct dentry *new = NULL;
1623
NeilBrown21c0d8f2006-10-04 02:16:16 -07001624 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001625 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 new = __d_find_alias(inode, 1);
1627 if (new) {
1628 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001629 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 d_move(new, dentry);
1632 iput(inode);
1633 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001634 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001635 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001636 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 security_d_instantiate(dentry, inode);
1638 d_rehash(dentry);
1639 }
1640 } else
1641 d_add(dentry, inode);
1642 return new;
1643}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001644EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645
Barry Naujok94035402008-05-21 16:50:46 +10001646/**
1647 * d_add_ci - lookup or allocate new dentry with case-exact name
1648 * @inode: the inode case-insensitive lookup has found
1649 * @dentry: the negative dentry that was passed to the parent's lookup func
1650 * @name: the case-exact name to be associated with the returned dentry
1651 *
1652 * This is to avoid filling the dcache with case-insensitive names to the
1653 * same inode, only the actual correct case is stored in the dcache for
1654 * case-insensitive filesystems.
1655 *
1656 * For a case-insensitive lookup match and if the the case-exact dentry
1657 * already exists in in the dcache, use it and return it.
1658 *
1659 * If no entry exists with the exact case name, allocate new dentry with
1660 * the exact case, and return the spliced entry.
1661 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001662struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001663 struct qstr *name)
1664{
1665 int error;
1666 struct dentry *found;
1667 struct dentry *new;
1668
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001669 /*
1670 * First check if a dentry matching the name already exists,
1671 * if not go ahead and create it now.
1672 */
Barry Naujok94035402008-05-21 16:50:46 +10001673 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001674 if (!found) {
1675 new = d_alloc(dentry->d_parent, name);
1676 if (!new) {
1677 error = -ENOMEM;
1678 goto err_out;
1679 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001680
Barry Naujok94035402008-05-21 16:50:46 +10001681 found = d_splice_alias(inode, new);
1682 if (found) {
1683 dput(new);
1684 return found;
1685 }
1686 return new;
1687 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001688
1689 /*
1690 * If a matching dentry exists, and it's not negative use it.
1691 *
1692 * Decrement the reference count to balance the iget() done
1693 * earlier on.
1694 */
Barry Naujok94035402008-05-21 16:50:46 +10001695 if (found->d_inode) {
1696 if (unlikely(found->d_inode != inode)) {
1697 /* This can't happen because bad inodes are unhashed. */
1698 BUG_ON(!is_bad_inode(inode));
1699 BUG_ON(!is_bad_inode(found->d_inode));
1700 }
Barry Naujok94035402008-05-21 16:50:46 +10001701 iput(inode);
1702 return found;
1703 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001704
Barry Naujok94035402008-05-21 16:50:46 +10001705 /*
1706 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001707 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001708 */
Nick Piggin873feea2011-01-07 17:50:06 +11001709 spin_lock(&inode->i_lock);
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001710 if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001711 __d_instantiate(found, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001712 spin_unlock(&inode->i_lock);
Barry Naujok94035402008-05-21 16:50:46 +10001713 security_d_instantiate(found, inode);
1714 return found;
1715 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001716
Barry Naujok94035402008-05-21 16:50:46 +10001717 /*
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001718 * In case a directory already has a (disconnected) entry grab a
1719 * reference to it, move it in place and use it.
Barry Naujok94035402008-05-21 16:50:46 +10001720 */
1721 new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
Nick Piggindc0474b2011-01-07 17:49:43 +11001722 __dget(new);
Nick Piggin873feea2011-01-07 17:50:06 +11001723 spin_unlock(&inode->i_lock);
Barry Naujok94035402008-05-21 16:50:46 +10001724 security_d_instantiate(found, inode);
Barry Naujok94035402008-05-21 16:50:46 +10001725 d_move(new, found);
Barry Naujok94035402008-05-21 16:50:46 +10001726 iput(inode);
Barry Naujok94035402008-05-21 16:50:46 +10001727 dput(found);
Barry Naujok94035402008-05-21 16:50:46 +10001728 return new;
1729
1730err_out:
1731 iput(inode);
1732 return ERR_PTR(error);
1733}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001734EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735
1736/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001737 * __d_lookup_rcu - search for a dentry (racy, store-free)
1738 * @parent: parent dentry
1739 * @name: qstr of name we wish to find
1740 * @seq: returns d_seq value at the point where the dentry was found
1741 * @inode: returns dentry->d_inode when the inode was found valid.
1742 * Returns: dentry, or NULL
1743 *
1744 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1745 * resolution (store-free path walking) design described in
1746 * Documentation/filesystems/path-lookup.txt.
1747 *
1748 * This is not to be used outside core vfs.
1749 *
1750 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1751 * held, and rcu_read_lock held. The returned dentry must not be stored into
1752 * without taking d_lock and checking d_seq sequence count against @seq
1753 * returned here.
1754 *
1755 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1756 * function.
1757 *
1758 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1759 * the returned dentry, so long as its parent's seqlock is checked after the
1760 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1761 * is formed, giving integrity down the path walk.
1762 */
1763struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
1764 unsigned *seq, struct inode **inode)
1765{
1766 unsigned int len = name->len;
1767 unsigned int hash = name->hash;
1768 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001769 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001770 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001771 struct dentry *dentry;
1772
1773 /*
1774 * Note: There is significant duplication with __d_lookup_rcu which is
1775 * required to prevent single threaded performance regressions
1776 * especially on architectures where smp_rmb (in seqcounts) are costly.
1777 * Keep the two functions in sync.
1778 */
1779
1780 /*
1781 * The hash list is protected using RCU.
1782 *
1783 * Carefully use d_seq when comparing a candidate dentry, to avoid
1784 * races with d_move().
1785 *
1786 * It is possible that concurrent renames can mess up our list
1787 * walk here and result in missing our dentry, resulting in the
1788 * false-negative result. d_lookup() protects against concurrent
1789 * renames using rename_lock seqlock.
1790 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001791 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001792 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001793 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001794 struct inode *i;
1795 const char *tname;
1796 int tlen;
1797
1798 if (dentry->d_name.hash != hash)
1799 continue;
1800
1801seqretry:
1802 *seq = read_seqcount_begin(&dentry->d_seq);
1803 if (dentry->d_parent != parent)
1804 continue;
1805 if (d_unhashed(dentry))
1806 continue;
1807 tlen = dentry->d_name.len;
1808 tname = dentry->d_name.name;
1809 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001810 prefetch(tname);
1811 if (i)
1812 prefetch(i);
Nick Piggin31e6b012011-01-07 17:49:52 +11001813 /*
1814 * This seqcount check is required to ensure name and
1815 * len are loaded atomically, so as not to walk off the
1816 * edge of memory when walking. If we could load this
1817 * atomically some other way, we could drop this check.
1818 */
1819 if (read_seqcount_retry(&dentry->d_seq, *seq))
1820 goto seqretry;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001821 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001822 if (parent->d_op->d_compare(parent, *inode,
1823 dentry, i,
1824 tlen, tname, name))
1825 continue;
1826 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001827 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001828 continue;
1829 }
1830 /*
1831 * No extra seqcount check is required after the name
1832 * compare. The caller must perform a seqcount check in
1833 * order to do anything useful with the returned dentry
1834 * anyway.
1835 */
1836 *inode = i;
1837 return dentry;
1838 }
1839 return NULL;
1840}
1841
1842/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 * d_lookup - search for a dentry
1844 * @parent: parent dentry
1845 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001846 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001848 * d_lookup searches the children of the parent dentry for the name in
1849 * question. If the dentry is found its reference count is incremented and the
1850 * dentry is returned. The caller must use dput to free the entry when it has
1851 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001853struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854{
Nick Piggin31e6b012011-01-07 17:49:52 +11001855 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001856 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857
1858 do {
1859 seq = read_seqbegin(&rename_lock);
1860 dentry = __d_lookup(parent, name);
1861 if (dentry)
1862 break;
1863 } while (read_seqretry(&rename_lock, seq));
1864 return dentry;
1865}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001866EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867
Nick Piggin31e6b012011-01-07 17:49:52 +11001868/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001869 * __d_lookup - search for a dentry (racy)
1870 * @parent: parent dentry
1871 * @name: qstr of name we wish to find
1872 * Returns: dentry, or NULL
1873 *
1874 * __d_lookup is like d_lookup, however it may (rarely) return a
1875 * false-negative result due to unrelated rename activity.
1876 *
1877 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1878 * however it must be used carefully, eg. with a following d_lookup in
1879 * the case of failure.
1880 *
1881 * __d_lookup callers must be commented.
1882 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001883struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884{
1885 unsigned int len = name->len;
1886 unsigned int hash = name->hash;
1887 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001888 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001889 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001890 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001891 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892
Nick Pigginb04f7842010-08-18 04:37:34 +10001893 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001894 * Note: There is significant duplication with __d_lookup_rcu which is
1895 * required to prevent single threaded performance regressions
1896 * especially on architectures where smp_rmb (in seqcounts) are costly.
1897 * Keep the two functions in sync.
1898 */
1899
1900 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001901 * The hash list is protected using RCU.
1902 *
1903 * Take d_lock when comparing a candidate dentry, to avoid races
1904 * with d_move().
1905 *
1906 * It is possible that concurrent renames can mess up our list
1907 * walk here and result in missing our dentry, resulting in the
1908 * false-negative result. d_lookup() protects against concurrent
1909 * renames using rename_lock seqlock.
1910 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001911 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001912 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 rcu_read_lock();
1914
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001915 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001916 const char *tname;
1917 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 if (dentry->d_name.hash != hash)
1920 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001921
1922 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923 if (dentry->d_parent != parent)
1924 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001925 if (d_unhashed(dentry))
1926 goto next;
1927
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 /*
1929 * It is safe to compare names since d_move() cannot
1930 * change the qstr (protected by d_lock).
1931 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001932 tlen = dentry->d_name.len;
1933 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001934 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001935 if (parent->d_op->d_compare(parent, parent->d_inode,
1936 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001937 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 goto next;
1939 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001940 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 goto next;
1942 }
1943
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001944 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001945 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 spin_unlock(&dentry->d_lock);
1947 break;
1948next:
1949 spin_unlock(&dentry->d_lock);
1950 }
1951 rcu_read_unlock();
1952
1953 return found;
1954}
1955
1956/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001957 * d_hash_and_lookup - hash the qstr then search for a dentry
1958 * @dir: Directory to search in
1959 * @name: qstr of name we wish to find
1960 *
1961 * On hash failure or on lookup failure NULL is returned.
1962 */
1963struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1964{
1965 struct dentry *dentry = NULL;
1966
1967 /*
1968 * Check for a fs-specific hash function. Note that we must
1969 * calculate the standard hash first, as the d_op->d_hash()
1970 * routine may choose to leave the hash value unchanged.
1971 */
1972 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001973 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001974 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001975 goto out;
1976 }
1977 dentry = d_lookup(dir, name);
1978out:
1979 return dentry;
1980}
1981
1982/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001983 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001985 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 *
1987 * An insecure source has sent us a dentry, here we verify it and dget() it.
1988 * This is used by ncpfs in its readdir implementation.
1989 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001990 *
1991 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001993int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994{
Nick Piggin786a5e12011-01-07 17:49:16 +11001995 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001996
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001997 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001998 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
1999 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002000 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11002001 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002002 spin_unlock(&dentry->d_lock);
2003 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004 return 1;
2005 }
2006 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002007 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11002008
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 return 0;
2010}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002011EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012
2013/*
2014 * When a file is deleted, we have two options:
2015 * - turn this dentry into a negative dentry
2016 * - unhash this dentry and free it.
2017 *
2018 * Usually, we want to just turn this into
2019 * a negative dentry, but if anybody else is
2020 * currently using the dentry or the inode
2021 * we can't do that and we fall back on removing
2022 * it from the hash queues and waiting for
2023 * it to be deleted later when it has no users
2024 */
2025
2026/**
2027 * d_delete - delete a dentry
2028 * @dentry: The dentry to delete
2029 *
2030 * Turn the dentry into a negative dentry if possible, otherwise
2031 * remove it from the hash queues so it can be deleted later
2032 */
2033
2034void d_delete(struct dentry * dentry)
2035{
Nick Piggin873feea2011-01-07 17:50:06 +11002036 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04002037 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038 /*
2039 * Are we the only user?
2040 */
Nick Piggin357f8e62011-01-07 17:49:42 +11002041again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002043 inode = dentry->d_inode;
2044 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002045 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11002046 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11002047 spin_unlock(&dentry->d_lock);
2048 cpu_relax();
2049 goto again;
2050 }
Al Viro13e3c5e2010-05-21 16:11:04 -04002051 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11002052 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04002053 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054 return;
2055 }
2056
2057 if (!d_unhashed(dentry))
2058 __d_drop(dentry);
2059
2060 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04002061
2062 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002064EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002066static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002068 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002069 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07002070 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002071 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002072 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002073}
2074
David Howells770bfad2006-08-22 20:06:07 -04002075static void _d_rehash(struct dentry * entry)
2076{
2077 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2078}
2079
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080/**
2081 * d_rehash - add an entry back to the hash
2082 * @entry: dentry to add to the hash
2083 *
2084 * Adds a dentry to the hash according to its name.
2085 */
2086
2087void d_rehash(struct dentry * entry)
2088{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002090 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002093EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002095/**
2096 * dentry_update_name_case - update case insensitive dentry with a new name
2097 * @dentry: dentry to be updated
2098 * @name: new name
2099 *
2100 * Update a case insensitive dentry with new case of name.
2101 *
2102 * dentry must have been returned by d_lookup with name @name. Old and new
2103 * name lengths must match (ie. no d_compare which allows mismatched name
2104 * lengths).
2105 *
2106 * Parent inode i_mutex must be held over d_lookup and into this call (to
2107 * keep renames and concurrent inserts, and readdir(2) away).
2108 */
2109void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2110{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002111 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002112 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2113
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002114 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002115 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002116 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002117 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002118 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002119}
2120EXPORT_SYMBOL(dentry_update_name_case);
2121
Linus Torvalds1da177e2005-04-16 15:20:36 -07002122static void switch_names(struct dentry *dentry, struct dentry *target)
2123{
2124 if (dname_external(target)) {
2125 if (dname_external(dentry)) {
2126 /*
2127 * Both external: swap the pointers
2128 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002129 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130 } else {
2131 /*
2132 * dentry:internal, target:external. Steal target's
2133 * storage and make target internal.
2134 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002135 memcpy(target->d_iname, dentry->d_name.name,
2136 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 dentry->d_name.name = target->d_name.name;
2138 target->d_name.name = target->d_iname;
2139 }
2140 } else {
2141 if (dname_external(dentry)) {
2142 /*
2143 * dentry:external, target:internal. Give dentry's
2144 * storage to target and make dentry internal
2145 */
2146 memcpy(dentry->d_iname, target->d_name.name,
2147 target->d_name.len + 1);
2148 target->d_name.name = dentry->d_name.name;
2149 dentry->d_name.name = dentry->d_iname;
2150 } else {
2151 /*
2152 * Both are internal. Just copy target to dentry
2153 */
2154 memcpy(dentry->d_iname, target->d_name.name,
2155 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002156 dentry->d_name.len = target->d_name.len;
2157 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 }
2159 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002160 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161}
2162
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002163static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2164{
2165 /*
2166 * XXXX: do we really need to take target->d_lock?
2167 */
2168 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2169 spin_lock(&target->d_parent->d_lock);
2170 else {
2171 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2172 spin_lock(&dentry->d_parent->d_lock);
2173 spin_lock_nested(&target->d_parent->d_lock,
2174 DENTRY_D_LOCK_NESTED);
2175 } else {
2176 spin_lock(&target->d_parent->d_lock);
2177 spin_lock_nested(&dentry->d_parent->d_lock,
2178 DENTRY_D_LOCK_NESTED);
2179 }
2180 }
2181 if (target < dentry) {
2182 spin_lock_nested(&target->d_lock, 2);
2183 spin_lock_nested(&dentry->d_lock, 3);
2184 } else {
2185 spin_lock_nested(&dentry->d_lock, 2);
2186 spin_lock_nested(&target->d_lock, 3);
2187 }
2188}
2189
2190static void dentry_unlock_parents_for_move(struct dentry *dentry,
2191 struct dentry *target)
2192{
2193 if (target->d_parent != dentry->d_parent)
2194 spin_unlock(&dentry->d_parent->d_lock);
2195 if (target->d_parent != target)
2196 spin_unlock(&target->d_parent->d_lock);
2197}
2198
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002200 * When switching names, the actual string doesn't strictly have to
2201 * be preserved in the target - because we're dropping the target
2202 * anyway. As such, we can just do a simple memcpy() to copy over
2203 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002205 * Note that we have to be a lot more careful about getting the hash
2206 * switched - we have to switch the hash value properly even if it
2207 * then no longer matches the actual (corrupted) string of the target.
2208 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002210/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +11002211 * d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212 * @dentry: entry to move
2213 * @target: new dentry
2214 *
2215 * Update the dcache to reflect the move of a file name. Negative
2216 * dcache entries should not be moved in this way.
2217 */
Nick Pigginb5c84bf2011-01-07 17:49:38 +11002218void d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 if (!dentry->d_inode)
2221 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2222
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002223 BUG_ON(d_ancestor(dentry, target));
2224 BUG_ON(d_ancestor(target, dentry));
2225
Linus Torvalds1da177e2005-04-16 15:20:36 -07002226 write_seqlock(&rename_lock);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002227
2228 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229
Nick Piggin31e6b012011-01-07 17:49:52 +11002230 write_seqcount_begin(&dentry->d_seq);
2231 write_seqcount_begin(&target->d_seq);
2232
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002233 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2234
2235 /*
2236 * Move the dentry to the target hash queue. Don't bother checking
2237 * for the same hash queue because of how unlikely it is.
2238 */
2239 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002240 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241
2242 /* Unhash the target: dput() will then get rid of it */
2243 __d_drop(target);
2244
Eric Dumazet5160ee62006-01-08 01:03:32 -08002245 list_del(&dentry->d_u.d_child);
2246 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247
2248 /* Switch the names.. */
2249 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002250 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251
2252 /* ... and switch the parents */
2253 if (IS_ROOT(dentry)) {
2254 dentry->d_parent = target->d_parent;
2255 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002256 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002258 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259
2260 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002261 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 }
2263
Eric Dumazet5160ee62006-01-08 01:03:32 -08002264 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002265
Nick Piggin31e6b012011-01-07 17:49:52 +11002266 write_seqcount_end(&target->d_seq);
2267 write_seqcount_end(&dentry->d_seq);
2268
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002269 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002271 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 spin_unlock(&dentry->d_lock);
2273 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002274}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002275EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002277/**
2278 * d_ancestor - search for an ancestor
2279 * @p1: ancestor dentry
2280 * @p2: child dentry
2281 *
2282 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2283 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002284 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002285struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002286{
2287 struct dentry *p;
2288
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002289 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002290 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002291 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002292 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002293 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002294}
2295
2296/*
2297 * This helper attempts to cope with remotely renamed directories
2298 *
2299 * It assumes that the caller is already holding
Nick Piggin873feea2011-01-07 17:50:06 +11002300 * dentry->d_parent->d_inode->i_mutex and the inode->i_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002301 *
2302 * Note: If ever the locking in lock_rename() changes, then please
2303 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002304 */
Nick Piggin873feea2011-01-07 17:50:06 +11002305static struct dentry *__d_unalias(struct inode *inode,
2306 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002307{
2308 struct mutex *m1 = NULL, *m2 = NULL;
2309 struct dentry *ret;
2310
2311 /* If alias and dentry share a parent, then no extra locks required */
2312 if (alias->d_parent == dentry->d_parent)
2313 goto out_unalias;
2314
2315 /* Check for loops */
2316 ret = ERR_PTR(-ELOOP);
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002317 if (d_ancestor(alias, dentry))
Trond Myklebust9eaef272006-10-21 10:24:20 -07002318 goto out_err;
2319
2320 /* See lock_rename() */
2321 ret = ERR_PTR(-EBUSY);
2322 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2323 goto out_err;
2324 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2325 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2326 goto out_err;
2327 m2 = &alias->d_parent->d_inode->i_mutex;
2328out_unalias:
Nick Pigginb5c84bf2011-01-07 17:49:38 +11002329 d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002330 ret = alias;
2331out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002332 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002333 if (m2)
2334 mutex_unlock(m2);
2335 if (m1)
2336 mutex_unlock(m1);
2337 return ret;
2338}
2339
2340/*
David Howells770bfad2006-08-22 20:06:07 -04002341 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2342 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002343 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002344 */
2345static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2346{
2347 struct dentry *dparent, *aparent;
2348
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002349 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002350
Nick Piggin31e6b012011-01-07 17:49:52 +11002351 write_seqcount_begin(&dentry->d_seq);
2352 write_seqcount_begin(&anon->d_seq);
2353
David Howells770bfad2006-08-22 20:06:07 -04002354 dparent = dentry->d_parent;
2355 aparent = anon->d_parent;
2356
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002357 switch_names(dentry, anon);
2358 swap(dentry->d_name.hash, anon->d_name.hash);
2359
David Howells770bfad2006-08-22 20:06:07 -04002360 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2361 list_del(&dentry->d_u.d_child);
2362 if (!IS_ROOT(dentry))
2363 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2364 else
2365 INIT_LIST_HEAD(&dentry->d_u.d_child);
2366
2367 anon->d_parent = (dparent == dentry) ? anon : dparent;
2368 list_del(&anon->d_u.d_child);
2369 if (!IS_ROOT(anon))
2370 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2371 else
2372 INIT_LIST_HEAD(&anon->d_u.d_child);
2373
Nick Piggin31e6b012011-01-07 17:49:52 +11002374 write_seqcount_end(&dentry->d_seq);
2375 write_seqcount_end(&anon->d_seq);
2376
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002377 dentry_unlock_parents_for_move(anon, dentry);
2378 spin_unlock(&dentry->d_lock);
2379
2380 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002381 anon->d_flags &= ~DCACHE_DISCONNECTED;
2382}
2383
2384/**
2385 * d_materialise_unique - introduce an inode into the tree
2386 * @dentry: candidate dentry
2387 * @inode: inode to bind to the dentry, to which aliases may be attached
2388 *
2389 * Introduces an dentry into the tree, substituting an extant disconnected
2390 * root directory alias in its place if there is one
2391 */
2392struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2393{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002394 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002395
2396 BUG_ON(!d_unhashed(dentry));
2397
David Howells770bfad2006-08-22 20:06:07 -04002398 if (!inode) {
2399 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002400 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002401 d_rehash(actual);
2402 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002403 }
2404
Nick Piggin873feea2011-01-07 17:50:06 +11002405 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002406
Trond Myklebust9eaef272006-10-21 10:24:20 -07002407 if (S_ISDIR(inode->i_mode)) {
2408 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002409
Trond Myklebust9eaef272006-10-21 10:24:20 -07002410 /* Does an aliased dentry already exist? */
2411 alias = __d_find_alias(inode, 0);
2412 if (alias) {
2413 actual = alias;
2414 /* Is this an anonymous mountpoint that we could splice
2415 * into our tree? */
2416 if (IS_ROOT(alias)) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002417 __d_materialise_dentry(dentry, alias);
2418 __d_drop(alias);
2419 goto found;
2420 }
2421 /* Nope, but we must(!) avoid directory aliasing */
Nick Piggin873feea2011-01-07 17:50:06 +11002422 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002423 if (IS_ERR(actual))
2424 dput(alias);
2425 goto out_nolock;
2426 }
David Howells770bfad2006-08-22 20:06:07 -04002427 }
2428
2429 /* Add a unique reference */
2430 actual = __d_instantiate_unique(dentry, inode);
2431 if (!actual)
2432 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002433 else
2434 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002435
David Howells770bfad2006-08-22 20:06:07 -04002436 spin_lock(&actual->d_lock);
2437found:
2438 _d_rehash(actual);
2439 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002440 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002441out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002442 if (actual == dentry) {
2443 security_d_instantiate(dentry, inode);
2444 return NULL;
2445 }
2446
2447 iput(inode);
2448 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002449}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002450EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002451
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002452static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002453{
2454 *buflen -= namelen;
2455 if (*buflen < 0)
2456 return -ENAMETOOLONG;
2457 *buffer -= namelen;
2458 memcpy(*buffer, str, namelen);
2459 return 0;
2460}
2461
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002462static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2463{
2464 return prepend(buffer, buflen, name->name, name->len);
2465}
2466
Linus Torvalds1da177e2005-04-16 15:20:36 -07002467/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002468 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002469 * @path: the dentry/vfsmount to report
2470 * @root: root vfsmnt/dentry (may be modified by this function)
2471 * @buffer: pointer to the end of the buffer
2472 * @buflen: pointer to buffer length
2473 *
Nick Piggin949854d2011-01-07 17:49:37 +11002474 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002475 *
2476 * If path is not reachable from the supplied root, then the value of
2477 * root is changed (without modifying refcounts).
2478 */
2479static int prepend_path(const struct path *path, struct path *root,
2480 char **buffer, int *buflen)
2481{
2482 struct dentry *dentry = path->dentry;
2483 struct vfsmount *vfsmnt = path->mnt;
2484 bool slash = false;
2485 int error = 0;
2486
Nick Piggin99b7db72010-08-18 04:37:39 +10002487 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002488 while (dentry != root->dentry || vfsmnt != root->mnt) {
2489 struct dentry * parent;
2490
2491 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2492 /* Global root? */
2493 if (vfsmnt->mnt_parent == vfsmnt) {
2494 goto global_root;
2495 }
2496 dentry = vfsmnt->mnt_mountpoint;
2497 vfsmnt = vfsmnt->mnt_parent;
2498 continue;
2499 }
2500 parent = dentry->d_parent;
2501 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002502 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002503 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002504 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002505 if (!error)
2506 error = prepend(buffer, buflen, "/", 1);
2507 if (error)
2508 break;
2509
2510 slash = true;
2511 dentry = parent;
2512 }
2513
2514out:
2515 if (!error && !slash)
2516 error = prepend(buffer, buflen, "/", 1);
2517
Nick Piggin99b7db72010-08-18 04:37:39 +10002518 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002519 return error;
2520
2521global_root:
2522 /*
2523 * Filesystems needing to implement special "root names"
2524 * should do so with ->d_dname()
2525 */
2526 if (IS_ROOT(dentry) &&
2527 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2528 WARN(1, "Root dentry has weird name <%.*s>\n",
2529 (int) dentry->d_name.len, dentry->d_name.name);
2530 }
2531 root->mnt = vfsmnt;
2532 root->dentry = dentry;
2533 goto out;
2534}
2535
2536/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002537 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002538 * @path: the dentry/vfsmount to report
2539 * @root: root vfsmnt/dentry (may be modified by this function)
Randy Dunlapcd956a12010-08-14 13:05:31 -07002540 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002541 * @buflen: buffer length
2542 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002543 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002544 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002545 * Returns a pointer into the buffer or an error code if the
2546 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002547 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002548 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002549 *
2550 * If path is not reachable from the supplied root, then the value of
2551 * root is changed (without modifying refcounts).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552 */
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002553char *__d_path(const struct path *path, struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002554 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002556 char *res = buf + buflen;
2557 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002558
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002559 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002560 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002561 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002562 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002563
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002564 if (error)
2565 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002566 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002567}
2568
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002569/*
2570 * same as __d_path but appends "(deleted)" for unlinked files.
2571 */
2572static int path_with_deleted(const struct path *path, struct path *root,
2573 char **buf, int *buflen)
2574{
2575 prepend(buf, buflen, "\0", 1);
2576 if (d_unlinked(path->dentry)) {
2577 int error = prepend(buf, buflen, " (deleted)", 10);
2578 if (error)
2579 return error;
2580 }
2581
2582 return prepend_path(path, root, buf, buflen);
2583}
2584
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002585static int prepend_unreachable(char **buffer, int *buflen)
2586{
2587 return prepend(buffer, buflen, "(unreachable)", 13);
2588}
2589
Jan Bluncka03a8a702008-02-14 19:38:32 -08002590/**
2591 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002592 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002593 * @buf: buffer to return value in
2594 * @buflen: buffer length
2595 *
2596 * Convert a dentry into an ASCII path name. If the entry has been deleted
2597 * the string " (deleted)" is appended. Note that this is ambiguous.
2598 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002599 * Returns a pointer into the buffer or an error code if the path was
2600 * too long. Note: Callers should use the returned pointer, not the passed
2601 * in buffer, to use the name! The implementation often starts at an offset
2602 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002603 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002604 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002605 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002606char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002607{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002608 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002609 struct path root;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002610 struct path tmp;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002611 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002612
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002613 /*
2614 * We have various synthetic filesystems that never get mounted. On
2615 * these filesystems dentries are never used for lookup purposes, and
2616 * thus don't need to be hashed. They also don't need a name until a
2617 * user wants to identify the object in /proc/pid/fd/. The little hack
2618 * below allows us to generate a name for these objects on demand:
2619 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002620 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2621 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002622
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002623 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002624 write_seqlock(&rename_lock);
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002625 tmp = root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002626 error = path_with_deleted(path, &tmp, &res, &buflen);
2627 if (error)
2628 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002629 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002630 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631 return res;
2632}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002633EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002635/**
2636 * d_path_with_unreachable - return the path of a dentry
2637 * @path: path to report
2638 * @buf: buffer to return value in
2639 * @buflen: buffer length
2640 *
2641 * The difference from d_path() is that this prepends "(unreachable)"
2642 * to paths which are unreachable from the current process' root.
2643 */
2644char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2645{
2646 char *res = buf + buflen;
2647 struct path root;
2648 struct path tmp;
2649 int error;
2650
2651 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2652 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2653
2654 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002655 write_seqlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002656 tmp = root;
2657 error = path_with_deleted(path, &tmp, &res, &buflen);
2658 if (!error && !path_equal(&tmp, &root))
2659 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002660 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002661 path_put(&root);
2662 if (error)
2663 res = ERR_PTR(error);
2664
2665 return res;
2666}
2667
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002669 * Helper function for dentry_operations.d_dname() members
2670 */
2671char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2672 const char *fmt, ...)
2673{
2674 va_list args;
2675 char temp[64];
2676 int sz;
2677
2678 va_start(args, fmt);
2679 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2680 va_end(args);
2681
2682 if (sz > sizeof(temp) || sz > buflen)
2683 return ERR_PTR(-ENAMETOOLONG);
2684
2685 buffer += buflen - sz;
2686 return memcpy(buffer, temp, sz);
2687}
2688
2689/*
Ram Pai6092d042008-03-27 13:06:20 +01002690 * Write full pathname from the root of the filesystem into the buffer.
2691 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002692static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002693{
2694 char *end = buf + buflen;
2695 char *retval;
2696
Ram Pai6092d042008-03-27 13:06:20 +01002697 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002698 if (buflen < 1)
2699 goto Elong;
2700 /* Get '/' right */
2701 retval = end-1;
2702 *retval = '/';
2703
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002704 while (!IS_ROOT(dentry)) {
2705 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002706 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002707
Ram Pai6092d042008-03-27 13:06:20 +01002708 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002709 spin_lock(&dentry->d_lock);
2710 error = prepend_name(&end, &buflen, &dentry->d_name);
2711 spin_unlock(&dentry->d_lock);
2712 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002713 goto Elong;
2714
2715 retval = end;
2716 dentry = parent;
2717 }
Al Viroc1031352010-06-06 22:31:14 -04002718 return retval;
2719Elong:
2720 return ERR_PTR(-ENAMETOOLONG);
2721}
Nick Pigginec2447c2011-01-07 17:49:29 +11002722
2723char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2724{
2725 char *retval;
2726
Nick Piggin949854d2011-01-07 17:49:37 +11002727 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002728 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002729 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002730
2731 return retval;
2732}
2733EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002734
2735char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2736{
2737 char *p = NULL;
2738 char *retval;
2739
Nick Piggin949854d2011-01-07 17:49:37 +11002740 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002741 if (d_unlinked(dentry)) {
2742 p = buf + buflen;
2743 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2744 goto Elong;
2745 buflen++;
2746 }
2747 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002748 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002749 if (!IS_ERR(retval) && p)
2750 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002751 return retval;
2752Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002753 return ERR_PTR(-ENAMETOOLONG);
2754}
2755
2756/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002757 * NOTE! The user-level library version returns a
2758 * character pointer. The kernel system call just
2759 * returns the length of the buffer filled (which
2760 * includes the ending '\0' character), or a negative
2761 * error value. So libc would do something like
2762 *
2763 * char *getcwd(char * buf, size_t size)
2764 * {
2765 * int retval;
2766 *
2767 * retval = sys_getcwd(buf, size);
2768 * if (retval >= 0)
2769 * return buf;
2770 * errno = -retval;
2771 * return NULL;
2772 * }
2773 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002774SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775{
Linus Torvalds552ce542007-02-13 12:08:18 -08002776 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002777 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002778 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002779
2780 if (!page)
2781 return -ENOMEM;
2782
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002783 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002784
Linus Torvalds552ce542007-02-13 12:08:18 -08002785 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002786 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002787 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002788 unsigned long len;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002789 struct path tmp = root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002790 char *cwd = page + PAGE_SIZE;
2791 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002793 prepend(&cwd, &buflen, "\0", 1);
2794 error = prepend_path(&pwd, &tmp, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002795 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002796
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002797 if (error)
Linus Torvalds552ce542007-02-13 12:08:18 -08002798 goto out;
2799
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002800 /* Unreachable from current root */
2801 if (!path_equal(&tmp, &root)) {
2802 error = prepend_unreachable(&cwd, &buflen);
2803 if (error)
2804 goto out;
2805 }
2806
Linus Torvalds552ce542007-02-13 12:08:18 -08002807 error = -ERANGE;
2808 len = PAGE_SIZE + page - cwd;
2809 if (len <= size) {
2810 error = len;
2811 if (copy_to_user(buf, cwd, len))
2812 error = -EFAULT;
2813 }
Nick Piggin949854d2011-01-07 17:49:37 +11002814 } else {
2815 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002816 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002817
2818out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002819 path_put(&pwd);
2820 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821 free_page((unsigned long) page);
2822 return error;
2823}
2824
2825/*
2826 * Test whether new_dentry is a subdirectory of old_dentry.
2827 *
2828 * Trivially implemented using the dcache structure
2829 */
2830
2831/**
2832 * is_subdir - is new dentry a subdirectory of old_dentry
2833 * @new_dentry: new dentry
2834 * @old_dentry: old dentry
2835 *
2836 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2837 * Returns 0 otherwise.
2838 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2839 */
2840
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002841int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842{
2843 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002844 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002846 if (new_dentry == old_dentry)
2847 return 1;
2848
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002849 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002850 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002851 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002852 /*
2853 * Need rcu_readlock to protect against the d_parent trashing
2854 * due to d_move
2855 */
2856 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002857 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002859 else
2860 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002861 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002862 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002863
2864 return result;
2865}
2866
Al Viro2096f752010-01-30 13:16:21 -05002867int path_is_under(struct path *path1, struct path *path2)
2868{
2869 struct vfsmount *mnt = path1->mnt;
2870 struct dentry *dentry = path1->dentry;
2871 int res;
Nick Piggin99b7db72010-08-18 04:37:39 +10002872
2873 br_read_lock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002874 if (mnt != path2->mnt) {
2875 for (;;) {
2876 if (mnt->mnt_parent == mnt) {
Nick Piggin99b7db72010-08-18 04:37:39 +10002877 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002878 return 0;
2879 }
2880 if (mnt->mnt_parent == path2->mnt)
2881 break;
2882 mnt = mnt->mnt_parent;
2883 }
2884 dentry = mnt->mnt_mountpoint;
2885 }
2886 res = is_subdir(dentry, path2->dentry);
Nick Piggin99b7db72010-08-18 04:37:39 +10002887 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002888 return res;
2889}
2890EXPORT_SYMBOL(path_is_under);
2891
Linus Torvalds1da177e2005-04-16 15:20:36 -07002892void d_genocide(struct dentry *root)
2893{
Nick Piggin949854d2011-01-07 17:49:37 +11002894 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002895 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002896 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002897 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002898
Nick Piggin949854d2011-01-07 17:49:37 +11002899 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002900again:
2901 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002902 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002903repeat:
2904 next = this_parent->d_subdirs.next;
2905resume:
2906 while (next != &this_parent->d_subdirs) {
2907 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002908 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002909 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002910
Nick Pigginda502952011-01-07 17:49:33 +11002911 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2912 if (d_unhashed(dentry) || !dentry->d_inode) {
2913 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002914 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002915 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002916 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002917 spin_unlock(&this_parent->d_lock);
2918 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002919 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002920 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002921 goto repeat;
2922 }
Nick Piggin949854d2011-01-07 17:49:37 +11002923 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2924 dentry->d_flags |= DCACHE_GENOCIDE;
2925 dentry->d_count--;
2926 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002927 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002928 }
2929 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002930 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002931 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2932 this_parent->d_flags |= DCACHE_GENOCIDE;
2933 this_parent->d_count--;
2934 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002935 this_parent = try_to_ascend(this_parent, locked, seq);
2936 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002937 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002938 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002939 goto resume;
2940 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002941 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002942 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002943 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002944 if (locked)
2945 write_sequnlock(&rename_lock);
2946 return;
2947
2948rename_retry:
2949 locked = 1;
2950 write_seqlock(&rename_lock);
2951 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002952}
2953
2954/**
2955 * find_inode_number - check for dentry with name
2956 * @dir: directory to check
2957 * @name: Name to find.
2958 *
2959 * Check whether a dentry already exists for the given name,
2960 * and return the inode number if it has an inode. Otherwise
2961 * 0 is returned.
2962 *
2963 * This routine is used to post-process directory listings for
2964 * filesystems using synthetic inode numbers, and is necessary
2965 * to keep getcwd() working.
2966 */
2967
2968ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2969{
2970 struct dentry * dentry;
2971 ino_t ino = 0;
2972
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002973 dentry = d_hash_and_lookup(dir, name);
2974 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002975 if (dentry->d_inode)
2976 ino = dentry->d_inode->i_ino;
2977 dput(dentry);
2978 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002979 return ino;
2980}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002981EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002982
2983static __initdata unsigned long dhash_entries;
2984static int __init set_dhash_entries(char *str)
2985{
2986 if (!str)
2987 return 0;
2988 dhash_entries = simple_strtoul(str, &str, 0);
2989 return 1;
2990}
2991__setup("dhash_entries=", set_dhash_entries);
2992
2993static void __init dcache_init_early(void)
2994{
2995 int loop;
2996
2997 /* If hashes are distributed across NUMA nodes, defer
2998 * hash allocation until vmalloc space is available.
2999 */
3000 if (hashdist)
3001 return;
3002
3003 dentry_hashtable =
3004 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003005 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003006 dhash_entries,
3007 13,
3008 HASH_EARLY,
3009 &d_hash_shift,
3010 &d_hash_mask,
3011 0);
3012
3013 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003014 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003015}
3016
Denis Cheng74bf17c2007-10-16 23:26:30 -07003017static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003018{
3019 int loop;
3020
3021 /*
3022 * A constructor could be added for stable state like the lists,
3023 * but it is probably not worth it because of the cache nature
3024 * of the dcache.
3025 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07003026 dentry_cache = KMEM_CACHE(dentry,
3027 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003028
Rusty Russell8e1f9362007-07-17 04:03:17 -07003029 register_shrinker(&dcache_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003030
3031 /* Hash may have been set up in dcache_init_early */
3032 if (!hashdist)
3033 return;
3034
3035 dentry_hashtable =
3036 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003037 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003038 dhash_entries,
3039 13,
3040 0,
3041 &d_hash_shift,
3042 &d_hash_mask,
3043 0);
3044
3045 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003046 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003047}
3048
3049/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08003050struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003051EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003052
Linus Torvalds1da177e2005-04-16 15:20:36 -07003053EXPORT_SYMBOL(d_genocide);
3054
Linus Torvalds1da177e2005-04-16 15:20:36 -07003055void __init vfs_caches_init_early(void)
3056{
3057 dcache_init_early();
3058 inode_init_early();
3059}
3060
3061void __init vfs_caches_init(unsigned long mempages)
3062{
3063 unsigned long reserve;
3064
3065 /* Base hash sizes on available memory, with a reserve equal to
3066 150% of current kernel size */
3067
3068 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3069 mempages -= reserve;
3070
3071 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003072 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003073
Denis Cheng74bf17c2007-10-16 23:26:30 -07003074 dcache_init();
3075 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003076 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003077 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003078 bdev_cache_init();
3079 chrdev_init();
3080}