blob: be18598c7fd7bc78ff5471ea10171225608b92f0 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/dcache.c
3 *
4 * Complete reimplementation
5 * (C) 1997 Thomas Schoebel-Theuer,
6 * with heavy changes by Linus Torvalds
7 */
8
9/*
10 * Notes on the allocation strategy:
11 *
12 * The dcache is a master of the icache - whenever a dcache entry
13 * exists, the inode will always exist. "iput()" is done either when
14 * the dcache entry is deleted or garbage collected.
15 */
16
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/syscalls.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/fs.h>
John McCutchan7a91bf72005-08-08 13:52:16 -040021#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/slab.h>
23#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/hash.h>
25#include <linux/cache.h>
26#include <linux/module.h>
27#include <linux/mount.h>
28#include <linux/file.h>
29#include <asm/uaccess.h>
30#include <linux/security.h>
31#include <linux/seqlock.h>
32#include <linux/swap.h>
33#include <linux/bootmem.h>
Al Viro5ad4e532009-03-29 19:50:06 -040034#include <linux/fs_struct.h>
Frederic Weisbecker613afbf2009-07-16 15:44:29 +020035#include <linux/hardirq.h>
Nick Pigginceb5bdc2011-01-07 17:50:05 +110036#include <linux/bit_spinlock.h>
37#include <linux/rculist_bl.h>
Linus Torvalds268bb0c2011-05-20 12:50:29 -070038#include <linux/prefetch.h>
David Howells07f3f052006-09-30 20:52:18 +020039#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
Nick Piggin789680d2011-01-07 17:49:30 +110041/*
42 * Usage:
Nick Piggin873feea2011-01-07 17:50:06 +110043 * dcache->d_inode->i_lock protects:
44 * - i_dentry, d_alias, d_inode of aliases
Nick Pigginceb5bdc2011-01-07 17:50:05 +110045 * dcache_hash_bucket lock protects:
46 * - the dcache hash table
47 * s_anon bl list spinlock protects:
48 * - the s_anon list (see __d_drop)
Nick Piggin23044502011-01-07 17:49:31 +110049 * dcache_lru_lock protects:
50 * - the dcache lru lists and counters
51 * d_lock protects:
52 * - d_flags
53 * - d_name
54 * - d_lru
Nick Pigginb7ab39f2011-01-07 17:49:32 +110055 * - d_count
Nick Pigginda502952011-01-07 17:49:33 +110056 * - d_unhashed()
Nick Piggin2fd6b7f2011-01-07 17:49:34 +110057 * - d_parent and d_subdirs
58 * - childrens' d_child and d_parent
Nick Pigginb23fb0a2011-01-07 17:49:35 +110059 * - d_alias, d_inode
Nick Piggin789680d2011-01-07 17:49:30 +110060 *
61 * Ordering:
Nick Piggin873feea2011-01-07 17:50:06 +110062 * dentry->d_inode->i_lock
Nick Pigginb5c84bf2011-01-07 17:49:38 +110063 * dentry->d_lock
64 * dcache_lru_lock
Nick Pigginceb5bdc2011-01-07 17:50:05 +110065 * dcache_hash_bucket lock
66 * s_anon lock
Nick Piggin789680d2011-01-07 17:49:30 +110067 *
Nick Pigginda502952011-01-07 17:49:33 +110068 * If there is an ancestor relationship:
69 * dentry->d_parent->...->d_parent->d_lock
70 * ...
71 * dentry->d_parent->d_lock
72 * dentry->d_lock
73 *
74 * If no ancestor relationship:
Nick Piggin789680d2011-01-07 17:49:30 +110075 * if (dentry1 < dentry2)
76 * dentry1->d_lock
77 * dentry2->d_lock
78 */
Eric Dumazetfa3536c2006-03-26 01:37:24 -080079int sysctl_vfs_cache_pressure __read_mostly = 100;
Linus Torvalds1da177e2005-04-16 15:20:36 -070080EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
81
Nick Piggin23044502011-01-07 17:49:31 +110082static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
Al Viro74c3cbe2007-07-22 08:04:18 -040083__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Nick Piggin949854d2011-01-07 17:49:37 +110085EXPORT_SYMBOL(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
Christoph Lametere18b8902006-12-06 20:33:20 -080087static struct kmem_cache *dentry_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
Linus Torvalds1da177e2005-04-16 15:20:36 -070089/*
90 * This is the single most critical data structure when it comes
91 * to the dcache: the hashtable for lookups. Somebody should try
92 * to make this good - I've just made it work.
93 *
94 * This hash-function tries to avoid losing too many bits of hash
95 * information, yet avoid using a prime hash-size or similar.
96 */
97#define D_HASHBITS d_hash_shift
98#define D_HASHMASK d_hash_mask
99
Eric Dumazetfa3536c2006-03-26 01:37:24 -0800100static unsigned int d_hash_mask __read_mostly;
101static unsigned int d_hash_shift __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100102
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700103static struct hlist_bl_head *dentry_hashtable __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100104
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700105static inline struct hlist_bl_head *d_hash(struct dentry *parent,
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100106 unsigned long hash)
107{
108 hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
109 hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
110 return dentry_hashtable + (hash & D_HASHMASK);
111}
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113/* Statistics gathering. */
114struct dentry_stat_t dentry_stat = {
115 .age_limit = 45,
116};
117
Nick Piggin3e880fb2011-01-07 17:49:19 +1100118static DEFINE_PER_CPU(unsigned int, nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400119
120#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Nick Piggin3e880fb2011-01-07 17:49:19 +1100121static int get_nr_dentry(void)
122{
123 int i;
124 int sum = 0;
125 for_each_possible_cpu(i)
126 sum += per_cpu(nr_dentry, i);
127 return sum < 0 ? 0 : sum;
128}
129
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400130int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
131 size_t *lenp, loff_t *ppos)
132{
Nick Piggin3e880fb2011-01-07 17:49:19 +1100133 dentry_stat.nr_dentry = get_nr_dentry();
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400134 return proc_dointvec(table, write, buffer, lenp, ppos);
135}
136#endif
137
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400138static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400140 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
141
Arjan van de Venfd217f42008-10-21 06:47:33 -0700142 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 if (dname_external(dentry))
144 kfree(dentry->d_name.name);
145 kmem_cache_free(dentry_cache, dentry);
146}
147
148/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100149 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 */
151static void d_free(struct dentry *dentry)
152{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100153 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100154 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 if (dentry->d_op && dentry->d_op->d_release)
156 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400157
Linus Torvaldsdea36672011-04-24 07:58:46 -0700158 /* if dentry was never visible to RCU, immediate free is OK */
159 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400160 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800161 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400162 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163}
164
Nick Piggin31e6b012011-01-07 17:49:52 +1100165/**
166 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800167 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100168 * After this call, in-progress rcu-walk path lookup will fail. This
169 * should be called after unhashing, and after changing d_inode (if
170 * the dentry has not already been unhashed).
171 */
172static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
173{
174 assert_spin_locked(&dentry->d_lock);
175 /* Go through a barrier */
176 write_seqcount_barrier(&dentry->d_seq);
177}
178
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179/*
180 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100181 * d_iput() operation if defined. Dentry has no refcount
182 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800184static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200185 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100186 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187{
188 struct inode *inode = dentry->d_inode;
189 if (inode) {
190 dentry->d_inode = NULL;
191 list_del_init(&dentry->d_alias);
192 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100193 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700194 if (!inode->i_nlink)
195 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 if (dentry->d_op && dentry->d_op->d_iput)
197 dentry->d_op->d_iput(dentry, inode);
198 else
199 iput(inode);
200 } else {
201 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 }
203}
204
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700205/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100206 * Release the dentry's inode, using the filesystem
207 * d_iput() operation if defined. dentry remains in-use.
208 */
209static void dentry_unlink_inode(struct dentry * dentry)
210 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100211 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100212{
213 struct inode *inode = dentry->d_inode;
214 dentry->d_inode = NULL;
215 list_del_init(&dentry->d_alias);
216 dentry_rcuwalk_barrier(dentry);
217 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100218 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100219 if (!inode->i_nlink)
220 fsnotify_inoderemove(inode);
221 if (dentry->d_op && dentry->d_op->d_iput)
222 dentry->d_op->d_iput(dentry, inode);
223 else
224 iput(inode);
225}
226
227/*
Nick Piggin23044502011-01-07 17:49:31 +1100228 * dentry_lru_(add|del|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700229 */
230static void dentry_lru_add(struct dentry *dentry)
231{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400232 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100233 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400234 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
235 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100236 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100237 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400238 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700239}
240
Nick Piggin23044502011-01-07 17:49:31 +1100241static void __dentry_lru_del(struct dentry *dentry)
242{
243 list_del_init(&dentry->d_lru);
244 dentry->d_sb->s_nr_dentry_unused--;
245 dentry_stat.nr_unused--;
246}
247
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700248static void dentry_lru_del(struct dentry *dentry)
249{
250 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100251 spin_lock(&dcache_lru_lock);
252 __dentry_lru_del(dentry);
253 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700254 }
255}
256
Christoph Hellwiga4633352010-10-10 05:36:26 -0400257static void dentry_lru_move_tail(struct dentry *dentry)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700258{
Nick Piggin23044502011-01-07 17:49:31 +1100259 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400260 if (list_empty(&dentry->d_lru)) {
261 list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
262 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100263 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400264 } else {
265 list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700266 }
Nick Piggin23044502011-01-07 17:49:31 +1100267 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700268}
269
Miklos Szeredid52b9082007-05-08 00:23:46 -0700270/**
271 * d_kill - kill dentry and return parent
272 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800273 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700274 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200275 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700276 *
277 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100278 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100279 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
280 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700281 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100282static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200283 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100284 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100285 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700286{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700287 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400288 /*
289 * Inform try_to_ascend() that we are no longer attached to the
290 * dentry tree
291 */
292 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100293 if (parent)
294 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700295 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100296 /*
297 * dentry_iput drops the locks, at which point nobody (except
298 * transient RCU lookups) can reach this dentry.
299 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700300 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900301 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700302}
303
Nick Piggin789680d2011-01-07 17:49:30 +1100304/**
305 * d_drop - drop a dentry
306 * @dentry: dentry to drop
307 *
308 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
309 * be found through a VFS lookup any more. Note that this is different from
310 * deleting the dentry - d_delete will try to mark the dentry negative if
311 * possible, giving a successful _negative_ lookup, while d_drop will
312 * just make the cache lookup fail.
313 *
314 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
315 * reason (NFS timeouts or autofs deletes).
316 *
317 * __d_drop requires dentry->d_lock.
318 */
319void __d_drop(struct dentry *dentry)
320{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700321 if (!d_unhashed(dentry)) {
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700322 struct hlist_bl_head *b;
Linus Torvaldsdea36672011-04-24 07:58:46 -0700323 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700324 b = &dentry->d_sb->s_anon;
Linus Torvaldsdea36672011-04-24 07:58:46 -0700325 else
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100326 b = d_hash(dentry->d_parent, dentry->d_name.hash);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700327
Christoph Hellwig1879fd62011-04-25 14:01:36 -0400328 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700329 __hlist_bl_del(&dentry->d_hash);
330 dentry->d_hash.pprev = NULL;
Christoph Hellwig1879fd62011-04-25 14:01:36 -0400331 hlist_bl_unlock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700332
333 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100334 }
335}
336EXPORT_SYMBOL(__d_drop);
337
338void d_drop(struct dentry *dentry)
339{
Nick Piggin789680d2011-01-07 17:49:30 +1100340 spin_lock(&dentry->d_lock);
341 __d_drop(dentry);
342 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100343}
344EXPORT_SYMBOL(d_drop);
345
Nick Piggin77812a12011-01-07 17:49:48 +1100346/*
Josef Bacik44396f42011-05-31 11:58:49 -0400347 * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag
348 * @dentry: dentry to drop
349 *
350 * This is called when we do a lookup on a placeholder dentry that needed to be
351 * looked up. The dentry should have been hashed in order for it to be found by
352 * the lookup code, but now needs to be unhashed while we do the actual lookup
353 * and clear the DCACHE_NEED_LOOKUP flag.
354 */
355void d_clear_need_lookup(struct dentry *dentry)
356{
357 spin_lock(&dentry->d_lock);
358 __d_drop(dentry);
359 dentry->d_flags &= ~DCACHE_NEED_LOOKUP;
360 spin_unlock(&dentry->d_lock);
361}
362EXPORT_SYMBOL(d_clear_need_lookup);
363
364/*
Nick Piggin77812a12011-01-07 17:49:48 +1100365 * Finish off a dentry we've decided to kill.
366 * dentry->d_lock must be held, returns with it unlocked.
367 * If ref is non-zero, then decrement the refcount too.
368 * Returns dentry requiring refcount drop, or NULL if we're done.
369 */
370static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
371 __releases(dentry->d_lock)
372{
Nick Piggin873feea2011-01-07 17:50:06 +1100373 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100374 struct dentry *parent;
375
Nick Piggin873feea2011-01-07 17:50:06 +1100376 inode = dentry->d_inode;
377 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100378relock:
379 spin_unlock(&dentry->d_lock);
380 cpu_relax();
381 return dentry; /* try again with same dentry */
382 }
383 if (IS_ROOT(dentry))
384 parent = NULL;
385 else
386 parent = dentry->d_parent;
387 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100388 if (inode)
389 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100390 goto relock;
391 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100392
Nick Piggin77812a12011-01-07 17:49:48 +1100393 if (ref)
394 dentry->d_count--;
395 /* if dentry was on the d_lru list delete it from there */
396 dentry_lru_del(dentry);
397 /* if it was on the hash then remove it */
398 __d_drop(dentry);
399 return d_kill(dentry, parent);
400}
401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402/*
403 * This is dput
404 *
405 * This is complicated by the fact that we do not want to put
406 * dentries that are no longer on any hash chain on the unused
407 * list: we'd much rather just get rid of them immediately.
408 *
409 * However, that implies that we have to traverse the dentry
410 * tree upwards to the parents which might _also_ now be
411 * scheduled for deletion (it may have been only waiting for
412 * its last child to go away).
413 *
414 * This tail recursion is done by hand as we don't want to depend
415 * on the compiler to always get this right (gcc generally doesn't).
416 * Real recursion would eat up our stack space.
417 */
418
419/*
420 * dput - release a dentry
421 * @dentry: dentry to release
422 *
423 * Release a dentry. This will drop the usage count and if appropriate
424 * call the dentry unlink method as well as removing it from the queues and
425 * releasing its resources. If the parent dentries were scheduled for release
426 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428void dput(struct dentry *dentry)
429{
430 if (!dentry)
431 return;
432
433repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100434 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100437 BUG_ON(!dentry->d_count);
438 if (dentry->d_count > 1) {
439 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 return;
442 }
443
Nick Pigginfb045ad2011-01-07 17:49:55 +1100444 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100446 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 }
Nick Piggin265ac902010-10-10 05:36:24 -0400448
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 /* Unreachable? Get rid of it */
450 if (d_unhashed(dentry))
451 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400452
Josef Bacik44396f42011-05-31 11:58:49 -0400453 /*
454 * If this dentry needs lookup, don't set the referenced flag so that it
455 * is more likely to be cleaned up by the dcache shrinker in case of
456 * memory pressure.
457 */
458 if (!d_need_lookup(dentry))
459 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400460 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400461
Nick Piggin61f3dee2011-01-07 17:49:40 +1100462 dentry->d_count--;
463 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 return;
465
Miklos Szeredid52b9082007-05-08 00:23:46 -0700466kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100467 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700468 if (dentry)
469 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700471EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473/**
474 * d_invalidate - invalidate a dentry
475 * @dentry: dentry to invalidate
476 *
477 * Try to invalidate the dentry if it turns out to be
478 * possible. If there are other dentries that can be
479 * reached through this one we can't delete it and we
480 * return -EBUSY. On success we return 0.
481 *
482 * no dcache lock.
483 */
484
485int d_invalidate(struct dentry * dentry)
486{
487 /*
488 * If it's already been dropped, return OK.
489 */
Nick Pigginda502952011-01-07 17:49:33 +1100490 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100492 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 return 0;
494 }
495 /*
496 * Check whether to do a partial shrink_dcache
497 * to get rid of unused child entries.
498 */
499 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100500 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100502 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 }
504
505 /*
506 * Somebody else still using it?
507 *
508 * If it's a directory, we can't drop it
509 * for fear of somebody re-populating it
510 * with children (even though dropping it
511 * would make it unreachable from the root,
512 * we might still populate it if it was a
513 * working directory or similar).
514 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100515 if (dentry->d_count > 1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) {
517 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 return -EBUSY;
519 }
520 }
521
522 __d_drop(dentry);
523 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 return 0;
525}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700526EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100528/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100529static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100531 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532}
533
Nick Piggindc0474b2011-01-07 17:49:43 +1100534static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100535{
Nick Piggin23044502011-01-07 17:49:31 +1100536 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100537 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100538 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100539}
540
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100541struct dentry *dget_parent(struct dentry *dentry)
542{
543 struct dentry *ret;
544
545repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100546 /*
547 * Don't need rcu_dereference because we re-check it was correct under
548 * the lock.
549 */
550 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100551 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100552 spin_lock(&ret->d_lock);
553 if (unlikely(ret != dentry->d_parent)) {
554 spin_unlock(&ret->d_lock);
555 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100556 goto repeat;
557 }
Nick Piggina734eb42011-01-07 17:49:44 +1100558 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100559 BUG_ON(!ret->d_count);
560 ret->d_count++;
561 spin_unlock(&ret->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100562 return ret;
563}
564EXPORT_SYMBOL(dget_parent);
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566/**
567 * d_find_alias - grab a hashed alias of inode
568 * @inode: inode in question
569 * @want_discon: flag, used by d_splice_alias, to request
570 * that only a DISCONNECTED alias be returned.
571 *
572 * If inode has a hashed alias, or is a directory and has any alias,
573 * acquire the reference to alias and return it. Otherwise return NULL.
574 * Notice that if inode is a directory there can be only one alias and
575 * it can be unhashed only if it has no children, or if it is the root
576 * of a filesystem.
577 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700578 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700580 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 */
Nick Pigginda502952011-01-07 17:49:33 +1100582static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583{
Nick Pigginda502952011-01-07 17:49:33 +1100584 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585
Nick Pigginda502952011-01-07 17:49:33 +1100586again:
587 discon_alias = NULL;
588 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
589 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700591 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100592 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100594 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100595 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100596 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 return alias;
598 }
599 }
Nick Pigginda502952011-01-07 17:49:33 +1100600 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 }
Nick Pigginda502952011-01-07 17:49:33 +1100602 if (discon_alias) {
603 alias = discon_alias;
604 spin_lock(&alias->d_lock);
605 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
606 if (IS_ROOT(alias) &&
607 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100608 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100609 spin_unlock(&alias->d_lock);
610 return alias;
611 }
612 }
613 spin_unlock(&alias->d_lock);
614 goto again;
615 }
616 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617}
618
Nick Pigginda502952011-01-07 17:49:33 +1100619struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620{
David Howells214fda12006-03-25 03:06:36 -0800621 struct dentry *de = NULL;
622
623 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100624 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800625 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100626 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800627 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 return de;
629}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700630EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631
632/*
633 * Try to kill dentries associated with this inode.
634 * WARNING: you must own a reference to inode.
635 */
636void d_prune_aliases(struct inode *inode)
637{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700638 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100640 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700641 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100643 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100644 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 __d_drop(dentry);
646 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100647 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 dput(dentry);
649 goto restart;
650 }
651 spin_unlock(&dentry->d_lock);
652 }
Nick Piggin873feea2011-01-07 17:50:06 +1100653 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700655EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656
657/*
Nick Piggin77812a12011-01-07 17:49:48 +1100658 * Try to throw away a dentry - free the inode, dput the parent.
659 * Requires dentry->d_lock is held, and dentry->d_count == 0.
660 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700661 *
Nick Piggin77812a12011-01-07 17:49:48 +1100662 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 */
Nick Piggin77812a12011-01-07 17:49:48 +1100664static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200665 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666{
Nick Piggin77812a12011-01-07 17:49:48 +1100667 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700668
Nick Piggin77812a12011-01-07 17:49:48 +1100669 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700670 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100671 * If dentry_kill returns NULL, we have nothing more to do.
672 * if it returns the same dentry, trylocks failed. In either
673 * case, just loop again.
674 *
675 * Otherwise, we need to prune ancestors too. This is necessary
676 * to prevent quadratic behavior of shrink_dcache_parent(), but
677 * is also expected to be beneficial in reducing dentry cache
678 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700679 */
Nick Piggin77812a12011-01-07 17:49:48 +1100680 if (!parent)
681 return;
682 if (parent == dentry)
683 return;
684
685 /* Prune ancestors. */
686 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700687 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100688 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100689 if (dentry->d_count > 1) {
690 dentry->d_count--;
691 spin_unlock(&dentry->d_lock);
692 return;
693 }
Nick Piggin77812a12011-01-07 17:49:48 +1100694 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700695 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696}
697
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400698static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700700 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700701
Nick Pigginec336792011-01-07 17:49:47 +1100702 rcu_read_lock();
703 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100704 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
705 if (&dentry->d_lru == list)
706 break; /* empty */
707 spin_lock(&dentry->d_lock);
708 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
709 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100710 continue;
711 }
712
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 /*
714 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700715 * the LRU because of laziness during lookup. Do not free
716 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100718 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100719 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700720 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 continue;
722 }
Nick Pigginec336792011-01-07 17:49:47 +1100723
Nick Pigginec336792011-01-07 17:49:47 +1100724 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100725
726 try_prune_one_dentry(dentry);
727
Nick Pigginec336792011-01-07 17:49:47 +1100728 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 }
Nick Pigginec336792011-01-07 17:49:47 +1100730 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400731}
732
733/**
734 * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
735 * @sb: superblock to shrink dentry LRU.
736 * @count: number of entries to prune
737 * @flags: flags to control the dentry processing
738 *
739 * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
740 */
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000741static void __shrink_dcache_sb(struct super_block *sb, int count, int flags)
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400742{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400743 struct dentry *dentry;
744 LIST_HEAD(referenced);
745 LIST_HEAD(tmp);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400746
Nick Piggin23044502011-01-07 17:49:31 +1100747relock:
748 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400749 while (!list_empty(&sb->s_dentry_lru)) {
750 dentry = list_entry(sb->s_dentry_lru.prev,
751 struct dentry, d_lru);
752 BUG_ON(dentry->d_sb != sb);
753
Nick Piggin23044502011-01-07 17:49:31 +1100754 if (!spin_trylock(&dentry->d_lock)) {
755 spin_unlock(&dcache_lru_lock);
756 cpu_relax();
757 goto relock;
758 }
759
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400760 /*
761 * If we are honouring the DCACHE_REFERENCED flag and the
762 * dentry has this flag set, don't free it. Clear the flag
763 * and put it back on the LRU.
764 */
Nick Piggin23044502011-01-07 17:49:31 +1100765 if (flags & DCACHE_REFERENCED &&
766 dentry->d_flags & DCACHE_REFERENCED) {
767 dentry->d_flags &= ~DCACHE_REFERENCED;
768 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400769 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100770 } else {
771 list_move_tail(&dentry->d_lru, &tmp);
772 spin_unlock(&dentry->d_lock);
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000773 if (!--count)
Nick Piggin23044502011-01-07 17:49:31 +1100774 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400775 }
Nick Pigginec336792011-01-07 17:49:47 +1100776 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400777 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700778 if (!list_empty(&referenced))
779 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100780 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100781
782 shrink_dentry_list(&tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783}
784
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700785/**
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000786 * prune_dcache_sb - shrink the dcache
787 * @nr_to_scan: number of entries to try to free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 *
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000789 * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
790 * done when we need more memory an called from the superblock shrinker
791 * function.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700792 *
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000793 * This function may fail to free any resources if all the dentries are in
794 * use.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 */
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000796void prune_dcache_sb(struct super_block *sb, int nr_to_scan)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700797{
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000798 __shrink_dcache_sb(sb, nr_to_scan, DCACHE_REFERENCED);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700799}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
801/**
802 * shrink_dcache_sb - shrink dcache for a superblock
803 * @sb: superblock
804 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400805 * Shrink the dcache for the specified super block. This is used to free
806 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400808void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400810 LIST_HEAD(tmp);
811
Nick Piggin23044502011-01-07 17:49:31 +1100812 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400813 while (!list_empty(&sb->s_dentry_lru)) {
814 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100815 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400816 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100817 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400818 }
Nick Piggin23044502011-01-07 17:49:31 +1100819 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700821EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822
823/*
David Howellsc636ebd2006-10-11 01:22:19 -0700824 * destroy a single subtree of dentries for unmount
825 * - see the comments on shrink_dcache_for_umount() for a description of the
826 * locking
827 */
828static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
829{
830 struct dentry *parent;
David Howellsf8713572006-10-28 10:38:46 -0700831 unsigned detached = 0;
David Howellsc636ebd2006-10-11 01:22:19 -0700832
833 BUG_ON(!IS_ROOT(dentry));
834
835 /* detach this root from the system */
Nick Piggin23044502011-01-07 17:49:31 +1100836 spin_lock(&dentry->d_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400837 dentry_lru_del(dentry);
David Howellsc636ebd2006-10-11 01:22:19 -0700838 __d_drop(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100839 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700840
841 for (;;) {
842 /* descend to the first leaf in the current subtree */
843 while (!list_empty(&dentry->d_subdirs)) {
844 struct dentry *loop;
845
846 /* this is a branch with children - detach all of them
847 * from the system in one go */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100848 spin_lock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700849 list_for_each_entry(loop, &dentry->d_subdirs,
850 d_u.d_child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100851 spin_lock_nested(&loop->d_lock,
852 DENTRY_D_LOCK_NESTED);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400853 dentry_lru_del(loop);
David Howellsc636ebd2006-10-11 01:22:19 -0700854 __d_drop(loop);
Nick Pigginda502952011-01-07 17:49:33 +1100855 spin_unlock(&loop->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700856 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100857 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700858
859 /* move to the first child */
860 dentry = list_entry(dentry->d_subdirs.next,
861 struct dentry, d_u.d_child);
862 }
863
864 /* consume the dentries from this leaf up through its parents
865 * until we find one with children or run out altogether */
866 do {
867 struct inode *inode;
868
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100869 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700870 printk(KERN_ERR
871 "BUG: Dentry %p{i=%lx,n=%s}"
872 " still in use (%d)"
873 " [unmount of %s %s]\n",
874 dentry,
875 dentry->d_inode ?
876 dentry->d_inode->i_ino : 0UL,
877 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100878 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700879 dentry->d_sb->s_type->name,
880 dentry->d_sb->s_id);
881 BUG();
882 }
883
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100884 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700885 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100886 list_del(&dentry->d_u.d_child);
887 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900888 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100889 spin_lock(&parent->d_lock);
890 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100891 list_del(&dentry->d_u.d_child);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100892 spin_unlock(&parent->d_lock);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900893 }
David Howellsc636ebd2006-10-11 01:22:19 -0700894
David Howellsf8713572006-10-28 10:38:46 -0700895 detached++;
David Howellsc636ebd2006-10-11 01:22:19 -0700896
897 inode = dentry->d_inode;
898 if (inode) {
899 dentry->d_inode = NULL;
900 list_del_init(&dentry->d_alias);
901 if (dentry->d_op && dentry->d_op->d_iput)
902 dentry->d_op->d_iput(dentry, inode);
903 else
904 iput(inode);
905 }
906
907 d_free(dentry);
908
909 /* finished when we fall off the top of the tree,
910 * otherwise we ascend to the parent and move to the
911 * next sibling if there is one */
912 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400913 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700914 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700915 } while (list_empty(&dentry->d_subdirs));
916
917 dentry = list_entry(dentry->d_subdirs.next,
918 struct dentry, d_u.d_child);
919 }
920}
921
922/*
923 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100924 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700925 * - the superblock is detached from all mountings and open files, so the
926 * dentry trees will not be rearranged by the VFS
927 * - s_umount is write-locked, so the memory pressure shrinker will ignore
928 * any dentries belonging to this superblock that it comes across
929 * - the filesystem itself is no longer permitted to rearrange the dentries
930 * in this superblock
931 */
932void shrink_dcache_for_umount(struct super_block *sb)
933{
934 struct dentry *dentry;
935
936 if (down_read_trylock(&sb->s_umount))
937 BUG();
938
939 dentry = sb->s_root;
940 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100941 spin_lock(&dentry->d_lock);
942 dentry->d_count--;
943 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700944 shrink_dcache_for_umount_subtree(dentry);
945
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100946 while (!hlist_bl_empty(&sb->s_anon)) {
947 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700948 shrink_dcache_for_umount_subtree(dentry);
949 }
950}
951
952/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700953 * This tries to ascend one level of parenthood, but
954 * we can race with renaming, so we need to re-check
955 * the parenthood after dropping the lock and check
956 * that the sequence number still matches.
957 */
958static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
959{
960 struct dentry *new = old->d_parent;
961
962 rcu_read_lock();
963 spin_unlock(&old->d_lock);
964 spin_lock(&new->d_lock);
965
966 /*
967 * might go back up the wrong parent if we have had a rename
968 * or deletion
969 */
970 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -0400971 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700972 (!locked && read_seqretry(&rename_lock, seq))) {
973 spin_unlock(&new->d_lock);
974 new = NULL;
975 }
976 rcu_read_unlock();
977 return new;
978}
979
980
981/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 * Search for at least 1 mount point in the dentry's subdirs.
983 * We descend to the next level whenever the d_subdirs
984 * list is non-empty and continue searching.
985 */
986
987/**
988 * have_submounts - check for mounts over a dentry
989 * @parent: dentry to check.
990 *
991 * Return true if the parent or its subdirectories contain
992 * a mount point
993 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994int have_submounts(struct dentry *parent)
995{
Nick Piggin949854d2011-01-07 17:49:37 +1100996 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +1100998 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +1100999 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001000
Nick Piggin949854d2011-01-07 17:49:37 +11001001 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001002again:
1003 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005 if (d_mountpoint(parent))
1006 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001007 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008repeat:
1009 next = this_parent->d_subdirs.next;
1010resume:
1011 while (next != &this_parent->d_subdirs) {
1012 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001013 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001015
1016 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001018 if (d_mountpoint(dentry)) {
1019 spin_unlock(&dentry->d_lock);
1020 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001022 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001024 spin_unlock(&this_parent->d_lock);
1025 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001027 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 goto repeat;
1029 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001030 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031 }
1032 /*
1033 * All done at this level ... ascend and resume the search.
1034 */
1035 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001036 struct dentry *child = this_parent;
1037 this_parent = try_to_ascend(this_parent, locked, seq);
1038 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001039 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001040 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 goto resume;
1042 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001043 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001044 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001045 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001046 if (locked)
1047 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 return 0; /* No mount points found in tree */
1049positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001050 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001051 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001052 if (locked)
1053 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001055
1056rename_retry:
1057 locked = 1;
1058 write_seqlock(&rename_lock);
1059 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001061EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
1063/*
1064 * Search the dentry child list for the specified parent,
1065 * and move any unused dentries to the end of the unused
1066 * list for prune_dcache(). We descend to the next level
1067 * whenever the d_subdirs list is non-empty and continue
1068 * searching.
1069 *
1070 * It returns zero iff there are no unused children,
1071 * otherwise it returns the number of children moved to
1072 * the end of the unused list. This may not be the total
1073 * number of unused children, because select_parent can
1074 * drop the lock and return early due to latency
1075 * constraints.
1076 */
1077static int select_parent(struct dentry * parent)
1078{
Nick Piggin949854d2011-01-07 17:49:37 +11001079 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001081 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001083 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084
Nick Piggin949854d2011-01-07 17:49:37 +11001085 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001086again:
1087 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001088 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089repeat:
1090 next = this_parent->d_subdirs.next;
1091resume:
1092 while (next != &this_parent->d_subdirs) {
1093 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001094 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 next = tmp->next;
1096
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001097 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001098
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 /*
1100 * move only zero ref count dentries to the end
1101 * of the unused list for prune_dcache
1102 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001103 if (!dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001104 dentry_lru_move_tail(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 found++;
Christoph Hellwiga4633352010-10-10 05:36:26 -04001106 } else {
1107 dentry_lru_del(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 }
1109
1110 /*
1111 * We can return to the caller if we have found some (this
1112 * ensures forward progress). We'll be coming back to find
1113 * the rest.
1114 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001115 if (found && need_resched()) {
1116 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117 goto out;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001118 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119
1120 /*
1121 * Descend a level if the d_subdirs list is non-empty.
1122 */
1123 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001124 spin_unlock(&this_parent->d_lock);
1125 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001127 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 goto repeat;
1129 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001130
1131 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 }
1133 /*
1134 * All done at this level ... ascend and resume the search.
1135 */
1136 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001137 struct dentry *child = this_parent;
1138 this_parent = try_to_ascend(this_parent, locked, seq);
1139 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001140 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001141 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 goto resume;
1143 }
1144out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001145 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001146 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001147 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001148 if (locked)
1149 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150 return found;
Nick Piggin58db63d2011-01-07 17:49:39 +11001151
1152rename_retry:
1153 if (found)
1154 return found;
1155 locked = 1;
1156 write_seqlock(&rename_lock);
1157 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158}
1159
1160/**
1161 * shrink_dcache_parent - prune dcache
1162 * @parent: parent of entries to prune
1163 *
1164 * Prune the dcache to remove unused children of the parent dentry.
1165 */
1166
1167void shrink_dcache_parent(struct dentry * parent)
1168{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -07001169 struct super_block *sb = parent->d_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 int found;
1171
1172 while ((found = select_parent(parent)) != 0)
Dave Chinnerb0d40c92011-07-08 14:14:42 +10001173 __shrink_dcache_sb(sb, found, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001175EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177/**
Al Viroa4464db2011-07-07 15:03:58 -04001178 * __d_alloc - allocate a dcache entry
1179 * @sb: filesystem it will belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 * @name: qstr of the name
1181 *
1182 * Allocates a dentry. It returns %NULL if there is insufficient memory
1183 * available. On a success the dentry is returned. The name passed in is
1184 * copied and the copy passed in may be reused after this call.
1185 */
1186
Al Viroa4464db2011-07-07 15:03:58 -04001187struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188{
1189 struct dentry *dentry;
1190 char *dname;
1191
Mel Gormane12ba742007-10-16 01:25:52 -07001192 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 if (!dentry)
1194 return NULL;
1195
1196 if (name->len > DNAME_INLINE_LEN-1) {
1197 dname = kmalloc(name->len + 1, GFP_KERNEL);
1198 if (!dname) {
1199 kmem_cache_free(dentry_cache, dentry);
1200 return NULL;
1201 }
1202 } else {
1203 dname = dentry->d_iname;
1204 }
1205 dentry->d_name.name = dname;
1206
1207 dentry->d_name.len = name->len;
1208 dentry->d_name.hash = name->hash;
1209 memcpy(dname, name->name, name->len);
1210 dname[name->len] = 0;
1211
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001212 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001213 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001215 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 dentry->d_inode = NULL;
Al Viroa4464db2011-07-07 15:03:58 -04001217 dentry->d_parent = dentry;
1218 dentry->d_sb = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 dentry->d_op = NULL;
1220 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001221 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 INIT_LIST_HEAD(&dentry->d_lru);
1223 INIT_LIST_HEAD(&dentry->d_subdirs);
1224 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001225 INIT_LIST_HEAD(&dentry->d_u.d_child);
Al Viroa4464db2011-07-07 15:03:58 -04001226 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227
Nick Piggin3e880fb2011-01-07 17:49:19 +11001228 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001229
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230 return dentry;
1231}
Al Viroa4464db2011-07-07 15:03:58 -04001232
1233/**
1234 * d_alloc - allocate a dcache entry
1235 * @parent: parent of entry to allocate
1236 * @name: qstr of the name
1237 *
1238 * Allocates a dentry. It returns %NULL if there is insufficient memory
1239 * available. On a success the dentry is returned. The name passed in is
1240 * copied and the copy passed in may be reused after this call.
1241 */
1242struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1243{
1244 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1245 if (!dentry)
1246 return NULL;
1247
1248 spin_lock(&parent->d_lock);
1249 /*
1250 * don't need child lock because it is not subject
1251 * to concurrency here
1252 */
1253 __dget_dlock(parent);
1254 dentry->d_parent = parent;
1255 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
1256 spin_unlock(&parent->d_lock);
1257
1258 return dentry;
1259}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001260EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261
Nick Piggin4b936882011-01-07 17:50:07 +11001262struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1263{
Al Viroa4464db2011-07-07 15:03:58 -04001264 struct dentry *dentry = __d_alloc(sb, name);
1265 if (dentry)
Nick Piggin4b936882011-01-07 17:50:07 +11001266 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin4b936882011-01-07 17:50:07 +11001267 return dentry;
1268}
1269EXPORT_SYMBOL(d_alloc_pseudo);
1270
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1272{
1273 struct qstr q;
1274
1275 q.name = name;
1276 q.len = strlen(name);
1277 q.hash = full_name_hash(q.name, q.len);
1278 return d_alloc(parent, &q);
1279}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001280EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281
Nick Pigginfb045ad2011-01-07 17:49:55 +11001282void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1283{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001284 WARN_ON_ONCE(dentry->d_op);
1285 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001286 DCACHE_OP_COMPARE |
1287 DCACHE_OP_REVALIDATE |
1288 DCACHE_OP_DELETE ));
1289 dentry->d_op = op;
1290 if (!op)
1291 return;
1292 if (op->d_hash)
1293 dentry->d_flags |= DCACHE_OP_HASH;
1294 if (op->d_compare)
1295 dentry->d_flags |= DCACHE_OP_COMPARE;
1296 if (op->d_revalidate)
1297 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1298 if (op->d_delete)
1299 dentry->d_flags |= DCACHE_OP_DELETE;
1300
1301}
1302EXPORT_SYMBOL(d_set_d_op);
1303
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001304static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1305{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001306 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001307 if (inode) {
1308 if (unlikely(IS_AUTOMOUNT(inode)))
1309 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001310 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001311 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001312 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001313 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001314 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001315 fsnotify_d_instantiate(dentry, inode);
1316}
1317
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318/**
1319 * d_instantiate - fill in inode information for a dentry
1320 * @entry: dentry to complete
1321 * @inode: inode to attach to this dentry
1322 *
1323 * Fill in inode information in the entry.
1324 *
1325 * This turns negative dentries into productive full members
1326 * of society.
1327 *
1328 * NOTE! This assumes that the inode count has been incremented
1329 * (or otherwise set) by the caller to indicate that it is now
1330 * in use by the dcache.
1331 */
1332
1333void d_instantiate(struct dentry *entry, struct inode * inode)
1334{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001335 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001336 if (inode)
1337 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001338 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001339 if (inode)
1340 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 security_d_instantiate(entry, inode);
1342}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001343EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344
1345/**
1346 * d_instantiate_unique - instantiate a non-aliased dentry
1347 * @entry: dentry to instantiate
1348 * @inode: inode to attach to this dentry
1349 *
1350 * Fill in inode information in the entry. On success, it returns NULL.
1351 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001352 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 *
1354 * Note that in order to avoid conflicts with rename() etc, the caller
1355 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001356 *
1357 * This also assumes that the inode count has been incremented
1358 * (or otherwise set) by the caller to indicate that it is now
1359 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 */
David Howells770bfad2006-08-22 20:06:07 -04001361static struct dentry *__d_instantiate_unique(struct dentry *entry,
1362 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363{
1364 struct dentry *alias;
1365 int len = entry->d_name.len;
1366 const char *name = entry->d_name.name;
1367 unsigned int hash = entry->d_name.hash;
1368
David Howells770bfad2006-08-22 20:06:07 -04001369 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001370 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001371 return NULL;
1372 }
1373
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1375 struct qstr *qstr = &alias->d_name;
1376
Nick Piggin9abca362011-01-07 17:49:36 +11001377 /*
1378 * Don't need alias->d_lock here, because aliases with
1379 * d_parent == entry->d_parent are not subject to name or
1380 * parent changes, because the parent inode i_mutex is held.
1381 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 if (qstr->hash != hash)
1383 continue;
1384 if (alias->d_parent != entry->d_parent)
1385 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001386 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001388 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 return alias;
1390 }
David Howells770bfad2006-08-22 20:06:07 -04001391
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001392 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 return NULL;
1394}
David Howells770bfad2006-08-22 20:06:07 -04001395
1396struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1397{
1398 struct dentry *result;
1399
1400 BUG_ON(!list_empty(&entry->d_alias));
1401
Nick Piggin873feea2011-01-07 17:50:06 +11001402 if (inode)
1403 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001404 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001405 if (inode)
1406 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001407
1408 if (!result) {
1409 security_d_instantiate(entry, inode);
1410 return NULL;
1411 }
1412
1413 BUG_ON(!d_unhashed(result));
1414 iput(inode);
1415 return result;
1416}
1417
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418EXPORT_SYMBOL(d_instantiate_unique);
1419
1420/**
1421 * d_alloc_root - allocate root dentry
1422 * @root_inode: inode to allocate the root for
1423 *
1424 * Allocate a root ("/") dentry for the inode given. The inode is
1425 * instantiated and returned. %NULL is returned if there is insufficient
1426 * memory or the inode passed is %NULL.
1427 */
1428
1429struct dentry * d_alloc_root(struct inode * root_inode)
1430{
1431 struct dentry *res = NULL;
1432
1433 if (root_inode) {
1434 static const struct qstr name = { .name = "/", .len = 1 };
1435
Al Viroa4464db2011-07-07 15:03:58 -04001436 res = __d_alloc(root_inode->i_sb, &name);
1437 if (res)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 d_instantiate(res, root_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 }
1440 return res;
1441}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001442EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001444static struct dentry * __d_find_any_alias(struct inode *inode)
1445{
1446 struct dentry *alias;
1447
1448 if (list_empty(&inode->i_dentry))
1449 return NULL;
1450 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1451 __dget(alias);
1452 return alias;
1453}
1454
1455static struct dentry * d_find_any_alias(struct inode *inode)
1456{
1457 struct dentry *de;
1458
1459 spin_lock(&inode->i_lock);
1460 de = __d_find_any_alias(inode);
1461 spin_unlock(&inode->i_lock);
1462 return de;
1463}
1464
1465
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001467 * d_obtain_alias - find or allocate a dentry for a given inode
1468 * @inode: inode to allocate the dentry for
1469 *
1470 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1471 * similar open by handle operations. The returned dentry may be anonymous,
1472 * or may have a full name (if the inode was already in the cache).
1473 *
1474 * When called on a directory inode, we must ensure that the inode only ever
1475 * has one dentry. If a dentry is found, that is returned instead of
1476 * allocating a new one.
1477 *
1478 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001479 * to the dentry. In case of an error the reference on the inode is released.
1480 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1481 * be passed in and will be the error will be propagate to the return value,
1482 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001483 */
1484struct dentry *d_obtain_alias(struct inode *inode)
1485{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001486 static const struct qstr anonstring = { .name = "" };
1487 struct dentry *tmp;
1488 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001489
1490 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001491 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001492 if (IS_ERR(inode))
1493 return ERR_CAST(inode);
1494
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001495 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001496 if (res)
1497 goto out_iput;
1498
Al Viroa4464db2011-07-07 15:03:58 -04001499 tmp = __d_alloc(inode->i_sb, &anonstring);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001500 if (!tmp) {
1501 res = ERR_PTR(-ENOMEM);
1502 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001503 }
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001504
Nick Piggin873feea2011-01-07 17:50:06 +11001505 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001506 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001507 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001508 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001509 dput(tmp);
1510 goto out_iput;
1511 }
1512
1513 /* attach a disconnected dentry */
1514 spin_lock(&tmp->d_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001515 tmp->d_inode = inode;
1516 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001517 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001518 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001519 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001520 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001521 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001522 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001523 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001524
Christoph Hellwig9308a612008-08-11 15:49:12 +02001525 return tmp;
1526
1527 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001528 if (res && !IS_ERR(res))
1529 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001530 iput(inode);
1531 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001532}
Benny Halevyadc48722009-02-27 14:02:59 -08001533EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534
1535/**
1536 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1537 * @inode: the inode which may have a disconnected dentry
1538 * @dentry: a negative dentry which we want to point to the inode.
1539 *
1540 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1541 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1542 * and return it, else simply d_add the inode to the dentry and return NULL.
1543 *
1544 * This is needed in the lookup routine of any filesystem that is exportable
1545 * (via knfsd) so that we can build dcache paths to directories effectively.
1546 *
1547 * If a dentry was found and moved, then it is returned. Otherwise NULL
1548 * is returned. This matches the expected return value of ->lookup.
1549 *
1550 */
1551struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1552{
1553 struct dentry *new = NULL;
1554
Al Viroa9049372011-07-08 21:20:11 -04001555 if (IS_ERR(inode))
1556 return ERR_CAST(inode);
1557
NeilBrown21c0d8f2006-10-04 02:16:16 -07001558 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001559 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 new = __d_find_alias(inode, 1);
1561 if (new) {
1562 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001563 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 d_move(new, dentry);
1566 iput(inode);
1567 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001568 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001569 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001570 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 security_d_instantiate(dentry, inode);
1572 d_rehash(dentry);
1573 }
1574 } else
1575 d_add(dentry, inode);
1576 return new;
1577}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001578EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
Barry Naujok94035402008-05-21 16:50:46 +10001580/**
1581 * d_add_ci - lookup or allocate new dentry with case-exact name
1582 * @inode: the inode case-insensitive lookup has found
1583 * @dentry: the negative dentry that was passed to the parent's lookup func
1584 * @name: the case-exact name to be associated with the returned dentry
1585 *
1586 * This is to avoid filling the dcache with case-insensitive names to the
1587 * same inode, only the actual correct case is stored in the dcache for
1588 * case-insensitive filesystems.
1589 *
1590 * For a case-insensitive lookup match and if the the case-exact dentry
1591 * already exists in in the dcache, use it and return it.
1592 *
1593 * If no entry exists with the exact case name, allocate new dentry with
1594 * the exact case, and return the spliced entry.
1595 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001596struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001597 struct qstr *name)
1598{
1599 int error;
1600 struct dentry *found;
1601 struct dentry *new;
1602
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001603 /*
1604 * First check if a dentry matching the name already exists,
1605 * if not go ahead and create it now.
1606 */
Barry Naujok94035402008-05-21 16:50:46 +10001607 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001608 if (!found) {
1609 new = d_alloc(dentry->d_parent, name);
1610 if (!new) {
1611 error = -ENOMEM;
1612 goto err_out;
1613 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001614
Barry Naujok94035402008-05-21 16:50:46 +10001615 found = d_splice_alias(inode, new);
1616 if (found) {
1617 dput(new);
1618 return found;
1619 }
1620 return new;
1621 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001622
1623 /*
1624 * If a matching dentry exists, and it's not negative use it.
1625 *
1626 * Decrement the reference count to balance the iget() done
1627 * earlier on.
1628 */
Barry Naujok94035402008-05-21 16:50:46 +10001629 if (found->d_inode) {
1630 if (unlikely(found->d_inode != inode)) {
1631 /* This can't happen because bad inodes are unhashed. */
1632 BUG_ON(!is_bad_inode(inode));
1633 BUG_ON(!is_bad_inode(found->d_inode));
1634 }
Barry Naujok94035402008-05-21 16:50:46 +10001635 iput(inode);
1636 return found;
1637 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001638
Barry Naujok94035402008-05-21 16:50:46 +10001639 /*
Josef Bacik44396f42011-05-31 11:58:49 -04001640 * We are going to instantiate this dentry, unhash it and clear the
1641 * lookup flag so we can do that.
1642 */
1643 if (unlikely(d_need_lookup(found)))
1644 d_clear_need_lookup(found);
1645
1646 /*
Barry Naujok94035402008-05-21 16:50:46 +10001647 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001648 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001649 */
Al Viro4513d892011-07-17 10:52:14 -04001650 new = d_splice_alias(inode, found);
1651 if (new) {
1652 dput(found);
1653 found = new;
Barry Naujok94035402008-05-21 16:50:46 +10001654 }
Al Viro4513d892011-07-17 10:52:14 -04001655 return found;
Barry Naujok94035402008-05-21 16:50:46 +10001656
1657err_out:
1658 iput(inode);
1659 return ERR_PTR(error);
1660}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001661EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662
1663/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001664 * __d_lookup_rcu - search for a dentry (racy, store-free)
1665 * @parent: parent dentry
1666 * @name: qstr of name we wish to find
1667 * @seq: returns d_seq value at the point where the dentry was found
1668 * @inode: returns dentry->d_inode when the inode was found valid.
1669 * Returns: dentry, or NULL
1670 *
1671 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1672 * resolution (store-free path walking) design described in
1673 * Documentation/filesystems/path-lookup.txt.
1674 *
1675 * This is not to be used outside core vfs.
1676 *
1677 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1678 * held, and rcu_read_lock held. The returned dentry must not be stored into
1679 * without taking d_lock and checking d_seq sequence count against @seq
1680 * returned here.
1681 *
1682 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1683 * function.
1684 *
1685 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1686 * the returned dentry, so long as its parent's seqlock is checked after the
1687 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1688 * is formed, giving integrity down the path walk.
1689 */
1690struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
1691 unsigned *seq, struct inode **inode)
1692{
1693 unsigned int len = name->len;
1694 unsigned int hash = name->hash;
1695 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001696 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001697 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001698 struct dentry *dentry;
1699
1700 /*
1701 * Note: There is significant duplication with __d_lookup_rcu which is
1702 * required to prevent single threaded performance regressions
1703 * especially on architectures where smp_rmb (in seqcounts) are costly.
1704 * Keep the two functions in sync.
1705 */
1706
1707 /*
1708 * The hash list is protected using RCU.
1709 *
1710 * Carefully use d_seq when comparing a candidate dentry, to avoid
1711 * races with d_move().
1712 *
1713 * It is possible that concurrent renames can mess up our list
1714 * walk here and result in missing our dentry, resulting in the
1715 * false-negative result. d_lookup() protects against concurrent
1716 * renames using rename_lock seqlock.
1717 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001718 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001719 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001720 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001721 struct inode *i;
1722 const char *tname;
1723 int tlen;
1724
1725 if (dentry->d_name.hash != hash)
1726 continue;
1727
1728seqretry:
1729 *seq = read_seqcount_begin(&dentry->d_seq);
1730 if (dentry->d_parent != parent)
1731 continue;
1732 if (d_unhashed(dentry))
1733 continue;
1734 tlen = dentry->d_name.len;
1735 tname = dentry->d_name.name;
1736 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001737 prefetch(tname);
Nick Piggin31e6b012011-01-07 17:49:52 +11001738 /*
1739 * This seqcount check is required to ensure name and
1740 * len are loaded atomically, so as not to walk off the
1741 * edge of memory when walking. If we could load this
1742 * atomically some other way, we could drop this check.
1743 */
1744 if (read_seqcount_retry(&dentry->d_seq, *seq))
1745 goto seqretry;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001746 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001747 if (parent->d_op->d_compare(parent, *inode,
1748 dentry, i,
1749 tlen, tname, name))
1750 continue;
1751 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001752 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001753 continue;
1754 }
1755 /*
1756 * No extra seqcount check is required after the name
1757 * compare. The caller must perform a seqcount check in
1758 * order to do anything useful with the returned dentry
1759 * anyway.
1760 */
1761 *inode = i;
1762 return dentry;
1763 }
1764 return NULL;
1765}
1766
1767/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 * d_lookup - search for a dentry
1769 * @parent: parent dentry
1770 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001771 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001773 * d_lookup searches the children of the parent dentry for the name in
1774 * question. If the dentry is found its reference count is incremented and the
1775 * dentry is returned. The caller must use dput to free the entry when it has
1776 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001778struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779{
Nick Piggin31e6b012011-01-07 17:49:52 +11001780 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001781 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782
1783 do {
1784 seq = read_seqbegin(&rename_lock);
1785 dentry = __d_lookup(parent, name);
1786 if (dentry)
1787 break;
1788 } while (read_seqretry(&rename_lock, seq));
1789 return dentry;
1790}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001791EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792
Nick Piggin31e6b012011-01-07 17:49:52 +11001793/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001794 * __d_lookup - search for a dentry (racy)
1795 * @parent: parent dentry
1796 * @name: qstr of name we wish to find
1797 * Returns: dentry, or NULL
1798 *
1799 * __d_lookup is like d_lookup, however it may (rarely) return a
1800 * false-negative result due to unrelated rename activity.
1801 *
1802 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1803 * however it must be used carefully, eg. with a following d_lookup in
1804 * the case of failure.
1805 *
1806 * __d_lookup callers must be commented.
1807 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001808struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809{
1810 unsigned int len = name->len;
1811 unsigned int hash = name->hash;
1812 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001813 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001814 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001815 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001816 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817
Nick Pigginb04f7842010-08-18 04:37:34 +10001818 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001819 * Note: There is significant duplication with __d_lookup_rcu which is
1820 * required to prevent single threaded performance regressions
1821 * especially on architectures where smp_rmb (in seqcounts) are costly.
1822 * Keep the two functions in sync.
1823 */
1824
1825 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001826 * The hash list is protected using RCU.
1827 *
1828 * Take d_lock when comparing a candidate dentry, to avoid races
1829 * with d_move().
1830 *
1831 * It is possible that concurrent renames can mess up our list
1832 * walk here and result in missing our dentry, resulting in the
1833 * false-negative result. d_lookup() protects against concurrent
1834 * renames using rename_lock seqlock.
1835 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001836 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001837 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001838 rcu_read_lock();
1839
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001840 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001841 const char *tname;
1842 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 if (dentry->d_name.hash != hash)
1845 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846
1847 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 if (dentry->d_parent != parent)
1849 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001850 if (d_unhashed(dentry))
1851 goto next;
1852
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 /*
1854 * It is safe to compare names since d_move() cannot
1855 * change the qstr (protected by d_lock).
1856 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001857 tlen = dentry->d_name.len;
1858 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001859 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001860 if (parent->d_op->d_compare(parent, parent->d_inode,
1861 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001862 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 goto next;
1864 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001865 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 goto next;
1867 }
1868
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001869 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001870 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 spin_unlock(&dentry->d_lock);
1872 break;
1873next:
1874 spin_unlock(&dentry->d_lock);
1875 }
1876 rcu_read_unlock();
1877
1878 return found;
1879}
1880
1881/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001882 * d_hash_and_lookup - hash the qstr then search for a dentry
1883 * @dir: Directory to search in
1884 * @name: qstr of name we wish to find
1885 *
1886 * On hash failure or on lookup failure NULL is returned.
1887 */
1888struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1889{
1890 struct dentry *dentry = NULL;
1891
1892 /*
1893 * Check for a fs-specific hash function. Note that we must
1894 * calculate the standard hash first, as the d_op->d_hash()
1895 * routine may choose to leave the hash value unchanged.
1896 */
1897 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001898 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001899 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001900 goto out;
1901 }
1902 dentry = d_lookup(dir, name);
1903out:
1904 return dentry;
1905}
1906
1907/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001908 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001910 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911 *
1912 * An insecure source has sent us a dentry, here we verify it and dget() it.
1913 * This is used by ncpfs in its readdir implementation.
1914 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001915 *
1916 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001918int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919{
Nick Piggin786a5e12011-01-07 17:49:16 +11001920 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001921
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001922 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001923 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
1924 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001925 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11001926 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001927 spin_unlock(&dentry->d_lock);
1928 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 return 1;
1930 }
1931 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001932 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001933
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 return 0;
1935}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001936EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937
1938/*
1939 * When a file is deleted, we have two options:
1940 * - turn this dentry into a negative dentry
1941 * - unhash this dentry and free it.
1942 *
1943 * Usually, we want to just turn this into
1944 * a negative dentry, but if anybody else is
1945 * currently using the dentry or the inode
1946 * we can't do that and we fall back on removing
1947 * it from the hash queues and waiting for
1948 * it to be deleted later when it has no users
1949 */
1950
1951/**
1952 * d_delete - delete a dentry
1953 * @dentry: The dentry to delete
1954 *
1955 * Turn the dentry into a negative dentry if possible, otherwise
1956 * remove it from the hash queues so it can be deleted later
1957 */
1958
1959void d_delete(struct dentry * dentry)
1960{
Nick Piggin873feea2011-01-07 17:50:06 +11001961 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04001962 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 /*
1964 * Are we the only user?
1965 */
Nick Piggin357f8e62011-01-07 17:49:42 +11001966again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001968 inode = dentry->d_inode;
1969 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001970 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11001971 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11001972 spin_unlock(&dentry->d_lock);
1973 cpu_relax();
1974 goto again;
1975 }
Al Viro13e3c5e2010-05-21 16:11:04 -04001976 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11001977 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04001978 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 return;
1980 }
1981
1982 if (!d_unhashed(dentry))
1983 __d_drop(dentry);
1984
1985 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04001986
1987 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001989EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001991static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001993 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001994 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07001995 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001996 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001997 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001998}
1999
David Howells770bfad2006-08-22 20:06:07 -04002000static void _d_rehash(struct dentry * entry)
2001{
2002 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2003}
2004
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005/**
2006 * d_rehash - add an entry back to the hash
2007 * @entry: dentry to add to the hash
2008 *
2009 * Adds a dentry to the hash according to its name.
2010 */
2011
2012void d_rehash(struct dentry * entry)
2013{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002015 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002018EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002020/**
2021 * dentry_update_name_case - update case insensitive dentry with a new name
2022 * @dentry: dentry to be updated
2023 * @name: new name
2024 *
2025 * Update a case insensitive dentry with new case of name.
2026 *
2027 * dentry must have been returned by d_lookup with name @name. Old and new
2028 * name lengths must match (ie. no d_compare which allows mismatched name
2029 * lengths).
2030 *
2031 * Parent inode i_mutex must be held over d_lookup and into this call (to
2032 * keep renames and concurrent inserts, and readdir(2) away).
2033 */
2034void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2035{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002036 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002037 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2038
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002039 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002040 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002041 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002042 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002043 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002044}
2045EXPORT_SYMBOL(dentry_update_name_case);
2046
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047static void switch_names(struct dentry *dentry, struct dentry *target)
2048{
2049 if (dname_external(target)) {
2050 if (dname_external(dentry)) {
2051 /*
2052 * Both external: swap the pointers
2053 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002054 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055 } else {
2056 /*
2057 * dentry:internal, target:external. Steal target's
2058 * storage and make target internal.
2059 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002060 memcpy(target->d_iname, dentry->d_name.name,
2061 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062 dentry->d_name.name = target->d_name.name;
2063 target->d_name.name = target->d_iname;
2064 }
2065 } else {
2066 if (dname_external(dentry)) {
2067 /*
2068 * dentry:external, target:internal. Give dentry's
2069 * storage to target and make dentry internal
2070 */
2071 memcpy(dentry->d_iname, target->d_name.name,
2072 target->d_name.len + 1);
2073 target->d_name.name = dentry->d_name.name;
2074 dentry->d_name.name = dentry->d_iname;
2075 } else {
2076 /*
2077 * Both are internal. Just copy target to dentry
2078 */
2079 memcpy(dentry->d_iname, target->d_name.name,
2080 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002081 dentry->d_name.len = target->d_name.len;
2082 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083 }
2084 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002085 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002086}
2087
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002088static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2089{
2090 /*
2091 * XXXX: do we really need to take target->d_lock?
2092 */
2093 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2094 spin_lock(&target->d_parent->d_lock);
2095 else {
2096 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2097 spin_lock(&dentry->d_parent->d_lock);
2098 spin_lock_nested(&target->d_parent->d_lock,
2099 DENTRY_D_LOCK_NESTED);
2100 } else {
2101 spin_lock(&target->d_parent->d_lock);
2102 spin_lock_nested(&dentry->d_parent->d_lock,
2103 DENTRY_D_LOCK_NESTED);
2104 }
2105 }
2106 if (target < dentry) {
2107 spin_lock_nested(&target->d_lock, 2);
2108 spin_lock_nested(&dentry->d_lock, 3);
2109 } else {
2110 spin_lock_nested(&dentry->d_lock, 2);
2111 spin_lock_nested(&target->d_lock, 3);
2112 }
2113}
2114
2115static void dentry_unlock_parents_for_move(struct dentry *dentry,
2116 struct dentry *target)
2117{
2118 if (target->d_parent != dentry->d_parent)
2119 spin_unlock(&dentry->d_parent->d_lock);
2120 if (target->d_parent != target)
2121 spin_unlock(&target->d_parent->d_lock);
2122}
2123
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002125 * When switching names, the actual string doesn't strictly have to
2126 * be preserved in the target - because we're dropping the target
2127 * anyway. As such, we can just do a simple memcpy() to copy over
2128 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002130 * Note that we have to be a lot more careful about getting the hash
2131 * switched - we have to switch the hash value properly even if it
2132 * then no longer matches the actual (corrupted) string of the target.
2133 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002135/*
Al Viro18367502011-07-12 21:42:24 -04002136 * __d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 * @dentry: entry to move
2138 * @target: new dentry
2139 *
2140 * Update the dcache to reflect the move of a file name. Negative
Al Viro18367502011-07-12 21:42:24 -04002141 * dcache entries should not be moved in this way. Caller hold
2142 * rename_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143 */
Al Viro18367502011-07-12 21:42:24 -04002144static void __d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 if (!dentry->d_inode)
2147 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2148
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002149 BUG_ON(d_ancestor(dentry, target));
2150 BUG_ON(d_ancestor(target, dentry));
2151
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002152 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153
Nick Piggin31e6b012011-01-07 17:49:52 +11002154 write_seqcount_begin(&dentry->d_seq);
2155 write_seqcount_begin(&target->d_seq);
2156
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002157 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2158
2159 /*
2160 * Move the dentry to the target hash queue. Don't bother checking
2161 * for the same hash queue because of how unlikely it is.
2162 */
2163 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002164 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165
2166 /* Unhash the target: dput() will then get rid of it */
2167 __d_drop(target);
2168
Eric Dumazet5160ee62006-01-08 01:03:32 -08002169 list_del(&dentry->d_u.d_child);
2170 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171
2172 /* Switch the names.. */
2173 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002174 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175
2176 /* ... and switch the parents */
2177 if (IS_ROOT(dentry)) {
2178 dentry->d_parent = target->d_parent;
2179 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002180 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002182 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183
2184 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002185 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186 }
2187
Eric Dumazet5160ee62006-01-08 01:03:32 -08002188 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002189
Nick Piggin31e6b012011-01-07 17:49:52 +11002190 write_seqcount_end(&target->d_seq);
2191 write_seqcount_end(&dentry->d_seq);
2192
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002193 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002195 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196 spin_unlock(&dentry->d_lock);
Al Viro18367502011-07-12 21:42:24 -04002197}
2198
2199/*
2200 * d_move - move a dentry
2201 * @dentry: entry to move
2202 * @target: new dentry
2203 *
2204 * Update the dcache to reflect the move of a file name. Negative
2205 * dcache entries should not be moved in this way.
2206 */
2207void d_move(struct dentry *dentry, struct dentry *target)
2208{
2209 write_seqlock(&rename_lock);
2210 __d_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002211 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002212}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002213EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002215/**
2216 * d_ancestor - search for an ancestor
2217 * @p1: ancestor dentry
2218 * @p2: child dentry
2219 *
2220 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2221 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002222 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002223struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002224{
2225 struct dentry *p;
2226
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002227 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002228 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002229 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002230 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002231 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002232}
2233
2234/*
2235 * This helper attempts to cope with remotely renamed directories
2236 *
2237 * It assumes that the caller is already holding
Al Viro18367502011-07-12 21:42:24 -04002238 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002239 *
2240 * Note: If ever the locking in lock_rename() changes, then please
2241 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002242 */
Nick Piggin873feea2011-01-07 17:50:06 +11002243static struct dentry *__d_unalias(struct inode *inode,
2244 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002245{
2246 struct mutex *m1 = NULL, *m2 = NULL;
2247 struct dentry *ret;
2248
2249 /* If alias and dentry share a parent, then no extra locks required */
2250 if (alias->d_parent == dentry->d_parent)
2251 goto out_unalias;
2252
Trond Myklebust9eaef272006-10-21 10:24:20 -07002253 /* See lock_rename() */
2254 ret = ERR_PTR(-EBUSY);
2255 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2256 goto out_err;
2257 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2258 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2259 goto out_err;
2260 m2 = &alias->d_parent->d_inode->i_mutex;
2261out_unalias:
Al Viro18367502011-07-12 21:42:24 -04002262 __d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002263 ret = alias;
2264out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002265 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002266 if (m2)
2267 mutex_unlock(m2);
2268 if (m1)
2269 mutex_unlock(m1);
2270 return ret;
2271}
2272
2273/*
David Howells770bfad2006-08-22 20:06:07 -04002274 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2275 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002276 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002277 */
2278static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2279{
2280 struct dentry *dparent, *aparent;
2281
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002282 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002283
Nick Piggin31e6b012011-01-07 17:49:52 +11002284 write_seqcount_begin(&dentry->d_seq);
2285 write_seqcount_begin(&anon->d_seq);
2286
David Howells770bfad2006-08-22 20:06:07 -04002287 dparent = dentry->d_parent;
2288 aparent = anon->d_parent;
2289
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002290 switch_names(dentry, anon);
2291 swap(dentry->d_name.hash, anon->d_name.hash);
2292
David Howells770bfad2006-08-22 20:06:07 -04002293 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2294 list_del(&dentry->d_u.d_child);
2295 if (!IS_ROOT(dentry))
2296 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2297 else
2298 INIT_LIST_HEAD(&dentry->d_u.d_child);
2299
2300 anon->d_parent = (dparent == dentry) ? anon : dparent;
2301 list_del(&anon->d_u.d_child);
2302 if (!IS_ROOT(anon))
2303 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2304 else
2305 INIT_LIST_HEAD(&anon->d_u.d_child);
2306
Nick Piggin31e6b012011-01-07 17:49:52 +11002307 write_seqcount_end(&dentry->d_seq);
2308 write_seqcount_end(&anon->d_seq);
2309
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002310 dentry_unlock_parents_for_move(anon, dentry);
2311 spin_unlock(&dentry->d_lock);
2312
2313 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002314 anon->d_flags &= ~DCACHE_DISCONNECTED;
2315}
2316
2317/**
2318 * d_materialise_unique - introduce an inode into the tree
2319 * @dentry: candidate dentry
2320 * @inode: inode to bind to the dentry, to which aliases may be attached
2321 *
2322 * Introduces an dentry into the tree, substituting an extant disconnected
2323 * root directory alias in its place if there is one
2324 */
2325struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2326{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002327 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002328
2329 BUG_ON(!d_unhashed(dentry));
2330
David Howells770bfad2006-08-22 20:06:07 -04002331 if (!inode) {
2332 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002333 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002334 d_rehash(actual);
2335 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002336 }
2337
Nick Piggin873feea2011-01-07 17:50:06 +11002338 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002339
Trond Myklebust9eaef272006-10-21 10:24:20 -07002340 if (S_ISDIR(inode->i_mode)) {
2341 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002342
Trond Myklebust9eaef272006-10-21 10:24:20 -07002343 /* Does an aliased dentry already exist? */
2344 alias = __d_find_alias(inode, 0);
2345 if (alias) {
2346 actual = alias;
Al Viro18367502011-07-12 21:42:24 -04002347 write_seqlock(&rename_lock);
2348
2349 if (d_ancestor(alias, dentry)) {
2350 /* Check for loops */
2351 actual = ERR_PTR(-ELOOP);
2352 } else if (IS_ROOT(alias)) {
2353 /* Is this an anonymous mountpoint that we
2354 * could splice into our tree? */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002355 __d_materialise_dentry(dentry, alias);
Al Viro18367502011-07-12 21:42:24 -04002356 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002357 __d_drop(alias);
2358 goto found;
Al Viro18367502011-07-12 21:42:24 -04002359 } else {
2360 /* Nope, but we must(!) avoid directory
2361 * aliasing */
2362 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002363 }
Al Viro18367502011-07-12 21:42:24 -04002364 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002365 if (IS_ERR(actual))
2366 dput(alias);
2367 goto out_nolock;
2368 }
David Howells770bfad2006-08-22 20:06:07 -04002369 }
2370
2371 /* Add a unique reference */
2372 actual = __d_instantiate_unique(dentry, inode);
2373 if (!actual)
2374 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002375 else
2376 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002377
David Howells770bfad2006-08-22 20:06:07 -04002378 spin_lock(&actual->d_lock);
2379found:
2380 _d_rehash(actual);
2381 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002382 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002383out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002384 if (actual == dentry) {
2385 security_d_instantiate(dentry, inode);
2386 return NULL;
2387 }
2388
2389 iput(inode);
2390 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002391}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002392EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002393
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002394static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002395{
2396 *buflen -= namelen;
2397 if (*buflen < 0)
2398 return -ENAMETOOLONG;
2399 *buffer -= namelen;
2400 memcpy(*buffer, str, namelen);
2401 return 0;
2402}
2403
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002404static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2405{
2406 return prepend(buffer, buflen, name->name, name->len);
2407}
2408
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002410 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002411 * @path: the dentry/vfsmount to report
2412 * @root: root vfsmnt/dentry (may be modified by this function)
2413 * @buffer: pointer to the end of the buffer
2414 * @buflen: pointer to buffer length
2415 *
Nick Piggin949854d2011-01-07 17:49:37 +11002416 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002417 *
2418 * If path is not reachable from the supplied root, then the value of
2419 * root is changed (without modifying refcounts).
2420 */
2421static int prepend_path(const struct path *path, struct path *root,
2422 char **buffer, int *buflen)
2423{
2424 struct dentry *dentry = path->dentry;
2425 struct vfsmount *vfsmnt = path->mnt;
2426 bool slash = false;
2427 int error = 0;
2428
Nick Piggin99b7db72010-08-18 04:37:39 +10002429 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002430 while (dentry != root->dentry || vfsmnt != root->mnt) {
2431 struct dentry * parent;
2432
2433 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2434 /* Global root? */
2435 if (vfsmnt->mnt_parent == vfsmnt) {
2436 goto global_root;
2437 }
2438 dentry = vfsmnt->mnt_mountpoint;
2439 vfsmnt = vfsmnt->mnt_parent;
2440 continue;
2441 }
2442 parent = dentry->d_parent;
2443 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002444 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002445 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002446 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002447 if (!error)
2448 error = prepend(buffer, buflen, "/", 1);
2449 if (error)
2450 break;
2451
2452 slash = true;
2453 dentry = parent;
2454 }
2455
2456out:
2457 if (!error && !slash)
2458 error = prepend(buffer, buflen, "/", 1);
2459
Nick Piggin99b7db72010-08-18 04:37:39 +10002460 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002461 return error;
2462
2463global_root:
2464 /*
2465 * Filesystems needing to implement special "root names"
2466 * should do so with ->d_dname()
2467 */
2468 if (IS_ROOT(dentry) &&
2469 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2470 WARN(1, "Root dentry has weird name <%.*s>\n",
2471 (int) dentry->d_name.len, dentry->d_name.name);
2472 }
2473 root->mnt = vfsmnt;
2474 root->dentry = dentry;
2475 goto out;
2476}
2477
2478/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002479 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002480 * @path: the dentry/vfsmount to report
2481 * @root: root vfsmnt/dentry (may be modified by this function)
Randy Dunlapcd956a12010-08-14 13:05:31 -07002482 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483 * @buflen: buffer length
2484 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002485 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002486 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002487 * Returns a pointer into the buffer or an error code if the
2488 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002489 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002490 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002491 *
2492 * If path is not reachable from the supplied root, then the value of
2493 * root is changed (without modifying refcounts).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002494 */
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002495char *__d_path(const struct path *path, struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002496 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002498 char *res = buf + buflen;
2499 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002501 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002502 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002503 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002504 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002505
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002506 if (error)
2507 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002508 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002509}
2510
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002511/*
2512 * same as __d_path but appends "(deleted)" for unlinked files.
2513 */
2514static int path_with_deleted(const struct path *path, struct path *root,
2515 char **buf, int *buflen)
2516{
2517 prepend(buf, buflen, "\0", 1);
2518 if (d_unlinked(path->dentry)) {
2519 int error = prepend(buf, buflen, " (deleted)", 10);
2520 if (error)
2521 return error;
2522 }
2523
2524 return prepend_path(path, root, buf, buflen);
2525}
2526
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002527static int prepend_unreachable(char **buffer, int *buflen)
2528{
2529 return prepend(buffer, buflen, "(unreachable)", 13);
2530}
2531
Jan Bluncka03a8a702008-02-14 19:38:32 -08002532/**
2533 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002534 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002535 * @buf: buffer to return value in
2536 * @buflen: buffer length
2537 *
2538 * Convert a dentry into an ASCII path name. If the entry has been deleted
2539 * the string " (deleted)" is appended. Note that this is ambiguous.
2540 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002541 * Returns a pointer into the buffer or an error code if the path was
2542 * too long. Note: Callers should use the returned pointer, not the passed
2543 * in buffer, to use the name! The implementation often starts at an offset
2544 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002545 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002546 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002547 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002548char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002549{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002550 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002551 struct path root;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002552 struct path tmp;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002553 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002554
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002555 /*
2556 * We have various synthetic filesystems that never get mounted. On
2557 * these filesystems dentries are never used for lookup purposes, and
2558 * thus don't need to be hashed. They also don't need a name until a
2559 * user wants to identify the object in /proc/pid/fd/. The little hack
2560 * below allows us to generate a name for these objects on demand:
2561 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002562 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2563 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002564
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002565 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002566 write_seqlock(&rename_lock);
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002567 tmp = root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002568 error = path_with_deleted(path, &tmp, &res, &buflen);
2569 if (error)
2570 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002571 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002572 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573 return res;
2574}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002575EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002576
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002577/**
2578 * d_path_with_unreachable - return the path of a dentry
2579 * @path: path to report
2580 * @buf: buffer to return value in
2581 * @buflen: buffer length
2582 *
2583 * The difference from d_path() is that this prepends "(unreachable)"
2584 * to paths which are unreachable from the current process' root.
2585 */
2586char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2587{
2588 char *res = buf + buflen;
2589 struct path root;
2590 struct path tmp;
2591 int error;
2592
2593 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2594 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2595
2596 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002597 write_seqlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002598 tmp = root;
2599 error = path_with_deleted(path, &tmp, &res, &buflen);
2600 if (!error && !path_equal(&tmp, &root))
2601 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002602 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002603 path_put(&root);
2604 if (error)
2605 res = ERR_PTR(error);
2606
2607 return res;
2608}
2609
Linus Torvalds1da177e2005-04-16 15:20:36 -07002610/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002611 * Helper function for dentry_operations.d_dname() members
2612 */
2613char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2614 const char *fmt, ...)
2615{
2616 va_list args;
2617 char temp[64];
2618 int sz;
2619
2620 va_start(args, fmt);
2621 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2622 va_end(args);
2623
2624 if (sz > sizeof(temp) || sz > buflen)
2625 return ERR_PTR(-ENAMETOOLONG);
2626
2627 buffer += buflen - sz;
2628 return memcpy(buffer, temp, sz);
2629}
2630
2631/*
Ram Pai6092d042008-03-27 13:06:20 +01002632 * Write full pathname from the root of the filesystem into the buffer.
2633 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002634static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002635{
2636 char *end = buf + buflen;
2637 char *retval;
2638
Ram Pai6092d042008-03-27 13:06:20 +01002639 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002640 if (buflen < 1)
2641 goto Elong;
2642 /* Get '/' right */
2643 retval = end-1;
2644 *retval = '/';
2645
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002646 while (!IS_ROOT(dentry)) {
2647 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002648 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002649
Ram Pai6092d042008-03-27 13:06:20 +01002650 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002651 spin_lock(&dentry->d_lock);
2652 error = prepend_name(&end, &buflen, &dentry->d_name);
2653 spin_unlock(&dentry->d_lock);
2654 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002655 goto Elong;
2656
2657 retval = end;
2658 dentry = parent;
2659 }
Al Viroc1031352010-06-06 22:31:14 -04002660 return retval;
2661Elong:
2662 return ERR_PTR(-ENAMETOOLONG);
2663}
Nick Pigginec2447c2011-01-07 17:49:29 +11002664
2665char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2666{
2667 char *retval;
2668
Nick Piggin949854d2011-01-07 17:49:37 +11002669 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002670 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002671 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002672
2673 return retval;
2674}
2675EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002676
2677char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2678{
2679 char *p = NULL;
2680 char *retval;
2681
Nick Piggin949854d2011-01-07 17:49:37 +11002682 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002683 if (d_unlinked(dentry)) {
2684 p = buf + buflen;
2685 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2686 goto Elong;
2687 buflen++;
2688 }
2689 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002690 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002691 if (!IS_ERR(retval) && p)
2692 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002693 return retval;
2694Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002695 return ERR_PTR(-ENAMETOOLONG);
2696}
2697
2698/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002699 * NOTE! The user-level library version returns a
2700 * character pointer. The kernel system call just
2701 * returns the length of the buffer filled (which
2702 * includes the ending '\0' character), or a negative
2703 * error value. So libc would do something like
2704 *
2705 * char *getcwd(char * buf, size_t size)
2706 * {
2707 * int retval;
2708 *
2709 * retval = sys_getcwd(buf, size);
2710 * if (retval >= 0)
2711 * return buf;
2712 * errno = -retval;
2713 * return NULL;
2714 * }
2715 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002716SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717{
Linus Torvalds552ce542007-02-13 12:08:18 -08002718 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002719 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002720 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002721
2722 if (!page)
2723 return -ENOMEM;
2724
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002725 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002726
Linus Torvalds552ce542007-02-13 12:08:18 -08002727 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002728 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002729 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002730 unsigned long len;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002731 struct path tmp = root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002732 char *cwd = page + PAGE_SIZE;
2733 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002735 prepend(&cwd, &buflen, "\0", 1);
2736 error = prepend_path(&pwd, &tmp, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002737 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002738
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002739 if (error)
Linus Torvalds552ce542007-02-13 12:08:18 -08002740 goto out;
2741
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002742 /* Unreachable from current root */
2743 if (!path_equal(&tmp, &root)) {
2744 error = prepend_unreachable(&cwd, &buflen);
2745 if (error)
2746 goto out;
2747 }
2748
Linus Torvalds552ce542007-02-13 12:08:18 -08002749 error = -ERANGE;
2750 len = PAGE_SIZE + page - cwd;
2751 if (len <= size) {
2752 error = len;
2753 if (copy_to_user(buf, cwd, len))
2754 error = -EFAULT;
2755 }
Nick Piggin949854d2011-01-07 17:49:37 +11002756 } else {
2757 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002758 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002759
2760out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002761 path_put(&pwd);
2762 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002763 free_page((unsigned long) page);
2764 return error;
2765}
2766
2767/*
2768 * Test whether new_dentry is a subdirectory of old_dentry.
2769 *
2770 * Trivially implemented using the dcache structure
2771 */
2772
2773/**
2774 * is_subdir - is new dentry a subdirectory of old_dentry
2775 * @new_dentry: new dentry
2776 * @old_dentry: old dentry
2777 *
2778 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2779 * Returns 0 otherwise.
2780 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2781 */
2782
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002783int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002784{
2785 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002786 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002787
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002788 if (new_dentry == old_dentry)
2789 return 1;
2790
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002791 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002793 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002794 /*
2795 * Need rcu_readlock to protect against the d_parent trashing
2796 * due to d_move
2797 */
2798 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002799 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002801 else
2802 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002803 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002804 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002805
2806 return result;
2807}
2808
Al Viro2096f752010-01-30 13:16:21 -05002809int path_is_under(struct path *path1, struct path *path2)
2810{
2811 struct vfsmount *mnt = path1->mnt;
2812 struct dentry *dentry = path1->dentry;
2813 int res;
Nick Piggin99b7db72010-08-18 04:37:39 +10002814
2815 br_read_lock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002816 if (mnt != path2->mnt) {
2817 for (;;) {
2818 if (mnt->mnt_parent == mnt) {
Nick Piggin99b7db72010-08-18 04:37:39 +10002819 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002820 return 0;
2821 }
2822 if (mnt->mnt_parent == path2->mnt)
2823 break;
2824 mnt = mnt->mnt_parent;
2825 }
2826 dentry = mnt->mnt_mountpoint;
2827 }
2828 res = is_subdir(dentry, path2->dentry);
Nick Piggin99b7db72010-08-18 04:37:39 +10002829 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002830 return res;
2831}
2832EXPORT_SYMBOL(path_is_under);
2833
Linus Torvalds1da177e2005-04-16 15:20:36 -07002834void d_genocide(struct dentry *root)
2835{
Nick Piggin949854d2011-01-07 17:49:37 +11002836 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002837 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002838 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002839 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002840
Nick Piggin949854d2011-01-07 17:49:37 +11002841 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002842again:
2843 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002844 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845repeat:
2846 next = this_parent->d_subdirs.next;
2847resume:
2848 while (next != &this_parent->d_subdirs) {
2849 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002850 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002851 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002852
Nick Pigginda502952011-01-07 17:49:33 +11002853 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2854 if (d_unhashed(dentry) || !dentry->d_inode) {
2855 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002856 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002857 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002859 spin_unlock(&this_parent->d_lock);
2860 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002861 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002862 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002863 goto repeat;
2864 }
Nick Piggin949854d2011-01-07 17:49:37 +11002865 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2866 dentry->d_flags |= DCACHE_GENOCIDE;
2867 dentry->d_count--;
2868 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002869 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002870 }
2871 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002872 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002873 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2874 this_parent->d_flags |= DCACHE_GENOCIDE;
2875 this_parent->d_count--;
2876 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002877 this_parent = try_to_ascend(this_parent, locked, seq);
2878 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002879 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002880 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002881 goto resume;
2882 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002883 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002884 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002885 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002886 if (locked)
2887 write_sequnlock(&rename_lock);
2888 return;
2889
2890rename_retry:
2891 locked = 1;
2892 write_seqlock(&rename_lock);
2893 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002894}
2895
2896/**
2897 * find_inode_number - check for dentry with name
2898 * @dir: directory to check
2899 * @name: Name to find.
2900 *
2901 * Check whether a dentry already exists for the given name,
2902 * and return the inode number if it has an inode. Otherwise
2903 * 0 is returned.
2904 *
2905 * This routine is used to post-process directory listings for
2906 * filesystems using synthetic inode numbers, and is necessary
2907 * to keep getcwd() working.
2908 */
2909
2910ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2911{
2912 struct dentry * dentry;
2913 ino_t ino = 0;
2914
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002915 dentry = d_hash_and_lookup(dir, name);
2916 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002917 if (dentry->d_inode)
2918 ino = dentry->d_inode->i_ino;
2919 dput(dentry);
2920 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002921 return ino;
2922}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002923EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002924
2925static __initdata unsigned long dhash_entries;
2926static int __init set_dhash_entries(char *str)
2927{
2928 if (!str)
2929 return 0;
2930 dhash_entries = simple_strtoul(str, &str, 0);
2931 return 1;
2932}
2933__setup("dhash_entries=", set_dhash_entries);
2934
2935static void __init dcache_init_early(void)
2936{
2937 int loop;
2938
2939 /* If hashes are distributed across NUMA nodes, defer
2940 * hash allocation until vmalloc space is available.
2941 */
2942 if (hashdist)
2943 return;
2944
2945 dentry_hashtable =
2946 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002947 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07002948 dhash_entries,
2949 13,
2950 HASH_EARLY,
2951 &d_hash_shift,
2952 &d_hash_mask,
2953 0);
2954
2955 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002956 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002957}
2958
Denis Cheng74bf17c2007-10-16 23:26:30 -07002959static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960{
2961 int loop;
2962
2963 /*
2964 * A constructor could be added for stable state like the lists,
2965 * but it is probably not worth it because of the cache nature
2966 * of the dcache.
2967 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07002968 dentry_cache = KMEM_CACHE(dentry,
2969 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002970
2971 /* Hash may have been set up in dcache_init_early */
2972 if (!hashdist)
2973 return;
2974
2975 dentry_hashtable =
2976 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002977 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978 dhash_entries,
2979 13,
2980 0,
2981 &d_hash_shift,
2982 &d_hash_mask,
2983 0);
2984
2985 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002986 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002987}
2988
2989/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08002990struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002991EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002992
Linus Torvalds1da177e2005-04-16 15:20:36 -07002993EXPORT_SYMBOL(d_genocide);
2994
Linus Torvalds1da177e2005-04-16 15:20:36 -07002995void __init vfs_caches_init_early(void)
2996{
2997 dcache_init_early();
2998 inode_init_early();
2999}
3000
3001void __init vfs_caches_init(unsigned long mempages)
3002{
3003 unsigned long reserve;
3004
3005 /* Base hash sizes on available memory, with a reserve equal to
3006 150% of current kernel size */
3007
3008 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3009 mempages -= reserve;
3010
3011 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003012 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003013
Denis Cheng74bf17c2007-10-16 23:26:30 -07003014 dcache_init();
3015 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003016 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003017 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003018 bdev_cache_init();
3019 chrdev_init();
3020}