blob: 616fedff011a7080c36b6446a33b3479c9c7e7d9 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/dcache.c
3 *
4 * Complete reimplementation
5 * (C) 1997 Thomas Schoebel-Theuer,
6 * with heavy changes by Linus Torvalds
7 */
8
9/*
10 * Notes on the allocation strategy:
11 *
12 * The dcache is a master of the icache - whenever a dcache entry
13 * exists, the inode will always exist. "iput()" is done either when
14 * the dcache entry is deleted or garbage collected.
15 */
16
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/syscalls.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/fs.h>
John McCutchan7a91bf72005-08-08 13:52:16 -040021#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/slab.h>
23#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/hash.h>
25#include <linux/cache.h>
26#include <linux/module.h>
27#include <linux/mount.h>
28#include <linux/file.h>
29#include <asm/uaccess.h>
30#include <linux/security.h>
31#include <linux/seqlock.h>
32#include <linux/swap.h>
33#include <linux/bootmem.h>
Al Viro5ad4e532009-03-29 19:50:06 -040034#include <linux/fs_struct.h>
Frederic Weisbecker613afbf2009-07-16 15:44:29 +020035#include <linux/hardirq.h>
Nick Pigginceb5bdc2011-01-07 17:50:05 +110036#include <linux/bit_spinlock.h>
37#include <linux/rculist_bl.h>
Linus Torvalds268bb0c2011-05-20 12:50:29 -070038#include <linux/prefetch.h>
David Howellsdd179942011-08-16 15:31:30 +010039#include <linux/ratelimit.h>
David Howells07f3f052006-09-30 20:52:18 +020040#include "internal.h"
Al Virob2dba1a2011-11-23 19:26:23 -050041#include "mount.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Nick Piggin789680d2011-01-07 17:49:30 +110043/*
44 * Usage:
Nick Piggin873feea2011-01-07 17:50:06 +110045 * dcache->d_inode->i_lock protects:
46 * - i_dentry, d_alias, d_inode of aliases
Nick Pigginceb5bdc2011-01-07 17:50:05 +110047 * dcache_hash_bucket lock protects:
48 * - the dcache hash table
49 * s_anon bl list spinlock protects:
50 * - the s_anon list (see __d_drop)
Nick Piggin23044502011-01-07 17:49:31 +110051 * dcache_lru_lock protects:
52 * - the dcache lru lists and counters
53 * d_lock protects:
54 * - d_flags
55 * - d_name
56 * - d_lru
Nick Pigginb7ab39f2011-01-07 17:49:32 +110057 * - d_count
Nick Pigginda502952011-01-07 17:49:33 +110058 * - d_unhashed()
Nick Piggin2fd6b7f2011-01-07 17:49:34 +110059 * - d_parent and d_subdirs
60 * - childrens' d_child and d_parent
Nick Pigginb23fb0a2011-01-07 17:49:35 +110061 * - d_alias, d_inode
Nick Piggin789680d2011-01-07 17:49:30 +110062 *
63 * Ordering:
Nick Piggin873feea2011-01-07 17:50:06 +110064 * dentry->d_inode->i_lock
Nick Pigginb5c84bf2011-01-07 17:49:38 +110065 * dentry->d_lock
66 * dcache_lru_lock
Nick Pigginceb5bdc2011-01-07 17:50:05 +110067 * dcache_hash_bucket lock
68 * s_anon lock
Nick Piggin789680d2011-01-07 17:49:30 +110069 *
Nick Pigginda502952011-01-07 17:49:33 +110070 * If there is an ancestor relationship:
71 * dentry->d_parent->...->d_parent->d_lock
72 * ...
73 * dentry->d_parent->d_lock
74 * dentry->d_lock
75 *
76 * If no ancestor relationship:
Nick Piggin789680d2011-01-07 17:49:30 +110077 * if (dentry1 < dentry2)
78 * dentry1->d_lock
79 * dentry2->d_lock
80 */
Eric Dumazetfa3536c2006-03-26 01:37:24 -080081int sysctl_vfs_cache_pressure __read_mostly = 100;
Linus Torvalds1da177e2005-04-16 15:20:36 -070082EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
83
Nick Piggin23044502011-01-07 17:49:31 +110084static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
Al Viro74c3cbe2007-07-22 08:04:18 -040085__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
Nick Piggin949854d2011-01-07 17:49:37 +110087EXPORT_SYMBOL(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
Christoph Lametere18b8902006-12-06 20:33:20 -080089static struct kmem_cache *dentry_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Linus Torvalds1da177e2005-04-16 15:20:36 -070091/*
92 * This is the single most critical data structure when it comes
93 * to the dcache: the hashtable for lookups. Somebody should try
94 * to make this good - I've just made it work.
95 *
96 * This hash-function tries to avoid losing too many bits of hash
97 * information, yet avoid using a prime hash-size or similar.
98 */
99#define D_HASHBITS d_hash_shift
100#define D_HASHMASK d_hash_mask
101
Eric Dumazetfa3536c2006-03-26 01:37:24 -0800102static unsigned int d_hash_mask __read_mostly;
103static unsigned int d_hash_shift __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100104
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700105static struct hlist_bl_head *dentry_hashtable __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100106
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700107static inline struct hlist_bl_head *d_hash(struct dentry *parent,
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100108 unsigned long hash)
109{
110 hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
111 hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
112 return dentry_hashtable + (hash & D_HASHMASK);
113}
114
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115/* Statistics gathering. */
116struct dentry_stat_t dentry_stat = {
117 .age_limit = 45,
118};
119
Nick Piggin3e880fb2011-01-07 17:49:19 +1100120static DEFINE_PER_CPU(unsigned int, nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400121
122#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Nick Piggin3e880fb2011-01-07 17:49:19 +1100123static int get_nr_dentry(void)
124{
125 int i;
126 int sum = 0;
127 for_each_possible_cpu(i)
128 sum += per_cpu(nr_dentry, i);
129 return sum < 0 ? 0 : sum;
130}
131
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400132int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
133 size_t *lenp, loff_t *ppos)
134{
Nick Piggin3e880fb2011-01-07 17:49:19 +1100135 dentry_stat.nr_dentry = get_nr_dentry();
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400136 return proc_dointvec(table, write, buffer, lenp, ppos);
137}
138#endif
139
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400140static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400142 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
143
Arjan van de Venfd217f42008-10-21 06:47:33 -0700144 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 if (dname_external(dentry))
146 kfree(dentry->d_name.name);
147 kmem_cache_free(dentry_cache, dentry);
148}
149
150/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100151 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 */
153static void d_free(struct dentry *dentry)
154{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100155 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100156 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 if (dentry->d_op && dentry->d_op->d_release)
158 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400159
Linus Torvaldsdea36672011-04-24 07:58:46 -0700160 /* if dentry was never visible to RCU, immediate free is OK */
161 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400162 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800163 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400164 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165}
166
Nick Piggin31e6b012011-01-07 17:49:52 +1100167/**
168 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800169 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100170 * After this call, in-progress rcu-walk path lookup will fail. This
171 * should be called after unhashing, and after changing d_inode (if
172 * the dentry has not already been unhashed).
173 */
174static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
175{
176 assert_spin_locked(&dentry->d_lock);
177 /* Go through a barrier */
178 write_seqcount_barrier(&dentry->d_seq);
179}
180
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181/*
182 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100183 * d_iput() operation if defined. Dentry has no refcount
184 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800186static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200187 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100188 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189{
190 struct inode *inode = dentry->d_inode;
191 if (inode) {
192 dentry->d_inode = NULL;
193 list_del_init(&dentry->d_alias);
194 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100195 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700196 if (!inode->i_nlink)
197 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 if (dentry->d_op && dentry->d_op->d_iput)
199 dentry->d_op->d_iput(dentry, inode);
200 else
201 iput(inode);
202 } else {
203 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 }
205}
206
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700207/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100208 * Release the dentry's inode, using the filesystem
209 * d_iput() operation if defined. dentry remains in-use.
210 */
211static void dentry_unlink_inode(struct dentry * dentry)
212 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100213 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100214{
215 struct inode *inode = dentry->d_inode;
216 dentry->d_inode = NULL;
217 list_del_init(&dentry->d_alias);
218 dentry_rcuwalk_barrier(dentry);
219 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100220 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100221 if (!inode->i_nlink)
222 fsnotify_inoderemove(inode);
223 if (dentry->d_op && dentry->d_op->d_iput)
224 dentry->d_op->d_iput(dentry, inode);
225 else
226 iput(inode);
227}
228
229/*
Sage Weilf0023bc2011-10-28 10:02:42 -0700230 * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700231 */
232static void dentry_lru_add(struct dentry *dentry)
233{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400234 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100235 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400236 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
237 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100238 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100239 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400240 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700241}
242
Nick Piggin23044502011-01-07 17:49:31 +1100243static void __dentry_lru_del(struct dentry *dentry)
244{
245 list_del_init(&dentry->d_lru);
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100246 dentry->d_flags &= ~DCACHE_SHRINK_LIST;
Nick Piggin23044502011-01-07 17:49:31 +1100247 dentry->d_sb->s_nr_dentry_unused--;
248 dentry_stat.nr_unused--;
249}
250
Sage Weilf0023bc2011-10-28 10:02:42 -0700251/*
252 * Remove a dentry with references from the LRU.
253 */
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700254static void dentry_lru_del(struct dentry *dentry)
255{
256 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100257 spin_lock(&dcache_lru_lock);
258 __dentry_lru_del(dentry);
259 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700260 }
261}
262
Sage Weilf0023bc2011-10-28 10:02:42 -0700263/*
264 * Remove a dentry that is unreferenced and about to be pruned
265 * (unhashed and destroyed) from the LRU, and inform the file system.
266 * This wrapper should be called _prior_ to unhashing a victim dentry.
267 */
268static void dentry_lru_prune(struct dentry *dentry)
269{
270 if (!list_empty(&dentry->d_lru)) {
271 if (dentry->d_flags & DCACHE_OP_PRUNE)
272 dentry->d_op->d_prune(dentry);
273
274 spin_lock(&dcache_lru_lock);
275 __dentry_lru_del(dentry);
276 spin_unlock(&dcache_lru_lock);
277 }
278}
279
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000280static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700281{
Nick Piggin23044502011-01-07 17:49:31 +1100282 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400283 if (list_empty(&dentry->d_lru)) {
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000284 list_add_tail(&dentry->d_lru, list);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400285 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100286 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400287 } else {
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000288 list_move_tail(&dentry->d_lru, list);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700289 }
Nick Piggin23044502011-01-07 17:49:31 +1100290 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700291}
292
Miklos Szeredid52b9082007-05-08 00:23:46 -0700293/**
294 * d_kill - kill dentry and return parent
295 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800296 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700297 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200298 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700299 *
300 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100301 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100302 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
303 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700304 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100305static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200306 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100307 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100308 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700309{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700310 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400311 /*
312 * Inform try_to_ascend() that we are no longer attached to the
313 * dentry tree
314 */
315 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100316 if (parent)
317 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700318 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100319 /*
320 * dentry_iput drops the locks, at which point nobody (except
321 * transient RCU lookups) can reach this dentry.
322 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700323 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900324 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700325}
326
David Howellsc6627c62011-06-07 14:09:20 +0100327/*
328 * Unhash a dentry without inserting an RCU walk barrier or checking that
329 * dentry->d_lock is locked. The caller must take care of that, if
330 * appropriate.
331 */
332static void __d_shrink(struct dentry *dentry)
333{
334 if (!d_unhashed(dentry)) {
335 struct hlist_bl_head *b;
336 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
337 b = &dentry->d_sb->s_anon;
338 else
339 b = d_hash(dentry->d_parent, dentry->d_name.hash);
340
341 hlist_bl_lock(b);
342 __hlist_bl_del(&dentry->d_hash);
343 dentry->d_hash.pprev = NULL;
344 hlist_bl_unlock(b);
345 }
346}
347
Nick Piggin789680d2011-01-07 17:49:30 +1100348/**
349 * d_drop - drop a dentry
350 * @dentry: dentry to drop
351 *
352 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
353 * be found through a VFS lookup any more. Note that this is different from
354 * deleting the dentry - d_delete will try to mark the dentry negative if
355 * possible, giving a successful _negative_ lookup, while d_drop will
356 * just make the cache lookup fail.
357 *
358 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
359 * reason (NFS timeouts or autofs deletes).
360 *
361 * __d_drop requires dentry->d_lock.
362 */
363void __d_drop(struct dentry *dentry)
364{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700365 if (!d_unhashed(dentry)) {
David Howellsc6627c62011-06-07 14:09:20 +0100366 __d_shrink(dentry);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700367 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100368 }
369}
370EXPORT_SYMBOL(__d_drop);
371
372void d_drop(struct dentry *dentry)
373{
Nick Piggin789680d2011-01-07 17:49:30 +1100374 spin_lock(&dentry->d_lock);
375 __d_drop(dentry);
376 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100377}
378EXPORT_SYMBOL(d_drop);
379
Nick Piggin77812a12011-01-07 17:49:48 +1100380/*
Josef Bacik44396f42011-05-31 11:58:49 -0400381 * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag
382 * @dentry: dentry to drop
383 *
384 * This is called when we do a lookup on a placeholder dentry that needed to be
385 * looked up. The dentry should have been hashed in order for it to be found by
386 * the lookup code, but now needs to be unhashed while we do the actual lookup
387 * and clear the DCACHE_NEED_LOOKUP flag.
388 */
389void d_clear_need_lookup(struct dentry *dentry)
390{
391 spin_lock(&dentry->d_lock);
392 __d_drop(dentry);
393 dentry->d_flags &= ~DCACHE_NEED_LOOKUP;
394 spin_unlock(&dentry->d_lock);
395}
396EXPORT_SYMBOL(d_clear_need_lookup);
397
398/*
Nick Piggin77812a12011-01-07 17:49:48 +1100399 * Finish off a dentry we've decided to kill.
400 * dentry->d_lock must be held, returns with it unlocked.
401 * If ref is non-zero, then decrement the refcount too.
402 * Returns dentry requiring refcount drop, or NULL if we're done.
403 */
404static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
405 __releases(dentry->d_lock)
406{
Nick Piggin873feea2011-01-07 17:50:06 +1100407 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100408 struct dentry *parent;
409
Nick Piggin873feea2011-01-07 17:50:06 +1100410 inode = dentry->d_inode;
411 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100412relock:
413 spin_unlock(&dentry->d_lock);
414 cpu_relax();
415 return dentry; /* try again with same dentry */
416 }
417 if (IS_ROOT(dentry))
418 parent = NULL;
419 else
420 parent = dentry->d_parent;
421 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100422 if (inode)
423 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100424 goto relock;
425 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100426
Nick Piggin77812a12011-01-07 17:49:48 +1100427 if (ref)
428 dentry->d_count--;
Sage Weilf0023bc2011-10-28 10:02:42 -0700429 /*
430 * if dentry was on the d_lru list delete it from there.
431 * inform the fs via d_prune that this dentry is about to be
432 * unhashed and destroyed.
433 */
434 dentry_lru_prune(dentry);
Nick Piggin77812a12011-01-07 17:49:48 +1100435 /* if it was on the hash then remove it */
436 __d_drop(dentry);
437 return d_kill(dentry, parent);
438}
439
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440/*
441 * This is dput
442 *
443 * This is complicated by the fact that we do not want to put
444 * dentries that are no longer on any hash chain on the unused
445 * list: we'd much rather just get rid of them immediately.
446 *
447 * However, that implies that we have to traverse the dentry
448 * tree upwards to the parents which might _also_ now be
449 * scheduled for deletion (it may have been only waiting for
450 * its last child to go away).
451 *
452 * This tail recursion is done by hand as we don't want to depend
453 * on the compiler to always get this right (gcc generally doesn't).
454 * Real recursion would eat up our stack space.
455 */
456
457/*
458 * dput - release a dentry
459 * @dentry: dentry to release
460 *
461 * Release a dentry. This will drop the usage count and if appropriate
462 * call the dentry unlink method as well as removing it from the queues and
463 * releasing its resources. If the parent dentries were scheduled for release
464 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466void dput(struct dentry *dentry)
467{
468 if (!dentry)
469 return;
470
471repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100472 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100475 BUG_ON(!dentry->d_count);
476 if (dentry->d_count > 1) {
477 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 return;
480 }
481
Nick Pigginfb045ad2011-01-07 17:49:55 +1100482 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100484 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 }
Nick Piggin265ac902010-10-10 05:36:24 -0400486
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 /* Unreachable? Get rid of it */
488 if (d_unhashed(dentry))
489 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400490
Josef Bacik44396f42011-05-31 11:58:49 -0400491 /*
492 * If this dentry needs lookup, don't set the referenced flag so that it
493 * is more likely to be cleaned up by the dcache shrinker in case of
494 * memory pressure.
495 */
496 if (!d_need_lookup(dentry))
497 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400498 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400499
Nick Piggin61f3dee2011-01-07 17:49:40 +1100500 dentry->d_count--;
501 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 return;
503
Miklos Szeredid52b9082007-05-08 00:23:46 -0700504kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100505 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700506 if (dentry)
507 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700509EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510
511/**
512 * d_invalidate - invalidate a dentry
513 * @dentry: dentry to invalidate
514 *
515 * Try to invalidate the dentry if it turns out to be
516 * possible. If there are other dentries that can be
517 * reached through this one we can't delete it and we
518 * return -EBUSY. On success we return 0.
519 *
520 * no dcache lock.
521 */
522
523int d_invalidate(struct dentry * dentry)
524{
525 /*
526 * If it's already been dropped, return OK.
527 */
Nick Pigginda502952011-01-07 17:49:33 +1100528 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100530 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 return 0;
532 }
533 /*
534 * Check whether to do a partial shrink_dcache
535 * to get rid of unused child entries.
536 */
537 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100538 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100540 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 }
542
543 /*
544 * Somebody else still using it?
545 *
546 * If it's a directory, we can't drop it
547 * for fear of somebody re-populating it
548 * with children (even though dropping it
549 * would make it unreachable from the root,
550 * we might still populate it if it was a
551 * working directory or similar).
Al Viro50e69632011-11-07 16:39:57 +0000552 * We also need to leave mountpoints alone,
553 * directory or not.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 */
Al Viro50e69632011-11-07 16:39:57 +0000555 if (dentry->d_count > 1 && dentry->d_inode) {
556 if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 return -EBUSY;
559 }
560 }
561
562 __d_drop(dentry);
563 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 return 0;
565}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700566EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100568/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100569static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100571 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572}
573
Nick Piggindc0474b2011-01-07 17:49:43 +1100574static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100575{
Nick Piggin23044502011-01-07 17:49:31 +1100576 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100577 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100578 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100579}
580
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100581struct dentry *dget_parent(struct dentry *dentry)
582{
583 struct dentry *ret;
584
585repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100586 /*
587 * Don't need rcu_dereference because we re-check it was correct under
588 * the lock.
589 */
590 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100591 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100592 spin_lock(&ret->d_lock);
593 if (unlikely(ret != dentry->d_parent)) {
594 spin_unlock(&ret->d_lock);
595 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100596 goto repeat;
597 }
Nick Piggina734eb42011-01-07 17:49:44 +1100598 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100599 BUG_ON(!ret->d_count);
600 ret->d_count++;
601 spin_unlock(&ret->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100602 return ret;
603}
604EXPORT_SYMBOL(dget_parent);
605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606/**
607 * d_find_alias - grab a hashed alias of inode
608 * @inode: inode in question
609 * @want_discon: flag, used by d_splice_alias, to request
610 * that only a DISCONNECTED alias be returned.
611 *
612 * If inode has a hashed alias, or is a directory and has any alias,
613 * acquire the reference to alias and return it. Otherwise return NULL.
614 * Notice that if inode is a directory there can be only one alias and
615 * it can be unhashed only if it has no children, or if it is the root
616 * of a filesystem.
617 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700618 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700620 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 */
Nick Pigginda502952011-01-07 17:49:33 +1100622static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623{
Nick Pigginda502952011-01-07 17:49:33 +1100624 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625
Nick Pigginda502952011-01-07 17:49:33 +1100626again:
627 discon_alias = NULL;
628 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
629 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700631 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100632 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100634 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100635 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100636 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 return alias;
638 }
639 }
Nick Pigginda502952011-01-07 17:49:33 +1100640 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 }
Nick Pigginda502952011-01-07 17:49:33 +1100642 if (discon_alias) {
643 alias = discon_alias;
644 spin_lock(&alias->d_lock);
645 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
646 if (IS_ROOT(alias) &&
647 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100648 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100649 spin_unlock(&alias->d_lock);
650 return alias;
651 }
652 }
653 spin_unlock(&alias->d_lock);
654 goto again;
655 }
656 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657}
658
Nick Pigginda502952011-01-07 17:49:33 +1100659struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660{
David Howells214fda12006-03-25 03:06:36 -0800661 struct dentry *de = NULL;
662
663 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100664 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800665 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100666 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800667 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 return de;
669}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700670EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671
672/*
673 * Try to kill dentries associated with this inode.
674 * WARNING: you must own a reference to inode.
675 */
676void d_prune_aliases(struct inode *inode)
677{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700678 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100680 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700681 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100683 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100684 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 __d_drop(dentry);
686 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100687 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 dput(dentry);
689 goto restart;
690 }
691 spin_unlock(&dentry->d_lock);
692 }
Nick Piggin873feea2011-01-07 17:50:06 +1100693 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700695EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696
697/*
Nick Piggin77812a12011-01-07 17:49:48 +1100698 * Try to throw away a dentry - free the inode, dput the parent.
699 * Requires dentry->d_lock is held, and dentry->d_count == 0.
700 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700701 *
Nick Piggin77812a12011-01-07 17:49:48 +1100702 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 */
Nick Piggin77812a12011-01-07 17:49:48 +1100704static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200705 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706{
Nick Piggin77812a12011-01-07 17:49:48 +1100707 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700708
Nick Piggin77812a12011-01-07 17:49:48 +1100709 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700710 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100711 * If dentry_kill returns NULL, we have nothing more to do.
712 * if it returns the same dentry, trylocks failed. In either
713 * case, just loop again.
714 *
715 * Otherwise, we need to prune ancestors too. This is necessary
716 * to prevent quadratic behavior of shrink_dcache_parent(), but
717 * is also expected to be beneficial in reducing dentry cache
718 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700719 */
Nick Piggin77812a12011-01-07 17:49:48 +1100720 if (!parent)
721 return;
722 if (parent == dentry)
723 return;
724
725 /* Prune ancestors. */
726 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700727 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100728 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100729 if (dentry->d_count > 1) {
730 dentry->d_count--;
731 spin_unlock(&dentry->d_lock);
732 return;
733 }
Nick Piggin77812a12011-01-07 17:49:48 +1100734 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700735 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736}
737
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400738static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700740 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700741
Nick Pigginec336792011-01-07 17:49:47 +1100742 rcu_read_lock();
743 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100744 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
745 if (&dentry->d_lru == list)
746 break; /* empty */
747 spin_lock(&dentry->d_lock);
748 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
749 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100750 continue;
751 }
752
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 /*
754 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700755 * the LRU because of laziness during lookup. Do not free
756 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100758 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100759 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700760 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 continue;
762 }
Nick Pigginec336792011-01-07 17:49:47 +1100763
Nick Pigginec336792011-01-07 17:49:47 +1100764 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100765
766 try_prune_one_dentry(dentry);
767
Nick Pigginec336792011-01-07 17:49:47 +1100768 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 }
Nick Pigginec336792011-01-07 17:49:47 +1100770 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400771}
772
773/**
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000774 * prune_dcache_sb - shrink the dcache
775 * @sb: superblock
776 * @count: number of entries to try to free
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400777 *
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000778 * Attempt to shrink the superblock dcache LRU by @count entries. This is
779 * done when we need more memory an called from the superblock shrinker
780 * function.
781 *
782 * This function may fail to free any resources if all the dentries are in
783 * use.
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400784 */
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000785void prune_dcache_sb(struct super_block *sb, int count)
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400786{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400787 struct dentry *dentry;
788 LIST_HEAD(referenced);
789 LIST_HEAD(tmp);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400790
Nick Piggin23044502011-01-07 17:49:31 +1100791relock:
792 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400793 while (!list_empty(&sb->s_dentry_lru)) {
794 dentry = list_entry(sb->s_dentry_lru.prev,
795 struct dentry, d_lru);
796 BUG_ON(dentry->d_sb != sb);
797
Nick Piggin23044502011-01-07 17:49:31 +1100798 if (!spin_trylock(&dentry->d_lock)) {
799 spin_unlock(&dcache_lru_lock);
800 cpu_relax();
801 goto relock;
802 }
803
Dave Chinnerb48f03b2011-08-23 18:56:24 +1000804 if (dentry->d_flags & DCACHE_REFERENCED) {
Nick Piggin23044502011-01-07 17:49:31 +1100805 dentry->d_flags &= ~DCACHE_REFERENCED;
806 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400807 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100808 } else {
809 list_move_tail(&dentry->d_lru, &tmp);
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100810 dentry->d_flags |= DCACHE_SHRINK_LIST;
Nick Piggin23044502011-01-07 17:49:31 +1100811 spin_unlock(&dentry->d_lock);
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000812 if (!--count)
Nick Piggin23044502011-01-07 17:49:31 +1100813 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400814 }
Nick Pigginec336792011-01-07 17:49:47 +1100815 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400816 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700817 if (!list_empty(&referenced))
818 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100819 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100820
821 shrink_dentry_list(&tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822}
823
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700824/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 * shrink_dcache_sb - shrink dcache for a superblock
826 * @sb: superblock
827 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400828 * Shrink the dcache for the specified super block. This is used to free
829 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400831void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400833 LIST_HEAD(tmp);
834
Nick Piggin23044502011-01-07 17:49:31 +1100835 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400836 while (!list_empty(&sb->s_dentry_lru)) {
837 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100838 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400839 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100840 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400841 }
Nick Piggin23044502011-01-07 17:49:31 +1100842 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700844EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845
846/*
David Howellsc636ebd2006-10-11 01:22:19 -0700847 * destroy a single subtree of dentries for unmount
848 * - see the comments on shrink_dcache_for_umount() for a description of the
849 * locking
850 */
851static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
852{
853 struct dentry *parent;
854
855 BUG_ON(!IS_ROOT(dentry));
856
David Howellsc636ebd2006-10-11 01:22:19 -0700857 for (;;) {
858 /* descend to the first leaf in the current subtree */
David Howells43c1c9c2011-06-07 14:09:30 +0100859 while (!list_empty(&dentry->d_subdirs))
David Howellsc636ebd2006-10-11 01:22:19 -0700860 dentry = list_entry(dentry->d_subdirs.next,
861 struct dentry, d_u.d_child);
David Howellsc636ebd2006-10-11 01:22:19 -0700862
863 /* consume the dentries from this leaf up through its parents
864 * until we find one with children or run out altogether */
865 do {
866 struct inode *inode;
867
Sage Weilf0023bc2011-10-28 10:02:42 -0700868 /*
869 * remove the dentry from the lru, and inform
870 * the fs that this dentry is about to be
871 * unhashed and destroyed.
872 */
873 dentry_lru_prune(dentry);
David Howells43c1c9c2011-06-07 14:09:30 +0100874 __d_shrink(dentry);
875
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100876 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700877 printk(KERN_ERR
878 "BUG: Dentry %p{i=%lx,n=%s}"
879 " still in use (%d)"
880 " [unmount of %s %s]\n",
881 dentry,
882 dentry->d_inode ?
883 dentry->d_inode->i_ino : 0UL,
884 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100885 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700886 dentry->d_sb->s_type->name,
887 dentry->d_sb->s_id);
888 BUG();
889 }
890
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100891 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700892 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100893 list_del(&dentry->d_u.d_child);
894 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900895 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100896 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100897 list_del(&dentry->d_u.d_child);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900898 }
David Howellsc636ebd2006-10-11 01:22:19 -0700899
David Howellsc636ebd2006-10-11 01:22:19 -0700900 inode = dentry->d_inode;
901 if (inode) {
902 dentry->d_inode = NULL;
903 list_del_init(&dentry->d_alias);
904 if (dentry->d_op && dentry->d_op->d_iput)
905 dentry->d_op->d_iput(dentry, inode);
906 else
907 iput(inode);
908 }
909
910 d_free(dentry);
911
912 /* finished when we fall off the top of the tree,
913 * otherwise we ascend to the parent and move to the
914 * next sibling if there is one */
915 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400916 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700917 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700918 } while (list_empty(&dentry->d_subdirs));
919
920 dentry = list_entry(dentry->d_subdirs.next,
921 struct dentry, d_u.d_child);
922 }
923}
924
925/*
926 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100927 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700928 * - the superblock is detached from all mountings and open files, so the
929 * dentry trees will not be rearranged by the VFS
930 * - s_umount is write-locked, so the memory pressure shrinker will ignore
931 * any dentries belonging to this superblock that it comes across
932 * - the filesystem itself is no longer permitted to rearrange the dentries
933 * in this superblock
934 */
935void shrink_dcache_for_umount(struct super_block *sb)
936{
937 struct dentry *dentry;
938
939 if (down_read_trylock(&sb->s_umount))
940 BUG();
941
942 dentry = sb->s_root;
943 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100944 dentry->d_count--;
David Howellsc636ebd2006-10-11 01:22:19 -0700945 shrink_dcache_for_umount_subtree(dentry);
946
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100947 while (!hlist_bl_empty(&sb->s_anon)) {
948 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700949 shrink_dcache_for_umount_subtree(dentry);
950 }
951}
952
953/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700954 * This tries to ascend one level of parenthood, but
955 * we can race with renaming, so we need to re-check
956 * the parenthood after dropping the lock and check
957 * that the sequence number still matches.
958 */
959static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
960{
961 struct dentry *new = old->d_parent;
962
963 rcu_read_lock();
964 spin_unlock(&old->d_lock);
965 spin_lock(&new->d_lock);
966
967 /*
968 * might go back up the wrong parent if we have had a rename
969 * or deletion
970 */
971 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -0400972 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700973 (!locked && read_seqretry(&rename_lock, seq))) {
974 spin_unlock(&new->d_lock);
975 new = NULL;
976 }
977 rcu_read_unlock();
978 return new;
979}
980
981
982/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 * Search for at least 1 mount point in the dentry's subdirs.
984 * We descend to the next level whenever the d_subdirs
985 * list is non-empty and continue searching.
986 */
987
988/**
989 * have_submounts - check for mounts over a dentry
990 * @parent: dentry to check.
991 *
992 * Return true if the parent or its subdirectories contain
993 * a mount point
994 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995int have_submounts(struct dentry *parent)
996{
Nick Piggin949854d2011-01-07 17:49:37 +1100997 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +1100999 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11001000 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001001
Nick Piggin949854d2011-01-07 17:49:37 +11001002 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001003again:
1004 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 if (d_mountpoint(parent))
1007 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001008 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009repeat:
1010 next = this_parent->d_subdirs.next;
1011resume:
1012 while (next != &this_parent->d_subdirs) {
1013 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001014 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001016
1017 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001019 if (d_mountpoint(dentry)) {
1020 spin_unlock(&dentry->d_lock);
1021 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001023 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001025 spin_unlock(&this_parent->d_lock);
1026 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001028 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 goto repeat;
1030 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001031 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032 }
1033 /*
1034 * All done at this level ... ascend and resume the search.
1035 */
1036 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001037 struct dentry *child = this_parent;
1038 this_parent = try_to_ascend(this_parent, locked, seq);
1039 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001040 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001041 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 goto resume;
1043 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001044 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001045 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001046 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001047 if (locked)
1048 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 return 0; /* No mount points found in tree */
1050positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001051 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001052 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001053 if (locked)
1054 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001056
1057rename_retry:
1058 locked = 1;
1059 write_seqlock(&rename_lock);
1060 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001062EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063
1064/*
1065 * Search the dentry child list for the specified parent,
1066 * and move any unused dentries to the end of the unused
1067 * list for prune_dcache(). We descend to the next level
1068 * whenever the d_subdirs list is non-empty and continue
1069 * searching.
1070 *
1071 * It returns zero iff there are no unused children,
1072 * otherwise it returns the number of children moved to
1073 * the end of the unused list. This may not be the total
1074 * number of unused children, because select_parent can
1075 * drop the lock and return early due to latency
1076 * constraints.
1077 */
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001078static int select_parent(struct dentry *parent, struct list_head *dispose)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079{
Nick Piggin949854d2011-01-07 17:49:37 +11001080 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001082 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001084 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
Nick Piggin949854d2011-01-07 17:49:37 +11001086 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001087again:
1088 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001089 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090repeat:
1091 next = this_parent->d_subdirs.next;
1092resume:
1093 while (next != &this_parent->d_subdirs) {
1094 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001095 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 next = tmp->next;
1097
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001098 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001099
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001100 /*
1101 * move only zero ref count dentries to the dispose list.
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001102 *
1103 * Those which are presently on the shrink list, being processed
1104 * by shrink_dentry_list(), shouldn't be moved. Otherwise the
1105 * loop in shrink_dcache_parent() might not make any progress
1106 * and loop forever.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 */
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001108 if (dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001109 dentry_lru_del(dentry);
Miklos Szeredieaf5f902012-01-10 18:22:25 +01001110 } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
1111 dentry_lru_move_list(dentry, dispose);
1112 dentry->d_flags |= DCACHE_SHRINK_LIST;
1113 found++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 /*
1116 * We can return to the caller if we have found some (this
1117 * ensures forward progress). We'll be coming back to find
1118 * the rest.
1119 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001120 if (found && need_resched()) {
1121 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 goto out;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001123 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124
1125 /*
1126 * Descend a level if the d_subdirs list is non-empty.
1127 */
1128 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001129 spin_unlock(&this_parent->d_lock);
1130 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001132 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 goto repeat;
1134 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001135
1136 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 }
1138 /*
1139 * All done at this level ... ascend and resume the search.
1140 */
1141 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001142 struct dentry *child = this_parent;
1143 this_parent = try_to_ascend(this_parent, locked, seq);
1144 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001145 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001146 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147 goto resume;
1148 }
1149out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001150 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001151 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001152 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001153 if (locked)
1154 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155 return found;
Nick Piggin58db63d2011-01-07 17:49:39 +11001156
1157rename_retry:
1158 if (found)
1159 return found;
1160 locked = 1;
1161 write_seqlock(&rename_lock);
1162 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163}
1164
1165/**
1166 * shrink_dcache_parent - prune dcache
1167 * @parent: parent of entries to prune
1168 *
1169 * Prune the dcache to remove unused children of the parent dentry.
1170 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171void shrink_dcache_parent(struct dentry * parent)
1172{
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001173 LIST_HEAD(dispose);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 int found;
1175
Dave Chinnerb48f03b2011-08-23 18:56:24 +10001176 while ((found = select_parent(parent, &dispose)) != 0)
1177 shrink_dentry_list(&dispose);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001179EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181/**
Al Viroa4464db2011-07-07 15:03:58 -04001182 * __d_alloc - allocate a dcache entry
1183 * @sb: filesystem it will belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 * @name: qstr of the name
1185 *
1186 * Allocates a dentry. It returns %NULL if there is insufficient memory
1187 * available. On a success the dentry is returned. The name passed in is
1188 * copied and the copy passed in may be reused after this call.
1189 */
1190
Al Viroa4464db2011-07-07 15:03:58 -04001191struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192{
1193 struct dentry *dentry;
1194 char *dname;
1195
Mel Gormane12ba742007-10-16 01:25:52 -07001196 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 if (!dentry)
1198 return NULL;
1199
1200 if (name->len > DNAME_INLINE_LEN-1) {
1201 dname = kmalloc(name->len + 1, GFP_KERNEL);
1202 if (!dname) {
1203 kmem_cache_free(dentry_cache, dentry);
1204 return NULL;
1205 }
1206 } else {
1207 dname = dentry->d_iname;
1208 }
1209 dentry->d_name.name = dname;
1210
1211 dentry->d_name.len = name->len;
1212 dentry->d_name.hash = name->hash;
1213 memcpy(dname, name->name, name->len);
1214 dname[name->len] = 0;
1215
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001216 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001217 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001219 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 dentry->d_inode = NULL;
Al Viroa4464db2011-07-07 15:03:58 -04001221 dentry->d_parent = dentry;
1222 dentry->d_sb = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223 dentry->d_op = NULL;
1224 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001225 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 INIT_LIST_HEAD(&dentry->d_lru);
1227 INIT_LIST_HEAD(&dentry->d_subdirs);
1228 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001229 INIT_LIST_HEAD(&dentry->d_u.d_child);
Al Viroa4464db2011-07-07 15:03:58 -04001230 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231
Nick Piggin3e880fb2011-01-07 17:49:19 +11001232 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001233
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234 return dentry;
1235}
Al Viroa4464db2011-07-07 15:03:58 -04001236
1237/**
1238 * d_alloc - allocate a dcache entry
1239 * @parent: parent of entry to allocate
1240 * @name: qstr of the name
1241 *
1242 * Allocates a dentry. It returns %NULL if there is insufficient memory
1243 * available. On a success the dentry is returned. The name passed in is
1244 * copied and the copy passed in may be reused after this call.
1245 */
1246struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1247{
1248 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1249 if (!dentry)
1250 return NULL;
1251
1252 spin_lock(&parent->d_lock);
1253 /*
1254 * don't need child lock because it is not subject
1255 * to concurrency here
1256 */
1257 __dget_dlock(parent);
1258 dentry->d_parent = parent;
1259 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
1260 spin_unlock(&parent->d_lock);
1261
1262 return dentry;
1263}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001264EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265
Nick Piggin4b936882011-01-07 17:50:07 +11001266struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1267{
Al Viroa4464db2011-07-07 15:03:58 -04001268 struct dentry *dentry = __d_alloc(sb, name);
1269 if (dentry)
Nick Piggin4b936882011-01-07 17:50:07 +11001270 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin4b936882011-01-07 17:50:07 +11001271 return dentry;
1272}
1273EXPORT_SYMBOL(d_alloc_pseudo);
1274
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1276{
1277 struct qstr q;
1278
1279 q.name = name;
1280 q.len = strlen(name);
1281 q.hash = full_name_hash(q.name, q.len);
1282 return d_alloc(parent, &q);
1283}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001284EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
Nick Pigginfb045ad2011-01-07 17:49:55 +11001286void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1287{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001288 WARN_ON_ONCE(dentry->d_op);
1289 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001290 DCACHE_OP_COMPARE |
1291 DCACHE_OP_REVALIDATE |
1292 DCACHE_OP_DELETE ));
1293 dentry->d_op = op;
1294 if (!op)
1295 return;
1296 if (op->d_hash)
1297 dentry->d_flags |= DCACHE_OP_HASH;
1298 if (op->d_compare)
1299 dentry->d_flags |= DCACHE_OP_COMPARE;
1300 if (op->d_revalidate)
1301 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1302 if (op->d_delete)
1303 dentry->d_flags |= DCACHE_OP_DELETE;
Sage Weilf0023bc2011-10-28 10:02:42 -07001304 if (op->d_prune)
1305 dentry->d_flags |= DCACHE_OP_PRUNE;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001306
1307}
1308EXPORT_SYMBOL(d_set_d_op);
1309
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001310static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1311{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001312 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001313 if (inode) {
1314 if (unlikely(IS_AUTOMOUNT(inode)))
1315 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001316 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001317 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001318 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001319 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001320 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001321 fsnotify_d_instantiate(dentry, inode);
1322}
1323
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324/**
1325 * d_instantiate - fill in inode information for a dentry
1326 * @entry: dentry to complete
1327 * @inode: inode to attach to this dentry
1328 *
1329 * Fill in inode information in the entry.
1330 *
1331 * This turns negative dentries into productive full members
1332 * of society.
1333 *
1334 * NOTE! This assumes that the inode count has been incremented
1335 * (or otherwise set) by the caller to indicate that it is now
1336 * in use by the dcache.
1337 */
1338
1339void d_instantiate(struct dentry *entry, struct inode * inode)
1340{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001341 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001342 if (inode)
1343 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001344 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001345 if (inode)
1346 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 security_d_instantiate(entry, inode);
1348}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001349EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350
1351/**
1352 * d_instantiate_unique - instantiate a non-aliased dentry
1353 * @entry: dentry to instantiate
1354 * @inode: inode to attach to this dentry
1355 *
1356 * Fill in inode information in the entry. On success, it returns NULL.
1357 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001358 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 *
1360 * Note that in order to avoid conflicts with rename() etc, the caller
1361 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001362 *
1363 * This also assumes that the inode count has been incremented
1364 * (or otherwise set) by the caller to indicate that it is now
1365 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 */
David Howells770bfad2006-08-22 20:06:07 -04001367static struct dentry *__d_instantiate_unique(struct dentry *entry,
1368 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369{
1370 struct dentry *alias;
1371 int len = entry->d_name.len;
1372 const char *name = entry->d_name.name;
1373 unsigned int hash = entry->d_name.hash;
1374
David Howells770bfad2006-08-22 20:06:07 -04001375 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001376 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001377 return NULL;
1378 }
1379
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1381 struct qstr *qstr = &alias->d_name;
1382
Nick Piggin9abca362011-01-07 17:49:36 +11001383 /*
1384 * Don't need alias->d_lock here, because aliases with
1385 * d_parent == entry->d_parent are not subject to name or
1386 * parent changes, because the parent inode i_mutex is held.
1387 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388 if (qstr->hash != hash)
1389 continue;
1390 if (alias->d_parent != entry->d_parent)
1391 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001392 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001394 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 return alias;
1396 }
David Howells770bfad2006-08-22 20:06:07 -04001397
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001398 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 return NULL;
1400}
David Howells770bfad2006-08-22 20:06:07 -04001401
1402struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1403{
1404 struct dentry *result;
1405
1406 BUG_ON(!list_empty(&entry->d_alias));
1407
Nick Piggin873feea2011-01-07 17:50:06 +11001408 if (inode)
1409 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001410 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001411 if (inode)
1412 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001413
1414 if (!result) {
1415 security_d_instantiate(entry, inode);
1416 return NULL;
1417 }
1418
1419 BUG_ON(!d_unhashed(result));
1420 iput(inode);
1421 return result;
1422}
1423
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424EXPORT_SYMBOL(d_instantiate_unique);
1425
1426/**
1427 * d_alloc_root - allocate root dentry
1428 * @root_inode: inode to allocate the root for
1429 *
1430 * Allocate a root ("/") dentry for the inode given. The inode is
1431 * instantiated and returned. %NULL is returned if there is insufficient
1432 * memory or the inode passed is %NULL.
1433 */
1434
1435struct dentry * d_alloc_root(struct inode * root_inode)
1436{
1437 struct dentry *res = NULL;
1438
1439 if (root_inode) {
1440 static const struct qstr name = { .name = "/", .len = 1 };
1441
Al Viroa4464db2011-07-07 15:03:58 -04001442 res = __d_alloc(root_inode->i_sb, &name);
1443 if (res)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444 d_instantiate(res, root_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 }
1446 return res;
1447}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001448EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449
Al Viroadc0e912012-01-08 16:49:21 -05001450struct dentry *d_make_root(struct inode *root_inode)
1451{
1452 struct dentry *res = NULL;
1453
1454 if (root_inode) {
1455 static const struct qstr name = { .name = "/", .len = 1 };
1456
1457 res = __d_alloc(root_inode->i_sb, &name);
1458 if (res)
1459 d_instantiate(res, root_inode);
1460 else
1461 iput(root_inode);
1462 }
1463 return res;
1464}
1465EXPORT_SYMBOL(d_make_root);
1466
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001467static struct dentry * __d_find_any_alias(struct inode *inode)
1468{
1469 struct dentry *alias;
1470
1471 if (list_empty(&inode->i_dentry))
1472 return NULL;
1473 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1474 __dget(alias);
1475 return alias;
1476}
1477
1478static struct dentry * d_find_any_alias(struct inode *inode)
1479{
1480 struct dentry *de;
1481
1482 spin_lock(&inode->i_lock);
1483 de = __d_find_any_alias(inode);
1484 spin_unlock(&inode->i_lock);
1485 return de;
1486}
1487
1488
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001490 * d_obtain_alias - find or allocate a dentry for a given inode
1491 * @inode: inode to allocate the dentry for
1492 *
1493 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1494 * similar open by handle operations. The returned dentry may be anonymous,
1495 * or may have a full name (if the inode was already in the cache).
1496 *
1497 * When called on a directory inode, we must ensure that the inode only ever
1498 * has one dentry. If a dentry is found, that is returned instead of
1499 * allocating a new one.
1500 *
1501 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001502 * to the dentry. In case of an error the reference on the inode is released.
1503 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1504 * be passed in and will be the error will be propagate to the return value,
1505 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001506 */
1507struct dentry *d_obtain_alias(struct inode *inode)
1508{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001509 static const struct qstr anonstring = { .name = "" };
1510 struct dentry *tmp;
1511 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001512
1513 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001514 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001515 if (IS_ERR(inode))
1516 return ERR_CAST(inode);
1517
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001518 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001519 if (res)
1520 goto out_iput;
1521
Al Viroa4464db2011-07-07 15:03:58 -04001522 tmp = __d_alloc(inode->i_sb, &anonstring);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001523 if (!tmp) {
1524 res = ERR_PTR(-ENOMEM);
1525 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001526 }
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001527
Nick Piggin873feea2011-01-07 17:50:06 +11001528 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001529 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001530 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001531 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001532 dput(tmp);
1533 goto out_iput;
1534 }
1535
1536 /* attach a disconnected dentry */
1537 spin_lock(&tmp->d_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001538 tmp->d_inode = inode;
1539 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001540 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001541 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001542 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001543 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001544 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001545 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001546 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001547
Christoph Hellwig9308a612008-08-11 15:49:12 +02001548 return tmp;
1549
1550 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001551 if (res && !IS_ERR(res))
1552 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001553 iput(inode);
1554 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001555}
Benny Halevyadc48722009-02-27 14:02:59 -08001556EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557
1558/**
1559 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1560 * @inode: the inode which may have a disconnected dentry
1561 * @dentry: a negative dentry which we want to point to the inode.
1562 *
1563 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1564 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1565 * and return it, else simply d_add the inode to the dentry and return NULL.
1566 *
1567 * This is needed in the lookup routine of any filesystem that is exportable
1568 * (via knfsd) so that we can build dcache paths to directories effectively.
1569 *
1570 * If a dentry was found and moved, then it is returned. Otherwise NULL
1571 * is returned. This matches the expected return value of ->lookup.
1572 *
1573 */
1574struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1575{
1576 struct dentry *new = NULL;
1577
Al Viroa9049372011-07-08 21:20:11 -04001578 if (IS_ERR(inode))
1579 return ERR_CAST(inode);
1580
NeilBrown21c0d8f2006-10-04 02:16:16 -07001581 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001582 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 new = __d_find_alias(inode, 1);
1584 if (new) {
1585 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001586 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588 d_move(new, dentry);
1589 iput(inode);
1590 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001591 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001592 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001593 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 security_d_instantiate(dentry, inode);
1595 d_rehash(dentry);
1596 }
1597 } else
1598 d_add(dentry, inode);
1599 return new;
1600}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001601EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602
Barry Naujok94035402008-05-21 16:50:46 +10001603/**
1604 * d_add_ci - lookup or allocate new dentry with case-exact name
1605 * @inode: the inode case-insensitive lookup has found
1606 * @dentry: the negative dentry that was passed to the parent's lookup func
1607 * @name: the case-exact name to be associated with the returned dentry
1608 *
1609 * This is to avoid filling the dcache with case-insensitive names to the
1610 * same inode, only the actual correct case is stored in the dcache for
1611 * case-insensitive filesystems.
1612 *
1613 * For a case-insensitive lookup match and if the the case-exact dentry
1614 * already exists in in the dcache, use it and return it.
1615 *
1616 * If no entry exists with the exact case name, allocate new dentry with
1617 * the exact case, and return the spliced entry.
1618 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001619struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001620 struct qstr *name)
1621{
1622 int error;
1623 struct dentry *found;
1624 struct dentry *new;
1625
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001626 /*
1627 * First check if a dentry matching the name already exists,
1628 * if not go ahead and create it now.
1629 */
Barry Naujok94035402008-05-21 16:50:46 +10001630 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001631 if (!found) {
1632 new = d_alloc(dentry->d_parent, name);
1633 if (!new) {
1634 error = -ENOMEM;
1635 goto err_out;
1636 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001637
Barry Naujok94035402008-05-21 16:50:46 +10001638 found = d_splice_alias(inode, new);
1639 if (found) {
1640 dput(new);
1641 return found;
1642 }
1643 return new;
1644 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001645
1646 /*
1647 * If a matching dentry exists, and it's not negative use it.
1648 *
1649 * Decrement the reference count to balance the iget() done
1650 * earlier on.
1651 */
Barry Naujok94035402008-05-21 16:50:46 +10001652 if (found->d_inode) {
1653 if (unlikely(found->d_inode != inode)) {
1654 /* This can't happen because bad inodes are unhashed. */
1655 BUG_ON(!is_bad_inode(inode));
1656 BUG_ON(!is_bad_inode(found->d_inode));
1657 }
Barry Naujok94035402008-05-21 16:50:46 +10001658 iput(inode);
1659 return found;
1660 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001661
Barry Naujok94035402008-05-21 16:50:46 +10001662 /*
Josef Bacik44396f42011-05-31 11:58:49 -04001663 * We are going to instantiate this dentry, unhash it and clear the
1664 * lookup flag so we can do that.
1665 */
1666 if (unlikely(d_need_lookup(found)))
1667 d_clear_need_lookup(found);
1668
1669 /*
Barry Naujok94035402008-05-21 16:50:46 +10001670 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001671 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001672 */
Al Viro4513d892011-07-17 10:52:14 -04001673 new = d_splice_alias(inode, found);
1674 if (new) {
1675 dput(found);
1676 found = new;
Barry Naujok94035402008-05-21 16:50:46 +10001677 }
Al Viro4513d892011-07-17 10:52:14 -04001678 return found;
Barry Naujok94035402008-05-21 16:50:46 +10001679
1680err_out:
1681 iput(inode);
1682 return ERR_PTR(error);
1683}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001684EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685
1686/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001687 * __d_lookup_rcu - search for a dentry (racy, store-free)
1688 * @parent: parent dentry
1689 * @name: qstr of name we wish to find
1690 * @seq: returns d_seq value at the point where the dentry was found
1691 * @inode: returns dentry->d_inode when the inode was found valid.
1692 * Returns: dentry, or NULL
1693 *
1694 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1695 * resolution (store-free path walking) design described in
1696 * Documentation/filesystems/path-lookup.txt.
1697 *
1698 * This is not to be used outside core vfs.
1699 *
1700 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1701 * held, and rcu_read_lock held. The returned dentry must not be stored into
1702 * without taking d_lock and checking d_seq sequence count against @seq
1703 * returned here.
1704 *
1705 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1706 * function.
1707 *
1708 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1709 * the returned dentry, so long as its parent's seqlock is checked after the
1710 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1711 * is formed, giving integrity down the path walk.
1712 */
1713struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
1714 unsigned *seq, struct inode **inode)
1715{
1716 unsigned int len = name->len;
1717 unsigned int hash = name->hash;
1718 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001719 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001720 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001721 struct dentry *dentry;
1722
1723 /*
1724 * Note: There is significant duplication with __d_lookup_rcu which is
1725 * required to prevent single threaded performance regressions
1726 * especially on architectures where smp_rmb (in seqcounts) are costly.
1727 * Keep the two functions in sync.
1728 */
1729
1730 /*
1731 * The hash list is protected using RCU.
1732 *
1733 * Carefully use d_seq when comparing a candidate dentry, to avoid
1734 * races with d_move().
1735 *
1736 * It is possible that concurrent renames can mess up our list
1737 * walk here and result in missing our dentry, resulting in the
1738 * false-negative result. d_lookup() protects against concurrent
1739 * renames using rename_lock seqlock.
1740 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001741 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001742 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001743 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001744 struct inode *i;
1745 const char *tname;
1746 int tlen;
1747
1748 if (dentry->d_name.hash != hash)
1749 continue;
1750
1751seqretry:
1752 *seq = read_seqcount_begin(&dentry->d_seq);
1753 if (dentry->d_parent != parent)
1754 continue;
1755 if (d_unhashed(dentry))
1756 continue;
1757 tlen = dentry->d_name.len;
1758 tname = dentry->d_name.name;
1759 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001760 prefetch(tname);
Nick Piggin31e6b012011-01-07 17:49:52 +11001761 /*
1762 * This seqcount check is required to ensure name and
1763 * len are loaded atomically, so as not to walk off the
1764 * edge of memory when walking. If we could load this
1765 * atomically some other way, we could drop this check.
1766 */
1767 if (read_seqcount_retry(&dentry->d_seq, *seq))
1768 goto seqretry;
Linus Torvalds830c0f02011-08-06 22:41:50 -07001769 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001770 if (parent->d_op->d_compare(parent, *inode,
1771 dentry, i,
1772 tlen, tname, name))
1773 continue;
1774 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001775 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001776 continue;
1777 }
1778 /*
1779 * No extra seqcount check is required after the name
1780 * compare. The caller must perform a seqcount check in
1781 * order to do anything useful with the returned dentry
1782 * anyway.
1783 */
1784 *inode = i;
1785 return dentry;
1786 }
1787 return NULL;
1788}
1789
1790/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 * d_lookup - search for a dentry
1792 * @parent: parent dentry
1793 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001794 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001796 * d_lookup searches the children of the parent dentry for the name in
1797 * question. If the dentry is found its reference count is incremented and the
1798 * dentry is returned. The caller must use dput to free the entry when it has
1799 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001801struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802{
Nick Piggin31e6b012011-01-07 17:49:52 +11001803 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001804 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001805
1806 do {
1807 seq = read_seqbegin(&rename_lock);
1808 dentry = __d_lookup(parent, name);
1809 if (dentry)
1810 break;
1811 } while (read_seqretry(&rename_lock, seq));
1812 return dentry;
1813}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001814EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815
Nick Piggin31e6b012011-01-07 17:49:52 +11001816/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001817 * __d_lookup - search for a dentry (racy)
1818 * @parent: parent dentry
1819 * @name: qstr of name we wish to find
1820 * Returns: dentry, or NULL
1821 *
1822 * __d_lookup is like d_lookup, however it may (rarely) return a
1823 * false-negative result due to unrelated rename activity.
1824 *
1825 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1826 * however it must be used carefully, eg. with a following d_lookup in
1827 * the case of failure.
1828 *
1829 * __d_lookup callers must be commented.
1830 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001831struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832{
1833 unsigned int len = name->len;
1834 unsigned int hash = name->hash;
1835 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001836 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001837 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001838 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001839 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840
Nick Pigginb04f7842010-08-18 04:37:34 +10001841 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001842 * Note: There is significant duplication with __d_lookup_rcu which is
1843 * required to prevent single threaded performance regressions
1844 * especially on architectures where smp_rmb (in seqcounts) are costly.
1845 * Keep the two functions in sync.
1846 */
1847
1848 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001849 * The hash list is protected using RCU.
1850 *
1851 * Take d_lock when comparing a candidate dentry, to avoid races
1852 * with d_move().
1853 *
1854 * It is possible that concurrent renames can mess up our list
1855 * walk here and result in missing our dentry, resulting in the
1856 * false-negative result. d_lookup() protects against concurrent
1857 * renames using rename_lock seqlock.
1858 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001859 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001860 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861 rcu_read_lock();
1862
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001863 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001864 const char *tname;
1865 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867 if (dentry->d_name.hash != hash)
1868 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869
1870 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 if (dentry->d_parent != parent)
1872 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001873 if (d_unhashed(dentry))
1874 goto next;
1875
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 /*
1877 * It is safe to compare names since d_move() cannot
1878 * change the qstr (protected by d_lock).
1879 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001880 tlen = dentry->d_name.len;
1881 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001882 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001883 if (parent->d_op->d_compare(parent, parent->d_inode,
1884 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001885 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886 goto next;
1887 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001888 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889 goto next;
1890 }
1891
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001892 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001893 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894 spin_unlock(&dentry->d_lock);
1895 break;
1896next:
1897 spin_unlock(&dentry->d_lock);
1898 }
1899 rcu_read_unlock();
1900
1901 return found;
1902}
1903
1904/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001905 * d_hash_and_lookup - hash the qstr then search for a dentry
1906 * @dir: Directory to search in
1907 * @name: qstr of name we wish to find
1908 *
1909 * On hash failure or on lookup failure NULL is returned.
1910 */
1911struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1912{
1913 struct dentry *dentry = NULL;
1914
1915 /*
1916 * Check for a fs-specific hash function. Note that we must
1917 * calculate the standard hash first, as the d_op->d_hash()
1918 * routine may choose to leave the hash value unchanged.
1919 */
1920 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001921 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001922 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001923 goto out;
1924 }
1925 dentry = d_lookup(dir, name);
1926out:
1927 return dentry;
1928}
1929
1930/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001931 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001933 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 *
1935 * An insecure source has sent us a dentry, here we verify it and dget() it.
1936 * This is used by ncpfs in its readdir implementation.
1937 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001938 *
1939 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001941int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942{
Nick Piggin786a5e12011-01-07 17:49:16 +11001943 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001944
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001945 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001946 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
1947 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001948 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11001949 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001950 spin_unlock(&dentry->d_lock);
1951 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952 return 1;
1953 }
1954 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001955 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001956
Linus Torvalds1da177e2005-04-16 15:20:36 -07001957 return 0;
1958}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001959EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960
1961/*
1962 * When a file is deleted, we have two options:
1963 * - turn this dentry into a negative dentry
1964 * - unhash this dentry and free it.
1965 *
1966 * Usually, we want to just turn this into
1967 * a negative dentry, but if anybody else is
1968 * currently using the dentry or the inode
1969 * we can't do that and we fall back on removing
1970 * it from the hash queues and waiting for
1971 * it to be deleted later when it has no users
1972 */
1973
1974/**
1975 * d_delete - delete a dentry
1976 * @dentry: The dentry to delete
1977 *
1978 * Turn the dentry into a negative dentry if possible, otherwise
1979 * remove it from the hash queues so it can be deleted later
1980 */
1981
1982void d_delete(struct dentry * dentry)
1983{
Nick Piggin873feea2011-01-07 17:50:06 +11001984 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04001985 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 /*
1987 * Are we the only user?
1988 */
Nick Piggin357f8e62011-01-07 17:49:42 +11001989again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001991 inode = dentry->d_inode;
1992 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001993 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11001994 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11001995 spin_unlock(&dentry->d_lock);
1996 cpu_relax();
1997 goto again;
1998 }
Al Viro13e3c5e2010-05-21 16:11:04 -04001999 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11002000 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04002001 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002 return;
2003 }
2004
2005 if (!d_unhashed(dentry))
2006 __d_drop(dentry);
2007
2008 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04002009
2010 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002012EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002014static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002016 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002017 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07002018 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002019 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002020 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021}
2022
David Howells770bfad2006-08-22 20:06:07 -04002023static void _d_rehash(struct dentry * entry)
2024{
2025 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2026}
2027
Linus Torvalds1da177e2005-04-16 15:20:36 -07002028/**
2029 * d_rehash - add an entry back to the hash
2030 * @entry: dentry to add to the hash
2031 *
2032 * Adds a dentry to the hash according to its name.
2033 */
2034
2035void d_rehash(struct dentry * entry)
2036{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002038 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002041EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002043/**
2044 * dentry_update_name_case - update case insensitive dentry with a new name
2045 * @dentry: dentry to be updated
2046 * @name: new name
2047 *
2048 * Update a case insensitive dentry with new case of name.
2049 *
2050 * dentry must have been returned by d_lookup with name @name. Old and new
2051 * name lengths must match (ie. no d_compare which allows mismatched name
2052 * lengths).
2053 *
2054 * Parent inode i_mutex must be held over d_lookup and into this call (to
2055 * keep renames and concurrent inserts, and readdir(2) away).
2056 */
2057void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2058{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002059 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002060 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2061
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002062 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002063 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002064 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002065 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002066 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002067}
2068EXPORT_SYMBOL(dentry_update_name_case);
2069
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070static void switch_names(struct dentry *dentry, struct dentry *target)
2071{
2072 if (dname_external(target)) {
2073 if (dname_external(dentry)) {
2074 /*
2075 * Both external: swap the pointers
2076 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002077 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 } else {
2079 /*
2080 * dentry:internal, target:external. Steal target's
2081 * storage and make target internal.
2082 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002083 memcpy(target->d_iname, dentry->d_name.name,
2084 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002085 dentry->d_name.name = target->d_name.name;
2086 target->d_name.name = target->d_iname;
2087 }
2088 } else {
2089 if (dname_external(dentry)) {
2090 /*
2091 * dentry:external, target:internal. Give dentry's
2092 * storage to target and make dentry internal
2093 */
2094 memcpy(dentry->d_iname, target->d_name.name,
2095 target->d_name.len + 1);
2096 target->d_name.name = dentry->d_name.name;
2097 dentry->d_name.name = dentry->d_iname;
2098 } else {
2099 /*
2100 * Both are internal. Just copy target to dentry
2101 */
2102 memcpy(dentry->d_iname, target->d_name.name,
2103 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002104 dentry->d_name.len = target->d_name.len;
2105 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 }
2107 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002108 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109}
2110
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002111static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2112{
2113 /*
2114 * XXXX: do we really need to take target->d_lock?
2115 */
2116 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2117 spin_lock(&target->d_parent->d_lock);
2118 else {
2119 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2120 spin_lock(&dentry->d_parent->d_lock);
2121 spin_lock_nested(&target->d_parent->d_lock,
2122 DENTRY_D_LOCK_NESTED);
2123 } else {
2124 spin_lock(&target->d_parent->d_lock);
2125 spin_lock_nested(&dentry->d_parent->d_lock,
2126 DENTRY_D_LOCK_NESTED);
2127 }
2128 }
2129 if (target < dentry) {
2130 spin_lock_nested(&target->d_lock, 2);
2131 spin_lock_nested(&dentry->d_lock, 3);
2132 } else {
2133 spin_lock_nested(&dentry->d_lock, 2);
2134 spin_lock_nested(&target->d_lock, 3);
2135 }
2136}
2137
2138static void dentry_unlock_parents_for_move(struct dentry *dentry,
2139 struct dentry *target)
2140{
2141 if (target->d_parent != dentry->d_parent)
2142 spin_unlock(&dentry->d_parent->d_lock);
2143 if (target->d_parent != target)
2144 spin_unlock(&target->d_parent->d_lock);
2145}
2146
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002148 * When switching names, the actual string doesn't strictly have to
2149 * be preserved in the target - because we're dropping the target
2150 * anyway. As such, we can just do a simple memcpy() to copy over
2151 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002153 * Note that we have to be a lot more careful about getting the hash
2154 * switched - we have to switch the hash value properly even if it
2155 * then no longer matches the actual (corrupted) string of the target.
2156 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002158/*
Al Viro18367502011-07-12 21:42:24 -04002159 * __d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 * @dentry: entry to move
2161 * @target: new dentry
2162 *
2163 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002164 * dcache entries should not be moved in this way. Caller must hold
2165 * rename_lock, the i_mutex of the source and target directories,
2166 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 */
Al Viro18367502011-07-12 21:42:24 -04002168static void __d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 if (!dentry->d_inode)
2171 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2172
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002173 BUG_ON(d_ancestor(dentry, target));
2174 BUG_ON(d_ancestor(target, dentry));
2175
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002176 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177
Nick Piggin31e6b012011-01-07 17:49:52 +11002178 write_seqcount_begin(&dentry->d_seq);
2179 write_seqcount_begin(&target->d_seq);
2180
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002181 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2182
2183 /*
2184 * Move the dentry to the target hash queue. Don't bother checking
2185 * for the same hash queue because of how unlikely it is.
2186 */
2187 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002188 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189
2190 /* Unhash the target: dput() will then get rid of it */
2191 __d_drop(target);
2192
Eric Dumazet5160ee62006-01-08 01:03:32 -08002193 list_del(&dentry->d_u.d_child);
2194 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195
2196 /* Switch the names.. */
2197 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002198 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199
2200 /* ... and switch the parents */
2201 if (IS_ROOT(dentry)) {
2202 dentry->d_parent = target->d_parent;
2203 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002204 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002206 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207
2208 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002209 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 }
2211
Eric Dumazet5160ee62006-01-08 01:03:32 -08002212 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002213
Nick Piggin31e6b012011-01-07 17:49:52 +11002214 write_seqcount_end(&target->d_seq);
2215 write_seqcount_end(&dentry->d_seq);
2216
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002217 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002219 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 spin_unlock(&dentry->d_lock);
Al Viro18367502011-07-12 21:42:24 -04002221}
2222
2223/*
2224 * d_move - move a dentry
2225 * @dentry: entry to move
2226 * @target: new dentry
2227 *
2228 * Update the dcache to reflect the move of a file name. Negative
Jeff Laytonc46c8872011-07-26 13:33:16 -04002229 * dcache entries should not be moved in this way. See the locking
2230 * requirements for __d_move.
Al Viro18367502011-07-12 21:42:24 -04002231 */
2232void d_move(struct dentry *dentry, struct dentry *target)
2233{
2234 write_seqlock(&rename_lock);
2235 __d_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002236 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002237}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002238EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002239
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002240/**
2241 * d_ancestor - search for an ancestor
2242 * @p1: ancestor dentry
2243 * @p2: child dentry
2244 *
2245 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2246 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002247 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002248struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002249{
2250 struct dentry *p;
2251
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002252 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002253 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002254 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002255 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002256 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002257}
2258
2259/*
2260 * This helper attempts to cope with remotely renamed directories
2261 *
2262 * It assumes that the caller is already holding
Al Viro18367502011-07-12 21:42:24 -04002263 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002264 *
2265 * Note: If ever the locking in lock_rename() changes, then please
2266 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002267 */
Nick Piggin873feea2011-01-07 17:50:06 +11002268static struct dentry *__d_unalias(struct inode *inode,
2269 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002270{
2271 struct mutex *m1 = NULL, *m2 = NULL;
2272 struct dentry *ret;
2273
2274 /* If alias and dentry share a parent, then no extra locks required */
2275 if (alias->d_parent == dentry->d_parent)
2276 goto out_unalias;
2277
Trond Myklebust9eaef272006-10-21 10:24:20 -07002278 /* See lock_rename() */
2279 ret = ERR_PTR(-EBUSY);
2280 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2281 goto out_err;
2282 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2283 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2284 goto out_err;
2285 m2 = &alias->d_parent->d_inode->i_mutex;
2286out_unalias:
Al Viro18367502011-07-12 21:42:24 -04002287 __d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002288 ret = alias;
2289out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002290 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002291 if (m2)
2292 mutex_unlock(m2);
2293 if (m1)
2294 mutex_unlock(m1);
2295 return ret;
2296}
2297
2298/*
David Howells770bfad2006-08-22 20:06:07 -04002299 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2300 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002301 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002302 */
2303static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2304{
2305 struct dentry *dparent, *aparent;
2306
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002307 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002308
Nick Piggin31e6b012011-01-07 17:49:52 +11002309 write_seqcount_begin(&dentry->d_seq);
2310 write_seqcount_begin(&anon->d_seq);
2311
David Howells770bfad2006-08-22 20:06:07 -04002312 dparent = dentry->d_parent;
2313 aparent = anon->d_parent;
2314
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002315 switch_names(dentry, anon);
2316 swap(dentry->d_name.hash, anon->d_name.hash);
2317
David Howells770bfad2006-08-22 20:06:07 -04002318 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2319 list_del(&dentry->d_u.d_child);
2320 if (!IS_ROOT(dentry))
2321 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2322 else
2323 INIT_LIST_HEAD(&dentry->d_u.d_child);
2324
2325 anon->d_parent = (dparent == dentry) ? anon : dparent;
2326 list_del(&anon->d_u.d_child);
2327 if (!IS_ROOT(anon))
2328 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2329 else
2330 INIT_LIST_HEAD(&anon->d_u.d_child);
2331
Nick Piggin31e6b012011-01-07 17:49:52 +11002332 write_seqcount_end(&dentry->d_seq);
2333 write_seqcount_end(&anon->d_seq);
2334
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002335 dentry_unlock_parents_for_move(anon, dentry);
2336 spin_unlock(&dentry->d_lock);
2337
2338 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002339 anon->d_flags &= ~DCACHE_DISCONNECTED;
2340}
2341
2342/**
2343 * d_materialise_unique - introduce an inode into the tree
2344 * @dentry: candidate dentry
2345 * @inode: inode to bind to the dentry, to which aliases may be attached
2346 *
2347 * Introduces an dentry into the tree, substituting an extant disconnected
Jeff Laytonc46c8872011-07-26 13:33:16 -04002348 * root directory alias in its place if there is one. Caller must hold the
2349 * i_mutex of the parent directory.
David Howells770bfad2006-08-22 20:06:07 -04002350 */
2351struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2352{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002353 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002354
2355 BUG_ON(!d_unhashed(dentry));
2356
David Howells770bfad2006-08-22 20:06:07 -04002357 if (!inode) {
2358 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002359 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002360 d_rehash(actual);
2361 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002362 }
2363
Nick Piggin873feea2011-01-07 17:50:06 +11002364 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002365
Trond Myklebust9eaef272006-10-21 10:24:20 -07002366 if (S_ISDIR(inode->i_mode)) {
2367 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002368
Trond Myklebust9eaef272006-10-21 10:24:20 -07002369 /* Does an aliased dentry already exist? */
2370 alias = __d_find_alias(inode, 0);
2371 if (alias) {
2372 actual = alias;
Al Viro18367502011-07-12 21:42:24 -04002373 write_seqlock(&rename_lock);
2374
2375 if (d_ancestor(alias, dentry)) {
2376 /* Check for loops */
2377 actual = ERR_PTR(-ELOOP);
2378 } else if (IS_ROOT(alias)) {
2379 /* Is this an anonymous mountpoint that we
2380 * could splice into our tree? */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002381 __d_materialise_dentry(dentry, alias);
Al Viro18367502011-07-12 21:42:24 -04002382 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002383 __d_drop(alias);
2384 goto found;
Al Viro18367502011-07-12 21:42:24 -04002385 } else {
2386 /* Nope, but we must(!) avoid directory
2387 * aliasing */
2388 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002389 }
Al Viro18367502011-07-12 21:42:24 -04002390 write_sequnlock(&rename_lock);
David Howellsdd179942011-08-16 15:31:30 +01002391 if (IS_ERR(actual)) {
2392 if (PTR_ERR(actual) == -ELOOP)
2393 pr_warn_ratelimited(
2394 "VFS: Lookup of '%s' in %s %s"
2395 " would have caused loop\n",
2396 dentry->d_name.name,
2397 inode->i_sb->s_type->name,
2398 inode->i_sb->s_id);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002399 dput(alias);
David Howellsdd179942011-08-16 15:31:30 +01002400 }
Trond Myklebust9eaef272006-10-21 10:24:20 -07002401 goto out_nolock;
2402 }
David Howells770bfad2006-08-22 20:06:07 -04002403 }
2404
2405 /* Add a unique reference */
2406 actual = __d_instantiate_unique(dentry, inode);
2407 if (!actual)
2408 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002409 else
2410 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002411
David Howells770bfad2006-08-22 20:06:07 -04002412 spin_lock(&actual->d_lock);
2413found:
2414 _d_rehash(actual);
2415 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002416 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002417out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002418 if (actual == dentry) {
2419 security_d_instantiate(dentry, inode);
2420 return NULL;
2421 }
2422
2423 iput(inode);
2424 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002425}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002426EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002427
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002428static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002429{
2430 *buflen -= namelen;
2431 if (*buflen < 0)
2432 return -ENAMETOOLONG;
2433 *buffer -= namelen;
2434 memcpy(*buffer, str, namelen);
2435 return 0;
2436}
2437
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002438static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2439{
2440 return prepend(buffer, buflen, name->name, name->len);
2441}
2442
Linus Torvalds1da177e2005-04-16 15:20:36 -07002443/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002444 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002445 * @path: the dentry/vfsmount to report
Al Viro02125a82011-12-05 08:43:34 -05002446 * @root: root vfsmnt/dentry
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002447 * @buffer: pointer to the end of the buffer
2448 * @buflen: pointer to buffer length
2449 *
Nick Piggin949854d2011-01-07 17:49:37 +11002450 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002451 */
Al Viro02125a82011-12-05 08:43:34 -05002452static int prepend_path(const struct path *path,
2453 const struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002454 char **buffer, int *buflen)
2455{
2456 struct dentry *dentry = path->dentry;
2457 struct vfsmount *vfsmnt = path->mnt;
Al Viro0714a532011-11-24 22:19:58 -05002458 struct mount *mnt = real_mount(vfsmnt);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002459 bool slash = false;
2460 int error = 0;
2461
Nick Piggin99b7db72010-08-18 04:37:39 +10002462 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002463 while (dentry != root->dentry || vfsmnt != root->mnt) {
2464 struct dentry * parent;
2465
2466 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2467 /* Global root? */
Al Viro676da582011-11-24 21:47:05 -05002468 if (!mnt_has_parent(mnt))
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002469 goto global_root;
Al Viroa73324d2011-11-24 22:25:07 -05002470 dentry = mnt->mnt_mountpoint;
Al Viro0714a532011-11-24 22:19:58 -05002471 mnt = mnt->mnt_parent;
2472 vfsmnt = &mnt->mnt;
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002473 continue;
2474 }
2475 parent = dentry->d_parent;
2476 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002477 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002478 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002479 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002480 if (!error)
2481 error = prepend(buffer, buflen, "/", 1);
2482 if (error)
2483 break;
2484
2485 slash = true;
2486 dentry = parent;
2487 }
2488
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002489 if (!error && !slash)
2490 error = prepend(buffer, buflen, "/", 1);
2491
Al Viro02125a82011-12-05 08:43:34 -05002492out:
Nick Piggin99b7db72010-08-18 04:37:39 +10002493 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002494 return error;
2495
2496global_root:
2497 /*
2498 * Filesystems needing to implement special "root names"
2499 * should do so with ->d_dname()
2500 */
2501 if (IS_ROOT(dentry) &&
2502 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2503 WARN(1, "Root dentry has weird name <%.*s>\n",
2504 (int) dentry->d_name.len, dentry->d_name.name);
2505 }
Al Viro02125a82011-12-05 08:43:34 -05002506 if (!slash)
2507 error = prepend(buffer, buflen, "/", 1);
2508 if (!error)
Al Viro143c8c92011-11-25 00:46:35 -05002509 error = real_mount(vfsmnt)->mnt_ns ? 1 : 2;
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002510 goto out;
2511}
2512
2513/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002514 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002515 * @path: the dentry/vfsmount to report
Al Viro02125a82011-12-05 08:43:34 -05002516 * @root: root vfsmnt/dentry
Randy Dunlapcd956a12010-08-14 13:05:31 -07002517 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518 * @buflen: buffer length
2519 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002520 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002522 * Returns a pointer into the buffer or an error code if the
2523 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002524 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002525 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002526 *
Al Viro02125a82011-12-05 08:43:34 -05002527 * If the path is not reachable from the supplied root, return %NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002528 */
Al Viro02125a82011-12-05 08:43:34 -05002529char *__d_path(const struct path *path,
2530 const struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002531 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002532{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002533 char *res = buf + buflen;
2534 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002535
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002536 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002537 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002538 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002539 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002540
Al Viro02125a82011-12-05 08:43:34 -05002541 if (error < 0)
2542 return ERR_PTR(error);
2543 if (error > 0)
2544 return NULL;
2545 return res;
2546}
2547
2548char *d_absolute_path(const struct path *path,
2549 char *buf, int buflen)
2550{
2551 struct path root = {};
2552 char *res = buf + buflen;
2553 int error;
2554
2555 prepend(&res, &buflen, "\0", 1);
2556 write_seqlock(&rename_lock);
2557 error = prepend_path(path, &root, &res, &buflen);
2558 write_sequnlock(&rename_lock);
2559
2560 if (error > 1)
2561 error = -EINVAL;
2562 if (error < 0)
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002563 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002564 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565}
2566
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002567/*
2568 * same as __d_path but appends "(deleted)" for unlinked files.
2569 */
Al Viro02125a82011-12-05 08:43:34 -05002570static int path_with_deleted(const struct path *path,
2571 const struct path *root,
2572 char **buf, int *buflen)
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002573{
2574 prepend(buf, buflen, "\0", 1);
2575 if (d_unlinked(path->dentry)) {
2576 int error = prepend(buf, buflen, " (deleted)", 10);
2577 if (error)
2578 return error;
2579 }
2580
2581 return prepend_path(path, root, buf, buflen);
2582}
2583
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002584static int prepend_unreachable(char **buffer, int *buflen)
2585{
2586 return prepend(buffer, buflen, "(unreachable)", 13);
2587}
2588
Jan Bluncka03a8a702008-02-14 19:38:32 -08002589/**
2590 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002591 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002592 * @buf: buffer to return value in
2593 * @buflen: buffer length
2594 *
2595 * Convert a dentry into an ASCII path name. If the entry has been deleted
2596 * the string " (deleted)" is appended. Note that this is ambiguous.
2597 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002598 * Returns a pointer into the buffer or an error code if the path was
2599 * too long. Note: Callers should use the returned pointer, not the passed
2600 * in buffer, to use the name! The implementation often starts at an offset
2601 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002602 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002603 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002604 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002605char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002606{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002607 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002608 struct path root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002609 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002610
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002611 /*
2612 * We have various synthetic filesystems that never get mounted. On
2613 * these filesystems dentries are never used for lookup purposes, and
2614 * thus don't need to be hashed. They also don't need a name until a
2615 * user wants to identify the object in /proc/pid/fd/. The little hack
2616 * below allows us to generate a name for these objects on demand:
2617 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002618 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2619 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002620
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002621 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002622 write_seqlock(&rename_lock);
Al Viro02125a82011-12-05 08:43:34 -05002623 error = path_with_deleted(path, &root, &res, &buflen);
2624 if (error < 0)
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002625 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002626 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002627 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002628 return res;
2629}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002630EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002632/**
2633 * d_path_with_unreachable - return the path of a dentry
2634 * @path: path to report
2635 * @buf: buffer to return value in
2636 * @buflen: buffer length
2637 *
2638 * The difference from d_path() is that this prepends "(unreachable)"
2639 * to paths which are unreachable from the current process' root.
2640 */
2641char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2642{
2643 char *res = buf + buflen;
2644 struct path root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002645 int error;
2646
2647 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2648 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2649
2650 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002651 write_seqlock(&rename_lock);
Al Viro02125a82011-12-05 08:43:34 -05002652 error = path_with_deleted(path, &root, &res, &buflen);
2653 if (error > 0)
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002654 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002655 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002656 path_put(&root);
2657 if (error)
2658 res = ERR_PTR(error);
2659
2660 return res;
2661}
2662
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002664 * Helper function for dentry_operations.d_dname() members
2665 */
2666char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2667 const char *fmt, ...)
2668{
2669 va_list args;
2670 char temp[64];
2671 int sz;
2672
2673 va_start(args, fmt);
2674 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2675 va_end(args);
2676
2677 if (sz > sizeof(temp) || sz > buflen)
2678 return ERR_PTR(-ENAMETOOLONG);
2679
2680 buffer += buflen - sz;
2681 return memcpy(buffer, temp, sz);
2682}
2683
2684/*
Ram Pai6092d042008-03-27 13:06:20 +01002685 * Write full pathname from the root of the filesystem into the buffer.
2686 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002687static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002688{
2689 char *end = buf + buflen;
2690 char *retval;
2691
Ram Pai6092d042008-03-27 13:06:20 +01002692 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002693 if (buflen < 1)
2694 goto Elong;
2695 /* Get '/' right */
2696 retval = end-1;
2697 *retval = '/';
2698
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002699 while (!IS_ROOT(dentry)) {
2700 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002701 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002702
Ram Pai6092d042008-03-27 13:06:20 +01002703 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002704 spin_lock(&dentry->d_lock);
2705 error = prepend_name(&end, &buflen, &dentry->d_name);
2706 spin_unlock(&dentry->d_lock);
2707 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002708 goto Elong;
2709
2710 retval = end;
2711 dentry = parent;
2712 }
Al Viroc1031352010-06-06 22:31:14 -04002713 return retval;
2714Elong:
2715 return ERR_PTR(-ENAMETOOLONG);
2716}
Nick Pigginec2447c2011-01-07 17:49:29 +11002717
2718char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2719{
2720 char *retval;
2721
Nick Piggin949854d2011-01-07 17:49:37 +11002722 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002723 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002724 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002725
2726 return retval;
2727}
2728EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002729
2730char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2731{
2732 char *p = NULL;
2733 char *retval;
2734
Nick Piggin949854d2011-01-07 17:49:37 +11002735 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002736 if (d_unlinked(dentry)) {
2737 p = buf + buflen;
2738 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2739 goto Elong;
2740 buflen++;
2741 }
2742 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002743 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002744 if (!IS_ERR(retval) && p)
2745 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002746 return retval;
2747Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002748 return ERR_PTR(-ENAMETOOLONG);
2749}
2750
2751/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002752 * NOTE! The user-level library version returns a
2753 * character pointer. The kernel system call just
2754 * returns the length of the buffer filled (which
2755 * includes the ending '\0' character), or a negative
2756 * error value. So libc would do something like
2757 *
2758 * char *getcwd(char * buf, size_t size)
2759 * {
2760 * int retval;
2761 *
2762 * retval = sys_getcwd(buf, size);
2763 * if (retval >= 0)
2764 * return buf;
2765 * errno = -retval;
2766 * return NULL;
2767 * }
2768 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002769SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002770{
Linus Torvalds552ce542007-02-13 12:08:18 -08002771 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002772 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002773 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002774
2775 if (!page)
2776 return -ENOMEM;
2777
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002778 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002779
Linus Torvalds552ce542007-02-13 12:08:18 -08002780 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002781 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002782 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002783 unsigned long len;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002784 char *cwd = page + PAGE_SIZE;
2785 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002786
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002787 prepend(&cwd, &buflen, "\0", 1);
Al Viro02125a82011-12-05 08:43:34 -05002788 error = prepend_path(&pwd, &root, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002789 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002790
Al Viro02125a82011-12-05 08:43:34 -05002791 if (error < 0)
Linus Torvalds552ce542007-02-13 12:08:18 -08002792 goto out;
2793
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002794 /* Unreachable from current root */
Al Viro02125a82011-12-05 08:43:34 -05002795 if (error > 0) {
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002796 error = prepend_unreachable(&cwd, &buflen);
2797 if (error)
2798 goto out;
2799 }
2800
Linus Torvalds552ce542007-02-13 12:08:18 -08002801 error = -ERANGE;
2802 len = PAGE_SIZE + page - cwd;
2803 if (len <= size) {
2804 error = len;
2805 if (copy_to_user(buf, cwd, len))
2806 error = -EFAULT;
2807 }
Nick Piggin949854d2011-01-07 17:49:37 +11002808 } else {
2809 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002810 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002811
2812out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002813 path_put(&pwd);
2814 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815 free_page((unsigned long) page);
2816 return error;
2817}
2818
2819/*
2820 * Test whether new_dentry is a subdirectory of old_dentry.
2821 *
2822 * Trivially implemented using the dcache structure
2823 */
2824
2825/**
2826 * is_subdir - is new dentry a subdirectory of old_dentry
2827 * @new_dentry: new dentry
2828 * @old_dentry: old dentry
2829 *
2830 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2831 * Returns 0 otherwise.
2832 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2833 */
2834
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002835int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836{
2837 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002838 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002839
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002840 if (new_dentry == old_dentry)
2841 return 1;
2842
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002843 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002844 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002846 /*
2847 * Need rcu_readlock to protect against the d_parent trashing
2848 * due to d_move
2849 */
2850 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002851 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002852 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002853 else
2854 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002855 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002856 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002857
2858 return result;
2859}
2860
2861void d_genocide(struct dentry *root)
2862{
Nick Piggin949854d2011-01-07 17:49:37 +11002863 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002864 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002865 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002866 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867
Nick Piggin949854d2011-01-07 17:49:37 +11002868 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002869again:
2870 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002871 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002872repeat:
2873 next = this_parent->d_subdirs.next;
2874resume:
2875 while (next != &this_parent->d_subdirs) {
2876 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002877 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002878 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002879
Nick Pigginda502952011-01-07 17:49:33 +11002880 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2881 if (d_unhashed(dentry) || !dentry->d_inode) {
2882 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002883 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002884 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002885 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002886 spin_unlock(&this_parent->d_lock);
2887 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002888 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002889 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002890 goto repeat;
2891 }
Nick Piggin949854d2011-01-07 17:49:37 +11002892 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2893 dentry->d_flags |= DCACHE_GENOCIDE;
2894 dentry->d_count--;
2895 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002896 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002897 }
2898 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002899 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002900 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2901 this_parent->d_flags |= DCACHE_GENOCIDE;
2902 this_parent->d_count--;
2903 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002904 this_parent = try_to_ascend(this_parent, locked, seq);
2905 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002906 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002907 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002908 goto resume;
2909 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002910 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002911 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002912 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002913 if (locked)
2914 write_sequnlock(&rename_lock);
2915 return;
2916
2917rename_retry:
2918 locked = 1;
2919 write_seqlock(&rename_lock);
2920 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002921}
2922
2923/**
2924 * find_inode_number - check for dentry with name
2925 * @dir: directory to check
2926 * @name: Name to find.
2927 *
2928 * Check whether a dentry already exists for the given name,
2929 * and return the inode number if it has an inode. Otherwise
2930 * 0 is returned.
2931 *
2932 * This routine is used to post-process directory listings for
2933 * filesystems using synthetic inode numbers, and is necessary
2934 * to keep getcwd() working.
2935 */
2936
2937ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2938{
2939 struct dentry * dentry;
2940 ino_t ino = 0;
2941
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002942 dentry = d_hash_and_lookup(dir, name);
2943 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002944 if (dentry->d_inode)
2945 ino = dentry->d_inode->i_ino;
2946 dput(dentry);
2947 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002948 return ino;
2949}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002950EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002951
2952static __initdata unsigned long dhash_entries;
2953static int __init set_dhash_entries(char *str)
2954{
2955 if (!str)
2956 return 0;
2957 dhash_entries = simple_strtoul(str, &str, 0);
2958 return 1;
2959}
2960__setup("dhash_entries=", set_dhash_entries);
2961
2962static void __init dcache_init_early(void)
2963{
2964 int loop;
2965
2966 /* If hashes are distributed across NUMA nodes, defer
2967 * hash allocation until vmalloc space is available.
2968 */
2969 if (hashdist)
2970 return;
2971
2972 dentry_hashtable =
2973 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002974 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07002975 dhash_entries,
2976 13,
2977 HASH_EARLY,
2978 &d_hash_shift,
2979 &d_hash_mask,
2980 0);
2981
2982 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002983 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002984}
2985
Denis Cheng74bf17c2007-10-16 23:26:30 -07002986static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002987{
2988 int loop;
2989
2990 /*
2991 * A constructor could be added for stable state like the lists,
2992 * but it is probably not worth it because of the cache nature
2993 * of the dcache.
2994 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07002995 dentry_cache = KMEM_CACHE(dentry,
2996 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002997
2998 /* Hash may have been set up in dcache_init_early */
2999 if (!hashdist)
3000 return;
3001
3002 dentry_hashtable =
3003 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003004 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07003005 dhash_entries,
3006 13,
3007 0,
3008 &d_hash_shift,
3009 &d_hash_mask,
3010 0);
3011
3012 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003013 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003014}
3015
3016/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08003017struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003018EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003019
Linus Torvalds1da177e2005-04-16 15:20:36 -07003020EXPORT_SYMBOL(d_genocide);
3021
Linus Torvalds1da177e2005-04-16 15:20:36 -07003022void __init vfs_caches_init_early(void)
3023{
3024 dcache_init_early();
3025 inode_init_early();
3026}
3027
3028void __init vfs_caches_init(unsigned long mempages)
3029{
3030 unsigned long reserve;
3031
3032 /* Base hash sizes on available memory, with a reserve equal to
3033 150% of current kernel size */
3034
3035 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3036 mempages -= reserve;
3037
3038 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003039 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003040
Denis Cheng74bf17c2007-10-16 23:26:30 -07003041 dcache_init();
3042 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003043 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003044 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003045 bdev_cache_init();
3046 chrdev_init();
3047}