blob: 2762804a140db03cb432648a1b38d910f24f640d [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/dcache.c
3 *
4 * Complete reimplementation
5 * (C) 1997 Thomas Schoebel-Theuer,
6 * with heavy changes by Linus Torvalds
7 */
8
9/*
10 * Notes on the allocation strategy:
11 *
12 * The dcache is a master of the icache - whenever a dcache entry
13 * exists, the inode will always exist. "iput()" is done either when
14 * the dcache entry is deleted or garbage collected.
15 */
16
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/syscalls.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/fs.h>
John McCutchan7a91bf72005-08-08 13:52:16 -040021#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/slab.h>
23#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/hash.h>
25#include <linux/cache.h>
26#include <linux/module.h>
27#include <linux/mount.h>
28#include <linux/file.h>
29#include <asm/uaccess.h>
30#include <linux/security.h>
31#include <linux/seqlock.h>
32#include <linux/swap.h>
33#include <linux/bootmem.h>
Al Viro5ad4e532009-03-29 19:50:06 -040034#include <linux/fs_struct.h>
Frederic Weisbecker613afbf2009-07-16 15:44:29 +020035#include <linux/hardirq.h>
Nick Pigginceb5bdc2011-01-07 17:50:05 +110036#include <linux/bit_spinlock.h>
37#include <linux/rculist_bl.h>
Linus Torvalds268bb0c2011-05-20 12:50:29 -070038#include <linux/prefetch.h>
David Howells07f3f052006-09-30 20:52:18 +020039#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
Nick Piggin789680d2011-01-07 17:49:30 +110041/*
42 * Usage:
Nick Piggin873feea2011-01-07 17:50:06 +110043 * dcache->d_inode->i_lock protects:
44 * - i_dentry, d_alias, d_inode of aliases
Nick Pigginceb5bdc2011-01-07 17:50:05 +110045 * dcache_hash_bucket lock protects:
46 * - the dcache hash table
47 * s_anon bl list spinlock protects:
48 * - the s_anon list (see __d_drop)
Nick Piggin23044502011-01-07 17:49:31 +110049 * dcache_lru_lock protects:
50 * - the dcache lru lists and counters
51 * d_lock protects:
52 * - d_flags
53 * - d_name
54 * - d_lru
Nick Pigginb7ab39f2011-01-07 17:49:32 +110055 * - d_count
Nick Pigginda502952011-01-07 17:49:33 +110056 * - d_unhashed()
Nick Piggin2fd6b7f2011-01-07 17:49:34 +110057 * - d_parent and d_subdirs
58 * - childrens' d_child and d_parent
Nick Pigginb23fb0a2011-01-07 17:49:35 +110059 * - d_alias, d_inode
Nick Piggin789680d2011-01-07 17:49:30 +110060 *
61 * Ordering:
Nick Piggin873feea2011-01-07 17:50:06 +110062 * dentry->d_inode->i_lock
Nick Pigginb5c84bf2011-01-07 17:49:38 +110063 * dentry->d_lock
64 * dcache_lru_lock
Nick Pigginceb5bdc2011-01-07 17:50:05 +110065 * dcache_hash_bucket lock
66 * s_anon lock
Nick Piggin789680d2011-01-07 17:49:30 +110067 *
Nick Pigginda502952011-01-07 17:49:33 +110068 * If there is an ancestor relationship:
69 * dentry->d_parent->...->d_parent->d_lock
70 * ...
71 * dentry->d_parent->d_lock
72 * dentry->d_lock
73 *
74 * If no ancestor relationship:
Nick Piggin789680d2011-01-07 17:49:30 +110075 * if (dentry1 < dentry2)
76 * dentry1->d_lock
77 * dentry2->d_lock
78 */
Eric Dumazetfa3536c2006-03-26 01:37:24 -080079int sysctl_vfs_cache_pressure __read_mostly = 100;
Linus Torvalds1da177e2005-04-16 15:20:36 -070080EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
81
Nick Piggin23044502011-01-07 17:49:31 +110082static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
Al Viro74c3cbe2007-07-22 08:04:18 -040083__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Nick Piggin949854d2011-01-07 17:49:37 +110085EXPORT_SYMBOL(rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
Christoph Lametere18b8902006-12-06 20:33:20 -080087static struct kmem_cache *dentry_cache __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
Linus Torvalds1da177e2005-04-16 15:20:36 -070089/*
90 * This is the single most critical data structure when it comes
91 * to the dcache: the hashtable for lookups. Somebody should try
92 * to make this good - I've just made it work.
93 *
94 * This hash-function tries to avoid losing too many bits of hash
95 * information, yet avoid using a prime hash-size or similar.
96 */
97#define D_HASHBITS d_hash_shift
98#define D_HASHMASK d_hash_mask
99
Eric Dumazetfa3536c2006-03-26 01:37:24 -0800100static unsigned int d_hash_mask __read_mostly;
101static unsigned int d_hash_shift __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100102
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700103static struct hlist_bl_head *dentry_hashtable __read_mostly;
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100104
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700105static inline struct hlist_bl_head *d_hash(struct dentry *parent,
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100106 unsigned long hash)
107{
108 hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
109 hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
110 return dentry_hashtable + (hash & D_HASHMASK);
111}
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113/* Statistics gathering. */
114struct dentry_stat_t dentry_stat = {
115 .age_limit = 45,
116};
117
Nick Piggin3e880fb2011-01-07 17:49:19 +1100118static DEFINE_PER_CPU(unsigned int, nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400119
120#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Nick Piggin3e880fb2011-01-07 17:49:19 +1100121static int get_nr_dentry(void)
122{
123 int i;
124 int sum = 0;
125 for_each_possible_cpu(i)
126 sum += per_cpu(nr_dentry, i);
127 return sum < 0 ? 0 : sum;
128}
129
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400130int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
131 size_t *lenp, loff_t *ppos)
132{
Nick Piggin3e880fb2011-01-07 17:49:19 +1100133 dentry_stat.nr_dentry = get_nr_dentry();
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400134 return proc_dointvec(table, write, buffer, lenp, ppos);
135}
136#endif
137
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400138static void __d_free(struct rcu_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139{
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400140 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
141
Arjan van de Venfd217f42008-10-21 06:47:33 -0700142 WARN_ON(!list_empty(&dentry->d_alias));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 if (dname_external(dentry))
144 kfree(dentry->d_name.name);
145 kmem_cache_free(dentry_cache, dentry);
146}
147
148/*
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100149 * no locks, please.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 */
151static void d_free(struct dentry *dentry)
152{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100153 BUG_ON(dentry->d_count);
Nick Piggin3e880fb2011-01-07 17:49:19 +1100154 this_cpu_dec(nr_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 if (dentry->d_op && dentry->d_op->d_release)
156 dentry->d_op->d_release(dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400157
Linus Torvaldsdea36672011-04-24 07:58:46 -0700158 /* if dentry was never visible to RCU, immediate free is OK */
159 if (!(dentry->d_flags & DCACHE_RCUACCESS))
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400160 __d_free(&dentry->d_u.d_rcu);
Eric Dumazetb3423412006-12-06 20:38:48 -0800161 else
Christoph Hellwig9c82ab92010-10-10 05:36:22 -0400162 call_rcu(&dentry->d_u.d_rcu, __d_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163}
164
Nick Piggin31e6b012011-01-07 17:49:52 +1100165/**
166 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800167 * @dentry: the target dentry
Nick Piggin31e6b012011-01-07 17:49:52 +1100168 * After this call, in-progress rcu-walk path lookup will fail. This
169 * should be called after unhashing, and after changing d_inode (if
170 * the dentry has not already been unhashed).
171 */
172static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
173{
174 assert_spin_locked(&dentry->d_lock);
175 /* Go through a barrier */
176 write_seqcount_barrier(&dentry->d_seq);
177}
178
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179/*
180 * Release the dentry's inode, using the filesystem
Nick Piggin31e6b012011-01-07 17:49:52 +1100181 * d_iput() operation if defined. Dentry has no refcount
182 * and is unhashed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800184static void dentry_iput(struct dentry * dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200185 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100186 __releases(dentry->d_inode->i_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187{
188 struct inode *inode = dentry->d_inode;
189 if (inode) {
190 dentry->d_inode = NULL;
191 list_del_init(&dentry->d_alias);
192 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100193 spin_unlock(&inode->i_lock);
Linus Torvaldsf805fbd2005-09-19 19:54:29 -0700194 if (!inode->i_nlink)
195 fsnotify_inoderemove(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 if (dentry->d_op && dentry->d_op->d_iput)
197 dentry->d_op->d_iput(dentry, inode);
198 else
199 iput(inode);
200 } else {
201 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 }
203}
204
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700205/*
Nick Piggin31e6b012011-01-07 17:49:52 +1100206 * Release the dentry's inode, using the filesystem
207 * d_iput() operation if defined. dentry remains in-use.
208 */
209static void dentry_unlink_inode(struct dentry * dentry)
210 __releases(dentry->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100211 __releases(dentry->d_inode->i_lock)
Nick Piggin31e6b012011-01-07 17:49:52 +1100212{
213 struct inode *inode = dentry->d_inode;
214 dentry->d_inode = NULL;
215 list_del_init(&dentry->d_alias);
216 dentry_rcuwalk_barrier(dentry);
217 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100218 spin_unlock(&inode->i_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +1100219 if (!inode->i_nlink)
220 fsnotify_inoderemove(inode);
221 if (dentry->d_op && dentry->d_op->d_iput)
222 dentry->d_op->d_iput(dentry, inode);
223 else
224 iput(inode);
225}
226
227/*
Nick Piggin23044502011-01-07 17:49:31 +1100228 * dentry_lru_(add|del|move_tail) must be called with d_lock held.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700229 */
230static void dentry_lru_add(struct dentry *dentry)
231{
Christoph Hellwiga4633352010-10-10 05:36:26 -0400232 if (list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100233 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400234 list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
235 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100236 dentry_stat.nr_unused++;
Nick Piggin23044502011-01-07 17:49:31 +1100237 spin_unlock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400238 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700239}
240
Nick Piggin23044502011-01-07 17:49:31 +1100241static void __dentry_lru_del(struct dentry *dentry)
242{
243 list_del_init(&dentry->d_lru);
244 dentry->d_sb->s_nr_dentry_unused--;
245 dentry_stat.nr_unused--;
246}
247
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700248static void dentry_lru_del(struct dentry *dentry)
249{
250 if (!list_empty(&dentry->d_lru)) {
Nick Piggin23044502011-01-07 17:49:31 +1100251 spin_lock(&dcache_lru_lock);
252 __dentry_lru_del(dentry);
253 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700254 }
255}
256
Christoph Hellwiga4633352010-10-10 05:36:26 -0400257static void dentry_lru_move_tail(struct dentry *dentry)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700258{
Nick Piggin23044502011-01-07 17:49:31 +1100259 spin_lock(&dcache_lru_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400260 if (list_empty(&dentry->d_lru)) {
261 list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
262 dentry->d_sb->s_nr_dentry_unused++;
Nick Piggin86c87492011-01-07 17:49:18 +1100263 dentry_stat.nr_unused++;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400264 } else {
265 list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700266 }
Nick Piggin23044502011-01-07 17:49:31 +1100267 spin_unlock(&dcache_lru_lock);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700268}
269
Miklos Szeredid52b9082007-05-08 00:23:46 -0700270/**
271 * d_kill - kill dentry and return parent
272 * @dentry: dentry to kill
Randy Dunlapff5fdb62011-01-22 20:16:06 -0800273 * @parent: parent dentry
Miklos Szeredid52b9082007-05-08 00:23:46 -0700274 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200275 * The dentry must already be unhashed and removed from the LRU.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700276 *
277 * If this is the root of the dentry tree, return NULL.
Nick Piggin23044502011-01-07 17:49:31 +1100278 *
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100279 * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
280 * d_kill.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700281 */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100282static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200283 __releases(dentry->d_lock)
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100284 __releases(parent->d_lock)
Nick Piggin873feea2011-01-07 17:50:06 +1100285 __releases(dentry->d_inode->i_lock)
Miklos Szeredid52b9082007-05-08 00:23:46 -0700286{
Miklos Szeredid52b9082007-05-08 00:23:46 -0700287 list_del(&dentry->d_u.d_child);
Trond Myklebustc83ce982011-03-15 13:36:43 -0400288 /*
289 * Inform try_to_ascend() that we are no longer attached to the
290 * dentry tree
291 */
292 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100293 if (parent)
294 spin_unlock(&parent->d_lock);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700295 dentry_iput(dentry);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100296 /*
297 * dentry_iput drops the locks, at which point nobody (except
298 * transient RCU lookups) can reach this dentry.
299 */
Miklos Szeredid52b9082007-05-08 00:23:46 -0700300 d_free(dentry);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900301 return parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700302}
303
Nick Piggin789680d2011-01-07 17:49:30 +1100304/**
305 * d_drop - drop a dentry
306 * @dentry: dentry to drop
307 *
308 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
309 * be found through a VFS lookup any more. Note that this is different from
310 * deleting the dentry - d_delete will try to mark the dentry negative if
311 * possible, giving a successful _negative_ lookup, while d_drop will
312 * just make the cache lookup fail.
313 *
314 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
315 * reason (NFS timeouts or autofs deletes).
316 *
317 * __d_drop requires dentry->d_lock.
318 */
319void __d_drop(struct dentry *dentry)
320{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700321 if (!d_unhashed(dentry)) {
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700322 struct hlist_bl_head *b;
Linus Torvaldsdea36672011-04-24 07:58:46 -0700323 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
Linus Torvaldsb07ad992011-04-23 22:32:03 -0700324 b = &dentry->d_sb->s_anon;
Linus Torvaldsdea36672011-04-24 07:58:46 -0700325 else
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100326 b = d_hash(dentry->d_parent, dentry->d_name.hash);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700327
Christoph Hellwig1879fd62011-04-25 14:01:36 -0400328 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700329 __hlist_bl_del(&dentry->d_hash);
330 dentry->d_hash.pprev = NULL;
Christoph Hellwig1879fd62011-04-25 14:01:36 -0400331 hlist_bl_unlock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -0700332
333 dentry_rcuwalk_barrier(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +1100334 }
335}
336EXPORT_SYMBOL(__d_drop);
337
338void d_drop(struct dentry *dentry)
339{
Nick Piggin789680d2011-01-07 17:49:30 +1100340 spin_lock(&dentry->d_lock);
341 __d_drop(dentry);
342 spin_unlock(&dentry->d_lock);
Nick Piggin789680d2011-01-07 17:49:30 +1100343}
344EXPORT_SYMBOL(d_drop);
345
Nick Piggin77812a12011-01-07 17:49:48 +1100346/*
Josef Bacik44396f42011-05-31 11:58:49 -0400347 * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag
348 * @dentry: dentry to drop
349 *
350 * This is called when we do a lookup on a placeholder dentry that needed to be
351 * looked up. The dentry should have been hashed in order for it to be found by
352 * the lookup code, but now needs to be unhashed while we do the actual lookup
353 * and clear the DCACHE_NEED_LOOKUP flag.
354 */
355void d_clear_need_lookup(struct dentry *dentry)
356{
357 spin_lock(&dentry->d_lock);
358 __d_drop(dentry);
359 dentry->d_flags &= ~DCACHE_NEED_LOOKUP;
360 spin_unlock(&dentry->d_lock);
361}
362EXPORT_SYMBOL(d_clear_need_lookup);
363
364/*
Nick Piggin77812a12011-01-07 17:49:48 +1100365 * Finish off a dentry we've decided to kill.
366 * dentry->d_lock must be held, returns with it unlocked.
367 * If ref is non-zero, then decrement the refcount too.
368 * Returns dentry requiring refcount drop, or NULL if we're done.
369 */
370static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
371 __releases(dentry->d_lock)
372{
Nick Piggin873feea2011-01-07 17:50:06 +1100373 struct inode *inode;
Nick Piggin77812a12011-01-07 17:49:48 +1100374 struct dentry *parent;
375
Nick Piggin873feea2011-01-07 17:50:06 +1100376 inode = dentry->d_inode;
377 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin77812a12011-01-07 17:49:48 +1100378relock:
379 spin_unlock(&dentry->d_lock);
380 cpu_relax();
381 return dentry; /* try again with same dentry */
382 }
383 if (IS_ROOT(dentry))
384 parent = NULL;
385 else
386 parent = dentry->d_parent;
387 if (parent && !spin_trylock(&parent->d_lock)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100388 if (inode)
389 spin_unlock(&inode->i_lock);
Nick Piggin77812a12011-01-07 17:49:48 +1100390 goto relock;
391 }
Nick Piggin31e6b012011-01-07 17:49:52 +1100392
Nick Piggin77812a12011-01-07 17:49:48 +1100393 if (ref)
394 dentry->d_count--;
395 /* if dentry was on the d_lru list delete it from there */
396 dentry_lru_del(dentry);
397 /* if it was on the hash then remove it */
398 __d_drop(dentry);
399 return d_kill(dentry, parent);
400}
401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402/*
403 * This is dput
404 *
405 * This is complicated by the fact that we do not want to put
406 * dentries that are no longer on any hash chain on the unused
407 * list: we'd much rather just get rid of them immediately.
408 *
409 * However, that implies that we have to traverse the dentry
410 * tree upwards to the parents which might _also_ now be
411 * scheduled for deletion (it may have been only waiting for
412 * its last child to go away).
413 *
414 * This tail recursion is done by hand as we don't want to depend
415 * on the compiler to always get this right (gcc generally doesn't).
416 * Real recursion would eat up our stack space.
417 */
418
419/*
420 * dput - release a dentry
421 * @dentry: dentry to release
422 *
423 * Release a dentry. This will drop the usage count and if appropriate
424 * call the dentry unlink method as well as removing it from the queues and
425 * releasing its resources. If the parent dentries were scheduled for release
426 * they too may now get deleted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428void dput(struct dentry *dentry)
429{
430 if (!dentry)
431 return;
432
433repeat:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100434 if (dentry->d_count == 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 spin_lock(&dentry->d_lock);
Nick Piggin61f3dee2011-01-07 17:49:40 +1100437 BUG_ON(!dentry->d_count);
438 if (dentry->d_count > 1) {
439 dentry->d_count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 return;
442 }
443
Nick Pigginfb045ad2011-01-07 17:49:55 +1100444 if (dentry->d_flags & DCACHE_OP_DELETE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 if (dentry->d_op->d_delete(dentry))
Nick Piggin61f3dee2011-01-07 17:49:40 +1100446 goto kill_it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 }
Nick Piggin265ac902010-10-10 05:36:24 -0400448
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 /* Unreachable? Get rid of it */
450 if (d_unhashed(dentry))
451 goto kill_it;
Nick Piggin265ac902010-10-10 05:36:24 -0400452
Josef Bacik44396f42011-05-31 11:58:49 -0400453 /*
454 * If this dentry needs lookup, don't set the referenced flag so that it
455 * is more likely to be cleaned up by the dcache shrinker in case of
456 * memory pressure.
457 */
458 if (!d_need_lookup(dentry))
459 dentry->d_flags |= DCACHE_REFERENCED;
Christoph Hellwiga4633352010-10-10 05:36:26 -0400460 dentry_lru_add(dentry);
Nick Piggin265ac902010-10-10 05:36:24 -0400461
Nick Piggin61f3dee2011-01-07 17:49:40 +1100462 dentry->d_count--;
463 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 return;
465
Miklos Szeredid52b9082007-05-08 00:23:46 -0700466kill_it:
Nick Piggin77812a12011-01-07 17:49:48 +1100467 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700468 if (dentry)
469 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700471EXPORT_SYMBOL(dput);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473/**
474 * d_invalidate - invalidate a dentry
475 * @dentry: dentry to invalidate
476 *
477 * Try to invalidate the dentry if it turns out to be
478 * possible. If there are other dentries that can be
479 * reached through this one we can't delete it and we
480 * return -EBUSY. On success we return 0.
481 *
482 * no dcache lock.
483 */
484
485int d_invalidate(struct dentry * dentry)
486{
487 /*
488 * If it's already been dropped, return OK.
489 */
Nick Pigginda502952011-01-07 17:49:33 +1100490 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 if (d_unhashed(dentry)) {
Nick Pigginda502952011-01-07 17:49:33 +1100492 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 return 0;
494 }
495 /*
496 * Check whether to do a partial shrink_dcache
497 * to get rid of unused child entries.
498 */
499 if (!list_empty(&dentry->d_subdirs)) {
Nick Pigginda502952011-01-07 17:49:33 +1100500 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 shrink_dcache_parent(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100502 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 }
504
505 /*
506 * Somebody else still using it?
507 *
508 * If it's a directory, we can't drop it
509 * for fear of somebody re-populating it
510 * with children (even though dropping it
511 * would make it unreachable from the root,
512 * we might still populate it if it was a
513 * working directory or similar).
514 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100515 if (dentry->d_count > 1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) {
517 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 return -EBUSY;
519 }
520 }
521
522 __d_drop(dentry);
523 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 return 0;
525}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700526EXPORT_SYMBOL(d_invalidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100528/* This must be called with d_lock held */
Nick Piggindc0474b2011-01-07 17:49:43 +1100529static inline void __dget_dlock(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530{
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100531 dentry->d_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532}
533
Nick Piggindc0474b2011-01-07 17:49:43 +1100534static inline void __dget(struct dentry *dentry)
Nick Piggin23044502011-01-07 17:49:31 +1100535{
Nick Piggin23044502011-01-07 17:49:31 +1100536 spin_lock(&dentry->d_lock);
Nick Piggindc0474b2011-01-07 17:49:43 +1100537 __dget_dlock(dentry);
Nick Piggin23044502011-01-07 17:49:31 +1100538 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100539}
540
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100541struct dentry *dget_parent(struct dentry *dentry)
542{
543 struct dentry *ret;
544
545repeat:
Nick Piggina734eb42011-01-07 17:49:44 +1100546 /*
547 * Don't need rcu_dereference because we re-check it was correct under
548 * the lock.
549 */
550 rcu_read_lock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100551 ret = dentry->d_parent;
Nick Piggina734eb42011-01-07 17:49:44 +1100552 if (!ret) {
553 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100554 goto out;
555 }
Nick Piggina734eb42011-01-07 17:49:44 +1100556 spin_lock(&ret->d_lock);
557 if (unlikely(ret != dentry->d_parent)) {
558 spin_unlock(&ret->d_lock);
559 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100560 goto repeat;
561 }
Nick Piggina734eb42011-01-07 17:49:44 +1100562 rcu_read_unlock();
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100563 BUG_ON(!ret->d_count);
564 ret->d_count++;
565 spin_unlock(&ret->d_lock);
566out:
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100567 return ret;
568}
569EXPORT_SYMBOL(dget_parent);
570
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571/**
572 * d_find_alias - grab a hashed alias of inode
573 * @inode: inode in question
574 * @want_discon: flag, used by d_splice_alias, to request
575 * that only a DISCONNECTED alias be returned.
576 *
577 * If inode has a hashed alias, or is a directory and has any alias,
578 * acquire the reference to alias and return it. Otherwise return NULL.
579 * Notice that if inode is a directory there can be only one alias and
580 * it can be unhashed only if it has no children, or if it is the root
581 * of a filesystem.
582 *
NeilBrown21c0d8f2006-10-04 02:16:16 -0700583 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 * any other hashed alias over that one unless @want_discon is set,
NeilBrown21c0d8f2006-10-04 02:16:16 -0700585 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 */
Nick Pigginda502952011-01-07 17:49:33 +1100587static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588{
Nick Pigginda502952011-01-07 17:49:33 +1100589 struct dentry *alias, *discon_alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
Nick Pigginda502952011-01-07 17:49:33 +1100591again:
592 discon_alias = NULL;
593 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
594 spin_lock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
NeilBrown21c0d8f2006-10-04 02:16:16 -0700596 if (IS_ROOT(alias) &&
Nick Pigginda502952011-01-07 17:49:33 +1100597 (alias->d_flags & DCACHE_DISCONNECTED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 discon_alias = alias;
Nick Pigginda502952011-01-07 17:49:33 +1100599 } else if (!want_discon) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100600 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100601 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602 return alias;
603 }
604 }
Nick Pigginda502952011-01-07 17:49:33 +1100605 spin_unlock(&alias->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 }
Nick Pigginda502952011-01-07 17:49:33 +1100607 if (discon_alias) {
608 alias = discon_alias;
609 spin_lock(&alias->d_lock);
610 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
611 if (IS_ROOT(alias) &&
612 (alias->d_flags & DCACHE_DISCONNECTED)) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100613 __dget_dlock(alias);
Nick Pigginda502952011-01-07 17:49:33 +1100614 spin_unlock(&alias->d_lock);
615 return alias;
616 }
617 }
618 spin_unlock(&alias->d_lock);
619 goto again;
620 }
621 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622}
623
Nick Pigginda502952011-01-07 17:49:33 +1100624struct dentry *d_find_alias(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625{
David Howells214fda12006-03-25 03:06:36 -0800626 struct dentry *de = NULL;
627
628 if (!list_empty(&inode->i_dentry)) {
Nick Piggin873feea2011-01-07 17:50:06 +1100629 spin_lock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800630 de = __d_find_alias(inode, 0);
Nick Piggin873feea2011-01-07 17:50:06 +1100631 spin_unlock(&inode->i_lock);
David Howells214fda12006-03-25 03:06:36 -0800632 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 return de;
634}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700635EXPORT_SYMBOL(d_find_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
637/*
638 * Try to kill dentries associated with this inode.
639 * WARNING: you must own a reference to inode.
640 */
641void d_prune_aliases(struct inode *inode)
642{
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700643 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644restart:
Nick Piggin873feea2011-01-07 17:50:06 +1100645 spin_lock(&inode->i_lock);
Domen Puncer0cdca3f2005-09-10 00:27:07 -0700646 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 spin_lock(&dentry->d_lock);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100648 if (!dentry->d_count) {
Nick Piggindc0474b2011-01-07 17:49:43 +1100649 __dget_dlock(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 __d_drop(dentry);
651 spin_unlock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +1100652 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 dput(dentry);
654 goto restart;
655 }
656 spin_unlock(&dentry->d_lock);
657 }
Nick Piggin873feea2011-01-07 17:50:06 +1100658 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700660EXPORT_SYMBOL(d_prune_aliases);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661
662/*
Nick Piggin77812a12011-01-07 17:49:48 +1100663 * Try to throw away a dentry - free the inode, dput the parent.
664 * Requires dentry->d_lock is held, and dentry->d_count == 0.
665 * Releases dentry->d_lock.
Andrew Mortond702ccb2006-06-22 14:47:31 -0700666 *
Nick Piggin77812a12011-01-07 17:49:48 +1100667 * This may fail if locks cannot be acquired no problem, just try again.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 */
Nick Piggin77812a12011-01-07 17:49:48 +1100669static void try_prune_one_dentry(struct dentry *dentry)
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +0200670 __releases(dentry->d_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671{
Nick Piggin77812a12011-01-07 17:49:48 +1100672 struct dentry *parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700673
Nick Piggin77812a12011-01-07 17:49:48 +1100674 parent = dentry_kill(dentry, 0);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700675 /*
Nick Piggin77812a12011-01-07 17:49:48 +1100676 * If dentry_kill returns NULL, we have nothing more to do.
677 * if it returns the same dentry, trylocks failed. In either
678 * case, just loop again.
679 *
680 * Otherwise, we need to prune ancestors too. This is necessary
681 * to prevent quadratic behavior of shrink_dcache_parent(), but
682 * is also expected to be beneficial in reducing dentry cache
683 * fragmentation.
Miklos Szeredid52b9082007-05-08 00:23:46 -0700684 */
Nick Piggin77812a12011-01-07 17:49:48 +1100685 if (!parent)
686 return;
687 if (parent == dentry)
688 return;
689
690 /* Prune ancestors. */
691 dentry = parent;
Miklos Szeredid52b9082007-05-08 00:23:46 -0700692 while (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100693 spin_lock(&dentry->d_lock);
Nick Piggin89e60542011-01-07 17:49:45 +1100694 if (dentry->d_count > 1) {
695 dentry->d_count--;
696 spin_unlock(&dentry->d_lock);
697 return;
698 }
Nick Piggin77812a12011-01-07 17:49:48 +1100699 dentry = dentry_kill(dentry, 1);
Miklos Szeredid52b9082007-05-08 00:23:46 -0700700 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701}
702
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400703static void shrink_dentry_list(struct list_head *list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700705 struct dentry *dentry;
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700706
Nick Pigginec336792011-01-07 17:49:47 +1100707 rcu_read_lock();
708 for (;;) {
Nick Pigginec336792011-01-07 17:49:47 +1100709 dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
710 if (&dentry->d_lru == list)
711 break; /* empty */
712 spin_lock(&dentry->d_lock);
713 if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
714 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100715 continue;
716 }
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 /*
719 * We found an inuse dentry which was not removed from
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700720 * the LRU because of laziness during lookup. Do not free
721 * it - just keep it off the LRU list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100723 if (dentry->d_count) {
Nick Pigginec336792011-01-07 17:49:47 +1100724 dentry_lru_del(dentry);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700725 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 continue;
727 }
Nick Pigginec336792011-01-07 17:49:47 +1100728
Nick Pigginec336792011-01-07 17:49:47 +1100729 rcu_read_unlock();
Nick Piggin77812a12011-01-07 17:49:48 +1100730
731 try_prune_one_dentry(dentry);
732
Nick Pigginec336792011-01-07 17:49:47 +1100733 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 }
Nick Pigginec336792011-01-07 17:49:47 +1100735 rcu_read_unlock();
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400736}
737
738/**
739 * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
740 * @sb: superblock to shrink dentry LRU.
741 * @count: number of entries to prune
742 * @flags: flags to control the dentry processing
743 *
744 * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
745 */
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000746static void __shrink_dcache_sb(struct super_block *sb, int count, int flags)
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400747{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400748 struct dentry *dentry;
749 LIST_HEAD(referenced);
750 LIST_HEAD(tmp);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400751
Nick Piggin23044502011-01-07 17:49:31 +1100752relock:
753 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400754 while (!list_empty(&sb->s_dentry_lru)) {
755 dentry = list_entry(sb->s_dentry_lru.prev,
756 struct dentry, d_lru);
757 BUG_ON(dentry->d_sb != sb);
758
Nick Piggin23044502011-01-07 17:49:31 +1100759 if (!spin_trylock(&dentry->d_lock)) {
760 spin_unlock(&dcache_lru_lock);
761 cpu_relax();
762 goto relock;
763 }
764
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400765 /*
766 * If we are honouring the DCACHE_REFERENCED flag and the
767 * dentry has this flag set, don't free it. Clear the flag
768 * and put it back on the LRU.
769 */
Nick Piggin23044502011-01-07 17:49:31 +1100770 if (flags & DCACHE_REFERENCED &&
771 dentry->d_flags & DCACHE_REFERENCED) {
772 dentry->d_flags &= ~DCACHE_REFERENCED;
773 list_move(&dentry->d_lru, &referenced);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400774 spin_unlock(&dentry->d_lock);
Nick Piggin23044502011-01-07 17:49:31 +1100775 } else {
776 list_move_tail(&dentry->d_lru, &tmp);
777 spin_unlock(&dentry->d_lock);
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000778 if (!--count)
Nick Piggin23044502011-01-07 17:49:31 +1100779 break;
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400780 }
Nick Pigginec336792011-01-07 17:49:47 +1100781 cond_resched_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400782 }
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700783 if (!list_empty(&referenced))
784 list_splice(&referenced, &sb->s_dentry_lru);
Nick Piggin23044502011-01-07 17:49:31 +1100785 spin_unlock(&dcache_lru_lock);
Nick Pigginec336792011-01-07 17:49:47 +1100786
787 shrink_dentry_list(&tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788}
789
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700790/**
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000791 * prune_dcache_sb - shrink the dcache
792 * @nr_to_scan: number of entries to try to free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 *
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000794 * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
795 * done when we need more memory an called from the superblock shrinker
796 * function.
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700797 *
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000798 * This function may fail to free any resources if all the dentries are in
799 * use.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 */
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000801void prune_dcache_sb(struct super_block *sb, int nr_to_scan)
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700802{
Dave Chinnerb0d40c92011-07-08 14:14:42 +1000803 __shrink_dcache_sb(sb, nr_to_scan, DCACHE_REFERENCED);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -0700804}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805
806/**
807 * shrink_dcache_sb - shrink dcache for a superblock
808 * @sb: superblock
809 *
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400810 * Shrink the dcache for the specified super block. This is used to free
811 * the dcache before unmounting a file system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 */
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400813void shrink_dcache_sb(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814{
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400815 LIST_HEAD(tmp);
816
Nick Piggin23044502011-01-07 17:49:31 +1100817 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400818 while (!list_empty(&sb->s_dentry_lru)) {
819 list_splice_init(&sb->s_dentry_lru, &tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100820 spin_unlock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400821 shrink_dentry_list(&tmp);
Nick Pigginec336792011-01-07 17:49:47 +1100822 spin_lock(&dcache_lru_lock);
Christoph Hellwig3049cfe2010-10-10 05:36:25 -0400823 }
Nick Piggin23044502011-01-07 17:49:31 +1100824 spin_unlock(&dcache_lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -0700826EXPORT_SYMBOL(shrink_dcache_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827
828/*
David Howellsc636ebd2006-10-11 01:22:19 -0700829 * destroy a single subtree of dentries for unmount
830 * - see the comments on shrink_dcache_for_umount() for a description of the
831 * locking
832 */
833static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
834{
835 struct dentry *parent;
David Howellsf8713572006-10-28 10:38:46 -0700836 unsigned detached = 0;
David Howellsc636ebd2006-10-11 01:22:19 -0700837
838 BUG_ON(!IS_ROOT(dentry));
839
840 /* detach this root from the system */
Nick Piggin23044502011-01-07 17:49:31 +1100841 spin_lock(&dentry->d_lock);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400842 dentry_lru_del(dentry);
David Howellsc636ebd2006-10-11 01:22:19 -0700843 __d_drop(dentry);
Nick Pigginda502952011-01-07 17:49:33 +1100844 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700845
846 for (;;) {
847 /* descend to the first leaf in the current subtree */
848 while (!list_empty(&dentry->d_subdirs)) {
849 struct dentry *loop;
850
851 /* this is a branch with children - detach all of them
852 * from the system in one go */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100853 spin_lock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700854 list_for_each_entry(loop, &dentry->d_subdirs,
855 d_u.d_child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100856 spin_lock_nested(&loop->d_lock,
857 DENTRY_D_LOCK_NESTED);
Christoph Hellwiga4633352010-10-10 05:36:26 -0400858 dentry_lru_del(loop);
David Howellsc636ebd2006-10-11 01:22:19 -0700859 __d_drop(loop);
Nick Pigginda502952011-01-07 17:49:33 +1100860 spin_unlock(&loop->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700861 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100862 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700863
864 /* move to the first child */
865 dentry = list_entry(dentry->d_subdirs.next,
866 struct dentry, d_u.d_child);
867 }
868
869 /* consume the dentries from this leaf up through its parents
870 * until we find one with children or run out altogether */
871 do {
872 struct inode *inode;
873
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100874 if (dentry->d_count != 0) {
David Howellsc636ebd2006-10-11 01:22:19 -0700875 printk(KERN_ERR
876 "BUG: Dentry %p{i=%lx,n=%s}"
877 " still in use (%d)"
878 " [unmount of %s %s]\n",
879 dentry,
880 dentry->d_inode ?
881 dentry->d_inode->i_ino : 0UL,
882 dentry->d_name.name,
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100883 dentry->d_count,
David Howellsc636ebd2006-10-11 01:22:19 -0700884 dentry->d_sb->s_type->name,
885 dentry->d_sb->s_id);
886 BUG();
887 }
888
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100889 if (IS_ROOT(dentry)) {
David Howellsc636ebd2006-10-11 01:22:19 -0700890 parent = NULL;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100891 list_del(&dentry->d_u.d_child);
892 } else {
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900893 parent = dentry->d_parent;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100894 spin_lock(&parent->d_lock);
895 parent->d_count--;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100896 list_del(&dentry->d_u.d_child);
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100897 spin_unlock(&parent->d_lock);
OGAWA Hirofumi871c0062008-10-16 07:50:27 +0900898 }
David Howellsc636ebd2006-10-11 01:22:19 -0700899
David Howellsf8713572006-10-28 10:38:46 -0700900 detached++;
David Howellsc636ebd2006-10-11 01:22:19 -0700901
902 inode = dentry->d_inode;
903 if (inode) {
904 dentry->d_inode = NULL;
905 list_del_init(&dentry->d_alias);
906 if (dentry->d_op && dentry->d_op->d_iput)
907 dentry->d_op->d_iput(dentry, inode);
908 else
909 iput(inode);
910 }
911
912 d_free(dentry);
913
914 /* finished when we fall off the top of the tree,
915 * otherwise we ascend to the parent and move to the
916 * next sibling if there is one */
917 if (!parent)
Christoph Hellwig312d3ca2010-10-10 05:36:23 -0400918 return;
David Howellsc636ebd2006-10-11 01:22:19 -0700919 dentry = parent;
David Howellsc636ebd2006-10-11 01:22:19 -0700920 } while (list_empty(&dentry->d_subdirs));
921
922 dentry = list_entry(dentry->d_subdirs.next,
923 struct dentry, d_u.d_child);
924 }
925}
926
927/*
928 * destroy the dentries attached to a superblock on unmounting
Nick Pigginb5c84bf2011-01-07 17:49:38 +1100929 * - we don't need to use dentry->d_lock because:
David Howellsc636ebd2006-10-11 01:22:19 -0700930 * - the superblock is detached from all mountings and open files, so the
931 * dentry trees will not be rearranged by the VFS
932 * - s_umount is write-locked, so the memory pressure shrinker will ignore
933 * any dentries belonging to this superblock that it comes across
934 * - the filesystem itself is no longer permitted to rearrange the dentries
935 * in this superblock
936 */
937void shrink_dcache_for_umount(struct super_block *sb)
938{
939 struct dentry *dentry;
940
941 if (down_read_trylock(&sb->s_umount))
942 BUG();
943
944 dentry = sb->s_root;
945 sb->s_root = NULL;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100946 spin_lock(&dentry->d_lock);
947 dentry->d_count--;
948 spin_unlock(&dentry->d_lock);
David Howellsc636ebd2006-10-11 01:22:19 -0700949 shrink_dcache_for_umount_subtree(dentry);
950
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100951 while (!hlist_bl_empty(&sb->s_anon)) {
952 dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
David Howellsc636ebd2006-10-11 01:22:19 -0700953 shrink_dcache_for_umount_subtree(dentry);
954 }
955}
956
957/*
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700958 * This tries to ascend one level of parenthood, but
959 * we can race with renaming, so we need to re-check
960 * the parenthood after dropping the lock and check
961 * that the sequence number still matches.
962 */
963static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
964{
965 struct dentry *new = old->d_parent;
966
967 rcu_read_lock();
968 spin_unlock(&old->d_lock);
969 spin_lock(&new->d_lock);
970
971 /*
972 * might go back up the wrong parent if we have had a rename
973 * or deletion
974 */
975 if (new != old->d_parent ||
Trond Myklebustc83ce982011-03-15 13:36:43 -0400976 (old->d_flags & DCACHE_DISCONNECTED) ||
Linus Torvaldsc826cb72011-03-15 15:29:21 -0700977 (!locked && read_seqretry(&rename_lock, seq))) {
978 spin_unlock(&new->d_lock);
979 new = NULL;
980 }
981 rcu_read_unlock();
982 return new;
983}
984
985
986/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 * Search for at least 1 mount point in the dentry's subdirs.
988 * We descend to the next level whenever the d_subdirs
989 * list is non-empty and continue searching.
990 */
991
992/**
993 * have_submounts - check for mounts over a dentry
994 * @parent: dentry to check.
995 *
996 * Return true if the parent or its subdirectories contain
997 * a mount point
998 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999int have_submounts(struct dentry *parent)
1000{
Nick Piggin949854d2011-01-07 17:49:37 +11001001 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001003 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11001004 int locked = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11001005
Nick Piggin949854d2011-01-07 17:49:37 +11001006 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001007again:
1008 this_parent = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 if (d_mountpoint(parent))
1011 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001012 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013repeat:
1014 next = this_parent->d_subdirs.next;
1015resume:
1016 while (next != &this_parent->d_subdirs) {
1017 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001018 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 next = tmp->next;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001020
1021 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 /* Have we found a mount point ? */
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001023 if (d_mountpoint(dentry)) {
1024 spin_unlock(&dentry->d_lock);
1025 spin_unlock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 goto positive;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001027 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001029 spin_unlock(&this_parent->d_lock);
1030 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001032 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 goto repeat;
1034 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001035 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 }
1037 /*
1038 * All done at this level ... ascend and resume the search.
1039 */
1040 if (this_parent != parent) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07001041 struct dentry *child = this_parent;
1042 this_parent = try_to_ascend(this_parent, locked, seq);
1043 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11001044 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11001045 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046 goto resume;
1047 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001048 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001049 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001050 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001051 if (locked)
1052 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053 return 0; /* No mount points found in tree */
1054positive:
Nick Piggin58db63d2011-01-07 17:49:39 +11001055 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11001056 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11001057 if (locked)
1058 write_sequnlock(&rename_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 return 1;
Nick Piggin58db63d2011-01-07 17:49:39 +11001060
1061rename_retry:
1062 locked = 1;
1063 write_seqlock(&rename_lock);
1064 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001066EXPORT_SYMBOL(have_submounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067
1068/*
1069 * Search the dentry child list for the specified parent,
1070 * and move any unused dentries to the end of the unused
1071 * list for prune_dcache(). We descend to the next level
1072 * whenever the d_subdirs list is non-empty and continue
1073 * searching.
1074 *
1075 * It returns zero iff there are no unused children,
1076 * otherwise it returns the number of children moved to
1077 * the end of the unused list. This may not be the total
1078 * number of unused children, because select_parent can
1079 * drop the lock and return early due to latency
1080 * constraints.
1081 */
1082static int select_parent(struct dentry * parent)
1083{
Nick Piggin949854d2011-01-07 17:49:37 +11001084 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11001086 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 int found = 0;
Nick Piggin58db63d2011-01-07 17:49:39 +11001088 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089
Nick Piggin949854d2011-01-07 17:49:37 +11001090 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11001091again:
1092 this_parent = parent;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001093 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094repeat:
1095 next = this_parent->d_subdirs.next;
1096resume:
1097 while (next != &this_parent->d_subdirs) {
1098 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08001099 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100 next = tmp->next;
1101
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001102 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggin23044502011-01-07 17:49:31 +11001103
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 /*
1105 * move only zero ref count dentries to the end
1106 * of the unused list for prune_dcache
1107 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001108 if (!dentry->d_count) {
Christoph Hellwiga4633352010-10-10 05:36:26 -04001109 dentry_lru_move_tail(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 found++;
Christoph Hellwiga4633352010-10-10 05:36:26 -04001111 } else {
1112 dentry_lru_del(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 }
1114
1115 /*
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 */
1171
1172void shrink_dcache_parent(struct dentry * parent)
1173{
Kentaro Makitada3bbdd2008-07-23 21:27:13 -07001174 struct super_block *sb = parent->d_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 int found;
1176
1177 while ((found = select_parent(parent)) != 0)
Dave Chinnerb0d40c92011-07-08 14:14:42 +10001178 __shrink_dcache_sb(sb, found, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001180EXPORT_SYMBOL(shrink_dcache_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182/**
Al Viroa4464db2011-07-07 15:03:58 -04001183 * __d_alloc - allocate a dcache entry
1184 * @sb: filesystem it will belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185 * @name: qstr of the name
1186 *
1187 * Allocates a dentry. It returns %NULL if there is insufficient memory
1188 * available. On a success the dentry is returned. The name passed in is
1189 * copied and the copy passed in may be reused after this call.
1190 */
1191
Al Viroa4464db2011-07-07 15:03:58 -04001192struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193{
1194 struct dentry *dentry;
1195 char *dname;
1196
Mel Gormane12ba742007-10-16 01:25:52 -07001197 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 if (!dentry)
1199 return NULL;
1200
1201 if (name->len > DNAME_INLINE_LEN-1) {
1202 dname = kmalloc(name->len + 1, GFP_KERNEL);
1203 if (!dname) {
1204 kmem_cache_free(dentry_cache, dentry);
1205 return NULL;
1206 }
1207 } else {
1208 dname = dentry->d_iname;
1209 }
1210 dentry->d_name.name = dname;
1211
1212 dentry->d_name.len = name->len;
1213 dentry->d_name.hash = name->hash;
1214 memcpy(dname, name->name, name->len);
1215 dname[name->len] = 0;
1216
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001217 dentry->d_count = 1;
Linus Torvaldsdea36672011-04-24 07:58:46 -07001218 dentry->d_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 spin_lock_init(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11001220 seqcount_init(&dentry->d_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 dentry->d_inode = NULL;
Al Viroa4464db2011-07-07 15:03:58 -04001222 dentry->d_parent = dentry;
1223 dentry->d_sb = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224 dentry->d_op = NULL;
1225 dentry->d_fsdata = NULL;
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001226 INIT_HLIST_BL_NODE(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 INIT_LIST_HEAD(&dentry->d_lru);
1228 INIT_LIST_HEAD(&dentry->d_subdirs);
1229 INIT_LIST_HEAD(&dentry->d_alias);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001230 INIT_LIST_HEAD(&dentry->d_u.d_child);
Al Viroa4464db2011-07-07 15:03:58 -04001231 d_set_d_op(dentry, dentry->d_sb->s_d_op);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232
Nick Piggin3e880fb2011-01-07 17:49:19 +11001233 this_cpu_inc(nr_dentry);
Christoph Hellwig312d3ca2010-10-10 05:36:23 -04001234
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 return dentry;
1236}
Al Viroa4464db2011-07-07 15:03:58 -04001237
1238/**
1239 * d_alloc - allocate a dcache entry
1240 * @parent: parent of entry to allocate
1241 * @name: qstr of the name
1242 *
1243 * Allocates a dentry. It returns %NULL if there is insufficient memory
1244 * available. On a success the dentry is returned. The name passed in is
1245 * copied and the copy passed in may be reused after this call.
1246 */
1247struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1248{
1249 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1250 if (!dentry)
1251 return NULL;
1252
1253 spin_lock(&parent->d_lock);
1254 /*
1255 * don't need child lock because it is not subject
1256 * to concurrency here
1257 */
1258 __dget_dlock(parent);
1259 dentry->d_parent = parent;
1260 list_add(&dentry->d_u.d_child, &parent->d_subdirs);
1261 spin_unlock(&parent->d_lock);
1262
1263 return dentry;
1264}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001265EXPORT_SYMBOL(d_alloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266
Nick Piggin4b936882011-01-07 17:50:07 +11001267struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1268{
Al Viroa4464db2011-07-07 15:03:58 -04001269 struct dentry *dentry = __d_alloc(sb, name);
1270 if (dentry)
Nick Piggin4b936882011-01-07 17:50:07 +11001271 dentry->d_flags |= DCACHE_DISCONNECTED;
Nick Piggin4b936882011-01-07 17:50:07 +11001272 return dentry;
1273}
1274EXPORT_SYMBOL(d_alloc_pseudo);
1275
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1277{
1278 struct qstr q;
1279
1280 q.name = name;
1281 q.len = strlen(name);
1282 q.hash = full_name_hash(q.name, q.len);
1283 return d_alloc(parent, &q);
1284}
H Hartley Sweetenef26ca92009-09-29 20:09:42 -04001285EXPORT_SYMBOL(d_alloc_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286
Nick Pigginfb045ad2011-01-07 17:49:55 +11001287void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1288{
Linus Torvalds6f7f7ca2011-01-14 13:26:18 -08001289 WARN_ON_ONCE(dentry->d_op);
1290 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
Nick Pigginfb045ad2011-01-07 17:49:55 +11001291 DCACHE_OP_COMPARE |
1292 DCACHE_OP_REVALIDATE |
1293 DCACHE_OP_DELETE ));
1294 dentry->d_op = op;
1295 if (!op)
1296 return;
1297 if (op->d_hash)
1298 dentry->d_flags |= DCACHE_OP_HASH;
1299 if (op->d_compare)
1300 dentry->d_flags |= DCACHE_OP_COMPARE;
1301 if (op->d_revalidate)
1302 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1303 if (op->d_delete)
1304 dentry->d_flags |= DCACHE_OP_DELETE;
1305
1306}
1307EXPORT_SYMBOL(d_set_d_op);
1308
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001309static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1310{
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001311 spin_lock(&dentry->d_lock);
David Howells9875cf82011-01-14 18:45:21 +00001312 if (inode) {
1313 if (unlikely(IS_AUTOMOUNT(inode)))
1314 dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001315 list_add(&dentry->d_alias, &inode->i_dentry);
David Howells9875cf82011-01-14 18:45:21 +00001316 }
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001317 dentry->d_inode = inode;
Nick Piggin31e6b012011-01-07 17:49:52 +11001318 dentry_rcuwalk_barrier(dentry);
Nick Pigginb23fb0a2011-01-07 17:49:35 +11001319 spin_unlock(&dentry->d_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001320 fsnotify_d_instantiate(dentry, inode);
1321}
1322
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323/**
1324 * d_instantiate - fill in inode information for a dentry
1325 * @entry: dentry to complete
1326 * @inode: inode to attach to this dentry
1327 *
1328 * Fill in inode information in the entry.
1329 *
1330 * This turns negative dentries into productive full members
1331 * of society.
1332 *
1333 * NOTE! This assumes that the inode count has been incremented
1334 * (or otherwise set) by the caller to indicate that it is now
1335 * in use by the dcache.
1336 */
1337
1338void d_instantiate(struct dentry *entry, struct inode * inode)
1339{
Eric Sesterhenn28133c72006-03-26 18:25:39 +02001340 BUG_ON(!list_empty(&entry->d_alias));
Nick Piggin873feea2011-01-07 17:50:06 +11001341 if (inode)
1342 spin_lock(&inode->i_lock);
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001343 __d_instantiate(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001344 if (inode)
1345 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 security_d_instantiate(entry, inode);
1347}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001348EXPORT_SYMBOL(d_instantiate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349
1350/**
1351 * d_instantiate_unique - instantiate a non-aliased dentry
1352 * @entry: dentry to instantiate
1353 * @inode: inode to attach to this dentry
1354 *
1355 * Fill in inode information in the entry. On success, it returns NULL.
1356 * If an unhashed alias of "entry" already exists, then we return the
Oleg Drokine866cfa2006-01-09 20:52:51 -08001357 * aliased dentry instead and drop one reference to inode.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 *
1359 * Note that in order to avoid conflicts with rename() etc, the caller
1360 * had better be holding the parent directory semaphore.
Oleg Drokine866cfa2006-01-09 20:52:51 -08001361 *
1362 * This also assumes that the inode count has been incremented
1363 * (or otherwise set) by the caller to indicate that it is now
1364 * in use by the dcache.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 */
David Howells770bfad2006-08-22 20:06:07 -04001366static struct dentry *__d_instantiate_unique(struct dentry *entry,
1367 struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368{
1369 struct dentry *alias;
1370 int len = entry->d_name.len;
1371 const char *name = entry->d_name.name;
1372 unsigned int hash = entry->d_name.hash;
1373
David Howells770bfad2006-08-22 20:06:07 -04001374 if (!inode) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001375 __d_instantiate(entry, NULL);
David Howells770bfad2006-08-22 20:06:07 -04001376 return NULL;
1377 }
1378
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 list_for_each_entry(alias, &inode->i_dentry, d_alias) {
1380 struct qstr *qstr = &alias->d_name;
1381
Nick Piggin9abca362011-01-07 17:49:36 +11001382 /*
1383 * Don't need alias->d_lock here, because aliases with
1384 * d_parent == entry->d_parent are not subject to name or
1385 * parent changes, because the parent inode i_mutex is held.
1386 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 if (qstr->hash != hash)
1388 continue;
1389 if (alias->d_parent != entry->d_parent)
1390 continue;
Nick Piggin9d55c362011-01-07 17:50:09 +11001391 if (dentry_cmp(qstr->name, qstr->len, name, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 continue;
Nick Piggindc0474b2011-01-07 17:49:43 +11001393 __dget(alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 return alias;
1395 }
David Howells770bfad2006-08-22 20:06:07 -04001396
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001397 __d_instantiate(entry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 return NULL;
1399}
David Howells770bfad2006-08-22 20:06:07 -04001400
1401struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
1402{
1403 struct dentry *result;
1404
1405 BUG_ON(!list_empty(&entry->d_alias));
1406
Nick Piggin873feea2011-01-07 17:50:06 +11001407 if (inode)
1408 spin_lock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001409 result = __d_instantiate_unique(entry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001410 if (inode)
1411 spin_unlock(&inode->i_lock);
David Howells770bfad2006-08-22 20:06:07 -04001412
1413 if (!result) {
1414 security_d_instantiate(entry, inode);
1415 return NULL;
1416 }
1417
1418 BUG_ON(!d_unhashed(result));
1419 iput(inode);
1420 return result;
1421}
1422
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423EXPORT_SYMBOL(d_instantiate_unique);
1424
1425/**
1426 * d_alloc_root - allocate root dentry
1427 * @root_inode: inode to allocate the root for
1428 *
1429 * Allocate a root ("/") dentry for the inode given. The inode is
1430 * instantiated and returned. %NULL is returned if there is insufficient
1431 * memory or the inode passed is %NULL.
1432 */
1433
1434struct dentry * d_alloc_root(struct inode * root_inode)
1435{
1436 struct dentry *res = NULL;
1437
1438 if (root_inode) {
1439 static const struct qstr name = { .name = "/", .len = 1 };
1440
Al Viroa4464db2011-07-07 15:03:58 -04001441 res = __d_alloc(root_inode->i_sb, &name);
1442 if (res)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 d_instantiate(res, root_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444 }
1445 return res;
1446}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001447EXPORT_SYMBOL(d_alloc_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001449static struct dentry * __d_find_any_alias(struct inode *inode)
1450{
1451 struct dentry *alias;
1452
1453 if (list_empty(&inode->i_dentry))
1454 return NULL;
1455 alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias);
1456 __dget(alias);
1457 return alias;
1458}
1459
1460static struct dentry * d_find_any_alias(struct inode *inode)
1461{
1462 struct dentry *de;
1463
1464 spin_lock(&inode->i_lock);
1465 de = __d_find_any_alias(inode);
1466 spin_unlock(&inode->i_lock);
1467 return de;
1468}
1469
1470
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471/**
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001472 * d_obtain_alias - find or allocate a dentry for a given inode
1473 * @inode: inode to allocate the dentry for
1474 *
1475 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1476 * similar open by handle operations. The returned dentry may be anonymous,
1477 * or may have a full name (if the inode was already in the cache).
1478 *
1479 * When called on a directory inode, we must ensure that the inode only ever
1480 * has one dentry. If a dentry is found, that is returned instead of
1481 * allocating a new one.
1482 *
1483 * On successful return, the reference to the inode has been transferred
Christoph Hellwig44003722008-08-11 15:49:04 +02001484 * to the dentry. In case of an error the reference on the inode is released.
1485 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1486 * be passed in and will be the error will be propagate to the return value,
1487 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001488 */
1489struct dentry *d_obtain_alias(struct inode *inode)
1490{
Christoph Hellwig9308a612008-08-11 15:49:12 +02001491 static const struct qstr anonstring = { .name = "" };
1492 struct dentry *tmp;
1493 struct dentry *res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001494
1495 if (!inode)
Christoph Hellwig44003722008-08-11 15:49:04 +02001496 return ERR_PTR(-ESTALE);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001497 if (IS_ERR(inode))
1498 return ERR_CAST(inode);
1499
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001500 res = d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001501 if (res)
1502 goto out_iput;
1503
Al Viroa4464db2011-07-07 15:03:58 -04001504 tmp = __d_alloc(inode->i_sb, &anonstring);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001505 if (!tmp) {
1506 res = ERR_PTR(-ENOMEM);
1507 goto out_iput;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001508 }
Nick Pigginb5c84bf2011-01-07 17:49:38 +11001509
Nick Piggin873feea2011-01-07 17:50:06 +11001510 spin_lock(&inode->i_lock);
J. Bruce Fieldsd891eed2011-01-18 15:45:09 -05001511 res = __d_find_any_alias(inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001512 if (res) {
Nick Piggin873feea2011-01-07 17:50:06 +11001513 spin_unlock(&inode->i_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001514 dput(tmp);
1515 goto out_iput;
1516 }
1517
1518 /* attach a disconnected dentry */
1519 spin_lock(&tmp->d_lock);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001520 tmp->d_inode = inode;
1521 tmp->d_flags |= DCACHE_DISCONNECTED;
Christoph Hellwig9308a612008-08-11 15:49:12 +02001522 list_add(&tmp->d_alias, &inode->i_dentry);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001523 hlist_bl_lock(&tmp->d_sb->s_anon);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001524 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04001525 hlist_bl_unlock(&tmp->d_sb->s_anon);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001526 spin_unlock(&tmp->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001527 spin_unlock(&inode->i_lock);
Josef Bacik24ff6662010-11-18 20:52:55 -05001528 security_d_instantiate(tmp, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001529
Christoph Hellwig9308a612008-08-11 15:49:12 +02001530 return tmp;
1531
1532 out_iput:
Josef Bacik24ff6662010-11-18 20:52:55 -05001533 if (res && !IS_ERR(res))
1534 security_d_instantiate(res, inode);
Christoph Hellwig9308a612008-08-11 15:49:12 +02001535 iput(inode);
1536 return res;
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +02001537}
Benny Halevyadc48722009-02-27 14:02:59 -08001538EXPORT_SYMBOL(d_obtain_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539
1540/**
1541 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1542 * @inode: the inode which may have a disconnected dentry
1543 * @dentry: a negative dentry which we want to point to the inode.
1544 *
1545 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1546 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1547 * and return it, else simply d_add the inode to the dentry and return NULL.
1548 *
1549 * This is needed in the lookup routine of any filesystem that is exportable
1550 * (via knfsd) so that we can build dcache paths to directories effectively.
1551 *
1552 * If a dentry was found and moved, then it is returned. Otherwise NULL
1553 * is returned. This matches the expected return value of ->lookup.
1554 *
1555 */
1556struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
1557{
1558 struct dentry *new = NULL;
1559
Al Viroa9049372011-07-08 21:20:11 -04001560 if (IS_ERR(inode))
1561 return ERR_CAST(inode);
1562
NeilBrown21c0d8f2006-10-04 02:16:16 -07001563 if (inode && S_ISDIR(inode->i_mode)) {
Nick Piggin873feea2011-01-07 17:50:06 +11001564 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 new = __d_find_alias(inode, 1);
1566 if (new) {
1567 BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
Nick Piggin873feea2011-01-07 17:50:06 +11001568 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569 security_d_instantiate(new, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 d_move(new, dentry);
1571 iput(inode);
1572 } else {
Nick Piggin873feea2011-01-07 17:50:06 +11001573 /* already taking inode->i_lock, so d_add() by hand */
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001574 __d_instantiate(dentry, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001575 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576 security_d_instantiate(dentry, inode);
1577 d_rehash(dentry);
1578 }
1579 } else
1580 d_add(dentry, inode);
1581 return new;
1582}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001583EXPORT_SYMBOL(d_splice_alias);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584
Barry Naujok94035402008-05-21 16:50:46 +10001585/**
1586 * d_add_ci - lookup or allocate new dentry with case-exact name
1587 * @inode: the inode case-insensitive lookup has found
1588 * @dentry: the negative dentry that was passed to the parent's lookup func
1589 * @name: the case-exact name to be associated with the returned dentry
1590 *
1591 * This is to avoid filling the dcache with case-insensitive names to the
1592 * same inode, only the actual correct case is stored in the dcache for
1593 * case-insensitive filesystems.
1594 *
1595 * For a case-insensitive lookup match and if the the case-exact dentry
1596 * already exists in in the dcache, use it and return it.
1597 *
1598 * If no entry exists with the exact case name, allocate new dentry with
1599 * the exact case, and return the spliced entry.
1600 */
Christoph Hellwige45b5902008-08-07 23:49:07 +02001601struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
Barry Naujok94035402008-05-21 16:50:46 +10001602 struct qstr *name)
1603{
1604 int error;
1605 struct dentry *found;
1606 struct dentry *new;
1607
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001608 /*
1609 * First check if a dentry matching the name already exists,
1610 * if not go ahead and create it now.
1611 */
Barry Naujok94035402008-05-21 16:50:46 +10001612 found = d_hash_and_lookup(dentry->d_parent, name);
Barry Naujok94035402008-05-21 16:50:46 +10001613 if (!found) {
1614 new = d_alloc(dentry->d_parent, name);
1615 if (!new) {
1616 error = -ENOMEM;
1617 goto err_out;
1618 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001619
Barry Naujok94035402008-05-21 16:50:46 +10001620 found = d_splice_alias(inode, new);
1621 if (found) {
1622 dput(new);
1623 return found;
1624 }
1625 return new;
1626 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001627
1628 /*
1629 * If a matching dentry exists, and it's not negative use it.
1630 *
1631 * Decrement the reference count to balance the iget() done
1632 * earlier on.
1633 */
Barry Naujok94035402008-05-21 16:50:46 +10001634 if (found->d_inode) {
1635 if (unlikely(found->d_inode != inode)) {
1636 /* This can't happen because bad inodes are unhashed. */
1637 BUG_ON(!is_bad_inode(inode));
1638 BUG_ON(!is_bad_inode(found->d_inode));
1639 }
Barry Naujok94035402008-05-21 16:50:46 +10001640 iput(inode);
1641 return found;
1642 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001643
Barry Naujok94035402008-05-21 16:50:46 +10001644 /*
Josef Bacik44396f42011-05-31 11:58:49 -04001645 * We are going to instantiate this dentry, unhash it and clear the
1646 * lookup flag so we can do that.
1647 */
1648 if (unlikely(d_need_lookup(found)))
1649 d_clear_need_lookup(found);
1650
1651 /*
Barry Naujok94035402008-05-21 16:50:46 +10001652 * Negative dentry: instantiate it unless the inode is a directory and
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001653 * already has a dentry.
Barry Naujok94035402008-05-21 16:50:46 +10001654 */
Nick Piggin873feea2011-01-07 17:50:06 +11001655 spin_lock(&inode->i_lock);
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001656 if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
OGAWA Hirofumi360da902008-10-16 07:50:28 +09001657 __d_instantiate(found, inode);
Nick Piggin873feea2011-01-07 17:50:06 +11001658 spin_unlock(&inode->i_lock);
Barry Naujok94035402008-05-21 16:50:46 +10001659 security_d_instantiate(found, inode);
1660 return found;
1661 }
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001662
Barry Naujok94035402008-05-21 16:50:46 +10001663 /*
Christoph Hellwigb6520c82009-01-05 19:10:37 +01001664 * In case a directory already has a (disconnected) entry grab a
1665 * reference to it, move it in place and use it.
Barry Naujok94035402008-05-21 16:50:46 +10001666 */
1667 new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
Nick Piggindc0474b2011-01-07 17:49:43 +11001668 __dget(new);
Nick Piggin873feea2011-01-07 17:50:06 +11001669 spin_unlock(&inode->i_lock);
Barry Naujok94035402008-05-21 16:50:46 +10001670 security_d_instantiate(found, inode);
Barry Naujok94035402008-05-21 16:50:46 +10001671 d_move(new, found);
Barry Naujok94035402008-05-21 16:50:46 +10001672 iput(inode);
Barry Naujok94035402008-05-21 16:50:46 +10001673 dput(found);
Barry Naujok94035402008-05-21 16:50:46 +10001674 return new;
1675
1676err_out:
1677 iput(inode);
1678 return ERR_PTR(error);
1679}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001680EXPORT_SYMBOL(d_add_ci);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681
1682/**
Nick Piggin31e6b012011-01-07 17:49:52 +11001683 * __d_lookup_rcu - search for a dentry (racy, store-free)
1684 * @parent: parent dentry
1685 * @name: qstr of name we wish to find
1686 * @seq: returns d_seq value at the point where the dentry was found
1687 * @inode: returns dentry->d_inode when the inode was found valid.
1688 * Returns: dentry, or NULL
1689 *
1690 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1691 * resolution (store-free path walking) design described in
1692 * Documentation/filesystems/path-lookup.txt.
1693 *
1694 * This is not to be used outside core vfs.
1695 *
1696 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1697 * held, and rcu_read_lock held. The returned dentry must not be stored into
1698 * without taking d_lock and checking d_seq sequence count against @seq
1699 * returned here.
1700 *
1701 * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
1702 * function.
1703 *
1704 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1705 * the returned dentry, so long as its parent's seqlock is checked after the
1706 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1707 * is formed, giving integrity down the path walk.
1708 */
1709struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
1710 unsigned *seq, struct inode **inode)
1711{
1712 unsigned int len = name->len;
1713 unsigned int hash = name->hash;
1714 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001715 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001716 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001717 struct dentry *dentry;
1718
1719 /*
1720 * Note: There is significant duplication with __d_lookup_rcu which is
1721 * required to prevent single threaded performance regressions
1722 * especially on architectures where smp_rmb (in seqcounts) are costly.
1723 * Keep the two functions in sync.
1724 */
1725
1726 /*
1727 * The hash list is protected using RCU.
1728 *
1729 * Carefully use d_seq when comparing a candidate dentry, to avoid
1730 * races with d_move().
1731 *
1732 * It is possible that concurrent renames can mess up our list
1733 * walk here and result in missing our dentry, resulting in the
1734 * false-negative result. d_lookup() protects against concurrent
1735 * renames using rename_lock seqlock.
1736 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001737 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Piggin31e6b012011-01-07 17:49:52 +11001738 */
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001739 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001740 struct inode *i;
1741 const char *tname;
1742 int tlen;
1743
1744 if (dentry->d_name.hash != hash)
1745 continue;
1746
1747seqretry:
1748 *seq = read_seqcount_begin(&dentry->d_seq);
1749 if (dentry->d_parent != parent)
1750 continue;
1751 if (d_unhashed(dentry))
1752 continue;
1753 tlen = dentry->d_name.len;
1754 tname = dentry->d_name.name;
1755 i = dentry->d_inode;
Nick Piggine1bb5782011-01-07 17:50:08 +11001756 prefetch(tname);
1757 if (i)
1758 prefetch(i);
Nick Piggin31e6b012011-01-07 17:49:52 +11001759 /*
1760 * This seqcount check is required to ensure name and
1761 * len are loaded atomically, so as not to walk off the
1762 * edge of memory when walking. If we could load this
1763 * atomically some other way, we could drop this check.
1764 */
1765 if (read_seqcount_retry(&dentry->d_seq, *seq))
1766 goto seqretry;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001767 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001768 if (parent->d_op->d_compare(parent, *inode,
1769 dentry, i,
1770 tlen, tname, name))
1771 continue;
1772 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001773 if (dentry_cmp(tname, tlen, str, len))
Nick Piggin31e6b012011-01-07 17:49:52 +11001774 continue;
1775 }
1776 /*
1777 * No extra seqcount check is required after the name
1778 * compare. The caller must perform a seqcount check in
1779 * order to do anything useful with the returned dentry
1780 * anyway.
1781 */
1782 *inode = i;
1783 return dentry;
1784 }
1785 return NULL;
1786}
1787
1788/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 * d_lookup - search for a dentry
1790 * @parent: parent dentry
1791 * @name: qstr of name we wish to find
Nick Pigginb04f7842010-08-18 04:37:34 +10001792 * Returns: dentry, or NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 *
Nick Pigginb04f7842010-08-18 04:37:34 +10001794 * d_lookup searches the children of the parent dentry for the name in
1795 * question. If the dentry is found its reference count is incremented and the
1796 * dentry is returned. The caller must use dput to free the entry when it has
1797 * finished using it. %NULL is returned if the dentry does not exist.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001799struct dentry *d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800{
Nick Piggin31e6b012011-01-07 17:49:52 +11001801 struct dentry *dentry;
Nick Piggin949854d2011-01-07 17:49:37 +11001802 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803
1804 do {
1805 seq = read_seqbegin(&rename_lock);
1806 dentry = __d_lookup(parent, name);
1807 if (dentry)
1808 break;
1809 } while (read_seqretry(&rename_lock, seq));
1810 return dentry;
1811}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001812EXPORT_SYMBOL(d_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
Nick Piggin31e6b012011-01-07 17:49:52 +11001814/**
Nick Pigginb04f7842010-08-18 04:37:34 +10001815 * __d_lookup - search for a dentry (racy)
1816 * @parent: parent dentry
1817 * @name: qstr of name we wish to find
1818 * Returns: dentry, or NULL
1819 *
1820 * __d_lookup is like d_lookup, however it may (rarely) return a
1821 * false-negative result due to unrelated rename activity.
1822 *
1823 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1824 * however it must be used carefully, eg. with a following d_lookup in
1825 * the case of failure.
1826 *
1827 * __d_lookup callers must be commented.
1828 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001829struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830{
1831 unsigned int len = name->len;
1832 unsigned int hash = name->hash;
1833 const unsigned char *str = name->name;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001834 struct hlist_bl_head *b = d_hash(parent, hash);
Nick Pigginceb5bdc2011-01-07 17:50:05 +11001835 struct hlist_bl_node *node;
Nick Piggin31e6b012011-01-07 17:49:52 +11001836 struct dentry *found = NULL;
Paul E. McKenney665a7582005-11-07 00:59:17 -08001837 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001838
Nick Pigginb04f7842010-08-18 04:37:34 +10001839 /*
Nick Piggin31e6b012011-01-07 17:49:52 +11001840 * Note: There is significant duplication with __d_lookup_rcu which is
1841 * required to prevent single threaded performance regressions
1842 * especially on architectures where smp_rmb (in seqcounts) are costly.
1843 * Keep the two functions in sync.
1844 */
1845
1846 /*
Nick Pigginb04f7842010-08-18 04:37:34 +10001847 * The hash list is protected using RCU.
1848 *
1849 * Take d_lock when comparing a candidate dentry, to avoid races
1850 * with d_move().
1851 *
1852 * It is possible that concurrent renames can mess up our list
1853 * walk here and result in missing our dentry, resulting in the
1854 * false-negative result. d_lookup() protects against concurrent
1855 * renames using rename_lock seqlock.
1856 *
Namhyung Kimb0a4bb82011-01-22 15:31:32 +09001857 * See Documentation/filesystems/path-lookup.txt for more details.
Nick Pigginb04f7842010-08-18 04:37:34 +10001858 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 rcu_read_lock();
1860
Linus Torvaldsb07ad992011-04-23 22:32:03 -07001861 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
Nick Piggin31e6b012011-01-07 17:49:52 +11001862 const char *tname;
1863 int tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001864
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 if (dentry->d_name.hash != hash)
1866 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867
1868 spin_lock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869 if (dentry->d_parent != parent)
1870 goto next;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001871 if (d_unhashed(dentry))
1872 goto next;
1873
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 /*
1875 * It is safe to compare names since d_move() cannot
1876 * change the qstr (protected by d_lock).
1877 */
Nick Piggin31e6b012011-01-07 17:49:52 +11001878 tlen = dentry->d_name.len;
1879 tname = dentry->d_name.name;
Nick Pigginfb045ad2011-01-07 17:49:55 +11001880 if (parent->d_flags & DCACHE_OP_COMPARE) {
Nick Piggin621e1552011-01-07 17:49:27 +11001881 if (parent->d_op->d_compare(parent, parent->d_inode,
1882 dentry, dentry->d_inode,
Nick Piggin31e6b012011-01-07 17:49:52 +11001883 tlen, tname, name))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884 goto next;
1885 } else {
Nick Piggin9d55c362011-01-07 17:50:09 +11001886 if (dentry_cmp(tname, tlen, str, len))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887 goto next;
1888 }
1889
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001890 dentry->d_count++;
Linus Torvaldsd0185c02008-09-29 07:42:57 -07001891 found = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 spin_unlock(&dentry->d_lock);
1893 break;
1894next:
1895 spin_unlock(&dentry->d_lock);
1896 }
1897 rcu_read_unlock();
1898
1899 return found;
1900}
1901
1902/**
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001903 * d_hash_and_lookup - hash the qstr then search for a dentry
1904 * @dir: Directory to search in
1905 * @name: qstr of name we wish to find
1906 *
1907 * On hash failure or on lookup failure NULL is returned.
1908 */
1909struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
1910{
1911 struct dentry *dentry = NULL;
1912
1913 /*
1914 * Check for a fs-specific hash function. Note that we must
1915 * calculate the standard hash first, as the d_op->d_hash()
1916 * routine may choose to leave the hash value unchanged.
1917 */
1918 name->hash = full_name_hash(name->name, name->len);
Nick Pigginfb045ad2011-01-07 17:49:55 +11001919 if (dir->d_flags & DCACHE_OP_HASH) {
Nick Pigginb1e6a012011-01-07 17:49:28 +11001920 if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08001921 goto out;
1922 }
1923 dentry = d_lookup(dir, name);
1924out:
1925 return dentry;
1926}
1927
1928/**
Nick Piggin786a5e12011-01-07 17:49:16 +11001929 * d_validate - verify dentry provided from insecure source (deprecated)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 * @dentry: The dentry alleged to be valid child of @dparent
Randy Dunlapff5fdb62011-01-22 20:16:06 -08001931 * @dparent: The parent dentry (known to be valid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 *
1933 * An insecure source has sent us a dentry, here we verify it and dget() it.
1934 * This is used by ncpfs in its readdir implementation.
1935 * Zero is returned in the dentry is invalid.
Nick Piggin786a5e12011-01-07 17:49:16 +11001936 *
1937 * This function is slow for big directories, and deprecated, do not use it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 */
Nick Piggind3a23e12011-01-05 20:01:21 +11001939int d_validate(struct dentry *dentry, struct dentry *dparent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940{
Nick Piggin786a5e12011-01-07 17:49:16 +11001941 struct dentry *child;
Nick Piggind3a23e12011-01-05 20:01:21 +11001942
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001943 spin_lock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001944 list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
1945 if (dentry == child) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001946 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Nick Piggindc0474b2011-01-07 17:49:43 +11001947 __dget_dlock(dentry);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001948 spin_unlock(&dentry->d_lock);
1949 spin_unlock(&dparent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001950 return 1;
1951 }
1952 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11001953 spin_unlock(&dparent->d_lock);
Nick Piggin786a5e12011-01-07 17:49:16 +11001954
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 return 0;
1956}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07001957EXPORT_SYMBOL(d_validate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958
1959/*
1960 * When a file is deleted, we have two options:
1961 * - turn this dentry into a negative dentry
1962 * - unhash this dentry and free it.
1963 *
1964 * Usually, we want to just turn this into
1965 * a negative dentry, but if anybody else is
1966 * currently using the dentry or the inode
1967 * we can't do that and we fall back on removing
1968 * it from the hash queues and waiting for
1969 * it to be deleted later when it has no users
1970 */
1971
1972/**
1973 * d_delete - delete a dentry
1974 * @dentry: The dentry to delete
1975 *
1976 * Turn the dentry into a negative dentry if possible, otherwise
1977 * remove it from the hash queues so it can be deleted later
1978 */
1979
1980void d_delete(struct dentry * dentry)
1981{
Nick Piggin873feea2011-01-07 17:50:06 +11001982 struct inode *inode;
John McCutchan7a91bf72005-08-08 13:52:16 -04001983 int isdir = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984 /*
1985 * Are we the only user?
1986 */
Nick Piggin357f8e62011-01-07 17:49:42 +11001987again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988 spin_lock(&dentry->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11001989 inode = dentry->d_inode;
1990 isdir = S_ISDIR(inode->i_mode);
Nick Pigginb7ab39f2011-01-07 17:49:32 +11001991 if (dentry->d_count == 1) {
Nick Piggin873feea2011-01-07 17:50:06 +11001992 if (inode && !spin_trylock(&inode->i_lock)) {
Nick Piggin357f8e62011-01-07 17:49:42 +11001993 spin_unlock(&dentry->d_lock);
1994 cpu_relax();
1995 goto again;
1996 }
Al Viro13e3c5e2010-05-21 16:11:04 -04001997 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
Nick Piggin31e6b012011-01-07 17:49:52 +11001998 dentry_unlink_inode(dentry);
John McCutchan7a91bf72005-08-08 13:52:16 -04001999 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002000 return;
2001 }
2002
2003 if (!d_unhashed(dentry))
2004 __d_drop(dentry);
2005
2006 spin_unlock(&dentry->d_lock);
John McCutchan7a91bf72005-08-08 13:52:16 -04002007
2008 fsnotify_nameremove(dentry, isdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002010EXPORT_SYMBOL(d_delete);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002012static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013{
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002014 BUG_ON(!d_unhashed(entry));
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002015 hlist_bl_lock(b);
Linus Torvaldsdea36672011-04-24 07:58:46 -07002016 entry->d_flags |= DCACHE_RCUACCESS;
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002017 hlist_bl_add_head_rcu(&entry->d_hash, b);
Christoph Hellwig1879fd62011-04-25 14:01:36 -04002018 hlist_bl_unlock(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019}
2020
David Howells770bfad2006-08-22 20:06:07 -04002021static void _d_rehash(struct dentry * entry)
2022{
2023 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2024}
2025
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026/**
2027 * d_rehash - add an entry back to the hash
2028 * @entry: dentry to add to the hash
2029 *
2030 * Adds a dentry to the hash according to its name.
2031 */
2032
2033void d_rehash(struct dentry * entry)
2034{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035 spin_lock(&entry->d_lock);
David Howells770bfad2006-08-22 20:06:07 -04002036 _d_rehash(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037 spin_unlock(&entry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002039EXPORT_SYMBOL(d_rehash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002041/**
2042 * dentry_update_name_case - update case insensitive dentry with a new name
2043 * @dentry: dentry to be updated
2044 * @name: new name
2045 *
2046 * Update a case insensitive dentry with new case of name.
2047 *
2048 * dentry must have been returned by d_lookup with name @name. Old and new
2049 * name lengths must match (ie. no d_compare which allows mismatched name
2050 * lengths).
2051 *
2052 * Parent inode i_mutex must be held over d_lookup and into this call (to
2053 * keep renames and concurrent inserts, and readdir(2) away).
2054 */
2055void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2056{
Linus Torvalds7ebfa572011-04-15 07:34:26 -07002057 BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002058 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2059
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002060 spin_lock(&dentry->d_lock);
Nick Piggin31e6b012011-01-07 17:49:52 +11002061 write_seqcount_begin(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002062 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
Nick Piggin31e6b012011-01-07 17:49:52 +11002063 write_seqcount_end(&dentry->d_seq);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002064 spin_unlock(&dentry->d_lock);
Nick Pigginfb2d5b82011-01-07 17:49:26 +11002065}
2066EXPORT_SYMBOL(dentry_update_name_case);
2067
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068static void switch_names(struct dentry *dentry, struct dentry *target)
2069{
2070 if (dname_external(target)) {
2071 if (dname_external(dentry)) {
2072 /*
2073 * Both external: swap the pointers
2074 */
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002075 swap(target->d_name.name, dentry->d_name.name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076 } else {
2077 /*
2078 * dentry:internal, target:external. Steal target's
2079 * storage and make target internal.
2080 */
J. Bruce Fields321bcf92007-10-21 16:41:38 -07002081 memcpy(target->d_iname, dentry->d_name.name,
2082 dentry->d_name.len + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083 dentry->d_name.name = target->d_name.name;
2084 target->d_name.name = target->d_iname;
2085 }
2086 } else {
2087 if (dname_external(dentry)) {
2088 /*
2089 * dentry:external, target:internal. Give dentry's
2090 * storage to target and make dentry internal
2091 */
2092 memcpy(dentry->d_iname, target->d_name.name,
2093 target->d_name.len + 1);
2094 target->d_name.name = dentry->d_name.name;
2095 dentry->d_name.name = dentry->d_iname;
2096 } else {
2097 /*
2098 * Both are internal. Just copy target to dentry
2099 */
2100 memcpy(dentry->d_iname, target->d_name.name,
2101 target->d_name.len + 1);
Al Virodc711ca2008-11-03 15:03:50 -05002102 dentry->d_name.len = target->d_name.len;
2103 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002104 }
2105 }
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002106 swap(dentry->d_name.len, target->d_name.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107}
2108
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002109static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2110{
2111 /*
2112 * XXXX: do we really need to take target->d_lock?
2113 */
2114 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2115 spin_lock(&target->d_parent->d_lock);
2116 else {
2117 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2118 spin_lock(&dentry->d_parent->d_lock);
2119 spin_lock_nested(&target->d_parent->d_lock,
2120 DENTRY_D_LOCK_NESTED);
2121 } else {
2122 spin_lock(&target->d_parent->d_lock);
2123 spin_lock_nested(&dentry->d_parent->d_lock,
2124 DENTRY_D_LOCK_NESTED);
2125 }
2126 }
2127 if (target < dentry) {
2128 spin_lock_nested(&target->d_lock, 2);
2129 spin_lock_nested(&dentry->d_lock, 3);
2130 } else {
2131 spin_lock_nested(&dentry->d_lock, 2);
2132 spin_lock_nested(&target->d_lock, 3);
2133 }
2134}
2135
2136static void dentry_unlock_parents_for_move(struct dentry *dentry,
2137 struct dentry *target)
2138{
2139 if (target->d_parent != dentry->d_parent)
2140 spin_unlock(&dentry->d_parent->d_lock);
2141 if (target->d_parent != target)
2142 spin_unlock(&target->d_parent->d_lock);
2143}
2144
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145/*
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002146 * When switching names, the actual string doesn't strictly have to
2147 * be preserved in the target - because we're dropping the target
2148 * anyway. As such, we can just do a simple memcpy() to copy over
2149 * the new name before we switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 *
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002151 * Note that we have to be a lot more careful about getting the hash
2152 * switched - we have to switch the hash value properly even if it
2153 * then no longer matches the actual (corrupted) string of the target.
2154 * The hash value has to match the hash queue that the dentry is on..
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002156/*
Al Viro18367502011-07-12 21:42:24 -04002157 * __d_move - move a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 * @dentry: entry to move
2159 * @target: new dentry
2160 *
2161 * Update the dcache to reflect the move of a file name. Negative
Al Viro18367502011-07-12 21:42:24 -04002162 * dcache entries should not be moved in this way. Caller hold
2163 * rename_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 */
Al Viro18367502011-07-12 21:42:24 -04002165static void __d_move(struct dentry * dentry, struct dentry * target)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 if (!dentry->d_inode)
2168 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2169
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002170 BUG_ON(d_ancestor(dentry, target));
2171 BUG_ON(d_ancestor(target, dentry));
2172
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002173 dentry_lock_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174
Nick Piggin31e6b012011-01-07 17:49:52 +11002175 write_seqcount_begin(&dentry->d_seq);
2176 write_seqcount_begin(&target->d_seq);
2177
Nick Pigginceb5bdc2011-01-07 17:50:05 +11002178 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2179
2180 /*
2181 * Move the dentry to the target hash queue. Don't bother checking
2182 * for the same hash queue because of how unlikely it is.
2183 */
2184 __d_drop(dentry);
Nick Piggin789680d2011-01-07 17:49:30 +11002185 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186
2187 /* Unhash the target: dput() will then get rid of it */
2188 __d_drop(target);
2189
Eric Dumazet5160ee62006-01-08 01:03:32 -08002190 list_del(&dentry->d_u.d_child);
2191 list_del(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192
2193 /* Switch the names.. */
2194 switch_names(dentry, target);
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002195 swap(dentry->d_name.hash, target->d_name.hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196
2197 /* ... and switch the parents */
2198 if (IS_ROOT(dentry)) {
2199 dentry->d_parent = target->d_parent;
2200 target->d_parent = target;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002201 INIT_LIST_HEAD(&target->d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202 } else {
Wu Fengguang9a8d5bb2009-01-07 18:09:14 -08002203 swap(dentry->d_parent, target->d_parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204
2205 /* And add them back to the (new) parent lists */
Eric Dumazet5160ee62006-01-08 01:03:32 -08002206 list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 }
2208
Eric Dumazet5160ee62006-01-08 01:03:32 -08002209 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002210
Nick Piggin31e6b012011-01-07 17:49:52 +11002211 write_seqcount_end(&target->d_seq);
2212 write_seqcount_end(&dentry->d_seq);
2213
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002214 dentry_unlock_parents_for_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002215 spin_unlock(&target->d_lock);
Nick Pigginc32ccd82006-03-25 03:07:09 -08002216 fsnotify_d_move(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217 spin_unlock(&dentry->d_lock);
Al Viro18367502011-07-12 21:42:24 -04002218}
2219
2220/*
2221 * d_move - move a dentry
2222 * @dentry: entry to move
2223 * @target: new dentry
2224 *
2225 * Update the dcache to reflect the move of a file name. Negative
2226 * dcache entries should not be moved in this way.
2227 */
2228void d_move(struct dentry *dentry, struct dentry *target)
2229{
2230 write_seqlock(&rename_lock);
2231 __d_move(dentry, target);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002233}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002234EXPORT_SYMBOL(d_move);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002236/**
2237 * d_ancestor - search for an ancestor
2238 * @p1: ancestor dentry
2239 * @p2: child dentry
2240 *
2241 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2242 * an ancestor of p2, else NULL.
Trond Myklebust9eaef272006-10-21 10:24:20 -07002243 */
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002244struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002245{
2246 struct dentry *p;
2247
OGAWA Hirofumi871c0062008-10-16 07:50:27 +09002248 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
Trond Myklebust9eaef272006-10-21 10:24:20 -07002249 if (p->d_parent == p1)
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002250 return p;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002251 }
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002252 return NULL;
Trond Myklebust9eaef272006-10-21 10:24:20 -07002253}
2254
2255/*
2256 * This helper attempts to cope with remotely renamed directories
2257 *
2258 * It assumes that the caller is already holding
Al Viro18367502011-07-12 21:42:24 -04002259 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
Trond Myklebust9eaef272006-10-21 10:24:20 -07002260 *
2261 * Note: If ever the locking in lock_rename() changes, then please
2262 * remember to update this too...
Trond Myklebust9eaef272006-10-21 10:24:20 -07002263 */
Nick Piggin873feea2011-01-07 17:50:06 +11002264static struct dentry *__d_unalias(struct inode *inode,
2265 struct dentry *dentry, struct dentry *alias)
Trond Myklebust9eaef272006-10-21 10:24:20 -07002266{
2267 struct mutex *m1 = NULL, *m2 = NULL;
2268 struct dentry *ret;
2269
2270 /* If alias and dentry share a parent, then no extra locks required */
2271 if (alias->d_parent == dentry->d_parent)
2272 goto out_unalias;
2273
Trond Myklebust9eaef272006-10-21 10:24:20 -07002274 /* See lock_rename() */
2275 ret = ERR_PTR(-EBUSY);
2276 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2277 goto out_err;
2278 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2279 if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
2280 goto out_err;
2281 m2 = &alias->d_parent->d_inode->i_mutex;
2282out_unalias:
Al Viro18367502011-07-12 21:42:24 -04002283 __d_move(alias, dentry);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002284 ret = alias;
2285out_err:
Nick Piggin873feea2011-01-07 17:50:06 +11002286 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002287 if (m2)
2288 mutex_unlock(m2);
2289 if (m1)
2290 mutex_unlock(m1);
2291 return ret;
2292}
2293
2294/*
David Howells770bfad2006-08-22 20:06:07 -04002295 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2296 * named dentry in place of the dentry to be replaced.
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002297 * returns with anon->d_lock held!
David Howells770bfad2006-08-22 20:06:07 -04002298 */
2299static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
2300{
2301 struct dentry *dparent, *aparent;
2302
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002303 dentry_lock_for_move(anon, dentry);
David Howells770bfad2006-08-22 20:06:07 -04002304
Nick Piggin31e6b012011-01-07 17:49:52 +11002305 write_seqcount_begin(&dentry->d_seq);
2306 write_seqcount_begin(&anon->d_seq);
2307
David Howells770bfad2006-08-22 20:06:07 -04002308 dparent = dentry->d_parent;
2309 aparent = anon->d_parent;
2310
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002311 switch_names(dentry, anon);
2312 swap(dentry->d_name.hash, anon->d_name.hash);
2313
David Howells770bfad2006-08-22 20:06:07 -04002314 dentry->d_parent = (aparent == anon) ? dentry : aparent;
2315 list_del(&dentry->d_u.d_child);
2316 if (!IS_ROOT(dentry))
2317 list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
2318 else
2319 INIT_LIST_HEAD(&dentry->d_u.d_child);
2320
2321 anon->d_parent = (dparent == dentry) ? anon : dparent;
2322 list_del(&anon->d_u.d_child);
2323 if (!IS_ROOT(anon))
2324 list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs);
2325 else
2326 INIT_LIST_HEAD(&anon->d_u.d_child);
2327
Nick Piggin31e6b012011-01-07 17:49:52 +11002328 write_seqcount_end(&dentry->d_seq);
2329 write_seqcount_end(&anon->d_seq);
2330
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002331 dentry_unlock_parents_for_move(anon, dentry);
2332 spin_unlock(&dentry->d_lock);
2333
2334 /* anon->d_lock still locked, returns locked */
David Howells770bfad2006-08-22 20:06:07 -04002335 anon->d_flags &= ~DCACHE_DISCONNECTED;
2336}
2337
2338/**
2339 * d_materialise_unique - introduce an inode into the tree
2340 * @dentry: candidate dentry
2341 * @inode: inode to bind to the dentry, to which aliases may be attached
2342 *
2343 * Introduces an dentry into the tree, substituting an extant disconnected
2344 * root directory alias in its place if there is one
2345 */
2346struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
2347{
Trond Myklebust9eaef272006-10-21 10:24:20 -07002348 struct dentry *actual;
David Howells770bfad2006-08-22 20:06:07 -04002349
2350 BUG_ON(!d_unhashed(dentry));
2351
David Howells770bfad2006-08-22 20:06:07 -04002352 if (!inode) {
2353 actual = dentry;
OGAWA Hirofumi360da902008-10-16 07:50:28 +09002354 __d_instantiate(dentry, NULL);
Nick Piggin357f8e62011-01-07 17:49:42 +11002355 d_rehash(actual);
2356 goto out_nolock;
David Howells770bfad2006-08-22 20:06:07 -04002357 }
2358
Nick Piggin873feea2011-01-07 17:50:06 +11002359 spin_lock(&inode->i_lock);
Nick Piggin357f8e62011-01-07 17:49:42 +11002360
Trond Myklebust9eaef272006-10-21 10:24:20 -07002361 if (S_ISDIR(inode->i_mode)) {
2362 struct dentry *alias;
David Howells770bfad2006-08-22 20:06:07 -04002363
Trond Myklebust9eaef272006-10-21 10:24:20 -07002364 /* Does an aliased dentry already exist? */
2365 alias = __d_find_alias(inode, 0);
2366 if (alias) {
2367 actual = alias;
Al Viro18367502011-07-12 21:42:24 -04002368 write_seqlock(&rename_lock);
2369
2370 if (d_ancestor(alias, dentry)) {
2371 /* Check for loops */
2372 actual = ERR_PTR(-ELOOP);
2373 } else if (IS_ROOT(alias)) {
2374 /* Is this an anonymous mountpoint that we
2375 * could splice into our tree? */
Trond Myklebust9eaef272006-10-21 10:24:20 -07002376 __d_materialise_dentry(dentry, alias);
Al Viro18367502011-07-12 21:42:24 -04002377 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002378 __d_drop(alias);
2379 goto found;
Al Viro18367502011-07-12 21:42:24 -04002380 } else {
2381 /* Nope, but we must(!) avoid directory
2382 * aliasing */
2383 actual = __d_unalias(inode, dentry, alias);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002384 }
Al Viro18367502011-07-12 21:42:24 -04002385 write_sequnlock(&rename_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002386 if (IS_ERR(actual))
2387 dput(alias);
2388 goto out_nolock;
2389 }
David Howells770bfad2006-08-22 20:06:07 -04002390 }
2391
2392 /* Add a unique reference */
2393 actual = __d_instantiate_unique(dentry, inode);
2394 if (!actual)
2395 actual = dentry;
Nick Piggin357f8e62011-01-07 17:49:42 +11002396 else
2397 BUG_ON(!d_unhashed(actual));
David Howells770bfad2006-08-22 20:06:07 -04002398
David Howells770bfad2006-08-22 20:06:07 -04002399 spin_lock(&actual->d_lock);
2400found:
2401 _d_rehash(actual);
2402 spin_unlock(&actual->d_lock);
Nick Piggin873feea2011-01-07 17:50:06 +11002403 spin_unlock(&inode->i_lock);
Trond Myklebust9eaef272006-10-21 10:24:20 -07002404out_nolock:
David Howells770bfad2006-08-22 20:06:07 -04002405 if (actual == dentry) {
2406 security_d_instantiate(dentry, inode);
2407 return NULL;
2408 }
2409
2410 iput(inode);
2411 return actual;
David Howells770bfad2006-08-22 20:06:07 -04002412}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002413EXPORT_SYMBOL_GPL(d_materialise_unique);
David Howells770bfad2006-08-22 20:06:07 -04002414
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002415static int prepend(char **buffer, int *buflen, const char *str, int namelen)
Ram Pai6092d042008-03-27 13:06:20 +01002416{
2417 *buflen -= namelen;
2418 if (*buflen < 0)
2419 return -ENAMETOOLONG;
2420 *buffer -= namelen;
2421 memcpy(*buffer, str, namelen);
2422 return 0;
2423}
2424
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002425static int prepend_name(char **buffer, int *buflen, struct qstr *name)
2426{
2427 return prepend(buffer, buflen, name->name, name->len);
2428}
2429
Linus Torvalds1da177e2005-04-16 15:20:36 -07002430/**
Randy Dunlap208898c2010-11-18 15:02:49 -08002431 * prepend_path - Prepend path string to a buffer
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002432 * @path: the dentry/vfsmount to report
2433 * @root: root vfsmnt/dentry (may be modified by this function)
2434 * @buffer: pointer to the end of the buffer
2435 * @buflen: pointer to buffer length
2436 *
Nick Piggin949854d2011-01-07 17:49:37 +11002437 * Caller holds the rename_lock.
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002438 *
2439 * If path is not reachable from the supplied root, then the value of
2440 * root is changed (without modifying refcounts).
2441 */
2442static int prepend_path(const struct path *path, struct path *root,
2443 char **buffer, int *buflen)
2444{
2445 struct dentry *dentry = path->dentry;
2446 struct vfsmount *vfsmnt = path->mnt;
2447 bool slash = false;
2448 int error = 0;
2449
Nick Piggin99b7db72010-08-18 04:37:39 +10002450 br_read_lock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002451 while (dentry != root->dentry || vfsmnt != root->mnt) {
2452 struct dentry * parent;
2453
2454 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
2455 /* Global root? */
2456 if (vfsmnt->mnt_parent == vfsmnt) {
2457 goto global_root;
2458 }
2459 dentry = vfsmnt->mnt_mountpoint;
2460 vfsmnt = vfsmnt->mnt_parent;
2461 continue;
2462 }
2463 parent = dentry->d_parent;
2464 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002465 spin_lock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002466 error = prepend_name(buffer, buflen, &dentry->d_name);
Nick Piggin9abca362011-01-07 17:49:36 +11002467 spin_unlock(&dentry->d_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002468 if (!error)
2469 error = prepend(buffer, buflen, "/", 1);
2470 if (error)
2471 break;
2472
2473 slash = true;
2474 dentry = parent;
2475 }
2476
2477out:
2478 if (!error && !slash)
2479 error = prepend(buffer, buflen, "/", 1);
2480
Nick Piggin99b7db72010-08-18 04:37:39 +10002481 br_read_unlock(vfsmount_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002482 return error;
2483
2484global_root:
2485 /*
2486 * Filesystems needing to implement special "root names"
2487 * should do so with ->d_dname()
2488 */
2489 if (IS_ROOT(dentry) &&
2490 (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) {
2491 WARN(1, "Root dentry has weird name <%.*s>\n",
2492 (int) dentry->d_name.len, dentry->d_name.name);
2493 }
2494 root->mnt = vfsmnt;
2495 root->dentry = dentry;
2496 goto out;
2497}
2498
2499/**
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002500 * __d_path - return the path of a dentry
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002501 * @path: the dentry/vfsmount to report
2502 * @root: root vfsmnt/dentry (may be modified by this function)
Randy Dunlapcd956a12010-08-14 13:05:31 -07002503 * @buf: buffer to return value in
Linus Torvalds1da177e2005-04-16 15:20:36 -07002504 * @buflen: buffer length
2505 *
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002506 * Convert a dentry into an ASCII path name.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002507 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002508 * Returns a pointer into the buffer or an error code if the
2509 * path was too long.
Linus Torvalds552ce542007-02-13 12:08:18 -08002510 *
Christoph Hellwigbe148242010-10-10 05:36:21 -04002511 * "buflen" should be positive.
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002512 *
2513 * If path is not reachable from the supplied root, then the value of
2514 * root is changed (without modifying refcounts).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515 */
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002516char *__d_path(const struct path *path, struct path *root,
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002517 char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518{
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002519 char *res = buf + buflen;
2520 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002522 prepend(&res, &buflen, "\0", 1);
Nick Piggin949854d2011-01-07 17:49:37 +11002523 write_seqlock(&rename_lock);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002524 error = prepend_path(path, root, &res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002525 write_sequnlock(&rename_lock);
Christoph Hellwigbe148242010-10-10 05:36:21 -04002526
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002527 if (error)
2528 return ERR_PTR(error);
Miklos Szeredif2eb6572010-08-10 11:41:39 +02002529 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530}
2531
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002532/*
2533 * same as __d_path but appends "(deleted)" for unlinked files.
2534 */
2535static int path_with_deleted(const struct path *path, struct path *root,
2536 char **buf, int *buflen)
2537{
2538 prepend(buf, buflen, "\0", 1);
2539 if (d_unlinked(path->dentry)) {
2540 int error = prepend(buf, buflen, " (deleted)", 10);
2541 if (error)
2542 return error;
2543 }
2544
2545 return prepend_path(path, root, buf, buflen);
2546}
2547
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002548static int prepend_unreachable(char **buffer, int *buflen)
2549{
2550 return prepend(buffer, buflen, "(unreachable)", 13);
2551}
2552
Jan Bluncka03a8a702008-02-14 19:38:32 -08002553/**
2554 * d_path - return the path of a dentry
Jan Blunckcf28b482008-02-14 19:38:44 -08002555 * @path: path to report
Jan Bluncka03a8a702008-02-14 19:38:32 -08002556 * @buf: buffer to return value in
2557 * @buflen: buffer length
2558 *
2559 * Convert a dentry into an ASCII path name. If the entry has been deleted
2560 * the string " (deleted)" is appended. Note that this is ambiguous.
2561 *
Arjan van de Ven52afeef2008-12-01 14:35:00 -08002562 * Returns a pointer into the buffer or an error code if the path was
2563 * too long. Note: Callers should use the returned pointer, not the passed
2564 * in buffer, to use the name! The implementation often starts at an offset
2565 * into the buffer, and may leave 0 bytes at the start.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002566 *
Miklos Szeredi31f3e0b2008-06-23 18:11:52 +02002567 * "buflen" should be positive.
Jan Bluncka03a8a702008-02-14 19:38:32 -08002568 */
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -07002569char *d_path(const struct path *path, char *buf, int buflen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002570{
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002571 char *res = buf + buflen;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002572 struct path root;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002573 struct path tmp;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002574 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002575
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002576 /*
2577 * We have various synthetic filesystems that never get mounted. On
2578 * these filesystems dentries are never used for lookup purposes, and
2579 * thus don't need to be hashed. They also don't need a name until a
2580 * user wants to identify the object in /proc/pid/fd/. The little hack
2581 * below allows us to generate a name for these objects on demand:
2582 */
Jan Blunckcf28b482008-02-14 19:38:44 -08002583 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2584 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002585
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002586 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002587 write_seqlock(&rename_lock);
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002588 tmp = root;
Miklos Szerediffd1f4e2010-08-10 11:41:40 +02002589 error = path_with_deleted(path, &tmp, &res, &buflen);
2590 if (error)
2591 res = ERR_PTR(error);
Nick Piggin949854d2011-01-07 17:49:37 +11002592 write_sequnlock(&rename_lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002593 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002594 return res;
2595}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002596EXPORT_SYMBOL(d_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002597
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002598/**
2599 * d_path_with_unreachable - return the path of a dentry
2600 * @path: path to report
2601 * @buf: buffer to return value in
2602 * @buflen: buffer length
2603 *
2604 * The difference from d_path() is that this prepends "(unreachable)"
2605 * to paths which are unreachable from the current process' root.
2606 */
2607char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
2608{
2609 char *res = buf + buflen;
2610 struct path root;
2611 struct path tmp;
2612 int error;
2613
2614 if (path->dentry->d_op && path->dentry->d_op->d_dname)
2615 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
2616
2617 get_fs_root(current->fs, &root);
Nick Piggin949854d2011-01-07 17:49:37 +11002618 write_seqlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002619 tmp = root;
2620 error = path_with_deleted(path, &tmp, &res, &buflen);
2621 if (!error && !path_equal(&tmp, &root))
2622 error = prepend_unreachable(&res, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002623 write_sequnlock(&rename_lock);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002624 path_put(&root);
2625 if (error)
2626 res = ERR_PTR(error);
2627
2628 return res;
2629}
2630
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631/*
Eric Dumazetc23fbb62007-05-08 00:26:18 -07002632 * Helper function for dentry_operations.d_dname() members
2633 */
2634char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
2635 const char *fmt, ...)
2636{
2637 va_list args;
2638 char temp[64];
2639 int sz;
2640
2641 va_start(args, fmt);
2642 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
2643 va_end(args);
2644
2645 if (sz > sizeof(temp) || sz > buflen)
2646 return ERR_PTR(-ENAMETOOLONG);
2647
2648 buffer += buflen - sz;
2649 return memcpy(buffer, temp, sz);
2650}
2651
2652/*
Ram Pai6092d042008-03-27 13:06:20 +01002653 * Write full pathname from the root of the filesystem into the buffer.
2654 */
Nick Pigginec2447c2011-01-07 17:49:29 +11002655static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
Ram Pai6092d042008-03-27 13:06:20 +01002656{
2657 char *end = buf + buflen;
2658 char *retval;
2659
Ram Pai6092d042008-03-27 13:06:20 +01002660 prepend(&end, &buflen, "\0", 1);
Ram Pai6092d042008-03-27 13:06:20 +01002661 if (buflen < 1)
2662 goto Elong;
2663 /* Get '/' right */
2664 retval = end-1;
2665 *retval = '/';
2666
Miklos Szeredicdd16d02008-06-23 18:11:53 +02002667 while (!IS_ROOT(dentry)) {
2668 struct dentry *parent = dentry->d_parent;
Nick Piggin9abca362011-01-07 17:49:36 +11002669 int error;
Ram Pai6092d042008-03-27 13:06:20 +01002670
Ram Pai6092d042008-03-27 13:06:20 +01002671 prefetch(parent);
Nick Piggin9abca362011-01-07 17:49:36 +11002672 spin_lock(&dentry->d_lock);
2673 error = prepend_name(&end, &buflen, &dentry->d_name);
2674 spin_unlock(&dentry->d_lock);
2675 if (error != 0 || prepend(&end, &buflen, "/", 1) != 0)
Ram Pai6092d042008-03-27 13:06:20 +01002676 goto Elong;
2677
2678 retval = end;
2679 dentry = parent;
2680 }
Al Viroc1031352010-06-06 22:31:14 -04002681 return retval;
2682Elong:
2683 return ERR_PTR(-ENAMETOOLONG);
2684}
Nick Pigginec2447c2011-01-07 17:49:29 +11002685
2686char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
2687{
2688 char *retval;
2689
Nick Piggin949854d2011-01-07 17:49:37 +11002690 write_seqlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002691 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002692 write_sequnlock(&rename_lock);
Nick Pigginec2447c2011-01-07 17:49:29 +11002693
2694 return retval;
2695}
2696EXPORT_SYMBOL(dentry_path_raw);
Al Viroc1031352010-06-06 22:31:14 -04002697
2698char *dentry_path(struct dentry *dentry, char *buf, int buflen)
2699{
2700 char *p = NULL;
2701 char *retval;
2702
Nick Piggin949854d2011-01-07 17:49:37 +11002703 write_seqlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002704 if (d_unlinked(dentry)) {
2705 p = buf + buflen;
2706 if (prepend(&p, &buflen, "//deleted", 10) != 0)
2707 goto Elong;
2708 buflen++;
2709 }
2710 retval = __dentry_path(dentry, buf, buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002711 write_sequnlock(&rename_lock);
Al Viroc1031352010-06-06 22:31:14 -04002712 if (!IS_ERR(retval) && p)
2713 *p = '/'; /* restore '/' overriden with '\0' */
Ram Pai6092d042008-03-27 13:06:20 +01002714 return retval;
2715Elong:
Ram Pai6092d042008-03-27 13:06:20 +01002716 return ERR_PTR(-ENAMETOOLONG);
2717}
2718
2719/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002720 * NOTE! The user-level library version returns a
2721 * character pointer. The kernel system call just
2722 * returns the length of the buffer filled (which
2723 * includes the ending '\0' character), or a negative
2724 * error value. So libc would do something like
2725 *
2726 * char *getcwd(char * buf, size_t size)
2727 * {
2728 * int retval;
2729 *
2730 * retval = sys_getcwd(buf, size);
2731 * if (retval >= 0)
2732 * return buf;
2733 * errno = -retval;
2734 * return NULL;
2735 * }
2736 */
Heiko Carstens3cdad422009-01-14 14:14:22 +01002737SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002738{
Linus Torvalds552ce542007-02-13 12:08:18 -08002739 int error;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002740 struct path pwd, root;
Linus Torvalds552ce542007-02-13 12:08:18 -08002741 char *page = (char *) __get_free_page(GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742
2743 if (!page)
2744 return -ENOMEM;
2745
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02002746 get_fs_root_and_pwd(current->fs, &root, &pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747
Linus Torvalds552ce542007-02-13 12:08:18 -08002748 error = -ENOENT;
Nick Piggin949854d2011-01-07 17:49:37 +11002749 write_seqlock(&rename_lock);
Alexey Dobriyanf3da3922009-05-04 03:32:03 +04002750 if (!d_unlinked(pwd.dentry)) {
Linus Torvalds552ce542007-02-13 12:08:18 -08002751 unsigned long len;
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +01002752 struct path tmp = root;
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002753 char *cwd = page + PAGE_SIZE;
2754 int buflen = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002755
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002756 prepend(&cwd, &buflen, "\0", 1);
2757 error = prepend_path(&pwd, &tmp, &cwd, &buflen);
Nick Piggin949854d2011-01-07 17:49:37 +11002758 write_sequnlock(&rename_lock);
Linus Torvalds552ce542007-02-13 12:08:18 -08002759
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002760 if (error)
Linus Torvalds552ce542007-02-13 12:08:18 -08002761 goto out;
2762
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +02002763 /* Unreachable from current root */
2764 if (!path_equal(&tmp, &root)) {
2765 error = prepend_unreachable(&cwd, &buflen);
2766 if (error)
2767 goto out;
2768 }
2769
Linus Torvalds552ce542007-02-13 12:08:18 -08002770 error = -ERANGE;
2771 len = PAGE_SIZE + page - cwd;
2772 if (len <= size) {
2773 error = len;
2774 if (copy_to_user(buf, cwd, len))
2775 error = -EFAULT;
2776 }
Nick Piggin949854d2011-01-07 17:49:37 +11002777 } else {
2778 write_sequnlock(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002779 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002780
2781out:
Jan Blunck6ac08c32008-02-14 19:34:38 -08002782 path_put(&pwd);
2783 path_put(&root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002784 free_page((unsigned long) page);
2785 return error;
2786}
2787
2788/*
2789 * Test whether new_dentry is a subdirectory of old_dentry.
2790 *
2791 * Trivially implemented using the dcache structure
2792 */
2793
2794/**
2795 * is_subdir - is new dentry a subdirectory of old_dentry
2796 * @new_dentry: new dentry
2797 * @old_dentry: old dentry
2798 *
2799 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2800 * Returns 0 otherwise.
2801 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2802 */
2803
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002804int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002805{
2806 int result;
Nick Piggin949854d2011-01-07 17:49:37 +11002807 unsigned seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002808
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002809 if (new_dentry == old_dentry)
2810 return 1;
2811
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002812 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002813 /* for restarting inner loop in case of seq retry */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002814 seq = read_seqbegin(&rename_lock);
Nick Piggin949854d2011-01-07 17:49:37 +11002815 /*
2816 * Need rcu_readlock to protect against the d_parent trashing
2817 * due to d_move
2818 */
2819 rcu_read_lock();
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002820 if (d_ancestor(old_dentry, new_dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821 result = 1;
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09002822 else
2823 result = 0;
Nick Piggin949854d2011-01-07 17:49:37 +11002824 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002825 } while (read_seqretry(&rename_lock, seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826
2827 return result;
2828}
2829
Al Viro2096f752010-01-30 13:16:21 -05002830int path_is_under(struct path *path1, struct path *path2)
2831{
2832 struct vfsmount *mnt = path1->mnt;
2833 struct dentry *dentry = path1->dentry;
2834 int res;
Nick Piggin99b7db72010-08-18 04:37:39 +10002835
2836 br_read_lock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002837 if (mnt != path2->mnt) {
2838 for (;;) {
2839 if (mnt->mnt_parent == mnt) {
Nick Piggin99b7db72010-08-18 04:37:39 +10002840 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002841 return 0;
2842 }
2843 if (mnt->mnt_parent == path2->mnt)
2844 break;
2845 mnt = mnt->mnt_parent;
2846 }
2847 dentry = mnt->mnt_mountpoint;
2848 }
2849 res = is_subdir(dentry, path2->dentry);
Nick Piggin99b7db72010-08-18 04:37:39 +10002850 br_read_unlock(vfsmount_lock);
Al Viro2096f752010-01-30 13:16:21 -05002851 return res;
2852}
2853EXPORT_SYMBOL(path_is_under);
2854
Linus Torvalds1da177e2005-04-16 15:20:36 -07002855void d_genocide(struct dentry *root)
2856{
Nick Piggin949854d2011-01-07 17:49:37 +11002857 struct dentry *this_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858 struct list_head *next;
Nick Piggin949854d2011-01-07 17:49:37 +11002859 unsigned seq;
Nick Piggin58db63d2011-01-07 17:49:39 +11002860 int locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002861
Nick Piggin949854d2011-01-07 17:49:37 +11002862 seq = read_seqbegin(&rename_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002863again:
2864 this_parent = root;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002865 spin_lock(&this_parent->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002866repeat:
2867 next = this_parent->d_subdirs.next;
2868resume:
2869 while (next != &this_parent->d_subdirs) {
2870 struct list_head *tmp = next;
Eric Dumazet5160ee62006-01-08 01:03:32 -08002871 struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002872 next = tmp->next;
Nick Piggin949854d2011-01-07 17:49:37 +11002873
Nick Pigginda502952011-01-07 17:49:33 +11002874 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
2875 if (d_unhashed(dentry) || !dentry->d_inode) {
2876 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002877 continue;
Nick Pigginda502952011-01-07 17:49:33 +11002878 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002879 if (!list_empty(&dentry->d_subdirs)) {
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002880 spin_unlock(&this_parent->d_lock);
2881 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002882 this_parent = dentry;
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002883 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002884 goto repeat;
2885 }
Nick Piggin949854d2011-01-07 17:49:37 +11002886 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
2887 dentry->d_flags |= DCACHE_GENOCIDE;
2888 dentry->d_count--;
2889 }
Nick Pigginb7ab39f2011-01-07 17:49:32 +11002890 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002891 }
2892 if (this_parent != root) {
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002893 struct dentry *child = this_parent;
Nick Piggin949854d2011-01-07 17:49:37 +11002894 if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
2895 this_parent->d_flags |= DCACHE_GENOCIDE;
2896 this_parent->d_count--;
2897 }
Linus Torvaldsc826cb72011-03-15 15:29:21 -07002898 this_parent = try_to_ascend(this_parent, locked, seq);
2899 if (!this_parent)
Nick Piggin949854d2011-01-07 17:49:37 +11002900 goto rename_retry;
Nick Piggin949854d2011-01-07 17:49:37 +11002901 next = child->d_u.d_child.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002902 goto resume;
2903 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +11002904 spin_unlock(&this_parent->d_lock);
Nick Piggin58db63d2011-01-07 17:49:39 +11002905 if (!locked && read_seqretry(&rename_lock, seq))
Nick Piggin949854d2011-01-07 17:49:37 +11002906 goto rename_retry;
Nick Piggin58db63d2011-01-07 17:49:39 +11002907 if (locked)
2908 write_sequnlock(&rename_lock);
2909 return;
2910
2911rename_retry:
2912 locked = 1;
2913 write_seqlock(&rename_lock);
2914 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002915}
2916
2917/**
2918 * find_inode_number - check for dentry with name
2919 * @dir: directory to check
2920 * @name: Name to find.
2921 *
2922 * Check whether a dentry already exists for the given name,
2923 * and return the inode number if it has an inode. Otherwise
2924 * 0 is returned.
2925 *
2926 * This routine is used to post-process directory listings for
2927 * filesystems using synthetic inode numbers, and is necessary
2928 * to keep getcwd() working.
2929 */
2930
2931ino_t find_inode_number(struct dentry *dir, struct qstr *name)
2932{
2933 struct dentry * dentry;
2934 ino_t ino = 0;
2935
Eric W. Biederman3e7e2412006-03-31 02:31:43 -08002936 dentry = d_hash_and_lookup(dir, name);
2937 if (dentry) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938 if (dentry->d_inode)
2939 ino = dentry->d_inode->i_ino;
2940 dput(dentry);
2941 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002942 return ino;
2943}
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07002944EXPORT_SYMBOL(find_inode_number);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002945
2946static __initdata unsigned long dhash_entries;
2947static int __init set_dhash_entries(char *str)
2948{
2949 if (!str)
2950 return 0;
2951 dhash_entries = simple_strtoul(str, &str, 0);
2952 return 1;
2953}
2954__setup("dhash_entries=", set_dhash_entries);
2955
2956static void __init dcache_init_early(void)
2957{
2958 int loop;
2959
2960 /* If hashes are distributed across NUMA nodes, defer
2961 * hash allocation until vmalloc space is available.
2962 */
2963 if (hashdist)
2964 return;
2965
2966 dentry_hashtable =
2967 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002968 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07002969 dhash_entries,
2970 13,
2971 HASH_EARLY,
2972 &d_hash_shift,
2973 &d_hash_mask,
2974 0);
2975
2976 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002977 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978}
2979
Denis Cheng74bf17c2007-10-16 23:26:30 -07002980static void __init dcache_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002981{
2982 int loop;
2983
2984 /*
2985 * A constructor could be added for stable state like the lists,
2986 * but it is probably not worth it because of the cache nature
2987 * of the dcache.
2988 */
Christoph Lameter0a31bd52007-05-06 14:49:57 -07002989 dentry_cache = KMEM_CACHE(dentry,
2990 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002991
2992 /* Hash may have been set up in dcache_init_early */
2993 if (!hashdist)
2994 return;
2995
2996 dentry_hashtable =
2997 alloc_large_system_hash("Dentry cache",
Linus Torvaldsb07ad992011-04-23 22:32:03 -07002998 sizeof(struct hlist_bl_head),
Linus Torvalds1da177e2005-04-16 15:20:36 -07002999 dhash_entries,
3000 13,
3001 0,
3002 &d_hash_shift,
3003 &d_hash_mask,
3004 0);
3005
3006 for (loop = 0; loop < (1 << d_hash_shift); loop++)
Linus Torvaldsb07ad992011-04-23 22:32:03 -07003007 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003008}
3009
3010/* SLAB cache for __getname() consumers */
Christoph Lametere18b8902006-12-06 20:33:20 -08003011struct kmem_cache *names_cachep __read_mostly;
H Hartley Sweetenec4f8602010-01-05 13:45:18 -07003012EXPORT_SYMBOL(names_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003013
Linus Torvalds1da177e2005-04-16 15:20:36 -07003014EXPORT_SYMBOL(d_genocide);
3015
Linus Torvalds1da177e2005-04-16 15:20:36 -07003016void __init vfs_caches_init_early(void)
3017{
3018 dcache_init_early();
3019 inode_init_early();
3020}
3021
3022void __init vfs_caches_init(unsigned long mempages)
3023{
3024 unsigned long reserve;
3025
3026 /* Base hash sizes on available memory, with a reserve equal to
3027 150% of current kernel size */
3028
3029 reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
3030 mempages -= reserve;
3031
3032 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
Paul Mundt20c2df82007-07-20 10:11:58 +09003033 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003034
Denis Cheng74bf17c2007-10-16 23:26:30 -07003035 dcache_init();
3036 inode_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003037 files_init(mempages);
Denis Cheng74bf17c2007-10-16 23:26:30 -07003038 mnt_init();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003039 bdev_cache_init();
3040 chrdev_init();
3041}