Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
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 | ||
1da177e4 LT |
17 | #include <linux/syscalls.h> |
18 | #include <linux/string.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/fs.h> | |
7a91bf7f | 21 | #include <linux/fsnotify.h> |
1da177e4 LT |
22 | #include <linux/slab.h> |
23 | #include <linux/init.h> | |
1da177e4 LT |
24 | #include <linux/hash.h> |
25 | #include <linux/cache.h> | |
630d9c47 | 26 | #include <linux/export.h> |
1da177e4 LT |
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> | |
5ad4e53b | 34 | #include <linux/fs_struct.h> |
613afbf8 | 35 | #include <linux/hardirq.h> |
ceb5bdc2 NP |
36 | #include <linux/bit_spinlock.h> |
37 | #include <linux/rculist_bl.h> | |
268bb0ce | 38 | #include <linux/prefetch.h> |
dd179946 | 39 | #include <linux/ratelimit.h> |
f6041567 | 40 | #include <linux/list_lru.h> |
07f3f05c | 41 | #include "internal.h" |
b2dba1af | 42 | #include "mount.h" |
1da177e4 | 43 | |
789680d1 NP |
44 | /* |
45 | * Usage: | |
873feea0 NP |
46 | * dcache->d_inode->i_lock protects: |
47 | * - i_dentry, d_alias, d_inode of aliases | |
ceb5bdc2 NP |
48 | * dcache_hash_bucket lock protects: |
49 | * - the dcache hash table | |
50 | * s_anon bl list spinlock protects: | |
51 | * - the s_anon list (see __d_drop) | |
19156840 | 52 | * dentry->d_sb->s_dentry_lru_lock protects: |
23044507 NP |
53 | * - the dcache lru lists and counters |
54 | * d_lock protects: | |
55 | * - d_flags | |
56 | * - d_name | |
57 | * - d_lru | |
b7ab39f6 | 58 | * - d_count |
da502956 | 59 | * - d_unhashed() |
2fd6b7f5 NP |
60 | * - d_parent and d_subdirs |
61 | * - childrens' d_child and d_parent | |
b23fb0a6 | 62 | * - d_alias, d_inode |
789680d1 NP |
63 | * |
64 | * Ordering: | |
873feea0 | 65 | * dentry->d_inode->i_lock |
b5c84bf6 | 66 | * dentry->d_lock |
19156840 | 67 | * dentry->d_sb->s_dentry_lru_lock |
ceb5bdc2 NP |
68 | * dcache_hash_bucket lock |
69 | * s_anon lock | |
789680d1 | 70 | * |
da502956 NP |
71 | * If there is an ancestor relationship: |
72 | * dentry->d_parent->...->d_parent->d_lock | |
73 | * ... | |
74 | * dentry->d_parent->d_lock | |
75 | * dentry->d_lock | |
76 | * | |
77 | * If no ancestor relationship: | |
789680d1 NP |
78 | * if (dentry1 < dentry2) |
79 | * dentry1->d_lock | |
80 | * dentry2->d_lock | |
81 | */ | |
fa3536cc | 82 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
83 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
84 | ||
74c3cbe3 | 85 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 | 86 | |
949854d0 | 87 | EXPORT_SYMBOL(rename_lock); |
1da177e4 | 88 | |
e18b890b | 89 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 | 90 | |
232d2d60 WL |
91 | /** |
92 | * read_seqbegin_or_lock - begin a sequence number check or locking block | |
18129977 WL |
93 | * @lock: sequence lock |
94 | * @seq : sequence number to be checked | |
232d2d60 WL |
95 | * |
96 | * First try it once optimistically without taking the lock. If that fails, | |
97 | * take the lock. The sequence number is also used as a marker for deciding | |
98 | * whether to be a reader (even) or writer (odd). | |
99 | * N.B. seq must be initialized to an even number to begin with. | |
100 | */ | |
101 | static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq) | |
102 | { | |
48f5ec21 | 103 | if (!(*seq & 1)) /* Even */ |
232d2d60 | 104 | *seq = read_seqbegin(lock); |
48f5ec21 | 105 | else /* Odd */ |
18129977 | 106 | read_seqlock_excl(lock); |
232d2d60 WL |
107 | } |
108 | ||
48f5ec21 | 109 | static inline int need_seqretry(seqlock_t *lock, int seq) |
232d2d60 | 110 | { |
48f5ec21 AV |
111 | return !(seq & 1) && read_seqretry(lock, seq); |
112 | } | |
113 | ||
114 | static inline void done_seqretry(seqlock_t *lock, int seq) | |
115 | { | |
116 | if (seq & 1) | |
18129977 | 117 | read_sequnlock_excl(lock); |
232d2d60 WL |
118 | } |
119 | ||
1da177e4 LT |
120 | /* |
121 | * This is the single most critical data structure when it comes | |
122 | * to the dcache: the hashtable for lookups. Somebody should try | |
123 | * to make this good - I've just made it work. | |
124 | * | |
125 | * This hash-function tries to avoid losing too many bits of hash | |
126 | * information, yet avoid using a prime hash-size or similar. | |
127 | */ | |
128 | #define D_HASHBITS d_hash_shift | |
129 | #define D_HASHMASK d_hash_mask | |
130 | ||
fa3536cc ED |
131 | static unsigned int d_hash_mask __read_mostly; |
132 | static unsigned int d_hash_shift __read_mostly; | |
ceb5bdc2 | 133 | |
b07ad996 | 134 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
ceb5bdc2 | 135 | |
8966be90 | 136 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
6d7d1a0d | 137 | unsigned int hash) |
ceb5bdc2 | 138 | { |
6d7d1a0d LT |
139 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
140 | hash = hash + (hash >> D_HASHBITS); | |
ceb5bdc2 NP |
141 | return dentry_hashtable + (hash & D_HASHMASK); |
142 | } | |
143 | ||
1da177e4 LT |
144 | /* Statistics gathering. */ |
145 | struct dentry_stat_t dentry_stat = { | |
146 | .age_limit = 45, | |
147 | }; | |
148 | ||
3942c07c | 149 | static DEFINE_PER_CPU(long, nr_dentry); |
62d36c77 | 150 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
312d3ca8 CH |
151 | |
152 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
62d36c77 DC |
153 | |
154 | /* | |
155 | * Here we resort to our own counters instead of using generic per-cpu counters | |
156 | * for consistency with what the vfs inode code does. We are expected to harvest | |
157 | * better code and performance by having our own specialized counters. | |
158 | * | |
159 | * Please note that the loop is done over all possible CPUs, not over all online | |
160 | * CPUs. The reason for this is that we don't want to play games with CPUs going | |
161 | * on and off. If one of them goes off, we will just keep their counters. | |
162 | * | |
163 | * glommer: See cffbc8a for details, and if you ever intend to change this, | |
164 | * please update all vfs counters to match. | |
165 | */ | |
3942c07c | 166 | static long get_nr_dentry(void) |
3e880fb5 NP |
167 | { |
168 | int i; | |
3942c07c | 169 | long sum = 0; |
3e880fb5 NP |
170 | for_each_possible_cpu(i) |
171 | sum += per_cpu(nr_dentry, i); | |
172 | return sum < 0 ? 0 : sum; | |
173 | } | |
174 | ||
62d36c77 DC |
175 | static long get_nr_dentry_unused(void) |
176 | { | |
177 | int i; | |
178 | long sum = 0; | |
179 | for_each_possible_cpu(i) | |
180 | sum += per_cpu(nr_dentry_unused, i); | |
181 | return sum < 0 ? 0 : sum; | |
182 | } | |
183 | ||
312d3ca8 CH |
184 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
185 | size_t *lenp, loff_t *ppos) | |
186 | { | |
3e880fb5 | 187 | dentry_stat.nr_dentry = get_nr_dentry(); |
62d36c77 | 188 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
3942c07c | 189 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
312d3ca8 CH |
190 | } |
191 | #endif | |
192 | ||
5483f18e LT |
193 | /* |
194 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. | |
195 | * The strings are both count bytes long, and count is non-zero. | |
196 | */ | |
e419b4cc LT |
197 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
198 | ||
199 | #include <asm/word-at-a-time.h> | |
200 | /* | |
201 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a | |
202 | * aligned allocation for this particular component. We don't | |
203 | * strictly need the load_unaligned_zeropad() safety, but it | |
204 | * doesn't hurt either. | |
205 | * | |
206 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do | |
207 | * need the careful unaligned handling. | |
208 | */ | |
94753db5 | 209 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
5483f18e | 210 | { |
bfcfaa77 | 211 | unsigned long a,b,mask; |
bfcfaa77 LT |
212 | |
213 | for (;;) { | |
12f8ad4b | 214 | a = *(unsigned long *)cs; |
e419b4cc | 215 | b = load_unaligned_zeropad(ct); |
bfcfaa77 LT |
216 | if (tcount < sizeof(unsigned long)) |
217 | break; | |
218 | if (unlikely(a != b)) | |
219 | return 1; | |
220 | cs += sizeof(unsigned long); | |
221 | ct += sizeof(unsigned long); | |
222 | tcount -= sizeof(unsigned long); | |
223 | if (!tcount) | |
224 | return 0; | |
225 | } | |
226 | mask = ~(~0ul << tcount*8); | |
227 | return unlikely(!!((a ^ b) & mask)); | |
e419b4cc LT |
228 | } |
229 | ||
bfcfaa77 | 230 | #else |
e419b4cc | 231 | |
94753db5 | 232 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
e419b4cc | 233 | { |
5483f18e LT |
234 | do { |
235 | if (*cs != *ct) | |
236 | return 1; | |
237 | cs++; | |
238 | ct++; | |
239 | tcount--; | |
240 | } while (tcount); | |
241 | return 0; | |
242 | } | |
243 | ||
e419b4cc LT |
244 | #endif |
245 | ||
94753db5 LT |
246 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
247 | { | |
6326c71f | 248 | const unsigned char *cs; |
94753db5 LT |
249 | /* |
250 | * Be careful about RCU walk racing with rename: | |
251 | * use ACCESS_ONCE to fetch the name pointer. | |
252 | * | |
253 | * NOTE! Even if a rename will mean that the length | |
254 | * was not loaded atomically, we don't care. The | |
255 | * RCU walk will check the sequence count eventually, | |
256 | * and catch it. And we won't overrun the buffer, | |
257 | * because we're reading the name pointer atomically, | |
258 | * and a dentry name is guaranteed to be properly | |
259 | * terminated with a NUL byte. | |
260 | * | |
261 | * End result: even if 'len' is wrong, we'll exit | |
262 | * early because the data cannot match (there can | |
263 | * be no NUL in the ct/tcount data) | |
264 | */ | |
6326c71f LT |
265 | cs = ACCESS_ONCE(dentry->d_name.name); |
266 | smp_read_barrier_depends(); | |
267 | return dentry_string_cmp(cs, ct, tcount); | |
94753db5 LT |
268 | } |
269 | ||
9c82ab9c | 270 | static void __d_free(struct rcu_head *head) |
1da177e4 | 271 | { |
9c82ab9c CH |
272 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
273 | ||
b3d9b7a3 | 274 | WARN_ON(!hlist_unhashed(&dentry->d_alias)); |
1da177e4 LT |
275 | if (dname_external(dentry)) |
276 | kfree(dentry->d_name.name); | |
277 | kmem_cache_free(dentry_cache, dentry); | |
278 | } | |
279 | ||
280 | /* | |
b5c84bf6 | 281 | * no locks, please. |
1da177e4 LT |
282 | */ |
283 | static void d_free(struct dentry *dentry) | |
284 | { | |
0d98439e | 285 | BUG_ON((int)dentry->d_lockref.count > 0); |
3e880fb5 | 286 | this_cpu_dec(nr_dentry); |
1da177e4 LT |
287 | if (dentry->d_op && dentry->d_op->d_release) |
288 | dentry->d_op->d_release(dentry); | |
312d3ca8 | 289 | |
dea3667b LT |
290 | /* if dentry was never visible to RCU, immediate free is OK */ |
291 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) | |
9c82ab9c | 292 | __d_free(&dentry->d_u.d_rcu); |
b3423415 | 293 | else |
9c82ab9c | 294 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
1da177e4 LT |
295 | } |
296 | ||
31e6b01f NP |
297 | /** |
298 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups | |
ff5fdb61 | 299 | * @dentry: the target dentry |
31e6b01f NP |
300 | * After this call, in-progress rcu-walk path lookup will fail. This |
301 | * should be called after unhashing, and after changing d_inode (if | |
302 | * the dentry has not already been unhashed). | |
303 | */ | |
304 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) | |
305 | { | |
306 | assert_spin_locked(&dentry->d_lock); | |
307 | /* Go through a barrier */ | |
308 | write_seqcount_barrier(&dentry->d_seq); | |
309 | } | |
310 | ||
1da177e4 LT |
311 | /* |
312 | * Release the dentry's inode, using the filesystem | |
31e6b01f NP |
313 | * d_iput() operation if defined. Dentry has no refcount |
314 | * and is unhashed. | |
1da177e4 | 315 | */ |
858119e1 | 316 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 | 317 | __releases(dentry->d_lock) |
873feea0 | 318 | __releases(dentry->d_inode->i_lock) |
1da177e4 LT |
319 | { |
320 | struct inode *inode = dentry->d_inode; | |
321 | if (inode) { | |
322 | dentry->d_inode = NULL; | |
b3d9b7a3 | 323 | hlist_del_init(&dentry->d_alias); |
1da177e4 | 324 | spin_unlock(&dentry->d_lock); |
873feea0 | 325 | spin_unlock(&inode->i_lock); |
f805fbda LT |
326 | if (!inode->i_nlink) |
327 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
328 | if (dentry->d_op && dentry->d_op->d_iput) |
329 | dentry->d_op->d_iput(dentry, inode); | |
330 | else | |
331 | iput(inode); | |
332 | } else { | |
333 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
334 | } |
335 | } | |
336 | ||
31e6b01f NP |
337 | /* |
338 | * Release the dentry's inode, using the filesystem | |
339 | * d_iput() operation if defined. dentry remains in-use. | |
340 | */ | |
341 | static void dentry_unlink_inode(struct dentry * dentry) | |
342 | __releases(dentry->d_lock) | |
873feea0 | 343 | __releases(dentry->d_inode->i_lock) |
31e6b01f NP |
344 | { |
345 | struct inode *inode = dentry->d_inode; | |
346 | dentry->d_inode = NULL; | |
b3d9b7a3 | 347 | hlist_del_init(&dentry->d_alias); |
31e6b01f NP |
348 | dentry_rcuwalk_barrier(dentry); |
349 | spin_unlock(&dentry->d_lock); | |
873feea0 | 350 | spin_unlock(&inode->i_lock); |
31e6b01f NP |
351 | if (!inode->i_nlink) |
352 | fsnotify_inoderemove(inode); | |
353 | if (dentry->d_op && dentry->d_op->d_iput) | |
354 | dentry->d_op->d_iput(dentry, inode); | |
355 | else | |
356 | iput(inode); | |
357 | } | |
358 | ||
89dc77bc LT |
359 | /* |
360 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry | |
361 | * is in use - which includes both the "real" per-superblock | |
362 | * LRU list _and_ the DCACHE_SHRINK_LIST use. | |
363 | * | |
364 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is | |
365 | * on the shrink list (ie not on the superblock LRU list). | |
366 | * | |
367 | * The per-cpu "nr_dentry_unused" counters are updated with | |
368 | * the DCACHE_LRU_LIST bit. | |
369 | * | |
370 | * These helper functions make sure we always follow the | |
371 | * rules. d_lock must be held by the caller. | |
372 | */ | |
373 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) | |
374 | static void d_lru_add(struct dentry *dentry) | |
375 | { | |
376 | D_FLAG_VERIFY(dentry, 0); | |
377 | dentry->d_flags |= DCACHE_LRU_LIST; | |
378 | this_cpu_inc(nr_dentry_unused); | |
379 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
380 | } | |
381 | ||
382 | static void d_lru_del(struct dentry *dentry) | |
383 | { | |
384 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
385 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
386 | this_cpu_dec(nr_dentry_unused); | |
387 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
388 | } | |
389 | ||
390 | static void d_shrink_del(struct dentry *dentry) | |
391 | { | |
392 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
393 | list_del_init(&dentry->d_lru); | |
394 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
395 | this_cpu_dec(nr_dentry_unused); | |
396 | } | |
397 | ||
398 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) | |
399 | { | |
400 | D_FLAG_VERIFY(dentry, 0); | |
401 | list_add(&dentry->d_lru, list); | |
402 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; | |
403 | this_cpu_inc(nr_dentry_unused); | |
404 | } | |
405 | ||
406 | /* | |
407 | * These can only be called under the global LRU lock, ie during the | |
408 | * callback for freeing the LRU list. "isolate" removes it from the | |
409 | * LRU lists entirely, while shrink_move moves it to the indicated | |
410 | * private list. | |
411 | */ | |
412 | static void d_lru_isolate(struct dentry *dentry) | |
413 | { | |
414 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
415 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
416 | this_cpu_dec(nr_dentry_unused); | |
417 | list_del_init(&dentry->d_lru); | |
418 | } | |
419 | ||
420 | static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list) | |
421 | { | |
422 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
423 | dentry->d_flags |= DCACHE_SHRINK_LIST; | |
424 | list_move_tail(&dentry->d_lru, list); | |
425 | } | |
426 | ||
da3bbdd4 | 427 | /* |
f6041567 | 428 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
da3bbdd4 KM |
429 | */ |
430 | static void dentry_lru_add(struct dentry *dentry) | |
431 | { | |
89dc77bc LT |
432 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
433 | d_lru_add(dentry); | |
da3bbdd4 KM |
434 | } |
435 | ||
f0023bc6 SW |
436 | /* |
437 | * Remove a dentry with references from the LRU. | |
dd1f6b2e DC |
438 | * |
439 | * If we are on the shrink list, then we can get to try_prune_one_dentry() and | |
440 | * lose our last reference through the parent walk. In this case, we need to | |
441 | * remove ourselves from the shrink list, not the LRU. | |
f0023bc6 | 442 | */ |
da3bbdd4 KM |
443 | static void dentry_lru_del(struct dentry *dentry) |
444 | { | |
89dc77bc LT |
445 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
446 | if (dentry->d_flags & DCACHE_SHRINK_LIST) | |
447 | return d_shrink_del(dentry); | |
448 | d_lru_del(dentry); | |
da3bbdd4 | 449 | } |
da3bbdd4 KM |
450 | } |
451 | ||
d52b9086 MS |
452 | /** |
453 | * d_kill - kill dentry and return parent | |
454 | * @dentry: dentry to kill | |
ff5fdb61 | 455 | * @parent: parent dentry |
d52b9086 | 456 | * |
31f3e0b3 | 457 | * The dentry must already be unhashed and removed from the LRU. |
d52b9086 MS |
458 | * |
459 | * If this is the root of the dentry tree, return NULL. | |
23044507 | 460 | * |
b5c84bf6 NP |
461 | * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by |
462 | * d_kill. | |
d52b9086 | 463 | */ |
2fd6b7f5 | 464 | static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
31f3e0b3 | 465 | __releases(dentry->d_lock) |
2fd6b7f5 | 466 | __releases(parent->d_lock) |
873feea0 | 467 | __releases(dentry->d_inode->i_lock) |
d52b9086 | 468 | { |
d52b9086 | 469 | list_del(&dentry->d_u.d_child); |
c83ce989 TM |
470 | /* |
471 | * Inform try_to_ascend() that we are no longer attached to the | |
472 | * dentry tree | |
473 | */ | |
b161dfa6 | 474 | dentry->d_flags |= DCACHE_DENTRY_KILLED; |
2fd6b7f5 NP |
475 | if (parent) |
476 | spin_unlock(&parent->d_lock); | |
d52b9086 | 477 | dentry_iput(dentry); |
b7ab39f6 NP |
478 | /* |
479 | * dentry_iput drops the locks, at which point nobody (except | |
480 | * transient RCU lookups) can reach this dentry. | |
481 | */ | |
d52b9086 | 482 | d_free(dentry); |
871c0067 | 483 | return parent; |
d52b9086 MS |
484 | } |
485 | ||
c6627c60 DH |
486 | /* |
487 | * Unhash a dentry without inserting an RCU walk barrier or checking that | |
488 | * dentry->d_lock is locked. The caller must take care of that, if | |
489 | * appropriate. | |
490 | */ | |
491 | static void __d_shrink(struct dentry *dentry) | |
492 | { | |
493 | if (!d_unhashed(dentry)) { | |
494 | struct hlist_bl_head *b; | |
495 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) | |
496 | b = &dentry->d_sb->s_anon; | |
497 | else | |
498 | b = d_hash(dentry->d_parent, dentry->d_name.hash); | |
499 | ||
500 | hlist_bl_lock(b); | |
501 | __hlist_bl_del(&dentry->d_hash); | |
502 | dentry->d_hash.pprev = NULL; | |
503 | hlist_bl_unlock(b); | |
504 | } | |
505 | } | |
506 | ||
789680d1 NP |
507 | /** |
508 | * d_drop - drop a dentry | |
509 | * @dentry: dentry to drop | |
510 | * | |
511 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
512 | * be found through a VFS lookup any more. Note that this is different from | |
513 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
514 | * possible, giving a successful _negative_ lookup, while d_drop will | |
515 | * just make the cache lookup fail. | |
516 | * | |
517 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
518 | * reason (NFS timeouts or autofs deletes). | |
519 | * | |
520 | * __d_drop requires dentry->d_lock. | |
521 | */ | |
522 | void __d_drop(struct dentry *dentry) | |
523 | { | |
dea3667b | 524 | if (!d_unhashed(dentry)) { |
c6627c60 | 525 | __d_shrink(dentry); |
dea3667b | 526 | dentry_rcuwalk_barrier(dentry); |
789680d1 NP |
527 | } |
528 | } | |
529 | EXPORT_SYMBOL(__d_drop); | |
530 | ||
531 | void d_drop(struct dentry *dentry) | |
532 | { | |
789680d1 NP |
533 | spin_lock(&dentry->d_lock); |
534 | __d_drop(dentry); | |
535 | spin_unlock(&dentry->d_lock); | |
789680d1 NP |
536 | } |
537 | EXPORT_SYMBOL(d_drop); | |
538 | ||
77812a1e NP |
539 | /* |
540 | * Finish off a dentry we've decided to kill. | |
541 | * dentry->d_lock must be held, returns with it unlocked. | |
542 | * If ref is non-zero, then decrement the refcount too. | |
543 | * Returns dentry requiring refcount drop, or NULL if we're done. | |
544 | */ | |
358eec18 | 545 | static struct dentry * |
dd1f6b2e | 546 | dentry_kill(struct dentry *dentry, int unlock_on_failure) |
77812a1e NP |
547 | __releases(dentry->d_lock) |
548 | { | |
873feea0 | 549 | struct inode *inode; |
77812a1e NP |
550 | struct dentry *parent; |
551 | ||
873feea0 NP |
552 | inode = dentry->d_inode; |
553 | if (inode && !spin_trylock(&inode->i_lock)) { | |
77812a1e | 554 | relock: |
dd1f6b2e DC |
555 | if (unlock_on_failure) { |
556 | spin_unlock(&dentry->d_lock); | |
557 | cpu_relax(); | |
558 | } | |
77812a1e NP |
559 | return dentry; /* try again with same dentry */ |
560 | } | |
561 | if (IS_ROOT(dentry)) | |
562 | parent = NULL; | |
563 | else | |
564 | parent = dentry->d_parent; | |
565 | if (parent && !spin_trylock(&parent->d_lock)) { | |
873feea0 NP |
566 | if (inode) |
567 | spin_unlock(&inode->i_lock); | |
77812a1e NP |
568 | goto relock; |
569 | } | |
31e6b01f | 570 | |
0d98439e LT |
571 | /* |
572 | * The dentry is now unrecoverably dead to the world. | |
573 | */ | |
574 | lockref_mark_dead(&dentry->d_lockref); | |
575 | ||
f0023bc6 | 576 | /* |
f0023bc6 SW |
577 | * inform the fs via d_prune that this dentry is about to be |
578 | * unhashed and destroyed. | |
579 | */ | |
590fb51f | 580 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry)) |
61572bb1 YZ |
581 | dentry->d_op->d_prune(dentry); |
582 | ||
583 | dentry_lru_del(dentry); | |
77812a1e NP |
584 | /* if it was on the hash then remove it */ |
585 | __d_drop(dentry); | |
586 | return d_kill(dentry, parent); | |
587 | } | |
588 | ||
1da177e4 LT |
589 | /* |
590 | * This is dput | |
591 | * | |
592 | * This is complicated by the fact that we do not want to put | |
593 | * dentries that are no longer on any hash chain on the unused | |
594 | * list: we'd much rather just get rid of them immediately. | |
595 | * | |
596 | * However, that implies that we have to traverse the dentry | |
597 | * tree upwards to the parents which might _also_ now be | |
598 | * scheduled for deletion (it may have been only waiting for | |
599 | * its last child to go away). | |
600 | * | |
601 | * This tail recursion is done by hand as we don't want to depend | |
602 | * on the compiler to always get this right (gcc generally doesn't). | |
603 | * Real recursion would eat up our stack space. | |
604 | */ | |
605 | ||
606 | /* | |
607 | * dput - release a dentry | |
608 | * @dentry: dentry to release | |
609 | * | |
610 | * Release a dentry. This will drop the usage count and if appropriate | |
611 | * call the dentry unlink method as well as removing it from the queues and | |
612 | * releasing its resources. If the parent dentries were scheduled for release | |
613 | * they too may now get deleted. | |
1da177e4 | 614 | */ |
1da177e4 LT |
615 | void dput(struct dentry *dentry) |
616 | { | |
8aab6a27 | 617 | if (unlikely(!dentry)) |
1da177e4 LT |
618 | return; |
619 | ||
620 | repeat: | |
98474236 | 621 | if (lockref_put_or_lock(&dentry->d_lockref)) |
1da177e4 | 622 | return; |
1da177e4 | 623 | |
8aab6a27 LT |
624 | /* Unreachable? Get rid of it */ |
625 | if (unlikely(d_unhashed(dentry))) | |
626 | goto kill_it; | |
627 | ||
628 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { | |
1da177e4 | 629 | if (dentry->d_op->d_delete(dentry)) |
61f3dee4 | 630 | goto kill_it; |
1da177e4 | 631 | } |
265ac902 | 632 | |
358eec18 LT |
633 | if (!(dentry->d_flags & DCACHE_REFERENCED)) |
634 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 635 | dentry_lru_add(dentry); |
265ac902 | 636 | |
98474236 | 637 | dentry->d_lockref.count--; |
61f3dee4 | 638 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
639 | return; |
640 | ||
d52b9086 | 641 | kill_it: |
dd1f6b2e | 642 | dentry = dentry_kill(dentry, 1); |
d52b9086 MS |
643 | if (dentry) |
644 | goto repeat; | |
1da177e4 | 645 | } |
ec4f8605 | 646 | EXPORT_SYMBOL(dput); |
1da177e4 LT |
647 | |
648 | /** | |
649 | * d_invalidate - invalidate a dentry | |
650 | * @dentry: dentry to invalidate | |
651 | * | |
652 | * Try to invalidate the dentry if it turns out to be | |
653 | * possible. If there are other dentries that can be | |
654 | * reached through this one we can't delete it and we | |
655 | * return -EBUSY. On success we return 0. | |
656 | * | |
657 | * no dcache lock. | |
658 | */ | |
659 | ||
660 | int d_invalidate(struct dentry * dentry) | |
661 | { | |
662 | /* | |
663 | * If it's already been dropped, return OK. | |
664 | */ | |
da502956 | 665 | spin_lock(&dentry->d_lock); |
1da177e4 | 666 | if (d_unhashed(dentry)) { |
da502956 | 667 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
668 | return 0; |
669 | } | |
670 | /* | |
671 | * Check whether to do a partial shrink_dcache | |
672 | * to get rid of unused child entries. | |
673 | */ | |
674 | if (!list_empty(&dentry->d_subdirs)) { | |
da502956 | 675 | spin_unlock(&dentry->d_lock); |
1da177e4 | 676 | shrink_dcache_parent(dentry); |
da502956 | 677 | spin_lock(&dentry->d_lock); |
1da177e4 LT |
678 | } |
679 | ||
680 | /* | |
681 | * Somebody else still using it? | |
682 | * | |
683 | * If it's a directory, we can't drop it | |
684 | * for fear of somebody re-populating it | |
685 | * with children (even though dropping it | |
686 | * would make it unreachable from the root, | |
687 | * we might still populate it if it was a | |
688 | * working directory or similar). | |
50e69630 AV |
689 | * We also need to leave mountpoints alone, |
690 | * directory or not. | |
1da177e4 | 691 | */ |
98474236 | 692 | if (dentry->d_lockref.count > 1 && dentry->d_inode) { |
50e69630 | 693 | if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) { |
1da177e4 | 694 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
695 | return -EBUSY; |
696 | } | |
697 | } | |
698 | ||
699 | __d_drop(dentry); | |
700 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
701 | return 0; |
702 | } | |
ec4f8605 | 703 | EXPORT_SYMBOL(d_invalidate); |
1da177e4 | 704 | |
b5c84bf6 | 705 | /* This must be called with d_lock held */ |
dc0474be | 706 | static inline void __dget_dlock(struct dentry *dentry) |
23044507 | 707 | { |
98474236 | 708 | dentry->d_lockref.count++; |
23044507 NP |
709 | } |
710 | ||
dc0474be | 711 | static inline void __dget(struct dentry *dentry) |
1da177e4 | 712 | { |
98474236 | 713 | lockref_get(&dentry->d_lockref); |
1da177e4 LT |
714 | } |
715 | ||
b7ab39f6 NP |
716 | struct dentry *dget_parent(struct dentry *dentry) |
717 | { | |
df3d0bbc | 718 | int gotref; |
b7ab39f6 NP |
719 | struct dentry *ret; |
720 | ||
df3d0bbc WL |
721 | /* |
722 | * Do optimistic parent lookup without any | |
723 | * locking. | |
724 | */ | |
725 | rcu_read_lock(); | |
726 | ret = ACCESS_ONCE(dentry->d_parent); | |
727 | gotref = lockref_get_not_zero(&ret->d_lockref); | |
728 | rcu_read_unlock(); | |
729 | if (likely(gotref)) { | |
730 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) | |
731 | return ret; | |
732 | dput(ret); | |
733 | } | |
734 | ||
b7ab39f6 | 735 | repeat: |
a734eb45 NP |
736 | /* |
737 | * Don't need rcu_dereference because we re-check it was correct under | |
738 | * the lock. | |
739 | */ | |
740 | rcu_read_lock(); | |
b7ab39f6 | 741 | ret = dentry->d_parent; |
a734eb45 NP |
742 | spin_lock(&ret->d_lock); |
743 | if (unlikely(ret != dentry->d_parent)) { | |
744 | spin_unlock(&ret->d_lock); | |
745 | rcu_read_unlock(); | |
b7ab39f6 NP |
746 | goto repeat; |
747 | } | |
a734eb45 | 748 | rcu_read_unlock(); |
98474236 WL |
749 | BUG_ON(!ret->d_lockref.count); |
750 | ret->d_lockref.count++; | |
b7ab39f6 | 751 | spin_unlock(&ret->d_lock); |
b7ab39f6 NP |
752 | return ret; |
753 | } | |
754 | EXPORT_SYMBOL(dget_parent); | |
755 | ||
1da177e4 LT |
756 | /** |
757 | * d_find_alias - grab a hashed alias of inode | |
758 | * @inode: inode in question | |
32ba9c3f LT |
759 | * @want_discon: flag, used by d_splice_alias, to request |
760 | * that only a DISCONNECTED alias be returned. | |
1da177e4 LT |
761 | * |
762 | * If inode has a hashed alias, or is a directory and has any alias, | |
763 | * acquire the reference to alias and return it. Otherwise return NULL. | |
764 | * Notice that if inode is a directory there can be only one alias and | |
765 | * it can be unhashed only if it has no children, or if it is the root | |
766 | * of a filesystem. | |
767 | * | |
21c0d8fd | 768 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
32ba9c3f LT |
769 | * any other hashed alias over that one unless @want_discon is set, |
770 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. | |
1da177e4 | 771 | */ |
32ba9c3f | 772 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
1da177e4 | 773 | { |
da502956 | 774 | struct dentry *alias, *discon_alias; |
1da177e4 | 775 | |
da502956 NP |
776 | again: |
777 | discon_alias = NULL; | |
b67bfe0d | 778 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
da502956 | 779 | spin_lock(&alias->d_lock); |
1da177e4 | 780 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
21c0d8fd | 781 | if (IS_ROOT(alias) && |
da502956 | 782 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
1da177e4 | 783 | discon_alias = alias; |
32ba9c3f | 784 | } else if (!want_discon) { |
dc0474be | 785 | __dget_dlock(alias); |
da502956 NP |
786 | spin_unlock(&alias->d_lock); |
787 | return alias; | |
788 | } | |
789 | } | |
790 | spin_unlock(&alias->d_lock); | |
791 | } | |
792 | if (discon_alias) { | |
793 | alias = discon_alias; | |
794 | spin_lock(&alias->d_lock); | |
795 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
796 | if (IS_ROOT(alias) && | |
797 | (alias->d_flags & DCACHE_DISCONNECTED)) { | |
dc0474be | 798 | __dget_dlock(alias); |
da502956 | 799 | spin_unlock(&alias->d_lock); |
1da177e4 LT |
800 | return alias; |
801 | } | |
802 | } | |
da502956 NP |
803 | spin_unlock(&alias->d_lock); |
804 | goto again; | |
1da177e4 | 805 | } |
da502956 | 806 | return NULL; |
1da177e4 LT |
807 | } |
808 | ||
da502956 | 809 | struct dentry *d_find_alias(struct inode *inode) |
1da177e4 | 810 | { |
214fda1f DH |
811 | struct dentry *de = NULL; |
812 | ||
b3d9b7a3 | 813 | if (!hlist_empty(&inode->i_dentry)) { |
873feea0 | 814 | spin_lock(&inode->i_lock); |
32ba9c3f | 815 | de = __d_find_alias(inode, 0); |
873feea0 | 816 | spin_unlock(&inode->i_lock); |
214fda1f | 817 | } |
1da177e4 LT |
818 | return de; |
819 | } | |
ec4f8605 | 820 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
821 | |
822 | /* | |
823 | * Try to kill dentries associated with this inode. | |
824 | * WARNING: you must own a reference to inode. | |
825 | */ | |
826 | void d_prune_aliases(struct inode *inode) | |
827 | { | |
0cdca3f9 | 828 | struct dentry *dentry; |
1da177e4 | 829 | restart: |
873feea0 | 830 | spin_lock(&inode->i_lock); |
b67bfe0d | 831 | hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 | 832 | spin_lock(&dentry->d_lock); |
98474236 | 833 | if (!dentry->d_lockref.count) { |
590fb51f YZ |
834 | /* |
835 | * inform the fs via d_prune that this dentry | |
836 | * is about to be unhashed and destroyed. | |
837 | */ | |
838 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && | |
839 | !d_unhashed(dentry)) | |
840 | dentry->d_op->d_prune(dentry); | |
841 | ||
dc0474be | 842 | __dget_dlock(dentry); |
1da177e4 LT |
843 | __d_drop(dentry); |
844 | spin_unlock(&dentry->d_lock); | |
873feea0 | 845 | spin_unlock(&inode->i_lock); |
1da177e4 LT |
846 | dput(dentry); |
847 | goto restart; | |
848 | } | |
849 | spin_unlock(&dentry->d_lock); | |
850 | } | |
873feea0 | 851 | spin_unlock(&inode->i_lock); |
1da177e4 | 852 | } |
ec4f8605 | 853 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 LT |
854 | |
855 | /* | |
77812a1e NP |
856 | * Try to throw away a dentry - free the inode, dput the parent. |
857 | * Requires dentry->d_lock is held, and dentry->d_count == 0. | |
858 | * Releases dentry->d_lock. | |
d702ccb3 | 859 | * |
77812a1e | 860 | * This may fail if locks cannot be acquired no problem, just try again. |
1da177e4 | 861 | */ |
dd1f6b2e | 862 | static struct dentry * try_prune_one_dentry(struct dentry *dentry) |
31f3e0b3 | 863 | __releases(dentry->d_lock) |
1da177e4 | 864 | { |
77812a1e | 865 | struct dentry *parent; |
d52b9086 | 866 | |
dd1f6b2e | 867 | parent = dentry_kill(dentry, 0); |
d52b9086 | 868 | /* |
77812a1e NP |
869 | * If dentry_kill returns NULL, we have nothing more to do. |
870 | * if it returns the same dentry, trylocks failed. In either | |
871 | * case, just loop again. | |
872 | * | |
873 | * Otherwise, we need to prune ancestors too. This is necessary | |
874 | * to prevent quadratic behavior of shrink_dcache_parent(), but | |
875 | * is also expected to be beneficial in reducing dentry cache | |
876 | * fragmentation. | |
d52b9086 | 877 | */ |
77812a1e | 878 | if (!parent) |
dd1f6b2e | 879 | return NULL; |
77812a1e | 880 | if (parent == dentry) |
dd1f6b2e | 881 | return dentry; |
77812a1e NP |
882 | |
883 | /* Prune ancestors. */ | |
884 | dentry = parent; | |
d52b9086 | 885 | while (dentry) { |
98474236 | 886 | if (lockref_put_or_lock(&dentry->d_lockref)) |
dd1f6b2e DC |
887 | return NULL; |
888 | dentry = dentry_kill(dentry, 1); | |
d52b9086 | 889 | } |
dd1f6b2e | 890 | return NULL; |
1da177e4 LT |
891 | } |
892 | ||
3049cfe2 | 893 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 894 | { |
da3bbdd4 | 895 | struct dentry *dentry; |
da3bbdd4 | 896 | |
ec33679d NP |
897 | rcu_read_lock(); |
898 | for (;;) { | |
ec33679d NP |
899 | dentry = list_entry_rcu(list->prev, struct dentry, d_lru); |
900 | if (&dentry->d_lru == list) | |
901 | break; /* empty */ | |
89dc77bc LT |
902 | |
903 | /* | |
904 | * Get the dentry lock, and re-verify that the dentry is | |
905 | * this on the shrinking list. If it is, we know that | |
906 | * DCACHE_SHRINK_LIST and DCACHE_LRU_LIST are set. | |
907 | */ | |
ec33679d NP |
908 | spin_lock(&dentry->d_lock); |
909 | if (dentry != list_entry(list->prev, struct dentry, d_lru)) { | |
910 | spin_unlock(&dentry->d_lock); | |
23044507 NP |
911 | continue; |
912 | } | |
913 | ||
dd1f6b2e DC |
914 | /* |
915 | * The dispose list is isolated and dentries are not accounted | |
916 | * to the LRU here, so we can simply remove it from the list | |
917 | * here regardless of whether it is referenced or not. | |
918 | */ | |
89dc77bc | 919 | d_shrink_del(dentry); |
dd1f6b2e | 920 | |
1da177e4 LT |
921 | /* |
922 | * We found an inuse dentry which was not removed from | |
dd1f6b2e | 923 | * the LRU because of laziness during lookup. Do not free it. |
1da177e4 | 924 | */ |
98474236 | 925 | if (dentry->d_lockref.count) { |
da3bbdd4 | 926 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
927 | continue; |
928 | } | |
ec33679d | 929 | rcu_read_unlock(); |
77812a1e | 930 | |
89dc77bc LT |
931 | /* |
932 | * If 'try_to_prune()' returns a dentry, it will | |
933 | * be the same one we passed in, and d_lock will | |
934 | * have been held the whole time, so it will not | |
935 | * have been added to any other lists. We failed | |
936 | * to get the inode lock. | |
937 | * | |
938 | * We just add it back to the shrink list. | |
939 | */ | |
dd1f6b2e | 940 | dentry = try_prune_one_dentry(dentry); |
77812a1e | 941 | |
ec33679d | 942 | rcu_read_lock(); |
dd1f6b2e | 943 | if (dentry) { |
89dc77bc | 944 | d_shrink_add(dentry, list); |
dd1f6b2e DC |
945 | spin_unlock(&dentry->d_lock); |
946 | } | |
da3bbdd4 | 947 | } |
ec33679d | 948 | rcu_read_unlock(); |
3049cfe2 CH |
949 | } |
950 | ||
f6041567 DC |
951 | static enum lru_status |
952 | dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) | |
953 | { | |
954 | struct list_head *freeable = arg; | |
955 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
956 | ||
957 | ||
958 | /* | |
959 | * we are inverting the lru lock/dentry->d_lock here, | |
960 | * so use a trylock. If we fail to get the lock, just skip | |
961 | * it | |
962 | */ | |
963 | if (!spin_trylock(&dentry->d_lock)) | |
964 | return LRU_SKIP; | |
965 | ||
966 | /* | |
967 | * Referenced dentries are still in use. If they have active | |
968 | * counts, just remove them from the LRU. Otherwise give them | |
969 | * another pass through the LRU. | |
970 | */ | |
971 | if (dentry->d_lockref.count) { | |
89dc77bc | 972 | d_lru_isolate(dentry); |
f6041567 DC |
973 | spin_unlock(&dentry->d_lock); |
974 | return LRU_REMOVED; | |
975 | } | |
976 | ||
977 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
978 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
979 | spin_unlock(&dentry->d_lock); | |
980 | ||
981 | /* | |
982 | * The list move itself will be made by the common LRU code. At | |
983 | * this point, we've dropped the dentry->d_lock but keep the | |
984 | * lru lock. This is safe to do, since every list movement is | |
985 | * protected by the lru lock even if both locks are held. | |
986 | * | |
987 | * This is guaranteed by the fact that all LRU management | |
988 | * functions are intermediated by the LRU API calls like | |
989 | * list_lru_add and list_lru_del. List movement in this file | |
990 | * only ever occur through this functions or through callbacks | |
991 | * like this one, that are called from the LRU API. | |
992 | * | |
993 | * The only exceptions to this are functions like | |
994 | * shrink_dentry_list, and code that first checks for the | |
995 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be | |
996 | * operating only with stack provided lists after they are | |
997 | * properly isolated from the main list. It is thus, always a | |
998 | * local access. | |
999 | */ | |
1000 | return LRU_ROTATE; | |
1001 | } | |
1002 | ||
89dc77bc | 1003 | d_lru_shrink_move(dentry, freeable); |
f6041567 DC |
1004 | spin_unlock(&dentry->d_lock); |
1005 | ||
1006 | return LRU_REMOVED; | |
1007 | } | |
1008 | ||
3049cfe2 | 1009 | /** |
b48f03b3 DC |
1010 | * prune_dcache_sb - shrink the dcache |
1011 | * @sb: superblock | |
f6041567 | 1012 | * @nr_to_scan : number of entries to try to free |
9b17c623 | 1013 | * @nid: which node to scan for freeable entities |
b48f03b3 | 1014 | * |
f6041567 | 1015 | * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is |
b48f03b3 DC |
1016 | * done when we need more memory an called from the superblock shrinker |
1017 | * function. | |
3049cfe2 | 1018 | * |
b48f03b3 DC |
1019 | * This function may fail to free any resources if all the dentries are in |
1020 | * use. | |
3049cfe2 | 1021 | */ |
9b17c623 DC |
1022 | long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan, |
1023 | int nid) | |
3049cfe2 | 1024 | { |
f6041567 DC |
1025 | LIST_HEAD(dispose); |
1026 | long freed; | |
3049cfe2 | 1027 | |
9b17c623 DC |
1028 | freed = list_lru_walk_node(&sb->s_dentry_lru, nid, dentry_lru_isolate, |
1029 | &dispose, &nr_to_scan); | |
f6041567 | 1030 | shrink_dentry_list(&dispose); |
0a234c6d | 1031 | return freed; |
da3bbdd4 | 1032 | } |
23044507 | 1033 | |
4e717f5c GC |
1034 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
1035 | spinlock_t *lru_lock, void *arg) | |
dd1f6b2e | 1036 | { |
4e717f5c GC |
1037 | struct list_head *freeable = arg; |
1038 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
dd1f6b2e | 1039 | |
4e717f5c GC |
1040 | /* |
1041 | * we are inverting the lru lock/dentry->d_lock here, | |
1042 | * so use a trylock. If we fail to get the lock, just skip | |
1043 | * it | |
1044 | */ | |
1045 | if (!spin_trylock(&dentry->d_lock)) | |
1046 | return LRU_SKIP; | |
1047 | ||
89dc77bc | 1048 | d_lru_shrink_move(dentry, freeable); |
4e717f5c | 1049 | spin_unlock(&dentry->d_lock); |
ec33679d | 1050 | |
4e717f5c | 1051 | return LRU_REMOVED; |
da3bbdd4 KM |
1052 | } |
1053 | ||
4e717f5c | 1054 | |
1da177e4 LT |
1055 | /** |
1056 | * shrink_dcache_sb - shrink dcache for a superblock | |
1057 | * @sb: superblock | |
1058 | * | |
3049cfe2 CH |
1059 | * Shrink the dcache for the specified super block. This is used to free |
1060 | * the dcache before unmounting a file system. | |
1da177e4 | 1061 | */ |
3049cfe2 | 1062 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 1063 | { |
4e717f5c GC |
1064 | long freed; |
1065 | ||
1066 | do { | |
1067 | LIST_HEAD(dispose); | |
1068 | ||
1069 | freed = list_lru_walk(&sb->s_dentry_lru, | |
1070 | dentry_lru_isolate_shrink, &dispose, UINT_MAX); | |
3049cfe2 | 1071 | |
4e717f5c GC |
1072 | this_cpu_sub(nr_dentry_unused, freed); |
1073 | shrink_dentry_list(&dispose); | |
1074 | } while (freed > 0); | |
1da177e4 | 1075 | } |
ec4f8605 | 1076 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 1077 | |
c636ebdb DH |
1078 | /* |
1079 | * destroy a single subtree of dentries for unmount | |
1080 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
1081 | * locking | |
1082 | */ | |
1083 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
1084 | { | |
1085 | struct dentry *parent; | |
1086 | ||
1087 | BUG_ON(!IS_ROOT(dentry)); | |
1088 | ||
c636ebdb DH |
1089 | for (;;) { |
1090 | /* descend to the first leaf in the current subtree */ | |
43c1c9cd | 1091 | while (!list_empty(&dentry->d_subdirs)) |
c636ebdb DH |
1092 | dentry = list_entry(dentry->d_subdirs.next, |
1093 | struct dentry, d_u.d_child); | |
c636ebdb DH |
1094 | |
1095 | /* consume the dentries from this leaf up through its parents | |
1096 | * until we find one with children or run out altogether */ | |
1097 | do { | |
1098 | struct inode *inode; | |
1099 | ||
f0023bc6 | 1100 | /* |
61572bb1 | 1101 | * inform the fs that this dentry is about to be |
f0023bc6 SW |
1102 | * unhashed and destroyed. |
1103 | */ | |
590fb51f YZ |
1104 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && |
1105 | !d_unhashed(dentry)) | |
61572bb1 YZ |
1106 | dentry->d_op->d_prune(dentry); |
1107 | ||
1108 | dentry_lru_del(dentry); | |
43c1c9cd DH |
1109 | __d_shrink(dentry); |
1110 | ||
98474236 | 1111 | if (dentry->d_lockref.count != 0) { |
c636ebdb DH |
1112 | printk(KERN_ERR |
1113 | "BUG: Dentry %p{i=%lx,n=%s}" | |
1114 | " still in use (%d)" | |
1115 | " [unmount of %s %s]\n", | |
1116 | dentry, | |
1117 | dentry->d_inode ? | |
1118 | dentry->d_inode->i_ino : 0UL, | |
1119 | dentry->d_name.name, | |
98474236 | 1120 | dentry->d_lockref.count, |
c636ebdb DH |
1121 | dentry->d_sb->s_type->name, |
1122 | dentry->d_sb->s_id); | |
1123 | BUG(); | |
1124 | } | |
1125 | ||
2fd6b7f5 | 1126 | if (IS_ROOT(dentry)) { |
c636ebdb | 1127 | parent = NULL; |
2fd6b7f5 NP |
1128 | list_del(&dentry->d_u.d_child); |
1129 | } else { | |
871c0067 | 1130 | parent = dentry->d_parent; |
98474236 | 1131 | parent->d_lockref.count--; |
2fd6b7f5 | 1132 | list_del(&dentry->d_u.d_child); |
871c0067 | 1133 | } |
c636ebdb | 1134 | |
c636ebdb DH |
1135 | inode = dentry->d_inode; |
1136 | if (inode) { | |
1137 | dentry->d_inode = NULL; | |
b3d9b7a3 | 1138 | hlist_del_init(&dentry->d_alias); |
c636ebdb DH |
1139 | if (dentry->d_op && dentry->d_op->d_iput) |
1140 | dentry->d_op->d_iput(dentry, inode); | |
1141 | else | |
1142 | iput(inode); | |
1143 | } | |
1144 | ||
1145 | d_free(dentry); | |
1146 | ||
1147 | /* finished when we fall off the top of the tree, | |
1148 | * otherwise we ascend to the parent and move to the | |
1149 | * next sibling if there is one */ | |
1150 | if (!parent) | |
312d3ca8 | 1151 | return; |
c636ebdb | 1152 | dentry = parent; |
c636ebdb DH |
1153 | } while (list_empty(&dentry->d_subdirs)); |
1154 | ||
1155 | dentry = list_entry(dentry->d_subdirs.next, | |
1156 | struct dentry, d_u.d_child); | |
1157 | } | |
1158 | } | |
1159 | ||
1160 | /* | |
1161 | * destroy the dentries attached to a superblock on unmounting | |
b5c84bf6 | 1162 | * - we don't need to use dentry->d_lock because: |
c636ebdb DH |
1163 | * - the superblock is detached from all mountings and open files, so the |
1164 | * dentry trees will not be rearranged by the VFS | |
1165 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
1166 | * any dentries belonging to this superblock that it comes across | |
1167 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
1168 | * in this superblock | |
1169 | */ | |
1170 | void shrink_dcache_for_umount(struct super_block *sb) | |
1171 | { | |
1172 | struct dentry *dentry; | |
1173 | ||
1174 | if (down_read_trylock(&sb->s_umount)) | |
1175 | BUG(); | |
1176 | ||
1177 | dentry = sb->s_root; | |
1178 | sb->s_root = NULL; | |
98474236 | 1179 | dentry->d_lockref.count--; |
c636ebdb DH |
1180 | shrink_dcache_for_umount_subtree(dentry); |
1181 | ||
ceb5bdc2 NP |
1182 | while (!hlist_bl_empty(&sb->s_anon)) { |
1183 | dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); | |
c636ebdb DH |
1184 | shrink_dcache_for_umount_subtree(dentry); |
1185 | } | |
1186 | } | |
1187 | ||
c826cb7d LT |
1188 | /* |
1189 | * This tries to ascend one level of parenthood, but | |
1190 | * we can race with renaming, so we need to re-check | |
1191 | * the parenthood after dropping the lock and check | |
1192 | * that the sequence number still matches. | |
1193 | */ | |
48f5ec21 | 1194 | static struct dentry *try_to_ascend(struct dentry *old, unsigned seq) |
c826cb7d LT |
1195 | { |
1196 | struct dentry *new = old->d_parent; | |
1197 | ||
1198 | rcu_read_lock(); | |
1199 | spin_unlock(&old->d_lock); | |
1200 | spin_lock(&new->d_lock); | |
1201 | ||
1202 | /* | |
1203 | * might go back up the wrong parent if we have had a rename | |
1204 | * or deletion | |
1205 | */ | |
1206 | if (new != old->d_parent || | |
b161dfa6 | 1207 | (old->d_flags & DCACHE_DENTRY_KILLED) || |
48f5ec21 | 1208 | need_seqretry(&rename_lock, seq)) { |
c826cb7d LT |
1209 | spin_unlock(&new->d_lock); |
1210 | new = NULL; | |
1211 | } | |
1212 | rcu_read_unlock(); | |
1213 | return new; | |
1214 | } | |
1215 | ||
db14fc3a MS |
1216 | /** |
1217 | * enum d_walk_ret - action to talke during tree walk | |
1218 | * @D_WALK_CONTINUE: contrinue walk | |
1219 | * @D_WALK_QUIT: quit walk | |
1220 | * @D_WALK_NORETRY: quit when retry is needed | |
1221 | * @D_WALK_SKIP: skip this dentry and its children | |
1222 | */ | |
1223 | enum d_walk_ret { | |
1224 | D_WALK_CONTINUE, | |
1225 | D_WALK_QUIT, | |
1226 | D_WALK_NORETRY, | |
1227 | D_WALK_SKIP, | |
1228 | }; | |
c826cb7d | 1229 | |
1da177e4 | 1230 | /** |
db14fc3a MS |
1231 | * d_walk - walk the dentry tree |
1232 | * @parent: start of walk | |
1233 | * @data: data passed to @enter() and @finish() | |
1234 | * @enter: callback when first entering the dentry | |
1235 | * @finish: callback when successfully finished the walk | |
1da177e4 | 1236 | * |
db14fc3a | 1237 | * The @enter() and @finish() callbacks are called with d_lock held. |
1da177e4 | 1238 | */ |
db14fc3a MS |
1239 | static void d_walk(struct dentry *parent, void *data, |
1240 | enum d_walk_ret (*enter)(void *, struct dentry *), | |
1241 | void (*finish)(void *)) | |
1da177e4 | 1242 | { |
949854d0 | 1243 | struct dentry *this_parent; |
1da177e4 | 1244 | struct list_head *next; |
48f5ec21 | 1245 | unsigned seq = 0; |
db14fc3a MS |
1246 | enum d_walk_ret ret; |
1247 | bool retry = true; | |
949854d0 | 1248 | |
58db63d0 | 1249 | again: |
48f5ec21 | 1250 | read_seqbegin_or_lock(&rename_lock, &seq); |
58db63d0 | 1251 | this_parent = parent; |
2fd6b7f5 | 1252 | spin_lock(&this_parent->d_lock); |
db14fc3a MS |
1253 | |
1254 | ret = enter(data, this_parent); | |
1255 | switch (ret) { | |
1256 | case D_WALK_CONTINUE: | |
1257 | break; | |
1258 | case D_WALK_QUIT: | |
1259 | case D_WALK_SKIP: | |
1260 | goto out_unlock; | |
1261 | case D_WALK_NORETRY: | |
1262 | retry = false; | |
1263 | break; | |
1264 | } | |
1da177e4 LT |
1265 | repeat: |
1266 | next = this_parent->d_subdirs.next; | |
1267 | resume: | |
1268 | while (next != &this_parent->d_subdirs) { | |
1269 | struct list_head *tmp = next; | |
5160ee6f | 1270 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 | 1271 | next = tmp->next; |
2fd6b7f5 NP |
1272 | |
1273 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
db14fc3a MS |
1274 | |
1275 | ret = enter(data, dentry); | |
1276 | switch (ret) { | |
1277 | case D_WALK_CONTINUE: | |
1278 | break; | |
1279 | case D_WALK_QUIT: | |
2fd6b7f5 | 1280 | spin_unlock(&dentry->d_lock); |
db14fc3a MS |
1281 | goto out_unlock; |
1282 | case D_WALK_NORETRY: | |
1283 | retry = false; | |
1284 | break; | |
1285 | case D_WALK_SKIP: | |
1286 | spin_unlock(&dentry->d_lock); | |
1287 | continue; | |
2fd6b7f5 | 1288 | } |
db14fc3a | 1289 | |
1da177e4 | 1290 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
1291 | spin_unlock(&this_parent->d_lock); |
1292 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1293 | this_parent = dentry; |
2fd6b7f5 | 1294 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1295 | goto repeat; |
1296 | } | |
2fd6b7f5 | 1297 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
1298 | } |
1299 | /* | |
1300 | * All done at this level ... ascend and resume the search. | |
1301 | */ | |
1302 | if (this_parent != parent) { | |
c826cb7d | 1303 | struct dentry *child = this_parent; |
48f5ec21 | 1304 | this_parent = try_to_ascend(this_parent, seq); |
c826cb7d | 1305 | if (!this_parent) |
949854d0 | 1306 | goto rename_retry; |
949854d0 | 1307 | next = child->d_u.d_child.next; |
1da177e4 LT |
1308 | goto resume; |
1309 | } | |
48f5ec21 | 1310 | if (need_seqretry(&rename_lock, seq)) { |
db14fc3a | 1311 | spin_unlock(&this_parent->d_lock); |
949854d0 | 1312 | goto rename_retry; |
db14fc3a MS |
1313 | } |
1314 | if (finish) | |
1315 | finish(data); | |
1316 | ||
1317 | out_unlock: | |
1318 | spin_unlock(&this_parent->d_lock); | |
48f5ec21 | 1319 | done_seqretry(&rename_lock, seq); |
db14fc3a | 1320 | return; |
58db63d0 NP |
1321 | |
1322 | rename_retry: | |
db14fc3a MS |
1323 | if (!retry) |
1324 | return; | |
48f5ec21 | 1325 | seq = 1; |
58db63d0 | 1326 | goto again; |
1da177e4 | 1327 | } |
db14fc3a MS |
1328 | |
1329 | /* | |
1330 | * Search for at least 1 mount point in the dentry's subdirs. | |
1331 | * We descend to the next level whenever the d_subdirs | |
1332 | * list is non-empty and continue searching. | |
1333 | */ | |
1334 | ||
db14fc3a MS |
1335 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
1336 | { | |
1337 | int *ret = data; | |
1338 | if (d_mountpoint(dentry)) { | |
1339 | *ret = 1; | |
1340 | return D_WALK_QUIT; | |
1341 | } | |
1342 | return D_WALK_CONTINUE; | |
1343 | } | |
1344 | ||
69c88dc7 RD |
1345 | /** |
1346 | * have_submounts - check for mounts over a dentry | |
1347 | * @parent: dentry to check. | |
1348 | * | |
1349 | * Return true if the parent or its subdirectories contain | |
1350 | * a mount point | |
1351 | */ | |
db14fc3a MS |
1352 | int have_submounts(struct dentry *parent) |
1353 | { | |
1354 | int ret = 0; | |
1355 | ||
1356 | d_walk(parent, &ret, check_mount, NULL); | |
1357 | ||
1358 | return ret; | |
1359 | } | |
ec4f8605 | 1360 | EXPORT_SYMBOL(have_submounts); |
1da177e4 | 1361 | |
eed81007 MS |
1362 | /* |
1363 | * Called by mount code to set a mountpoint and check if the mountpoint is | |
1364 | * reachable (e.g. NFS can unhash a directory dentry and then the complete | |
1365 | * subtree can become unreachable). | |
1366 | * | |
1367 | * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For | |
1368 | * this reason take rename_lock and d_lock on dentry and ancestors. | |
1369 | */ | |
1370 | int d_set_mounted(struct dentry *dentry) | |
1371 | { | |
1372 | struct dentry *p; | |
1373 | int ret = -ENOENT; | |
1374 | write_seqlock(&rename_lock); | |
1375 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { | |
1376 | /* Need exclusion wrt. check_submounts_and_drop() */ | |
1377 | spin_lock(&p->d_lock); | |
1378 | if (unlikely(d_unhashed(p))) { | |
1379 | spin_unlock(&p->d_lock); | |
1380 | goto out; | |
1381 | } | |
1382 | spin_unlock(&p->d_lock); | |
1383 | } | |
1384 | spin_lock(&dentry->d_lock); | |
1385 | if (!d_unlinked(dentry)) { | |
1386 | dentry->d_flags |= DCACHE_MOUNTED; | |
1387 | ret = 0; | |
1388 | } | |
1389 | spin_unlock(&dentry->d_lock); | |
1390 | out: | |
1391 | write_sequnlock(&rename_lock); | |
1392 | return ret; | |
1393 | } | |
1394 | ||
1da177e4 | 1395 | /* |
fd517909 | 1396 | * Search the dentry child list of the specified parent, |
1da177e4 LT |
1397 | * and move any unused dentries to the end of the unused |
1398 | * list for prune_dcache(). We descend to the next level | |
1399 | * whenever the d_subdirs list is non-empty and continue | |
1400 | * searching. | |
1401 | * | |
1402 | * It returns zero iff there are no unused children, | |
1403 | * otherwise it returns the number of children moved to | |
1404 | * the end of the unused list. This may not be the total | |
1405 | * number of unused children, because select_parent can | |
1406 | * drop the lock and return early due to latency | |
1407 | * constraints. | |
1408 | */ | |
1da177e4 | 1409 | |
db14fc3a MS |
1410 | struct select_data { |
1411 | struct dentry *start; | |
1412 | struct list_head dispose; | |
1413 | int found; | |
1414 | }; | |
23044507 | 1415 | |
db14fc3a MS |
1416 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
1417 | { | |
1418 | struct select_data *data = _data; | |
1419 | enum d_walk_ret ret = D_WALK_CONTINUE; | |
1da177e4 | 1420 | |
db14fc3a MS |
1421 | if (data->start == dentry) |
1422 | goto out; | |
2fd6b7f5 | 1423 | |
1da177e4 | 1424 | /* |
db14fc3a MS |
1425 | * move only zero ref count dentries to the dispose list. |
1426 | * | |
1427 | * Those which are presently on the shrink list, being processed | |
1428 | * by shrink_dentry_list(), shouldn't be moved. Otherwise the | |
1429 | * loop in shrink_dcache_parent() might not make any progress | |
1430 | * and loop forever. | |
1da177e4 | 1431 | */ |
db14fc3a MS |
1432 | if (dentry->d_lockref.count) { |
1433 | dentry_lru_del(dentry); | |
1434 | } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { | |
89dc77bc LT |
1435 | /* |
1436 | * We can't use d_lru_shrink_move() because we | |
1437 | * need to get the global LRU lock and do the | |
05a8252b | 1438 | * LRU accounting. |
89dc77bc LT |
1439 | */ |
1440 | d_lru_del(dentry); | |
1441 | d_shrink_add(dentry, &data->dispose); | |
db14fc3a MS |
1442 | data->found++; |
1443 | ret = D_WALK_NORETRY; | |
1da177e4 | 1444 | } |
db14fc3a MS |
1445 | /* |
1446 | * We can return to the caller if we have found some (this | |
1447 | * ensures forward progress). We'll be coming back to find | |
1448 | * the rest. | |
1449 | */ | |
1450 | if (data->found && need_resched()) | |
1451 | ret = D_WALK_QUIT; | |
1da177e4 | 1452 | out: |
db14fc3a | 1453 | return ret; |
1da177e4 LT |
1454 | } |
1455 | ||
1456 | /** | |
1457 | * shrink_dcache_parent - prune dcache | |
1458 | * @parent: parent of entries to prune | |
1459 | * | |
1460 | * Prune the dcache to remove unused children of the parent dentry. | |
1461 | */ | |
db14fc3a | 1462 | void shrink_dcache_parent(struct dentry *parent) |
1da177e4 | 1463 | { |
db14fc3a MS |
1464 | for (;;) { |
1465 | struct select_data data; | |
1da177e4 | 1466 | |
db14fc3a MS |
1467 | INIT_LIST_HEAD(&data.dispose); |
1468 | data.start = parent; | |
1469 | data.found = 0; | |
1470 | ||
1471 | d_walk(parent, &data, select_collect, NULL); | |
1472 | if (!data.found) | |
1473 | break; | |
1474 | ||
1475 | shrink_dentry_list(&data.dispose); | |
421348f1 GT |
1476 | cond_resched(); |
1477 | } | |
1da177e4 | 1478 | } |
ec4f8605 | 1479 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1480 | |
848ac114 MS |
1481 | static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry) |
1482 | { | |
1483 | struct select_data *data = _data; | |
1484 | ||
1485 | if (d_mountpoint(dentry)) { | |
1486 | data->found = -EBUSY; | |
1487 | return D_WALK_QUIT; | |
1488 | } | |
1489 | ||
1490 | return select_collect(_data, dentry); | |
1491 | } | |
1492 | ||
1493 | static void check_and_drop(void *_data) | |
1494 | { | |
1495 | struct select_data *data = _data; | |
1496 | ||
1497 | if (d_mountpoint(data->start)) | |
1498 | data->found = -EBUSY; | |
1499 | if (!data->found) | |
1500 | __d_drop(data->start); | |
1501 | } | |
1502 | ||
1503 | /** | |
1504 | * check_submounts_and_drop - prune dcache, check for submounts and drop | |
1505 | * | |
1506 | * All done as a single atomic operation relative to has_unlinked_ancestor(). | |
1507 | * Returns 0 if successfully unhashed @parent. If there were submounts then | |
1508 | * return -EBUSY. | |
1509 | * | |
1510 | * @dentry: dentry to prune and drop | |
1511 | */ | |
1512 | int check_submounts_and_drop(struct dentry *dentry) | |
1513 | { | |
1514 | int ret = 0; | |
1515 | ||
1516 | /* Negative dentries can be dropped without further checks */ | |
1517 | if (!dentry->d_inode) { | |
1518 | d_drop(dentry); | |
1519 | goto out; | |
1520 | } | |
1521 | ||
1522 | for (;;) { | |
1523 | struct select_data data; | |
1524 | ||
1525 | INIT_LIST_HEAD(&data.dispose); | |
1526 | data.start = dentry; | |
1527 | data.found = 0; | |
1528 | ||
1529 | d_walk(dentry, &data, check_and_collect, check_and_drop); | |
1530 | ret = data.found; | |
1531 | ||
1532 | if (!list_empty(&data.dispose)) | |
1533 | shrink_dentry_list(&data.dispose); | |
1534 | ||
1535 | if (ret <= 0) | |
1536 | break; | |
1537 | ||
1538 | cond_resched(); | |
1539 | } | |
1540 | ||
1541 | out: | |
1542 | return ret; | |
1543 | } | |
1544 | EXPORT_SYMBOL(check_submounts_and_drop); | |
1545 | ||
1da177e4 | 1546 | /** |
a4464dbc AV |
1547 | * __d_alloc - allocate a dcache entry |
1548 | * @sb: filesystem it will belong to | |
1da177e4 LT |
1549 | * @name: qstr of the name |
1550 | * | |
1551 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1552 | * available. On a success the dentry is returned. The name passed in is | |
1553 | * copied and the copy passed in may be reused after this call. | |
1554 | */ | |
1555 | ||
a4464dbc | 1556 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1da177e4 LT |
1557 | { |
1558 | struct dentry *dentry; | |
1559 | char *dname; | |
1560 | ||
e12ba74d | 1561 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1562 | if (!dentry) |
1563 | return NULL; | |
1564 | ||
6326c71f LT |
1565 | /* |
1566 | * We guarantee that the inline name is always NUL-terminated. | |
1567 | * This way the memcpy() done by the name switching in rename | |
1568 | * will still always have a NUL at the end, even if we might | |
1569 | * be overwriting an internal NUL character | |
1570 | */ | |
1571 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; | |
1da177e4 LT |
1572 | if (name->len > DNAME_INLINE_LEN-1) { |
1573 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
1574 | if (!dname) { | |
1575 | kmem_cache_free(dentry_cache, dentry); | |
1576 | return NULL; | |
1577 | } | |
1578 | } else { | |
1579 | dname = dentry->d_iname; | |
1580 | } | |
1da177e4 LT |
1581 | |
1582 | dentry->d_name.len = name->len; | |
1583 | dentry->d_name.hash = name->hash; | |
1584 | memcpy(dname, name->name, name->len); | |
1585 | dname[name->len] = 0; | |
1586 | ||
6326c71f LT |
1587 | /* Make sure we always see the terminating NUL character */ |
1588 | smp_wmb(); | |
1589 | dentry->d_name.name = dname; | |
1590 | ||
98474236 | 1591 | dentry->d_lockref.count = 1; |
dea3667b | 1592 | dentry->d_flags = 0; |
1da177e4 | 1593 | spin_lock_init(&dentry->d_lock); |
31e6b01f | 1594 | seqcount_init(&dentry->d_seq); |
1da177e4 | 1595 | dentry->d_inode = NULL; |
a4464dbc AV |
1596 | dentry->d_parent = dentry; |
1597 | dentry->d_sb = sb; | |
1da177e4 LT |
1598 | dentry->d_op = NULL; |
1599 | dentry->d_fsdata = NULL; | |
ceb5bdc2 | 1600 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1da177e4 LT |
1601 | INIT_LIST_HEAD(&dentry->d_lru); |
1602 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
b3d9b7a3 | 1603 | INIT_HLIST_NODE(&dentry->d_alias); |
2fd6b7f5 | 1604 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
a4464dbc | 1605 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1da177e4 | 1606 | |
3e880fb5 | 1607 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1608 | |
1da177e4 LT |
1609 | return dentry; |
1610 | } | |
a4464dbc AV |
1611 | |
1612 | /** | |
1613 | * d_alloc - allocate a dcache entry | |
1614 | * @parent: parent of entry to allocate | |
1615 | * @name: qstr of the name | |
1616 | * | |
1617 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1618 | * available. On a success the dentry is returned. The name passed in is | |
1619 | * copied and the copy passed in may be reused after this call. | |
1620 | */ | |
1621 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1622 | { | |
1623 | struct dentry *dentry = __d_alloc(parent->d_sb, name); | |
1624 | if (!dentry) | |
1625 | return NULL; | |
1626 | ||
1627 | spin_lock(&parent->d_lock); | |
1628 | /* | |
1629 | * don't need child lock because it is not subject | |
1630 | * to concurrency here | |
1631 | */ | |
1632 | __dget_dlock(parent); | |
1633 | dentry->d_parent = parent; | |
1634 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); | |
1635 | spin_unlock(&parent->d_lock); | |
1636 | ||
1637 | return dentry; | |
1638 | } | |
ec4f8605 | 1639 | EXPORT_SYMBOL(d_alloc); |
1da177e4 | 1640 | |
4b936885 NP |
1641 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1642 | { | |
a4464dbc AV |
1643 | struct dentry *dentry = __d_alloc(sb, name); |
1644 | if (dentry) | |
4b936885 | 1645 | dentry->d_flags |= DCACHE_DISCONNECTED; |
4b936885 NP |
1646 | return dentry; |
1647 | } | |
1648 | EXPORT_SYMBOL(d_alloc_pseudo); | |
1649 | ||
1da177e4 LT |
1650 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1651 | { | |
1652 | struct qstr q; | |
1653 | ||
1654 | q.name = name; | |
1655 | q.len = strlen(name); | |
1656 | q.hash = full_name_hash(q.name, q.len); | |
1657 | return d_alloc(parent, &q); | |
1658 | } | |
ef26ca97 | 1659 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1660 | |
fb045adb NP |
1661 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1662 | { | |
6f7f7caa LT |
1663 | WARN_ON_ONCE(dentry->d_op); |
1664 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | | |
fb045adb NP |
1665 | DCACHE_OP_COMPARE | |
1666 | DCACHE_OP_REVALIDATE | | |
ecf3d1f1 | 1667 | DCACHE_OP_WEAK_REVALIDATE | |
fb045adb NP |
1668 | DCACHE_OP_DELETE )); |
1669 | dentry->d_op = op; | |
1670 | if (!op) | |
1671 | return; | |
1672 | if (op->d_hash) | |
1673 | dentry->d_flags |= DCACHE_OP_HASH; | |
1674 | if (op->d_compare) | |
1675 | dentry->d_flags |= DCACHE_OP_COMPARE; | |
1676 | if (op->d_revalidate) | |
1677 | dentry->d_flags |= DCACHE_OP_REVALIDATE; | |
ecf3d1f1 JL |
1678 | if (op->d_weak_revalidate) |
1679 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; | |
fb045adb NP |
1680 | if (op->d_delete) |
1681 | dentry->d_flags |= DCACHE_OP_DELETE; | |
f0023bc6 SW |
1682 | if (op->d_prune) |
1683 | dentry->d_flags |= DCACHE_OP_PRUNE; | |
fb045adb NP |
1684 | |
1685 | } | |
1686 | EXPORT_SYMBOL(d_set_d_op); | |
1687 | ||
360da900 OH |
1688 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1689 | { | |
b23fb0a6 | 1690 | spin_lock(&dentry->d_lock); |
9875cf80 DH |
1691 | if (inode) { |
1692 | if (unlikely(IS_AUTOMOUNT(inode))) | |
1693 | dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; | |
b3d9b7a3 | 1694 | hlist_add_head(&dentry->d_alias, &inode->i_dentry); |
9875cf80 | 1695 | } |
360da900 | 1696 | dentry->d_inode = inode; |
31e6b01f | 1697 | dentry_rcuwalk_barrier(dentry); |
b23fb0a6 | 1698 | spin_unlock(&dentry->d_lock); |
360da900 OH |
1699 | fsnotify_d_instantiate(dentry, inode); |
1700 | } | |
1701 | ||
1da177e4 LT |
1702 | /** |
1703 | * d_instantiate - fill in inode information for a dentry | |
1704 | * @entry: dentry to complete | |
1705 | * @inode: inode to attach to this dentry | |
1706 | * | |
1707 | * Fill in inode information in the entry. | |
1708 | * | |
1709 | * This turns negative dentries into productive full members | |
1710 | * of society. | |
1711 | * | |
1712 | * NOTE! This assumes that the inode count has been incremented | |
1713 | * (or otherwise set) by the caller to indicate that it is now | |
1714 | * in use by the dcache. | |
1715 | */ | |
1716 | ||
1717 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1718 | { | |
b3d9b7a3 | 1719 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
873feea0 NP |
1720 | if (inode) |
1721 | spin_lock(&inode->i_lock); | |
360da900 | 1722 | __d_instantiate(entry, inode); |
873feea0 NP |
1723 | if (inode) |
1724 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
1725 | security_d_instantiate(entry, inode); |
1726 | } | |
ec4f8605 | 1727 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 LT |
1728 | |
1729 | /** | |
1730 | * d_instantiate_unique - instantiate a non-aliased dentry | |
1731 | * @entry: dentry to instantiate | |
1732 | * @inode: inode to attach to this dentry | |
1733 | * | |
1734 | * Fill in inode information in the entry. On success, it returns NULL. | |
1735 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 1736 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1737 | * |
1738 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1739 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1740 | * |
1741 | * This also assumes that the inode count has been incremented | |
1742 | * (or otherwise set) by the caller to indicate that it is now | |
1743 | * in use by the dcache. | |
1da177e4 | 1744 | */ |
770bfad8 DH |
1745 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1746 | struct inode *inode) | |
1da177e4 LT |
1747 | { |
1748 | struct dentry *alias; | |
1749 | int len = entry->d_name.len; | |
1750 | const char *name = entry->d_name.name; | |
1751 | unsigned int hash = entry->d_name.hash; | |
1752 | ||
770bfad8 | 1753 | if (!inode) { |
360da900 | 1754 | __d_instantiate(entry, NULL); |
770bfad8 DH |
1755 | return NULL; |
1756 | } | |
1757 | ||
b67bfe0d | 1758 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
9abca360 NP |
1759 | /* |
1760 | * Don't need alias->d_lock here, because aliases with | |
1761 | * d_parent == entry->d_parent are not subject to name or | |
1762 | * parent changes, because the parent inode i_mutex is held. | |
1763 | */ | |
12f8ad4b | 1764 | if (alias->d_name.hash != hash) |
1da177e4 LT |
1765 | continue; |
1766 | if (alias->d_parent != entry->d_parent) | |
1767 | continue; | |
ee983e89 LT |
1768 | if (alias->d_name.len != len) |
1769 | continue; | |
12f8ad4b | 1770 | if (dentry_cmp(alias, name, len)) |
1da177e4 | 1771 | continue; |
dc0474be | 1772 | __dget(alias); |
1da177e4 LT |
1773 | return alias; |
1774 | } | |
770bfad8 | 1775 | |
360da900 | 1776 | __d_instantiate(entry, inode); |
1da177e4 LT |
1777 | return NULL; |
1778 | } | |
770bfad8 DH |
1779 | |
1780 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1781 | { | |
1782 | struct dentry *result; | |
1783 | ||
b3d9b7a3 | 1784 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
770bfad8 | 1785 | |
873feea0 NP |
1786 | if (inode) |
1787 | spin_lock(&inode->i_lock); | |
770bfad8 | 1788 | result = __d_instantiate_unique(entry, inode); |
873feea0 NP |
1789 | if (inode) |
1790 | spin_unlock(&inode->i_lock); | |
770bfad8 DH |
1791 | |
1792 | if (!result) { | |
1793 | security_d_instantiate(entry, inode); | |
1794 | return NULL; | |
1795 | } | |
1796 | ||
1797 | BUG_ON(!d_unhashed(result)); | |
1798 | iput(inode); | |
1799 | return result; | |
1800 | } | |
1801 | ||
1da177e4 LT |
1802 | EXPORT_SYMBOL(d_instantiate_unique); |
1803 | ||
adc0e91a AV |
1804 | struct dentry *d_make_root(struct inode *root_inode) |
1805 | { | |
1806 | struct dentry *res = NULL; | |
1807 | ||
1808 | if (root_inode) { | |
26fe5750 | 1809 | static const struct qstr name = QSTR_INIT("/", 1); |
adc0e91a AV |
1810 | |
1811 | res = __d_alloc(root_inode->i_sb, &name); | |
1812 | if (res) | |
1813 | d_instantiate(res, root_inode); | |
1814 | else | |
1815 | iput(root_inode); | |
1816 | } | |
1817 | return res; | |
1818 | } | |
1819 | EXPORT_SYMBOL(d_make_root); | |
1820 | ||
d891eedb BF |
1821 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1822 | { | |
1823 | struct dentry *alias; | |
1824 | ||
b3d9b7a3 | 1825 | if (hlist_empty(&inode->i_dentry)) |
d891eedb | 1826 | return NULL; |
b3d9b7a3 | 1827 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias); |
d891eedb BF |
1828 | __dget(alias); |
1829 | return alias; | |
1830 | } | |
1831 | ||
46f72b34 SW |
1832 | /** |
1833 | * d_find_any_alias - find any alias for a given inode | |
1834 | * @inode: inode to find an alias for | |
1835 | * | |
1836 | * If any aliases exist for the given inode, take and return a | |
1837 | * reference for one of them. If no aliases exist, return %NULL. | |
1838 | */ | |
1839 | struct dentry *d_find_any_alias(struct inode *inode) | |
d891eedb BF |
1840 | { |
1841 | struct dentry *de; | |
1842 | ||
1843 | spin_lock(&inode->i_lock); | |
1844 | de = __d_find_any_alias(inode); | |
1845 | spin_unlock(&inode->i_lock); | |
1846 | return de; | |
1847 | } | |
46f72b34 | 1848 | EXPORT_SYMBOL(d_find_any_alias); |
d891eedb | 1849 | |
4ea3ada2 CH |
1850 | /** |
1851 | * d_obtain_alias - find or allocate a dentry for a given inode | |
1852 | * @inode: inode to allocate the dentry for | |
1853 | * | |
1854 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1855 | * similar open by handle operations. The returned dentry may be anonymous, | |
1856 | * or may have a full name (if the inode was already in the cache). | |
1857 | * | |
1858 | * When called on a directory inode, we must ensure that the inode only ever | |
1859 | * has one dentry. If a dentry is found, that is returned instead of | |
1860 | * allocating a new one. | |
1861 | * | |
1862 | * On successful return, the reference to the inode has been transferred | |
44003728 CH |
1863 | * to the dentry. In case of an error the reference on the inode is released. |
1864 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1865 | * be passed in and will be the error will be propagate to the return value, | |
1866 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
4ea3ada2 CH |
1867 | */ |
1868 | struct dentry *d_obtain_alias(struct inode *inode) | |
1869 | { | |
b911a6bd | 1870 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
9308a612 CH |
1871 | struct dentry *tmp; |
1872 | struct dentry *res; | |
4ea3ada2 CH |
1873 | |
1874 | if (!inode) | |
44003728 | 1875 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1876 | if (IS_ERR(inode)) |
1877 | return ERR_CAST(inode); | |
1878 | ||
d891eedb | 1879 | res = d_find_any_alias(inode); |
9308a612 CH |
1880 | if (res) |
1881 | goto out_iput; | |
1882 | ||
a4464dbc | 1883 | tmp = __d_alloc(inode->i_sb, &anonstring); |
9308a612 CH |
1884 | if (!tmp) { |
1885 | res = ERR_PTR(-ENOMEM); | |
1886 | goto out_iput; | |
4ea3ada2 | 1887 | } |
b5c84bf6 | 1888 | |
873feea0 | 1889 | spin_lock(&inode->i_lock); |
d891eedb | 1890 | res = __d_find_any_alias(inode); |
9308a612 | 1891 | if (res) { |
873feea0 | 1892 | spin_unlock(&inode->i_lock); |
9308a612 CH |
1893 | dput(tmp); |
1894 | goto out_iput; | |
1895 | } | |
1896 | ||
1897 | /* attach a disconnected dentry */ | |
1898 | spin_lock(&tmp->d_lock); | |
9308a612 CH |
1899 | tmp->d_inode = inode; |
1900 | tmp->d_flags |= DCACHE_DISCONNECTED; | |
b3d9b7a3 | 1901 | hlist_add_head(&tmp->d_alias, &inode->i_dentry); |
1879fd6a | 1902 | hlist_bl_lock(&tmp->d_sb->s_anon); |
ceb5bdc2 | 1903 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1879fd6a | 1904 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
9308a612 | 1905 | spin_unlock(&tmp->d_lock); |
873feea0 | 1906 | spin_unlock(&inode->i_lock); |
24ff6663 | 1907 | security_d_instantiate(tmp, inode); |
9308a612 | 1908 | |
9308a612 CH |
1909 | return tmp; |
1910 | ||
1911 | out_iput: | |
24ff6663 JB |
1912 | if (res && !IS_ERR(res)) |
1913 | security_d_instantiate(res, inode); | |
9308a612 CH |
1914 | iput(inode); |
1915 | return res; | |
4ea3ada2 | 1916 | } |
adc48720 | 1917 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 LT |
1918 | |
1919 | /** | |
1920 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1921 | * @inode: the inode which may have a disconnected dentry | |
1922 | * @dentry: a negative dentry which we want to point to the inode. | |
1923 | * | |
1924 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1925 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1926 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1927 | * | |
1928 | * This is needed in the lookup routine of any filesystem that is exportable | |
1929 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1930 | * | |
1931 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1932 | * is returned. This matches the expected return value of ->lookup. | |
1933 | * | |
6d4ade98 SW |
1934 | * Cluster filesystems may call this function with a negative, hashed dentry. |
1935 | * In that case, we know that the inode will be a regular file, and also this | |
1936 | * will only occur during atomic_open. So we need to check for the dentry | |
1937 | * being already hashed only in the final case. | |
1da177e4 LT |
1938 | */ |
1939 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1940 | { | |
1941 | struct dentry *new = NULL; | |
1942 | ||
a9049376 AV |
1943 | if (IS_ERR(inode)) |
1944 | return ERR_CAST(inode); | |
1945 | ||
21c0d8fd | 1946 | if (inode && S_ISDIR(inode->i_mode)) { |
873feea0 | 1947 | spin_lock(&inode->i_lock); |
32ba9c3f | 1948 | new = __d_find_alias(inode, 1); |
1da177e4 | 1949 | if (new) { |
32ba9c3f | 1950 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
873feea0 | 1951 | spin_unlock(&inode->i_lock); |
1da177e4 | 1952 | security_d_instantiate(new, inode); |
1da177e4 LT |
1953 | d_move(new, dentry); |
1954 | iput(inode); | |
1955 | } else { | |
873feea0 | 1956 | /* already taking inode->i_lock, so d_add() by hand */ |
360da900 | 1957 | __d_instantiate(dentry, inode); |
873feea0 | 1958 | spin_unlock(&inode->i_lock); |
1da177e4 LT |
1959 | security_d_instantiate(dentry, inode); |
1960 | d_rehash(dentry); | |
1961 | } | |
6d4ade98 SW |
1962 | } else { |
1963 | d_instantiate(dentry, inode); | |
1964 | if (d_unhashed(dentry)) | |
1965 | d_rehash(dentry); | |
1966 | } | |
1da177e4 LT |
1967 | return new; |
1968 | } | |
ec4f8605 | 1969 | EXPORT_SYMBOL(d_splice_alias); |
1da177e4 | 1970 | |
9403540c BN |
1971 | /** |
1972 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
1973 | * @inode: the inode case-insensitive lookup has found | |
1974 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
1975 | * @name: the case-exact name to be associated with the returned dentry | |
1976 | * | |
1977 | * This is to avoid filling the dcache with case-insensitive names to the | |
1978 | * same inode, only the actual correct case is stored in the dcache for | |
1979 | * case-insensitive filesystems. | |
1980 | * | |
1981 | * For a case-insensitive lookup match and if the the case-exact dentry | |
1982 | * already exists in in the dcache, use it and return it. | |
1983 | * | |
1984 | * If no entry exists with the exact case name, allocate new dentry with | |
1985 | * the exact case, and return the spliced entry. | |
1986 | */ | |
e45b590b | 1987 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
1988 | struct qstr *name) |
1989 | { | |
9403540c BN |
1990 | struct dentry *found; |
1991 | struct dentry *new; | |
1992 | ||
b6520c81 CH |
1993 | /* |
1994 | * First check if a dentry matching the name already exists, | |
1995 | * if not go ahead and create it now. | |
1996 | */ | |
9403540c | 1997 | found = d_hash_and_lookup(dentry->d_parent, name); |
4f522a24 AV |
1998 | if (unlikely(IS_ERR(found))) |
1999 | goto err_out; | |
9403540c BN |
2000 | if (!found) { |
2001 | new = d_alloc(dentry->d_parent, name); | |
2002 | if (!new) { | |
4f522a24 | 2003 | found = ERR_PTR(-ENOMEM); |
9403540c BN |
2004 | goto err_out; |
2005 | } | |
b6520c81 | 2006 | |
9403540c BN |
2007 | found = d_splice_alias(inode, new); |
2008 | if (found) { | |
2009 | dput(new); | |
2010 | return found; | |
2011 | } | |
2012 | return new; | |
2013 | } | |
b6520c81 CH |
2014 | |
2015 | /* | |
2016 | * If a matching dentry exists, and it's not negative use it. | |
2017 | * | |
2018 | * Decrement the reference count to balance the iget() done | |
2019 | * earlier on. | |
2020 | */ | |
9403540c BN |
2021 | if (found->d_inode) { |
2022 | if (unlikely(found->d_inode != inode)) { | |
2023 | /* This can't happen because bad inodes are unhashed. */ | |
2024 | BUG_ON(!is_bad_inode(inode)); | |
2025 | BUG_ON(!is_bad_inode(found->d_inode)); | |
2026 | } | |
9403540c BN |
2027 | iput(inode); |
2028 | return found; | |
2029 | } | |
b6520c81 | 2030 | |
9403540c | 2031 | /* |
9403540c | 2032 | * Negative dentry: instantiate it unless the inode is a directory and |
b6520c81 | 2033 | * already has a dentry. |
9403540c | 2034 | */ |
4513d899 AV |
2035 | new = d_splice_alias(inode, found); |
2036 | if (new) { | |
2037 | dput(found); | |
2038 | found = new; | |
9403540c | 2039 | } |
4513d899 | 2040 | return found; |
9403540c BN |
2041 | |
2042 | err_out: | |
2043 | iput(inode); | |
4f522a24 | 2044 | return found; |
9403540c | 2045 | } |
ec4f8605 | 2046 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 | 2047 | |
12f8ad4b LT |
2048 | /* |
2049 | * Do the slow-case of the dentry name compare. | |
2050 | * | |
2051 | * Unlike the dentry_cmp() function, we need to atomically | |
da53be12 | 2052 | * load the name and length information, so that the |
12f8ad4b LT |
2053 | * filesystem can rely on them, and can use the 'name' and |
2054 | * 'len' information without worrying about walking off the | |
2055 | * end of memory etc. | |
2056 | * | |
2057 | * Thus the read_seqcount_retry() and the "duplicate" info | |
2058 | * in arguments (the low-level filesystem should not look | |
2059 | * at the dentry inode or name contents directly, since | |
2060 | * rename can change them while we're in RCU mode). | |
2061 | */ | |
2062 | enum slow_d_compare { | |
2063 | D_COMP_OK, | |
2064 | D_COMP_NOMATCH, | |
2065 | D_COMP_SEQRETRY, | |
2066 | }; | |
2067 | ||
2068 | static noinline enum slow_d_compare slow_dentry_cmp( | |
2069 | const struct dentry *parent, | |
12f8ad4b LT |
2070 | struct dentry *dentry, |
2071 | unsigned int seq, | |
2072 | const struct qstr *name) | |
2073 | { | |
2074 | int tlen = dentry->d_name.len; | |
2075 | const char *tname = dentry->d_name.name; | |
12f8ad4b LT |
2076 | |
2077 | if (read_seqcount_retry(&dentry->d_seq, seq)) { | |
2078 | cpu_relax(); | |
2079 | return D_COMP_SEQRETRY; | |
2080 | } | |
da53be12 | 2081 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
12f8ad4b LT |
2082 | return D_COMP_NOMATCH; |
2083 | return D_COMP_OK; | |
2084 | } | |
2085 | ||
31e6b01f NP |
2086 | /** |
2087 | * __d_lookup_rcu - search for a dentry (racy, store-free) | |
2088 | * @parent: parent dentry | |
2089 | * @name: qstr of name we wish to find | |
1f1e6e52 | 2090 | * @seqp: returns d_seq value at the point where the dentry was found |
31e6b01f NP |
2091 | * Returns: dentry, or NULL |
2092 | * | |
2093 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name | |
2094 | * resolution (store-free path walking) design described in | |
2095 | * Documentation/filesystems/path-lookup.txt. | |
2096 | * | |
2097 | * This is not to be used outside core vfs. | |
2098 | * | |
2099 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock | |
2100 | * held, and rcu_read_lock held. The returned dentry must not be stored into | |
2101 | * without taking d_lock and checking d_seq sequence count against @seq | |
2102 | * returned here. | |
2103 | * | |
15570086 | 2104 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
31e6b01f NP |
2105 | * function. |
2106 | * | |
2107 | * Alternatively, __d_lookup_rcu may be called again to look up the child of | |
2108 | * the returned dentry, so long as its parent's seqlock is checked after the | |
2109 | * child is looked up. Thus, an interlocking stepping of sequence lock checks | |
2110 | * is formed, giving integrity down the path walk. | |
12f8ad4b LT |
2111 | * |
2112 | * NOTE! The caller *has* to check the resulting dentry against the sequence | |
2113 | * number we've returned before using any of the resulting dentry state! | |
31e6b01f | 2114 | */ |
8966be90 LT |
2115 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
2116 | const struct qstr *name, | |
da53be12 | 2117 | unsigned *seqp) |
31e6b01f | 2118 | { |
26fe5750 | 2119 | u64 hashlen = name->hash_len; |
31e6b01f | 2120 | const unsigned char *str = name->name; |
26fe5750 | 2121 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
ceb5bdc2 | 2122 | struct hlist_bl_node *node; |
31e6b01f NP |
2123 | struct dentry *dentry; |
2124 | ||
2125 | /* | |
2126 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2127 | * required to prevent single threaded performance regressions | |
2128 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2129 | * Keep the two functions in sync. | |
2130 | */ | |
2131 | ||
2132 | /* | |
2133 | * The hash list is protected using RCU. | |
2134 | * | |
2135 | * Carefully use d_seq when comparing a candidate dentry, to avoid | |
2136 | * races with d_move(). | |
2137 | * | |
2138 | * It is possible that concurrent renames can mess up our list | |
2139 | * walk here and result in missing our dentry, resulting in the | |
2140 | * false-negative result. d_lookup() protects against concurrent | |
2141 | * renames using rename_lock seqlock. | |
2142 | * | |
b0a4bb83 | 2143 | * See Documentation/filesystems/path-lookup.txt for more details. |
31e6b01f | 2144 | */ |
b07ad996 | 2145 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
8966be90 | 2146 | unsigned seq; |
31e6b01f | 2147 | |
31e6b01f | 2148 | seqretry: |
12f8ad4b LT |
2149 | /* |
2150 | * The dentry sequence count protects us from concurrent | |
da53be12 | 2151 | * renames, and thus protects parent and name fields. |
12f8ad4b LT |
2152 | * |
2153 | * The caller must perform a seqcount check in order | |
da53be12 | 2154 | * to do anything useful with the returned dentry. |
12f8ad4b LT |
2155 | * |
2156 | * NOTE! We do a "raw" seqcount_begin here. That means that | |
2157 | * we don't wait for the sequence count to stabilize if it | |
2158 | * is in the middle of a sequence change. If we do the slow | |
2159 | * dentry compare, we will do seqretries until it is stable, | |
2160 | * and if we end up with a successful lookup, we actually | |
2161 | * want to exit RCU lookup anyway. | |
2162 | */ | |
2163 | seq = raw_seqcount_begin(&dentry->d_seq); | |
31e6b01f NP |
2164 | if (dentry->d_parent != parent) |
2165 | continue; | |
2e321806 LT |
2166 | if (d_unhashed(dentry)) |
2167 | continue; | |
12f8ad4b | 2168 | |
830c0f0e | 2169 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
26fe5750 LT |
2170 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
2171 | continue; | |
da53be12 LT |
2172 | *seqp = seq; |
2173 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { | |
12f8ad4b LT |
2174 | case D_COMP_OK: |
2175 | return dentry; | |
2176 | case D_COMP_NOMATCH: | |
31e6b01f | 2177 | continue; |
12f8ad4b LT |
2178 | default: |
2179 | goto seqretry; | |
2180 | } | |
31e6b01f | 2181 | } |
12f8ad4b | 2182 | |
26fe5750 | 2183 | if (dentry->d_name.hash_len != hashlen) |
ee983e89 | 2184 | continue; |
da53be12 | 2185 | *seqp = seq; |
26fe5750 | 2186 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
12f8ad4b | 2187 | return dentry; |
31e6b01f NP |
2188 | } |
2189 | return NULL; | |
2190 | } | |
2191 | ||
1da177e4 LT |
2192 | /** |
2193 | * d_lookup - search for a dentry | |
2194 | * @parent: parent dentry | |
2195 | * @name: qstr of name we wish to find | |
b04f784e | 2196 | * Returns: dentry, or NULL |
1da177e4 | 2197 | * |
b04f784e NP |
2198 | * d_lookup searches the children of the parent dentry for the name in |
2199 | * question. If the dentry is found its reference count is incremented and the | |
2200 | * dentry is returned. The caller must use dput to free the entry when it has | |
2201 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 2202 | */ |
da2d8455 | 2203 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 | 2204 | { |
31e6b01f | 2205 | struct dentry *dentry; |
949854d0 | 2206 | unsigned seq; |
1da177e4 LT |
2207 | |
2208 | do { | |
2209 | seq = read_seqbegin(&rename_lock); | |
2210 | dentry = __d_lookup(parent, name); | |
2211 | if (dentry) | |
2212 | break; | |
2213 | } while (read_seqretry(&rename_lock, seq)); | |
2214 | return dentry; | |
2215 | } | |
ec4f8605 | 2216 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 2217 | |
31e6b01f | 2218 | /** |
b04f784e NP |
2219 | * __d_lookup - search for a dentry (racy) |
2220 | * @parent: parent dentry | |
2221 | * @name: qstr of name we wish to find | |
2222 | * Returns: dentry, or NULL | |
2223 | * | |
2224 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
2225 | * false-negative result due to unrelated rename activity. | |
2226 | * | |
2227 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
2228 | * however it must be used carefully, eg. with a following d_lookup in | |
2229 | * the case of failure. | |
2230 | * | |
2231 | * __d_lookup callers must be commented. | |
2232 | */ | |
a713ca2a | 2233 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 LT |
2234 | { |
2235 | unsigned int len = name->len; | |
2236 | unsigned int hash = name->hash; | |
2237 | const unsigned char *str = name->name; | |
b07ad996 | 2238 | struct hlist_bl_head *b = d_hash(parent, hash); |
ceb5bdc2 | 2239 | struct hlist_bl_node *node; |
31e6b01f | 2240 | struct dentry *found = NULL; |
665a7583 | 2241 | struct dentry *dentry; |
1da177e4 | 2242 | |
31e6b01f NP |
2243 | /* |
2244 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2245 | * required to prevent single threaded performance regressions | |
2246 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2247 | * Keep the two functions in sync. | |
2248 | */ | |
2249 | ||
b04f784e NP |
2250 | /* |
2251 | * The hash list is protected using RCU. | |
2252 | * | |
2253 | * Take d_lock when comparing a candidate dentry, to avoid races | |
2254 | * with d_move(). | |
2255 | * | |
2256 | * It is possible that concurrent renames can mess up our list | |
2257 | * walk here and result in missing our dentry, resulting in the | |
2258 | * false-negative result. d_lookup() protects against concurrent | |
2259 | * renames using rename_lock seqlock. | |
2260 | * | |
b0a4bb83 | 2261 | * See Documentation/filesystems/path-lookup.txt for more details. |
b04f784e | 2262 | */ |
1da177e4 LT |
2263 | rcu_read_lock(); |
2264 | ||
b07ad996 | 2265 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1da177e4 | 2266 | |
1da177e4 LT |
2267 | if (dentry->d_name.hash != hash) |
2268 | continue; | |
1da177e4 LT |
2269 | |
2270 | spin_lock(&dentry->d_lock); | |
1da177e4 LT |
2271 | if (dentry->d_parent != parent) |
2272 | goto next; | |
d0185c08 LT |
2273 | if (d_unhashed(dentry)) |
2274 | goto next; | |
2275 | ||
1da177e4 LT |
2276 | /* |
2277 | * It is safe to compare names since d_move() cannot | |
2278 | * change the qstr (protected by d_lock). | |
2279 | */ | |
fb045adb | 2280 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
12f8ad4b LT |
2281 | int tlen = dentry->d_name.len; |
2282 | const char *tname = dentry->d_name.name; | |
da53be12 | 2283 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
1da177e4 LT |
2284 | goto next; |
2285 | } else { | |
ee983e89 LT |
2286 | if (dentry->d_name.len != len) |
2287 | goto next; | |
12f8ad4b | 2288 | if (dentry_cmp(dentry, str, len)) |
1da177e4 LT |
2289 | goto next; |
2290 | } | |
2291 | ||
98474236 | 2292 | dentry->d_lockref.count++; |
d0185c08 | 2293 | found = dentry; |
1da177e4 LT |
2294 | spin_unlock(&dentry->d_lock); |
2295 | break; | |
2296 | next: | |
2297 | spin_unlock(&dentry->d_lock); | |
2298 | } | |
2299 | rcu_read_unlock(); | |
2300 | ||
2301 | return found; | |
2302 | } | |
2303 | ||
3e7e241f EB |
2304 | /** |
2305 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
2306 | * @dir: Directory to search in | |
2307 | * @name: qstr of name we wish to find | |
2308 | * | |
4f522a24 | 2309 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
3e7e241f EB |
2310 | */ |
2311 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
2312 | { | |
3e7e241f EB |
2313 | /* |
2314 | * Check for a fs-specific hash function. Note that we must | |
2315 | * calculate the standard hash first, as the d_op->d_hash() | |
2316 | * routine may choose to leave the hash value unchanged. | |
2317 | */ | |
2318 | name->hash = full_name_hash(name->name, name->len); | |
fb045adb | 2319 | if (dir->d_flags & DCACHE_OP_HASH) { |
da53be12 | 2320 | int err = dir->d_op->d_hash(dir, name); |
4f522a24 AV |
2321 | if (unlikely(err < 0)) |
2322 | return ERR_PTR(err); | |
3e7e241f | 2323 | } |
4f522a24 | 2324 | return d_lookup(dir, name); |
3e7e241f | 2325 | } |
4f522a24 | 2326 | EXPORT_SYMBOL(d_hash_and_lookup); |
3e7e241f | 2327 | |
1da177e4 | 2328 | /** |
786a5e15 | 2329 | * d_validate - verify dentry provided from insecure source (deprecated) |
1da177e4 | 2330 | * @dentry: The dentry alleged to be valid child of @dparent |
ff5fdb61 | 2331 | * @dparent: The parent dentry (known to be valid) |
1da177e4 LT |
2332 | * |
2333 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
2334 | * This is used by ncpfs in its readdir implementation. | |
2335 | * Zero is returned in the dentry is invalid. | |
786a5e15 NP |
2336 | * |
2337 | * This function is slow for big directories, and deprecated, do not use it. | |
1da177e4 | 2338 | */ |
d3a23e16 | 2339 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
1da177e4 | 2340 | { |
786a5e15 | 2341 | struct dentry *child; |
d3a23e16 | 2342 | |
2fd6b7f5 | 2343 | spin_lock(&dparent->d_lock); |
786a5e15 NP |
2344 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
2345 | if (dentry == child) { | |
2fd6b7f5 | 2346 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
dc0474be | 2347 | __dget_dlock(dentry); |
2fd6b7f5 NP |
2348 | spin_unlock(&dentry->d_lock); |
2349 | spin_unlock(&dparent->d_lock); | |
1da177e4 LT |
2350 | return 1; |
2351 | } | |
2352 | } | |
2fd6b7f5 | 2353 | spin_unlock(&dparent->d_lock); |
786a5e15 | 2354 | |
1da177e4 LT |
2355 | return 0; |
2356 | } | |
ec4f8605 | 2357 | EXPORT_SYMBOL(d_validate); |
1da177e4 LT |
2358 | |
2359 | /* | |
2360 | * When a file is deleted, we have two options: | |
2361 | * - turn this dentry into a negative dentry | |
2362 | * - unhash this dentry and free it. | |
2363 | * | |
2364 | * Usually, we want to just turn this into | |
2365 | * a negative dentry, but if anybody else is | |
2366 | * currently using the dentry or the inode | |
2367 | * we can't do that and we fall back on removing | |
2368 | * it from the hash queues and waiting for | |
2369 | * it to be deleted later when it has no users | |
2370 | */ | |
2371 | ||
2372 | /** | |
2373 | * d_delete - delete a dentry | |
2374 | * @dentry: The dentry to delete | |
2375 | * | |
2376 | * Turn the dentry into a negative dentry if possible, otherwise | |
2377 | * remove it from the hash queues so it can be deleted later | |
2378 | */ | |
2379 | ||
2380 | void d_delete(struct dentry * dentry) | |
2381 | { | |
873feea0 | 2382 | struct inode *inode; |
7a91bf7f | 2383 | int isdir = 0; |
1da177e4 LT |
2384 | /* |
2385 | * Are we the only user? | |
2386 | */ | |
357f8e65 | 2387 | again: |
1da177e4 | 2388 | spin_lock(&dentry->d_lock); |
873feea0 NP |
2389 | inode = dentry->d_inode; |
2390 | isdir = S_ISDIR(inode->i_mode); | |
98474236 | 2391 | if (dentry->d_lockref.count == 1) { |
1fe0c023 | 2392 | if (!spin_trylock(&inode->i_lock)) { |
357f8e65 NP |
2393 | spin_unlock(&dentry->d_lock); |
2394 | cpu_relax(); | |
2395 | goto again; | |
2396 | } | |
13e3c5e5 | 2397 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
31e6b01f | 2398 | dentry_unlink_inode(dentry); |
7a91bf7f | 2399 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
2400 | return; |
2401 | } | |
2402 | ||
2403 | if (!d_unhashed(dentry)) | |
2404 | __d_drop(dentry); | |
2405 | ||
2406 | spin_unlock(&dentry->d_lock); | |
7a91bf7f JM |
2407 | |
2408 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 2409 | } |
ec4f8605 | 2410 | EXPORT_SYMBOL(d_delete); |
1da177e4 | 2411 | |
b07ad996 | 2412 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
1da177e4 | 2413 | { |
ceb5bdc2 | 2414 | BUG_ON(!d_unhashed(entry)); |
1879fd6a | 2415 | hlist_bl_lock(b); |
dea3667b | 2416 | entry->d_flags |= DCACHE_RCUACCESS; |
b07ad996 | 2417 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
1879fd6a | 2418 | hlist_bl_unlock(b); |
1da177e4 LT |
2419 | } |
2420 | ||
770bfad8 DH |
2421 | static void _d_rehash(struct dentry * entry) |
2422 | { | |
2423 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
2424 | } | |
2425 | ||
1da177e4 LT |
2426 | /** |
2427 | * d_rehash - add an entry back to the hash | |
2428 | * @entry: dentry to add to the hash | |
2429 | * | |
2430 | * Adds a dentry to the hash according to its name. | |
2431 | */ | |
2432 | ||
2433 | void d_rehash(struct dentry * entry) | |
2434 | { | |
1da177e4 | 2435 | spin_lock(&entry->d_lock); |
770bfad8 | 2436 | _d_rehash(entry); |
1da177e4 | 2437 | spin_unlock(&entry->d_lock); |
1da177e4 | 2438 | } |
ec4f8605 | 2439 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 2440 | |
fb2d5b86 NP |
2441 | /** |
2442 | * dentry_update_name_case - update case insensitive dentry with a new name | |
2443 | * @dentry: dentry to be updated | |
2444 | * @name: new name | |
2445 | * | |
2446 | * Update a case insensitive dentry with new case of name. | |
2447 | * | |
2448 | * dentry must have been returned by d_lookup with name @name. Old and new | |
2449 | * name lengths must match (ie. no d_compare which allows mismatched name | |
2450 | * lengths). | |
2451 | * | |
2452 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
2453 | * keep renames and concurrent inserts, and readdir(2) away). | |
2454 | */ | |
2455 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
2456 | { | |
7ebfa57f | 2457 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
fb2d5b86 NP |
2458 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2459 | ||
fb2d5b86 | 2460 | spin_lock(&dentry->d_lock); |
31e6b01f | 2461 | write_seqcount_begin(&dentry->d_seq); |
fb2d5b86 | 2462 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
31e6b01f | 2463 | write_seqcount_end(&dentry->d_seq); |
fb2d5b86 | 2464 | spin_unlock(&dentry->d_lock); |
fb2d5b86 NP |
2465 | } |
2466 | EXPORT_SYMBOL(dentry_update_name_case); | |
2467 | ||
1da177e4 LT |
2468 | static void switch_names(struct dentry *dentry, struct dentry *target) |
2469 | { | |
2470 | if (dname_external(target)) { | |
2471 | if (dname_external(dentry)) { | |
2472 | /* | |
2473 | * Both external: swap the pointers | |
2474 | */ | |
9a8d5bb4 | 2475 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
2476 | } else { |
2477 | /* | |
2478 | * dentry:internal, target:external. Steal target's | |
2479 | * storage and make target internal. | |
2480 | */ | |
321bcf92 BF |
2481 | memcpy(target->d_iname, dentry->d_name.name, |
2482 | dentry->d_name.len + 1); | |
1da177e4 LT |
2483 | dentry->d_name.name = target->d_name.name; |
2484 | target->d_name.name = target->d_iname; | |
2485 | } | |
2486 | } else { | |
2487 | if (dname_external(dentry)) { | |
2488 | /* | |
2489 | * dentry:external, target:internal. Give dentry's | |
2490 | * storage to target and make dentry internal | |
2491 | */ | |
2492 | memcpy(dentry->d_iname, target->d_name.name, | |
2493 | target->d_name.len + 1); | |
2494 | target->d_name.name = dentry->d_name.name; | |
2495 | dentry->d_name.name = dentry->d_iname; | |
2496 | } else { | |
2497 | /* | |
2498 | * Both are internal. Just copy target to dentry | |
2499 | */ | |
2500 | memcpy(dentry->d_iname, target->d_name.name, | |
2501 | target->d_name.len + 1); | |
dc711ca3 AV |
2502 | dentry->d_name.len = target->d_name.len; |
2503 | return; | |
1da177e4 LT |
2504 | } |
2505 | } | |
9a8d5bb4 | 2506 | swap(dentry->d_name.len, target->d_name.len); |
1da177e4 LT |
2507 | } |
2508 | ||
2fd6b7f5 NP |
2509 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2510 | { | |
2511 | /* | |
2512 | * XXXX: do we really need to take target->d_lock? | |
2513 | */ | |
2514 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) | |
2515 | spin_lock(&target->d_parent->d_lock); | |
2516 | else { | |
2517 | if (d_ancestor(dentry->d_parent, target->d_parent)) { | |
2518 | spin_lock(&dentry->d_parent->d_lock); | |
2519 | spin_lock_nested(&target->d_parent->d_lock, | |
2520 | DENTRY_D_LOCK_NESTED); | |
2521 | } else { | |
2522 | spin_lock(&target->d_parent->d_lock); | |
2523 | spin_lock_nested(&dentry->d_parent->d_lock, | |
2524 | DENTRY_D_LOCK_NESTED); | |
2525 | } | |
2526 | } | |
2527 | if (target < dentry) { | |
2528 | spin_lock_nested(&target->d_lock, 2); | |
2529 | spin_lock_nested(&dentry->d_lock, 3); | |
2530 | } else { | |
2531 | spin_lock_nested(&dentry->d_lock, 2); | |
2532 | spin_lock_nested(&target->d_lock, 3); | |
2533 | } | |
2534 | } | |
2535 | ||
2536 | static void dentry_unlock_parents_for_move(struct dentry *dentry, | |
2537 | struct dentry *target) | |
2538 | { | |
2539 | if (target->d_parent != dentry->d_parent) | |
2540 | spin_unlock(&dentry->d_parent->d_lock); | |
2541 | if (target->d_parent != target) | |
2542 | spin_unlock(&target->d_parent->d_lock); | |
2543 | } | |
2544 | ||
1da177e4 | 2545 | /* |
2fd6b7f5 NP |
2546 | * When switching names, the actual string doesn't strictly have to |
2547 | * be preserved in the target - because we're dropping the target | |
2548 | * anyway. As such, we can just do a simple memcpy() to copy over | |
2549 | * the new name before we switch. | |
2550 | * | |
2551 | * Note that we have to be a lot more careful about getting the hash | |
2552 | * switched - we have to switch the hash value properly even if it | |
2553 | * then no longer matches the actual (corrupted) string of the target. | |
2554 | * The hash value has to match the hash queue that the dentry is on.. | |
1da177e4 | 2555 | */ |
9eaef27b | 2556 | /* |
18367501 | 2557 | * __d_move - move a dentry |
1da177e4 LT |
2558 | * @dentry: entry to move |
2559 | * @target: new dentry | |
2560 | * | |
2561 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2562 | * dcache entries should not be moved in this way. Caller must hold |
2563 | * rename_lock, the i_mutex of the source and target directories, | |
2564 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). | |
1da177e4 | 2565 | */ |
18367501 | 2566 | static void __d_move(struct dentry * dentry, struct dentry * target) |
1da177e4 | 2567 | { |
1da177e4 LT |
2568 | if (!dentry->d_inode) |
2569 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
2570 | ||
2fd6b7f5 NP |
2571 | BUG_ON(d_ancestor(dentry, target)); |
2572 | BUG_ON(d_ancestor(target, dentry)); | |
2573 | ||
2fd6b7f5 | 2574 | dentry_lock_for_move(dentry, target); |
1da177e4 | 2575 | |
31e6b01f NP |
2576 | write_seqcount_begin(&dentry->d_seq); |
2577 | write_seqcount_begin(&target->d_seq); | |
2578 | ||
ceb5bdc2 NP |
2579 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2580 | ||
2581 | /* | |
2582 | * Move the dentry to the target hash queue. Don't bother checking | |
2583 | * for the same hash queue because of how unlikely it is. | |
2584 | */ | |
2585 | __d_drop(dentry); | |
789680d1 | 2586 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
1da177e4 LT |
2587 | |
2588 | /* Unhash the target: dput() will then get rid of it */ | |
2589 | __d_drop(target); | |
2590 | ||
5160ee6f ED |
2591 | list_del(&dentry->d_u.d_child); |
2592 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
2593 | |
2594 | /* Switch the names.. */ | |
2595 | switch_names(dentry, target); | |
9a8d5bb4 | 2596 | swap(dentry->d_name.hash, target->d_name.hash); |
1da177e4 LT |
2597 | |
2598 | /* ... and switch the parents */ | |
2599 | if (IS_ROOT(dentry)) { | |
2600 | dentry->d_parent = target->d_parent; | |
2601 | target->d_parent = target; | |
5160ee6f | 2602 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 | 2603 | } else { |
9a8d5bb4 | 2604 | swap(dentry->d_parent, target->d_parent); |
1da177e4 LT |
2605 | |
2606 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 2607 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
2608 | } |
2609 | ||
5160ee6f | 2610 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2fd6b7f5 | 2611 | |
31e6b01f NP |
2612 | write_seqcount_end(&target->d_seq); |
2613 | write_seqcount_end(&dentry->d_seq); | |
2614 | ||
2fd6b7f5 | 2615 | dentry_unlock_parents_for_move(dentry, target); |
1da177e4 | 2616 | spin_unlock(&target->d_lock); |
c32ccd87 | 2617 | fsnotify_d_move(dentry); |
1da177e4 | 2618 | spin_unlock(&dentry->d_lock); |
18367501 AV |
2619 | } |
2620 | ||
2621 | /* | |
2622 | * d_move - move a dentry | |
2623 | * @dentry: entry to move | |
2624 | * @target: new dentry | |
2625 | * | |
2626 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2627 | * dcache entries should not be moved in this way. See the locking |
2628 | * requirements for __d_move. | |
18367501 AV |
2629 | */ |
2630 | void d_move(struct dentry *dentry, struct dentry *target) | |
2631 | { | |
2632 | write_seqlock(&rename_lock); | |
2633 | __d_move(dentry, target); | |
1da177e4 | 2634 | write_sequnlock(&rename_lock); |
9eaef27b | 2635 | } |
ec4f8605 | 2636 | EXPORT_SYMBOL(d_move); |
1da177e4 | 2637 | |
e2761a11 OH |
2638 | /** |
2639 | * d_ancestor - search for an ancestor | |
2640 | * @p1: ancestor dentry | |
2641 | * @p2: child dentry | |
2642 | * | |
2643 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
2644 | * an ancestor of p2, else NULL. | |
9eaef27b | 2645 | */ |
e2761a11 | 2646 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
2647 | { |
2648 | struct dentry *p; | |
2649 | ||
871c0067 | 2650 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 2651 | if (p->d_parent == p1) |
e2761a11 | 2652 | return p; |
9eaef27b | 2653 | } |
e2761a11 | 2654 | return NULL; |
9eaef27b TM |
2655 | } |
2656 | ||
2657 | /* | |
2658 | * This helper attempts to cope with remotely renamed directories | |
2659 | * | |
2660 | * It assumes that the caller is already holding | |
18367501 | 2661 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
9eaef27b TM |
2662 | * |
2663 | * Note: If ever the locking in lock_rename() changes, then please | |
2664 | * remember to update this too... | |
9eaef27b | 2665 | */ |
873feea0 NP |
2666 | static struct dentry *__d_unalias(struct inode *inode, |
2667 | struct dentry *dentry, struct dentry *alias) | |
9eaef27b TM |
2668 | { |
2669 | struct mutex *m1 = NULL, *m2 = NULL; | |
ee3efa91 | 2670 | struct dentry *ret = ERR_PTR(-EBUSY); |
9eaef27b TM |
2671 | |
2672 | /* If alias and dentry share a parent, then no extra locks required */ | |
2673 | if (alias->d_parent == dentry->d_parent) | |
2674 | goto out_unalias; | |
2675 | ||
9eaef27b | 2676 | /* See lock_rename() */ |
9eaef27b TM |
2677 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2678 | goto out_err; | |
2679 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
2680 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
2681 | goto out_err; | |
2682 | m2 = &alias->d_parent->d_inode->i_mutex; | |
2683 | out_unalias: | |
ee3efa91 AV |
2684 | if (likely(!d_mountpoint(alias))) { |
2685 | __d_move(alias, dentry); | |
2686 | ret = alias; | |
2687 | } | |
9eaef27b | 2688 | out_err: |
873feea0 | 2689 | spin_unlock(&inode->i_lock); |
9eaef27b TM |
2690 | if (m2) |
2691 | mutex_unlock(m2); | |
2692 | if (m1) | |
2693 | mutex_unlock(m1); | |
2694 | return ret; | |
2695 | } | |
2696 | ||
770bfad8 DH |
2697 | /* |
2698 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
2699 | * named dentry in place of the dentry to be replaced. | |
2fd6b7f5 | 2700 | * returns with anon->d_lock held! |
770bfad8 DH |
2701 | */ |
2702 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
2703 | { | |
740da42e | 2704 | struct dentry *dparent; |
770bfad8 | 2705 | |
2fd6b7f5 | 2706 | dentry_lock_for_move(anon, dentry); |
770bfad8 | 2707 | |
31e6b01f NP |
2708 | write_seqcount_begin(&dentry->d_seq); |
2709 | write_seqcount_begin(&anon->d_seq); | |
2710 | ||
770bfad8 | 2711 | dparent = dentry->d_parent; |
770bfad8 | 2712 | |
2fd6b7f5 NP |
2713 | switch_names(dentry, anon); |
2714 | swap(dentry->d_name.hash, anon->d_name.hash); | |
2715 | ||
740da42e AV |
2716 | dentry->d_parent = dentry; |
2717 | list_del_init(&dentry->d_u.d_child); | |
2718 | anon->d_parent = dparent; | |
9ed53b12 | 2719 | list_move(&anon->d_u.d_child, &dparent->d_subdirs); |
770bfad8 | 2720 | |
31e6b01f NP |
2721 | write_seqcount_end(&dentry->d_seq); |
2722 | write_seqcount_end(&anon->d_seq); | |
2723 | ||
2fd6b7f5 NP |
2724 | dentry_unlock_parents_for_move(anon, dentry); |
2725 | spin_unlock(&dentry->d_lock); | |
2726 | ||
2727 | /* anon->d_lock still locked, returns locked */ | |
770bfad8 DH |
2728 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
2729 | } | |
2730 | ||
2731 | /** | |
2732 | * d_materialise_unique - introduce an inode into the tree | |
2733 | * @dentry: candidate dentry | |
2734 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
2735 | * | |
2736 | * Introduces an dentry into the tree, substituting an extant disconnected | |
c46c8877 JL |
2737 | * root directory alias in its place if there is one. Caller must hold the |
2738 | * i_mutex of the parent directory. | |
770bfad8 DH |
2739 | */ |
2740 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
2741 | { | |
9eaef27b | 2742 | struct dentry *actual; |
770bfad8 DH |
2743 | |
2744 | BUG_ON(!d_unhashed(dentry)); | |
2745 | ||
770bfad8 DH |
2746 | if (!inode) { |
2747 | actual = dentry; | |
360da900 | 2748 | __d_instantiate(dentry, NULL); |
357f8e65 NP |
2749 | d_rehash(actual); |
2750 | goto out_nolock; | |
770bfad8 DH |
2751 | } |
2752 | ||
873feea0 | 2753 | spin_lock(&inode->i_lock); |
357f8e65 | 2754 | |
9eaef27b TM |
2755 | if (S_ISDIR(inode->i_mode)) { |
2756 | struct dentry *alias; | |
2757 | ||
2758 | /* Does an aliased dentry already exist? */ | |
32ba9c3f | 2759 | alias = __d_find_alias(inode, 0); |
9eaef27b TM |
2760 | if (alias) { |
2761 | actual = alias; | |
18367501 AV |
2762 | write_seqlock(&rename_lock); |
2763 | ||
2764 | if (d_ancestor(alias, dentry)) { | |
2765 | /* Check for loops */ | |
2766 | actual = ERR_PTR(-ELOOP); | |
b18dafc8 | 2767 | spin_unlock(&inode->i_lock); |
18367501 AV |
2768 | } else if (IS_ROOT(alias)) { |
2769 | /* Is this an anonymous mountpoint that we | |
2770 | * could splice into our tree? */ | |
9eaef27b | 2771 | __d_materialise_dentry(dentry, alias); |
18367501 | 2772 | write_sequnlock(&rename_lock); |
9eaef27b TM |
2773 | __d_drop(alias); |
2774 | goto found; | |
18367501 AV |
2775 | } else { |
2776 | /* Nope, but we must(!) avoid directory | |
b18dafc8 | 2777 | * aliasing. This drops inode->i_lock */ |
18367501 | 2778 | actual = __d_unalias(inode, dentry, alias); |
9eaef27b | 2779 | } |
18367501 | 2780 | write_sequnlock(&rename_lock); |
dd179946 DH |
2781 | if (IS_ERR(actual)) { |
2782 | if (PTR_ERR(actual) == -ELOOP) | |
2783 | pr_warn_ratelimited( | |
2784 | "VFS: Lookup of '%s' in %s %s" | |
2785 | " would have caused loop\n", | |
2786 | dentry->d_name.name, | |
2787 | inode->i_sb->s_type->name, | |
2788 | inode->i_sb->s_id); | |
9eaef27b | 2789 | dput(alias); |
dd179946 | 2790 | } |
9eaef27b TM |
2791 | goto out_nolock; |
2792 | } | |
770bfad8 DH |
2793 | } |
2794 | ||
2795 | /* Add a unique reference */ | |
2796 | actual = __d_instantiate_unique(dentry, inode); | |
2797 | if (!actual) | |
2798 | actual = dentry; | |
357f8e65 NP |
2799 | else |
2800 | BUG_ON(!d_unhashed(actual)); | |
770bfad8 | 2801 | |
770bfad8 DH |
2802 | spin_lock(&actual->d_lock); |
2803 | found: | |
2804 | _d_rehash(actual); | |
2805 | spin_unlock(&actual->d_lock); | |
873feea0 | 2806 | spin_unlock(&inode->i_lock); |
9eaef27b | 2807 | out_nolock: |
770bfad8 DH |
2808 | if (actual == dentry) { |
2809 | security_d_instantiate(dentry, inode); | |
2810 | return NULL; | |
2811 | } | |
2812 | ||
2813 | iput(inode); | |
2814 | return actual; | |
770bfad8 | 2815 | } |
ec4f8605 | 2816 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
770bfad8 | 2817 | |
cdd16d02 | 2818 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
2819 | { |
2820 | *buflen -= namelen; | |
2821 | if (*buflen < 0) | |
2822 | return -ENAMETOOLONG; | |
2823 | *buffer -= namelen; | |
2824 | memcpy(*buffer, str, namelen); | |
2825 | return 0; | |
2826 | } | |
2827 | ||
232d2d60 WL |
2828 | /** |
2829 | * prepend_name - prepend a pathname in front of current buffer pointer | |
18129977 WL |
2830 | * @buffer: buffer pointer |
2831 | * @buflen: allocated length of the buffer | |
2832 | * @name: name string and length qstr structure | |
232d2d60 WL |
2833 | * |
2834 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to | |
2835 | * make sure that either the old or the new name pointer and length are | |
2836 | * fetched. However, there may be mismatch between length and pointer. | |
2837 | * The length cannot be trusted, we need to copy it byte-by-byte until | |
2838 | * the length is reached or a null byte is found. It also prepends "/" at | |
2839 | * the beginning of the name. The sequence number check at the caller will | |
2840 | * retry it again when a d_move() does happen. So any garbage in the buffer | |
2841 | * due to mismatched pointer and length will be discarded. | |
2842 | */ | |
cdd16d02 MS |
2843 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2844 | { | |
232d2d60 WL |
2845 | const char *dname = ACCESS_ONCE(name->name); |
2846 | u32 dlen = ACCESS_ONCE(name->len); | |
2847 | char *p; | |
2848 | ||
2849 | if (*buflen < dlen + 1) | |
2850 | return -ENAMETOOLONG; | |
2851 | *buflen -= dlen + 1; | |
2852 | p = *buffer -= dlen + 1; | |
2853 | *p++ = '/'; | |
2854 | while (dlen--) { | |
2855 | char c = *dname++; | |
2856 | if (!c) | |
2857 | break; | |
2858 | *p++ = c; | |
2859 | } | |
2860 | return 0; | |
cdd16d02 MS |
2861 | } |
2862 | ||
1da177e4 | 2863 | /** |
208898c1 | 2864 | * prepend_path - Prepend path string to a buffer |
9d1bc601 | 2865 | * @path: the dentry/vfsmount to report |
02125a82 | 2866 | * @root: root vfsmnt/dentry |
f2eb6575 MS |
2867 | * @buffer: pointer to the end of the buffer |
2868 | * @buflen: pointer to buffer length | |
552ce544 | 2869 | * |
18129977 WL |
2870 | * The function will first try to write out the pathname without taking any |
2871 | * lock other than the RCU read lock to make sure that dentries won't go away. | |
2872 | * It only checks the sequence number of the global rename_lock as any change | |
2873 | * in the dentry's d_seq will be preceded by changes in the rename_lock | |
2874 | * sequence number. If the sequence number had been changed, it will restart | |
2875 | * the whole pathname back-tracing sequence again by taking the rename_lock. | |
2876 | * In this case, there is no need to take the RCU read lock as the recursive | |
2877 | * parent pointer references will keep the dentry chain alive as long as no | |
2878 | * rename operation is performed. | |
1da177e4 | 2879 | */ |
02125a82 AV |
2880 | static int prepend_path(const struct path *path, |
2881 | const struct path *root, | |
f2eb6575 | 2882 | char **buffer, int *buflen) |
1da177e4 | 2883 | { |
9d1bc601 MS |
2884 | struct dentry *dentry = path->dentry; |
2885 | struct vfsmount *vfsmnt = path->mnt; | |
0714a533 | 2886 | struct mount *mnt = real_mount(vfsmnt); |
f2eb6575 | 2887 | int error = 0; |
232d2d60 WL |
2888 | unsigned seq = 0; |
2889 | char *bptr; | |
2890 | int blen; | |
6092d048 | 2891 | |
48f5ec21 | 2892 | rcu_read_lock(); |
232d2d60 WL |
2893 | restart: |
2894 | bptr = *buffer; | |
2895 | blen = *buflen; | |
2896 | read_seqbegin_or_lock(&rename_lock, &seq); | |
f2eb6575 | 2897 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
2898 | struct dentry * parent; |
2899 | ||
1da177e4 | 2900 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 2901 | /* Global root? */ |
232d2d60 WL |
2902 | if (mnt_has_parent(mnt)) { |
2903 | dentry = mnt->mnt_mountpoint; | |
2904 | mnt = mnt->mnt_parent; | |
2905 | vfsmnt = &mnt->mnt; | |
2906 | continue; | |
2907 | } | |
2908 | /* | |
2909 | * Filesystems needing to implement special "root names" | |
2910 | * should do so with ->d_dname() | |
2911 | */ | |
2912 | if (IS_ROOT(dentry) && | |
2913 | (dentry->d_name.len != 1 || | |
2914 | dentry->d_name.name[0] != '/')) { | |
2915 | WARN(1, "Root dentry has weird name <%.*s>\n", | |
2916 | (int) dentry->d_name.len, | |
2917 | dentry->d_name.name); | |
2918 | } | |
2919 | if (!error) | |
2920 | error = is_mounted(vfsmnt) ? 1 : 2; | |
2921 | break; | |
1da177e4 LT |
2922 | } |
2923 | parent = dentry->d_parent; | |
2924 | prefetch(parent); | |
232d2d60 | 2925 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
f2eb6575 MS |
2926 | if (error) |
2927 | break; | |
2928 | ||
1da177e4 LT |
2929 | dentry = parent; |
2930 | } | |
48f5ec21 AV |
2931 | if (!(seq & 1)) |
2932 | rcu_read_unlock(); | |
2933 | if (need_seqretry(&rename_lock, seq)) { | |
2934 | seq = 1; | |
232d2d60 | 2935 | goto restart; |
48f5ec21 AV |
2936 | } |
2937 | done_seqretry(&rename_lock, seq); | |
1da177e4 | 2938 | |
232d2d60 WL |
2939 | if (error >= 0 && bptr == *buffer) { |
2940 | if (--blen < 0) | |
2941 | error = -ENAMETOOLONG; | |
2942 | else | |
2943 | *--bptr = '/'; | |
2944 | } | |
2945 | *buffer = bptr; | |
2946 | *buflen = blen; | |
7ea600b5 | 2947 | return error; |
f2eb6575 | 2948 | } |
be285c71 | 2949 | |
f2eb6575 MS |
2950 | /** |
2951 | * __d_path - return the path of a dentry | |
2952 | * @path: the dentry/vfsmount to report | |
02125a82 | 2953 | * @root: root vfsmnt/dentry |
cd956a1c | 2954 | * @buf: buffer to return value in |
f2eb6575 MS |
2955 | * @buflen: buffer length |
2956 | * | |
ffd1f4ed | 2957 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
2958 | * |
2959 | * Returns a pointer into the buffer or an error code if the | |
2960 | * path was too long. | |
2961 | * | |
be148247 | 2962 | * "buflen" should be positive. |
f2eb6575 | 2963 | * |
02125a82 | 2964 | * If the path is not reachable from the supplied root, return %NULL. |
f2eb6575 | 2965 | */ |
02125a82 AV |
2966 | char *__d_path(const struct path *path, |
2967 | const struct path *root, | |
f2eb6575 MS |
2968 | char *buf, int buflen) |
2969 | { | |
2970 | char *res = buf + buflen; | |
2971 | int error; | |
2972 | ||
2973 | prepend(&res, &buflen, "\0", 1); | |
7ea600b5 | 2974 | br_read_lock(&vfsmount_lock); |
f2eb6575 | 2975 | error = prepend_path(path, root, &res, &buflen); |
7ea600b5 | 2976 | br_read_unlock(&vfsmount_lock); |
be148247 | 2977 | |
02125a82 AV |
2978 | if (error < 0) |
2979 | return ERR_PTR(error); | |
2980 | if (error > 0) | |
2981 | return NULL; | |
2982 | return res; | |
2983 | } | |
2984 | ||
2985 | char *d_absolute_path(const struct path *path, | |
2986 | char *buf, int buflen) | |
2987 | { | |
2988 | struct path root = {}; | |
2989 | char *res = buf + buflen; | |
2990 | int error; | |
2991 | ||
2992 | prepend(&res, &buflen, "\0", 1); | |
7ea600b5 | 2993 | br_read_lock(&vfsmount_lock); |
02125a82 | 2994 | error = prepend_path(path, &root, &res, &buflen); |
7ea600b5 | 2995 | br_read_unlock(&vfsmount_lock); |
02125a82 AV |
2996 | |
2997 | if (error > 1) | |
2998 | error = -EINVAL; | |
2999 | if (error < 0) | |
f2eb6575 | 3000 | return ERR_PTR(error); |
f2eb6575 | 3001 | return res; |
1da177e4 LT |
3002 | } |
3003 | ||
ffd1f4ed MS |
3004 | /* |
3005 | * same as __d_path but appends "(deleted)" for unlinked files. | |
3006 | */ | |
02125a82 AV |
3007 | static int path_with_deleted(const struct path *path, |
3008 | const struct path *root, | |
3009 | char **buf, int *buflen) | |
ffd1f4ed MS |
3010 | { |
3011 | prepend(buf, buflen, "\0", 1); | |
3012 | if (d_unlinked(path->dentry)) { | |
3013 | int error = prepend(buf, buflen, " (deleted)", 10); | |
3014 | if (error) | |
3015 | return error; | |
3016 | } | |
3017 | ||
3018 | return prepend_path(path, root, buf, buflen); | |
3019 | } | |
3020 | ||
8df9d1a4 MS |
3021 | static int prepend_unreachable(char **buffer, int *buflen) |
3022 | { | |
3023 | return prepend(buffer, buflen, "(unreachable)", 13); | |
3024 | } | |
3025 | ||
68f0d9d9 LT |
3026 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
3027 | { | |
3028 | unsigned seq; | |
3029 | ||
3030 | do { | |
3031 | seq = read_seqcount_begin(&fs->seq); | |
3032 | *root = fs->root; | |
3033 | } while (read_seqcount_retry(&fs->seq, seq)); | |
3034 | } | |
3035 | ||
a03a8a70 JB |
3036 | /** |
3037 | * d_path - return the path of a dentry | |
cf28b486 | 3038 | * @path: path to report |
a03a8a70 JB |
3039 | * @buf: buffer to return value in |
3040 | * @buflen: buffer length | |
3041 | * | |
3042 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
3043 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
3044 | * | |
52afeefb AV |
3045 | * Returns a pointer into the buffer or an error code if the path was |
3046 | * too long. Note: Callers should use the returned pointer, not the passed | |
3047 | * in buffer, to use the name! The implementation often starts at an offset | |
3048 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 3049 | * |
31f3e0b3 | 3050 | * "buflen" should be positive. |
a03a8a70 | 3051 | */ |
20d4fdc1 | 3052 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 3053 | { |
ffd1f4ed | 3054 | char *res = buf + buflen; |
6ac08c39 | 3055 | struct path root; |
ffd1f4ed | 3056 | int error; |
1da177e4 | 3057 | |
c23fbb6b ED |
3058 | /* |
3059 | * We have various synthetic filesystems that never get mounted. On | |
3060 | * these filesystems dentries are never used for lookup purposes, and | |
3061 | * thus don't need to be hashed. They also don't need a name until a | |
3062 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
3063 | * below allows us to generate a name for these objects on demand: | |
3064 | */ | |
cf28b486 JB |
3065 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
3066 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
c23fbb6b | 3067 | |
68f0d9d9 LT |
3068 | rcu_read_lock(); |
3069 | get_fs_root_rcu(current->fs, &root); | |
7ea600b5 | 3070 | br_read_lock(&vfsmount_lock); |
02125a82 | 3071 | error = path_with_deleted(path, &root, &res, &buflen); |
7ea600b5 | 3072 | br_read_unlock(&vfsmount_lock); |
68f0d9d9 LT |
3073 | rcu_read_unlock(); |
3074 | ||
02125a82 | 3075 | if (error < 0) |
ffd1f4ed | 3076 | res = ERR_PTR(error); |
1da177e4 LT |
3077 | return res; |
3078 | } | |
ec4f8605 | 3079 | EXPORT_SYMBOL(d_path); |
1da177e4 | 3080 | |
c23fbb6b ED |
3081 | /* |
3082 | * Helper function for dentry_operations.d_dname() members | |
3083 | */ | |
3084 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
3085 | const char *fmt, ...) | |
3086 | { | |
3087 | va_list args; | |
3088 | char temp[64]; | |
3089 | int sz; | |
3090 | ||
3091 | va_start(args, fmt); | |
3092 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
3093 | va_end(args); | |
3094 | ||
3095 | if (sz > sizeof(temp) || sz > buflen) | |
3096 | return ERR_PTR(-ENAMETOOLONG); | |
3097 | ||
3098 | buffer += buflen - sz; | |
3099 | return memcpy(buffer, temp, sz); | |
3100 | } | |
3101 | ||
118b2302 AV |
3102 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
3103 | { | |
3104 | char *end = buffer + buflen; | |
3105 | /* these dentries are never renamed, so d_lock is not needed */ | |
3106 | if (prepend(&end, &buflen, " (deleted)", 11) || | |
232d2d60 | 3107 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
118b2302 AV |
3108 | prepend(&end, &buflen, "/", 1)) |
3109 | end = ERR_PTR(-ENAMETOOLONG); | |
232d2d60 | 3110 | return end; |
118b2302 AV |
3111 | } |
3112 | ||
6092d048 RP |
3113 | /* |
3114 | * Write full pathname from the root of the filesystem into the buffer. | |
3115 | */ | |
ec2447c2 | 3116 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
6092d048 | 3117 | { |
232d2d60 WL |
3118 | char *end, *retval; |
3119 | int len, seq = 0; | |
3120 | int error = 0; | |
6092d048 | 3121 | |
48f5ec21 | 3122 | rcu_read_lock(); |
232d2d60 WL |
3123 | restart: |
3124 | end = buf + buflen; | |
3125 | len = buflen; | |
3126 | prepend(&end, &len, "\0", 1); | |
6092d048 RP |
3127 | if (buflen < 1) |
3128 | goto Elong; | |
3129 | /* Get '/' right */ | |
3130 | retval = end-1; | |
3131 | *retval = '/'; | |
232d2d60 | 3132 | read_seqbegin_or_lock(&rename_lock, &seq); |
cdd16d02 MS |
3133 | while (!IS_ROOT(dentry)) { |
3134 | struct dentry *parent = dentry->d_parent; | |
9abca360 | 3135 | int error; |
6092d048 | 3136 | |
6092d048 | 3137 | prefetch(parent); |
232d2d60 WL |
3138 | error = prepend_name(&end, &len, &dentry->d_name); |
3139 | if (error) | |
3140 | break; | |
6092d048 RP |
3141 | |
3142 | retval = end; | |
3143 | dentry = parent; | |
3144 | } | |
48f5ec21 AV |
3145 | if (!(seq & 1)) |
3146 | rcu_read_unlock(); | |
3147 | if (need_seqretry(&rename_lock, seq)) { | |
3148 | seq = 1; | |
232d2d60 | 3149 | goto restart; |
48f5ec21 AV |
3150 | } |
3151 | done_seqretry(&rename_lock, seq); | |
232d2d60 WL |
3152 | if (error) |
3153 | goto Elong; | |
c103135c AV |
3154 | return retval; |
3155 | Elong: | |
3156 | return ERR_PTR(-ENAMETOOLONG); | |
3157 | } | |
ec2447c2 NP |
3158 | |
3159 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
3160 | { | |
232d2d60 | 3161 | return __dentry_path(dentry, buf, buflen); |
ec2447c2 NP |
3162 | } |
3163 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
3164 | |
3165 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
3166 | { | |
3167 | char *p = NULL; | |
3168 | char *retval; | |
3169 | ||
c103135c AV |
3170 | if (d_unlinked(dentry)) { |
3171 | p = buf + buflen; | |
3172 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
3173 | goto Elong; | |
3174 | buflen++; | |
3175 | } | |
3176 | retval = __dentry_path(dentry, buf, buflen); | |
c103135c AV |
3177 | if (!IS_ERR(retval) && p) |
3178 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
3179 | return retval; |
3180 | Elong: | |
6092d048 RP |
3181 | return ERR_PTR(-ENAMETOOLONG); |
3182 | } | |
3183 | ||
8b19e341 LT |
3184 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
3185 | struct path *pwd) | |
5762482f | 3186 | { |
8b19e341 LT |
3187 | unsigned seq; |
3188 | ||
3189 | do { | |
3190 | seq = read_seqcount_begin(&fs->seq); | |
3191 | *root = fs->root; | |
3192 | *pwd = fs->pwd; | |
3193 | } while (read_seqcount_retry(&fs->seq, seq)); | |
5762482f LT |
3194 | } |
3195 | ||
1da177e4 LT |
3196 | /* |
3197 | * NOTE! The user-level library version returns a | |
3198 | * character pointer. The kernel system call just | |
3199 | * returns the length of the buffer filled (which | |
3200 | * includes the ending '\0' character), or a negative | |
3201 | * error value. So libc would do something like | |
3202 | * | |
3203 | * char *getcwd(char * buf, size_t size) | |
3204 | * { | |
3205 | * int retval; | |
3206 | * | |
3207 | * retval = sys_getcwd(buf, size); | |
3208 | * if (retval >= 0) | |
3209 | * return buf; | |
3210 | * errno = -retval; | |
3211 | * return NULL; | |
3212 | * } | |
3213 | */ | |
3cdad428 | 3214 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 3215 | { |
552ce544 | 3216 | int error; |
6ac08c39 | 3217 | struct path pwd, root; |
3272c544 | 3218 | char *page = __getname(); |
1da177e4 LT |
3219 | |
3220 | if (!page) | |
3221 | return -ENOMEM; | |
3222 | ||
8b19e341 LT |
3223 | rcu_read_lock(); |
3224 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); | |
1da177e4 | 3225 | |
552ce544 | 3226 | error = -ENOENT; |
7ea600b5 | 3227 | br_read_lock(&vfsmount_lock); |
f3da392e | 3228 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 3229 | unsigned long len; |
3272c544 LT |
3230 | char *cwd = page + PATH_MAX; |
3231 | int buflen = PATH_MAX; | |
1da177e4 | 3232 | |
8df9d1a4 | 3233 | prepend(&cwd, &buflen, "\0", 1); |
02125a82 | 3234 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
7ea600b5 | 3235 | br_read_unlock(&vfsmount_lock); |
ff812d72 | 3236 | rcu_read_unlock(); |
552ce544 | 3237 | |
02125a82 | 3238 | if (error < 0) |
552ce544 LT |
3239 | goto out; |
3240 | ||
8df9d1a4 | 3241 | /* Unreachable from current root */ |
02125a82 | 3242 | if (error > 0) { |
8df9d1a4 MS |
3243 | error = prepend_unreachable(&cwd, &buflen); |
3244 | if (error) | |
3245 | goto out; | |
3246 | } | |
3247 | ||
552ce544 | 3248 | error = -ERANGE; |
3272c544 | 3249 | len = PATH_MAX + page - cwd; |
552ce544 LT |
3250 | if (len <= size) { |
3251 | error = len; | |
3252 | if (copy_to_user(buf, cwd, len)) | |
3253 | error = -EFAULT; | |
3254 | } | |
949854d0 | 3255 | } else { |
7ea600b5 | 3256 | br_read_unlock(&vfsmount_lock); |
ff812d72 | 3257 | rcu_read_unlock(); |
949854d0 | 3258 | } |
1da177e4 LT |
3259 | |
3260 | out: | |
3272c544 | 3261 | __putname(page); |
1da177e4 LT |
3262 | return error; |
3263 | } | |
3264 | ||
3265 | /* | |
3266 | * Test whether new_dentry is a subdirectory of old_dentry. | |
3267 | * | |
3268 | * Trivially implemented using the dcache structure | |
3269 | */ | |
3270 | ||
3271 | /** | |
3272 | * is_subdir - is new dentry a subdirectory of old_dentry | |
3273 | * @new_dentry: new dentry | |
3274 | * @old_dentry: old dentry | |
3275 | * | |
3276 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
3277 | * Returns 0 otherwise. | |
3278 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
3279 | */ | |
3280 | ||
e2761a11 | 3281 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 LT |
3282 | { |
3283 | int result; | |
949854d0 | 3284 | unsigned seq; |
1da177e4 | 3285 | |
e2761a11 OH |
3286 | if (new_dentry == old_dentry) |
3287 | return 1; | |
3288 | ||
e2761a11 | 3289 | do { |
1da177e4 | 3290 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 3291 | seq = read_seqbegin(&rename_lock); |
949854d0 NP |
3292 | /* |
3293 | * Need rcu_readlock to protect against the d_parent trashing | |
3294 | * due to d_move | |
3295 | */ | |
3296 | rcu_read_lock(); | |
e2761a11 | 3297 | if (d_ancestor(old_dentry, new_dentry)) |
1da177e4 | 3298 | result = 1; |
e2761a11 OH |
3299 | else |
3300 | result = 0; | |
949854d0 | 3301 | rcu_read_unlock(); |
1da177e4 | 3302 | } while (read_seqretry(&rename_lock, seq)); |
1da177e4 LT |
3303 | |
3304 | return result; | |
3305 | } | |
3306 | ||
db14fc3a | 3307 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
1da177e4 | 3308 | { |
db14fc3a MS |
3309 | struct dentry *root = data; |
3310 | if (dentry != root) { | |
3311 | if (d_unhashed(dentry) || !dentry->d_inode) | |
3312 | return D_WALK_SKIP; | |
1da177e4 | 3313 | |
01ddc4ed MS |
3314 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
3315 | dentry->d_flags |= DCACHE_GENOCIDE; | |
3316 | dentry->d_lockref.count--; | |
3317 | } | |
1da177e4 | 3318 | } |
db14fc3a MS |
3319 | return D_WALK_CONTINUE; |
3320 | } | |
58db63d0 | 3321 | |
db14fc3a MS |
3322 | void d_genocide(struct dentry *parent) |
3323 | { | |
3324 | d_walk(parent, parent, d_genocide_kill, NULL); | |
1da177e4 LT |
3325 | } |
3326 | ||
60545d0d | 3327 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
1da177e4 | 3328 | { |
60545d0d AV |
3329 | inode_dec_link_count(inode); |
3330 | BUG_ON(dentry->d_name.name != dentry->d_iname || | |
3331 | !hlist_unhashed(&dentry->d_alias) || | |
3332 | !d_unlinked(dentry)); | |
3333 | spin_lock(&dentry->d_parent->d_lock); | |
3334 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
3335 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", | |
3336 | (unsigned long long)inode->i_ino); | |
3337 | spin_unlock(&dentry->d_lock); | |
3338 | spin_unlock(&dentry->d_parent->d_lock); | |
3339 | d_instantiate(dentry, inode); | |
1da177e4 | 3340 | } |
60545d0d | 3341 | EXPORT_SYMBOL(d_tmpfile); |
1da177e4 LT |
3342 | |
3343 | static __initdata unsigned long dhash_entries; | |
3344 | static int __init set_dhash_entries(char *str) | |
3345 | { | |
3346 | if (!str) | |
3347 | return 0; | |
3348 | dhash_entries = simple_strtoul(str, &str, 0); | |
3349 | return 1; | |
3350 | } | |
3351 | __setup("dhash_entries=", set_dhash_entries); | |
3352 | ||
3353 | static void __init dcache_init_early(void) | |
3354 | { | |
074b8517 | 3355 | unsigned int loop; |
1da177e4 LT |
3356 | |
3357 | /* If hashes are distributed across NUMA nodes, defer | |
3358 | * hash allocation until vmalloc space is available. | |
3359 | */ | |
3360 | if (hashdist) | |
3361 | return; | |
3362 | ||
3363 | dentry_hashtable = | |
3364 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3365 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3366 | dhash_entries, |
3367 | 13, | |
3368 | HASH_EARLY, | |
3369 | &d_hash_shift, | |
3370 | &d_hash_mask, | |
31fe62b9 | 3371 | 0, |
1da177e4 LT |
3372 | 0); |
3373 | ||
074b8517 | 3374 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3375 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3376 | } |
3377 | ||
74bf17cf | 3378 | static void __init dcache_init(void) |
1da177e4 | 3379 | { |
074b8517 | 3380 | unsigned int loop; |
1da177e4 LT |
3381 | |
3382 | /* | |
3383 | * A constructor could be added for stable state like the lists, | |
3384 | * but it is probably not worth it because of the cache nature | |
3385 | * of the dcache. | |
3386 | */ | |
0a31bd5f CL |
3387 | dentry_cache = KMEM_CACHE(dentry, |
3388 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 LT |
3389 | |
3390 | /* Hash may have been set up in dcache_init_early */ | |
3391 | if (!hashdist) | |
3392 | return; | |
3393 | ||
3394 | dentry_hashtable = | |
3395 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3396 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3397 | dhash_entries, |
3398 | 13, | |
3399 | 0, | |
3400 | &d_hash_shift, | |
3401 | &d_hash_mask, | |
31fe62b9 | 3402 | 0, |
1da177e4 LT |
3403 | 0); |
3404 | ||
074b8517 | 3405 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3406 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3407 | } |
3408 | ||
3409 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 3410 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 3411 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 3412 | |
1da177e4 LT |
3413 | EXPORT_SYMBOL(d_genocide); |
3414 | ||
1da177e4 LT |
3415 | void __init vfs_caches_init_early(void) |
3416 | { | |
3417 | dcache_init_early(); | |
3418 | inode_init_early(); | |
3419 | } | |
3420 | ||
3421 | void __init vfs_caches_init(unsigned long mempages) | |
3422 | { | |
3423 | unsigned long reserve; | |
3424 | ||
3425 | /* Base hash sizes on available memory, with a reserve equal to | |
3426 | 150% of current kernel size */ | |
3427 | ||
3428 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
3429 | mempages -= reserve; | |
3430 | ||
3431 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 3432 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 3433 | |
74bf17cf DC |
3434 | dcache_init(); |
3435 | inode_init(); | |
1da177e4 | 3436 | files_init(mempages); |
74bf17cf | 3437 | mnt_init(); |
1da177e4 LT |
3438 | bdev_cache_init(); |
3439 | chrdev_init(); | |
3440 | } |