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 | |
1da177e4 LT |
91 | /* |
92 | * This is the single most critical data structure when it comes | |
93 | * to the dcache: the hashtable for lookups. Somebody should try | |
94 | * to make this good - I've just made it work. | |
95 | * | |
96 | * This hash-function tries to avoid losing too many bits of hash | |
97 | * information, yet avoid using a prime hash-size or similar. | |
98 | */ | |
1da177e4 | 99 | |
fa3536cc ED |
100 | static unsigned int d_hash_mask __read_mostly; |
101 | static unsigned int d_hash_shift __read_mostly; | |
ceb5bdc2 | 102 | |
b07ad996 | 103 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
ceb5bdc2 | 104 | |
8966be90 | 105 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
6d7d1a0d | 106 | unsigned int hash) |
ceb5bdc2 | 107 | { |
6d7d1a0d | 108 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
482db906 AV |
109 | hash = hash + (hash >> d_hash_shift); |
110 | return dentry_hashtable + (hash & d_hash_mask); | |
ceb5bdc2 NP |
111 | } |
112 | ||
1da177e4 LT |
113 | /* Statistics gathering. */ |
114 | struct dentry_stat_t dentry_stat = { | |
115 | .age_limit = 45, | |
116 | }; | |
117 | ||
3942c07c | 118 | static DEFINE_PER_CPU(long, nr_dentry); |
62d36c77 | 119 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
312d3ca8 CH |
120 | |
121 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
62d36c77 DC |
122 | |
123 | /* | |
124 | * Here we resort to our own counters instead of using generic per-cpu counters | |
125 | * for consistency with what the vfs inode code does. We are expected to harvest | |
126 | * better code and performance by having our own specialized counters. | |
127 | * | |
128 | * Please note that the loop is done over all possible CPUs, not over all online | |
129 | * CPUs. The reason for this is that we don't want to play games with CPUs going | |
130 | * on and off. If one of them goes off, we will just keep their counters. | |
131 | * | |
132 | * glommer: See cffbc8a for details, and if you ever intend to change this, | |
133 | * please update all vfs counters to match. | |
134 | */ | |
3942c07c | 135 | static long get_nr_dentry(void) |
3e880fb5 NP |
136 | { |
137 | int i; | |
3942c07c | 138 | long sum = 0; |
3e880fb5 NP |
139 | for_each_possible_cpu(i) |
140 | sum += per_cpu(nr_dentry, i); | |
141 | return sum < 0 ? 0 : sum; | |
142 | } | |
143 | ||
62d36c77 DC |
144 | static long get_nr_dentry_unused(void) |
145 | { | |
146 | int i; | |
147 | long sum = 0; | |
148 | for_each_possible_cpu(i) | |
149 | sum += per_cpu(nr_dentry_unused, i); | |
150 | return sum < 0 ? 0 : sum; | |
151 | } | |
152 | ||
312d3ca8 CH |
153 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
154 | size_t *lenp, loff_t *ppos) | |
155 | { | |
3e880fb5 | 156 | dentry_stat.nr_dentry = get_nr_dentry(); |
62d36c77 | 157 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
3942c07c | 158 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
312d3ca8 CH |
159 | } |
160 | #endif | |
161 | ||
5483f18e LT |
162 | /* |
163 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. | |
164 | * The strings are both count bytes long, and count is non-zero. | |
165 | */ | |
e419b4cc LT |
166 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
167 | ||
168 | #include <asm/word-at-a-time.h> | |
169 | /* | |
170 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a | |
171 | * aligned allocation for this particular component. We don't | |
172 | * strictly need the load_unaligned_zeropad() safety, but it | |
173 | * doesn't hurt either. | |
174 | * | |
175 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do | |
176 | * need the careful unaligned handling. | |
177 | */ | |
94753db5 | 178 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
5483f18e | 179 | { |
bfcfaa77 | 180 | unsigned long a,b,mask; |
bfcfaa77 LT |
181 | |
182 | for (;;) { | |
12f8ad4b | 183 | a = *(unsigned long *)cs; |
e419b4cc | 184 | b = load_unaligned_zeropad(ct); |
bfcfaa77 LT |
185 | if (tcount < sizeof(unsigned long)) |
186 | break; | |
187 | if (unlikely(a != b)) | |
188 | return 1; | |
189 | cs += sizeof(unsigned long); | |
190 | ct += sizeof(unsigned long); | |
191 | tcount -= sizeof(unsigned long); | |
192 | if (!tcount) | |
193 | return 0; | |
194 | } | |
a5c21dce | 195 | mask = bytemask_from_count(tcount); |
bfcfaa77 | 196 | return unlikely(!!((a ^ b) & mask)); |
e419b4cc LT |
197 | } |
198 | ||
bfcfaa77 | 199 | #else |
e419b4cc | 200 | |
94753db5 | 201 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
e419b4cc | 202 | { |
5483f18e LT |
203 | do { |
204 | if (*cs != *ct) | |
205 | return 1; | |
206 | cs++; | |
207 | ct++; | |
208 | tcount--; | |
209 | } while (tcount); | |
210 | return 0; | |
211 | } | |
212 | ||
e419b4cc LT |
213 | #endif |
214 | ||
94753db5 LT |
215 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
216 | { | |
6326c71f | 217 | const unsigned char *cs; |
94753db5 LT |
218 | /* |
219 | * Be careful about RCU walk racing with rename: | |
220 | * use ACCESS_ONCE to fetch the name pointer. | |
221 | * | |
222 | * NOTE! Even if a rename will mean that the length | |
223 | * was not loaded atomically, we don't care. The | |
224 | * RCU walk will check the sequence count eventually, | |
225 | * and catch it. And we won't overrun the buffer, | |
226 | * because we're reading the name pointer atomically, | |
227 | * and a dentry name is guaranteed to be properly | |
228 | * terminated with a NUL byte. | |
229 | * | |
230 | * End result: even if 'len' is wrong, we'll exit | |
231 | * early because the data cannot match (there can | |
232 | * be no NUL in the ct/tcount data) | |
233 | */ | |
6326c71f LT |
234 | cs = ACCESS_ONCE(dentry->d_name.name); |
235 | smp_read_barrier_depends(); | |
236 | return dentry_string_cmp(cs, ct, tcount); | |
94753db5 LT |
237 | } |
238 | ||
9c82ab9c | 239 | static void __d_free(struct rcu_head *head) |
1da177e4 | 240 | { |
9c82ab9c CH |
241 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
242 | ||
b3d9b7a3 | 243 | WARN_ON(!hlist_unhashed(&dentry->d_alias)); |
1da177e4 LT |
244 | if (dname_external(dentry)) |
245 | kfree(dentry->d_name.name); | |
246 | kmem_cache_free(dentry_cache, dentry); | |
247 | } | |
248 | ||
b4f0354e AV |
249 | static void dentry_free(struct dentry *dentry) |
250 | { | |
251 | /* if dentry was never visible to RCU, immediate free is OK */ | |
252 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) | |
253 | __d_free(&dentry->d_u.d_rcu); | |
254 | else | |
255 | call_rcu(&dentry->d_u.d_rcu, __d_free); | |
256 | } | |
257 | ||
31e6b01f NP |
258 | /** |
259 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups | |
ff5fdb61 | 260 | * @dentry: the target dentry |
31e6b01f NP |
261 | * After this call, in-progress rcu-walk path lookup will fail. This |
262 | * should be called after unhashing, and after changing d_inode (if | |
263 | * the dentry has not already been unhashed). | |
264 | */ | |
265 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) | |
266 | { | |
267 | assert_spin_locked(&dentry->d_lock); | |
268 | /* Go through a barrier */ | |
269 | write_seqcount_barrier(&dentry->d_seq); | |
270 | } | |
271 | ||
1da177e4 LT |
272 | /* |
273 | * Release the dentry's inode, using the filesystem | |
31e6b01f NP |
274 | * d_iput() operation if defined. Dentry has no refcount |
275 | * and is unhashed. | |
1da177e4 | 276 | */ |
858119e1 | 277 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 | 278 | __releases(dentry->d_lock) |
873feea0 | 279 | __releases(dentry->d_inode->i_lock) |
1da177e4 LT |
280 | { |
281 | struct inode *inode = dentry->d_inode; | |
282 | if (inode) { | |
283 | dentry->d_inode = NULL; | |
b3d9b7a3 | 284 | hlist_del_init(&dentry->d_alias); |
1da177e4 | 285 | spin_unlock(&dentry->d_lock); |
873feea0 | 286 | spin_unlock(&inode->i_lock); |
f805fbda LT |
287 | if (!inode->i_nlink) |
288 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
289 | if (dentry->d_op && dentry->d_op->d_iput) |
290 | dentry->d_op->d_iput(dentry, inode); | |
291 | else | |
292 | iput(inode); | |
293 | } else { | |
294 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
295 | } |
296 | } | |
297 | ||
31e6b01f NP |
298 | /* |
299 | * Release the dentry's inode, using the filesystem | |
300 | * d_iput() operation if defined. dentry remains in-use. | |
301 | */ | |
302 | static void dentry_unlink_inode(struct dentry * dentry) | |
303 | __releases(dentry->d_lock) | |
873feea0 | 304 | __releases(dentry->d_inode->i_lock) |
31e6b01f NP |
305 | { |
306 | struct inode *inode = dentry->d_inode; | |
b18825a7 | 307 | __d_clear_type(dentry); |
31e6b01f | 308 | dentry->d_inode = NULL; |
b3d9b7a3 | 309 | hlist_del_init(&dentry->d_alias); |
31e6b01f NP |
310 | dentry_rcuwalk_barrier(dentry); |
311 | spin_unlock(&dentry->d_lock); | |
873feea0 | 312 | spin_unlock(&inode->i_lock); |
31e6b01f NP |
313 | if (!inode->i_nlink) |
314 | fsnotify_inoderemove(inode); | |
315 | if (dentry->d_op && dentry->d_op->d_iput) | |
316 | dentry->d_op->d_iput(dentry, inode); | |
317 | else | |
318 | iput(inode); | |
319 | } | |
320 | ||
89dc77bc LT |
321 | /* |
322 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry | |
323 | * is in use - which includes both the "real" per-superblock | |
324 | * LRU list _and_ the DCACHE_SHRINK_LIST use. | |
325 | * | |
326 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is | |
327 | * on the shrink list (ie not on the superblock LRU list). | |
328 | * | |
329 | * The per-cpu "nr_dentry_unused" counters are updated with | |
330 | * the DCACHE_LRU_LIST bit. | |
331 | * | |
332 | * These helper functions make sure we always follow the | |
333 | * rules. d_lock must be held by the caller. | |
334 | */ | |
335 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) | |
336 | static void d_lru_add(struct dentry *dentry) | |
337 | { | |
338 | D_FLAG_VERIFY(dentry, 0); | |
339 | dentry->d_flags |= DCACHE_LRU_LIST; | |
340 | this_cpu_inc(nr_dentry_unused); | |
341 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
342 | } | |
343 | ||
344 | static void d_lru_del(struct dentry *dentry) | |
345 | { | |
346 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
347 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
348 | this_cpu_dec(nr_dentry_unused); | |
349 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
350 | } | |
351 | ||
352 | static void d_shrink_del(struct dentry *dentry) | |
353 | { | |
354 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
355 | list_del_init(&dentry->d_lru); | |
356 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
357 | this_cpu_dec(nr_dentry_unused); | |
358 | } | |
359 | ||
360 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) | |
361 | { | |
362 | D_FLAG_VERIFY(dentry, 0); | |
363 | list_add(&dentry->d_lru, list); | |
364 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; | |
365 | this_cpu_inc(nr_dentry_unused); | |
366 | } | |
367 | ||
368 | /* | |
369 | * These can only be called under the global LRU lock, ie during the | |
370 | * callback for freeing the LRU list. "isolate" removes it from the | |
371 | * LRU lists entirely, while shrink_move moves it to the indicated | |
372 | * private list. | |
373 | */ | |
374 | static void d_lru_isolate(struct dentry *dentry) | |
375 | { | |
376 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
377 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
378 | this_cpu_dec(nr_dentry_unused); | |
379 | list_del_init(&dentry->d_lru); | |
380 | } | |
381 | ||
382 | static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list) | |
383 | { | |
384 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
385 | dentry->d_flags |= DCACHE_SHRINK_LIST; | |
386 | list_move_tail(&dentry->d_lru, list); | |
387 | } | |
388 | ||
da3bbdd4 | 389 | /* |
f6041567 | 390 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
da3bbdd4 KM |
391 | */ |
392 | static void dentry_lru_add(struct dentry *dentry) | |
393 | { | |
89dc77bc LT |
394 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
395 | d_lru_add(dentry); | |
da3bbdd4 KM |
396 | } |
397 | ||
789680d1 NP |
398 | /** |
399 | * d_drop - drop a dentry | |
400 | * @dentry: dentry to drop | |
401 | * | |
402 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
403 | * be found through a VFS lookup any more. Note that this is different from | |
404 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
405 | * possible, giving a successful _negative_ lookup, while d_drop will | |
406 | * just make the cache lookup fail. | |
407 | * | |
408 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
409 | * reason (NFS timeouts or autofs deletes). | |
410 | * | |
411 | * __d_drop requires dentry->d_lock. | |
412 | */ | |
413 | void __d_drop(struct dentry *dentry) | |
414 | { | |
dea3667b | 415 | if (!d_unhashed(dentry)) { |
b61625d2 | 416 | struct hlist_bl_head *b; |
7632e465 BF |
417 | /* |
418 | * Hashed dentries are normally on the dentry hashtable, | |
419 | * with the exception of those newly allocated by | |
420 | * d_obtain_alias, which are always IS_ROOT: | |
421 | */ | |
422 | if (unlikely(IS_ROOT(dentry))) | |
b61625d2 AV |
423 | b = &dentry->d_sb->s_anon; |
424 | else | |
425 | b = d_hash(dentry->d_parent, dentry->d_name.hash); | |
426 | ||
427 | hlist_bl_lock(b); | |
428 | __hlist_bl_del(&dentry->d_hash); | |
429 | dentry->d_hash.pprev = NULL; | |
430 | hlist_bl_unlock(b); | |
dea3667b | 431 | dentry_rcuwalk_barrier(dentry); |
789680d1 NP |
432 | } |
433 | } | |
434 | EXPORT_SYMBOL(__d_drop); | |
435 | ||
436 | void d_drop(struct dentry *dentry) | |
437 | { | |
789680d1 NP |
438 | spin_lock(&dentry->d_lock); |
439 | __d_drop(dentry); | |
440 | spin_unlock(&dentry->d_lock); | |
789680d1 NP |
441 | } |
442 | EXPORT_SYMBOL(d_drop); | |
443 | ||
e55fd011 | 444 | static void __dentry_kill(struct dentry *dentry) |
77812a1e | 445 | { |
41edf278 AV |
446 | struct dentry *parent = NULL; |
447 | bool can_free = true; | |
41edf278 | 448 | if (!IS_ROOT(dentry)) |
77812a1e | 449 | parent = dentry->d_parent; |
31e6b01f | 450 | |
0d98439e LT |
451 | /* |
452 | * The dentry is now unrecoverably dead to the world. | |
453 | */ | |
454 | lockref_mark_dead(&dentry->d_lockref); | |
455 | ||
f0023bc6 | 456 | /* |
f0023bc6 SW |
457 | * inform the fs via d_prune that this dentry is about to be |
458 | * unhashed and destroyed. | |
459 | */ | |
590fb51f | 460 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry)) |
61572bb1 YZ |
461 | dentry->d_op->d_prune(dentry); |
462 | ||
01b60351 AV |
463 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
464 | if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) | |
465 | d_lru_del(dentry); | |
01b60351 | 466 | } |
77812a1e NP |
467 | /* if it was on the hash then remove it */ |
468 | __d_drop(dentry); | |
03b3b889 AV |
469 | list_del(&dentry->d_u.d_child); |
470 | /* | |
471 | * Inform d_walk() that we are no longer attached to the | |
472 | * dentry tree | |
473 | */ | |
474 | dentry->d_flags |= DCACHE_DENTRY_KILLED; | |
475 | if (parent) | |
476 | spin_unlock(&parent->d_lock); | |
477 | dentry_iput(dentry); | |
478 | /* | |
479 | * dentry_iput drops the locks, at which point nobody (except | |
480 | * transient RCU lookups) can reach this dentry. | |
481 | */ | |
482 | BUG_ON((int)dentry->d_lockref.count > 0); | |
483 | this_cpu_dec(nr_dentry); | |
484 | if (dentry->d_op && dentry->d_op->d_release) | |
485 | dentry->d_op->d_release(dentry); | |
486 | ||
41edf278 AV |
487 | spin_lock(&dentry->d_lock); |
488 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { | |
489 | dentry->d_flags |= DCACHE_MAY_FREE; | |
490 | can_free = false; | |
491 | } | |
492 | spin_unlock(&dentry->d_lock); | |
41edf278 AV |
493 | if (likely(can_free)) |
494 | dentry_free(dentry); | |
e55fd011 AV |
495 | } |
496 | ||
497 | /* | |
498 | * Finish off a dentry we've decided to kill. | |
499 | * dentry->d_lock must be held, returns with it unlocked. | |
500 | * If ref is non-zero, then decrement the refcount too. | |
501 | * Returns dentry requiring refcount drop, or NULL if we're done. | |
502 | */ | |
8cbf74da | 503 | static struct dentry *dentry_kill(struct dentry *dentry) |
e55fd011 AV |
504 | __releases(dentry->d_lock) |
505 | { | |
506 | struct inode *inode = dentry->d_inode; | |
507 | struct dentry *parent = NULL; | |
508 | ||
509 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) | |
510 | goto failed; | |
511 | ||
512 | if (!IS_ROOT(dentry)) { | |
513 | parent = dentry->d_parent; | |
514 | if (unlikely(!spin_trylock(&parent->d_lock))) { | |
515 | if (inode) | |
516 | spin_unlock(&inode->i_lock); | |
517 | goto failed; | |
518 | } | |
519 | } | |
520 | ||
521 | __dentry_kill(dentry); | |
03b3b889 | 522 | return parent; |
e55fd011 AV |
523 | |
524 | failed: | |
8cbf74da AV |
525 | spin_unlock(&dentry->d_lock); |
526 | cpu_relax(); | |
e55fd011 | 527 | return dentry; /* try again with same dentry */ |
77812a1e NP |
528 | } |
529 | ||
046b961b AV |
530 | static inline struct dentry *lock_parent(struct dentry *dentry) |
531 | { | |
532 | struct dentry *parent = dentry->d_parent; | |
533 | if (IS_ROOT(dentry)) | |
534 | return NULL; | |
535 | if (likely(spin_trylock(&parent->d_lock))) | |
536 | return parent; | |
537 | spin_unlock(&dentry->d_lock); | |
538 | rcu_read_lock(); | |
539 | again: | |
540 | parent = ACCESS_ONCE(dentry->d_parent); | |
541 | spin_lock(&parent->d_lock); | |
542 | /* | |
543 | * We can't blindly lock dentry until we are sure | |
544 | * that we won't violate the locking order. | |
545 | * Any changes of dentry->d_parent must have | |
546 | * been done with parent->d_lock held, so | |
547 | * spin_lock() above is enough of a barrier | |
548 | * for checking if it's still our child. | |
549 | */ | |
550 | if (unlikely(parent != dentry->d_parent)) { | |
551 | spin_unlock(&parent->d_lock); | |
552 | goto again; | |
553 | } | |
554 | rcu_read_unlock(); | |
555 | if (parent != dentry) | |
9f12600f | 556 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
046b961b AV |
557 | else |
558 | parent = NULL; | |
559 | return parent; | |
560 | } | |
561 | ||
1da177e4 LT |
562 | /* |
563 | * This is dput | |
564 | * | |
565 | * This is complicated by the fact that we do not want to put | |
566 | * dentries that are no longer on any hash chain on the unused | |
567 | * list: we'd much rather just get rid of them immediately. | |
568 | * | |
569 | * However, that implies that we have to traverse the dentry | |
570 | * tree upwards to the parents which might _also_ now be | |
571 | * scheduled for deletion (it may have been only waiting for | |
572 | * its last child to go away). | |
573 | * | |
574 | * This tail recursion is done by hand as we don't want to depend | |
575 | * on the compiler to always get this right (gcc generally doesn't). | |
576 | * Real recursion would eat up our stack space. | |
577 | */ | |
578 | ||
579 | /* | |
580 | * dput - release a dentry | |
581 | * @dentry: dentry to release | |
582 | * | |
583 | * Release a dentry. This will drop the usage count and if appropriate | |
584 | * call the dentry unlink method as well as removing it from the queues and | |
585 | * releasing its resources. If the parent dentries were scheduled for release | |
586 | * they too may now get deleted. | |
1da177e4 | 587 | */ |
1da177e4 LT |
588 | void dput(struct dentry *dentry) |
589 | { | |
8aab6a27 | 590 | if (unlikely(!dentry)) |
1da177e4 LT |
591 | return; |
592 | ||
593 | repeat: | |
98474236 | 594 | if (lockref_put_or_lock(&dentry->d_lockref)) |
1da177e4 | 595 | return; |
1da177e4 | 596 | |
8aab6a27 LT |
597 | /* Unreachable? Get rid of it */ |
598 | if (unlikely(d_unhashed(dentry))) | |
599 | goto kill_it; | |
600 | ||
601 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { | |
1da177e4 | 602 | if (dentry->d_op->d_delete(dentry)) |
61f3dee4 | 603 | goto kill_it; |
1da177e4 | 604 | } |
265ac902 | 605 | |
358eec18 LT |
606 | if (!(dentry->d_flags & DCACHE_REFERENCED)) |
607 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 608 | dentry_lru_add(dentry); |
265ac902 | 609 | |
98474236 | 610 | dentry->d_lockref.count--; |
61f3dee4 | 611 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
612 | return; |
613 | ||
d52b9086 | 614 | kill_it: |
8cbf74da | 615 | dentry = dentry_kill(dentry); |
d52b9086 MS |
616 | if (dentry) |
617 | goto repeat; | |
1da177e4 | 618 | } |
ec4f8605 | 619 | EXPORT_SYMBOL(dput); |
1da177e4 LT |
620 | |
621 | /** | |
622 | * d_invalidate - invalidate a dentry | |
623 | * @dentry: dentry to invalidate | |
624 | * | |
625 | * Try to invalidate the dentry if it turns out to be | |
626 | * possible. If there are other dentries that can be | |
627 | * reached through this one we can't delete it and we | |
628 | * return -EBUSY. On success we return 0. | |
629 | * | |
630 | * no dcache lock. | |
631 | */ | |
632 | ||
633 | int d_invalidate(struct dentry * dentry) | |
634 | { | |
635 | /* | |
636 | * If it's already been dropped, return OK. | |
637 | */ | |
da502956 | 638 | spin_lock(&dentry->d_lock); |
1da177e4 | 639 | if (d_unhashed(dentry)) { |
da502956 | 640 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
641 | return 0; |
642 | } | |
643 | /* | |
644 | * Check whether to do a partial shrink_dcache | |
645 | * to get rid of unused child entries. | |
646 | */ | |
647 | if (!list_empty(&dentry->d_subdirs)) { | |
da502956 | 648 | spin_unlock(&dentry->d_lock); |
1da177e4 | 649 | shrink_dcache_parent(dentry); |
da502956 | 650 | spin_lock(&dentry->d_lock); |
1da177e4 LT |
651 | } |
652 | ||
653 | /* | |
654 | * Somebody else still using it? | |
655 | * | |
656 | * If it's a directory, we can't drop it | |
657 | * for fear of somebody re-populating it | |
658 | * with children (even though dropping it | |
659 | * would make it unreachable from the root, | |
660 | * we might still populate it if it was a | |
661 | * working directory or similar). | |
50e69630 AV |
662 | * We also need to leave mountpoints alone, |
663 | * directory or not. | |
1da177e4 | 664 | */ |
98474236 | 665 | if (dentry->d_lockref.count > 1 && dentry->d_inode) { |
50e69630 | 666 | if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) { |
1da177e4 | 667 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
668 | return -EBUSY; |
669 | } | |
670 | } | |
671 | ||
672 | __d_drop(dentry); | |
673 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
674 | return 0; |
675 | } | |
ec4f8605 | 676 | EXPORT_SYMBOL(d_invalidate); |
1da177e4 | 677 | |
b5c84bf6 | 678 | /* This must be called with d_lock held */ |
dc0474be | 679 | static inline void __dget_dlock(struct dentry *dentry) |
23044507 | 680 | { |
98474236 | 681 | dentry->d_lockref.count++; |
23044507 NP |
682 | } |
683 | ||
dc0474be | 684 | static inline void __dget(struct dentry *dentry) |
1da177e4 | 685 | { |
98474236 | 686 | lockref_get(&dentry->d_lockref); |
1da177e4 LT |
687 | } |
688 | ||
b7ab39f6 NP |
689 | struct dentry *dget_parent(struct dentry *dentry) |
690 | { | |
df3d0bbc | 691 | int gotref; |
b7ab39f6 NP |
692 | struct dentry *ret; |
693 | ||
df3d0bbc WL |
694 | /* |
695 | * Do optimistic parent lookup without any | |
696 | * locking. | |
697 | */ | |
698 | rcu_read_lock(); | |
699 | ret = ACCESS_ONCE(dentry->d_parent); | |
700 | gotref = lockref_get_not_zero(&ret->d_lockref); | |
701 | rcu_read_unlock(); | |
702 | if (likely(gotref)) { | |
703 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) | |
704 | return ret; | |
705 | dput(ret); | |
706 | } | |
707 | ||
b7ab39f6 | 708 | repeat: |
a734eb45 NP |
709 | /* |
710 | * Don't need rcu_dereference because we re-check it was correct under | |
711 | * the lock. | |
712 | */ | |
713 | rcu_read_lock(); | |
b7ab39f6 | 714 | ret = dentry->d_parent; |
a734eb45 NP |
715 | spin_lock(&ret->d_lock); |
716 | if (unlikely(ret != dentry->d_parent)) { | |
717 | spin_unlock(&ret->d_lock); | |
718 | rcu_read_unlock(); | |
b7ab39f6 NP |
719 | goto repeat; |
720 | } | |
a734eb45 | 721 | rcu_read_unlock(); |
98474236 WL |
722 | BUG_ON(!ret->d_lockref.count); |
723 | ret->d_lockref.count++; | |
b7ab39f6 | 724 | spin_unlock(&ret->d_lock); |
b7ab39f6 NP |
725 | return ret; |
726 | } | |
727 | EXPORT_SYMBOL(dget_parent); | |
728 | ||
1da177e4 LT |
729 | /** |
730 | * d_find_alias - grab a hashed alias of inode | |
731 | * @inode: inode in question | |
32ba9c3f LT |
732 | * @want_discon: flag, used by d_splice_alias, to request |
733 | * that only a DISCONNECTED alias be returned. | |
1da177e4 LT |
734 | * |
735 | * If inode has a hashed alias, or is a directory and has any alias, | |
736 | * acquire the reference to alias and return it. Otherwise return NULL. | |
737 | * Notice that if inode is a directory there can be only one alias and | |
738 | * it can be unhashed only if it has no children, or if it is the root | |
739 | * of a filesystem. | |
740 | * | |
21c0d8fd | 741 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
32ba9c3f LT |
742 | * any other hashed alias over that one unless @want_discon is set, |
743 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. | |
1da177e4 | 744 | */ |
32ba9c3f | 745 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
1da177e4 | 746 | { |
da502956 | 747 | struct dentry *alias, *discon_alias; |
1da177e4 | 748 | |
da502956 NP |
749 | again: |
750 | discon_alias = NULL; | |
b67bfe0d | 751 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
da502956 | 752 | spin_lock(&alias->d_lock); |
1da177e4 | 753 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
21c0d8fd | 754 | if (IS_ROOT(alias) && |
da502956 | 755 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
1da177e4 | 756 | discon_alias = alias; |
32ba9c3f | 757 | } else if (!want_discon) { |
dc0474be | 758 | __dget_dlock(alias); |
da502956 NP |
759 | spin_unlock(&alias->d_lock); |
760 | return alias; | |
761 | } | |
762 | } | |
763 | spin_unlock(&alias->d_lock); | |
764 | } | |
765 | if (discon_alias) { | |
766 | alias = discon_alias; | |
767 | spin_lock(&alias->d_lock); | |
768 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
769 | if (IS_ROOT(alias) && | |
770 | (alias->d_flags & DCACHE_DISCONNECTED)) { | |
dc0474be | 771 | __dget_dlock(alias); |
da502956 | 772 | spin_unlock(&alias->d_lock); |
1da177e4 LT |
773 | return alias; |
774 | } | |
775 | } | |
da502956 NP |
776 | spin_unlock(&alias->d_lock); |
777 | goto again; | |
1da177e4 | 778 | } |
da502956 | 779 | return NULL; |
1da177e4 LT |
780 | } |
781 | ||
da502956 | 782 | struct dentry *d_find_alias(struct inode *inode) |
1da177e4 | 783 | { |
214fda1f DH |
784 | struct dentry *de = NULL; |
785 | ||
b3d9b7a3 | 786 | if (!hlist_empty(&inode->i_dentry)) { |
873feea0 | 787 | spin_lock(&inode->i_lock); |
32ba9c3f | 788 | de = __d_find_alias(inode, 0); |
873feea0 | 789 | spin_unlock(&inode->i_lock); |
214fda1f | 790 | } |
1da177e4 LT |
791 | return de; |
792 | } | |
ec4f8605 | 793 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
794 | |
795 | /* | |
796 | * Try to kill dentries associated with this inode. | |
797 | * WARNING: you must own a reference to inode. | |
798 | */ | |
799 | void d_prune_aliases(struct inode *inode) | |
800 | { | |
0cdca3f9 | 801 | struct dentry *dentry; |
1da177e4 | 802 | restart: |
873feea0 | 803 | spin_lock(&inode->i_lock); |
b67bfe0d | 804 | hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 | 805 | spin_lock(&dentry->d_lock); |
98474236 | 806 | if (!dentry->d_lockref.count) { |
590fb51f YZ |
807 | /* |
808 | * inform the fs via d_prune that this dentry | |
809 | * is about to be unhashed and destroyed. | |
810 | */ | |
811 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && | |
812 | !d_unhashed(dentry)) | |
813 | dentry->d_op->d_prune(dentry); | |
814 | ||
dc0474be | 815 | __dget_dlock(dentry); |
1da177e4 LT |
816 | __d_drop(dentry); |
817 | spin_unlock(&dentry->d_lock); | |
873feea0 | 818 | spin_unlock(&inode->i_lock); |
1da177e4 LT |
819 | dput(dentry); |
820 | goto restart; | |
821 | } | |
822 | spin_unlock(&dentry->d_lock); | |
823 | } | |
873feea0 | 824 | spin_unlock(&inode->i_lock); |
1da177e4 | 825 | } |
ec4f8605 | 826 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 | 827 | |
3049cfe2 | 828 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 829 | { |
5c47e6d0 | 830 | struct dentry *dentry, *parent; |
da3bbdd4 | 831 | |
60942f2f | 832 | while (!list_empty(list)) { |
ff2fde99 | 833 | struct inode *inode; |
60942f2f | 834 | dentry = list_entry(list->prev, struct dentry, d_lru); |
ec33679d | 835 | spin_lock(&dentry->d_lock); |
046b961b AV |
836 | parent = lock_parent(dentry); |
837 | ||
dd1f6b2e DC |
838 | /* |
839 | * The dispose list is isolated and dentries are not accounted | |
840 | * to the LRU here, so we can simply remove it from the list | |
841 | * here regardless of whether it is referenced or not. | |
842 | */ | |
89dc77bc | 843 | d_shrink_del(dentry); |
dd1f6b2e | 844 | |
1da177e4 LT |
845 | /* |
846 | * We found an inuse dentry which was not removed from | |
dd1f6b2e | 847 | * the LRU because of laziness during lookup. Do not free it. |
1da177e4 | 848 | */ |
41edf278 | 849 | if ((int)dentry->d_lockref.count > 0) { |
da3bbdd4 | 850 | spin_unlock(&dentry->d_lock); |
046b961b AV |
851 | if (parent) |
852 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
853 | continue; |
854 | } | |
77812a1e | 855 | |
64fd72e0 AV |
856 | |
857 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) { | |
858 | bool can_free = dentry->d_flags & DCACHE_MAY_FREE; | |
859 | spin_unlock(&dentry->d_lock); | |
046b961b AV |
860 | if (parent) |
861 | spin_unlock(&parent->d_lock); | |
64fd72e0 AV |
862 | if (can_free) |
863 | dentry_free(dentry); | |
864 | continue; | |
865 | } | |
866 | ||
ff2fde99 AV |
867 | inode = dentry->d_inode; |
868 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) { | |
89dc77bc | 869 | d_shrink_add(dentry, list); |
dd1f6b2e | 870 | spin_unlock(&dentry->d_lock); |
046b961b AV |
871 | if (parent) |
872 | spin_unlock(&parent->d_lock); | |
5c47e6d0 | 873 | continue; |
dd1f6b2e | 874 | } |
ff2fde99 | 875 | |
ff2fde99 | 876 | __dentry_kill(dentry); |
046b961b | 877 | |
5c47e6d0 AV |
878 | /* |
879 | * We need to prune ancestors too. This is necessary to prevent | |
880 | * quadratic behavior of shrink_dcache_parent(), but is also | |
881 | * expected to be beneficial in reducing dentry cache | |
882 | * fragmentation. | |
883 | */ | |
884 | dentry = parent; | |
b2b80195 AV |
885 | while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { |
886 | parent = lock_parent(dentry); | |
887 | if (dentry->d_lockref.count != 1) { | |
888 | dentry->d_lockref.count--; | |
889 | spin_unlock(&dentry->d_lock); | |
890 | if (parent) | |
891 | spin_unlock(&parent->d_lock); | |
892 | break; | |
893 | } | |
894 | inode = dentry->d_inode; /* can't be NULL */ | |
895 | if (unlikely(!spin_trylock(&inode->i_lock))) { | |
896 | spin_unlock(&dentry->d_lock); | |
897 | if (parent) | |
898 | spin_unlock(&parent->d_lock); | |
899 | cpu_relax(); | |
900 | continue; | |
901 | } | |
902 | __dentry_kill(dentry); | |
903 | dentry = parent; | |
904 | } | |
da3bbdd4 | 905 | } |
3049cfe2 CH |
906 | } |
907 | ||
f6041567 DC |
908 | static enum lru_status |
909 | dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) | |
910 | { | |
911 | struct list_head *freeable = arg; | |
912 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
913 | ||
914 | ||
915 | /* | |
916 | * we are inverting the lru lock/dentry->d_lock here, | |
917 | * so use a trylock. If we fail to get the lock, just skip | |
918 | * it | |
919 | */ | |
920 | if (!spin_trylock(&dentry->d_lock)) | |
921 | return LRU_SKIP; | |
922 | ||
923 | /* | |
924 | * Referenced dentries are still in use. If they have active | |
925 | * counts, just remove them from the LRU. Otherwise give them | |
926 | * another pass through the LRU. | |
927 | */ | |
928 | if (dentry->d_lockref.count) { | |
89dc77bc | 929 | d_lru_isolate(dentry); |
f6041567 DC |
930 | spin_unlock(&dentry->d_lock); |
931 | return LRU_REMOVED; | |
932 | } | |
933 | ||
934 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
935 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
936 | spin_unlock(&dentry->d_lock); | |
937 | ||
938 | /* | |
939 | * The list move itself will be made by the common LRU code. At | |
940 | * this point, we've dropped the dentry->d_lock but keep the | |
941 | * lru lock. This is safe to do, since every list movement is | |
942 | * protected by the lru lock even if both locks are held. | |
943 | * | |
944 | * This is guaranteed by the fact that all LRU management | |
945 | * functions are intermediated by the LRU API calls like | |
946 | * list_lru_add and list_lru_del. List movement in this file | |
947 | * only ever occur through this functions or through callbacks | |
948 | * like this one, that are called from the LRU API. | |
949 | * | |
950 | * The only exceptions to this are functions like | |
951 | * shrink_dentry_list, and code that first checks for the | |
952 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be | |
953 | * operating only with stack provided lists after they are | |
954 | * properly isolated from the main list. It is thus, always a | |
955 | * local access. | |
956 | */ | |
957 | return LRU_ROTATE; | |
958 | } | |
959 | ||
89dc77bc | 960 | d_lru_shrink_move(dentry, freeable); |
f6041567 DC |
961 | spin_unlock(&dentry->d_lock); |
962 | ||
963 | return LRU_REMOVED; | |
964 | } | |
965 | ||
3049cfe2 | 966 | /** |
b48f03b3 DC |
967 | * prune_dcache_sb - shrink the dcache |
968 | * @sb: superblock | |
f6041567 | 969 | * @nr_to_scan : number of entries to try to free |
9b17c623 | 970 | * @nid: which node to scan for freeable entities |
b48f03b3 | 971 | * |
f6041567 | 972 | * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is |
b48f03b3 DC |
973 | * done when we need more memory an called from the superblock shrinker |
974 | * function. | |
3049cfe2 | 975 | * |
b48f03b3 DC |
976 | * This function may fail to free any resources if all the dentries are in |
977 | * use. | |
3049cfe2 | 978 | */ |
9b17c623 DC |
979 | long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan, |
980 | int nid) | |
3049cfe2 | 981 | { |
f6041567 DC |
982 | LIST_HEAD(dispose); |
983 | long freed; | |
3049cfe2 | 984 | |
9b17c623 DC |
985 | freed = list_lru_walk_node(&sb->s_dentry_lru, nid, dentry_lru_isolate, |
986 | &dispose, &nr_to_scan); | |
f6041567 | 987 | shrink_dentry_list(&dispose); |
0a234c6d | 988 | return freed; |
da3bbdd4 | 989 | } |
23044507 | 990 | |
4e717f5c GC |
991 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
992 | spinlock_t *lru_lock, void *arg) | |
dd1f6b2e | 993 | { |
4e717f5c GC |
994 | struct list_head *freeable = arg; |
995 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
dd1f6b2e | 996 | |
4e717f5c GC |
997 | /* |
998 | * we are inverting the lru lock/dentry->d_lock here, | |
999 | * so use a trylock. If we fail to get the lock, just skip | |
1000 | * it | |
1001 | */ | |
1002 | if (!spin_trylock(&dentry->d_lock)) | |
1003 | return LRU_SKIP; | |
1004 | ||
89dc77bc | 1005 | d_lru_shrink_move(dentry, freeable); |
4e717f5c | 1006 | spin_unlock(&dentry->d_lock); |
ec33679d | 1007 | |
4e717f5c | 1008 | return LRU_REMOVED; |
da3bbdd4 KM |
1009 | } |
1010 | ||
4e717f5c | 1011 | |
1da177e4 LT |
1012 | /** |
1013 | * shrink_dcache_sb - shrink dcache for a superblock | |
1014 | * @sb: superblock | |
1015 | * | |
3049cfe2 CH |
1016 | * Shrink the dcache for the specified super block. This is used to free |
1017 | * the dcache before unmounting a file system. | |
1da177e4 | 1018 | */ |
3049cfe2 | 1019 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 1020 | { |
4e717f5c GC |
1021 | long freed; |
1022 | ||
1023 | do { | |
1024 | LIST_HEAD(dispose); | |
1025 | ||
1026 | freed = list_lru_walk(&sb->s_dentry_lru, | |
1027 | dentry_lru_isolate_shrink, &dispose, UINT_MAX); | |
3049cfe2 | 1028 | |
4e717f5c GC |
1029 | this_cpu_sub(nr_dentry_unused, freed); |
1030 | shrink_dentry_list(&dispose); | |
1031 | } while (freed > 0); | |
1da177e4 | 1032 | } |
ec4f8605 | 1033 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 1034 | |
db14fc3a MS |
1035 | /** |
1036 | * enum d_walk_ret - action to talke during tree walk | |
1037 | * @D_WALK_CONTINUE: contrinue walk | |
1038 | * @D_WALK_QUIT: quit walk | |
1039 | * @D_WALK_NORETRY: quit when retry is needed | |
1040 | * @D_WALK_SKIP: skip this dentry and its children | |
1041 | */ | |
1042 | enum d_walk_ret { | |
1043 | D_WALK_CONTINUE, | |
1044 | D_WALK_QUIT, | |
1045 | D_WALK_NORETRY, | |
1046 | D_WALK_SKIP, | |
1047 | }; | |
c826cb7d | 1048 | |
1da177e4 | 1049 | /** |
db14fc3a MS |
1050 | * d_walk - walk the dentry tree |
1051 | * @parent: start of walk | |
1052 | * @data: data passed to @enter() and @finish() | |
1053 | * @enter: callback when first entering the dentry | |
1054 | * @finish: callback when successfully finished the walk | |
1da177e4 | 1055 | * |
db14fc3a | 1056 | * The @enter() and @finish() callbacks are called with d_lock held. |
1da177e4 | 1057 | */ |
db14fc3a MS |
1058 | static void d_walk(struct dentry *parent, void *data, |
1059 | enum d_walk_ret (*enter)(void *, struct dentry *), | |
1060 | void (*finish)(void *)) | |
1da177e4 | 1061 | { |
949854d0 | 1062 | struct dentry *this_parent; |
1da177e4 | 1063 | struct list_head *next; |
48f5ec21 | 1064 | unsigned seq = 0; |
db14fc3a MS |
1065 | enum d_walk_ret ret; |
1066 | bool retry = true; | |
949854d0 | 1067 | |
58db63d0 | 1068 | again: |
48f5ec21 | 1069 | read_seqbegin_or_lock(&rename_lock, &seq); |
58db63d0 | 1070 | this_parent = parent; |
2fd6b7f5 | 1071 | spin_lock(&this_parent->d_lock); |
db14fc3a MS |
1072 | |
1073 | ret = enter(data, this_parent); | |
1074 | switch (ret) { | |
1075 | case D_WALK_CONTINUE: | |
1076 | break; | |
1077 | case D_WALK_QUIT: | |
1078 | case D_WALK_SKIP: | |
1079 | goto out_unlock; | |
1080 | case D_WALK_NORETRY: | |
1081 | retry = false; | |
1082 | break; | |
1083 | } | |
1da177e4 LT |
1084 | repeat: |
1085 | next = this_parent->d_subdirs.next; | |
1086 | resume: | |
1087 | while (next != &this_parent->d_subdirs) { | |
1088 | struct list_head *tmp = next; | |
5160ee6f | 1089 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 | 1090 | next = tmp->next; |
2fd6b7f5 NP |
1091 | |
1092 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
db14fc3a MS |
1093 | |
1094 | ret = enter(data, dentry); | |
1095 | switch (ret) { | |
1096 | case D_WALK_CONTINUE: | |
1097 | break; | |
1098 | case D_WALK_QUIT: | |
2fd6b7f5 | 1099 | spin_unlock(&dentry->d_lock); |
db14fc3a MS |
1100 | goto out_unlock; |
1101 | case D_WALK_NORETRY: | |
1102 | retry = false; | |
1103 | break; | |
1104 | case D_WALK_SKIP: | |
1105 | spin_unlock(&dentry->d_lock); | |
1106 | continue; | |
2fd6b7f5 | 1107 | } |
db14fc3a | 1108 | |
1da177e4 | 1109 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
1110 | spin_unlock(&this_parent->d_lock); |
1111 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1112 | this_parent = dentry; |
2fd6b7f5 | 1113 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1114 | goto repeat; |
1115 | } | |
2fd6b7f5 | 1116 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
1117 | } |
1118 | /* | |
1119 | * All done at this level ... ascend and resume the search. | |
1120 | */ | |
1121 | if (this_parent != parent) { | |
c826cb7d | 1122 | struct dentry *child = this_parent; |
31dec132 AV |
1123 | this_parent = child->d_parent; |
1124 | ||
1125 | rcu_read_lock(); | |
1126 | spin_unlock(&child->d_lock); | |
1127 | spin_lock(&this_parent->d_lock); | |
1128 | ||
1129 | /* | |
1130 | * might go back up the wrong parent if we have had a rename | |
1131 | * or deletion | |
1132 | */ | |
1133 | if (this_parent != child->d_parent || | |
1134 | (child->d_flags & DCACHE_DENTRY_KILLED) || | |
1135 | need_seqretry(&rename_lock, seq)) { | |
1136 | spin_unlock(&this_parent->d_lock); | |
1137 | rcu_read_unlock(); | |
949854d0 | 1138 | goto rename_retry; |
31dec132 AV |
1139 | } |
1140 | rcu_read_unlock(); | |
949854d0 | 1141 | next = child->d_u.d_child.next; |
1da177e4 LT |
1142 | goto resume; |
1143 | } | |
48f5ec21 | 1144 | if (need_seqretry(&rename_lock, seq)) { |
db14fc3a | 1145 | spin_unlock(&this_parent->d_lock); |
949854d0 | 1146 | goto rename_retry; |
db14fc3a MS |
1147 | } |
1148 | if (finish) | |
1149 | finish(data); | |
1150 | ||
1151 | out_unlock: | |
1152 | spin_unlock(&this_parent->d_lock); | |
48f5ec21 | 1153 | done_seqretry(&rename_lock, seq); |
db14fc3a | 1154 | return; |
58db63d0 NP |
1155 | |
1156 | rename_retry: | |
db14fc3a MS |
1157 | if (!retry) |
1158 | return; | |
48f5ec21 | 1159 | seq = 1; |
58db63d0 | 1160 | goto again; |
1da177e4 | 1161 | } |
db14fc3a MS |
1162 | |
1163 | /* | |
1164 | * Search for at least 1 mount point in the dentry's subdirs. | |
1165 | * We descend to the next level whenever the d_subdirs | |
1166 | * list is non-empty and continue searching. | |
1167 | */ | |
1168 | ||
db14fc3a MS |
1169 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
1170 | { | |
1171 | int *ret = data; | |
1172 | if (d_mountpoint(dentry)) { | |
1173 | *ret = 1; | |
1174 | return D_WALK_QUIT; | |
1175 | } | |
1176 | return D_WALK_CONTINUE; | |
1177 | } | |
1178 | ||
69c88dc7 RD |
1179 | /** |
1180 | * have_submounts - check for mounts over a dentry | |
1181 | * @parent: dentry to check. | |
1182 | * | |
1183 | * Return true if the parent or its subdirectories contain | |
1184 | * a mount point | |
1185 | */ | |
db14fc3a MS |
1186 | int have_submounts(struct dentry *parent) |
1187 | { | |
1188 | int ret = 0; | |
1189 | ||
1190 | d_walk(parent, &ret, check_mount, NULL); | |
1191 | ||
1192 | return ret; | |
1193 | } | |
ec4f8605 | 1194 | EXPORT_SYMBOL(have_submounts); |
1da177e4 | 1195 | |
eed81007 MS |
1196 | /* |
1197 | * Called by mount code to set a mountpoint and check if the mountpoint is | |
1198 | * reachable (e.g. NFS can unhash a directory dentry and then the complete | |
1199 | * subtree can become unreachable). | |
1200 | * | |
1201 | * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For | |
1202 | * this reason take rename_lock and d_lock on dentry and ancestors. | |
1203 | */ | |
1204 | int d_set_mounted(struct dentry *dentry) | |
1205 | { | |
1206 | struct dentry *p; | |
1207 | int ret = -ENOENT; | |
1208 | write_seqlock(&rename_lock); | |
1209 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { | |
1210 | /* Need exclusion wrt. check_submounts_and_drop() */ | |
1211 | spin_lock(&p->d_lock); | |
1212 | if (unlikely(d_unhashed(p))) { | |
1213 | spin_unlock(&p->d_lock); | |
1214 | goto out; | |
1215 | } | |
1216 | spin_unlock(&p->d_lock); | |
1217 | } | |
1218 | spin_lock(&dentry->d_lock); | |
1219 | if (!d_unlinked(dentry)) { | |
1220 | dentry->d_flags |= DCACHE_MOUNTED; | |
1221 | ret = 0; | |
1222 | } | |
1223 | spin_unlock(&dentry->d_lock); | |
1224 | out: | |
1225 | write_sequnlock(&rename_lock); | |
1226 | return ret; | |
1227 | } | |
1228 | ||
1da177e4 | 1229 | /* |
fd517909 | 1230 | * Search the dentry child list of the specified parent, |
1da177e4 LT |
1231 | * and move any unused dentries to the end of the unused |
1232 | * list for prune_dcache(). We descend to the next level | |
1233 | * whenever the d_subdirs list is non-empty and continue | |
1234 | * searching. | |
1235 | * | |
1236 | * It returns zero iff there are no unused children, | |
1237 | * otherwise it returns the number of children moved to | |
1238 | * the end of the unused list. This may not be the total | |
1239 | * number of unused children, because select_parent can | |
1240 | * drop the lock and return early due to latency | |
1241 | * constraints. | |
1242 | */ | |
1da177e4 | 1243 | |
db14fc3a MS |
1244 | struct select_data { |
1245 | struct dentry *start; | |
1246 | struct list_head dispose; | |
1247 | int found; | |
1248 | }; | |
23044507 | 1249 | |
db14fc3a MS |
1250 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
1251 | { | |
1252 | struct select_data *data = _data; | |
1253 | enum d_walk_ret ret = D_WALK_CONTINUE; | |
1da177e4 | 1254 | |
db14fc3a MS |
1255 | if (data->start == dentry) |
1256 | goto out; | |
2fd6b7f5 | 1257 | |
fe91522a | 1258 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
db14fc3a | 1259 | data->found++; |
fe91522a AV |
1260 | } else { |
1261 | if (dentry->d_flags & DCACHE_LRU_LIST) | |
1262 | d_lru_del(dentry); | |
1263 | if (!dentry->d_lockref.count) { | |
1264 | d_shrink_add(dentry, &data->dispose); | |
1265 | data->found++; | |
1266 | } | |
1da177e4 | 1267 | } |
db14fc3a MS |
1268 | /* |
1269 | * We can return to the caller if we have found some (this | |
1270 | * ensures forward progress). We'll be coming back to find | |
1271 | * the rest. | |
1272 | */ | |
fe91522a AV |
1273 | if (!list_empty(&data->dispose)) |
1274 | ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; | |
1da177e4 | 1275 | out: |
db14fc3a | 1276 | return ret; |
1da177e4 LT |
1277 | } |
1278 | ||
1279 | /** | |
1280 | * shrink_dcache_parent - prune dcache | |
1281 | * @parent: parent of entries to prune | |
1282 | * | |
1283 | * Prune the dcache to remove unused children of the parent dentry. | |
1284 | */ | |
db14fc3a | 1285 | void shrink_dcache_parent(struct dentry *parent) |
1da177e4 | 1286 | { |
db14fc3a MS |
1287 | for (;;) { |
1288 | struct select_data data; | |
1da177e4 | 1289 | |
db14fc3a MS |
1290 | INIT_LIST_HEAD(&data.dispose); |
1291 | data.start = parent; | |
1292 | data.found = 0; | |
1293 | ||
1294 | d_walk(parent, &data, select_collect, NULL); | |
1295 | if (!data.found) | |
1296 | break; | |
1297 | ||
1298 | shrink_dentry_list(&data.dispose); | |
421348f1 GT |
1299 | cond_resched(); |
1300 | } | |
1da177e4 | 1301 | } |
ec4f8605 | 1302 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1303 | |
9c8c10e2 | 1304 | static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) |
42c32608 | 1305 | { |
9c8c10e2 AV |
1306 | /* it has busy descendents; complain about those instead */ |
1307 | if (!list_empty(&dentry->d_subdirs)) | |
1308 | return D_WALK_CONTINUE; | |
42c32608 | 1309 | |
9c8c10e2 AV |
1310 | /* root with refcount 1 is fine */ |
1311 | if (dentry == _data && dentry->d_lockref.count == 1) | |
1312 | return D_WALK_CONTINUE; | |
1313 | ||
1314 | printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} " | |
1315 | " still in use (%d) [unmount of %s %s]\n", | |
42c32608 AV |
1316 | dentry, |
1317 | dentry->d_inode ? | |
1318 | dentry->d_inode->i_ino : 0UL, | |
9c8c10e2 | 1319 | dentry, |
42c32608 AV |
1320 | dentry->d_lockref.count, |
1321 | dentry->d_sb->s_type->name, | |
1322 | dentry->d_sb->s_id); | |
9c8c10e2 AV |
1323 | WARN_ON(1); |
1324 | return D_WALK_CONTINUE; | |
1325 | } | |
1326 | ||
1327 | static void do_one_tree(struct dentry *dentry) | |
1328 | { | |
1329 | shrink_dcache_parent(dentry); | |
1330 | d_walk(dentry, dentry, umount_check, NULL); | |
1331 | d_drop(dentry); | |
1332 | dput(dentry); | |
42c32608 AV |
1333 | } |
1334 | ||
1335 | /* | |
1336 | * destroy the dentries attached to a superblock on unmounting | |
1337 | */ | |
1338 | void shrink_dcache_for_umount(struct super_block *sb) | |
1339 | { | |
1340 | struct dentry *dentry; | |
1341 | ||
9c8c10e2 | 1342 | WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked"); |
42c32608 AV |
1343 | |
1344 | dentry = sb->s_root; | |
1345 | sb->s_root = NULL; | |
9c8c10e2 | 1346 | do_one_tree(dentry); |
42c32608 AV |
1347 | |
1348 | while (!hlist_bl_empty(&sb->s_anon)) { | |
9c8c10e2 AV |
1349 | dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash)); |
1350 | do_one_tree(dentry); | |
42c32608 AV |
1351 | } |
1352 | } | |
1353 | ||
848ac114 MS |
1354 | static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry) |
1355 | { | |
1356 | struct select_data *data = _data; | |
1357 | ||
1358 | if (d_mountpoint(dentry)) { | |
1359 | data->found = -EBUSY; | |
1360 | return D_WALK_QUIT; | |
1361 | } | |
1362 | ||
1363 | return select_collect(_data, dentry); | |
1364 | } | |
1365 | ||
1366 | static void check_and_drop(void *_data) | |
1367 | { | |
1368 | struct select_data *data = _data; | |
1369 | ||
1370 | if (d_mountpoint(data->start)) | |
1371 | data->found = -EBUSY; | |
1372 | if (!data->found) | |
1373 | __d_drop(data->start); | |
1374 | } | |
1375 | ||
1376 | /** | |
1377 | * check_submounts_and_drop - prune dcache, check for submounts and drop | |
1378 | * | |
1379 | * All done as a single atomic operation relative to has_unlinked_ancestor(). | |
1380 | * Returns 0 if successfully unhashed @parent. If there were submounts then | |
1381 | * return -EBUSY. | |
1382 | * | |
1383 | * @dentry: dentry to prune and drop | |
1384 | */ | |
1385 | int check_submounts_and_drop(struct dentry *dentry) | |
1386 | { | |
1387 | int ret = 0; | |
1388 | ||
1389 | /* Negative dentries can be dropped without further checks */ | |
1390 | if (!dentry->d_inode) { | |
1391 | d_drop(dentry); | |
1392 | goto out; | |
1393 | } | |
1394 | ||
1395 | for (;;) { | |
1396 | struct select_data data; | |
1397 | ||
1398 | INIT_LIST_HEAD(&data.dispose); | |
1399 | data.start = dentry; | |
1400 | data.found = 0; | |
1401 | ||
1402 | d_walk(dentry, &data, check_and_collect, check_and_drop); | |
1403 | ret = data.found; | |
1404 | ||
1405 | if (!list_empty(&data.dispose)) | |
1406 | shrink_dentry_list(&data.dispose); | |
1407 | ||
1408 | if (ret <= 0) | |
1409 | break; | |
1410 | ||
1411 | cond_resched(); | |
1412 | } | |
1413 | ||
1414 | out: | |
1415 | return ret; | |
1416 | } | |
1417 | EXPORT_SYMBOL(check_submounts_and_drop); | |
1418 | ||
1da177e4 | 1419 | /** |
a4464dbc AV |
1420 | * __d_alloc - allocate a dcache entry |
1421 | * @sb: filesystem it will belong to | |
1da177e4 LT |
1422 | * @name: qstr of the name |
1423 | * | |
1424 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1425 | * available. On a success the dentry is returned. The name passed in is | |
1426 | * copied and the copy passed in may be reused after this call. | |
1427 | */ | |
1428 | ||
a4464dbc | 1429 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1da177e4 LT |
1430 | { |
1431 | struct dentry *dentry; | |
1432 | char *dname; | |
1433 | ||
e12ba74d | 1434 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1435 | if (!dentry) |
1436 | return NULL; | |
1437 | ||
6326c71f LT |
1438 | /* |
1439 | * We guarantee that the inline name is always NUL-terminated. | |
1440 | * This way the memcpy() done by the name switching in rename | |
1441 | * will still always have a NUL at the end, even if we might | |
1442 | * be overwriting an internal NUL character | |
1443 | */ | |
1444 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; | |
1da177e4 LT |
1445 | if (name->len > DNAME_INLINE_LEN-1) { |
1446 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
1447 | if (!dname) { | |
1448 | kmem_cache_free(dentry_cache, dentry); | |
1449 | return NULL; | |
1450 | } | |
1451 | } else { | |
1452 | dname = dentry->d_iname; | |
1453 | } | |
1da177e4 LT |
1454 | |
1455 | dentry->d_name.len = name->len; | |
1456 | dentry->d_name.hash = name->hash; | |
1457 | memcpy(dname, name->name, name->len); | |
1458 | dname[name->len] = 0; | |
1459 | ||
6326c71f LT |
1460 | /* Make sure we always see the terminating NUL character */ |
1461 | smp_wmb(); | |
1462 | dentry->d_name.name = dname; | |
1463 | ||
98474236 | 1464 | dentry->d_lockref.count = 1; |
dea3667b | 1465 | dentry->d_flags = 0; |
1da177e4 | 1466 | spin_lock_init(&dentry->d_lock); |
31e6b01f | 1467 | seqcount_init(&dentry->d_seq); |
1da177e4 | 1468 | dentry->d_inode = NULL; |
a4464dbc AV |
1469 | dentry->d_parent = dentry; |
1470 | dentry->d_sb = sb; | |
1da177e4 LT |
1471 | dentry->d_op = NULL; |
1472 | dentry->d_fsdata = NULL; | |
ceb5bdc2 | 1473 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1da177e4 LT |
1474 | INIT_LIST_HEAD(&dentry->d_lru); |
1475 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
b3d9b7a3 | 1476 | INIT_HLIST_NODE(&dentry->d_alias); |
2fd6b7f5 | 1477 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
a4464dbc | 1478 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1da177e4 | 1479 | |
3e880fb5 | 1480 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1481 | |
1da177e4 LT |
1482 | return dentry; |
1483 | } | |
a4464dbc AV |
1484 | |
1485 | /** | |
1486 | * d_alloc - allocate a dcache entry | |
1487 | * @parent: parent of entry to allocate | |
1488 | * @name: qstr of the name | |
1489 | * | |
1490 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1491 | * available. On a success the dentry is returned. The name passed in is | |
1492 | * copied and the copy passed in may be reused after this call. | |
1493 | */ | |
1494 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1495 | { | |
1496 | struct dentry *dentry = __d_alloc(parent->d_sb, name); | |
1497 | if (!dentry) | |
1498 | return NULL; | |
1499 | ||
1500 | spin_lock(&parent->d_lock); | |
1501 | /* | |
1502 | * don't need child lock because it is not subject | |
1503 | * to concurrency here | |
1504 | */ | |
1505 | __dget_dlock(parent); | |
1506 | dentry->d_parent = parent; | |
1507 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); | |
1508 | spin_unlock(&parent->d_lock); | |
1509 | ||
1510 | return dentry; | |
1511 | } | |
ec4f8605 | 1512 | EXPORT_SYMBOL(d_alloc); |
1da177e4 | 1513 | |
e1a24bb0 BF |
1514 | /** |
1515 | * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) | |
1516 | * @sb: the superblock | |
1517 | * @name: qstr of the name | |
1518 | * | |
1519 | * For a filesystem that just pins its dentries in memory and never | |
1520 | * performs lookups at all, return an unhashed IS_ROOT dentry. | |
1521 | */ | |
4b936885 NP |
1522 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1523 | { | |
e1a24bb0 | 1524 | return __d_alloc(sb, name); |
4b936885 NP |
1525 | } |
1526 | EXPORT_SYMBOL(d_alloc_pseudo); | |
1527 | ||
1da177e4 LT |
1528 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1529 | { | |
1530 | struct qstr q; | |
1531 | ||
1532 | q.name = name; | |
1533 | q.len = strlen(name); | |
1534 | q.hash = full_name_hash(q.name, q.len); | |
1535 | return d_alloc(parent, &q); | |
1536 | } | |
ef26ca97 | 1537 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1538 | |
fb045adb NP |
1539 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1540 | { | |
6f7f7caa LT |
1541 | WARN_ON_ONCE(dentry->d_op); |
1542 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | | |
fb045adb NP |
1543 | DCACHE_OP_COMPARE | |
1544 | DCACHE_OP_REVALIDATE | | |
ecf3d1f1 | 1545 | DCACHE_OP_WEAK_REVALIDATE | |
fb045adb NP |
1546 | DCACHE_OP_DELETE )); |
1547 | dentry->d_op = op; | |
1548 | if (!op) | |
1549 | return; | |
1550 | if (op->d_hash) | |
1551 | dentry->d_flags |= DCACHE_OP_HASH; | |
1552 | if (op->d_compare) | |
1553 | dentry->d_flags |= DCACHE_OP_COMPARE; | |
1554 | if (op->d_revalidate) | |
1555 | dentry->d_flags |= DCACHE_OP_REVALIDATE; | |
ecf3d1f1 JL |
1556 | if (op->d_weak_revalidate) |
1557 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; | |
fb045adb NP |
1558 | if (op->d_delete) |
1559 | dentry->d_flags |= DCACHE_OP_DELETE; | |
f0023bc6 SW |
1560 | if (op->d_prune) |
1561 | dentry->d_flags |= DCACHE_OP_PRUNE; | |
fb045adb NP |
1562 | |
1563 | } | |
1564 | EXPORT_SYMBOL(d_set_d_op); | |
1565 | ||
b18825a7 DH |
1566 | static unsigned d_flags_for_inode(struct inode *inode) |
1567 | { | |
1568 | unsigned add_flags = DCACHE_FILE_TYPE; | |
1569 | ||
1570 | if (!inode) | |
1571 | return DCACHE_MISS_TYPE; | |
1572 | ||
1573 | if (S_ISDIR(inode->i_mode)) { | |
1574 | add_flags = DCACHE_DIRECTORY_TYPE; | |
1575 | if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { | |
1576 | if (unlikely(!inode->i_op->lookup)) | |
1577 | add_flags = DCACHE_AUTODIR_TYPE; | |
1578 | else | |
1579 | inode->i_opflags |= IOP_LOOKUP; | |
1580 | } | |
1581 | } else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
1582 | if (unlikely(inode->i_op->follow_link)) | |
1583 | add_flags = DCACHE_SYMLINK_TYPE; | |
1584 | else | |
1585 | inode->i_opflags |= IOP_NOFOLLOW; | |
1586 | } | |
1587 | ||
1588 | if (unlikely(IS_AUTOMOUNT(inode))) | |
1589 | add_flags |= DCACHE_NEED_AUTOMOUNT; | |
1590 | return add_flags; | |
1591 | } | |
1592 | ||
360da900 OH |
1593 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1594 | { | |
b18825a7 DH |
1595 | unsigned add_flags = d_flags_for_inode(inode); |
1596 | ||
b23fb0a6 | 1597 | spin_lock(&dentry->d_lock); |
22213318 | 1598 | __d_set_type(dentry, add_flags); |
b18825a7 | 1599 | if (inode) |
b3d9b7a3 | 1600 | hlist_add_head(&dentry->d_alias, &inode->i_dentry); |
360da900 | 1601 | dentry->d_inode = inode; |
31e6b01f | 1602 | dentry_rcuwalk_barrier(dentry); |
b23fb0a6 | 1603 | spin_unlock(&dentry->d_lock); |
360da900 OH |
1604 | fsnotify_d_instantiate(dentry, inode); |
1605 | } | |
1606 | ||
1da177e4 LT |
1607 | /** |
1608 | * d_instantiate - fill in inode information for a dentry | |
1609 | * @entry: dentry to complete | |
1610 | * @inode: inode to attach to this dentry | |
1611 | * | |
1612 | * Fill in inode information in the entry. | |
1613 | * | |
1614 | * This turns negative dentries into productive full members | |
1615 | * of society. | |
1616 | * | |
1617 | * NOTE! This assumes that the inode count has been incremented | |
1618 | * (or otherwise set) by the caller to indicate that it is now | |
1619 | * in use by the dcache. | |
1620 | */ | |
1621 | ||
1622 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1623 | { | |
b3d9b7a3 | 1624 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
873feea0 NP |
1625 | if (inode) |
1626 | spin_lock(&inode->i_lock); | |
360da900 | 1627 | __d_instantiate(entry, inode); |
873feea0 NP |
1628 | if (inode) |
1629 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
1630 | security_d_instantiate(entry, inode); |
1631 | } | |
ec4f8605 | 1632 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 LT |
1633 | |
1634 | /** | |
1635 | * d_instantiate_unique - instantiate a non-aliased dentry | |
1636 | * @entry: dentry to instantiate | |
1637 | * @inode: inode to attach to this dentry | |
1638 | * | |
1639 | * Fill in inode information in the entry. On success, it returns NULL. | |
1640 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 1641 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1642 | * |
1643 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1644 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1645 | * |
1646 | * This also assumes that the inode count has been incremented | |
1647 | * (or otherwise set) by the caller to indicate that it is now | |
1648 | * in use by the dcache. | |
1da177e4 | 1649 | */ |
770bfad8 DH |
1650 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1651 | struct inode *inode) | |
1da177e4 LT |
1652 | { |
1653 | struct dentry *alias; | |
1654 | int len = entry->d_name.len; | |
1655 | const char *name = entry->d_name.name; | |
1656 | unsigned int hash = entry->d_name.hash; | |
1657 | ||
770bfad8 | 1658 | if (!inode) { |
360da900 | 1659 | __d_instantiate(entry, NULL); |
770bfad8 DH |
1660 | return NULL; |
1661 | } | |
1662 | ||
b67bfe0d | 1663 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
9abca360 NP |
1664 | /* |
1665 | * Don't need alias->d_lock here, because aliases with | |
1666 | * d_parent == entry->d_parent are not subject to name or | |
1667 | * parent changes, because the parent inode i_mutex is held. | |
1668 | */ | |
12f8ad4b | 1669 | if (alias->d_name.hash != hash) |
1da177e4 LT |
1670 | continue; |
1671 | if (alias->d_parent != entry->d_parent) | |
1672 | continue; | |
ee983e89 LT |
1673 | if (alias->d_name.len != len) |
1674 | continue; | |
12f8ad4b | 1675 | if (dentry_cmp(alias, name, len)) |
1da177e4 | 1676 | continue; |
dc0474be | 1677 | __dget(alias); |
1da177e4 LT |
1678 | return alias; |
1679 | } | |
770bfad8 | 1680 | |
360da900 | 1681 | __d_instantiate(entry, inode); |
1da177e4 LT |
1682 | return NULL; |
1683 | } | |
770bfad8 DH |
1684 | |
1685 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1686 | { | |
1687 | struct dentry *result; | |
1688 | ||
b3d9b7a3 | 1689 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
770bfad8 | 1690 | |
873feea0 NP |
1691 | if (inode) |
1692 | spin_lock(&inode->i_lock); | |
770bfad8 | 1693 | result = __d_instantiate_unique(entry, inode); |
873feea0 NP |
1694 | if (inode) |
1695 | spin_unlock(&inode->i_lock); | |
770bfad8 DH |
1696 | |
1697 | if (!result) { | |
1698 | security_d_instantiate(entry, inode); | |
1699 | return NULL; | |
1700 | } | |
1701 | ||
1702 | BUG_ON(!d_unhashed(result)); | |
1703 | iput(inode); | |
1704 | return result; | |
1705 | } | |
1706 | ||
1da177e4 LT |
1707 | EXPORT_SYMBOL(d_instantiate_unique); |
1708 | ||
b70a80e7 MS |
1709 | /** |
1710 | * d_instantiate_no_diralias - instantiate a non-aliased dentry | |
1711 | * @entry: dentry to complete | |
1712 | * @inode: inode to attach to this dentry | |
1713 | * | |
1714 | * Fill in inode information in the entry. If a directory alias is found, then | |
1715 | * return an error (and drop inode). Together with d_materialise_unique() this | |
1716 | * guarantees that a directory inode may never have more than one alias. | |
1717 | */ | |
1718 | int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) | |
1719 | { | |
1720 | BUG_ON(!hlist_unhashed(&entry->d_alias)); | |
1721 | ||
1722 | spin_lock(&inode->i_lock); | |
1723 | if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { | |
1724 | spin_unlock(&inode->i_lock); | |
1725 | iput(inode); | |
1726 | return -EBUSY; | |
1727 | } | |
1728 | __d_instantiate(entry, inode); | |
1729 | spin_unlock(&inode->i_lock); | |
1730 | security_d_instantiate(entry, inode); | |
1731 | ||
1732 | return 0; | |
1733 | } | |
1734 | EXPORT_SYMBOL(d_instantiate_no_diralias); | |
1735 | ||
adc0e91a AV |
1736 | struct dentry *d_make_root(struct inode *root_inode) |
1737 | { | |
1738 | struct dentry *res = NULL; | |
1739 | ||
1740 | if (root_inode) { | |
26fe5750 | 1741 | static const struct qstr name = QSTR_INIT("/", 1); |
adc0e91a AV |
1742 | |
1743 | res = __d_alloc(root_inode->i_sb, &name); | |
1744 | if (res) | |
1745 | d_instantiate(res, root_inode); | |
1746 | else | |
1747 | iput(root_inode); | |
1748 | } | |
1749 | return res; | |
1750 | } | |
1751 | EXPORT_SYMBOL(d_make_root); | |
1752 | ||
d891eedb BF |
1753 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1754 | { | |
1755 | struct dentry *alias; | |
1756 | ||
b3d9b7a3 | 1757 | if (hlist_empty(&inode->i_dentry)) |
d891eedb | 1758 | return NULL; |
b3d9b7a3 | 1759 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias); |
d891eedb BF |
1760 | __dget(alias); |
1761 | return alias; | |
1762 | } | |
1763 | ||
46f72b34 SW |
1764 | /** |
1765 | * d_find_any_alias - find any alias for a given inode | |
1766 | * @inode: inode to find an alias for | |
1767 | * | |
1768 | * If any aliases exist for the given inode, take and return a | |
1769 | * reference for one of them. If no aliases exist, return %NULL. | |
1770 | */ | |
1771 | struct dentry *d_find_any_alias(struct inode *inode) | |
d891eedb BF |
1772 | { |
1773 | struct dentry *de; | |
1774 | ||
1775 | spin_lock(&inode->i_lock); | |
1776 | de = __d_find_any_alias(inode); | |
1777 | spin_unlock(&inode->i_lock); | |
1778 | return de; | |
1779 | } | |
46f72b34 | 1780 | EXPORT_SYMBOL(d_find_any_alias); |
d891eedb | 1781 | |
4ea3ada2 CH |
1782 | /** |
1783 | * d_obtain_alias - find or allocate a dentry for a given inode | |
1784 | * @inode: inode to allocate the dentry for | |
1785 | * | |
1786 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1787 | * similar open by handle operations. The returned dentry may be anonymous, | |
1788 | * or may have a full name (if the inode was already in the cache). | |
1789 | * | |
1790 | * When called on a directory inode, we must ensure that the inode only ever | |
1791 | * has one dentry. If a dentry is found, that is returned instead of | |
1792 | * allocating a new one. | |
1793 | * | |
1794 | * On successful return, the reference to the inode has been transferred | |
44003728 CH |
1795 | * to the dentry. In case of an error the reference on the inode is released. |
1796 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1797 | * be passed in and will be the error will be propagate to the return value, | |
1798 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
4ea3ada2 CH |
1799 | */ |
1800 | struct dentry *d_obtain_alias(struct inode *inode) | |
1801 | { | |
b911a6bd | 1802 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
9308a612 CH |
1803 | struct dentry *tmp; |
1804 | struct dentry *res; | |
b18825a7 | 1805 | unsigned add_flags; |
4ea3ada2 CH |
1806 | |
1807 | if (!inode) | |
44003728 | 1808 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1809 | if (IS_ERR(inode)) |
1810 | return ERR_CAST(inode); | |
1811 | ||
d891eedb | 1812 | res = d_find_any_alias(inode); |
9308a612 CH |
1813 | if (res) |
1814 | goto out_iput; | |
1815 | ||
a4464dbc | 1816 | tmp = __d_alloc(inode->i_sb, &anonstring); |
9308a612 CH |
1817 | if (!tmp) { |
1818 | res = ERR_PTR(-ENOMEM); | |
1819 | goto out_iput; | |
4ea3ada2 | 1820 | } |
b5c84bf6 | 1821 | |
873feea0 | 1822 | spin_lock(&inode->i_lock); |
d891eedb | 1823 | res = __d_find_any_alias(inode); |
9308a612 | 1824 | if (res) { |
873feea0 | 1825 | spin_unlock(&inode->i_lock); |
9308a612 CH |
1826 | dput(tmp); |
1827 | goto out_iput; | |
1828 | } | |
1829 | ||
1830 | /* attach a disconnected dentry */ | |
b18825a7 DH |
1831 | add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED; |
1832 | ||
9308a612 | 1833 | spin_lock(&tmp->d_lock); |
9308a612 | 1834 | tmp->d_inode = inode; |
b18825a7 | 1835 | tmp->d_flags |= add_flags; |
b3d9b7a3 | 1836 | hlist_add_head(&tmp->d_alias, &inode->i_dentry); |
1879fd6a | 1837 | hlist_bl_lock(&tmp->d_sb->s_anon); |
ceb5bdc2 | 1838 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1879fd6a | 1839 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
9308a612 | 1840 | spin_unlock(&tmp->d_lock); |
873feea0 | 1841 | spin_unlock(&inode->i_lock); |
24ff6663 | 1842 | security_d_instantiate(tmp, inode); |
9308a612 | 1843 | |
9308a612 CH |
1844 | return tmp; |
1845 | ||
1846 | out_iput: | |
24ff6663 JB |
1847 | if (res && !IS_ERR(res)) |
1848 | security_d_instantiate(res, inode); | |
9308a612 CH |
1849 | iput(inode); |
1850 | return res; | |
4ea3ada2 | 1851 | } |
adc48720 | 1852 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 LT |
1853 | |
1854 | /** | |
1855 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1856 | * @inode: the inode which may have a disconnected dentry | |
1857 | * @dentry: a negative dentry which we want to point to the inode. | |
1858 | * | |
1859 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1860 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1861 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1862 | * | |
1863 | * This is needed in the lookup routine of any filesystem that is exportable | |
1864 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1865 | * | |
1866 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1867 | * is returned. This matches the expected return value of ->lookup. | |
1868 | * | |
6d4ade98 SW |
1869 | * Cluster filesystems may call this function with a negative, hashed dentry. |
1870 | * In that case, we know that the inode will be a regular file, and also this | |
1871 | * will only occur during atomic_open. So we need to check for the dentry | |
1872 | * being already hashed only in the final case. | |
1da177e4 LT |
1873 | */ |
1874 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1875 | { | |
1876 | struct dentry *new = NULL; | |
1877 | ||
a9049376 AV |
1878 | if (IS_ERR(inode)) |
1879 | return ERR_CAST(inode); | |
1880 | ||
21c0d8fd | 1881 | if (inode && S_ISDIR(inode->i_mode)) { |
873feea0 | 1882 | spin_lock(&inode->i_lock); |
32ba9c3f | 1883 | new = __d_find_alias(inode, 1); |
1da177e4 | 1884 | if (new) { |
32ba9c3f | 1885 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
873feea0 | 1886 | spin_unlock(&inode->i_lock); |
1da177e4 | 1887 | security_d_instantiate(new, inode); |
1da177e4 LT |
1888 | d_move(new, dentry); |
1889 | iput(inode); | |
1890 | } else { | |
873feea0 | 1891 | /* already taking inode->i_lock, so d_add() by hand */ |
360da900 | 1892 | __d_instantiate(dentry, inode); |
873feea0 | 1893 | spin_unlock(&inode->i_lock); |
1da177e4 LT |
1894 | security_d_instantiate(dentry, inode); |
1895 | d_rehash(dentry); | |
1896 | } | |
6d4ade98 SW |
1897 | } else { |
1898 | d_instantiate(dentry, inode); | |
1899 | if (d_unhashed(dentry)) | |
1900 | d_rehash(dentry); | |
1901 | } | |
1da177e4 LT |
1902 | return new; |
1903 | } | |
ec4f8605 | 1904 | EXPORT_SYMBOL(d_splice_alias); |
1da177e4 | 1905 | |
9403540c BN |
1906 | /** |
1907 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
1908 | * @inode: the inode case-insensitive lookup has found | |
1909 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
1910 | * @name: the case-exact name to be associated with the returned dentry | |
1911 | * | |
1912 | * This is to avoid filling the dcache with case-insensitive names to the | |
1913 | * same inode, only the actual correct case is stored in the dcache for | |
1914 | * case-insensitive filesystems. | |
1915 | * | |
1916 | * For a case-insensitive lookup match and if the the case-exact dentry | |
1917 | * already exists in in the dcache, use it and return it. | |
1918 | * | |
1919 | * If no entry exists with the exact case name, allocate new dentry with | |
1920 | * the exact case, and return the spliced entry. | |
1921 | */ | |
e45b590b | 1922 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
1923 | struct qstr *name) |
1924 | { | |
9403540c BN |
1925 | struct dentry *found; |
1926 | struct dentry *new; | |
1927 | ||
b6520c81 CH |
1928 | /* |
1929 | * First check if a dentry matching the name already exists, | |
1930 | * if not go ahead and create it now. | |
1931 | */ | |
9403540c | 1932 | found = d_hash_and_lookup(dentry->d_parent, name); |
4f522a24 AV |
1933 | if (unlikely(IS_ERR(found))) |
1934 | goto err_out; | |
9403540c BN |
1935 | if (!found) { |
1936 | new = d_alloc(dentry->d_parent, name); | |
1937 | if (!new) { | |
4f522a24 | 1938 | found = ERR_PTR(-ENOMEM); |
9403540c BN |
1939 | goto err_out; |
1940 | } | |
b6520c81 | 1941 | |
9403540c BN |
1942 | found = d_splice_alias(inode, new); |
1943 | if (found) { | |
1944 | dput(new); | |
1945 | return found; | |
1946 | } | |
1947 | return new; | |
1948 | } | |
b6520c81 CH |
1949 | |
1950 | /* | |
1951 | * If a matching dentry exists, and it's not negative use it. | |
1952 | * | |
1953 | * Decrement the reference count to balance the iget() done | |
1954 | * earlier on. | |
1955 | */ | |
9403540c BN |
1956 | if (found->d_inode) { |
1957 | if (unlikely(found->d_inode != inode)) { | |
1958 | /* This can't happen because bad inodes are unhashed. */ | |
1959 | BUG_ON(!is_bad_inode(inode)); | |
1960 | BUG_ON(!is_bad_inode(found->d_inode)); | |
1961 | } | |
9403540c BN |
1962 | iput(inode); |
1963 | return found; | |
1964 | } | |
b6520c81 | 1965 | |
9403540c | 1966 | /* |
9403540c | 1967 | * Negative dentry: instantiate it unless the inode is a directory and |
b6520c81 | 1968 | * already has a dentry. |
9403540c | 1969 | */ |
4513d899 AV |
1970 | new = d_splice_alias(inode, found); |
1971 | if (new) { | |
1972 | dput(found); | |
1973 | found = new; | |
9403540c | 1974 | } |
4513d899 | 1975 | return found; |
9403540c BN |
1976 | |
1977 | err_out: | |
1978 | iput(inode); | |
4f522a24 | 1979 | return found; |
9403540c | 1980 | } |
ec4f8605 | 1981 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 | 1982 | |
12f8ad4b LT |
1983 | /* |
1984 | * Do the slow-case of the dentry name compare. | |
1985 | * | |
1986 | * Unlike the dentry_cmp() function, we need to atomically | |
da53be12 | 1987 | * load the name and length information, so that the |
12f8ad4b LT |
1988 | * filesystem can rely on them, and can use the 'name' and |
1989 | * 'len' information without worrying about walking off the | |
1990 | * end of memory etc. | |
1991 | * | |
1992 | * Thus the read_seqcount_retry() and the "duplicate" info | |
1993 | * in arguments (the low-level filesystem should not look | |
1994 | * at the dentry inode or name contents directly, since | |
1995 | * rename can change them while we're in RCU mode). | |
1996 | */ | |
1997 | enum slow_d_compare { | |
1998 | D_COMP_OK, | |
1999 | D_COMP_NOMATCH, | |
2000 | D_COMP_SEQRETRY, | |
2001 | }; | |
2002 | ||
2003 | static noinline enum slow_d_compare slow_dentry_cmp( | |
2004 | const struct dentry *parent, | |
12f8ad4b LT |
2005 | struct dentry *dentry, |
2006 | unsigned int seq, | |
2007 | const struct qstr *name) | |
2008 | { | |
2009 | int tlen = dentry->d_name.len; | |
2010 | const char *tname = dentry->d_name.name; | |
12f8ad4b LT |
2011 | |
2012 | if (read_seqcount_retry(&dentry->d_seq, seq)) { | |
2013 | cpu_relax(); | |
2014 | return D_COMP_SEQRETRY; | |
2015 | } | |
da53be12 | 2016 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
12f8ad4b LT |
2017 | return D_COMP_NOMATCH; |
2018 | return D_COMP_OK; | |
2019 | } | |
2020 | ||
31e6b01f NP |
2021 | /** |
2022 | * __d_lookup_rcu - search for a dentry (racy, store-free) | |
2023 | * @parent: parent dentry | |
2024 | * @name: qstr of name we wish to find | |
1f1e6e52 | 2025 | * @seqp: returns d_seq value at the point where the dentry was found |
31e6b01f NP |
2026 | * Returns: dentry, or NULL |
2027 | * | |
2028 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name | |
2029 | * resolution (store-free path walking) design described in | |
2030 | * Documentation/filesystems/path-lookup.txt. | |
2031 | * | |
2032 | * This is not to be used outside core vfs. | |
2033 | * | |
2034 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock | |
2035 | * held, and rcu_read_lock held. The returned dentry must not be stored into | |
2036 | * without taking d_lock and checking d_seq sequence count against @seq | |
2037 | * returned here. | |
2038 | * | |
15570086 | 2039 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
31e6b01f NP |
2040 | * function. |
2041 | * | |
2042 | * Alternatively, __d_lookup_rcu may be called again to look up the child of | |
2043 | * the returned dentry, so long as its parent's seqlock is checked after the | |
2044 | * child is looked up. Thus, an interlocking stepping of sequence lock checks | |
2045 | * is formed, giving integrity down the path walk. | |
12f8ad4b LT |
2046 | * |
2047 | * NOTE! The caller *has* to check the resulting dentry against the sequence | |
2048 | * number we've returned before using any of the resulting dentry state! | |
31e6b01f | 2049 | */ |
8966be90 LT |
2050 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
2051 | const struct qstr *name, | |
da53be12 | 2052 | unsigned *seqp) |
31e6b01f | 2053 | { |
26fe5750 | 2054 | u64 hashlen = name->hash_len; |
31e6b01f | 2055 | const unsigned char *str = name->name; |
26fe5750 | 2056 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
ceb5bdc2 | 2057 | struct hlist_bl_node *node; |
31e6b01f NP |
2058 | struct dentry *dentry; |
2059 | ||
2060 | /* | |
2061 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2062 | * required to prevent single threaded performance regressions | |
2063 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2064 | * Keep the two functions in sync. | |
2065 | */ | |
2066 | ||
2067 | /* | |
2068 | * The hash list is protected using RCU. | |
2069 | * | |
2070 | * Carefully use d_seq when comparing a candidate dentry, to avoid | |
2071 | * races with d_move(). | |
2072 | * | |
2073 | * It is possible that concurrent renames can mess up our list | |
2074 | * walk here and result in missing our dentry, resulting in the | |
2075 | * false-negative result. d_lookup() protects against concurrent | |
2076 | * renames using rename_lock seqlock. | |
2077 | * | |
b0a4bb83 | 2078 | * See Documentation/filesystems/path-lookup.txt for more details. |
31e6b01f | 2079 | */ |
b07ad996 | 2080 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
8966be90 | 2081 | unsigned seq; |
31e6b01f | 2082 | |
31e6b01f | 2083 | seqretry: |
12f8ad4b LT |
2084 | /* |
2085 | * The dentry sequence count protects us from concurrent | |
da53be12 | 2086 | * renames, and thus protects parent and name fields. |
12f8ad4b LT |
2087 | * |
2088 | * The caller must perform a seqcount check in order | |
da53be12 | 2089 | * to do anything useful with the returned dentry. |
12f8ad4b LT |
2090 | * |
2091 | * NOTE! We do a "raw" seqcount_begin here. That means that | |
2092 | * we don't wait for the sequence count to stabilize if it | |
2093 | * is in the middle of a sequence change. If we do the slow | |
2094 | * dentry compare, we will do seqretries until it is stable, | |
2095 | * and if we end up with a successful lookup, we actually | |
2096 | * want to exit RCU lookup anyway. | |
2097 | */ | |
2098 | seq = raw_seqcount_begin(&dentry->d_seq); | |
31e6b01f NP |
2099 | if (dentry->d_parent != parent) |
2100 | continue; | |
2e321806 LT |
2101 | if (d_unhashed(dentry)) |
2102 | continue; | |
12f8ad4b | 2103 | |
830c0f0e | 2104 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
26fe5750 LT |
2105 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
2106 | continue; | |
da53be12 LT |
2107 | *seqp = seq; |
2108 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { | |
12f8ad4b LT |
2109 | case D_COMP_OK: |
2110 | return dentry; | |
2111 | case D_COMP_NOMATCH: | |
31e6b01f | 2112 | continue; |
12f8ad4b LT |
2113 | default: |
2114 | goto seqretry; | |
2115 | } | |
31e6b01f | 2116 | } |
12f8ad4b | 2117 | |
26fe5750 | 2118 | if (dentry->d_name.hash_len != hashlen) |
ee983e89 | 2119 | continue; |
da53be12 | 2120 | *seqp = seq; |
26fe5750 | 2121 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
12f8ad4b | 2122 | return dentry; |
31e6b01f NP |
2123 | } |
2124 | return NULL; | |
2125 | } | |
2126 | ||
1da177e4 LT |
2127 | /** |
2128 | * d_lookup - search for a dentry | |
2129 | * @parent: parent dentry | |
2130 | * @name: qstr of name we wish to find | |
b04f784e | 2131 | * Returns: dentry, or NULL |
1da177e4 | 2132 | * |
b04f784e NP |
2133 | * d_lookup searches the children of the parent dentry for the name in |
2134 | * question. If the dentry is found its reference count is incremented and the | |
2135 | * dentry is returned. The caller must use dput to free the entry when it has | |
2136 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 2137 | */ |
da2d8455 | 2138 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 | 2139 | { |
31e6b01f | 2140 | struct dentry *dentry; |
949854d0 | 2141 | unsigned seq; |
1da177e4 LT |
2142 | |
2143 | do { | |
2144 | seq = read_seqbegin(&rename_lock); | |
2145 | dentry = __d_lookup(parent, name); | |
2146 | if (dentry) | |
2147 | break; | |
2148 | } while (read_seqretry(&rename_lock, seq)); | |
2149 | return dentry; | |
2150 | } | |
ec4f8605 | 2151 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 2152 | |
31e6b01f | 2153 | /** |
b04f784e NP |
2154 | * __d_lookup - search for a dentry (racy) |
2155 | * @parent: parent dentry | |
2156 | * @name: qstr of name we wish to find | |
2157 | * Returns: dentry, or NULL | |
2158 | * | |
2159 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
2160 | * false-negative result due to unrelated rename activity. | |
2161 | * | |
2162 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
2163 | * however it must be used carefully, eg. with a following d_lookup in | |
2164 | * the case of failure. | |
2165 | * | |
2166 | * __d_lookup callers must be commented. | |
2167 | */ | |
a713ca2a | 2168 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 LT |
2169 | { |
2170 | unsigned int len = name->len; | |
2171 | unsigned int hash = name->hash; | |
2172 | const unsigned char *str = name->name; | |
b07ad996 | 2173 | struct hlist_bl_head *b = d_hash(parent, hash); |
ceb5bdc2 | 2174 | struct hlist_bl_node *node; |
31e6b01f | 2175 | struct dentry *found = NULL; |
665a7583 | 2176 | struct dentry *dentry; |
1da177e4 | 2177 | |
31e6b01f NP |
2178 | /* |
2179 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2180 | * required to prevent single threaded performance regressions | |
2181 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2182 | * Keep the two functions in sync. | |
2183 | */ | |
2184 | ||
b04f784e NP |
2185 | /* |
2186 | * The hash list is protected using RCU. | |
2187 | * | |
2188 | * Take d_lock when comparing a candidate dentry, to avoid races | |
2189 | * with d_move(). | |
2190 | * | |
2191 | * It is possible that concurrent renames can mess up our list | |
2192 | * walk here and result in missing our dentry, resulting in the | |
2193 | * false-negative result. d_lookup() protects against concurrent | |
2194 | * renames using rename_lock seqlock. | |
2195 | * | |
b0a4bb83 | 2196 | * See Documentation/filesystems/path-lookup.txt for more details. |
b04f784e | 2197 | */ |
1da177e4 LT |
2198 | rcu_read_lock(); |
2199 | ||
b07ad996 | 2200 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1da177e4 | 2201 | |
1da177e4 LT |
2202 | if (dentry->d_name.hash != hash) |
2203 | continue; | |
1da177e4 LT |
2204 | |
2205 | spin_lock(&dentry->d_lock); | |
1da177e4 LT |
2206 | if (dentry->d_parent != parent) |
2207 | goto next; | |
d0185c08 LT |
2208 | if (d_unhashed(dentry)) |
2209 | goto next; | |
2210 | ||
1da177e4 LT |
2211 | /* |
2212 | * It is safe to compare names since d_move() cannot | |
2213 | * change the qstr (protected by d_lock). | |
2214 | */ | |
fb045adb | 2215 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
12f8ad4b LT |
2216 | int tlen = dentry->d_name.len; |
2217 | const char *tname = dentry->d_name.name; | |
da53be12 | 2218 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
1da177e4 LT |
2219 | goto next; |
2220 | } else { | |
ee983e89 LT |
2221 | if (dentry->d_name.len != len) |
2222 | goto next; | |
12f8ad4b | 2223 | if (dentry_cmp(dentry, str, len)) |
1da177e4 LT |
2224 | goto next; |
2225 | } | |
2226 | ||
98474236 | 2227 | dentry->d_lockref.count++; |
d0185c08 | 2228 | found = dentry; |
1da177e4 LT |
2229 | spin_unlock(&dentry->d_lock); |
2230 | break; | |
2231 | next: | |
2232 | spin_unlock(&dentry->d_lock); | |
2233 | } | |
2234 | rcu_read_unlock(); | |
2235 | ||
2236 | return found; | |
2237 | } | |
2238 | ||
3e7e241f EB |
2239 | /** |
2240 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
2241 | * @dir: Directory to search in | |
2242 | * @name: qstr of name we wish to find | |
2243 | * | |
4f522a24 | 2244 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
3e7e241f EB |
2245 | */ |
2246 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
2247 | { | |
3e7e241f EB |
2248 | /* |
2249 | * Check for a fs-specific hash function. Note that we must | |
2250 | * calculate the standard hash first, as the d_op->d_hash() | |
2251 | * routine may choose to leave the hash value unchanged. | |
2252 | */ | |
2253 | name->hash = full_name_hash(name->name, name->len); | |
fb045adb | 2254 | if (dir->d_flags & DCACHE_OP_HASH) { |
da53be12 | 2255 | int err = dir->d_op->d_hash(dir, name); |
4f522a24 AV |
2256 | if (unlikely(err < 0)) |
2257 | return ERR_PTR(err); | |
3e7e241f | 2258 | } |
4f522a24 | 2259 | return d_lookup(dir, name); |
3e7e241f | 2260 | } |
4f522a24 | 2261 | EXPORT_SYMBOL(d_hash_and_lookup); |
3e7e241f | 2262 | |
1da177e4 | 2263 | /** |
786a5e15 | 2264 | * d_validate - verify dentry provided from insecure source (deprecated) |
1da177e4 | 2265 | * @dentry: The dentry alleged to be valid child of @dparent |
ff5fdb61 | 2266 | * @dparent: The parent dentry (known to be valid) |
1da177e4 LT |
2267 | * |
2268 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
2269 | * This is used by ncpfs in its readdir implementation. | |
2270 | * Zero is returned in the dentry is invalid. | |
786a5e15 NP |
2271 | * |
2272 | * This function is slow for big directories, and deprecated, do not use it. | |
1da177e4 | 2273 | */ |
d3a23e16 | 2274 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
1da177e4 | 2275 | { |
786a5e15 | 2276 | struct dentry *child; |
d3a23e16 | 2277 | |
2fd6b7f5 | 2278 | spin_lock(&dparent->d_lock); |
786a5e15 NP |
2279 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
2280 | if (dentry == child) { | |
2fd6b7f5 | 2281 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
dc0474be | 2282 | __dget_dlock(dentry); |
2fd6b7f5 NP |
2283 | spin_unlock(&dentry->d_lock); |
2284 | spin_unlock(&dparent->d_lock); | |
1da177e4 LT |
2285 | return 1; |
2286 | } | |
2287 | } | |
2fd6b7f5 | 2288 | spin_unlock(&dparent->d_lock); |
786a5e15 | 2289 | |
1da177e4 LT |
2290 | return 0; |
2291 | } | |
ec4f8605 | 2292 | EXPORT_SYMBOL(d_validate); |
1da177e4 LT |
2293 | |
2294 | /* | |
2295 | * When a file is deleted, we have two options: | |
2296 | * - turn this dentry into a negative dentry | |
2297 | * - unhash this dentry and free it. | |
2298 | * | |
2299 | * Usually, we want to just turn this into | |
2300 | * a negative dentry, but if anybody else is | |
2301 | * currently using the dentry or the inode | |
2302 | * we can't do that and we fall back on removing | |
2303 | * it from the hash queues and waiting for | |
2304 | * it to be deleted later when it has no users | |
2305 | */ | |
2306 | ||
2307 | /** | |
2308 | * d_delete - delete a dentry | |
2309 | * @dentry: The dentry to delete | |
2310 | * | |
2311 | * Turn the dentry into a negative dentry if possible, otherwise | |
2312 | * remove it from the hash queues so it can be deleted later | |
2313 | */ | |
2314 | ||
2315 | void d_delete(struct dentry * dentry) | |
2316 | { | |
873feea0 | 2317 | struct inode *inode; |
7a91bf7f | 2318 | int isdir = 0; |
1da177e4 LT |
2319 | /* |
2320 | * Are we the only user? | |
2321 | */ | |
357f8e65 | 2322 | again: |
1da177e4 | 2323 | spin_lock(&dentry->d_lock); |
873feea0 NP |
2324 | inode = dentry->d_inode; |
2325 | isdir = S_ISDIR(inode->i_mode); | |
98474236 | 2326 | if (dentry->d_lockref.count == 1) { |
1fe0c023 | 2327 | if (!spin_trylock(&inode->i_lock)) { |
357f8e65 NP |
2328 | spin_unlock(&dentry->d_lock); |
2329 | cpu_relax(); | |
2330 | goto again; | |
2331 | } | |
13e3c5e5 | 2332 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
31e6b01f | 2333 | dentry_unlink_inode(dentry); |
7a91bf7f | 2334 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
2335 | return; |
2336 | } | |
2337 | ||
2338 | if (!d_unhashed(dentry)) | |
2339 | __d_drop(dentry); | |
2340 | ||
2341 | spin_unlock(&dentry->d_lock); | |
7a91bf7f JM |
2342 | |
2343 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 2344 | } |
ec4f8605 | 2345 | EXPORT_SYMBOL(d_delete); |
1da177e4 | 2346 | |
b07ad996 | 2347 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
1da177e4 | 2348 | { |
ceb5bdc2 | 2349 | BUG_ON(!d_unhashed(entry)); |
1879fd6a | 2350 | hlist_bl_lock(b); |
dea3667b | 2351 | entry->d_flags |= DCACHE_RCUACCESS; |
b07ad996 | 2352 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
1879fd6a | 2353 | hlist_bl_unlock(b); |
1da177e4 LT |
2354 | } |
2355 | ||
770bfad8 DH |
2356 | static void _d_rehash(struct dentry * entry) |
2357 | { | |
2358 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
2359 | } | |
2360 | ||
1da177e4 LT |
2361 | /** |
2362 | * d_rehash - add an entry back to the hash | |
2363 | * @entry: dentry to add to the hash | |
2364 | * | |
2365 | * Adds a dentry to the hash according to its name. | |
2366 | */ | |
2367 | ||
2368 | void d_rehash(struct dentry * entry) | |
2369 | { | |
1da177e4 | 2370 | spin_lock(&entry->d_lock); |
770bfad8 | 2371 | _d_rehash(entry); |
1da177e4 | 2372 | spin_unlock(&entry->d_lock); |
1da177e4 | 2373 | } |
ec4f8605 | 2374 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 2375 | |
fb2d5b86 NP |
2376 | /** |
2377 | * dentry_update_name_case - update case insensitive dentry with a new name | |
2378 | * @dentry: dentry to be updated | |
2379 | * @name: new name | |
2380 | * | |
2381 | * Update a case insensitive dentry with new case of name. | |
2382 | * | |
2383 | * dentry must have been returned by d_lookup with name @name. Old and new | |
2384 | * name lengths must match (ie. no d_compare which allows mismatched name | |
2385 | * lengths). | |
2386 | * | |
2387 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
2388 | * keep renames and concurrent inserts, and readdir(2) away). | |
2389 | */ | |
2390 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
2391 | { | |
7ebfa57f | 2392 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
fb2d5b86 NP |
2393 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2394 | ||
fb2d5b86 | 2395 | spin_lock(&dentry->d_lock); |
31e6b01f | 2396 | write_seqcount_begin(&dentry->d_seq); |
fb2d5b86 | 2397 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
31e6b01f | 2398 | write_seqcount_end(&dentry->d_seq); |
fb2d5b86 | 2399 | spin_unlock(&dentry->d_lock); |
fb2d5b86 NP |
2400 | } |
2401 | EXPORT_SYMBOL(dentry_update_name_case); | |
2402 | ||
1da177e4 LT |
2403 | static void switch_names(struct dentry *dentry, struct dentry *target) |
2404 | { | |
2405 | if (dname_external(target)) { | |
2406 | if (dname_external(dentry)) { | |
2407 | /* | |
2408 | * Both external: swap the pointers | |
2409 | */ | |
9a8d5bb4 | 2410 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
2411 | } else { |
2412 | /* | |
2413 | * dentry:internal, target:external. Steal target's | |
2414 | * storage and make target internal. | |
2415 | */ | |
321bcf92 BF |
2416 | memcpy(target->d_iname, dentry->d_name.name, |
2417 | dentry->d_name.len + 1); | |
1da177e4 LT |
2418 | dentry->d_name.name = target->d_name.name; |
2419 | target->d_name.name = target->d_iname; | |
2420 | } | |
2421 | } else { | |
2422 | if (dname_external(dentry)) { | |
2423 | /* | |
2424 | * dentry:external, target:internal. Give dentry's | |
2425 | * storage to target and make dentry internal | |
2426 | */ | |
2427 | memcpy(dentry->d_iname, target->d_name.name, | |
2428 | target->d_name.len + 1); | |
2429 | target->d_name.name = dentry->d_name.name; | |
2430 | dentry->d_name.name = dentry->d_iname; | |
2431 | } else { | |
2432 | /* | |
da1ce067 | 2433 | * Both are internal. |
1da177e4 | 2434 | */ |
da1ce067 MS |
2435 | unsigned int i; |
2436 | BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); | |
2437 | for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { | |
2438 | swap(((long *) &dentry->d_iname)[i], | |
2439 | ((long *) &target->d_iname)[i]); | |
2440 | } | |
1da177e4 LT |
2441 | } |
2442 | } | |
9a8d5bb4 | 2443 | swap(dentry->d_name.len, target->d_name.len); |
1da177e4 LT |
2444 | } |
2445 | ||
2fd6b7f5 NP |
2446 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2447 | { | |
2448 | /* | |
2449 | * XXXX: do we really need to take target->d_lock? | |
2450 | */ | |
2451 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) | |
2452 | spin_lock(&target->d_parent->d_lock); | |
2453 | else { | |
2454 | if (d_ancestor(dentry->d_parent, target->d_parent)) { | |
2455 | spin_lock(&dentry->d_parent->d_lock); | |
2456 | spin_lock_nested(&target->d_parent->d_lock, | |
2457 | DENTRY_D_LOCK_NESTED); | |
2458 | } else { | |
2459 | spin_lock(&target->d_parent->d_lock); | |
2460 | spin_lock_nested(&dentry->d_parent->d_lock, | |
2461 | DENTRY_D_LOCK_NESTED); | |
2462 | } | |
2463 | } | |
2464 | if (target < dentry) { | |
2465 | spin_lock_nested(&target->d_lock, 2); | |
2466 | spin_lock_nested(&dentry->d_lock, 3); | |
2467 | } else { | |
2468 | spin_lock_nested(&dentry->d_lock, 2); | |
2469 | spin_lock_nested(&target->d_lock, 3); | |
2470 | } | |
2471 | } | |
2472 | ||
2473 | static void dentry_unlock_parents_for_move(struct dentry *dentry, | |
2474 | struct dentry *target) | |
2475 | { | |
2476 | if (target->d_parent != dentry->d_parent) | |
2477 | spin_unlock(&dentry->d_parent->d_lock); | |
2478 | if (target->d_parent != target) | |
2479 | spin_unlock(&target->d_parent->d_lock); | |
2480 | } | |
2481 | ||
1da177e4 | 2482 | /* |
2fd6b7f5 NP |
2483 | * When switching names, the actual string doesn't strictly have to |
2484 | * be preserved in the target - because we're dropping the target | |
2485 | * anyway. As such, we can just do a simple memcpy() to copy over | |
2486 | * the new name before we switch. | |
2487 | * | |
2488 | * Note that we have to be a lot more careful about getting the hash | |
2489 | * switched - we have to switch the hash value properly even if it | |
2490 | * then no longer matches the actual (corrupted) string of the target. | |
2491 | * The hash value has to match the hash queue that the dentry is on.. | |
1da177e4 | 2492 | */ |
9eaef27b | 2493 | /* |
18367501 | 2494 | * __d_move - move a dentry |
1da177e4 LT |
2495 | * @dentry: entry to move |
2496 | * @target: new dentry | |
da1ce067 | 2497 | * @exchange: exchange the two dentries |
1da177e4 LT |
2498 | * |
2499 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2500 | * dcache entries should not be moved in this way. Caller must hold |
2501 | * rename_lock, the i_mutex of the source and target directories, | |
2502 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). | |
1da177e4 | 2503 | */ |
da1ce067 MS |
2504 | static void __d_move(struct dentry *dentry, struct dentry *target, |
2505 | bool exchange) | |
1da177e4 | 2506 | { |
1da177e4 LT |
2507 | if (!dentry->d_inode) |
2508 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
2509 | ||
2fd6b7f5 NP |
2510 | BUG_ON(d_ancestor(dentry, target)); |
2511 | BUG_ON(d_ancestor(target, dentry)); | |
2512 | ||
2fd6b7f5 | 2513 | dentry_lock_for_move(dentry, target); |
1da177e4 | 2514 | |
31e6b01f | 2515 | write_seqcount_begin(&dentry->d_seq); |
1ca7d67c | 2516 | write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); |
31e6b01f | 2517 | |
ceb5bdc2 NP |
2518 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2519 | ||
2520 | /* | |
2521 | * Move the dentry to the target hash queue. Don't bother checking | |
2522 | * for the same hash queue because of how unlikely it is. | |
2523 | */ | |
2524 | __d_drop(dentry); | |
789680d1 | 2525 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
1da177e4 | 2526 | |
da1ce067 MS |
2527 | /* |
2528 | * Unhash the target (d_delete() is not usable here). If exchanging | |
2529 | * the two dentries, then rehash onto the other's hash queue. | |
2530 | */ | |
1da177e4 | 2531 | __d_drop(target); |
da1ce067 MS |
2532 | if (exchange) { |
2533 | __d_rehash(target, | |
2534 | d_hash(dentry->d_parent, dentry->d_name.hash)); | |
2535 | } | |
1da177e4 | 2536 | |
5160ee6f ED |
2537 | list_del(&dentry->d_u.d_child); |
2538 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
2539 | |
2540 | /* Switch the names.. */ | |
2541 | switch_names(dentry, target); | |
9a8d5bb4 | 2542 | swap(dentry->d_name.hash, target->d_name.hash); |
1da177e4 LT |
2543 | |
2544 | /* ... and switch the parents */ | |
2545 | if (IS_ROOT(dentry)) { | |
2546 | dentry->d_parent = target->d_parent; | |
2547 | target->d_parent = target; | |
5160ee6f | 2548 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 | 2549 | } else { |
9a8d5bb4 | 2550 | swap(dentry->d_parent, target->d_parent); |
1da177e4 LT |
2551 | |
2552 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 2553 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
2554 | } |
2555 | ||
5160ee6f | 2556 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2fd6b7f5 | 2557 | |
31e6b01f NP |
2558 | write_seqcount_end(&target->d_seq); |
2559 | write_seqcount_end(&dentry->d_seq); | |
2560 | ||
2fd6b7f5 | 2561 | dentry_unlock_parents_for_move(dentry, target); |
da1ce067 MS |
2562 | if (exchange) |
2563 | fsnotify_d_move(target); | |
1da177e4 | 2564 | spin_unlock(&target->d_lock); |
c32ccd87 | 2565 | fsnotify_d_move(dentry); |
1da177e4 | 2566 | spin_unlock(&dentry->d_lock); |
18367501 AV |
2567 | } |
2568 | ||
2569 | /* | |
2570 | * d_move - move a dentry | |
2571 | * @dentry: entry to move | |
2572 | * @target: new dentry | |
2573 | * | |
2574 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2575 | * dcache entries should not be moved in this way. See the locking |
2576 | * requirements for __d_move. | |
18367501 AV |
2577 | */ |
2578 | void d_move(struct dentry *dentry, struct dentry *target) | |
2579 | { | |
2580 | write_seqlock(&rename_lock); | |
da1ce067 | 2581 | __d_move(dentry, target, false); |
1da177e4 | 2582 | write_sequnlock(&rename_lock); |
9eaef27b | 2583 | } |
ec4f8605 | 2584 | EXPORT_SYMBOL(d_move); |
1da177e4 | 2585 | |
da1ce067 MS |
2586 | /* |
2587 | * d_exchange - exchange two dentries | |
2588 | * @dentry1: first dentry | |
2589 | * @dentry2: second dentry | |
2590 | */ | |
2591 | void d_exchange(struct dentry *dentry1, struct dentry *dentry2) | |
2592 | { | |
2593 | write_seqlock(&rename_lock); | |
2594 | ||
2595 | WARN_ON(!dentry1->d_inode); | |
2596 | WARN_ON(!dentry2->d_inode); | |
2597 | WARN_ON(IS_ROOT(dentry1)); | |
2598 | WARN_ON(IS_ROOT(dentry2)); | |
2599 | ||
2600 | __d_move(dentry1, dentry2, true); | |
2601 | ||
2602 | write_sequnlock(&rename_lock); | |
2603 | } | |
2604 | ||
e2761a11 OH |
2605 | /** |
2606 | * d_ancestor - search for an ancestor | |
2607 | * @p1: ancestor dentry | |
2608 | * @p2: child dentry | |
2609 | * | |
2610 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
2611 | * an ancestor of p2, else NULL. | |
9eaef27b | 2612 | */ |
e2761a11 | 2613 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
2614 | { |
2615 | struct dentry *p; | |
2616 | ||
871c0067 | 2617 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 2618 | if (p->d_parent == p1) |
e2761a11 | 2619 | return p; |
9eaef27b | 2620 | } |
e2761a11 | 2621 | return NULL; |
9eaef27b TM |
2622 | } |
2623 | ||
2624 | /* | |
2625 | * This helper attempts to cope with remotely renamed directories | |
2626 | * | |
2627 | * It assumes that the caller is already holding | |
18367501 | 2628 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
9eaef27b TM |
2629 | * |
2630 | * Note: If ever the locking in lock_rename() changes, then please | |
2631 | * remember to update this too... | |
9eaef27b | 2632 | */ |
873feea0 NP |
2633 | static struct dentry *__d_unalias(struct inode *inode, |
2634 | struct dentry *dentry, struct dentry *alias) | |
9eaef27b TM |
2635 | { |
2636 | struct mutex *m1 = NULL, *m2 = NULL; | |
ee3efa91 | 2637 | struct dentry *ret = ERR_PTR(-EBUSY); |
9eaef27b TM |
2638 | |
2639 | /* If alias and dentry share a parent, then no extra locks required */ | |
2640 | if (alias->d_parent == dentry->d_parent) | |
2641 | goto out_unalias; | |
2642 | ||
9eaef27b | 2643 | /* See lock_rename() */ |
9eaef27b TM |
2644 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2645 | goto out_err; | |
2646 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
2647 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
2648 | goto out_err; | |
2649 | m2 = &alias->d_parent->d_inode->i_mutex; | |
2650 | out_unalias: | |
ee3efa91 | 2651 | if (likely(!d_mountpoint(alias))) { |
da1ce067 | 2652 | __d_move(alias, dentry, false); |
ee3efa91 AV |
2653 | ret = alias; |
2654 | } | |
9eaef27b | 2655 | out_err: |
873feea0 | 2656 | spin_unlock(&inode->i_lock); |
9eaef27b TM |
2657 | if (m2) |
2658 | mutex_unlock(m2); | |
2659 | if (m1) | |
2660 | mutex_unlock(m1); | |
2661 | return ret; | |
2662 | } | |
2663 | ||
770bfad8 DH |
2664 | /* |
2665 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
2666 | * named dentry in place of the dentry to be replaced. | |
2fd6b7f5 | 2667 | * returns with anon->d_lock held! |
770bfad8 DH |
2668 | */ |
2669 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
2670 | { | |
740da42e | 2671 | struct dentry *dparent; |
770bfad8 | 2672 | |
2fd6b7f5 | 2673 | dentry_lock_for_move(anon, dentry); |
770bfad8 | 2674 | |
31e6b01f | 2675 | write_seqcount_begin(&dentry->d_seq); |
1ca7d67c | 2676 | write_seqcount_begin_nested(&anon->d_seq, DENTRY_D_LOCK_NESTED); |
31e6b01f | 2677 | |
770bfad8 | 2678 | dparent = dentry->d_parent; |
770bfad8 | 2679 | |
2fd6b7f5 NP |
2680 | switch_names(dentry, anon); |
2681 | swap(dentry->d_name.hash, anon->d_name.hash); | |
2682 | ||
740da42e AV |
2683 | dentry->d_parent = dentry; |
2684 | list_del_init(&dentry->d_u.d_child); | |
2685 | anon->d_parent = dparent; | |
9ed53b12 | 2686 | list_move(&anon->d_u.d_child, &dparent->d_subdirs); |
770bfad8 | 2687 | |
31e6b01f NP |
2688 | write_seqcount_end(&dentry->d_seq); |
2689 | write_seqcount_end(&anon->d_seq); | |
2690 | ||
2fd6b7f5 NP |
2691 | dentry_unlock_parents_for_move(anon, dentry); |
2692 | spin_unlock(&dentry->d_lock); | |
2693 | ||
2694 | /* anon->d_lock still locked, returns locked */ | |
770bfad8 DH |
2695 | } |
2696 | ||
2697 | /** | |
2698 | * d_materialise_unique - introduce an inode into the tree | |
2699 | * @dentry: candidate dentry | |
2700 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
2701 | * | |
2702 | * Introduces an dentry into the tree, substituting an extant disconnected | |
c46c8877 JL |
2703 | * root directory alias in its place if there is one. Caller must hold the |
2704 | * i_mutex of the parent directory. | |
770bfad8 DH |
2705 | */ |
2706 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
2707 | { | |
9eaef27b | 2708 | struct dentry *actual; |
770bfad8 DH |
2709 | |
2710 | BUG_ON(!d_unhashed(dentry)); | |
2711 | ||
770bfad8 DH |
2712 | if (!inode) { |
2713 | actual = dentry; | |
360da900 | 2714 | __d_instantiate(dentry, NULL); |
357f8e65 NP |
2715 | d_rehash(actual); |
2716 | goto out_nolock; | |
770bfad8 DH |
2717 | } |
2718 | ||
873feea0 | 2719 | spin_lock(&inode->i_lock); |
357f8e65 | 2720 | |
9eaef27b TM |
2721 | if (S_ISDIR(inode->i_mode)) { |
2722 | struct dentry *alias; | |
2723 | ||
2724 | /* Does an aliased dentry already exist? */ | |
32ba9c3f | 2725 | alias = __d_find_alias(inode, 0); |
9eaef27b TM |
2726 | if (alias) { |
2727 | actual = alias; | |
18367501 AV |
2728 | write_seqlock(&rename_lock); |
2729 | ||
2730 | if (d_ancestor(alias, dentry)) { | |
2731 | /* Check for loops */ | |
2732 | actual = ERR_PTR(-ELOOP); | |
b18dafc8 | 2733 | spin_unlock(&inode->i_lock); |
18367501 AV |
2734 | } else if (IS_ROOT(alias)) { |
2735 | /* Is this an anonymous mountpoint that we | |
2736 | * could splice into our tree? */ | |
9eaef27b | 2737 | __d_materialise_dentry(dentry, alias); |
18367501 | 2738 | write_sequnlock(&rename_lock); |
9eaef27b TM |
2739 | __d_drop(alias); |
2740 | goto found; | |
18367501 AV |
2741 | } else { |
2742 | /* Nope, but we must(!) avoid directory | |
b18dafc8 | 2743 | * aliasing. This drops inode->i_lock */ |
18367501 | 2744 | actual = __d_unalias(inode, dentry, alias); |
9eaef27b | 2745 | } |
18367501 | 2746 | write_sequnlock(&rename_lock); |
dd179946 DH |
2747 | if (IS_ERR(actual)) { |
2748 | if (PTR_ERR(actual) == -ELOOP) | |
2749 | pr_warn_ratelimited( | |
2750 | "VFS: Lookup of '%s' in %s %s" | |
2751 | " would have caused loop\n", | |
2752 | dentry->d_name.name, | |
2753 | inode->i_sb->s_type->name, | |
2754 | inode->i_sb->s_id); | |
9eaef27b | 2755 | dput(alias); |
dd179946 | 2756 | } |
9eaef27b TM |
2757 | goto out_nolock; |
2758 | } | |
770bfad8 DH |
2759 | } |
2760 | ||
2761 | /* Add a unique reference */ | |
2762 | actual = __d_instantiate_unique(dentry, inode); | |
2763 | if (!actual) | |
2764 | actual = dentry; | |
357f8e65 NP |
2765 | else |
2766 | BUG_ON(!d_unhashed(actual)); | |
770bfad8 | 2767 | |
770bfad8 DH |
2768 | spin_lock(&actual->d_lock); |
2769 | found: | |
2770 | _d_rehash(actual); | |
2771 | spin_unlock(&actual->d_lock); | |
873feea0 | 2772 | spin_unlock(&inode->i_lock); |
9eaef27b | 2773 | out_nolock: |
770bfad8 DH |
2774 | if (actual == dentry) { |
2775 | security_d_instantiate(dentry, inode); | |
2776 | return NULL; | |
2777 | } | |
2778 | ||
2779 | iput(inode); | |
2780 | return actual; | |
770bfad8 | 2781 | } |
ec4f8605 | 2782 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
770bfad8 | 2783 | |
cdd16d02 | 2784 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
2785 | { |
2786 | *buflen -= namelen; | |
2787 | if (*buflen < 0) | |
2788 | return -ENAMETOOLONG; | |
2789 | *buffer -= namelen; | |
2790 | memcpy(*buffer, str, namelen); | |
2791 | return 0; | |
2792 | } | |
2793 | ||
232d2d60 WL |
2794 | /** |
2795 | * prepend_name - prepend a pathname in front of current buffer pointer | |
18129977 WL |
2796 | * @buffer: buffer pointer |
2797 | * @buflen: allocated length of the buffer | |
2798 | * @name: name string and length qstr structure | |
232d2d60 WL |
2799 | * |
2800 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to | |
2801 | * make sure that either the old or the new name pointer and length are | |
2802 | * fetched. However, there may be mismatch between length and pointer. | |
2803 | * The length cannot be trusted, we need to copy it byte-by-byte until | |
2804 | * the length is reached or a null byte is found. It also prepends "/" at | |
2805 | * the beginning of the name. The sequence number check at the caller will | |
2806 | * retry it again when a d_move() does happen. So any garbage in the buffer | |
2807 | * due to mismatched pointer and length will be discarded. | |
2808 | */ | |
cdd16d02 MS |
2809 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2810 | { | |
232d2d60 WL |
2811 | const char *dname = ACCESS_ONCE(name->name); |
2812 | u32 dlen = ACCESS_ONCE(name->len); | |
2813 | char *p; | |
2814 | ||
232d2d60 | 2815 | *buflen -= dlen + 1; |
e825196d AV |
2816 | if (*buflen < 0) |
2817 | return -ENAMETOOLONG; | |
232d2d60 WL |
2818 | p = *buffer -= dlen + 1; |
2819 | *p++ = '/'; | |
2820 | while (dlen--) { | |
2821 | char c = *dname++; | |
2822 | if (!c) | |
2823 | break; | |
2824 | *p++ = c; | |
2825 | } | |
2826 | return 0; | |
cdd16d02 MS |
2827 | } |
2828 | ||
1da177e4 | 2829 | /** |
208898c1 | 2830 | * prepend_path - Prepend path string to a buffer |
9d1bc601 | 2831 | * @path: the dentry/vfsmount to report |
02125a82 | 2832 | * @root: root vfsmnt/dentry |
f2eb6575 MS |
2833 | * @buffer: pointer to the end of the buffer |
2834 | * @buflen: pointer to buffer length | |
552ce544 | 2835 | * |
18129977 WL |
2836 | * The function will first try to write out the pathname without taking any |
2837 | * lock other than the RCU read lock to make sure that dentries won't go away. | |
2838 | * It only checks the sequence number of the global rename_lock as any change | |
2839 | * in the dentry's d_seq will be preceded by changes in the rename_lock | |
2840 | * sequence number. If the sequence number had been changed, it will restart | |
2841 | * the whole pathname back-tracing sequence again by taking the rename_lock. | |
2842 | * In this case, there is no need to take the RCU read lock as the recursive | |
2843 | * parent pointer references will keep the dentry chain alive as long as no | |
2844 | * rename operation is performed. | |
1da177e4 | 2845 | */ |
02125a82 AV |
2846 | static int prepend_path(const struct path *path, |
2847 | const struct path *root, | |
f2eb6575 | 2848 | char **buffer, int *buflen) |
1da177e4 | 2849 | { |
ede4cebc AV |
2850 | struct dentry *dentry; |
2851 | struct vfsmount *vfsmnt; | |
2852 | struct mount *mnt; | |
f2eb6575 | 2853 | int error = 0; |
48a066e7 | 2854 | unsigned seq, m_seq = 0; |
232d2d60 WL |
2855 | char *bptr; |
2856 | int blen; | |
6092d048 | 2857 | |
48f5ec21 | 2858 | rcu_read_lock(); |
48a066e7 AV |
2859 | restart_mnt: |
2860 | read_seqbegin_or_lock(&mount_lock, &m_seq); | |
2861 | seq = 0; | |
4ec6c2ae | 2862 | rcu_read_lock(); |
232d2d60 WL |
2863 | restart: |
2864 | bptr = *buffer; | |
2865 | blen = *buflen; | |
48a066e7 | 2866 | error = 0; |
ede4cebc AV |
2867 | dentry = path->dentry; |
2868 | vfsmnt = path->mnt; | |
2869 | mnt = real_mount(vfsmnt); | |
232d2d60 | 2870 | read_seqbegin_or_lock(&rename_lock, &seq); |
f2eb6575 | 2871 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
2872 | struct dentry * parent; |
2873 | ||
1da177e4 | 2874 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
48a066e7 | 2875 | struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); |
552ce544 | 2876 | /* Global root? */ |
48a066e7 AV |
2877 | if (mnt != parent) { |
2878 | dentry = ACCESS_ONCE(mnt->mnt_mountpoint); | |
2879 | mnt = parent; | |
232d2d60 WL |
2880 | vfsmnt = &mnt->mnt; |
2881 | continue; | |
2882 | } | |
2883 | /* | |
2884 | * Filesystems needing to implement special "root names" | |
2885 | * should do so with ->d_dname() | |
2886 | */ | |
2887 | if (IS_ROOT(dentry) && | |
2888 | (dentry->d_name.len != 1 || | |
2889 | dentry->d_name.name[0] != '/')) { | |
2890 | WARN(1, "Root dentry has weird name <%.*s>\n", | |
2891 | (int) dentry->d_name.len, | |
2892 | dentry->d_name.name); | |
2893 | } | |
2894 | if (!error) | |
2895 | error = is_mounted(vfsmnt) ? 1 : 2; | |
2896 | break; | |
1da177e4 LT |
2897 | } |
2898 | parent = dentry->d_parent; | |
2899 | prefetch(parent); | |
232d2d60 | 2900 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
f2eb6575 MS |
2901 | if (error) |
2902 | break; | |
2903 | ||
1da177e4 LT |
2904 | dentry = parent; |
2905 | } | |
48f5ec21 AV |
2906 | if (!(seq & 1)) |
2907 | rcu_read_unlock(); | |
2908 | if (need_seqretry(&rename_lock, seq)) { | |
2909 | seq = 1; | |
232d2d60 | 2910 | goto restart; |
48f5ec21 AV |
2911 | } |
2912 | done_seqretry(&rename_lock, seq); | |
4ec6c2ae LZ |
2913 | |
2914 | if (!(m_seq & 1)) | |
2915 | rcu_read_unlock(); | |
48a066e7 AV |
2916 | if (need_seqretry(&mount_lock, m_seq)) { |
2917 | m_seq = 1; | |
2918 | goto restart_mnt; | |
2919 | } | |
2920 | done_seqretry(&mount_lock, m_seq); | |
1da177e4 | 2921 | |
232d2d60 WL |
2922 | if (error >= 0 && bptr == *buffer) { |
2923 | if (--blen < 0) | |
2924 | error = -ENAMETOOLONG; | |
2925 | else | |
2926 | *--bptr = '/'; | |
2927 | } | |
2928 | *buffer = bptr; | |
2929 | *buflen = blen; | |
7ea600b5 | 2930 | return error; |
f2eb6575 | 2931 | } |
be285c71 | 2932 | |
f2eb6575 MS |
2933 | /** |
2934 | * __d_path - return the path of a dentry | |
2935 | * @path: the dentry/vfsmount to report | |
02125a82 | 2936 | * @root: root vfsmnt/dentry |
cd956a1c | 2937 | * @buf: buffer to return value in |
f2eb6575 MS |
2938 | * @buflen: buffer length |
2939 | * | |
ffd1f4ed | 2940 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
2941 | * |
2942 | * Returns a pointer into the buffer or an error code if the | |
2943 | * path was too long. | |
2944 | * | |
be148247 | 2945 | * "buflen" should be positive. |
f2eb6575 | 2946 | * |
02125a82 | 2947 | * If the path is not reachable from the supplied root, return %NULL. |
f2eb6575 | 2948 | */ |
02125a82 AV |
2949 | char *__d_path(const struct path *path, |
2950 | const struct path *root, | |
f2eb6575 MS |
2951 | char *buf, int buflen) |
2952 | { | |
2953 | char *res = buf + buflen; | |
2954 | int error; | |
2955 | ||
2956 | prepend(&res, &buflen, "\0", 1); | |
f2eb6575 | 2957 | error = prepend_path(path, root, &res, &buflen); |
be148247 | 2958 | |
02125a82 AV |
2959 | if (error < 0) |
2960 | return ERR_PTR(error); | |
2961 | if (error > 0) | |
2962 | return NULL; | |
2963 | return res; | |
2964 | } | |
2965 | ||
2966 | char *d_absolute_path(const struct path *path, | |
2967 | char *buf, int buflen) | |
2968 | { | |
2969 | struct path root = {}; | |
2970 | char *res = buf + buflen; | |
2971 | int error; | |
2972 | ||
2973 | prepend(&res, &buflen, "\0", 1); | |
02125a82 | 2974 | error = prepend_path(path, &root, &res, &buflen); |
02125a82 AV |
2975 | |
2976 | if (error > 1) | |
2977 | error = -EINVAL; | |
2978 | if (error < 0) | |
f2eb6575 | 2979 | return ERR_PTR(error); |
f2eb6575 | 2980 | return res; |
1da177e4 LT |
2981 | } |
2982 | ||
ffd1f4ed MS |
2983 | /* |
2984 | * same as __d_path but appends "(deleted)" for unlinked files. | |
2985 | */ | |
02125a82 AV |
2986 | static int path_with_deleted(const struct path *path, |
2987 | const struct path *root, | |
2988 | char **buf, int *buflen) | |
ffd1f4ed MS |
2989 | { |
2990 | prepend(buf, buflen, "\0", 1); | |
2991 | if (d_unlinked(path->dentry)) { | |
2992 | int error = prepend(buf, buflen, " (deleted)", 10); | |
2993 | if (error) | |
2994 | return error; | |
2995 | } | |
2996 | ||
2997 | return prepend_path(path, root, buf, buflen); | |
2998 | } | |
2999 | ||
8df9d1a4 MS |
3000 | static int prepend_unreachable(char **buffer, int *buflen) |
3001 | { | |
3002 | return prepend(buffer, buflen, "(unreachable)", 13); | |
3003 | } | |
3004 | ||
68f0d9d9 LT |
3005 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
3006 | { | |
3007 | unsigned seq; | |
3008 | ||
3009 | do { | |
3010 | seq = read_seqcount_begin(&fs->seq); | |
3011 | *root = fs->root; | |
3012 | } while (read_seqcount_retry(&fs->seq, seq)); | |
3013 | } | |
3014 | ||
a03a8a70 JB |
3015 | /** |
3016 | * d_path - return the path of a dentry | |
cf28b486 | 3017 | * @path: path to report |
a03a8a70 JB |
3018 | * @buf: buffer to return value in |
3019 | * @buflen: buffer length | |
3020 | * | |
3021 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
3022 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
3023 | * | |
52afeefb AV |
3024 | * Returns a pointer into the buffer or an error code if the path was |
3025 | * too long. Note: Callers should use the returned pointer, not the passed | |
3026 | * in buffer, to use the name! The implementation often starts at an offset | |
3027 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 3028 | * |
31f3e0b3 | 3029 | * "buflen" should be positive. |
a03a8a70 | 3030 | */ |
20d4fdc1 | 3031 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 3032 | { |
ffd1f4ed | 3033 | char *res = buf + buflen; |
6ac08c39 | 3034 | struct path root; |
ffd1f4ed | 3035 | int error; |
1da177e4 | 3036 | |
c23fbb6b ED |
3037 | /* |
3038 | * We have various synthetic filesystems that never get mounted. On | |
3039 | * these filesystems dentries are never used for lookup purposes, and | |
3040 | * thus don't need to be hashed. They also don't need a name until a | |
3041 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
3042 | * below allows us to generate a name for these objects on demand: | |
f48cfddc EB |
3043 | * |
3044 | * Some pseudo inodes are mountable. When they are mounted | |
3045 | * path->dentry == path->mnt->mnt_root. In that case don't call d_dname | |
3046 | * and instead have d_path return the mounted path. | |
c23fbb6b | 3047 | */ |
f48cfddc EB |
3048 | if (path->dentry->d_op && path->dentry->d_op->d_dname && |
3049 | (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root)) | |
cf28b486 | 3050 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
c23fbb6b | 3051 | |
68f0d9d9 LT |
3052 | rcu_read_lock(); |
3053 | get_fs_root_rcu(current->fs, &root); | |
02125a82 | 3054 | error = path_with_deleted(path, &root, &res, &buflen); |
68f0d9d9 LT |
3055 | rcu_read_unlock(); |
3056 | ||
02125a82 | 3057 | if (error < 0) |
ffd1f4ed | 3058 | res = ERR_PTR(error); |
1da177e4 LT |
3059 | return res; |
3060 | } | |
ec4f8605 | 3061 | EXPORT_SYMBOL(d_path); |
1da177e4 | 3062 | |
c23fbb6b ED |
3063 | /* |
3064 | * Helper function for dentry_operations.d_dname() members | |
3065 | */ | |
3066 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
3067 | const char *fmt, ...) | |
3068 | { | |
3069 | va_list args; | |
3070 | char temp[64]; | |
3071 | int sz; | |
3072 | ||
3073 | va_start(args, fmt); | |
3074 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
3075 | va_end(args); | |
3076 | ||
3077 | if (sz > sizeof(temp) || sz > buflen) | |
3078 | return ERR_PTR(-ENAMETOOLONG); | |
3079 | ||
3080 | buffer += buflen - sz; | |
3081 | return memcpy(buffer, temp, sz); | |
3082 | } | |
3083 | ||
118b2302 AV |
3084 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
3085 | { | |
3086 | char *end = buffer + buflen; | |
3087 | /* these dentries are never renamed, so d_lock is not needed */ | |
3088 | if (prepend(&end, &buflen, " (deleted)", 11) || | |
232d2d60 | 3089 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
118b2302 AV |
3090 | prepend(&end, &buflen, "/", 1)) |
3091 | end = ERR_PTR(-ENAMETOOLONG); | |
232d2d60 | 3092 | return end; |
118b2302 | 3093 | } |
31bbe16f | 3094 | EXPORT_SYMBOL(simple_dname); |
118b2302 | 3095 | |
6092d048 RP |
3096 | /* |
3097 | * Write full pathname from the root of the filesystem into the buffer. | |
3098 | */ | |
f6500801 | 3099 | static char *__dentry_path(struct dentry *d, char *buf, int buflen) |
6092d048 | 3100 | { |
f6500801 | 3101 | struct dentry *dentry; |
232d2d60 WL |
3102 | char *end, *retval; |
3103 | int len, seq = 0; | |
3104 | int error = 0; | |
6092d048 | 3105 | |
f6500801 AV |
3106 | if (buflen < 2) |
3107 | goto Elong; | |
3108 | ||
48f5ec21 | 3109 | rcu_read_lock(); |
232d2d60 | 3110 | restart: |
f6500801 | 3111 | dentry = d; |
232d2d60 WL |
3112 | end = buf + buflen; |
3113 | len = buflen; | |
3114 | prepend(&end, &len, "\0", 1); | |
6092d048 RP |
3115 | /* Get '/' right */ |
3116 | retval = end-1; | |
3117 | *retval = '/'; | |
232d2d60 | 3118 | read_seqbegin_or_lock(&rename_lock, &seq); |
cdd16d02 MS |
3119 | while (!IS_ROOT(dentry)) { |
3120 | struct dentry *parent = dentry->d_parent; | |
6092d048 | 3121 | |
6092d048 | 3122 | prefetch(parent); |
232d2d60 WL |
3123 | error = prepend_name(&end, &len, &dentry->d_name); |
3124 | if (error) | |
3125 | break; | |
6092d048 RP |
3126 | |
3127 | retval = end; | |
3128 | dentry = parent; | |
3129 | } | |
48f5ec21 AV |
3130 | if (!(seq & 1)) |
3131 | rcu_read_unlock(); | |
3132 | if (need_seqretry(&rename_lock, seq)) { | |
3133 | seq = 1; | |
232d2d60 | 3134 | goto restart; |
48f5ec21 AV |
3135 | } |
3136 | done_seqretry(&rename_lock, seq); | |
232d2d60 WL |
3137 | if (error) |
3138 | goto Elong; | |
c103135c AV |
3139 | return retval; |
3140 | Elong: | |
3141 | return ERR_PTR(-ENAMETOOLONG); | |
3142 | } | |
ec2447c2 NP |
3143 | |
3144 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
3145 | { | |
232d2d60 | 3146 | return __dentry_path(dentry, buf, buflen); |
ec2447c2 NP |
3147 | } |
3148 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
3149 | |
3150 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
3151 | { | |
3152 | char *p = NULL; | |
3153 | char *retval; | |
3154 | ||
c103135c AV |
3155 | if (d_unlinked(dentry)) { |
3156 | p = buf + buflen; | |
3157 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
3158 | goto Elong; | |
3159 | buflen++; | |
3160 | } | |
3161 | retval = __dentry_path(dentry, buf, buflen); | |
c103135c AV |
3162 | if (!IS_ERR(retval) && p) |
3163 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
3164 | return retval; |
3165 | Elong: | |
6092d048 RP |
3166 | return ERR_PTR(-ENAMETOOLONG); |
3167 | } | |
3168 | ||
8b19e341 LT |
3169 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
3170 | struct path *pwd) | |
5762482f | 3171 | { |
8b19e341 LT |
3172 | unsigned seq; |
3173 | ||
3174 | do { | |
3175 | seq = read_seqcount_begin(&fs->seq); | |
3176 | *root = fs->root; | |
3177 | *pwd = fs->pwd; | |
3178 | } while (read_seqcount_retry(&fs->seq, seq)); | |
5762482f LT |
3179 | } |
3180 | ||
1da177e4 LT |
3181 | /* |
3182 | * NOTE! The user-level library version returns a | |
3183 | * character pointer. The kernel system call just | |
3184 | * returns the length of the buffer filled (which | |
3185 | * includes the ending '\0' character), or a negative | |
3186 | * error value. So libc would do something like | |
3187 | * | |
3188 | * char *getcwd(char * buf, size_t size) | |
3189 | * { | |
3190 | * int retval; | |
3191 | * | |
3192 | * retval = sys_getcwd(buf, size); | |
3193 | * if (retval >= 0) | |
3194 | * return buf; | |
3195 | * errno = -retval; | |
3196 | * return NULL; | |
3197 | * } | |
3198 | */ | |
3cdad428 | 3199 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 3200 | { |
552ce544 | 3201 | int error; |
6ac08c39 | 3202 | struct path pwd, root; |
3272c544 | 3203 | char *page = __getname(); |
1da177e4 LT |
3204 | |
3205 | if (!page) | |
3206 | return -ENOMEM; | |
3207 | ||
8b19e341 LT |
3208 | rcu_read_lock(); |
3209 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); | |
1da177e4 | 3210 | |
552ce544 | 3211 | error = -ENOENT; |
f3da392e | 3212 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 3213 | unsigned long len; |
3272c544 LT |
3214 | char *cwd = page + PATH_MAX; |
3215 | int buflen = PATH_MAX; | |
1da177e4 | 3216 | |
8df9d1a4 | 3217 | prepend(&cwd, &buflen, "\0", 1); |
02125a82 | 3218 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
ff812d72 | 3219 | rcu_read_unlock(); |
552ce544 | 3220 | |
02125a82 | 3221 | if (error < 0) |
552ce544 LT |
3222 | goto out; |
3223 | ||
8df9d1a4 | 3224 | /* Unreachable from current root */ |
02125a82 | 3225 | if (error > 0) { |
8df9d1a4 MS |
3226 | error = prepend_unreachable(&cwd, &buflen); |
3227 | if (error) | |
3228 | goto out; | |
3229 | } | |
3230 | ||
552ce544 | 3231 | error = -ERANGE; |
3272c544 | 3232 | len = PATH_MAX + page - cwd; |
552ce544 LT |
3233 | if (len <= size) { |
3234 | error = len; | |
3235 | if (copy_to_user(buf, cwd, len)) | |
3236 | error = -EFAULT; | |
3237 | } | |
949854d0 | 3238 | } else { |
ff812d72 | 3239 | rcu_read_unlock(); |
949854d0 | 3240 | } |
1da177e4 LT |
3241 | |
3242 | out: | |
3272c544 | 3243 | __putname(page); |
1da177e4 LT |
3244 | return error; |
3245 | } | |
3246 | ||
3247 | /* | |
3248 | * Test whether new_dentry is a subdirectory of old_dentry. | |
3249 | * | |
3250 | * Trivially implemented using the dcache structure | |
3251 | */ | |
3252 | ||
3253 | /** | |
3254 | * is_subdir - is new dentry a subdirectory of old_dentry | |
3255 | * @new_dentry: new dentry | |
3256 | * @old_dentry: old dentry | |
3257 | * | |
3258 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
3259 | * Returns 0 otherwise. | |
3260 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
3261 | */ | |
3262 | ||
e2761a11 | 3263 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 LT |
3264 | { |
3265 | int result; | |
949854d0 | 3266 | unsigned seq; |
1da177e4 | 3267 | |
e2761a11 OH |
3268 | if (new_dentry == old_dentry) |
3269 | return 1; | |
3270 | ||
e2761a11 | 3271 | do { |
1da177e4 | 3272 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 3273 | seq = read_seqbegin(&rename_lock); |
949854d0 NP |
3274 | /* |
3275 | * Need rcu_readlock to protect against the d_parent trashing | |
3276 | * due to d_move | |
3277 | */ | |
3278 | rcu_read_lock(); | |
e2761a11 | 3279 | if (d_ancestor(old_dentry, new_dentry)) |
1da177e4 | 3280 | result = 1; |
e2761a11 OH |
3281 | else |
3282 | result = 0; | |
949854d0 | 3283 | rcu_read_unlock(); |
1da177e4 | 3284 | } while (read_seqretry(&rename_lock, seq)); |
1da177e4 LT |
3285 | |
3286 | return result; | |
3287 | } | |
3288 | ||
db14fc3a | 3289 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
1da177e4 | 3290 | { |
db14fc3a MS |
3291 | struct dentry *root = data; |
3292 | if (dentry != root) { | |
3293 | if (d_unhashed(dentry) || !dentry->d_inode) | |
3294 | return D_WALK_SKIP; | |
1da177e4 | 3295 | |
01ddc4ed MS |
3296 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
3297 | dentry->d_flags |= DCACHE_GENOCIDE; | |
3298 | dentry->d_lockref.count--; | |
3299 | } | |
1da177e4 | 3300 | } |
db14fc3a MS |
3301 | return D_WALK_CONTINUE; |
3302 | } | |
58db63d0 | 3303 | |
db14fc3a MS |
3304 | void d_genocide(struct dentry *parent) |
3305 | { | |
3306 | d_walk(parent, parent, d_genocide_kill, NULL); | |
1da177e4 LT |
3307 | } |
3308 | ||
60545d0d | 3309 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
1da177e4 | 3310 | { |
60545d0d AV |
3311 | inode_dec_link_count(inode); |
3312 | BUG_ON(dentry->d_name.name != dentry->d_iname || | |
3313 | !hlist_unhashed(&dentry->d_alias) || | |
3314 | !d_unlinked(dentry)); | |
3315 | spin_lock(&dentry->d_parent->d_lock); | |
3316 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
3317 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", | |
3318 | (unsigned long long)inode->i_ino); | |
3319 | spin_unlock(&dentry->d_lock); | |
3320 | spin_unlock(&dentry->d_parent->d_lock); | |
3321 | d_instantiate(dentry, inode); | |
1da177e4 | 3322 | } |
60545d0d | 3323 | EXPORT_SYMBOL(d_tmpfile); |
1da177e4 LT |
3324 | |
3325 | static __initdata unsigned long dhash_entries; | |
3326 | static int __init set_dhash_entries(char *str) | |
3327 | { | |
3328 | if (!str) | |
3329 | return 0; | |
3330 | dhash_entries = simple_strtoul(str, &str, 0); | |
3331 | return 1; | |
3332 | } | |
3333 | __setup("dhash_entries=", set_dhash_entries); | |
3334 | ||
3335 | static void __init dcache_init_early(void) | |
3336 | { | |
074b8517 | 3337 | unsigned int loop; |
1da177e4 LT |
3338 | |
3339 | /* If hashes are distributed across NUMA nodes, defer | |
3340 | * hash allocation until vmalloc space is available. | |
3341 | */ | |
3342 | if (hashdist) | |
3343 | return; | |
3344 | ||
3345 | dentry_hashtable = | |
3346 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3347 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3348 | dhash_entries, |
3349 | 13, | |
3350 | HASH_EARLY, | |
3351 | &d_hash_shift, | |
3352 | &d_hash_mask, | |
31fe62b9 | 3353 | 0, |
1da177e4 LT |
3354 | 0); |
3355 | ||
074b8517 | 3356 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3357 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3358 | } |
3359 | ||
74bf17cf | 3360 | static void __init dcache_init(void) |
1da177e4 | 3361 | { |
074b8517 | 3362 | unsigned int loop; |
1da177e4 LT |
3363 | |
3364 | /* | |
3365 | * A constructor could be added for stable state like the lists, | |
3366 | * but it is probably not worth it because of the cache nature | |
3367 | * of the dcache. | |
3368 | */ | |
0a31bd5f CL |
3369 | dentry_cache = KMEM_CACHE(dentry, |
3370 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 LT |
3371 | |
3372 | /* Hash may have been set up in dcache_init_early */ | |
3373 | if (!hashdist) | |
3374 | return; | |
3375 | ||
3376 | dentry_hashtable = | |
3377 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3378 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3379 | dhash_entries, |
3380 | 13, | |
3381 | 0, | |
3382 | &d_hash_shift, | |
3383 | &d_hash_mask, | |
31fe62b9 | 3384 | 0, |
1da177e4 LT |
3385 | 0); |
3386 | ||
074b8517 | 3387 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3388 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3389 | } |
3390 | ||
3391 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 3392 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 3393 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 3394 | |
1da177e4 LT |
3395 | EXPORT_SYMBOL(d_genocide); |
3396 | ||
1da177e4 LT |
3397 | void __init vfs_caches_init_early(void) |
3398 | { | |
3399 | dcache_init_early(); | |
3400 | inode_init_early(); | |
3401 | } | |
3402 | ||
3403 | void __init vfs_caches_init(unsigned long mempages) | |
3404 | { | |
3405 | unsigned long reserve; | |
3406 | ||
3407 | /* Base hash sizes on available memory, with a reserve equal to | |
3408 | 150% of current kernel size */ | |
3409 | ||
3410 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
3411 | mempages -= reserve; | |
3412 | ||
3413 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 3414 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 3415 | |
74bf17cf DC |
3416 | dcache_init(); |
3417 | inode_init(); | |
1da177e4 | 3418 | files_init(mempages); |
74bf17cf | 3419 | mnt_init(); |
1da177e4 LT |
3420 | bdev_cache_init(); |
3421 | chrdev_init(); | |
3422 | } |