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Commit | Line | Data |
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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> |
07f3f05c | 40 | #include "internal.h" |
b2dba1af | 41 | #include "mount.h" |
1da177e4 | 42 | |
789680d1 NP |
43 | /* |
44 | * Usage: | |
873feea0 NP |
45 | * dcache->d_inode->i_lock protects: |
46 | * - i_dentry, d_alias, d_inode of aliases | |
ceb5bdc2 NP |
47 | * dcache_hash_bucket lock protects: |
48 | * - the dcache hash table | |
49 | * s_anon bl list spinlock protects: | |
50 | * - the s_anon list (see __d_drop) | |
23044507 NP |
51 | * dcache_lru_lock protects: |
52 | * - the dcache lru lists and counters | |
53 | * d_lock protects: | |
54 | * - d_flags | |
55 | * - d_name | |
56 | * - d_lru | |
b7ab39f6 | 57 | * - d_count |
da502956 | 58 | * - d_unhashed() |
2fd6b7f5 NP |
59 | * - d_parent and d_subdirs |
60 | * - childrens' d_child and d_parent | |
b23fb0a6 | 61 | * - d_alias, d_inode |
789680d1 NP |
62 | * |
63 | * Ordering: | |
873feea0 | 64 | * dentry->d_inode->i_lock |
b5c84bf6 NP |
65 | * dentry->d_lock |
66 | * dcache_lru_lock | |
ceb5bdc2 NP |
67 | * dcache_hash_bucket lock |
68 | * s_anon lock | |
789680d1 | 69 | * |
da502956 NP |
70 | * If there is an ancestor relationship: |
71 | * dentry->d_parent->...->d_parent->d_lock | |
72 | * ... | |
73 | * dentry->d_parent->d_lock | |
74 | * dentry->d_lock | |
75 | * | |
76 | * If no ancestor relationship: | |
789680d1 NP |
77 | * if (dentry1 < dentry2) |
78 | * dentry1->d_lock | |
79 | * dentry2->d_lock | |
80 | */ | |
fa3536cc | 81 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
82 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
83 | ||
23044507 | 84 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); |
74c3cbe3 | 85 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 | 86 | |
949854d0 | 87 | EXPORT_SYMBOL(rename_lock); |
1da177e4 | 88 | |
e18b890b | 89 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 | 90 | |
232d2d60 WL |
91 | /** |
92 | * read_seqbegin_or_lock - begin a sequence number check or locking block | |
93 | * lock: sequence lock | |
94 | * seq : sequence number to be checked | |
95 | * | |
96 | * First try it once optimistically without taking the lock. If that fails, | |
97 | * take the lock. The sequence number is also used as a marker for deciding | |
98 | * whether to be a reader (even) or writer (odd). | |
99 | * N.B. seq must be initialized to an even number to begin with. | |
100 | */ | |
101 | static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq) | |
102 | { | |
103 | if (!(*seq & 1)) { /* Even */ | |
104 | *seq = read_seqbegin(lock); | |
105 | rcu_read_lock(); | |
106 | } else /* Odd */ | |
107 | write_seqlock(lock); | |
108 | } | |
109 | ||
110 | /** | |
111 | * read_seqretry_or_unlock - end a seqretry or lock block & return retry status | |
112 | * lock : sequence lock | |
113 | * seq : sequence number | |
114 | * Return: 1 to retry operation again, 0 to continue | |
115 | */ | |
116 | static inline int read_seqretry_or_unlock(seqlock_t *lock, int *seq) | |
117 | { | |
118 | if (!(*seq & 1)) { /* Even */ | |
119 | rcu_read_unlock(); | |
120 | if (read_seqretry(lock, *seq)) { | |
121 | (*seq)++; /* Take writer lock */ | |
122 | return 1; | |
123 | } | |
124 | } else /* Odd */ | |
125 | write_sequnlock(lock); | |
126 | return 0; | |
127 | } | |
128 | ||
1da177e4 LT |
129 | /* |
130 | * This is the single most critical data structure when it comes | |
131 | * to the dcache: the hashtable for lookups. Somebody should try | |
132 | * to make this good - I've just made it work. | |
133 | * | |
134 | * This hash-function tries to avoid losing too many bits of hash | |
135 | * information, yet avoid using a prime hash-size or similar. | |
136 | */ | |
137 | #define D_HASHBITS d_hash_shift | |
138 | #define D_HASHMASK d_hash_mask | |
139 | ||
fa3536cc ED |
140 | static unsigned int d_hash_mask __read_mostly; |
141 | static unsigned int d_hash_shift __read_mostly; | |
ceb5bdc2 | 142 | |
b07ad996 | 143 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
ceb5bdc2 | 144 | |
8966be90 | 145 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
6d7d1a0d | 146 | unsigned int hash) |
ceb5bdc2 | 147 | { |
6d7d1a0d LT |
148 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
149 | hash = hash + (hash >> D_HASHBITS); | |
ceb5bdc2 NP |
150 | return dentry_hashtable + (hash & D_HASHMASK); |
151 | } | |
152 | ||
1da177e4 LT |
153 | /* Statistics gathering. */ |
154 | struct dentry_stat_t dentry_stat = { | |
155 | .age_limit = 45, | |
156 | }; | |
157 | ||
3e880fb5 | 158 | static DEFINE_PER_CPU(unsigned int, nr_dentry); |
312d3ca8 CH |
159 | |
160 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
3e880fb5 NP |
161 | static int get_nr_dentry(void) |
162 | { | |
163 | int i; | |
164 | int sum = 0; | |
165 | for_each_possible_cpu(i) | |
166 | sum += per_cpu(nr_dentry, i); | |
167 | return sum < 0 ? 0 : sum; | |
168 | } | |
169 | ||
312d3ca8 CH |
170 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
171 | size_t *lenp, loff_t *ppos) | |
172 | { | |
3e880fb5 | 173 | dentry_stat.nr_dentry = get_nr_dentry(); |
312d3ca8 CH |
174 | return proc_dointvec(table, write, buffer, lenp, ppos); |
175 | } | |
176 | #endif | |
177 | ||
5483f18e LT |
178 | /* |
179 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. | |
180 | * The strings are both count bytes long, and count is non-zero. | |
181 | */ | |
e419b4cc LT |
182 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
183 | ||
184 | #include <asm/word-at-a-time.h> | |
185 | /* | |
186 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a | |
187 | * aligned allocation for this particular component. We don't | |
188 | * strictly need the load_unaligned_zeropad() safety, but it | |
189 | * doesn't hurt either. | |
190 | * | |
191 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do | |
192 | * need the careful unaligned handling. | |
193 | */ | |
94753db5 | 194 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
5483f18e | 195 | { |
bfcfaa77 | 196 | unsigned long a,b,mask; |
bfcfaa77 LT |
197 | |
198 | for (;;) { | |
12f8ad4b | 199 | a = *(unsigned long *)cs; |
e419b4cc | 200 | b = load_unaligned_zeropad(ct); |
bfcfaa77 LT |
201 | if (tcount < sizeof(unsigned long)) |
202 | break; | |
203 | if (unlikely(a != b)) | |
204 | return 1; | |
205 | cs += sizeof(unsigned long); | |
206 | ct += sizeof(unsigned long); | |
207 | tcount -= sizeof(unsigned long); | |
208 | if (!tcount) | |
209 | return 0; | |
210 | } | |
211 | mask = ~(~0ul << tcount*8); | |
212 | return unlikely(!!((a ^ b) & mask)); | |
e419b4cc LT |
213 | } |
214 | ||
bfcfaa77 | 215 | #else |
e419b4cc | 216 | |
94753db5 | 217 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
e419b4cc | 218 | { |
5483f18e LT |
219 | do { |
220 | if (*cs != *ct) | |
221 | return 1; | |
222 | cs++; | |
223 | ct++; | |
224 | tcount--; | |
225 | } while (tcount); | |
226 | return 0; | |
227 | } | |
228 | ||
e419b4cc LT |
229 | #endif |
230 | ||
94753db5 LT |
231 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
232 | { | |
6326c71f | 233 | const unsigned char *cs; |
94753db5 LT |
234 | /* |
235 | * Be careful about RCU walk racing with rename: | |
236 | * use ACCESS_ONCE to fetch the name pointer. | |
237 | * | |
238 | * NOTE! Even if a rename will mean that the length | |
239 | * was not loaded atomically, we don't care. The | |
240 | * RCU walk will check the sequence count eventually, | |
241 | * and catch it. And we won't overrun the buffer, | |
242 | * because we're reading the name pointer atomically, | |
243 | * and a dentry name is guaranteed to be properly | |
244 | * terminated with a NUL byte. | |
245 | * | |
246 | * End result: even if 'len' is wrong, we'll exit | |
247 | * early because the data cannot match (there can | |
248 | * be no NUL in the ct/tcount data) | |
249 | */ | |
6326c71f LT |
250 | cs = ACCESS_ONCE(dentry->d_name.name); |
251 | smp_read_barrier_depends(); | |
252 | return dentry_string_cmp(cs, ct, tcount); | |
94753db5 LT |
253 | } |
254 | ||
9c82ab9c | 255 | static void __d_free(struct rcu_head *head) |
1da177e4 | 256 | { |
9c82ab9c CH |
257 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
258 | ||
b3d9b7a3 | 259 | WARN_ON(!hlist_unhashed(&dentry->d_alias)); |
1da177e4 LT |
260 | if (dname_external(dentry)) |
261 | kfree(dentry->d_name.name); | |
262 | kmem_cache_free(dentry_cache, dentry); | |
263 | } | |
264 | ||
265 | /* | |
b5c84bf6 | 266 | * no locks, please. |
1da177e4 LT |
267 | */ |
268 | static void d_free(struct dentry *dentry) | |
269 | { | |
98474236 | 270 | BUG_ON(dentry->d_lockref.count); |
3e880fb5 | 271 | this_cpu_dec(nr_dentry); |
1da177e4 LT |
272 | if (dentry->d_op && dentry->d_op->d_release) |
273 | dentry->d_op->d_release(dentry); | |
312d3ca8 | 274 | |
dea3667b LT |
275 | /* if dentry was never visible to RCU, immediate free is OK */ |
276 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) | |
9c82ab9c | 277 | __d_free(&dentry->d_u.d_rcu); |
b3423415 | 278 | else |
9c82ab9c | 279 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
1da177e4 LT |
280 | } |
281 | ||
31e6b01f NP |
282 | /** |
283 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups | |
ff5fdb61 | 284 | * @dentry: the target dentry |
31e6b01f NP |
285 | * After this call, in-progress rcu-walk path lookup will fail. This |
286 | * should be called after unhashing, and after changing d_inode (if | |
287 | * the dentry has not already been unhashed). | |
288 | */ | |
289 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) | |
290 | { | |
291 | assert_spin_locked(&dentry->d_lock); | |
292 | /* Go through a barrier */ | |
293 | write_seqcount_barrier(&dentry->d_seq); | |
294 | } | |
295 | ||
1da177e4 LT |
296 | /* |
297 | * Release the dentry's inode, using the filesystem | |
31e6b01f NP |
298 | * d_iput() operation if defined. Dentry has no refcount |
299 | * and is unhashed. | |
1da177e4 | 300 | */ |
858119e1 | 301 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 | 302 | __releases(dentry->d_lock) |
873feea0 | 303 | __releases(dentry->d_inode->i_lock) |
1da177e4 LT |
304 | { |
305 | struct inode *inode = dentry->d_inode; | |
306 | if (inode) { | |
307 | dentry->d_inode = NULL; | |
b3d9b7a3 | 308 | hlist_del_init(&dentry->d_alias); |
1da177e4 | 309 | spin_unlock(&dentry->d_lock); |
873feea0 | 310 | spin_unlock(&inode->i_lock); |
f805fbda LT |
311 | if (!inode->i_nlink) |
312 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
313 | if (dentry->d_op && dentry->d_op->d_iput) |
314 | dentry->d_op->d_iput(dentry, inode); | |
315 | else | |
316 | iput(inode); | |
317 | } else { | |
318 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
319 | } |
320 | } | |
321 | ||
31e6b01f NP |
322 | /* |
323 | * Release the dentry's inode, using the filesystem | |
324 | * d_iput() operation if defined. dentry remains in-use. | |
325 | */ | |
326 | static void dentry_unlink_inode(struct dentry * dentry) | |
327 | __releases(dentry->d_lock) | |
873feea0 | 328 | __releases(dentry->d_inode->i_lock) |
31e6b01f NP |
329 | { |
330 | struct inode *inode = dentry->d_inode; | |
331 | dentry->d_inode = NULL; | |
b3d9b7a3 | 332 | hlist_del_init(&dentry->d_alias); |
31e6b01f NP |
333 | dentry_rcuwalk_barrier(dentry); |
334 | spin_unlock(&dentry->d_lock); | |
873feea0 | 335 | spin_unlock(&inode->i_lock); |
31e6b01f NP |
336 | if (!inode->i_nlink) |
337 | fsnotify_inoderemove(inode); | |
338 | if (dentry->d_op && dentry->d_op->d_iput) | |
339 | dentry->d_op->d_iput(dentry, inode); | |
340 | else | |
341 | iput(inode); | |
342 | } | |
343 | ||
da3bbdd4 | 344 | /* |
f0023bc6 | 345 | * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held. |
da3bbdd4 KM |
346 | */ |
347 | static void dentry_lru_add(struct dentry *dentry) | |
348 | { | |
a4633357 | 349 | if (list_empty(&dentry->d_lru)) { |
23044507 | 350 | spin_lock(&dcache_lru_lock); |
a4633357 CH |
351 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
352 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 353 | dentry_stat.nr_unused++; |
23044507 | 354 | spin_unlock(&dcache_lru_lock); |
a4633357 | 355 | } |
da3bbdd4 KM |
356 | } |
357 | ||
23044507 NP |
358 | static void __dentry_lru_del(struct dentry *dentry) |
359 | { | |
360 | list_del_init(&dentry->d_lru); | |
eaf5f907 | 361 | dentry->d_flags &= ~DCACHE_SHRINK_LIST; |
23044507 NP |
362 | dentry->d_sb->s_nr_dentry_unused--; |
363 | dentry_stat.nr_unused--; | |
364 | } | |
365 | ||
f0023bc6 SW |
366 | /* |
367 | * Remove a dentry with references from the LRU. | |
368 | */ | |
da3bbdd4 KM |
369 | static void dentry_lru_del(struct dentry *dentry) |
370 | { | |
371 | if (!list_empty(&dentry->d_lru)) { | |
23044507 NP |
372 | spin_lock(&dcache_lru_lock); |
373 | __dentry_lru_del(dentry); | |
374 | spin_unlock(&dcache_lru_lock); | |
da3bbdd4 KM |
375 | } |
376 | } | |
377 | ||
b48f03b3 | 378 | static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list) |
da3bbdd4 | 379 | { |
23044507 | 380 | spin_lock(&dcache_lru_lock); |
a4633357 | 381 | if (list_empty(&dentry->d_lru)) { |
b48f03b3 | 382 | list_add_tail(&dentry->d_lru, list); |
a4633357 | 383 | dentry->d_sb->s_nr_dentry_unused++; |
86c8749e | 384 | dentry_stat.nr_unused++; |
a4633357 | 385 | } else { |
b48f03b3 | 386 | list_move_tail(&dentry->d_lru, list); |
da3bbdd4 | 387 | } |
23044507 | 388 | spin_unlock(&dcache_lru_lock); |
da3bbdd4 KM |
389 | } |
390 | ||
d52b9086 MS |
391 | /** |
392 | * d_kill - kill dentry and return parent | |
393 | * @dentry: dentry to kill | |
ff5fdb61 | 394 | * @parent: parent dentry |
d52b9086 | 395 | * |
31f3e0b3 | 396 | * The dentry must already be unhashed and removed from the LRU. |
d52b9086 MS |
397 | * |
398 | * If this is the root of the dentry tree, return NULL. | |
23044507 | 399 | * |
b5c84bf6 NP |
400 | * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by |
401 | * d_kill. | |
d52b9086 | 402 | */ |
2fd6b7f5 | 403 | static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
31f3e0b3 | 404 | __releases(dentry->d_lock) |
2fd6b7f5 | 405 | __releases(parent->d_lock) |
873feea0 | 406 | __releases(dentry->d_inode->i_lock) |
d52b9086 | 407 | { |
d52b9086 | 408 | list_del(&dentry->d_u.d_child); |
c83ce989 TM |
409 | /* |
410 | * Inform try_to_ascend() that we are no longer attached to the | |
411 | * dentry tree | |
412 | */ | |
b161dfa6 | 413 | dentry->d_flags |= DCACHE_DENTRY_KILLED; |
2fd6b7f5 NP |
414 | if (parent) |
415 | spin_unlock(&parent->d_lock); | |
d52b9086 | 416 | dentry_iput(dentry); |
b7ab39f6 NP |
417 | /* |
418 | * dentry_iput drops the locks, at which point nobody (except | |
419 | * transient RCU lookups) can reach this dentry. | |
420 | */ | |
d52b9086 | 421 | d_free(dentry); |
871c0067 | 422 | return parent; |
d52b9086 MS |
423 | } |
424 | ||
c6627c60 DH |
425 | /* |
426 | * Unhash a dentry without inserting an RCU walk barrier or checking that | |
427 | * dentry->d_lock is locked. The caller must take care of that, if | |
428 | * appropriate. | |
429 | */ | |
430 | static void __d_shrink(struct dentry *dentry) | |
431 | { | |
432 | if (!d_unhashed(dentry)) { | |
433 | struct hlist_bl_head *b; | |
434 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) | |
435 | b = &dentry->d_sb->s_anon; | |
436 | else | |
437 | b = d_hash(dentry->d_parent, dentry->d_name.hash); | |
438 | ||
439 | hlist_bl_lock(b); | |
440 | __hlist_bl_del(&dentry->d_hash); | |
441 | dentry->d_hash.pprev = NULL; | |
442 | hlist_bl_unlock(b); | |
443 | } | |
444 | } | |
445 | ||
789680d1 NP |
446 | /** |
447 | * d_drop - drop a dentry | |
448 | * @dentry: dentry to drop | |
449 | * | |
450 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
451 | * be found through a VFS lookup any more. Note that this is different from | |
452 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
453 | * possible, giving a successful _negative_ lookup, while d_drop will | |
454 | * just make the cache lookup fail. | |
455 | * | |
456 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
457 | * reason (NFS timeouts or autofs deletes). | |
458 | * | |
459 | * __d_drop requires dentry->d_lock. | |
460 | */ | |
461 | void __d_drop(struct dentry *dentry) | |
462 | { | |
dea3667b | 463 | if (!d_unhashed(dentry)) { |
c6627c60 | 464 | __d_shrink(dentry); |
dea3667b | 465 | dentry_rcuwalk_barrier(dentry); |
789680d1 NP |
466 | } |
467 | } | |
468 | EXPORT_SYMBOL(__d_drop); | |
469 | ||
470 | void d_drop(struct dentry *dentry) | |
471 | { | |
789680d1 NP |
472 | spin_lock(&dentry->d_lock); |
473 | __d_drop(dentry); | |
474 | spin_unlock(&dentry->d_lock); | |
789680d1 NP |
475 | } |
476 | EXPORT_SYMBOL(d_drop); | |
477 | ||
77812a1e NP |
478 | /* |
479 | * Finish off a dentry we've decided to kill. | |
480 | * dentry->d_lock must be held, returns with it unlocked. | |
481 | * If ref is non-zero, then decrement the refcount too. | |
482 | * Returns dentry requiring refcount drop, or NULL if we're done. | |
483 | */ | |
484 | static inline struct dentry *dentry_kill(struct dentry *dentry, int ref) | |
485 | __releases(dentry->d_lock) | |
486 | { | |
873feea0 | 487 | struct inode *inode; |
77812a1e NP |
488 | struct dentry *parent; |
489 | ||
873feea0 NP |
490 | inode = dentry->d_inode; |
491 | if (inode && !spin_trylock(&inode->i_lock)) { | |
77812a1e NP |
492 | relock: |
493 | spin_unlock(&dentry->d_lock); | |
494 | cpu_relax(); | |
495 | return dentry; /* try again with same dentry */ | |
496 | } | |
497 | if (IS_ROOT(dentry)) | |
498 | parent = NULL; | |
499 | else | |
500 | parent = dentry->d_parent; | |
501 | if (parent && !spin_trylock(&parent->d_lock)) { | |
873feea0 NP |
502 | if (inode) |
503 | spin_unlock(&inode->i_lock); | |
77812a1e NP |
504 | goto relock; |
505 | } | |
31e6b01f | 506 | |
77812a1e | 507 | if (ref) |
98474236 | 508 | dentry->d_lockref.count--; |
f0023bc6 | 509 | /* |
f0023bc6 SW |
510 | * inform the fs via d_prune that this dentry is about to be |
511 | * unhashed and destroyed. | |
512 | */ | |
590fb51f | 513 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry)) |
61572bb1 YZ |
514 | dentry->d_op->d_prune(dentry); |
515 | ||
516 | dentry_lru_del(dentry); | |
77812a1e NP |
517 | /* if it was on the hash then remove it */ |
518 | __d_drop(dentry); | |
519 | return d_kill(dentry, parent); | |
520 | } | |
521 | ||
1da177e4 LT |
522 | /* |
523 | * This is dput | |
524 | * | |
525 | * This is complicated by the fact that we do not want to put | |
526 | * dentries that are no longer on any hash chain on the unused | |
527 | * list: we'd much rather just get rid of them immediately. | |
528 | * | |
529 | * However, that implies that we have to traverse the dentry | |
530 | * tree upwards to the parents which might _also_ now be | |
531 | * scheduled for deletion (it may have been only waiting for | |
532 | * its last child to go away). | |
533 | * | |
534 | * This tail recursion is done by hand as we don't want to depend | |
535 | * on the compiler to always get this right (gcc generally doesn't). | |
536 | * Real recursion would eat up our stack space. | |
537 | */ | |
538 | ||
539 | /* | |
540 | * dput - release a dentry | |
541 | * @dentry: dentry to release | |
542 | * | |
543 | * Release a dentry. This will drop the usage count and if appropriate | |
544 | * call the dentry unlink method as well as removing it from the queues and | |
545 | * releasing its resources. If the parent dentries were scheduled for release | |
546 | * they too may now get deleted. | |
1da177e4 | 547 | */ |
1da177e4 LT |
548 | void dput(struct dentry *dentry) |
549 | { | |
550 | if (!dentry) | |
551 | return; | |
552 | ||
553 | repeat: | |
98474236 | 554 | if (dentry->d_lockref.count == 1) |
1da177e4 | 555 | might_sleep(); |
98474236 | 556 | if (lockref_put_or_lock(&dentry->d_lockref)) |
1da177e4 | 557 | return; |
1da177e4 | 558 | |
fb045adb | 559 | if (dentry->d_flags & DCACHE_OP_DELETE) { |
1da177e4 | 560 | if (dentry->d_op->d_delete(dentry)) |
61f3dee4 | 561 | goto kill_it; |
1da177e4 | 562 | } |
265ac902 | 563 | |
1da177e4 LT |
564 | /* Unreachable? Get rid of it */ |
565 | if (d_unhashed(dentry)) | |
566 | goto kill_it; | |
265ac902 | 567 | |
39e3c955 | 568 | dentry->d_flags |= DCACHE_REFERENCED; |
a4633357 | 569 | dentry_lru_add(dentry); |
265ac902 | 570 | |
98474236 | 571 | dentry->d_lockref.count--; |
61f3dee4 | 572 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
573 | return; |
574 | ||
d52b9086 | 575 | kill_it: |
77812a1e | 576 | dentry = dentry_kill(dentry, 1); |
d52b9086 MS |
577 | if (dentry) |
578 | goto repeat; | |
1da177e4 | 579 | } |
ec4f8605 | 580 | EXPORT_SYMBOL(dput); |
1da177e4 LT |
581 | |
582 | /** | |
583 | * d_invalidate - invalidate a dentry | |
584 | * @dentry: dentry to invalidate | |
585 | * | |
586 | * Try to invalidate the dentry if it turns out to be | |
587 | * possible. If there are other dentries that can be | |
588 | * reached through this one we can't delete it and we | |
589 | * return -EBUSY. On success we return 0. | |
590 | * | |
591 | * no dcache lock. | |
592 | */ | |
593 | ||
594 | int d_invalidate(struct dentry * dentry) | |
595 | { | |
596 | /* | |
597 | * If it's already been dropped, return OK. | |
598 | */ | |
da502956 | 599 | spin_lock(&dentry->d_lock); |
1da177e4 | 600 | if (d_unhashed(dentry)) { |
da502956 | 601 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
602 | return 0; |
603 | } | |
604 | /* | |
605 | * Check whether to do a partial shrink_dcache | |
606 | * to get rid of unused child entries. | |
607 | */ | |
608 | if (!list_empty(&dentry->d_subdirs)) { | |
da502956 | 609 | spin_unlock(&dentry->d_lock); |
1da177e4 | 610 | shrink_dcache_parent(dentry); |
da502956 | 611 | spin_lock(&dentry->d_lock); |
1da177e4 LT |
612 | } |
613 | ||
614 | /* | |
615 | * Somebody else still using it? | |
616 | * | |
617 | * If it's a directory, we can't drop it | |
618 | * for fear of somebody re-populating it | |
619 | * with children (even though dropping it | |
620 | * would make it unreachable from the root, | |
621 | * we might still populate it if it was a | |
622 | * working directory or similar). | |
50e69630 AV |
623 | * We also need to leave mountpoints alone, |
624 | * directory or not. | |
1da177e4 | 625 | */ |
98474236 | 626 | if (dentry->d_lockref.count > 1 && dentry->d_inode) { |
50e69630 | 627 | if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) { |
1da177e4 | 628 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
629 | return -EBUSY; |
630 | } | |
631 | } | |
632 | ||
633 | __d_drop(dentry); | |
634 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
635 | return 0; |
636 | } | |
ec4f8605 | 637 | EXPORT_SYMBOL(d_invalidate); |
1da177e4 | 638 | |
b5c84bf6 | 639 | /* This must be called with d_lock held */ |
dc0474be | 640 | static inline void __dget_dlock(struct dentry *dentry) |
23044507 | 641 | { |
98474236 | 642 | dentry->d_lockref.count++; |
23044507 NP |
643 | } |
644 | ||
dc0474be | 645 | static inline void __dget(struct dentry *dentry) |
1da177e4 | 646 | { |
98474236 | 647 | lockref_get(&dentry->d_lockref); |
1da177e4 LT |
648 | } |
649 | ||
b7ab39f6 NP |
650 | struct dentry *dget_parent(struct dentry *dentry) |
651 | { | |
df3d0bbc | 652 | int gotref; |
b7ab39f6 NP |
653 | struct dentry *ret; |
654 | ||
df3d0bbc WL |
655 | /* |
656 | * Do optimistic parent lookup without any | |
657 | * locking. | |
658 | */ | |
659 | rcu_read_lock(); | |
660 | ret = ACCESS_ONCE(dentry->d_parent); | |
661 | gotref = lockref_get_not_zero(&ret->d_lockref); | |
662 | rcu_read_unlock(); | |
663 | if (likely(gotref)) { | |
664 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) | |
665 | return ret; | |
666 | dput(ret); | |
667 | } | |
668 | ||
b7ab39f6 | 669 | repeat: |
a734eb45 NP |
670 | /* |
671 | * Don't need rcu_dereference because we re-check it was correct under | |
672 | * the lock. | |
673 | */ | |
674 | rcu_read_lock(); | |
b7ab39f6 | 675 | ret = dentry->d_parent; |
a734eb45 NP |
676 | spin_lock(&ret->d_lock); |
677 | if (unlikely(ret != dentry->d_parent)) { | |
678 | spin_unlock(&ret->d_lock); | |
679 | rcu_read_unlock(); | |
b7ab39f6 NP |
680 | goto repeat; |
681 | } | |
a734eb45 | 682 | rcu_read_unlock(); |
98474236 WL |
683 | BUG_ON(!ret->d_lockref.count); |
684 | ret->d_lockref.count++; | |
b7ab39f6 | 685 | spin_unlock(&ret->d_lock); |
b7ab39f6 NP |
686 | return ret; |
687 | } | |
688 | EXPORT_SYMBOL(dget_parent); | |
689 | ||
1da177e4 LT |
690 | /** |
691 | * d_find_alias - grab a hashed alias of inode | |
692 | * @inode: inode in question | |
32ba9c3f LT |
693 | * @want_discon: flag, used by d_splice_alias, to request |
694 | * that only a DISCONNECTED alias be returned. | |
1da177e4 LT |
695 | * |
696 | * If inode has a hashed alias, or is a directory and has any alias, | |
697 | * acquire the reference to alias and return it. Otherwise return NULL. | |
698 | * Notice that if inode is a directory there can be only one alias and | |
699 | * it can be unhashed only if it has no children, or if it is the root | |
700 | * of a filesystem. | |
701 | * | |
21c0d8fd | 702 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
32ba9c3f LT |
703 | * any other hashed alias over that one unless @want_discon is set, |
704 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. | |
1da177e4 | 705 | */ |
32ba9c3f | 706 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
1da177e4 | 707 | { |
da502956 | 708 | struct dentry *alias, *discon_alias; |
1da177e4 | 709 | |
da502956 NP |
710 | again: |
711 | discon_alias = NULL; | |
b67bfe0d | 712 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
da502956 | 713 | spin_lock(&alias->d_lock); |
1da177e4 | 714 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
21c0d8fd | 715 | if (IS_ROOT(alias) && |
da502956 | 716 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
1da177e4 | 717 | discon_alias = alias; |
32ba9c3f | 718 | } else if (!want_discon) { |
dc0474be | 719 | __dget_dlock(alias); |
da502956 NP |
720 | spin_unlock(&alias->d_lock); |
721 | return alias; | |
722 | } | |
723 | } | |
724 | spin_unlock(&alias->d_lock); | |
725 | } | |
726 | if (discon_alias) { | |
727 | alias = discon_alias; | |
728 | spin_lock(&alias->d_lock); | |
729 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
730 | if (IS_ROOT(alias) && | |
731 | (alias->d_flags & DCACHE_DISCONNECTED)) { | |
dc0474be | 732 | __dget_dlock(alias); |
da502956 | 733 | spin_unlock(&alias->d_lock); |
1da177e4 LT |
734 | return alias; |
735 | } | |
736 | } | |
da502956 NP |
737 | spin_unlock(&alias->d_lock); |
738 | goto again; | |
1da177e4 | 739 | } |
da502956 | 740 | return NULL; |
1da177e4 LT |
741 | } |
742 | ||
da502956 | 743 | struct dentry *d_find_alias(struct inode *inode) |
1da177e4 | 744 | { |
214fda1f DH |
745 | struct dentry *de = NULL; |
746 | ||
b3d9b7a3 | 747 | if (!hlist_empty(&inode->i_dentry)) { |
873feea0 | 748 | spin_lock(&inode->i_lock); |
32ba9c3f | 749 | de = __d_find_alias(inode, 0); |
873feea0 | 750 | spin_unlock(&inode->i_lock); |
214fda1f | 751 | } |
1da177e4 LT |
752 | return de; |
753 | } | |
ec4f8605 | 754 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
755 | |
756 | /* | |
757 | * Try to kill dentries associated with this inode. | |
758 | * WARNING: you must own a reference to inode. | |
759 | */ | |
760 | void d_prune_aliases(struct inode *inode) | |
761 | { | |
0cdca3f9 | 762 | struct dentry *dentry; |
1da177e4 | 763 | restart: |
873feea0 | 764 | spin_lock(&inode->i_lock); |
b67bfe0d | 765 | hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 | 766 | spin_lock(&dentry->d_lock); |
98474236 | 767 | if (!dentry->d_lockref.count) { |
590fb51f YZ |
768 | /* |
769 | * inform the fs via d_prune that this dentry | |
770 | * is about to be unhashed and destroyed. | |
771 | */ | |
772 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && | |
773 | !d_unhashed(dentry)) | |
774 | dentry->d_op->d_prune(dentry); | |
775 | ||
dc0474be | 776 | __dget_dlock(dentry); |
1da177e4 LT |
777 | __d_drop(dentry); |
778 | spin_unlock(&dentry->d_lock); | |
873feea0 | 779 | spin_unlock(&inode->i_lock); |
1da177e4 LT |
780 | dput(dentry); |
781 | goto restart; | |
782 | } | |
783 | spin_unlock(&dentry->d_lock); | |
784 | } | |
873feea0 | 785 | spin_unlock(&inode->i_lock); |
1da177e4 | 786 | } |
ec4f8605 | 787 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 LT |
788 | |
789 | /* | |
77812a1e NP |
790 | * Try to throw away a dentry - free the inode, dput the parent. |
791 | * Requires dentry->d_lock is held, and dentry->d_count == 0. | |
792 | * Releases dentry->d_lock. | |
d702ccb3 | 793 | * |
77812a1e | 794 | * This may fail if locks cannot be acquired no problem, just try again. |
1da177e4 | 795 | */ |
77812a1e | 796 | static void try_prune_one_dentry(struct dentry *dentry) |
31f3e0b3 | 797 | __releases(dentry->d_lock) |
1da177e4 | 798 | { |
77812a1e | 799 | struct dentry *parent; |
d52b9086 | 800 | |
77812a1e | 801 | parent = dentry_kill(dentry, 0); |
d52b9086 | 802 | /* |
77812a1e NP |
803 | * If dentry_kill returns NULL, we have nothing more to do. |
804 | * if it returns the same dentry, trylocks failed. In either | |
805 | * case, just loop again. | |
806 | * | |
807 | * Otherwise, we need to prune ancestors too. This is necessary | |
808 | * to prevent quadratic behavior of shrink_dcache_parent(), but | |
809 | * is also expected to be beneficial in reducing dentry cache | |
810 | * fragmentation. | |
d52b9086 | 811 | */ |
77812a1e NP |
812 | if (!parent) |
813 | return; | |
814 | if (parent == dentry) | |
815 | return; | |
816 | ||
817 | /* Prune ancestors. */ | |
818 | dentry = parent; | |
d52b9086 | 819 | while (dentry) { |
98474236 | 820 | if (lockref_put_or_lock(&dentry->d_lockref)) |
89e60548 | 821 | return; |
77812a1e | 822 | dentry = dentry_kill(dentry, 1); |
d52b9086 | 823 | } |
1da177e4 LT |
824 | } |
825 | ||
3049cfe2 | 826 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 827 | { |
da3bbdd4 | 828 | struct dentry *dentry; |
da3bbdd4 | 829 | |
ec33679d NP |
830 | rcu_read_lock(); |
831 | for (;;) { | |
ec33679d NP |
832 | dentry = list_entry_rcu(list->prev, struct dentry, d_lru); |
833 | if (&dentry->d_lru == list) | |
834 | break; /* empty */ | |
835 | spin_lock(&dentry->d_lock); | |
836 | if (dentry != list_entry(list->prev, struct dentry, d_lru)) { | |
837 | spin_unlock(&dentry->d_lock); | |
23044507 NP |
838 | continue; |
839 | } | |
840 | ||
1da177e4 LT |
841 | /* |
842 | * We found an inuse dentry which was not removed from | |
da3bbdd4 KM |
843 | * the LRU because of laziness during lookup. Do not free |
844 | * it - just keep it off the LRU list. | |
1da177e4 | 845 | */ |
98474236 | 846 | if (dentry->d_lockref.count) { |
ec33679d | 847 | dentry_lru_del(dentry); |
da3bbdd4 | 848 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
849 | continue; |
850 | } | |
ec33679d | 851 | |
ec33679d | 852 | rcu_read_unlock(); |
77812a1e NP |
853 | |
854 | try_prune_one_dentry(dentry); | |
855 | ||
ec33679d | 856 | rcu_read_lock(); |
da3bbdd4 | 857 | } |
ec33679d | 858 | rcu_read_unlock(); |
3049cfe2 CH |
859 | } |
860 | ||
861 | /** | |
b48f03b3 DC |
862 | * prune_dcache_sb - shrink the dcache |
863 | * @sb: superblock | |
864 | * @count: number of entries to try to free | |
865 | * | |
866 | * Attempt to shrink the superblock dcache LRU by @count entries. This is | |
867 | * done when we need more memory an called from the superblock shrinker | |
868 | * function. | |
3049cfe2 | 869 | * |
b48f03b3 DC |
870 | * This function may fail to free any resources if all the dentries are in |
871 | * use. | |
3049cfe2 | 872 | */ |
b48f03b3 | 873 | void prune_dcache_sb(struct super_block *sb, int count) |
3049cfe2 | 874 | { |
3049cfe2 CH |
875 | struct dentry *dentry; |
876 | LIST_HEAD(referenced); | |
877 | LIST_HEAD(tmp); | |
3049cfe2 | 878 | |
23044507 NP |
879 | relock: |
880 | spin_lock(&dcache_lru_lock); | |
3049cfe2 CH |
881 | while (!list_empty(&sb->s_dentry_lru)) { |
882 | dentry = list_entry(sb->s_dentry_lru.prev, | |
883 | struct dentry, d_lru); | |
884 | BUG_ON(dentry->d_sb != sb); | |
885 | ||
23044507 NP |
886 | if (!spin_trylock(&dentry->d_lock)) { |
887 | spin_unlock(&dcache_lru_lock); | |
888 | cpu_relax(); | |
889 | goto relock; | |
890 | } | |
891 | ||
b48f03b3 | 892 | if (dentry->d_flags & DCACHE_REFERENCED) { |
23044507 NP |
893 | dentry->d_flags &= ~DCACHE_REFERENCED; |
894 | list_move(&dentry->d_lru, &referenced); | |
3049cfe2 | 895 | spin_unlock(&dentry->d_lock); |
23044507 NP |
896 | } else { |
897 | list_move_tail(&dentry->d_lru, &tmp); | |
eaf5f907 | 898 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
23044507 | 899 | spin_unlock(&dentry->d_lock); |
b0d40c92 | 900 | if (!--count) |
23044507 | 901 | break; |
3049cfe2 | 902 | } |
ec33679d | 903 | cond_resched_lock(&dcache_lru_lock); |
3049cfe2 | 904 | } |
da3bbdd4 KM |
905 | if (!list_empty(&referenced)) |
906 | list_splice(&referenced, &sb->s_dentry_lru); | |
23044507 | 907 | spin_unlock(&dcache_lru_lock); |
ec33679d NP |
908 | |
909 | shrink_dentry_list(&tmp); | |
da3bbdd4 KM |
910 | } |
911 | ||
1da177e4 LT |
912 | /** |
913 | * shrink_dcache_sb - shrink dcache for a superblock | |
914 | * @sb: superblock | |
915 | * | |
3049cfe2 CH |
916 | * Shrink the dcache for the specified super block. This is used to free |
917 | * the dcache before unmounting a file system. | |
1da177e4 | 918 | */ |
3049cfe2 | 919 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 920 | { |
3049cfe2 CH |
921 | LIST_HEAD(tmp); |
922 | ||
23044507 | 923 | spin_lock(&dcache_lru_lock); |
3049cfe2 CH |
924 | while (!list_empty(&sb->s_dentry_lru)) { |
925 | list_splice_init(&sb->s_dentry_lru, &tmp); | |
ec33679d | 926 | spin_unlock(&dcache_lru_lock); |
3049cfe2 | 927 | shrink_dentry_list(&tmp); |
ec33679d | 928 | spin_lock(&dcache_lru_lock); |
3049cfe2 | 929 | } |
23044507 | 930 | spin_unlock(&dcache_lru_lock); |
1da177e4 | 931 | } |
ec4f8605 | 932 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 933 | |
c636ebdb DH |
934 | /* |
935 | * destroy a single subtree of dentries for unmount | |
936 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
937 | * locking | |
938 | */ | |
939 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
940 | { | |
941 | struct dentry *parent; | |
942 | ||
943 | BUG_ON(!IS_ROOT(dentry)); | |
944 | ||
c636ebdb DH |
945 | for (;;) { |
946 | /* descend to the first leaf in the current subtree */ | |
43c1c9cd | 947 | while (!list_empty(&dentry->d_subdirs)) |
c636ebdb DH |
948 | dentry = list_entry(dentry->d_subdirs.next, |
949 | struct dentry, d_u.d_child); | |
c636ebdb DH |
950 | |
951 | /* consume the dentries from this leaf up through its parents | |
952 | * until we find one with children or run out altogether */ | |
953 | do { | |
954 | struct inode *inode; | |
955 | ||
f0023bc6 | 956 | /* |
61572bb1 | 957 | * inform the fs that this dentry is about to be |
f0023bc6 SW |
958 | * unhashed and destroyed. |
959 | */ | |
590fb51f YZ |
960 | if ((dentry->d_flags & DCACHE_OP_PRUNE) && |
961 | !d_unhashed(dentry)) | |
61572bb1 YZ |
962 | dentry->d_op->d_prune(dentry); |
963 | ||
964 | dentry_lru_del(dentry); | |
43c1c9cd DH |
965 | __d_shrink(dentry); |
966 | ||
98474236 | 967 | if (dentry->d_lockref.count != 0) { |
c636ebdb DH |
968 | printk(KERN_ERR |
969 | "BUG: Dentry %p{i=%lx,n=%s}" | |
970 | " still in use (%d)" | |
971 | " [unmount of %s %s]\n", | |
972 | dentry, | |
973 | dentry->d_inode ? | |
974 | dentry->d_inode->i_ino : 0UL, | |
975 | dentry->d_name.name, | |
98474236 | 976 | dentry->d_lockref.count, |
c636ebdb DH |
977 | dentry->d_sb->s_type->name, |
978 | dentry->d_sb->s_id); | |
979 | BUG(); | |
980 | } | |
981 | ||
2fd6b7f5 | 982 | if (IS_ROOT(dentry)) { |
c636ebdb | 983 | parent = NULL; |
2fd6b7f5 NP |
984 | list_del(&dentry->d_u.d_child); |
985 | } else { | |
871c0067 | 986 | parent = dentry->d_parent; |
98474236 | 987 | parent->d_lockref.count--; |
2fd6b7f5 | 988 | list_del(&dentry->d_u.d_child); |
871c0067 | 989 | } |
c636ebdb | 990 | |
c636ebdb DH |
991 | inode = dentry->d_inode; |
992 | if (inode) { | |
993 | dentry->d_inode = NULL; | |
b3d9b7a3 | 994 | hlist_del_init(&dentry->d_alias); |
c636ebdb DH |
995 | if (dentry->d_op && dentry->d_op->d_iput) |
996 | dentry->d_op->d_iput(dentry, inode); | |
997 | else | |
998 | iput(inode); | |
999 | } | |
1000 | ||
1001 | d_free(dentry); | |
1002 | ||
1003 | /* finished when we fall off the top of the tree, | |
1004 | * otherwise we ascend to the parent and move to the | |
1005 | * next sibling if there is one */ | |
1006 | if (!parent) | |
312d3ca8 | 1007 | return; |
c636ebdb | 1008 | dentry = parent; |
c636ebdb DH |
1009 | } while (list_empty(&dentry->d_subdirs)); |
1010 | ||
1011 | dentry = list_entry(dentry->d_subdirs.next, | |
1012 | struct dentry, d_u.d_child); | |
1013 | } | |
1014 | } | |
1015 | ||
1016 | /* | |
1017 | * destroy the dentries attached to a superblock on unmounting | |
b5c84bf6 | 1018 | * - we don't need to use dentry->d_lock because: |
c636ebdb DH |
1019 | * - the superblock is detached from all mountings and open files, so the |
1020 | * dentry trees will not be rearranged by the VFS | |
1021 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
1022 | * any dentries belonging to this superblock that it comes across | |
1023 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
1024 | * in this superblock | |
1025 | */ | |
1026 | void shrink_dcache_for_umount(struct super_block *sb) | |
1027 | { | |
1028 | struct dentry *dentry; | |
1029 | ||
1030 | if (down_read_trylock(&sb->s_umount)) | |
1031 | BUG(); | |
1032 | ||
1033 | dentry = sb->s_root; | |
1034 | sb->s_root = NULL; | |
98474236 | 1035 | dentry->d_lockref.count--; |
c636ebdb DH |
1036 | shrink_dcache_for_umount_subtree(dentry); |
1037 | ||
ceb5bdc2 NP |
1038 | while (!hlist_bl_empty(&sb->s_anon)) { |
1039 | dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); | |
c636ebdb DH |
1040 | shrink_dcache_for_umount_subtree(dentry); |
1041 | } | |
1042 | } | |
1043 | ||
c826cb7d LT |
1044 | /* |
1045 | * This tries to ascend one level of parenthood, but | |
1046 | * we can race with renaming, so we need to re-check | |
1047 | * the parenthood after dropping the lock and check | |
1048 | * that the sequence number still matches. | |
1049 | */ | |
1050 | static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq) | |
1051 | { | |
1052 | struct dentry *new = old->d_parent; | |
1053 | ||
1054 | rcu_read_lock(); | |
1055 | spin_unlock(&old->d_lock); | |
1056 | spin_lock(&new->d_lock); | |
1057 | ||
1058 | /* | |
1059 | * might go back up the wrong parent if we have had a rename | |
1060 | * or deletion | |
1061 | */ | |
1062 | if (new != old->d_parent || | |
b161dfa6 | 1063 | (old->d_flags & DCACHE_DENTRY_KILLED) || |
c826cb7d LT |
1064 | (!locked && read_seqretry(&rename_lock, seq))) { |
1065 | spin_unlock(&new->d_lock); | |
1066 | new = NULL; | |
1067 | } | |
1068 | rcu_read_unlock(); | |
1069 | return new; | |
1070 | } | |
1071 | ||
db14fc3a MS |
1072 | /** |
1073 | * enum d_walk_ret - action to talke during tree walk | |
1074 | * @D_WALK_CONTINUE: contrinue walk | |
1075 | * @D_WALK_QUIT: quit walk | |
1076 | * @D_WALK_NORETRY: quit when retry is needed | |
1077 | * @D_WALK_SKIP: skip this dentry and its children | |
1078 | */ | |
1079 | enum d_walk_ret { | |
1080 | D_WALK_CONTINUE, | |
1081 | D_WALK_QUIT, | |
1082 | D_WALK_NORETRY, | |
1083 | D_WALK_SKIP, | |
1084 | }; | |
c826cb7d | 1085 | |
1da177e4 | 1086 | /** |
db14fc3a MS |
1087 | * d_walk - walk the dentry tree |
1088 | * @parent: start of walk | |
1089 | * @data: data passed to @enter() and @finish() | |
1090 | * @enter: callback when first entering the dentry | |
1091 | * @finish: callback when successfully finished the walk | |
1da177e4 | 1092 | * |
db14fc3a | 1093 | * The @enter() and @finish() callbacks are called with d_lock held. |
1da177e4 | 1094 | */ |
db14fc3a MS |
1095 | static void d_walk(struct dentry *parent, void *data, |
1096 | enum d_walk_ret (*enter)(void *, struct dentry *), | |
1097 | void (*finish)(void *)) | |
1da177e4 | 1098 | { |
949854d0 | 1099 | struct dentry *this_parent; |
1da177e4 | 1100 | struct list_head *next; |
949854d0 | 1101 | unsigned seq; |
58db63d0 | 1102 | int locked = 0; |
db14fc3a MS |
1103 | enum d_walk_ret ret; |
1104 | bool retry = true; | |
949854d0 | 1105 | |
949854d0 | 1106 | seq = read_seqbegin(&rename_lock); |
58db63d0 NP |
1107 | again: |
1108 | this_parent = parent; | |
2fd6b7f5 | 1109 | spin_lock(&this_parent->d_lock); |
db14fc3a MS |
1110 | |
1111 | ret = enter(data, this_parent); | |
1112 | switch (ret) { | |
1113 | case D_WALK_CONTINUE: | |
1114 | break; | |
1115 | case D_WALK_QUIT: | |
1116 | case D_WALK_SKIP: | |
1117 | goto out_unlock; | |
1118 | case D_WALK_NORETRY: | |
1119 | retry = false; | |
1120 | break; | |
1121 | } | |
1da177e4 LT |
1122 | repeat: |
1123 | next = this_parent->d_subdirs.next; | |
1124 | resume: | |
1125 | while (next != &this_parent->d_subdirs) { | |
1126 | struct list_head *tmp = next; | |
5160ee6f | 1127 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 | 1128 | next = tmp->next; |
2fd6b7f5 NP |
1129 | |
1130 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
db14fc3a MS |
1131 | |
1132 | ret = enter(data, dentry); | |
1133 | switch (ret) { | |
1134 | case D_WALK_CONTINUE: | |
1135 | break; | |
1136 | case D_WALK_QUIT: | |
2fd6b7f5 | 1137 | spin_unlock(&dentry->d_lock); |
db14fc3a MS |
1138 | goto out_unlock; |
1139 | case D_WALK_NORETRY: | |
1140 | retry = false; | |
1141 | break; | |
1142 | case D_WALK_SKIP: | |
1143 | spin_unlock(&dentry->d_lock); | |
1144 | continue; | |
2fd6b7f5 | 1145 | } |
db14fc3a | 1146 | |
1da177e4 | 1147 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
1148 | spin_unlock(&this_parent->d_lock); |
1149 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1150 | this_parent = dentry; |
2fd6b7f5 | 1151 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1152 | goto repeat; |
1153 | } | |
2fd6b7f5 | 1154 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
1155 | } |
1156 | /* | |
1157 | * All done at this level ... ascend and resume the search. | |
1158 | */ | |
1159 | if (this_parent != parent) { | |
c826cb7d LT |
1160 | struct dentry *child = this_parent; |
1161 | this_parent = try_to_ascend(this_parent, locked, seq); | |
1162 | if (!this_parent) | |
949854d0 | 1163 | goto rename_retry; |
949854d0 | 1164 | next = child->d_u.d_child.next; |
1da177e4 LT |
1165 | goto resume; |
1166 | } | |
db14fc3a MS |
1167 | if (!locked && read_seqretry(&rename_lock, seq)) { |
1168 | spin_unlock(&this_parent->d_lock); | |
949854d0 | 1169 | goto rename_retry; |
db14fc3a MS |
1170 | } |
1171 | if (finish) | |
1172 | finish(data); | |
1173 | ||
1174 | out_unlock: | |
1175 | spin_unlock(&this_parent->d_lock); | |
58db63d0 NP |
1176 | if (locked) |
1177 | write_sequnlock(&rename_lock); | |
db14fc3a | 1178 | return; |
58db63d0 NP |
1179 | |
1180 | rename_retry: | |
db14fc3a MS |
1181 | if (!retry) |
1182 | return; | |
8110e16d MS |
1183 | if (locked) |
1184 | goto again; | |
58db63d0 NP |
1185 | locked = 1; |
1186 | write_seqlock(&rename_lock); | |
1187 | goto again; | |
1da177e4 | 1188 | } |
db14fc3a MS |
1189 | |
1190 | /* | |
1191 | * Search for at least 1 mount point in the dentry's subdirs. | |
1192 | * We descend to the next level whenever the d_subdirs | |
1193 | * list is non-empty and continue searching. | |
1194 | */ | |
1195 | ||
1196 | /** | |
1197 | * have_submounts - check for mounts over a dentry | |
1198 | * @parent: dentry to check. | |
1199 | * | |
1200 | * Return true if the parent or its subdirectories contain | |
1201 | * a mount point | |
1202 | */ | |
1203 | ||
1204 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) | |
1205 | { | |
1206 | int *ret = data; | |
1207 | if (d_mountpoint(dentry)) { | |
1208 | *ret = 1; | |
1209 | return D_WALK_QUIT; | |
1210 | } | |
1211 | return D_WALK_CONTINUE; | |
1212 | } | |
1213 | ||
1214 | int have_submounts(struct dentry *parent) | |
1215 | { | |
1216 | int ret = 0; | |
1217 | ||
1218 | d_walk(parent, &ret, check_mount, NULL); | |
1219 | ||
1220 | return ret; | |
1221 | } | |
ec4f8605 | 1222 | EXPORT_SYMBOL(have_submounts); |
1da177e4 | 1223 | |
eed81007 MS |
1224 | /* |
1225 | * Called by mount code to set a mountpoint and check if the mountpoint is | |
1226 | * reachable (e.g. NFS can unhash a directory dentry and then the complete | |
1227 | * subtree can become unreachable). | |
1228 | * | |
1229 | * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For | |
1230 | * this reason take rename_lock and d_lock on dentry and ancestors. | |
1231 | */ | |
1232 | int d_set_mounted(struct dentry *dentry) | |
1233 | { | |
1234 | struct dentry *p; | |
1235 | int ret = -ENOENT; | |
1236 | write_seqlock(&rename_lock); | |
1237 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { | |
1238 | /* Need exclusion wrt. check_submounts_and_drop() */ | |
1239 | spin_lock(&p->d_lock); | |
1240 | if (unlikely(d_unhashed(p))) { | |
1241 | spin_unlock(&p->d_lock); | |
1242 | goto out; | |
1243 | } | |
1244 | spin_unlock(&p->d_lock); | |
1245 | } | |
1246 | spin_lock(&dentry->d_lock); | |
1247 | if (!d_unlinked(dentry)) { | |
1248 | dentry->d_flags |= DCACHE_MOUNTED; | |
1249 | ret = 0; | |
1250 | } | |
1251 | spin_unlock(&dentry->d_lock); | |
1252 | out: | |
1253 | write_sequnlock(&rename_lock); | |
1254 | return ret; | |
1255 | } | |
1256 | ||
1da177e4 | 1257 | /* |
fd517909 | 1258 | * Search the dentry child list of the specified parent, |
1da177e4 LT |
1259 | * and move any unused dentries to the end of the unused |
1260 | * list for prune_dcache(). We descend to the next level | |
1261 | * whenever the d_subdirs list is non-empty and continue | |
1262 | * searching. | |
1263 | * | |
1264 | * It returns zero iff there are no unused children, | |
1265 | * otherwise it returns the number of children moved to | |
1266 | * the end of the unused list. This may not be the total | |
1267 | * number of unused children, because select_parent can | |
1268 | * drop the lock and return early due to latency | |
1269 | * constraints. | |
1270 | */ | |
1da177e4 | 1271 | |
db14fc3a MS |
1272 | struct select_data { |
1273 | struct dentry *start; | |
1274 | struct list_head dispose; | |
1275 | int found; | |
1276 | }; | |
23044507 | 1277 | |
db14fc3a MS |
1278 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
1279 | { | |
1280 | struct select_data *data = _data; | |
1281 | enum d_walk_ret ret = D_WALK_CONTINUE; | |
1da177e4 | 1282 | |
db14fc3a MS |
1283 | if (data->start == dentry) |
1284 | goto out; | |
2fd6b7f5 | 1285 | |
1da177e4 | 1286 | /* |
db14fc3a MS |
1287 | * move only zero ref count dentries to the dispose list. |
1288 | * | |
1289 | * Those which are presently on the shrink list, being processed | |
1290 | * by shrink_dentry_list(), shouldn't be moved. Otherwise the | |
1291 | * loop in shrink_dcache_parent() might not make any progress | |
1292 | * and loop forever. | |
1da177e4 | 1293 | */ |
db14fc3a MS |
1294 | if (dentry->d_lockref.count) { |
1295 | dentry_lru_del(dentry); | |
1296 | } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { | |
1297 | dentry_lru_move_list(dentry, &data->dispose); | |
1298 | dentry->d_flags |= DCACHE_SHRINK_LIST; | |
1299 | data->found++; | |
1300 | ret = D_WALK_NORETRY; | |
1da177e4 | 1301 | } |
db14fc3a MS |
1302 | /* |
1303 | * We can return to the caller if we have found some (this | |
1304 | * ensures forward progress). We'll be coming back to find | |
1305 | * the rest. | |
1306 | */ | |
1307 | if (data->found && need_resched()) | |
1308 | ret = D_WALK_QUIT; | |
1da177e4 | 1309 | out: |
db14fc3a | 1310 | return ret; |
1da177e4 LT |
1311 | } |
1312 | ||
1313 | /** | |
1314 | * shrink_dcache_parent - prune dcache | |
1315 | * @parent: parent of entries to prune | |
1316 | * | |
1317 | * Prune the dcache to remove unused children of the parent dentry. | |
1318 | */ | |
db14fc3a | 1319 | void shrink_dcache_parent(struct dentry *parent) |
1da177e4 | 1320 | { |
db14fc3a MS |
1321 | for (;;) { |
1322 | struct select_data data; | |
1da177e4 | 1323 | |
db14fc3a MS |
1324 | INIT_LIST_HEAD(&data.dispose); |
1325 | data.start = parent; | |
1326 | data.found = 0; | |
1327 | ||
1328 | d_walk(parent, &data, select_collect, NULL); | |
1329 | if (!data.found) | |
1330 | break; | |
1331 | ||
1332 | shrink_dentry_list(&data.dispose); | |
421348f1 GT |
1333 | cond_resched(); |
1334 | } | |
1da177e4 | 1335 | } |
ec4f8605 | 1336 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1337 | |
848ac114 MS |
1338 | static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry) |
1339 | { | |
1340 | struct select_data *data = _data; | |
1341 | ||
1342 | if (d_mountpoint(dentry)) { | |
1343 | data->found = -EBUSY; | |
1344 | return D_WALK_QUIT; | |
1345 | } | |
1346 | ||
1347 | return select_collect(_data, dentry); | |
1348 | } | |
1349 | ||
1350 | static void check_and_drop(void *_data) | |
1351 | { | |
1352 | struct select_data *data = _data; | |
1353 | ||
1354 | if (d_mountpoint(data->start)) | |
1355 | data->found = -EBUSY; | |
1356 | if (!data->found) | |
1357 | __d_drop(data->start); | |
1358 | } | |
1359 | ||
1360 | /** | |
1361 | * check_submounts_and_drop - prune dcache, check for submounts and drop | |
1362 | * | |
1363 | * All done as a single atomic operation relative to has_unlinked_ancestor(). | |
1364 | * Returns 0 if successfully unhashed @parent. If there were submounts then | |
1365 | * return -EBUSY. | |
1366 | * | |
1367 | * @dentry: dentry to prune and drop | |
1368 | */ | |
1369 | int check_submounts_and_drop(struct dentry *dentry) | |
1370 | { | |
1371 | int ret = 0; | |
1372 | ||
1373 | /* Negative dentries can be dropped without further checks */ | |
1374 | if (!dentry->d_inode) { | |
1375 | d_drop(dentry); | |
1376 | goto out; | |
1377 | } | |
1378 | ||
1379 | for (;;) { | |
1380 | struct select_data data; | |
1381 | ||
1382 | INIT_LIST_HEAD(&data.dispose); | |
1383 | data.start = dentry; | |
1384 | data.found = 0; | |
1385 | ||
1386 | d_walk(dentry, &data, check_and_collect, check_and_drop); | |
1387 | ret = data.found; | |
1388 | ||
1389 | if (!list_empty(&data.dispose)) | |
1390 | shrink_dentry_list(&data.dispose); | |
1391 | ||
1392 | if (ret <= 0) | |
1393 | break; | |
1394 | ||
1395 | cond_resched(); | |
1396 | } | |
1397 | ||
1398 | out: | |
1399 | return ret; | |
1400 | } | |
1401 | EXPORT_SYMBOL(check_submounts_and_drop); | |
1402 | ||
1da177e4 | 1403 | /** |
a4464dbc AV |
1404 | * __d_alloc - allocate a dcache entry |
1405 | * @sb: filesystem it will belong to | |
1da177e4 LT |
1406 | * @name: qstr of the name |
1407 | * | |
1408 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1409 | * available. On a success the dentry is returned. The name passed in is | |
1410 | * copied and the copy passed in may be reused after this call. | |
1411 | */ | |
1412 | ||
a4464dbc | 1413 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1da177e4 LT |
1414 | { |
1415 | struct dentry *dentry; | |
1416 | char *dname; | |
1417 | ||
e12ba74d | 1418 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1419 | if (!dentry) |
1420 | return NULL; | |
1421 | ||
6326c71f LT |
1422 | /* |
1423 | * We guarantee that the inline name is always NUL-terminated. | |
1424 | * This way the memcpy() done by the name switching in rename | |
1425 | * will still always have a NUL at the end, even if we might | |
1426 | * be overwriting an internal NUL character | |
1427 | */ | |
1428 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; | |
1da177e4 LT |
1429 | if (name->len > DNAME_INLINE_LEN-1) { |
1430 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
1431 | if (!dname) { | |
1432 | kmem_cache_free(dentry_cache, dentry); | |
1433 | return NULL; | |
1434 | } | |
1435 | } else { | |
1436 | dname = dentry->d_iname; | |
1437 | } | |
1da177e4 LT |
1438 | |
1439 | dentry->d_name.len = name->len; | |
1440 | dentry->d_name.hash = name->hash; | |
1441 | memcpy(dname, name->name, name->len); | |
1442 | dname[name->len] = 0; | |
1443 | ||
6326c71f LT |
1444 | /* Make sure we always see the terminating NUL character */ |
1445 | smp_wmb(); | |
1446 | dentry->d_name.name = dname; | |
1447 | ||
98474236 | 1448 | dentry->d_lockref.count = 1; |
dea3667b | 1449 | dentry->d_flags = 0; |
1da177e4 | 1450 | spin_lock_init(&dentry->d_lock); |
31e6b01f | 1451 | seqcount_init(&dentry->d_seq); |
1da177e4 | 1452 | dentry->d_inode = NULL; |
a4464dbc AV |
1453 | dentry->d_parent = dentry; |
1454 | dentry->d_sb = sb; | |
1da177e4 LT |
1455 | dentry->d_op = NULL; |
1456 | dentry->d_fsdata = NULL; | |
ceb5bdc2 | 1457 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1da177e4 LT |
1458 | INIT_LIST_HEAD(&dentry->d_lru); |
1459 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
b3d9b7a3 | 1460 | INIT_HLIST_NODE(&dentry->d_alias); |
2fd6b7f5 | 1461 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
a4464dbc | 1462 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1da177e4 | 1463 | |
3e880fb5 | 1464 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1465 | |
1da177e4 LT |
1466 | return dentry; |
1467 | } | |
a4464dbc AV |
1468 | |
1469 | /** | |
1470 | * d_alloc - allocate a dcache entry | |
1471 | * @parent: parent of entry to allocate | |
1472 | * @name: qstr of the name | |
1473 | * | |
1474 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1475 | * available. On a success the dentry is returned. The name passed in is | |
1476 | * copied and the copy passed in may be reused after this call. | |
1477 | */ | |
1478 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1479 | { | |
1480 | struct dentry *dentry = __d_alloc(parent->d_sb, name); | |
1481 | if (!dentry) | |
1482 | return NULL; | |
1483 | ||
1484 | spin_lock(&parent->d_lock); | |
1485 | /* | |
1486 | * don't need child lock because it is not subject | |
1487 | * to concurrency here | |
1488 | */ | |
1489 | __dget_dlock(parent); | |
1490 | dentry->d_parent = parent; | |
1491 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); | |
1492 | spin_unlock(&parent->d_lock); | |
1493 | ||
1494 | return dentry; | |
1495 | } | |
ec4f8605 | 1496 | EXPORT_SYMBOL(d_alloc); |
1da177e4 | 1497 | |
4b936885 NP |
1498 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1499 | { | |
a4464dbc AV |
1500 | struct dentry *dentry = __d_alloc(sb, name); |
1501 | if (dentry) | |
4b936885 | 1502 | dentry->d_flags |= DCACHE_DISCONNECTED; |
4b936885 NP |
1503 | return dentry; |
1504 | } | |
1505 | EXPORT_SYMBOL(d_alloc_pseudo); | |
1506 | ||
1da177e4 LT |
1507 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1508 | { | |
1509 | struct qstr q; | |
1510 | ||
1511 | q.name = name; | |
1512 | q.len = strlen(name); | |
1513 | q.hash = full_name_hash(q.name, q.len); | |
1514 | return d_alloc(parent, &q); | |
1515 | } | |
ef26ca97 | 1516 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1517 | |
fb045adb NP |
1518 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1519 | { | |
6f7f7caa LT |
1520 | WARN_ON_ONCE(dentry->d_op); |
1521 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | | |
fb045adb NP |
1522 | DCACHE_OP_COMPARE | |
1523 | DCACHE_OP_REVALIDATE | | |
ecf3d1f1 | 1524 | DCACHE_OP_WEAK_REVALIDATE | |
fb045adb NP |
1525 | DCACHE_OP_DELETE )); |
1526 | dentry->d_op = op; | |
1527 | if (!op) | |
1528 | return; | |
1529 | if (op->d_hash) | |
1530 | dentry->d_flags |= DCACHE_OP_HASH; | |
1531 | if (op->d_compare) | |
1532 | dentry->d_flags |= DCACHE_OP_COMPARE; | |
1533 | if (op->d_revalidate) | |
1534 | dentry->d_flags |= DCACHE_OP_REVALIDATE; | |
ecf3d1f1 JL |
1535 | if (op->d_weak_revalidate) |
1536 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; | |
fb045adb NP |
1537 | if (op->d_delete) |
1538 | dentry->d_flags |= DCACHE_OP_DELETE; | |
f0023bc6 SW |
1539 | if (op->d_prune) |
1540 | dentry->d_flags |= DCACHE_OP_PRUNE; | |
fb045adb NP |
1541 | |
1542 | } | |
1543 | EXPORT_SYMBOL(d_set_d_op); | |
1544 | ||
360da900 OH |
1545 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1546 | { | |
b23fb0a6 | 1547 | spin_lock(&dentry->d_lock); |
9875cf80 DH |
1548 | if (inode) { |
1549 | if (unlikely(IS_AUTOMOUNT(inode))) | |
1550 | dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; | |
b3d9b7a3 | 1551 | hlist_add_head(&dentry->d_alias, &inode->i_dentry); |
9875cf80 | 1552 | } |
360da900 | 1553 | dentry->d_inode = inode; |
31e6b01f | 1554 | dentry_rcuwalk_barrier(dentry); |
b23fb0a6 | 1555 | spin_unlock(&dentry->d_lock); |
360da900 OH |
1556 | fsnotify_d_instantiate(dentry, inode); |
1557 | } | |
1558 | ||
1da177e4 LT |
1559 | /** |
1560 | * d_instantiate - fill in inode information for a dentry | |
1561 | * @entry: dentry to complete | |
1562 | * @inode: inode to attach to this dentry | |
1563 | * | |
1564 | * Fill in inode information in the entry. | |
1565 | * | |
1566 | * This turns negative dentries into productive full members | |
1567 | * of society. | |
1568 | * | |
1569 | * NOTE! This assumes that the inode count has been incremented | |
1570 | * (or otherwise set) by the caller to indicate that it is now | |
1571 | * in use by the dcache. | |
1572 | */ | |
1573 | ||
1574 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1575 | { | |
b3d9b7a3 | 1576 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
873feea0 NP |
1577 | if (inode) |
1578 | spin_lock(&inode->i_lock); | |
360da900 | 1579 | __d_instantiate(entry, inode); |
873feea0 NP |
1580 | if (inode) |
1581 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
1582 | security_d_instantiate(entry, inode); |
1583 | } | |
ec4f8605 | 1584 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 LT |
1585 | |
1586 | /** | |
1587 | * d_instantiate_unique - instantiate a non-aliased dentry | |
1588 | * @entry: dentry to instantiate | |
1589 | * @inode: inode to attach to this dentry | |
1590 | * | |
1591 | * Fill in inode information in the entry. On success, it returns NULL. | |
1592 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 1593 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1594 | * |
1595 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1596 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1597 | * |
1598 | * This also assumes that the inode count has been incremented | |
1599 | * (or otherwise set) by the caller to indicate that it is now | |
1600 | * in use by the dcache. | |
1da177e4 | 1601 | */ |
770bfad8 DH |
1602 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1603 | struct inode *inode) | |
1da177e4 LT |
1604 | { |
1605 | struct dentry *alias; | |
1606 | int len = entry->d_name.len; | |
1607 | const char *name = entry->d_name.name; | |
1608 | unsigned int hash = entry->d_name.hash; | |
1609 | ||
770bfad8 | 1610 | if (!inode) { |
360da900 | 1611 | __d_instantiate(entry, NULL); |
770bfad8 DH |
1612 | return NULL; |
1613 | } | |
1614 | ||
b67bfe0d | 1615 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
9abca360 NP |
1616 | /* |
1617 | * Don't need alias->d_lock here, because aliases with | |
1618 | * d_parent == entry->d_parent are not subject to name or | |
1619 | * parent changes, because the parent inode i_mutex is held. | |
1620 | */ | |
12f8ad4b | 1621 | if (alias->d_name.hash != hash) |
1da177e4 LT |
1622 | continue; |
1623 | if (alias->d_parent != entry->d_parent) | |
1624 | continue; | |
ee983e89 LT |
1625 | if (alias->d_name.len != len) |
1626 | continue; | |
12f8ad4b | 1627 | if (dentry_cmp(alias, name, len)) |
1da177e4 | 1628 | continue; |
dc0474be | 1629 | __dget(alias); |
1da177e4 LT |
1630 | return alias; |
1631 | } | |
770bfad8 | 1632 | |
360da900 | 1633 | __d_instantiate(entry, inode); |
1da177e4 LT |
1634 | return NULL; |
1635 | } | |
770bfad8 DH |
1636 | |
1637 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1638 | { | |
1639 | struct dentry *result; | |
1640 | ||
b3d9b7a3 | 1641 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
770bfad8 | 1642 | |
873feea0 NP |
1643 | if (inode) |
1644 | spin_lock(&inode->i_lock); | |
770bfad8 | 1645 | result = __d_instantiate_unique(entry, inode); |
873feea0 NP |
1646 | if (inode) |
1647 | spin_unlock(&inode->i_lock); | |
770bfad8 DH |
1648 | |
1649 | if (!result) { | |
1650 | security_d_instantiate(entry, inode); | |
1651 | return NULL; | |
1652 | } | |
1653 | ||
1654 | BUG_ON(!d_unhashed(result)); | |
1655 | iput(inode); | |
1656 | return result; | |
1657 | } | |
1658 | ||
1da177e4 LT |
1659 | EXPORT_SYMBOL(d_instantiate_unique); |
1660 | ||
adc0e91a AV |
1661 | struct dentry *d_make_root(struct inode *root_inode) |
1662 | { | |
1663 | struct dentry *res = NULL; | |
1664 | ||
1665 | if (root_inode) { | |
26fe5750 | 1666 | static const struct qstr name = QSTR_INIT("/", 1); |
adc0e91a AV |
1667 | |
1668 | res = __d_alloc(root_inode->i_sb, &name); | |
1669 | if (res) | |
1670 | d_instantiate(res, root_inode); | |
1671 | else | |
1672 | iput(root_inode); | |
1673 | } | |
1674 | return res; | |
1675 | } | |
1676 | EXPORT_SYMBOL(d_make_root); | |
1677 | ||
d891eedb BF |
1678 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1679 | { | |
1680 | struct dentry *alias; | |
1681 | ||
b3d9b7a3 | 1682 | if (hlist_empty(&inode->i_dentry)) |
d891eedb | 1683 | return NULL; |
b3d9b7a3 | 1684 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias); |
d891eedb BF |
1685 | __dget(alias); |
1686 | return alias; | |
1687 | } | |
1688 | ||
46f72b34 SW |
1689 | /** |
1690 | * d_find_any_alias - find any alias for a given inode | |
1691 | * @inode: inode to find an alias for | |
1692 | * | |
1693 | * If any aliases exist for the given inode, take and return a | |
1694 | * reference for one of them. If no aliases exist, return %NULL. | |
1695 | */ | |
1696 | struct dentry *d_find_any_alias(struct inode *inode) | |
d891eedb BF |
1697 | { |
1698 | struct dentry *de; | |
1699 | ||
1700 | spin_lock(&inode->i_lock); | |
1701 | de = __d_find_any_alias(inode); | |
1702 | spin_unlock(&inode->i_lock); | |
1703 | return de; | |
1704 | } | |
46f72b34 | 1705 | EXPORT_SYMBOL(d_find_any_alias); |
d891eedb | 1706 | |
4ea3ada2 CH |
1707 | /** |
1708 | * d_obtain_alias - find or allocate a dentry for a given inode | |
1709 | * @inode: inode to allocate the dentry for | |
1710 | * | |
1711 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1712 | * similar open by handle operations. The returned dentry may be anonymous, | |
1713 | * or may have a full name (if the inode was already in the cache). | |
1714 | * | |
1715 | * When called on a directory inode, we must ensure that the inode only ever | |
1716 | * has one dentry. If a dentry is found, that is returned instead of | |
1717 | * allocating a new one. | |
1718 | * | |
1719 | * On successful return, the reference to the inode has been transferred | |
44003728 CH |
1720 | * to the dentry. In case of an error the reference on the inode is released. |
1721 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1722 | * be passed in and will be the error will be propagate to the return value, | |
1723 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
4ea3ada2 CH |
1724 | */ |
1725 | struct dentry *d_obtain_alias(struct inode *inode) | |
1726 | { | |
b911a6bd | 1727 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
9308a612 CH |
1728 | struct dentry *tmp; |
1729 | struct dentry *res; | |
4ea3ada2 CH |
1730 | |
1731 | if (!inode) | |
44003728 | 1732 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1733 | if (IS_ERR(inode)) |
1734 | return ERR_CAST(inode); | |
1735 | ||
d891eedb | 1736 | res = d_find_any_alias(inode); |
9308a612 CH |
1737 | if (res) |
1738 | goto out_iput; | |
1739 | ||
a4464dbc | 1740 | tmp = __d_alloc(inode->i_sb, &anonstring); |
9308a612 CH |
1741 | if (!tmp) { |
1742 | res = ERR_PTR(-ENOMEM); | |
1743 | goto out_iput; | |
4ea3ada2 | 1744 | } |
b5c84bf6 | 1745 | |
873feea0 | 1746 | spin_lock(&inode->i_lock); |
d891eedb | 1747 | res = __d_find_any_alias(inode); |
9308a612 | 1748 | if (res) { |
873feea0 | 1749 | spin_unlock(&inode->i_lock); |
9308a612 CH |
1750 | dput(tmp); |
1751 | goto out_iput; | |
1752 | } | |
1753 | ||
1754 | /* attach a disconnected dentry */ | |
1755 | spin_lock(&tmp->d_lock); | |
9308a612 CH |
1756 | tmp->d_inode = inode; |
1757 | tmp->d_flags |= DCACHE_DISCONNECTED; | |
b3d9b7a3 | 1758 | hlist_add_head(&tmp->d_alias, &inode->i_dentry); |
1879fd6a | 1759 | hlist_bl_lock(&tmp->d_sb->s_anon); |
ceb5bdc2 | 1760 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1879fd6a | 1761 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
9308a612 | 1762 | spin_unlock(&tmp->d_lock); |
873feea0 | 1763 | spin_unlock(&inode->i_lock); |
24ff6663 | 1764 | security_d_instantiate(tmp, inode); |
9308a612 | 1765 | |
9308a612 CH |
1766 | return tmp; |
1767 | ||
1768 | out_iput: | |
24ff6663 JB |
1769 | if (res && !IS_ERR(res)) |
1770 | security_d_instantiate(res, inode); | |
9308a612 CH |
1771 | iput(inode); |
1772 | return res; | |
4ea3ada2 | 1773 | } |
adc48720 | 1774 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 LT |
1775 | |
1776 | /** | |
1777 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1778 | * @inode: the inode which may have a disconnected dentry | |
1779 | * @dentry: a negative dentry which we want to point to the inode. | |
1780 | * | |
1781 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1782 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1783 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1784 | * | |
1785 | * This is needed in the lookup routine of any filesystem that is exportable | |
1786 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1787 | * | |
1788 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1789 | * is returned. This matches the expected return value of ->lookup. | |
1790 | * | |
6d4ade98 SW |
1791 | * Cluster filesystems may call this function with a negative, hashed dentry. |
1792 | * In that case, we know that the inode will be a regular file, and also this | |
1793 | * will only occur during atomic_open. So we need to check for the dentry | |
1794 | * being already hashed only in the final case. | |
1da177e4 LT |
1795 | */ |
1796 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1797 | { | |
1798 | struct dentry *new = NULL; | |
1799 | ||
a9049376 AV |
1800 | if (IS_ERR(inode)) |
1801 | return ERR_CAST(inode); | |
1802 | ||
21c0d8fd | 1803 | if (inode && S_ISDIR(inode->i_mode)) { |
873feea0 | 1804 | spin_lock(&inode->i_lock); |
32ba9c3f | 1805 | new = __d_find_alias(inode, 1); |
1da177e4 | 1806 | if (new) { |
32ba9c3f | 1807 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
873feea0 | 1808 | spin_unlock(&inode->i_lock); |
1da177e4 | 1809 | security_d_instantiate(new, inode); |
1da177e4 LT |
1810 | d_move(new, dentry); |
1811 | iput(inode); | |
1812 | } else { | |
873feea0 | 1813 | /* already taking inode->i_lock, so d_add() by hand */ |
360da900 | 1814 | __d_instantiate(dentry, inode); |
873feea0 | 1815 | spin_unlock(&inode->i_lock); |
1da177e4 LT |
1816 | security_d_instantiate(dentry, inode); |
1817 | d_rehash(dentry); | |
1818 | } | |
6d4ade98 SW |
1819 | } else { |
1820 | d_instantiate(dentry, inode); | |
1821 | if (d_unhashed(dentry)) | |
1822 | d_rehash(dentry); | |
1823 | } | |
1da177e4 LT |
1824 | return new; |
1825 | } | |
ec4f8605 | 1826 | EXPORT_SYMBOL(d_splice_alias); |
1da177e4 | 1827 | |
9403540c BN |
1828 | /** |
1829 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
1830 | * @inode: the inode case-insensitive lookup has found | |
1831 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
1832 | * @name: the case-exact name to be associated with the returned dentry | |
1833 | * | |
1834 | * This is to avoid filling the dcache with case-insensitive names to the | |
1835 | * same inode, only the actual correct case is stored in the dcache for | |
1836 | * case-insensitive filesystems. | |
1837 | * | |
1838 | * For a case-insensitive lookup match and if the the case-exact dentry | |
1839 | * already exists in in the dcache, use it and return it. | |
1840 | * | |
1841 | * If no entry exists with the exact case name, allocate new dentry with | |
1842 | * the exact case, and return the spliced entry. | |
1843 | */ | |
e45b590b | 1844 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
1845 | struct qstr *name) |
1846 | { | |
9403540c BN |
1847 | struct dentry *found; |
1848 | struct dentry *new; | |
1849 | ||
b6520c81 CH |
1850 | /* |
1851 | * First check if a dentry matching the name already exists, | |
1852 | * if not go ahead and create it now. | |
1853 | */ | |
9403540c | 1854 | found = d_hash_and_lookup(dentry->d_parent, name); |
4f522a24 AV |
1855 | if (unlikely(IS_ERR(found))) |
1856 | goto err_out; | |
9403540c BN |
1857 | if (!found) { |
1858 | new = d_alloc(dentry->d_parent, name); | |
1859 | if (!new) { | |
4f522a24 | 1860 | found = ERR_PTR(-ENOMEM); |
9403540c BN |
1861 | goto err_out; |
1862 | } | |
b6520c81 | 1863 | |
9403540c BN |
1864 | found = d_splice_alias(inode, new); |
1865 | if (found) { | |
1866 | dput(new); | |
1867 | return found; | |
1868 | } | |
1869 | return new; | |
1870 | } | |
b6520c81 CH |
1871 | |
1872 | /* | |
1873 | * If a matching dentry exists, and it's not negative use it. | |
1874 | * | |
1875 | * Decrement the reference count to balance the iget() done | |
1876 | * earlier on. | |
1877 | */ | |
9403540c BN |
1878 | if (found->d_inode) { |
1879 | if (unlikely(found->d_inode != inode)) { | |
1880 | /* This can't happen because bad inodes are unhashed. */ | |
1881 | BUG_ON(!is_bad_inode(inode)); | |
1882 | BUG_ON(!is_bad_inode(found->d_inode)); | |
1883 | } | |
9403540c BN |
1884 | iput(inode); |
1885 | return found; | |
1886 | } | |
b6520c81 | 1887 | |
9403540c | 1888 | /* |
9403540c | 1889 | * Negative dentry: instantiate it unless the inode is a directory and |
b6520c81 | 1890 | * already has a dentry. |
9403540c | 1891 | */ |
4513d899 AV |
1892 | new = d_splice_alias(inode, found); |
1893 | if (new) { | |
1894 | dput(found); | |
1895 | found = new; | |
9403540c | 1896 | } |
4513d899 | 1897 | return found; |
9403540c BN |
1898 | |
1899 | err_out: | |
1900 | iput(inode); | |
4f522a24 | 1901 | return found; |
9403540c | 1902 | } |
ec4f8605 | 1903 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 | 1904 | |
12f8ad4b LT |
1905 | /* |
1906 | * Do the slow-case of the dentry name compare. | |
1907 | * | |
1908 | * Unlike the dentry_cmp() function, we need to atomically | |
da53be12 | 1909 | * load the name and length information, so that the |
12f8ad4b LT |
1910 | * filesystem can rely on them, and can use the 'name' and |
1911 | * 'len' information without worrying about walking off the | |
1912 | * end of memory etc. | |
1913 | * | |
1914 | * Thus the read_seqcount_retry() and the "duplicate" info | |
1915 | * in arguments (the low-level filesystem should not look | |
1916 | * at the dentry inode or name contents directly, since | |
1917 | * rename can change them while we're in RCU mode). | |
1918 | */ | |
1919 | enum slow_d_compare { | |
1920 | D_COMP_OK, | |
1921 | D_COMP_NOMATCH, | |
1922 | D_COMP_SEQRETRY, | |
1923 | }; | |
1924 | ||
1925 | static noinline enum slow_d_compare slow_dentry_cmp( | |
1926 | const struct dentry *parent, | |
12f8ad4b LT |
1927 | struct dentry *dentry, |
1928 | unsigned int seq, | |
1929 | const struct qstr *name) | |
1930 | { | |
1931 | int tlen = dentry->d_name.len; | |
1932 | const char *tname = dentry->d_name.name; | |
12f8ad4b LT |
1933 | |
1934 | if (read_seqcount_retry(&dentry->d_seq, seq)) { | |
1935 | cpu_relax(); | |
1936 | return D_COMP_SEQRETRY; | |
1937 | } | |
da53be12 | 1938 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
12f8ad4b LT |
1939 | return D_COMP_NOMATCH; |
1940 | return D_COMP_OK; | |
1941 | } | |
1942 | ||
31e6b01f NP |
1943 | /** |
1944 | * __d_lookup_rcu - search for a dentry (racy, store-free) | |
1945 | * @parent: parent dentry | |
1946 | * @name: qstr of name we wish to find | |
1f1e6e52 | 1947 | * @seqp: returns d_seq value at the point where the dentry was found |
31e6b01f NP |
1948 | * Returns: dentry, or NULL |
1949 | * | |
1950 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name | |
1951 | * resolution (store-free path walking) design described in | |
1952 | * Documentation/filesystems/path-lookup.txt. | |
1953 | * | |
1954 | * This is not to be used outside core vfs. | |
1955 | * | |
1956 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock | |
1957 | * held, and rcu_read_lock held. The returned dentry must not be stored into | |
1958 | * without taking d_lock and checking d_seq sequence count against @seq | |
1959 | * returned here. | |
1960 | * | |
15570086 | 1961 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
31e6b01f NP |
1962 | * function. |
1963 | * | |
1964 | * Alternatively, __d_lookup_rcu may be called again to look up the child of | |
1965 | * the returned dentry, so long as its parent's seqlock is checked after the | |
1966 | * child is looked up. Thus, an interlocking stepping of sequence lock checks | |
1967 | * is formed, giving integrity down the path walk. | |
12f8ad4b LT |
1968 | * |
1969 | * NOTE! The caller *has* to check the resulting dentry against the sequence | |
1970 | * number we've returned before using any of the resulting dentry state! | |
31e6b01f | 1971 | */ |
8966be90 LT |
1972 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
1973 | const struct qstr *name, | |
da53be12 | 1974 | unsigned *seqp) |
31e6b01f | 1975 | { |
26fe5750 | 1976 | u64 hashlen = name->hash_len; |
31e6b01f | 1977 | const unsigned char *str = name->name; |
26fe5750 | 1978 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
ceb5bdc2 | 1979 | struct hlist_bl_node *node; |
31e6b01f NP |
1980 | struct dentry *dentry; |
1981 | ||
1982 | /* | |
1983 | * Note: There is significant duplication with __d_lookup_rcu which is | |
1984 | * required to prevent single threaded performance regressions | |
1985 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
1986 | * Keep the two functions in sync. | |
1987 | */ | |
1988 | ||
1989 | /* | |
1990 | * The hash list is protected using RCU. | |
1991 | * | |
1992 | * Carefully use d_seq when comparing a candidate dentry, to avoid | |
1993 | * races with d_move(). | |
1994 | * | |
1995 | * It is possible that concurrent renames can mess up our list | |
1996 | * walk here and result in missing our dentry, resulting in the | |
1997 | * false-negative result. d_lookup() protects against concurrent | |
1998 | * renames using rename_lock seqlock. | |
1999 | * | |
b0a4bb83 | 2000 | * See Documentation/filesystems/path-lookup.txt for more details. |
31e6b01f | 2001 | */ |
b07ad996 | 2002 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
8966be90 | 2003 | unsigned seq; |
31e6b01f | 2004 | |
31e6b01f | 2005 | seqretry: |
12f8ad4b LT |
2006 | /* |
2007 | * The dentry sequence count protects us from concurrent | |
da53be12 | 2008 | * renames, and thus protects parent and name fields. |
12f8ad4b LT |
2009 | * |
2010 | * The caller must perform a seqcount check in order | |
da53be12 | 2011 | * to do anything useful with the returned dentry. |
12f8ad4b LT |
2012 | * |
2013 | * NOTE! We do a "raw" seqcount_begin here. That means that | |
2014 | * we don't wait for the sequence count to stabilize if it | |
2015 | * is in the middle of a sequence change. If we do the slow | |
2016 | * dentry compare, we will do seqretries until it is stable, | |
2017 | * and if we end up with a successful lookup, we actually | |
2018 | * want to exit RCU lookup anyway. | |
2019 | */ | |
2020 | seq = raw_seqcount_begin(&dentry->d_seq); | |
31e6b01f NP |
2021 | if (dentry->d_parent != parent) |
2022 | continue; | |
2e321806 LT |
2023 | if (d_unhashed(dentry)) |
2024 | continue; | |
12f8ad4b | 2025 | |
830c0f0e | 2026 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
26fe5750 LT |
2027 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
2028 | continue; | |
da53be12 LT |
2029 | *seqp = seq; |
2030 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { | |
12f8ad4b LT |
2031 | case D_COMP_OK: |
2032 | return dentry; | |
2033 | case D_COMP_NOMATCH: | |
31e6b01f | 2034 | continue; |
12f8ad4b LT |
2035 | default: |
2036 | goto seqretry; | |
2037 | } | |
31e6b01f | 2038 | } |
12f8ad4b | 2039 | |
26fe5750 | 2040 | if (dentry->d_name.hash_len != hashlen) |
ee983e89 | 2041 | continue; |
da53be12 | 2042 | *seqp = seq; |
26fe5750 | 2043 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
12f8ad4b | 2044 | return dentry; |
31e6b01f NP |
2045 | } |
2046 | return NULL; | |
2047 | } | |
2048 | ||
1da177e4 LT |
2049 | /** |
2050 | * d_lookup - search for a dentry | |
2051 | * @parent: parent dentry | |
2052 | * @name: qstr of name we wish to find | |
b04f784e | 2053 | * Returns: dentry, or NULL |
1da177e4 | 2054 | * |
b04f784e NP |
2055 | * d_lookup searches the children of the parent dentry for the name in |
2056 | * question. If the dentry is found its reference count is incremented and the | |
2057 | * dentry is returned. The caller must use dput to free the entry when it has | |
2058 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 2059 | */ |
da2d8455 | 2060 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 | 2061 | { |
31e6b01f | 2062 | struct dentry *dentry; |
949854d0 | 2063 | unsigned seq; |
1da177e4 LT |
2064 | |
2065 | do { | |
2066 | seq = read_seqbegin(&rename_lock); | |
2067 | dentry = __d_lookup(parent, name); | |
2068 | if (dentry) | |
2069 | break; | |
2070 | } while (read_seqretry(&rename_lock, seq)); | |
2071 | return dentry; | |
2072 | } | |
ec4f8605 | 2073 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 2074 | |
31e6b01f | 2075 | /** |
b04f784e NP |
2076 | * __d_lookup - search for a dentry (racy) |
2077 | * @parent: parent dentry | |
2078 | * @name: qstr of name we wish to find | |
2079 | * Returns: dentry, or NULL | |
2080 | * | |
2081 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
2082 | * false-negative result due to unrelated rename activity. | |
2083 | * | |
2084 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
2085 | * however it must be used carefully, eg. with a following d_lookup in | |
2086 | * the case of failure. | |
2087 | * | |
2088 | * __d_lookup callers must be commented. | |
2089 | */ | |
a713ca2a | 2090 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 LT |
2091 | { |
2092 | unsigned int len = name->len; | |
2093 | unsigned int hash = name->hash; | |
2094 | const unsigned char *str = name->name; | |
b07ad996 | 2095 | struct hlist_bl_head *b = d_hash(parent, hash); |
ceb5bdc2 | 2096 | struct hlist_bl_node *node; |
31e6b01f | 2097 | struct dentry *found = NULL; |
665a7583 | 2098 | struct dentry *dentry; |
1da177e4 | 2099 | |
31e6b01f NP |
2100 | /* |
2101 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2102 | * required to prevent single threaded performance regressions | |
2103 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2104 | * Keep the two functions in sync. | |
2105 | */ | |
2106 | ||
b04f784e NP |
2107 | /* |
2108 | * The hash list is protected using RCU. | |
2109 | * | |
2110 | * Take d_lock when comparing a candidate dentry, to avoid races | |
2111 | * with d_move(). | |
2112 | * | |
2113 | * It is possible that concurrent renames can mess up our list | |
2114 | * walk here and result in missing our dentry, resulting in the | |
2115 | * false-negative result. d_lookup() protects against concurrent | |
2116 | * renames using rename_lock seqlock. | |
2117 | * | |
b0a4bb83 | 2118 | * See Documentation/filesystems/path-lookup.txt for more details. |
b04f784e | 2119 | */ |
1da177e4 LT |
2120 | rcu_read_lock(); |
2121 | ||
b07ad996 | 2122 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1da177e4 | 2123 | |
1da177e4 LT |
2124 | if (dentry->d_name.hash != hash) |
2125 | continue; | |
1da177e4 LT |
2126 | |
2127 | spin_lock(&dentry->d_lock); | |
1da177e4 LT |
2128 | if (dentry->d_parent != parent) |
2129 | goto next; | |
d0185c08 LT |
2130 | if (d_unhashed(dentry)) |
2131 | goto next; | |
2132 | ||
1da177e4 LT |
2133 | /* |
2134 | * It is safe to compare names since d_move() cannot | |
2135 | * change the qstr (protected by d_lock). | |
2136 | */ | |
fb045adb | 2137 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
12f8ad4b LT |
2138 | int tlen = dentry->d_name.len; |
2139 | const char *tname = dentry->d_name.name; | |
da53be12 | 2140 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
1da177e4 LT |
2141 | goto next; |
2142 | } else { | |
ee983e89 LT |
2143 | if (dentry->d_name.len != len) |
2144 | goto next; | |
12f8ad4b | 2145 | if (dentry_cmp(dentry, str, len)) |
1da177e4 LT |
2146 | goto next; |
2147 | } | |
2148 | ||
98474236 | 2149 | dentry->d_lockref.count++; |
d0185c08 | 2150 | found = dentry; |
1da177e4 LT |
2151 | spin_unlock(&dentry->d_lock); |
2152 | break; | |
2153 | next: | |
2154 | spin_unlock(&dentry->d_lock); | |
2155 | } | |
2156 | rcu_read_unlock(); | |
2157 | ||
2158 | return found; | |
2159 | } | |
2160 | ||
3e7e241f EB |
2161 | /** |
2162 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
2163 | * @dir: Directory to search in | |
2164 | * @name: qstr of name we wish to find | |
2165 | * | |
4f522a24 | 2166 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
3e7e241f EB |
2167 | */ |
2168 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
2169 | { | |
3e7e241f EB |
2170 | /* |
2171 | * Check for a fs-specific hash function. Note that we must | |
2172 | * calculate the standard hash first, as the d_op->d_hash() | |
2173 | * routine may choose to leave the hash value unchanged. | |
2174 | */ | |
2175 | name->hash = full_name_hash(name->name, name->len); | |
fb045adb | 2176 | if (dir->d_flags & DCACHE_OP_HASH) { |
da53be12 | 2177 | int err = dir->d_op->d_hash(dir, name); |
4f522a24 AV |
2178 | if (unlikely(err < 0)) |
2179 | return ERR_PTR(err); | |
3e7e241f | 2180 | } |
4f522a24 | 2181 | return d_lookup(dir, name); |
3e7e241f | 2182 | } |
4f522a24 | 2183 | EXPORT_SYMBOL(d_hash_and_lookup); |
3e7e241f | 2184 | |
1da177e4 | 2185 | /** |
786a5e15 | 2186 | * d_validate - verify dentry provided from insecure source (deprecated) |
1da177e4 | 2187 | * @dentry: The dentry alleged to be valid child of @dparent |
ff5fdb61 | 2188 | * @dparent: The parent dentry (known to be valid) |
1da177e4 LT |
2189 | * |
2190 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
2191 | * This is used by ncpfs in its readdir implementation. | |
2192 | * Zero is returned in the dentry is invalid. | |
786a5e15 NP |
2193 | * |
2194 | * This function is slow for big directories, and deprecated, do not use it. | |
1da177e4 | 2195 | */ |
d3a23e16 | 2196 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
1da177e4 | 2197 | { |
786a5e15 | 2198 | struct dentry *child; |
d3a23e16 | 2199 | |
2fd6b7f5 | 2200 | spin_lock(&dparent->d_lock); |
786a5e15 NP |
2201 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
2202 | if (dentry == child) { | |
2fd6b7f5 | 2203 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
dc0474be | 2204 | __dget_dlock(dentry); |
2fd6b7f5 NP |
2205 | spin_unlock(&dentry->d_lock); |
2206 | spin_unlock(&dparent->d_lock); | |
1da177e4 LT |
2207 | return 1; |
2208 | } | |
2209 | } | |
2fd6b7f5 | 2210 | spin_unlock(&dparent->d_lock); |
786a5e15 | 2211 | |
1da177e4 LT |
2212 | return 0; |
2213 | } | |
ec4f8605 | 2214 | EXPORT_SYMBOL(d_validate); |
1da177e4 LT |
2215 | |
2216 | /* | |
2217 | * When a file is deleted, we have two options: | |
2218 | * - turn this dentry into a negative dentry | |
2219 | * - unhash this dentry and free it. | |
2220 | * | |
2221 | * Usually, we want to just turn this into | |
2222 | * a negative dentry, but if anybody else is | |
2223 | * currently using the dentry or the inode | |
2224 | * we can't do that and we fall back on removing | |
2225 | * it from the hash queues and waiting for | |
2226 | * it to be deleted later when it has no users | |
2227 | */ | |
2228 | ||
2229 | /** | |
2230 | * d_delete - delete a dentry | |
2231 | * @dentry: The dentry to delete | |
2232 | * | |
2233 | * Turn the dentry into a negative dentry if possible, otherwise | |
2234 | * remove it from the hash queues so it can be deleted later | |
2235 | */ | |
2236 | ||
2237 | void d_delete(struct dentry * dentry) | |
2238 | { | |
873feea0 | 2239 | struct inode *inode; |
7a91bf7f | 2240 | int isdir = 0; |
1da177e4 LT |
2241 | /* |
2242 | * Are we the only user? | |
2243 | */ | |
357f8e65 | 2244 | again: |
1da177e4 | 2245 | spin_lock(&dentry->d_lock); |
873feea0 NP |
2246 | inode = dentry->d_inode; |
2247 | isdir = S_ISDIR(inode->i_mode); | |
98474236 | 2248 | if (dentry->d_lockref.count == 1) { |
1fe0c023 | 2249 | if (!spin_trylock(&inode->i_lock)) { |
357f8e65 NP |
2250 | spin_unlock(&dentry->d_lock); |
2251 | cpu_relax(); | |
2252 | goto again; | |
2253 | } | |
13e3c5e5 | 2254 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
31e6b01f | 2255 | dentry_unlink_inode(dentry); |
7a91bf7f | 2256 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
2257 | return; |
2258 | } | |
2259 | ||
2260 | if (!d_unhashed(dentry)) | |
2261 | __d_drop(dentry); | |
2262 | ||
2263 | spin_unlock(&dentry->d_lock); | |
7a91bf7f JM |
2264 | |
2265 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 2266 | } |
ec4f8605 | 2267 | EXPORT_SYMBOL(d_delete); |
1da177e4 | 2268 | |
b07ad996 | 2269 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
1da177e4 | 2270 | { |
ceb5bdc2 | 2271 | BUG_ON(!d_unhashed(entry)); |
1879fd6a | 2272 | hlist_bl_lock(b); |
dea3667b | 2273 | entry->d_flags |= DCACHE_RCUACCESS; |
b07ad996 | 2274 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
1879fd6a | 2275 | hlist_bl_unlock(b); |
1da177e4 LT |
2276 | } |
2277 | ||
770bfad8 DH |
2278 | static void _d_rehash(struct dentry * entry) |
2279 | { | |
2280 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
2281 | } | |
2282 | ||
1da177e4 LT |
2283 | /** |
2284 | * d_rehash - add an entry back to the hash | |
2285 | * @entry: dentry to add to the hash | |
2286 | * | |
2287 | * Adds a dentry to the hash according to its name. | |
2288 | */ | |
2289 | ||
2290 | void d_rehash(struct dentry * entry) | |
2291 | { | |
1da177e4 | 2292 | spin_lock(&entry->d_lock); |
770bfad8 | 2293 | _d_rehash(entry); |
1da177e4 | 2294 | spin_unlock(&entry->d_lock); |
1da177e4 | 2295 | } |
ec4f8605 | 2296 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 2297 | |
fb2d5b86 NP |
2298 | /** |
2299 | * dentry_update_name_case - update case insensitive dentry with a new name | |
2300 | * @dentry: dentry to be updated | |
2301 | * @name: new name | |
2302 | * | |
2303 | * Update a case insensitive dentry with new case of name. | |
2304 | * | |
2305 | * dentry must have been returned by d_lookup with name @name. Old and new | |
2306 | * name lengths must match (ie. no d_compare which allows mismatched name | |
2307 | * lengths). | |
2308 | * | |
2309 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
2310 | * keep renames and concurrent inserts, and readdir(2) away). | |
2311 | */ | |
2312 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
2313 | { | |
7ebfa57f | 2314 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
fb2d5b86 NP |
2315 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2316 | ||
fb2d5b86 | 2317 | spin_lock(&dentry->d_lock); |
31e6b01f | 2318 | write_seqcount_begin(&dentry->d_seq); |
fb2d5b86 | 2319 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
31e6b01f | 2320 | write_seqcount_end(&dentry->d_seq); |
fb2d5b86 | 2321 | spin_unlock(&dentry->d_lock); |
fb2d5b86 NP |
2322 | } |
2323 | EXPORT_SYMBOL(dentry_update_name_case); | |
2324 | ||
1da177e4 LT |
2325 | static void switch_names(struct dentry *dentry, struct dentry *target) |
2326 | { | |
2327 | if (dname_external(target)) { | |
2328 | if (dname_external(dentry)) { | |
2329 | /* | |
2330 | * Both external: swap the pointers | |
2331 | */ | |
9a8d5bb4 | 2332 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
2333 | } else { |
2334 | /* | |
2335 | * dentry:internal, target:external. Steal target's | |
2336 | * storage and make target internal. | |
2337 | */ | |
321bcf92 BF |
2338 | memcpy(target->d_iname, dentry->d_name.name, |
2339 | dentry->d_name.len + 1); | |
1da177e4 LT |
2340 | dentry->d_name.name = target->d_name.name; |
2341 | target->d_name.name = target->d_iname; | |
2342 | } | |
2343 | } else { | |
2344 | if (dname_external(dentry)) { | |
2345 | /* | |
2346 | * dentry:external, target:internal. Give dentry's | |
2347 | * storage to target and make dentry internal | |
2348 | */ | |
2349 | memcpy(dentry->d_iname, target->d_name.name, | |
2350 | target->d_name.len + 1); | |
2351 | target->d_name.name = dentry->d_name.name; | |
2352 | dentry->d_name.name = dentry->d_iname; | |
2353 | } else { | |
2354 | /* | |
2355 | * Both are internal. Just copy target to dentry | |
2356 | */ | |
2357 | memcpy(dentry->d_iname, target->d_name.name, | |
2358 | target->d_name.len + 1); | |
dc711ca3 AV |
2359 | dentry->d_name.len = target->d_name.len; |
2360 | return; | |
1da177e4 LT |
2361 | } |
2362 | } | |
9a8d5bb4 | 2363 | swap(dentry->d_name.len, target->d_name.len); |
1da177e4 LT |
2364 | } |
2365 | ||
2fd6b7f5 NP |
2366 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2367 | { | |
2368 | /* | |
2369 | * XXXX: do we really need to take target->d_lock? | |
2370 | */ | |
2371 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) | |
2372 | spin_lock(&target->d_parent->d_lock); | |
2373 | else { | |
2374 | if (d_ancestor(dentry->d_parent, target->d_parent)) { | |
2375 | spin_lock(&dentry->d_parent->d_lock); | |
2376 | spin_lock_nested(&target->d_parent->d_lock, | |
2377 | DENTRY_D_LOCK_NESTED); | |
2378 | } else { | |
2379 | spin_lock(&target->d_parent->d_lock); | |
2380 | spin_lock_nested(&dentry->d_parent->d_lock, | |
2381 | DENTRY_D_LOCK_NESTED); | |
2382 | } | |
2383 | } | |
2384 | if (target < dentry) { | |
2385 | spin_lock_nested(&target->d_lock, 2); | |
2386 | spin_lock_nested(&dentry->d_lock, 3); | |
2387 | } else { | |
2388 | spin_lock_nested(&dentry->d_lock, 2); | |
2389 | spin_lock_nested(&target->d_lock, 3); | |
2390 | } | |
2391 | } | |
2392 | ||
2393 | static void dentry_unlock_parents_for_move(struct dentry *dentry, | |
2394 | struct dentry *target) | |
2395 | { | |
2396 | if (target->d_parent != dentry->d_parent) | |
2397 | spin_unlock(&dentry->d_parent->d_lock); | |
2398 | if (target->d_parent != target) | |
2399 | spin_unlock(&target->d_parent->d_lock); | |
2400 | } | |
2401 | ||
1da177e4 | 2402 | /* |
2fd6b7f5 NP |
2403 | * When switching names, the actual string doesn't strictly have to |
2404 | * be preserved in the target - because we're dropping the target | |
2405 | * anyway. As such, we can just do a simple memcpy() to copy over | |
2406 | * the new name before we switch. | |
2407 | * | |
2408 | * Note that we have to be a lot more careful about getting the hash | |
2409 | * switched - we have to switch the hash value properly even if it | |
2410 | * then no longer matches the actual (corrupted) string of the target. | |
2411 | * The hash value has to match the hash queue that the dentry is on.. | |
1da177e4 | 2412 | */ |
9eaef27b | 2413 | /* |
18367501 | 2414 | * __d_move - move a dentry |
1da177e4 LT |
2415 | * @dentry: entry to move |
2416 | * @target: new dentry | |
2417 | * | |
2418 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2419 | * dcache entries should not be moved in this way. Caller must hold |
2420 | * rename_lock, the i_mutex of the source and target directories, | |
2421 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). | |
1da177e4 | 2422 | */ |
18367501 | 2423 | static void __d_move(struct dentry * dentry, struct dentry * target) |
1da177e4 | 2424 | { |
1da177e4 LT |
2425 | if (!dentry->d_inode) |
2426 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
2427 | ||
2fd6b7f5 NP |
2428 | BUG_ON(d_ancestor(dentry, target)); |
2429 | BUG_ON(d_ancestor(target, dentry)); | |
2430 | ||
2fd6b7f5 | 2431 | dentry_lock_for_move(dentry, target); |
1da177e4 | 2432 | |
31e6b01f NP |
2433 | write_seqcount_begin(&dentry->d_seq); |
2434 | write_seqcount_begin(&target->d_seq); | |
2435 | ||
ceb5bdc2 NP |
2436 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2437 | ||
2438 | /* | |
2439 | * Move the dentry to the target hash queue. Don't bother checking | |
2440 | * for the same hash queue because of how unlikely it is. | |
2441 | */ | |
2442 | __d_drop(dentry); | |
789680d1 | 2443 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
1da177e4 LT |
2444 | |
2445 | /* Unhash the target: dput() will then get rid of it */ | |
2446 | __d_drop(target); | |
2447 | ||
5160ee6f ED |
2448 | list_del(&dentry->d_u.d_child); |
2449 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
2450 | |
2451 | /* Switch the names.. */ | |
2452 | switch_names(dentry, target); | |
9a8d5bb4 | 2453 | swap(dentry->d_name.hash, target->d_name.hash); |
1da177e4 LT |
2454 | |
2455 | /* ... and switch the parents */ | |
2456 | if (IS_ROOT(dentry)) { | |
2457 | dentry->d_parent = target->d_parent; | |
2458 | target->d_parent = target; | |
5160ee6f | 2459 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 | 2460 | } else { |
9a8d5bb4 | 2461 | swap(dentry->d_parent, target->d_parent); |
1da177e4 LT |
2462 | |
2463 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 2464 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
2465 | } |
2466 | ||
5160ee6f | 2467 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2fd6b7f5 | 2468 | |
31e6b01f NP |
2469 | write_seqcount_end(&target->d_seq); |
2470 | write_seqcount_end(&dentry->d_seq); | |
2471 | ||
2fd6b7f5 | 2472 | dentry_unlock_parents_for_move(dentry, target); |
1da177e4 | 2473 | spin_unlock(&target->d_lock); |
c32ccd87 | 2474 | fsnotify_d_move(dentry); |
1da177e4 | 2475 | spin_unlock(&dentry->d_lock); |
18367501 AV |
2476 | } |
2477 | ||
2478 | /* | |
2479 | * d_move - move a dentry | |
2480 | * @dentry: entry to move | |
2481 | * @target: new dentry | |
2482 | * | |
2483 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2484 | * dcache entries should not be moved in this way. See the locking |
2485 | * requirements for __d_move. | |
18367501 AV |
2486 | */ |
2487 | void d_move(struct dentry *dentry, struct dentry *target) | |
2488 | { | |
2489 | write_seqlock(&rename_lock); | |
2490 | __d_move(dentry, target); | |
1da177e4 | 2491 | write_sequnlock(&rename_lock); |
9eaef27b | 2492 | } |
ec4f8605 | 2493 | EXPORT_SYMBOL(d_move); |
1da177e4 | 2494 | |
e2761a11 OH |
2495 | /** |
2496 | * d_ancestor - search for an ancestor | |
2497 | * @p1: ancestor dentry | |
2498 | * @p2: child dentry | |
2499 | * | |
2500 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
2501 | * an ancestor of p2, else NULL. | |
9eaef27b | 2502 | */ |
e2761a11 | 2503 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
2504 | { |
2505 | struct dentry *p; | |
2506 | ||
871c0067 | 2507 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 2508 | if (p->d_parent == p1) |
e2761a11 | 2509 | return p; |
9eaef27b | 2510 | } |
e2761a11 | 2511 | return NULL; |
9eaef27b TM |
2512 | } |
2513 | ||
2514 | /* | |
2515 | * This helper attempts to cope with remotely renamed directories | |
2516 | * | |
2517 | * It assumes that the caller is already holding | |
18367501 | 2518 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
9eaef27b TM |
2519 | * |
2520 | * Note: If ever the locking in lock_rename() changes, then please | |
2521 | * remember to update this too... | |
9eaef27b | 2522 | */ |
873feea0 NP |
2523 | static struct dentry *__d_unalias(struct inode *inode, |
2524 | struct dentry *dentry, struct dentry *alias) | |
9eaef27b TM |
2525 | { |
2526 | struct mutex *m1 = NULL, *m2 = NULL; | |
ee3efa91 | 2527 | struct dentry *ret = ERR_PTR(-EBUSY); |
9eaef27b TM |
2528 | |
2529 | /* If alias and dentry share a parent, then no extra locks required */ | |
2530 | if (alias->d_parent == dentry->d_parent) | |
2531 | goto out_unalias; | |
2532 | ||
9eaef27b | 2533 | /* See lock_rename() */ |
9eaef27b TM |
2534 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2535 | goto out_err; | |
2536 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
2537 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
2538 | goto out_err; | |
2539 | m2 = &alias->d_parent->d_inode->i_mutex; | |
2540 | out_unalias: | |
ee3efa91 AV |
2541 | if (likely(!d_mountpoint(alias))) { |
2542 | __d_move(alias, dentry); | |
2543 | ret = alias; | |
2544 | } | |
9eaef27b | 2545 | out_err: |
873feea0 | 2546 | spin_unlock(&inode->i_lock); |
9eaef27b TM |
2547 | if (m2) |
2548 | mutex_unlock(m2); | |
2549 | if (m1) | |
2550 | mutex_unlock(m1); | |
2551 | return ret; | |
2552 | } | |
2553 | ||
770bfad8 DH |
2554 | /* |
2555 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
2556 | * named dentry in place of the dentry to be replaced. | |
2fd6b7f5 | 2557 | * returns with anon->d_lock held! |
770bfad8 DH |
2558 | */ |
2559 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
2560 | { | |
740da42e | 2561 | struct dentry *dparent; |
770bfad8 | 2562 | |
2fd6b7f5 | 2563 | dentry_lock_for_move(anon, dentry); |
770bfad8 | 2564 | |
31e6b01f NP |
2565 | write_seqcount_begin(&dentry->d_seq); |
2566 | write_seqcount_begin(&anon->d_seq); | |
2567 | ||
770bfad8 | 2568 | dparent = dentry->d_parent; |
770bfad8 | 2569 | |
2fd6b7f5 NP |
2570 | switch_names(dentry, anon); |
2571 | swap(dentry->d_name.hash, anon->d_name.hash); | |
2572 | ||
740da42e AV |
2573 | dentry->d_parent = dentry; |
2574 | list_del_init(&dentry->d_u.d_child); | |
2575 | anon->d_parent = dparent; | |
9ed53b12 | 2576 | list_move(&anon->d_u.d_child, &dparent->d_subdirs); |
770bfad8 | 2577 | |
31e6b01f NP |
2578 | write_seqcount_end(&dentry->d_seq); |
2579 | write_seqcount_end(&anon->d_seq); | |
2580 | ||
2fd6b7f5 NP |
2581 | dentry_unlock_parents_for_move(anon, dentry); |
2582 | spin_unlock(&dentry->d_lock); | |
2583 | ||
2584 | /* anon->d_lock still locked, returns locked */ | |
770bfad8 DH |
2585 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
2586 | } | |
2587 | ||
2588 | /** | |
2589 | * d_materialise_unique - introduce an inode into the tree | |
2590 | * @dentry: candidate dentry | |
2591 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
2592 | * | |
2593 | * Introduces an dentry into the tree, substituting an extant disconnected | |
c46c8877 JL |
2594 | * root directory alias in its place if there is one. Caller must hold the |
2595 | * i_mutex of the parent directory. | |
770bfad8 DH |
2596 | */ |
2597 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
2598 | { | |
9eaef27b | 2599 | struct dentry *actual; |
770bfad8 DH |
2600 | |
2601 | BUG_ON(!d_unhashed(dentry)); | |
2602 | ||
770bfad8 DH |
2603 | if (!inode) { |
2604 | actual = dentry; | |
360da900 | 2605 | __d_instantiate(dentry, NULL); |
357f8e65 NP |
2606 | d_rehash(actual); |
2607 | goto out_nolock; | |
770bfad8 DH |
2608 | } |
2609 | ||
873feea0 | 2610 | spin_lock(&inode->i_lock); |
357f8e65 | 2611 | |
9eaef27b TM |
2612 | if (S_ISDIR(inode->i_mode)) { |
2613 | struct dentry *alias; | |
2614 | ||
2615 | /* Does an aliased dentry already exist? */ | |
32ba9c3f | 2616 | alias = __d_find_alias(inode, 0); |
9eaef27b TM |
2617 | if (alias) { |
2618 | actual = alias; | |
18367501 AV |
2619 | write_seqlock(&rename_lock); |
2620 | ||
2621 | if (d_ancestor(alias, dentry)) { | |
2622 | /* Check for loops */ | |
2623 | actual = ERR_PTR(-ELOOP); | |
b18dafc8 | 2624 | spin_unlock(&inode->i_lock); |
18367501 AV |
2625 | } else if (IS_ROOT(alias)) { |
2626 | /* Is this an anonymous mountpoint that we | |
2627 | * could splice into our tree? */ | |
9eaef27b | 2628 | __d_materialise_dentry(dentry, alias); |
18367501 | 2629 | write_sequnlock(&rename_lock); |
9eaef27b TM |
2630 | __d_drop(alias); |
2631 | goto found; | |
18367501 AV |
2632 | } else { |
2633 | /* Nope, but we must(!) avoid directory | |
b18dafc8 | 2634 | * aliasing. This drops inode->i_lock */ |
18367501 | 2635 | actual = __d_unalias(inode, dentry, alias); |
9eaef27b | 2636 | } |
18367501 | 2637 | write_sequnlock(&rename_lock); |
dd179946 DH |
2638 | if (IS_ERR(actual)) { |
2639 | if (PTR_ERR(actual) == -ELOOP) | |
2640 | pr_warn_ratelimited( | |
2641 | "VFS: Lookup of '%s' in %s %s" | |
2642 | " would have caused loop\n", | |
2643 | dentry->d_name.name, | |
2644 | inode->i_sb->s_type->name, | |
2645 | inode->i_sb->s_id); | |
9eaef27b | 2646 | dput(alias); |
dd179946 | 2647 | } |
9eaef27b TM |
2648 | goto out_nolock; |
2649 | } | |
770bfad8 DH |
2650 | } |
2651 | ||
2652 | /* Add a unique reference */ | |
2653 | actual = __d_instantiate_unique(dentry, inode); | |
2654 | if (!actual) | |
2655 | actual = dentry; | |
357f8e65 NP |
2656 | else |
2657 | BUG_ON(!d_unhashed(actual)); | |
770bfad8 | 2658 | |
770bfad8 DH |
2659 | spin_lock(&actual->d_lock); |
2660 | found: | |
2661 | _d_rehash(actual); | |
2662 | spin_unlock(&actual->d_lock); | |
873feea0 | 2663 | spin_unlock(&inode->i_lock); |
9eaef27b | 2664 | out_nolock: |
770bfad8 DH |
2665 | if (actual == dentry) { |
2666 | security_d_instantiate(dentry, inode); | |
2667 | return NULL; | |
2668 | } | |
2669 | ||
2670 | iput(inode); | |
2671 | return actual; | |
770bfad8 | 2672 | } |
ec4f8605 | 2673 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
770bfad8 | 2674 | |
cdd16d02 | 2675 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
2676 | { |
2677 | *buflen -= namelen; | |
2678 | if (*buflen < 0) | |
2679 | return -ENAMETOOLONG; | |
2680 | *buffer -= namelen; | |
2681 | memcpy(*buffer, str, namelen); | |
2682 | return 0; | |
2683 | } | |
2684 | ||
232d2d60 WL |
2685 | /** |
2686 | * prepend_name - prepend a pathname in front of current buffer pointer | |
2687 | * buffer: buffer pointer | |
2688 | * buflen: allocated length of the buffer | |
2689 | * name: name string and length qstr structure | |
2690 | * | |
2691 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to | |
2692 | * make sure that either the old or the new name pointer and length are | |
2693 | * fetched. However, there may be mismatch between length and pointer. | |
2694 | * The length cannot be trusted, we need to copy it byte-by-byte until | |
2695 | * the length is reached or a null byte is found. It also prepends "/" at | |
2696 | * the beginning of the name. The sequence number check at the caller will | |
2697 | * retry it again when a d_move() does happen. So any garbage in the buffer | |
2698 | * due to mismatched pointer and length will be discarded. | |
2699 | */ | |
cdd16d02 MS |
2700 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2701 | { | |
232d2d60 WL |
2702 | const char *dname = ACCESS_ONCE(name->name); |
2703 | u32 dlen = ACCESS_ONCE(name->len); | |
2704 | char *p; | |
2705 | ||
2706 | if (*buflen < dlen + 1) | |
2707 | return -ENAMETOOLONG; | |
2708 | *buflen -= dlen + 1; | |
2709 | p = *buffer -= dlen + 1; | |
2710 | *p++ = '/'; | |
2711 | while (dlen--) { | |
2712 | char c = *dname++; | |
2713 | if (!c) | |
2714 | break; | |
2715 | *p++ = c; | |
2716 | } | |
2717 | return 0; | |
cdd16d02 MS |
2718 | } |
2719 | ||
1da177e4 | 2720 | /** |
208898c1 | 2721 | * prepend_path - Prepend path string to a buffer |
9d1bc601 | 2722 | * @path: the dentry/vfsmount to report |
02125a82 | 2723 | * @root: root vfsmnt/dentry |
f2eb6575 MS |
2724 | * @buffer: pointer to the end of the buffer |
2725 | * @buflen: pointer to buffer length | |
552ce544 | 2726 | * |
232d2d60 WL |
2727 | * The function tries to write out the pathname without taking any lock other |
2728 | * than the RCU read lock to make sure that dentries won't go away. It only | |
2729 | * checks the sequence number of the global rename_lock as any change in the | |
2730 | * dentry's d_seq will be preceded by changes in the rename_lock sequence | |
2731 | * number. If the sequence number had been change, it will restart the whole | |
2732 | * pathname back-tracing sequence again. It performs a total of 3 trials of | |
2733 | * lockless back-tracing sequences before falling back to take the | |
2734 | * rename_lock. | |
1da177e4 | 2735 | */ |
02125a82 AV |
2736 | static int prepend_path(const struct path *path, |
2737 | const struct path *root, | |
f2eb6575 | 2738 | char **buffer, int *buflen) |
1da177e4 | 2739 | { |
9d1bc601 MS |
2740 | struct dentry *dentry = path->dentry; |
2741 | struct vfsmount *vfsmnt = path->mnt; | |
0714a533 | 2742 | struct mount *mnt = real_mount(vfsmnt); |
f2eb6575 | 2743 | int error = 0; |
232d2d60 WL |
2744 | unsigned seq = 0; |
2745 | char *bptr; | |
2746 | int blen; | |
6092d048 | 2747 | |
232d2d60 WL |
2748 | restart: |
2749 | bptr = *buffer; | |
2750 | blen = *buflen; | |
2751 | read_seqbegin_or_lock(&rename_lock, &seq); | |
f2eb6575 | 2752 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
2753 | struct dentry * parent; |
2754 | ||
1da177e4 | 2755 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 2756 | /* Global root? */ |
232d2d60 WL |
2757 | if (mnt_has_parent(mnt)) { |
2758 | dentry = mnt->mnt_mountpoint; | |
2759 | mnt = mnt->mnt_parent; | |
2760 | vfsmnt = &mnt->mnt; | |
2761 | continue; | |
2762 | } | |
2763 | /* | |
2764 | * Filesystems needing to implement special "root names" | |
2765 | * should do so with ->d_dname() | |
2766 | */ | |
2767 | if (IS_ROOT(dentry) && | |
2768 | (dentry->d_name.len != 1 || | |
2769 | dentry->d_name.name[0] != '/')) { | |
2770 | WARN(1, "Root dentry has weird name <%.*s>\n", | |
2771 | (int) dentry->d_name.len, | |
2772 | dentry->d_name.name); | |
2773 | } | |
2774 | if (!error) | |
2775 | error = is_mounted(vfsmnt) ? 1 : 2; | |
2776 | break; | |
1da177e4 LT |
2777 | } |
2778 | parent = dentry->d_parent; | |
2779 | prefetch(parent); | |
232d2d60 | 2780 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
f2eb6575 MS |
2781 | if (error) |
2782 | break; | |
2783 | ||
1da177e4 LT |
2784 | dentry = parent; |
2785 | } | |
232d2d60 WL |
2786 | if (read_seqretry_or_unlock(&rename_lock, &seq)) |
2787 | goto restart; | |
1da177e4 | 2788 | |
232d2d60 WL |
2789 | if (error >= 0 && bptr == *buffer) { |
2790 | if (--blen < 0) | |
2791 | error = -ENAMETOOLONG; | |
2792 | else | |
2793 | *--bptr = '/'; | |
2794 | } | |
2795 | *buffer = bptr; | |
2796 | *buflen = blen; | |
7ea600b5 | 2797 | return error; |
f2eb6575 | 2798 | } |
be285c71 | 2799 | |
f2eb6575 MS |
2800 | /** |
2801 | * __d_path - return the path of a dentry | |
2802 | * @path: the dentry/vfsmount to report | |
02125a82 | 2803 | * @root: root vfsmnt/dentry |
cd956a1c | 2804 | * @buf: buffer to return value in |
f2eb6575 MS |
2805 | * @buflen: buffer length |
2806 | * | |
ffd1f4ed | 2807 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
2808 | * |
2809 | * Returns a pointer into the buffer or an error code if the | |
2810 | * path was too long. | |
2811 | * | |
be148247 | 2812 | * "buflen" should be positive. |
f2eb6575 | 2813 | * |
02125a82 | 2814 | * If the path is not reachable from the supplied root, return %NULL. |
f2eb6575 | 2815 | */ |
02125a82 AV |
2816 | char *__d_path(const struct path *path, |
2817 | const struct path *root, | |
f2eb6575 MS |
2818 | char *buf, int buflen) |
2819 | { | |
2820 | char *res = buf + buflen; | |
2821 | int error; | |
2822 | ||
2823 | prepend(&res, &buflen, "\0", 1); | |
7ea600b5 | 2824 | br_read_lock(&vfsmount_lock); |
f2eb6575 | 2825 | error = prepend_path(path, root, &res, &buflen); |
7ea600b5 | 2826 | br_read_unlock(&vfsmount_lock); |
be148247 | 2827 | |
02125a82 AV |
2828 | if (error < 0) |
2829 | return ERR_PTR(error); | |
2830 | if (error > 0) | |
2831 | return NULL; | |
2832 | return res; | |
2833 | } | |
2834 | ||
2835 | char *d_absolute_path(const struct path *path, | |
2836 | char *buf, int buflen) | |
2837 | { | |
2838 | struct path root = {}; | |
2839 | char *res = buf + buflen; | |
2840 | int error; | |
2841 | ||
2842 | prepend(&res, &buflen, "\0", 1); | |
7ea600b5 | 2843 | br_read_lock(&vfsmount_lock); |
02125a82 | 2844 | error = prepend_path(path, &root, &res, &buflen); |
7ea600b5 | 2845 | br_read_unlock(&vfsmount_lock); |
02125a82 AV |
2846 | |
2847 | if (error > 1) | |
2848 | error = -EINVAL; | |
2849 | if (error < 0) | |
f2eb6575 | 2850 | return ERR_PTR(error); |
f2eb6575 | 2851 | return res; |
1da177e4 LT |
2852 | } |
2853 | ||
ffd1f4ed MS |
2854 | /* |
2855 | * same as __d_path but appends "(deleted)" for unlinked files. | |
2856 | */ | |
02125a82 AV |
2857 | static int path_with_deleted(const struct path *path, |
2858 | const struct path *root, | |
2859 | char **buf, int *buflen) | |
ffd1f4ed MS |
2860 | { |
2861 | prepend(buf, buflen, "\0", 1); | |
2862 | if (d_unlinked(path->dentry)) { | |
2863 | int error = prepend(buf, buflen, " (deleted)", 10); | |
2864 | if (error) | |
2865 | return error; | |
2866 | } | |
2867 | ||
2868 | return prepend_path(path, root, buf, buflen); | |
2869 | } | |
2870 | ||
8df9d1a4 MS |
2871 | static int prepend_unreachable(char **buffer, int *buflen) |
2872 | { | |
2873 | return prepend(buffer, buflen, "(unreachable)", 13); | |
2874 | } | |
2875 | ||
a03a8a70 JB |
2876 | /** |
2877 | * d_path - return the path of a dentry | |
cf28b486 | 2878 | * @path: path to report |
a03a8a70 JB |
2879 | * @buf: buffer to return value in |
2880 | * @buflen: buffer length | |
2881 | * | |
2882 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
2883 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
2884 | * | |
52afeefb AV |
2885 | * Returns a pointer into the buffer or an error code if the path was |
2886 | * too long. Note: Callers should use the returned pointer, not the passed | |
2887 | * in buffer, to use the name! The implementation often starts at an offset | |
2888 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 2889 | * |
31f3e0b3 | 2890 | * "buflen" should be positive. |
a03a8a70 | 2891 | */ |
20d4fdc1 | 2892 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 2893 | { |
ffd1f4ed | 2894 | char *res = buf + buflen; |
6ac08c39 | 2895 | struct path root; |
ffd1f4ed | 2896 | int error; |
1da177e4 | 2897 | |
c23fbb6b ED |
2898 | /* |
2899 | * We have various synthetic filesystems that never get mounted. On | |
2900 | * these filesystems dentries are never used for lookup purposes, and | |
2901 | * thus don't need to be hashed. They also don't need a name until a | |
2902 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
2903 | * below allows us to generate a name for these objects on demand: | |
2904 | */ | |
cf28b486 JB |
2905 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2906 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
c23fbb6b | 2907 | |
f7ad3c6b | 2908 | get_fs_root(current->fs, &root); |
7ea600b5 | 2909 | br_read_lock(&vfsmount_lock); |
02125a82 | 2910 | error = path_with_deleted(path, &root, &res, &buflen); |
7ea600b5 | 2911 | br_read_unlock(&vfsmount_lock); |
02125a82 | 2912 | if (error < 0) |
ffd1f4ed | 2913 | res = ERR_PTR(error); |
6ac08c39 | 2914 | path_put(&root); |
1da177e4 LT |
2915 | return res; |
2916 | } | |
ec4f8605 | 2917 | EXPORT_SYMBOL(d_path); |
1da177e4 | 2918 | |
c23fbb6b ED |
2919 | /* |
2920 | * Helper function for dentry_operations.d_dname() members | |
2921 | */ | |
2922 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
2923 | const char *fmt, ...) | |
2924 | { | |
2925 | va_list args; | |
2926 | char temp[64]; | |
2927 | int sz; | |
2928 | ||
2929 | va_start(args, fmt); | |
2930 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
2931 | va_end(args); | |
2932 | ||
2933 | if (sz > sizeof(temp) || sz > buflen) | |
2934 | return ERR_PTR(-ENAMETOOLONG); | |
2935 | ||
2936 | buffer += buflen - sz; | |
2937 | return memcpy(buffer, temp, sz); | |
2938 | } | |
2939 | ||
118b2302 AV |
2940 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
2941 | { | |
2942 | char *end = buffer + buflen; | |
2943 | /* these dentries are never renamed, so d_lock is not needed */ | |
2944 | if (prepend(&end, &buflen, " (deleted)", 11) || | |
232d2d60 | 2945 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
118b2302 AV |
2946 | prepend(&end, &buflen, "/", 1)) |
2947 | end = ERR_PTR(-ENAMETOOLONG); | |
232d2d60 | 2948 | return end; |
118b2302 AV |
2949 | } |
2950 | ||
6092d048 RP |
2951 | /* |
2952 | * Write full pathname from the root of the filesystem into the buffer. | |
2953 | */ | |
ec2447c2 | 2954 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
6092d048 | 2955 | { |
232d2d60 WL |
2956 | char *end, *retval; |
2957 | int len, seq = 0; | |
2958 | int error = 0; | |
6092d048 | 2959 | |
232d2d60 WL |
2960 | restart: |
2961 | end = buf + buflen; | |
2962 | len = buflen; | |
2963 | prepend(&end, &len, "\0", 1); | |
6092d048 RP |
2964 | if (buflen < 1) |
2965 | goto Elong; | |
2966 | /* Get '/' right */ | |
2967 | retval = end-1; | |
2968 | *retval = '/'; | |
232d2d60 | 2969 | read_seqbegin_or_lock(&rename_lock, &seq); |
cdd16d02 MS |
2970 | while (!IS_ROOT(dentry)) { |
2971 | struct dentry *parent = dentry->d_parent; | |
9abca360 | 2972 | int error; |
6092d048 | 2973 | |
6092d048 | 2974 | prefetch(parent); |
232d2d60 WL |
2975 | error = prepend_name(&end, &len, &dentry->d_name); |
2976 | if (error) | |
2977 | break; | |
6092d048 RP |
2978 | |
2979 | retval = end; | |
2980 | dentry = parent; | |
2981 | } | |
232d2d60 WL |
2982 | if (read_seqretry_or_unlock(&rename_lock, &seq)) |
2983 | goto restart; | |
2984 | if (error) | |
2985 | goto Elong; | |
c103135c AV |
2986 | return retval; |
2987 | Elong: | |
2988 | return ERR_PTR(-ENAMETOOLONG); | |
2989 | } | |
ec2447c2 NP |
2990 | |
2991 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
2992 | { | |
232d2d60 | 2993 | return __dentry_path(dentry, buf, buflen); |
ec2447c2 NP |
2994 | } |
2995 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
2996 | |
2997 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
2998 | { | |
2999 | char *p = NULL; | |
3000 | char *retval; | |
3001 | ||
c103135c AV |
3002 | if (d_unlinked(dentry)) { |
3003 | p = buf + buflen; | |
3004 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
3005 | goto Elong; | |
3006 | buflen++; | |
3007 | } | |
3008 | retval = __dentry_path(dentry, buf, buflen); | |
c103135c AV |
3009 | if (!IS_ERR(retval) && p) |
3010 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
3011 | return retval; |
3012 | Elong: | |
6092d048 RP |
3013 | return ERR_PTR(-ENAMETOOLONG); |
3014 | } | |
3015 | ||
1da177e4 LT |
3016 | /* |
3017 | * NOTE! The user-level library version returns a | |
3018 | * character pointer. The kernel system call just | |
3019 | * returns the length of the buffer filled (which | |
3020 | * includes the ending '\0' character), or a negative | |
3021 | * error value. So libc would do something like | |
3022 | * | |
3023 | * char *getcwd(char * buf, size_t size) | |
3024 | * { | |
3025 | * int retval; | |
3026 | * | |
3027 | * retval = sys_getcwd(buf, size); | |
3028 | * if (retval >= 0) | |
3029 | * return buf; | |
3030 | * errno = -retval; | |
3031 | * return NULL; | |
3032 | * } | |
3033 | */ | |
3cdad428 | 3034 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 3035 | { |
552ce544 | 3036 | int error; |
6ac08c39 | 3037 | struct path pwd, root; |
552ce544 | 3038 | char *page = (char *) __get_free_page(GFP_USER); |
1da177e4 LT |
3039 | |
3040 | if (!page) | |
3041 | return -ENOMEM; | |
3042 | ||
f7ad3c6b | 3043 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
1da177e4 | 3044 | |
552ce544 | 3045 | error = -ENOENT; |
7ea600b5 | 3046 | br_read_lock(&vfsmount_lock); |
f3da392e | 3047 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 3048 | unsigned long len; |
8df9d1a4 MS |
3049 | char *cwd = page + PAGE_SIZE; |
3050 | int buflen = PAGE_SIZE; | |
1da177e4 | 3051 | |
8df9d1a4 | 3052 | prepend(&cwd, &buflen, "\0", 1); |
02125a82 | 3053 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
7ea600b5 | 3054 | br_read_unlock(&vfsmount_lock); |
552ce544 | 3055 | |
02125a82 | 3056 | if (error < 0) |
552ce544 LT |
3057 | goto out; |
3058 | ||
8df9d1a4 | 3059 | /* Unreachable from current root */ |
02125a82 | 3060 | if (error > 0) { |
8df9d1a4 MS |
3061 | error = prepend_unreachable(&cwd, &buflen); |
3062 | if (error) | |
3063 | goto out; | |
3064 | } | |
3065 | ||
552ce544 LT |
3066 | error = -ERANGE; |
3067 | len = PAGE_SIZE + page - cwd; | |
3068 | if (len <= size) { | |
3069 | error = len; | |
3070 | if (copy_to_user(buf, cwd, len)) | |
3071 | error = -EFAULT; | |
3072 | } | |
949854d0 | 3073 | } else { |
7ea600b5 | 3074 | br_read_unlock(&vfsmount_lock); |
949854d0 | 3075 | } |
1da177e4 LT |
3076 | |
3077 | out: | |
6ac08c39 JB |
3078 | path_put(&pwd); |
3079 | path_put(&root); | |
1da177e4 LT |
3080 | free_page((unsigned long) page); |
3081 | return error; | |
3082 | } | |
3083 | ||
3084 | /* | |
3085 | * Test whether new_dentry is a subdirectory of old_dentry. | |
3086 | * | |
3087 | * Trivially implemented using the dcache structure | |
3088 | */ | |
3089 | ||
3090 | /** | |
3091 | * is_subdir - is new dentry a subdirectory of old_dentry | |
3092 | * @new_dentry: new dentry | |
3093 | * @old_dentry: old dentry | |
3094 | * | |
3095 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
3096 | * Returns 0 otherwise. | |
3097 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
3098 | */ | |
3099 | ||
e2761a11 | 3100 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 LT |
3101 | { |
3102 | int result; | |
949854d0 | 3103 | unsigned seq; |
1da177e4 | 3104 | |
e2761a11 OH |
3105 | if (new_dentry == old_dentry) |
3106 | return 1; | |
3107 | ||
e2761a11 | 3108 | do { |
1da177e4 | 3109 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 3110 | seq = read_seqbegin(&rename_lock); |
949854d0 NP |
3111 | /* |
3112 | * Need rcu_readlock to protect against the d_parent trashing | |
3113 | * due to d_move | |
3114 | */ | |
3115 | rcu_read_lock(); | |
e2761a11 | 3116 | if (d_ancestor(old_dentry, new_dentry)) |
1da177e4 | 3117 | result = 1; |
e2761a11 OH |
3118 | else |
3119 | result = 0; | |
949854d0 | 3120 | rcu_read_unlock(); |
1da177e4 | 3121 | } while (read_seqretry(&rename_lock, seq)); |
1da177e4 LT |
3122 | |
3123 | return result; | |
3124 | } | |
3125 | ||
db14fc3a | 3126 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
1da177e4 | 3127 | { |
db14fc3a MS |
3128 | struct dentry *root = data; |
3129 | if (dentry != root) { | |
3130 | if (d_unhashed(dentry) || !dentry->d_inode) | |
3131 | return D_WALK_SKIP; | |
1da177e4 | 3132 | |
01ddc4ed MS |
3133 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
3134 | dentry->d_flags |= DCACHE_GENOCIDE; | |
3135 | dentry->d_lockref.count--; | |
3136 | } | |
1da177e4 | 3137 | } |
db14fc3a MS |
3138 | return D_WALK_CONTINUE; |
3139 | } | |
58db63d0 | 3140 | |
db14fc3a MS |
3141 | void d_genocide(struct dentry *parent) |
3142 | { | |
3143 | d_walk(parent, parent, d_genocide_kill, NULL); | |
1da177e4 LT |
3144 | } |
3145 | ||
60545d0d | 3146 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
1da177e4 | 3147 | { |
60545d0d AV |
3148 | inode_dec_link_count(inode); |
3149 | BUG_ON(dentry->d_name.name != dentry->d_iname || | |
3150 | !hlist_unhashed(&dentry->d_alias) || | |
3151 | !d_unlinked(dentry)); | |
3152 | spin_lock(&dentry->d_parent->d_lock); | |
3153 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
3154 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", | |
3155 | (unsigned long long)inode->i_ino); | |
3156 | spin_unlock(&dentry->d_lock); | |
3157 | spin_unlock(&dentry->d_parent->d_lock); | |
3158 | d_instantiate(dentry, inode); | |
1da177e4 | 3159 | } |
60545d0d | 3160 | EXPORT_SYMBOL(d_tmpfile); |
1da177e4 LT |
3161 | |
3162 | static __initdata unsigned long dhash_entries; | |
3163 | static int __init set_dhash_entries(char *str) | |
3164 | { | |
3165 | if (!str) | |
3166 | return 0; | |
3167 | dhash_entries = simple_strtoul(str, &str, 0); | |
3168 | return 1; | |
3169 | } | |
3170 | __setup("dhash_entries=", set_dhash_entries); | |
3171 | ||
3172 | static void __init dcache_init_early(void) | |
3173 | { | |
074b8517 | 3174 | unsigned int loop; |
1da177e4 LT |
3175 | |
3176 | /* If hashes are distributed across NUMA nodes, defer | |
3177 | * hash allocation until vmalloc space is available. | |
3178 | */ | |
3179 | if (hashdist) | |
3180 | return; | |
3181 | ||
3182 | dentry_hashtable = | |
3183 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3184 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3185 | dhash_entries, |
3186 | 13, | |
3187 | HASH_EARLY, | |
3188 | &d_hash_shift, | |
3189 | &d_hash_mask, | |
31fe62b9 | 3190 | 0, |
1da177e4 LT |
3191 | 0); |
3192 | ||
074b8517 | 3193 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3194 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3195 | } |
3196 | ||
74bf17cf | 3197 | static void __init dcache_init(void) |
1da177e4 | 3198 | { |
074b8517 | 3199 | unsigned int loop; |
1da177e4 LT |
3200 | |
3201 | /* | |
3202 | * A constructor could be added for stable state like the lists, | |
3203 | * but it is probably not worth it because of the cache nature | |
3204 | * of the dcache. | |
3205 | */ | |
0a31bd5f CL |
3206 | dentry_cache = KMEM_CACHE(dentry, |
3207 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 LT |
3208 | |
3209 | /* Hash may have been set up in dcache_init_early */ | |
3210 | if (!hashdist) | |
3211 | return; | |
3212 | ||
3213 | dentry_hashtable = | |
3214 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3215 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3216 | dhash_entries, |
3217 | 13, | |
3218 | 0, | |
3219 | &d_hash_shift, | |
3220 | &d_hash_mask, | |
31fe62b9 | 3221 | 0, |
1da177e4 LT |
3222 | 0); |
3223 | ||
074b8517 | 3224 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3225 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3226 | } |
3227 | ||
3228 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 3229 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 3230 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 3231 | |
1da177e4 LT |
3232 | EXPORT_SYMBOL(d_genocide); |
3233 | ||
1da177e4 LT |
3234 | void __init vfs_caches_init_early(void) |
3235 | { | |
3236 | dcache_init_early(); | |
3237 | inode_init_early(); | |
3238 | } | |
3239 | ||
3240 | void __init vfs_caches_init(unsigned long mempages) | |
3241 | { | |
3242 | unsigned long reserve; | |
3243 | ||
3244 | /* Base hash sizes on available memory, with a reserve equal to | |
3245 | 150% of current kernel size */ | |
3246 | ||
3247 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
3248 | mempages -= reserve; | |
3249 | ||
3250 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 3251 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 3252 | |
74bf17cf DC |
3253 | dcache_init(); |
3254 | inode_init(); | |
1da177e4 | 3255 | files_init(mempages); |
74bf17cf | 3256 | mnt_init(); |
1da177e4 LT |
3257 | bdev_cache_init(); |
3258 | chrdev_init(); | |
3259 | } |