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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> |
f6041567 | 40 | #include <linux/list_lru.h> |
df4c0e36 AR |
41 | #include <linux/kasan.h> |
42 | ||
07f3f05c | 43 | #include "internal.h" |
b2dba1af | 44 | #include "mount.h" |
1da177e4 | 45 | |
789680d1 NP |
46 | /* |
47 | * Usage: | |
873feea0 | 48 | * dcache->d_inode->i_lock protects: |
946e51f2 | 49 | * - i_dentry, d_u.d_alias, d_inode of aliases |
ceb5bdc2 NP |
50 | * dcache_hash_bucket lock protects: |
51 | * - the dcache hash table | |
52 | * s_anon bl list spinlock protects: | |
53 | * - the s_anon list (see __d_drop) | |
19156840 | 54 | * dentry->d_sb->s_dentry_lru_lock protects: |
23044507 NP |
55 | * - the dcache lru lists and counters |
56 | * d_lock protects: | |
57 | * - d_flags | |
58 | * - d_name | |
59 | * - d_lru | |
b7ab39f6 | 60 | * - d_count |
da502956 | 61 | * - d_unhashed() |
2fd6b7f5 NP |
62 | * - d_parent and d_subdirs |
63 | * - childrens' d_child and d_parent | |
946e51f2 | 64 | * - d_u.d_alias, d_inode |
789680d1 NP |
65 | * |
66 | * Ordering: | |
873feea0 | 67 | * dentry->d_inode->i_lock |
b5c84bf6 | 68 | * dentry->d_lock |
19156840 | 69 | * dentry->d_sb->s_dentry_lru_lock |
ceb5bdc2 NP |
70 | * dcache_hash_bucket lock |
71 | * s_anon lock | |
789680d1 | 72 | * |
da502956 NP |
73 | * If there is an ancestor relationship: |
74 | * dentry->d_parent->...->d_parent->d_lock | |
75 | * ... | |
76 | * dentry->d_parent->d_lock | |
77 | * dentry->d_lock | |
78 | * | |
79 | * If no ancestor relationship: | |
789680d1 NP |
80 | * if (dentry1 < dentry2) |
81 | * dentry1->d_lock | |
82 | * dentry2->d_lock | |
83 | */ | |
fa3536cc | 84 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
85 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
86 | ||
74c3cbe3 | 87 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 | 88 | |
949854d0 | 89 | EXPORT_SYMBOL(rename_lock); |
1da177e4 | 90 | |
e18b890b | 91 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 | 92 | |
1da177e4 LT |
93 | /* |
94 | * This is the single most critical data structure when it comes | |
95 | * to the dcache: the hashtable for lookups. Somebody should try | |
96 | * to make this good - I've just made it work. | |
97 | * | |
98 | * This hash-function tries to avoid losing too many bits of hash | |
99 | * information, yet avoid using a prime hash-size or similar. | |
100 | */ | |
1da177e4 | 101 | |
fa3536cc ED |
102 | static unsigned int d_hash_mask __read_mostly; |
103 | static unsigned int d_hash_shift __read_mostly; | |
ceb5bdc2 | 104 | |
b07ad996 | 105 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
ceb5bdc2 | 106 | |
8966be90 | 107 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
6d7d1a0d | 108 | unsigned int hash) |
ceb5bdc2 | 109 | { |
6d7d1a0d | 110 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
99d263d4 | 111 | return dentry_hashtable + hash_32(hash, d_hash_shift); |
ceb5bdc2 NP |
112 | } |
113 | ||
94bdd655 AV |
114 | #define IN_LOOKUP_SHIFT 10 |
115 | static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT]; | |
116 | ||
117 | static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent, | |
118 | unsigned int hash) | |
119 | { | |
120 | hash += (unsigned long) parent / L1_CACHE_BYTES; | |
121 | return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT); | |
122 | } | |
123 | ||
124 | ||
1da177e4 LT |
125 | /* Statistics gathering. */ |
126 | struct dentry_stat_t dentry_stat = { | |
127 | .age_limit = 45, | |
128 | }; | |
129 | ||
3942c07c | 130 | static DEFINE_PER_CPU(long, nr_dentry); |
62d36c77 | 131 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
312d3ca8 CH |
132 | |
133 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
62d36c77 DC |
134 | |
135 | /* | |
136 | * Here we resort to our own counters instead of using generic per-cpu counters | |
137 | * for consistency with what the vfs inode code does. We are expected to harvest | |
138 | * better code and performance by having our own specialized counters. | |
139 | * | |
140 | * Please note that the loop is done over all possible CPUs, not over all online | |
141 | * CPUs. The reason for this is that we don't want to play games with CPUs going | |
142 | * on and off. If one of them goes off, we will just keep their counters. | |
143 | * | |
144 | * glommer: See cffbc8a for details, and if you ever intend to change this, | |
145 | * please update all vfs counters to match. | |
146 | */ | |
3942c07c | 147 | static long get_nr_dentry(void) |
3e880fb5 NP |
148 | { |
149 | int i; | |
3942c07c | 150 | long sum = 0; |
3e880fb5 NP |
151 | for_each_possible_cpu(i) |
152 | sum += per_cpu(nr_dentry, i); | |
153 | return sum < 0 ? 0 : sum; | |
154 | } | |
155 | ||
62d36c77 DC |
156 | static long get_nr_dentry_unused(void) |
157 | { | |
158 | int i; | |
159 | long sum = 0; | |
160 | for_each_possible_cpu(i) | |
161 | sum += per_cpu(nr_dentry_unused, i); | |
162 | return sum < 0 ? 0 : sum; | |
163 | } | |
164 | ||
1f7e0616 | 165 | int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer, |
312d3ca8 CH |
166 | size_t *lenp, loff_t *ppos) |
167 | { | |
3e880fb5 | 168 | dentry_stat.nr_dentry = get_nr_dentry(); |
62d36c77 | 169 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
3942c07c | 170 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
312d3ca8 CH |
171 | } |
172 | #endif | |
173 | ||
5483f18e LT |
174 | /* |
175 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. | |
176 | * The strings are both count bytes long, and count is non-zero. | |
177 | */ | |
e419b4cc LT |
178 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
179 | ||
180 | #include <asm/word-at-a-time.h> | |
181 | /* | |
182 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a | |
183 | * aligned allocation for this particular component. We don't | |
184 | * strictly need the load_unaligned_zeropad() safety, but it | |
185 | * doesn't hurt either. | |
186 | * | |
187 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do | |
188 | * need the careful unaligned handling. | |
189 | */ | |
94753db5 | 190 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
5483f18e | 191 | { |
bfcfaa77 | 192 | unsigned long a,b,mask; |
bfcfaa77 LT |
193 | |
194 | for (;;) { | |
12f8ad4b | 195 | a = *(unsigned long *)cs; |
e419b4cc | 196 | b = load_unaligned_zeropad(ct); |
bfcfaa77 LT |
197 | if (tcount < sizeof(unsigned long)) |
198 | break; | |
199 | if (unlikely(a != b)) | |
200 | return 1; | |
201 | cs += sizeof(unsigned long); | |
202 | ct += sizeof(unsigned long); | |
203 | tcount -= sizeof(unsigned long); | |
204 | if (!tcount) | |
205 | return 0; | |
206 | } | |
a5c21dce | 207 | mask = bytemask_from_count(tcount); |
bfcfaa77 | 208 | return unlikely(!!((a ^ b) & mask)); |
e419b4cc LT |
209 | } |
210 | ||
bfcfaa77 | 211 | #else |
e419b4cc | 212 | |
94753db5 | 213 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
e419b4cc | 214 | { |
5483f18e LT |
215 | do { |
216 | if (*cs != *ct) | |
217 | return 1; | |
218 | cs++; | |
219 | ct++; | |
220 | tcount--; | |
221 | } while (tcount); | |
222 | return 0; | |
223 | } | |
224 | ||
e419b4cc LT |
225 | #endif |
226 | ||
94753db5 LT |
227 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
228 | { | |
6326c71f | 229 | const unsigned char *cs; |
94753db5 LT |
230 | /* |
231 | * Be careful about RCU walk racing with rename: | |
232 | * use ACCESS_ONCE to fetch the name pointer. | |
233 | * | |
234 | * NOTE! Even if a rename will mean that the length | |
235 | * was not loaded atomically, we don't care. The | |
236 | * RCU walk will check the sequence count eventually, | |
237 | * and catch it. And we won't overrun the buffer, | |
238 | * because we're reading the name pointer atomically, | |
239 | * and a dentry name is guaranteed to be properly | |
240 | * terminated with a NUL byte. | |
241 | * | |
242 | * End result: even if 'len' is wrong, we'll exit | |
243 | * early because the data cannot match (there can | |
244 | * be no NUL in the ct/tcount data) | |
245 | */ | |
6326c71f LT |
246 | cs = ACCESS_ONCE(dentry->d_name.name); |
247 | smp_read_barrier_depends(); | |
248 | return dentry_string_cmp(cs, ct, tcount); | |
94753db5 LT |
249 | } |
250 | ||
8d85b484 AV |
251 | struct external_name { |
252 | union { | |
253 | atomic_t count; | |
254 | struct rcu_head head; | |
255 | } u; | |
256 | unsigned char name[]; | |
257 | }; | |
258 | ||
259 | static inline struct external_name *external_name(struct dentry *dentry) | |
260 | { | |
261 | return container_of(dentry->d_name.name, struct external_name, name[0]); | |
262 | } | |
263 | ||
9c82ab9c | 264 | static void __d_free(struct rcu_head *head) |
1da177e4 | 265 | { |
9c82ab9c CH |
266 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
267 | ||
8d85b484 AV |
268 | kmem_cache_free(dentry_cache, dentry); |
269 | } | |
270 | ||
271 | static void __d_free_external(struct rcu_head *head) | |
272 | { | |
273 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); | |
8d85b484 | 274 | kfree(external_name(dentry)); |
1da177e4 LT |
275 | kmem_cache_free(dentry_cache, dentry); |
276 | } | |
277 | ||
810bb172 AV |
278 | static inline int dname_external(const struct dentry *dentry) |
279 | { | |
280 | return dentry->d_name.name != dentry->d_iname; | |
281 | } | |
282 | ||
4bf46a27 DH |
283 | static inline void __d_set_inode_and_type(struct dentry *dentry, |
284 | struct inode *inode, | |
285 | unsigned type_flags) | |
286 | { | |
287 | unsigned flags; | |
288 | ||
289 | dentry->d_inode = inode; | |
4bf46a27 DH |
290 | flags = READ_ONCE(dentry->d_flags); |
291 | flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); | |
292 | flags |= type_flags; | |
293 | WRITE_ONCE(dentry->d_flags, flags); | |
294 | } | |
295 | ||
4bf46a27 DH |
296 | static inline void __d_clear_type_and_inode(struct dentry *dentry) |
297 | { | |
298 | unsigned flags = READ_ONCE(dentry->d_flags); | |
299 | ||
300 | flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); | |
301 | WRITE_ONCE(dentry->d_flags, flags); | |
4bf46a27 DH |
302 | dentry->d_inode = NULL; |
303 | } | |
304 | ||
b4f0354e AV |
305 | static void dentry_free(struct dentry *dentry) |
306 | { | |
946e51f2 | 307 | WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias)); |
8d85b484 AV |
308 | if (unlikely(dname_external(dentry))) { |
309 | struct external_name *p = external_name(dentry); | |
310 | if (likely(atomic_dec_and_test(&p->u.count))) { | |
311 | call_rcu(&dentry->d_u.d_rcu, __d_free_external); | |
312 | return; | |
313 | } | |
314 | } | |
b4f0354e AV |
315 | /* if dentry was never visible to RCU, immediate free is OK */ |
316 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) | |
317 | __d_free(&dentry->d_u.d_rcu); | |
318 | else | |
319 | call_rcu(&dentry->d_u.d_rcu, __d_free); | |
320 | } | |
321 | ||
31e6b01f | 322 | /** |
a7c6f571 | 323 | * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups |
ff5fdb61 | 324 | * @dentry: the target dentry |
31e6b01f NP |
325 | * After this call, in-progress rcu-walk path lookup will fail. This |
326 | * should be called after unhashing, and after changing d_inode (if | |
327 | * the dentry has not already been unhashed). | |
328 | */ | |
a7c6f571 | 329 | static inline void dentry_rcuwalk_invalidate(struct dentry *dentry) |
31e6b01f | 330 | { |
a7c6f571 PZ |
331 | lockdep_assert_held(&dentry->d_lock); |
332 | /* Go through am invalidation barrier */ | |
333 | write_seqcount_invalidate(&dentry->d_seq); | |
31e6b01f NP |
334 | } |
335 | ||
1da177e4 LT |
336 | /* |
337 | * Release the dentry's inode, using the filesystem | |
31e6b01f NP |
338 | * d_iput() operation if defined. Dentry has no refcount |
339 | * and is unhashed. | |
1da177e4 | 340 | */ |
858119e1 | 341 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 | 342 | __releases(dentry->d_lock) |
873feea0 | 343 | __releases(dentry->d_inode->i_lock) |
1da177e4 LT |
344 | { |
345 | struct inode *inode = dentry->d_inode; | |
346 | if (inode) { | |
4bf46a27 | 347 | __d_clear_type_and_inode(dentry); |
946e51f2 | 348 | hlist_del_init(&dentry->d_u.d_alias); |
1da177e4 | 349 | spin_unlock(&dentry->d_lock); |
873feea0 | 350 | spin_unlock(&inode->i_lock); |
f805fbda LT |
351 | if (!inode->i_nlink) |
352 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
353 | if (dentry->d_op && dentry->d_op->d_iput) |
354 | dentry->d_op->d_iput(dentry, inode); | |
355 | else | |
356 | iput(inode); | |
357 | } else { | |
358 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
359 | } |
360 | } | |
361 | ||
31e6b01f NP |
362 | /* |
363 | * Release the dentry's inode, using the filesystem | |
364 | * d_iput() operation if defined. dentry remains in-use. | |
365 | */ | |
366 | static void dentry_unlink_inode(struct dentry * dentry) | |
367 | __releases(dentry->d_lock) | |
873feea0 | 368 | __releases(dentry->d_inode->i_lock) |
31e6b01f NP |
369 | { |
370 | struct inode *inode = dentry->d_inode; | |
a528aca7 AV |
371 | |
372 | raw_write_seqcount_begin(&dentry->d_seq); | |
4bf46a27 | 373 | __d_clear_type_and_inode(dentry); |
946e51f2 | 374 | hlist_del_init(&dentry->d_u.d_alias); |
a528aca7 | 375 | raw_write_seqcount_end(&dentry->d_seq); |
31e6b01f | 376 | spin_unlock(&dentry->d_lock); |
873feea0 | 377 | spin_unlock(&inode->i_lock); |
31e6b01f NP |
378 | if (!inode->i_nlink) |
379 | fsnotify_inoderemove(inode); | |
380 | if (dentry->d_op && dentry->d_op->d_iput) | |
381 | dentry->d_op->d_iput(dentry, inode); | |
382 | else | |
383 | iput(inode); | |
384 | } | |
385 | ||
89dc77bc LT |
386 | /* |
387 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry | |
388 | * is in use - which includes both the "real" per-superblock | |
389 | * LRU list _and_ the DCACHE_SHRINK_LIST use. | |
390 | * | |
391 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is | |
392 | * on the shrink list (ie not on the superblock LRU list). | |
393 | * | |
394 | * The per-cpu "nr_dentry_unused" counters are updated with | |
395 | * the DCACHE_LRU_LIST bit. | |
396 | * | |
397 | * These helper functions make sure we always follow the | |
398 | * rules. d_lock must be held by the caller. | |
399 | */ | |
400 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) | |
401 | static void d_lru_add(struct dentry *dentry) | |
402 | { | |
403 | D_FLAG_VERIFY(dentry, 0); | |
404 | dentry->d_flags |= DCACHE_LRU_LIST; | |
405 | this_cpu_inc(nr_dentry_unused); | |
406 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
407 | } | |
408 | ||
409 | static void d_lru_del(struct dentry *dentry) | |
410 | { | |
411 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
412 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
413 | this_cpu_dec(nr_dentry_unused); | |
414 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
415 | } | |
416 | ||
417 | static void d_shrink_del(struct dentry *dentry) | |
418 | { | |
419 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
420 | list_del_init(&dentry->d_lru); | |
421 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
422 | this_cpu_dec(nr_dentry_unused); | |
423 | } | |
424 | ||
425 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) | |
426 | { | |
427 | D_FLAG_VERIFY(dentry, 0); | |
428 | list_add(&dentry->d_lru, list); | |
429 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; | |
430 | this_cpu_inc(nr_dentry_unused); | |
431 | } | |
432 | ||
433 | /* | |
434 | * These can only be called under the global LRU lock, ie during the | |
435 | * callback for freeing the LRU list. "isolate" removes it from the | |
436 | * LRU lists entirely, while shrink_move moves it to the indicated | |
437 | * private list. | |
438 | */ | |
3f97b163 | 439 | static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry) |
89dc77bc LT |
440 | { |
441 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
442 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
443 | this_cpu_dec(nr_dentry_unused); | |
3f97b163 | 444 | list_lru_isolate(lru, &dentry->d_lru); |
89dc77bc LT |
445 | } |
446 | ||
3f97b163 VD |
447 | static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry, |
448 | struct list_head *list) | |
89dc77bc LT |
449 | { |
450 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
451 | dentry->d_flags |= DCACHE_SHRINK_LIST; | |
3f97b163 | 452 | list_lru_isolate_move(lru, &dentry->d_lru, list); |
89dc77bc LT |
453 | } |
454 | ||
da3bbdd4 | 455 | /* |
f6041567 | 456 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
da3bbdd4 KM |
457 | */ |
458 | static void dentry_lru_add(struct dentry *dentry) | |
459 | { | |
89dc77bc LT |
460 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
461 | d_lru_add(dentry); | |
da3bbdd4 KM |
462 | } |
463 | ||
789680d1 NP |
464 | /** |
465 | * d_drop - drop a dentry | |
466 | * @dentry: dentry to drop | |
467 | * | |
468 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
469 | * be found through a VFS lookup any more. Note that this is different from | |
470 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
471 | * possible, giving a successful _negative_ lookup, while d_drop will | |
472 | * just make the cache lookup fail. | |
473 | * | |
474 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
475 | * reason (NFS timeouts or autofs deletes). | |
476 | * | |
477 | * __d_drop requires dentry->d_lock. | |
478 | */ | |
479 | void __d_drop(struct dentry *dentry) | |
480 | { | |
dea3667b | 481 | if (!d_unhashed(dentry)) { |
b61625d2 | 482 | struct hlist_bl_head *b; |
7632e465 BF |
483 | /* |
484 | * Hashed dentries are normally on the dentry hashtable, | |
485 | * with the exception of those newly allocated by | |
486 | * d_obtain_alias, which are always IS_ROOT: | |
487 | */ | |
488 | if (unlikely(IS_ROOT(dentry))) | |
b61625d2 AV |
489 | b = &dentry->d_sb->s_anon; |
490 | else | |
491 | b = d_hash(dentry->d_parent, dentry->d_name.hash); | |
492 | ||
493 | hlist_bl_lock(b); | |
494 | __hlist_bl_del(&dentry->d_hash); | |
495 | dentry->d_hash.pprev = NULL; | |
496 | hlist_bl_unlock(b); | |
a7c6f571 | 497 | dentry_rcuwalk_invalidate(dentry); |
789680d1 NP |
498 | } |
499 | } | |
500 | EXPORT_SYMBOL(__d_drop); | |
501 | ||
502 | void d_drop(struct dentry *dentry) | |
503 | { | |
789680d1 NP |
504 | spin_lock(&dentry->d_lock); |
505 | __d_drop(dentry); | |
506 | spin_unlock(&dentry->d_lock); | |
789680d1 NP |
507 | } |
508 | EXPORT_SYMBOL(d_drop); | |
509 | ||
ba65dc5e AV |
510 | static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) |
511 | { | |
512 | struct dentry *next; | |
513 | /* | |
514 | * Inform d_walk() and shrink_dentry_list() that we are no longer | |
515 | * attached to the dentry tree | |
516 | */ | |
517 | dentry->d_flags |= DCACHE_DENTRY_KILLED; | |
518 | if (unlikely(list_empty(&dentry->d_child))) | |
519 | return; | |
520 | __list_del_entry(&dentry->d_child); | |
521 | /* | |
522 | * Cursors can move around the list of children. While we'd been | |
523 | * a normal list member, it didn't matter - ->d_child.next would've | |
524 | * been updated. However, from now on it won't be and for the | |
525 | * things like d_walk() it might end up with a nasty surprise. | |
526 | * Normally d_walk() doesn't care about cursors moving around - | |
527 | * ->d_lock on parent prevents that and since a cursor has no children | |
528 | * of its own, we get through it without ever unlocking the parent. | |
529 | * There is one exception, though - if we ascend from a child that | |
530 | * gets killed as soon as we unlock it, the next sibling is found | |
531 | * using the value left in its ->d_child.next. And if _that_ | |
532 | * pointed to a cursor, and cursor got moved (e.g. by lseek()) | |
533 | * before d_walk() regains parent->d_lock, we'll end up skipping | |
534 | * everything the cursor had been moved past. | |
535 | * | |
536 | * Solution: make sure that the pointer left behind in ->d_child.next | |
537 | * points to something that won't be moving around. I.e. skip the | |
538 | * cursors. | |
539 | */ | |
540 | while (dentry->d_child.next != &parent->d_subdirs) { | |
541 | next = list_entry(dentry->d_child.next, struct dentry, d_child); | |
542 | if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR))) | |
543 | break; | |
544 | dentry->d_child.next = next->d_child.next; | |
545 | } | |
546 | } | |
547 | ||
e55fd011 | 548 | static void __dentry_kill(struct dentry *dentry) |
77812a1e | 549 | { |
41edf278 AV |
550 | struct dentry *parent = NULL; |
551 | bool can_free = true; | |
41edf278 | 552 | if (!IS_ROOT(dentry)) |
77812a1e | 553 | parent = dentry->d_parent; |
31e6b01f | 554 | |
0d98439e LT |
555 | /* |
556 | * The dentry is now unrecoverably dead to the world. | |
557 | */ | |
558 | lockref_mark_dead(&dentry->d_lockref); | |
559 | ||
f0023bc6 | 560 | /* |
f0023bc6 SW |
561 | * inform the fs via d_prune that this dentry is about to be |
562 | * unhashed and destroyed. | |
563 | */ | |
29266201 | 564 | if (dentry->d_flags & DCACHE_OP_PRUNE) |
61572bb1 YZ |
565 | dentry->d_op->d_prune(dentry); |
566 | ||
01b60351 AV |
567 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
568 | if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) | |
569 | d_lru_del(dentry); | |
01b60351 | 570 | } |
77812a1e NP |
571 | /* if it was on the hash then remove it */ |
572 | __d_drop(dentry); | |
ba65dc5e | 573 | dentry_unlist(dentry, parent); |
03b3b889 AV |
574 | if (parent) |
575 | spin_unlock(&parent->d_lock); | |
576 | dentry_iput(dentry); | |
577 | /* | |
578 | * dentry_iput drops the locks, at which point nobody (except | |
579 | * transient RCU lookups) can reach this dentry. | |
580 | */ | |
360f5479 | 581 | BUG_ON(dentry->d_lockref.count > 0); |
03b3b889 AV |
582 | this_cpu_dec(nr_dentry); |
583 | if (dentry->d_op && dentry->d_op->d_release) | |
584 | dentry->d_op->d_release(dentry); | |
585 | ||
41edf278 AV |
586 | spin_lock(&dentry->d_lock); |
587 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { | |
588 | dentry->d_flags |= DCACHE_MAY_FREE; | |
589 | can_free = false; | |
590 | } | |
591 | spin_unlock(&dentry->d_lock); | |
41edf278 AV |
592 | if (likely(can_free)) |
593 | dentry_free(dentry); | |
e55fd011 AV |
594 | } |
595 | ||
596 | /* | |
597 | * Finish off a dentry we've decided to kill. | |
598 | * dentry->d_lock must be held, returns with it unlocked. | |
599 | * If ref is non-zero, then decrement the refcount too. | |
600 | * Returns dentry requiring refcount drop, or NULL if we're done. | |
601 | */ | |
8cbf74da | 602 | static struct dentry *dentry_kill(struct dentry *dentry) |
e55fd011 AV |
603 | __releases(dentry->d_lock) |
604 | { | |
605 | struct inode *inode = dentry->d_inode; | |
606 | struct dentry *parent = NULL; | |
607 | ||
608 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) | |
609 | goto failed; | |
610 | ||
611 | if (!IS_ROOT(dentry)) { | |
612 | parent = dentry->d_parent; | |
613 | if (unlikely(!spin_trylock(&parent->d_lock))) { | |
614 | if (inode) | |
615 | spin_unlock(&inode->i_lock); | |
616 | goto failed; | |
617 | } | |
618 | } | |
619 | ||
620 | __dentry_kill(dentry); | |
03b3b889 | 621 | return parent; |
e55fd011 AV |
622 | |
623 | failed: | |
8cbf74da AV |
624 | spin_unlock(&dentry->d_lock); |
625 | cpu_relax(); | |
e55fd011 | 626 | return dentry; /* try again with same dentry */ |
77812a1e NP |
627 | } |
628 | ||
046b961b AV |
629 | static inline struct dentry *lock_parent(struct dentry *dentry) |
630 | { | |
631 | struct dentry *parent = dentry->d_parent; | |
632 | if (IS_ROOT(dentry)) | |
633 | return NULL; | |
360f5479 | 634 | if (unlikely(dentry->d_lockref.count < 0)) |
c2338f2d | 635 | return NULL; |
046b961b AV |
636 | if (likely(spin_trylock(&parent->d_lock))) |
637 | return parent; | |
046b961b | 638 | rcu_read_lock(); |
c2338f2d | 639 | spin_unlock(&dentry->d_lock); |
046b961b AV |
640 | again: |
641 | parent = ACCESS_ONCE(dentry->d_parent); | |
642 | spin_lock(&parent->d_lock); | |
643 | /* | |
644 | * We can't blindly lock dentry until we are sure | |
645 | * that we won't violate the locking order. | |
646 | * Any changes of dentry->d_parent must have | |
647 | * been done with parent->d_lock held, so | |
648 | * spin_lock() above is enough of a barrier | |
649 | * for checking if it's still our child. | |
650 | */ | |
651 | if (unlikely(parent != dentry->d_parent)) { | |
652 | spin_unlock(&parent->d_lock); | |
653 | goto again; | |
654 | } | |
655 | rcu_read_unlock(); | |
656 | if (parent != dentry) | |
9f12600f | 657 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
046b961b AV |
658 | else |
659 | parent = NULL; | |
660 | return parent; | |
661 | } | |
662 | ||
360f5479 LT |
663 | /* |
664 | * Try to do a lockless dput(), and return whether that was successful. | |
665 | * | |
666 | * If unsuccessful, we return false, having already taken the dentry lock. | |
667 | * | |
668 | * The caller needs to hold the RCU read lock, so that the dentry is | |
669 | * guaranteed to stay around even if the refcount goes down to zero! | |
670 | */ | |
671 | static inline bool fast_dput(struct dentry *dentry) | |
672 | { | |
673 | int ret; | |
674 | unsigned int d_flags; | |
675 | ||
676 | /* | |
677 | * If we have a d_op->d_delete() operation, we sould not | |
75a6f82a | 678 | * let the dentry count go to zero, so use "put_or_lock". |
360f5479 LT |
679 | */ |
680 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) | |
681 | return lockref_put_or_lock(&dentry->d_lockref); | |
682 | ||
683 | /* | |
684 | * .. otherwise, we can try to just decrement the | |
685 | * lockref optimistically. | |
686 | */ | |
687 | ret = lockref_put_return(&dentry->d_lockref); | |
688 | ||
689 | /* | |
690 | * If the lockref_put_return() failed due to the lock being held | |
691 | * by somebody else, the fast path has failed. We will need to | |
692 | * get the lock, and then check the count again. | |
693 | */ | |
694 | if (unlikely(ret < 0)) { | |
695 | spin_lock(&dentry->d_lock); | |
696 | if (dentry->d_lockref.count > 1) { | |
697 | dentry->d_lockref.count--; | |
698 | spin_unlock(&dentry->d_lock); | |
699 | return 1; | |
700 | } | |
701 | return 0; | |
702 | } | |
703 | ||
704 | /* | |
705 | * If we weren't the last ref, we're done. | |
706 | */ | |
707 | if (ret) | |
708 | return 1; | |
709 | ||
710 | /* | |
711 | * Careful, careful. The reference count went down | |
712 | * to zero, but we don't hold the dentry lock, so | |
713 | * somebody else could get it again, and do another | |
714 | * dput(), and we need to not race with that. | |
715 | * | |
716 | * However, there is a very special and common case | |
717 | * where we don't care, because there is nothing to | |
718 | * do: the dentry is still hashed, it does not have | |
719 | * a 'delete' op, and it's referenced and already on | |
720 | * the LRU list. | |
721 | * | |
722 | * NOTE! Since we aren't locked, these values are | |
723 | * not "stable". However, it is sufficient that at | |
724 | * some point after we dropped the reference the | |
725 | * dentry was hashed and the flags had the proper | |
726 | * value. Other dentry users may have re-gotten | |
727 | * a reference to the dentry and change that, but | |
728 | * our work is done - we can leave the dentry | |
729 | * around with a zero refcount. | |
730 | */ | |
731 | smp_rmb(); | |
732 | d_flags = ACCESS_ONCE(dentry->d_flags); | |
75a6f82a | 733 | d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED; |
360f5479 LT |
734 | |
735 | /* Nothing to do? Dropping the reference was all we needed? */ | |
736 | if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry)) | |
737 | return 1; | |
738 | ||
739 | /* | |
740 | * Not the fast normal case? Get the lock. We've already decremented | |
741 | * the refcount, but we'll need to re-check the situation after | |
742 | * getting the lock. | |
743 | */ | |
744 | spin_lock(&dentry->d_lock); | |
745 | ||
746 | /* | |
747 | * Did somebody else grab a reference to it in the meantime, and | |
748 | * we're no longer the last user after all? Alternatively, somebody | |
749 | * else could have killed it and marked it dead. Either way, we | |
750 | * don't need to do anything else. | |
751 | */ | |
752 | if (dentry->d_lockref.count) { | |
753 | spin_unlock(&dentry->d_lock); | |
754 | return 1; | |
755 | } | |
756 | ||
757 | /* | |
758 | * Re-get the reference we optimistically dropped. We hold the | |
759 | * lock, and we just tested that it was zero, so we can just | |
760 | * set it to 1. | |
761 | */ | |
762 | dentry->d_lockref.count = 1; | |
763 | return 0; | |
764 | } | |
765 | ||
766 | ||
1da177e4 LT |
767 | /* |
768 | * This is dput | |
769 | * | |
770 | * This is complicated by the fact that we do not want to put | |
771 | * dentries that are no longer on any hash chain on the unused | |
772 | * list: we'd much rather just get rid of them immediately. | |
773 | * | |
774 | * However, that implies that we have to traverse the dentry | |
775 | * tree upwards to the parents which might _also_ now be | |
776 | * scheduled for deletion (it may have been only waiting for | |
777 | * its last child to go away). | |
778 | * | |
779 | * This tail recursion is done by hand as we don't want to depend | |
780 | * on the compiler to always get this right (gcc generally doesn't). | |
781 | * Real recursion would eat up our stack space. | |
782 | */ | |
783 | ||
784 | /* | |
785 | * dput - release a dentry | |
786 | * @dentry: dentry to release | |
787 | * | |
788 | * Release a dentry. This will drop the usage count and if appropriate | |
789 | * call the dentry unlink method as well as removing it from the queues and | |
790 | * releasing its resources. If the parent dentries were scheduled for release | |
791 | * they too may now get deleted. | |
1da177e4 | 792 | */ |
1da177e4 LT |
793 | void dput(struct dentry *dentry) |
794 | { | |
8aab6a27 | 795 | if (unlikely(!dentry)) |
1da177e4 LT |
796 | return; |
797 | ||
798 | repeat: | |
360f5479 LT |
799 | rcu_read_lock(); |
800 | if (likely(fast_dput(dentry))) { | |
801 | rcu_read_unlock(); | |
1da177e4 | 802 | return; |
360f5479 LT |
803 | } |
804 | ||
805 | /* Slow case: now with the dentry lock held */ | |
806 | rcu_read_unlock(); | |
1da177e4 | 807 | |
85c7f810 AV |
808 | WARN_ON(d_in_lookup(dentry)); |
809 | ||
8aab6a27 LT |
810 | /* Unreachable? Get rid of it */ |
811 | if (unlikely(d_unhashed(dentry))) | |
812 | goto kill_it; | |
813 | ||
75a6f82a AV |
814 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) |
815 | goto kill_it; | |
816 | ||
8aab6a27 | 817 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { |
1da177e4 | 818 | if (dentry->d_op->d_delete(dentry)) |
61f3dee4 | 819 | goto kill_it; |
1da177e4 | 820 | } |
265ac902 | 821 | |
358eec18 LT |
822 | if (!(dentry->d_flags & DCACHE_REFERENCED)) |
823 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 824 | dentry_lru_add(dentry); |
265ac902 | 825 | |
98474236 | 826 | dentry->d_lockref.count--; |
61f3dee4 | 827 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
828 | return; |
829 | ||
d52b9086 | 830 | kill_it: |
8cbf74da | 831 | dentry = dentry_kill(dentry); |
d52b9086 MS |
832 | if (dentry) |
833 | goto repeat; | |
1da177e4 | 834 | } |
ec4f8605 | 835 | EXPORT_SYMBOL(dput); |
1da177e4 | 836 | |
1da177e4 | 837 | |
b5c84bf6 | 838 | /* This must be called with d_lock held */ |
dc0474be | 839 | static inline void __dget_dlock(struct dentry *dentry) |
23044507 | 840 | { |
98474236 | 841 | dentry->d_lockref.count++; |
23044507 NP |
842 | } |
843 | ||
dc0474be | 844 | static inline void __dget(struct dentry *dentry) |
1da177e4 | 845 | { |
98474236 | 846 | lockref_get(&dentry->d_lockref); |
1da177e4 LT |
847 | } |
848 | ||
b7ab39f6 NP |
849 | struct dentry *dget_parent(struct dentry *dentry) |
850 | { | |
df3d0bbc | 851 | int gotref; |
b7ab39f6 NP |
852 | struct dentry *ret; |
853 | ||
df3d0bbc WL |
854 | /* |
855 | * Do optimistic parent lookup without any | |
856 | * locking. | |
857 | */ | |
858 | rcu_read_lock(); | |
859 | ret = ACCESS_ONCE(dentry->d_parent); | |
860 | gotref = lockref_get_not_zero(&ret->d_lockref); | |
861 | rcu_read_unlock(); | |
862 | if (likely(gotref)) { | |
863 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) | |
864 | return ret; | |
865 | dput(ret); | |
866 | } | |
867 | ||
b7ab39f6 | 868 | repeat: |
a734eb45 NP |
869 | /* |
870 | * Don't need rcu_dereference because we re-check it was correct under | |
871 | * the lock. | |
872 | */ | |
873 | rcu_read_lock(); | |
b7ab39f6 | 874 | ret = dentry->d_parent; |
a734eb45 NP |
875 | spin_lock(&ret->d_lock); |
876 | if (unlikely(ret != dentry->d_parent)) { | |
877 | spin_unlock(&ret->d_lock); | |
878 | rcu_read_unlock(); | |
b7ab39f6 NP |
879 | goto repeat; |
880 | } | |
a734eb45 | 881 | rcu_read_unlock(); |
98474236 WL |
882 | BUG_ON(!ret->d_lockref.count); |
883 | ret->d_lockref.count++; | |
b7ab39f6 | 884 | spin_unlock(&ret->d_lock); |
b7ab39f6 NP |
885 | return ret; |
886 | } | |
887 | EXPORT_SYMBOL(dget_parent); | |
888 | ||
1da177e4 LT |
889 | /** |
890 | * d_find_alias - grab a hashed alias of inode | |
891 | * @inode: inode in question | |
1da177e4 LT |
892 | * |
893 | * If inode has a hashed alias, or is a directory and has any alias, | |
894 | * acquire the reference to alias and return it. Otherwise return NULL. | |
895 | * Notice that if inode is a directory there can be only one alias and | |
896 | * it can be unhashed only if it has no children, or if it is the root | |
3ccb354d EB |
897 | * of a filesystem, or if the directory was renamed and d_revalidate |
898 | * was the first vfs operation to notice. | |
1da177e4 | 899 | * |
21c0d8fd | 900 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
52ed46f0 | 901 | * any other hashed alias over that one. |
1da177e4 | 902 | */ |
52ed46f0 | 903 | static struct dentry *__d_find_alias(struct inode *inode) |
1da177e4 | 904 | { |
da502956 | 905 | struct dentry *alias, *discon_alias; |
1da177e4 | 906 | |
da502956 NP |
907 | again: |
908 | discon_alias = NULL; | |
946e51f2 | 909 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
da502956 | 910 | spin_lock(&alias->d_lock); |
1da177e4 | 911 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
21c0d8fd | 912 | if (IS_ROOT(alias) && |
da502956 | 913 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
1da177e4 | 914 | discon_alias = alias; |
52ed46f0 | 915 | } else { |
dc0474be | 916 | __dget_dlock(alias); |
da502956 NP |
917 | spin_unlock(&alias->d_lock); |
918 | return alias; | |
919 | } | |
920 | } | |
921 | spin_unlock(&alias->d_lock); | |
922 | } | |
923 | if (discon_alias) { | |
924 | alias = discon_alias; | |
925 | spin_lock(&alias->d_lock); | |
926 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
8d80d7da BF |
927 | __dget_dlock(alias); |
928 | spin_unlock(&alias->d_lock); | |
929 | return alias; | |
1da177e4 | 930 | } |
da502956 NP |
931 | spin_unlock(&alias->d_lock); |
932 | goto again; | |
1da177e4 | 933 | } |
da502956 | 934 | return NULL; |
1da177e4 LT |
935 | } |
936 | ||
da502956 | 937 | struct dentry *d_find_alias(struct inode *inode) |
1da177e4 | 938 | { |
214fda1f DH |
939 | struct dentry *de = NULL; |
940 | ||
b3d9b7a3 | 941 | if (!hlist_empty(&inode->i_dentry)) { |
873feea0 | 942 | spin_lock(&inode->i_lock); |
52ed46f0 | 943 | de = __d_find_alias(inode); |
873feea0 | 944 | spin_unlock(&inode->i_lock); |
214fda1f | 945 | } |
1da177e4 LT |
946 | return de; |
947 | } | |
ec4f8605 | 948 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
949 | |
950 | /* | |
951 | * Try to kill dentries associated with this inode. | |
952 | * WARNING: you must own a reference to inode. | |
953 | */ | |
954 | void d_prune_aliases(struct inode *inode) | |
955 | { | |
0cdca3f9 | 956 | struct dentry *dentry; |
1da177e4 | 957 | restart: |
873feea0 | 958 | spin_lock(&inode->i_lock); |
946e51f2 | 959 | hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
1da177e4 | 960 | spin_lock(&dentry->d_lock); |
98474236 | 961 | if (!dentry->d_lockref.count) { |
29355c39 AV |
962 | struct dentry *parent = lock_parent(dentry); |
963 | if (likely(!dentry->d_lockref.count)) { | |
964 | __dentry_kill(dentry); | |
4a7795d3 | 965 | dput(parent); |
29355c39 AV |
966 | goto restart; |
967 | } | |
968 | if (parent) | |
969 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
970 | } |
971 | spin_unlock(&dentry->d_lock); | |
972 | } | |
873feea0 | 973 | spin_unlock(&inode->i_lock); |
1da177e4 | 974 | } |
ec4f8605 | 975 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 | 976 | |
3049cfe2 | 977 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 978 | { |
5c47e6d0 | 979 | struct dentry *dentry, *parent; |
da3bbdd4 | 980 | |
60942f2f | 981 | while (!list_empty(list)) { |
ff2fde99 | 982 | struct inode *inode; |
60942f2f | 983 | dentry = list_entry(list->prev, struct dentry, d_lru); |
ec33679d | 984 | spin_lock(&dentry->d_lock); |
046b961b AV |
985 | parent = lock_parent(dentry); |
986 | ||
dd1f6b2e DC |
987 | /* |
988 | * The dispose list is isolated and dentries are not accounted | |
989 | * to the LRU here, so we can simply remove it from the list | |
990 | * here regardless of whether it is referenced or not. | |
991 | */ | |
89dc77bc | 992 | d_shrink_del(dentry); |
dd1f6b2e | 993 | |
1da177e4 LT |
994 | /* |
995 | * We found an inuse dentry which was not removed from | |
dd1f6b2e | 996 | * the LRU because of laziness during lookup. Do not free it. |
1da177e4 | 997 | */ |
360f5479 | 998 | if (dentry->d_lockref.count > 0) { |
da3bbdd4 | 999 | spin_unlock(&dentry->d_lock); |
046b961b AV |
1000 | if (parent) |
1001 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
1002 | continue; |
1003 | } | |
77812a1e | 1004 | |
64fd72e0 AV |
1005 | |
1006 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) { | |
1007 | bool can_free = dentry->d_flags & DCACHE_MAY_FREE; | |
1008 | spin_unlock(&dentry->d_lock); | |
046b961b AV |
1009 | if (parent) |
1010 | spin_unlock(&parent->d_lock); | |
64fd72e0 AV |
1011 | if (can_free) |
1012 | dentry_free(dentry); | |
1013 | continue; | |
1014 | } | |
1015 | ||
ff2fde99 AV |
1016 | inode = dentry->d_inode; |
1017 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) { | |
89dc77bc | 1018 | d_shrink_add(dentry, list); |
dd1f6b2e | 1019 | spin_unlock(&dentry->d_lock); |
046b961b AV |
1020 | if (parent) |
1021 | spin_unlock(&parent->d_lock); | |
5c47e6d0 | 1022 | continue; |
dd1f6b2e | 1023 | } |
ff2fde99 | 1024 | |
ff2fde99 | 1025 | __dentry_kill(dentry); |
046b961b | 1026 | |
5c47e6d0 AV |
1027 | /* |
1028 | * We need to prune ancestors too. This is necessary to prevent | |
1029 | * quadratic behavior of shrink_dcache_parent(), but is also | |
1030 | * expected to be beneficial in reducing dentry cache | |
1031 | * fragmentation. | |
1032 | */ | |
1033 | dentry = parent; | |
b2b80195 AV |
1034 | while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { |
1035 | parent = lock_parent(dentry); | |
1036 | if (dentry->d_lockref.count != 1) { | |
1037 | dentry->d_lockref.count--; | |
1038 | spin_unlock(&dentry->d_lock); | |
1039 | if (parent) | |
1040 | spin_unlock(&parent->d_lock); | |
1041 | break; | |
1042 | } | |
1043 | inode = dentry->d_inode; /* can't be NULL */ | |
1044 | if (unlikely(!spin_trylock(&inode->i_lock))) { | |
1045 | spin_unlock(&dentry->d_lock); | |
1046 | if (parent) | |
1047 | spin_unlock(&parent->d_lock); | |
1048 | cpu_relax(); | |
1049 | continue; | |
1050 | } | |
1051 | __dentry_kill(dentry); | |
1052 | dentry = parent; | |
1053 | } | |
da3bbdd4 | 1054 | } |
3049cfe2 CH |
1055 | } |
1056 | ||
3f97b163 VD |
1057 | static enum lru_status dentry_lru_isolate(struct list_head *item, |
1058 | struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) | |
f6041567 DC |
1059 | { |
1060 | struct list_head *freeable = arg; | |
1061 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
1062 | ||
1063 | ||
1064 | /* | |
1065 | * we are inverting the lru lock/dentry->d_lock here, | |
1066 | * so use a trylock. If we fail to get the lock, just skip | |
1067 | * it | |
1068 | */ | |
1069 | if (!spin_trylock(&dentry->d_lock)) | |
1070 | return LRU_SKIP; | |
1071 | ||
1072 | /* | |
1073 | * Referenced dentries are still in use. If they have active | |
1074 | * counts, just remove them from the LRU. Otherwise give them | |
1075 | * another pass through the LRU. | |
1076 | */ | |
1077 | if (dentry->d_lockref.count) { | |
3f97b163 | 1078 | d_lru_isolate(lru, dentry); |
f6041567 DC |
1079 | spin_unlock(&dentry->d_lock); |
1080 | return LRU_REMOVED; | |
1081 | } | |
1082 | ||
1083 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
1084 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
1085 | spin_unlock(&dentry->d_lock); | |
1086 | ||
1087 | /* | |
1088 | * The list move itself will be made by the common LRU code. At | |
1089 | * this point, we've dropped the dentry->d_lock but keep the | |
1090 | * lru lock. This is safe to do, since every list movement is | |
1091 | * protected by the lru lock even if both locks are held. | |
1092 | * | |
1093 | * This is guaranteed by the fact that all LRU management | |
1094 | * functions are intermediated by the LRU API calls like | |
1095 | * list_lru_add and list_lru_del. List movement in this file | |
1096 | * only ever occur through this functions or through callbacks | |
1097 | * like this one, that are called from the LRU API. | |
1098 | * | |
1099 | * The only exceptions to this are functions like | |
1100 | * shrink_dentry_list, and code that first checks for the | |
1101 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be | |
1102 | * operating only with stack provided lists after they are | |
1103 | * properly isolated from the main list. It is thus, always a | |
1104 | * local access. | |
1105 | */ | |
1106 | return LRU_ROTATE; | |
1107 | } | |
1108 | ||
3f97b163 | 1109 | d_lru_shrink_move(lru, dentry, freeable); |
f6041567 DC |
1110 | spin_unlock(&dentry->d_lock); |
1111 | ||
1112 | return LRU_REMOVED; | |
1113 | } | |
1114 | ||
3049cfe2 | 1115 | /** |
b48f03b3 DC |
1116 | * prune_dcache_sb - shrink the dcache |
1117 | * @sb: superblock | |
503c358c | 1118 | * @sc: shrink control, passed to list_lru_shrink_walk() |
b48f03b3 | 1119 | * |
503c358c VD |
1120 | * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This |
1121 | * is done when we need more memory and called from the superblock shrinker | |
b48f03b3 | 1122 | * function. |
3049cfe2 | 1123 | * |
b48f03b3 DC |
1124 | * This function may fail to free any resources if all the dentries are in |
1125 | * use. | |
3049cfe2 | 1126 | */ |
503c358c | 1127 | long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc) |
3049cfe2 | 1128 | { |
f6041567 DC |
1129 | LIST_HEAD(dispose); |
1130 | long freed; | |
3049cfe2 | 1131 | |
503c358c VD |
1132 | freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc, |
1133 | dentry_lru_isolate, &dispose); | |
f6041567 | 1134 | shrink_dentry_list(&dispose); |
0a234c6d | 1135 | return freed; |
da3bbdd4 | 1136 | } |
23044507 | 1137 | |
4e717f5c | 1138 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
3f97b163 | 1139 | struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) |
dd1f6b2e | 1140 | { |
4e717f5c GC |
1141 | struct list_head *freeable = arg; |
1142 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
dd1f6b2e | 1143 | |
4e717f5c GC |
1144 | /* |
1145 | * we are inverting the lru lock/dentry->d_lock here, | |
1146 | * so use a trylock. If we fail to get the lock, just skip | |
1147 | * it | |
1148 | */ | |
1149 | if (!spin_trylock(&dentry->d_lock)) | |
1150 | return LRU_SKIP; | |
1151 | ||
3f97b163 | 1152 | d_lru_shrink_move(lru, dentry, freeable); |
4e717f5c | 1153 | spin_unlock(&dentry->d_lock); |
ec33679d | 1154 | |
4e717f5c | 1155 | return LRU_REMOVED; |
da3bbdd4 KM |
1156 | } |
1157 | ||
4e717f5c | 1158 | |
1da177e4 LT |
1159 | /** |
1160 | * shrink_dcache_sb - shrink dcache for a superblock | |
1161 | * @sb: superblock | |
1162 | * | |
3049cfe2 CH |
1163 | * Shrink the dcache for the specified super block. This is used to free |
1164 | * the dcache before unmounting a file system. | |
1da177e4 | 1165 | */ |
3049cfe2 | 1166 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 1167 | { |
4e717f5c GC |
1168 | long freed; |
1169 | ||
1170 | do { | |
1171 | LIST_HEAD(dispose); | |
1172 | ||
1173 | freed = list_lru_walk(&sb->s_dentry_lru, | |
1174 | dentry_lru_isolate_shrink, &dispose, UINT_MAX); | |
3049cfe2 | 1175 | |
4e717f5c GC |
1176 | this_cpu_sub(nr_dentry_unused, freed); |
1177 | shrink_dentry_list(&dispose); | |
1178 | } while (freed > 0); | |
1da177e4 | 1179 | } |
ec4f8605 | 1180 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 1181 | |
db14fc3a MS |
1182 | /** |
1183 | * enum d_walk_ret - action to talke during tree walk | |
1184 | * @D_WALK_CONTINUE: contrinue walk | |
1185 | * @D_WALK_QUIT: quit walk | |
1186 | * @D_WALK_NORETRY: quit when retry is needed | |
1187 | * @D_WALK_SKIP: skip this dentry and its children | |
1188 | */ | |
1189 | enum d_walk_ret { | |
1190 | D_WALK_CONTINUE, | |
1191 | D_WALK_QUIT, | |
1192 | D_WALK_NORETRY, | |
1193 | D_WALK_SKIP, | |
1194 | }; | |
c826cb7d | 1195 | |
1da177e4 | 1196 | /** |
db14fc3a MS |
1197 | * d_walk - walk the dentry tree |
1198 | * @parent: start of walk | |
1199 | * @data: data passed to @enter() and @finish() | |
1200 | * @enter: callback when first entering the dentry | |
1201 | * @finish: callback when successfully finished the walk | |
1da177e4 | 1202 | * |
db14fc3a | 1203 | * The @enter() and @finish() callbacks are called with d_lock held. |
1da177e4 | 1204 | */ |
db14fc3a MS |
1205 | static void d_walk(struct dentry *parent, void *data, |
1206 | enum d_walk_ret (*enter)(void *, struct dentry *), | |
1207 | void (*finish)(void *)) | |
1da177e4 | 1208 | { |
949854d0 | 1209 | struct dentry *this_parent; |
1da177e4 | 1210 | struct list_head *next; |
48f5ec21 | 1211 | unsigned seq = 0; |
db14fc3a MS |
1212 | enum d_walk_ret ret; |
1213 | bool retry = true; | |
949854d0 | 1214 | |
58db63d0 | 1215 | again: |
48f5ec21 | 1216 | read_seqbegin_or_lock(&rename_lock, &seq); |
58db63d0 | 1217 | this_parent = parent; |
2fd6b7f5 | 1218 | spin_lock(&this_parent->d_lock); |
db14fc3a MS |
1219 | |
1220 | ret = enter(data, this_parent); | |
1221 | switch (ret) { | |
1222 | case D_WALK_CONTINUE: | |
1223 | break; | |
1224 | case D_WALK_QUIT: | |
1225 | case D_WALK_SKIP: | |
1226 | goto out_unlock; | |
1227 | case D_WALK_NORETRY: | |
1228 | retry = false; | |
1229 | break; | |
1230 | } | |
1da177e4 LT |
1231 | repeat: |
1232 | next = this_parent->d_subdirs.next; | |
1233 | resume: | |
1234 | while (next != &this_parent->d_subdirs) { | |
1235 | struct list_head *tmp = next; | |
946e51f2 | 1236 | struct dentry *dentry = list_entry(tmp, struct dentry, d_child); |
1da177e4 | 1237 | next = tmp->next; |
2fd6b7f5 | 1238 | |
ba65dc5e AV |
1239 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR)) |
1240 | continue; | |
1241 | ||
2fd6b7f5 | 1242 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
db14fc3a MS |
1243 | |
1244 | ret = enter(data, dentry); | |
1245 | switch (ret) { | |
1246 | case D_WALK_CONTINUE: | |
1247 | break; | |
1248 | case D_WALK_QUIT: | |
2fd6b7f5 | 1249 | spin_unlock(&dentry->d_lock); |
db14fc3a MS |
1250 | goto out_unlock; |
1251 | case D_WALK_NORETRY: | |
1252 | retry = false; | |
1253 | break; | |
1254 | case D_WALK_SKIP: | |
1255 | spin_unlock(&dentry->d_lock); | |
1256 | continue; | |
2fd6b7f5 | 1257 | } |
db14fc3a | 1258 | |
1da177e4 | 1259 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
1260 | spin_unlock(&this_parent->d_lock); |
1261 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1262 | this_parent = dentry; |
2fd6b7f5 | 1263 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1264 | goto repeat; |
1265 | } | |
2fd6b7f5 | 1266 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
1267 | } |
1268 | /* | |
1269 | * All done at this level ... ascend and resume the search. | |
1270 | */ | |
ca5358ef AV |
1271 | rcu_read_lock(); |
1272 | ascend: | |
1da177e4 | 1273 | if (this_parent != parent) { |
c826cb7d | 1274 | struct dentry *child = this_parent; |
31dec132 AV |
1275 | this_parent = child->d_parent; |
1276 | ||
31dec132 AV |
1277 | spin_unlock(&child->d_lock); |
1278 | spin_lock(&this_parent->d_lock); | |
1279 | ||
ca5358ef AV |
1280 | /* might go back up the wrong parent if we have had a rename. */ |
1281 | if (need_seqretry(&rename_lock, seq)) | |
949854d0 | 1282 | goto rename_retry; |
2159184e AV |
1283 | /* go into the first sibling still alive */ |
1284 | do { | |
1285 | next = child->d_child.next; | |
ca5358ef AV |
1286 | if (next == &this_parent->d_subdirs) |
1287 | goto ascend; | |
1288 | child = list_entry(next, struct dentry, d_child); | |
2159184e | 1289 | } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); |
31dec132 | 1290 | rcu_read_unlock(); |
1da177e4 LT |
1291 | goto resume; |
1292 | } | |
ca5358ef | 1293 | if (need_seqretry(&rename_lock, seq)) |
949854d0 | 1294 | goto rename_retry; |
ca5358ef | 1295 | rcu_read_unlock(); |
db14fc3a MS |
1296 | if (finish) |
1297 | finish(data); | |
1298 | ||
1299 | out_unlock: | |
1300 | spin_unlock(&this_parent->d_lock); | |
48f5ec21 | 1301 | done_seqretry(&rename_lock, seq); |
db14fc3a | 1302 | return; |
58db63d0 NP |
1303 | |
1304 | rename_retry: | |
ca5358ef AV |
1305 | spin_unlock(&this_parent->d_lock); |
1306 | rcu_read_unlock(); | |
1307 | BUG_ON(seq & 1); | |
db14fc3a MS |
1308 | if (!retry) |
1309 | return; | |
48f5ec21 | 1310 | seq = 1; |
58db63d0 | 1311 | goto again; |
1da177e4 | 1312 | } |
db14fc3a MS |
1313 | |
1314 | /* | |
1315 | * Search for at least 1 mount point in the dentry's subdirs. | |
1316 | * We descend to the next level whenever the d_subdirs | |
1317 | * list is non-empty and continue searching. | |
1318 | */ | |
1319 | ||
db14fc3a MS |
1320 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
1321 | { | |
1322 | int *ret = data; | |
1323 | if (d_mountpoint(dentry)) { | |
1324 | *ret = 1; | |
1325 | return D_WALK_QUIT; | |
1326 | } | |
1327 | return D_WALK_CONTINUE; | |
1328 | } | |
1329 | ||
69c88dc7 RD |
1330 | /** |
1331 | * have_submounts - check for mounts over a dentry | |
1332 | * @parent: dentry to check. | |
1333 | * | |
1334 | * Return true if the parent or its subdirectories contain | |
1335 | * a mount point | |
1336 | */ | |
db14fc3a MS |
1337 | int have_submounts(struct dentry *parent) |
1338 | { | |
1339 | int ret = 0; | |
1340 | ||
1341 | d_walk(parent, &ret, check_mount, NULL); | |
1342 | ||
1343 | return ret; | |
1344 | } | |
ec4f8605 | 1345 | EXPORT_SYMBOL(have_submounts); |
1da177e4 | 1346 | |
eed81007 MS |
1347 | /* |
1348 | * Called by mount code to set a mountpoint and check if the mountpoint is | |
1349 | * reachable (e.g. NFS can unhash a directory dentry and then the complete | |
1350 | * subtree can become unreachable). | |
1351 | * | |
1ffe46d1 | 1352 | * Only one of d_invalidate() and d_set_mounted() must succeed. For |
eed81007 MS |
1353 | * this reason take rename_lock and d_lock on dentry and ancestors. |
1354 | */ | |
1355 | int d_set_mounted(struct dentry *dentry) | |
1356 | { | |
1357 | struct dentry *p; | |
1358 | int ret = -ENOENT; | |
1359 | write_seqlock(&rename_lock); | |
1360 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { | |
1ffe46d1 | 1361 | /* Need exclusion wrt. d_invalidate() */ |
eed81007 MS |
1362 | spin_lock(&p->d_lock); |
1363 | if (unlikely(d_unhashed(p))) { | |
1364 | spin_unlock(&p->d_lock); | |
1365 | goto out; | |
1366 | } | |
1367 | spin_unlock(&p->d_lock); | |
1368 | } | |
1369 | spin_lock(&dentry->d_lock); | |
1370 | if (!d_unlinked(dentry)) { | |
1371 | dentry->d_flags |= DCACHE_MOUNTED; | |
1372 | ret = 0; | |
1373 | } | |
1374 | spin_unlock(&dentry->d_lock); | |
1375 | out: | |
1376 | write_sequnlock(&rename_lock); | |
1377 | return ret; | |
1378 | } | |
1379 | ||
1da177e4 | 1380 | /* |
fd517909 | 1381 | * Search the dentry child list of the specified parent, |
1da177e4 LT |
1382 | * and move any unused dentries to the end of the unused |
1383 | * list for prune_dcache(). We descend to the next level | |
1384 | * whenever the d_subdirs list is non-empty and continue | |
1385 | * searching. | |
1386 | * | |
1387 | * It returns zero iff there are no unused children, | |
1388 | * otherwise it returns the number of children moved to | |
1389 | * the end of the unused list. This may not be the total | |
1390 | * number of unused children, because select_parent can | |
1391 | * drop the lock and return early due to latency | |
1392 | * constraints. | |
1393 | */ | |
1da177e4 | 1394 | |
db14fc3a MS |
1395 | struct select_data { |
1396 | struct dentry *start; | |
1397 | struct list_head dispose; | |
1398 | int found; | |
1399 | }; | |
23044507 | 1400 | |
db14fc3a MS |
1401 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
1402 | { | |
1403 | struct select_data *data = _data; | |
1404 | enum d_walk_ret ret = D_WALK_CONTINUE; | |
1da177e4 | 1405 | |
db14fc3a MS |
1406 | if (data->start == dentry) |
1407 | goto out; | |
2fd6b7f5 | 1408 | |
fe91522a | 1409 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
db14fc3a | 1410 | data->found++; |
fe91522a AV |
1411 | } else { |
1412 | if (dentry->d_flags & DCACHE_LRU_LIST) | |
1413 | d_lru_del(dentry); | |
1414 | if (!dentry->d_lockref.count) { | |
1415 | d_shrink_add(dentry, &data->dispose); | |
1416 | data->found++; | |
1417 | } | |
1da177e4 | 1418 | } |
db14fc3a MS |
1419 | /* |
1420 | * We can return to the caller if we have found some (this | |
1421 | * ensures forward progress). We'll be coming back to find | |
1422 | * the rest. | |
1423 | */ | |
fe91522a AV |
1424 | if (!list_empty(&data->dispose)) |
1425 | ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; | |
1da177e4 | 1426 | out: |
db14fc3a | 1427 | return ret; |
1da177e4 LT |
1428 | } |
1429 | ||
1430 | /** | |
1431 | * shrink_dcache_parent - prune dcache | |
1432 | * @parent: parent of entries to prune | |
1433 | * | |
1434 | * Prune the dcache to remove unused children of the parent dentry. | |
1435 | */ | |
db14fc3a | 1436 | void shrink_dcache_parent(struct dentry *parent) |
1da177e4 | 1437 | { |
db14fc3a MS |
1438 | for (;;) { |
1439 | struct select_data data; | |
1da177e4 | 1440 | |
db14fc3a MS |
1441 | INIT_LIST_HEAD(&data.dispose); |
1442 | data.start = parent; | |
1443 | data.found = 0; | |
1444 | ||
1445 | d_walk(parent, &data, select_collect, NULL); | |
1446 | if (!data.found) | |
1447 | break; | |
1448 | ||
1449 | shrink_dentry_list(&data.dispose); | |
421348f1 GT |
1450 | cond_resched(); |
1451 | } | |
1da177e4 | 1452 | } |
ec4f8605 | 1453 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1454 | |
9c8c10e2 | 1455 | static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) |
42c32608 | 1456 | { |
9c8c10e2 AV |
1457 | /* it has busy descendents; complain about those instead */ |
1458 | if (!list_empty(&dentry->d_subdirs)) | |
1459 | return D_WALK_CONTINUE; | |
42c32608 | 1460 | |
9c8c10e2 AV |
1461 | /* root with refcount 1 is fine */ |
1462 | if (dentry == _data && dentry->d_lockref.count == 1) | |
1463 | return D_WALK_CONTINUE; | |
1464 | ||
1465 | printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} " | |
1466 | " still in use (%d) [unmount of %s %s]\n", | |
42c32608 AV |
1467 | dentry, |
1468 | dentry->d_inode ? | |
1469 | dentry->d_inode->i_ino : 0UL, | |
9c8c10e2 | 1470 | dentry, |
42c32608 AV |
1471 | dentry->d_lockref.count, |
1472 | dentry->d_sb->s_type->name, | |
1473 | dentry->d_sb->s_id); | |
9c8c10e2 AV |
1474 | WARN_ON(1); |
1475 | return D_WALK_CONTINUE; | |
1476 | } | |
1477 | ||
1478 | static void do_one_tree(struct dentry *dentry) | |
1479 | { | |
1480 | shrink_dcache_parent(dentry); | |
1481 | d_walk(dentry, dentry, umount_check, NULL); | |
1482 | d_drop(dentry); | |
1483 | dput(dentry); | |
42c32608 AV |
1484 | } |
1485 | ||
1486 | /* | |
1487 | * destroy the dentries attached to a superblock on unmounting | |
1488 | */ | |
1489 | void shrink_dcache_for_umount(struct super_block *sb) | |
1490 | { | |
1491 | struct dentry *dentry; | |
1492 | ||
9c8c10e2 | 1493 | WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked"); |
42c32608 AV |
1494 | |
1495 | dentry = sb->s_root; | |
1496 | sb->s_root = NULL; | |
9c8c10e2 | 1497 | do_one_tree(dentry); |
42c32608 AV |
1498 | |
1499 | while (!hlist_bl_empty(&sb->s_anon)) { | |
9c8c10e2 AV |
1500 | dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash)); |
1501 | do_one_tree(dentry); | |
42c32608 AV |
1502 | } |
1503 | } | |
1504 | ||
8ed936b5 EB |
1505 | struct detach_data { |
1506 | struct select_data select; | |
1507 | struct dentry *mountpoint; | |
1508 | }; | |
1509 | static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry) | |
848ac114 | 1510 | { |
8ed936b5 | 1511 | struct detach_data *data = _data; |
848ac114 MS |
1512 | |
1513 | if (d_mountpoint(dentry)) { | |
8ed936b5 EB |
1514 | __dget_dlock(dentry); |
1515 | data->mountpoint = dentry; | |
848ac114 MS |
1516 | return D_WALK_QUIT; |
1517 | } | |
1518 | ||
8ed936b5 | 1519 | return select_collect(&data->select, dentry); |
848ac114 MS |
1520 | } |
1521 | ||
1522 | static void check_and_drop(void *_data) | |
1523 | { | |
8ed936b5 | 1524 | struct detach_data *data = _data; |
848ac114 | 1525 | |
8ed936b5 EB |
1526 | if (!data->mountpoint && !data->select.found) |
1527 | __d_drop(data->select.start); | |
848ac114 MS |
1528 | } |
1529 | ||
1530 | /** | |
1ffe46d1 EB |
1531 | * d_invalidate - detach submounts, prune dcache, and drop |
1532 | * @dentry: dentry to invalidate (aka detach, prune and drop) | |
1533 | * | |
1ffe46d1 | 1534 | * no dcache lock. |
848ac114 | 1535 | * |
8ed936b5 EB |
1536 | * The final d_drop is done as an atomic operation relative to |
1537 | * rename_lock ensuring there are no races with d_set_mounted. This | |
1538 | * ensures there are no unhashed dentries on the path to a mountpoint. | |
848ac114 | 1539 | */ |
5542aa2f | 1540 | void d_invalidate(struct dentry *dentry) |
848ac114 | 1541 | { |
1ffe46d1 EB |
1542 | /* |
1543 | * If it's already been dropped, return OK. | |
1544 | */ | |
1545 | spin_lock(&dentry->d_lock); | |
1546 | if (d_unhashed(dentry)) { | |
1547 | spin_unlock(&dentry->d_lock); | |
5542aa2f | 1548 | return; |
1ffe46d1 EB |
1549 | } |
1550 | spin_unlock(&dentry->d_lock); | |
1551 | ||
848ac114 MS |
1552 | /* Negative dentries can be dropped without further checks */ |
1553 | if (!dentry->d_inode) { | |
1554 | d_drop(dentry); | |
5542aa2f | 1555 | return; |
848ac114 MS |
1556 | } |
1557 | ||
1558 | for (;;) { | |
8ed936b5 | 1559 | struct detach_data data; |
848ac114 | 1560 | |
8ed936b5 EB |
1561 | data.mountpoint = NULL; |
1562 | INIT_LIST_HEAD(&data.select.dispose); | |
1563 | data.select.start = dentry; | |
1564 | data.select.found = 0; | |
1565 | ||
1566 | d_walk(dentry, &data, detach_and_collect, check_and_drop); | |
848ac114 | 1567 | |
8ed936b5 EB |
1568 | if (data.select.found) |
1569 | shrink_dentry_list(&data.select.dispose); | |
848ac114 | 1570 | |
8ed936b5 EB |
1571 | if (data.mountpoint) { |
1572 | detach_mounts(data.mountpoint); | |
1573 | dput(data.mountpoint); | |
1574 | } | |
848ac114 | 1575 | |
8ed936b5 | 1576 | if (!data.mountpoint && !data.select.found) |
848ac114 MS |
1577 | break; |
1578 | ||
1579 | cond_resched(); | |
1580 | } | |
848ac114 | 1581 | } |
1ffe46d1 | 1582 | EXPORT_SYMBOL(d_invalidate); |
848ac114 | 1583 | |
1da177e4 | 1584 | /** |
a4464dbc AV |
1585 | * __d_alloc - allocate a dcache entry |
1586 | * @sb: filesystem it will belong to | |
1da177e4 LT |
1587 | * @name: qstr of the name |
1588 | * | |
1589 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1590 | * available. On a success the dentry is returned. The name passed in is | |
1591 | * copied and the copy passed in may be reused after this call. | |
1592 | */ | |
1593 | ||
a4464dbc | 1594 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1da177e4 LT |
1595 | { |
1596 | struct dentry *dentry; | |
1597 | char *dname; | |
1598 | ||
e12ba74d | 1599 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1600 | if (!dentry) |
1601 | return NULL; | |
1602 | ||
6326c71f LT |
1603 | /* |
1604 | * We guarantee that the inline name is always NUL-terminated. | |
1605 | * This way the memcpy() done by the name switching in rename | |
1606 | * will still always have a NUL at the end, even if we might | |
1607 | * be overwriting an internal NUL character | |
1608 | */ | |
1609 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; | |
798434bd AV |
1610 | if (unlikely(!name)) { |
1611 | static const struct qstr anon = QSTR_INIT("/", 1); | |
1612 | name = &anon; | |
1613 | dname = dentry->d_iname; | |
1614 | } else if (name->len > DNAME_INLINE_LEN-1) { | |
8d85b484 | 1615 | size_t size = offsetof(struct external_name, name[1]); |
5d097056 VD |
1616 | struct external_name *p = kmalloc(size + name->len, |
1617 | GFP_KERNEL_ACCOUNT); | |
8d85b484 | 1618 | if (!p) { |
1da177e4 LT |
1619 | kmem_cache_free(dentry_cache, dentry); |
1620 | return NULL; | |
1621 | } | |
8d85b484 AV |
1622 | atomic_set(&p->u.count, 1); |
1623 | dname = p->name; | |
df4c0e36 AR |
1624 | if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS)) |
1625 | kasan_unpoison_shadow(dname, | |
1626 | round_up(name->len + 1, sizeof(unsigned long))); | |
1da177e4 LT |
1627 | } else { |
1628 | dname = dentry->d_iname; | |
1629 | } | |
1da177e4 LT |
1630 | |
1631 | dentry->d_name.len = name->len; | |
1632 | dentry->d_name.hash = name->hash; | |
1633 | memcpy(dname, name->name, name->len); | |
1634 | dname[name->len] = 0; | |
1635 | ||
6326c71f LT |
1636 | /* Make sure we always see the terminating NUL character */ |
1637 | smp_wmb(); | |
1638 | dentry->d_name.name = dname; | |
1639 | ||
98474236 | 1640 | dentry->d_lockref.count = 1; |
dea3667b | 1641 | dentry->d_flags = 0; |
1da177e4 | 1642 | spin_lock_init(&dentry->d_lock); |
31e6b01f | 1643 | seqcount_init(&dentry->d_seq); |
1da177e4 | 1644 | dentry->d_inode = NULL; |
a4464dbc AV |
1645 | dentry->d_parent = dentry; |
1646 | dentry->d_sb = sb; | |
1da177e4 LT |
1647 | dentry->d_op = NULL; |
1648 | dentry->d_fsdata = NULL; | |
ceb5bdc2 | 1649 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1da177e4 LT |
1650 | INIT_LIST_HEAD(&dentry->d_lru); |
1651 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
946e51f2 AV |
1652 | INIT_HLIST_NODE(&dentry->d_u.d_alias); |
1653 | INIT_LIST_HEAD(&dentry->d_child); | |
a4464dbc | 1654 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1da177e4 | 1655 | |
3e880fb5 | 1656 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1657 | |
1da177e4 LT |
1658 | return dentry; |
1659 | } | |
a4464dbc AV |
1660 | |
1661 | /** | |
1662 | * d_alloc - allocate a dcache entry | |
1663 | * @parent: parent of entry to allocate | |
1664 | * @name: qstr of the name | |
1665 | * | |
1666 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1667 | * available. On a success the dentry is returned. The name passed in is | |
1668 | * copied and the copy passed in may be reused after this call. | |
1669 | */ | |
1670 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1671 | { | |
1672 | struct dentry *dentry = __d_alloc(parent->d_sb, name); | |
1673 | if (!dentry) | |
1674 | return NULL; | |
3d56c25e | 1675 | dentry->d_flags |= DCACHE_RCUACCESS; |
a4464dbc AV |
1676 | spin_lock(&parent->d_lock); |
1677 | /* | |
1678 | * don't need child lock because it is not subject | |
1679 | * to concurrency here | |
1680 | */ | |
1681 | __dget_dlock(parent); | |
1682 | dentry->d_parent = parent; | |
946e51f2 | 1683 | list_add(&dentry->d_child, &parent->d_subdirs); |
a4464dbc AV |
1684 | spin_unlock(&parent->d_lock); |
1685 | ||
1686 | return dentry; | |
1687 | } | |
ec4f8605 | 1688 | EXPORT_SYMBOL(d_alloc); |
1da177e4 | 1689 | |
ba65dc5e AV |
1690 | struct dentry *d_alloc_cursor(struct dentry * parent) |
1691 | { | |
1692 | struct dentry *dentry = __d_alloc(parent->d_sb, NULL); | |
1693 | if (dentry) { | |
1694 | dentry->d_flags |= DCACHE_RCUACCESS | DCACHE_DENTRY_CURSOR; | |
1695 | dentry->d_parent = dget(parent); | |
1696 | } | |
1697 | return dentry; | |
1698 | } | |
1699 | ||
e1a24bb0 BF |
1700 | /** |
1701 | * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) | |
1702 | * @sb: the superblock | |
1703 | * @name: qstr of the name | |
1704 | * | |
1705 | * For a filesystem that just pins its dentries in memory and never | |
1706 | * performs lookups at all, return an unhashed IS_ROOT dentry. | |
1707 | */ | |
4b936885 NP |
1708 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1709 | { | |
e1a24bb0 | 1710 | return __d_alloc(sb, name); |
4b936885 NP |
1711 | } |
1712 | EXPORT_SYMBOL(d_alloc_pseudo); | |
1713 | ||
1da177e4 LT |
1714 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1715 | { | |
1716 | struct qstr q; | |
1717 | ||
1718 | q.name = name; | |
fcfd2fbf | 1719 | q.hash_len = hashlen_string(name); |
1da177e4 LT |
1720 | return d_alloc(parent, &q); |
1721 | } | |
ef26ca97 | 1722 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1723 | |
fb045adb NP |
1724 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1725 | { | |
6f7f7caa LT |
1726 | WARN_ON_ONCE(dentry->d_op); |
1727 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | | |
fb045adb NP |
1728 | DCACHE_OP_COMPARE | |
1729 | DCACHE_OP_REVALIDATE | | |
ecf3d1f1 | 1730 | DCACHE_OP_WEAK_REVALIDATE | |
4bacc9c9 | 1731 | DCACHE_OP_DELETE | |
d101a125 MS |
1732 | DCACHE_OP_SELECT_INODE | |
1733 | DCACHE_OP_REAL)); | |
fb045adb NP |
1734 | dentry->d_op = op; |
1735 | if (!op) | |
1736 | return; | |
1737 | if (op->d_hash) | |
1738 | dentry->d_flags |= DCACHE_OP_HASH; | |
1739 | if (op->d_compare) | |
1740 | dentry->d_flags |= DCACHE_OP_COMPARE; | |
1741 | if (op->d_revalidate) | |
1742 | dentry->d_flags |= DCACHE_OP_REVALIDATE; | |
ecf3d1f1 JL |
1743 | if (op->d_weak_revalidate) |
1744 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; | |
fb045adb NP |
1745 | if (op->d_delete) |
1746 | dentry->d_flags |= DCACHE_OP_DELETE; | |
f0023bc6 SW |
1747 | if (op->d_prune) |
1748 | dentry->d_flags |= DCACHE_OP_PRUNE; | |
4bacc9c9 DH |
1749 | if (op->d_select_inode) |
1750 | dentry->d_flags |= DCACHE_OP_SELECT_INODE; | |
d101a125 MS |
1751 | if (op->d_real) |
1752 | dentry->d_flags |= DCACHE_OP_REAL; | |
fb045adb NP |
1753 | |
1754 | } | |
1755 | EXPORT_SYMBOL(d_set_d_op); | |
1756 | ||
df1a085a DH |
1757 | |
1758 | /* | |
1759 | * d_set_fallthru - Mark a dentry as falling through to a lower layer | |
1760 | * @dentry - The dentry to mark | |
1761 | * | |
1762 | * Mark a dentry as falling through to the lower layer (as set with | |
1763 | * d_pin_lower()). This flag may be recorded on the medium. | |
1764 | */ | |
1765 | void d_set_fallthru(struct dentry *dentry) | |
1766 | { | |
1767 | spin_lock(&dentry->d_lock); | |
1768 | dentry->d_flags |= DCACHE_FALLTHRU; | |
1769 | spin_unlock(&dentry->d_lock); | |
1770 | } | |
1771 | EXPORT_SYMBOL(d_set_fallthru); | |
1772 | ||
b18825a7 DH |
1773 | static unsigned d_flags_for_inode(struct inode *inode) |
1774 | { | |
44bdb5e5 | 1775 | unsigned add_flags = DCACHE_REGULAR_TYPE; |
b18825a7 DH |
1776 | |
1777 | if (!inode) | |
1778 | return DCACHE_MISS_TYPE; | |
1779 | ||
1780 | if (S_ISDIR(inode->i_mode)) { | |
1781 | add_flags = DCACHE_DIRECTORY_TYPE; | |
1782 | if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { | |
1783 | if (unlikely(!inode->i_op->lookup)) | |
1784 | add_flags = DCACHE_AUTODIR_TYPE; | |
1785 | else | |
1786 | inode->i_opflags |= IOP_LOOKUP; | |
1787 | } | |
44bdb5e5 DH |
1788 | goto type_determined; |
1789 | } | |
1790 | ||
1791 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
6b255391 | 1792 | if (unlikely(inode->i_op->get_link)) { |
b18825a7 | 1793 | add_flags = DCACHE_SYMLINK_TYPE; |
44bdb5e5 DH |
1794 | goto type_determined; |
1795 | } | |
1796 | inode->i_opflags |= IOP_NOFOLLOW; | |
b18825a7 DH |
1797 | } |
1798 | ||
44bdb5e5 DH |
1799 | if (unlikely(!S_ISREG(inode->i_mode))) |
1800 | add_flags = DCACHE_SPECIAL_TYPE; | |
1801 | ||
1802 | type_determined: | |
b18825a7 DH |
1803 | if (unlikely(IS_AUTOMOUNT(inode))) |
1804 | add_flags |= DCACHE_NEED_AUTOMOUNT; | |
1805 | return add_flags; | |
1806 | } | |
1807 | ||
360da900 OH |
1808 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1809 | { | |
b18825a7 | 1810 | unsigned add_flags = d_flags_for_inode(inode); |
85c7f810 | 1811 | WARN_ON(d_in_lookup(dentry)); |
b18825a7 | 1812 | |
b23fb0a6 | 1813 | spin_lock(&dentry->d_lock); |
de689f5e | 1814 | hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); |
a528aca7 | 1815 | raw_write_seqcount_begin(&dentry->d_seq); |
4bf46a27 | 1816 | __d_set_inode_and_type(dentry, inode, add_flags); |
a528aca7 | 1817 | raw_write_seqcount_end(&dentry->d_seq); |
de689f5e | 1818 | __fsnotify_d_instantiate(dentry); |
b23fb0a6 | 1819 | spin_unlock(&dentry->d_lock); |
360da900 OH |
1820 | } |
1821 | ||
1da177e4 LT |
1822 | /** |
1823 | * d_instantiate - fill in inode information for a dentry | |
1824 | * @entry: dentry to complete | |
1825 | * @inode: inode to attach to this dentry | |
1826 | * | |
1827 | * Fill in inode information in the entry. | |
1828 | * | |
1829 | * This turns negative dentries into productive full members | |
1830 | * of society. | |
1831 | * | |
1832 | * NOTE! This assumes that the inode count has been incremented | |
1833 | * (or otherwise set) by the caller to indicate that it is now | |
1834 | * in use by the dcache. | |
1835 | */ | |
1836 | ||
1837 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1838 | { | |
946e51f2 | 1839 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
de689f5e | 1840 | if (inode) { |
b9680917 | 1841 | security_d_instantiate(entry, inode); |
873feea0 | 1842 | spin_lock(&inode->i_lock); |
de689f5e | 1843 | __d_instantiate(entry, inode); |
873feea0 | 1844 | spin_unlock(&inode->i_lock); |
de689f5e | 1845 | } |
1da177e4 | 1846 | } |
ec4f8605 | 1847 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 | 1848 | |
b70a80e7 MS |
1849 | /** |
1850 | * d_instantiate_no_diralias - instantiate a non-aliased dentry | |
1851 | * @entry: dentry to complete | |
1852 | * @inode: inode to attach to this dentry | |
1853 | * | |
1854 | * Fill in inode information in the entry. If a directory alias is found, then | |
1855 | * return an error (and drop inode). Together with d_materialise_unique() this | |
1856 | * guarantees that a directory inode may never have more than one alias. | |
1857 | */ | |
1858 | int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) | |
1859 | { | |
946e51f2 | 1860 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
b70a80e7 | 1861 | |
b9680917 | 1862 | security_d_instantiate(entry, inode); |
b70a80e7 MS |
1863 | spin_lock(&inode->i_lock); |
1864 | if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { | |
1865 | spin_unlock(&inode->i_lock); | |
1866 | iput(inode); | |
1867 | return -EBUSY; | |
1868 | } | |
1869 | __d_instantiate(entry, inode); | |
1870 | spin_unlock(&inode->i_lock); | |
b70a80e7 MS |
1871 | |
1872 | return 0; | |
1873 | } | |
1874 | EXPORT_SYMBOL(d_instantiate_no_diralias); | |
1875 | ||
adc0e91a AV |
1876 | struct dentry *d_make_root(struct inode *root_inode) |
1877 | { | |
1878 | struct dentry *res = NULL; | |
1879 | ||
1880 | if (root_inode) { | |
798434bd | 1881 | res = __d_alloc(root_inode->i_sb, NULL); |
adc0e91a AV |
1882 | if (res) |
1883 | d_instantiate(res, root_inode); | |
1884 | else | |
1885 | iput(root_inode); | |
1886 | } | |
1887 | return res; | |
1888 | } | |
1889 | EXPORT_SYMBOL(d_make_root); | |
1890 | ||
d891eedb BF |
1891 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1892 | { | |
1893 | struct dentry *alias; | |
1894 | ||
b3d9b7a3 | 1895 | if (hlist_empty(&inode->i_dentry)) |
d891eedb | 1896 | return NULL; |
946e51f2 | 1897 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); |
d891eedb BF |
1898 | __dget(alias); |
1899 | return alias; | |
1900 | } | |
1901 | ||
46f72b34 SW |
1902 | /** |
1903 | * d_find_any_alias - find any alias for a given inode | |
1904 | * @inode: inode to find an alias for | |
1905 | * | |
1906 | * If any aliases exist for the given inode, take and return a | |
1907 | * reference for one of them. If no aliases exist, return %NULL. | |
1908 | */ | |
1909 | struct dentry *d_find_any_alias(struct inode *inode) | |
d891eedb BF |
1910 | { |
1911 | struct dentry *de; | |
1912 | ||
1913 | spin_lock(&inode->i_lock); | |
1914 | de = __d_find_any_alias(inode); | |
1915 | spin_unlock(&inode->i_lock); | |
1916 | return de; | |
1917 | } | |
46f72b34 | 1918 | EXPORT_SYMBOL(d_find_any_alias); |
d891eedb | 1919 | |
49c7dd28 | 1920 | static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) |
4ea3ada2 | 1921 | { |
9308a612 CH |
1922 | struct dentry *tmp; |
1923 | struct dentry *res; | |
b18825a7 | 1924 | unsigned add_flags; |
4ea3ada2 CH |
1925 | |
1926 | if (!inode) | |
44003728 | 1927 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1928 | if (IS_ERR(inode)) |
1929 | return ERR_CAST(inode); | |
1930 | ||
d891eedb | 1931 | res = d_find_any_alias(inode); |
9308a612 CH |
1932 | if (res) |
1933 | goto out_iput; | |
1934 | ||
798434bd | 1935 | tmp = __d_alloc(inode->i_sb, NULL); |
9308a612 CH |
1936 | if (!tmp) { |
1937 | res = ERR_PTR(-ENOMEM); | |
1938 | goto out_iput; | |
4ea3ada2 | 1939 | } |
b5c84bf6 | 1940 | |
b9680917 | 1941 | security_d_instantiate(tmp, inode); |
873feea0 | 1942 | spin_lock(&inode->i_lock); |
d891eedb | 1943 | res = __d_find_any_alias(inode); |
9308a612 | 1944 | if (res) { |
873feea0 | 1945 | spin_unlock(&inode->i_lock); |
9308a612 CH |
1946 | dput(tmp); |
1947 | goto out_iput; | |
1948 | } | |
1949 | ||
1950 | /* attach a disconnected dentry */ | |
1a0a397e BF |
1951 | add_flags = d_flags_for_inode(inode); |
1952 | ||
1953 | if (disconnected) | |
1954 | add_flags |= DCACHE_DISCONNECTED; | |
b18825a7 | 1955 | |
9308a612 | 1956 | spin_lock(&tmp->d_lock); |
4bf46a27 | 1957 | __d_set_inode_and_type(tmp, inode, add_flags); |
946e51f2 | 1958 | hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry); |
1879fd6a | 1959 | hlist_bl_lock(&tmp->d_sb->s_anon); |
ceb5bdc2 | 1960 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1879fd6a | 1961 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
9308a612 | 1962 | spin_unlock(&tmp->d_lock); |
873feea0 | 1963 | spin_unlock(&inode->i_lock); |
9308a612 | 1964 | |
9308a612 CH |
1965 | return tmp; |
1966 | ||
1967 | out_iput: | |
1968 | iput(inode); | |
1969 | return res; | |
4ea3ada2 | 1970 | } |
1a0a397e BF |
1971 | |
1972 | /** | |
1973 | * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode | |
1974 | * @inode: inode to allocate the dentry for | |
1975 | * | |
1976 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1977 | * similar open by handle operations. The returned dentry may be anonymous, | |
1978 | * or may have a full name (if the inode was already in the cache). | |
1979 | * | |
1980 | * When called on a directory inode, we must ensure that the inode only ever | |
1981 | * has one dentry. If a dentry is found, that is returned instead of | |
1982 | * allocating a new one. | |
1983 | * | |
1984 | * On successful return, the reference to the inode has been transferred | |
1985 | * to the dentry. In case of an error the reference on the inode is released. | |
1986 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1987 | * be passed in and the error will be propagated to the return value, | |
1988 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
1989 | */ | |
1990 | struct dentry *d_obtain_alias(struct inode *inode) | |
1991 | { | |
1992 | return __d_obtain_alias(inode, 1); | |
1993 | } | |
adc48720 | 1994 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 | 1995 | |
1a0a397e BF |
1996 | /** |
1997 | * d_obtain_root - find or allocate a dentry for a given inode | |
1998 | * @inode: inode to allocate the dentry for | |
1999 | * | |
2000 | * Obtain an IS_ROOT dentry for the root of a filesystem. | |
2001 | * | |
2002 | * We must ensure that directory inodes only ever have one dentry. If a | |
2003 | * dentry is found, that is returned instead of allocating a new one. | |
2004 | * | |
2005 | * On successful return, the reference to the inode has been transferred | |
2006 | * to the dentry. In case of an error the reference on the inode is | |
2007 | * released. A %NULL or IS_ERR inode may be passed in and will be the | |
2008 | * error will be propagate to the return value, with a %NULL @inode | |
2009 | * replaced by ERR_PTR(-ESTALE). | |
2010 | */ | |
2011 | struct dentry *d_obtain_root(struct inode *inode) | |
2012 | { | |
2013 | return __d_obtain_alias(inode, 0); | |
2014 | } | |
2015 | EXPORT_SYMBOL(d_obtain_root); | |
2016 | ||
9403540c BN |
2017 | /** |
2018 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
2019 | * @inode: the inode case-insensitive lookup has found | |
2020 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
2021 | * @name: the case-exact name to be associated with the returned dentry | |
2022 | * | |
2023 | * This is to avoid filling the dcache with case-insensitive names to the | |
2024 | * same inode, only the actual correct case is stored in the dcache for | |
2025 | * case-insensitive filesystems. | |
2026 | * | |
2027 | * For a case-insensitive lookup match and if the the case-exact dentry | |
2028 | * already exists in in the dcache, use it and return it. | |
2029 | * | |
2030 | * If no entry exists with the exact case name, allocate new dentry with | |
2031 | * the exact case, and return the spliced entry. | |
2032 | */ | |
e45b590b | 2033 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
2034 | struct qstr *name) |
2035 | { | |
d9171b93 | 2036 | struct dentry *found, *res; |
9403540c | 2037 | |
b6520c81 CH |
2038 | /* |
2039 | * First check if a dentry matching the name already exists, | |
2040 | * if not go ahead and create it now. | |
2041 | */ | |
9403540c | 2042 | found = d_hash_and_lookup(dentry->d_parent, name); |
d9171b93 AV |
2043 | if (found) { |
2044 | iput(inode); | |
2045 | return found; | |
2046 | } | |
2047 | if (d_in_lookup(dentry)) { | |
2048 | found = d_alloc_parallel(dentry->d_parent, name, | |
2049 | dentry->d_wait); | |
2050 | if (IS_ERR(found) || !d_in_lookup(found)) { | |
2051 | iput(inode); | |
2052 | return found; | |
9403540c | 2053 | } |
d9171b93 AV |
2054 | } else { |
2055 | found = d_alloc(dentry->d_parent, name); | |
2056 | if (!found) { | |
2057 | iput(inode); | |
2058 | return ERR_PTR(-ENOMEM); | |
2059 | } | |
2060 | } | |
2061 | res = d_splice_alias(inode, found); | |
2062 | if (res) { | |
2063 | dput(found); | |
2064 | return res; | |
9403540c | 2065 | } |
4f522a24 | 2066 | return found; |
9403540c | 2067 | } |
ec4f8605 | 2068 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 | 2069 | |
12f8ad4b LT |
2070 | /* |
2071 | * Do the slow-case of the dentry name compare. | |
2072 | * | |
2073 | * Unlike the dentry_cmp() function, we need to atomically | |
da53be12 | 2074 | * load the name and length information, so that the |
12f8ad4b LT |
2075 | * filesystem can rely on them, and can use the 'name' and |
2076 | * 'len' information without worrying about walking off the | |
2077 | * end of memory etc. | |
2078 | * | |
2079 | * Thus the read_seqcount_retry() and the "duplicate" info | |
2080 | * in arguments (the low-level filesystem should not look | |
2081 | * at the dentry inode or name contents directly, since | |
2082 | * rename can change them while we're in RCU mode). | |
2083 | */ | |
2084 | enum slow_d_compare { | |
2085 | D_COMP_OK, | |
2086 | D_COMP_NOMATCH, | |
2087 | D_COMP_SEQRETRY, | |
2088 | }; | |
2089 | ||
2090 | static noinline enum slow_d_compare slow_dentry_cmp( | |
2091 | const struct dentry *parent, | |
12f8ad4b LT |
2092 | struct dentry *dentry, |
2093 | unsigned int seq, | |
2094 | const struct qstr *name) | |
2095 | { | |
2096 | int tlen = dentry->d_name.len; | |
2097 | const char *tname = dentry->d_name.name; | |
12f8ad4b LT |
2098 | |
2099 | if (read_seqcount_retry(&dentry->d_seq, seq)) { | |
2100 | cpu_relax(); | |
2101 | return D_COMP_SEQRETRY; | |
2102 | } | |
da53be12 | 2103 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
12f8ad4b LT |
2104 | return D_COMP_NOMATCH; |
2105 | return D_COMP_OK; | |
2106 | } | |
2107 | ||
31e6b01f NP |
2108 | /** |
2109 | * __d_lookup_rcu - search for a dentry (racy, store-free) | |
2110 | * @parent: parent dentry | |
2111 | * @name: qstr of name we wish to find | |
1f1e6e52 | 2112 | * @seqp: returns d_seq value at the point where the dentry was found |
31e6b01f NP |
2113 | * Returns: dentry, or NULL |
2114 | * | |
2115 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name | |
2116 | * resolution (store-free path walking) design described in | |
2117 | * Documentation/filesystems/path-lookup.txt. | |
2118 | * | |
2119 | * This is not to be used outside core vfs. | |
2120 | * | |
2121 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock | |
2122 | * held, and rcu_read_lock held. The returned dentry must not be stored into | |
2123 | * without taking d_lock and checking d_seq sequence count against @seq | |
2124 | * returned here. | |
2125 | * | |
15570086 | 2126 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
31e6b01f NP |
2127 | * function. |
2128 | * | |
2129 | * Alternatively, __d_lookup_rcu may be called again to look up the child of | |
2130 | * the returned dentry, so long as its parent's seqlock is checked after the | |
2131 | * child is looked up. Thus, an interlocking stepping of sequence lock checks | |
2132 | * is formed, giving integrity down the path walk. | |
12f8ad4b LT |
2133 | * |
2134 | * NOTE! The caller *has* to check the resulting dentry against the sequence | |
2135 | * number we've returned before using any of the resulting dentry state! | |
31e6b01f | 2136 | */ |
8966be90 LT |
2137 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
2138 | const struct qstr *name, | |
da53be12 | 2139 | unsigned *seqp) |
31e6b01f | 2140 | { |
26fe5750 | 2141 | u64 hashlen = name->hash_len; |
31e6b01f | 2142 | const unsigned char *str = name->name; |
26fe5750 | 2143 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
ceb5bdc2 | 2144 | struct hlist_bl_node *node; |
31e6b01f NP |
2145 | struct dentry *dentry; |
2146 | ||
2147 | /* | |
2148 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2149 | * required to prevent single threaded performance regressions | |
2150 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2151 | * Keep the two functions in sync. | |
2152 | */ | |
2153 | ||
2154 | /* | |
2155 | * The hash list is protected using RCU. | |
2156 | * | |
2157 | * Carefully use d_seq when comparing a candidate dentry, to avoid | |
2158 | * races with d_move(). | |
2159 | * | |
2160 | * It is possible that concurrent renames can mess up our list | |
2161 | * walk here and result in missing our dentry, resulting in the | |
2162 | * false-negative result. d_lookup() protects against concurrent | |
2163 | * renames using rename_lock seqlock. | |
2164 | * | |
b0a4bb83 | 2165 | * See Documentation/filesystems/path-lookup.txt for more details. |
31e6b01f | 2166 | */ |
b07ad996 | 2167 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
8966be90 | 2168 | unsigned seq; |
31e6b01f | 2169 | |
31e6b01f | 2170 | seqretry: |
12f8ad4b LT |
2171 | /* |
2172 | * The dentry sequence count protects us from concurrent | |
da53be12 | 2173 | * renames, and thus protects parent and name fields. |
12f8ad4b LT |
2174 | * |
2175 | * The caller must perform a seqcount check in order | |
da53be12 | 2176 | * to do anything useful with the returned dentry. |
12f8ad4b LT |
2177 | * |
2178 | * NOTE! We do a "raw" seqcount_begin here. That means that | |
2179 | * we don't wait for the sequence count to stabilize if it | |
2180 | * is in the middle of a sequence change. If we do the slow | |
2181 | * dentry compare, we will do seqretries until it is stable, | |
2182 | * and if we end up with a successful lookup, we actually | |
2183 | * want to exit RCU lookup anyway. | |
2184 | */ | |
2185 | seq = raw_seqcount_begin(&dentry->d_seq); | |
31e6b01f NP |
2186 | if (dentry->d_parent != parent) |
2187 | continue; | |
2e321806 LT |
2188 | if (d_unhashed(dentry)) |
2189 | continue; | |
12f8ad4b | 2190 | |
830c0f0e | 2191 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
26fe5750 LT |
2192 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
2193 | continue; | |
da53be12 LT |
2194 | *seqp = seq; |
2195 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { | |
12f8ad4b LT |
2196 | case D_COMP_OK: |
2197 | return dentry; | |
2198 | case D_COMP_NOMATCH: | |
31e6b01f | 2199 | continue; |
12f8ad4b LT |
2200 | default: |
2201 | goto seqretry; | |
2202 | } | |
31e6b01f | 2203 | } |
12f8ad4b | 2204 | |
26fe5750 | 2205 | if (dentry->d_name.hash_len != hashlen) |
ee983e89 | 2206 | continue; |
da53be12 | 2207 | *seqp = seq; |
26fe5750 | 2208 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
12f8ad4b | 2209 | return dentry; |
31e6b01f NP |
2210 | } |
2211 | return NULL; | |
2212 | } | |
2213 | ||
1da177e4 LT |
2214 | /** |
2215 | * d_lookup - search for a dentry | |
2216 | * @parent: parent dentry | |
2217 | * @name: qstr of name we wish to find | |
b04f784e | 2218 | * Returns: dentry, or NULL |
1da177e4 | 2219 | * |
b04f784e NP |
2220 | * d_lookup searches the children of the parent dentry for the name in |
2221 | * question. If the dentry is found its reference count is incremented and the | |
2222 | * dentry is returned. The caller must use dput to free the entry when it has | |
2223 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 2224 | */ |
da2d8455 | 2225 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 | 2226 | { |
31e6b01f | 2227 | struct dentry *dentry; |
949854d0 | 2228 | unsigned seq; |
1da177e4 | 2229 | |
b8314f93 DY |
2230 | do { |
2231 | seq = read_seqbegin(&rename_lock); | |
2232 | dentry = __d_lookup(parent, name); | |
2233 | if (dentry) | |
1da177e4 LT |
2234 | break; |
2235 | } while (read_seqretry(&rename_lock, seq)); | |
2236 | return dentry; | |
2237 | } | |
ec4f8605 | 2238 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 2239 | |
31e6b01f | 2240 | /** |
b04f784e NP |
2241 | * __d_lookup - search for a dentry (racy) |
2242 | * @parent: parent dentry | |
2243 | * @name: qstr of name we wish to find | |
2244 | * Returns: dentry, or NULL | |
2245 | * | |
2246 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
2247 | * false-negative result due to unrelated rename activity. | |
2248 | * | |
2249 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
2250 | * however it must be used carefully, eg. with a following d_lookup in | |
2251 | * the case of failure. | |
2252 | * | |
2253 | * __d_lookup callers must be commented. | |
2254 | */ | |
a713ca2a | 2255 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 LT |
2256 | { |
2257 | unsigned int len = name->len; | |
2258 | unsigned int hash = name->hash; | |
2259 | const unsigned char *str = name->name; | |
b07ad996 | 2260 | struct hlist_bl_head *b = d_hash(parent, hash); |
ceb5bdc2 | 2261 | struct hlist_bl_node *node; |
31e6b01f | 2262 | struct dentry *found = NULL; |
665a7583 | 2263 | struct dentry *dentry; |
1da177e4 | 2264 | |
31e6b01f NP |
2265 | /* |
2266 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2267 | * required to prevent single threaded performance regressions | |
2268 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2269 | * Keep the two functions in sync. | |
2270 | */ | |
2271 | ||
b04f784e NP |
2272 | /* |
2273 | * The hash list is protected using RCU. | |
2274 | * | |
2275 | * Take d_lock when comparing a candidate dentry, to avoid races | |
2276 | * with d_move(). | |
2277 | * | |
2278 | * It is possible that concurrent renames can mess up our list | |
2279 | * walk here and result in missing our dentry, resulting in the | |
2280 | * false-negative result. d_lookup() protects against concurrent | |
2281 | * renames using rename_lock seqlock. | |
2282 | * | |
b0a4bb83 | 2283 | * See Documentation/filesystems/path-lookup.txt for more details. |
b04f784e | 2284 | */ |
1da177e4 LT |
2285 | rcu_read_lock(); |
2286 | ||
b07ad996 | 2287 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1da177e4 | 2288 | |
1da177e4 LT |
2289 | if (dentry->d_name.hash != hash) |
2290 | continue; | |
1da177e4 LT |
2291 | |
2292 | spin_lock(&dentry->d_lock); | |
1da177e4 LT |
2293 | if (dentry->d_parent != parent) |
2294 | goto next; | |
d0185c08 LT |
2295 | if (d_unhashed(dentry)) |
2296 | goto next; | |
2297 | ||
1da177e4 LT |
2298 | /* |
2299 | * It is safe to compare names since d_move() cannot | |
2300 | * change the qstr (protected by d_lock). | |
2301 | */ | |
fb045adb | 2302 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
12f8ad4b LT |
2303 | int tlen = dentry->d_name.len; |
2304 | const char *tname = dentry->d_name.name; | |
da53be12 | 2305 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
1da177e4 LT |
2306 | goto next; |
2307 | } else { | |
ee983e89 LT |
2308 | if (dentry->d_name.len != len) |
2309 | goto next; | |
12f8ad4b | 2310 | if (dentry_cmp(dentry, str, len)) |
1da177e4 LT |
2311 | goto next; |
2312 | } | |
2313 | ||
98474236 | 2314 | dentry->d_lockref.count++; |
d0185c08 | 2315 | found = dentry; |
1da177e4 LT |
2316 | spin_unlock(&dentry->d_lock); |
2317 | break; | |
2318 | next: | |
2319 | spin_unlock(&dentry->d_lock); | |
2320 | } | |
2321 | rcu_read_unlock(); | |
2322 | ||
2323 | return found; | |
2324 | } | |
2325 | ||
3e7e241f EB |
2326 | /** |
2327 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
2328 | * @dir: Directory to search in | |
2329 | * @name: qstr of name we wish to find | |
2330 | * | |
4f522a24 | 2331 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
3e7e241f EB |
2332 | */ |
2333 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
2334 | { | |
3e7e241f EB |
2335 | /* |
2336 | * Check for a fs-specific hash function. Note that we must | |
2337 | * calculate the standard hash first, as the d_op->d_hash() | |
2338 | * routine may choose to leave the hash value unchanged. | |
2339 | */ | |
2340 | name->hash = full_name_hash(name->name, name->len); | |
fb045adb | 2341 | if (dir->d_flags & DCACHE_OP_HASH) { |
da53be12 | 2342 | int err = dir->d_op->d_hash(dir, name); |
4f522a24 AV |
2343 | if (unlikely(err < 0)) |
2344 | return ERR_PTR(err); | |
3e7e241f | 2345 | } |
4f522a24 | 2346 | return d_lookup(dir, name); |
3e7e241f | 2347 | } |
4f522a24 | 2348 | EXPORT_SYMBOL(d_hash_and_lookup); |
3e7e241f | 2349 | |
1da177e4 LT |
2350 | /* |
2351 | * When a file is deleted, we have two options: | |
2352 | * - turn this dentry into a negative dentry | |
2353 | * - unhash this dentry and free it. | |
2354 | * | |
2355 | * Usually, we want to just turn this into | |
2356 | * a negative dentry, but if anybody else is | |
2357 | * currently using the dentry or the inode | |
2358 | * we can't do that and we fall back on removing | |
2359 | * it from the hash queues and waiting for | |
2360 | * it to be deleted later when it has no users | |
2361 | */ | |
2362 | ||
2363 | /** | |
2364 | * d_delete - delete a dentry | |
2365 | * @dentry: The dentry to delete | |
2366 | * | |
2367 | * Turn the dentry into a negative dentry if possible, otherwise | |
2368 | * remove it from the hash queues so it can be deleted later | |
2369 | */ | |
2370 | ||
2371 | void d_delete(struct dentry * dentry) | |
2372 | { | |
873feea0 | 2373 | struct inode *inode; |
7a91bf7f | 2374 | int isdir = 0; |
1da177e4 LT |
2375 | /* |
2376 | * Are we the only user? | |
2377 | */ | |
357f8e65 | 2378 | again: |
1da177e4 | 2379 | spin_lock(&dentry->d_lock); |
873feea0 NP |
2380 | inode = dentry->d_inode; |
2381 | isdir = S_ISDIR(inode->i_mode); | |
98474236 | 2382 | if (dentry->d_lockref.count == 1) { |
1fe0c023 | 2383 | if (!spin_trylock(&inode->i_lock)) { |
357f8e65 NP |
2384 | spin_unlock(&dentry->d_lock); |
2385 | cpu_relax(); | |
2386 | goto again; | |
2387 | } | |
13e3c5e5 | 2388 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
31e6b01f | 2389 | dentry_unlink_inode(dentry); |
7a91bf7f | 2390 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
2391 | return; |
2392 | } | |
2393 | ||
2394 | if (!d_unhashed(dentry)) | |
2395 | __d_drop(dentry); | |
2396 | ||
2397 | spin_unlock(&dentry->d_lock); | |
7a91bf7f JM |
2398 | |
2399 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 2400 | } |
ec4f8605 | 2401 | EXPORT_SYMBOL(d_delete); |
1da177e4 | 2402 | |
b07ad996 | 2403 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
1da177e4 | 2404 | { |
ceb5bdc2 | 2405 | BUG_ON(!d_unhashed(entry)); |
1879fd6a | 2406 | hlist_bl_lock(b); |
b07ad996 | 2407 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
1879fd6a | 2408 | hlist_bl_unlock(b); |
1da177e4 LT |
2409 | } |
2410 | ||
770bfad8 DH |
2411 | static void _d_rehash(struct dentry * entry) |
2412 | { | |
2413 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
2414 | } | |
2415 | ||
1da177e4 LT |
2416 | /** |
2417 | * d_rehash - add an entry back to the hash | |
2418 | * @entry: dentry to add to the hash | |
2419 | * | |
2420 | * Adds a dentry to the hash according to its name. | |
2421 | */ | |
2422 | ||
2423 | void d_rehash(struct dentry * entry) | |
2424 | { | |
1da177e4 | 2425 | spin_lock(&entry->d_lock); |
770bfad8 | 2426 | _d_rehash(entry); |
1da177e4 | 2427 | spin_unlock(&entry->d_lock); |
1da177e4 | 2428 | } |
ec4f8605 | 2429 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 2430 | |
84e710da AV |
2431 | static inline unsigned start_dir_add(struct inode *dir) |
2432 | { | |
2433 | ||
2434 | for (;;) { | |
2435 | unsigned n = dir->i_dir_seq; | |
2436 | if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n) | |
2437 | return n; | |
2438 | cpu_relax(); | |
2439 | } | |
2440 | } | |
2441 | ||
2442 | static inline void end_dir_add(struct inode *dir, unsigned n) | |
2443 | { | |
2444 | smp_store_release(&dir->i_dir_seq, n + 2); | |
2445 | } | |
2446 | ||
d9171b93 AV |
2447 | static void d_wait_lookup(struct dentry *dentry) |
2448 | { | |
2449 | if (d_in_lookup(dentry)) { | |
2450 | DECLARE_WAITQUEUE(wait, current); | |
2451 | add_wait_queue(dentry->d_wait, &wait); | |
2452 | do { | |
2453 | set_current_state(TASK_UNINTERRUPTIBLE); | |
2454 | spin_unlock(&dentry->d_lock); | |
2455 | schedule(); | |
2456 | spin_lock(&dentry->d_lock); | |
2457 | } while (d_in_lookup(dentry)); | |
2458 | } | |
2459 | } | |
2460 | ||
94bdd655 | 2461 | struct dentry *d_alloc_parallel(struct dentry *parent, |
d9171b93 AV |
2462 | const struct qstr *name, |
2463 | wait_queue_head_t *wq) | |
94bdd655 AV |
2464 | { |
2465 | unsigned int len = name->len; | |
2466 | unsigned int hash = name->hash; | |
2467 | const unsigned char *str = name->name; | |
2468 | struct hlist_bl_head *b = in_lookup_hash(parent, hash); | |
2469 | struct hlist_bl_node *node; | |
2470 | struct dentry *new = d_alloc(parent, name); | |
2471 | struct dentry *dentry; | |
2472 | unsigned seq, r_seq, d_seq; | |
2473 | ||
2474 | if (unlikely(!new)) | |
2475 | return ERR_PTR(-ENOMEM); | |
2476 | ||
2477 | retry: | |
2478 | rcu_read_lock(); | |
2479 | seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1; | |
2480 | r_seq = read_seqbegin(&rename_lock); | |
2481 | dentry = __d_lookup_rcu(parent, name, &d_seq); | |
2482 | if (unlikely(dentry)) { | |
2483 | if (!lockref_get_not_dead(&dentry->d_lockref)) { | |
2484 | rcu_read_unlock(); | |
2485 | goto retry; | |
2486 | } | |
2487 | if (read_seqcount_retry(&dentry->d_seq, d_seq)) { | |
2488 | rcu_read_unlock(); | |
2489 | dput(dentry); | |
2490 | goto retry; | |
2491 | } | |
2492 | rcu_read_unlock(); | |
2493 | dput(new); | |
2494 | return dentry; | |
2495 | } | |
2496 | if (unlikely(read_seqretry(&rename_lock, r_seq))) { | |
2497 | rcu_read_unlock(); | |
2498 | goto retry; | |
2499 | } | |
2500 | hlist_bl_lock(b); | |
2501 | if (unlikely(parent->d_inode->i_dir_seq != seq)) { | |
2502 | hlist_bl_unlock(b); | |
2503 | rcu_read_unlock(); | |
2504 | goto retry; | |
2505 | } | |
94bdd655 AV |
2506 | /* |
2507 | * No changes for the parent since the beginning of d_lookup(). | |
2508 | * Since all removals from the chain happen with hlist_bl_lock(), | |
2509 | * any potential in-lookup matches are going to stay here until | |
2510 | * we unlock the chain. All fields are stable in everything | |
2511 | * we encounter. | |
2512 | */ | |
2513 | hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) { | |
2514 | if (dentry->d_name.hash != hash) | |
2515 | continue; | |
2516 | if (dentry->d_parent != parent) | |
2517 | continue; | |
94bdd655 AV |
2518 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
2519 | int tlen = dentry->d_name.len; | |
2520 | const char *tname = dentry->d_name.name; | |
2521 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) | |
2522 | continue; | |
2523 | } else { | |
2524 | if (dentry->d_name.len != len) | |
2525 | continue; | |
2526 | if (dentry_cmp(dentry, str, len)) | |
2527 | continue; | |
2528 | } | |
94bdd655 | 2529 | hlist_bl_unlock(b); |
e7d6ef97 AV |
2530 | /* now we can try to grab a reference */ |
2531 | if (!lockref_get_not_dead(&dentry->d_lockref)) { | |
2532 | rcu_read_unlock(); | |
2533 | goto retry; | |
2534 | } | |
2535 | ||
2536 | rcu_read_unlock(); | |
2537 | /* | |
2538 | * somebody is likely to be still doing lookup for it; | |
2539 | * wait for them to finish | |
2540 | */ | |
d9171b93 AV |
2541 | spin_lock(&dentry->d_lock); |
2542 | d_wait_lookup(dentry); | |
2543 | /* | |
2544 | * it's not in-lookup anymore; in principle we should repeat | |
2545 | * everything from dcache lookup, but it's likely to be what | |
2546 | * d_lookup() would've found anyway. If it is, just return it; | |
2547 | * otherwise we really have to repeat the whole thing. | |
2548 | */ | |
2549 | if (unlikely(dentry->d_name.hash != hash)) | |
2550 | goto mismatch; | |
2551 | if (unlikely(dentry->d_parent != parent)) | |
2552 | goto mismatch; | |
2553 | if (unlikely(d_unhashed(dentry))) | |
2554 | goto mismatch; | |
2555 | if (parent->d_flags & DCACHE_OP_COMPARE) { | |
2556 | int tlen = dentry->d_name.len; | |
2557 | const char *tname = dentry->d_name.name; | |
2558 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) | |
2559 | goto mismatch; | |
2560 | } else { | |
2561 | if (unlikely(dentry->d_name.len != len)) | |
2562 | goto mismatch; | |
2563 | if (unlikely(dentry_cmp(dentry, str, len))) | |
2564 | goto mismatch; | |
2565 | } | |
2566 | /* OK, it *is* a hashed match; return it */ | |
2567 | spin_unlock(&dentry->d_lock); | |
94bdd655 AV |
2568 | dput(new); |
2569 | return dentry; | |
2570 | } | |
e7d6ef97 | 2571 | rcu_read_unlock(); |
94bdd655 AV |
2572 | /* we can't take ->d_lock here; it's OK, though. */ |
2573 | new->d_flags |= DCACHE_PAR_LOOKUP; | |
d9171b93 | 2574 | new->d_wait = wq; |
94bdd655 AV |
2575 | hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b); |
2576 | hlist_bl_unlock(b); | |
2577 | return new; | |
d9171b93 AV |
2578 | mismatch: |
2579 | spin_unlock(&dentry->d_lock); | |
2580 | dput(dentry); | |
2581 | goto retry; | |
94bdd655 AV |
2582 | } |
2583 | EXPORT_SYMBOL(d_alloc_parallel); | |
2584 | ||
85c7f810 AV |
2585 | void __d_lookup_done(struct dentry *dentry) |
2586 | { | |
94bdd655 AV |
2587 | struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent, |
2588 | dentry->d_name.hash); | |
2589 | hlist_bl_lock(b); | |
85c7f810 | 2590 | dentry->d_flags &= ~DCACHE_PAR_LOOKUP; |
94bdd655 | 2591 | __hlist_bl_del(&dentry->d_u.d_in_lookup_hash); |
d9171b93 AV |
2592 | wake_up_all(dentry->d_wait); |
2593 | dentry->d_wait = NULL; | |
94bdd655 AV |
2594 | hlist_bl_unlock(b); |
2595 | INIT_HLIST_NODE(&dentry->d_u.d_alias); | |
d9171b93 | 2596 | INIT_LIST_HEAD(&dentry->d_lru); |
85c7f810 AV |
2597 | } |
2598 | EXPORT_SYMBOL(__d_lookup_done); | |
ed782b5a AV |
2599 | |
2600 | /* inode->i_lock held if inode is non-NULL */ | |
2601 | ||
2602 | static inline void __d_add(struct dentry *dentry, struct inode *inode) | |
2603 | { | |
84e710da AV |
2604 | struct inode *dir = NULL; |
2605 | unsigned n; | |
0568d705 | 2606 | spin_lock(&dentry->d_lock); |
84e710da AV |
2607 | if (unlikely(d_in_lookup(dentry))) { |
2608 | dir = dentry->d_parent->d_inode; | |
2609 | n = start_dir_add(dir); | |
85c7f810 | 2610 | __d_lookup_done(dentry); |
84e710da | 2611 | } |
ed782b5a | 2612 | if (inode) { |
0568d705 AV |
2613 | unsigned add_flags = d_flags_for_inode(inode); |
2614 | hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); | |
2615 | raw_write_seqcount_begin(&dentry->d_seq); | |
2616 | __d_set_inode_and_type(dentry, inode, add_flags); | |
2617 | raw_write_seqcount_end(&dentry->d_seq); | |
2618 | __fsnotify_d_instantiate(dentry); | |
ed782b5a | 2619 | } |
0568d705 | 2620 | _d_rehash(dentry); |
84e710da AV |
2621 | if (dir) |
2622 | end_dir_add(dir, n); | |
0568d705 AV |
2623 | spin_unlock(&dentry->d_lock); |
2624 | if (inode) | |
2625 | spin_unlock(&inode->i_lock); | |
ed782b5a AV |
2626 | } |
2627 | ||
34d0d19d AV |
2628 | /** |
2629 | * d_add - add dentry to hash queues | |
2630 | * @entry: dentry to add | |
2631 | * @inode: The inode to attach to this dentry | |
2632 | * | |
2633 | * This adds the entry to the hash queues and initializes @inode. | |
2634 | * The entry was actually filled in earlier during d_alloc(). | |
2635 | */ | |
2636 | ||
2637 | void d_add(struct dentry *entry, struct inode *inode) | |
2638 | { | |
b9680917 AV |
2639 | if (inode) { |
2640 | security_d_instantiate(entry, inode); | |
ed782b5a | 2641 | spin_lock(&inode->i_lock); |
b9680917 | 2642 | } |
ed782b5a | 2643 | __d_add(entry, inode); |
34d0d19d AV |
2644 | } |
2645 | EXPORT_SYMBOL(d_add); | |
2646 | ||
668d0cd5 AV |
2647 | /** |
2648 | * d_exact_alias - find and hash an exact unhashed alias | |
2649 | * @entry: dentry to add | |
2650 | * @inode: The inode to go with this dentry | |
2651 | * | |
2652 | * If an unhashed dentry with the same name/parent and desired | |
2653 | * inode already exists, hash and return it. Otherwise, return | |
2654 | * NULL. | |
2655 | * | |
2656 | * Parent directory should be locked. | |
2657 | */ | |
2658 | struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) | |
2659 | { | |
2660 | struct dentry *alias; | |
2661 | int len = entry->d_name.len; | |
2662 | const char *name = entry->d_name.name; | |
2663 | unsigned int hash = entry->d_name.hash; | |
2664 | ||
2665 | spin_lock(&inode->i_lock); | |
2666 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { | |
2667 | /* | |
2668 | * Don't need alias->d_lock here, because aliases with | |
2669 | * d_parent == entry->d_parent are not subject to name or | |
2670 | * parent changes, because the parent inode i_mutex is held. | |
2671 | */ | |
2672 | if (alias->d_name.hash != hash) | |
2673 | continue; | |
2674 | if (alias->d_parent != entry->d_parent) | |
2675 | continue; | |
2676 | if (alias->d_name.len != len) | |
2677 | continue; | |
2678 | if (dentry_cmp(alias, name, len)) | |
2679 | continue; | |
2680 | spin_lock(&alias->d_lock); | |
2681 | if (!d_unhashed(alias)) { | |
2682 | spin_unlock(&alias->d_lock); | |
2683 | alias = NULL; | |
2684 | } else { | |
2685 | __dget_dlock(alias); | |
2686 | _d_rehash(alias); | |
2687 | spin_unlock(&alias->d_lock); | |
2688 | } | |
2689 | spin_unlock(&inode->i_lock); | |
2690 | return alias; | |
2691 | } | |
2692 | spin_unlock(&inode->i_lock); | |
2693 | return NULL; | |
2694 | } | |
2695 | EXPORT_SYMBOL(d_exact_alias); | |
2696 | ||
fb2d5b86 NP |
2697 | /** |
2698 | * dentry_update_name_case - update case insensitive dentry with a new name | |
2699 | * @dentry: dentry to be updated | |
2700 | * @name: new name | |
2701 | * | |
2702 | * Update a case insensitive dentry with new case of name. | |
2703 | * | |
2704 | * dentry must have been returned by d_lookup with name @name. Old and new | |
2705 | * name lengths must match (ie. no d_compare which allows mismatched name | |
2706 | * lengths). | |
2707 | * | |
2708 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
2709 | * keep renames and concurrent inserts, and readdir(2) away). | |
2710 | */ | |
2711 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
2712 | { | |
5955102c | 2713 | BUG_ON(!inode_is_locked(dentry->d_parent->d_inode)); |
fb2d5b86 NP |
2714 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2715 | ||
fb2d5b86 | 2716 | spin_lock(&dentry->d_lock); |
31e6b01f | 2717 | write_seqcount_begin(&dentry->d_seq); |
fb2d5b86 | 2718 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
31e6b01f | 2719 | write_seqcount_end(&dentry->d_seq); |
fb2d5b86 | 2720 | spin_unlock(&dentry->d_lock); |
fb2d5b86 NP |
2721 | } |
2722 | EXPORT_SYMBOL(dentry_update_name_case); | |
2723 | ||
8d85b484 | 2724 | static void swap_names(struct dentry *dentry, struct dentry *target) |
1da177e4 | 2725 | { |
8d85b484 AV |
2726 | if (unlikely(dname_external(target))) { |
2727 | if (unlikely(dname_external(dentry))) { | |
1da177e4 LT |
2728 | /* |
2729 | * Both external: swap the pointers | |
2730 | */ | |
9a8d5bb4 | 2731 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
2732 | } else { |
2733 | /* | |
2734 | * dentry:internal, target:external. Steal target's | |
2735 | * storage and make target internal. | |
2736 | */ | |
321bcf92 BF |
2737 | memcpy(target->d_iname, dentry->d_name.name, |
2738 | dentry->d_name.len + 1); | |
1da177e4 LT |
2739 | dentry->d_name.name = target->d_name.name; |
2740 | target->d_name.name = target->d_iname; | |
2741 | } | |
2742 | } else { | |
8d85b484 | 2743 | if (unlikely(dname_external(dentry))) { |
1da177e4 LT |
2744 | /* |
2745 | * dentry:external, target:internal. Give dentry's | |
2746 | * storage to target and make dentry internal | |
2747 | */ | |
2748 | memcpy(dentry->d_iname, target->d_name.name, | |
2749 | target->d_name.len + 1); | |
2750 | target->d_name.name = dentry->d_name.name; | |
2751 | dentry->d_name.name = dentry->d_iname; | |
2752 | } else { | |
2753 | /* | |
da1ce067 | 2754 | * Both are internal. |
1da177e4 | 2755 | */ |
da1ce067 MS |
2756 | unsigned int i; |
2757 | BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); | |
08d4f772 MP |
2758 | kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN); |
2759 | kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN); | |
da1ce067 MS |
2760 | for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { |
2761 | swap(((long *) &dentry->d_iname)[i], | |
2762 | ((long *) &target->d_iname)[i]); | |
2763 | } | |
1da177e4 LT |
2764 | } |
2765 | } | |
a28ddb87 | 2766 | swap(dentry->d_name.hash_len, target->d_name.hash_len); |
1da177e4 LT |
2767 | } |
2768 | ||
8d85b484 AV |
2769 | static void copy_name(struct dentry *dentry, struct dentry *target) |
2770 | { | |
2771 | struct external_name *old_name = NULL; | |
2772 | if (unlikely(dname_external(dentry))) | |
2773 | old_name = external_name(dentry); | |
2774 | if (unlikely(dname_external(target))) { | |
2775 | atomic_inc(&external_name(target)->u.count); | |
2776 | dentry->d_name = target->d_name; | |
2777 | } else { | |
2778 | memcpy(dentry->d_iname, target->d_name.name, | |
2779 | target->d_name.len + 1); | |
2780 | dentry->d_name.name = dentry->d_iname; | |
2781 | dentry->d_name.hash_len = target->d_name.hash_len; | |
2782 | } | |
2783 | if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) | |
2784 | kfree_rcu(old_name, u.head); | |
2785 | } | |
2786 | ||
2fd6b7f5 NP |
2787 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2788 | { | |
2789 | /* | |
2790 | * XXXX: do we really need to take target->d_lock? | |
2791 | */ | |
2792 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) | |
2793 | spin_lock(&target->d_parent->d_lock); | |
2794 | else { | |
2795 | if (d_ancestor(dentry->d_parent, target->d_parent)) { | |
2796 | spin_lock(&dentry->d_parent->d_lock); | |
2797 | spin_lock_nested(&target->d_parent->d_lock, | |
2798 | DENTRY_D_LOCK_NESTED); | |
2799 | } else { | |
2800 | spin_lock(&target->d_parent->d_lock); | |
2801 | spin_lock_nested(&dentry->d_parent->d_lock, | |
2802 | DENTRY_D_LOCK_NESTED); | |
2803 | } | |
2804 | } | |
2805 | if (target < dentry) { | |
2806 | spin_lock_nested(&target->d_lock, 2); | |
2807 | spin_lock_nested(&dentry->d_lock, 3); | |
2808 | } else { | |
2809 | spin_lock_nested(&dentry->d_lock, 2); | |
2810 | spin_lock_nested(&target->d_lock, 3); | |
2811 | } | |
2812 | } | |
2813 | ||
986c0194 | 2814 | static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target) |
2fd6b7f5 NP |
2815 | { |
2816 | if (target->d_parent != dentry->d_parent) | |
2817 | spin_unlock(&dentry->d_parent->d_lock); | |
2818 | if (target->d_parent != target) | |
2819 | spin_unlock(&target->d_parent->d_lock); | |
986c0194 AV |
2820 | spin_unlock(&target->d_lock); |
2821 | spin_unlock(&dentry->d_lock); | |
2fd6b7f5 NP |
2822 | } |
2823 | ||
1da177e4 | 2824 | /* |
2fd6b7f5 NP |
2825 | * When switching names, the actual string doesn't strictly have to |
2826 | * be preserved in the target - because we're dropping the target | |
2827 | * anyway. As such, we can just do a simple memcpy() to copy over | |
d2fa4a84 ME |
2828 | * the new name before we switch, unless we are going to rehash |
2829 | * it. Note that if we *do* unhash the target, we are not allowed | |
2830 | * to rehash it without giving it a new name/hash key - whether | |
2831 | * we swap or overwrite the names here, resulting name won't match | |
2832 | * the reality in filesystem; it's only there for d_path() purposes. | |
2833 | * Note that all of this is happening under rename_lock, so the | |
2834 | * any hash lookup seeing it in the middle of manipulations will | |
2835 | * be discarded anyway. So we do not care what happens to the hash | |
2836 | * key in that case. | |
1da177e4 | 2837 | */ |
9eaef27b | 2838 | /* |
18367501 | 2839 | * __d_move - move a dentry |
1da177e4 LT |
2840 | * @dentry: entry to move |
2841 | * @target: new dentry | |
da1ce067 | 2842 | * @exchange: exchange the two dentries |
1da177e4 LT |
2843 | * |
2844 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2845 | * dcache entries should not be moved in this way. Caller must hold |
2846 | * rename_lock, the i_mutex of the source and target directories, | |
2847 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). | |
1da177e4 | 2848 | */ |
da1ce067 MS |
2849 | static void __d_move(struct dentry *dentry, struct dentry *target, |
2850 | bool exchange) | |
1da177e4 | 2851 | { |
84e710da AV |
2852 | struct inode *dir = NULL; |
2853 | unsigned n; | |
1da177e4 LT |
2854 | if (!dentry->d_inode) |
2855 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
2856 | ||
2fd6b7f5 NP |
2857 | BUG_ON(d_ancestor(dentry, target)); |
2858 | BUG_ON(d_ancestor(target, dentry)); | |
2859 | ||
2fd6b7f5 | 2860 | dentry_lock_for_move(dentry, target); |
84e710da AV |
2861 | if (unlikely(d_in_lookup(target))) { |
2862 | dir = target->d_parent->d_inode; | |
2863 | n = start_dir_add(dir); | |
85c7f810 | 2864 | __d_lookup_done(target); |
84e710da | 2865 | } |
1da177e4 | 2866 | |
31e6b01f | 2867 | write_seqcount_begin(&dentry->d_seq); |
1ca7d67c | 2868 | write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); |
31e6b01f | 2869 | |
ceb5bdc2 NP |
2870 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2871 | ||
2872 | /* | |
2873 | * Move the dentry to the target hash queue. Don't bother checking | |
2874 | * for the same hash queue because of how unlikely it is. | |
2875 | */ | |
2876 | __d_drop(dentry); | |
789680d1 | 2877 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
1da177e4 | 2878 | |
da1ce067 MS |
2879 | /* |
2880 | * Unhash the target (d_delete() is not usable here). If exchanging | |
2881 | * the two dentries, then rehash onto the other's hash queue. | |
2882 | */ | |
1da177e4 | 2883 | __d_drop(target); |
da1ce067 MS |
2884 | if (exchange) { |
2885 | __d_rehash(target, | |
2886 | d_hash(dentry->d_parent, dentry->d_name.hash)); | |
2887 | } | |
1da177e4 | 2888 | |
1da177e4 | 2889 | /* Switch the names.. */ |
8d85b484 AV |
2890 | if (exchange) |
2891 | swap_names(dentry, target); | |
2892 | else | |
2893 | copy_name(dentry, target); | |
1da177e4 | 2894 | |
63cf427a | 2895 | /* ... and switch them in the tree */ |
1da177e4 | 2896 | if (IS_ROOT(dentry)) { |
63cf427a | 2897 | /* splicing a tree */ |
3d56c25e | 2898 | dentry->d_flags |= DCACHE_RCUACCESS; |
1da177e4 LT |
2899 | dentry->d_parent = target->d_parent; |
2900 | target->d_parent = target; | |
946e51f2 AV |
2901 | list_del_init(&target->d_child); |
2902 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); | |
1da177e4 | 2903 | } else { |
63cf427a | 2904 | /* swapping two dentries */ |
9a8d5bb4 | 2905 | swap(dentry->d_parent, target->d_parent); |
946e51f2 AV |
2906 | list_move(&target->d_child, &target->d_parent->d_subdirs); |
2907 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); | |
63cf427a AV |
2908 | if (exchange) |
2909 | fsnotify_d_move(target); | |
2910 | fsnotify_d_move(dentry); | |
1da177e4 LT |
2911 | } |
2912 | ||
31e6b01f NP |
2913 | write_seqcount_end(&target->d_seq); |
2914 | write_seqcount_end(&dentry->d_seq); | |
2915 | ||
84e710da AV |
2916 | if (dir) |
2917 | end_dir_add(dir, n); | |
986c0194 | 2918 | dentry_unlock_for_move(dentry, target); |
18367501 AV |
2919 | } |
2920 | ||
2921 | /* | |
2922 | * d_move - move a dentry | |
2923 | * @dentry: entry to move | |
2924 | * @target: new dentry | |
2925 | * | |
2926 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2927 | * dcache entries should not be moved in this way. See the locking |
2928 | * requirements for __d_move. | |
18367501 AV |
2929 | */ |
2930 | void d_move(struct dentry *dentry, struct dentry *target) | |
2931 | { | |
2932 | write_seqlock(&rename_lock); | |
da1ce067 | 2933 | __d_move(dentry, target, false); |
1da177e4 | 2934 | write_sequnlock(&rename_lock); |
9eaef27b | 2935 | } |
ec4f8605 | 2936 | EXPORT_SYMBOL(d_move); |
1da177e4 | 2937 | |
da1ce067 MS |
2938 | /* |
2939 | * d_exchange - exchange two dentries | |
2940 | * @dentry1: first dentry | |
2941 | * @dentry2: second dentry | |
2942 | */ | |
2943 | void d_exchange(struct dentry *dentry1, struct dentry *dentry2) | |
2944 | { | |
2945 | write_seqlock(&rename_lock); | |
2946 | ||
2947 | WARN_ON(!dentry1->d_inode); | |
2948 | WARN_ON(!dentry2->d_inode); | |
2949 | WARN_ON(IS_ROOT(dentry1)); | |
2950 | WARN_ON(IS_ROOT(dentry2)); | |
2951 | ||
2952 | __d_move(dentry1, dentry2, true); | |
2953 | ||
2954 | write_sequnlock(&rename_lock); | |
2955 | } | |
2956 | ||
e2761a11 OH |
2957 | /** |
2958 | * d_ancestor - search for an ancestor | |
2959 | * @p1: ancestor dentry | |
2960 | * @p2: child dentry | |
2961 | * | |
2962 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
2963 | * an ancestor of p2, else NULL. | |
9eaef27b | 2964 | */ |
e2761a11 | 2965 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
2966 | { |
2967 | struct dentry *p; | |
2968 | ||
871c0067 | 2969 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 2970 | if (p->d_parent == p1) |
e2761a11 | 2971 | return p; |
9eaef27b | 2972 | } |
e2761a11 | 2973 | return NULL; |
9eaef27b TM |
2974 | } |
2975 | ||
2976 | /* | |
2977 | * This helper attempts to cope with remotely renamed directories | |
2978 | * | |
2979 | * It assumes that the caller is already holding | |
a03e283b | 2980 | * dentry->d_parent->d_inode->i_mutex, and rename_lock |
9eaef27b TM |
2981 | * |
2982 | * Note: If ever the locking in lock_rename() changes, then please | |
2983 | * remember to update this too... | |
9eaef27b | 2984 | */ |
b5ae6b15 | 2985 | static int __d_unalias(struct inode *inode, |
873feea0 | 2986 | struct dentry *dentry, struct dentry *alias) |
9eaef27b | 2987 | { |
9902af79 AV |
2988 | struct mutex *m1 = NULL; |
2989 | struct rw_semaphore *m2 = NULL; | |
3d330dc1 | 2990 | int ret = -ESTALE; |
9eaef27b TM |
2991 | |
2992 | /* If alias and dentry share a parent, then no extra locks required */ | |
2993 | if (alias->d_parent == dentry->d_parent) | |
2994 | goto out_unalias; | |
2995 | ||
9eaef27b | 2996 | /* See lock_rename() */ |
9eaef27b TM |
2997 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2998 | goto out_err; | |
2999 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
9902af79 | 3000 | if (!inode_trylock_shared(alias->d_parent->d_inode)) |
9eaef27b | 3001 | goto out_err; |
9902af79 | 3002 | m2 = &alias->d_parent->d_inode->i_rwsem; |
9eaef27b | 3003 | out_unalias: |
8ed936b5 | 3004 | __d_move(alias, dentry, false); |
b5ae6b15 | 3005 | ret = 0; |
9eaef27b | 3006 | out_err: |
9eaef27b | 3007 | if (m2) |
9902af79 | 3008 | up_read(m2); |
9eaef27b TM |
3009 | if (m1) |
3010 | mutex_unlock(m1); | |
3011 | return ret; | |
3012 | } | |
3013 | ||
3f70bd51 BF |
3014 | /** |
3015 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
3016 | * @inode: the inode which may have a disconnected dentry | |
3017 | * @dentry: a negative dentry which we want to point to the inode. | |
3018 | * | |
da093a9b BF |
3019 | * If inode is a directory and has an IS_ROOT alias, then d_move that in |
3020 | * place of the given dentry and return it, else simply d_add the inode | |
3021 | * to the dentry and return NULL. | |
3f70bd51 | 3022 | * |
908790fa BF |
3023 | * If a non-IS_ROOT directory is found, the filesystem is corrupt, and |
3024 | * we should error out: directories can't have multiple aliases. | |
3025 | * | |
3f70bd51 BF |
3026 | * This is needed in the lookup routine of any filesystem that is exportable |
3027 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
3028 | * | |
3029 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
3030 | * is returned. This matches the expected return value of ->lookup. | |
3031 | * | |
3032 | * Cluster filesystems may call this function with a negative, hashed dentry. | |
3033 | * In that case, we know that the inode will be a regular file, and also this | |
3034 | * will only occur during atomic_open. So we need to check for the dentry | |
3035 | * being already hashed only in the final case. | |
3036 | */ | |
3037 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
3038 | { | |
3f70bd51 BF |
3039 | if (IS_ERR(inode)) |
3040 | return ERR_CAST(inode); | |
3041 | ||
770bfad8 DH |
3042 | BUG_ON(!d_unhashed(dentry)); |
3043 | ||
de689f5e | 3044 | if (!inode) |
b5ae6b15 | 3045 | goto out; |
de689f5e | 3046 | |
b9680917 | 3047 | security_d_instantiate(dentry, inode); |
873feea0 | 3048 | spin_lock(&inode->i_lock); |
9eaef27b | 3049 | if (S_ISDIR(inode->i_mode)) { |
b5ae6b15 AV |
3050 | struct dentry *new = __d_find_any_alias(inode); |
3051 | if (unlikely(new)) { | |
a03e283b EB |
3052 | /* The reference to new ensures it remains an alias */ |
3053 | spin_unlock(&inode->i_lock); | |
18367501 | 3054 | write_seqlock(&rename_lock); |
b5ae6b15 AV |
3055 | if (unlikely(d_ancestor(new, dentry))) { |
3056 | write_sequnlock(&rename_lock); | |
b5ae6b15 AV |
3057 | dput(new); |
3058 | new = ERR_PTR(-ELOOP); | |
3059 | pr_warn_ratelimited( | |
3060 | "VFS: Lookup of '%s' in %s %s" | |
3061 | " would have caused loop\n", | |
3062 | dentry->d_name.name, | |
3063 | inode->i_sb->s_type->name, | |
3064 | inode->i_sb->s_id); | |
3065 | } else if (!IS_ROOT(new)) { | |
3066 | int err = __d_unalias(inode, dentry, new); | |
18367501 | 3067 | write_sequnlock(&rename_lock); |
b5ae6b15 AV |
3068 | if (err) { |
3069 | dput(new); | |
3070 | new = ERR_PTR(err); | |
3071 | } | |
18367501 | 3072 | } else { |
b5ae6b15 AV |
3073 | __d_move(new, dentry, false); |
3074 | write_sequnlock(&rename_lock); | |
dd179946 | 3075 | } |
b5ae6b15 AV |
3076 | iput(inode); |
3077 | return new; | |
9eaef27b | 3078 | } |
770bfad8 | 3079 | } |
b5ae6b15 | 3080 | out: |
ed782b5a | 3081 | __d_add(dentry, inode); |
b5ae6b15 | 3082 | return NULL; |
770bfad8 | 3083 | } |
b5ae6b15 | 3084 | EXPORT_SYMBOL(d_splice_alias); |
770bfad8 | 3085 | |
cdd16d02 | 3086 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
3087 | { |
3088 | *buflen -= namelen; | |
3089 | if (*buflen < 0) | |
3090 | return -ENAMETOOLONG; | |
3091 | *buffer -= namelen; | |
3092 | memcpy(*buffer, str, namelen); | |
3093 | return 0; | |
3094 | } | |
3095 | ||
232d2d60 WL |
3096 | /** |
3097 | * prepend_name - prepend a pathname in front of current buffer pointer | |
18129977 WL |
3098 | * @buffer: buffer pointer |
3099 | * @buflen: allocated length of the buffer | |
3100 | * @name: name string and length qstr structure | |
232d2d60 WL |
3101 | * |
3102 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to | |
3103 | * make sure that either the old or the new name pointer and length are | |
3104 | * fetched. However, there may be mismatch between length and pointer. | |
3105 | * The length cannot be trusted, we need to copy it byte-by-byte until | |
3106 | * the length is reached or a null byte is found. It also prepends "/" at | |
3107 | * the beginning of the name. The sequence number check at the caller will | |
3108 | * retry it again when a d_move() does happen. So any garbage in the buffer | |
3109 | * due to mismatched pointer and length will be discarded. | |
6d13f694 AV |
3110 | * |
3111 | * Data dependency barrier is needed to make sure that we see that terminating | |
3112 | * NUL. Alpha strikes again, film at 11... | |
232d2d60 | 3113 | */ |
cdd16d02 MS |
3114 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
3115 | { | |
232d2d60 WL |
3116 | const char *dname = ACCESS_ONCE(name->name); |
3117 | u32 dlen = ACCESS_ONCE(name->len); | |
3118 | char *p; | |
3119 | ||
6d13f694 AV |
3120 | smp_read_barrier_depends(); |
3121 | ||
232d2d60 | 3122 | *buflen -= dlen + 1; |
e825196d AV |
3123 | if (*buflen < 0) |
3124 | return -ENAMETOOLONG; | |
232d2d60 WL |
3125 | p = *buffer -= dlen + 1; |
3126 | *p++ = '/'; | |
3127 | while (dlen--) { | |
3128 | char c = *dname++; | |
3129 | if (!c) | |
3130 | break; | |
3131 | *p++ = c; | |
3132 | } | |
3133 | return 0; | |
cdd16d02 MS |
3134 | } |
3135 | ||
1da177e4 | 3136 | /** |
208898c1 | 3137 | * prepend_path - Prepend path string to a buffer |
9d1bc601 | 3138 | * @path: the dentry/vfsmount to report |
02125a82 | 3139 | * @root: root vfsmnt/dentry |
f2eb6575 MS |
3140 | * @buffer: pointer to the end of the buffer |
3141 | * @buflen: pointer to buffer length | |
552ce544 | 3142 | * |
18129977 WL |
3143 | * The function will first try to write out the pathname without taking any |
3144 | * lock other than the RCU read lock to make sure that dentries won't go away. | |
3145 | * It only checks the sequence number of the global rename_lock as any change | |
3146 | * in the dentry's d_seq will be preceded by changes in the rename_lock | |
3147 | * sequence number. If the sequence number had been changed, it will restart | |
3148 | * the whole pathname back-tracing sequence again by taking the rename_lock. | |
3149 | * In this case, there is no need to take the RCU read lock as the recursive | |
3150 | * parent pointer references will keep the dentry chain alive as long as no | |
3151 | * rename operation is performed. | |
1da177e4 | 3152 | */ |
02125a82 AV |
3153 | static int prepend_path(const struct path *path, |
3154 | const struct path *root, | |
f2eb6575 | 3155 | char **buffer, int *buflen) |
1da177e4 | 3156 | { |
ede4cebc AV |
3157 | struct dentry *dentry; |
3158 | struct vfsmount *vfsmnt; | |
3159 | struct mount *mnt; | |
f2eb6575 | 3160 | int error = 0; |
48a066e7 | 3161 | unsigned seq, m_seq = 0; |
232d2d60 WL |
3162 | char *bptr; |
3163 | int blen; | |
6092d048 | 3164 | |
48f5ec21 | 3165 | rcu_read_lock(); |
48a066e7 AV |
3166 | restart_mnt: |
3167 | read_seqbegin_or_lock(&mount_lock, &m_seq); | |
3168 | seq = 0; | |
4ec6c2ae | 3169 | rcu_read_lock(); |
232d2d60 WL |
3170 | restart: |
3171 | bptr = *buffer; | |
3172 | blen = *buflen; | |
48a066e7 | 3173 | error = 0; |
ede4cebc AV |
3174 | dentry = path->dentry; |
3175 | vfsmnt = path->mnt; | |
3176 | mnt = real_mount(vfsmnt); | |
232d2d60 | 3177 | read_seqbegin_or_lock(&rename_lock, &seq); |
f2eb6575 | 3178 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
3179 | struct dentry * parent; |
3180 | ||
1da177e4 | 3181 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
48a066e7 | 3182 | struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); |
cde93be4 EB |
3183 | /* Escaped? */ |
3184 | if (dentry != vfsmnt->mnt_root) { | |
3185 | bptr = *buffer; | |
3186 | blen = *buflen; | |
3187 | error = 3; | |
3188 | break; | |
3189 | } | |
552ce544 | 3190 | /* Global root? */ |
48a066e7 AV |
3191 | if (mnt != parent) { |
3192 | dentry = ACCESS_ONCE(mnt->mnt_mountpoint); | |
3193 | mnt = parent; | |
232d2d60 WL |
3194 | vfsmnt = &mnt->mnt; |
3195 | continue; | |
3196 | } | |
232d2d60 WL |
3197 | if (!error) |
3198 | error = is_mounted(vfsmnt) ? 1 : 2; | |
3199 | break; | |
1da177e4 LT |
3200 | } |
3201 | parent = dentry->d_parent; | |
3202 | prefetch(parent); | |
232d2d60 | 3203 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
f2eb6575 MS |
3204 | if (error) |
3205 | break; | |
3206 | ||
1da177e4 LT |
3207 | dentry = parent; |
3208 | } | |
48f5ec21 AV |
3209 | if (!(seq & 1)) |
3210 | rcu_read_unlock(); | |
3211 | if (need_seqretry(&rename_lock, seq)) { | |
3212 | seq = 1; | |
232d2d60 | 3213 | goto restart; |
48f5ec21 AV |
3214 | } |
3215 | done_seqretry(&rename_lock, seq); | |
4ec6c2ae LZ |
3216 | |
3217 | if (!(m_seq & 1)) | |
3218 | rcu_read_unlock(); | |
48a066e7 AV |
3219 | if (need_seqretry(&mount_lock, m_seq)) { |
3220 | m_seq = 1; | |
3221 | goto restart_mnt; | |
3222 | } | |
3223 | done_seqretry(&mount_lock, m_seq); | |
1da177e4 | 3224 | |
232d2d60 WL |
3225 | if (error >= 0 && bptr == *buffer) { |
3226 | if (--blen < 0) | |
3227 | error = -ENAMETOOLONG; | |
3228 | else | |
3229 | *--bptr = '/'; | |
3230 | } | |
3231 | *buffer = bptr; | |
3232 | *buflen = blen; | |
7ea600b5 | 3233 | return error; |
f2eb6575 | 3234 | } |
be285c71 | 3235 | |
f2eb6575 MS |
3236 | /** |
3237 | * __d_path - return the path of a dentry | |
3238 | * @path: the dentry/vfsmount to report | |
02125a82 | 3239 | * @root: root vfsmnt/dentry |
cd956a1c | 3240 | * @buf: buffer to return value in |
f2eb6575 MS |
3241 | * @buflen: buffer length |
3242 | * | |
ffd1f4ed | 3243 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
3244 | * |
3245 | * Returns a pointer into the buffer or an error code if the | |
3246 | * path was too long. | |
3247 | * | |
be148247 | 3248 | * "buflen" should be positive. |
f2eb6575 | 3249 | * |
02125a82 | 3250 | * If the path is not reachable from the supplied root, return %NULL. |
f2eb6575 | 3251 | */ |
02125a82 AV |
3252 | char *__d_path(const struct path *path, |
3253 | const struct path *root, | |
f2eb6575 MS |
3254 | char *buf, int buflen) |
3255 | { | |
3256 | char *res = buf + buflen; | |
3257 | int error; | |
3258 | ||
3259 | prepend(&res, &buflen, "\0", 1); | |
f2eb6575 | 3260 | error = prepend_path(path, root, &res, &buflen); |
be148247 | 3261 | |
02125a82 AV |
3262 | if (error < 0) |
3263 | return ERR_PTR(error); | |
3264 | if (error > 0) | |
3265 | return NULL; | |
3266 | return res; | |
3267 | } | |
3268 | ||
3269 | char *d_absolute_path(const struct path *path, | |
3270 | char *buf, int buflen) | |
3271 | { | |
3272 | struct path root = {}; | |
3273 | char *res = buf + buflen; | |
3274 | int error; | |
3275 | ||
3276 | prepend(&res, &buflen, "\0", 1); | |
02125a82 | 3277 | error = prepend_path(path, &root, &res, &buflen); |
02125a82 AV |
3278 | |
3279 | if (error > 1) | |
3280 | error = -EINVAL; | |
3281 | if (error < 0) | |
f2eb6575 | 3282 | return ERR_PTR(error); |
f2eb6575 | 3283 | return res; |
1da177e4 LT |
3284 | } |
3285 | ||
ffd1f4ed MS |
3286 | /* |
3287 | * same as __d_path but appends "(deleted)" for unlinked files. | |
3288 | */ | |
02125a82 AV |
3289 | static int path_with_deleted(const struct path *path, |
3290 | const struct path *root, | |
3291 | char **buf, int *buflen) | |
ffd1f4ed MS |
3292 | { |
3293 | prepend(buf, buflen, "\0", 1); | |
3294 | if (d_unlinked(path->dentry)) { | |
3295 | int error = prepend(buf, buflen, " (deleted)", 10); | |
3296 | if (error) | |
3297 | return error; | |
3298 | } | |
3299 | ||
3300 | return prepend_path(path, root, buf, buflen); | |
3301 | } | |
3302 | ||
8df9d1a4 MS |
3303 | static int prepend_unreachable(char **buffer, int *buflen) |
3304 | { | |
3305 | return prepend(buffer, buflen, "(unreachable)", 13); | |
3306 | } | |
3307 | ||
68f0d9d9 LT |
3308 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
3309 | { | |
3310 | unsigned seq; | |
3311 | ||
3312 | do { | |
3313 | seq = read_seqcount_begin(&fs->seq); | |
3314 | *root = fs->root; | |
3315 | } while (read_seqcount_retry(&fs->seq, seq)); | |
3316 | } | |
3317 | ||
a03a8a70 JB |
3318 | /** |
3319 | * d_path - return the path of a dentry | |
cf28b486 | 3320 | * @path: path to report |
a03a8a70 JB |
3321 | * @buf: buffer to return value in |
3322 | * @buflen: buffer length | |
3323 | * | |
3324 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
3325 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
3326 | * | |
52afeefb AV |
3327 | * Returns a pointer into the buffer or an error code if the path was |
3328 | * too long. Note: Callers should use the returned pointer, not the passed | |
3329 | * in buffer, to use the name! The implementation often starts at an offset | |
3330 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 3331 | * |
31f3e0b3 | 3332 | * "buflen" should be positive. |
a03a8a70 | 3333 | */ |
20d4fdc1 | 3334 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 3335 | { |
ffd1f4ed | 3336 | char *res = buf + buflen; |
6ac08c39 | 3337 | struct path root; |
ffd1f4ed | 3338 | int error; |
1da177e4 | 3339 | |
c23fbb6b ED |
3340 | /* |
3341 | * We have various synthetic filesystems that never get mounted. On | |
3342 | * these filesystems dentries are never used for lookup purposes, and | |
3343 | * thus don't need to be hashed. They also don't need a name until a | |
3344 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
3345 | * below allows us to generate a name for these objects on demand: | |
f48cfddc EB |
3346 | * |
3347 | * Some pseudo inodes are mountable. When they are mounted | |
3348 | * path->dentry == path->mnt->mnt_root. In that case don't call d_dname | |
3349 | * and instead have d_path return the mounted path. | |
c23fbb6b | 3350 | */ |
f48cfddc EB |
3351 | if (path->dentry->d_op && path->dentry->d_op->d_dname && |
3352 | (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root)) | |
cf28b486 | 3353 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
c23fbb6b | 3354 | |
68f0d9d9 LT |
3355 | rcu_read_lock(); |
3356 | get_fs_root_rcu(current->fs, &root); | |
02125a82 | 3357 | error = path_with_deleted(path, &root, &res, &buflen); |
68f0d9d9 LT |
3358 | rcu_read_unlock(); |
3359 | ||
02125a82 | 3360 | if (error < 0) |
ffd1f4ed | 3361 | res = ERR_PTR(error); |
1da177e4 LT |
3362 | return res; |
3363 | } | |
ec4f8605 | 3364 | EXPORT_SYMBOL(d_path); |
1da177e4 | 3365 | |
c23fbb6b ED |
3366 | /* |
3367 | * Helper function for dentry_operations.d_dname() members | |
3368 | */ | |
3369 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
3370 | const char *fmt, ...) | |
3371 | { | |
3372 | va_list args; | |
3373 | char temp[64]; | |
3374 | int sz; | |
3375 | ||
3376 | va_start(args, fmt); | |
3377 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
3378 | va_end(args); | |
3379 | ||
3380 | if (sz > sizeof(temp) || sz > buflen) | |
3381 | return ERR_PTR(-ENAMETOOLONG); | |
3382 | ||
3383 | buffer += buflen - sz; | |
3384 | return memcpy(buffer, temp, sz); | |
3385 | } | |
3386 | ||
118b2302 AV |
3387 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
3388 | { | |
3389 | char *end = buffer + buflen; | |
3390 | /* these dentries are never renamed, so d_lock is not needed */ | |
3391 | if (prepend(&end, &buflen, " (deleted)", 11) || | |
232d2d60 | 3392 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
118b2302 AV |
3393 | prepend(&end, &buflen, "/", 1)) |
3394 | end = ERR_PTR(-ENAMETOOLONG); | |
232d2d60 | 3395 | return end; |
118b2302 | 3396 | } |
31bbe16f | 3397 | EXPORT_SYMBOL(simple_dname); |
118b2302 | 3398 | |
6092d048 RP |
3399 | /* |
3400 | * Write full pathname from the root of the filesystem into the buffer. | |
3401 | */ | |
f6500801 | 3402 | static char *__dentry_path(struct dentry *d, char *buf, int buflen) |
6092d048 | 3403 | { |
f6500801 | 3404 | struct dentry *dentry; |
232d2d60 WL |
3405 | char *end, *retval; |
3406 | int len, seq = 0; | |
3407 | int error = 0; | |
6092d048 | 3408 | |
f6500801 AV |
3409 | if (buflen < 2) |
3410 | goto Elong; | |
3411 | ||
48f5ec21 | 3412 | rcu_read_lock(); |
232d2d60 | 3413 | restart: |
f6500801 | 3414 | dentry = d; |
232d2d60 WL |
3415 | end = buf + buflen; |
3416 | len = buflen; | |
3417 | prepend(&end, &len, "\0", 1); | |
6092d048 RP |
3418 | /* Get '/' right */ |
3419 | retval = end-1; | |
3420 | *retval = '/'; | |
232d2d60 | 3421 | read_seqbegin_or_lock(&rename_lock, &seq); |
cdd16d02 MS |
3422 | while (!IS_ROOT(dentry)) { |
3423 | struct dentry *parent = dentry->d_parent; | |
6092d048 | 3424 | |
6092d048 | 3425 | prefetch(parent); |
232d2d60 WL |
3426 | error = prepend_name(&end, &len, &dentry->d_name); |
3427 | if (error) | |
3428 | break; | |
6092d048 RP |
3429 | |
3430 | retval = end; | |
3431 | dentry = parent; | |
3432 | } | |
48f5ec21 AV |
3433 | if (!(seq & 1)) |
3434 | rcu_read_unlock(); | |
3435 | if (need_seqretry(&rename_lock, seq)) { | |
3436 | seq = 1; | |
232d2d60 | 3437 | goto restart; |
48f5ec21 AV |
3438 | } |
3439 | done_seqretry(&rename_lock, seq); | |
232d2d60 WL |
3440 | if (error) |
3441 | goto Elong; | |
c103135c AV |
3442 | return retval; |
3443 | Elong: | |
3444 | return ERR_PTR(-ENAMETOOLONG); | |
3445 | } | |
ec2447c2 NP |
3446 | |
3447 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
3448 | { | |
232d2d60 | 3449 | return __dentry_path(dentry, buf, buflen); |
ec2447c2 NP |
3450 | } |
3451 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
3452 | |
3453 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
3454 | { | |
3455 | char *p = NULL; | |
3456 | char *retval; | |
3457 | ||
c103135c AV |
3458 | if (d_unlinked(dentry)) { |
3459 | p = buf + buflen; | |
3460 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
3461 | goto Elong; | |
3462 | buflen++; | |
3463 | } | |
3464 | retval = __dentry_path(dentry, buf, buflen); | |
c103135c AV |
3465 | if (!IS_ERR(retval) && p) |
3466 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
3467 | return retval; |
3468 | Elong: | |
6092d048 RP |
3469 | return ERR_PTR(-ENAMETOOLONG); |
3470 | } | |
3471 | ||
8b19e341 LT |
3472 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
3473 | struct path *pwd) | |
5762482f | 3474 | { |
8b19e341 LT |
3475 | unsigned seq; |
3476 | ||
3477 | do { | |
3478 | seq = read_seqcount_begin(&fs->seq); | |
3479 | *root = fs->root; | |
3480 | *pwd = fs->pwd; | |
3481 | } while (read_seqcount_retry(&fs->seq, seq)); | |
5762482f LT |
3482 | } |
3483 | ||
1da177e4 LT |
3484 | /* |
3485 | * NOTE! The user-level library version returns a | |
3486 | * character pointer. The kernel system call just | |
3487 | * returns the length of the buffer filled (which | |
3488 | * includes the ending '\0' character), or a negative | |
3489 | * error value. So libc would do something like | |
3490 | * | |
3491 | * char *getcwd(char * buf, size_t size) | |
3492 | * { | |
3493 | * int retval; | |
3494 | * | |
3495 | * retval = sys_getcwd(buf, size); | |
3496 | * if (retval >= 0) | |
3497 | * return buf; | |
3498 | * errno = -retval; | |
3499 | * return NULL; | |
3500 | * } | |
3501 | */ | |
3cdad428 | 3502 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 3503 | { |
552ce544 | 3504 | int error; |
6ac08c39 | 3505 | struct path pwd, root; |
3272c544 | 3506 | char *page = __getname(); |
1da177e4 LT |
3507 | |
3508 | if (!page) | |
3509 | return -ENOMEM; | |
3510 | ||
8b19e341 LT |
3511 | rcu_read_lock(); |
3512 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); | |
1da177e4 | 3513 | |
552ce544 | 3514 | error = -ENOENT; |
f3da392e | 3515 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 3516 | unsigned long len; |
3272c544 LT |
3517 | char *cwd = page + PATH_MAX; |
3518 | int buflen = PATH_MAX; | |
1da177e4 | 3519 | |
8df9d1a4 | 3520 | prepend(&cwd, &buflen, "\0", 1); |
02125a82 | 3521 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
ff812d72 | 3522 | rcu_read_unlock(); |
552ce544 | 3523 | |
02125a82 | 3524 | if (error < 0) |
552ce544 LT |
3525 | goto out; |
3526 | ||
8df9d1a4 | 3527 | /* Unreachable from current root */ |
02125a82 | 3528 | if (error > 0) { |
8df9d1a4 MS |
3529 | error = prepend_unreachable(&cwd, &buflen); |
3530 | if (error) | |
3531 | goto out; | |
3532 | } | |
3533 | ||
552ce544 | 3534 | error = -ERANGE; |
3272c544 | 3535 | len = PATH_MAX + page - cwd; |
552ce544 LT |
3536 | if (len <= size) { |
3537 | error = len; | |
3538 | if (copy_to_user(buf, cwd, len)) | |
3539 | error = -EFAULT; | |
3540 | } | |
949854d0 | 3541 | } else { |
ff812d72 | 3542 | rcu_read_unlock(); |
949854d0 | 3543 | } |
1da177e4 LT |
3544 | |
3545 | out: | |
3272c544 | 3546 | __putname(page); |
1da177e4 LT |
3547 | return error; |
3548 | } | |
3549 | ||
3550 | /* | |
3551 | * Test whether new_dentry is a subdirectory of old_dentry. | |
3552 | * | |
3553 | * Trivially implemented using the dcache structure | |
3554 | */ | |
3555 | ||
3556 | /** | |
3557 | * is_subdir - is new dentry a subdirectory of old_dentry | |
3558 | * @new_dentry: new dentry | |
3559 | * @old_dentry: old dentry | |
3560 | * | |
a6e5787f YB |
3561 | * Returns true if new_dentry is a subdirectory of the parent (at any depth). |
3562 | * Returns false otherwise. | |
1da177e4 LT |
3563 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
3564 | */ | |
3565 | ||
a6e5787f | 3566 | bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 | 3567 | { |
a6e5787f | 3568 | bool result; |
949854d0 | 3569 | unsigned seq; |
1da177e4 | 3570 | |
e2761a11 | 3571 | if (new_dentry == old_dentry) |
a6e5787f | 3572 | return true; |
e2761a11 | 3573 | |
e2761a11 | 3574 | do { |
1da177e4 | 3575 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 3576 | seq = read_seqbegin(&rename_lock); |
949854d0 NP |
3577 | /* |
3578 | * Need rcu_readlock to protect against the d_parent trashing | |
3579 | * due to d_move | |
3580 | */ | |
3581 | rcu_read_lock(); | |
e2761a11 | 3582 | if (d_ancestor(old_dentry, new_dentry)) |
a6e5787f | 3583 | result = true; |
e2761a11 | 3584 | else |
a6e5787f | 3585 | result = false; |
949854d0 | 3586 | rcu_read_unlock(); |
1da177e4 | 3587 | } while (read_seqretry(&rename_lock, seq)); |
1da177e4 LT |
3588 | |
3589 | return result; | |
3590 | } | |
3591 | ||
db14fc3a | 3592 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
1da177e4 | 3593 | { |
db14fc3a MS |
3594 | struct dentry *root = data; |
3595 | if (dentry != root) { | |
3596 | if (d_unhashed(dentry) || !dentry->d_inode) | |
3597 | return D_WALK_SKIP; | |
1da177e4 | 3598 | |
01ddc4ed MS |
3599 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
3600 | dentry->d_flags |= DCACHE_GENOCIDE; | |
3601 | dentry->d_lockref.count--; | |
3602 | } | |
1da177e4 | 3603 | } |
db14fc3a MS |
3604 | return D_WALK_CONTINUE; |
3605 | } | |
58db63d0 | 3606 | |
db14fc3a MS |
3607 | void d_genocide(struct dentry *parent) |
3608 | { | |
3609 | d_walk(parent, parent, d_genocide_kill, NULL); | |
1da177e4 LT |
3610 | } |
3611 | ||
60545d0d | 3612 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
1da177e4 | 3613 | { |
60545d0d AV |
3614 | inode_dec_link_count(inode); |
3615 | BUG_ON(dentry->d_name.name != dentry->d_iname || | |
946e51f2 | 3616 | !hlist_unhashed(&dentry->d_u.d_alias) || |
60545d0d AV |
3617 | !d_unlinked(dentry)); |
3618 | spin_lock(&dentry->d_parent->d_lock); | |
3619 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
3620 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", | |
3621 | (unsigned long long)inode->i_ino); | |
3622 | spin_unlock(&dentry->d_lock); | |
3623 | spin_unlock(&dentry->d_parent->d_lock); | |
3624 | d_instantiate(dentry, inode); | |
1da177e4 | 3625 | } |
60545d0d | 3626 | EXPORT_SYMBOL(d_tmpfile); |
1da177e4 LT |
3627 | |
3628 | static __initdata unsigned long dhash_entries; | |
3629 | static int __init set_dhash_entries(char *str) | |
3630 | { | |
3631 | if (!str) | |
3632 | return 0; | |
3633 | dhash_entries = simple_strtoul(str, &str, 0); | |
3634 | return 1; | |
3635 | } | |
3636 | __setup("dhash_entries=", set_dhash_entries); | |
3637 | ||
3638 | static void __init dcache_init_early(void) | |
3639 | { | |
074b8517 | 3640 | unsigned int loop; |
1da177e4 LT |
3641 | |
3642 | /* If hashes are distributed across NUMA nodes, defer | |
3643 | * hash allocation until vmalloc space is available. | |
3644 | */ | |
3645 | if (hashdist) | |
3646 | return; | |
3647 | ||
3648 | dentry_hashtable = | |
3649 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3650 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3651 | dhash_entries, |
3652 | 13, | |
3653 | HASH_EARLY, | |
3654 | &d_hash_shift, | |
3655 | &d_hash_mask, | |
31fe62b9 | 3656 | 0, |
1da177e4 LT |
3657 | 0); |
3658 | ||
074b8517 | 3659 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3660 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3661 | } |
3662 | ||
74bf17cf | 3663 | static void __init dcache_init(void) |
1da177e4 | 3664 | { |
074b8517 | 3665 | unsigned int loop; |
1da177e4 LT |
3666 | |
3667 | /* | |
3668 | * A constructor could be added for stable state like the lists, | |
3669 | * but it is probably not worth it because of the cache nature | |
3670 | * of the dcache. | |
3671 | */ | |
0a31bd5f | 3672 | dentry_cache = KMEM_CACHE(dentry, |
5d097056 | 3673 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT); |
1da177e4 LT |
3674 | |
3675 | /* Hash may have been set up in dcache_init_early */ | |
3676 | if (!hashdist) | |
3677 | return; | |
3678 | ||
3679 | dentry_hashtable = | |
3680 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3681 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3682 | dhash_entries, |
3683 | 13, | |
3684 | 0, | |
3685 | &d_hash_shift, | |
3686 | &d_hash_mask, | |
31fe62b9 | 3687 | 0, |
1da177e4 LT |
3688 | 0); |
3689 | ||
074b8517 | 3690 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3691 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3692 | } |
3693 | ||
3694 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 3695 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 3696 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 3697 | |
1da177e4 LT |
3698 | EXPORT_SYMBOL(d_genocide); |
3699 | ||
1da177e4 LT |
3700 | void __init vfs_caches_init_early(void) |
3701 | { | |
3702 | dcache_init_early(); | |
3703 | inode_init_early(); | |
3704 | } | |
3705 | ||
4248b0da | 3706 | void __init vfs_caches_init(void) |
1da177e4 | 3707 | { |
1da177e4 | 3708 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
20c2df83 | 3709 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 3710 | |
74bf17cf DC |
3711 | dcache_init(); |
3712 | inode_init(); | |
4248b0da MG |
3713 | files_init(); |
3714 | files_maxfiles_init(); | |
74bf17cf | 3715 | mnt_init(); |
1da177e4 LT |
3716 | bdev_cache_init(); |
3717 | chrdev_init(); | |
3718 | } |