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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 | |
8387ff25 | 107 | static inline struct hlist_bl_head *d_hash(unsigned int hash) |
ceb5bdc2 | 108 | { |
703b5faf | 109 | return dentry_hashtable + (hash >> (32 - d_hash_shift)); |
ceb5bdc2 NP |
110 | } |
111 | ||
94bdd655 AV |
112 | #define IN_LOOKUP_SHIFT 10 |
113 | static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT]; | |
114 | ||
115 | static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent, | |
116 | unsigned int hash) | |
117 | { | |
118 | hash += (unsigned long) parent / L1_CACHE_BYTES; | |
119 | return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT); | |
120 | } | |
121 | ||
122 | ||
1da177e4 LT |
123 | /* Statistics gathering. */ |
124 | struct dentry_stat_t dentry_stat = { | |
125 | .age_limit = 45, | |
126 | }; | |
127 | ||
3942c07c | 128 | static DEFINE_PER_CPU(long, nr_dentry); |
62d36c77 | 129 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
312d3ca8 CH |
130 | |
131 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
62d36c77 DC |
132 | |
133 | /* | |
134 | * Here we resort to our own counters instead of using generic per-cpu counters | |
135 | * for consistency with what the vfs inode code does. We are expected to harvest | |
136 | * better code and performance by having our own specialized counters. | |
137 | * | |
138 | * Please note that the loop is done over all possible CPUs, not over all online | |
139 | * CPUs. The reason for this is that we don't want to play games with CPUs going | |
140 | * on and off. If one of them goes off, we will just keep their counters. | |
141 | * | |
142 | * glommer: See cffbc8a for details, and if you ever intend to change this, | |
143 | * please update all vfs counters to match. | |
144 | */ | |
3942c07c | 145 | static long get_nr_dentry(void) |
3e880fb5 NP |
146 | { |
147 | int i; | |
3942c07c | 148 | long sum = 0; |
3e880fb5 NP |
149 | for_each_possible_cpu(i) |
150 | sum += per_cpu(nr_dentry, i); | |
151 | return sum < 0 ? 0 : sum; | |
152 | } | |
153 | ||
62d36c77 DC |
154 | static long get_nr_dentry_unused(void) |
155 | { | |
156 | int i; | |
157 | long sum = 0; | |
158 | for_each_possible_cpu(i) | |
159 | sum += per_cpu(nr_dentry_unused, i); | |
160 | return sum < 0 ? 0 : sum; | |
161 | } | |
162 | ||
1f7e0616 | 163 | int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer, |
312d3ca8 CH |
164 | size_t *lenp, loff_t *ppos) |
165 | { | |
3e880fb5 | 166 | dentry_stat.nr_dentry = get_nr_dentry(); |
62d36c77 | 167 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
3942c07c | 168 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
312d3ca8 CH |
169 | } |
170 | #endif | |
171 | ||
5483f18e LT |
172 | /* |
173 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. | |
174 | * The strings are both count bytes long, and count is non-zero. | |
175 | */ | |
e419b4cc LT |
176 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
177 | ||
178 | #include <asm/word-at-a-time.h> | |
179 | /* | |
180 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a | |
181 | * aligned allocation for this particular component. We don't | |
182 | * strictly need the load_unaligned_zeropad() safety, but it | |
183 | * doesn't hurt either. | |
184 | * | |
185 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do | |
186 | * need the careful unaligned handling. | |
187 | */ | |
94753db5 | 188 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
5483f18e | 189 | { |
bfcfaa77 | 190 | unsigned long a,b,mask; |
bfcfaa77 LT |
191 | |
192 | for (;;) { | |
12f8ad4b | 193 | a = *(unsigned long *)cs; |
e419b4cc | 194 | b = load_unaligned_zeropad(ct); |
bfcfaa77 LT |
195 | if (tcount < sizeof(unsigned long)) |
196 | break; | |
197 | if (unlikely(a != b)) | |
198 | return 1; | |
199 | cs += sizeof(unsigned long); | |
200 | ct += sizeof(unsigned long); | |
201 | tcount -= sizeof(unsigned long); | |
202 | if (!tcount) | |
203 | return 0; | |
204 | } | |
a5c21dce | 205 | mask = bytemask_from_count(tcount); |
bfcfaa77 | 206 | return unlikely(!!((a ^ b) & mask)); |
e419b4cc LT |
207 | } |
208 | ||
bfcfaa77 | 209 | #else |
e419b4cc | 210 | |
94753db5 | 211 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
e419b4cc | 212 | { |
5483f18e LT |
213 | do { |
214 | if (*cs != *ct) | |
215 | return 1; | |
216 | cs++; | |
217 | ct++; | |
218 | tcount--; | |
219 | } while (tcount); | |
220 | return 0; | |
221 | } | |
222 | ||
e419b4cc LT |
223 | #endif |
224 | ||
94753db5 LT |
225 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
226 | { | |
94753db5 LT |
227 | /* |
228 | * Be careful about RCU walk racing with rename: | |
ae0a843c | 229 | * use 'lockless_dereference' to fetch the name pointer. |
94753db5 LT |
230 | * |
231 | * NOTE! Even if a rename will mean that the length | |
232 | * was not loaded atomically, we don't care. The | |
233 | * RCU walk will check the sequence count eventually, | |
234 | * and catch it. And we won't overrun the buffer, | |
235 | * because we're reading the name pointer atomically, | |
236 | * and a dentry name is guaranteed to be properly | |
237 | * terminated with a NUL byte. | |
238 | * | |
239 | * End result: even if 'len' is wrong, we'll exit | |
240 | * early because the data cannot match (there can | |
241 | * be no NUL in the ct/tcount data) | |
242 | */ | |
ae0a843c HK |
243 | const unsigned char *cs = lockless_dereference(dentry->d_name.name); |
244 | ||
6326c71f | 245 | return dentry_string_cmp(cs, ct, tcount); |
94753db5 LT |
246 | } |
247 | ||
8d85b484 AV |
248 | struct external_name { |
249 | union { | |
250 | atomic_t count; | |
251 | struct rcu_head head; | |
252 | } u; | |
253 | unsigned char name[]; | |
254 | }; | |
255 | ||
256 | static inline struct external_name *external_name(struct dentry *dentry) | |
257 | { | |
258 | return container_of(dentry->d_name.name, struct external_name, name[0]); | |
259 | } | |
260 | ||
9c82ab9c | 261 | static void __d_free(struct rcu_head *head) |
1da177e4 | 262 | { |
9c82ab9c CH |
263 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
264 | ||
8d85b484 AV |
265 | kmem_cache_free(dentry_cache, dentry); |
266 | } | |
267 | ||
268 | static void __d_free_external(struct rcu_head *head) | |
269 | { | |
270 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); | |
8d85b484 | 271 | kfree(external_name(dentry)); |
1da177e4 LT |
272 | kmem_cache_free(dentry_cache, dentry); |
273 | } | |
274 | ||
810bb172 AV |
275 | static inline int dname_external(const struct dentry *dentry) |
276 | { | |
277 | return dentry->d_name.name != dentry->d_iname; | |
278 | } | |
279 | ||
ad25f11e AV |
280 | void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry) |
281 | { | |
282 | spin_lock(&dentry->d_lock); | |
283 | if (unlikely(dname_external(dentry))) { | |
284 | struct external_name *p = external_name(dentry); | |
285 | atomic_inc(&p->u.count); | |
286 | spin_unlock(&dentry->d_lock); | |
287 | name->name = p->name; | |
288 | } else { | |
fc2afa80 TH |
289 | memcpy(name->inline_name, dentry->d_iname, |
290 | dentry->d_name.len + 1); | |
ad25f11e AV |
291 | spin_unlock(&dentry->d_lock); |
292 | name->name = name->inline_name; | |
293 | } | |
294 | } | |
295 | EXPORT_SYMBOL(take_dentry_name_snapshot); | |
296 | ||
297 | void release_dentry_name_snapshot(struct name_snapshot *name) | |
298 | { | |
299 | if (unlikely(name->name != name->inline_name)) { | |
300 | struct external_name *p; | |
301 | p = container_of(name->name, struct external_name, name[0]); | |
302 | if (unlikely(atomic_dec_and_test(&p->u.count))) | |
303 | kfree_rcu(p, u.head); | |
304 | } | |
305 | } | |
306 | EXPORT_SYMBOL(release_dentry_name_snapshot); | |
307 | ||
4bf46a27 DH |
308 | static inline void __d_set_inode_and_type(struct dentry *dentry, |
309 | struct inode *inode, | |
310 | unsigned type_flags) | |
311 | { | |
312 | unsigned flags; | |
313 | ||
314 | dentry->d_inode = inode; | |
4bf46a27 DH |
315 | flags = READ_ONCE(dentry->d_flags); |
316 | flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); | |
317 | flags |= type_flags; | |
318 | WRITE_ONCE(dentry->d_flags, flags); | |
319 | } | |
320 | ||
4bf46a27 DH |
321 | static inline void __d_clear_type_and_inode(struct dentry *dentry) |
322 | { | |
323 | unsigned flags = READ_ONCE(dentry->d_flags); | |
324 | ||
325 | flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); | |
326 | WRITE_ONCE(dentry->d_flags, flags); | |
4bf46a27 DH |
327 | dentry->d_inode = NULL; |
328 | } | |
329 | ||
b4f0354e AV |
330 | static void dentry_free(struct dentry *dentry) |
331 | { | |
946e51f2 | 332 | WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias)); |
8d85b484 AV |
333 | if (unlikely(dname_external(dentry))) { |
334 | struct external_name *p = external_name(dentry); | |
335 | if (likely(atomic_dec_and_test(&p->u.count))) { | |
336 | call_rcu(&dentry->d_u.d_rcu, __d_free_external); | |
337 | return; | |
338 | } | |
339 | } | |
b4f0354e AV |
340 | /* if dentry was never visible to RCU, immediate free is OK */ |
341 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) | |
342 | __d_free(&dentry->d_u.d_rcu); | |
343 | else | |
344 | call_rcu(&dentry->d_u.d_rcu, __d_free); | |
345 | } | |
346 | ||
1da177e4 LT |
347 | /* |
348 | * Release the dentry's inode, using the filesystem | |
550dce01 | 349 | * d_iput() operation if defined. |
31e6b01f NP |
350 | */ |
351 | static void dentry_unlink_inode(struct dentry * dentry) | |
352 | __releases(dentry->d_lock) | |
873feea0 | 353 | __releases(dentry->d_inode->i_lock) |
31e6b01f NP |
354 | { |
355 | struct inode *inode = dentry->d_inode; | |
a528aca7 | 356 | |
59199c04 | 357 | raw_write_seqcount_begin(&dentry->d_seq); |
4bf46a27 | 358 | __d_clear_type_and_inode(dentry); |
946e51f2 | 359 | hlist_del_init(&dentry->d_u.d_alias); |
59199c04 | 360 | raw_write_seqcount_end(&dentry->d_seq); |
31e6b01f | 361 | spin_unlock(&dentry->d_lock); |
873feea0 | 362 | spin_unlock(&inode->i_lock); |
31e6b01f NP |
363 | if (!inode->i_nlink) |
364 | fsnotify_inoderemove(inode); | |
365 | if (dentry->d_op && dentry->d_op->d_iput) | |
366 | dentry->d_op->d_iput(dentry, inode); | |
367 | else | |
368 | iput(inode); | |
369 | } | |
370 | ||
89dc77bc LT |
371 | /* |
372 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry | |
373 | * is in use - which includes both the "real" per-superblock | |
374 | * LRU list _and_ the DCACHE_SHRINK_LIST use. | |
375 | * | |
376 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is | |
377 | * on the shrink list (ie not on the superblock LRU list). | |
378 | * | |
379 | * The per-cpu "nr_dentry_unused" counters are updated with | |
380 | * the DCACHE_LRU_LIST bit. | |
381 | * | |
382 | * These helper functions make sure we always follow the | |
383 | * rules. d_lock must be held by the caller. | |
384 | */ | |
385 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) | |
386 | static void d_lru_add(struct dentry *dentry) | |
387 | { | |
388 | D_FLAG_VERIFY(dentry, 0); | |
389 | dentry->d_flags |= DCACHE_LRU_LIST; | |
390 | this_cpu_inc(nr_dentry_unused); | |
391 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
392 | } | |
393 | ||
394 | static void d_lru_del(struct dentry *dentry) | |
395 | { | |
396 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
397 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
398 | this_cpu_dec(nr_dentry_unused); | |
399 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); | |
400 | } | |
401 | ||
402 | static void d_shrink_del(struct dentry *dentry) | |
403 | { | |
404 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
405 | list_del_init(&dentry->d_lru); | |
406 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); | |
407 | this_cpu_dec(nr_dentry_unused); | |
408 | } | |
409 | ||
410 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) | |
411 | { | |
412 | D_FLAG_VERIFY(dentry, 0); | |
413 | list_add(&dentry->d_lru, list); | |
414 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; | |
415 | this_cpu_inc(nr_dentry_unused); | |
416 | } | |
417 | ||
418 | /* | |
419 | * These can only be called under the global LRU lock, ie during the | |
420 | * callback for freeing the LRU list. "isolate" removes it from the | |
421 | * LRU lists entirely, while shrink_move moves it to the indicated | |
422 | * private list. | |
423 | */ | |
3f97b163 | 424 | static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry) |
89dc77bc LT |
425 | { |
426 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
427 | dentry->d_flags &= ~DCACHE_LRU_LIST; | |
428 | this_cpu_dec(nr_dentry_unused); | |
3f97b163 | 429 | list_lru_isolate(lru, &dentry->d_lru); |
89dc77bc LT |
430 | } |
431 | ||
3f97b163 VD |
432 | static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry, |
433 | struct list_head *list) | |
89dc77bc LT |
434 | { |
435 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); | |
436 | dentry->d_flags |= DCACHE_SHRINK_LIST; | |
3f97b163 | 437 | list_lru_isolate_move(lru, &dentry->d_lru, list); |
89dc77bc LT |
438 | } |
439 | ||
da3bbdd4 | 440 | /* |
f6041567 | 441 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
da3bbdd4 KM |
442 | */ |
443 | static void dentry_lru_add(struct dentry *dentry) | |
444 | { | |
89dc77bc LT |
445 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
446 | d_lru_add(dentry); | |
da3bbdd4 KM |
447 | } |
448 | ||
789680d1 NP |
449 | /** |
450 | * d_drop - drop a dentry | |
451 | * @dentry: dentry to drop | |
452 | * | |
453 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
454 | * be found through a VFS lookup any more. Note that this is different from | |
455 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
456 | * possible, giving a successful _negative_ lookup, while d_drop will | |
457 | * just make the cache lookup fail. | |
458 | * | |
459 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
460 | * reason (NFS timeouts or autofs deletes). | |
461 | * | |
3aa66ba5 N |
462 | * __d_drop requires dentry->d_lock |
463 | * ___d_drop doesn't mark dentry as "unhashed" | |
464 | * (dentry->d_hash.pprev will be LIST_POISON2, not NULL). | |
789680d1 | 465 | */ |
3aa66ba5 | 466 | static void ___d_drop(struct dentry *dentry) |
789680d1 | 467 | { |
dea3667b | 468 | if (!d_unhashed(dentry)) { |
b61625d2 | 469 | struct hlist_bl_head *b; |
7632e465 BF |
470 | /* |
471 | * Hashed dentries are normally on the dentry hashtable, | |
472 | * with the exception of those newly allocated by | |
473 | * d_obtain_alias, which are always IS_ROOT: | |
474 | */ | |
475 | if (unlikely(IS_ROOT(dentry))) | |
b61625d2 AV |
476 | b = &dentry->d_sb->s_anon; |
477 | else | |
8387ff25 | 478 | b = d_hash(dentry->d_name.hash); |
b61625d2 AV |
479 | |
480 | hlist_bl_lock(b); | |
481 | __hlist_bl_del(&dentry->d_hash); | |
b61625d2 | 482 | hlist_bl_unlock(b); |
d614146d AV |
483 | /* After this call, in-progress rcu-walk path lookup will fail. */ |
484 | write_seqcount_invalidate(&dentry->d_seq); | |
789680d1 NP |
485 | } |
486 | } | |
3aa66ba5 N |
487 | |
488 | void __d_drop(struct dentry *dentry) | |
489 | { | |
490 | ___d_drop(dentry); | |
491 | dentry->d_hash.pprev = NULL; | |
492 | } | |
789680d1 NP |
493 | EXPORT_SYMBOL(__d_drop); |
494 | ||
495 | void d_drop(struct dentry *dentry) | |
496 | { | |
789680d1 NP |
497 | spin_lock(&dentry->d_lock); |
498 | __d_drop(dentry); | |
499 | spin_unlock(&dentry->d_lock); | |
789680d1 NP |
500 | } |
501 | EXPORT_SYMBOL(d_drop); | |
502 | ||
ba65dc5e AV |
503 | static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) |
504 | { | |
505 | struct dentry *next; | |
506 | /* | |
507 | * Inform d_walk() and shrink_dentry_list() that we are no longer | |
508 | * attached to the dentry tree | |
509 | */ | |
510 | dentry->d_flags |= DCACHE_DENTRY_KILLED; | |
511 | if (unlikely(list_empty(&dentry->d_child))) | |
512 | return; | |
513 | __list_del_entry(&dentry->d_child); | |
514 | /* | |
515 | * Cursors can move around the list of children. While we'd been | |
516 | * a normal list member, it didn't matter - ->d_child.next would've | |
517 | * been updated. However, from now on it won't be and for the | |
518 | * things like d_walk() it might end up with a nasty surprise. | |
519 | * Normally d_walk() doesn't care about cursors moving around - | |
520 | * ->d_lock on parent prevents that and since a cursor has no children | |
521 | * of its own, we get through it without ever unlocking the parent. | |
522 | * There is one exception, though - if we ascend from a child that | |
523 | * gets killed as soon as we unlock it, the next sibling is found | |
524 | * using the value left in its ->d_child.next. And if _that_ | |
525 | * pointed to a cursor, and cursor got moved (e.g. by lseek()) | |
526 | * before d_walk() regains parent->d_lock, we'll end up skipping | |
527 | * everything the cursor had been moved past. | |
528 | * | |
529 | * Solution: make sure that the pointer left behind in ->d_child.next | |
530 | * points to something that won't be moving around. I.e. skip the | |
531 | * cursors. | |
532 | */ | |
533 | while (dentry->d_child.next != &parent->d_subdirs) { | |
534 | next = list_entry(dentry->d_child.next, struct dentry, d_child); | |
535 | if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR))) | |
536 | break; | |
537 | dentry->d_child.next = next->d_child.next; | |
538 | } | |
539 | } | |
540 | ||
e55fd011 | 541 | static void __dentry_kill(struct dentry *dentry) |
77812a1e | 542 | { |
41edf278 AV |
543 | struct dentry *parent = NULL; |
544 | bool can_free = true; | |
41edf278 | 545 | if (!IS_ROOT(dentry)) |
77812a1e | 546 | parent = dentry->d_parent; |
31e6b01f | 547 | |
0d98439e LT |
548 | /* |
549 | * The dentry is now unrecoverably dead to the world. | |
550 | */ | |
551 | lockref_mark_dead(&dentry->d_lockref); | |
552 | ||
f0023bc6 | 553 | /* |
f0023bc6 SW |
554 | * inform the fs via d_prune that this dentry is about to be |
555 | * unhashed and destroyed. | |
556 | */ | |
29266201 | 557 | if (dentry->d_flags & DCACHE_OP_PRUNE) |
61572bb1 YZ |
558 | dentry->d_op->d_prune(dentry); |
559 | ||
01b60351 AV |
560 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
561 | if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) | |
562 | d_lru_del(dentry); | |
01b60351 | 563 | } |
77812a1e NP |
564 | /* if it was on the hash then remove it */ |
565 | __d_drop(dentry); | |
ba65dc5e | 566 | dentry_unlist(dentry, parent); |
03b3b889 AV |
567 | if (parent) |
568 | spin_unlock(&parent->d_lock); | |
550dce01 AV |
569 | if (dentry->d_inode) |
570 | dentry_unlink_inode(dentry); | |
571 | else | |
572 | spin_unlock(&dentry->d_lock); | |
03b3b889 AV |
573 | this_cpu_dec(nr_dentry); |
574 | if (dentry->d_op && dentry->d_op->d_release) | |
575 | dentry->d_op->d_release(dentry); | |
576 | ||
41edf278 AV |
577 | spin_lock(&dentry->d_lock); |
578 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { | |
579 | dentry->d_flags |= DCACHE_MAY_FREE; | |
580 | can_free = false; | |
581 | } | |
582 | spin_unlock(&dentry->d_lock); | |
41edf278 AV |
583 | if (likely(can_free)) |
584 | dentry_free(dentry); | |
e55fd011 AV |
585 | } |
586 | ||
587 | /* | |
588 | * Finish off a dentry we've decided to kill. | |
589 | * dentry->d_lock must be held, returns with it unlocked. | |
590 | * If ref is non-zero, then decrement the refcount too. | |
591 | * Returns dentry requiring refcount drop, or NULL if we're done. | |
592 | */ | |
8cbf74da | 593 | static struct dentry *dentry_kill(struct dentry *dentry) |
e55fd011 AV |
594 | __releases(dentry->d_lock) |
595 | { | |
596 | struct inode *inode = dentry->d_inode; | |
597 | struct dentry *parent = NULL; | |
598 | ||
599 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) | |
600 | goto failed; | |
601 | ||
602 | if (!IS_ROOT(dentry)) { | |
603 | parent = dentry->d_parent; | |
604 | if (unlikely(!spin_trylock(&parent->d_lock))) { | |
605 | if (inode) | |
606 | spin_unlock(&inode->i_lock); | |
607 | goto failed; | |
608 | } | |
609 | } | |
610 | ||
611 | __dentry_kill(dentry); | |
03b3b889 | 612 | return parent; |
e55fd011 AV |
613 | |
614 | failed: | |
8cbf74da | 615 | spin_unlock(&dentry->d_lock); |
e55fd011 | 616 | return dentry; /* try again with same dentry */ |
77812a1e NP |
617 | } |
618 | ||
046b961b AV |
619 | static inline struct dentry *lock_parent(struct dentry *dentry) |
620 | { | |
621 | struct dentry *parent = dentry->d_parent; | |
622 | if (IS_ROOT(dentry)) | |
623 | return NULL; | |
360f5479 | 624 | if (unlikely(dentry->d_lockref.count < 0)) |
c2338f2d | 625 | return NULL; |
046b961b AV |
626 | if (likely(spin_trylock(&parent->d_lock))) |
627 | return parent; | |
046b961b | 628 | rcu_read_lock(); |
c2338f2d | 629 | spin_unlock(&dentry->d_lock); |
046b961b AV |
630 | again: |
631 | parent = ACCESS_ONCE(dentry->d_parent); | |
632 | spin_lock(&parent->d_lock); | |
633 | /* | |
634 | * We can't blindly lock dentry until we are sure | |
635 | * that we won't violate the locking order. | |
636 | * Any changes of dentry->d_parent must have | |
637 | * been done with parent->d_lock held, so | |
638 | * spin_lock() above is enough of a barrier | |
639 | * for checking if it's still our child. | |
640 | */ | |
641 | if (unlikely(parent != dentry->d_parent)) { | |
642 | spin_unlock(&parent->d_lock); | |
643 | goto again; | |
644 | } | |
05f16fe9 | 645 | if (parent != dentry) { |
9f12600f | 646 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
05f16fe9 AV |
647 | if (unlikely(dentry->d_lockref.count < 0)) { |
648 | spin_unlock(&parent->d_lock); | |
649 | parent = NULL; | |
650 | } | |
651 | } else { | |
046b961b | 652 | parent = NULL; |
05f16fe9 AV |
653 | } |
654 | rcu_read_unlock(); | |
046b961b AV |
655 | return parent; |
656 | } | |
657 | ||
360f5479 LT |
658 | /* |
659 | * Try to do a lockless dput(), and return whether that was successful. | |
660 | * | |
661 | * If unsuccessful, we return false, having already taken the dentry lock. | |
662 | * | |
663 | * The caller needs to hold the RCU read lock, so that the dentry is | |
664 | * guaranteed to stay around even if the refcount goes down to zero! | |
665 | */ | |
666 | static inline bool fast_dput(struct dentry *dentry) | |
667 | { | |
668 | int ret; | |
669 | unsigned int d_flags; | |
670 | ||
671 | /* | |
672 | * If we have a d_op->d_delete() operation, we sould not | |
75a6f82a | 673 | * let the dentry count go to zero, so use "put_or_lock". |
360f5479 LT |
674 | */ |
675 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) | |
676 | return lockref_put_or_lock(&dentry->d_lockref); | |
677 | ||
678 | /* | |
679 | * .. otherwise, we can try to just decrement the | |
680 | * lockref optimistically. | |
681 | */ | |
682 | ret = lockref_put_return(&dentry->d_lockref); | |
683 | ||
684 | /* | |
685 | * If the lockref_put_return() failed due to the lock being held | |
686 | * by somebody else, the fast path has failed. We will need to | |
687 | * get the lock, and then check the count again. | |
688 | */ | |
689 | if (unlikely(ret < 0)) { | |
690 | spin_lock(&dentry->d_lock); | |
691 | if (dentry->d_lockref.count > 1) { | |
692 | dentry->d_lockref.count--; | |
693 | spin_unlock(&dentry->d_lock); | |
694 | return 1; | |
695 | } | |
696 | return 0; | |
697 | } | |
698 | ||
699 | /* | |
700 | * If we weren't the last ref, we're done. | |
701 | */ | |
702 | if (ret) | |
703 | return 1; | |
704 | ||
705 | /* | |
706 | * Careful, careful. The reference count went down | |
707 | * to zero, but we don't hold the dentry lock, so | |
708 | * somebody else could get it again, and do another | |
709 | * dput(), and we need to not race with that. | |
710 | * | |
711 | * However, there is a very special and common case | |
712 | * where we don't care, because there is nothing to | |
713 | * do: the dentry is still hashed, it does not have | |
714 | * a 'delete' op, and it's referenced and already on | |
715 | * the LRU list. | |
716 | * | |
717 | * NOTE! Since we aren't locked, these values are | |
718 | * not "stable". However, it is sufficient that at | |
719 | * some point after we dropped the reference the | |
720 | * dentry was hashed and the flags had the proper | |
721 | * value. Other dentry users may have re-gotten | |
722 | * a reference to the dentry and change that, but | |
723 | * our work is done - we can leave the dentry | |
724 | * around with a zero refcount. | |
725 | */ | |
726 | smp_rmb(); | |
727 | d_flags = ACCESS_ONCE(dentry->d_flags); | |
75a6f82a | 728 | d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED; |
360f5479 LT |
729 | |
730 | /* Nothing to do? Dropping the reference was all we needed? */ | |
731 | if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry)) | |
732 | return 1; | |
733 | ||
734 | /* | |
735 | * Not the fast normal case? Get the lock. We've already decremented | |
736 | * the refcount, but we'll need to re-check the situation after | |
737 | * getting the lock. | |
738 | */ | |
739 | spin_lock(&dentry->d_lock); | |
740 | ||
741 | /* | |
742 | * Did somebody else grab a reference to it in the meantime, and | |
743 | * we're no longer the last user after all? Alternatively, somebody | |
744 | * else could have killed it and marked it dead. Either way, we | |
745 | * don't need to do anything else. | |
746 | */ | |
747 | if (dentry->d_lockref.count) { | |
748 | spin_unlock(&dentry->d_lock); | |
749 | return 1; | |
750 | } | |
751 | ||
752 | /* | |
753 | * Re-get the reference we optimistically dropped. We hold the | |
754 | * lock, and we just tested that it was zero, so we can just | |
755 | * set it to 1. | |
756 | */ | |
757 | dentry->d_lockref.count = 1; | |
758 | return 0; | |
759 | } | |
760 | ||
761 | ||
1da177e4 LT |
762 | /* |
763 | * This is dput | |
764 | * | |
765 | * This is complicated by the fact that we do not want to put | |
766 | * dentries that are no longer on any hash chain on the unused | |
767 | * list: we'd much rather just get rid of them immediately. | |
768 | * | |
769 | * However, that implies that we have to traverse the dentry | |
770 | * tree upwards to the parents which might _also_ now be | |
771 | * scheduled for deletion (it may have been only waiting for | |
772 | * its last child to go away). | |
773 | * | |
774 | * This tail recursion is done by hand as we don't want to depend | |
775 | * on the compiler to always get this right (gcc generally doesn't). | |
776 | * Real recursion would eat up our stack space. | |
777 | */ | |
778 | ||
779 | /* | |
780 | * dput - release a dentry | |
781 | * @dentry: dentry to release | |
782 | * | |
783 | * Release a dentry. This will drop the usage count and if appropriate | |
784 | * call the dentry unlink method as well as removing it from the queues and | |
785 | * releasing its resources. If the parent dentries were scheduled for release | |
786 | * they too may now get deleted. | |
1da177e4 | 787 | */ |
1da177e4 LT |
788 | void dput(struct dentry *dentry) |
789 | { | |
8aab6a27 | 790 | if (unlikely(!dentry)) |
1da177e4 LT |
791 | return; |
792 | ||
793 | repeat: | |
47be6184 WF |
794 | might_sleep(); |
795 | ||
360f5479 LT |
796 | rcu_read_lock(); |
797 | if (likely(fast_dput(dentry))) { | |
798 | rcu_read_unlock(); | |
1da177e4 | 799 | return; |
360f5479 LT |
800 | } |
801 | ||
802 | /* Slow case: now with the dentry lock held */ | |
803 | rcu_read_unlock(); | |
1da177e4 | 804 | |
85c7f810 AV |
805 | WARN_ON(d_in_lookup(dentry)); |
806 | ||
8aab6a27 LT |
807 | /* Unreachable? Get rid of it */ |
808 | if (unlikely(d_unhashed(dentry))) | |
809 | goto kill_it; | |
810 | ||
75a6f82a AV |
811 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) |
812 | goto kill_it; | |
813 | ||
8aab6a27 | 814 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { |
1da177e4 | 815 | if (dentry->d_op->d_delete(dentry)) |
61f3dee4 | 816 | goto kill_it; |
1da177e4 | 817 | } |
265ac902 | 818 | |
358eec18 LT |
819 | if (!(dentry->d_flags & DCACHE_REFERENCED)) |
820 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 821 | dentry_lru_add(dentry); |
265ac902 | 822 | |
98474236 | 823 | dentry->d_lockref.count--; |
61f3dee4 | 824 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
825 | return; |
826 | ||
d52b9086 | 827 | kill_it: |
8cbf74da | 828 | dentry = dentry_kill(dentry); |
47be6184 WF |
829 | if (dentry) { |
830 | cond_resched(); | |
d52b9086 | 831 | goto repeat; |
47be6184 | 832 | } |
1da177e4 | 833 | } |
ec4f8605 | 834 | EXPORT_SYMBOL(dput); |
1da177e4 | 835 | |
1da177e4 | 836 | |
b5c84bf6 | 837 | /* This must be called with d_lock held */ |
dc0474be | 838 | static inline void __dget_dlock(struct dentry *dentry) |
23044507 | 839 | { |
98474236 | 840 | dentry->d_lockref.count++; |
23044507 NP |
841 | } |
842 | ||
dc0474be | 843 | static inline void __dget(struct dentry *dentry) |
1da177e4 | 844 | { |
98474236 | 845 | lockref_get(&dentry->d_lockref); |
1da177e4 LT |
846 | } |
847 | ||
b7ab39f6 NP |
848 | struct dentry *dget_parent(struct dentry *dentry) |
849 | { | |
df3d0bbc | 850 | int gotref; |
b7ab39f6 NP |
851 | struct dentry *ret; |
852 | ||
df3d0bbc WL |
853 | /* |
854 | * Do optimistic parent lookup without any | |
855 | * locking. | |
856 | */ | |
857 | rcu_read_lock(); | |
858 | ret = ACCESS_ONCE(dentry->d_parent); | |
859 | gotref = lockref_get_not_zero(&ret->d_lockref); | |
860 | rcu_read_unlock(); | |
861 | if (likely(gotref)) { | |
862 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) | |
863 | return ret; | |
864 | dput(ret); | |
865 | } | |
866 | ||
b7ab39f6 | 867 | repeat: |
a734eb45 NP |
868 | /* |
869 | * Don't need rcu_dereference because we re-check it was correct under | |
870 | * the lock. | |
871 | */ | |
872 | rcu_read_lock(); | |
b7ab39f6 | 873 | ret = dentry->d_parent; |
a734eb45 NP |
874 | spin_lock(&ret->d_lock); |
875 | if (unlikely(ret != dentry->d_parent)) { | |
876 | spin_unlock(&ret->d_lock); | |
877 | rcu_read_unlock(); | |
b7ab39f6 NP |
878 | goto repeat; |
879 | } | |
a734eb45 | 880 | rcu_read_unlock(); |
98474236 WL |
881 | BUG_ON(!ret->d_lockref.count); |
882 | ret->d_lockref.count++; | |
b7ab39f6 | 883 | spin_unlock(&ret->d_lock); |
b7ab39f6 NP |
884 | return ret; |
885 | } | |
886 | EXPORT_SYMBOL(dget_parent); | |
887 | ||
1da177e4 LT |
888 | /** |
889 | * d_find_alias - grab a hashed alias of inode | |
890 | * @inode: inode in question | |
1da177e4 LT |
891 | * |
892 | * If inode has a hashed alias, or is a directory and has any alias, | |
893 | * acquire the reference to alias and return it. Otherwise return NULL. | |
894 | * Notice that if inode is a directory there can be only one alias and | |
895 | * it can be unhashed only if it has no children, or if it is the root | |
3ccb354d EB |
896 | * of a filesystem, or if the directory was renamed and d_revalidate |
897 | * was the first vfs operation to notice. | |
1da177e4 | 898 | * |
21c0d8fd | 899 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
52ed46f0 | 900 | * any other hashed alias over that one. |
1da177e4 | 901 | */ |
52ed46f0 | 902 | static struct dentry *__d_find_alias(struct inode *inode) |
1da177e4 | 903 | { |
da502956 | 904 | struct dentry *alias, *discon_alias; |
1da177e4 | 905 | |
da502956 NP |
906 | again: |
907 | discon_alias = NULL; | |
946e51f2 | 908 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
da502956 | 909 | spin_lock(&alias->d_lock); |
1da177e4 | 910 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
21c0d8fd | 911 | if (IS_ROOT(alias) && |
da502956 | 912 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
1da177e4 | 913 | discon_alias = alias; |
52ed46f0 | 914 | } else { |
dc0474be | 915 | __dget_dlock(alias); |
da502956 NP |
916 | spin_unlock(&alias->d_lock); |
917 | return alias; | |
918 | } | |
919 | } | |
920 | spin_unlock(&alias->d_lock); | |
921 | } | |
922 | if (discon_alias) { | |
923 | alias = discon_alias; | |
924 | spin_lock(&alias->d_lock); | |
925 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
8d80d7da BF |
926 | __dget_dlock(alias); |
927 | spin_unlock(&alias->d_lock); | |
928 | return alias; | |
1da177e4 | 929 | } |
da502956 NP |
930 | spin_unlock(&alias->d_lock); |
931 | goto again; | |
1da177e4 | 932 | } |
da502956 | 933 | return NULL; |
1da177e4 LT |
934 | } |
935 | ||
da502956 | 936 | struct dentry *d_find_alias(struct inode *inode) |
1da177e4 | 937 | { |
214fda1f DH |
938 | struct dentry *de = NULL; |
939 | ||
b3d9b7a3 | 940 | if (!hlist_empty(&inode->i_dentry)) { |
873feea0 | 941 | spin_lock(&inode->i_lock); |
52ed46f0 | 942 | de = __d_find_alias(inode); |
873feea0 | 943 | spin_unlock(&inode->i_lock); |
214fda1f | 944 | } |
1da177e4 LT |
945 | return de; |
946 | } | |
ec4f8605 | 947 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
948 | |
949 | /* | |
950 | * Try to kill dentries associated with this inode. | |
951 | * WARNING: you must own a reference to inode. | |
952 | */ | |
953 | void d_prune_aliases(struct inode *inode) | |
954 | { | |
0cdca3f9 | 955 | struct dentry *dentry; |
1da177e4 | 956 | restart: |
873feea0 | 957 | spin_lock(&inode->i_lock); |
946e51f2 | 958 | hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
1da177e4 | 959 | spin_lock(&dentry->d_lock); |
98474236 | 960 | if (!dentry->d_lockref.count) { |
29355c39 AV |
961 | struct dentry *parent = lock_parent(dentry); |
962 | if (likely(!dentry->d_lockref.count)) { | |
963 | __dentry_kill(dentry); | |
4a7795d3 | 964 | dput(parent); |
29355c39 AV |
965 | goto restart; |
966 | } | |
967 | if (parent) | |
968 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
969 | } |
970 | spin_unlock(&dentry->d_lock); | |
971 | } | |
873feea0 | 972 | spin_unlock(&inode->i_lock); |
1da177e4 | 973 | } |
ec4f8605 | 974 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 | 975 | |
3049cfe2 | 976 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 977 | { |
5c47e6d0 | 978 | struct dentry *dentry, *parent; |
da3bbdd4 | 979 | |
60942f2f | 980 | while (!list_empty(list)) { |
ff2fde99 | 981 | struct inode *inode; |
60942f2f | 982 | dentry = list_entry(list->prev, struct dentry, d_lru); |
ec33679d | 983 | spin_lock(&dentry->d_lock); |
046b961b AV |
984 | parent = lock_parent(dentry); |
985 | ||
dd1f6b2e DC |
986 | /* |
987 | * The dispose list is isolated and dentries are not accounted | |
988 | * to the LRU here, so we can simply remove it from the list | |
989 | * here regardless of whether it is referenced or not. | |
990 | */ | |
89dc77bc | 991 | d_shrink_del(dentry); |
dd1f6b2e | 992 | |
1da177e4 LT |
993 | /* |
994 | * We found an inuse dentry which was not removed from | |
dd1f6b2e | 995 | * the LRU because of laziness during lookup. Do not free it. |
1da177e4 | 996 | */ |
360f5479 | 997 | if (dentry->d_lockref.count > 0) { |
da3bbdd4 | 998 | spin_unlock(&dentry->d_lock); |
046b961b AV |
999 | if (parent) |
1000 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
1001 | continue; |
1002 | } | |
77812a1e | 1003 | |
64fd72e0 AV |
1004 | |
1005 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) { | |
1006 | bool can_free = dentry->d_flags & DCACHE_MAY_FREE; | |
1007 | spin_unlock(&dentry->d_lock); | |
046b961b AV |
1008 | if (parent) |
1009 | spin_unlock(&parent->d_lock); | |
64fd72e0 AV |
1010 | if (can_free) |
1011 | dentry_free(dentry); | |
1012 | continue; | |
1013 | } | |
1014 | ||
ff2fde99 AV |
1015 | inode = dentry->d_inode; |
1016 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) { | |
89dc77bc | 1017 | d_shrink_add(dentry, list); |
dd1f6b2e | 1018 | spin_unlock(&dentry->d_lock); |
046b961b AV |
1019 | if (parent) |
1020 | spin_unlock(&parent->d_lock); | |
5c47e6d0 | 1021 | continue; |
dd1f6b2e | 1022 | } |
ff2fde99 | 1023 | |
ff2fde99 | 1024 | __dentry_kill(dentry); |
046b961b | 1025 | |
5c47e6d0 AV |
1026 | /* |
1027 | * We need to prune ancestors too. This is necessary to prevent | |
1028 | * quadratic behavior of shrink_dcache_parent(), but is also | |
1029 | * expected to be beneficial in reducing dentry cache | |
1030 | * fragmentation. | |
1031 | */ | |
1032 | dentry = parent; | |
b2b80195 AV |
1033 | while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { |
1034 | parent = lock_parent(dentry); | |
1035 | if (dentry->d_lockref.count != 1) { | |
1036 | dentry->d_lockref.count--; | |
1037 | spin_unlock(&dentry->d_lock); | |
1038 | if (parent) | |
1039 | spin_unlock(&parent->d_lock); | |
1040 | break; | |
1041 | } | |
1042 | inode = dentry->d_inode; /* can't be NULL */ | |
1043 | if (unlikely(!spin_trylock(&inode->i_lock))) { | |
1044 | spin_unlock(&dentry->d_lock); | |
1045 | if (parent) | |
1046 | spin_unlock(&parent->d_lock); | |
1047 | cpu_relax(); | |
1048 | continue; | |
1049 | } | |
1050 | __dentry_kill(dentry); | |
1051 | dentry = parent; | |
1052 | } | |
da3bbdd4 | 1053 | } |
3049cfe2 CH |
1054 | } |
1055 | ||
3f97b163 VD |
1056 | static enum lru_status dentry_lru_isolate(struct list_head *item, |
1057 | struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) | |
f6041567 DC |
1058 | { |
1059 | struct list_head *freeable = arg; | |
1060 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
1061 | ||
1062 | ||
1063 | /* | |
1064 | * we are inverting the lru lock/dentry->d_lock here, | |
1065 | * so use a trylock. If we fail to get the lock, just skip | |
1066 | * it | |
1067 | */ | |
1068 | if (!spin_trylock(&dentry->d_lock)) | |
1069 | return LRU_SKIP; | |
1070 | ||
1071 | /* | |
1072 | * Referenced dentries are still in use. If they have active | |
1073 | * counts, just remove them from the LRU. Otherwise give them | |
1074 | * another pass through the LRU. | |
1075 | */ | |
1076 | if (dentry->d_lockref.count) { | |
3f97b163 | 1077 | d_lru_isolate(lru, dentry); |
f6041567 DC |
1078 | spin_unlock(&dentry->d_lock); |
1079 | return LRU_REMOVED; | |
1080 | } | |
1081 | ||
1082 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
1083 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
1084 | spin_unlock(&dentry->d_lock); | |
1085 | ||
1086 | /* | |
1087 | * The list move itself will be made by the common LRU code. At | |
1088 | * this point, we've dropped the dentry->d_lock but keep the | |
1089 | * lru lock. This is safe to do, since every list movement is | |
1090 | * protected by the lru lock even if both locks are held. | |
1091 | * | |
1092 | * This is guaranteed by the fact that all LRU management | |
1093 | * functions are intermediated by the LRU API calls like | |
1094 | * list_lru_add and list_lru_del. List movement in this file | |
1095 | * only ever occur through this functions or through callbacks | |
1096 | * like this one, that are called from the LRU API. | |
1097 | * | |
1098 | * The only exceptions to this are functions like | |
1099 | * shrink_dentry_list, and code that first checks for the | |
1100 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be | |
1101 | * operating only with stack provided lists after they are | |
1102 | * properly isolated from the main list. It is thus, always a | |
1103 | * local access. | |
1104 | */ | |
1105 | return LRU_ROTATE; | |
1106 | } | |
1107 | ||
3f97b163 | 1108 | d_lru_shrink_move(lru, dentry, freeable); |
f6041567 DC |
1109 | spin_unlock(&dentry->d_lock); |
1110 | ||
1111 | return LRU_REMOVED; | |
1112 | } | |
1113 | ||
3049cfe2 | 1114 | /** |
b48f03b3 DC |
1115 | * prune_dcache_sb - shrink the dcache |
1116 | * @sb: superblock | |
503c358c | 1117 | * @sc: shrink control, passed to list_lru_shrink_walk() |
b48f03b3 | 1118 | * |
503c358c VD |
1119 | * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This |
1120 | * is done when we need more memory and called from the superblock shrinker | |
b48f03b3 | 1121 | * function. |
3049cfe2 | 1122 | * |
b48f03b3 DC |
1123 | * This function may fail to free any resources if all the dentries are in |
1124 | * use. | |
3049cfe2 | 1125 | */ |
503c358c | 1126 | long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc) |
3049cfe2 | 1127 | { |
f6041567 DC |
1128 | LIST_HEAD(dispose); |
1129 | long freed; | |
3049cfe2 | 1130 | |
503c358c VD |
1131 | freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc, |
1132 | dentry_lru_isolate, &dispose); | |
f6041567 | 1133 | shrink_dentry_list(&dispose); |
0a234c6d | 1134 | return freed; |
da3bbdd4 | 1135 | } |
23044507 | 1136 | |
4e717f5c | 1137 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
3f97b163 | 1138 | struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) |
dd1f6b2e | 1139 | { |
4e717f5c GC |
1140 | struct list_head *freeable = arg; |
1141 | struct dentry *dentry = container_of(item, struct dentry, d_lru); | |
dd1f6b2e | 1142 | |
4e717f5c GC |
1143 | /* |
1144 | * we are inverting the lru lock/dentry->d_lock here, | |
1145 | * so use a trylock. If we fail to get the lock, just skip | |
1146 | * it | |
1147 | */ | |
1148 | if (!spin_trylock(&dentry->d_lock)) | |
1149 | return LRU_SKIP; | |
1150 | ||
3f97b163 | 1151 | d_lru_shrink_move(lru, dentry, freeable); |
4e717f5c | 1152 | spin_unlock(&dentry->d_lock); |
ec33679d | 1153 | |
4e717f5c | 1154 | return LRU_REMOVED; |
da3bbdd4 KM |
1155 | } |
1156 | ||
4e717f5c | 1157 | |
1da177e4 LT |
1158 | /** |
1159 | * shrink_dcache_sb - shrink dcache for a superblock | |
1160 | * @sb: superblock | |
1161 | * | |
3049cfe2 CH |
1162 | * Shrink the dcache for the specified super block. This is used to free |
1163 | * the dcache before unmounting a file system. | |
1da177e4 | 1164 | */ |
3049cfe2 | 1165 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 1166 | { |
4e717f5c GC |
1167 | do { |
1168 | LIST_HEAD(dispose); | |
1169 | ||
92744323 | 1170 | list_lru_walk(&sb->s_dentry_lru, |
a9aa6522 | 1171 | dentry_lru_isolate_shrink, &dispose, 1024); |
4e717f5c | 1172 | shrink_dentry_list(&dispose); |
a9aa6522 ST |
1173 | cond_resched(); |
1174 | } while (list_lru_count(&sb->s_dentry_lru) > 0); | |
1da177e4 | 1175 | } |
ec4f8605 | 1176 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 1177 | |
db14fc3a MS |
1178 | /** |
1179 | * enum d_walk_ret - action to talke during tree walk | |
1180 | * @D_WALK_CONTINUE: contrinue walk | |
1181 | * @D_WALK_QUIT: quit walk | |
1182 | * @D_WALK_NORETRY: quit when retry is needed | |
1183 | * @D_WALK_SKIP: skip this dentry and its children | |
1184 | */ | |
1185 | enum d_walk_ret { | |
1186 | D_WALK_CONTINUE, | |
1187 | D_WALK_QUIT, | |
1188 | D_WALK_NORETRY, | |
1189 | D_WALK_SKIP, | |
1190 | }; | |
c826cb7d | 1191 | |
1da177e4 | 1192 | /** |
db14fc3a MS |
1193 | * d_walk - walk the dentry tree |
1194 | * @parent: start of walk | |
1195 | * @data: data passed to @enter() and @finish() | |
1196 | * @enter: callback when first entering the dentry | |
1197 | * @finish: callback when successfully finished the walk | |
1da177e4 | 1198 | * |
db14fc3a | 1199 | * The @enter() and @finish() callbacks are called with d_lock held. |
1da177e4 | 1200 | */ |
db14fc3a MS |
1201 | static void d_walk(struct dentry *parent, void *data, |
1202 | enum d_walk_ret (*enter)(void *, struct dentry *), | |
1203 | void (*finish)(void *)) | |
1da177e4 | 1204 | { |
949854d0 | 1205 | struct dentry *this_parent; |
1da177e4 | 1206 | struct list_head *next; |
48f5ec21 | 1207 | unsigned seq = 0; |
db14fc3a MS |
1208 | enum d_walk_ret ret; |
1209 | bool retry = true; | |
949854d0 | 1210 | |
58db63d0 | 1211 | again: |
48f5ec21 | 1212 | read_seqbegin_or_lock(&rename_lock, &seq); |
58db63d0 | 1213 | this_parent = parent; |
2fd6b7f5 | 1214 | spin_lock(&this_parent->d_lock); |
db14fc3a MS |
1215 | |
1216 | ret = enter(data, this_parent); | |
1217 | switch (ret) { | |
1218 | case D_WALK_CONTINUE: | |
1219 | break; | |
1220 | case D_WALK_QUIT: | |
1221 | case D_WALK_SKIP: | |
1222 | goto out_unlock; | |
1223 | case D_WALK_NORETRY: | |
1224 | retry = false; | |
1225 | break; | |
1226 | } | |
1da177e4 LT |
1227 | repeat: |
1228 | next = this_parent->d_subdirs.next; | |
1229 | resume: | |
1230 | while (next != &this_parent->d_subdirs) { | |
1231 | struct list_head *tmp = next; | |
946e51f2 | 1232 | struct dentry *dentry = list_entry(tmp, struct dentry, d_child); |
1da177e4 | 1233 | next = tmp->next; |
2fd6b7f5 | 1234 | |
ba65dc5e AV |
1235 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR)) |
1236 | continue; | |
1237 | ||
2fd6b7f5 | 1238 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
db14fc3a MS |
1239 | |
1240 | ret = enter(data, dentry); | |
1241 | switch (ret) { | |
1242 | case D_WALK_CONTINUE: | |
1243 | break; | |
1244 | case D_WALK_QUIT: | |
2fd6b7f5 | 1245 | spin_unlock(&dentry->d_lock); |
db14fc3a MS |
1246 | goto out_unlock; |
1247 | case D_WALK_NORETRY: | |
1248 | retry = false; | |
1249 | break; | |
1250 | case D_WALK_SKIP: | |
1251 | spin_unlock(&dentry->d_lock); | |
1252 | continue; | |
2fd6b7f5 | 1253 | } |
db14fc3a | 1254 | |
1da177e4 | 1255 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
1256 | spin_unlock(&this_parent->d_lock); |
1257 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1258 | this_parent = dentry; |
2fd6b7f5 | 1259 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1260 | goto repeat; |
1261 | } | |
2fd6b7f5 | 1262 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
1263 | } |
1264 | /* | |
1265 | * All done at this level ... ascend and resume the search. | |
1266 | */ | |
ca5358ef AV |
1267 | rcu_read_lock(); |
1268 | ascend: | |
1da177e4 | 1269 | if (this_parent != parent) { |
c826cb7d | 1270 | struct dentry *child = this_parent; |
31dec132 AV |
1271 | this_parent = child->d_parent; |
1272 | ||
31dec132 AV |
1273 | spin_unlock(&child->d_lock); |
1274 | spin_lock(&this_parent->d_lock); | |
1275 | ||
ca5358ef AV |
1276 | /* might go back up the wrong parent if we have had a rename. */ |
1277 | if (need_seqretry(&rename_lock, seq)) | |
949854d0 | 1278 | goto rename_retry; |
2159184e AV |
1279 | /* go into the first sibling still alive */ |
1280 | do { | |
1281 | next = child->d_child.next; | |
ca5358ef AV |
1282 | if (next == &this_parent->d_subdirs) |
1283 | goto ascend; | |
1284 | child = list_entry(next, struct dentry, d_child); | |
2159184e | 1285 | } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); |
31dec132 | 1286 | rcu_read_unlock(); |
1da177e4 LT |
1287 | goto resume; |
1288 | } | |
ca5358ef | 1289 | if (need_seqretry(&rename_lock, seq)) |
949854d0 | 1290 | goto rename_retry; |
ca5358ef | 1291 | rcu_read_unlock(); |
db14fc3a MS |
1292 | if (finish) |
1293 | finish(data); | |
1294 | ||
1295 | out_unlock: | |
1296 | spin_unlock(&this_parent->d_lock); | |
48f5ec21 | 1297 | done_seqretry(&rename_lock, seq); |
db14fc3a | 1298 | return; |
58db63d0 NP |
1299 | |
1300 | rename_retry: | |
ca5358ef AV |
1301 | spin_unlock(&this_parent->d_lock); |
1302 | rcu_read_unlock(); | |
1303 | BUG_ON(seq & 1); | |
db14fc3a MS |
1304 | if (!retry) |
1305 | return; | |
48f5ec21 | 1306 | seq = 1; |
58db63d0 | 1307 | goto again; |
1da177e4 | 1308 | } |
db14fc3a MS |
1309 | |
1310 | /* | |
1311 | * Search for at least 1 mount point in the dentry's subdirs. | |
1312 | * We descend to the next level whenever the d_subdirs | |
1313 | * list is non-empty and continue searching. | |
1314 | */ | |
1315 | ||
db14fc3a MS |
1316 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
1317 | { | |
1318 | int *ret = data; | |
1319 | if (d_mountpoint(dentry)) { | |
1320 | *ret = 1; | |
1321 | return D_WALK_QUIT; | |
1322 | } | |
1323 | return D_WALK_CONTINUE; | |
1324 | } | |
1325 | ||
69c88dc7 RD |
1326 | /** |
1327 | * have_submounts - check for mounts over a dentry | |
1328 | * @parent: dentry to check. | |
1329 | * | |
1330 | * Return true if the parent or its subdirectories contain | |
1331 | * a mount point | |
1332 | */ | |
db14fc3a MS |
1333 | int have_submounts(struct dentry *parent) |
1334 | { | |
1335 | int ret = 0; | |
1336 | ||
1337 | d_walk(parent, &ret, check_mount, NULL); | |
1338 | ||
1339 | return ret; | |
1340 | } | |
ec4f8605 | 1341 | EXPORT_SYMBOL(have_submounts); |
1da177e4 | 1342 | |
eed81007 MS |
1343 | /* |
1344 | * Called by mount code to set a mountpoint and check if the mountpoint is | |
1345 | * reachable (e.g. NFS can unhash a directory dentry and then the complete | |
1346 | * subtree can become unreachable). | |
1347 | * | |
1ffe46d1 | 1348 | * Only one of d_invalidate() and d_set_mounted() must succeed. For |
eed81007 MS |
1349 | * this reason take rename_lock and d_lock on dentry and ancestors. |
1350 | */ | |
1351 | int d_set_mounted(struct dentry *dentry) | |
1352 | { | |
1353 | struct dentry *p; | |
1354 | int ret = -ENOENT; | |
1355 | write_seqlock(&rename_lock); | |
1356 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { | |
1ffe46d1 | 1357 | /* Need exclusion wrt. d_invalidate() */ |
eed81007 MS |
1358 | spin_lock(&p->d_lock); |
1359 | if (unlikely(d_unhashed(p))) { | |
1360 | spin_unlock(&p->d_lock); | |
1361 | goto out; | |
1362 | } | |
1363 | spin_unlock(&p->d_lock); | |
1364 | } | |
1365 | spin_lock(&dentry->d_lock); | |
1366 | if (!d_unlinked(dentry)) { | |
1a62a0f7 EB |
1367 | ret = -EBUSY; |
1368 | if (!d_mountpoint(dentry)) { | |
1369 | dentry->d_flags |= DCACHE_MOUNTED; | |
1370 | ret = 0; | |
1371 | } | |
eed81007 MS |
1372 | } |
1373 | spin_unlock(&dentry->d_lock); | |
1374 | out: | |
1375 | write_sequnlock(&rename_lock); | |
1376 | return ret; | |
1377 | } | |
1378 | ||
1da177e4 | 1379 | /* |
fd517909 | 1380 | * Search the dentry child list of the specified parent, |
1da177e4 LT |
1381 | * and move any unused dentries to the end of the unused |
1382 | * list for prune_dcache(). We descend to the next level | |
1383 | * whenever the d_subdirs list is non-empty and continue | |
1384 | * searching. | |
1385 | * | |
1386 | * It returns zero iff there are no unused children, | |
1387 | * otherwise it returns the number of children moved to | |
1388 | * the end of the unused list. This may not be the total | |
1389 | * number of unused children, because select_parent can | |
1390 | * drop the lock and return early due to latency | |
1391 | * constraints. | |
1392 | */ | |
1da177e4 | 1393 | |
db14fc3a MS |
1394 | struct select_data { |
1395 | struct dentry *start; | |
1396 | struct list_head dispose; | |
1397 | int found; | |
1398 | }; | |
23044507 | 1399 | |
db14fc3a MS |
1400 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
1401 | { | |
1402 | struct select_data *data = _data; | |
1403 | enum d_walk_ret ret = D_WALK_CONTINUE; | |
1da177e4 | 1404 | |
db14fc3a MS |
1405 | if (data->start == dentry) |
1406 | goto out; | |
2fd6b7f5 | 1407 | |
fe91522a | 1408 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
db14fc3a | 1409 | data->found++; |
fe91522a AV |
1410 | } else { |
1411 | if (dentry->d_flags & DCACHE_LRU_LIST) | |
1412 | d_lru_del(dentry); | |
1413 | if (!dentry->d_lockref.count) { | |
1414 | d_shrink_add(dentry, &data->dispose); | |
1415 | data->found++; | |
1416 | } | |
1da177e4 | 1417 | } |
db14fc3a MS |
1418 | /* |
1419 | * We can return to the caller if we have found some (this | |
1420 | * ensures forward progress). We'll be coming back to find | |
1421 | * the rest. | |
1422 | */ | |
fe91522a AV |
1423 | if (!list_empty(&data->dispose)) |
1424 | ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; | |
1da177e4 | 1425 | out: |
db14fc3a | 1426 | return ret; |
1da177e4 LT |
1427 | } |
1428 | ||
1429 | /** | |
1430 | * shrink_dcache_parent - prune dcache | |
1431 | * @parent: parent of entries to prune | |
1432 | * | |
1433 | * Prune the dcache to remove unused children of the parent dentry. | |
1434 | */ | |
db14fc3a | 1435 | void shrink_dcache_parent(struct dentry *parent) |
1da177e4 | 1436 | { |
db14fc3a MS |
1437 | for (;;) { |
1438 | struct select_data data; | |
1da177e4 | 1439 | |
db14fc3a MS |
1440 | INIT_LIST_HEAD(&data.dispose); |
1441 | data.start = parent; | |
1442 | data.found = 0; | |
1443 | ||
1444 | d_walk(parent, &data, select_collect, NULL); | |
1445 | if (!data.found) | |
1446 | break; | |
1447 | ||
1448 | shrink_dentry_list(&data.dispose); | |
421348f1 GT |
1449 | cond_resched(); |
1450 | } | |
1da177e4 | 1451 | } |
ec4f8605 | 1452 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1453 | |
9c8c10e2 | 1454 | static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) |
42c32608 | 1455 | { |
9c8c10e2 AV |
1456 | /* it has busy descendents; complain about those instead */ |
1457 | if (!list_empty(&dentry->d_subdirs)) | |
1458 | return D_WALK_CONTINUE; | |
42c32608 | 1459 | |
9c8c10e2 AV |
1460 | /* root with refcount 1 is fine */ |
1461 | if (dentry == _data && dentry->d_lockref.count == 1) | |
1462 | return D_WALK_CONTINUE; | |
1463 | ||
1464 | printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} " | |
1465 | " still in use (%d) [unmount of %s %s]\n", | |
42c32608 AV |
1466 | dentry, |
1467 | dentry->d_inode ? | |
1468 | dentry->d_inode->i_ino : 0UL, | |
9c8c10e2 | 1469 | dentry, |
42c32608 AV |
1470 | dentry->d_lockref.count, |
1471 | dentry->d_sb->s_type->name, | |
1472 | dentry->d_sb->s_id); | |
9c8c10e2 AV |
1473 | WARN_ON(1); |
1474 | return D_WALK_CONTINUE; | |
1475 | } | |
1476 | ||
1477 | static void do_one_tree(struct dentry *dentry) | |
1478 | { | |
1479 | shrink_dcache_parent(dentry); | |
1480 | d_walk(dentry, dentry, umount_check, NULL); | |
1481 | d_drop(dentry); | |
1482 | dput(dentry); | |
42c32608 AV |
1483 | } |
1484 | ||
1485 | /* | |
1486 | * destroy the dentries attached to a superblock on unmounting | |
1487 | */ | |
1488 | void shrink_dcache_for_umount(struct super_block *sb) | |
1489 | { | |
1490 | struct dentry *dentry; | |
1491 | ||
9c8c10e2 | 1492 | WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked"); |
42c32608 AV |
1493 | |
1494 | dentry = sb->s_root; | |
1495 | sb->s_root = NULL; | |
9c8c10e2 | 1496 | do_one_tree(dentry); |
42c32608 AV |
1497 | |
1498 | while (!hlist_bl_empty(&sb->s_anon)) { | |
9c8c10e2 AV |
1499 | dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash)); |
1500 | do_one_tree(dentry); | |
42c32608 AV |
1501 | } |
1502 | } | |
1503 | ||
8ed936b5 EB |
1504 | struct detach_data { |
1505 | struct select_data select; | |
1506 | struct dentry *mountpoint; | |
1507 | }; | |
1508 | static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry) | |
848ac114 | 1509 | { |
8ed936b5 | 1510 | struct detach_data *data = _data; |
848ac114 MS |
1511 | |
1512 | if (d_mountpoint(dentry)) { | |
8ed936b5 EB |
1513 | __dget_dlock(dentry); |
1514 | data->mountpoint = dentry; | |
848ac114 MS |
1515 | return D_WALK_QUIT; |
1516 | } | |
1517 | ||
8ed936b5 | 1518 | return select_collect(&data->select, dentry); |
848ac114 MS |
1519 | } |
1520 | ||
1521 | static void check_and_drop(void *_data) | |
1522 | { | |
8ed936b5 | 1523 | struct detach_data *data = _data; |
848ac114 | 1524 | |
1987172d | 1525 | if (!data->mountpoint && list_empty(&data->select.dispose)) |
8ed936b5 | 1526 | __d_drop(data->select.start); |
848ac114 MS |
1527 | } |
1528 | ||
1529 | /** | |
1ffe46d1 EB |
1530 | * d_invalidate - detach submounts, prune dcache, and drop |
1531 | * @dentry: dentry to invalidate (aka detach, prune and drop) | |
1532 | * | |
1ffe46d1 | 1533 | * no dcache lock. |
848ac114 | 1534 | * |
8ed936b5 EB |
1535 | * The final d_drop is done as an atomic operation relative to |
1536 | * rename_lock ensuring there are no races with d_set_mounted. This | |
1537 | * ensures there are no unhashed dentries on the path to a mountpoint. | |
848ac114 | 1538 | */ |
5542aa2f | 1539 | void d_invalidate(struct dentry *dentry) |
848ac114 | 1540 | { |
1ffe46d1 EB |
1541 | /* |
1542 | * If it's already been dropped, return OK. | |
1543 | */ | |
1544 | spin_lock(&dentry->d_lock); | |
1545 | if (d_unhashed(dentry)) { | |
1546 | spin_unlock(&dentry->d_lock); | |
5542aa2f | 1547 | return; |
1ffe46d1 EB |
1548 | } |
1549 | spin_unlock(&dentry->d_lock); | |
1550 | ||
848ac114 MS |
1551 | /* Negative dentries can be dropped without further checks */ |
1552 | if (!dentry->d_inode) { | |
1553 | d_drop(dentry); | |
5542aa2f | 1554 | return; |
848ac114 MS |
1555 | } |
1556 | ||
1557 | for (;;) { | |
8ed936b5 | 1558 | struct detach_data data; |
848ac114 | 1559 | |
8ed936b5 EB |
1560 | data.mountpoint = NULL; |
1561 | INIT_LIST_HEAD(&data.select.dispose); | |
1562 | data.select.start = dentry; | |
1563 | data.select.found = 0; | |
1564 | ||
1565 | d_walk(dentry, &data, detach_and_collect, check_and_drop); | |
848ac114 | 1566 | |
1987172d | 1567 | if (!list_empty(&data.select.dispose)) |
8ed936b5 | 1568 | shrink_dentry_list(&data.select.dispose); |
1987172d AV |
1569 | else if (!data.mountpoint) |
1570 | return; | |
848ac114 | 1571 | |
8ed936b5 EB |
1572 | if (data.mountpoint) { |
1573 | detach_mounts(data.mountpoint); | |
1574 | dput(data.mountpoint); | |
1575 | } | |
848ac114 MS |
1576 | cond_resched(); |
1577 | } | |
848ac114 | 1578 | } |
1ffe46d1 | 1579 | EXPORT_SYMBOL(d_invalidate); |
848ac114 | 1580 | |
1da177e4 | 1581 | /** |
a4464dbc AV |
1582 | * __d_alloc - allocate a dcache entry |
1583 | * @sb: filesystem it will belong to | |
1da177e4 LT |
1584 | * @name: qstr of the name |
1585 | * | |
1586 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1587 | * available. On a success the dentry is returned. The name passed in is | |
1588 | * copied and the copy passed in may be reused after this call. | |
1589 | */ | |
1590 | ||
a4464dbc | 1591 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1da177e4 LT |
1592 | { |
1593 | struct dentry *dentry; | |
1594 | char *dname; | |
285b102d | 1595 | int err; |
1da177e4 | 1596 | |
e12ba74d | 1597 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1598 | if (!dentry) |
1599 | return NULL; | |
1600 | ||
6326c71f LT |
1601 | /* |
1602 | * We guarantee that the inline name is always NUL-terminated. | |
1603 | * This way the memcpy() done by the name switching in rename | |
1604 | * will still always have a NUL at the end, even if we might | |
1605 | * be overwriting an internal NUL character | |
1606 | */ | |
1607 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; | |
798434bd AV |
1608 | if (unlikely(!name)) { |
1609 | static const struct qstr anon = QSTR_INIT("/", 1); | |
1610 | name = &anon; | |
1611 | dname = dentry->d_iname; | |
1612 | } else if (name->len > DNAME_INLINE_LEN-1) { | |
8d85b484 | 1613 | size_t size = offsetof(struct external_name, name[1]); |
5d097056 VD |
1614 | struct external_name *p = kmalloc(size + name->len, |
1615 | GFP_KERNEL_ACCOUNT); | |
8d85b484 | 1616 | if (!p) { |
1da177e4 LT |
1617 | kmem_cache_free(dentry_cache, dentry); |
1618 | return NULL; | |
1619 | } | |
8d85b484 AV |
1620 | atomic_set(&p->u.count, 1); |
1621 | dname = p->name; | |
df4c0e36 AR |
1622 | if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS)) |
1623 | kasan_unpoison_shadow(dname, | |
1624 | round_up(name->len + 1, sizeof(unsigned long))); | |
1da177e4 LT |
1625 | } else { |
1626 | dname = dentry->d_iname; | |
1627 | } | |
1da177e4 LT |
1628 | |
1629 | dentry->d_name.len = name->len; | |
1630 | dentry->d_name.hash = name->hash; | |
1631 | memcpy(dname, name->name, name->len); | |
1632 | dname[name->len] = 0; | |
1633 | ||
6326c71f LT |
1634 | /* Make sure we always see the terminating NUL character */ |
1635 | smp_wmb(); | |
1636 | dentry->d_name.name = dname; | |
1637 | ||
98474236 | 1638 | dentry->d_lockref.count = 1; |
dea3667b | 1639 | dentry->d_flags = 0; |
1da177e4 | 1640 | spin_lock_init(&dentry->d_lock); |
31e6b01f | 1641 | seqcount_init(&dentry->d_seq); |
1da177e4 | 1642 | dentry->d_inode = NULL; |
a4464dbc AV |
1643 | dentry->d_parent = dentry; |
1644 | dentry->d_sb = sb; | |
1da177e4 LT |
1645 | dentry->d_op = NULL; |
1646 | dentry->d_fsdata = NULL; | |
ceb5bdc2 | 1647 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1da177e4 LT |
1648 | INIT_LIST_HEAD(&dentry->d_lru); |
1649 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
946e51f2 AV |
1650 | INIT_HLIST_NODE(&dentry->d_u.d_alias); |
1651 | INIT_LIST_HEAD(&dentry->d_child); | |
a4464dbc | 1652 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1da177e4 | 1653 | |
285b102d MS |
1654 | if (dentry->d_op && dentry->d_op->d_init) { |
1655 | err = dentry->d_op->d_init(dentry); | |
1656 | if (err) { | |
1657 | if (dname_external(dentry)) | |
1658 | kfree(external_name(dentry)); | |
1659 | kmem_cache_free(dentry_cache, dentry); | |
1660 | return NULL; | |
1661 | } | |
1662 | } | |
1663 | ||
3e880fb5 | 1664 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1665 | |
1da177e4 LT |
1666 | return dentry; |
1667 | } | |
a4464dbc AV |
1668 | |
1669 | /** | |
1670 | * d_alloc - allocate a dcache entry | |
1671 | * @parent: parent of entry to allocate | |
1672 | * @name: qstr of the name | |
1673 | * | |
1674 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1675 | * available. On a success the dentry is returned. The name passed in is | |
1676 | * copied and the copy passed in may be reused after this call. | |
1677 | */ | |
1678 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1679 | { | |
1680 | struct dentry *dentry = __d_alloc(parent->d_sb, name); | |
1681 | if (!dentry) | |
1682 | return NULL; | |
3d56c25e | 1683 | dentry->d_flags |= DCACHE_RCUACCESS; |
a4464dbc AV |
1684 | spin_lock(&parent->d_lock); |
1685 | /* | |
1686 | * don't need child lock because it is not subject | |
1687 | * to concurrency here | |
1688 | */ | |
1689 | __dget_dlock(parent); | |
1690 | dentry->d_parent = parent; | |
946e51f2 | 1691 | list_add(&dentry->d_child, &parent->d_subdirs); |
a4464dbc AV |
1692 | spin_unlock(&parent->d_lock); |
1693 | ||
1694 | return dentry; | |
1695 | } | |
ec4f8605 | 1696 | EXPORT_SYMBOL(d_alloc); |
1da177e4 | 1697 | |
ba65dc5e AV |
1698 | struct dentry *d_alloc_cursor(struct dentry * parent) |
1699 | { | |
1700 | struct dentry *dentry = __d_alloc(parent->d_sb, NULL); | |
1701 | if (dentry) { | |
1702 | dentry->d_flags |= DCACHE_RCUACCESS | DCACHE_DENTRY_CURSOR; | |
1703 | dentry->d_parent = dget(parent); | |
1704 | } | |
1705 | return dentry; | |
1706 | } | |
1707 | ||
e1a24bb0 BF |
1708 | /** |
1709 | * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) | |
1710 | * @sb: the superblock | |
1711 | * @name: qstr of the name | |
1712 | * | |
1713 | * For a filesystem that just pins its dentries in memory and never | |
1714 | * performs lookups at all, return an unhashed IS_ROOT dentry. | |
1715 | */ | |
4b936885 NP |
1716 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1717 | { | |
e1a24bb0 | 1718 | return __d_alloc(sb, name); |
4b936885 NP |
1719 | } |
1720 | EXPORT_SYMBOL(d_alloc_pseudo); | |
1721 | ||
1da177e4 LT |
1722 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1723 | { | |
1724 | struct qstr q; | |
1725 | ||
1726 | q.name = name; | |
8387ff25 | 1727 | q.hash_len = hashlen_string(parent, name); |
1da177e4 LT |
1728 | return d_alloc(parent, &q); |
1729 | } | |
ef26ca97 | 1730 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1731 | |
fb045adb NP |
1732 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1733 | { | |
6f7f7caa LT |
1734 | WARN_ON_ONCE(dentry->d_op); |
1735 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | | |
fb045adb NP |
1736 | DCACHE_OP_COMPARE | |
1737 | DCACHE_OP_REVALIDATE | | |
ecf3d1f1 | 1738 | DCACHE_OP_WEAK_REVALIDATE | |
4bacc9c9 | 1739 | DCACHE_OP_DELETE | |
d101a125 | 1740 | DCACHE_OP_REAL)); |
fb045adb NP |
1741 | dentry->d_op = op; |
1742 | if (!op) | |
1743 | return; | |
1744 | if (op->d_hash) | |
1745 | dentry->d_flags |= DCACHE_OP_HASH; | |
1746 | if (op->d_compare) | |
1747 | dentry->d_flags |= DCACHE_OP_COMPARE; | |
1748 | if (op->d_revalidate) | |
1749 | dentry->d_flags |= DCACHE_OP_REVALIDATE; | |
ecf3d1f1 JL |
1750 | if (op->d_weak_revalidate) |
1751 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; | |
fb045adb NP |
1752 | if (op->d_delete) |
1753 | dentry->d_flags |= DCACHE_OP_DELETE; | |
f0023bc6 SW |
1754 | if (op->d_prune) |
1755 | dentry->d_flags |= DCACHE_OP_PRUNE; | |
d101a125 MS |
1756 | if (op->d_real) |
1757 | dentry->d_flags |= DCACHE_OP_REAL; | |
fb045adb NP |
1758 | |
1759 | } | |
1760 | EXPORT_SYMBOL(d_set_d_op); | |
1761 | ||
df1a085a DH |
1762 | |
1763 | /* | |
1764 | * d_set_fallthru - Mark a dentry as falling through to a lower layer | |
1765 | * @dentry - The dentry to mark | |
1766 | * | |
1767 | * Mark a dentry as falling through to the lower layer (as set with | |
1768 | * d_pin_lower()). This flag may be recorded on the medium. | |
1769 | */ | |
1770 | void d_set_fallthru(struct dentry *dentry) | |
1771 | { | |
1772 | spin_lock(&dentry->d_lock); | |
1773 | dentry->d_flags |= DCACHE_FALLTHRU; | |
1774 | spin_unlock(&dentry->d_lock); | |
1775 | } | |
1776 | EXPORT_SYMBOL(d_set_fallthru); | |
1777 | ||
b18825a7 DH |
1778 | static unsigned d_flags_for_inode(struct inode *inode) |
1779 | { | |
44bdb5e5 | 1780 | unsigned add_flags = DCACHE_REGULAR_TYPE; |
b18825a7 DH |
1781 | |
1782 | if (!inode) | |
1783 | return DCACHE_MISS_TYPE; | |
1784 | ||
1785 | if (S_ISDIR(inode->i_mode)) { | |
1786 | add_flags = DCACHE_DIRECTORY_TYPE; | |
1787 | if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { | |
1788 | if (unlikely(!inode->i_op->lookup)) | |
1789 | add_flags = DCACHE_AUTODIR_TYPE; | |
1790 | else | |
1791 | inode->i_opflags |= IOP_LOOKUP; | |
1792 | } | |
44bdb5e5 DH |
1793 | goto type_determined; |
1794 | } | |
1795 | ||
1796 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
6b255391 | 1797 | if (unlikely(inode->i_op->get_link)) { |
b18825a7 | 1798 | add_flags = DCACHE_SYMLINK_TYPE; |
44bdb5e5 DH |
1799 | goto type_determined; |
1800 | } | |
1801 | inode->i_opflags |= IOP_NOFOLLOW; | |
b18825a7 DH |
1802 | } |
1803 | ||
44bdb5e5 DH |
1804 | if (unlikely(!S_ISREG(inode->i_mode))) |
1805 | add_flags = DCACHE_SPECIAL_TYPE; | |
1806 | ||
1807 | type_determined: | |
b18825a7 DH |
1808 | if (unlikely(IS_AUTOMOUNT(inode))) |
1809 | add_flags |= DCACHE_NEED_AUTOMOUNT; | |
1810 | return add_flags; | |
1811 | } | |
1812 | ||
360da900 OH |
1813 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1814 | { | |
b18825a7 | 1815 | unsigned add_flags = d_flags_for_inode(inode); |
85c7f810 | 1816 | WARN_ON(d_in_lookup(dentry)); |
b18825a7 | 1817 | |
b23fb0a6 | 1818 | spin_lock(&dentry->d_lock); |
de689f5e | 1819 | hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); |
a528aca7 | 1820 | raw_write_seqcount_begin(&dentry->d_seq); |
4bf46a27 | 1821 | __d_set_inode_and_type(dentry, inode, add_flags); |
a528aca7 | 1822 | raw_write_seqcount_end(&dentry->d_seq); |
affda484 | 1823 | fsnotify_update_flags(dentry); |
b23fb0a6 | 1824 | spin_unlock(&dentry->d_lock); |
360da900 OH |
1825 | } |
1826 | ||
1da177e4 LT |
1827 | /** |
1828 | * d_instantiate - fill in inode information for a dentry | |
1829 | * @entry: dentry to complete | |
1830 | * @inode: inode to attach to this dentry | |
1831 | * | |
1832 | * Fill in inode information in the entry. | |
1833 | * | |
1834 | * This turns negative dentries into productive full members | |
1835 | * of society. | |
1836 | * | |
1837 | * NOTE! This assumes that the inode count has been incremented | |
1838 | * (or otherwise set) by the caller to indicate that it is now | |
1839 | * in use by the dcache. | |
1840 | */ | |
1841 | ||
1842 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1843 | { | |
946e51f2 | 1844 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
de689f5e | 1845 | if (inode) { |
b9680917 | 1846 | security_d_instantiate(entry, inode); |
873feea0 | 1847 | spin_lock(&inode->i_lock); |
de689f5e | 1848 | __d_instantiate(entry, inode); |
873feea0 | 1849 | spin_unlock(&inode->i_lock); |
de689f5e | 1850 | } |
1da177e4 | 1851 | } |
ec4f8605 | 1852 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 | 1853 | |
2d2d3f1e AV |
1854 | /* |
1855 | * This should be equivalent to d_instantiate() + unlock_new_inode(), | |
1856 | * with lockdep-related part of unlock_new_inode() done before | |
1857 | * anything else. Use that instead of open-coding d_instantiate()/ | |
1858 | * unlock_new_inode() combinations. | |
1859 | */ | |
1860 | void d_instantiate_new(struct dentry *entry, struct inode *inode) | |
1861 | { | |
1862 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); | |
1863 | BUG_ON(!inode); | |
1864 | lockdep_annotate_inode_mutex_key(inode); | |
1865 | security_d_instantiate(entry, inode); | |
1866 | spin_lock(&inode->i_lock); | |
1867 | __d_instantiate(entry, inode); | |
1868 | WARN_ON(!(inode->i_state & I_NEW)); | |
1869 | inode->i_state &= ~I_NEW; | |
1870 | smp_mb(); | |
1871 | wake_up_bit(&inode->i_state, __I_NEW); | |
1872 | spin_unlock(&inode->i_lock); | |
1873 | } | |
1874 | EXPORT_SYMBOL(d_instantiate_new); | |
1875 | ||
b70a80e7 MS |
1876 | /** |
1877 | * d_instantiate_no_diralias - instantiate a non-aliased dentry | |
1878 | * @entry: dentry to complete | |
1879 | * @inode: inode to attach to this dentry | |
1880 | * | |
1881 | * Fill in inode information in the entry. If a directory alias is found, then | |
1882 | * return an error (and drop inode). Together with d_materialise_unique() this | |
1883 | * guarantees that a directory inode may never have more than one alias. | |
1884 | */ | |
1885 | int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) | |
1886 | { | |
946e51f2 | 1887 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
b70a80e7 | 1888 | |
b9680917 | 1889 | security_d_instantiate(entry, inode); |
b70a80e7 MS |
1890 | spin_lock(&inode->i_lock); |
1891 | if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { | |
1892 | spin_unlock(&inode->i_lock); | |
1893 | iput(inode); | |
1894 | return -EBUSY; | |
1895 | } | |
1896 | __d_instantiate(entry, inode); | |
1897 | spin_unlock(&inode->i_lock); | |
b70a80e7 MS |
1898 | |
1899 | return 0; | |
1900 | } | |
1901 | EXPORT_SYMBOL(d_instantiate_no_diralias); | |
1902 | ||
adc0e91a AV |
1903 | struct dentry *d_make_root(struct inode *root_inode) |
1904 | { | |
1905 | struct dentry *res = NULL; | |
1906 | ||
1907 | if (root_inode) { | |
798434bd | 1908 | res = __d_alloc(root_inode->i_sb, NULL); |
cfac7df7 AV |
1909 | if (res) { |
1910 | res->d_flags |= DCACHE_RCUACCESS; | |
adc0e91a | 1911 | d_instantiate(res, root_inode); |
cfac7df7 | 1912 | } else { |
adc0e91a | 1913 | iput(root_inode); |
cfac7df7 | 1914 | } |
adc0e91a AV |
1915 | } |
1916 | return res; | |
1917 | } | |
1918 | EXPORT_SYMBOL(d_make_root); | |
1919 | ||
d891eedb BF |
1920 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1921 | { | |
1922 | struct dentry *alias; | |
1923 | ||
b3d9b7a3 | 1924 | if (hlist_empty(&inode->i_dentry)) |
d891eedb | 1925 | return NULL; |
946e51f2 | 1926 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); |
d891eedb BF |
1927 | __dget(alias); |
1928 | return alias; | |
1929 | } | |
1930 | ||
46f72b34 SW |
1931 | /** |
1932 | * d_find_any_alias - find any alias for a given inode | |
1933 | * @inode: inode to find an alias for | |
1934 | * | |
1935 | * If any aliases exist for the given inode, take and return a | |
1936 | * reference for one of them. If no aliases exist, return %NULL. | |
1937 | */ | |
1938 | struct dentry *d_find_any_alias(struct inode *inode) | |
d891eedb BF |
1939 | { |
1940 | struct dentry *de; | |
1941 | ||
1942 | spin_lock(&inode->i_lock); | |
1943 | de = __d_find_any_alias(inode); | |
1944 | spin_unlock(&inode->i_lock); | |
1945 | return de; | |
1946 | } | |
46f72b34 | 1947 | EXPORT_SYMBOL(d_find_any_alias); |
d891eedb | 1948 | |
49c7dd28 | 1949 | static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) |
4ea3ada2 | 1950 | { |
9308a612 CH |
1951 | struct dentry *tmp; |
1952 | struct dentry *res; | |
b18825a7 | 1953 | unsigned add_flags; |
4ea3ada2 CH |
1954 | |
1955 | if (!inode) | |
44003728 | 1956 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1957 | if (IS_ERR(inode)) |
1958 | return ERR_CAST(inode); | |
1959 | ||
d891eedb | 1960 | res = d_find_any_alias(inode); |
9308a612 CH |
1961 | if (res) |
1962 | goto out_iput; | |
1963 | ||
798434bd | 1964 | tmp = __d_alloc(inode->i_sb, NULL); |
9308a612 CH |
1965 | if (!tmp) { |
1966 | res = ERR_PTR(-ENOMEM); | |
1967 | goto out_iput; | |
4ea3ada2 | 1968 | } |
b5c84bf6 | 1969 | |
b9680917 | 1970 | security_d_instantiate(tmp, inode); |
873feea0 | 1971 | spin_lock(&inode->i_lock); |
d891eedb | 1972 | res = __d_find_any_alias(inode); |
9308a612 | 1973 | if (res) { |
873feea0 | 1974 | spin_unlock(&inode->i_lock); |
9308a612 CH |
1975 | dput(tmp); |
1976 | goto out_iput; | |
1977 | } | |
1978 | ||
1979 | /* attach a disconnected dentry */ | |
1a0a397e BF |
1980 | add_flags = d_flags_for_inode(inode); |
1981 | ||
1982 | if (disconnected) | |
1983 | add_flags |= DCACHE_DISCONNECTED; | |
b18825a7 | 1984 | |
9308a612 | 1985 | spin_lock(&tmp->d_lock); |
4bf46a27 | 1986 | __d_set_inode_and_type(tmp, inode, add_flags); |
946e51f2 | 1987 | hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry); |
1879fd6a | 1988 | hlist_bl_lock(&tmp->d_sb->s_anon); |
ceb5bdc2 | 1989 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1879fd6a | 1990 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
9308a612 | 1991 | spin_unlock(&tmp->d_lock); |
873feea0 | 1992 | spin_unlock(&inode->i_lock); |
9308a612 | 1993 | |
9308a612 CH |
1994 | return tmp; |
1995 | ||
1996 | out_iput: | |
1997 | iput(inode); | |
1998 | return res; | |
4ea3ada2 | 1999 | } |
1a0a397e BF |
2000 | |
2001 | /** | |
2002 | * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode | |
2003 | * @inode: inode to allocate the dentry for | |
2004 | * | |
2005 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
2006 | * similar open by handle operations. The returned dentry may be anonymous, | |
2007 | * or may have a full name (if the inode was already in the cache). | |
2008 | * | |
2009 | * When called on a directory inode, we must ensure that the inode only ever | |
2010 | * has one dentry. If a dentry is found, that is returned instead of | |
2011 | * allocating a new one. | |
2012 | * | |
2013 | * On successful return, the reference to the inode has been transferred | |
2014 | * to the dentry. In case of an error the reference on the inode is released. | |
2015 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
2016 | * be passed in and the error will be propagated to the return value, | |
2017 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
2018 | */ | |
2019 | struct dentry *d_obtain_alias(struct inode *inode) | |
2020 | { | |
2021 | return __d_obtain_alias(inode, 1); | |
2022 | } | |
adc48720 | 2023 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 | 2024 | |
1a0a397e BF |
2025 | /** |
2026 | * d_obtain_root - find or allocate a dentry for a given inode | |
2027 | * @inode: inode to allocate the dentry for | |
2028 | * | |
2029 | * Obtain an IS_ROOT dentry for the root of a filesystem. | |
2030 | * | |
2031 | * We must ensure that directory inodes only ever have one dentry. If a | |
2032 | * dentry is found, that is returned instead of allocating a new one. | |
2033 | * | |
2034 | * On successful return, the reference to the inode has been transferred | |
2035 | * to the dentry. In case of an error the reference on the inode is | |
2036 | * released. A %NULL or IS_ERR inode may be passed in and will be the | |
2037 | * error will be propagate to the return value, with a %NULL @inode | |
2038 | * replaced by ERR_PTR(-ESTALE). | |
2039 | */ | |
2040 | struct dentry *d_obtain_root(struct inode *inode) | |
2041 | { | |
2042 | return __d_obtain_alias(inode, 0); | |
2043 | } | |
2044 | EXPORT_SYMBOL(d_obtain_root); | |
2045 | ||
9403540c BN |
2046 | /** |
2047 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
2048 | * @inode: the inode case-insensitive lookup has found | |
2049 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
2050 | * @name: the case-exact name to be associated with the returned dentry | |
2051 | * | |
2052 | * This is to avoid filling the dcache with case-insensitive names to the | |
2053 | * same inode, only the actual correct case is stored in the dcache for | |
2054 | * case-insensitive filesystems. | |
2055 | * | |
2056 | * For a case-insensitive lookup match and if the the case-exact dentry | |
2057 | * already exists in in the dcache, use it and return it. | |
2058 | * | |
2059 | * If no entry exists with the exact case name, allocate new dentry with | |
2060 | * the exact case, and return the spliced entry. | |
2061 | */ | |
e45b590b | 2062 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
2063 | struct qstr *name) |
2064 | { | |
d9171b93 | 2065 | struct dentry *found, *res; |
9403540c | 2066 | |
b6520c81 CH |
2067 | /* |
2068 | * First check if a dentry matching the name already exists, | |
2069 | * if not go ahead and create it now. | |
2070 | */ | |
9403540c | 2071 | found = d_hash_and_lookup(dentry->d_parent, name); |
d9171b93 AV |
2072 | if (found) { |
2073 | iput(inode); | |
2074 | return found; | |
2075 | } | |
2076 | if (d_in_lookup(dentry)) { | |
2077 | found = d_alloc_parallel(dentry->d_parent, name, | |
2078 | dentry->d_wait); | |
2079 | if (IS_ERR(found) || !d_in_lookup(found)) { | |
2080 | iput(inode); | |
2081 | return found; | |
9403540c | 2082 | } |
d9171b93 AV |
2083 | } else { |
2084 | found = d_alloc(dentry->d_parent, name); | |
2085 | if (!found) { | |
2086 | iput(inode); | |
2087 | return ERR_PTR(-ENOMEM); | |
2088 | } | |
2089 | } | |
2090 | res = d_splice_alias(inode, found); | |
2091 | if (res) { | |
2092 | dput(found); | |
2093 | return res; | |
9403540c | 2094 | } |
4f522a24 | 2095 | return found; |
9403540c | 2096 | } |
ec4f8605 | 2097 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 | 2098 | |
12f8ad4b | 2099 | |
d4c91a8f AV |
2100 | static inline bool d_same_name(const struct dentry *dentry, |
2101 | const struct dentry *parent, | |
2102 | const struct qstr *name) | |
12f8ad4b | 2103 | { |
d4c91a8f AV |
2104 | if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) { |
2105 | if (dentry->d_name.len != name->len) | |
2106 | return false; | |
2107 | return dentry_cmp(dentry, name->name, name->len) == 0; | |
12f8ad4b | 2108 | } |
6fa67e70 | 2109 | return parent->d_op->d_compare(dentry, |
d4c91a8f AV |
2110 | dentry->d_name.len, dentry->d_name.name, |
2111 | name) == 0; | |
12f8ad4b LT |
2112 | } |
2113 | ||
31e6b01f NP |
2114 | /** |
2115 | * __d_lookup_rcu - search for a dentry (racy, store-free) | |
2116 | * @parent: parent dentry | |
2117 | * @name: qstr of name we wish to find | |
1f1e6e52 | 2118 | * @seqp: returns d_seq value at the point where the dentry was found |
31e6b01f NP |
2119 | * Returns: dentry, or NULL |
2120 | * | |
2121 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name | |
2122 | * resolution (store-free path walking) design described in | |
2123 | * Documentation/filesystems/path-lookup.txt. | |
2124 | * | |
2125 | * This is not to be used outside core vfs. | |
2126 | * | |
2127 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock | |
2128 | * held, and rcu_read_lock held. The returned dentry must not be stored into | |
2129 | * without taking d_lock and checking d_seq sequence count against @seq | |
2130 | * returned here. | |
2131 | * | |
15570086 | 2132 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
31e6b01f NP |
2133 | * function. |
2134 | * | |
2135 | * Alternatively, __d_lookup_rcu may be called again to look up the child of | |
2136 | * the returned dentry, so long as its parent's seqlock is checked after the | |
2137 | * child is looked up. Thus, an interlocking stepping of sequence lock checks | |
2138 | * is formed, giving integrity down the path walk. | |
12f8ad4b LT |
2139 | * |
2140 | * NOTE! The caller *has* to check the resulting dentry against the sequence | |
2141 | * number we've returned before using any of the resulting dentry state! | |
31e6b01f | 2142 | */ |
8966be90 LT |
2143 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
2144 | const struct qstr *name, | |
da53be12 | 2145 | unsigned *seqp) |
31e6b01f | 2146 | { |
26fe5750 | 2147 | u64 hashlen = name->hash_len; |
31e6b01f | 2148 | const unsigned char *str = name->name; |
8387ff25 | 2149 | struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen)); |
ceb5bdc2 | 2150 | struct hlist_bl_node *node; |
31e6b01f NP |
2151 | struct dentry *dentry; |
2152 | ||
2153 | /* | |
2154 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2155 | * required to prevent single threaded performance regressions | |
2156 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2157 | * Keep the two functions in sync. | |
2158 | */ | |
2159 | ||
2160 | /* | |
2161 | * The hash list is protected using RCU. | |
2162 | * | |
2163 | * Carefully use d_seq when comparing a candidate dentry, to avoid | |
2164 | * races with d_move(). | |
2165 | * | |
2166 | * It is possible that concurrent renames can mess up our list | |
2167 | * walk here and result in missing our dentry, resulting in the | |
2168 | * false-negative result. d_lookup() protects against concurrent | |
2169 | * renames using rename_lock seqlock. | |
2170 | * | |
b0a4bb83 | 2171 | * See Documentation/filesystems/path-lookup.txt for more details. |
31e6b01f | 2172 | */ |
b07ad996 | 2173 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
8966be90 | 2174 | unsigned seq; |
31e6b01f | 2175 | |
31e6b01f | 2176 | seqretry: |
12f8ad4b LT |
2177 | /* |
2178 | * The dentry sequence count protects us from concurrent | |
da53be12 | 2179 | * renames, and thus protects parent and name fields. |
12f8ad4b LT |
2180 | * |
2181 | * The caller must perform a seqcount check in order | |
da53be12 | 2182 | * to do anything useful with the returned dentry. |
12f8ad4b LT |
2183 | * |
2184 | * NOTE! We do a "raw" seqcount_begin here. That means that | |
2185 | * we don't wait for the sequence count to stabilize if it | |
2186 | * is in the middle of a sequence change. If we do the slow | |
2187 | * dentry compare, we will do seqretries until it is stable, | |
2188 | * and if we end up with a successful lookup, we actually | |
2189 | * want to exit RCU lookup anyway. | |
d4c91a8f AV |
2190 | * |
2191 | * Note that raw_seqcount_begin still *does* smp_rmb(), so | |
2192 | * we are still guaranteed NUL-termination of ->d_name.name. | |
12f8ad4b LT |
2193 | */ |
2194 | seq = raw_seqcount_begin(&dentry->d_seq); | |
31e6b01f NP |
2195 | if (dentry->d_parent != parent) |
2196 | continue; | |
2e321806 LT |
2197 | if (d_unhashed(dentry)) |
2198 | continue; | |
12f8ad4b | 2199 | |
830c0f0e | 2200 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
d4c91a8f AV |
2201 | int tlen; |
2202 | const char *tname; | |
26fe5750 LT |
2203 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
2204 | continue; | |
d4c91a8f AV |
2205 | tlen = dentry->d_name.len; |
2206 | tname = dentry->d_name.name; | |
2207 | /* we want a consistent (name,len) pair */ | |
2208 | if (read_seqcount_retry(&dentry->d_seq, seq)) { | |
2209 | cpu_relax(); | |
12f8ad4b LT |
2210 | goto seqretry; |
2211 | } | |
6fa67e70 | 2212 | if (parent->d_op->d_compare(dentry, |
d4c91a8f AV |
2213 | tlen, tname, name) != 0) |
2214 | continue; | |
2215 | } else { | |
2216 | if (dentry->d_name.hash_len != hashlen) | |
2217 | continue; | |
2218 | if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0) | |
2219 | continue; | |
31e6b01f | 2220 | } |
da53be12 | 2221 | *seqp = seq; |
d4c91a8f | 2222 | return dentry; |
31e6b01f NP |
2223 | } |
2224 | return NULL; | |
2225 | } | |
2226 | ||
1da177e4 LT |
2227 | /** |
2228 | * d_lookup - search for a dentry | |
2229 | * @parent: parent dentry | |
2230 | * @name: qstr of name we wish to find | |
b04f784e | 2231 | * Returns: dentry, or NULL |
1da177e4 | 2232 | * |
b04f784e NP |
2233 | * d_lookup searches the children of the parent dentry for the name in |
2234 | * question. If the dentry is found its reference count is incremented and the | |
2235 | * dentry is returned. The caller must use dput to free the entry when it has | |
2236 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 2237 | */ |
da2d8455 | 2238 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 | 2239 | { |
31e6b01f | 2240 | struct dentry *dentry; |
949854d0 | 2241 | unsigned seq; |
1da177e4 | 2242 | |
b8314f93 DY |
2243 | do { |
2244 | seq = read_seqbegin(&rename_lock); | |
2245 | dentry = __d_lookup(parent, name); | |
2246 | if (dentry) | |
1da177e4 LT |
2247 | break; |
2248 | } while (read_seqretry(&rename_lock, seq)); | |
2249 | return dentry; | |
2250 | } | |
ec4f8605 | 2251 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 2252 | |
31e6b01f | 2253 | /** |
b04f784e NP |
2254 | * __d_lookup - search for a dentry (racy) |
2255 | * @parent: parent dentry | |
2256 | * @name: qstr of name we wish to find | |
2257 | * Returns: dentry, or NULL | |
2258 | * | |
2259 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
2260 | * false-negative result due to unrelated rename activity. | |
2261 | * | |
2262 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
2263 | * however it must be used carefully, eg. with a following d_lookup in | |
2264 | * the case of failure. | |
2265 | * | |
2266 | * __d_lookup callers must be commented. | |
2267 | */ | |
a713ca2a | 2268 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4 | 2269 | { |
1da177e4 | 2270 | unsigned int hash = name->hash; |
8387ff25 | 2271 | struct hlist_bl_head *b = d_hash(hash); |
ceb5bdc2 | 2272 | struct hlist_bl_node *node; |
31e6b01f | 2273 | struct dentry *found = NULL; |
665a7583 | 2274 | struct dentry *dentry; |
1da177e4 | 2275 | |
31e6b01f NP |
2276 | /* |
2277 | * Note: There is significant duplication with __d_lookup_rcu which is | |
2278 | * required to prevent single threaded performance regressions | |
2279 | * especially on architectures where smp_rmb (in seqcounts) are costly. | |
2280 | * Keep the two functions in sync. | |
2281 | */ | |
2282 | ||
b04f784e NP |
2283 | /* |
2284 | * The hash list is protected using RCU. | |
2285 | * | |
2286 | * Take d_lock when comparing a candidate dentry, to avoid races | |
2287 | * with d_move(). | |
2288 | * | |
2289 | * It is possible that concurrent renames can mess up our list | |
2290 | * walk here and result in missing our dentry, resulting in the | |
2291 | * false-negative result. d_lookup() protects against concurrent | |
2292 | * renames using rename_lock seqlock. | |
2293 | * | |
b0a4bb83 | 2294 | * See Documentation/filesystems/path-lookup.txt for more details. |
b04f784e | 2295 | */ |
1da177e4 LT |
2296 | rcu_read_lock(); |
2297 | ||
b07ad996 | 2298 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1da177e4 | 2299 | |
1da177e4 LT |
2300 | if (dentry->d_name.hash != hash) |
2301 | continue; | |
1da177e4 LT |
2302 | |
2303 | spin_lock(&dentry->d_lock); | |
1da177e4 LT |
2304 | if (dentry->d_parent != parent) |
2305 | goto next; | |
d0185c08 LT |
2306 | if (d_unhashed(dentry)) |
2307 | goto next; | |
2308 | ||
d4c91a8f AV |
2309 | if (!d_same_name(dentry, parent, name)) |
2310 | goto next; | |
1da177e4 | 2311 | |
98474236 | 2312 | dentry->d_lockref.count++; |
d0185c08 | 2313 | found = dentry; |
1da177e4 LT |
2314 | spin_unlock(&dentry->d_lock); |
2315 | break; | |
2316 | next: | |
2317 | spin_unlock(&dentry->d_lock); | |
2318 | } | |
2319 | rcu_read_unlock(); | |
2320 | ||
2321 | return found; | |
2322 | } | |
2323 | ||
3e7e241f EB |
2324 | /** |
2325 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
2326 | * @dir: Directory to search in | |
2327 | * @name: qstr of name we wish to find | |
2328 | * | |
4f522a24 | 2329 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
3e7e241f EB |
2330 | */ |
2331 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
2332 | { | |
3e7e241f EB |
2333 | /* |
2334 | * Check for a fs-specific hash function. Note that we must | |
2335 | * calculate the standard hash first, as the d_op->d_hash() | |
2336 | * routine may choose to leave the hash value unchanged. | |
2337 | */ | |
8387ff25 | 2338 | name->hash = full_name_hash(dir, name->name, name->len); |
fb045adb | 2339 | if (dir->d_flags & DCACHE_OP_HASH) { |
da53be12 | 2340 | int err = dir->d_op->d_hash(dir, name); |
4f522a24 AV |
2341 | if (unlikely(err < 0)) |
2342 | return ERR_PTR(err); | |
3e7e241f | 2343 | } |
4f522a24 | 2344 | return d_lookup(dir, name); |
3e7e241f | 2345 | } |
4f522a24 | 2346 | EXPORT_SYMBOL(d_hash_and_lookup); |
3e7e241f | 2347 | |
1da177e4 LT |
2348 | /* |
2349 | * When a file is deleted, we have two options: | |
2350 | * - turn this dentry into a negative dentry | |
2351 | * - unhash this dentry and free it. | |
2352 | * | |
2353 | * Usually, we want to just turn this into | |
2354 | * a negative dentry, but if anybody else is | |
2355 | * currently using the dentry or the inode | |
2356 | * we can't do that and we fall back on removing | |
2357 | * it from the hash queues and waiting for | |
2358 | * it to be deleted later when it has no users | |
2359 | */ | |
2360 | ||
2361 | /** | |
2362 | * d_delete - delete a dentry | |
2363 | * @dentry: The dentry to delete | |
2364 | * | |
2365 | * Turn the dentry into a negative dentry if possible, otherwise | |
2366 | * remove it from the hash queues so it can be deleted later | |
2367 | */ | |
2368 | ||
2369 | void d_delete(struct dentry * dentry) | |
2370 | { | |
873feea0 | 2371 | struct inode *inode; |
7a91bf7f | 2372 | int isdir = 0; |
1da177e4 LT |
2373 | /* |
2374 | * Are we the only user? | |
2375 | */ | |
357f8e65 | 2376 | again: |
1da177e4 | 2377 | spin_lock(&dentry->d_lock); |
873feea0 NP |
2378 | inode = dentry->d_inode; |
2379 | isdir = S_ISDIR(inode->i_mode); | |
98474236 | 2380 | if (dentry->d_lockref.count == 1) { |
1fe0c023 | 2381 | if (!spin_trylock(&inode->i_lock)) { |
357f8e65 NP |
2382 | spin_unlock(&dentry->d_lock); |
2383 | cpu_relax(); | |
2384 | goto again; | |
2385 | } | |
13e3c5e5 | 2386 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
31e6b01f | 2387 | dentry_unlink_inode(dentry); |
7a91bf7f | 2388 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
2389 | return; |
2390 | } | |
2391 | ||
2392 | if (!d_unhashed(dentry)) | |
2393 | __d_drop(dentry); | |
2394 | ||
2395 | spin_unlock(&dentry->d_lock); | |
7a91bf7f JM |
2396 | |
2397 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 2398 | } |
ec4f8605 | 2399 | EXPORT_SYMBOL(d_delete); |
1da177e4 | 2400 | |
15d3c589 | 2401 | static void __d_rehash(struct dentry *entry) |
1da177e4 | 2402 | { |
15d3c589 | 2403 | struct hlist_bl_head *b = d_hash(entry->d_name.hash); |
3aa66ba5 | 2404 | |
1879fd6a | 2405 | hlist_bl_lock(b); |
b07ad996 | 2406 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
1879fd6a | 2407 | hlist_bl_unlock(b); |
1da177e4 LT |
2408 | } |
2409 | ||
2410 | /** | |
2411 | * d_rehash - add an entry back to the hash | |
2412 | * @entry: dentry to add to the hash | |
2413 | * | |
2414 | * Adds a dentry to the hash according to its name. | |
2415 | */ | |
2416 | ||
2417 | void d_rehash(struct dentry * entry) | |
2418 | { | |
1da177e4 | 2419 | spin_lock(&entry->d_lock); |
15d3c589 | 2420 | __d_rehash(entry); |
1da177e4 | 2421 | spin_unlock(&entry->d_lock); |
1da177e4 | 2422 | } |
ec4f8605 | 2423 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 2424 | |
84e710da AV |
2425 | static inline unsigned start_dir_add(struct inode *dir) |
2426 | { | |
2427 | ||
2428 | for (;;) { | |
2429 | unsigned n = dir->i_dir_seq; | |
2430 | if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n) | |
2431 | return n; | |
2432 | cpu_relax(); | |
2433 | } | |
2434 | } | |
2435 | ||
2436 | static inline void end_dir_add(struct inode *dir, unsigned n) | |
2437 | { | |
2438 | smp_store_release(&dir->i_dir_seq, n + 2); | |
2439 | } | |
2440 | ||
d9171b93 AV |
2441 | static void d_wait_lookup(struct dentry *dentry) |
2442 | { | |
2443 | if (d_in_lookup(dentry)) { | |
2444 | DECLARE_WAITQUEUE(wait, current); | |
2445 | add_wait_queue(dentry->d_wait, &wait); | |
2446 | do { | |
2447 | set_current_state(TASK_UNINTERRUPTIBLE); | |
2448 | spin_unlock(&dentry->d_lock); | |
2449 | schedule(); | |
2450 | spin_lock(&dentry->d_lock); | |
2451 | } while (d_in_lookup(dentry)); | |
2452 | } | |
2453 | } | |
2454 | ||
94bdd655 | 2455 | struct dentry *d_alloc_parallel(struct dentry *parent, |
d9171b93 AV |
2456 | const struct qstr *name, |
2457 | wait_queue_head_t *wq) | |
94bdd655 | 2458 | { |
94bdd655 | 2459 | unsigned int hash = name->hash; |
94bdd655 AV |
2460 | struct hlist_bl_head *b = in_lookup_hash(parent, hash); |
2461 | struct hlist_bl_node *node; | |
2462 | struct dentry *new = d_alloc(parent, name); | |
2463 | struct dentry *dentry; | |
2464 | unsigned seq, r_seq, d_seq; | |
2465 | ||
2466 | if (unlikely(!new)) | |
2467 | return ERR_PTR(-ENOMEM); | |
2468 | ||
2469 | retry: | |
2470 | rcu_read_lock(); | |
bcefedb8 | 2471 | seq = smp_load_acquire(&parent->d_inode->i_dir_seq); |
94bdd655 AV |
2472 | r_seq = read_seqbegin(&rename_lock); |
2473 | dentry = __d_lookup_rcu(parent, name, &d_seq); | |
2474 | if (unlikely(dentry)) { | |
2475 | if (!lockref_get_not_dead(&dentry->d_lockref)) { | |
2476 | rcu_read_unlock(); | |
2477 | goto retry; | |
2478 | } | |
2479 | if (read_seqcount_retry(&dentry->d_seq, d_seq)) { | |
2480 | rcu_read_unlock(); | |
2481 | dput(dentry); | |
2482 | goto retry; | |
2483 | } | |
2484 | rcu_read_unlock(); | |
2485 | dput(new); | |
2486 | return dentry; | |
2487 | } | |
2488 | if (unlikely(read_seqretry(&rename_lock, r_seq))) { | |
2489 | rcu_read_unlock(); | |
2490 | goto retry; | |
2491 | } | |
bcefedb8 WD |
2492 | |
2493 | if (unlikely(seq & 1)) { | |
2494 | rcu_read_unlock(); | |
2495 | goto retry; | |
2496 | } | |
2497 | ||
94bdd655 | 2498 | hlist_bl_lock(b); |
527ed41f | 2499 | if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) { |
94bdd655 AV |
2500 | hlist_bl_unlock(b); |
2501 | rcu_read_unlock(); | |
2502 | goto retry; | |
2503 | } | |
94bdd655 AV |
2504 | /* |
2505 | * No changes for the parent since the beginning of d_lookup(). | |
2506 | * Since all removals from the chain happen with hlist_bl_lock(), | |
2507 | * any potential in-lookup matches are going to stay here until | |
2508 | * we unlock the chain. All fields are stable in everything | |
2509 | * we encounter. | |
2510 | */ | |
2511 | hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) { | |
2512 | if (dentry->d_name.hash != hash) | |
2513 | continue; | |
2514 | if (dentry->d_parent != parent) | |
2515 | continue; | |
d4c91a8f AV |
2516 | if (!d_same_name(dentry, parent, name)) |
2517 | continue; | |
94bdd655 | 2518 | hlist_bl_unlock(b); |
e7d6ef97 AV |
2519 | /* now we can try to grab a reference */ |
2520 | if (!lockref_get_not_dead(&dentry->d_lockref)) { | |
2521 | rcu_read_unlock(); | |
2522 | goto retry; | |
2523 | } | |
2524 | ||
2525 | rcu_read_unlock(); | |
2526 | /* | |
2527 | * somebody is likely to be still doing lookup for it; | |
2528 | * wait for them to finish | |
2529 | */ | |
d9171b93 AV |
2530 | spin_lock(&dentry->d_lock); |
2531 | d_wait_lookup(dentry); | |
2532 | /* | |
2533 | * it's not in-lookup anymore; in principle we should repeat | |
2534 | * everything from dcache lookup, but it's likely to be what | |
2535 | * d_lookup() would've found anyway. If it is, just return it; | |
2536 | * otherwise we really have to repeat the whole thing. | |
2537 | */ | |
2538 | if (unlikely(dentry->d_name.hash != hash)) | |
2539 | goto mismatch; | |
2540 | if (unlikely(dentry->d_parent != parent)) | |
2541 | goto mismatch; | |
2542 | if (unlikely(d_unhashed(dentry))) | |
2543 | goto mismatch; | |
d4c91a8f AV |
2544 | if (unlikely(!d_same_name(dentry, parent, name))) |
2545 | goto mismatch; | |
d9171b93 AV |
2546 | /* OK, it *is* a hashed match; return it */ |
2547 | spin_unlock(&dentry->d_lock); | |
94bdd655 AV |
2548 | dput(new); |
2549 | return dentry; | |
2550 | } | |
e7d6ef97 | 2551 | rcu_read_unlock(); |
94bdd655 AV |
2552 | /* we can't take ->d_lock here; it's OK, though. */ |
2553 | new->d_flags |= DCACHE_PAR_LOOKUP; | |
d9171b93 | 2554 | new->d_wait = wq; |
94bdd655 AV |
2555 | hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b); |
2556 | hlist_bl_unlock(b); | |
2557 | return new; | |
d9171b93 AV |
2558 | mismatch: |
2559 | spin_unlock(&dentry->d_lock); | |
2560 | dput(dentry); | |
2561 | goto retry; | |
94bdd655 AV |
2562 | } |
2563 | EXPORT_SYMBOL(d_alloc_parallel); | |
2564 | ||
85c7f810 AV |
2565 | void __d_lookup_done(struct dentry *dentry) |
2566 | { | |
94bdd655 AV |
2567 | struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent, |
2568 | dentry->d_name.hash); | |
2569 | hlist_bl_lock(b); | |
85c7f810 | 2570 | dentry->d_flags &= ~DCACHE_PAR_LOOKUP; |
94bdd655 | 2571 | __hlist_bl_del(&dentry->d_u.d_in_lookup_hash); |
d9171b93 AV |
2572 | wake_up_all(dentry->d_wait); |
2573 | dentry->d_wait = NULL; | |
94bdd655 AV |
2574 | hlist_bl_unlock(b); |
2575 | INIT_HLIST_NODE(&dentry->d_u.d_alias); | |
d9171b93 | 2576 | INIT_LIST_HEAD(&dentry->d_lru); |
85c7f810 AV |
2577 | } |
2578 | EXPORT_SYMBOL(__d_lookup_done); | |
ed782b5a AV |
2579 | |
2580 | /* inode->i_lock held if inode is non-NULL */ | |
2581 | ||
2582 | static inline void __d_add(struct dentry *dentry, struct inode *inode) | |
2583 | { | |
84e710da AV |
2584 | struct inode *dir = NULL; |
2585 | unsigned n; | |
0568d705 | 2586 | spin_lock(&dentry->d_lock); |
84e710da AV |
2587 | if (unlikely(d_in_lookup(dentry))) { |
2588 | dir = dentry->d_parent->d_inode; | |
2589 | n = start_dir_add(dir); | |
85c7f810 | 2590 | __d_lookup_done(dentry); |
84e710da | 2591 | } |
ed782b5a | 2592 | if (inode) { |
0568d705 AV |
2593 | unsigned add_flags = d_flags_for_inode(inode); |
2594 | hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); | |
2595 | raw_write_seqcount_begin(&dentry->d_seq); | |
2596 | __d_set_inode_and_type(dentry, inode, add_flags); | |
2597 | raw_write_seqcount_end(&dentry->d_seq); | |
affda484 | 2598 | fsnotify_update_flags(dentry); |
ed782b5a | 2599 | } |
15d3c589 | 2600 | __d_rehash(dentry); |
84e710da AV |
2601 | if (dir) |
2602 | end_dir_add(dir, n); | |
0568d705 AV |
2603 | spin_unlock(&dentry->d_lock); |
2604 | if (inode) | |
2605 | spin_unlock(&inode->i_lock); | |
ed782b5a AV |
2606 | } |
2607 | ||
34d0d19d AV |
2608 | /** |
2609 | * d_add - add dentry to hash queues | |
2610 | * @entry: dentry to add | |
2611 | * @inode: The inode to attach to this dentry | |
2612 | * | |
2613 | * This adds the entry to the hash queues and initializes @inode. | |
2614 | * The entry was actually filled in earlier during d_alloc(). | |
2615 | */ | |
2616 | ||
2617 | void d_add(struct dentry *entry, struct inode *inode) | |
2618 | { | |
b9680917 AV |
2619 | if (inode) { |
2620 | security_d_instantiate(entry, inode); | |
ed782b5a | 2621 | spin_lock(&inode->i_lock); |
b9680917 | 2622 | } |
ed782b5a | 2623 | __d_add(entry, inode); |
34d0d19d AV |
2624 | } |
2625 | EXPORT_SYMBOL(d_add); | |
2626 | ||
668d0cd5 AV |
2627 | /** |
2628 | * d_exact_alias - find and hash an exact unhashed alias | |
2629 | * @entry: dentry to add | |
2630 | * @inode: The inode to go with this dentry | |
2631 | * | |
2632 | * If an unhashed dentry with the same name/parent and desired | |
2633 | * inode already exists, hash and return it. Otherwise, return | |
2634 | * NULL. | |
2635 | * | |
2636 | * Parent directory should be locked. | |
2637 | */ | |
2638 | struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) | |
2639 | { | |
2640 | struct dentry *alias; | |
668d0cd5 AV |
2641 | unsigned int hash = entry->d_name.hash; |
2642 | ||
2643 | spin_lock(&inode->i_lock); | |
2644 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { | |
2645 | /* | |
2646 | * Don't need alias->d_lock here, because aliases with | |
2647 | * d_parent == entry->d_parent are not subject to name or | |
2648 | * parent changes, because the parent inode i_mutex is held. | |
2649 | */ | |
2650 | if (alias->d_name.hash != hash) | |
2651 | continue; | |
2652 | if (alias->d_parent != entry->d_parent) | |
2653 | continue; | |
d4c91a8f | 2654 | if (!d_same_name(alias, entry->d_parent, &entry->d_name)) |
668d0cd5 AV |
2655 | continue; |
2656 | spin_lock(&alias->d_lock); | |
2657 | if (!d_unhashed(alias)) { | |
2658 | spin_unlock(&alias->d_lock); | |
2659 | alias = NULL; | |
2660 | } else { | |
2661 | __dget_dlock(alias); | |
15d3c589 | 2662 | __d_rehash(alias); |
668d0cd5 AV |
2663 | spin_unlock(&alias->d_lock); |
2664 | } | |
2665 | spin_unlock(&inode->i_lock); | |
2666 | return alias; | |
2667 | } | |
2668 | spin_unlock(&inode->i_lock); | |
2669 | return NULL; | |
2670 | } | |
2671 | EXPORT_SYMBOL(d_exact_alias); | |
2672 | ||
fb2d5b86 NP |
2673 | /** |
2674 | * dentry_update_name_case - update case insensitive dentry with a new name | |
2675 | * @dentry: dentry to be updated | |
2676 | * @name: new name | |
2677 | * | |
2678 | * Update a case insensitive dentry with new case of name. | |
2679 | * | |
2680 | * dentry must have been returned by d_lookup with name @name. Old and new | |
2681 | * name lengths must match (ie. no d_compare which allows mismatched name | |
2682 | * lengths). | |
2683 | * | |
2684 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
2685 | * keep renames and concurrent inserts, and readdir(2) away). | |
2686 | */ | |
9aba36de | 2687 | void dentry_update_name_case(struct dentry *dentry, const struct qstr *name) |
fb2d5b86 | 2688 | { |
5955102c | 2689 | BUG_ON(!inode_is_locked(dentry->d_parent->d_inode)); |
fb2d5b86 NP |
2690 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2691 | ||
fb2d5b86 | 2692 | spin_lock(&dentry->d_lock); |
31e6b01f | 2693 | write_seqcount_begin(&dentry->d_seq); |
fb2d5b86 | 2694 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
31e6b01f | 2695 | write_seqcount_end(&dentry->d_seq); |
fb2d5b86 | 2696 | spin_unlock(&dentry->d_lock); |
fb2d5b86 NP |
2697 | } |
2698 | EXPORT_SYMBOL(dentry_update_name_case); | |
2699 | ||
8d85b484 | 2700 | static void swap_names(struct dentry *dentry, struct dentry *target) |
1da177e4 | 2701 | { |
8d85b484 AV |
2702 | if (unlikely(dname_external(target))) { |
2703 | if (unlikely(dname_external(dentry))) { | |
1da177e4 LT |
2704 | /* |
2705 | * Both external: swap the pointers | |
2706 | */ | |
9a8d5bb4 | 2707 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
2708 | } else { |
2709 | /* | |
2710 | * dentry:internal, target:external. Steal target's | |
2711 | * storage and make target internal. | |
2712 | */ | |
321bcf92 BF |
2713 | memcpy(target->d_iname, dentry->d_name.name, |
2714 | dentry->d_name.len + 1); | |
1da177e4 LT |
2715 | dentry->d_name.name = target->d_name.name; |
2716 | target->d_name.name = target->d_iname; | |
2717 | } | |
2718 | } else { | |
8d85b484 | 2719 | if (unlikely(dname_external(dentry))) { |
1da177e4 LT |
2720 | /* |
2721 | * dentry:external, target:internal. Give dentry's | |
2722 | * storage to target and make dentry internal | |
2723 | */ | |
2724 | memcpy(dentry->d_iname, target->d_name.name, | |
2725 | target->d_name.len + 1); | |
2726 | target->d_name.name = dentry->d_name.name; | |
2727 | dentry->d_name.name = dentry->d_iname; | |
2728 | } else { | |
2729 | /* | |
da1ce067 | 2730 | * Both are internal. |
1da177e4 | 2731 | */ |
da1ce067 MS |
2732 | unsigned int i; |
2733 | BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); | |
08d4f772 MP |
2734 | kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN); |
2735 | kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN); | |
da1ce067 MS |
2736 | for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { |
2737 | swap(((long *) &dentry->d_iname)[i], | |
2738 | ((long *) &target->d_iname)[i]); | |
2739 | } | |
1da177e4 LT |
2740 | } |
2741 | } | |
a28ddb87 | 2742 | swap(dentry->d_name.hash_len, target->d_name.hash_len); |
1da177e4 LT |
2743 | } |
2744 | ||
8d85b484 AV |
2745 | static void copy_name(struct dentry *dentry, struct dentry *target) |
2746 | { | |
2747 | struct external_name *old_name = NULL; | |
2748 | if (unlikely(dname_external(dentry))) | |
2749 | old_name = external_name(dentry); | |
2750 | if (unlikely(dname_external(target))) { | |
2751 | atomic_inc(&external_name(target)->u.count); | |
2752 | dentry->d_name = target->d_name; | |
2753 | } else { | |
2754 | memcpy(dentry->d_iname, target->d_name.name, | |
2755 | target->d_name.len + 1); | |
2756 | dentry->d_name.name = dentry->d_iname; | |
2757 | dentry->d_name.hash_len = target->d_name.hash_len; | |
2758 | } | |
2759 | if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) | |
2760 | kfree_rcu(old_name, u.head); | |
2761 | } | |
2762 | ||
2fd6b7f5 NP |
2763 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2764 | { | |
2765 | /* | |
2766 | * XXXX: do we really need to take target->d_lock? | |
2767 | */ | |
2768 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) | |
2769 | spin_lock(&target->d_parent->d_lock); | |
2770 | else { | |
2771 | if (d_ancestor(dentry->d_parent, target->d_parent)) { | |
2772 | spin_lock(&dentry->d_parent->d_lock); | |
2773 | spin_lock_nested(&target->d_parent->d_lock, | |
2774 | DENTRY_D_LOCK_NESTED); | |
2775 | } else { | |
2776 | spin_lock(&target->d_parent->d_lock); | |
2777 | spin_lock_nested(&dentry->d_parent->d_lock, | |
2778 | DENTRY_D_LOCK_NESTED); | |
2779 | } | |
2780 | } | |
2781 | if (target < dentry) { | |
2782 | spin_lock_nested(&target->d_lock, 2); | |
2783 | spin_lock_nested(&dentry->d_lock, 3); | |
2784 | } else { | |
2785 | spin_lock_nested(&dentry->d_lock, 2); | |
2786 | spin_lock_nested(&target->d_lock, 3); | |
2787 | } | |
2788 | } | |
2789 | ||
986c0194 | 2790 | static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target) |
2fd6b7f5 NP |
2791 | { |
2792 | if (target->d_parent != dentry->d_parent) | |
2793 | spin_unlock(&dentry->d_parent->d_lock); | |
2794 | if (target->d_parent != target) | |
2795 | spin_unlock(&target->d_parent->d_lock); | |
986c0194 AV |
2796 | spin_unlock(&target->d_lock); |
2797 | spin_unlock(&dentry->d_lock); | |
2fd6b7f5 NP |
2798 | } |
2799 | ||
1da177e4 | 2800 | /* |
2fd6b7f5 NP |
2801 | * When switching names, the actual string doesn't strictly have to |
2802 | * be preserved in the target - because we're dropping the target | |
2803 | * anyway. As such, we can just do a simple memcpy() to copy over | |
d2fa4a84 ME |
2804 | * the new name before we switch, unless we are going to rehash |
2805 | * it. Note that if we *do* unhash the target, we are not allowed | |
2806 | * to rehash it without giving it a new name/hash key - whether | |
2807 | * we swap or overwrite the names here, resulting name won't match | |
2808 | * the reality in filesystem; it's only there for d_path() purposes. | |
2809 | * Note that all of this is happening under rename_lock, so the | |
2810 | * any hash lookup seeing it in the middle of manipulations will | |
2811 | * be discarded anyway. So we do not care what happens to the hash | |
2812 | * key in that case. | |
1da177e4 | 2813 | */ |
9eaef27b | 2814 | /* |
18367501 | 2815 | * __d_move - move a dentry |
1da177e4 LT |
2816 | * @dentry: entry to move |
2817 | * @target: new dentry | |
da1ce067 | 2818 | * @exchange: exchange the two dentries |
1da177e4 LT |
2819 | * |
2820 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2821 | * dcache entries should not be moved in this way. Caller must hold |
2822 | * rename_lock, the i_mutex of the source and target directories, | |
2823 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). | |
1da177e4 | 2824 | */ |
da1ce067 MS |
2825 | static void __d_move(struct dentry *dentry, struct dentry *target, |
2826 | bool exchange) | |
1da177e4 | 2827 | { |
84e710da AV |
2828 | struct inode *dir = NULL; |
2829 | unsigned n; | |
1da177e4 LT |
2830 | if (!dentry->d_inode) |
2831 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
2832 | ||
2fd6b7f5 NP |
2833 | BUG_ON(d_ancestor(dentry, target)); |
2834 | BUG_ON(d_ancestor(target, dentry)); | |
2835 | ||
2fd6b7f5 | 2836 | dentry_lock_for_move(dentry, target); |
84e710da AV |
2837 | if (unlikely(d_in_lookup(target))) { |
2838 | dir = target->d_parent->d_inode; | |
2839 | n = start_dir_add(dir); | |
85c7f810 | 2840 | __d_lookup_done(target); |
84e710da | 2841 | } |
1da177e4 | 2842 | |
31e6b01f | 2843 | write_seqcount_begin(&dentry->d_seq); |
1ca7d67c | 2844 | write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); |
31e6b01f | 2845 | |
15d3c589 | 2846 | /* unhash both */ |
3aa66ba5 N |
2847 | /* ___d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2848 | ___d_drop(dentry); | |
2849 | ___d_drop(target); | |
1da177e4 | 2850 | |
1da177e4 | 2851 | /* Switch the names.. */ |
8d85b484 AV |
2852 | if (exchange) |
2853 | swap_names(dentry, target); | |
2854 | else | |
2855 | copy_name(dentry, target); | |
1da177e4 | 2856 | |
15d3c589 AV |
2857 | /* rehash in new place(s) */ |
2858 | __d_rehash(dentry); | |
2859 | if (exchange) | |
2860 | __d_rehash(target); | |
3aa66ba5 N |
2861 | else |
2862 | target->d_hash.pprev = NULL; | |
15d3c589 | 2863 | |
63cf427a | 2864 | /* ... and switch them in the tree */ |
1da177e4 | 2865 | if (IS_ROOT(dentry)) { |
63cf427a | 2866 | /* splicing a tree */ |
3d56c25e | 2867 | dentry->d_flags |= DCACHE_RCUACCESS; |
1da177e4 LT |
2868 | dentry->d_parent = target->d_parent; |
2869 | target->d_parent = target; | |
946e51f2 AV |
2870 | list_del_init(&target->d_child); |
2871 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); | |
1da177e4 | 2872 | } else { |
63cf427a | 2873 | /* swapping two dentries */ |
9a8d5bb4 | 2874 | swap(dentry->d_parent, target->d_parent); |
946e51f2 AV |
2875 | list_move(&target->d_child, &target->d_parent->d_subdirs); |
2876 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); | |
63cf427a | 2877 | if (exchange) |
affda484 AV |
2878 | fsnotify_update_flags(target); |
2879 | fsnotify_update_flags(dentry); | |
1da177e4 LT |
2880 | } |
2881 | ||
31e6b01f NP |
2882 | write_seqcount_end(&target->d_seq); |
2883 | write_seqcount_end(&dentry->d_seq); | |
2884 | ||
84e710da AV |
2885 | if (dir) |
2886 | end_dir_add(dir, n); | |
986c0194 | 2887 | dentry_unlock_for_move(dentry, target); |
18367501 AV |
2888 | } |
2889 | ||
2890 | /* | |
2891 | * d_move - move a dentry | |
2892 | * @dentry: entry to move | |
2893 | * @target: new dentry | |
2894 | * | |
2895 | * Update the dcache to reflect the move of a file name. Negative | |
c46c8877 JL |
2896 | * dcache entries should not be moved in this way. See the locking |
2897 | * requirements for __d_move. | |
18367501 AV |
2898 | */ |
2899 | void d_move(struct dentry *dentry, struct dentry *target) | |
2900 | { | |
2901 | write_seqlock(&rename_lock); | |
da1ce067 | 2902 | __d_move(dentry, target, false); |
1da177e4 | 2903 | write_sequnlock(&rename_lock); |
9eaef27b | 2904 | } |
ec4f8605 | 2905 | EXPORT_SYMBOL(d_move); |
1da177e4 | 2906 | |
da1ce067 MS |
2907 | /* |
2908 | * d_exchange - exchange two dentries | |
2909 | * @dentry1: first dentry | |
2910 | * @dentry2: second dentry | |
2911 | */ | |
2912 | void d_exchange(struct dentry *dentry1, struct dentry *dentry2) | |
2913 | { | |
2914 | write_seqlock(&rename_lock); | |
2915 | ||
2916 | WARN_ON(!dentry1->d_inode); | |
2917 | WARN_ON(!dentry2->d_inode); | |
2918 | WARN_ON(IS_ROOT(dentry1)); | |
2919 | WARN_ON(IS_ROOT(dentry2)); | |
2920 | ||
2921 | __d_move(dentry1, dentry2, true); | |
2922 | ||
2923 | write_sequnlock(&rename_lock); | |
2924 | } | |
2925 | ||
e2761a11 OH |
2926 | /** |
2927 | * d_ancestor - search for an ancestor | |
2928 | * @p1: ancestor dentry | |
2929 | * @p2: child dentry | |
2930 | * | |
2931 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
2932 | * an ancestor of p2, else NULL. | |
9eaef27b | 2933 | */ |
e2761a11 | 2934 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
2935 | { |
2936 | struct dentry *p; | |
2937 | ||
871c0067 | 2938 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 2939 | if (p->d_parent == p1) |
e2761a11 | 2940 | return p; |
9eaef27b | 2941 | } |
e2761a11 | 2942 | return NULL; |
9eaef27b TM |
2943 | } |
2944 | ||
2945 | /* | |
2946 | * This helper attempts to cope with remotely renamed directories | |
2947 | * | |
2948 | * It assumes that the caller is already holding | |
a03e283b | 2949 | * dentry->d_parent->d_inode->i_mutex, and rename_lock |
9eaef27b TM |
2950 | * |
2951 | * Note: If ever the locking in lock_rename() changes, then please | |
2952 | * remember to update this too... | |
9eaef27b | 2953 | */ |
b5ae6b15 | 2954 | static int __d_unalias(struct inode *inode, |
873feea0 | 2955 | struct dentry *dentry, struct dentry *alias) |
9eaef27b | 2956 | { |
9902af79 AV |
2957 | struct mutex *m1 = NULL; |
2958 | struct rw_semaphore *m2 = NULL; | |
3d330dc1 | 2959 | int ret = -ESTALE; |
9eaef27b TM |
2960 | |
2961 | /* If alias and dentry share a parent, then no extra locks required */ | |
2962 | if (alias->d_parent == dentry->d_parent) | |
2963 | goto out_unalias; | |
2964 | ||
9eaef27b | 2965 | /* See lock_rename() */ |
9eaef27b TM |
2966 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2967 | goto out_err; | |
2968 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
9902af79 | 2969 | if (!inode_trylock_shared(alias->d_parent->d_inode)) |
9eaef27b | 2970 | goto out_err; |
9902af79 | 2971 | m2 = &alias->d_parent->d_inode->i_rwsem; |
9eaef27b | 2972 | out_unalias: |
8ed936b5 | 2973 | __d_move(alias, dentry, false); |
b5ae6b15 | 2974 | ret = 0; |
9eaef27b | 2975 | out_err: |
9eaef27b | 2976 | if (m2) |
9902af79 | 2977 | up_read(m2); |
9eaef27b TM |
2978 | if (m1) |
2979 | mutex_unlock(m1); | |
2980 | return ret; | |
2981 | } | |
2982 | ||
3f70bd51 BF |
2983 | /** |
2984 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
2985 | * @inode: the inode which may have a disconnected dentry | |
2986 | * @dentry: a negative dentry which we want to point to the inode. | |
2987 | * | |
da093a9b BF |
2988 | * If inode is a directory and has an IS_ROOT alias, then d_move that in |
2989 | * place of the given dentry and return it, else simply d_add the inode | |
2990 | * to the dentry and return NULL. | |
3f70bd51 | 2991 | * |
908790fa BF |
2992 | * If a non-IS_ROOT directory is found, the filesystem is corrupt, and |
2993 | * we should error out: directories can't have multiple aliases. | |
2994 | * | |
3f70bd51 BF |
2995 | * This is needed in the lookup routine of any filesystem that is exportable |
2996 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
2997 | * | |
2998 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
2999 | * is returned. This matches the expected return value of ->lookup. | |
3000 | * | |
3001 | * Cluster filesystems may call this function with a negative, hashed dentry. | |
3002 | * In that case, we know that the inode will be a regular file, and also this | |
3003 | * will only occur during atomic_open. So we need to check for the dentry | |
3004 | * being already hashed only in the final case. | |
3005 | */ | |
3006 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
3007 | { | |
3f70bd51 BF |
3008 | if (IS_ERR(inode)) |
3009 | return ERR_CAST(inode); | |
3010 | ||
770bfad8 DH |
3011 | BUG_ON(!d_unhashed(dentry)); |
3012 | ||
de689f5e | 3013 | if (!inode) |
b5ae6b15 | 3014 | goto out; |
de689f5e | 3015 | |
b9680917 | 3016 | security_d_instantiate(dentry, inode); |
873feea0 | 3017 | spin_lock(&inode->i_lock); |
9eaef27b | 3018 | if (S_ISDIR(inode->i_mode)) { |
b5ae6b15 AV |
3019 | struct dentry *new = __d_find_any_alias(inode); |
3020 | if (unlikely(new)) { | |
a03e283b EB |
3021 | /* The reference to new ensures it remains an alias */ |
3022 | spin_unlock(&inode->i_lock); | |
18367501 | 3023 | write_seqlock(&rename_lock); |
b5ae6b15 AV |
3024 | if (unlikely(d_ancestor(new, dentry))) { |
3025 | write_sequnlock(&rename_lock); | |
b5ae6b15 AV |
3026 | dput(new); |
3027 | new = ERR_PTR(-ELOOP); | |
3028 | pr_warn_ratelimited( | |
3029 | "VFS: Lookup of '%s' in %s %s" | |
3030 | " would have caused loop\n", | |
3031 | dentry->d_name.name, | |
3032 | inode->i_sb->s_type->name, | |
3033 | inode->i_sb->s_id); | |
3034 | } else if (!IS_ROOT(new)) { | |
3035 | int err = __d_unalias(inode, dentry, new); | |
18367501 | 3036 | write_sequnlock(&rename_lock); |
b5ae6b15 AV |
3037 | if (err) { |
3038 | dput(new); | |
3039 | new = ERR_PTR(err); | |
3040 | } | |
18367501 | 3041 | } else { |
b5ae6b15 AV |
3042 | __d_move(new, dentry, false); |
3043 | write_sequnlock(&rename_lock); | |
dd179946 | 3044 | } |
b5ae6b15 AV |
3045 | iput(inode); |
3046 | return new; | |
9eaef27b | 3047 | } |
770bfad8 | 3048 | } |
b5ae6b15 | 3049 | out: |
ed782b5a | 3050 | __d_add(dentry, inode); |
b5ae6b15 | 3051 | return NULL; |
770bfad8 | 3052 | } |
b5ae6b15 | 3053 | EXPORT_SYMBOL(d_splice_alias); |
770bfad8 | 3054 | |
cdd16d02 | 3055 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
3056 | { |
3057 | *buflen -= namelen; | |
3058 | if (*buflen < 0) | |
3059 | return -ENAMETOOLONG; | |
3060 | *buffer -= namelen; | |
3061 | memcpy(*buffer, str, namelen); | |
3062 | return 0; | |
3063 | } | |
3064 | ||
232d2d60 WL |
3065 | /** |
3066 | * prepend_name - prepend a pathname in front of current buffer pointer | |
18129977 WL |
3067 | * @buffer: buffer pointer |
3068 | * @buflen: allocated length of the buffer | |
3069 | * @name: name string and length qstr structure | |
232d2d60 WL |
3070 | * |
3071 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to | |
3072 | * make sure that either the old or the new name pointer and length are | |
3073 | * fetched. However, there may be mismatch between length and pointer. | |
3074 | * The length cannot be trusted, we need to copy it byte-by-byte until | |
3075 | * the length is reached or a null byte is found. It also prepends "/" at | |
3076 | * the beginning of the name. The sequence number check at the caller will | |
3077 | * retry it again when a d_move() does happen. So any garbage in the buffer | |
3078 | * due to mismatched pointer and length will be discarded. | |
6d13f694 AV |
3079 | * |
3080 | * Data dependency barrier is needed to make sure that we see that terminating | |
3081 | * NUL. Alpha strikes again, film at 11... | |
232d2d60 | 3082 | */ |
9aba36de | 3083 | static int prepend_name(char **buffer, int *buflen, const struct qstr *name) |
cdd16d02 | 3084 | { |
232d2d60 WL |
3085 | const char *dname = ACCESS_ONCE(name->name); |
3086 | u32 dlen = ACCESS_ONCE(name->len); | |
3087 | char *p; | |
3088 | ||
6d13f694 AV |
3089 | smp_read_barrier_depends(); |
3090 | ||
232d2d60 | 3091 | *buflen -= dlen + 1; |
e825196d AV |
3092 | if (*buflen < 0) |
3093 | return -ENAMETOOLONG; | |
232d2d60 WL |
3094 | p = *buffer -= dlen + 1; |
3095 | *p++ = '/'; | |
3096 | while (dlen--) { | |
3097 | char c = *dname++; | |
3098 | if (!c) | |
3099 | break; | |
3100 | *p++ = c; | |
3101 | } | |
3102 | return 0; | |
cdd16d02 MS |
3103 | } |
3104 | ||
1da177e4 | 3105 | /** |
208898c1 | 3106 | * prepend_path - Prepend path string to a buffer |
9d1bc601 | 3107 | * @path: the dentry/vfsmount to report |
02125a82 | 3108 | * @root: root vfsmnt/dentry |
f2eb6575 MS |
3109 | * @buffer: pointer to the end of the buffer |
3110 | * @buflen: pointer to buffer length | |
552ce544 | 3111 | * |
18129977 WL |
3112 | * The function will first try to write out the pathname without taking any |
3113 | * lock other than the RCU read lock to make sure that dentries won't go away. | |
3114 | * It only checks the sequence number of the global rename_lock as any change | |
3115 | * in the dentry's d_seq will be preceded by changes in the rename_lock | |
3116 | * sequence number. If the sequence number had been changed, it will restart | |
3117 | * the whole pathname back-tracing sequence again by taking the rename_lock. | |
3118 | * In this case, there is no need to take the RCU read lock as the recursive | |
3119 | * parent pointer references will keep the dentry chain alive as long as no | |
3120 | * rename operation is performed. | |
1da177e4 | 3121 | */ |
02125a82 AV |
3122 | static int prepend_path(const struct path *path, |
3123 | const struct path *root, | |
f2eb6575 | 3124 | char **buffer, int *buflen) |
1da177e4 | 3125 | { |
ede4cebc AV |
3126 | struct dentry *dentry; |
3127 | struct vfsmount *vfsmnt; | |
3128 | struct mount *mnt; | |
f2eb6575 | 3129 | int error = 0; |
48a066e7 | 3130 | unsigned seq, m_seq = 0; |
232d2d60 WL |
3131 | char *bptr; |
3132 | int blen; | |
6092d048 | 3133 | |
48f5ec21 | 3134 | rcu_read_lock(); |
48a066e7 AV |
3135 | restart_mnt: |
3136 | read_seqbegin_or_lock(&mount_lock, &m_seq); | |
3137 | seq = 0; | |
4ec6c2ae | 3138 | rcu_read_lock(); |
232d2d60 WL |
3139 | restart: |
3140 | bptr = *buffer; | |
3141 | blen = *buflen; | |
48a066e7 | 3142 | error = 0; |
ede4cebc AV |
3143 | dentry = path->dentry; |
3144 | vfsmnt = path->mnt; | |
3145 | mnt = real_mount(vfsmnt); | |
232d2d60 | 3146 | read_seqbegin_or_lock(&rename_lock, &seq); |
f2eb6575 | 3147 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
3148 | struct dentry * parent; |
3149 | ||
1da177e4 | 3150 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
48a066e7 | 3151 | struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); |
cde93be4 EB |
3152 | /* Escaped? */ |
3153 | if (dentry != vfsmnt->mnt_root) { | |
3154 | bptr = *buffer; | |
3155 | blen = *buflen; | |
3156 | error = 3; | |
3157 | break; | |
3158 | } | |
552ce544 | 3159 | /* Global root? */ |
48a066e7 AV |
3160 | if (mnt != parent) { |
3161 | dentry = ACCESS_ONCE(mnt->mnt_mountpoint); | |
3162 | mnt = parent; | |
232d2d60 WL |
3163 | vfsmnt = &mnt->mnt; |
3164 | continue; | |
3165 | } | |
232d2d60 WL |
3166 | if (!error) |
3167 | error = is_mounted(vfsmnt) ? 1 : 2; | |
3168 | break; | |
1da177e4 LT |
3169 | } |
3170 | parent = dentry->d_parent; | |
3171 | prefetch(parent); | |
232d2d60 | 3172 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
f2eb6575 MS |
3173 | if (error) |
3174 | break; | |
3175 | ||
1da177e4 LT |
3176 | dentry = parent; |
3177 | } | |
48f5ec21 AV |
3178 | if (!(seq & 1)) |
3179 | rcu_read_unlock(); | |
3180 | if (need_seqretry(&rename_lock, seq)) { | |
3181 | seq = 1; | |
232d2d60 | 3182 | goto restart; |
48f5ec21 AV |
3183 | } |
3184 | done_seqretry(&rename_lock, seq); | |
4ec6c2ae LZ |
3185 | |
3186 | if (!(m_seq & 1)) | |
3187 | rcu_read_unlock(); | |
48a066e7 AV |
3188 | if (need_seqretry(&mount_lock, m_seq)) { |
3189 | m_seq = 1; | |
3190 | goto restart_mnt; | |
3191 | } | |
3192 | done_seqretry(&mount_lock, m_seq); | |
1da177e4 | 3193 | |
232d2d60 WL |
3194 | if (error >= 0 && bptr == *buffer) { |
3195 | if (--blen < 0) | |
3196 | error = -ENAMETOOLONG; | |
3197 | else | |
3198 | *--bptr = '/'; | |
3199 | } | |
3200 | *buffer = bptr; | |
3201 | *buflen = blen; | |
7ea600b5 | 3202 | return error; |
f2eb6575 | 3203 | } |
be285c71 | 3204 | |
f2eb6575 MS |
3205 | /** |
3206 | * __d_path - return the path of a dentry | |
3207 | * @path: the dentry/vfsmount to report | |
02125a82 | 3208 | * @root: root vfsmnt/dentry |
cd956a1c | 3209 | * @buf: buffer to return value in |
f2eb6575 MS |
3210 | * @buflen: buffer length |
3211 | * | |
ffd1f4ed | 3212 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
3213 | * |
3214 | * Returns a pointer into the buffer or an error code if the | |
3215 | * path was too long. | |
3216 | * | |
be148247 | 3217 | * "buflen" should be positive. |
f2eb6575 | 3218 | * |
02125a82 | 3219 | * If the path is not reachable from the supplied root, return %NULL. |
f2eb6575 | 3220 | */ |
02125a82 AV |
3221 | char *__d_path(const struct path *path, |
3222 | const struct path *root, | |
f2eb6575 MS |
3223 | char *buf, int buflen) |
3224 | { | |
3225 | char *res = buf + buflen; | |
3226 | int error; | |
3227 | ||
3228 | prepend(&res, &buflen, "\0", 1); | |
f2eb6575 | 3229 | error = prepend_path(path, root, &res, &buflen); |
be148247 | 3230 | |
02125a82 AV |
3231 | if (error < 0) |
3232 | return ERR_PTR(error); | |
3233 | if (error > 0) | |
3234 | return NULL; | |
3235 | return res; | |
3236 | } | |
3237 | ||
3238 | char *d_absolute_path(const struct path *path, | |
3239 | char *buf, int buflen) | |
3240 | { | |
3241 | struct path root = {}; | |
3242 | char *res = buf + buflen; | |
3243 | int error; | |
3244 | ||
3245 | prepend(&res, &buflen, "\0", 1); | |
02125a82 | 3246 | error = prepend_path(path, &root, &res, &buflen); |
02125a82 AV |
3247 | |
3248 | if (error > 1) | |
3249 | error = -EINVAL; | |
3250 | if (error < 0) | |
f2eb6575 | 3251 | return ERR_PTR(error); |
f2eb6575 | 3252 | return res; |
1da177e4 LT |
3253 | } |
3254 | ||
ffd1f4ed MS |
3255 | /* |
3256 | * same as __d_path but appends "(deleted)" for unlinked files. | |
3257 | */ | |
02125a82 AV |
3258 | static int path_with_deleted(const struct path *path, |
3259 | const struct path *root, | |
3260 | char **buf, int *buflen) | |
ffd1f4ed MS |
3261 | { |
3262 | prepend(buf, buflen, "\0", 1); | |
3263 | if (d_unlinked(path->dentry)) { | |
3264 | int error = prepend(buf, buflen, " (deleted)", 10); | |
3265 | if (error) | |
3266 | return error; | |
3267 | } | |
3268 | ||
3269 | return prepend_path(path, root, buf, buflen); | |
3270 | } | |
3271 | ||
8df9d1a4 MS |
3272 | static int prepend_unreachable(char **buffer, int *buflen) |
3273 | { | |
3274 | return prepend(buffer, buflen, "(unreachable)", 13); | |
3275 | } | |
3276 | ||
68f0d9d9 LT |
3277 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
3278 | { | |
3279 | unsigned seq; | |
3280 | ||
3281 | do { | |
3282 | seq = read_seqcount_begin(&fs->seq); | |
3283 | *root = fs->root; | |
3284 | } while (read_seqcount_retry(&fs->seq, seq)); | |
3285 | } | |
3286 | ||
a03a8a70 JB |
3287 | /** |
3288 | * d_path - return the path of a dentry | |
cf28b486 | 3289 | * @path: path to report |
a03a8a70 JB |
3290 | * @buf: buffer to return value in |
3291 | * @buflen: buffer length | |
3292 | * | |
3293 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
3294 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
3295 | * | |
52afeefb AV |
3296 | * Returns a pointer into the buffer or an error code if the path was |
3297 | * too long. Note: Callers should use the returned pointer, not the passed | |
3298 | * in buffer, to use the name! The implementation often starts at an offset | |
3299 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 3300 | * |
31f3e0b3 | 3301 | * "buflen" should be positive. |
a03a8a70 | 3302 | */ |
20d4fdc1 | 3303 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 3304 | { |
ffd1f4ed | 3305 | char *res = buf + buflen; |
6ac08c39 | 3306 | struct path root; |
ffd1f4ed | 3307 | int error; |
1da177e4 | 3308 | |
c23fbb6b ED |
3309 | /* |
3310 | * We have various synthetic filesystems that never get mounted. On | |
3311 | * these filesystems dentries are never used for lookup purposes, and | |
3312 | * thus don't need to be hashed. They also don't need a name until a | |
3313 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
3314 | * below allows us to generate a name for these objects on demand: | |
f48cfddc EB |
3315 | * |
3316 | * Some pseudo inodes are mountable. When they are mounted | |
3317 | * path->dentry == path->mnt->mnt_root. In that case don't call d_dname | |
3318 | * and instead have d_path return the mounted path. | |
c23fbb6b | 3319 | */ |
f48cfddc EB |
3320 | if (path->dentry->d_op && path->dentry->d_op->d_dname && |
3321 | (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root)) | |
cf28b486 | 3322 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
c23fbb6b | 3323 | |
68f0d9d9 LT |
3324 | rcu_read_lock(); |
3325 | get_fs_root_rcu(current->fs, &root); | |
02125a82 | 3326 | error = path_with_deleted(path, &root, &res, &buflen); |
68f0d9d9 LT |
3327 | rcu_read_unlock(); |
3328 | ||
02125a82 | 3329 | if (error < 0) |
ffd1f4ed | 3330 | res = ERR_PTR(error); |
1da177e4 LT |
3331 | return res; |
3332 | } | |
ec4f8605 | 3333 | EXPORT_SYMBOL(d_path); |
1da177e4 | 3334 | |
c23fbb6b ED |
3335 | /* |
3336 | * Helper function for dentry_operations.d_dname() members | |
3337 | */ | |
3338 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
3339 | const char *fmt, ...) | |
3340 | { | |
3341 | va_list args; | |
3342 | char temp[64]; | |
3343 | int sz; | |
3344 | ||
3345 | va_start(args, fmt); | |
3346 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
3347 | va_end(args); | |
3348 | ||
3349 | if (sz > sizeof(temp) || sz > buflen) | |
3350 | return ERR_PTR(-ENAMETOOLONG); | |
3351 | ||
3352 | buffer += buflen - sz; | |
3353 | return memcpy(buffer, temp, sz); | |
3354 | } | |
3355 | ||
118b2302 AV |
3356 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
3357 | { | |
3358 | char *end = buffer + buflen; | |
3359 | /* these dentries are never renamed, so d_lock is not needed */ | |
3360 | if (prepend(&end, &buflen, " (deleted)", 11) || | |
232d2d60 | 3361 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
118b2302 AV |
3362 | prepend(&end, &buflen, "/", 1)) |
3363 | end = ERR_PTR(-ENAMETOOLONG); | |
232d2d60 | 3364 | return end; |
118b2302 | 3365 | } |
31bbe16f | 3366 | EXPORT_SYMBOL(simple_dname); |
118b2302 | 3367 | |
6092d048 RP |
3368 | /* |
3369 | * Write full pathname from the root of the filesystem into the buffer. | |
3370 | */ | |
f6500801 | 3371 | static char *__dentry_path(struct dentry *d, char *buf, int buflen) |
6092d048 | 3372 | { |
f6500801 | 3373 | struct dentry *dentry; |
232d2d60 WL |
3374 | char *end, *retval; |
3375 | int len, seq = 0; | |
3376 | int error = 0; | |
6092d048 | 3377 | |
f6500801 AV |
3378 | if (buflen < 2) |
3379 | goto Elong; | |
3380 | ||
48f5ec21 | 3381 | rcu_read_lock(); |
232d2d60 | 3382 | restart: |
f6500801 | 3383 | dentry = d; |
232d2d60 WL |
3384 | end = buf + buflen; |
3385 | len = buflen; | |
3386 | prepend(&end, &len, "\0", 1); | |
6092d048 RP |
3387 | /* Get '/' right */ |
3388 | retval = end-1; | |
3389 | *retval = '/'; | |
232d2d60 | 3390 | read_seqbegin_or_lock(&rename_lock, &seq); |
cdd16d02 MS |
3391 | while (!IS_ROOT(dentry)) { |
3392 | struct dentry *parent = dentry->d_parent; | |
6092d048 | 3393 | |
6092d048 | 3394 | prefetch(parent); |
232d2d60 WL |
3395 | error = prepend_name(&end, &len, &dentry->d_name); |
3396 | if (error) | |
3397 | break; | |
6092d048 RP |
3398 | |
3399 | retval = end; | |
3400 | dentry = parent; | |
3401 | } | |
48f5ec21 AV |
3402 | if (!(seq & 1)) |
3403 | rcu_read_unlock(); | |
3404 | if (need_seqretry(&rename_lock, seq)) { | |
3405 | seq = 1; | |
232d2d60 | 3406 | goto restart; |
48f5ec21 AV |
3407 | } |
3408 | done_seqretry(&rename_lock, seq); | |
232d2d60 WL |
3409 | if (error) |
3410 | goto Elong; | |
c103135c AV |
3411 | return retval; |
3412 | Elong: | |
3413 | return ERR_PTR(-ENAMETOOLONG); | |
3414 | } | |
ec2447c2 NP |
3415 | |
3416 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
3417 | { | |
232d2d60 | 3418 | return __dentry_path(dentry, buf, buflen); |
ec2447c2 NP |
3419 | } |
3420 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
3421 | |
3422 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
3423 | { | |
3424 | char *p = NULL; | |
3425 | char *retval; | |
3426 | ||
c103135c AV |
3427 | if (d_unlinked(dentry)) { |
3428 | p = buf + buflen; | |
3429 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
3430 | goto Elong; | |
3431 | buflen++; | |
3432 | } | |
3433 | retval = __dentry_path(dentry, buf, buflen); | |
c103135c AV |
3434 | if (!IS_ERR(retval) && p) |
3435 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
3436 | return retval; |
3437 | Elong: | |
6092d048 RP |
3438 | return ERR_PTR(-ENAMETOOLONG); |
3439 | } | |
3440 | ||
8b19e341 LT |
3441 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
3442 | struct path *pwd) | |
5762482f | 3443 | { |
8b19e341 LT |
3444 | unsigned seq; |
3445 | ||
3446 | do { | |
3447 | seq = read_seqcount_begin(&fs->seq); | |
3448 | *root = fs->root; | |
3449 | *pwd = fs->pwd; | |
3450 | } while (read_seqcount_retry(&fs->seq, seq)); | |
5762482f LT |
3451 | } |
3452 | ||
1da177e4 LT |
3453 | /* |
3454 | * NOTE! The user-level library version returns a | |
3455 | * character pointer. The kernel system call just | |
3456 | * returns the length of the buffer filled (which | |
3457 | * includes the ending '\0' character), or a negative | |
3458 | * error value. So libc would do something like | |
3459 | * | |
3460 | * char *getcwd(char * buf, size_t size) | |
3461 | * { | |
3462 | * int retval; | |
3463 | * | |
3464 | * retval = sys_getcwd(buf, size); | |
3465 | * if (retval >= 0) | |
3466 | * return buf; | |
3467 | * errno = -retval; | |
3468 | * return NULL; | |
3469 | * } | |
3470 | */ | |
3cdad428 | 3471 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 3472 | { |
552ce544 | 3473 | int error; |
6ac08c39 | 3474 | struct path pwd, root; |
3272c544 | 3475 | char *page = __getname(); |
1da177e4 LT |
3476 | |
3477 | if (!page) | |
3478 | return -ENOMEM; | |
3479 | ||
8b19e341 LT |
3480 | rcu_read_lock(); |
3481 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); | |
1da177e4 | 3482 | |
552ce544 | 3483 | error = -ENOENT; |
f3da392e | 3484 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 3485 | unsigned long len; |
3272c544 LT |
3486 | char *cwd = page + PATH_MAX; |
3487 | int buflen = PATH_MAX; | |
1da177e4 | 3488 | |
8df9d1a4 | 3489 | prepend(&cwd, &buflen, "\0", 1); |
02125a82 | 3490 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
ff812d72 | 3491 | rcu_read_unlock(); |
552ce544 | 3492 | |
02125a82 | 3493 | if (error < 0) |
552ce544 LT |
3494 | goto out; |
3495 | ||
8df9d1a4 | 3496 | /* Unreachable from current root */ |
02125a82 | 3497 | if (error > 0) { |
8df9d1a4 MS |
3498 | error = prepend_unreachable(&cwd, &buflen); |
3499 | if (error) | |
3500 | goto out; | |
3501 | } | |
3502 | ||
552ce544 | 3503 | error = -ERANGE; |
3272c544 | 3504 | len = PATH_MAX + page - cwd; |
552ce544 LT |
3505 | if (len <= size) { |
3506 | error = len; | |
3507 | if (copy_to_user(buf, cwd, len)) | |
3508 | error = -EFAULT; | |
3509 | } | |
949854d0 | 3510 | } else { |
ff812d72 | 3511 | rcu_read_unlock(); |
949854d0 | 3512 | } |
1da177e4 LT |
3513 | |
3514 | out: | |
3272c544 | 3515 | __putname(page); |
1da177e4 LT |
3516 | return error; |
3517 | } | |
3518 | ||
3519 | /* | |
3520 | * Test whether new_dentry is a subdirectory of old_dentry. | |
3521 | * | |
3522 | * Trivially implemented using the dcache structure | |
3523 | */ | |
3524 | ||
3525 | /** | |
3526 | * is_subdir - is new dentry a subdirectory of old_dentry | |
3527 | * @new_dentry: new dentry | |
3528 | * @old_dentry: old dentry | |
3529 | * | |
a6e5787f YB |
3530 | * Returns true if new_dentry is a subdirectory of the parent (at any depth). |
3531 | * Returns false otherwise. | |
1da177e4 LT |
3532 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
3533 | */ | |
3534 | ||
a6e5787f | 3535 | bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 | 3536 | { |
a6e5787f | 3537 | bool result; |
949854d0 | 3538 | unsigned seq; |
1da177e4 | 3539 | |
e2761a11 | 3540 | if (new_dentry == old_dentry) |
a6e5787f | 3541 | return true; |
e2761a11 | 3542 | |
e2761a11 | 3543 | do { |
1da177e4 | 3544 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 3545 | seq = read_seqbegin(&rename_lock); |
949854d0 NP |
3546 | /* |
3547 | * Need rcu_readlock to protect against the d_parent trashing | |
3548 | * due to d_move | |
3549 | */ | |
3550 | rcu_read_lock(); | |
e2761a11 | 3551 | if (d_ancestor(old_dentry, new_dentry)) |
a6e5787f | 3552 | result = true; |
e2761a11 | 3553 | else |
a6e5787f | 3554 | result = false; |
949854d0 | 3555 | rcu_read_unlock(); |
1da177e4 | 3556 | } while (read_seqretry(&rename_lock, seq)); |
1da177e4 LT |
3557 | |
3558 | return result; | |
3559 | } | |
3560 | ||
db14fc3a | 3561 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
1da177e4 | 3562 | { |
db14fc3a MS |
3563 | struct dentry *root = data; |
3564 | if (dentry != root) { | |
3565 | if (d_unhashed(dentry) || !dentry->d_inode) | |
3566 | return D_WALK_SKIP; | |
1da177e4 | 3567 | |
01ddc4ed MS |
3568 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
3569 | dentry->d_flags |= DCACHE_GENOCIDE; | |
3570 | dentry->d_lockref.count--; | |
3571 | } | |
1da177e4 | 3572 | } |
db14fc3a MS |
3573 | return D_WALK_CONTINUE; |
3574 | } | |
58db63d0 | 3575 | |
db14fc3a MS |
3576 | void d_genocide(struct dentry *parent) |
3577 | { | |
3578 | d_walk(parent, parent, d_genocide_kill, NULL); | |
1da177e4 LT |
3579 | } |
3580 | ||
60545d0d | 3581 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
1da177e4 | 3582 | { |
60545d0d AV |
3583 | inode_dec_link_count(inode); |
3584 | BUG_ON(dentry->d_name.name != dentry->d_iname || | |
946e51f2 | 3585 | !hlist_unhashed(&dentry->d_u.d_alias) || |
60545d0d AV |
3586 | !d_unlinked(dentry)); |
3587 | spin_lock(&dentry->d_parent->d_lock); | |
3588 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
3589 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", | |
3590 | (unsigned long long)inode->i_ino); | |
3591 | spin_unlock(&dentry->d_lock); | |
3592 | spin_unlock(&dentry->d_parent->d_lock); | |
3593 | d_instantiate(dentry, inode); | |
1da177e4 | 3594 | } |
60545d0d | 3595 | EXPORT_SYMBOL(d_tmpfile); |
1da177e4 LT |
3596 | |
3597 | static __initdata unsigned long dhash_entries; | |
3598 | static int __init set_dhash_entries(char *str) | |
3599 | { | |
3600 | if (!str) | |
3601 | return 0; | |
3602 | dhash_entries = simple_strtoul(str, &str, 0); | |
3603 | return 1; | |
3604 | } | |
3605 | __setup("dhash_entries=", set_dhash_entries); | |
3606 | ||
3607 | static void __init dcache_init_early(void) | |
3608 | { | |
074b8517 | 3609 | unsigned int loop; |
1da177e4 LT |
3610 | |
3611 | /* If hashes are distributed across NUMA nodes, defer | |
3612 | * hash allocation until vmalloc space is available. | |
3613 | */ | |
3614 | if (hashdist) | |
3615 | return; | |
3616 | ||
3617 | dentry_hashtable = | |
3618 | alloc_large_system_hash("Dentry cache", | |
b07ad996 | 3619 | sizeof(struct hlist_bl_head), |
1da177e4 LT |
3620 | dhash_entries, |
3621 | 13, | |
3622 | HASH_EARLY, | |
3623 | &d_hash_shift, | |
3624 | &d_hash_mask, | |
31fe62b9 | 3625 | 0, |
1da177e4 LT |
3626 | 0); |
3627 | ||
074b8517 | 3628 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
b07ad996 | 3629 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
1da177e4 LT |
3630 | } |
3631 | ||
74bf17cf | 3632 | static void __init dcache_init(void) |
1da177e4 | 3633 | { |
074b8517 | 3634 | unsigned int loop; |
1da177e4 LT |
3635 | |
3636 | /* | |
3637 | * A constructor could be added for stable state like the lists, | |
3638 | * but it is probably not worth it because of the cache nature | |
3639 | * of the dcache. | |
3640 | */ | |
0a31bd5f | 3641 | dentry_cache = KMEM_CACHE(dentry, |
5d097056 | 3642 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT); |
1da177e4 LT |
3643 | |
3644 | /* Hash may have been set up in dcache_init_early */ | |
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 | 0, | |
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 | ||
3663 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 3664 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 3665 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 3666 | |
1da177e4 LT |
3667 | EXPORT_SYMBOL(d_genocide); |
3668 | ||
1da177e4 LT |
3669 | void __init vfs_caches_init_early(void) |
3670 | { | |
3671 | dcache_init_early(); | |
3672 | inode_init_early(); | |
3673 | } | |
3674 | ||
4248b0da | 3675 | void __init vfs_caches_init(void) |
1da177e4 | 3676 | { |
1da177e4 | 3677 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
20c2df83 | 3678 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 3679 | |
74bf17cf DC |
3680 | dcache_init(); |
3681 | inode_init(); | |
4248b0da MG |
3682 | files_init(); |
3683 | files_maxfiles_init(); | |
74bf17cf | 3684 | mnt_init(); |
1da177e4 LT |
3685 | bdev_cache_init(); |
3686 | chrdev_init(); | |
3687 | } |