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1 : : // SPDX-License-Identifier: GPL-2.0-only
2 : : /*
3 : : * fs/dcache.c
4 : : *
5 : : * Complete reimplementation
6 : : * (C) 1997 Thomas Schoebel-Theuer,
7 : : * with heavy changes by Linus Torvalds
8 : : */
9 : :
10 : : /*
11 : : * Notes on the allocation strategy:
12 : : *
13 : : * The dcache is a master of the icache - whenever a dcache entry
14 : : * exists, the inode will always exist. "iput()" is done either when
15 : : * the dcache entry is deleted or garbage collected.
16 : : */
17 : :
18 : : #include <linux/ratelimit.h>
19 : : #include <linux/string.h>
20 : : #include <linux/mm.h>
21 : : #include <linux/fs.h>
22 : : #include <linux/fscrypt.h>
23 : : #include <linux/fsnotify.h>
24 : : #include <linux/slab.h>
25 : : #include <linux/init.h>
26 : : #include <linux/hash.h>
27 : : #include <linux/cache.h>
28 : : #include <linux/export.h>
29 : : #include <linux/security.h>
30 : : #include <linux/seqlock.h>
31 : : #include <linux/memblock.h>
32 : : #include <linux/bit_spinlock.h>
33 : : #include <linux/rculist_bl.h>
34 : : #include <linux/list_lru.h>
35 : : #include "internal.h"
36 : : #include "mount.h"
37 : :
38 : : /*
39 : : * Usage:
40 : : * dcache->d_inode->i_lock protects:
41 : : * - i_dentry, d_u.d_alias, d_inode of aliases
42 : : * dcache_hash_bucket lock protects:
43 : : * - the dcache hash table
44 : : * s_roots bl list spinlock protects:
45 : : * - the s_roots list (see __d_drop)
46 : : * dentry->d_sb->s_dentry_lru_lock protects:
47 : : * - the dcache lru lists and counters
48 : : * d_lock protects:
49 : : * - d_flags
50 : : * - d_name
51 : : * - d_lru
52 : : * - d_count
53 : : * - d_unhashed()
54 : : * - d_parent and d_subdirs
55 : : * - childrens' d_child and d_parent
56 : : * - d_u.d_alias, d_inode
57 : : *
58 : : * Ordering:
59 : : * dentry->d_inode->i_lock
60 : : * dentry->d_lock
61 : : * dentry->d_sb->s_dentry_lru_lock
62 : : * dcache_hash_bucket lock
63 : : * s_roots lock
64 : : *
65 : : * If there is an ancestor relationship:
66 : : * dentry->d_parent->...->d_parent->d_lock
67 : : * ...
68 : : * dentry->d_parent->d_lock
69 : : * dentry->d_lock
70 : : *
71 : : * If no ancestor relationship:
72 : : * arbitrary, since it's serialized on rename_lock
73 : : */
74 : : int sysctl_vfs_cache_pressure __read_mostly = 100;
75 : : EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
76 : :
77 : : __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
78 : :
79 : : EXPORT_SYMBOL(rename_lock);
80 : :
81 : : static struct kmem_cache *dentry_cache __read_mostly;
82 : :
83 : : const struct qstr empty_name = QSTR_INIT("", 0);
84 : : EXPORT_SYMBOL(empty_name);
85 : : const struct qstr slash_name = QSTR_INIT("/", 1);
86 : : EXPORT_SYMBOL(slash_name);
87 : :
88 : : /*
89 : : * This is the single most critical data structure when it comes
90 : : * to the dcache: the hashtable for lookups. Somebody should try
91 : : * to make this good - I've just made it work.
92 : : *
93 : : * This hash-function tries to avoid losing too many bits of hash
94 : : * information, yet avoid using a prime hash-size or similar.
95 : : */
96 : :
97 : : static unsigned int d_hash_shift __read_mostly;
98 : :
99 : : static struct hlist_bl_head *dentry_hashtable __read_mostly;
100 : :
101 : : static inline struct hlist_bl_head *d_hash(unsigned int hash)
102 : : {
103 : 110519866 : return dentry_hashtable + (hash >> d_hash_shift);
104 : : }
105 : :
106 : : #define IN_LOOKUP_SHIFT 10
107 : : static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT];
108 : :
109 : : static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent,
110 : : unsigned int hash)
111 : : {
112 : 19808984 : hash += (unsigned long) parent / L1_CACHE_BYTES;
113 : 19808984 : return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT);
114 : : }
115 : :
116 : :
117 : : /* Statistics gathering. */
118 : : struct dentry_stat_t dentry_stat = {
119 : : .age_limit = 45,
120 : : };
121 : :
122 : : static DEFINE_PER_CPU(long, nr_dentry);
123 : : static DEFINE_PER_CPU(long, nr_dentry_unused);
124 : : static DEFINE_PER_CPU(long, nr_dentry_negative);
125 : :
126 : : #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
127 : :
128 : : /*
129 : : * Here we resort to our own counters instead of using generic per-cpu counters
130 : : * for consistency with what the vfs inode code does. We are expected to harvest
131 : : * better code and performance by having our own specialized counters.
132 : : *
133 : : * Please note that the loop is done over all possible CPUs, not over all online
134 : : * CPUs. The reason for this is that we don't want to play games with CPUs going
135 : : * on and off. If one of them goes off, we will just keep their counters.
136 : : *
137 : : * glommer: See cffbc8a for details, and if you ever intend to change this,
138 : : * please update all vfs counters to match.
139 : : */
140 : 0 : static long get_nr_dentry(void)
141 : : {
142 : : int i;
143 : : long sum = 0;
144 [ # # ]: 0 : for_each_possible_cpu(i)
145 : 0 : sum += per_cpu(nr_dentry, i);
146 : 0 : return sum < 0 ? 0 : sum;
147 : : }
148 : :
149 : 0 : static long get_nr_dentry_unused(void)
150 : : {
151 : : int i;
152 : : long sum = 0;
153 [ # # ]: 0 : for_each_possible_cpu(i)
154 : 0 : sum += per_cpu(nr_dentry_unused, i);
155 : 0 : return sum < 0 ? 0 : sum;
156 : : }
157 : :
158 : 0 : static long get_nr_dentry_negative(void)
159 : : {
160 : : int i;
161 : : long sum = 0;
162 : :
163 [ # # ]: 0 : for_each_possible_cpu(i)
164 : 0 : sum += per_cpu(nr_dentry_negative, i);
165 : 0 : return sum < 0 ? 0 : sum;
166 : : }
167 : :
168 : 0 : int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer,
169 : : size_t *lenp, loff_t *ppos)
170 : : {
171 : 0 : dentry_stat.nr_dentry = get_nr_dentry();
172 : 0 : dentry_stat.nr_unused = get_nr_dentry_unused();
173 : 0 : dentry_stat.nr_negative = get_nr_dentry_negative();
174 : 0 : return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
175 : : }
176 : : #endif
177 : :
178 : : /*
179 : : * Compare 2 name strings, return 0 if they match, otherwise non-zero.
180 : : * The strings are both count bytes long, and count is non-zero.
181 : : */
182 : : #ifdef CONFIG_DCACHE_WORD_ACCESS
183 : :
184 : : #include <asm/word-at-a-time.h>
185 : : /*
186 : : * NOTE! 'cs' and 'scount' come from a dentry, so it has a
187 : : * aligned allocation for this particular component. We don't
188 : : * strictly need the load_unaligned_zeropad() safety, but it
189 : : * doesn't hurt either.
190 : : *
191 : : * In contrast, 'ct' and 'tcount' can be from a pathname, and do
192 : : * need the careful unaligned handling.
193 : : */
194 : 75683567 : static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
195 : : {
196 : : unsigned long a,b,mask;
197 : :
198 : : for (;;) {
199 : : a = read_word_at_a_time(cs);
200 : 147501656 : b = load_unaligned_zeropad(ct);
201 [ + + ]: 147452939 : if (tcount < sizeof(unsigned long))
202 : : break;
203 [ + + ]: 83890914 : if (unlikely(a != b))
204 : : return 1;
205 : 83896837 : cs += sizeof(unsigned long);
206 : 83896837 : ct += sizeof(unsigned long);
207 : 83896837 : tcount -= sizeof(unsigned long);
208 [ + + ]: 83896837 : if (!tcount)
209 : : return 0;
210 : : }
211 : 63562025 : mask = bytemask_from_count(tcount);
212 : 63562025 : return unlikely(!!((a ^ b) & mask));
213 : : }
214 : :
215 : : #else
216 : :
217 : : static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
218 : : {
219 : : do {
220 : : if (*cs != *ct)
221 : : return 1;
222 : : cs++;
223 : : ct++;
224 : : tcount--;
225 : : } while (tcount);
226 : : return 0;
227 : : }
228 : :
229 : : #endif
230 : :
231 : : static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount)
232 : : {
233 : : /*
234 : : * Be careful about RCU walk racing with rename:
235 : : * use 'READ_ONCE' to fetch the name pointer.
236 : : *
237 : : * NOTE! Even if a rename will mean that the length
238 : : * was not loaded atomically, we don't care. The
239 : : * RCU walk will check the sequence count eventually,
240 : : * and catch it. And we won't overrun the buffer,
241 : : * because we're reading the name pointer atomically,
242 : : * and a dentry name is guaranteed to be properly
243 : : * terminated with a NUL byte.
244 : : *
245 : : * End result: even if 'len' is wrong, we'll exit
246 : : * early because the data cannot match (there can
247 : : * be no NUL in the ct/tcount data)
248 : : */
249 : 75629197 : const unsigned char *cs = READ_ONCE(dentry->d_name.name);
250 : :
251 : 75629197 : return dentry_string_cmp(cs, ct, tcount);
252 : : }
253 : :
254 : : struct external_name {
255 : : union {
256 : : atomic_t count;
257 : : struct rcu_head head;
258 : : } u;
259 : : unsigned char name[];
260 : : };
261 : :
262 : : static inline struct external_name *external_name(struct dentry *dentry)
263 : : {
264 : 255252 : return container_of(dentry->d_name.name, struct external_name, name[0]);
265 : : }
266 : :
267 : 5254670 : static void __d_free(struct rcu_head *head)
268 : : {
269 : 5254670 : struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
270 : :
271 : 5515420 : kmem_cache_free(dentry_cache, dentry);
272 : 5255429 : }
273 : :
274 : 242620 : static void __d_free_external(struct rcu_head *head)
275 : : {
276 : 242620 : struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
277 : 242620 : kfree(external_name(dentry));
278 : 242625 : kmem_cache_free(dentry_cache, dentry);
279 : 242625 : }
280 : :
281 : : static inline int dname_external(const struct dentry *dentry)
282 : : {
283 : 5988720 : return dentry->d_name.name != dentry->d_iname;
284 : : }
285 : :
286 : 77139 : void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry)
287 : : {
288 : : spin_lock(&dentry->d_lock);
289 : 77139 : name->name = dentry->d_name;
290 [ + + ]: 77139 : if (unlikely(dname_external(dentry))) {
291 : 12632 : atomic_inc(&external_name(dentry)->u.count);
292 : : } else {
293 : 129014 : memcpy(name->inline_name, dentry->d_iname,
294 : 64507 : dentry->d_name.len + 1);
295 : 64507 : name->name.name = name->inline_name;
296 : : }
297 : : spin_unlock(&dentry->d_lock);
298 : 77136 : }
299 : : EXPORT_SYMBOL(take_dentry_name_snapshot);
300 : :
301 : 77123 : void release_dentry_name_snapshot(struct name_snapshot *name)
302 : : {
303 [ + + ]: 77123 : if (unlikely(name->name.name != name->inline_name)) {
304 : : struct external_name *p;
305 : 12632 : p = container_of(name->name.name, struct external_name, name[0]);
306 [ + - ]: 25264 : if (unlikely(atomic_dec_and_test(&p->u.count)))
307 [ + - ]: 12632 : kfree_rcu(p, u.head);
308 : : }
309 : 77123 : }
310 : : EXPORT_SYMBOL(release_dentry_name_snapshot);
311 : :
312 : : static inline void __d_set_inode_and_type(struct dentry *dentry,
313 : : struct inode *inode,
314 : : unsigned type_flags)
315 : : {
316 : : unsigned flags;
317 : :
318 : 6302960 : dentry->d_inode = inode;
319 : : flags = READ_ONCE(dentry->d_flags);
320 : 6302960 : flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
321 : 6302960 : flags |= type_flags;
322 : : WRITE_ONCE(dentry->d_flags, flags);
323 : : }
324 : :
325 : 1886380 : static inline void __d_clear_type_and_inode(struct dentry *dentry)
326 : : {
327 : : unsigned flags = READ_ONCE(dentry->d_flags);
328 : :
329 : 1886380 : flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
330 : : WRITE_ONCE(dentry->d_flags, flags);
331 : 1886380 : dentry->d_inode = NULL;
332 [ + + ]: 1886380 : if (dentry->d_flags & DCACHE_LRU_LIST)
333 : 4060 : this_cpu_inc(nr_dentry_negative);
334 : 1886380 : }
335 : :
336 : 5760271 : static void dentry_free(struct dentry *dentry)
337 : : {
338 [ - + ]: 5760271 : WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
339 [ + + ]: 5757559 : if (unlikely(dname_external(dentry))) {
340 : : struct external_name *p = external_name(dentry);
341 [ + + ]: 493157 : if (likely(atomic_dec_and_test(&p->u.count))) {
342 : 242616 : call_rcu(&dentry->d_u.d_rcu, __d_free_external);
343 : 6003939 : return;
344 : : }
345 : : }
346 : : /* if dentry was never visible to RCU, immediate free is OK */
347 [ + + ]: 5514964 : if (dentry->d_flags & DCACHE_NORCU)
348 : : __d_free(&dentry->d_u.d_rcu);
349 : : else
350 : 5254214 : call_rcu(&dentry->d_u.d_rcu, __d_free);
351 : : }
352 : :
353 : : /*
354 : : * Release the dentry's inode, using the filesystem
355 : : * d_iput() operation if defined.
356 : : */
357 : 1886737 : static void dentry_unlink_inode(struct dentry * dentry)
358 : : __releases(dentry->d_lock)
359 : : __releases(dentry->d_inode->i_lock)
360 : : {
361 : 1886737 : struct inode *inode = dentry->d_inode;
362 : :
363 : : raw_write_seqcount_begin(&dentry->d_seq);
364 : 1886286 : __d_clear_type_and_inode(dentry);
365 : : hlist_del_init(&dentry->d_u.d_alias);
366 : : raw_write_seqcount_end(&dentry->d_seq);
367 : : spin_unlock(&dentry->d_lock);
368 : : spin_unlock(&inode->i_lock);
369 [ + + ]: 1886574 : if (!inode->i_nlink)
370 : 32701 : fsnotify_inoderemove(inode);
371 [ + + - + ]: 1886387 : if (dentry->d_op && dentry->d_op->d_iput)
372 : 0 : dentry->d_op->d_iput(dentry, inode);
373 : : else
374 : 1886387 : iput(inode);
375 : 1886737 : }
376 : :
377 : : /*
378 : : * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
379 : : * is in use - which includes both the "real" per-superblock
380 : : * LRU list _and_ the DCACHE_SHRINK_LIST use.
381 : : *
382 : : * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
383 : : * on the shrink list (ie not on the superblock LRU list).
384 : : *
385 : : * The per-cpu "nr_dentry_unused" counters are updated with
386 : : * the DCACHE_LRU_LIST bit.
387 : : *
388 : : * The per-cpu "nr_dentry_negative" counters are only updated
389 : : * when deleted from or added to the per-superblock LRU list, not
390 : : * from/to the shrink list. That is to avoid an unneeded dec/inc
391 : : * pair when moving from LRU to shrink list in select_collect().
392 : : *
393 : : * These helper functions make sure we always follow the
394 : : * rules. d_lock must be held by the caller.
395 : : */
396 : : #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
397 : 3236453 : static void d_lru_add(struct dentry *dentry)
398 : : {
399 [ - + # # ]: 3236453 : D_FLAG_VERIFY(dentry, 0);
400 : 3236453 : dentry->d_flags |= DCACHE_LRU_LIST;
401 : 6472804 : this_cpu_inc(nr_dentry_unused);
402 [ + + ]: 3236500 : if (d_is_negative(dentry))
403 : 1214450 : this_cpu_inc(nr_dentry_negative);
404 [ - + # # ]: 3236575 : WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
405 : 3236406 : }
406 : :
407 : 1105519 : static void d_lru_del(struct dentry *dentry)
408 : : {
409 [ - + # # ]: 1105519 : D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
410 : 1105519 : dentry->d_flags &= ~DCACHE_LRU_LIST;
411 : 2210914 : this_cpu_dec(nr_dentry_unused);
412 [ + + ]: 1105476 : if (d_is_negative(dentry))
413 : 1274 : this_cpu_dec(nr_dentry_negative);
414 [ - + # # ]: 1105476 : WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
415 : 1105507 : }
416 : :
417 : 1367616 : static void d_shrink_del(struct dentry *dentry)
418 : : {
419 [ - + # # ]: 1367616 : D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
420 : 1367616 : list_del_init(&dentry->d_lru);
421 : 1367616 : dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
422 : 2735164 : this_cpu_dec(nr_dentry_unused);
423 : 1367637 : }
424 : :
425 : 1162302 : static void d_shrink_add(struct dentry *dentry, struct list_head *list)
426 : : {
427 [ - + # # ]: 1162302 : D_FLAG_VERIFY(dentry, 0);
428 : 1162302 : list_add(&dentry->d_lru, list);
429 : 1162302 : dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST;
430 : 2324598 : this_cpu_inc(nr_dentry_unused);
431 : 1162274 : }
432 : :
433 : : /*
434 : : * These can only be called under the global LRU lock, ie during the
435 : : * callback for freeing the LRU list. "isolate" removes it from the
436 : : * LRU lists entirely, while shrink_move moves it to the indicated
437 : : * private list.
438 : : */
439 : 0 : static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry)
440 : : {
441 [ # # # # ]: 0 : D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
442 : 0 : dentry->d_flags &= ~DCACHE_LRU_LIST;
443 : 0 : this_cpu_dec(nr_dentry_unused);
444 [ # # ]: 0 : if (d_is_negative(dentry))
445 : 0 : this_cpu_dec(nr_dentry_negative);
446 : 0 : list_lru_isolate(lru, &dentry->d_lru);
447 : 0 : }
448 : :
449 : 205352 : static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry,
450 : : struct list_head *list)
451 : : {
452 [ - + # # ]: 205352 : D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
453 : 205352 : dentry->d_flags |= DCACHE_SHRINK_LIST;
454 [ + + ]: 205352 : if (d_is_negative(dentry))
455 : 94408 : this_cpu_dec(nr_dentry_negative);
456 : 205352 : list_lru_isolate_move(lru, &dentry->d_lru, list);
457 : 205352 : }
458 : :
459 : : /**
460 : : * d_drop - drop a dentry
461 : : * @dentry: dentry to drop
462 : : *
463 : : * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
464 : : * be found through a VFS lookup any more. Note that this is different from
465 : : * deleting the dentry - d_delete will try to mark the dentry negative if
466 : : * possible, giving a successful _negative_ lookup, while d_drop will
467 : : * just make the cache lookup fail.
468 : : *
469 : : * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
470 : : * reason (NFS timeouts or autofs deletes).
471 : : *
472 : : * __d_drop requires dentry->d_lock
473 : : * ___d_drop doesn't mark dentry as "unhashed"
474 : : * (dentry->d_hash.pprev will be LIST_POISON2, not NULL).
475 : : */
476 : 3960952 : static void ___d_drop(struct dentry *dentry)
477 : : {
478 : : struct hlist_bl_head *b;
479 : : /*
480 : : * Hashed dentries are normally on the dentry hashtable,
481 : : * with the exception of those newly allocated by
482 : : * d_obtain_root, which are always IS_ROOT:
483 : : */
484 [ - + ]: 3960952 : if (unlikely(IS_ROOT(dentry)))
485 : 0 : b = &dentry->d_sb->s_roots;
486 : : else
487 : 3960952 : b = d_hash(dentry->d_name.hash);
488 : :
489 : : hlist_bl_lock(b);
490 : : __hlist_bl_del(&dentry->d_hash);
491 : : hlist_bl_unlock(b);
492 : 3960520 : }
493 : :
494 : 6014398 : void __d_drop(struct dentry *dentry)
495 : : {
496 [ + + ]: 6014398 : if (!d_unhashed(dentry)) {
497 : 3807157 : ___d_drop(dentry);
498 : 3806914 : dentry->d_hash.pprev = NULL;
499 : : write_seqcount_invalidate(&dentry->d_seq);
500 : : }
501 : 6012711 : }
502 : : EXPORT_SYMBOL(__d_drop);
503 : :
504 : 2693 : void d_drop(struct dentry *dentry)
505 : : {
506 : : spin_lock(&dentry->d_lock);
507 : 2693 : __d_drop(dentry);
508 : : spin_unlock(&dentry->d_lock);
509 : 2693 : }
510 : : EXPORT_SYMBOL(d_drop);
511 : :
512 : 5757378 : static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
513 : : {
514 : : struct dentry *next;
515 : : /*
516 : : * Inform d_walk() and shrink_dentry_list() that we are no longer
517 : : * attached to the dentry tree
518 : : */
519 : 5757378 : dentry->d_flags |= DCACHE_DENTRY_KILLED;
520 [ + + ]: 11514756 : if (unlikely(list_empty(&dentry->d_child)))
521 : 5757378 : return;
522 : : __list_del_entry(&dentry->d_child);
523 : : /*
524 : : * Cursors can move around the list of children. While we'd been
525 : : * a normal list member, it didn't matter - ->d_child.next would've
526 : : * been updated. However, from now on it won't be and for the
527 : : * things like d_walk() it might end up with a nasty surprise.
528 : : * Normally d_walk() doesn't care about cursors moving around -
529 : : * ->d_lock on parent prevents that and since a cursor has no children
530 : : * of its own, we get through it without ever unlocking the parent.
531 : : * There is one exception, though - if we ascend from a child that
532 : : * gets killed as soon as we unlock it, the next sibling is found
533 : : * using the value left in its ->d_child.next. And if _that_
534 : : * pointed to a cursor, and cursor got moved (e.g. by lseek())
535 : : * before d_walk() regains parent->d_lock, we'll end up skipping
536 : : * everything the cursor had been moved past.
537 : : *
538 : : * Solution: make sure that the pointer left behind in ->d_child.next
539 : : * points to something that won't be moving around. I.e. skip the
540 : : * cursors.
541 : : */
542 [ + + ]: 5411259 : while (dentry->d_child.next != &parent->d_subdirs) {
543 : : next = list_entry(dentry->d_child.next, struct dentry, d_child);
544 [ - + ]: 4626386 : if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR)))
545 : : break;
546 : 0 : dentry->d_child.next = next->d_child.next;
547 : : }
548 : : }
549 : :
550 : 5760473 : static void __dentry_kill(struct dentry *dentry)
551 : : {
552 : : struct dentry *parent = NULL;
553 : : bool can_free = true;
554 [ + + ]: 5760473 : if (!IS_ROOT(dentry))
555 : : parent = dentry->d_parent;
556 : :
557 : : /*
558 : : * The dentry is now unrecoverably dead to the world.
559 : : */
560 : 5760473 : lockref_mark_dead(&dentry->d_lockref);
561 : :
562 : : /*
563 : : * inform the fs via d_prune that this dentry is about to be
564 : : * unhashed and destroyed.
565 : : */
566 [ - + ]: 5759109 : if (dentry->d_flags & DCACHE_OP_PRUNE)
567 : 0 : dentry->d_op->d_prune(dentry);
568 : :
569 [ + + ]: 5757466 : if (dentry->d_flags & DCACHE_LRU_LIST) {
570 [ + + ]: 793 : if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
571 : 708 : d_lru_del(dentry);
572 : : }
573 : : /* if it was on the hash then remove it */
574 : 5757466 : __d_drop(dentry);
575 : 5756451 : dentry_unlist(dentry, parent);
576 [ + + ]: 5760666 : if (parent)
577 : : spin_unlock(&parent->d_lock);
578 [ + + ]: 5758235 : if (dentry->d_inode)
579 : 1841689 : dentry_unlink_inode(dentry);
580 : : else
581 : : spin_unlock(&dentry->d_lock);
582 : 11515628 : this_cpu_dec(nr_dentry);
583 [ + + + + ]: 5760864 : if (dentry->d_op && dentry->d_op->d_release)
584 : 48852 : dentry->d_op->d_release(dentry);
585 : :
586 : : spin_lock(&dentry->d_lock);
587 [ + + ]: 5760775 : if (dentry->d_flags & DCACHE_SHRINK_LIST) {
588 : 85 : dentry->d_flags |= DCACHE_MAY_FREE;
589 : : can_free = false;
590 : : }
591 : : spin_unlock(&dentry->d_lock);
592 [ + + ]: 5760156 : if (likely(can_free))
593 : 5760039 : dentry_free(dentry);
594 : 5761305 : cond_resched();
595 : 5761277 : }
596 : :
597 : 4018 : static struct dentry *__lock_parent(struct dentry *dentry)
598 : : {
599 : : struct dentry *parent;
600 : : rcu_read_lock();
601 : : spin_unlock(&dentry->d_lock);
602 : : again:
603 : 4016 : parent = READ_ONCE(dentry->d_parent);
604 : : spin_lock(&parent->d_lock);
605 : : /*
606 : : * We can't blindly lock dentry until we are sure
607 : : * that we won't violate the locking order.
608 : : * Any changes of dentry->d_parent must have
609 : : * been done with parent->d_lock held, so
610 : : * spin_lock() above is enough of a barrier
611 : : * for checking if it's still our child.
612 : : */
613 [ - + ]: 4018 : if (unlikely(parent != dentry->d_parent)) {
614 : : spin_unlock(&parent->d_lock);
615 : : goto again;
616 : : }
617 : : rcu_read_unlock();
618 [ + - ]: 4018 : if (parent != dentry)
619 : 4018 : spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
620 : : else
621 : : parent = NULL;
622 : 4018 : return parent;
623 : : }
624 : :
625 : 206 : static inline struct dentry *lock_parent(struct dentry *dentry)
626 : : {
627 : 206 : struct dentry *parent = dentry->d_parent;
628 [ - + ]: 206 : if (IS_ROOT(dentry))
629 : : return NULL;
630 [ # # ]: 0 : if (likely(spin_trylock(&parent->d_lock)))
631 : : return parent;
632 : 0 : return __lock_parent(dentry);
633 : : }
634 : :
635 : 8698291 : static inline bool retain_dentry(struct dentry *dentry)
636 : : {
637 [ - + ]: 8698291 : WARN_ON(d_in_lookup(dentry));
638 : :
639 : : /* Unreachable? Get rid of it */
640 [ + + ]: 8699956 : if (unlikely(d_unhashed(dentry)))
641 : : return false;
642 : :
643 [ + + ]: 6491641 : if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
644 : : return false;
645 : :
646 [ + + ]: 6490483 : if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
647 [ + + ]: 3878493 : if (dentry->d_op->d_delete(dentry))
648 : : return false;
649 : : }
650 : : /* retain; LRU fodder */
651 : 4296098 : dentry->d_lockref.count--;
652 [ + + ]: 4296098 : if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
653 : 3236778 : d_lru_add(dentry);
654 [ + + ]: 1059320 : else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
655 : 816913 : dentry->d_flags |= DCACHE_REFERENCED;
656 : : return true;
657 : : }
658 : :
659 : : /*
660 : : * Finish off a dentry we've decided to kill.
661 : : * dentry->d_lock must be held, returns with it unlocked.
662 : : * Returns dentry requiring refcount drop, or NULL if we're done.
663 : : */
664 : 4399254 : static struct dentry *dentry_kill(struct dentry *dentry)
665 : : __releases(dentry->d_lock)
666 : : {
667 : 4399254 : struct inode *inode = dentry->d_inode;
668 : : struct dentry *parent = NULL;
669 : :
670 [ + + + + ]: 4928245 : if (inode && unlikely(!spin_trylock(&inode->i_lock)))
671 : : goto slow_positive;
672 : :
673 [ + + ]: 4398015 : if (!IS_ROOT(dentry)) {
674 : : parent = dentry->d_parent;
675 [ + + ]: 4138446 : if (unlikely(!spin_trylock(&parent->d_lock))) {
676 : 4017 : parent = __lock_parent(dentry);
677 [ + + - + ]: 4018 : if (likely(inode || !dentry->d_inode))
678 : : goto got_locks;
679 : : /* negative that became positive */
680 [ # # ]: 0 : if (parent)
681 : : spin_unlock(&parent->d_lock);
682 : 0 : inode = dentry->d_inode;
683 : 0 : goto slow_positive;
684 : : }
685 : : }
686 : 4395609 : __dentry_kill(dentry);
687 : 4396697 : return parent;
688 : :
689 : : slow_positive:
690 : : spin_unlock(&dentry->d_lock);
691 : : spin_lock(&inode->i_lock);
692 : : spin_lock(&dentry->d_lock);
693 : 206 : parent = lock_parent(dentry);
694 : : got_locks:
695 [ + + ]: 4224 : if (unlikely(dentry->d_lockref.count != 1)) {
696 : 13 : dentry->d_lockref.count--;
697 [ + - ]: 4211 : } else if (likely(!retain_dentry(dentry))) {
698 : 4211 : __dentry_kill(dentry);
699 : 4211 : return parent;
700 : : }
701 : : /* we are keeping it, after all */
702 [ - + ]: 13 : if (inode)
703 : : spin_unlock(&inode->i_lock);
704 [ + - ]: 13 : if (parent)
705 : : spin_unlock(&parent->d_lock);
706 : : spin_unlock(&dentry->d_lock);
707 : 13 : return NULL;
708 : : }
709 : :
710 : : /*
711 : : * Try to do a lockless dput(), and return whether that was successful.
712 : : *
713 : : * If unsuccessful, we return false, having already taken the dentry lock.
714 : : *
715 : : * The caller needs to hold the RCU read lock, so that the dentry is
716 : : * guaranteed to stay around even if the refcount goes down to zero!
717 : : */
718 : 93940656 : static inline bool fast_dput(struct dentry *dentry)
719 : : {
720 : : int ret;
721 : : unsigned int d_flags;
722 : :
723 : : /*
724 : : * If we have a d_op->d_delete() operation, we sould not
725 : : * let the dentry count go to zero, so use "put_or_lock".
726 : : */
727 [ + + ]: 93940656 : if (unlikely(dentry->d_flags & DCACHE_OP_DELETE))
728 : 18438729 : return lockref_put_or_lock(&dentry->d_lockref);
729 : :
730 : : /*
731 : : * .. otherwise, we can try to just decrement the
732 : : * lockref optimistically.
733 : : */
734 : 75501927 : ret = lockref_put_return(&dentry->d_lockref);
735 : :
736 : : /*
737 : : * If the lockref_put_return() failed due to the lock being held
738 : : * by somebody else, the fast path has failed. We will need to
739 : : * get the lock, and then check the count again.
740 : : */
741 [ + + ]: 75503923 : if (unlikely(ret < 0)) {
742 : : spin_lock(&dentry->d_lock);
743 [ + + ]: 22975 : if (dentry->d_lockref.count > 1) {
744 : 22855 : dentry->d_lockref.count--;
745 : : spin_unlock(&dentry->d_lock);
746 : 22855 : return true;
747 : : }
748 : : return false;
749 : : }
750 : :
751 : : /*
752 : : * If we weren't the last ref, we're done.
753 : : */
754 [ + + ]: 75480949 : if (ret)
755 : : return true;
756 : :
757 : : /*
758 : : * Careful, careful. The reference count went down
759 : : * to zero, but we don't hold the dentry lock, so
760 : : * somebody else could get it again, and do another
761 : : * dput(), and we need to not race with that.
762 : : *
763 : : * However, there is a very special and common case
764 : : * where we don't care, because there is nothing to
765 : : * do: the dentry is still hashed, it does not have
766 : : * a 'delete' op, and it's referenced and already on
767 : : * the LRU list.
768 : : *
769 : : * NOTE! Since we aren't locked, these values are
770 : : * not "stable". However, it is sufficient that at
771 : : * some point after we dropped the reference the
772 : : * dentry was hashed and the flags had the proper
773 : : * value. Other dentry users may have re-gotten
774 : : * a reference to the dentry and change that, but
775 : : * our work is done - we can leave the dentry
776 : : * around with a zero refcount.
777 : : */
778 : 7949810 : smp_rmb();
779 : : d_flags = READ_ONCE(dentry->d_flags);
780 : 7949059 : d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED;
781 : :
782 : : /* Nothing to do? Dropping the reference was all we needed? */
783 [ + + + + ]: 11457149 : if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
784 : : return true;
785 : :
786 : : /*
787 : : * Not the fast normal case? Get the lock. We've already decremented
788 : : * the refcount, but we'll need to re-check the situation after
789 : : * getting the lock.
790 : : */
791 : : spin_lock(&dentry->d_lock);
792 : :
793 : : /*
794 : : * Did somebody else grab a reference to it in the meantime, and
795 : : * we're no longer the last user after all? Alternatively, somebody
796 : : * else could have killed it and marked it dead. Either way, we
797 : : * don't need to do anything else.
798 : : */
799 [ + + ]: 4441467 : if (dentry->d_lockref.count) {
800 : : spin_unlock(&dentry->d_lock);
801 : 5 : return true;
802 : : }
803 : :
804 : : /*
805 : : * Re-get the reference we optimistically dropped. We hold the
806 : : * lock, and we just tested that it was zero, so we can just
807 : : * set it to 1.
808 : : */
809 : 4441462 : dentry->d_lockref.count = 1;
810 : 4441462 : return false;
811 : : }
812 : :
813 : :
814 : : /*
815 : : * This is dput
816 : : *
817 : : * This is complicated by the fact that we do not want to put
818 : : * dentries that are no longer on any hash chain on the unused
819 : : * list: we'd much rather just get rid of them immediately.
820 : : *
821 : : * However, that implies that we have to traverse the dentry
822 : : * tree upwards to the parents which might _also_ now be
823 : : * scheduled for deletion (it may have been only waiting for
824 : : * its last child to go away).
825 : : *
826 : : * This tail recursion is done by hand as we don't want to depend
827 : : * on the compiler to always get this right (gcc generally doesn't).
828 : : * Real recursion would eat up our stack space.
829 : : */
830 : :
831 : : /*
832 : : * dput - release a dentry
833 : : * @dentry: dentry to release
834 : : *
835 : : * Release a dentry. This will drop the usage count and if appropriate
836 : : * call the dentry unlink method as well as removing it from the queues and
837 : : * releasing its resources. If the parent dentries were scheduled for release
838 : : * they too may now get deleted.
839 : : */
840 : 107536175 : void dput(struct dentry *dentry)
841 : : {
842 [ + + ]: 219503387 : while (dentry) {
843 : 93901714 : might_sleep();
844 : :
845 : : rcu_read_lock();
846 [ + + ]: 93926904 : if (likely(fast_dput(dentry))) {
847 : : rcu_read_unlock();
848 : : return;
849 : : }
850 : :
851 : : /* Slow case: now with the dentry lock held */
852 : : rcu_read_unlock();
853 : :
854 [ + + ]: 8695386 : if (likely(retain_dentry(dentry))) {
855 : : spin_unlock(&dentry->d_lock);
856 : : return;
857 : : }
858 : :
859 : 4397510 : dentry = dentry_kill(dentry);
860 : : }
861 : : }
862 : : EXPORT_SYMBOL(dput);
863 : :
864 : 1360337 : static void __dput_to_list(struct dentry *dentry, struct list_head *list)
865 : : __must_hold(&dentry->d_lock)
866 : : {
867 [ - + ]: 1360337 : if (dentry->d_flags & DCACHE_SHRINK_LIST) {
868 : : /* let the owner of the list it's on deal with it */
869 : 0 : --dentry->d_lockref.count;
870 : : } else {
871 [ + + ]: 1360337 : if (dentry->d_flags & DCACHE_LRU_LIST)
872 : 213 : d_lru_del(dentry);
873 [ + + ]: 1360313 : if (!--dentry->d_lockref.count)
874 : 57664 : d_shrink_add(dentry, list);
875 : : }
876 : 1360313 : }
877 : :
878 : 10592 : void dput_to_list(struct dentry *dentry, struct list_head *list)
879 : : {
880 : : rcu_read_lock();
881 [ + + ]: 10592 : if (likely(fast_dput(dentry))) {
882 : : rcu_read_unlock();
883 : 10592 : return;
884 : : }
885 : : rcu_read_unlock();
886 [ - + ]: 209 : if (!retain_dentry(dentry))
887 : 0 : __dput_to_list(dentry, list);
888 : : spin_unlock(&dentry->d_lock);
889 : : }
890 : :
891 : : /* This must be called with d_lock held */
892 : : static inline void __dget_dlock(struct dentry *dentry)
893 : : {
894 : 10303134 : dentry->d_lockref.count++;
895 : : }
896 : :
897 : : static inline void __dget(struct dentry *dentry)
898 : : {
899 : 0 : lockref_get(&dentry->d_lockref);
900 : : }
901 : :
902 : 5429579 : struct dentry *dget_parent(struct dentry *dentry)
903 : : {
904 : : int gotref;
905 : : struct dentry *ret;
906 : :
907 : : /*
908 : : * Do optimistic parent lookup without any
909 : : * locking.
910 : : */
911 : : rcu_read_lock();
912 : 5433335 : ret = READ_ONCE(dentry->d_parent);
913 : 5433335 : gotref = lockref_get_not_zero(&ret->d_lockref);
914 : : rcu_read_unlock();
915 [ + - ]: 5434743 : if (likely(gotref)) {
916 [ - + ]: 5439313 : if (likely(ret == READ_ONCE(dentry->d_parent)))
917 : : return ret;
918 : 0 : dput(ret);
919 : : }
920 : :
921 : : repeat:
922 : : /*
923 : : * Don't need rcu_dereference because we re-check it was correct under
924 : : * the lock.
925 : : */
926 : : rcu_read_lock();
927 : 0 : ret = dentry->d_parent;
928 : : spin_lock(&ret->d_lock);
929 [ # # ]: 0 : if (unlikely(ret != dentry->d_parent)) {
930 : : spin_unlock(&ret->d_lock);
931 : : rcu_read_unlock();
932 : : goto repeat;
933 : : }
934 : : rcu_read_unlock();
935 [ # # ]: 0 : BUG_ON(!ret->d_lockref.count);
936 : 0 : ret->d_lockref.count++;
937 : : spin_unlock(&ret->d_lock);
938 : 0 : return ret;
939 : : }
940 : : EXPORT_SYMBOL(dget_parent);
941 : :
942 : : static struct dentry * __d_find_any_alias(struct inode *inode)
943 : : {
944 : : struct dentry *alias;
945 : :
946 [ - + # # : 745017 : if (hlist_empty(&inode->i_dentry))
# # # # ]
947 : : return NULL;
948 : 0 : alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
949 : : __dget(alias);
950 : : return alias;
951 : : }
952 : :
953 : : /**
954 : : * d_find_any_alias - find any alias for a given inode
955 : : * @inode: inode to find an alias for
956 : : *
957 : : * If any aliases exist for the given inode, take and return a
958 : : * reference for one of them. If no aliases exist, return %NULL.
959 : : */
960 : 0 : struct dentry *d_find_any_alias(struct inode *inode)
961 : : {
962 : : struct dentry *de;
963 : :
964 : : spin_lock(&inode->i_lock);
965 : : de = __d_find_any_alias(inode);
966 : : spin_unlock(&inode->i_lock);
967 : 0 : return de;
968 : : }
969 : : EXPORT_SYMBOL(d_find_any_alias);
970 : :
971 : : /**
972 : : * d_find_alias - grab a hashed alias of inode
973 : : * @inode: inode in question
974 : : *
975 : : * If inode has a hashed alias, or is a directory and has any alias,
976 : : * acquire the reference to alias and return it. Otherwise return NULL.
977 : : * Notice that if inode is a directory there can be only one alias and
978 : : * it can be unhashed only if it has no children, or if it is the root
979 : : * of a filesystem, or if the directory was renamed and d_revalidate
980 : : * was the first vfs operation to notice.
981 : : *
982 : : * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
983 : : * any other hashed alias over that one.
984 : : */
985 : 0 : static struct dentry *__d_find_alias(struct inode *inode)
986 : : {
987 : : struct dentry *alias;
988 : :
989 [ # # ]: 0 : if (S_ISDIR(inode->i_mode))
990 : 0 : return __d_find_any_alias(inode);
991 : :
992 [ # # # # : 0 : hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
# # ]
993 : : spin_lock(&alias->d_lock);
994 [ # # ]: 0 : if (!d_unhashed(alias)) {
995 : : __dget_dlock(alias);
996 : : spin_unlock(&alias->d_lock);
997 : 0 : return alias;
998 : : }
999 : : spin_unlock(&alias->d_lock);
1000 : : }
1001 : : return NULL;
1002 : : }
1003 : :
1004 : 0 : struct dentry *d_find_alias(struct inode *inode)
1005 : : {
1006 : : struct dentry *de = NULL;
1007 : :
1008 [ # # ]: 0 : if (!hlist_empty(&inode->i_dentry)) {
1009 : : spin_lock(&inode->i_lock);
1010 : 0 : de = __d_find_alias(inode);
1011 : : spin_unlock(&inode->i_lock);
1012 : : }
1013 : 0 : return de;
1014 : : }
1015 : : EXPORT_SYMBOL(d_find_alias);
1016 : :
1017 : : /*
1018 : : * Try to kill dentries associated with this inode.
1019 : : * WARNING: you must own a reference to inode.
1020 : : */
1021 : 0 : void d_prune_aliases(struct inode *inode)
1022 : : {
1023 : : struct dentry *dentry;
1024 : : restart:
1025 : : spin_lock(&inode->i_lock);
1026 [ # # # # : 0 : hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
# # ]
1027 : : spin_lock(&dentry->d_lock);
1028 [ # # ]: 0 : if (!dentry->d_lockref.count) {
1029 : 0 : struct dentry *parent = lock_parent(dentry);
1030 [ # # ]: 0 : if (likely(!dentry->d_lockref.count)) {
1031 : 0 : __dentry_kill(dentry);
1032 : 0 : dput(parent);
1033 : 0 : goto restart;
1034 : : }
1035 [ # # ]: 0 : if (parent)
1036 : : spin_unlock(&parent->d_lock);
1037 : : }
1038 : : spin_unlock(&dentry->d_lock);
1039 : : }
1040 : : spin_unlock(&inode->i_lock);
1041 : 0 : }
1042 : : EXPORT_SYMBOL(d_prune_aliases);
1043 : :
1044 : : /*
1045 : : * Lock a dentry from shrink list.
1046 : : * Called under rcu_read_lock() and dentry->d_lock; the former
1047 : : * guarantees that nothing we access will be freed under us.
1048 : : * Note that dentry is *not* protected from concurrent dentry_kill(),
1049 : : * d_delete(), etc.
1050 : : *
1051 : : * Return false if dentry has been disrupted or grabbed, leaving
1052 : : * the caller to kick it off-list. Otherwise, return true and have
1053 : : * that dentry's inode and parent both locked.
1054 : : */
1055 : 1367736 : static bool shrink_lock_dentry(struct dentry *dentry)
1056 : : {
1057 : : struct inode *inode;
1058 : : struct dentry *parent;
1059 : :
1060 [ + + ]: 1367736 : if (dentry->d_lockref.count)
1061 : : return false;
1062 : :
1063 : 1360319 : inode = dentry->d_inode;
1064 [ + + - + ]: 2673242 : if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
1065 : : spin_unlock(&dentry->d_lock);
1066 : : spin_lock(&inode->i_lock);
1067 : : spin_lock(&dentry->d_lock);
1068 [ # # ]: 0 : if (unlikely(dentry->d_lockref.count))
1069 : : goto out;
1070 : : /* changed inode means that somebody had grabbed it */
1071 [ # # ]: 0 : if (unlikely(inode != dentry->d_inode))
1072 : : goto out;
1073 : : }
1074 : :
1075 : 1360324 : parent = dentry->d_parent;
1076 [ + + + + ]: 2720664 : if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock)))
1077 : : return true;
1078 : :
1079 : : spin_unlock(&dentry->d_lock);
1080 : : spin_lock(&parent->d_lock);
1081 [ - + ]: 10 : if (unlikely(parent != dentry->d_parent)) {
1082 : : spin_unlock(&parent->d_lock);
1083 : : spin_lock(&dentry->d_lock);
1084 : : goto out;
1085 : : }
1086 : 10 : spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
1087 [ - + ]: 10 : if (likely(!dentry->d_lockref.count))
1088 : : return true;
1089 : : spin_unlock(&parent->d_lock);
1090 : : out:
1091 [ # # ]: 0 : if (inode)
1092 : : spin_unlock(&inode->i_lock);
1093 : : return false;
1094 : : }
1095 : :
1096 : 295589 : void shrink_dentry_list(struct list_head *list)
1097 : : {
1098 [ + + ]: 1958834 : while (!list_empty(list)) {
1099 : : struct dentry *dentry, *parent;
1100 : :
1101 : 1367604 : dentry = list_entry(list->prev, struct dentry, d_lru);
1102 : : spin_lock(&dentry->d_lock);
1103 : : rcu_read_lock();
1104 [ + + ]: 1367649 : if (!shrink_lock_dentry(dentry)) {
1105 : : bool can_free = false;
1106 : : rcu_read_unlock();
1107 : 7394 : d_shrink_del(dentry);
1108 [ + + ]: 7394 : if (dentry->d_lockref.count < 0)
1109 : 85 : can_free = dentry->d_flags & DCACHE_MAY_FREE;
1110 : : spin_unlock(&dentry->d_lock);
1111 [ + + ]: 7394 : if (can_free)
1112 : 85 : dentry_free(dentry);
1113 : 7394 : continue;
1114 : : }
1115 : : rcu_read_unlock();
1116 : 1360262 : d_shrink_del(dentry);
1117 : 1360191 : parent = dentry->d_parent;
1118 [ + + ]: 1360191 : if (parent != dentry)
1119 : 1360226 : __dput_to_list(parent, list);
1120 : 1360183 : __dentry_kill(dentry);
1121 : : }
1122 : 295641 : }
1123 : :
1124 : 0 : static enum lru_status dentry_lru_isolate(struct list_head *item,
1125 : : struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
1126 : : {
1127 : : struct list_head *freeable = arg;
1128 : 0 : struct dentry *dentry = container_of(item, struct dentry, d_lru);
1129 : :
1130 : :
1131 : : /*
1132 : : * we are inverting the lru lock/dentry->d_lock here,
1133 : : * so use a trylock. If we fail to get the lock, just skip
1134 : : * it
1135 : : */
1136 [ # # ]: 0 : if (!spin_trylock(&dentry->d_lock))
1137 : : return LRU_SKIP;
1138 : :
1139 : : /*
1140 : : * Referenced dentries are still in use. If they have active
1141 : : * counts, just remove them from the LRU. Otherwise give them
1142 : : * another pass through the LRU.
1143 : : */
1144 [ # # ]: 0 : if (dentry->d_lockref.count) {
1145 : 0 : d_lru_isolate(lru, dentry);
1146 : : spin_unlock(&dentry->d_lock);
1147 : 0 : return LRU_REMOVED;
1148 : : }
1149 : :
1150 [ # # ]: 0 : if (dentry->d_flags & DCACHE_REFERENCED) {
1151 : 0 : dentry->d_flags &= ~DCACHE_REFERENCED;
1152 : : spin_unlock(&dentry->d_lock);
1153 : :
1154 : : /*
1155 : : * The list move itself will be made by the common LRU code. At
1156 : : * this point, we've dropped the dentry->d_lock but keep the
1157 : : * lru lock. This is safe to do, since every list movement is
1158 : : * protected by the lru lock even if both locks are held.
1159 : : *
1160 : : * This is guaranteed by the fact that all LRU management
1161 : : * functions are intermediated by the LRU API calls like
1162 : : * list_lru_add and list_lru_del. List movement in this file
1163 : : * only ever occur through this functions or through callbacks
1164 : : * like this one, that are called from the LRU API.
1165 : : *
1166 : : * The only exceptions to this are functions like
1167 : : * shrink_dentry_list, and code that first checks for the
1168 : : * DCACHE_SHRINK_LIST flag. Those are guaranteed to be
1169 : : * operating only with stack provided lists after they are
1170 : : * properly isolated from the main list. It is thus, always a
1171 : : * local access.
1172 : : */
1173 : 0 : return LRU_ROTATE;
1174 : : }
1175 : :
1176 : 0 : d_lru_shrink_move(lru, dentry, freeable);
1177 : : spin_unlock(&dentry->d_lock);
1178 : :
1179 : 0 : return LRU_REMOVED;
1180 : : }
1181 : :
1182 : : /**
1183 : : * prune_dcache_sb - shrink the dcache
1184 : : * @sb: superblock
1185 : : * @sc: shrink control, passed to list_lru_shrink_walk()
1186 : : *
1187 : : * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This
1188 : : * is done when we need more memory and called from the superblock shrinker
1189 : : * function.
1190 : : *
1191 : : * This function may fail to free any resources if all the dentries are in
1192 : : * use.
1193 : : */
1194 : 0 : long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc)
1195 : : {
1196 : 0 : LIST_HEAD(dispose);
1197 : : long freed;
1198 : :
1199 : 0 : freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc,
1200 : : dentry_lru_isolate, &dispose);
1201 : 0 : shrink_dentry_list(&dispose);
1202 : 0 : return freed;
1203 : : }
1204 : :
1205 : 205352 : static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
1206 : : struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
1207 : : {
1208 : : struct list_head *freeable = arg;
1209 : 205352 : struct dentry *dentry = container_of(item, struct dentry, d_lru);
1210 : :
1211 : : /*
1212 : : * we are inverting the lru lock/dentry->d_lock here,
1213 : : * so use a trylock. If we fail to get the lock, just skip
1214 : : * it
1215 : : */
1216 [ + - ]: 205352 : if (!spin_trylock(&dentry->d_lock))
1217 : : return LRU_SKIP;
1218 : :
1219 : 205352 : d_lru_shrink_move(lru, dentry, freeable);
1220 : : spin_unlock(&dentry->d_lock);
1221 : :
1222 : 205352 : return LRU_REMOVED;
1223 : : }
1224 : :
1225 : :
1226 : : /**
1227 : : * shrink_dcache_sb - shrink dcache for a superblock
1228 : : * @sb: superblock
1229 : : *
1230 : : * Shrink the dcache for the specified super block. This is used to free
1231 : : * the dcache before unmounting a file system.
1232 : : */
1233 : 828 : void shrink_dcache_sb(struct super_block *sb)
1234 : : {
1235 : : do {
1236 : 951 : LIST_HEAD(dispose);
1237 : :
1238 : 951 : list_lru_walk(&sb->s_dentry_lru,
1239 : : dentry_lru_isolate_shrink, &dispose, 1024);
1240 : 951 : shrink_dentry_list(&dispose);
1241 [ + + ]: 951 : } while (list_lru_count(&sb->s_dentry_lru) > 0);
1242 : 828 : }
1243 : : EXPORT_SYMBOL(shrink_dcache_sb);
1244 : :
1245 : : /**
1246 : : * enum d_walk_ret - action to talke during tree walk
1247 : : * @D_WALK_CONTINUE: contrinue walk
1248 : : * @D_WALK_QUIT: quit walk
1249 : : * @D_WALK_NORETRY: quit when retry is needed
1250 : : * @D_WALK_SKIP: skip this dentry and its children
1251 : : */
1252 : : enum d_walk_ret {
1253 : : D_WALK_CONTINUE,
1254 : : D_WALK_QUIT,
1255 : : D_WALK_NORETRY,
1256 : : D_WALK_SKIP,
1257 : : };
1258 : :
1259 : : /**
1260 : : * d_walk - walk the dentry tree
1261 : : * @parent: start of walk
1262 : : * @data: data passed to @enter() and @finish()
1263 : : * @enter: callback when first entering the dentry
1264 : : *
1265 : : * The @enter() callbacks are called with d_lock held.
1266 : : */
1267 : 809032 : static void d_walk(struct dentry *parent, void *data,
1268 : : enum d_walk_ret (*enter)(void *, struct dentry *))
1269 : : {
1270 : : struct dentry *this_parent;
1271 : : struct list_head *next;
1272 : 809032 : unsigned seq = 0;
1273 : : enum d_walk_ret ret;
1274 : : bool retry = true;
1275 : :
1276 : : again:
1277 : 809033 : read_seqbegin_or_lock(&rename_lock, &seq);
1278 : : this_parent = parent;
1279 : : spin_lock(&this_parent->d_lock);
1280 : :
1281 : 809065 : ret = enter(data, this_parent);
1282 [ - + + ]: 809044 : switch (ret) {
1283 : : case D_WALK_CONTINUE:
1284 : : break;
1285 : : case D_WALK_QUIT:
1286 : : case D_WALK_SKIP:
1287 : : goto out_unlock;
1288 : : case D_WALK_NORETRY:
1289 : : retry = false;
1290 : 0 : break;
1291 : : }
1292 : : repeat:
1293 : 835906 : next = this_parent->d_subdirs.next;
1294 : : resume:
1295 [ + + ]: 1949135 : while (next != &this_parent->d_subdirs) {
1296 : : struct list_head *tmp = next;
1297 : 1132624 : struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
1298 : 1132624 : next = tmp->next;
1299 : :
1300 [ - + ]: 1132624 : if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR))
1301 : 0 : continue;
1302 : :
1303 : 1132624 : spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
1304 : :
1305 : 1132706 : ret = enter(data, dentry);
1306 [ + + - + ]: 1132710 : switch (ret) {
1307 : : case D_WALK_CONTINUE:
1308 : : break;
1309 : : case D_WALK_QUIT:
1310 : : spin_unlock(&dentry->d_lock);
1311 : : goto out_unlock;
1312 : : case D_WALK_NORETRY:
1313 : : retry = false;
1314 : 1126119 : break;
1315 : : case D_WALK_SKIP:
1316 : : spin_unlock(&dentry->d_lock);
1317 : 0 : continue;
1318 : : }
1319 : :
1320 [ + + ]: 2262144 : if (!list_empty(&dentry->d_subdirs)) {
1321 : : spin_unlock(&this_parent->d_lock);
1322 : : spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
1323 : 26916 : this_parent = dentry;
1324 : : spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
1325 : 26916 : goto repeat;
1326 : : }
1327 : : spin_unlock(&dentry->d_lock);
1328 : : }
1329 : : /*
1330 : : * All done at this level ... ascend and resume the search.
1331 : : */
1332 : : rcu_read_lock();
1333 : : ascend:
1334 [ + + ]: 834062 : if (this_parent != parent) {
1335 : : struct dentry *child = this_parent;
1336 : 26667 : this_parent = child->d_parent;
1337 : :
1338 : : spin_unlock(&child->d_lock);
1339 : : spin_lock(&this_parent->d_lock);
1340 : :
1341 : : /* might go back up the wrong parent if we have had a rename. */
1342 [ + + ]: 53332 : if (need_seqretry(&rename_lock, seq))
1343 : : goto rename_retry;
1344 : : /* go into the first sibling still alive */
1345 : : do {
1346 : 26644 : next = child->d_child.next;
1347 [ + + ]: 26644 : if (next == &this_parent->d_subdirs)
1348 : : goto ascend;
1349 : 9077 : child = list_entry(next, struct dentry, d_child);
1350 [ - + ]: 9077 : } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
1351 : : rcu_read_unlock();
1352 : : goto resume;
1353 : : }
1354 [ + + ]: 1614758 : if (need_seqretry(&rename_lock, seq))
1355 : : goto rename_retry;
1356 : : rcu_read_unlock();
1357 : :
1358 : : out_unlock:
1359 : : spin_unlock(&this_parent->d_lock);
1360 : 809069 : done_seqretry(&rename_lock, seq);
1361 : : return;
1362 : :
1363 : : rename_retry:
1364 : : spin_unlock(&this_parent->d_lock);
1365 : : rcu_read_unlock();
1366 [ - + ]: 29 : BUG_ON(seq & 1);
1367 [ + + ]: 29 : if (!retry)
1368 : : return;
1369 : 1 : seq = 1;
1370 : 1 : goto again;
1371 : : }
1372 : :
1373 : : struct check_mount {
1374 : : struct vfsmount *mnt;
1375 : : unsigned int mounted;
1376 : : };
1377 : :
1378 : 0 : static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry)
1379 : : {
1380 : : struct check_mount *info = data;
1381 : 0 : struct path path = { .mnt = info->mnt, .dentry = dentry };
1382 : :
1383 [ # # ]: 0 : if (likely(!d_mountpoint(dentry)))
1384 : : return D_WALK_CONTINUE;
1385 [ # # ]: 0 : if (__path_is_mountpoint(&path)) {
1386 : 0 : info->mounted = 1;
1387 : 0 : return D_WALK_QUIT;
1388 : : }
1389 : : return D_WALK_CONTINUE;
1390 : : }
1391 : :
1392 : : /**
1393 : : * path_has_submounts - check for mounts over a dentry in the
1394 : : * current namespace.
1395 : : * @parent: path to check.
1396 : : *
1397 : : * Return true if the parent or its subdirectories contain
1398 : : * a mount point in the current namespace.
1399 : : */
1400 : 0 : int path_has_submounts(const struct path *parent)
1401 : : {
1402 : 0 : struct check_mount data = { .mnt = parent->mnt, .mounted = 0 };
1403 : :
1404 : : read_seqlock_excl(&mount_lock);
1405 : 0 : d_walk(parent->dentry, &data, path_check_mount);
1406 : : read_sequnlock_excl(&mount_lock);
1407 : :
1408 : 0 : return data.mounted;
1409 : : }
1410 : : EXPORT_SYMBOL(path_has_submounts);
1411 : :
1412 : : /*
1413 : : * Called by mount code to set a mountpoint and check if the mountpoint is
1414 : : * reachable (e.g. NFS can unhash a directory dentry and then the complete
1415 : : * subtree can become unreachable).
1416 : : *
1417 : : * Only one of d_invalidate() and d_set_mounted() must succeed. For
1418 : : * this reason take rename_lock and d_lock on dentry and ancestors.
1419 : : */
1420 : 21148 : int d_set_mounted(struct dentry *dentry)
1421 : : {
1422 : : struct dentry *p;
1423 : : int ret = -ENOENT;
1424 : : write_seqlock(&rename_lock);
1425 [ + + ]: 28618 : for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
1426 : : /* Need exclusion wrt. d_invalidate() */
1427 : : spin_lock(&p->d_lock);
1428 [ - + ]: 7470 : if (unlikely(d_unhashed(p))) {
1429 : : spin_unlock(&p->d_lock);
1430 : : goto out;
1431 : : }
1432 : : spin_unlock(&p->d_lock);
1433 : : }
1434 : : spin_lock(&dentry->d_lock);
1435 [ + - ]: 21148 : if (!d_unlinked(dentry)) {
1436 : : ret = -EBUSY;
1437 [ + - ]: 21148 : if (!d_mountpoint(dentry)) {
1438 : 21148 : dentry->d_flags |= DCACHE_MOUNTED;
1439 : : ret = 0;
1440 : : }
1441 : : }
1442 : : spin_unlock(&dentry->d_lock);
1443 : : out:
1444 : : write_sequnlock(&rename_lock);
1445 : 21148 : return ret;
1446 : : }
1447 : :
1448 : : /*
1449 : : * Search the dentry child list of the specified parent,
1450 : : * and move any unused dentries to the end of the unused
1451 : : * list for prune_dcache(). We descend to the next level
1452 : : * whenever the d_subdirs list is non-empty and continue
1453 : : * searching.
1454 : : *
1455 : : * It returns zero iff there are no unused children,
1456 : : * otherwise it returns the number of children moved to
1457 : : * the end of the unused list. This may not be the total
1458 : : * number of unused children, because select_parent can
1459 : : * drop the lock and return early due to latency
1460 : : * constraints.
1461 : : */
1462 : :
1463 : : struct select_data {
1464 : : struct dentry *start;
1465 : : union {
1466 : : long found;
1467 : : struct dentry *victim;
1468 : : };
1469 : : struct list_head dispose;
1470 : : };
1471 : :
1472 : 1690019 : static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
1473 : : {
1474 : : struct select_data *data = _data;
1475 : : enum d_walk_ret ret = D_WALK_CONTINUE;
1476 : :
1477 [ + + ]: 1690019 : if (data->start == dentry)
1478 : : goto out;
1479 : :
1480 [ + + ]: 1132527 : if (dentry->d_flags & DCACHE_SHRINK_LIST) {
1481 : 1006 : data->found++;
1482 : : } else {
1483 [ + + ]: 1131521 : if (dentry->d_flags & DCACHE_LRU_LIST)
1484 : 1104602 : d_lru_del(dentry);
1485 [ + + ]: 1131456 : if (!dentry->d_lockref.count) {
1486 : 1104636 : d_shrink_add(dentry, &data->dispose);
1487 : 1104640 : data->found++;
1488 : : }
1489 : : }
1490 : : /*
1491 : : * We can return to the caller if we have found some (this
1492 : : * ensures forward progress). We'll be coming back to find
1493 : : * the rest.
1494 : : */
1495 [ + + ]: 2264932 : if (!list_empty(&data->dispose))
1496 [ + + ]: 1127616 : ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
1497 : : out:
1498 : 1689964 : return ret;
1499 : : }
1500 : :
1501 : 207 : static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry)
1502 : : {
1503 : : struct select_data *data = _data;
1504 : : enum d_walk_ret ret = D_WALK_CONTINUE;
1505 : :
1506 [ + + ]: 207 : if (data->start == dentry)
1507 : : goto out;
1508 : :
1509 [ + + ]: 128 : if (dentry->d_flags & DCACHE_SHRINK_LIST) {
1510 [ + - ]: 79 : if (!dentry->d_lockref.count) {
1511 : : rcu_read_lock();
1512 : 79 : data->victim = dentry;
1513 : 79 : return D_WALK_QUIT;
1514 : : }
1515 : : } else {
1516 [ - + ]: 49 : if (dentry->d_flags & DCACHE_LRU_LIST)
1517 : 0 : d_lru_del(dentry);
1518 [ - + ]: 49 : if (!dentry->d_lockref.count)
1519 : 0 : d_shrink_add(dentry, &data->dispose);
1520 : : }
1521 : : /*
1522 : : * We can return to the caller if we have found some (this
1523 : : * ensures forward progress). We'll be coming back to find
1524 : : * the rest.
1525 : : */
1526 [ - + ]: 98 : if (!list_empty(&data->dispose))
1527 [ # # ]: 0 : ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
1528 : : out:
1529 : 128 : return ret;
1530 : : }
1531 : :
1532 : : /**
1533 : : * shrink_dcache_parent - prune dcache
1534 : : * @parent: parent of entries to prune
1535 : : *
1536 : : * Prune the dcache to remove unused children of the parent dentry.
1537 : : */
1538 : 279681 : void shrink_dcache_parent(struct dentry *parent)
1539 : : {
1540 : : for (;;) {
1541 : 557483 : struct select_data data = {.start = parent};
1542 : :
1543 : : INIT_LIST_HEAD(&data.dispose);
1544 : 557483 : d_walk(parent, &data, select_collect);
1545 : :
1546 [ + + ]: 557488 : if (!list_empty(&data.dispose)) {
1547 : 277724 : shrink_dentry_list(&data.dispose);
1548 : 277723 : continue;
1549 : : }
1550 : :
1551 : 279764 : cond_resched();
1552 [ + + ]: 279753 : if (!data.found)
1553 : : break;
1554 : 79 : data.victim = NULL;
1555 : 79 : d_walk(parent, &data, select_collect2);
1556 [ + - ]: 79 : if (data.victim) {
1557 : : struct dentry *parent;
1558 : : spin_lock(&data.victim->d_lock);
1559 [ - + ]: 79 : if (!shrink_lock_dentry(data.victim)) {
1560 : 0 : spin_unlock(&data.victim->d_lock);
1561 : : rcu_read_unlock();
1562 : : } else {
1563 : : rcu_read_unlock();
1564 : 79 : parent = data.victim->d_parent;
1565 [ + - ]: 79 : if (parent != data.victim)
1566 : 79 : __dput_to_list(parent, &data.dispose);
1567 : 79 : __dentry_kill(data.victim);
1568 : : }
1569 : : }
1570 [ + + ]: 79 : if (!list_empty(&data.dispose))
1571 : 6 : shrink_dentry_list(&data.dispose);
1572 : : }
1573 : 279674 : }
1574 : : EXPORT_SYMBOL(shrink_dcache_parent);
1575 : :
1576 : 2 : static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
1577 : : {
1578 : : /* it has busy descendents; complain about those instead */
1579 [ + - ]: 4 : if (!list_empty(&dentry->d_subdirs))
1580 : : return D_WALK_CONTINUE;
1581 : :
1582 : : /* root with refcount 1 is fine */
1583 [ + - - + ]: 2 : if (dentry == _data && dentry->d_lockref.count == 1)
1584 : : return D_WALK_CONTINUE;
1585 : :
1586 [ # # ]: 0 : printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} "
1587 : : " still in use (%d) [unmount of %s %s]\n",
1588 : : dentry,
1589 : 0 : dentry->d_inode ?
1590 : : dentry->d_inode->i_ino : 0UL,
1591 : : dentry,
1592 : : dentry->d_lockref.count,
1593 : 0 : dentry->d_sb->s_type->name,
1594 : 0 : dentry->d_sb->s_id);
1595 : 0 : WARN_ON(1);
1596 : 0 : return D_WALK_CONTINUE;
1597 : : }
1598 : :
1599 : 2 : static void do_one_tree(struct dentry *dentry)
1600 : : {
1601 : 2 : shrink_dcache_parent(dentry);
1602 : 2 : d_walk(dentry, dentry, umount_check);
1603 : 2 : d_drop(dentry);
1604 : 2 : dput(dentry);
1605 : 2 : }
1606 : :
1607 : : /*
1608 : : * destroy the dentries attached to a superblock on unmounting
1609 : : */
1610 : 2 : void shrink_dcache_for_umount(struct super_block *sb)
1611 : : {
1612 : : struct dentry *dentry;
1613 : :
1614 [ - + ]: 2 : WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
1615 : :
1616 : 2 : dentry = sb->s_root;
1617 : 2 : sb->s_root = NULL;
1618 : 2 : do_one_tree(dentry);
1619 : :
1620 [ - + ]: 4 : while (!hlist_bl_empty(&sb->s_roots)) {
1621 : 0 : dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_roots), struct dentry, d_hash));
1622 : 0 : do_one_tree(dentry);
1623 : : }
1624 : 2 : }
1625 : :
1626 : 251536 : static enum d_walk_ret find_submount(void *_data, struct dentry *dentry)
1627 : : {
1628 : : struct dentry **victim = _data;
1629 [ - + ]: 251536 : if (d_mountpoint(dentry)) {
1630 : : __dget_dlock(dentry);
1631 : 0 : *victim = dentry;
1632 : 0 : return D_WALK_QUIT;
1633 : : }
1634 : : return D_WALK_CONTINUE;
1635 : : }
1636 : :
1637 : : /**
1638 : : * d_invalidate - detach submounts, prune dcache, and drop
1639 : : * @dentry: dentry to invalidate (aka detach, prune and drop)
1640 : : */
1641 : 251945 : void d_invalidate(struct dentry *dentry)
1642 : : {
1643 : : bool had_submounts = false;
1644 : : spin_lock(&dentry->d_lock);
1645 [ - + ]: 251944 : if (d_unhashed(dentry)) {
1646 : : spin_unlock(&dentry->d_lock);
1647 : : return;
1648 : : }
1649 : 251944 : __d_drop(dentry);
1650 : : spin_unlock(&dentry->d_lock);
1651 : :
1652 : : /* Negative dentries can be dropped without further checks */
1653 [ + + ]: 251942 : if (!dentry->d_inode)
1654 : : return;
1655 : :
1656 : 251518 : shrink_dcache_parent(dentry);
1657 : : for (;;) {
1658 : 251502 : struct dentry *victim = NULL;
1659 : 251502 : d_walk(dentry, &victim, find_submount);
1660 [ + - ]: 251515 : if (!victim) {
1661 [ - + ]: 251515 : if (had_submounts)
1662 : 0 : shrink_dcache_parent(dentry);
1663 : 251531 : return;
1664 : : }
1665 : : had_submounts = true;
1666 : : detach_mounts(victim);
1667 : 0 : dput(victim);
1668 : 0 : }
1669 : : }
1670 : : EXPORT_SYMBOL(d_invalidate);
1671 : :
1672 : : /**
1673 : : * __d_alloc - allocate a dcache entry
1674 : : * @sb: filesystem it will belong to
1675 : : * @name: qstr of the name
1676 : : *
1677 : : * Allocates a dentry. It returns %NULL if there is insufficient memory
1678 : : * available. On a success the dentry is returned. The name passed in is
1679 : : * copied and the copy passed in may be reused after this call.
1680 : : */
1681 : :
1682 : 10736475 : struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
1683 : : {
1684 : : struct dentry *dentry;
1685 : : char *dname;
1686 : : int err;
1687 : :
1688 : 10736475 : dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
1689 [ + + ]: 10740294 : if (!dentry)
1690 : : return NULL;
1691 : :
1692 : : /*
1693 : : * We guarantee that the inline name is always NUL-terminated.
1694 : : * This way the memcpy() done by the name switching in rename
1695 : : * will still always have a NUL at the end, even if we might
1696 : : * be overwriting an internal NUL character
1697 : : */
1698 : 10740144 : dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
1699 [ + + ]: 10740144 : if (unlikely(!name)) {
1700 : : name = &slash_name;
1701 : 96839 : dname = dentry->d_iname;
1702 [ + + ]: 10643305 : } else if (name->len > DNAME_INLINE_LEN-1) {
1703 : : size_t size = offsetof(struct external_name, name[1]);
1704 : 415952 : struct external_name *p = kmalloc(size + name->len,
1705 : : GFP_KERNEL_ACCOUNT |
1706 : : __GFP_RECLAIMABLE);
1707 [ - + ]: 415943 : if (!p) {
1708 : 0 : kmem_cache_free(dentry_cache, dentry);
1709 : 0 : return NULL;
1710 : : }
1711 : : atomic_set(&p->u.count, 1);
1712 : 415943 : dname = p->name;
1713 : : } else {
1714 : 10227353 : dname = dentry->d_iname;
1715 : : }
1716 : :
1717 : 10740135 : dentry->d_name.len = name->len;
1718 : 10740135 : dentry->d_name.hash = name->hash;
1719 : 10740135 : memcpy(dname, name->name, name->len);
1720 : 10740135 : dname[name->len] = 0;
1721 : :
1722 : : /* Make sure we always see the terminating NUL character */
1723 : 10740135 : smp_store_release(&dentry->d_name.name, dname); /* ^^^ */
1724 : :
1725 : 10727118 : dentry->d_lockref.count = 1;
1726 : 10727118 : dentry->d_flags = 0;
1727 : 10727118 : spin_lock_init(&dentry->d_lock);
1728 : : seqcount_init(&dentry->d_seq);
1729 : 10727118 : dentry->d_inode = NULL;
1730 : 10727118 : dentry->d_parent = dentry;
1731 : 10727118 : dentry->d_sb = sb;
1732 : 10727118 : dentry->d_op = NULL;
1733 : 10727118 : dentry->d_fsdata = NULL;
1734 : : INIT_HLIST_BL_NODE(&dentry->d_hash);
1735 : 10727118 : INIT_LIST_HEAD(&dentry->d_lru);
1736 : 10727118 : INIT_LIST_HEAD(&dentry->d_subdirs);
1737 : : INIT_HLIST_NODE(&dentry->d_u.d_alias);
1738 : 10727118 : INIT_LIST_HEAD(&dentry->d_child);
1739 : 10727118 : d_set_d_op(dentry, dentry->d_sb->s_d_op);
1740 : :
1741 [ + + + + ]: 10735237 : if (dentry->d_op && dentry->d_op->d_init) {
1742 : 1035 : err = dentry->d_op->d_init(dentry);
1743 [ - + ]: 1035 : if (err) {
1744 [ # # ]: 0 : if (dname_external(dentry))
1745 : 0 : kfree(external_name(dentry));
1746 : 0 : kmem_cache_free(dentry_cache, dentry);
1747 : 0 : return NULL;
1748 : : }
1749 : : }
1750 : :
1751 : 21466150 : this_cpu_inc(nr_dentry);
1752 : :
1753 : 10739248 : return dentry;
1754 : : }
1755 : :
1756 : : /**
1757 : : * d_alloc - allocate a dcache entry
1758 : : * @parent: parent of entry to allocate
1759 : : * @name: qstr of the name
1760 : : *
1761 : : * Allocates a dentry. It returns %NULL if there is insufficient memory
1762 : : * available. On a success the dentry is returned. The name passed in is
1763 : : * copied and the copy passed in may be reused after this call.
1764 : : */
1765 : 10302951 : struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1766 : : {
1767 : 10302951 : struct dentry *dentry = __d_alloc(parent->d_sb, name);
1768 [ + + ]: 10305608 : if (!dentry)
1769 : : return NULL;
1770 : : spin_lock(&parent->d_lock);
1771 : : /*
1772 : : * don't need child lock because it is not subject
1773 : : * to concurrency here
1774 : : */
1775 : : __dget_dlock(parent);
1776 : 10303134 : dentry->d_parent = parent;
1777 : 10303134 : list_add(&dentry->d_child, &parent->d_subdirs);
1778 : : spin_unlock(&parent->d_lock);
1779 : :
1780 : 10307124 : return dentry;
1781 : : }
1782 : : EXPORT_SYMBOL(d_alloc);
1783 : :
1784 : 0 : struct dentry *d_alloc_anon(struct super_block *sb)
1785 : : {
1786 : 96840 : return __d_alloc(sb, NULL);
1787 : : }
1788 : : EXPORT_SYMBOL(d_alloc_anon);
1789 : :
1790 : 88145 : struct dentry *d_alloc_cursor(struct dentry * parent)
1791 : : {
1792 : 88145 : struct dentry *dentry = d_alloc_anon(parent->d_sb);
1793 [ + + ]: 88145 : if (dentry) {
1794 : 88144 : dentry->d_flags |= DCACHE_DENTRY_CURSOR;
1795 : 88145 : dentry->d_parent = dget(parent);
1796 : : }
1797 : 88146 : return dentry;
1798 : : }
1799 : :
1800 : : /**
1801 : : * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
1802 : : * @sb: the superblock
1803 : : * @name: qstr of the name
1804 : : *
1805 : : * For a filesystem that just pins its dentries in memory and never
1806 : : * performs lookups at all, return an unhashed IS_ROOT dentry.
1807 : : * This is used for pipes, sockets et.al. - the stuff that should
1808 : : * never be anyone's children or parents. Unlike all other
1809 : : * dentries, these will not have RCU delay between dropping the
1810 : : * last reference and freeing them.
1811 : : *
1812 : : * The only user is alloc_file_pseudo() and that's what should
1813 : : * be considered a public interface. Don't use directly.
1814 : : */
1815 : 336051 : struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1816 : : {
1817 : 336051 : struct dentry *dentry = __d_alloc(sb, name);
1818 [ + + ]: 335969 : if (likely(dentry))
1819 : 335940 : dentry->d_flags |= DCACHE_NORCU;
1820 : 335969 : return dentry;
1821 : : }
1822 : :
1823 : 2272 : struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1824 : : {
1825 : : struct qstr q;
1826 : :
1827 : 2272 : q.name = name;
1828 : 2272 : q.hash_len = hashlen_string(parent, name);
1829 : 2272 : return d_alloc(parent, &q);
1830 : : }
1831 : : EXPORT_SYMBOL(d_alloc_name);
1832 : :
1833 : 16178277 : void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1834 : : {
1835 [ - + # # ]: 16178277 : WARN_ON_ONCE(dentry->d_op);
1836 [ - + # # ]: 16175882 : WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
1837 : : DCACHE_OP_COMPARE |
1838 : : DCACHE_OP_REVALIDATE |
1839 : : DCACHE_OP_WEAK_REVALIDATE |
1840 : : DCACHE_OP_DELETE |
1841 : : DCACHE_OP_REAL));
1842 : 16175882 : dentry->d_op = op;
1843 [ + + ]: 16175882 : if (!op)
1844 : 16175882 : return;
1845 [ + + ]: 9274467 : if (op->d_hash)
1846 : 828 : dentry->d_flags |= DCACHE_OP_HASH;
1847 [ + + ]: 9274467 : if (op->d_compare)
1848 : 9936 : dentry->d_flags |= DCACHE_OP_COMPARE;
1849 [ + + ]: 9274467 : if (op->d_revalidate)
1850 : 3876232 : dentry->d_flags |= DCACHE_OP_REVALIDATE;
1851 [ - + ]: 9274467 : if (op->d_weak_revalidate)
1852 : 0 : dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE;
1853 [ + + ]: 9274467 : if (op->d_delete)
1854 : 6707737 : dentry->d_flags |= DCACHE_OP_DELETE;
1855 [ - + ]: 9274467 : if (op->d_prune)
1856 : 0 : dentry->d_flags |= DCACHE_OP_PRUNE;
1857 [ - + ]: 9274467 : if (op->d_real)
1858 : 0 : dentry->d_flags |= DCACHE_OP_REAL;
1859 : :
1860 : : }
1861 : : EXPORT_SYMBOL(d_set_d_op);
1862 : :
1863 : :
1864 : : /*
1865 : : * d_set_fallthru - Mark a dentry as falling through to a lower layer
1866 : : * @dentry - The dentry to mark
1867 : : *
1868 : : * Mark a dentry as falling through to the lower layer (as set with
1869 : : * d_pin_lower()). This flag may be recorded on the medium.
1870 : : */
1871 : 0 : void d_set_fallthru(struct dentry *dentry)
1872 : : {
1873 : : spin_lock(&dentry->d_lock);
1874 : 0 : dentry->d_flags |= DCACHE_FALLTHRU;
1875 : : spin_unlock(&dentry->d_lock);
1876 : 0 : }
1877 : : EXPORT_SYMBOL(d_set_fallthru);
1878 : :
1879 : 6305608 : static unsigned d_flags_for_inode(struct inode *inode)
1880 : : {
1881 : : unsigned add_flags = DCACHE_REGULAR_TYPE;
1882 : :
1883 [ + + ]: 6305608 : if (!inode)
1884 : : return DCACHE_MISS_TYPE;
1885 : :
1886 [ + + ]: 6305133 : if (S_ISDIR(inode->i_mode)) {
1887 : : add_flags = DCACHE_DIRECTORY_TYPE;
1888 [ + + ]: 1153227 : if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
1889 [ + + ]: 1145310 : if (unlikely(!inode->i_op->lookup))
1890 : : add_flags = DCACHE_AUTODIR_TYPE;
1891 : : else
1892 : 1143689 : inode->i_opflags |= IOP_LOOKUP;
1893 : : }
1894 : : goto type_determined;
1895 : : }
1896 : :
1897 [ + + ]: 5151906 : if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
1898 [ + + ]: 5037617 : if (unlikely(inode->i_op->get_link)) {
1899 : : add_flags = DCACHE_SYMLINK_TYPE;
1900 : : goto type_determined;
1901 : : }
1902 : 3180983 : inode->i_opflags |= IOP_NOFOLLOW;
1903 : : }
1904 : :
1905 [ + + ]: 3295272 : if (unlikely(!S_ISREG(inode->i_mode)))
1906 : : add_flags = DCACHE_SPECIAL_TYPE;
1907 : :
1908 : : type_determined:
1909 [ + + ]: 6305133 : if (unlikely(IS_AUTOMOUNT(inode)))
1910 : 207 : add_flags |= DCACHE_NEED_AUTOMOUNT;
1911 : 6305133 : return add_flags;
1912 : : }
1913 : :
1914 : 3233361 : static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1915 : : {
1916 : 3233361 : unsigned add_flags = d_flags_for_inode(inode);
1917 [ - + ]: 3233254 : WARN_ON(d_in_lookup(dentry));
1918 : :
1919 : : spin_lock(&dentry->d_lock);
1920 : : /*
1921 : : * Decrement negative dentry count if it was in the LRU list.
1922 : : */
1923 [ + + ]: 3233363 : if (dentry->d_flags & DCACHE_LRU_LIST)
1924 : 3782 : this_cpu_dec(nr_dentry_negative);
1925 : 3233364 : hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
1926 : : raw_write_seqcount_begin(&dentry->d_seq);
1927 : : __d_set_inode_and_type(dentry, inode, add_flags);
1928 : : raw_write_seqcount_end(&dentry->d_seq);
1929 : 3233024 : fsnotify_update_flags(dentry);
1930 : : spin_unlock(&dentry->d_lock);
1931 : 3233332 : }
1932 : :
1933 : : /**
1934 : : * d_instantiate - fill in inode information for a dentry
1935 : : * @entry: dentry to complete
1936 : : * @inode: inode to attach to this dentry
1937 : : *
1938 : : * Fill in inode information in the entry.
1939 : : *
1940 : : * This turns negative dentries into productive full members
1941 : : * of society.
1942 : : *
1943 : : * NOTE! This assumes that the inode count has been incremented
1944 : : * (or otherwise set) by the caller to indicate that it is now
1945 : : * in use by the dcache.
1946 : : */
1947 : :
1948 : 3118698 : void d_instantiate(struct dentry *entry, struct inode * inode)
1949 : : {
1950 [ - + ]: 3118698 : BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
1951 [ + + ]: 3118698 : if (inode) {
1952 : 3118697 : security_d_instantiate(entry, inode);
1953 : : spin_lock(&inode->i_lock);
1954 : 3118606 : __d_instantiate(entry, inode);
1955 : : spin_unlock(&inode->i_lock);
1956 : : }
1957 : 3118684 : }
1958 : : EXPORT_SYMBOL(d_instantiate);
1959 : :
1960 : : /*
1961 : : * This should be equivalent to d_instantiate() + unlock_new_inode(),
1962 : : * with lockdep-related part of unlock_new_inode() done before
1963 : : * anything else. Use that instead of open-coding d_instantiate()/
1964 : : * unlock_new_inode() combinations.
1965 : : */
1966 : 114657 : void d_instantiate_new(struct dentry *entry, struct inode *inode)
1967 : : {
1968 [ - + ]: 114657 : BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
1969 [ - + ]: 114657 : BUG_ON(!inode);
1970 : : lockdep_annotate_inode_mutex_key(inode);
1971 : 114657 : security_d_instantiate(entry, inode);
1972 : : spin_lock(&inode->i_lock);
1973 : 114657 : __d_instantiate(entry, inode);
1974 [ - + ]: 114657 : WARN_ON(!(inode->i_state & I_NEW));
1975 : 114657 : inode->i_state &= ~I_NEW & ~I_CREATING;
1976 : 114657 : smp_mb();
1977 : 114657 : wake_up_bit(&inode->i_state, __I_NEW);
1978 : : spin_unlock(&inode->i_lock);
1979 : 114657 : }
1980 : : EXPORT_SYMBOL(d_instantiate_new);
1981 : :
1982 : 8695 : struct dentry *d_make_root(struct inode *root_inode)
1983 : : {
1984 : : struct dentry *res = NULL;
1985 : :
1986 [ + - ]: 8695 : if (root_inode) {
1987 : 8695 : res = d_alloc_anon(root_inode->i_sb);
1988 [ + - ]: 8695 : if (res)
1989 : 8695 : d_instantiate(res, root_inode);
1990 : : else
1991 : 0 : iput(root_inode);
1992 : : }
1993 : 8695 : return res;
1994 : : }
1995 : : EXPORT_SYMBOL(d_make_root);
1996 : :
1997 : 0 : static struct dentry *__d_instantiate_anon(struct dentry *dentry,
1998 : : struct inode *inode,
1999 : : bool disconnected)
2000 : : {
2001 : : struct dentry *res;
2002 : : unsigned add_flags;
2003 : :
2004 : 0 : security_d_instantiate(dentry, inode);
2005 : : spin_lock(&inode->i_lock);
2006 : : res = __d_find_any_alias(inode);
2007 [ # # ]: 0 : if (res) {
2008 : : spin_unlock(&inode->i_lock);
2009 : 0 : dput(dentry);
2010 : : goto out_iput;
2011 : : }
2012 : :
2013 : : /* attach a disconnected dentry */
2014 : 0 : add_flags = d_flags_for_inode(inode);
2015 : :
2016 [ # # ]: 0 : if (disconnected)
2017 : 0 : add_flags |= DCACHE_DISCONNECTED;
2018 : :
2019 : : spin_lock(&dentry->d_lock);
2020 : : __d_set_inode_and_type(dentry, inode, add_flags);
2021 : 0 : hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
2022 [ # # ]: 0 : if (!disconnected) {
2023 : 0 : hlist_bl_lock(&dentry->d_sb->s_roots);
2024 : 0 : hlist_bl_add_head(&dentry->d_hash, &dentry->d_sb->s_roots);
2025 : 0 : hlist_bl_unlock(&dentry->d_sb->s_roots);
2026 : : }
2027 : : spin_unlock(&dentry->d_lock);
2028 : : spin_unlock(&inode->i_lock);
2029 : :
2030 : 0 : return dentry;
2031 : :
2032 : : out_iput:
2033 : 0 : iput(inode);
2034 : 0 : return res;
2035 : : }
2036 : :
2037 : 0 : struct dentry *d_instantiate_anon(struct dentry *dentry, struct inode *inode)
2038 : : {
2039 : 0 : return __d_instantiate_anon(dentry, inode, true);
2040 : : }
2041 : : EXPORT_SYMBOL(d_instantiate_anon);
2042 : :
2043 : 0 : static struct dentry *__d_obtain_alias(struct inode *inode, bool disconnected)
2044 : : {
2045 : : struct dentry *tmp;
2046 : : struct dentry *res;
2047 : :
2048 [ # # ]: 0 : if (!inode)
2049 : : return ERR_PTR(-ESTALE);
2050 [ # # ]: 0 : if (IS_ERR(inode))
2051 : : return ERR_CAST(inode);
2052 : :
2053 : 0 : res = d_find_any_alias(inode);
2054 [ # # ]: 0 : if (res)
2055 : : goto out_iput;
2056 : :
2057 : 0 : tmp = d_alloc_anon(inode->i_sb);
2058 [ # # ]: 0 : if (!tmp) {
2059 : : res = ERR_PTR(-ENOMEM);
2060 : : goto out_iput;
2061 : : }
2062 : :
2063 : 0 : return __d_instantiate_anon(tmp, inode, disconnected);
2064 : :
2065 : : out_iput:
2066 : 0 : iput(inode);
2067 : 0 : return res;
2068 : : }
2069 : :
2070 : : /**
2071 : : * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
2072 : : * @inode: inode to allocate the dentry for
2073 : : *
2074 : : * Obtain a dentry for an inode resulting from NFS filehandle conversion or
2075 : : * similar open by handle operations. The returned dentry may be anonymous,
2076 : : * or may have a full name (if the inode was already in the cache).
2077 : : *
2078 : : * When called on a directory inode, we must ensure that the inode only ever
2079 : : * has one dentry. If a dentry is found, that is returned instead of
2080 : : * allocating a new one.
2081 : : *
2082 : : * On successful return, the reference to the inode has been transferred
2083 : : * to the dentry. In case of an error the reference on the inode is released.
2084 : : * To make it easier to use in export operations a %NULL or IS_ERR inode may
2085 : : * be passed in and the error will be propagated to the return value,
2086 : : * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
2087 : : */
2088 : 0 : struct dentry *d_obtain_alias(struct inode *inode)
2089 : : {
2090 : 0 : return __d_obtain_alias(inode, true);
2091 : : }
2092 : : EXPORT_SYMBOL(d_obtain_alias);
2093 : :
2094 : : /**
2095 : : * d_obtain_root - find or allocate a dentry for a given inode
2096 : : * @inode: inode to allocate the dentry for
2097 : : *
2098 : : * Obtain an IS_ROOT dentry for the root of a filesystem.
2099 : : *
2100 : : * We must ensure that directory inodes only ever have one dentry. If a
2101 : : * dentry is found, that is returned instead of allocating a new one.
2102 : : *
2103 : : * On successful return, the reference to the inode has been transferred
2104 : : * to the dentry. In case of an error the reference on the inode is
2105 : : * released. A %NULL or IS_ERR inode may be passed in and will be the
2106 : : * error will be propagate to the return value, with a %NULL @inode
2107 : : * replaced by ERR_PTR(-ESTALE).
2108 : : */
2109 : 0 : struct dentry *d_obtain_root(struct inode *inode)
2110 : : {
2111 : 0 : return __d_obtain_alias(inode, false);
2112 : : }
2113 : : EXPORT_SYMBOL(d_obtain_root);
2114 : :
2115 : : /**
2116 : : * d_add_ci - lookup or allocate new dentry with case-exact name
2117 : : * @inode: the inode case-insensitive lookup has found
2118 : : * @dentry: the negative dentry that was passed to the parent's lookup func
2119 : : * @name: the case-exact name to be associated with the returned dentry
2120 : : *
2121 : : * This is to avoid filling the dcache with case-insensitive names to the
2122 : : * same inode, only the actual correct case is stored in the dcache for
2123 : : * case-insensitive filesystems.
2124 : : *
2125 : : * For a case-insensitive lookup match and if the the case-exact dentry
2126 : : * already exists in in the dcache, use it and return it.
2127 : : *
2128 : : * If no entry exists with the exact case name, allocate new dentry with
2129 : : * the exact case, and return the spliced entry.
2130 : : */
2131 : 0 : struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
2132 : : struct qstr *name)
2133 : : {
2134 : : struct dentry *found, *res;
2135 : :
2136 : : /*
2137 : : * First check if a dentry matching the name already exists,
2138 : : * if not go ahead and create it now.
2139 : : */
2140 : 0 : found = d_hash_and_lookup(dentry->d_parent, name);
2141 [ # # ]: 0 : if (found) {
2142 : 0 : iput(inode);
2143 : 0 : return found;
2144 : : }
2145 [ # # ]: 0 : if (d_in_lookup(dentry)) {
2146 : 0 : found = d_alloc_parallel(dentry->d_parent, name,
2147 : : dentry->d_wait);
2148 [ # # # # ]: 0 : if (IS_ERR(found) || !d_in_lookup(found)) {
2149 : 0 : iput(inode);
2150 : 0 : return found;
2151 : : }
2152 : : } else {
2153 : 0 : found = d_alloc(dentry->d_parent, name);
2154 [ # # ]: 0 : if (!found) {
2155 : 0 : iput(inode);
2156 : 0 : return ERR_PTR(-ENOMEM);
2157 : : }
2158 : : }
2159 : 0 : res = d_splice_alias(inode, found);
2160 [ # # ]: 0 : if (res) {
2161 : 0 : dput(found);
2162 : 0 : return res;
2163 : : }
2164 : : return found;
2165 : : }
2166 : : EXPORT_SYMBOL(d_add_ci);
2167 : :
2168 : :
2169 : 20358068 : static inline bool d_same_name(const struct dentry *dentry,
2170 : : const struct dentry *parent,
2171 : : const struct qstr *name)
2172 : : {
2173 [ + + ]: 20358068 : if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) {
2174 [ + + ]: 20337746 : if (dentry->d_name.len != name->len)
2175 : : return false;
2176 : 40670921 : return dentry_cmp(dentry, name->name, name->len) == 0;
2177 : : }
2178 : 40644 : return parent->d_op->d_compare(dentry,
2179 : 20322 : dentry->d_name.len, dentry->d_name.name,
2180 : : name) == 0;
2181 : : }
2182 : :
2183 : : /**
2184 : : * __d_lookup_rcu - search for a dentry (racy, store-free)
2185 : : * @parent: parent dentry
2186 : : * @name: qstr of name we wish to find
2187 : : * @seqp: returns d_seq value at the point where the dentry was found
2188 : : * Returns: dentry, or NULL
2189 : : *
2190 : : * __d_lookup_rcu is the dcache lookup function for rcu-walk name
2191 : : * resolution (store-free path walking) design described in
2192 : : * Documentation/filesystems/path-lookup.txt.
2193 : : *
2194 : : * This is not to be used outside core vfs.
2195 : : *
2196 : : * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
2197 : : * held, and rcu_read_lock held. The returned dentry must not be stored into
2198 : : * without taking d_lock and checking d_seq sequence count against @seq
2199 : : * returned here.
2200 : : *
2201 : : * A refcount may be taken on the found dentry with the d_rcu_to_refcount
2202 : : * function.
2203 : : *
2204 : : * Alternatively, __d_lookup_rcu may be called again to look up the child of
2205 : : * the returned dentry, so long as its parent's seqlock is checked after the
2206 : : * child is looked up. Thus, an interlocking stepping of sequence lock checks
2207 : : * is formed, giving integrity down the path walk.
2208 : : *
2209 : : * NOTE! The caller *has* to check the resulting dentry against the sequence
2210 : : * number we've returned before using any of the resulting dentry state!
2211 : : */
2212 : 69012203 : struct dentry *__d_lookup_rcu(const struct dentry *parent,
2213 : : const struct qstr *name,
2214 : : unsigned *seqp)
2215 : : {
2216 : 69012203 : u64 hashlen = name->hash_len;
2217 : 69012203 : const unsigned char *str = name->name;
2218 : 69012203 : struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen));
2219 : : struct hlist_bl_node *node;
2220 : : struct dentry *dentry;
2221 : :
2222 : : /*
2223 : : * Note: There is significant duplication with __d_lookup_rcu which is
2224 : : * required to prevent single threaded performance regressions
2225 : : * especially on architectures where smp_rmb (in seqcounts) are costly.
2226 : : * Keep the two functions in sync.
2227 : : */
2228 : :
2229 : : /*
2230 : : * The hash list is protected using RCU.
2231 : : *
2232 : : * Carefully use d_seq when comparing a candidate dentry, to avoid
2233 : : * races with d_move().
2234 : : *
2235 : : * It is possible that concurrent renames can mess up our list
2236 : : * walk here and result in missing our dentry, resulting in the
2237 : : * false-negative result. d_lookup() protects against concurrent
2238 : : * renames using rename_lock seqlock.
2239 : : *
2240 : : * See Documentation/filesystems/path-lookup.txt for more details.
2241 : : */
2242 [ + + ]: 73046532 : hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
2243 : : unsigned seq;
2244 : :
2245 : : seqretry:
2246 : : /*
2247 : : * The dentry sequence count protects us from concurrent
2248 : : * renames, and thus protects parent and name fields.
2249 : : *
2250 : : * The caller must perform a seqcount check in order
2251 : : * to do anything useful with the returned dentry.
2252 : : *
2253 : : * NOTE! We do a "raw" seqcount_begin here. That means that
2254 : : * we don't wait for the sequence count to stabilize if it
2255 : : * is in the middle of a sequence change. If we do the slow
2256 : : * dentry compare, we will do seqretries until it is stable,
2257 : : * and if we end up with a successful lookup, we actually
2258 : : * want to exit RCU lookup anyway.
2259 : : *
2260 : : * Note that raw_seqcount_begin still *does* smp_rmb(), so
2261 : : * we are still guaranteed NUL-termination of ->d_name.name.
2262 : : */
2263 : : seq = raw_seqcount_begin(&dentry->d_seq);
2264 [ + + ]: 59329066 : if (dentry->d_parent != parent)
2265 : 4028566 : continue;
2266 [ + + ]: 55300500 : if (d_unhashed(dentry))
2267 : 2 : continue;
2268 : :
2269 [ + + ]: 55300498 : if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
2270 : : int tlen;
2271 : : const char *tname;
2272 [ + + ]: 830 : if (dentry->d_name.hash != hashlen_hash(hashlen))
2273 : 2 : continue;
2274 : 828 : tlen = dentry->d_name.len;
2275 : 828 : tname = dentry->d_name.name;
2276 : : /* we want a consistent (name,len) pair */
2277 [ - + ]: 828 : if (read_seqcount_retry(&dentry->d_seq, seq)) {
2278 : 0 : cpu_relax();
2279 : 0 : goto seqretry;
2280 : : }
2281 [ - + ]: 828 : if (parent->d_op->d_compare(dentry,
2282 : : tlen, tname, name) != 0)
2283 : 0 : continue;
2284 : : } else {
2285 [ + + ]: 55299668 : if (dentry->d_name.hash_len != hashlen)
2286 : 5759 : continue;
2287 [ - + ]: 110610326 : if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0)
2288 : 0 : continue;
2289 : : }
2290 : 55375328 : *seqp = seq;
2291 : 55375328 : return dentry;
2292 : : }
2293 : : return NULL;
2294 : : }
2295 : :
2296 : : /**
2297 : : * d_lookup - search for a dentry
2298 : : * @parent: parent dentry
2299 : : * @name: qstr of name we wish to find
2300 : : * Returns: dentry, or NULL
2301 : : *
2302 : : * d_lookup searches the children of the parent dentry for the name in
2303 : : * question. If the dentry is found its reference count is incremented and the
2304 : : * dentry is returned. The caller must use dput to free the entry when it has
2305 : : * finished using it. %NULL is returned if the dentry does not exist.
2306 : : */
2307 : 6624568 : struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name)
2308 : : {
2309 : : struct dentry *dentry;
2310 : : unsigned seq;
2311 : :
2312 : : do {
2313 : : seq = read_seqbegin(&rename_lock);
2314 : 6626072 : dentry = __d_lookup(parent, name);
2315 [ + + ]: 6626817 : if (dentry)
2316 : : break;
2317 [ + + ]: 5601880 : } while (read_seqretry(&rename_lock, seq));
2318 : 6628031 : return dentry;
2319 : : }
2320 : : EXPORT_SYMBOL(d_lookup);
2321 : :
2322 : : /**
2323 : : * __d_lookup - search for a dentry (racy)
2324 : : * @parent: parent dentry
2325 : : * @name: qstr of name we wish to find
2326 : : * Returns: dentry, or NULL
2327 : : *
2328 : : * __d_lookup is like d_lookup, however it may (rarely) return a
2329 : : * false-negative result due to unrelated rename activity.
2330 : : *
2331 : : * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
2332 : : * however it must be used carefully, eg. with a following d_lookup in
2333 : : * the case of failure.
2334 : : *
2335 : : * __d_lookup callers must be commented.
2336 : : */
2337 : 28693699 : struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
2338 : : {
2339 : 28693699 : unsigned int hash = name->hash;
2340 : : struct hlist_bl_head *b = d_hash(hash);
2341 : : struct hlist_bl_node *node;
2342 : : struct dentry *found = NULL;
2343 : : struct dentry *dentry;
2344 : :
2345 : : /*
2346 : : * Note: There is significant duplication with __d_lookup_rcu which is
2347 : : * required to prevent single threaded performance regressions
2348 : : * especially on architectures where smp_rmb (in seqcounts) are costly.
2349 : : * Keep the two functions in sync.
2350 : : */
2351 : :
2352 : : /*
2353 : : * The hash list is protected using RCU.
2354 : : *
2355 : : * Take d_lock when comparing a candidate dentry, to avoid races
2356 : : * with d_move().
2357 : : *
2358 : : * It is possible that concurrent renames can mess up our list
2359 : : * walk here and result in missing our dentry, resulting in the
2360 : : * false-negative result. d_lookup() protects against concurrent
2361 : : * renames using rename_lock seqlock.
2362 : : *
2363 : : * See Documentation/filesystems/path-lookup.txt for more details.
2364 : : */
2365 : : rcu_read_lock();
2366 : :
2367 [ + + ]: 30154601 : hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
2368 : :
2369 [ + + ]: 21796844 : if (dentry->d_name.hash != hash)
2370 : 1474056 : continue;
2371 : :
2372 : : spin_lock(&dentry->d_lock);
2373 [ + + ]: 20324875 : if (dentry->d_parent != parent)
2374 : : goto next;
2375 [ + + ]: 20324915 : if (d_unhashed(dentry))
2376 : : goto next;
2377 : :
2378 [ + + ]: 20324788 : if (!d_same_name(dentry, parent, name))
2379 : : goto next;
2380 : :
2381 : 20323542 : dentry->d_lockref.count++;
2382 : 20323542 : found = dentry;
2383 : : spin_unlock(&dentry->d_lock);
2384 : : break;
2385 : : next:
2386 : : spin_unlock(&dentry->d_lock);
2387 : : }
2388 : : rcu_read_unlock();
2389 : :
2390 : 28698381 : return found;
2391 : : }
2392 : :
2393 : : /**
2394 : : * d_hash_and_lookup - hash the qstr then search for a dentry
2395 : : * @dir: Directory to search in
2396 : : * @name: qstr of name we wish to find
2397 : : *
2398 : : * On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
2399 : : */
2400 : 1284699 : struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
2401 : : {
2402 : : /*
2403 : : * Check for a fs-specific hash function. Note that we must
2404 : : * calculate the standard hash first, as the d_op->d_hash()
2405 : : * routine may choose to leave the hash value unchanged.
2406 : : */
2407 : 1284699 : name->hash = full_name_hash(dir, name->name, name->len);
2408 [ - + ]: 1284588 : if (dir->d_flags & DCACHE_OP_HASH) {
2409 : 0 : int err = dir->d_op->d_hash(dir, name);
2410 [ # # ]: 0 : if (unlikely(err < 0))
2411 : 0 : return ERR_PTR(err);
2412 : : }
2413 : 1284588 : return d_lookup(dir, name);
2414 : : }
2415 : : EXPORT_SYMBOL(d_hash_and_lookup);
2416 : :
2417 : : /*
2418 : : * When a file is deleted, we have two options:
2419 : : * - turn this dentry into a negative dentry
2420 : : * - unhash this dentry and free it.
2421 : : *
2422 : : * Usually, we want to just turn this into
2423 : : * a negative dentry, but if anybody else is
2424 : : * currently using the dentry or the inode
2425 : : * we can't do that and we fall back on removing
2426 : : * it from the hash queues and waiting for
2427 : : * it to be deleted later when it has no users
2428 : : */
2429 : :
2430 : : /**
2431 : : * d_delete - delete a dentry
2432 : : * @dentry: The dentry to delete
2433 : : *
2434 : : * Turn the dentry into a negative dentry if possible, otherwise
2435 : : * remove it from the hash queues so it can be deleted later
2436 : : */
2437 : :
2438 : 44993 : void d_delete(struct dentry * dentry)
2439 : : {
2440 : 44993 : struct inode *inode = dentry->d_inode;
2441 : :
2442 : : spin_lock(&inode->i_lock);
2443 : : spin_lock(&dentry->d_lock);
2444 : : /*
2445 : : * Are we the only user?
2446 : : */
2447 [ + + ]: 44993 : if (dentry->d_lockref.count == 1) {
2448 : 44773 : dentry->d_flags &= ~DCACHE_CANT_MOUNT;
2449 : 44773 : dentry_unlink_inode(dentry);
2450 : : } else {
2451 : 220 : __d_drop(dentry);
2452 : : spin_unlock(&dentry->d_lock);
2453 : : spin_unlock(&inode->i_lock);
2454 : : }
2455 : 44993 : }
2456 : : EXPORT_SYMBOL(d_delete);
2457 : :
2458 : 8853012 : static void __d_rehash(struct dentry *entry)
2459 : : {
2460 : 8853012 : struct hlist_bl_head *b = d_hash(entry->d_name.hash);
2461 : :
2462 : : hlist_bl_lock(b);
2463 : 8855199 : hlist_bl_add_head_rcu(&entry->d_hash, b);
2464 : : hlist_bl_unlock(b);
2465 : 8855872 : }
2466 : :
2467 : : /**
2468 : : * d_rehash - add an entry back to the hash
2469 : : * @entry: dentry to add to the hash
2470 : : *
2471 : : * Adds a dentry to the hash according to its name.
2472 : : */
2473 : :
2474 : 0 : void d_rehash(struct dentry * entry)
2475 : : {
2476 : : spin_lock(&entry->d_lock);
2477 : 0 : __d_rehash(entry);
2478 : : spin_unlock(&entry->d_lock);
2479 : 0 : }
2480 : : EXPORT_SYMBOL(d_rehash);
2481 : :
2482 : 8446696 : static inline unsigned start_dir_add(struct inode *dir)
2483 : : {
2484 : :
2485 : : for (;;) {
2486 : 14648723 : unsigned n = dir->i_dir_seq;
2487 [ + + + + ]: 14648723 : if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
2488 : 8445556 : return n;
2489 : 6205061 : cpu_relax();
2490 : 6202027 : }
2491 : : }
2492 : :
2493 : : static inline void end_dir_add(struct inode *dir, unsigned n)
2494 : : {
2495 : 8447196 : smp_store_release(&dir->i_dir_seq, n + 2);
2496 : : }
2497 : :
2498 : 22732 : static void d_wait_lookup(struct dentry *dentry)
2499 : : {
2500 [ + + ]: 22732 : if (d_in_lookup(dentry)) {
2501 : 32560 : DECLARE_WAITQUEUE(wait, current);
2502 : 16280 : add_wait_queue(dentry->d_wait, &wait);
2503 : : do {
2504 : 48840 : set_current_state(TASK_UNINTERRUPTIBLE);
2505 : : spin_unlock(&dentry->d_lock);
2506 : 16280 : schedule();
2507 : : spin_lock(&dentry->d_lock);
2508 [ - + ]: 16279 : } while (d_in_lookup(dentry));
2509 : : }
2510 : 22731 : }
2511 : :
2512 : 9909447 : struct dentry *d_alloc_parallel(struct dentry *parent,
2513 : : const struct qstr *name,
2514 : : wait_queue_head_t *wq)
2515 : : {
2516 : 9909447 : unsigned int hash = name->hash;
2517 : : struct hlist_bl_head *b = in_lookup_hash(parent, hash);
2518 : : struct hlist_bl_node *node;
2519 : 9909447 : struct dentry *new = d_alloc(parent, name);
2520 : : struct dentry *dentry;
2521 : : unsigned seq, r_seq, d_seq;
2522 : :
2523 [ + + ]: 9914373 : if (unlikely(!new))
2524 : : return ERR_PTR(-ENOMEM);
2525 : :
2526 : : retry:
2527 : : rcu_read_lock();
2528 : 20231308 : seq = smp_load_acquire(&parent->d_inode->i_dir_seq);
2529 : : r_seq = read_seqbegin(&rename_lock);
2530 : 10119714 : dentry = __d_lookup_rcu(parent, name, &d_seq);
2531 [ + + ]: 10117260 : if (unlikely(dentry)) {
2532 [ + + ]: 4584 : if (!lockref_get_not_dead(&dentry->d_lockref)) {
2533 : : rcu_read_unlock();
2534 : : goto retry;
2535 : : }
2536 [ - + ]: 8720 : if (read_seqcount_retry(&dentry->d_seq, d_seq)) {
2537 : : rcu_read_unlock();
2538 : 0 : dput(dentry);
2539 : 0 : goto retry;
2540 : : }
2541 : : rcu_read_unlock();
2542 : 4360 : dput(new);
2543 : 4361 : return dentry;
2544 : : }
2545 [ + + ]: 10112679 : if (unlikely(read_seqretry(&rename_lock, r_seq))) {
2546 : : rcu_read_unlock();
2547 : : goto retry;
2548 : : }
2549 : :
2550 [ + + ]: 10112617 : if (unlikely(seq & 1)) {
2551 : : rcu_read_unlock();
2552 : : goto retry;
2553 : : }
2554 : :
2555 : : hlist_bl_lock(b);
2556 [ + + ]: 19846230 : if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) {
2557 : : hlist_bl_unlock(b);
2558 : : rcu_read_unlock();
2559 : : goto retry;
2560 : : }
2561 : : /*
2562 : : * No changes for the parent since the beginning of d_lookup().
2563 : : * Since all removals from the chain happen with hlist_bl_lock(),
2564 : : * any potential in-lookup matches are going to stay here until
2565 : : * we unlock the chain. All fields are stable in everything
2566 : : * we encounter.
2567 : : */
2568 [ + + ]: 9923529 : hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) {
2569 [ + + ]: 23760 : if (dentry->d_name.hash != hash)
2570 : 1028 : continue;
2571 [ - + ]: 22732 : if (dentry->d_parent != parent)
2572 : 0 : continue;
2573 [ - + ]: 22732 : if (!d_same_name(dentry, parent, name))
2574 : 0 : continue;
2575 : : hlist_bl_unlock(b);
2576 : : /* now we can try to grab a reference */
2577 [ - + ]: 22732 : if (!lockref_get_not_dead(&dentry->d_lockref)) {
2578 : : rcu_read_unlock();
2579 : : goto retry;
2580 : : }
2581 : :
2582 : : rcu_read_unlock();
2583 : : /*
2584 : : * somebody is likely to be still doing lookup for it;
2585 : : * wait for them to finish
2586 : : */
2587 : : spin_lock(&dentry->d_lock);
2588 : 22731 : d_wait_lookup(dentry);
2589 : : /*
2590 : : * it's not in-lookup anymore; in principle we should repeat
2591 : : * everything from dcache lookup, but it's likely to be what
2592 : : * d_lookup() would've found anyway. If it is, just return it;
2593 : : * otherwise we really have to repeat the whole thing.
2594 : : */
2595 [ + - ]: 22730 : if (unlikely(dentry->d_name.hash != hash))
2596 : : goto mismatch;
2597 [ + + ]: 22732 : if (unlikely(dentry->d_parent != parent))
2598 : : goto mismatch;
2599 [ + + ]: 22731 : if (unlikely(d_unhashed(dentry)))
2600 : : goto mismatch;
2601 [ + - ]: 10444 : if (unlikely(!d_same_name(dentry, parent, name)))
2602 : : goto mismatch;
2603 : : /* OK, it *is* a hashed match; return it */
2604 : : spin_unlock(&dentry->d_lock);
2605 : 10444 : dput(new);
2606 : 10443 : return dentry;
2607 : : }
2608 : : rcu_read_unlock();
2609 : : /* we can't take ->d_lock here; it's OK, though. */
2610 : 9898263 : new->d_flags |= DCACHE_PAR_LOOKUP;
2611 : 9898263 : new->d_wait = wq;
2612 : 9898263 : hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b);
2613 : : hlist_bl_unlock(b);
2614 : 9899260 : return new;
2615 : : mismatch:
2616 : : spin_unlock(&dentry->d_lock);
2617 : 12286 : dput(dentry);
2618 : 12287 : goto retry;
2619 : : }
2620 : : EXPORT_SYMBOL(d_alloc_parallel);
2621 : :
2622 : 9899537 : void __d_lookup_done(struct dentry *dentry)
2623 : : {
2624 : 9899537 : struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent,
2625 : : dentry->d_name.hash);
2626 : : hlist_bl_lock(b);
2627 : 9900064 : dentry->d_flags &= ~DCACHE_PAR_LOOKUP;
2628 : : __hlist_bl_del(&dentry->d_u.d_in_lookup_hash);
2629 : 9900064 : wake_up_all(dentry->d_wait);
2630 : 9900568 : dentry->d_wait = NULL;
2631 : : hlist_bl_unlock(b);
2632 : : INIT_HLIST_NODE(&dentry->d_u.d_alias);
2633 : 9899177 : INIT_LIST_HEAD(&dentry->d_lru);
2634 : 9899177 : }
2635 : : EXPORT_SYMBOL(__d_lookup_done);
2636 : :
2637 : : /* inode->i_lock held if inode is non-NULL */
2638 : :
2639 : 8776153 : static inline void __d_add(struct dentry *dentry, struct inode *inode)
2640 : : {
2641 : : struct inode *dir = NULL;
2642 : : unsigned n;
2643 : : spin_lock(&dentry->d_lock);
2644 [ + + ]: 8779216 : if (unlikely(d_in_lookup(dentry))) {
2645 : 8439919 : dir = dentry->d_parent->d_inode;
2646 : 8439919 : n = start_dir_add(dir);
2647 : 8446524 : __d_lookup_done(dentry);
2648 : : }
2649 [ + + ]: 8778876 : if (inode) {
2650 : 3071928 : unsigned add_flags = d_flags_for_inode(inode);
2651 : 3071559 : hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
2652 : : raw_write_seqcount_begin(&dentry->d_seq);
2653 : : __d_set_inode_and_type(dentry, inode, add_flags);
2654 : : raw_write_seqcount_end(&dentry->d_seq);
2655 : 3069572 : fsnotify_update_flags(dentry);
2656 : : }
2657 : 8776644 : __d_rehash(dentry);
2658 [ + + ]: 8778494 : if (dir)
2659 : : end_dir_add(dir, n);
2660 : : spin_unlock(&dentry->d_lock);
2661 [ + + ]: 8778157 : if (inode)
2662 : : spin_unlock(&inode->i_lock);
2663 : 8777988 : }
2664 : :
2665 : : /**
2666 : : * d_add - add dentry to hash queues
2667 : : * @entry: dentry to add
2668 : : * @inode: The inode to attach to this dentry
2669 : : *
2670 : : * This adds the entry to the hash queues and initializes @inode.
2671 : : * The entry was actually filled in earlier during d_alloc().
2672 : : */
2673 : :
2674 : 5015400 : void d_add(struct dentry *entry, struct inode *inode)
2675 : : {
2676 [ + + ]: 5015400 : if (inode) {
2677 : 4342 : security_d_instantiate(entry, inode);
2678 : : spin_lock(&inode->i_lock);
2679 : : }
2680 : 5015400 : __d_add(entry, inode);
2681 : 5016562 : }
2682 : : EXPORT_SYMBOL(d_add);
2683 : :
2684 : : /**
2685 : : * d_exact_alias - find and hash an exact unhashed alias
2686 : : * @entry: dentry to add
2687 : : * @inode: The inode to go with this dentry
2688 : : *
2689 : : * If an unhashed dentry with the same name/parent and desired
2690 : : * inode already exists, hash and return it. Otherwise, return
2691 : : * NULL.
2692 : : *
2693 : : * Parent directory should be locked.
2694 : : */
2695 : 0 : struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode)
2696 : : {
2697 : : struct dentry *alias;
2698 : 0 : unsigned int hash = entry->d_name.hash;
2699 : :
2700 : : spin_lock(&inode->i_lock);
2701 [ # # # # : 0 : hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
# # ]
2702 : : /*
2703 : : * Don't need alias->d_lock here, because aliases with
2704 : : * d_parent == entry->d_parent are not subject to name or
2705 : : * parent changes, because the parent inode i_mutex is held.
2706 : : */
2707 [ # # ]: 0 : if (alias->d_name.hash != hash)
2708 : 0 : continue;
2709 [ # # ]: 0 : if (alias->d_parent != entry->d_parent)
2710 : 0 : continue;
2711 [ # # ]: 0 : if (!d_same_name(alias, entry->d_parent, &entry->d_name))
2712 : 0 : continue;
2713 : : spin_lock(&alias->d_lock);
2714 [ # # ]: 0 : if (!d_unhashed(alias)) {
2715 : : spin_unlock(&alias->d_lock);
2716 : : alias = NULL;
2717 : : } else {
2718 : : __dget_dlock(alias);
2719 : 0 : __d_rehash(alias);
2720 : : spin_unlock(&alias->d_lock);
2721 : : }
2722 : : spin_unlock(&inode->i_lock);
2723 : 0 : return alias;
2724 : : }
2725 : : spin_unlock(&inode->i_lock);
2726 : 0 : return NULL;
2727 : : }
2728 : : EXPORT_SYMBOL(d_exact_alias);
2729 : :
2730 : 0 : static void swap_names(struct dentry *dentry, struct dentry *target)
2731 : : {
2732 [ # # ]: 0 : if (unlikely(dname_external(target))) {
2733 [ # # ]: 0 : if (unlikely(dname_external(dentry))) {
2734 : : /*
2735 : : * Both external: swap the pointers
2736 : : */
2737 : 0 : swap(target->d_name.name, dentry->d_name.name);
2738 : : } else {
2739 : : /*
2740 : : * dentry:internal, target:external. Steal target's
2741 : : * storage and make target internal.
2742 : : */
2743 : 0 : memcpy(target->d_iname, dentry->d_name.name,
2744 : 0 : dentry->d_name.len + 1);
2745 : 0 : dentry->d_name.name = target->d_name.name;
2746 : 0 : target->d_name.name = target->d_iname;
2747 : : }
2748 : : } else {
2749 [ # # ]: 0 : if (unlikely(dname_external(dentry))) {
2750 : : /*
2751 : : * dentry:external, target:internal. Give dentry's
2752 : : * storage to target and make dentry internal
2753 : : */
2754 : 0 : memcpy(dentry->d_iname, target->d_name.name,
2755 : 0 : target->d_name.len + 1);
2756 : 0 : target->d_name.name = dentry->d_name.name;
2757 : 0 : dentry->d_name.name = dentry->d_iname;
2758 : : } else {
2759 : : /*
2760 : : * Both are internal.
2761 : : */
2762 : : unsigned int i;
2763 : : BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
2764 [ # # ]: 0 : for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
2765 : 0 : swap(((long *) &dentry->d_iname)[i],
2766 : : ((long *) &target->d_iname)[i]);
2767 : : }
2768 : : }
2769 : : }
2770 : 0 : swap(dentry->d_name.hash_len, target->d_name.hash_len);
2771 : 0 : }
2772 : :
2773 : 77011 : static void copy_name(struct dentry *dentry, struct dentry *target)
2774 : : {
2775 : : struct external_name *old_name = NULL;
2776 [ + + ]: 77011 : if (unlikely(dname_external(dentry)))
2777 : : old_name = external_name(dentry);
2778 [ + + ]: 77011 : if (unlikely(dname_external(target))) {
2779 : 3976 : atomic_inc(&external_name(target)->u.count);
2780 : 3976 : dentry->d_name = target->d_name;
2781 : : } else {
2782 : 73035 : memcpy(dentry->d_iname, target->d_name.name,
2783 : 73035 : target->d_name.len + 1);
2784 : 73035 : dentry->d_name.name = dentry->d_iname;
2785 : 73035 : dentry->d_name.hash_len = target->d_name.hash_len;
2786 : : }
2787 [ + + - + ]: 89643 : if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
2788 [ # # ]: 0 : kfree_rcu(old_name, u.head);
2789 : 77011 : }
2790 : :
2791 : : /*
2792 : : * __d_move - move a dentry
2793 : : * @dentry: entry to move
2794 : : * @target: new dentry
2795 : : * @exchange: exchange the two dentries
2796 : : *
2797 : : * Update the dcache to reflect the move of a file name. Negative
2798 : : * dcache entries should not be moved in this way. Caller must hold
2799 : : * rename_lock, the i_mutex of the source and target directories,
2800 : : * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
2801 : : */
2802 : 77011 : static void __d_move(struct dentry *dentry, struct dentry *target,
2803 : : bool exchange)
2804 : : {
2805 : : struct dentry *old_parent, *p;
2806 : : struct inode *dir = NULL;
2807 : : unsigned n;
2808 : :
2809 [ - + ]: 77011 : WARN_ON(!dentry->d_inode);
2810 [ - + + - ]: 77011 : if (WARN_ON(dentry == target))
2811 : 77011 : return;
2812 : :
2813 [ - + ]: 77011 : BUG_ON(d_ancestor(target, dentry));
2814 : 77011 : old_parent = dentry->d_parent;
2815 : : p = d_ancestor(old_parent, target);
2816 [ - + ]: 77011 : if (IS_ROOT(dentry)) {
2817 [ # # ]: 0 : BUG_ON(p);
2818 : 0 : spin_lock(&target->d_parent->d_lock);
2819 [ - + ]: 77011 : } else if (!p) {
2820 : : /* target is not a descendent of dentry->d_parent */
2821 : 0 : spin_lock(&target->d_parent->d_lock);
2822 : 0 : spin_lock_nested(&old_parent->d_lock, DENTRY_D_LOCK_NESTED);
2823 : : } else {
2824 [ - + ]: 77011 : BUG_ON(p == dentry);
2825 : : spin_lock(&old_parent->d_lock);
2826 [ - + ]: 77011 : if (p != target)
2827 : 0 : spin_lock_nested(&target->d_parent->d_lock,
2828 : : DENTRY_D_LOCK_NESTED);
2829 : : }
2830 : 77011 : spin_lock_nested(&dentry->d_lock, 2);
2831 : 77011 : spin_lock_nested(&target->d_lock, 3);
2832 : :
2833 [ - + ]: 77011 : if (unlikely(d_in_lookup(target))) {
2834 : 0 : dir = target->d_parent->d_inode;
2835 : 0 : n = start_dir_add(dir);
2836 : 0 : __d_lookup_done(target);
2837 : : }
2838 : :
2839 : : write_seqcount_begin(&dentry->d_seq);
2840 : : write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
2841 : :
2842 : : /* unhash both */
2843 [ + - ]: 77011 : if (!d_unhashed(dentry))
2844 : 77011 : ___d_drop(dentry);
2845 [ + - ]: 77011 : if (!d_unhashed(target))
2846 : 77011 : ___d_drop(target);
2847 : :
2848 : : /* ... and switch them in the tree */
2849 : 77011 : dentry->d_parent = target->d_parent;
2850 [ + - ]: 77011 : if (!exchange) {
2851 : 77011 : copy_name(dentry, target);
2852 : 77011 : target->d_hash.pprev = NULL;
2853 : 77011 : dentry->d_parent->d_lockref.count++;
2854 [ + - ]: 77011 : if (dentry != old_parent) /* wasn't IS_ROOT */
2855 [ - + ]: 77011 : WARN_ON(!--old_parent->d_lockref.count);
2856 : : } else {
2857 : 0 : target->d_parent = old_parent;
2858 : 0 : swap_names(dentry, target);
2859 : 0 : list_move(&target->d_child, &target->d_parent->d_subdirs);
2860 : 0 : __d_rehash(target);
2861 : 0 : fsnotify_update_flags(target);
2862 : : }
2863 : 77011 : list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
2864 : 77011 : __d_rehash(dentry);
2865 : 77011 : fsnotify_update_flags(dentry);
2866 : : fscrypt_handle_d_move(dentry);
2867 : :
2868 : : write_seqcount_end(&target->d_seq);
2869 : : write_seqcount_end(&dentry->d_seq);
2870 : :
2871 [ - + ]: 77011 : if (dir)
2872 : : end_dir_add(dir, n);
2873 : :
2874 [ - + ]: 77011 : if (dentry->d_parent != old_parent)
2875 : : spin_unlock(&dentry->d_parent->d_lock);
2876 [ + - ]: 77011 : if (dentry != old_parent)
2877 : : spin_unlock(&old_parent->d_lock);
2878 : : spin_unlock(&target->d_lock);
2879 : : spin_unlock(&dentry->d_lock);
2880 : : }
2881 : :
2882 : : /*
2883 : : * d_move - move a dentry
2884 : : * @dentry: entry to move
2885 : : * @target: new dentry
2886 : : *
2887 : : * Update the dcache to reflect the move of a file name. Negative
2888 : : * dcache entries should not be moved in this way. See the locking
2889 : : * requirements for __d_move.
2890 : : */
2891 : 77011 : void d_move(struct dentry *dentry, struct dentry *target)
2892 : : {
2893 : : write_seqlock(&rename_lock);
2894 : 77011 : __d_move(dentry, target, false);
2895 : : write_sequnlock(&rename_lock);
2896 : 77011 : }
2897 : : EXPORT_SYMBOL(d_move);
2898 : :
2899 : : /*
2900 : : * d_exchange - exchange two dentries
2901 : : * @dentry1: first dentry
2902 : : * @dentry2: second dentry
2903 : : */
2904 : 0 : void d_exchange(struct dentry *dentry1, struct dentry *dentry2)
2905 : : {
2906 : : write_seqlock(&rename_lock);
2907 : :
2908 [ # # ]: 0 : WARN_ON(!dentry1->d_inode);
2909 [ # # ]: 0 : WARN_ON(!dentry2->d_inode);
2910 [ # # ]: 0 : WARN_ON(IS_ROOT(dentry1));
2911 [ # # ]: 0 : WARN_ON(IS_ROOT(dentry2));
2912 : :
2913 : 0 : __d_move(dentry1, dentry2, true);
2914 : :
2915 : : write_sequnlock(&rename_lock);
2916 : 0 : }
2917 : :
2918 : : /**
2919 : : * d_ancestor - search for an ancestor
2920 : : * @p1: ancestor dentry
2921 : : * @p2: child dentry
2922 : : *
2923 : : * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2924 : : * an ancestor of p2, else NULL.
2925 : : */
2926 : 0 : struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
2927 : : {
2928 : : struct dentry *p;
2929 : :
2930 [ + + # # : 445009 : for (p = p2; !IS_ROOT(p); p = p->d_parent) {
# # + + +
- ]
2931 [ + + # # : 352374 : if (p->d_parent == p1)
# # - + +
- ]
2932 : 82405 : return p;
2933 : : }
2934 : : return NULL;
2935 : : }
2936 : :
2937 : : /*
2938 : : * This helper attempts to cope with remotely renamed directories
2939 : : *
2940 : : * It assumes that the caller is already holding
2941 : : * dentry->d_parent->d_inode->i_mutex, and rename_lock
2942 : : *
2943 : : * Note: If ever the locking in lock_rename() changes, then please
2944 : : * remember to update this too...
2945 : : */
2946 : 0 : static int __d_unalias(struct inode *inode,
2947 : : struct dentry *dentry, struct dentry *alias)
2948 : : {
2949 : : struct mutex *m1 = NULL;
2950 : : struct rw_semaphore *m2 = NULL;
2951 : : int ret = -ESTALE;
2952 : :
2953 : : /* If alias and dentry share a parent, then no extra locks required */
2954 [ # # ]: 0 : if (alias->d_parent == dentry->d_parent)
2955 : : goto out_unalias;
2956 : :
2957 : : /* See lock_rename() */
2958 [ # # ]: 0 : if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2959 : : goto out_err;
2960 : 0 : m1 = &dentry->d_sb->s_vfs_rename_mutex;
2961 [ # # ]: 0 : if (!inode_trylock_shared(alias->d_parent->d_inode))
2962 : : goto out_err;
2963 : 0 : m2 = &alias->d_parent->d_inode->i_rwsem;
2964 : : out_unalias:
2965 : 0 : __d_move(alias, dentry, false);
2966 : : ret = 0;
2967 : : out_err:
2968 [ # # ]: 0 : if (m2)
2969 : 0 : up_read(m2);
2970 [ # # ]: 0 : if (m1)
2971 : 0 : mutex_unlock(m1);
2972 : 0 : return ret;
2973 : : }
2974 : :
2975 : : /**
2976 : : * d_splice_alias - splice a disconnected dentry into the tree if one exists
2977 : : * @inode: the inode which may have a disconnected dentry
2978 : : * @dentry: a negative dentry which we want to point to the inode.
2979 : : *
2980 : : * If inode is a directory and has an IS_ROOT alias, then d_move that in
2981 : : * place of the given dentry and return it, else simply d_add the inode
2982 : : * to the dentry and return NULL.
2983 : : *
2984 : : * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
2985 : : * we should error out: directories can't have multiple aliases.
2986 : : *
2987 : : * This is needed in the lookup routine of any filesystem that is exportable
2988 : : * (via knfsd) so that we can build dcache paths to directories effectively.
2989 : : *
2990 : : * If a dentry was found and moved, then it is returned. Otherwise NULL
2991 : : * is returned. This matches the expected return value of ->lookup.
2992 : : *
2993 : : * Cluster filesystems may call this function with a negative, hashed dentry.
2994 : : * In that case, we know that the inode will be a regular file, and also this
2995 : : * will only occur during atomic_open. So we need to check for the dentry
2996 : : * being already hashed only in the final case.
2997 : : */
2998 : 3762579 : struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
2999 : : {
3000 [ + + ]: 3762579 : if (IS_ERR(inode))
3001 : : return ERR_CAST(inode);
3002 : :
3003 [ - + ]: 3762382 : BUG_ON(!d_unhashed(dentry));
3004 : :
3005 [ + + ]: 3762382 : if (!inode)
3006 : : goto out;
3007 : :
3008 : 3067072 : security_d_instantiate(dentry, inode);
3009 : : spin_lock(&inode->i_lock);
3010 [ + + ]: 3067834 : if (S_ISDIR(inode->i_mode)) {
3011 : : struct dentry *new = __d_find_any_alias(inode);
3012 [ - + ]: 745336 : if (unlikely(new)) {
3013 : : /* The reference to new ensures it remains an alias */
3014 : : spin_unlock(&inode->i_lock);
3015 : : write_seqlock(&rename_lock);
3016 [ # # ]: 0 : if (unlikely(d_ancestor(new, dentry))) {
3017 : : write_sequnlock(&rename_lock);
3018 : 0 : dput(new);
3019 : : new = ERR_PTR(-ELOOP);
3020 [ # # ]: 0 : pr_warn_ratelimited(
3021 : : "VFS: Lookup of '%s' in %s %s"
3022 : : " would have caused loop\n",
3023 : : dentry->d_name.name,
3024 : : inode->i_sb->s_type->name,
3025 : : inode->i_sb->s_id);
3026 [ # # ]: 0 : } else if (!IS_ROOT(new)) {
3027 : : struct dentry *old_parent = dget(new->d_parent);
3028 : 0 : int err = __d_unalias(inode, dentry, new);
3029 : : write_sequnlock(&rename_lock);
3030 [ # # ]: 0 : if (err) {
3031 : 0 : dput(new);
3032 : : new = ERR_PTR(err);
3033 : : }
3034 : 0 : dput(old_parent);
3035 : : } else {
3036 : 0 : __d_move(new, dentry, false);
3037 : : write_sequnlock(&rename_lock);
3038 : : }
3039 : 0 : iput(inode);
3040 : 0 : return new;
3041 : : }
3042 : : }
3043 : : out:
3044 : 3763463 : __d_add(dentry, inode);
3045 : 3762421 : return NULL;
3046 : : }
3047 : : EXPORT_SYMBOL(d_splice_alias);
3048 : :
3049 : : /*
3050 : : * Test whether new_dentry is a subdirectory of old_dentry.
3051 : : *
3052 : : * Trivially implemented using the dcache structure
3053 : : */
3054 : :
3055 : : /**
3056 : : * is_subdir - is new dentry a subdirectory of old_dentry
3057 : : * @new_dentry: new dentry
3058 : : * @old_dentry: old dentry
3059 : : *
3060 : : * Returns true if new_dentry is a subdirectory of the parent (at any depth).
3061 : : * Returns false otherwise.
3062 : : * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
3063 : : */
3064 : :
3065 : 21434 : bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
3066 : : {
3067 : : bool result;
3068 : : unsigned seq;
3069 : :
3070 [ + + ]: 21434 : if (new_dentry == old_dentry)
3071 : : return true;
3072 : :
3073 : : do {
3074 : : /* for restarting inner loop in case of seq retry */
3075 : : seq = read_seqbegin(&rename_lock);
3076 : : /*
3077 : : * Need rcu_readlock to protect against the d_parent trashing
3078 : : * due to d_move
3079 : : */
3080 : : rcu_read_lock();
3081 [ + + ]: 21018 : if (d_ancestor(old_dentry, new_dentry))
3082 : : result = true;
3083 : : else
3084 : : result = false;
3085 : : rcu_read_unlock();
3086 [ - + ]: 21018 : } while (read_seqretry(&rename_lock, seq));
3087 : :
3088 : 21018 : return result;
3089 : : }
3090 : : EXPORT_SYMBOL(is_subdir);
3091 : :
3092 : 50 : static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
3093 : : {
3094 : : struct dentry *root = data;
3095 [ + + ]: 50 : if (dentry != root) {
3096 [ + - + - ]: 48 : if (d_unhashed(dentry) || !dentry->d_inode)
3097 : : return D_WALK_SKIP;
3098 : :
3099 [ + - ]: 48 : if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
3100 : 48 : dentry->d_flags |= DCACHE_GENOCIDE;
3101 : 48 : dentry->d_lockref.count--;
3102 : : }
3103 : : }
3104 : : return D_WALK_CONTINUE;
3105 : : }
3106 : :
3107 : 2 : void d_genocide(struct dentry *parent)
3108 : : {
3109 : 2 : d_walk(parent, parent, d_genocide_kill);
3110 : 2 : }
3111 : :
3112 : : EXPORT_SYMBOL(d_genocide);
3113 : :
3114 : 213 : void d_tmpfile(struct dentry *dentry, struct inode *inode)
3115 : : {
3116 : : inode_dec_link_count(inode);
3117 [ + - + - : 639 : BUG_ON(dentry->d_name.name != dentry->d_iname ||
+ - - + ]
3118 : : !hlist_unhashed(&dentry->d_u.d_alias) ||
3119 : : !d_unlinked(dentry));
3120 : 213 : spin_lock(&dentry->d_parent->d_lock);
3121 : 213 : spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
3122 : 213 : dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
3123 : 213 : (unsigned long long)inode->i_ino);
3124 : : spin_unlock(&dentry->d_lock);
3125 : 213 : spin_unlock(&dentry->d_parent->d_lock);
3126 : 213 : d_instantiate(dentry, inode);
3127 : 213 : }
3128 : : EXPORT_SYMBOL(d_tmpfile);
3129 : :
3130 : : static __initdata unsigned long dhash_entries;
3131 : 0 : static int __init set_dhash_entries(char *str)
3132 : : {
3133 [ # # ]: 0 : if (!str)
3134 : : return 0;
3135 : 0 : dhash_entries = simple_strtoul(str, &str, 0);
3136 : 0 : return 1;
3137 : : }
3138 : : __setup("dhash_entries=", set_dhash_entries);
3139 : :
3140 : 207 : static void __init dcache_init_early(void)
3141 : : {
3142 : : /* If hashes are distributed across NUMA nodes, defer
3143 : : * hash allocation until vmalloc space is available.
3144 : : */
3145 : : if (hashdist)
3146 : 207 : return;
3147 : :
3148 : 207 : dentry_hashtable =
3149 : 207 : alloc_large_system_hash("Dentry cache",
3150 : : sizeof(struct hlist_bl_head),
3151 : : dhash_entries,
3152 : : 13,
3153 : : HASH_EARLY | HASH_ZERO,
3154 : : &d_hash_shift,
3155 : : NULL,
3156 : : 0,
3157 : : 0);
3158 : 207 : d_hash_shift = 32 - d_hash_shift;
3159 : : }
3160 : :
3161 : 207 : static void __init dcache_init(void)
3162 : : {
3163 : : /*
3164 : : * A constructor could be added for stable state like the lists,
3165 : : * but it is probably not worth it because of the cache nature
3166 : : * of the dcache.
3167 : : */
3168 : 207 : dentry_cache = KMEM_CACHE_USERCOPY(dentry,
3169 : : SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT,
3170 : : d_iname);
3171 : :
3172 : : /* Hash may have been set up in dcache_init_early */
3173 : : if (!hashdist)
3174 : 207 : return;
3175 : :
3176 : : dentry_hashtable =
3177 : : alloc_large_system_hash("Dentry cache",
3178 : : sizeof(struct hlist_bl_head),
3179 : : dhash_entries,
3180 : : 13,
3181 : : HASH_ZERO,
3182 : : &d_hash_shift,
3183 : : NULL,
3184 : : 0,
3185 : : 0);
3186 : : d_hash_shift = 32 - d_hash_shift;
3187 : : }
3188 : :
3189 : : /* SLAB cache for __getname() consumers */
3190 : : struct kmem_cache *names_cachep __read_mostly;
3191 : : EXPORT_SYMBOL(names_cachep);
3192 : :
3193 : 207 : void __init vfs_caches_init_early(void)
3194 : : {
3195 : : int i;
3196 : :
3197 [ + + ]: 212175 : for (i = 0; i < ARRAY_SIZE(in_lookup_hashtable); i++)
3198 : 211968 : INIT_HLIST_BL_HEAD(&in_lookup_hashtable[i]);
3199 : :
3200 : 207 : dcache_init_early();
3201 : 207 : inode_init_early();
3202 : 207 : }
3203 : :
3204 : 207 : void __init vfs_caches_init(void)
3205 : : {
3206 : 207 : names_cachep = kmem_cache_create_usercopy("names_cache", PATH_MAX, 0,
3207 : : SLAB_HWCACHE_ALIGN|SLAB_PANIC, 0, PATH_MAX, NULL);
3208 : :
3209 : 207 : dcache_init();
3210 : 207 : inode_init();
3211 : 207 : files_init();
3212 : 207 : files_maxfiles_init();
3213 : 207 : mnt_init();
3214 : 207 : bdev_cache_init();
3215 : 207 : chrdev_init();
3216 : 207 : }
|
