FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_cache.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1993, 1995
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Poul-Henning Kamp of the FreeBSD Project.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39
40 #include "opt_ddb.h"
41 #include "opt_ktrace.h"
42
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/capsicum.h>
46 #include <sys/counter.h>
47 #include <sys/filedesc.h>
48 #include <sys/fnv_hash.h>
49 #include <sys/kernel.h>
50 #include <sys/ktr.h>
51 #include <sys/lock.h>
52 #include <sys/malloc.h>
53 #include <sys/fcntl.h>
54 #include <sys/jail.h>
55 #include <sys/mount.h>
56 #include <sys/namei.h>
57 #include <sys/proc.h>
58 #include <sys/seqc.h>
59 #include <sys/sdt.h>
60 #include <sys/smr.h>
61 #include <sys/smp.h>
62 #include <sys/syscallsubr.h>
63 #include <sys/sysctl.h>
64 #include <sys/sysproto.h>
65 #include <sys/vnode.h>
66 #include <ck_queue.h>
67 #ifdef KTRACE
68 #include <sys/ktrace.h>
69 #endif
70 #ifdef INVARIANTS
71 #include <machine/_inttypes.h>
72 #endif
73
74 #include <sys/capsicum.h>
75
76 #include <security/audit/audit.h>
77 #include <security/mac/mac_framework.h>
78
79 #ifdef DDB
80 #include <ddb/ddb.h>
81 #endif
82
83 #include <vm/uma.h>
84
85 /*
86 * High level overview of name caching in the VFS layer.
87 *
88 * Originally caching was implemented as part of UFS, later extracted to allow
89 * use by other filesystems. A decision was made to make it optional and
90 * completely detached from the rest of the kernel, which comes with limitations
91 * outlined near the end of this comment block.
92 *
93 * This fundamental choice needs to be revisited. In the meantime, the current
94 * state is described below. Significance of all notable routines is explained
95 * in comments placed above their implementation. Scattered thoroughout the
96 * file are TODO comments indicating shortcomings which can be fixed without
97 * reworking everything (most of the fixes will likely be reusable). Various
98 * details are omitted from this explanation to not clutter the overview, they
99 * have to be checked by reading the code and associated commentary.
100 *
101 * Keep in mind that it's individual path components which are cached, not full
102 * paths. That is, for a fully cached path "foo/bar/baz" there are 3 entries,
103 * one for each name.
104 *
105 * I. Data organization
106 *
107 * Entries are described by "struct namecache" objects and stored in a hash
108 * table. See cache_get_hash for more information.
109 *
110 * "struct vnode" contains pointers to source entries (names which can be found
111 * when traversing through said vnode), destination entries (names of that
112 * vnode (see "Limitations" for a breakdown on the subject) and a pointer to
113 * the parent vnode.
114 *
115 * The (directory vnode; name) tuple reliably determines the target entry if
116 * it exists.
117 *
118 * Since there are no small locks at this time (all are 32 bytes in size on
119 * LP64), the code works around the problem by introducing lock arrays to
120 * protect hash buckets and vnode lists.
121 *
122 * II. Filesystem integration
123 *
124 * Filesystems participating in name caching do the following:
125 * - set vop_lookup routine to vfs_cache_lookup
126 * - set vop_cachedlookup to whatever can perform the lookup if the above fails
127 * - if they support lockless lookup (see below), vop_fplookup_vexec and
128 * vop_fplookup_symlink are set along with the MNTK_FPLOOKUP flag on the
129 * mount point
130 * - call cache_purge or cache_vop_* routines to eliminate stale entries as
131 * applicable
132 * - call cache_enter to add entries depending on the MAKEENTRY flag
133 *
134 * With the above in mind, there are 2 entry points when doing lookups:
135 * - ... -> namei -> cache_fplookup -- this is the default
136 * - ... -> VOP_LOOKUP -> vfs_cache_lookup -- normally only called by namei
137 * should the above fail
138 *
139 * Example code flow how an entry is added:
140 * ... -> namei -> cache_fplookup -> cache_fplookup_noentry -> VOP_LOOKUP ->
141 * vfs_cache_lookup -> VOP_CACHEDLOOKUP -> ufs_lookup_ino -> cache_enter
142 *
143 * III. Performance considerations
144 *
145 * For lockless case forward lookup avoids any writes to shared areas apart
146 * from the terminal path component. In other words non-modifying lookups of
147 * different files don't suffer any scalability problems in the namecache.
148 * Looking up the same file is limited by VFS and goes beyond the scope of this
149 * file.
150 *
151 * At least on amd64 the single-threaded bottleneck for long paths is hashing
152 * (see cache_get_hash). There are cases where the code issues acquire fence
153 * multiple times, they can be combined on architectures which suffer from it.
154 *
155 * For locked case each encountered vnode has to be referenced and locked in
156 * order to be handed out to the caller (normally that's namei). This
157 * introduces significant hit single-threaded and serialization multi-threaded.
158 *
159 * Reverse lookup (e.g., "getcwd") fully scales provided it is fully cached --
160 * avoids any writes to shared areas to any components.
161 *
162 * Unrelated insertions are partially serialized on updating the global entry
163 * counter and possibly serialized on colliding bucket or vnode locks.
164 *
165 * IV. Observability
166 *
167 * Note not everything has an explicit dtrace probe nor it should have, thus
168 * some of the one-liners below depend on implementation details.
169 *
170 * Examples:
171 *
172 * # Check what lookups failed to be handled in a lockless manner. Column 1 is
173 * # line number, column 2 is status code (see cache_fpl_status)
174 * dtrace -n 'vfs:fplookup:lookup:done { @[arg1, arg2] = count(); }'
175 *
176 * # Lengths of names added by binary name
177 * dtrace -n 'fbt::cache_enter_time:entry { @[execname] = quantize(args[2]->cn_namelen); }'
178 *
179 * # Same as above but only those which exceed 64 characters
180 * dtrace -n 'fbt::cache_enter_time:entry /args[2]->cn_namelen > 64/ { @[execname] = quantize(args[2]->cn_namelen); }'
181 *
182 * # Who is performing lookups with spurious slashes (e.g., "foo//bar") and what
183 * # path is it
184 * dtrace -n 'fbt::cache_fplookup_skip_slashes:entry { @[execname, stringof(args[0]->cnp->cn_pnbuf)] = count(); }'
185 *
186 * V. Limitations and implementation defects
187 *
188 * - since it is possible there is no entry for an open file, tools like
189 * "procstat" may fail to resolve fd -> vnode -> path to anything
190 * - even if a filesystem adds an entry, it may get purged (e.g., due to memory
191 * shortage) in which case the above problem applies
192 * - hardlinks are not tracked, thus if a vnode is reachable in more than one
193 * way, resolving a name may return a different path than the one used to
194 * open it (even if said path is still valid)
195 * - by default entries are not added for newly created files
196 * - adding an entry may need to evict negative entry first, which happens in 2
197 * distinct places (evicting on lookup, adding in a later VOP) making it
198 * impossible to simply reuse it
199 * - there is a simple scheme to evict negative entries as the cache is approaching
200 * its capacity, but it is very unclear if doing so is a good idea to begin with
201 * - vnodes are subject to being recycled even if target inode is left in memory,
202 * which loses the name cache entries when it perhaps should not. in case of tmpfs
203 * names get duplicated -- kept by filesystem itself and namecache separately
204 * - struct namecache has a fixed size and comes in 2 variants, often wasting space.
205 * now hard to replace with malloc due to dependence on SMR.
206 * - lack of better integration with the kernel also turns nullfs into a layered
207 * filesystem instead of something which can take advantage of caching
208 */
209
210 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
211 "Name cache");
212
213 SDT_PROVIDER_DECLARE(vfs);
214 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *",
215 "struct vnode *");
216 SDT_PROBE_DEFINE3(vfs, namecache, enter, duplicate, "struct vnode *", "char *",
217 "struct vnode *");
218 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
219 "char *");
220 SDT_PROBE_DEFINE2(vfs, namecache, fullpath_smr, hit, "struct vnode *",
221 "const char *");
222 SDT_PROBE_DEFINE4(vfs, namecache, fullpath_smr, miss, "struct vnode *",
223 "struct namecache *", "int", "int");
224 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
225 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
226 "char *", "struct vnode *");
227 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
228 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int",
229 "struct vnode *", "char *");
230 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
231 "struct vnode *");
232 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative,
233 "struct vnode *", "char *");
234 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
235 "char *");
236 SDT_PROBE_DEFINE2(vfs, namecache, removecnp, hit, "struct vnode *",
237 "struct componentname *");
238 SDT_PROBE_DEFINE2(vfs, namecache, removecnp, miss, "struct vnode *",
239 "struct componentname *");
240 SDT_PROBE_DEFINE3(vfs, namecache, purge, done, "struct vnode *", "size_t", "size_t");
241 SDT_PROBE_DEFINE1(vfs, namecache, purge, batch, "int");
242 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
243 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
244 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
245 "struct vnode *");
246 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *",
247 "char *");
248 SDT_PROBE_DEFINE2(vfs, namecache, evict_negative, done, "struct vnode *",
249 "char *");
250 SDT_PROBE_DEFINE1(vfs, namecache, symlink, alloc__fail, "size_t");
251
252 SDT_PROBE_DEFINE3(vfs, fplookup, lookup, done, "struct nameidata", "int", "bool");
253 SDT_PROBE_DECLARE(vfs, namei, lookup, entry);
254 SDT_PROBE_DECLARE(vfs, namei, lookup, return);
255
256 static char __read_frequently cache_fast_lookup_enabled = true;
257
258 /*
259 * This structure describes the elements in the cache of recent
260 * names looked up by namei.
261 */
262 struct negstate {
263 u_char neg_flag;
264 u_char neg_hit;
265 };
266 _Static_assert(sizeof(struct negstate) <= sizeof(struct vnode *),
267 "the state must fit in a union with a pointer without growing it");
268
269 struct namecache {
270 LIST_ENTRY(namecache) nc_src; /* source vnode list */
271 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
272 CK_SLIST_ENTRY(namecache) nc_hash;/* hash chain */
273 struct vnode *nc_dvp; /* vnode of parent of name */
274 union {
275 struct vnode *nu_vp; /* vnode the name refers to */
276 struct negstate nu_neg;/* negative entry state */
277 } n_un;
278 u_char nc_flag; /* flag bits */
279 u_char nc_nlen; /* length of name */
280 char nc_name[]; /* segment name + nul */
281 };
282
283 /*
284 * struct namecache_ts repeats struct namecache layout up to the
285 * nc_nlen member.
286 * struct namecache_ts is used in place of struct namecache when time(s) need
287 * to be stored. The nc_dotdottime field is used when a cache entry is mapping
288 * both a non-dotdot directory name plus dotdot for the directory's
289 * parent.
290 *
291 * See below for alignment requirement.
292 */
293 struct namecache_ts {
294 struct timespec nc_time; /* timespec provided by fs */
295 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */
296 int nc_ticks; /* ticks value when entry was added */
297 int nc_pad;
298 struct namecache nc_nc;
299 };
300
301 TAILQ_HEAD(cache_freebatch, namecache);
302
303 /*
304 * At least mips n32 performs 64-bit accesses to timespec as found
305 * in namecache_ts and requires them to be aligned. Since others
306 * may be in the same spot suffer a little bit and enforce the
307 * alignment for everyone. Note this is a nop for 64-bit platforms.
308 */
309 #define CACHE_ZONE_ALIGNMENT UMA_ALIGNOF(time_t)
310
311 /*
312 * TODO: the initial value of CACHE_PATH_CUTOFF was inherited from the
313 * 4.4 BSD codebase. Later on struct namecache was tweaked to become
314 * smaller and the value was bumped to retain the total size, but it
315 * was never re-evaluated for suitability. A simple test counting
316 * lengths during package building shows that the value of 45 covers
317 * about 86% of all added entries, reaching 99% at 65.
318 *
319 * Regardless of the above, use of dedicated zones instead of malloc may be
320 * inducing additional waste. This may be hard to address as said zones are
321 * tied to VFS SMR. Even if retaining them, the current split should be
322 * re-evaluated.
323 */
324 #ifdef __LP64__
325 #define CACHE_PATH_CUTOFF 45
326 #define CACHE_LARGE_PAD 6
327 #else
328 #define CACHE_PATH_CUTOFF 41
329 #define CACHE_LARGE_PAD 2
330 #endif
331
332 #define CACHE_ZONE_SMALL_SIZE (offsetof(struct namecache, nc_name) + CACHE_PATH_CUTOFF + 1)
333 #define CACHE_ZONE_SMALL_TS_SIZE (offsetof(struct namecache_ts, nc_nc) + CACHE_ZONE_SMALL_SIZE)
334 #define CACHE_ZONE_LARGE_SIZE (offsetof(struct namecache, nc_name) + NAME_MAX + 1 + CACHE_LARGE_PAD)
335 #define CACHE_ZONE_LARGE_TS_SIZE (offsetof(struct namecache_ts, nc_nc) + CACHE_ZONE_LARGE_SIZE)
336
337 _Static_assert((CACHE_ZONE_SMALL_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size");
338 _Static_assert((CACHE_ZONE_SMALL_TS_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size");
339 _Static_assert((CACHE_ZONE_LARGE_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size");
340 _Static_assert((CACHE_ZONE_LARGE_TS_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size");
341
342 #define nc_vp n_un.nu_vp
343 #define nc_neg n_un.nu_neg
344
345 /*
346 * Flags in namecache.nc_flag
347 */
348 #define NCF_WHITE 0x01
349 #define NCF_ISDOTDOT 0x02
350 #define NCF_TS 0x04
351 #define NCF_DTS 0x08
352 #define NCF_DVDROP 0x10
353 #define NCF_NEGATIVE 0x20
354 #define NCF_INVALID 0x40
355 #define NCF_WIP 0x80
356
357 /*
358 * Flags in negstate.neg_flag
359 */
360 #define NEG_HOT 0x01
361
362 static bool cache_neg_evict_cond(u_long lnumcache);
363
364 /*
365 * Mark an entry as invalid.
366 *
367 * This is called before it starts getting deconstructed.
368 */
369 static void
370 cache_ncp_invalidate(struct namecache *ncp)
371 {
372
373 KASSERT((ncp->nc_flag & NCF_INVALID) == 0,
374 ("%s: entry %p already invalid", __func__, ncp));
375 atomic_store_char(&ncp->nc_flag, ncp->nc_flag | NCF_INVALID);
376 atomic_thread_fence_rel();
377 }
378
379 /*
380 * Check whether the entry can be safely used.
381 *
382 * All places which elide locks are supposed to call this after they are
383 * done with reading from an entry.
384 */
385 #define cache_ncp_canuse(ncp) ({ \
386 struct namecache *_ncp = (ncp); \
387 u_char _nc_flag; \
388 \
389 atomic_thread_fence_acq(); \
390 _nc_flag = atomic_load_char(&_ncp->nc_flag); \
391 __predict_true((_nc_flag & (NCF_INVALID | NCF_WIP)) == 0); \
392 })
393
394 /*
395 * Like the above but also checks NCF_WHITE.
396 */
397 #define cache_fpl_neg_ncp_canuse(ncp) ({ \
398 struct namecache *_ncp = (ncp); \
399 u_char _nc_flag; \
400 \
401 atomic_thread_fence_acq(); \
402 _nc_flag = atomic_load_char(&_ncp->nc_flag); \
403 __predict_true((_nc_flag & (NCF_INVALID | NCF_WIP | NCF_WHITE)) == 0); \
404 })
405
406 VFS_SMR_DECLARE;
407
408 static SYSCTL_NODE(_vfs_cache, OID_AUTO, param, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
409 "Name cache parameters");
410
411 static u_int __read_mostly ncsize; /* the size as computed on creation or resizing */
412 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, size, CTLFLAG_RW, &ncsize, 0,
413 "Total namecache capacity");
414
415 u_int ncsizefactor = 2;
416 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, sizefactor, CTLFLAG_RW, &ncsizefactor, 0,
417 "Size factor for namecache");
418
419 static u_long __read_mostly ncnegfactor = 5; /* ratio of negative entries */
420 SYSCTL_ULONG(_vfs_cache_param, OID_AUTO, negfactor, CTLFLAG_RW, &ncnegfactor, 0,
421 "Ratio of negative namecache entries");
422
423 /*
424 * Negative entry % of namecache capacity above which automatic eviction is allowed.
425 *
426 * Check cache_neg_evict_cond for details.
427 */
428 static u_int ncnegminpct = 3;
429
430 static u_int __read_mostly neg_min; /* the above recomputed against ncsize */
431 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, negmin, CTLFLAG_RD, &neg_min, 0,
432 "Negative entry count above which automatic eviction is allowed");
433
434 /*
435 * Structures associated with name caching.
436 */
437 #define NCHHASH(hash) \
438 (&nchashtbl[(hash) & nchash])
439 static __read_mostly CK_SLIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */
440 static u_long __read_mostly nchash; /* size of hash table */
441 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
442 "Size of namecache hash table");
443 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */
444 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */
445
446 struct nchstats nchstats; /* cache effectiveness statistics */
447
448 static u_int __exclusive_cache_line neg_cycle;
449
450 #define ncneghash 3
451 #define numneglists (ncneghash + 1)
452
453 struct neglist {
454 struct mtx nl_evict_lock;
455 struct mtx nl_lock __aligned(CACHE_LINE_SIZE);
456 TAILQ_HEAD(, namecache) nl_list;
457 TAILQ_HEAD(, namecache) nl_hotlist;
458 u_long nl_hotnum;
459 } __aligned(CACHE_LINE_SIZE);
460
461 static struct neglist neglists[numneglists];
462
463 static inline struct neglist *
464 NCP2NEGLIST(struct namecache *ncp)
465 {
466
467 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]);
468 }
469
470 static inline struct negstate *
471 NCP2NEGSTATE(struct namecache *ncp)
472 {
473
474 MPASS(atomic_load_char(&ncp->nc_flag) & NCF_NEGATIVE);
475 return (&ncp->nc_neg);
476 }
477
478 #define numbucketlocks (ncbuckethash + 1)
479 static u_int __read_mostly ncbuckethash;
480 static struct mtx_padalign __read_mostly *bucketlocks;
481 #define HASH2BUCKETLOCK(hash) \
482 ((struct mtx *)(&bucketlocks[((hash) & ncbuckethash)]))
483
484 #define numvnodelocks (ncvnodehash + 1)
485 static u_int __read_mostly ncvnodehash;
486 static struct mtx __read_mostly *vnodelocks;
487 static inline struct mtx *
488 VP2VNODELOCK(struct vnode *vp)
489 {
490
491 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]);
492 }
493
494 static void
495 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp)
496 {
497 struct namecache_ts *ncp_ts;
498
499 KASSERT((ncp->nc_flag & NCF_TS) != 0 ||
500 (tsp == NULL && ticksp == NULL),
501 ("No NCF_TS"));
502
503 if (tsp == NULL)
504 return;
505
506 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
507 *tsp = ncp_ts->nc_time;
508 *ticksp = ncp_ts->nc_ticks;
509 }
510
511 #ifdef DEBUG_CACHE
512 static int __read_mostly doingcache = 1; /* 1 => enable the cache */
513 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0,
514 "VFS namecache enabled");
515 #endif
516
517 /* Export size information to userland */
518 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR,
519 sizeof(struct namecache), "sizeof(struct namecache)");
520
521 /*
522 * The new name cache statistics
523 */
524 static SYSCTL_NODE(_vfs_cache, OID_AUTO, stats, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
525 "Name cache statistics");
526
527 #define STATNODE_ULONG(name, varname, descr) \
528 SYSCTL_ULONG(_vfs_cache_stats, OID_AUTO, name, CTLFLAG_RD, &varname, 0, descr);
529 #define STATNODE_COUNTER(name, varname, descr) \
530 static COUNTER_U64_DEFINE_EARLY(varname); \
531 SYSCTL_COUNTER_U64(_vfs_cache_stats, OID_AUTO, name, CTLFLAG_RD, &varname, \
532 descr);
533 STATNODE_ULONG(neg, numneg, "Number of negative cache entries");
534 STATNODE_ULONG(count, numcache, "Number of cache entries");
535 STATNODE_COUNTER(heldvnodes, numcachehv, "Number of namecache entries with vnodes held");
536 STATNODE_COUNTER(drops, numdrops, "Number of dropped entries due to reaching the limit");
537 STATNODE_COUNTER(dothits, dothits, "Number of '.' hits");
538 STATNODE_COUNTER(dotdothis, dotdothits, "Number of '..' hits");
539 STATNODE_COUNTER(miss, nummiss, "Number of cache misses");
540 STATNODE_COUNTER(misszap, nummisszap, "Number of cache misses we do not want to cache");
541 STATNODE_COUNTER(posszaps, numposzaps,
542 "Number of cache hits (positive) we do not want to cache");
543 STATNODE_COUNTER(poshits, numposhits, "Number of cache hits (positive)");
544 STATNODE_COUNTER(negzaps, numnegzaps,
545 "Number of cache hits (negative) we do not want to cache");
546 STATNODE_COUNTER(neghits, numneghits, "Number of cache hits (negative)");
547 /* These count for vn_getcwd(), too. */
548 STATNODE_COUNTER(fullpathcalls, numfullpathcalls, "Number of fullpath search calls");
549 STATNODE_COUNTER(fullpathfail1, numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
550 STATNODE_COUNTER(fullpathfail2, numfullpathfail2,
551 "Number of fullpath search errors (VOP_VPTOCNP failures)");
552 STATNODE_COUNTER(fullpathfail4, numfullpathfail4, "Number of fullpath search errors (ENOMEM)");
553 STATNODE_COUNTER(fullpathfound, numfullpathfound, "Number of successful fullpath calls");
554 STATNODE_COUNTER(symlinktoobig, symlinktoobig, "Number of times symlink did not fit the cache");
555
556 /*
557 * Debug or developer statistics.
558 */
559 static SYSCTL_NODE(_vfs_cache, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
560 "Name cache debugging");
561 #define DEBUGNODE_ULONG(name, varname, descr) \
562 SYSCTL_ULONG(_vfs_cache_debug, OID_AUTO, name, CTLFLAG_RD, &varname, 0, descr);
563 #define DEBUGNODE_COUNTER(name, varname, descr) \
564 static COUNTER_U64_DEFINE_EARLY(varname); \
565 SYSCTL_COUNTER_U64(_vfs_cache_debug, OID_AUTO, name, CTLFLAG_RD, &varname, \
566 descr);
567 DEBUGNODE_COUNTER(zap_bucket_relock_success, zap_bucket_relock_success,
568 "Number of successful removals after relocking");
569 static long zap_bucket_fail;
570 DEBUGNODE_ULONG(zap_bucket_fail, zap_bucket_fail, "");
571 static long zap_bucket_fail2;
572 DEBUGNODE_ULONG(zap_bucket_fail2, zap_bucket_fail2, "");
573 static long cache_lock_vnodes_cel_3_failures;
574 DEBUGNODE_ULONG(vnodes_cel_3_failures, cache_lock_vnodes_cel_3_failures,
575 "Number of times 3-way vnode locking failed");
576
577 static void cache_zap_locked(struct namecache *ncp);
578 static int vn_fullpath_any_smr(struct vnode *vp, struct vnode *rdir, char *buf,
579 char **retbuf, size_t *buflen, size_t addend);
580 static int vn_fullpath_any(struct vnode *vp, struct vnode *rdir, char *buf,
581 char **retbuf, size_t *buflen);
582 static int vn_fullpath_dir(struct vnode *vp, struct vnode *rdir, char *buf,
583 char **retbuf, size_t *len, size_t addend);
584
585 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
586
587 static inline void
588 cache_assert_vlp_locked(struct mtx *vlp)
589 {
590
591 if (vlp != NULL)
592 mtx_assert(vlp, MA_OWNED);
593 }
594
595 static inline void
596 cache_assert_vnode_locked(struct vnode *vp)
597 {
598 struct mtx *vlp;
599
600 vlp = VP2VNODELOCK(vp);
601 cache_assert_vlp_locked(vlp);
602 }
603
604 /*
605 * Directory vnodes with entries are held for two reasons:
606 * 1. make them less of a target for reclamation in vnlru
607 * 2. suffer smaller performance penalty in locked lookup as requeieing is avoided
608 *
609 * It will be feasible to stop doing it altogether if all filesystems start
610 * supporting lockless lookup.
611 */
612 static void
613 cache_hold_vnode(struct vnode *vp)
614 {
615
616 cache_assert_vnode_locked(vp);
617 VNPASS(LIST_EMPTY(&vp->v_cache_src), vp);
618 vhold(vp);
619 counter_u64_add(numcachehv, 1);
620 }
621
622 static void
623 cache_drop_vnode(struct vnode *vp)
624 {
625
626 /*
627 * Called after all locks are dropped, meaning we can't assert
628 * on the state of v_cache_src.
629 */
630 vdrop(vp);
631 counter_u64_add(numcachehv, -1);
632 }
633
634 /*
635 * UMA zones.
636 */
637 static uma_zone_t __read_mostly cache_zone_small;
638 static uma_zone_t __read_mostly cache_zone_small_ts;
639 static uma_zone_t __read_mostly cache_zone_large;
640 static uma_zone_t __read_mostly cache_zone_large_ts;
641
642 char *
643 cache_symlink_alloc(size_t size, int flags)
644 {
645
646 if (size < CACHE_ZONE_SMALL_SIZE) {
647 return (uma_zalloc_smr(cache_zone_small, flags));
648 }
649 if (size < CACHE_ZONE_LARGE_SIZE) {
650 return (uma_zalloc_smr(cache_zone_large, flags));
651 }
652 counter_u64_add(symlinktoobig, 1);
653 SDT_PROBE1(vfs, namecache, symlink, alloc__fail, size);
654 return (NULL);
655 }
656
657 void
658 cache_symlink_free(char *string, size_t size)
659 {
660
661 MPASS(string != NULL);
662 KASSERT(size < CACHE_ZONE_LARGE_SIZE,
663 ("%s: size %zu too big", __func__, size));
664
665 if (size < CACHE_ZONE_SMALL_SIZE) {
666 uma_zfree_smr(cache_zone_small, string);
667 return;
668 }
669 if (size < CACHE_ZONE_LARGE_SIZE) {
670 uma_zfree_smr(cache_zone_large, string);
671 return;
672 }
673 __assert_unreachable();
674 }
675
676 static struct namecache *
677 cache_alloc_uma(int len, bool ts)
678 {
679 struct namecache_ts *ncp_ts;
680 struct namecache *ncp;
681
682 if (__predict_false(ts)) {
683 if (len <= CACHE_PATH_CUTOFF)
684 ncp_ts = uma_zalloc_smr(cache_zone_small_ts, M_WAITOK);
685 else
686 ncp_ts = uma_zalloc_smr(cache_zone_large_ts, M_WAITOK);
687 ncp = &ncp_ts->nc_nc;
688 } else {
689 if (len <= CACHE_PATH_CUTOFF)
690 ncp = uma_zalloc_smr(cache_zone_small, M_WAITOK);
691 else
692 ncp = uma_zalloc_smr(cache_zone_large, M_WAITOK);
693 }
694 return (ncp);
695 }
696
697 static void
698 cache_free_uma(struct namecache *ncp)
699 {
700 struct namecache_ts *ncp_ts;
701
702 if (__predict_false(ncp->nc_flag & NCF_TS)) {
703 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
704 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF)
705 uma_zfree_smr(cache_zone_small_ts, ncp_ts);
706 else
707 uma_zfree_smr(cache_zone_large_ts, ncp_ts);
708 } else {
709 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF)
710 uma_zfree_smr(cache_zone_small, ncp);
711 else
712 uma_zfree_smr(cache_zone_large, ncp);
713 }
714 }
715
716 static struct namecache *
717 cache_alloc(int len, bool ts)
718 {
719 u_long lnumcache;
720
721 /*
722 * Avoid blowout in namecache entries.
723 *
724 * Bugs:
725 * 1. filesystems may end up trying to add an already existing entry
726 * (for example this can happen after a cache miss during concurrent
727 * lookup), in which case we will call cache_neg_evict despite not
728 * adding anything.
729 * 2. the routine may fail to free anything and no provisions are made
730 * to make it try harder (see the inside for failure modes)
731 * 3. it only ever looks at negative entries.
732 */
733 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1;
734 if (cache_neg_evict_cond(lnumcache)) {
735 lnumcache = atomic_load_long(&numcache);
736 }
737 if (__predict_false(lnumcache >= ncsize)) {
738 atomic_subtract_long(&numcache, 1);
739 counter_u64_add(numdrops, 1);
740 return (NULL);
741 }
742 return (cache_alloc_uma(len, ts));
743 }
744
745 static void
746 cache_free(struct namecache *ncp)
747 {
748
749 MPASS(ncp != NULL);
750 if ((ncp->nc_flag & NCF_DVDROP) != 0) {
751 cache_drop_vnode(ncp->nc_dvp);
752 }
753 cache_free_uma(ncp);
754 atomic_subtract_long(&numcache, 1);
755 }
756
757 static void
758 cache_free_batch(struct cache_freebatch *batch)
759 {
760 struct namecache *ncp, *nnp;
761 int i;
762
763 i = 0;
764 if (TAILQ_EMPTY(batch))
765 goto out;
766 TAILQ_FOREACH_SAFE(ncp, batch, nc_dst, nnp) {
767 if ((ncp->nc_flag & NCF_DVDROP) != 0) {
768 cache_drop_vnode(ncp->nc_dvp);
769 }
770 cache_free_uma(ncp);
771 i++;
772 }
773 atomic_subtract_long(&numcache, i);
774 out:
775 SDT_PROBE1(vfs, namecache, purge, batch, i);
776 }
777
778 /*
779 * Hashing.
780 *
781 * The code was made to use FNV in 2001 and this choice needs to be revisited.
782 *
783 * Short summary of the difficulty:
784 * The longest name which can be inserted is NAME_MAX characters in length (or
785 * 255 at the time of writing this comment), while majority of names used in
786 * practice are significantly shorter (mostly below 10). More importantly
787 * majority of lookups performed find names are even shorter than that.
788 *
789 * This poses a problem where hashes which do better than FNV past word size
790 * (or so) tend to come with additional overhead when finalizing the result,
791 * making them noticeably slower for the most commonly used range.
792 *
793 * Consider a path like: /usr/obj/usr/src/sys/amd64/GENERIC/vnode_if.c
794 *
795 * When looking it up the most time consuming part by a large margin (at least
796 * on amd64) is hashing. Replacing FNV with something which pessimizes short
797 * input would make the slowest part stand out even more.
798 */
799
800 /*
801 * TODO: With the value stored we can do better than computing the hash based
802 * on the address.
803 */
804 static void
805 cache_prehash(struct vnode *vp)
806 {
807
808 vp->v_nchash = fnv_32_buf(&vp, sizeof(vp), FNV1_32_INIT);
809 }
810
811 static uint32_t
812 cache_get_hash(char *name, u_char len, struct vnode *dvp)
813 {
814
815 return (fnv_32_buf(name, len, dvp->v_nchash));
816 }
817
818 static uint32_t
819 cache_get_hash_iter_start(struct vnode *dvp)
820 {
821
822 return (dvp->v_nchash);
823 }
824
825 static uint32_t
826 cache_get_hash_iter(char c, uint32_t hash)
827 {
828
829 return (fnv_32_buf(&c, 1, hash));
830 }
831
832 static uint32_t
833 cache_get_hash_iter_finish(uint32_t hash)
834 {
835
836 return (hash);
837 }
838
839 static inline struct nchashhead *
840 NCP2BUCKET(struct namecache *ncp)
841 {
842 uint32_t hash;
843
844 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp);
845 return (NCHHASH(hash));
846 }
847
848 static inline struct mtx *
849 NCP2BUCKETLOCK(struct namecache *ncp)
850 {
851 uint32_t hash;
852
853 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp);
854 return (HASH2BUCKETLOCK(hash));
855 }
856
857 #ifdef INVARIANTS
858 static void
859 cache_assert_bucket_locked(struct namecache *ncp)
860 {
861 struct mtx *blp;
862
863 blp = NCP2BUCKETLOCK(ncp);
864 mtx_assert(blp, MA_OWNED);
865 }
866
867 static void
868 cache_assert_bucket_unlocked(struct namecache *ncp)
869 {
870 struct mtx *blp;
871
872 blp = NCP2BUCKETLOCK(ncp);
873 mtx_assert(blp, MA_NOTOWNED);
874 }
875 #else
876 #define cache_assert_bucket_locked(x) do { } while (0)
877 #define cache_assert_bucket_unlocked(x) do { } while (0)
878 #endif
879
880 #define cache_sort_vnodes(x, y) _cache_sort_vnodes((void **)(x), (void **)(y))
881 static void
882 _cache_sort_vnodes(void **p1, void **p2)
883 {
884 void *tmp;
885
886 MPASS(*p1 != NULL || *p2 != NULL);
887
888 if (*p1 > *p2) {
889 tmp = *p2;
890 *p2 = *p1;
891 *p1 = tmp;
892 }
893 }
894
895 static void
896 cache_lock_all_buckets(void)
897 {
898 u_int i;
899
900 for (i = 0; i < numbucketlocks; i++)
901 mtx_lock(&bucketlocks[i]);
902 }
903
904 static void
905 cache_unlock_all_buckets(void)
906 {
907 u_int i;
908
909 for (i = 0; i < numbucketlocks; i++)
910 mtx_unlock(&bucketlocks[i]);
911 }
912
913 static void
914 cache_lock_all_vnodes(void)
915 {
916 u_int i;
917
918 for (i = 0; i < numvnodelocks; i++)
919 mtx_lock(&vnodelocks[i]);
920 }
921
922 static void
923 cache_unlock_all_vnodes(void)
924 {
925 u_int i;
926
927 for (i = 0; i < numvnodelocks; i++)
928 mtx_unlock(&vnodelocks[i]);
929 }
930
931 static int
932 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
933 {
934
935 cache_sort_vnodes(&vlp1, &vlp2);
936
937 if (vlp1 != NULL) {
938 if (!mtx_trylock(vlp1))
939 return (EAGAIN);
940 }
941 if (!mtx_trylock(vlp2)) {
942 if (vlp1 != NULL)
943 mtx_unlock(vlp1);
944 return (EAGAIN);
945 }
946
947 return (0);
948 }
949
950 static void
951 cache_lock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
952 {
953
954 MPASS(vlp1 != NULL || vlp2 != NULL);
955 MPASS(vlp1 <= vlp2);
956
957 if (vlp1 != NULL)
958 mtx_lock(vlp1);
959 if (vlp2 != NULL)
960 mtx_lock(vlp2);
961 }
962
963 static void
964 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
965 {
966
967 MPASS(vlp1 != NULL || vlp2 != NULL);
968
969 if (vlp1 != NULL)
970 mtx_unlock(vlp1);
971 if (vlp2 != NULL)
972 mtx_unlock(vlp2);
973 }
974
975 static int
976 sysctl_nchstats(SYSCTL_HANDLER_ARGS)
977 {
978 struct nchstats snap;
979
980 if (req->oldptr == NULL)
981 return (SYSCTL_OUT(req, 0, sizeof(snap)));
982
983 snap = nchstats;
984 snap.ncs_goodhits = counter_u64_fetch(numposhits);
985 snap.ncs_neghits = counter_u64_fetch(numneghits);
986 snap.ncs_badhits = counter_u64_fetch(numposzaps) +
987 counter_u64_fetch(numnegzaps);
988 snap.ncs_miss = counter_u64_fetch(nummisszap) +
989 counter_u64_fetch(nummiss);
990
991 return (SYSCTL_OUT(req, &snap, sizeof(snap)));
992 }
993 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD |
994 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU",
995 "VFS cache effectiveness statistics");
996
997 static void
998 cache_recalc_neg_min(u_int val)
999 {
1000
1001 neg_min = (ncsize * val) / 100;
1002 }
1003
1004 static int
1005 sysctl_negminpct(SYSCTL_HANDLER_ARGS)
1006 {
1007 u_int val;
1008 int error;
1009
1010 val = ncnegminpct;
1011 error = sysctl_handle_int(oidp, &val, 0, req);
1012 if (error != 0 || req->newptr == NULL)
1013 return (error);
1014
1015 if (val == ncnegminpct)
1016 return (0);
1017 if (val < 0 || val > 99)
1018 return (EINVAL);
1019 ncnegminpct = val;
1020 cache_recalc_neg_min(val);
1021 return (0);
1022 }
1023
1024 SYSCTL_PROC(_vfs_cache_param, OID_AUTO, negminpct,
1025 CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0, sysctl_negminpct,
1026 "I", "Negative entry \% of namecache capacity above which automatic eviction is allowed");
1027
1028 #ifdef DEBUG_CACHE
1029 /*
1030 * Grab an atomic snapshot of the name cache hash chain lengths
1031 */
1032 static SYSCTL_NODE(_debug, OID_AUTO, hashstat,
1033 CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
1034 "hash table stats");
1035
1036 static int
1037 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
1038 {
1039 struct nchashhead *ncpp;
1040 struct namecache *ncp;
1041 int i, error, n_nchash, *cntbuf;
1042
1043 retry:
1044 n_nchash = nchash + 1; /* nchash is max index, not count */
1045 if (req->oldptr == NULL)
1046 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
1047 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK);
1048 cache_lock_all_buckets();
1049 if (n_nchash != nchash + 1) {
1050 cache_unlock_all_buckets();
1051 free(cntbuf, M_TEMP);
1052 goto retry;
1053 }
1054 /* Scan hash tables counting entries */
1055 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++)
1056 CK_SLIST_FOREACH(ncp, ncpp, nc_hash)
1057 cntbuf[i]++;
1058 cache_unlock_all_buckets();
1059 for (error = 0, i = 0; i < n_nchash; i++)
1060 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0)
1061 break;
1062 free(cntbuf, M_TEMP);
1063 return (error);
1064 }
1065 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD|
1066 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int",
1067 "nchash chain lengths");
1068
1069 static int
1070 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)
1071 {
1072 int error;
1073 struct nchashhead *ncpp;
1074 struct namecache *ncp;
1075 int n_nchash;
1076 int count, maxlength, used, pct;
1077
1078 if (!req->oldptr)
1079 return SYSCTL_OUT(req, 0, 4 * sizeof(int));
1080
1081 cache_lock_all_buckets();
1082 n_nchash = nchash + 1; /* nchash is max index, not count */
1083 used = 0;
1084 maxlength = 0;
1085
1086 /* Scan hash tables for applicable entries */
1087 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
1088 count = 0;
1089 CK_SLIST_FOREACH(ncp, ncpp, nc_hash) {
1090 count++;
1091 }
1092 if (count)
1093 used++;
1094 if (maxlength < count)
1095 maxlength = count;
1096 }
1097 n_nchash = nchash + 1;
1098 cache_unlock_all_buckets();
1099 pct = (used * 100) / (n_nchash / 100);
1100 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
1101 if (error)
1102 return (error);
1103 error = SYSCTL_OUT(req, &used, sizeof(used));
1104 if (error)
1105 return (error);
1106 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength));
1107 if (error)
1108 return (error);
1109 error = SYSCTL_OUT(req, &pct, sizeof(pct));
1110 if (error)
1111 return (error);
1112 return (0);
1113 }
1114 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD|
1115 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I",
1116 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)");
1117 #endif
1118
1119 /*
1120 * Negative entries management
1121 *
1122 * Various workloads create plenty of negative entries and barely use them
1123 * afterwards. Moreover malicious users can keep performing bogus lookups
1124 * adding even more entries. For example "make tinderbox" as of writing this
1125 * comment ends up with 2.6M namecache entries in total, 1.2M of which are
1126 * negative.
1127 *
1128 * As such, a rather aggressive eviction method is needed. The currently
1129 * employed method is a placeholder.
1130 *
1131 * Entries are split over numneglists separate lists, each of which is further
1132 * split into hot and cold entries. Entries get promoted after getting a hit.
1133 * Eviction happens on addition of new entry.
1134 */
1135 static SYSCTL_NODE(_vfs_cache, OID_AUTO, neg, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
1136 "Name cache negative entry statistics");
1137
1138 SYSCTL_ULONG(_vfs_cache_neg, OID_AUTO, count, CTLFLAG_RD, &numneg, 0,
1139 "Number of negative cache entries");
1140
1141 static COUNTER_U64_DEFINE_EARLY(neg_created);
1142 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, created, CTLFLAG_RD, &neg_created,
1143 "Number of created negative entries");
1144
1145 static COUNTER_U64_DEFINE_EARLY(neg_evicted);
1146 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evicted, CTLFLAG_RD, &neg_evicted,
1147 "Number of evicted negative entries");
1148
1149 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_empty);
1150 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_empty, CTLFLAG_RD,
1151 &neg_evict_skipped_empty,
1152 "Number of times evicting failed due to lack of entries");
1153
1154 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_missed);
1155 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_missed, CTLFLAG_RD,
1156 &neg_evict_skipped_missed,
1157 "Number of times evicting failed due to target entry disappearing");
1158
1159 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_contended);
1160 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_contended, CTLFLAG_RD,
1161 &neg_evict_skipped_contended,
1162 "Number of times evicting failed due to contention");
1163
1164 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, hits, CTLFLAG_RD, &numneghits,
1165 "Number of cache hits (negative)");
1166
1167 static int
1168 sysctl_neg_hot(SYSCTL_HANDLER_ARGS)
1169 {
1170 int i, out;
1171
1172 out = 0;
1173 for (i = 0; i < numneglists; i++)
1174 out += neglists[i].nl_hotnum;
1175
1176 return (SYSCTL_OUT(req, &out, sizeof(out)));
1177 }
1178 SYSCTL_PROC(_vfs_cache_neg, OID_AUTO, hot, CTLTYPE_INT | CTLFLAG_RD |
1179 CTLFLAG_MPSAFE, 0, 0, sysctl_neg_hot, "I",
1180 "Number of hot negative entries");
1181
1182 static void
1183 cache_neg_init(struct namecache *ncp)
1184 {
1185 struct negstate *ns;
1186
1187 ncp->nc_flag |= NCF_NEGATIVE;
1188 ns = NCP2NEGSTATE(ncp);
1189 ns->neg_flag = 0;
1190 ns->neg_hit = 0;
1191 counter_u64_add(neg_created, 1);
1192 }
1193
1194 #define CACHE_NEG_PROMOTION_THRESH 2
1195
1196 static bool
1197 cache_neg_hit_prep(struct namecache *ncp)
1198 {
1199 struct negstate *ns;
1200 u_char n;
1201
1202 ns = NCP2NEGSTATE(ncp);
1203 n = atomic_load_char(&ns->neg_hit);
1204 for (;;) {
1205 if (n >= CACHE_NEG_PROMOTION_THRESH)
1206 return (false);
1207 if (atomic_fcmpset_8(&ns->neg_hit, &n, n + 1))
1208 break;
1209 }
1210 return (n + 1 == CACHE_NEG_PROMOTION_THRESH);
1211 }
1212
1213 /*
1214 * Nothing to do here but it is provided for completeness as some
1215 * cache_neg_hit_prep callers may end up returning without even
1216 * trying to promote.
1217 */
1218 #define cache_neg_hit_abort(ncp) do { } while (0)
1219
1220 static void
1221 cache_neg_hit_finish(struct namecache *ncp)
1222 {
1223
1224 SDT_PROBE2(vfs, namecache, lookup, hit__negative, ncp->nc_dvp, ncp->nc_name);
1225 counter_u64_add(numneghits, 1);
1226 }
1227
1228 /*
1229 * Move a negative entry to the hot list.
1230 */
1231 static void
1232 cache_neg_promote_locked(struct namecache *ncp)
1233 {
1234 struct neglist *nl;
1235 struct negstate *ns;
1236
1237 ns = NCP2NEGSTATE(ncp);
1238 nl = NCP2NEGLIST(ncp);
1239 mtx_assert(&nl->nl_lock, MA_OWNED);
1240 if ((ns->neg_flag & NEG_HOT) == 0) {
1241 TAILQ_REMOVE(&nl->nl_list, ncp, nc_dst);
1242 TAILQ_INSERT_TAIL(&nl->nl_hotlist, ncp, nc_dst);
1243 nl->nl_hotnum++;
1244 ns->neg_flag |= NEG_HOT;
1245 }
1246 }
1247
1248 /*
1249 * Move a hot negative entry to the cold list.
1250 */
1251 static void
1252 cache_neg_demote_locked(struct namecache *ncp)
1253 {
1254 struct neglist *nl;
1255 struct negstate *ns;
1256
1257 ns = NCP2NEGSTATE(ncp);
1258 nl = NCP2NEGLIST(ncp);
1259 mtx_assert(&nl->nl_lock, MA_OWNED);
1260 MPASS(ns->neg_flag & NEG_HOT);
1261 TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst);
1262 TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst);
1263 nl->nl_hotnum--;
1264 ns->neg_flag &= ~NEG_HOT;
1265 atomic_store_char(&ns->neg_hit, 0);
1266 }
1267
1268 /*
1269 * Move a negative entry to the hot list if it matches the lookup.
1270 *
1271 * We have to take locks, but they may be contended and in the worst
1272 * case we may need to go off CPU. We don't want to spin within the
1273 * smr section and we can't block with it. Exiting the section means
1274 * the found entry could have been evicted. We are going to look it
1275 * up again.
1276 */
1277 static bool
1278 cache_neg_promote_cond(struct vnode *dvp, struct componentname *cnp,
1279 struct namecache *oncp, uint32_t hash)
1280 {
1281 struct namecache *ncp;
1282 struct neglist *nl;
1283 u_char nc_flag;
1284
1285 nl = NCP2NEGLIST(oncp);
1286
1287 mtx_lock(&nl->nl_lock);
1288 /*
1289 * For hash iteration.
1290 */
1291 vfs_smr_enter();
1292
1293 /*
1294 * Avoid all surprises by only succeeding if we got the same entry and
1295 * bailing completely otherwise.
1296 * XXX There are no provisions to keep the vnode around, meaning we may
1297 * end up promoting a negative entry for a *new* vnode and returning
1298 * ENOENT on its account. This is the error we want to return anyway
1299 * and promotion is harmless.
1300 *
1301 * In particular at this point there can be a new ncp which matches the
1302 * search but hashes to a different neglist.
1303 */
1304 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1305 if (ncp == oncp)
1306 break;
1307 }
1308
1309 /*
1310 * No match to begin with.
1311 */
1312 if (__predict_false(ncp == NULL)) {
1313 goto out_abort;
1314 }
1315
1316 /*
1317 * The newly found entry may be something different...
1318 */
1319 if (!(ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
1320 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))) {
1321 goto out_abort;
1322 }
1323
1324 /*
1325 * ... and not even negative.
1326 */
1327 nc_flag = atomic_load_char(&ncp->nc_flag);
1328 if ((nc_flag & NCF_NEGATIVE) == 0) {
1329 goto out_abort;
1330 }
1331
1332 if (!cache_ncp_canuse(ncp)) {
1333 goto out_abort;
1334 }
1335
1336 cache_neg_promote_locked(ncp);
1337 cache_neg_hit_finish(ncp);
1338 vfs_smr_exit();
1339 mtx_unlock(&nl->nl_lock);
1340 return (true);
1341 out_abort:
1342 vfs_smr_exit();
1343 mtx_unlock(&nl->nl_lock);
1344 return (false);
1345 }
1346
1347 static void
1348 cache_neg_promote(struct namecache *ncp)
1349 {
1350 struct neglist *nl;
1351
1352 nl = NCP2NEGLIST(ncp);
1353 mtx_lock(&nl->nl_lock);
1354 cache_neg_promote_locked(ncp);
1355 mtx_unlock(&nl->nl_lock);
1356 }
1357
1358 static void
1359 cache_neg_insert(struct namecache *ncp)
1360 {
1361 struct neglist *nl;
1362
1363 MPASS(ncp->nc_flag & NCF_NEGATIVE);
1364 cache_assert_bucket_locked(ncp);
1365 nl = NCP2NEGLIST(ncp);
1366 mtx_lock(&nl->nl_lock);
1367 TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst);
1368 mtx_unlock(&nl->nl_lock);
1369 atomic_add_long(&numneg, 1);
1370 }
1371
1372 static void
1373 cache_neg_remove(struct namecache *ncp)
1374 {
1375 struct neglist *nl;
1376 struct negstate *ns;
1377
1378 cache_assert_bucket_locked(ncp);
1379 nl = NCP2NEGLIST(ncp);
1380 ns = NCP2NEGSTATE(ncp);
1381 mtx_lock(&nl->nl_lock);
1382 if ((ns->neg_flag & NEG_HOT) != 0) {
1383 TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst);
1384 nl->nl_hotnum--;
1385 } else {
1386 TAILQ_REMOVE(&nl->nl_list, ncp, nc_dst);
1387 }
1388 mtx_unlock(&nl->nl_lock);
1389 atomic_subtract_long(&numneg, 1);
1390 }
1391
1392 static struct neglist *
1393 cache_neg_evict_select_list(void)
1394 {
1395 struct neglist *nl;
1396 u_int c;
1397
1398 c = atomic_fetchadd_int(&neg_cycle, 1) + 1;
1399 nl = &neglists[c % numneglists];
1400 if (!mtx_trylock(&nl->nl_evict_lock)) {
1401 counter_u64_add(neg_evict_skipped_contended, 1);
1402 return (NULL);
1403 }
1404 return (nl);
1405 }
1406
1407 static struct namecache *
1408 cache_neg_evict_select_entry(struct neglist *nl)
1409 {
1410 struct namecache *ncp, *lncp;
1411 struct negstate *ns, *lns;
1412 int i;
1413
1414 mtx_assert(&nl->nl_evict_lock, MA_OWNED);
1415 mtx_assert(&nl->nl_lock, MA_OWNED);
1416 ncp = TAILQ_FIRST(&nl->nl_list);
1417 if (ncp == NULL)
1418 return (NULL);
1419 lncp = ncp;
1420 lns = NCP2NEGSTATE(lncp);
1421 for (i = 1; i < 4; i++) {
1422 ncp = TAILQ_NEXT(ncp, nc_dst);
1423 if (ncp == NULL)
1424 break;
1425 ns = NCP2NEGSTATE(ncp);
1426 if (ns->neg_hit < lns->neg_hit) {
1427 lncp = ncp;
1428 lns = ns;
1429 }
1430 }
1431 return (lncp);
1432 }
1433
1434 static bool
1435 cache_neg_evict(void)
1436 {
1437 struct namecache *ncp, *ncp2;
1438 struct neglist *nl;
1439 struct vnode *dvp;
1440 struct mtx *dvlp;
1441 struct mtx *blp;
1442 uint32_t hash;
1443 u_char nlen;
1444 bool evicted;
1445
1446 nl = cache_neg_evict_select_list();
1447 if (nl == NULL) {
1448 return (false);
1449 }
1450
1451 mtx_lock(&nl->nl_lock);
1452 ncp = TAILQ_FIRST(&nl->nl_hotlist);
1453 if (ncp != NULL) {
1454 cache_neg_demote_locked(ncp);
1455 }
1456 ncp = cache_neg_evict_select_entry(nl);
1457 if (ncp == NULL) {
1458 counter_u64_add(neg_evict_skipped_empty, 1);
1459 mtx_unlock(&nl->nl_lock);
1460 mtx_unlock(&nl->nl_evict_lock);
1461 return (false);
1462 }
1463 nlen = ncp->nc_nlen;
1464 dvp = ncp->nc_dvp;
1465 hash = cache_get_hash(ncp->nc_name, nlen, dvp);
1466 dvlp = VP2VNODELOCK(dvp);
1467 blp = HASH2BUCKETLOCK(hash);
1468 mtx_unlock(&nl->nl_lock);
1469 mtx_unlock(&nl->nl_evict_lock);
1470 mtx_lock(dvlp);
1471 mtx_lock(blp);
1472 /*
1473 * Note that since all locks were dropped above, the entry may be
1474 * gone or reallocated to be something else.
1475 */
1476 CK_SLIST_FOREACH(ncp2, (NCHHASH(hash)), nc_hash) {
1477 if (ncp2 == ncp && ncp2->nc_dvp == dvp &&
1478 ncp2->nc_nlen == nlen && (ncp2->nc_flag & NCF_NEGATIVE) != 0)
1479 break;
1480 }
1481 if (ncp2 == NULL) {
1482 counter_u64_add(neg_evict_skipped_missed, 1);
1483 ncp = NULL;
1484 evicted = false;
1485 } else {
1486 MPASS(dvlp == VP2VNODELOCK(ncp->nc_dvp));
1487 MPASS(blp == NCP2BUCKETLOCK(ncp));
1488 SDT_PROBE2(vfs, namecache, evict_negative, done, ncp->nc_dvp,
1489 ncp->nc_name);
1490 cache_zap_locked(ncp);
1491 counter_u64_add(neg_evicted, 1);
1492 evicted = true;
1493 }
1494 mtx_unlock(blp);
1495 mtx_unlock(dvlp);
1496 if (ncp != NULL)
1497 cache_free(ncp);
1498 return (evicted);
1499 }
1500
1501 /*
1502 * Maybe evict a negative entry to create more room.
1503 *
1504 * The ncnegfactor parameter limits what fraction of the total count
1505 * can comprise of negative entries. However, if the cache is just
1506 * warming up this leads to excessive evictions. As such, ncnegminpct
1507 * (recomputed to neg_min) dictates whether the above should be
1508 * applied.
1509 *
1510 * Try evicting if the cache is close to full capacity regardless of
1511 * other considerations.
1512 */
1513 static bool
1514 cache_neg_evict_cond(u_long lnumcache)
1515 {
1516 u_long lnumneg;
1517
1518 if (ncsize - 1000 < lnumcache)
1519 goto out_evict;
1520 lnumneg = atomic_load_long(&numneg);
1521 if (lnumneg < neg_min)
1522 return (false);
1523 if (lnumneg * ncnegfactor < lnumcache)
1524 return (false);
1525 out_evict:
1526 return (cache_neg_evict());
1527 }
1528
1529 /*
1530 * cache_zap_locked():
1531 *
1532 * Removes a namecache entry from cache, whether it contains an actual
1533 * pointer to a vnode or if it is just a negative cache entry.
1534 */
1535 static void
1536 cache_zap_locked(struct namecache *ncp)
1537 {
1538 struct nchashhead *ncpp;
1539 struct vnode *dvp, *vp;
1540
1541 dvp = ncp->nc_dvp;
1542 vp = ncp->nc_vp;
1543
1544 if (!(ncp->nc_flag & NCF_NEGATIVE))
1545 cache_assert_vnode_locked(vp);
1546 cache_assert_vnode_locked(dvp);
1547 cache_assert_bucket_locked(ncp);
1548
1549 cache_ncp_invalidate(ncp);
1550
1551 ncpp = NCP2BUCKET(ncp);
1552 CK_SLIST_REMOVE(ncpp, ncp, namecache, nc_hash);
1553 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
1554 SDT_PROBE3(vfs, namecache, zap, done, dvp, ncp->nc_name, vp);
1555 TAILQ_REMOVE(&vp->v_cache_dst, ncp, nc_dst);
1556 if (ncp == vp->v_cache_dd) {
1557 atomic_store_ptr(&vp->v_cache_dd, NULL);
1558 }
1559 } else {
1560 SDT_PROBE2(vfs, namecache, zap_negative, done, dvp, ncp->nc_name);
1561 cache_neg_remove(ncp);
1562 }
1563 if (ncp->nc_flag & NCF_ISDOTDOT) {
1564 if (ncp == dvp->v_cache_dd) {
1565 atomic_store_ptr(&dvp->v_cache_dd, NULL);
1566 }
1567 } else {
1568 LIST_REMOVE(ncp, nc_src);
1569 if (LIST_EMPTY(&dvp->v_cache_src)) {
1570 ncp->nc_flag |= NCF_DVDROP;
1571 }
1572 }
1573 }
1574
1575 static void
1576 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp)
1577 {
1578 struct mtx *blp;
1579
1580 MPASS(ncp->nc_dvp == vp);
1581 MPASS(ncp->nc_flag & NCF_NEGATIVE);
1582 cache_assert_vnode_locked(vp);
1583
1584 blp = NCP2BUCKETLOCK(ncp);
1585 mtx_lock(blp);
1586 cache_zap_locked(ncp);
1587 mtx_unlock(blp);
1588 }
1589
1590 static bool
1591 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp,
1592 struct mtx **vlpp)
1593 {
1594 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
1595 struct mtx *blp;
1596
1597 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
1598 cache_assert_vnode_locked(vp);
1599
1600 if (ncp->nc_flag & NCF_NEGATIVE) {
1601 if (*vlpp != NULL) {
1602 mtx_unlock(*vlpp);
1603 *vlpp = NULL;
1604 }
1605 cache_zap_negative_locked_vnode_kl(ncp, vp);
1606 return (true);
1607 }
1608
1609 pvlp = VP2VNODELOCK(vp);
1610 blp = NCP2BUCKETLOCK(ncp);
1611 vlp1 = VP2VNODELOCK(ncp->nc_dvp);
1612 vlp2 = VP2VNODELOCK(ncp->nc_vp);
1613
1614 if (*vlpp == vlp1 || *vlpp == vlp2) {
1615 to_unlock = *vlpp;
1616 *vlpp = NULL;
1617 } else {
1618 if (*vlpp != NULL) {
1619 mtx_unlock(*vlpp);
1620 *vlpp = NULL;
1621 }
1622 cache_sort_vnodes(&vlp1, &vlp2);
1623 if (vlp1 == pvlp) {
1624 mtx_lock(vlp2);
1625 to_unlock = vlp2;
1626 } else {
1627 if (!mtx_trylock(vlp1))
1628 goto out_relock;
1629 to_unlock = vlp1;
1630 }
1631 }
1632 mtx_lock(blp);
1633 cache_zap_locked(ncp);
1634 mtx_unlock(blp);
1635 if (to_unlock != NULL)
1636 mtx_unlock(to_unlock);
1637 return (true);
1638
1639 out_relock:
1640 mtx_unlock(vlp2);
1641 mtx_lock(vlp1);
1642 mtx_lock(vlp2);
1643 MPASS(*vlpp == NULL);
1644 *vlpp = vlp1;
1645 return (false);
1646 }
1647
1648 /*
1649 * If trylocking failed we can get here. We know enough to take all needed locks
1650 * in the right order and re-lookup the entry.
1651 */
1652 static int
1653 cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp,
1654 struct vnode *dvp, struct mtx *dvlp, struct mtx *vlp, uint32_t hash,
1655 struct mtx *blp)
1656 {
1657 struct namecache *rncp;
1658
1659 cache_assert_bucket_unlocked(ncp);
1660
1661 cache_sort_vnodes(&dvlp, &vlp);
1662 cache_lock_vnodes(dvlp, vlp);
1663 mtx_lock(blp);
1664 CK_SLIST_FOREACH(rncp, (NCHHASH(hash)), nc_hash) {
1665 if (rncp == ncp && rncp->nc_dvp == dvp &&
1666 rncp->nc_nlen == cnp->cn_namelen &&
1667 !bcmp(rncp->nc_name, cnp->cn_nameptr, rncp->nc_nlen))
1668 break;
1669 }
1670 if (rncp != NULL) {
1671 cache_zap_locked(rncp);
1672 mtx_unlock(blp);
1673 cache_unlock_vnodes(dvlp, vlp);
1674 counter_u64_add(zap_bucket_relock_success, 1);
1675 return (0);
1676 }
1677
1678 mtx_unlock(blp);
1679 cache_unlock_vnodes(dvlp, vlp);
1680 return (EAGAIN);
1681 }
1682
1683 static int __noinline
1684 cache_zap_locked_bucket(struct namecache *ncp, struct componentname *cnp,
1685 uint32_t hash, struct mtx *blp)
1686 {
1687 struct mtx *dvlp, *vlp;
1688 struct vnode *dvp;
1689
1690 cache_assert_bucket_locked(ncp);
1691
1692 dvlp = VP2VNODELOCK(ncp->nc_dvp);
1693 vlp = NULL;
1694 if (!(ncp->nc_flag & NCF_NEGATIVE))
1695 vlp = VP2VNODELOCK(ncp->nc_vp);
1696 if (cache_trylock_vnodes(dvlp, vlp) == 0) {
1697 cache_zap_locked(ncp);
1698 mtx_unlock(blp);
1699 cache_unlock_vnodes(dvlp, vlp);
1700 return (0);
1701 }
1702
1703 dvp = ncp->nc_dvp;
1704 mtx_unlock(blp);
1705 return (cache_zap_unlocked_bucket(ncp, cnp, dvp, dvlp, vlp, hash, blp));
1706 }
1707
1708 static __noinline int
1709 cache_remove_cnp(struct vnode *dvp, struct componentname *cnp)
1710 {
1711 struct namecache *ncp;
1712 struct mtx *blp;
1713 struct mtx *dvlp, *dvlp2;
1714 uint32_t hash;
1715 int error;
1716
1717 if (cnp->cn_namelen == 2 &&
1718 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') {
1719 dvlp = VP2VNODELOCK(dvp);
1720 dvlp2 = NULL;
1721 mtx_lock(dvlp);
1722 retry_dotdot:
1723 ncp = dvp->v_cache_dd;
1724 if (ncp == NULL) {
1725 mtx_unlock(dvlp);
1726 if (dvlp2 != NULL)
1727 mtx_unlock(dvlp2);
1728 SDT_PROBE2(vfs, namecache, removecnp, miss, dvp, cnp);
1729 return (0);
1730 }
1731 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
1732 if (!cache_zap_locked_vnode_kl2(ncp, dvp, &dvlp2))
1733 goto retry_dotdot;
1734 MPASS(dvp->v_cache_dd == NULL);
1735 mtx_unlock(dvlp);
1736 if (dvlp2 != NULL)
1737 mtx_unlock(dvlp2);
1738 cache_free(ncp);
1739 } else {
1740 atomic_store_ptr(&dvp->v_cache_dd, NULL);
1741 mtx_unlock(dvlp);
1742 if (dvlp2 != NULL)
1743 mtx_unlock(dvlp2);
1744 }
1745 SDT_PROBE2(vfs, namecache, removecnp, hit, dvp, cnp);
1746 return (1);
1747 }
1748
1749 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
1750 blp = HASH2BUCKETLOCK(hash);
1751 retry:
1752 if (CK_SLIST_EMPTY(NCHHASH(hash)))
1753 goto out_no_entry;
1754
1755 mtx_lock(blp);
1756
1757 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1758 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
1759 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
1760 break;
1761 }
1762
1763 if (ncp == NULL) {
1764 mtx_unlock(blp);
1765 goto out_no_entry;
1766 }
1767
1768 error = cache_zap_locked_bucket(ncp, cnp, hash, blp);
1769 if (__predict_false(error != 0)) {
1770 zap_bucket_fail++;
1771 goto retry;
1772 }
1773 counter_u64_add(numposzaps, 1);
1774 SDT_PROBE2(vfs, namecache, removecnp, hit, dvp, cnp);
1775 cache_free(ncp);
1776 return (1);
1777 out_no_entry:
1778 counter_u64_add(nummisszap, 1);
1779 SDT_PROBE2(vfs, namecache, removecnp, miss, dvp, cnp);
1780 return (0);
1781 }
1782
1783 static int __noinline
1784 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
1785 struct timespec *tsp, int *ticksp)
1786 {
1787 int ltype;
1788
1789 *vpp = dvp;
1790 counter_u64_add(dothits, 1);
1791 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
1792 if (tsp != NULL)
1793 timespecclear(tsp);
1794 if (ticksp != NULL)
1795 *ticksp = ticks;
1796 vrefact(*vpp);
1797 /*
1798 * When we lookup "." we still can be asked to lock it
1799 * differently...
1800 */
1801 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
1802 if (ltype != VOP_ISLOCKED(*vpp)) {
1803 if (ltype == LK_EXCLUSIVE) {
1804 vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
1805 if (VN_IS_DOOMED((*vpp))) {
1806 /* forced unmount */
1807 vrele(*vpp);
1808 *vpp = NULL;
1809 return (ENOENT);
1810 }
1811 } else
1812 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
1813 }
1814 return (-1);
1815 }
1816
1817 static int __noinline
1818 cache_lookup_dotdot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
1819 struct timespec *tsp, int *ticksp)
1820 {
1821 struct namecache_ts *ncp_ts;
1822 struct namecache *ncp;
1823 struct mtx *dvlp;
1824 enum vgetstate vs;
1825 int error, ltype;
1826 bool whiteout;
1827
1828 MPASS((cnp->cn_flags & ISDOTDOT) != 0);
1829
1830 if ((cnp->cn_flags & MAKEENTRY) == 0) {
1831 cache_remove_cnp(dvp, cnp);
1832 return (0);
1833 }
1834
1835 counter_u64_add(dotdothits, 1);
1836 retry:
1837 dvlp = VP2VNODELOCK(dvp);
1838 mtx_lock(dvlp);
1839 ncp = dvp->v_cache_dd;
1840 if (ncp == NULL) {
1841 SDT_PROBE2(vfs, namecache, lookup, miss, dvp, "..");
1842 mtx_unlock(dvlp);
1843 return (0);
1844 }
1845 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
1846 if (ncp->nc_flag & NCF_NEGATIVE)
1847 *vpp = NULL;
1848 else
1849 *vpp = ncp->nc_vp;
1850 } else
1851 *vpp = ncp->nc_dvp;
1852 if (*vpp == NULL)
1853 goto negative_success;
1854 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", *vpp);
1855 cache_out_ts(ncp, tsp, ticksp);
1856 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
1857 NCF_DTS && tsp != NULL) {
1858 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
1859 *tsp = ncp_ts->nc_dotdottime;
1860 }
1861
1862 MPASS(dvp != *vpp);
1863 ltype = VOP_ISLOCKED(dvp);
1864 VOP_UNLOCK(dvp);
1865 vs = vget_prep(*vpp);
1866 mtx_unlock(dvlp);
1867 error = vget_finish(*vpp, cnp->cn_lkflags, vs);
1868 vn_lock(dvp, ltype | LK_RETRY);
1869 if (VN_IS_DOOMED(dvp)) {
1870 if (error == 0)
1871 vput(*vpp);
1872 *vpp = NULL;
1873 return (ENOENT);
1874 }
1875 if (error) {
1876 *vpp = NULL;
1877 goto retry;
1878 }
1879 return (-1);
1880 negative_success:
1881 if (__predict_false(cnp->cn_nameiop == CREATE)) {
1882 if (cnp->cn_flags & ISLASTCN) {
1883 counter_u64_add(numnegzaps, 1);
1884 cache_zap_negative_locked_vnode_kl(ncp, dvp);
1885 mtx_unlock(dvlp);
1886 cache_free(ncp);
1887 return (0);
1888 }
1889 }
1890
1891 whiteout = (ncp->nc_flag & NCF_WHITE);
1892 cache_out_ts(ncp, tsp, ticksp);
1893 if (cache_neg_hit_prep(ncp))
1894 cache_neg_promote(ncp);
1895 else
1896 cache_neg_hit_finish(ncp);
1897 mtx_unlock(dvlp);
1898 if (whiteout)
1899 cnp->cn_flags |= ISWHITEOUT;
1900 return (ENOENT);
1901 }
1902
1903 /**
1904 * Lookup a name in the name cache
1905 *
1906 * # Arguments
1907 *
1908 * - dvp: Parent directory in which to search.
1909 * - vpp: Return argument. Will contain desired vnode on cache hit.
1910 * - cnp: Parameters of the name search. The most interesting bits of
1911 * the cn_flags field have the following meanings:
1912 * - MAKEENTRY: If clear, free an entry from the cache rather than look
1913 * it up.
1914 * - ISDOTDOT: Must be set if and only if cn_nameptr == ".."
1915 * - tsp: Return storage for cache timestamp. On a successful (positive
1916 * or negative) lookup, tsp will be filled with any timespec that
1917 * was stored when this cache entry was created. However, it will
1918 * be clear for "." entries.
1919 * - ticks: Return storage for alternate cache timestamp. On a successful
1920 * (positive or negative) lookup, it will contain the ticks value
1921 * that was current when the cache entry was created, unless cnp
1922 * was ".".
1923 *
1924 * Either both tsp and ticks have to be provided or neither of them.
1925 *
1926 * # Returns
1927 *
1928 * - -1: A positive cache hit. vpp will contain the desired vnode.
1929 * - ENOENT: A negative cache hit, or dvp was recycled out from under us due
1930 * to a forced unmount. vpp will not be modified. If the entry
1931 * is a whiteout, then the ISWHITEOUT flag will be set in
1932 * cnp->cn_flags.
1933 * - 0: A cache miss. vpp will not be modified.
1934 *
1935 * # Locking
1936 *
1937 * On a cache hit, vpp will be returned locked and ref'd. If we're looking up
1938 * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the
1939 * lock is not recursively acquired.
1940 */
1941 static int __noinline
1942 cache_lookup_fallback(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
1943 struct timespec *tsp, int *ticksp)
1944 {
1945 struct namecache *ncp;
1946 struct mtx *blp;
1947 uint32_t hash;
1948 enum vgetstate vs;
1949 int error;
1950 bool whiteout;
1951
1952 MPASS((cnp->cn_flags & ISDOTDOT) == 0);
1953 MPASS((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) != 0);
1954
1955 retry:
1956 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
1957 blp = HASH2BUCKETLOCK(hash);
1958 mtx_lock(blp);
1959
1960 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1961 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
1962 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
1963 break;
1964 }
1965
1966 if (__predict_false(ncp == NULL)) {
1967 mtx_unlock(blp);
1968 SDT_PROBE2(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr);
1969 counter_u64_add(nummiss, 1);
1970 return (0);
1971 }
1972
1973 if (ncp->nc_flag & NCF_NEGATIVE)
1974 goto negative_success;
1975
1976 counter_u64_add(numposhits, 1);
1977 *vpp = ncp->nc_vp;
1978 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp);
1979 cache_out_ts(ncp, tsp, ticksp);
1980 MPASS(dvp != *vpp);
1981 vs = vget_prep(*vpp);
1982 mtx_unlock(blp);
1983 error = vget_finish(*vpp, cnp->cn_lkflags, vs);
1984 if (error) {
1985 *vpp = NULL;
1986 goto retry;
1987 }
1988 return (-1);
1989 negative_success:
1990 /*
1991 * We don't get here with regular lookup apart from corner cases.
1992 */
1993 if (__predict_true(cnp->cn_nameiop == CREATE)) {
1994 if (cnp->cn_flags & ISLASTCN) {
1995 counter_u64_add(numnegzaps, 1);
1996 error = cache_zap_locked_bucket(ncp, cnp, hash, blp);
1997 if (__predict_false(error != 0)) {
1998 zap_bucket_fail2++;
1999 goto retry;
2000 }
2001 cache_free(ncp);
2002 return (0);
2003 }
2004 }
2005
2006 whiteout = (ncp->nc_flag & NCF_WHITE);
2007 cache_out_ts(ncp, tsp, ticksp);
2008 if (cache_neg_hit_prep(ncp))
2009 cache_neg_promote(ncp);
2010 else
2011 cache_neg_hit_finish(ncp);
2012 mtx_unlock(blp);
2013 if (whiteout)
2014 cnp->cn_flags |= ISWHITEOUT;
2015 return (ENOENT);
2016 }
2017
2018 int
2019 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
2020 struct timespec *tsp, int *ticksp)
2021 {
2022 struct namecache *ncp;
2023 uint32_t hash;
2024 enum vgetstate vs;
2025 int error;
2026 bool whiteout, neg_promote;
2027 u_short nc_flag;
2028
2029 MPASS((tsp == NULL && ticksp == NULL) || (tsp != NULL && ticksp != NULL));
2030
2031 #ifdef DEBUG_CACHE
2032 if (__predict_false(!doingcache)) {
2033 cnp->cn_flags &= ~MAKEENTRY;
2034 return (0);
2035 }
2036 #endif
2037
2038 if (__predict_false(cnp->cn_nameptr[0] == '.')) {
2039 if (cnp->cn_namelen == 1)
2040 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp));
2041 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.')
2042 return (cache_lookup_dotdot(dvp, vpp, cnp, tsp, ticksp));
2043 }
2044
2045 MPASS((cnp->cn_flags & ISDOTDOT) == 0);
2046
2047 if ((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) == 0) {
2048 cache_remove_cnp(dvp, cnp);
2049 return (0);
2050 }
2051
2052 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
2053 vfs_smr_enter();
2054
2055 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
2056 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
2057 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
2058 break;
2059 }
2060
2061 if (__predict_false(ncp == NULL)) {
2062 vfs_smr_exit();
2063 SDT_PROBE2(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr);
2064 counter_u64_add(nummiss, 1);
2065 return (0);
2066 }
2067
2068 nc_flag = atomic_load_char(&ncp->nc_flag);
2069 if (nc_flag & NCF_NEGATIVE)
2070 goto negative_success;
2071
2072 counter_u64_add(numposhits, 1);
2073 *vpp = ncp->nc_vp;
2074 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp);
2075 cache_out_ts(ncp, tsp, ticksp);
2076 MPASS(dvp != *vpp);
2077 if (!cache_ncp_canuse(ncp)) {
2078 vfs_smr_exit();
2079 *vpp = NULL;
2080 goto out_fallback;
2081 }
2082 vs = vget_prep_smr(*vpp);
2083 vfs_smr_exit();
2084 if (__predict_false(vs == VGET_NONE)) {
2085 *vpp = NULL;
2086 goto out_fallback;
2087 }
2088 error = vget_finish(*vpp, cnp->cn_lkflags, vs);
2089 if (error) {
2090 *vpp = NULL;
2091 goto out_fallback;
2092 }
2093 return (-1);
2094 negative_success:
2095 if (cnp->cn_nameiop == CREATE) {
2096 if (cnp->cn_flags & ISLASTCN) {
2097 vfs_smr_exit();
2098 goto out_fallback;
2099 }
2100 }
2101
2102 cache_out_ts(ncp, tsp, ticksp);
2103 whiteout = (atomic_load_char(&ncp->nc_flag) & NCF_WHITE);
2104 neg_promote = cache_neg_hit_prep(ncp);
2105 if (!cache_ncp_canuse(ncp)) {
2106 cache_neg_hit_abort(ncp);
2107 vfs_smr_exit();
2108 goto out_fallback;
2109 }
2110 if (neg_promote) {
2111 vfs_smr_exit();
2112 if (!cache_neg_promote_cond(dvp, cnp, ncp, hash))
2113 goto out_fallback;
2114 } else {
2115 cache_neg_hit_finish(ncp);
2116 vfs_smr_exit();
2117 }
2118 if (whiteout)
2119 cnp->cn_flags |= ISWHITEOUT;
2120 return (ENOENT);
2121 out_fallback:
2122 return (cache_lookup_fallback(dvp, vpp, cnp, tsp, ticksp));
2123 }
2124
2125 struct celockstate {
2126 struct mtx *vlp[3];
2127 struct mtx *blp[2];
2128 };
2129 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3));
2130 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2));
2131
2132 static inline void
2133 cache_celockstate_init(struct celockstate *cel)
2134 {
2135
2136 bzero(cel, sizeof(*cel));
2137 }
2138
2139 static void
2140 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp,
2141 struct vnode *dvp)
2142 {
2143 struct mtx *vlp1, *vlp2;
2144
2145 MPASS(cel->vlp[0] == NULL);
2146 MPASS(cel->vlp[1] == NULL);
2147 MPASS(cel->vlp[2] == NULL);
2148
2149 MPASS(vp != NULL || dvp != NULL);
2150
2151 vlp1 = VP2VNODELOCK(vp);
2152 vlp2 = VP2VNODELOCK(dvp);
2153 cache_sort_vnodes(&vlp1, &vlp2);
2154
2155 if (vlp1 != NULL) {
2156 mtx_lock(vlp1);
2157 cel->vlp[0] = vlp1;
2158 }
2159 mtx_lock(vlp2);
2160 cel->vlp[1] = vlp2;
2161 }
2162
2163 static void
2164 cache_unlock_vnodes_cel(struct celockstate *cel)
2165 {
2166
2167 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL);
2168
2169 if (cel->vlp[0] != NULL)
2170 mtx_unlock(cel->vlp[0]);
2171 if (cel->vlp[1] != NULL)
2172 mtx_unlock(cel->vlp[1]);
2173 if (cel->vlp[2] != NULL)
2174 mtx_unlock(cel->vlp[2]);
2175 }
2176
2177 static bool
2178 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp)
2179 {
2180 struct mtx *vlp;
2181 bool ret;
2182
2183 cache_assert_vlp_locked(cel->vlp[0]);
2184 cache_assert_vlp_locked(cel->vlp[1]);
2185 MPASS(cel->vlp[2] == NULL);
2186
2187 MPASS(vp != NULL);
2188 vlp = VP2VNODELOCK(vp);
2189
2190 ret = true;
2191 if (vlp >= cel->vlp[1]) {
2192 mtx_lock(vlp);
2193 } else {
2194 if (mtx_trylock(vlp))
2195 goto out;
2196 cache_lock_vnodes_cel_3_failures++;
2197 cache_unlock_vnodes_cel(cel);
2198 if (vlp < cel->vlp[0]) {
2199 mtx_lock(vlp);
2200 mtx_lock(cel->vlp[0]);
2201 mtx_lock(cel->vlp[1]);
2202 } else {
2203 if (cel->vlp[0] != NULL)
2204 mtx_lock(cel->vlp[0]);
2205 mtx_lock(vlp);
2206 mtx_lock(cel->vlp[1]);
2207 }
2208 ret = false;
2209 }
2210 out:
2211 cel->vlp[2] = vlp;
2212 return (ret);
2213 }
2214
2215 static void
2216 cache_lock_buckets_cel(struct celockstate *cel, struct mtx *blp1,
2217 struct mtx *blp2)
2218 {
2219
2220 MPASS(cel->blp[0] == NULL);
2221 MPASS(cel->blp[1] == NULL);
2222
2223 cache_sort_vnodes(&blp1, &blp2);
2224
2225 if (blp1 != NULL) {
2226 mtx_lock(blp1);
2227 cel->blp[0] = blp1;
2228 }
2229 mtx_lock(blp2);
2230 cel->blp[1] = blp2;
2231 }
2232
2233 static void
2234 cache_unlock_buckets_cel(struct celockstate *cel)
2235 {
2236
2237 if (cel->blp[0] != NULL)
2238 mtx_unlock(cel->blp[0]);
2239 mtx_unlock(cel->blp[1]);
2240 }
2241
2242 /*
2243 * Lock part of the cache affected by the insertion.
2244 *
2245 * This means vnodelocks for dvp, vp and the relevant bucketlock.
2246 * However, insertion can result in removal of an old entry. In this
2247 * case we have an additional vnode and bucketlock pair to lock.
2248 *
2249 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while
2250 * preserving the locking order (smaller address first).
2251 */
2252 static void
2253 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
2254 uint32_t hash)
2255 {
2256 struct namecache *ncp;
2257 struct mtx *blps[2];
2258 u_char nc_flag;
2259
2260 blps[0] = HASH2BUCKETLOCK(hash);
2261 for (;;) {
2262 blps[1] = NULL;
2263 cache_lock_vnodes_cel(cel, dvp, vp);
2264 if (vp == NULL || vp->v_type != VDIR)
2265 break;
2266 ncp = atomic_load_consume_ptr(&vp->v_cache_dd);
2267 if (ncp == NULL)
2268 break;
2269 nc_flag = atomic_load_char(&ncp->nc_flag);
2270 if ((nc_flag & NCF_ISDOTDOT) == 0)
2271 break;
2272 MPASS(ncp->nc_dvp == vp);
2273 blps[1] = NCP2BUCKETLOCK(ncp);
2274 if ((nc_flag & NCF_NEGATIVE) != 0)
2275 break;
2276 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
2277 break;
2278 /*
2279 * All vnodes got re-locked. Re-validate the state and if
2280 * nothing changed we are done. Otherwise restart.
2281 */
2282 if (ncp == vp->v_cache_dd &&
2283 (ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
2284 blps[1] == NCP2BUCKETLOCK(ncp) &&
2285 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
2286 break;
2287 cache_unlock_vnodes_cel(cel);
2288 cel->vlp[0] = NULL;
2289 cel->vlp[1] = NULL;
2290 cel->vlp[2] = NULL;
2291 }
2292 cache_lock_buckets_cel(cel, blps[0], blps[1]);
2293 }
2294
2295 static void
2296 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
2297 uint32_t hash)
2298 {
2299 struct namecache *ncp;
2300 struct mtx *blps[2];
2301 u_char nc_flag;
2302
2303 blps[0] = HASH2BUCKETLOCK(hash);
2304 for (;;) {
2305 blps[1] = NULL;
2306 cache_lock_vnodes_cel(cel, dvp, vp);
2307 ncp = atomic_load_consume_ptr(&dvp->v_cache_dd);
2308 if (ncp == NULL)
2309 break;
2310 nc_flag = atomic_load_char(&ncp->nc_flag);
2311 if ((nc_flag & NCF_ISDOTDOT) == 0)
2312 break;
2313 MPASS(ncp->nc_dvp == dvp);
2314 blps[1] = NCP2BUCKETLOCK(ncp);
2315 if ((nc_flag & NCF_NEGATIVE) != 0)
2316 break;
2317 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
2318 break;
2319 if (ncp == dvp->v_cache_dd &&
2320 (ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
2321 blps[1] == NCP2BUCKETLOCK(ncp) &&
2322 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
2323 break;
2324 cache_unlock_vnodes_cel(cel);
2325 cel->vlp[0] = NULL;
2326 cel->vlp[1] = NULL;
2327 cel->vlp[2] = NULL;
2328 }
2329 cache_lock_buckets_cel(cel, blps[0], blps[1]);
2330 }
2331
2332 static void
2333 cache_enter_unlock(struct celockstate *cel)
2334 {
2335
2336 cache_unlock_buckets_cel(cel);
2337 cache_unlock_vnodes_cel(cel);
2338 }
2339
2340 static void __noinline
2341 cache_enter_dotdot_prep(struct vnode *dvp, struct vnode *vp,
2342 struct componentname *cnp)
2343 {
2344 struct celockstate cel;
2345 struct namecache *ncp;
2346 uint32_t hash;
2347 int len;
2348
2349 if (atomic_load_ptr(&dvp->v_cache_dd) == NULL)
2350 return;
2351 len = cnp->cn_namelen;
2352 cache_celockstate_init(&cel);
2353 hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
2354 cache_enter_lock_dd(&cel, dvp, vp, hash);
2355 ncp = dvp->v_cache_dd;
2356 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT)) {
2357 KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent"));
2358 cache_zap_locked(ncp);
2359 } else {
2360 ncp = NULL;
2361 }
2362 atomic_store_ptr(&dvp->v_cache_dd, NULL);
2363 cache_enter_unlock(&cel);
2364 if (ncp != NULL)
2365 cache_free(ncp);
2366 }
2367
2368 /*
2369 * Add an entry to the cache.
2370 */
2371 void
2372 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
2373 struct timespec *tsp, struct timespec *dtsp)
2374 {
2375 struct celockstate cel;
2376 struct namecache *ncp, *n2, *ndd;
2377 struct namecache_ts *ncp_ts;
2378 struct nchashhead *ncpp;
2379 uint32_t hash;
2380 int flag;
2381 int len;
2382
2383 KASSERT(cnp->cn_namelen <= NAME_MAX,
2384 ("%s: passed len %ld exceeds NAME_MAX (%d)", __func__, cnp->cn_namelen,
2385 NAME_MAX));
2386 VNPASS(!VN_IS_DOOMED(dvp), dvp);
2387 VNPASS(dvp->v_type != VNON, dvp);
2388 if (vp != NULL) {
2389 VNPASS(!VN_IS_DOOMED(vp), vp);
2390 VNPASS(vp->v_type != VNON, vp);
2391 }
2392 if (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') {
2393 KASSERT(dvp == vp,
2394 ("%s: different vnodes for dot entry (%p; %p)\n", __func__,
2395 dvp, vp));
2396 } else {
2397 KASSERT(dvp != vp,
2398 ("%s: same vnode for non-dot entry [%s] (%p)\n", __func__,
2399 cnp->cn_nameptr, dvp));
2400 }
2401
2402 #ifdef DEBUG_CACHE
2403 if (__predict_false(!doingcache))
2404 return;
2405 #endif
2406
2407 flag = 0;
2408 if (__predict_false(cnp->cn_nameptr[0] == '.')) {
2409 if (cnp->cn_namelen == 1)
2410 return;
2411 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
2412 cache_enter_dotdot_prep(dvp, vp, cnp);
2413 flag = NCF_ISDOTDOT;
2414 }
2415 }
2416
2417 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
2418 if (ncp == NULL)
2419 return;
2420
2421 cache_celockstate_init(&cel);
2422 ndd = NULL;
2423 ncp_ts = NULL;
2424
2425 /*
2426 * Calculate the hash key and setup as much of the new
2427 * namecache entry as possible before acquiring the lock.
2428 */
2429 ncp->nc_flag = flag | NCF_WIP;
2430 ncp->nc_vp = vp;
2431 if (vp == NULL)
2432 cache_neg_init(ncp);
2433 ncp->nc_dvp = dvp;
2434 if (tsp != NULL) {
2435 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
2436 ncp_ts->nc_time = *tsp;
2437 ncp_ts->nc_ticks = ticks;
2438 ncp_ts->nc_nc.nc_flag |= NCF_TS;
2439 if (dtsp != NULL) {
2440 ncp_ts->nc_dotdottime = *dtsp;
2441 ncp_ts->nc_nc.nc_flag |= NCF_DTS;
2442 }
2443 }
2444 len = ncp->nc_nlen = cnp->cn_namelen;
2445 hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
2446 memcpy(ncp->nc_name, cnp->cn_nameptr, len);
2447 ncp->nc_name[len] = '\0';
2448 cache_enter_lock(&cel, dvp, vp, hash);
2449
2450 /*
2451 * See if this vnode or negative entry is already in the cache
2452 * with this name. This can happen with concurrent lookups of
2453 * the same path name.
2454 */
2455 ncpp = NCHHASH(hash);
2456 CK_SLIST_FOREACH(n2, ncpp, nc_hash) {
2457 if (n2->nc_dvp == dvp &&
2458 n2->nc_nlen == cnp->cn_namelen &&
2459 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) {
2460 MPASS(cache_ncp_canuse(n2));
2461 if ((n2->nc_flag & NCF_NEGATIVE) != 0)
2462 KASSERT(vp == NULL,
2463 ("%s: found entry pointing to a different vnode (%p != %p) ; name [%s]",
2464 __func__, NULL, vp, cnp->cn_nameptr));
2465 else
2466 KASSERT(n2->nc_vp == vp,
2467 ("%s: found entry pointing to a different vnode (%p != %p) ; name [%s]",
2468 __func__, n2->nc_vp, vp, cnp->cn_nameptr));
2469 /*
2470 * Entries are supposed to be immutable unless in the
2471 * process of getting destroyed. Accommodating for
2472 * changing timestamps is possible but not worth it.
2473 * This should be harmless in terms of correctness, in
2474 * the worst case resulting in an earlier expiration.
2475 * Alternatively, the found entry can be replaced
2476 * altogether.
2477 */
2478 MPASS((n2->nc_flag & (NCF_TS | NCF_DTS)) == (ncp->nc_flag & (NCF_TS | NCF_DTS)));
2479 #if 0
2480 if (tsp != NULL) {
2481 KASSERT((n2->nc_flag & NCF_TS) != 0,
2482 ("no NCF_TS"));
2483 n2_ts = __containerof(n2, struct namecache_ts, nc_nc);
2484 n2_ts->nc_time = ncp_ts->nc_time;
2485 n2_ts->nc_ticks = ncp_ts->nc_ticks;
2486 if (dtsp != NULL) {
2487 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime;
2488 n2_ts->nc_nc.nc_flag |= NCF_DTS;
2489 }
2490 }
2491 #endif
2492 SDT_PROBE3(vfs, namecache, enter, duplicate, dvp, ncp->nc_name,
2493 vp);
2494 goto out_unlock_free;
2495 }
2496 }
2497
2498 if (flag == NCF_ISDOTDOT) {
2499 /*
2500 * See if we are trying to add .. entry, but some other lookup
2501 * has populated v_cache_dd pointer already.
2502 */
2503 if (dvp->v_cache_dd != NULL)
2504 goto out_unlock_free;
2505 KASSERT(vp == NULL || vp->v_type == VDIR,
2506 ("wrong vnode type %p", vp));
2507 atomic_thread_fence_rel();
2508 atomic_store_ptr(&dvp->v_cache_dd, ncp);
2509 }
2510
2511 if (vp != NULL) {
2512 if (flag != NCF_ISDOTDOT) {
2513 /*
2514 * For this case, the cache entry maps both the
2515 * directory name in it and the name ".." for the
2516 * directory's parent.
2517 */
2518 if ((ndd = vp->v_cache_dd) != NULL) {
2519 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0)
2520 cache_zap_locked(ndd);
2521 else
2522 ndd = NULL;
2523 }
2524 atomic_thread_fence_rel();
2525 atomic_store_ptr(&vp->v_cache_dd, ncp);
2526 } else if (vp->v_type != VDIR) {
2527 if (vp->v_cache_dd != NULL) {
2528 atomic_store_ptr(&vp->v_cache_dd, NULL);
2529 }
2530 }
2531 }
2532
2533 if (flag != NCF_ISDOTDOT) {
2534 if (LIST_EMPTY(&dvp->v_cache_src)) {
2535 cache_hold_vnode(dvp);
2536 }
2537 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
2538 }
2539
2540 /*
2541 * If the entry is "negative", we place it into the
2542 * "negative" cache queue, otherwise, we place it into the
2543 * destination vnode's cache entries queue.
2544 */
2545 if (vp != NULL) {
2546 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
2547 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name,
2548 vp);
2549 } else {
2550 if (cnp->cn_flags & ISWHITEOUT)
2551 atomic_store_char(&ncp->nc_flag, ncp->nc_flag | NCF_WHITE);
2552 cache_neg_insert(ncp);
2553 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
2554 ncp->nc_name);
2555 }
2556
2557 /*
2558 * Insert the new namecache entry into the appropriate chain
2559 * within the cache entries table.
2560 */
2561 CK_SLIST_INSERT_HEAD(ncpp, ncp, nc_hash);
2562
2563 atomic_thread_fence_rel();
2564 /*
2565 * Mark the entry as fully constructed.
2566 * It is immutable past this point until its removal.
2567 */
2568 atomic_store_char(&ncp->nc_flag, ncp->nc_flag & ~NCF_WIP);
2569
2570 cache_enter_unlock(&cel);
2571 if (ndd != NULL)
2572 cache_free(ndd);
2573 return;
2574 out_unlock_free:
2575 cache_enter_unlock(&cel);
2576 cache_free(ncp);
2577 return;
2578 }
2579
2580 /*
2581 * A variant of the above accepting flags.
2582 *
2583 * - VFS_CACHE_DROPOLD -- if a conflicting entry is found, drop it.
2584 *
2585 * TODO: this routine is a hack. It blindly removes the old entry, even if it
2586 * happens to match and it is doing it in an inefficient manner. It was added
2587 * to accommodate NFS which runs into a case where the target for a given name
2588 * may change from under it. Note this does nothing to solve the following
2589 * race: 2 callers of cache_enter_time_flags pass a different target vnode for
2590 * the same [dvp, cnp]. It may be argued that code doing this is broken.
2591 */
2592 void
2593 cache_enter_time_flags(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
2594 struct timespec *tsp, struct timespec *dtsp, int flags)
2595 {
2596
2597 MPASS((flags & ~(VFS_CACHE_DROPOLD)) == 0);
2598
2599 if (flags & VFS_CACHE_DROPOLD)
2600 cache_remove_cnp(dvp, cnp);
2601 cache_enter_time(dvp, vp, cnp, tsp, dtsp);
2602 }
2603
2604 static u_int
2605 cache_roundup_2(u_int val)
2606 {
2607 u_int res;
2608
2609 for (res = 1; res <= val; res <<= 1)
2610 continue;
2611
2612 return (res);
2613 }
2614
2615 static struct nchashhead *
2616 nchinittbl(u_long elements, u_long *hashmask)
2617 {
2618 struct nchashhead *hashtbl;
2619 u_long hashsize, i;
2620
2621 hashsize = cache_roundup_2(elements) / 2;
2622
2623 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), M_VFSCACHE, M_WAITOK);
2624 for (i = 0; i < hashsize; i++)
2625 CK_SLIST_INIT(&hashtbl[i]);
2626 *hashmask = hashsize - 1;
2627 return (hashtbl);
2628 }
2629
2630 static void
2631 ncfreetbl(struct nchashhead *hashtbl)
2632 {
2633
2634 free(hashtbl, M_VFSCACHE);
2635 }
2636
2637 /*
2638 * Name cache initialization, from vfs_init() when we are booting
2639 */
2640 static void
2641 nchinit(void *dummy __unused)
2642 {
2643 u_int i;
2644
2645 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL_SIZE,
2646 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT);
2647 cache_zone_small_ts = uma_zcreate("STS VFS Cache", CACHE_ZONE_SMALL_TS_SIZE,
2648 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT);
2649 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE_SIZE,
2650 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT);
2651 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", CACHE_ZONE_LARGE_TS_SIZE,
2652 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT);
2653
2654 VFS_SMR_ZONE_SET(cache_zone_small);
2655 VFS_SMR_ZONE_SET(cache_zone_small_ts);
2656 VFS_SMR_ZONE_SET(cache_zone_large);
2657 VFS_SMR_ZONE_SET(cache_zone_large_ts);
2658
2659 ncsize = desiredvnodes * ncsizefactor;
2660 cache_recalc_neg_min(ncnegminpct);
2661 nchashtbl = nchinittbl(desiredvnodes * 2, &nchash);
2662 ncbuckethash = cache_roundup_2(mp_ncpus * mp_ncpus) - 1;
2663 if (ncbuckethash < 7) /* arbitrarily chosen to avoid having one lock */
2664 ncbuckethash = 7;
2665 if (ncbuckethash > nchash)
2666 ncbuckethash = nchash;
2667 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE,
2668 M_WAITOK | M_ZERO);
2669 for (i = 0; i < numbucketlocks; i++)
2670 mtx_init(&bucketlocks[i], "ncbuc", NULL, MTX_DUPOK | MTX_RECURSE);
2671 ncvnodehash = ncbuckethash;
2672 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE,
2673 M_WAITOK | M_ZERO);
2674 for (i = 0; i < numvnodelocks; i++)
2675 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE);
2676
2677 for (i = 0; i < numneglists; i++) {
2678 mtx_init(&neglists[i].nl_evict_lock, "ncnege", NULL, MTX_DEF);
2679 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF);
2680 TAILQ_INIT(&neglists[i].nl_list);
2681 TAILQ_INIT(&neglists[i].nl_hotlist);
2682 }
2683 }
2684 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
2685
2686 void
2687 cache_vnode_init(struct vnode *vp)
2688 {
2689
2690 LIST_INIT(&vp->v_cache_src);
2691 TAILQ_INIT(&vp->v_cache_dst);
2692 vp->v_cache_dd = NULL;
2693 cache_prehash(vp);
2694 }
2695
2696 /*
2697 * Induce transient cache misses for lockless operation in cache_lookup() by
2698 * using a temporary hash table.
2699 *
2700 * This will force a fs lookup.
2701 *
2702 * Synchronisation is done in 2 steps, calling vfs_smr_synchronize each time
2703 * to observe all CPUs not performing the lookup.
2704 */
2705 static void
2706 cache_changesize_set_temp(struct nchashhead *temptbl, u_long temphash)
2707 {
2708
2709 MPASS(temphash < nchash);
2710 /*
2711 * Change the size. The new size is smaller and can safely be used
2712 * against the existing table. All lookups which now hash wrong will
2713 * result in a cache miss, which all callers are supposed to know how
2714 * to handle.
2715 */
2716 atomic_store_long(&nchash, temphash);
2717 atomic_thread_fence_rel();
2718 vfs_smr_synchronize();
2719 /*
2720 * At this point everyone sees the updated hash value, but they still
2721 * see the old table.
2722 */
2723 atomic_store_ptr(&nchashtbl, temptbl);
2724 atomic_thread_fence_rel();
2725 vfs_smr_synchronize();
2726 /*
2727 * At this point everyone sees the updated table pointer and size pair.
2728 */
2729 }
2730
2731 /*
2732 * Set the new hash table.
2733 *
2734 * Similarly to cache_changesize_set_temp(), this has to synchronize against
2735 * lockless operation in cache_lookup().
2736 */
2737 static void
2738 cache_changesize_set_new(struct nchashhead *new_tbl, u_long new_hash)
2739 {
2740
2741 MPASS(nchash < new_hash);
2742 /*
2743 * Change the pointer first. This wont result in out of bounds access
2744 * since the temporary table is guaranteed to be smaller.
2745 */
2746 atomic_store_ptr(&nchashtbl, new_tbl);
2747 atomic_thread_fence_rel();
2748 vfs_smr_synchronize();
2749 /*
2750 * At this point everyone sees the updated pointer value, but they
2751 * still see the old size.
2752 */
2753 atomic_store_long(&nchash, new_hash);
2754 atomic_thread_fence_rel();
2755 vfs_smr_synchronize();
2756 /*
2757 * At this point everyone sees the updated table pointer and size pair.
2758 */
2759 }
2760
2761 void
2762 cache_changesize(u_long newmaxvnodes)
2763 {
2764 struct nchashhead *new_nchashtbl, *old_nchashtbl, *temptbl;
2765 u_long new_nchash, old_nchash, temphash;
2766 struct namecache *ncp;
2767 uint32_t hash;
2768 u_long newncsize;
2769 int i;
2770
2771 newncsize = newmaxvnodes * ncsizefactor;
2772 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2);
2773 if (newmaxvnodes < numbucketlocks)
2774 newmaxvnodes = numbucketlocks;
2775
2776 new_nchashtbl = nchinittbl(newmaxvnodes, &new_nchash);
2777 /* If same hash table size, nothing to do */
2778 if (nchash == new_nchash) {
2779 ncfreetbl(new_nchashtbl);
2780 return;
2781 }
2782
2783 temptbl = nchinittbl(1, &temphash);
2784
2785 /*
2786 * Move everything from the old hash table to the new table.
2787 * None of the namecache entries in the table can be removed
2788 * because to do so, they have to be removed from the hash table.
2789 */
2790 cache_lock_all_vnodes();
2791 cache_lock_all_buckets();
2792 old_nchashtbl = nchashtbl;
2793 old_nchash = nchash;
2794 cache_changesize_set_temp(temptbl, temphash);
2795 for (i = 0; i <= old_nchash; i++) {
2796 while ((ncp = CK_SLIST_FIRST(&old_nchashtbl[i])) != NULL) {
2797 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen,
2798 ncp->nc_dvp);
2799 CK_SLIST_REMOVE(&old_nchashtbl[i], ncp, namecache, nc_hash);
2800 CK_SLIST_INSERT_HEAD(&new_nchashtbl[hash & new_nchash], ncp, nc_hash);
2801 }
2802 }
2803 ncsize = newncsize;
2804 cache_recalc_neg_min(ncnegminpct);
2805 cache_changesize_set_new(new_nchashtbl, new_nchash);
2806 cache_unlock_all_buckets();
2807 cache_unlock_all_vnodes();
2808 ncfreetbl(old_nchashtbl);
2809 ncfreetbl(temptbl);
2810 }
2811
2812 /*
2813 * Remove all entries from and to a particular vnode.
2814 */
2815 static void
2816 cache_purge_impl(struct vnode *vp)
2817 {
2818 struct cache_freebatch batch;
2819 struct namecache *ncp;
2820 struct mtx *vlp, *vlp2;
2821
2822 TAILQ_INIT(&batch);
2823 vlp = VP2VNODELOCK(vp);
2824 vlp2 = NULL;
2825 mtx_lock(vlp);
2826 retry:
2827 while (!LIST_EMPTY(&vp->v_cache_src)) {
2828 ncp = LIST_FIRST(&vp->v_cache_src);
2829 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
2830 goto retry;
2831 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst);
2832 }
2833 while (!TAILQ_EMPTY(&vp->v_cache_dst)) {
2834 ncp = TAILQ_FIRST(&vp->v_cache_dst);
2835 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
2836 goto retry;
2837 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst);
2838 }
2839 ncp = vp->v_cache_dd;
2840 if (ncp != NULL) {
2841 KASSERT(ncp->nc_flag & NCF_ISDOTDOT,
2842 ("lost dotdot link"));
2843 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
2844 goto retry;
2845 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst);
2846 }
2847 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
2848 mtx_unlock(vlp);
2849 if (vlp2 != NULL)
2850 mtx_unlock(vlp2);
2851 cache_free_batch(&batch);
2852 }
2853
2854 /*
2855 * Opportunistic check to see if there is anything to do.
2856 */
2857 static bool
2858 cache_has_entries(struct vnode *vp)
2859 {
2860
2861 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) &&
2862 atomic_load_ptr(&vp->v_cache_dd) == NULL)
2863 return (false);
2864 return (true);
2865 }
2866
2867 void
2868 cache_purge(struct vnode *vp)
2869 {
2870
2871 SDT_PROBE1(vfs, namecache, purge, done, vp);
2872 if (!cache_has_entries(vp))
2873 return;
2874 cache_purge_impl(vp);
2875 }
2876
2877 /*
2878 * Only to be used by vgone.
2879 */
2880 void
2881 cache_purge_vgone(struct vnode *vp)
2882 {
2883 struct mtx *vlp;
2884
2885 VNPASS(VN_IS_DOOMED(vp), vp);
2886 if (cache_has_entries(vp)) {
2887 cache_purge_impl(vp);
2888 return;
2889 }
2890
2891 /*
2892 * Serialize against a potential thread doing cache_purge.
2893 */
2894 vlp = VP2VNODELOCK(vp);
2895 mtx_wait_unlocked(vlp);
2896 if (cache_has_entries(vp)) {
2897 cache_purge_impl(vp);
2898 return;
2899 }
2900 return;
2901 }
2902
2903 /*
2904 * Remove all negative entries for a particular directory vnode.
2905 */
2906 void
2907 cache_purge_negative(struct vnode *vp)
2908 {
2909 struct cache_freebatch batch;
2910 struct namecache *ncp, *nnp;
2911 struct mtx *vlp;
2912
2913 SDT_PROBE1(vfs, namecache, purge_negative, done, vp);
2914 if (LIST_EMPTY(&vp->v_cache_src))
2915 return;
2916 TAILQ_INIT(&batch);
2917 vlp = VP2VNODELOCK(vp);
2918 mtx_lock(vlp);
2919 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) {
2920 if (!(ncp->nc_flag & NCF_NEGATIVE))
2921 continue;
2922 cache_zap_negative_locked_vnode_kl(ncp, vp);
2923 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst);
2924 }
2925 mtx_unlock(vlp);
2926 cache_free_batch(&batch);
2927 }
2928
2929 /*
2930 * Entry points for modifying VOP operations.
2931 */
2932 void
2933 cache_vop_rename(struct vnode *fdvp, struct vnode *fvp, struct vnode *tdvp,
2934 struct vnode *tvp, struct componentname *fcnp, struct componentname *tcnp)
2935 {
2936
2937 ASSERT_VOP_IN_SEQC(fdvp);
2938 ASSERT_VOP_IN_SEQC(fvp);
2939 ASSERT_VOP_IN_SEQC(tdvp);
2940 if (tvp != NULL)
2941 ASSERT_VOP_IN_SEQC(tvp);
2942
2943 cache_purge(fvp);
2944 if (tvp != NULL) {
2945 cache_purge(tvp);
2946 KASSERT(!cache_remove_cnp(tdvp, tcnp),
2947 ("%s: lingering negative entry", __func__));
2948 } else {
2949 cache_remove_cnp(tdvp, tcnp);
2950 }
2951
2952 /*
2953 * TODO
2954 *
2955 * Historically renaming was always purging all revelang entries,
2956 * but that's quite wasteful. In particular turns out that in many cases
2957 * the target file is immediately accessed after rename, inducing a cache
2958 * miss.
2959 *
2960 * Recode this to reduce relocking and reuse the existing entry (if any)
2961 * instead of just removing it above and allocating a new one here.
2962 */
2963 cache_enter(tdvp, fvp, tcnp);
2964 }
2965
2966 void
2967 cache_vop_rmdir(struct vnode *dvp, struct vnode *vp)
2968 {
2969
2970 ASSERT_VOP_IN_SEQC(dvp);
2971 ASSERT_VOP_IN_SEQC(vp);
2972 cache_purge(vp);
2973 }
2974
2975 #ifdef INVARIANTS
2976 /*
2977 * Validate that if an entry exists it matches.
2978 */
2979 void
2980 cache_validate(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
2981 {
2982 struct namecache *ncp;
2983 struct mtx *blp;
2984 uint32_t hash;
2985
2986 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
2987 if (CK_SLIST_EMPTY(NCHHASH(hash)))
2988 return;
2989 blp = HASH2BUCKETLOCK(hash);
2990 mtx_lock(blp);
2991 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
2992 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
2993 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) {
2994 if (ncp->nc_vp != vp)
2995 panic("%s: mismatch (%p != %p); ncp %p [%s] dvp %p\n",
2996 __func__, vp, ncp->nc_vp, ncp, ncp->nc_name, ncp->nc_dvp);
2997 }
2998 }
2999 mtx_unlock(blp);
3000 }
3001
3002 void
3003 cache_assert_no_entries(struct vnode *vp)
3004 {
3005
3006 VNPASS(TAILQ_EMPTY(&vp->v_cache_dst), vp);
3007 VNPASS(LIST_EMPTY(&vp->v_cache_src), vp);
3008 VNPASS(vp->v_cache_dd == NULL, vp);
3009 }
3010 #endif
3011
3012 /*
3013 * Flush all entries referencing a particular filesystem.
3014 */
3015 void
3016 cache_purgevfs(struct mount *mp)
3017 {
3018 struct vnode *vp, *mvp;
3019 size_t visited, purged;
3020
3021 visited = purged = 0;
3022 /*
3023 * Somewhat wasteful iteration over all vnodes. Would be better to
3024 * support filtering and avoid the interlock to begin with.
3025 */
3026 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
3027 visited++;
3028 if (!cache_has_entries(vp)) {
3029 VI_UNLOCK(vp);
3030 continue;
3031 }
3032 vholdl(vp);
3033 VI_UNLOCK(vp);
3034 cache_purge(vp);
3035 purged++;
3036 vdrop(vp);
3037 }
3038
3039 SDT_PROBE3(vfs, namecache, purgevfs, done, mp, visited, purged);
3040 }
3041
3042 /*
3043 * Perform canonical checks and cache lookup and pass on to filesystem
3044 * through the vop_cachedlookup only if needed.
3045 */
3046
3047 int
3048 vfs_cache_lookup(struct vop_lookup_args *ap)
3049 {
3050 struct vnode *dvp;
3051 int error;
3052 struct vnode **vpp = ap->a_vpp;
3053 struct componentname *cnp = ap->a_cnp;
3054 int flags = cnp->cn_flags;
3055
3056 *vpp = NULL;
3057 dvp = ap->a_dvp;
3058
3059 if (dvp->v_type != VDIR)
3060 return (ENOTDIR);
3061
3062 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
3063 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
3064 return (EROFS);
3065
3066 error = vn_dir_check_exec(dvp, cnp);
3067 if (error != 0)
3068 return (error);
3069
3070 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
3071 if (error == 0)
3072 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
3073 if (error == -1)
3074 return (0);
3075 return (error);
3076 }
3077
3078 /* Implementation of the getcwd syscall. */
3079 int
3080 sys___getcwd(struct thread *td, struct __getcwd_args *uap)
3081 {
3082 char *buf, *retbuf;
3083 size_t buflen;
3084 int error;
3085
3086 buflen = uap->buflen;
3087 if (__predict_false(buflen < 2))
3088 return (EINVAL);
3089 if (buflen > MAXPATHLEN)
3090 buflen = MAXPATHLEN;
3091
3092 buf = uma_zalloc(namei_zone, M_WAITOK);
3093 error = vn_getcwd(buf, &retbuf, &buflen);
3094 if (error == 0)
3095 error = copyout(retbuf, uap->buf, buflen);
3096 uma_zfree(namei_zone, buf);
3097 return (error);
3098 }
3099
3100 int
3101 vn_getcwd(char *buf, char **retbuf, size_t *buflen)
3102 {
3103 struct pwd *pwd;
3104 int error;
3105
3106 vfs_smr_enter();
3107 pwd = pwd_get_smr();
3108 error = vn_fullpath_any_smr(pwd->pwd_cdir, pwd->pwd_rdir, buf, retbuf,
3109 buflen, 0);
3110 VFS_SMR_ASSERT_NOT_ENTERED();
3111 if (error < 0) {
3112 pwd = pwd_hold(curthread);
3113 error = vn_fullpath_any(pwd->pwd_cdir, pwd->pwd_rdir, buf,
3114 retbuf, buflen);
3115 pwd_drop(pwd);
3116 }
3117
3118 #ifdef KTRACE
3119 if (KTRPOINT(curthread, KTR_NAMEI) && error == 0)
3120 ktrnamei(*retbuf);
3121 #endif
3122 return (error);
3123 }
3124
3125 /*
3126 * Canonicalize a path by walking it forward and back.
3127 *
3128 * BUGS:
3129 * - Nothing guarantees the integrity of the entire chain. Consider the case
3130 * where the path "foo/bar/baz/qux" is passed, but "bar" is moved out of
3131 * "foo" into "quux" during the backwards walk. The result will be
3132 * "quux/bar/baz/qux", which could not have been obtained by an incremental
3133 * walk in userspace. Moreover, the path we return is inaccessible if the
3134 * calling thread lacks permission to traverse "quux".
3135 */
3136 static int
3137 kern___realpathat(struct thread *td, int fd, const char *path, char *buf,
3138 size_t size, int flags, enum uio_seg pathseg)
3139 {
3140 struct nameidata nd;
3141 char *retbuf, *freebuf;
3142 int error;
3143
3144 if (flags != 0)
3145 return (EINVAL);
3146 NDINIT_ATRIGHTS(&nd, LOOKUP, FOLLOW | WANTPARENT | AUDITVNODE1,
3147 pathseg, path, fd, &cap_fstat_rights);
3148 if ((error = namei(&nd)) != 0)
3149 return (error);
3150
3151 if (nd.ni_vp->v_type == VREG && nd.ni_dvp->v_type != VDIR &&
3152 (nd.ni_vp->v_vflag & VV_ROOT) != 0) {
3153 /*
3154 * This happens if vp is a file mount. The call to
3155 * vn_fullpath_hardlink can panic if path resolution can't be
3156 * handled without the directory.
3157 *
3158 * To resolve this, we find the vnode which was mounted on -
3159 * this should have a unique global path since we disallow
3160 * mounting on linked files.
3161 */
3162 struct vnode *covered_vp;
3163 error = vn_lock(nd.ni_vp, LK_SHARED);
3164 if (error != 0)
3165 goto out;
3166 covered_vp = nd.ni_vp->v_mount->mnt_vnodecovered;
3167 vref(covered_vp);
3168 VOP_UNLOCK(nd.ni_vp);
3169 error = vn_fullpath(covered_vp, &retbuf, &freebuf);
3170 vrele(covered_vp);
3171 } else {
3172 error = vn_fullpath_hardlink(nd.ni_vp, nd.ni_dvp, nd.ni_cnd.cn_nameptr,
3173 nd.ni_cnd.cn_namelen, &retbuf, &freebuf, &size);
3174 }
3175 if (error == 0) {
3176 error = copyout(retbuf, buf, size);
3177 free(freebuf, M_TEMP);
3178 }
3179 out:
3180 vrele(nd.ni_vp);
3181 vrele(nd.ni_dvp);
3182 NDFREE_PNBUF(&nd);
3183 return (error);
3184 }
3185
3186 int
3187 sys___realpathat(struct thread *td, struct __realpathat_args *uap)
3188 {
3189
3190 return (kern___realpathat(td, uap->fd, uap->path, uap->buf, uap->size,
3191 uap->flags, UIO_USERSPACE));
3192 }
3193
3194 /*
3195 * Retrieve the full filesystem path that correspond to a vnode from the name
3196 * cache (if available)
3197 */
3198 int
3199 vn_fullpath(struct vnode *vp, char **retbuf, char **freebuf)
3200 {
3201 struct pwd *pwd;
3202 char *buf;
3203 size_t buflen;
3204 int error;
3205
3206 if (__predict_false(vp == NULL))
3207 return (EINVAL);
3208
3209 buflen = MAXPATHLEN;
3210 buf = malloc(buflen, M_TEMP, M_WAITOK);
3211 vfs_smr_enter();
3212 pwd = pwd_get_smr();
3213 error = vn_fullpath_any_smr(vp, pwd->pwd_rdir, buf, retbuf, &buflen, 0);
3214 VFS_SMR_ASSERT_NOT_ENTERED();
3215 if (error < 0) {
3216 pwd = pwd_hold(curthread);
3217 error = vn_fullpath_any(vp, pwd->pwd_rdir, buf, retbuf, &buflen);
3218 pwd_drop(pwd);
3219 }
3220 if (error == 0)
3221 *freebuf = buf;
3222 else
3223 free(buf, M_TEMP);
3224 return (error);
3225 }
3226
3227 /*
3228 * This function is similar to vn_fullpath, but it attempts to lookup the
3229 * pathname relative to the global root mount point. This is required for the
3230 * auditing sub-system, as audited pathnames must be absolute, relative to the
3231 * global root mount point.
3232 */
3233 int
3234 vn_fullpath_global(struct vnode *vp, char **retbuf, char **freebuf)
3235 {
3236 char *buf;
3237 size_t buflen;
3238 int error;
3239
3240 if (__predict_false(vp == NULL))
3241 return (EINVAL);
3242 buflen = MAXPATHLEN;
3243 buf = malloc(buflen, M_TEMP, M_WAITOK);
3244 vfs_smr_enter();
3245 error = vn_fullpath_any_smr(vp, rootvnode, buf, retbuf, &buflen, 0);
3246 VFS_SMR_ASSERT_NOT_ENTERED();
3247 if (error < 0) {
3248 error = vn_fullpath_any(vp, rootvnode, buf, retbuf, &buflen);
3249 }
3250 if (error == 0)
3251 *freebuf = buf;
3252 else
3253 free(buf, M_TEMP);
3254 return (error);
3255 }
3256
3257 static struct namecache *
3258 vn_dd_from_dst(struct vnode *vp)
3259 {
3260 struct namecache *ncp;
3261
3262 cache_assert_vnode_locked(vp);
3263 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) {
3264 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
3265 return (ncp);
3266 }
3267 return (NULL);
3268 }
3269
3270 int
3271 vn_vptocnp(struct vnode **vp, char *buf, size_t *buflen)
3272 {
3273 struct vnode *dvp;
3274 struct namecache *ncp;
3275 struct mtx *vlp;
3276 int error;
3277
3278 vlp = VP2VNODELOCK(*vp);
3279 mtx_lock(vlp);
3280 ncp = (*vp)->v_cache_dd;
3281 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT) == 0) {
3282 KASSERT(ncp == vn_dd_from_dst(*vp),
3283 ("%s: mismatch for dd entry (%p != %p)", __func__,
3284 ncp, vn_dd_from_dst(*vp)));
3285 } else {
3286 ncp = vn_dd_from_dst(*vp);
3287 }
3288 if (ncp != NULL) {
3289 if (*buflen < ncp->nc_nlen) {
3290 mtx_unlock(vlp);
3291 vrele(*vp);
3292 counter_u64_add(numfullpathfail4, 1);
3293 error = ENOMEM;
3294 SDT_PROBE3(vfs, namecache, fullpath, return, error,
3295 vp, NULL);
3296 return (error);
3297 }
3298 *buflen -= ncp->nc_nlen;
3299 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen);
3300 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp,
3301 ncp->nc_name, vp);
3302 dvp = *vp;
3303 *vp = ncp->nc_dvp;
3304 vref(*vp);
3305 mtx_unlock(vlp);
3306 vrele(dvp);
3307 return (0);
3308 }
3309 SDT_PROBE1(vfs, namecache, fullpath, miss, vp);
3310
3311 mtx_unlock(vlp);
3312 vn_lock(*vp, LK_SHARED | LK_RETRY);
3313 error = VOP_VPTOCNP(*vp, &dvp, buf, buflen);
3314 vput(*vp);
3315 if (error) {
3316 counter_u64_add(numfullpathfail2, 1);
3317 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
3318 return (error);
3319 }
3320
3321 *vp = dvp;
3322 if (VN_IS_DOOMED(dvp)) {
3323 /* forced unmount */
3324 vrele(dvp);
3325 error = ENOENT;
3326 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
3327 return (error);
3328 }
3329 /*
3330 * *vp has its use count incremented still.
3331 */
3332
3333 return (0);
3334 }
3335
3336 /*
3337 * Resolve a directory to a pathname.
3338 *
3339 * The name of the directory can always be found in the namecache or fetched
3340 * from the filesystem. There is also guaranteed to be only one parent, meaning
3341 * we can just follow vnodes up until we find the root.
3342 *
3343 * The vnode must be referenced.
3344 */
3345 static int
3346 vn_fullpath_dir(struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf,
3347 size_t *len, size_t addend)
3348 {
3349 #ifdef KDTRACE_HOOKS
3350 struct vnode *startvp = vp;
3351 #endif
3352 struct vnode *vp1;
3353 size_t buflen;
3354 int error;
3355 bool slash_prefixed;
3356
3357 VNPASS(vp->v_type == VDIR || VN_IS_DOOMED(vp), vp);
3358 VNPASS(vp->v_usecount > 0, vp);
3359
3360 buflen = *len;
3361
3362 slash_prefixed = true;
3363 if (addend == 0) {
3364 MPASS(*len >= 2);
3365 buflen--;
3366 buf[buflen] = '\0';
3367 slash_prefixed = false;
3368 }
3369
3370 error = 0;
3371
3372 SDT_PROBE1(vfs, namecache, fullpath, entry, vp);
3373 counter_u64_add(numfullpathcalls, 1);
3374 while (vp != rdir && vp != rootvnode) {
3375 /*
3376 * The vp vnode must be already fully constructed,
3377 * since it is either found in namecache or obtained
3378 * from VOP_VPTOCNP(). We may test for VV_ROOT safely
3379 * without obtaining the vnode lock.
3380 */
3381 if ((vp->v_vflag & VV_ROOT) != 0) {
3382 vn_lock(vp, LK_RETRY | LK_SHARED);
3383
3384 /*
3385 * With the vnode locked, check for races with
3386 * unmount, forced or not. Note that we
3387 * already verified that vp is not equal to
3388 * the root vnode, which means that
3389 * mnt_vnodecovered can be NULL only for the
3390 * case of unmount.
3391 */
3392 if (VN_IS_DOOMED(vp) ||
3393 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL ||
3394 vp1->v_mountedhere != vp->v_mount) {
3395 vput(vp);
3396 error = ENOENT;
3397 SDT_PROBE3(vfs, namecache, fullpath, return,
3398 error, vp, NULL);
3399 break;
3400 }
3401
3402 vref(vp1);
3403 vput(vp);
3404 vp = vp1;
3405 continue;
3406 }
3407 if (vp->v_type != VDIR) {
3408 vrele(vp);
3409 counter_u64_add(numfullpathfail1, 1);
3410 error = ENOTDIR;
3411 SDT_PROBE3(vfs, namecache, fullpath, return,
3412 error, vp, NULL);
3413 break;
3414 }
3415 error = vn_vptocnp(&vp, buf, &buflen);
3416 if (error)
3417 break;
3418 if (buflen == 0) {
3419 vrele(vp);
3420 error = ENOMEM;
3421 SDT_PROBE3(vfs, namecache, fullpath, return, error,
3422 startvp, NULL);
3423 break;
3424 }
3425 buf[--buflen] = '/';
3426 slash_prefixed = true;
3427 }
3428 if (error)
3429 return (error);
3430 if (!slash_prefixed) {
3431 if (buflen == 0) {
3432 vrele(vp);
3433 counter_u64_add(numfullpathfail4, 1);
3434 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM,
3435 startvp, NULL);
3436 return (ENOMEM);
3437 }
3438 buf[--buflen] = '/';
3439 }
3440 counter_u64_add(numfullpathfound, 1);
3441 vrele(vp);
3442
3443 *retbuf = buf + buflen;
3444 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, *retbuf);
3445 *len -= buflen;
3446 *len += addend;
3447 return (0);
3448 }
3449
3450 /*
3451 * Resolve an arbitrary vnode to a pathname.
3452 *
3453 * Note 2 caveats:
3454 * - hardlinks are not tracked, thus if the vnode is not a directory this can
3455 * resolve to a different path than the one used to find it
3456 * - namecache is not mandatory, meaning names are not guaranteed to be added
3457 * (in which case resolving fails)
3458 */
3459 static void __inline
3460 cache_rev_failed_impl(int *reason, int line)
3461 {
3462
3463 *reason = line;
3464 }
3465 #define cache_rev_failed(var) cache_rev_failed_impl((var), __LINE__)
3466
3467 static int
3468 vn_fullpath_any_smr(struct vnode *vp, struct vnode *rdir, char *buf,
3469 char **retbuf, size_t *buflen, size_t addend)
3470 {
3471 #ifdef KDTRACE_HOOKS
3472 struct vnode *startvp = vp;
3473 #endif
3474 struct vnode *tvp;
3475 struct mount *mp;
3476 struct namecache *ncp;
3477 size_t orig_buflen;
3478 int reason;
3479 int error;
3480 #ifdef KDTRACE_HOOKS
3481 int i;
3482 #endif
3483 seqc_t vp_seqc, tvp_seqc;
3484 u_char nc_flag;
3485
3486 VFS_SMR_ASSERT_ENTERED();
3487
3488 if (!atomic_load_char(&cache_fast_lookup_enabled)) {
3489 vfs_smr_exit();
3490 return (-1);
3491 }
3492
3493 orig_buflen = *buflen;
3494
3495 if (addend == 0) {
3496 MPASS(*buflen >= 2);
3497 *buflen -= 1;
3498 buf[*buflen] = '\0';
3499 }
3500
3501 if (vp == rdir || vp == rootvnode) {
3502 if (addend == 0) {
3503 *buflen -= 1;
3504 buf[*buflen] = '/';
3505 }
3506 goto out_ok;
3507 }
3508
3509 #ifdef KDTRACE_HOOKS
3510 i = 0;
3511 #endif
3512 error = -1;
3513 ncp = NULL; /* for sdt probe down below */
3514 vp_seqc = vn_seqc_read_any(vp);
3515 if (seqc_in_modify(vp_seqc)) {
3516 cache_rev_failed(&reason);
3517 goto out_abort;
3518 }
3519
3520 for (;;) {
3521 #ifdef KDTRACE_HOOKS
3522 i++;
3523 #endif
3524 if ((vp->v_vflag & VV_ROOT) != 0) {
3525 mp = atomic_load_ptr(&vp->v_mount);
3526 if (mp == NULL) {
3527 cache_rev_failed(&reason);
3528 goto out_abort;
3529 }
3530 tvp = atomic_load_ptr(&mp->mnt_vnodecovered);
3531 tvp_seqc = vn_seqc_read_any(tvp);
3532 if (seqc_in_modify(tvp_seqc)) {
3533 cache_rev_failed(&reason);
3534 goto out_abort;
3535 }
3536 if (!vn_seqc_consistent(vp, vp_seqc)) {
3537 cache_rev_failed(&reason);
3538 goto out_abort;
3539 }
3540 vp = tvp;
3541 vp_seqc = tvp_seqc;
3542 continue;
3543 }
3544 ncp = atomic_load_consume_ptr(&vp->v_cache_dd);
3545 if (ncp == NULL) {
3546 cache_rev_failed(&reason);
3547 goto out_abort;
3548 }
3549 nc_flag = atomic_load_char(&ncp->nc_flag);
3550 if ((nc_flag & NCF_ISDOTDOT) != 0) {
3551 cache_rev_failed(&reason);
3552 goto out_abort;
3553 }
3554 if (ncp->nc_nlen >= *buflen) {
3555 cache_rev_failed(&reason);
3556 error = ENOMEM;
3557 goto out_abort;
3558 }
3559 *buflen -= ncp->nc_nlen;
3560 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen);
3561 *buflen -= 1;
3562 buf[*buflen] = '/';
3563 tvp = ncp->nc_dvp;
3564 tvp_seqc = vn_seqc_read_any(tvp);
3565 if (seqc_in_modify(tvp_seqc)) {
3566 cache_rev_failed(&reason);
3567 goto out_abort;
3568 }
3569 if (!vn_seqc_consistent(vp, vp_seqc)) {
3570 cache_rev_failed(&reason);
3571 goto out_abort;
3572 }
3573 /*
3574 * Acquire fence provided by vn_seqc_read_any above.
3575 */
3576 if (__predict_false(atomic_load_ptr(&vp->v_cache_dd) != ncp)) {
3577 cache_rev_failed(&reason);
3578 goto out_abort;
3579 }
3580 if (!cache_ncp_canuse(ncp)) {
3581 cache_rev_failed(&reason);
3582 goto out_abort;
3583 }
3584 vp = tvp;
3585 vp_seqc = tvp_seqc;
3586 if (vp == rdir || vp == rootvnode)
3587 break;
3588 }
3589 out_ok:
3590 vfs_smr_exit();
3591 *retbuf = buf + *buflen;
3592 *buflen = orig_buflen - *buflen + addend;
3593 SDT_PROBE2(vfs, namecache, fullpath_smr, hit, startvp, *retbuf);
3594 return (0);
3595
3596 out_abort:
3597 *buflen = orig_buflen;
3598 SDT_PROBE4(vfs, namecache, fullpath_smr, miss, startvp, ncp, reason, i);
3599 vfs_smr_exit();
3600 return (error);
3601 }
3602
3603 static int
3604 vn_fullpath_any(struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf,
3605 size_t *buflen)
3606 {
3607 size_t orig_buflen, addend;
3608 int error;
3609
3610 if (*buflen < 2)
3611 return (EINVAL);
3612
3613 orig_buflen = *buflen;
3614
3615 vref(vp);
3616 addend = 0;
3617 if (vp->v_type != VDIR) {
3618 *buflen -= 1;
3619 buf[*buflen] = '\0';
3620 error = vn_vptocnp(&vp, buf, buflen);
3621 if (error)
3622 return (error);
3623 if (*buflen == 0) {
3624 vrele(vp);
3625 return (ENOMEM);
3626 }
3627 *buflen -= 1;
3628 buf[*buflen] = '/';
3629 addend = orig_buflen - *buflen;
3630 }
3631
3632 return (vn_fullpath_dir(vp, rdir, buf, retbuf, buflen, addend));
3633 }
3634
3635 /*
3636 * Resolve an arbitrary vnode to a pathname (taking care of hardlinks).
3637 *
3638 * Since the namecache does not track hardlinks, the caller is expected to
3639 * first look up the target vnode with WANTPARENT flag passed to namei to get
3640 * dvp and vp.
3641 *
3642 * Then we have 2 cases:
3643 * - if the found vnode is a directory, the path can be constructed just by
3644 * following names up the chain
3645 * - otherwise we populate the buffer with the saved name and start resolving
3646 * from the parent
3647 */
3648 int
3649 vn_fullpath_hardlink(struct vnode *vp, struct vnode *dvp,
3650 const char *hrdl_name, size_t hrdl_name_length,
3651 char **retbuf, char **freebuf, size_t *buflen)
3652 {
3653 char *buf, *tmpbuf;
3654 struct pwd *pwd;
3655 size_t addend;
3656 int error;
3657 enum vtype type;
3658
3659 if (*buflen < 2)
3660 return (EINVAL);
3661 if (*buflen > MAXPATHLEN)
3662 *buflen = MAXPATHLEN;
3663
3664 buf = malloc(*buflen, M_TEMP, M_WAITOK);
3665
3666 addend = 0;
3667
3668 /*
3669 * Check for VBAD to work around the vp_crossmp bug in lookup().
3670 *
3671 * For example consider tmpfs on /tmp and realpath /tmp. ni_vp will be
3672 * set to mount point's root vnode while ni_dvp will be vp_crossmp.
3673 * If the type is VDIR (like in this very case) we can skip looking
3674 * at ni_dvp in the first place. However, since vnodes get passed here
3675 * unlocked the target may transition to doomed state (type == VBAD)
3676 * before we get to evaluate the condition. If this happens, we will
3677 * populate part of the buffer and descend to vn_fullpath_dir with
3678 * vp == vp_crossmp. Prevent the problem by checking for VBAD.
3679 *
3680 * This should be atomic_load(&vp->v_type) but it is illegal to take
3681 * an address of a bit field, even if said field is sized to char.
3682 * Work around the problem by reading the value into a full-sized enum
3683 * and then re-reading it with atomic_load which will still prevent
3684 * the compiler from re-reading down the road.
3685 */
3686 type = vp->v_type;
3687 type = atomic_load_int(&type);
3688 if (type == VBAD) {
3689 error = ENOENT;
3690 goto out_bad;
3691 }
3692 if (type != VDIR) {
3693 addend = hrdl_name_length + 2;
3694 if (*buflen < addend) {
3695 error = ENOMEM;
3696 goto out_bad;
3697 }
3698 *buflen -= addend;
3699 tmpbuf = buf + *buflen;
3700 tmpbuf[0] = '/';
3701 memcpy(&tmpbuf[1], hrdl_name, hrdl_name_length);
3702 tmpbuf[addend - 1] = '\0';
3703 vp = dvp;
3704 }
3705
3706 vfs_smr_enter();
3707 pwd = pwd_get_smr();
3708 error = vn_fullpath_any_smr(vp, pwd->pwd_rdir, buf, retbuf, buflen,
3709 addend);
3710 VFS_SMR_ASSERT_NOT_ENTERED();
3711 if (error < 0) {
3712 pwd = pwd_hold(curthread);
3713 vref(vp);
3714 error = vn_fullpath_dir(vp, pwd->pwd_rdir, buf, retbuf, buflen,
3715 addend);
3716 pwd_drop(pwd);
3717 }
3718 if (error != 0)
3719 goto out_bad;
3720
3721 *freebuf = buf;
3722
3723 return (0);
3724 out_bad:
3725 free(buf, M_TEMP);
3726 return (error);
3727 }
3728
3729 struct vnode *
3730 vn_dir_dd_ino(struct vnode *vp)
3731 {
3732 struct namecache *ncp;
3733 struct vnode *ddvp;
3734 struct mtx *vlp;
3735 enum vgetstate vs;
3736
3737 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
3738 vlp = VP2VNODELOCK(vp);
3739 mtx_lock(vlp);
3740 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
3741 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
3742 continue;
3743 ddvp = ncp->nc_dvp;
3744 vs = vget_prep(ddvp);
3745 mtx_unlock(vlp);
3746 if (vget_finish(ddvp, LK_SHARED | LK_NOWAIT, vs))
3747 return (NULL);
3748 return (ddvp);
3749 }
3750 mtx_unlock(vlp);
3751 return (NULL);
3752 }
3753
3754 int
3755 vn_commname(struct vnode *vp, char *buf, u_int buflen)
3756 {
3757 struct namecache *ncp;
3758 struct mtx *vlp;
3759 int l;
3760
3761 vlp = VP2VNODELOCK(vp);
3762 mtx_lock(vlp);
3763 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
3764 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
3765 break;
3766 if (ncp == NULL) {
3767 mtx_unlock(vlp);
3768 return (ENOENT);
3769 }
3770 l = min(ncp->nc_nlen, buflen - 1);
3771 memcpy(buf, ncp->nc_name, l);
3772 mtx_unlock(vlp);
3773 buf[l] = '\0';
3774 return (0);
3775 }
3776
3777 /*
3778 * This function updates path string to vnode's full global path
3779 * and checks the size of the new path string against the pathlen argument.
3780 *
3781 * Requires a locked, referenced vnode.
3782 * Vnode is re-locked on success or ENODEV, otherwise unlocked.
3783 *
3784 * If vp is a directory, the call to vn_fullpath_global() always succeeds
3785 * because it falls back to the ".." lookup if the namecache lookup fails.
3786 */
3787 int
3788 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path,
3789 u_int pathlen)
3790 {
3791 struct nameidata nd;
3792 struct vnode *vp1;
3793 char *rpath, *fbuf;
3794 int error;
3795
3796 ASSERT_VOP_ELOCKED(vp, __func__);
3797
3798 /* Construct global filesystem path from vp. */
3799 VOP_UNLOCK(vp);
3800 error = vn_fullpath_global(vp, &rpath, &fbuf);
3801
3802 if (error != 0) {
3803 vrele(vp);
3804 return (error);
3805 }
3806
3807 if (strlen(rpath) >= pathlen) {
3808 vrele(vp);
3809 error = ENAMETOOLONG;
3810 goto out;
3811 }
3812
3813 /*
3814 * Re-lookup the vnode by path to detect a possible rename.
3815 * As a side effect, the vnode is relocked.
3816 * If vnode was renamed, return ENOENT.
3817 */
3818 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE, path);
3819 error = namei(&nd);
3820 if (error != 0) {
3821 vrele(vp);
3822 goto out;
3823 }
3824 NDFREE_PNBUF(&nd);
3825 vp1 = nd.ni_vp;
3826 vrele(vp);
3827 if (vp1 == vp)
3828 strcpy(path, rpath);
3829 else {
3830 vput(vp1);
3831 error = ENOENT;
3832 }
3833
3834 out:
3835 free(fbuf, M_TEMP);
3836 return (error);
3837 }
3838
3839 /*
3840 * This is similar to vn_path_to_global_path but allows for regular
3841 * files which may not be present in the cache.
3842 *
3843 * Requires a locked, referenced vnode.
3844 * Vnode is re-locked on success or ENODEV, otherwise unlocked.
3845 */
3846 int
3847 vn_path_to_global_path_hardlink(struct thread *td, struct vnode *vp,
3848 struct vnode *dvp, char *path, u_int pathlen, const char *leaf_name,
3849 size_t leaf_length)
3850 {
3851 struct nameidata nd;
3852 struct vnode *vp1;
3853 char *rpath, *fbuf;
3854 size_t len;
3855 int error;
3856
3857 ASSERT_VOP_ELOCKED(vp, __func__);
3858
3859 /*
3860 * Construct global filesystem path from dvp, vp and leaf
3861 * name.
3862 */
3863 VOP_UNLOCK(vp);
3864 error = vn_fullpath_hardlink(vp, dvp, leaf_name, leaf_length,
3865 &rpath, &fbuf, &len);
3866
3867 if (error != 0) {
3868 vrele(vp);
3869 goto out;
3870 }
3871
3872 if (strlen(rpath) >= pathlen) {
3873 vrele(vp);
3874 error = ENAMETOOLONG;
3875 goto out;
3876 }
3877
3878 /*
3879 * Re-lookup the vnode by path to detect a possible rename.
3880 * As a side effect, the vnode is relocked.
3881 * If vnode was renamed, return ENOENT.
3882 */
3883 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE, path);
3884 error = namei(&nd);
3885 if (error != 0) {
3886 vrele(vp);
3887 goto out;
3888 }
3889 NDFREE_PNBUF(&nd);
3890 vp1 = nd.ni_vp;
3891 vrele(vp);
3892 if (vp1 == vp)
3893 strcpy(path, rpath);
3894 else {
3895 vput(vp1);
3896 error = ENOENT;
3897 }
3898
3899 out:
3900 free(fbuf, M_TEMP);
3901 return (error);
3902 }
3903
3904 #ifdef DDB
3905 static void
3906 db_print_vpath(struct vnode *vp)
3907 {
3908
3909 while (vp != NULL) {
3910 db_printf("%p: ", vp);
3911 if (vp == rootvnode) {
3912 db_printf("/");
3913 vp = NULL;
3914 } else {
3915 if (vp->v_vflag & VV_ROOT) {
3916 db_printf("<mount point>");
3917 vp = vp->v_mount->mnt_vnodecovered;
3918 } else {
3919 struct namecache *ncp;
3920 char *ncn;
3921 int i;
3922
3923 ncp = TAILQ_FIRST(&vp->v_cache_dst);
3924 if (ncp != NULL) {
3925 ncn = ncp->nc_name;
3926 for (i = 0; i < ncp->nc_nlen; i++)
3927 db_printf("%c", *ncn++);
3928 vp = ncp->nc_dvp;
3929 } else {
3930 vp = NULL;
3931 }
3932 }
3933 }
3934 db_printf("\n");
3935 }
3936
3937 return;
3938 }
3939
3940 DB_SHOW_COMMAND(vpath, db_show_vpath)
3941 {
3942 struct vnode *vp;
3943
3944 if (!have_addr) {
3945 db_printf("usage: show vpath <struct vnode *>\n");
3946 return;
3947 }
3948
3949 vp = (struct vnode *)addr;
3950 db_print_vpath(vp);
3951 }
3952
3953 #endif
3954
3955 static int cache_fast_lookup = 1;
3956
3957 #define CACHE_FPL_FAILED -2020
3958
3959 void
3960 cache_fast_lookup_enabled_recalc(void)
3961 {
3962 int lookup_flag;
3963 int mac_on;
3964
3965 #ifdef MAC
3966 mac_on = mac_vnode_check_lookup_enabled();
3967 mac_on |= mac_vnode_check_readlink_enabled();
3968 #else
3969 mac_on = 0;
3970 #endif
3971
3972 lookup_flag = atomic_load_int(&cache_fast_lookup);
3973 if (lookup_flag && !mac_on) {
3974 atomic_store_char(&cache_fast_lookup_enabled, true);
3975 } else {
3976 atomic_store_char(&cache_fast_lookup_enabled, false);
3977 }
3978 }
3979
3980 static int
3981 syscal_vfs_cache_fast_lookup(SYSCTL_HANDLER_ARGS)
3982 {
3983 int error, old;
3984
3985 old = atomic_load_int(&cache_fast_lookup);
3986 error = sysctl_handle_int(oidp, arg1, arg2, req);
3987 if (error == 0 && req->newptr && old != atomic_load_int(&cache_fast_lookup))
3988 cache_fast_lookup_enabled_recalc();
3989 return (error);
3990 }
3991 SYSCTL_PROC(_vfs, OID_AUTO, cache_fast_lookup, CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
3992 &cache_fast_lookup, 0, syscal_vfs_cache_fast_lookup, "IU", "");
3993
3994 /*
3995 * Components of nameidata (or objects it can point to) which may
3996 * need restoring in case fast path lookup fails.
3997 */
3998 struct nameidata_outer {
3999 size_t ni_pathlen;
4000 int cn_flags;
4001 };
4002
4003 struct nameidata_saved {
4004 #ifdef INVARIANTS
4005 char *cn_nameptr;
4006 size_t ni_pathlen;
4007 #endif
4008 };
4009
4010 #ifdef INVARIANTS
4011 struct cache_fpl_debug {
4012 size_t ni_pathlen;
4013 };
4014 #endif
4015
4016 struct cache_fpl {
4017 struct nameidata *ndp;
4018 struct componentname *cnp;
4019 char *nulchar;
4020 struct vnode *dvp;
4021 struct vnode *tvp;
4022 seqc_t dvp_seqc;
4023 seqc_t tvp_seqc;
4024 uint32_t hash;
4025 struct nameidata_saved snd;
4026 struct nameidata_outer snd_outer;
4027 int line;
4028 enum cache_fpl_status status:8;
4029 bool in_smr;
4030 bool fsearch;
4031 struct pwd **pwd;
4032 #ifdef INVARIANTS
4033 struct cache_fpl_debug debug;
4034 #endif
4035 };
4036
4037 static bool cache_fplookup_mp_supported(struct mount *mp);
4038 static bool cache_fplookup_is_mp(struct cache_fpl *fpl);
4039 static int cache_fplookup_cross_mount(struct cache_fpl *fpl);
4040 static int cache_fplookup_partial_setup(struct cache_fpl *fpl);
4041 static int cache_fplookup_skip_slashes(struct cache_fpl *fpl);
4042 static int cache_fplookup_trailingslash(struct cache_fpl *fpl);
4043 static void cache_fpl_pathlen_dec(struct cache_fpl *fpl);
4044 static void cache_fpl_pathlen_inc(struct cache_fpl *fpl);
4045 static void cache_fpl_pathlen_add(struct cache_fpl *fpl, size_t n);
4046 static void cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n);
4047
4048 static void
4049 cache_fpl_cleanup_cnp(struct componentname *cnp)
4050 {
4051
4052 uma_zfree(namei_zone, cnp->cn_pnbuf);
4053 cnp->cn_pnbuf = NULL;
4054 cnp->cn_nameptr = NULL;
4055 }
4056
4057 static struct vnode *
4058 cache_fpl_handle_root(struct cache_fpl *fpl)
4059 {
4060 struct nameidata *ndp;
4061 struct componentname *cnp;
4062
4063 ndp = fpl->ndp;
4064 cnp = fpl->cnp;
4065
4066 MPASS(*(cnp->cn_nameptr) == '/');
4067 cnp->cn_nameptr++;
4068 cache_fpl_pathlen_dec(fpl);
4069
4070 if (__predict_false(*(cnp->cn_nameptr) == '/')) {
4071 do {
4072 cnp->cn_nameptr++;
4073 cache_fpl_pathlen_dec(fpl);
4074 } while (*(cnp->cn_nameptr) == '/');
4075 }
4076
4077 return (ndp->ni_rootdir);
4078 }
4079
4080 static void
4081 cache_fpl_checkpoint_outer(struct cache_fpl *fpl)
4082 {
4083
4084 fpl->snd_outer.ni_pathlen = fpl->ndp->ni_pathlen;
4085 fpl->snd_outer.cn_flags = fpl->ndp->ni_cnd.cn_flags;
4086 }
4087
4088 static void
4089 cache_fpl_checkpoint(struct cache_fpl *fpl)
4090 {
4091
4092 #ifdef INVARIANTS
4093 fpl->snd.cn_nameptr = fpl->ndp->ni_cnd.cn_nameptr;
4094 fpl->snd.ni_pathlen = fpl->debug.ni_pathlen;
4095 #endif
4096 }
4097
4098 static void
4099 cache_fpl_restore_partial(struct cache_fpl *fpl)
4100 {
4101
4102 fpl->ndp->ni_cnd.cn_flags = fpl->snd_outer.cn_flags;
4103 #ifdef INVARIANTS
4104 fpl->debug.ni_pathlen = fpl->snd.ni_pathlen;
4105 #endif
4106 }
4107
4108 static void
4109 cache_fpl_restore_abort(struct cache_fpl *fpl)
4110 {
4111
4112 cache_fpl_restore_partial(fpl);
4113 /*
4114 * It is 0 on entry by API contract.
4115 */
4116 fpl->ndp->ni_resflags = 0;
4117 fpl->ndp->ni_cnd.cn_nameptr = fpl->ndp->ni_cnd.cn_pnbuf;
4118 fpl->ndp->ni_pathlen = fpl->snd_outer.ni_pathlen;
4119 }
4120
4121 #ifdef INVARIANTS
4122 #define cache_fpl_smr_assert_entered(fpl) ({ \
4123 struct cache_fpl *_fpl = (fpl); \
4124 MPASS(_fpl->in_smr == true); \
4125 VFS_SMR_ASSERT_ENTERED(); \
4126 })
4127 #define cache_fpl_smr_assert_not_entered(fpl) ({ \
4128 struct cache_fpl *_fpl = (fpl); \
4129 MPASS(_fpl->in_smr == false); \
4130 VFS_SMR_ASSERT_NOT_ENTERED(); \
4131 })
4132 static void
4133 cache_fpl_assert_status(struct cache_fpl *fpl)
4134 {
4135
4136 switch (fpl->status) {
4137 case CACHE_FPL_STATUS_UNSET:
4138 __assert_unreachable();
4139 break;
4140 case CACHE_FPL_STATUS_DESTROYED:
4141 case CACHE_FPL_STATUS_ABORTED:
4142 case CACHE_FPL_STATUS_PARTIAL:
4143 case CACHE_FPL_STATUS_HANDLED:
4144 break;
4145 }
4146 }
4147 #else
4148 #define cache_fpl_smr_assert_entered(fpl) do { } while (0)
4149 #define cache_fpl_smr_assert_not_entered(fpl) do { } while (0)
4150 #define cache_fpl_assert_status(fpl) do { } while (0)
4151 #endif
4152
4153 #define cache_fpl_smr_enter_initial(fpl) ({ \
4154 struct cache_fpl *_fpl = (fpl); \
4155 vfs_smr_enter(); \
4156 _fpl->in_smr = true; \
4157 })
4158
4159 #define cache_fpl_smr_enter(fpl) ({ \
4160 struct cache_fpl *_fpl = (fpl); \
4161 MPASS(_fpl->in_smr == false); \
4162 vfs_smr_enter(); \
4163 _fpl->in_smr = true; \
4164 })
4165
4166 #define cache_fpl_smr_exit(fpl) ({ \
4167 struct cache_fpl *_fpl = (fpl); \
4168 MPASS(_fpl->in_smr == true); \
4169 vfs_smr_exit(); \
4170 _fpl->in_smr = false; \
4171 })
4172
4173 static int
4174 cache_fpl_aborted_early_impl(struct cache_fpl *fpl, int line)
4175 {
4176
4177 if (fpl->status != CACHE_FPL_STATUS_UNSET) {
4178 KASSERT(fpl->status == CACHE_FPL_STATUS_PARTIAL,
4179 ("%s: converting to abort from %d at %d, set at %d\n",
4180 __func__, fpl->status, line, fpl->line));
4181 }
4182 cache_fpl_smr_assert_not_entered(fpl);
4183 fpl->status = CACHE_FPL_STATUS_ABORTED;
4184 fpl->line = line;
4185 return (CACHE_FPL_FAILED);
4186 }
4187
4188 #define cache_fpl_aborted_early(x) cache_fpl_aborted_early_impl((x), __LINE__)
4189
4190 static int __noinline
4191 cache_fpl_aborted_impl(struct cache_fpl *fpl, int line)
4192 {
4193 struct nameidata *ndp;
4194 struct componentname *cnp;
4195
4196 ndp = fpl->ndp;
4197 cnp = fpl->cnp;
4198
4199 if (fpl->status != CACHE_FPL_STATUS_UNSET) {
4200 KASSERT(fpl->status == CACHE_FPL_STATUS_PARTIAL,
4201 ("%s: converting to abort from %d at %d, set at %d\n",
4202 __func__, fpl->status, line, fpl->line));
4203 }
4204 fpl->status = CACHE_FPL_STATUS_ABORTED;
4205 fpl->line = line;
4206 if (fpl->in_smr)
4207 cache_fpl_smr_exit(fpl);
4208 cache_fpl_restore_abort(fpl);
4209 /*
4210 * Resolving symlinks overwrites data passed by the caller.
4211 * Let namei know.
4212 */
4213 if (ndp->ni_loopcnt > 0) {
4214 fpl->status = CACHE_FPL_STATUS_DESTROYED;
4215 cache_fpl_cleanup_cnp(cnp);
4216 }
4217 return (CACHE_FPL_FAILED);
4218 }
4219
4220 #define cache_fpl_aborted(x) cache_fpl_aborted_impl((x), __LINE__)
4221
4222 static int __noinline
4223 cache_fpl_partial_impl(struct cache_fpl *fpl, int line)
4224 {
4225
4226 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET,
4227 ("%s: setting to partial at %d, but already set to %d at %d\n",
4228 __func__, line, fpl->status, fpl->line));
4229 cache_fpl_smr_assert_entered(fpl);
4230 fpl->status = CACHE_FPL_STATUS_PARTIAL;
4231 fpl->line = line;
4232 return (cache_fplookup_partial_setup(fpl));
4233 }
4234
4235 #define cache_fpl_partial(x) cache_fpl_partial_impl((x), __LINE__)
4236
4237 static int
4238 cache_fpl_handled_impl(struct cache_fpl *fpl, int line)
4239 {
4240
4241 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET,
4242 ("%s: setting to handled at %d, but already set to %d at %d\n",
4243 __func__, line, fpl->status, fpl->line));
4244 cache_fpl_smr_assert_not_entered(fpl);
4245 fpl->status = CACHE_FPL_STATUS_HANDLED;
4246 fpl->line = line;
4247 return (0);
4248 }
4249
4250 #define cache_fpl_handled(x) cache_fpl_handled_impl((x), __LINE__)
4251
4252 static int
4253 cache_fpl_handled_error_impl(struct cache_fpl *fpl, int error, int line)
4254 {
4255
4256 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET,
4257 ("%s: setting to handled at %d, but already set to %d at %d\n",
4258 __func__, line, fpl->status, fpl->line));
4259 MPASS(error != 0);
4260 MPASS(error != CACHE_FPL_FAILED);
4261 cache_fpl_smr_assert_not_entered(fpl);
4262 fpl->status = CACHE_FPL_STATUS_HANDLED;
4263 fpl->line = line;
4264 fpl->dvp = NULL;
4265 fpl->tvp = NULL;
4266 return (error);
4267 }
4268
4269 #define cache_fpl_handled_error(x, e) cache_fpl_handled_error_impl((x), (e), __LINE__)
4270
4271 static bool
4272 cache_fpl_terminated(struct cache_fpl *fpl)
4273 {
4274
4275 return (fpl->status != CACHE_FPL_STATUS_UNSET);
4276 }
4277
4278 #define CACHE_FPL_SUPPORTED_CN_FLAGS \
4279 (NC_NOMAKEENTRY | NC_KEEPPOSENTRY | LOCKLEAF | LOCKPARENT | WANTPARENT | \
4280 FAILIFEXISTS | FOLLOW | EMPTYPATH | LOCKSHARED | WILLBEDIR | \
4281 ISOPEN | NOMACCHECK | AUDITVNODE1 | AUDITVNODE2 | NOCAPCHECK | OPENREAD | \
4282 OPENWRITE | WANTIOCTLCAPS)
4283
4284 #define CACHE_FPL_INTERNAL_CN_FLAGS \
4285 (ISDOTDOT | MAKEENTRY | ISLASTCN)
4286
4287 _Static_assert((CACHE_FPL_SUPPORTED_CN_FLAGS & CACHE_FPL_INTERNAL_CN_FLAGS) == 0,
4288 "supported and internal flags overlap");
4289
4290 static bool
4291 cache_fpl_islastcn(struct nameidata *ndp)
4292 {
4293
4294 return (*ndp->ni_next == 0);
4295 }
4296
4297 static bool
4298 cache_fpl_istrailingslash(struct cache_fpl *fpl)
4299 {
4300
4301 MPASS(fpl->nulchar > fpl->cnp->cn_pnbuf);
4302 return (*(fpl->nulchar - 1) == '/');
4303 }
4304
4305 static bool
4306 cache_fpl_isdotdot(struct componentname *cnp)
4307 {
4308
4309 if (cnp->cn_namelen == 2 &&
4310 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
4311 return (true);
4312 return (false);
4313 }
4314
4315 static bool
4316 cache_can_fplookup(struct cache_fpl *fpl)
4317 {
4318 struct nameidata *ndp;
4319 struct componentname *cnp;
4320 struct thread *td;
4321
4322 ndp = fpl->ndp;
4323 cnp = fpl->cnp;
4324 td = curthread;
4325
4326 if (!atomic_load_char(&cache_fast_lookup_enabled)) {
4327 cache_fpl_aborted_early(fpl);
4328 return (false);
4329 }
4330 if ((cnp->cn_flags & ~CACHE_FPL_SUPPORTED_CN_FLAGS) != 0) {
4331 cache_fpl_aborted_early(fpl);
4332 return (false);
4333 }
4334 if (IN_CAPABILITY_MODE(td)) {
4335 cache_fpl_aborted_early(fpl);
4336 return (false);
4337 }
4338 if (AUDITING_TD(td)) {
4339 cache_fpl_aborted_early(fpl);
4340 return (false);
4341 }
4342 if (ndp->ni_startdir != NULL) {
4343 cache_fpl_aborted_early(fpl);
4344 return (false);
4345 }
4346 return (true);
4347 }
4348
4349 static int __noinline
4350 cache_fplookup_dirfd(struct cache_fpl *fpl, struct vnode **vpp)
4351 {
4352 struct nameidata *ndp;
4353 struct componentname *cnp;
4354 int error;
4355 bool fsearch;
4356
4357 ndp = fpl->ndp;
4358 cnp = fpl->cnp;
4359
4360 error = fgetvp_lookup_smr(ndp->ni_dirfd, ndp, vpp, &fsearch);
4361 if (__predict_false(error != 0)) {
4362 return (cache_fpl_aborted(fpl));
4363 }
4364 fpl->fsearch = fsearch;
4365 if ((*vpp)->v_type != VDIR) {
4366 if (!((cnp->cn_flags & EMPTYPATH) != 0 && cnp->cn_pnbuf[0] == '\0')) {
4367 cache_fpl_smr_exit(fpl);
4368 return (cache_fpl_handled_error(fpl, ENOTDIR));
4369 }
4370 }
4371 return (0);
4372 }
4373
4374 static int __noinline
4375 cache_fplookup_negative_promote(struct cache_fpl *fpl, struct namecache *oncp,
4376 uint32_t hash)
4377 {
4378 struct componentname *cnp;
4379 struct vnode *dvp;
4380
4381 cnp = fpl->cnp;
4382 dvp = fpl->dvp;
4383
4384 cache_fpl_smr_exit(fpl);
4385 if (cache_neg_promote_cond(dvp, cnp, oncp, hash))
4386 return (cache_fpl_handled_error(fpl, ENOENT));
4387 else
4388 return (cache_fpl_aborted(fpl));
4389 }
4390
4391 /*
4392 * The target vnode is not supported, prepare for the slow path to take over.
4393 */
4394 static int __noinline
4395 cache_fplookup_partial_setup(struct cache_fpl *fpl)
4396 {
4397 struct nameidata *ndp;
4398 struct componentname *cnp;
4399 enum vgetstate dvs;
4400 struct vnode *dvp;
4401 struct pwd *pwd;
4402 seqc_t dvp_seqc;
4403
4404 ndp = fpl->ndp;
4405 cnp = fpl->cnp;
4406 pwd = *(fpl->pwd);
4407 dvp = fpl->dvp;
4408 dvp_seqc = fpl->dvp_seqc;
4409
4410 if (!pwd_hold_smr(pwd)) {
4411 return (cache_fpl_aborted(fpl));
4412 }
4413
4414 /*
4415 * Note that seqc is checked before the vnode is locked, so by
4416 * the time regular lookup gets to it it may have moved.
4417 *
4418 * Ultimately this does not affect correctness, any lookup errors
4419 * are userspace racing with itself. It is guaranteed that any
4420 * path which ultimately gets found could also have been found
4421 * by regular lookup going all the way in absence of concurrent
4422 * modifications.
4423 */
4424 dvs = vget_prep_smr(dvp);
4425 cache_fpl_smr_exit(fpl);
4426 if (__predict_false(dvs == VGET_NONE)) {
4427 pwd_drop(pwd);
4428 return (cache_fpl_aborted(fpl));
4429 }
4430
4431 vget_finish_ref(dvp, dvs);
4432 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
4433 vrele(dvp);
4434 pwd_drop(pwd);
4435 return (cache_fpl_aborted(fpl));
4436 }
4437
4438 cache_fpl_restore_partial(fpl);
4439 #ifdef INVARIANTS
4440 if (cnp->cn_nameptr != fpl->snd.cn_nameptr) {
4441 panic("%s: cn_nameptr mismatch (%p != %p) full [%s]\n", __func__,
4442 cnp->cn_nameptr, fpl->snd.cn_nameptr, cnp->cn_pnbuf);
4443 }
4444 #endif
4445
4446 ndp->ni_startdir = dvp;
4447 cnp->cn_flags |= MAKEENTRY;
4448 if (cache_fpl_islastcn(ndp))
4449 cnp->cn_flags |= ISLASTCN;
4450 if (cache_fpl_isdotdot(cnp))
4451 cnp->cn_flags |= ISDOTDOT;
4452
4453 /*
4454 * Skip potential extra slashes parsing did not take care of.
4455 * cache_fplookup_skip_slashes explains the mechanism.
4456 */
4457 if (__predict_false(*(cnp->cn_nameptr) == '/')) {
4458 do {
4459 cnp->cn_nameptr++;
4460 cache_fpl_pathlen_dec(fpl);
4461 } while (*(cnp->cn_nameptr) == '/');
4462 }
4463
4464 ndp->ni_pathlen = fpl->nulchar - cnp->cn_nameptr + 1;
4465 #ifdef INVARIANTS
4466 if (ndp->ni_pathlen != fpl->debug.ni_pathlen) {
4467 panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n",
4468 __func__, ndp->ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar,
4469 cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf);
4470 }
4471 #endif
4472 return (0);
4473 }
4474
4475 static int
4476 cache_fplookup_final_child(struct cache_fpl *fpl, enum vgetstate tvs)
4477 {
4478 struct componentname *cnp;
4479 struct vnode *tvp;
4480 seqc_t tvp_seqc;
4481 int error, lkflags;
4482
4483 cnp = fpl->cnp;
4484 tvp = fpl->tvp;
4485 tvp_seqc = fpl->tvp_seqc;
4486
4487 if ((cnp->cn_flags & LOCKLEAF) != 0) {
4488 lkflags = LK_SHARED;
4489 if ((cnp->cn_flags & LOCKSHARED) == 0)
4490 lkflags = LK_EXCLUSIVE;
4491 error = vget_finish(tvp, lkflags, tvs);
4492 if (__predict_false(error != 0)) {
4493 return (cache_fpl_aborted(fpl));
4494 }
4495 } else {
4496 vget_finish_ref(tvp, tvs);
4497 }
4498
4499 if (!vn_seqc_consistent(tvp, tvp_seqc)) {
4500 if ((cnp->cn_flags & LOCKLEAF) != 0)
4501 vput(tvp);
4502 else
4503 vrele(tvp);
4504 return (cache_fpl_aborted(fpl));
4505 }
4506
4507 return (cache_fpl_handled(fpl));
4508 }
4509
4510 /*
4511 * They want to possibly modify the state of the namecache.
4512 */
4513 static int __noinline
4514 cache_fplookup_final_modifying(struct cache_fpl *fpl)
4515 {
4516 struct nameidata *ndp __diagused;
4517 struct componentname *cnp;
4518 enum vgetstate dvs;
4519 struct vnode *dvp, *tvp;
4520 struct mount *mp;
4521 seqc_t dvp_seqc;
4522 int error;
4523 bool docache;
4524
4525 ndp = fpl->ndp;
4526 cnp = fpl->cnp;
4527 dvp = fpl->dvp;
4528 dvp_seqc = fpl->dvp_seqc;
4529
4530 MPASS(*(cnp->cn_nameptr) != '/');
4531 MPASS(cache_fpl_islastcn(ndp));
4532 if ((cnp->cn_flags & LOCKPARENT) == 0)
4533 MPASS((cnp->cn_flags & WANTPARENT) != 0);
4534 MPASS((cnp->cn_flags & TRAILINGSLASH) == 0);
4535 MPASS(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == DELETE ||
4536 cnp->cn_nameiop == RENAME);
4537 MPASS((cnp->cn_flags & MAKEENTRY) == 0);
4538 MPASS((cnp->cn_flags & ISDOTDOT) == 0);
4539
4540 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
4541 if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
4542 docache = false;
4543
4544 /*
4545 * Regular lookup nulifies the slash, which we don't do here.
4546 * Don't take chances with filesystem routines seeing it for
4547 * the last entry.
4548 */
4549 if (cache_fpl_istrailingslash(fpl)) {
4550 return (cache_fpl_partial(fpl));
4551 }
4552
4553 mp = atomic_load_ptr(&dvp->v_mount);
4554 if (__predict_false(mp == NULL)) {
4555 return (cache_fpl_aborted(fpl));
4556 }
4557
4558 if (__predict_false(mp->mnt_flag & MNT_RDONLY)) {
4559 cache_fpl_smr_exit(fpl);
4560 /*
4561 * Original code keeps not checking for CREATE which
4562 * might be a bug. For now let the old lookup decide.
4563 */
4564 if (cnp->cn_nameiop == CREATE) {
4565 return (cache_fpl_aborted(fpl));
4566 }
4567 return (cache_fpl_handled_error(fpl, EROFS));
4568 }
4569
4570 if (fpl->tvp != NULL && (cnp->cn_flags & FAILIFEXISTS) != 0) {
4571 cache_fpl_smr_exit(fpl);
4572 return (cache_fpl_handled_error(fpl, EEXIST));
4573 }
4574
4575 /*
4576 * Secure access to dvp; check cache_fplookup_partial_setup for
4577 * reasoning.
4578 *
4579 * XXX At least UFS requires its lookup routine to be called for
4580 * the last path component, which leads to some level of complication
4581 * and inefficiency:
4582 * - the target routine always locks the target vnode, but our caller
4583 * may not need it locked
4584 * - some of the VOP machinery asserts that the parent is locked, which
4585 * once more may be not required
4586 *
4587 * TODO: add a flag for filesystems which don't need this.
4588 */
4589 dvs = vget_prep_smr(dvp);
4590 cache_fpl_smr_exit(fpl);
4591 if (__predict_false(dvs == VGET_NONE)) {
4592 return (cache_fpl_aborted(fpl));
4593 }
4594
4595 vget_finish_ref(dvp, dvs);
4596 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
4597 vrele(dvp);
4598 return (cache_fpl_aborted(fpl));
4599 }
4600
4601 error = vn_lock(dvp, LK_EXCLUSIVE);
4602 if (__predict_false(error != 0)) {
4603 vrele(dvp);
4604 return (cache_fpl_aborted(fpl));
4605 }
4606
4607 tvp = NULL;
4608 cnp->cn_flags |= ISLASTCN;
4609 if (docache)
4610 cnp->cn_flags |= MAKEENTRY;
4611 if (cache_fpl_isdotdot(cnp))
4612 cnp->cn_flags |= ISDOTDOT;
4613 cnp->cn_lkflags = LK_EXCLUSIVE;
4614 error = VOP_LOOKUP(dvp, &tvp, cnp);
4615 switch (error) {
4616 case EJUSTRETURN:
4617 case 0:
4618 break;
4619 case ENOTDIR:
4620 case ENOENT:
4621 vput(dvp);
4622 return (cache_fpl_handled_error(fpl, error));
4623 default:
4624 vput(dvp);
4625 return (cache_fpl_aborted(fpl));
4626 }
4627
4628 fpl->tvp = tvp;
4629
4630 if (tvp == NULL) {
4631 MPASS(error == EJUSTRETURN);
4632 if ((cnp->cn_flags & LOCKPARENT) == 0) {
4633 VOP_UNLOCK(dvp);
4634 }
4635 return (cache_fpl_handled(fpl));
4636 }
4637
4638 /*
4639 * There are very hairy corner cases concerning various flag combinations
4640 * and locking state. In particular here we only hold one lock instead of
4641 * two.
4642 *
4643 * Skip the complexity as it is of no significance for normal workloads.
4644 */
4645 if (__predict_false(tvp == dvp)) {
4646 vput(dvp);
4647 vrele(tvp);
4648 return (cache_fpl_aborted(fpl));
4649 }
4650
4651 /*
4652 * If they want the symlink itself we are fine, but if they want to
4653 * follow it regular lookup has to be engaged.
4654 */
4655 if (tvp->v_type == VLNK) {
4656 if ((cnp->cn_flags & FOLLOW) != 0) {
4657 vput(dvp);
4658 vput(tvp);
4659 return (cache_fpl_aborted(fpl));
4660 }
4661 }
4662
4663 /*
4664 * Since we expect this to be the terminal vnode it should almost never
4665 * be a mount point.
4666 */
4667 if (__predict_false(cache_fplookup_is_mp(fpl))) {
4668 vput(dvp);
4669 vput(tvp);
4670 return (cache_fpl_aborted(fpl));
4671 }
4672
4673 if ((cnp->cn_flags & FAILIFEXISTS) != 0) {
4674 vput(dvp);
4675 vput(tvp);
4676 return (cache_fpl_handled_error(fpl, EEXIST));
4677 }
4678
4679 if ((cnp->cn_flags & LOCKLEAF) == 0) {
4680 VOP_UNLOCK(tvp);
4681 }
4682
4683 if ((cnp->cn_flags & LOCKPARENT) == 0) {
4684 VOP_UNLOCK(dvp);
4685 }
4686
4687 return (cache_fpl_handled(fpl));
4688 }
4689
4690 static int __noinline
4691 cache_fplookup_modifying(struct cache_fpl *fpl)
4692 {
4693 struct nameidata *ndp;
4694
4695 ndp = fpl->ndp;
4696
4697 if (!cache_fpl_islastcn(ndp)) {
4698 return (cache_fpl_partial(fpl));
4699 }
4700 return (cache_fplookup_final_modifying(fpl));
4701 }
4702
4703 static int __noinline
4704 cache_fplookup_final_withparent(struct cache_fpl *fpl)
4705 {
4706 struct componentname *cnp;
4707 enum vgetstate dvs, tvs;
4708 struct vnode *dvp, *tvp;
4709 seqc_t dvp_seqc;
4710 int error;
4711
4712 cnp = fpl->cnp;
4713 dvp = fpl->dvp;
4714 dvp_seqc = fpl->dvp_seqc;
4715 tvp = fpl->tvp;
4716
4717 MPASS((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0);
4718
4719 /*
4720 * This is less efficient than it can be for simplicity.
4721 */
4722 dvs = vget_prep_smr(dvp);
4723 if (__predict_false(dvs == VGET_NONE)) {
4724 return (cache_fpl_aborted(fpl));
4725 }
4726 tvs = vget_prep_smr(tvp);
4727 if (__predict_false(tvs == VGET_NONE)) {
4728 cache_fpl_smr_exit(fpl);
4729 vget_abort(dvp, dvs);
4730 return (cache_fpl_aborted(fpl));
4731 }
4732
4733 cache_fpl_smr_exit(fpl);
4734
4735 if ((cnp->cn_flags & LOCKPARENT) != 0) {
4736 error = vget_finish(dvp, LK_EXCLUSIVE, dvs);
4737 if (__predict_false(error != 0)) {
4738 vget_abort(tvp, tvs);
4739 return (cache_fpl_aborted(fpl));
4740 }
4741 } else {
4742 vget_finish_ref(dvp, dvs);
4743 }
4744
4745 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
4746 vget_abort(tvp, tvs);
4747 if ((cnp->cn_flags & LOCKPARENT) != 0)
4748 vput(dvp);
4749 else
4750 vrele(dvp);
4751 return (cache_fpl_aborted(fpl));
4752 }
4753
4754 error = cache_fplookup_final_child(fpl, tvs);
4755 if (__predict_false(error != 0)) {
4756 MPASS(fpl->status == CACHE_FPL_STATUS_ABORTED ||
4757 fpl->status == CACHE_FPL_STATUS_DESTROYED);
4758 if ((cnp->cn_flags & LOCKPARENT) != 0)
4759 vput(dvp);
4760 else
4761 vrele(dvp);
4762 return (error);
4763 }
4764
4765 MPASS(fpl->status == CACHE_FPL_STATUS_HANDLED);
4766 return (0);
4767 }
4768
4769 static int
4770 cache_fplookup_final(struct cache_fpl *fpl)
4771 {
4772 struct componentname *cnp;
4773 enum vgetstate tvs;
4774 struct vnode *dvp, *tvp;
4775 seqc_t dvp_seqc;
4776
4777 cnp = fpl->cnp;
4778 dvp = fpl->dvp;
4779 dvp_seqc = fpl->dvp_seqc;
4780 tvp = fpl->tvp;
4781
4782 MPASS(*(cnp->cn_nameptr) != '/');
4783
4784 if (cnp->cn_nameiop != LOOKUP) {
4785 return (cache_fplookup_final_modifying(fpl));
4786 }
4787
4788 if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0)
4789 return (cache_fplookup_final_withparent(fpl));
4790
4791 tvs = vget_prep_smr(tvp);
4792 if (__predict_false(tvs == VGET_NONE)) {
4793 return (cache_fpl_partial(fpl));
4794 }
4795
4796 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
4797 cache_fpl_smr_exit(fpl);
4798 vget_abort(tvp, tvs);
4799 return (cache_fpl_aborted(fpl));
4800 }
4801
4802 cache_fpl_smr_exit(fpl);
4803 return (cache_fplookup_final_child(fpl, tvs));
4804 }
4805
4806 /*
4807 * Comment from locked lookup:
4808 * Check for degenerate name (e.g. / or "") which is a way of talking about a
4809 * directory, e.g. like "/." or ".".
4810 */
4811 static int __noinline
4812 cache_fplookup_degenerate(struct cache_fpl *fpl)
4813 {
4814 struct componentname *cnp;
4815 struct vnode *dvp;
4816 enum vgetstate dvs;
4817 int error, lkflags;
4818 #ifdef INVARIANTS
4819 char *cp;
4820 #endif
4821
4822 fpl->tvp = fpl->dvp;
4823 fpl->tvp_seqc = fpl->dvp_seqc;
4824
4825 cnp = fpl->cnp;
4826 dvp = fpl->dvp;
4827
4828 #ifdef INVARIANTS
4829 for (cp = cnp->cn_pnbuf; *cp != '\0'; cp++) {
4830 KASSERT(*cp == '/',
4831 ("%s: encountered non-slash; string [%s]\n", __func__,
4832 cnp->cn_pnbuf));
4833 }
4834 #endif
4835
4836 if (__predict_false(cnp->cn_nameiop != LOOKUP)) {
4837 cache_fpl_smr_exit(fpl);
4838 return (cache_fpl_handled_error(fpl, EISDIR));
4839 }
4840
4841 if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0) {
4842 return (cache_fplookup_final_withparent(fpl));
4843 }
4844
4845 dvs = vget_prep_smr(dvp);
4846 cache_fpl_smr_exit(fpl);
4847 if (__predict_false(dvs == VGET_NONE)) {
4848 return (cache_fpl_aborted(fpl));
4849 }
4850
4851 if ((cnp->cn_flags & LOCKLEAF) != 0) {
4852 lkflags = LK_SHARED;
4853 if ((cnp->cn_flags & LOCKSHARED) == 0)
4854 lkflags = LK_EXCLUSIVE;
4855 error = vget_finish(dvp, lkflags, dvs);
4856 if (__predict_false(error != 0)) {
4857 return (cache_fpl_aborted(fpl));
4858 }
4859 } else {
4860 vget_finish_ref(dvp, dvs);
4861 }
4862 return (cache_fpl_handled(fpl));
4863 }
4864
4865 static int __noinline
4866 cache_fplookup_emptypath(struct cache_fpl *fpl)
4867 {
4868 struct nameidata *ndp;
4869 struct componentname *cnp;
4870 enum vgetstate tvs;
4871 struct vnode *tvp;
4872 int error, lkflags;
4873
4874 fpl->tvp = fpl->dvp;
4875 fpl->tvp_seqc = fpl->dvp_seqc;
4876
4877 ndp = fpl->ndp;
4878 cnp = fpl->cnp;
4879 tvp = fpl->tvp;
4880
4881 MPASS(*cnp->cn_pnbuf == '\0');
4882
4883 if (__predict_false((cnp->cn_flags & EMPTYPATH) == 0)) {
4884 cache_fpl_smr_exit(fpl);
4885 return (cache_fpl_handled_error(fpl, ENOENT));
4886 }
4887
4888 MPASS((cnp->cn_flags & (LOCKPARENT | WANTPARENT)) == 0);
4889
4890 tvs = vget_prep_smr(tvp);
4891 cache_fpl_smr_exit(fpl);
4892 if (__predict_false(tvs == VGET_NONE)) {
4893 return (cache_fpl_aborted(fpl));
4894 }
4895
4896 if ((cnp->cn_flags & LOCKLEAF) != 0) {
4897 lkflags = LK_SHARED;
4898 if ((cnp->cn_flags & LOCKSHARED) == 0)
4899 lkflags = LK_EXCLUSIVE;
4900 error = vget_finish(tvp, lkflags, tvs);
4901 if (__predict_false(error != 0)) {
4902 return (cache_fpl_aborted(fpl));
4903 }
4904 } else {
4905 vget_finish_ref(tvp, tvs);
4906 }
4907
4908 ndp->ni_resflags |= NIRES_EMPTYPATH;
4909 return (cache_fpl_handled(fpl));
4910 }
4911
4912 static int __noinline
4913 cache_fplookup_noentry(struct cache_fpl *fpl)
4914 {
4915 struct nameidata *ndp;
4916 struct componentname *cnp;
4917 enum vgetstate dvs;
4918 struct vnode *dvp, *tvp;
4919 seqc_t dvp_seqc;
4920 int error;
4921
4922 ndp = fpl->ndp;
4923 cnp = fpl->cnp;
4924 dvp = fpl->dvp;
4925 dvp_seqc = fpl->dvp_seqc;
4926
4927 MPASS((cnp->cn_flags & MAKEENTRY) == 0);
4928 MPASS((cnp->cn_flags & ISDOTDOT) == 0);
4929 if (cnp->cn_nameiop == LOOKUP)
4930 MPASS((cnp->cn_flags & NOCACHE) == 0);
4931 MPASS(!cache_fpl_isdotdot(cnp));
4932
4933 /*
4934 * Hack: delayed name len checking.
4935 */
4936 if (__predict_false(cnp->cn_namelen > NAME_MAX)) {
4937 cache_fpl_smr_exit(fpl);
4938 return (cache_fpl_handled_error(fpl, ENAMETOOLONG));
4939 }
4940
4941 if (cnp->cn_nameptr[0] == '/') {
4942 return (cache_fplookup_skip_slashes(fpl));
4943 }
4944
4945 if (cnp->cn_pnbuf[0] == '\0') {
4946 return (cache_fplookup_emptypath(fpl));
4947 }
4948
4949 if (cnp->cn_nameptr[0] == '\0') {
4950 if (fpl->tvp == NULL) {
4951 return (cache_fplookup_degenerate(fpl));
4952 }
4953 return (cache_fplookup_trailingslash(fpl));
4954 }
4955
4956 if (cnp->cn_nameiop != LOOKUP) {
4957 fpl->tvp = NULL;
4958 return (cache_fplookup_modifying(fpl));
4959 }
4960
4961 /*
4962 * Only try to fill in the component if it is the last one,
4963 * otherwise not only there may be several to handle but the
4964 * walk may be complicated.
4965 */
4966 if (!cache_fpl_islastcn(ndp)) {
4967 return (cache_fpl_partial(fpl));
4968 }
4969
4970 /*
4971 * Regular lookup nulifies the slash, which we don't do here.
4972 * Don't take chances with filesystem routines seeing it for
4973 * the last entry.
4974 */
4975 if (cache_fpl_istrailingslash(fpl)) {
4976 return (cache_fpl_partial(fpl));
4977 }
4978
4979 /*
4980 * Secure access to dvp; check cache_fplookup_partial_setup for
4981 * reasoning.
4982 */
4983 dvs = vget_prep_smr(dvp);
4984 cache_fpl_smr_exit(fpl);
4985 if (__predict_false(dvs == VGET_NONE)) {
4986 return (cache_fpl_aborted(fpl));
4987 }
4988
4989 vget_finish_ref(dvp, dvs);
4990 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
4991 vrele(dvp);
4992 return (cache_fpl_aborted(fpl));
4993 }
4994
4995 error = vn_lock(dvp, LK_SHARED);
4996 if (__predict_false(error != 0)) {
4997 vrele(dvp);
4998 return (cache_fpl_aborted(fpl));
4999 }
5000
5001 tvp = NULL;
5002 /*
5003 * TODO: provide variants which don't require locking either vnode.
5004 */
5005 cnp->cn_flags |= ISLASTCN | MAKEENTRY;
5006 cnp->cn_lkflags = LK_SHARED;
5007 if ((cnp->cn_flags & LOCKSHARED) == 0) {
5008 cnp->cn_lkflags = LK_EXCLUSIVE;
5009 }
5010 error = VOP_LOOKUP(dvp, &tvp, cnp);
5011 switch (error) {
5012 case EJUSTRETURN:
5013 case 0:
5014 break;
5015 case ENOTDIR:
5016 case ENOENT:
5017 vput(dvp);
5018 return (cache_fpl_handled_error(fpl, error));
5019 default:
5020 vput(dvp);
5021 return (cache_fpl_aborted(fpl));
5022 }
5023
5024 fpl->tvp = tvp;
5025
5026 if (tvp == NULL) {
5027 MPASS(error == EJUSTRETURN);
5028 if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) {
5029 vput(dvp);
5030 } else if ((cnp->cn_flags & LOCKPARENT) == 0) {
5031 VOP_UNLOCK(dvp);
5032 }
5033 return (cache_fpl_handled(fpl));
5034 }
5035
5036 if (tvp->v_type == VLNK) {
5037 if ((cnp->cn_flags & FOLLOW) != 0) {
5038 vput(dvp);
5039 vput(tvp);
5040 return (cache_fpl_aborted(fpl));
5041 }
5042 }
5043
5044 if (__predict_false(cache_fplookup_is_mp(fpl))) {
5045 vput(dvp);
5046 vput(tvp);
5047 return (cache_fpl_aborted(fpl));
5048 }
5049
5050 if ((cnp->cn_flags & LOCKLEAF) == 0) {
5051 VOP_UNLOCK(tvp);
5052 }
5053
5054 if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) {
5055 vput(dvp);
5056 } else if ((cnp->cn_flags & LOCKPARENT) == 0) {
5057 VOP_UNLOCK(dvp);
5058 }
5059 return (cache_fpl_handled(fpl));
5060 }
5061
5062 static int __noinline
5063 cache_fplookup_dot(struct cache_fpl *fpl)
5064 {
5065 int error;
5066
5067 MPASS(!seqc_in_modify(fpl->dvp_seqc));
5068 /*
5069 * Just re-assign the value. seqc will be checked later for the first
5070 * non-dot path component in line and/or before deciding to return the
5071 * vnode.
5072 */
5073 fpl->tvp = fpl->dvp;
5074 fpl->tvp_seqc = fpl->dvp_seqc;
5075
5076 counter_u64_add(dothits, 1);
5077 SDT_PROBE3(vfs, namecache, lookup, hit, fpl->dvp, ".", fpl->dvp);
5078
5079 error = 0;
5080 if (cache_fplookup_is_mp(fpl)) {
5081 error = cache_fplookup_cross_mount(fpl);
5082 }
5083 return (error);
5084 }
5085
5086 static int __noinline
5087 cache_fplookup_dotdot(struct cache_fpl *fpl)
5088 {
5089 struct nameidata *ndp;
5090 struct componentname *cnp;
5091 struct namecache *ncp;
5092 struct vnode *dvp;
5093 struct prison *pr;
5094 u_char nc_flag;
5095
5096 ndp = fpl->ndp;
5097 cnp = fpl->cnp;
5098 dvp = fpl->dvp;
5099
5100 MPASS(cache_fpl_isdotdot(cnp));
5101
5102 /*
5103 * XXX this is racy the same way regular lookup is
5104 */
5105 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
5106 pr = pr->pr_parent)
5107 if (dvp == pr->pr_root)
5108 break;
5109
5110 if (dvp == ndp->ni_rootdir ||
5111 dvp == ndp->ni_topdir ||
5112 dvp == rootvnode ||
5113 pr != NULL) {
5114 fpl->tvp = dvp;
5115 fpl->tvp_seqc = vn_seqc_read_any(dvp);
5116 if (seqc_in_modify(fpl->tvp_seqc)) {
5117 return (cache_fpl_aborted(fpl));
5118 }
5119 return (0);
5120 }
5121
5122 if ((dvp->v_vflag & VV_ROOT) != 0) {
5123 /*
5124 * TODO
5125 * The opposite of climb mount is needed here.
5126 */
5127 return (cache_fpl_partial(fpl));
5128 }
5129
5130 ncp = atomic_load_consume_ptr(&dvp->v_cache_dd);
5131 if (ncp == NULL) {
5132 return (cache_fpl_aborted(fpl));
5133 }
5134
5135 nc_flag = atomic_load_char(&ncp->nc_flag);
5136 if ((nc_flag & NCF_ISDOTDOT) != 0) {
5137 if ((nc_flag & NCF_NEGATIVE) != 0)
5138 return (cache_fpl_aborted(fpl));
5139 fpl->tvp = ncp->nc_vp;
5140 } else {
5141 fpl->tvp = ncp->nc_dvp;
5142 }
5143
5144 fpl->tvp_seqc = vn_seqc_read_any(fpl->tvp);
5145 if (seqc_in_modify(fpl->tvp_seqc)) {
5146 return (cache_fpl_partial(fpl));
5147 }
5148
5149 /*
5150 * Acquire fence provided by vn_seqc_read_any above.
5151 */
5152 if (__predict_false(atomic_load_ptr(&dvp->v_cache_dd) != ncp)) {
5153 return (cache_fpl_aborted(fpl));
5154 }
5155
5156 if (!cache_ncp_canuse(ncp)) {
5157 return (cache_fpl_aborted(fpl));
5158 }
5159
5160 counter_u64_add(dotdothits, 1);
5161 return (0);
5162 }
5163
5164 static int __noinline
5165 cache_fplookup_neg(struct cache_fpl *fpl, struct namecache *ncp, uint32_t hash)
5166 {
5167 u_char nc_flag __diagused;
5168 bool neg_promote;
5169
5170 #ifdef INVARIANTS
5171 nc_flag = atomic_load_char(&ncp->nc_flag);
5172 MPASS((nc_flag & NCF_NEGATIVE) != 0);
5173 #endif
5174 /*
5175 * If they want to create an entry we need to replace this one.
5176 */
5177 if (__predict_false(fpl->cnp->cn_nameiop != LOOKUP)) {
5178 fpl->tvp = NULL;
5179 return (cache_fplookup_modifying(fpl));
5180 }
5181 neg_promote = cache_neg_hit_prep(ncp);
5182 if (!cache_fpl_neg_ncp_canuse(ncp)) {
5183 cache_neg_hit_abort(ncp);
5184 return (cache_fpl_partial(fpl));
5185 }
5186 if (neg_promote) {
5187 return (cache_fplookup_negative_promote(fpl, ncp, hash));
5188 }
5189 cache_neg_hit_finish(ncp);
5190 cache_fpl_smr_exit(fpl);
5191 return (cache_fpl_handled_error(fpl, ENOENT));
5192 }
5193
5194 /*
5195 * Resolve a symlink. Called by filesystem-specific routines.
5196 *
5197 * Code flow is:
5198 * ... -> cache_fplookup_symlink -> VOP_FPLOOKUP_SYMLINK -> cache_symlink_resolve
5199 */
5200 int
5201 cache_symlink_resolve(struct cache_fpl *fpl, const char *string, size_t len)
5202 {
5203 struct nameidata *ndp;
5204 struct componentname *cnp;
5205 size_t adjust;
5206
5207 ndp = fpl->ndp;
5208 cnp = fpl->cnp;
5209
5210 if (__predict_false(len == 0)) {
5211 return (ENOENT);
5212 }
5213
5214 if (__predict_false(len > MAXPATHLEN - 2)) {
5215 if (cache_fpl_istrailingslash(fpl)) {
5216 return (EAGAIN);
5217 }
5218 }
5219
5220 ndp->ni_pathlen = fpl->nulchar - cnp->cn_nameptr - cnp->cn_namelen + 1;
5221 #ifdef INVARIANTS
5222 if (ndp->ni_pathlen != fpl->debug.ni_pathlen) {
5223 panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n",
5224 __func__, ndp->ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar,
5225 cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf);
5226 }
5227 #endif
5228
5229 if (__predict_false(len + ndp->ni_pathlen > MAXPATHLEN)) {
5230 return (ENAMETOOLONG);
5231 }
5232
5233 if (__predict_false(ndp->ni_loopcnt++ >= MAXSYMLINKS)) {
5234 return (ELOOP);
5235 }
5236
5237 adjust = len;
5238 if (ndp->ni_pathlen > 1) {
5239 bcopy(ndp->ni_next, cnp->cn_pnbuf + len, ndp->ni_pathlen);
5240 } else {
5241 if (cache_fpl_istrailingslash(fpl)) {
5242 adjust = len + 1;
5243 cnp->cn_pnbuf[len] = '/';
5244 cnp->cn_pnbuf[len + 1] = '\0';
5245 } else {
5246 cnp->cn_pnbuf[len] = '\0';
5247 }
5248 }
5249 bcopy(string, cnp->cn_pnbuf, len);
5250
5251 ndp->ni_pathlen += adjust;
5252 cache_fpl_pathlen_add(fpl, adjust);
5253 cnp->cn_nameptr = cnp->cn_pnbuf;
5254 fpl->nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1];
5255 fpl->tvp = NULL;
5256 return (0);
5257 }
5258
5259 static int __noinline
5260 cache_fplookup_symlink(struct cache_fpl *fpl)
5261 {
5262 struct mount *mp;
5263 struct nameidata *ndp;
5264 struct componentname *cnp;
5265 struct vnode *dvp, *tvp;
5266 int error;
5267
5268 ndp = fpl->ndp;
5269 cnp = fpl->cnp;
5270 dvp = fpl->dvp;
5271 tvp = fpl->tvp;
5272
5273 if (cache_fpl_islastcn(ndp)) {
5274 if ((cnp->cn_flags & FOLLOW) == 0) {
5275 return (cache_fplookup_final(fpl));
5276 }
5277 }
5278
5279 mp = atomic_load_ptr(&dvp->v_mount);
5280 if (__predict_false(mp == NULL)) {
5281 return (cache_fpl_aborted(fpl));
5282 }
5283
5284 /*
5285 * Note this check races against setting the flag just like regular
5286 * lookup.
5287 */
5288 if (__predict_false((mp->mnt_flag & MNT_NOSYMFOLLOW) != 0)) {
5289 cache_fpl_smr_exit(fpl);
5290 return (cache_fpl_handled_error(fpl, EACCES));
5291 }
5292
5293 error = VOP_FPLOOKUP_SYMLINK(tvp, fpl);
5294 if (__predict_false(error != 0)) {
5295 switch (error) {
5296 case EAGAIN:
5297 return (cache_fpl_partial(fpl));
5298 case ENOENT:
5299 case ENAMETOOLONG:
5300 case ELOOP:
5301 cache_fpl_smr_exit(fpl);
5302 return (cache_fpl_handled_error(fpl, error));
5303 default:
5304 return (cache_fpl_aborted(fpl));
5305 }
5306 }
5307
5308 if (*(cnp->cn_nameptr) == '/') {
5309 fpl->dvp = cache_fpl_handle_root(fpl);
5310 fpl->dvp_seqc = vn_seqc_read_any(fpl->dvp);
5311 if (seqc_in_modify(fpl->dvp_seqc)) {
5312 return (cache_fpl_aborted(fpl));
5313 }
5314 /*
5315 * The main loop assumes that ->dvp points to a vnode belonging
5316 * to a filesystem which can do lockless lookup, but the absolute
5317 * symlink can be wandering off to one which does not.
5318 */
5319 mp = atomic_load_ptr(&fpl->dvp->v_mount);
5320 if (__predict_false(mp == NULL)) {
5321 return (cache_fpl_aborted(fpl));
5322 }
5323 if (!cache_fplookup_mp_supported(mp)) {
5324 cache_fpl_checkpoint(fpl);
5325 return (cache_fpl_partial(fpl));
5326 }
5327 }
5328 return (0);
5329 }
5330
5331 static int
5332 cache_fplookup_next(struct cache_fpl *fpl)
5333 {
5334 struct componentname *cnp;
5335 struct namecache *ncp;
5336 struct vnode *dvp, *tvp;
5337 u_char nc_flag;
5338 uint32_t hash;
5339 int error;
5340
5341 cnp = fpl->cnp;
5342 dvp = fpl->dvp;
5343 hash = fpl->hash;
5344
5345 if (__predict_false(cnp->cn_nameptr[0] == '.')) {
5346 if (cnp->cn_namelen == 1) {
5347 return (cache_fplookup_dot(fpl));
5348 }
5349 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
5350 return (cache_fplookup_dotdot(fpl));
5351 }
5352 }
5353
5354 MPASS(!cache_fpl_isdotdot(cnp));
5355
5356 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
5357 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
5358 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
5359 break;
5360 }
5361
5362 if (__predict_false(ncp == NULL)) {
5363 return (cache_fplookup_noentry(fpl));
5364 }
5365
5366 tvp = atomic_load_ptr(&ncp->nc_vp);
5367 nc_flag = atomic_load_char(&ncp->nc_flag);
5368 if ((nc_flag & NCF_NEGATIVE) != 0) {
5369 return (cache_fplookup_neg(fpl, ncp, hash));
5370 }
5371
5372 if (!cache_ncp_canuse(ncp)) {
5373 return (cache_fpl_partial(fpl));
5374 }
5375
5376 fpl->tvp = tvp;
5377 fpl->tvp_seqc = vn_seqc_read_any(tvp);
5378 if (seqc_in_modify(fpl->tvp_seqc)) {
5379 return (cache_fpl_partial(fpl));
5380 }
5381
5382 counter_u64_add(numposhits, 1);
5383 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, tvp);
5384
5385 error = 0;
5386 if (cache_fplookup_is_mp(fpl)) {
5387 error = cache_fplookup_cross_mount(fpl);
5388 }
5389 return (error);
5390 }
5391
5392 static bool
5393 cache_fplookup_mp_supported(struct mount *mp)
5394 {
5395
5396 MPASS(mp != NULL);
5397 if ((mp->mnt_kern_flag & MNTK_FPLOOKUP) == 0)
5398 return (false);
5399 return (true);
5400 }
5401
5402 /*
5403 * Walk up the mount stack (if any).
5404 *
5405 * Correctness is provided in the following ways:
5406 * - all vnodes are protected from freeing with SMR
5407 * - struct mount objects are type stable making them always safe to access
5408 * - stability of the particular mount is provided by busying it
5409 * - relationship between the vnode which is mounted on and the mount is
5410 * verified with the vnode sequence counter after busying
5411 * - association between root vnode of the mount and the mount is protected
5412 * by busy
5413 *
5414 * From that point on we can read the sequence counter of the root vnode
5415 * and get the next mount on the stack (if any) using the same protection.
5416 *
5417 * By the end of successful walk we are guaranteed the reached state was
5418 * indeed present at least at some point which matches the regular lookup.
5419 */
5420 static int __noinline
5421 cache_fplookup_climb_mount(struct cache_fpl *fpl)
5422 {
5423 struct mount *mp, *prev_mp;
5424 struct mount_pcpu *mpcpu, *prev_mpcpu;
5425 struct vnode *vp;
5426 seqc_t vp_seqc;
5427
5428 vp = fpl->tvp;
5429 vp_seqc = fpl->tvp_seqc;
5430
5431 VNPASS(vp->v_type == VDIR || vp->v_type == VREG || vp->v_type == VBAD, vp);
5432 mp = atomic_load_ptr(&vp->v_mountedhere);
5433 if (__predict_false(mp == NULL)) {
5434 return (0);
5435 }
5436
5437 prev_mp = NULL;
5438 for (;;) {
5439 if (!vfs_op_thread_enter_crit(mp, mpcpu)) {
5440 if (prev_mp != NULL)
5441 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu);
5442 return (cache_fpl_partial(fpl));
5443 }
5444 if (prev_mp != NULL)
5445 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu);
5446 if (!vn_seqc_consistent(vp, vp_seqc)) {
5447 vfs_op_thread_exit_crit(mp, mpcpu);
5448 return (cache_fpl_partial(fpl));
5449 }
5450 if (!cache_fplookup_mp_supported(mp)) {
5451 vfs_op_thread_exit_crit(mp, mpcpu);
5452 return (cache_fpl_partial(fpl));
5453 }
5454 vp = atomic_load_ptr(&mp->mnt_rootvnode);
5455 if (vp == NULL) {
5456 vfs_op_thread_exit_crit(mp, mpcpu);
5457 return (cache_fpl_partial(fpl));
5458 }
5459 vp_seqc = vn_seqc_read_any(vp);
5460 if (seqc_in_modify(vp_seqc)) {
5461 vfs_op_thread_exit_crit(mp, mpcpu);
5462 return (cache_fpl_partial(fpl));
5463 }
5464 prev_mp = mp;
5465 prev_mpcpu = mpcpu;
5466 mp = atomic_load_ptr(&vp->v_mountedhere);
5467 if (mp == NULL)
5468 break;
5469 }
5470
5471 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu);
5472 fpl->tvp = vp;
5473 fpl->tvp_seqc = vp_seqc;
5474 return (0);
5475 }
5476
5477 static int __noinline
5478 cache_fplookup_cross_mount(struct cache_fpl *fpl)
5479 {
5480 struct mount *mp;
5481 struct mount_pcpu *mpcpu;
5482 struct vnode *vp;
5483 seqc_t vp_seqc;
5484
5485 vp = fpl->tvp;
5486 vp_seqc = fpl->tvp_seqc;
5487
5488 VNPASS(vp->v_type == VDIR || vp->v_type == VREG || vp->v_type == VBAD, vp);
5489 mp = atomic_load_ptr(&vp->v_mountedhere);
5490 if (__predict_false(mp == NULL)) {
5491 return (0);
5492 }
5493
5494 if (!vfs_op_thread_enter_crit(mp, mpcpu)) {
5495 return (cache_fpl_partial(fpl));
5496 }
5497 if (!vn_seqc_consistent(vp, vp_seqc)) {
5498 vfs_op_thread_exit_crit(mp, mpcpu);
5499 return (cache_fpl_partial(fpl));
5500 }
5501 if (!cache_fplookup_mp_supported(mp)) {
5502 vfs_op_thread_exit_crit(mp, mpcpu);
5503 return (cache_fpl_partial(fpl));
5504 }
5505 vp = atomic_load_ptr(&mp->mnt_rootvnode);
5506 if (__predict_false(vp == NULL)) {
5507 vfs_op_thread_exit_crit(mp, mpcpu);
5508 return (cache_fpl_partial(fpl));
5509 }
5510 vp_seqc = vn_seqc_read_any(vp);
5511 vfs_op_thread_exit_crit(mp, mpcpu);
5512 if (seqc_in_modify(vp_seqc)) {
5513 return (cache_fpl_partial(fpl));
5514 }
5515 mp = atomic_load_ptr(&vp->v_mountedhere);
5516 if (__predict_false(mp != NULL)) {
5517 /*
5518 * There are possibly more mount points on top.
5519 * Normally this does not happen so for simplicity just start
5520 * over.
5521 */
5522 return (cache_fplookup_climb_mount(fpl));
5523 }
5524
5525 fpl->tvp = vp;
5526 fpl->tvp_seqc = vp_seqc;
5527 return (0);
5528 }
5529
5530 /*
5531 * Check if a vnode is mounted on.
5532 */
5533 static bool
5534 cache_fplookup_is_mp(struct cache_fpl *fpl)
5535 {
5536 struct vnode *vp;
5537
5538 vp = fpl->tvp;
5539 return ((vn_irflag_read(vp) & VIRF_MOUNTPOINT) != 0);
5540 }
5541
5542 /*
5543 * Parse the path.
5544 *
5545 * The code was originally copy-pasted from regular lookup and despite
5546 * clean ups leaves performance on the table. Any modifications here
5547 * must take into account that in case off fallback the resulting
5548 * nameidata state has to be compatible with the original.
5549 */
5550
5551 /*
5552 * Debug ni_pathlen tracking.
5553 */
5554 #ifdef INVARIANTS
5555 static void
5556 cache_fpl_pathlen_add(struct cache_fpl *fpl, size_t n)
5557 {
5558
5559 fpl->debug.ni_pathlen += n;
5560 KASSERT(fpl->debug.ni_pathlen <= PATH_MAX,
5561 ("%s: pathlen overflow to %zd\n", __func__, fpl->debug.ni_pathlen));
5562 }
5563
5564 static void
5565 cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n)
5566 {
5567
5568 fpl->debug.ni_pathlen -= n;
5569 KASSERT(fpl->debug.ni_pathlen <= PATH_MAX,
5570 ("%s: pathlen underflow to %zd\n", __func__, fpl->debug.ni_pathlen));
5571 }
5572
5573 static void
5574 cache_fpl_pathlen_inc(struct cache_fpl *fpl)
5575 {
5576
5577 cache_fpl_pathlen_add(fpl, 1);
5578 }
5579
5580 static void
5581 cache_fpl_pathlen_dec(struct cache_fpl *fpl)
5582 {
5583
5584 cache_fpl_pathlen_sub(fpl, 1);
5585 }
5586 #else
5587 static void
5588 cache_fpl_pathlen_add(struct cache_fpl *fpl, size_t n)
5589 {
5590 }
5591
5592 static void
5593 cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n)
5594 {
5595 }
5596
5597 static void
5598 cache_fpl_pathlen_inc(struct cache_fpl *fpl)
5599 {
5600 }
5601
5602 static void
5603 cache_fpl_pathlen_dec(struct cache_fpl *fpl)
5604 {
5605 }
5606 #endif
5607
5608 static void
5609 cache_fplookup_parse(struct cache_fpl *fpl)
5610 {
5611 struct nameidata *ndp;
5612 struct componentname *cnp;
5613 struct vnode *dvp;
5614 char *cp;
5615 uint32_t hash;
5616
5617 ndp = fpl->ndp;
5618 cnp = fpl->cnp;
5619 dvp = fpl->dvp;
5620
5621 /*
5622 * Find the end of this path component, it is either / or nul.
5623 *
5624 * Store / as a temporary sentinel so that we only have one character
5625 * to test for. Pathnames tend to be short so this should not be
5626 * resulting in cache misses.
5627 *
5628 * TODO: fix this to be word-sized.
5629 */
5630 MPASS(&cnp->cn_nameptr[fpl->debug.ni_pathlen - 1] >= cnp->cn_pnbuf);
5631 KASSERT(&cnp->cn_nameptr[fpl->debug.ni_pathlen - 1] == fpl->nulchar,
5632 ("%s: mismatch between pathlen (%zu) and nulchar (%p != %p), string [%s]\n",
5633 __func__, fpl->debug.ni_pathlen, &cnp->cn_nameptr[fpl->debug.ni_pathlen - 1],
5634 fpl->nulchar, cnp->cn_pnbuf));
5635 KASSERT(*fpl->nulchar == '\0',
5636 ("%s: expected nul at %p; string [%s]\n", __func__, fpl->nulchar,
5637 cnp->cn_pnbuf));
5638 hash = cache_get_hash_iter_start(dvp);
5639 *fpl->nulchar = '/';
5640 for (cp = cnp->cn_nameptr; *cp != '/'; cp++) {
5641 KASSERT(*cp != '\0',
5642 ("%s: encountered unexpected nul; string [%s]\n", __func__,
5643 cnp->cn_nameptr));
5644 hash = cache_get_hash_iter(*cp, hash);
5645 continue;
5646 }
5647 *fpl->nulchar = '\0';
5648 fpl->hash = cache_get_hash_iter_finish(hash);
5649
5650 cnp->cn_namelen = cp - cnp->cn_nameptr;
5651 cache_fpl_pathlen_sub(fpl, cnp->cn_namelen);
5652
5653 #ifdef INVARIANTS
5654 /*
5655 * cache_get_hash only accepts lengths up to NAME_MAX. This is fine since
5656 * we are going to fail this lookup with ENAMETOOLONG (see below).
5657 */
5658 if (cnp->cn_namelen <= NAME_MAX) {
5659 if (fpl->hash != cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp)) {
5660 panic("%s: mismatched hash for [%s] len %ld", __func__,
5661 cnp->cn_nameptr, cnp->cn_namelen);
5662 }
5663 }
5664 #endif
5665
5666 /*
5667 * Hack: we have to check if the found path component's length exceeds
5668 * NAME_MAX. However, the condition is very rarely true and check can
5669 * be elided in the common case -- if an entry was found in the cache,
5670 * then it could not have been too long to begin with.
5671 */
5672 ndp->ni_next = cp;
5673 }
5674
5675 static void
5676 cache_fplookup_parse_advance(struct cache_fpl *fpl)
5677 {
5678 struct nameidata *ndp;
5679 struct componentname *cnp;
5680
5681 ndp = fpl->ndp;
5682 cnp = fpl->cnp;
5683
5684 cnp->cn_nameptr = ndp->ni_next;
5685 KASSERT(*(cnp->cn_nameptr) == '/',
5686 ("%s: should have seen slash at %p ; buf %p [%s]\n", __func__,
5687 cnp->cn_nameptr, cnp->cn_pnbuf, cnp->cn_pnbuf));
5688 cnp->cn_nameptr++;
5689 cache_fpl_pathlen_dec(fpl);
5690 }
5691
5692 /*
5693 * Skip spurious slashes in a pathname (e.g., "foo///bar") and retry.
5694 *
5695 * Lockless lookup tries to elide checking for spurious slashes and should they
5696 * be present is guaranteed to fail to find an entry. In this case the caller
5697 * must check if the name starts with a slash and call this routine. It is
5698 * going to fast forward across the spurious slashes and set the state up for
5699 * retry.
5700 */
5701 static int __noinline
5702 cache_fplookup_skip_slashes(struct cache_fpl *fpl)
5703 {
5704 struct nameidata *ndp;
5705 struct componentname *cnp;
5706
5707 ndp = fpl->ndp;
5708 cnp = fpl->cnp;
5709
5710 MPASS(*(cnp->cn_nameptr) == '/');
5711 do {
5712 cnp->cn_nameptr++;
5713 cache_fpl_pathlen_dec(fpl);
5714 } while (*(cnp->cn_nameptr) == '/');
5715
5716 /*
5717 * Go back to one slash so that cache_fplookup_parse_advance has
5718 * something to skip.
5719 */
5720 cnp->cn_nameptr--;
5721 cache_fpl_pathlen_inc(fpl);
5722
5723 /*
5724 * cache_fplookup_parse_advance starts from ndp->ni_next
5725 */
5726 ndp->ni_next = cnp->cn_nameptr;
5727
5728 /*
5729 * See cache_fplookup_dot.
5730 */
5731 fpl->tvp = fpl->dvp;
5732 fpl->tvp_seqc = fpl->dvp_seqc;
5733
5734 return (0);
5735 }
5736
5737 /*
5738 * Handle trailing slashes (e.g., "foo/").
5739 *
5740 * If a trailing slash is found the terminal vnode must be a directory.
5741 * Regular lookup shortens the path by nulifying the first trailing slash and
5742 * sets the TRAILINGSLASH flag to denote this took place. There are several
5743 * checks on it performed later.
5744 *
5745 * Similarly to spurious slashes, lockless lookup handles this in a speculative
5746 * manner relying on an invariant that a non-directory vnode will get a miss.
5747 * In this case cn_nameptr[0] == '\0' and cn_namelen == 0.
5748 *
5749 * Thus for a path like "foo/bar/" the code unwinds the state back to "bar/"
5750 * and denotes this is the last path component, which avoids looping back.
5751 *
5752 * Only plain lookups are supported for now to restrict corner cases to handle.
5753 */
5754 static int __noinline
5755 cache_fplookup_trailingslash(struct cache_fpl *fpl)
5756 {
5757 #ifdef INVARIANTS
5758 size_t ni_pathlen;
5759 #endif
5760 struct nameidata *ndp;
5761 struct componentname *cnp;
5762 struct namecache *ncp;
5763 struct vnode *tvp;
5764 char *cn_nameptr_orig, *cn_nameptr_slash;
5765 seqc_t tvp_seqc;
5766 u_char nc_flag;
5767
5768 ndp = fpl->ndp;
5769 cnp = fpl->cnp;
5770 tvp = fpl->tvp;
5771 tvp_seqc = fpl->tvp_seqc;
5772
5773 MPASS(fpl->dvp == fpl->tvp);
5774 KASSERT(cache_fpl_istrailingslash(fpl),
5775 ("%s: expected trailing slash at %p; string [%s]\n", __func__, fpl->nulchar - 1,
5776 cnp->cn_pnbuf));
5777 KASSERT(cnp->cn_nameptr[0] == '\0',
5778 ("%s: expected nul char at %p; string [%s]\n", __func__, &cnp->cn_nameptr[0],
5779 cnp->cn_pnbuf));
5780 KASSERT(cnp->cn_namelen == 0,
5781 ("%s: namelen 0 but got %ld; string [%s]\n", __func__, cnp->cn_namelen,
5782 cnp->cn_pnbuf));
5783 MPASS(cnp->cn_nameptr > cnp->cn_pnbuf);
5784
5785 if (cnp->cn_nameiop != LOOKUP) {
5786 return (cache_fpl_aborted(fpl));
5787 }
5788
5789 if (__predict_false(tvp->v_type != VDIR)) {
5790 if (!vn_seqc_consistent(tvp, tvp_seqc)) {
5791 return (cache_fpl_aborted(fpl));
5792 }
5793 cache_fpl_smr_exit(fpl);
5794 return (cache_fpl_handled_error(fpl, ENOTDIR));
5795 }
5796
5797 /*
5798 * Denote the last component.
5799 */
5800 ndp->ni_next = &cnp->cn_nameptr[0];
5801 MPASS(cache_fpl_islastcn(ndp));
5802
5803 /*
5804 * Unwind trailing slashes.
5805 */
5806 cn_nameptr_orig = cnp->cn_nameptr;
5807 while (cnp->cn_nameptr >= cnp->cn_pnbuf) {
5808 cnp->cn_nameptr--;
5809 if (cnp->cn_nameptr[0] != '/') {
5810 break;
5811 }
5812 }
5813
5814 /*
5815 * Unwind to the beginning of the path component.
5816 *
5817 * Note the path may or may not have started with a slash.
5818 */
5819 cn_nameptr_slash = cnp->cn_nameptr;
5820 while (cnp->cn_nameptr > cnp->cn_pnbuf) {
5821 cnp->cn_nameptr--;
5822 if (cnp->cn_nameptr[0] == '/') {
5823 break;
5824 }
5825 }
5826 if (cnp->cn_nameptr[0] == '/') {
5827 cnp->cn_nameptr++;
5828 }
5829
5830 cnp->cn_namelen = cn_nameptr_slash - cnp->cn_nameptr + 1;
5831 cache_fpl_pathlen_add(fpl, cn_nameptr_orig - cnp->cn_nameptr);
5832 cache_fpl_checkpoint(fpl);
5833
5834 #ifdef INVARIANTS
5835 ni_pathlen = fpl->nulchar - cnp->cn_nameptr + 1;
5836 if (ni_pathlen != fpl->debug.ni_pathlen) {
5837 panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n",
5838 __func__, ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar,
5839 cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf);
5840 }
5841 #endif
5842
5843 /*
5844 * If this was a "./" lookup the parent directory is already correct.
5845 */
5846 if (cnp->cn_nameptr[0] == '.' && cnp->cn_namelen == 1) {
5847 return (0);
5848 }
5849
5850 /*
5851 * Otherwise we need to look it up.
5852 */
5853 tvp = fpl->tvp;
5854 ncp = atomic_load_consume_ptr(&tvp->v_cache_dd);
5855 if (__predict_false(ncp == NULL)) {
5856 return (cache_fpl_aborted(fpl));
5857 }
5858 nc_flag = atomic_load_char(&ncp->nc_flag);
5859 if ((nc_flag & NCF_ISDOTDOT) != 0) {
5860 return (cache_fpl_aborted(fpl));
5861 }
5862 fpl->dvp = ncp->nc_dvp;
5863 fpl->dvp_seqc = vn_seqc_read_any(fpl->dvp);
5864 if (seqc_in_modify(fpl->dvp_seqc)) {
5865 return (cache_fpl_aborted(fpl));
5866 }
5867 return (0);
5868 }
5869
5870 /*
5871 * See the API contract for VOP_FPLOOKUP_VEXEC.
5872 */
5873 static int __noinline
5874 cache_fplookup_failed_vexec(struct cache_fpl *fpl, int error)
5875 {
5876 struct componentname *cnp;
5877 struct vnode *dvp;
5878 seqc_t dvp_seqc;
5879
5880 cnp = fpl->cnp;
5881 dvp = fpl->dvp;
5882 dvp_seqc = fpl->dvp_seqc;
5883
5884 /*
5885 * Hack: delayed empty path checking.
5886 */
5887 if (cnp->cn_pnbuf[0] == '\0') {
5888 return (cache_fplookup_emptypath(fpl));
5889 }
5890
5891 /*
5892 * TODO: Due to ignoring trailing slashes lookup will perform a
5893 * permission check on the last dir when it should not be doing it. It
5894 * may fail, but said failure should be ignored. It is possible to fix
5895 * it up fully without resorting to regular lookup, but for now just
5896 * abort.
5897 */
5898 if (cache_fpl_istrailingslash(fpl)) {
5899 return (cache_fpl_aborted(fpl));
5900 }
5901
5902 /*
5903 * Hack: delayed degenerate path checking.
5904 */
5905 if (cnp->cn_nameptr[0] == '\0' && fpl->tvp == NULL) {
5906 return (cache_fplookup_degenerate(fpl));
5907 }
5908
5909 /*
5910 * Hack: delayed name len checking.
5911 */
5912 if (__predict_false(cnp->cn_namelen > NAME_MAX)) {
5913 cache_fpl_smr_exit(fpl);
5914 return (cache_fpl_handled_error(fpl, ENAMETOOLONG));
5915 }
5916
5917 /*
5918 * Hack: they may be looking up foo/bar, where foo is not a directory.
5919 * In such a case we need to return ENOTDIR, but we may happen to get
5920 * here with a different error.
5921 */
5922 if (dvp->v_type != VDIR) {
5923 error = ENOTDIR;
5924 }
5925
5926 /*
5927 * Hack: handle O_SEARCH.
5928 *
5929 * Open Group Base Specifications Issue 7, 2018 edition states:
5930 * <quote>
5931 * If the access mode of the open file description associated with the
5932 * file descriptor is not O_SEARCH, the function shall check whether
5933 * directory searches are permitted using the current permissions of
5934 * the directory underlying the file descriptor. If the access mode is
5935 * O_SEARCH, the function shall not perform the check.
5936 * </quote>
5937 *
5938 * Regular lookup tests for the NOEXECCHECK flag for every path
5939 * component to decide whether to do the permission check. However,
5940 * since most lookups never have the flag (and when they do it is only
5941 * present for the first path component), lockless lookup only acts on
5942 * it if there is a permission problem. Here the flag is represented
5943 * with a boolean so that we don't have to clear it on the way out.
5944 *
5945 * For simplicity this always aborts.
5946 * TODO: check if this is the first lookup and ignore the permission
5947 * problem. Note the flag has to survive fallback (if it happens to be
5948 * performed).
5949 */
5950 if (fpl->fsearch) {
5951 return (cache_fpl_aborted(fpl));
5952 }
5953
5954 switch (error) {
5955 case EAGAIN:
5956 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
5957 error = cache_fpl_aborted(fpl);
5958 } else {
5959 cache_fpl_partial(fpl);
5960 }
5961 break;
5962 default:
5963 if (!vn_seqc_consistent(dvp, dvp_seqc)) {
5964 error = cache_fpl_aborted(fpl);
5965 } else {
5966 cache_fpl_smr_exit(fpl);
5967 cache_fpl_handled_error(fpl, error);
5968 }
5969 break;
5970 }
5971 return (error);
5972 }
5973
5974 static int
5975 cache_fplookup_impl(struct vnode *dvp, struct cache_fpl *fpl)
5976 {
5977 struct nameidata *ndp;
5978 struct componentname *cnp;
5979 struct mount *mp;
5980 int error;
5981
5982 ndp = fpl->ndp;
5983 cnp = fpl->cnp;
5984
5985 cache_fpl_checkpoint(fpl);
5986
5987 /*
5988 * The vnode at hand is almost always stable, skip checking for it.
5989 * Worst case this postpones the check towards the end of the iteration
5990 * of the main loop.
5991 */
5992 fpl->dvp = dvp;
5993 fpl->dvp_seqc = vn_seqc_read_notmodify(fpl->dvp);
5994
5995 mp = atomic_load_ptr(&dvp->v_mount);
5996 if (__predict_false(mp == NULL || !cache_fplookup_mp_supported(mp))) {
5997 return (cache_fpl_aborted(fpl));
5998 }
5999
6000 MPASS(fpl->tvp == NULL);
6001
6002 for (;;) {
6003 cache_fplookup_parse(fpl);
6004
6005 error = VOP_FPLOOKUP_VEXEC(fpl->dvp, cnp->cn_cred);
6006 if (__predict_false(error != 0)) {
6007 error = cache_fplookup_failed_vexec(fpl, error);
6008 break;
6009 }
6010
6011 error = cache_fplookup_next(fpl);
6012 if (__predict_false(cache_fpl_terminated(fpl))) {
6013 break;
6014 }
6015
6016 VNPASS(!seqc_in_modify(fpl->tvp_seqc), fpl->tvp);
6017
6018 if (fpl->tvp->v_type == VLNK) {
6019 error = cache_fplookup_symlink(fpl);
6020 if (cache_fpl_terminated(fpl)) {
6021 break;
6022 }
6023 } else {
6024 if (cache_fpl_islastcn(ndp)) {
6025 error = cache_fplookup_final(fpl);
6026 break;
6027 }
6028
6029 if (!vn_seqc_consistent(fpl->dvp, fpl->dvp_seqc)) {
6030 error = cache_fpl_aborted(fpl);
6031 break;
6032 }
6033
6034 fpl->dvp = fpl->tvp;
6035 fpl->dvp_seqc = fpl->tvp_seqc;
6036 cache_fplookup_parse_advance(fpl);
6037 }
6038
6039 cache_fpl_checkpoint(fpl);
6040 }
6041
6042 return (error);
6043 }
6044
6045 /*
6046 * Fast path lookup protected with SMR and sequence counters.
6047 *
6048 * Note: all VOP_FPLOOKUP_VEXEC routines have a comment referencing this one.
6049 *
6050 * Filesystems can opt in by setting the MNTK_FPLOOKUP flag and meeting criteria
6051 * outlined below.
6052 *
6053 * Traditional vnode lookup conceptually looks like this:
6054 *
6055 * vn_lock(current);
6056 * for (;;) {
6057 * next = find();
6058 * vn_lock(next);
6059 * vn_unlock(current);
6060 * current = next;
6061 * if (last)
6062 * break;
6063 * }
6064 * return (current);
6065 *
6066 * Each jump to the next vnode is safe memory-wise and atomic with respect to
6067 * any modifications thanks to holding respective locks.
6068 *
6069 * The same guarantee can be provided with a combination of safe memory
6070 * reclamation and sequence counters instead. If all operations which affect
6071 * the relationship between the current vnode and the one we are looking for
6072 * also modify the counter, we can verify whether all the conditions held as
6073 * we made the jump. This includes things like permissions, mount points etc.
6074 * Counter modification is provided by enclosing relevant places in
6075 * vn_seqc_write_begin()/end() calls.
6076 *
6077 * Thus this translates to:
6078 *
6079 * vfs_smr_enter();
6080 * dvp_seqc = seqc_read_any(dvp);
6081 * if (seqc_in_modify(dvp_seqc)) // someone is altering the vnode
6082 * abort();
6083 * for (;;) {
6084 * tvp = find();
6085 * tvp_seqc = seqc_read_any(tvp);
6086 * if (seqc_in_modify(tvp_seqc)) // someone is altering the target vnode
6087 * abort();
6088 * if (!seqc_consistent(dvp, dvp_seqc) // someone is altering the vnode
6089 * abort();
6090 * dvp = tvp; // we know nothing of importance has changed
6091 * dvp_seqc = tvp_seqc; // store the counter for the tvp iteration
6092 * if (last)
6093 * break;
6094 * }
6095 * vget(); // secure the vnode
6096 * if (!seqc_consistent(tvp, tvp_seqc) // final check
6097 * abort();
6098 * // at this point we know nothing has changed for any parent<->child pair
6099 * // as they were crossed during the lookup, meaning we matched the guarantee
6100 * // of the locked variant
6101 * return (tvp);
6102 *
6103 * The API contract for VOP_FPLOOKUP_VEXEC routines is as follows:
6104 * - they are called while within vfs_smr protection which they must never exit
6105 * - EAGAIN can be returned to denote checking could not be performed, it is
6106 * always valid to return it
6107 * - if the sequence counter has not changed the result must be valid
6108 * - if the sequence counter has changed both false positives and false negatives
6109 * are permitted (since the result will be rejected later)
6110 * - for simple cases of unix permission checks vaccess_vexec_smr can be used
6111 *
6112 * Caveats to watch out for:
6113 * - vnodes are passed unlocked and unreferenced with nothing stopping
6114 * VOP_RECLAIM, in turn meaning that ->v_data can become NULL. It is advised
6115 * to use atomic_load_ptr to fetch it.
6116 * - the aforementioned object can also get freed, meaning absent other means it
6117 * should be protected with vfs_smr
6118 * - either safely checking permissions as they are modified or guaranteeing
6119 * their stability is left to the routine
6120 */
6121 int
6122 cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status,
6123 struct pwd **pwdp)
6124 {
6125 struct cache_fpl fpl;
6126 struct pwd *pwd;
6127 struct vnode *dvp;
6128 struct componentname *cnp;
6129 int error;
6130
6131 fpl.status = CACHE_FPL_STATUS_UNSET;
6132 fpl.in_smr = false;
6133 fpl.ndp = ndp;
6134 fpl.cnp = cnp = &ndp->ni_cnd;
6135 MPASS(ndp->ni_lcf == 0);
6136 KASSERT ((cnp->cn_flags & CACHE_FPL_INTERNAL_CN_FLAGS) == 0,
6137 ("%s: internal flags found in cn_flags %" PRIx64, __func__,
6138 cnp->cn_flags));
6139 MPASS(cnp->cn_nameptr == cnp->cn_pnbuf);
6140
6141 if (__predict_false(!cache_can_fplookup(&fpl))) {
6142 *status = fpl.status;
6143 SDT_PROBE3(vfs, fplookup, lookup, done, ndp, fpl.line, fpl.status);
6144 return (EOPNOTSUPP);
6145 }
6146
6147 cache_fpl_checkpoint_outer(&fpl);
6148
6149 cache_fpl_smr_enter_initial(&fpl);
6150 #ifdef INVARIANTS
6151 fpl.debug.ni_pathlen = ndp->ni_pathlen;
6152 #endif
6153 fpl.nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1];
6154 fpl.fsearch = false;
6155 fpl.tvp = NULL; /* for degenerate path handling */
6156 fpl.pwd = pwdp;
6157 pwd = pwd_get_smr();
6158 *(fpl.pwd) = pwd;
6159 ndp->ni_rootdir = pwd->pwd_rdir;
6160 ndp->ni_topdir = pwd->pwd_jdir;
6161
6162 if (cnp->cn_pnbuf[0] == '/') {
6163 dvp = cache_fpl_handle_root(&fpl);
6164 MPASS(ndp->ni_resflags == 0);
6165 ndp->ni_resflags = NIRES_ABS;
6166 } else {
6167 if (ndp->ni_dirfd == AT_FDCWD) {
6168 dvp = pwd->pwd_cdir;
6169 } else {
6170 error = cache_fplookup_dirfd(&fpl, &dvp);
6171 if (__predict_false(error != 0)) {
6172 goto out;
6173 }
6174 }
6175 }
6176
6177 SDT_PROBE4(vfs, namei, lookup, entry, dvp, cnp->cn_pnbuf, cnp->cn_flags, true);
6178 error = cache_fplookup_impl(dvp, &fpl);
6179 out:
6180 cache_fpl_smr_assert_not_entered(&fpl);
6181 cache_fpl_assert_status(&fpl);
6182 *status = fpl.status;
6183 if (SDT_PROBES_ENABLED()) {
6184 SDT_PROBE3(vfs, fplookup, lookup, done, ndp, fpl.line, fpl.status);
6185 if (fpl.status == CACHE_FPL_STATUS_HANDLED)
6186 SDT_PROBE4(vfs, namei, lookup, return, error, ndp->ni_vp, true,
6187 ndp);
6188 }
6189
6190 if (__predict_true(fpl.status == CACHE_FPL_STATUS_HANDLED)) {
6191 MPASS(error != CACHE_FPL_FAILED);
6192 if (error != 0) {
6193 cache_fpl_cleanup_cnp(fpl.cnp);
6194 MPASS(fpl.dvp == NULL);
6195 MPASS(fpl.tvp == NULL);
6196 }
6197 ndp->ni_dvp = fpl.dvp;
6198 ndp->ni_vp = fpl.tvp;
6199 }
6200 return (error);
6201 }
Cache object: dcff630c453ec0cdc0ad94c084061204
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