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 #include "opt_ddb.h" 39 #include "opt_ktrace.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/capsicum.h> 44 #include <sys/counter.h> 45 #include <sys/filedesc.h> 46 #include <sys/fnv_hash.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/lock.h> 50 #include <sys/malloc.h> 51 #include <sys/fcntl.h> 52 #include <sys/jail.h> 53 #include <sys/mount.h> 54 #include <sys/namei.h> 55 #include <sys/proc.h> 56 #include <sys/seqc.h> 57 #include <sys/sdt.h> 58 #include <sys/smr.h> 59 #include <sys/smp.h> 60 #include <sys/syscallsubr.h> 61 #include <sys/sysctl.h> 62 #include <sys/sysproto.h> 63 #include <sys/vnode.h> 64 #include <ck_queue.h> 65 #ifdef KTRACE 66 #include <sys/ktrace.h> 67 #endif 68 #ifdef INVARIANTS 69 #include <machine/_inttypes.h> 70 #endif 71 72 #include <security/audit/audit.h> 73 #include <security/mac/mac_framework.h> 74 75 #ifdef DDB 76 #include <ddb/ddb.h> 77 #endif 78 79 #include <vm/uma.h> 80 81 /* 82 * High level overview of name caching in the VFS layer. 83 * 84 * Originally caching was implemented as part of UFS, later extracted to allow 85 * use by other filesystems. A decision was made to make it optional and 86 * completely detached from the rest of the kernel, which comes with limitations 87 * outlined near the end of this comment block. 88 * 89 * This fundamental choice needs to be revisited. In the meantime, the current 90 * state is described below. Significance of all notable routines is explained 91 * in comments placed above their implementation. Scattered thoroughout the 92 * file are TODO comments indicating shortcomings which can be fixed without 93 * reworking everything (most of the fixes will likely be reusable). Various 94 * details are omitted from this explanation to not clutter the overview, they 95 * have to be checked by reading the code and associated commentary. 96 * 97 * Keep in mind that it's individual path components which are cached, not full 98 * paths. That is, for a fully cached path "foo/bar/baz" there are 3 entries, 99 * one for each name. 100 * 101 * I. Data organization 102 * 103 * Entries are described by "struct namecache" objects and stored in a hash 104 * table. See cache_get_hash for more information. 105 * 106 * "struct vnode" contains pointers to source entries (names which can be found 107 * when traversing through said vnode), destination entries (names of that 108 * vnode (see "Limitations" for a breakdown on the subject) and a pointer to 109 * the parent vnode. 110 * 111 * The (directory vnode; name) tuple reliably determines the target entry if 112 * it exists. 113 * 114 * Since there are no small locks at this time (all are 32 bytes in size on 115 * LP64), the code works around the problem by introducing lock arrays to 116 * protect hash buckets and vnode lists. 117 * 118 * II. Filesystem integration 119 * 120 * Filesystems participating in name caching do the following: 121 * - set vop_lookup routine to vfs_cache_lookup 122 * - set vop_cachedlookup to whatever can perform the lookup if the above fails 123 * - if they support lockless lookup (see below), vop_fplookup_vexec and 124 * vop_fplookup_symlink are set along with the MNTK_FPLOOKUP flag on the 125 * mount point 126 * - call cache_purge or cache_vop_* routines to eliminate stale entries as 127 * applicable 128 * - call cache_enter to add entries depending on the MAKEENTRY flag 129 * 130 * With the above in mind, there are 2 entry points when doing lookups: 131 * - ... -> namei -> cache_fplookup -- this is the default 132 * - ... -> VOP_LOOKUP -> vfs_cache_lookup -- normally only called by namei 133 * should the above fail 134 * 135 * Example code flow how an entry is added: 136 * ... -> namei -> cache_fplookup -> cache_fplookup_noentry -> VOP_LOOKUP -> 137 * vfs_cache_lookup -> VOP_CACHEDLOOKUP -> ufs_lookup_ino -> cache_enter 138 * 139 * III. Performance considerations 140 * 141 * For lockless case forward lookup avoids any writes to shared areas apart 142 * from the terminal path component. In other words non-modifying lookups of 143 * different files don't suffer any scalability problems in the namecache. 144 * Looking up the same file is limited by VFS and goes beyond the scope of this 145 * file. 146 * 147 * At least on amd64 the single-threaded bottleneck for long paths is hashing 148 * (see cache_get_hash). There are cases where the code issues acquire fence 149 * multiple times, they can be combined on architectures which suffer from it. 150 * 151 * For locked case each encountered vnode has to be referenced and locked in 152 * order to be handed out to the caller (normally that's namei). This 153 * introduces significant hit single-threaded and serialization multi-threaded. 154 * 155 * Reverse lookup (e.g., "getcwd") fully scales provided it is fully cached -- 156 * avoids any writes to shared areas to any components. 157 * 158 * Unrelated insertions are partially serialized on updating the global entry 159 * counter and possibly serialized on colliding bucket or vnode locks. 160 * 161 * IV. Observability 162 * 163 * Note not everything has an explicit dtrace probe nor it should have, thus 164 * some of the one-liners below depend on implementation details. 165 * 166 * Examples: 167 * 168 * # Check what lookups failed to be handled in a lockless manner. Column 1 is 169 * # line number, column 2 is status code (see cache_fpl_status) 170 * dtrace -n 'vfs:fplookup:lookup:done { @[arg1, arg2] = count(); }' 171 * 172 * # Lengths of names added by binary name 173 * dtrace -n 'fbt::cache_enter_time:entry { @[execname] = quantize(args[2]->cn_namelen); }' 174 * 175 * # Same as above but only those which exceed 64 characters 176 * dtrace -n 'fbt::cache_enter_time:entry /args[2]->cn_namelen > 64/ { @[execname] = quantize(args[2]->cn_namelen); }' 177 * 178 * # Who is performing lookups with spurious slashes (e.g., "foo//bar") and what 179 * # path is it 180 * dtrace -n 'fbt::cache_fplookup_skip_slashes:entry { @[execname, stringof(args[0]->cnp->cn_pnbuf)] = count(); }' 181 * 182 * V. Limitations and implementation defects 183 * 184 * - since it is possible there is no entry for an open file, tools like 185 * "procstat" may fail to resolve fd -> vnode -> path to anything 186 * - even if a filesystem adds an entry, it may get purged (e.g., due to memory 187 * shortage) in which case the above problem applies 188 * - hardlinks are not tracked, thus if a vnode is reachable in more than one 189 * way, resolving a name may return a different path than the one used to 190 * open it (even if said path is still valid) 191 * - by default entries are not added for newly created files 192 * - adding an entry may need to evict negative entry first, which happens in 2 193 * distinct places (evicting on lookup, adding in a later VOP) making it 194 * impossible to simply reuse it 195 * - there is a simple scheme to evict negative entries as the cache is approaching 196 * its capacity, but it is very unclear if doing so is a good idea to begin with 197 * - vnodes are subject to being recycled even if target inode is left in memory, 198 * which loses the name cache entries when it perhaps should not. in case of tmpfs 199 * names get duplicated -- kept by filesystem itself and namecache separately 200 * - struct namecache has a fixed size and comes in 2 variants, often wasting 201 * space. now hard to replace with malloc due to dependence on SMR, which 202 * requires UMA zones to opt in 203 * - lack of better integration with the kernel also turns nullfs into a layered 204 * filesystem instead of something which can take advantage of caching 205 * 206 * Appendix A: where is the time lost, expanding on paragraph III 207 * 208 * While some care went into optimizing lookups, there is still plenty of 209 * performance left on the table, most notably from single-threaded standpoint. 210 * Below is a woefully incomplete list of changes which can help. Ideas are 211 * mostly sketched out, no claim is made all kinks or prerequisites are laid 212 * out. 213 * 214 * Note there is performance lost all over VFS. 215 * 216 * === SMR-only lookup 217 * 218 * For commonly used ops like stat(2), when the terminal vnode *is* cached, 219 * lockless lookup could refrain from refing/locking the found vnode and 220 * instead return while within the SMR section. Then a call to, say, 221 * vop_stat_smr could do the work (or fail with EAGAIN), finally the result 222 * would be validated with seqc not changing. This would be faster 223 * single-threaded as it dodges atomics and would provide full scalability for 224 * multicore uses. This would *not* work for open(2) or other calls which need 225 * the vnode to hang around for the long haul, but would work for aforementioned 226 * stat(2) but also access(2), readlink(2), realpathat(2) and probably more. 227 * 228 * === hotpatching for sdt probes 229 * 230 * They result in *tons* of branches all over with rather regrettable codegen 231 * at times. Removing sdt probes altogether gives over 2% boost in lookup rate. 232 * Reworking the code to patch itself at runtime with asm goto would solve it. 233 * asm goto is fully supported by gcc and clang. 234 * 235 * === copyinstr 236 * 237 * On all architectures it operates one byte at a time, while it could be 238 * word-sized instead thanks to the Mycroft trick. 239 * 240 * API itself is rather pessimal for path lookup, accepting arbitrary sizes and 241 * *optionally* filling in the length parameter. 242 * 243 * Instead a new routine (copyinpath?) could be introduced, demanding a buffer 244 * size which is a multiply of the word (and never zero), with the length 245 * always returned. On top of it the routine could be allowed to transform the 246 * buffer in arbitrary ways, most notably writing past the found length (not to 247 * be confused with writing past buffer size) -- this would allow word-sized 248 * movs while checking for '\0' later. 249 * 250 * === detour through namei 251 * 252 * Currently one suffers being called from namei, which then has to check if 253 * things worked out locklessly. Instead the lockless lookup could be the 254 * actual entry point which calls what is currently namei as a fallback. 255 * 256 * === avoidable branches in cache_can_fplookup 257 * 258 * The cache_fast_lookup_enabled flag check could be hotpatchable (in fact if 259 * this is off, none of fplookup code should execute). 260 * 261 * Both audit and capsicum branches can be combined into one, but it requires 262 * paying off a lot of tech debt first. 263 * 264 * ni_startdir could be indicated with a flag in cn_flags, eliminating the 265 * branch. 266 * 267 * === mount stacks 268 * 269 * Crossing a mount requires checking if perhaps something is mounted on top. 270 * Instead, an additional entry could be added to struct mount with a pointer 271 * to the final mount on the stack. This would be recalculated on each 272 * mount/unmount. 273 * 274 * === root vnodes 275 * 276 * It could become part of the API contract to *always* have a rootvnode set in 277 * mnt_rootvnode. Such vnodes are annotated with VV_ROOT and vnlru would have 278 * to be modified to always skip them. 279 * 280 * === inactive on v_usecount reaching 0 281 * 282 * VOP_NEED_INACTIVE should not exist. Filesystems would indicate need for such 283 * processing with a bit in usecount. 284 * 285 * === v_holdcnt 286 * 287 * Hold count should probably get eliminated, but one can argue it is a useful 288 * feature. Even if so, handling of v_usecount could be decoupled from it -- 289 * vnlru et al would consider the vnode not-freeable if has either hold or 290 * usecount on it. 291 * 292 * This would eliminate 2 atomics. 293 */ 294 295 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 296 "Name cache"); 297 298 SDT_PROVIDER_DECLARE(vfs); 299 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", 300 "struct vnode *"); 301 SDT_PROBE_DEFINE3(vfs, namecache, enter, duplicate, "struct vnode *", "char *", 302 "struct vnode *"); 303 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", 304 "char *"); 305 SDT_PROBE_DEFINE2(vfs, namecache, fullpath_smr, hit, "struct vnode *", 306 "const char *"); 307 SDT_PROBE_DEFINE4(vfs, namecache, fullpath_smr, miss, "struct vnode *", 308 "struct namecache *", "int", "int"); 309 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); 310 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", 311 "char *", "struct vnode *"); 312 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); 313 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", 314 "struct vnode *", "char *"); 315 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", 316 "struct vnode *"); 317 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, 318 "struct vnode *", "char *"); 319 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", 320 "char *"); 321 SDT_PROBE_DEFINE2(vfs, namecache, removecnp, hit, "struct vnode *", 322 "struct componentname *"); 323 SDT_PROBE_DEFINE2(vfs, namecache, removecnp, miss, "struct vnode *", 324 "struct componentname *"); 325 SDT_PROBE_DEFINE3(vfs, namecache, purge, done, "struct vnode *", "size_t", "size_t"); 326 SDT_PROBE_DEFINE1(vfs, namecache, purge, batch, "int"); 327 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); 328 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); 329 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", 330 "struct vnode *"); 331 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *", 332 "char *"); 333 SDT_PROBE_DEFINE2(vfs, namecache, evict_negative, done, "struct vnode *", 334 "char *"); 335 SDT_PROBE_DEFINE1(vfs, namecache, symlink, alloc__fail, "size_t"); 336 337 SDT_PROBE_DEFINE3(vfs, fplookup, lookup, done, "struct nameidata", "int", "bool"); 338 SDT_PROBE_DECLARE(vfs, namei, lookup, entry); 339 SDT_PROBE_DECLARE(vfs, namei, lookup, return); 340 341 static char __read_frequently cache_fast_lookup_enabled = true; 342 343 /* 344 * This structure describes the elements in the cache of recent 345 * names looked up by namei. 346 */ 347 struct negstate { 348 u_char neg_flag; 349 u_char neg_hit; 350 }; 351 _Static_assert(sizeof(struct negstate) <= sizeof(struct vnode *), 352 "the state must fit in a union with a pointer without growing it"); 353 354 struct namecache { 355 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 356 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 357 CK_SLIST_ENTRY(namecache) nc_hash;/* hash chain */ 358 struct vnode *nc_dvp; /* vnode of parent of name */ 359 union { 360 struct vnode *nu_vp; /* vnode the name refers to */ 361 struct negstate nu_neg;/* negative entry state */ 362 } n_un; 363 u_char nc_flag; /* flag bits */ 364 u_char nc_nlen; /* length of name */ 365 char nc_name[]; /* segment name + nul */ 366 }; 367 368 /* 369 * struct namecache_ts repeats struct namecache layout up to the 370 * nc_nlen member. 371 * struct namecache_ts is used in place of struct namecache when time(s) need 372 * to be stored. The nc_dotdottime field is used when a cache entry is mapping 373 * both a non-dotdot directory name plus dotdot for the directory's 374 * parent. 375 * 376 * See below for alignment requirement. 377 */ 378 struct namecache_ts { 379 struct timespec nc_time; /* timespec provided by fs */ 380 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ 381 int nc_ticks; /* ticks value when entry was added */ 382 int nc_pad; 383 struct namecache nc_nc; 384 }; 385 386 TAILQ_HEAD(cache_freebatch, namecache); 387 388 /* 389 * At least mips n32 performs 64-bit accesses to timespec as found 390 * in namecache_ts and requires them to be aligned. Since others 391 * may be in the same spot suffer a little bit and enforce the 392 * alignment for everyone. Note this is a nop for 64-bit platforms. 393 */ 394 #define CACHE_ZONE_ALIGNMENT UMA_ALIGNOF(time_t) 395 396 /* 397 * TODO: the initial value of CACHE_PATH_CUTOFF was inherited from the 398 * 4.4 BSD codebase. Later on struct namecache was tweaked to become 399 * smaller and the value was bumped to retain the total size, but it 400 * was never re-evaluated for suitability. A simple test counting 401 * lengths during package building shows that the value of 45 covers 402 * about 86% of all added entries, reaching 99% at 65. 403 * 404 * Regardless of the above, use of dedicated zones instead of malloc may be 405 * inducing additional waste. This may be hard to address as said zones are 406 * tied to VFS SMR. Even if retaining them, the current split should be 407 * re-evaluated. 408 */ 409 #ifdef __LP64__ 410 #define CACHE_PATH_CUTOFF 45 411 #define CACHE_LARGE_PAD 6 412 #else 413 #define CACHE_PATH_CUTOFF 41 414 #define CACHE_LARGE_PAD 2 415 #endif 416 417 #define CACHE_ZONE_SMALL_SIZE (offsetof(struct namecache, nc_name) + CACHE_PATH_CUTOFF + 1) 418 #define CACHE_ZONE_SMALL_TS_SIZE (offsetof(struct namecache_ts, nc_nc) + CACHE_ZONE_SMALL_SIZE) 419 #define CACHE_ZONE_LARGE_SIZE (offsetof(struct namecache, nc_name) + NAME_MAX + 1 + CACHE_LARGE_PAD) 420 #define CACHE_ZONE_LARGE_TS_SIZE (offsetof(struct namecache_ts, nc_nc) + CACHE_ZONE_LARGE_SIZE) 421 422 _Static_assert((CACHE_ZONE_SMALL_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 423 _Static_assert((CACHE_ZONE_SMALL_TS_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 424 _Static_assert((CACHE_ZONE_LARGE_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 425 _Static_assert((CACHE_ZONE_LARGE_TS_SIZE % (CACHE_ZONE_ALIGNMENT + 1)) == 0, "bad zone size"); 426 427 #define nc_vp n_un.nu_vp 428 #define nc_neg n_un.nu_neg 429 430 /* 431 * Flags in namecache.nc_flag 432 */ 433 #define NCF_WHITE 0x01 434 #define NCF_ISDOTDOT 0x02 435 #define NCF_TS 0x04 436 #define NCF_DTS 0x08 437 #define NCF_DVDROP 0x10 438 #define NCF_NEGATIVE 0x20 439 #define NCF_INVALID 0x40 440 #define NCF_WIP 0x80 441 442 /* 443 * Flags in negstate.neg_flag 444 */ 445 #define NEG_HOT 0x01 446 447 static bool cache_neg_evict_cond(u_long lnumcache); 448 449 /* 450 * Mark an entry as invalid. 451 * 452 * This is called before it starts getting deconstructed. 453 */ 454 static void 455 cache_ncp_invalidate(struct namecache *ncp) 456 { 457 458 KASSERT((ncp->nc_flag & NCF_INVALID) == 0, 459 ("%s: entry %p already invalid", __func__, ncp)); 460 atomic_store_char(&ncp->nc_flag, ncp->nc_flag | NCF_INVALID); 461 atomic_thread_fence_rel(); 462 } 463 464 /* 465 * Check whether the entry can be safely used. 466 * 467 * All places which elide locks are supposed to call this after they are 468 * done with reading from an entry. 469 */ 470 #define cache_ncp_canuse(ncp) ({ \ 471 struct namecache *_ncp = (ncp); \ 472 u_char _nc_flag; \ 473 \ 474 atomic_thread_fence_acq(); \ 475 _nc_flag = atomic_load_char(&_ncp->nc_flag); \ 476 __predict_true((_nc_flag & (NCF_INVALID | NCF_WIP)) == 0); \ 477 }) 478 479 /* 480 * Like the above but also checks NCF_WHITE. 481 */ 482 #define cache_fpl_neg_ncp_canuse(ncp) ({ \ 483 struct namecache *_ncp = (ncp); \ 484 u_char _nc_flag; \ 485 \ 486 atomic_thread_fence_acq(); \ 487 _nc_flag = atomic_load_char(&_ncp->nc_flag); \ 488 __predict_true((_nc_flag & (NCF_INVALID | NCF_WIP | NCF_WHITE)) == 0); \ 489 }) 490 491 VFS_SMR_DECLARE; 492 493 static SYSCTL_NODE(_vfs_cache, OID_AUTO, param, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 494 "Name cache parameters"); 495 496 static u_int __read_mostly ncsize; /* the size as computed on creation or resizing */ 497 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, size, CTLFLAG_RD, &ncsize, 0, 498 "Total namecache capacity"); 499 500 u_int ncsizefactor = 2; 501 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, sizefactor, CTLFLAG_RW, &ncsizefactor, 0, 502 "Size factor for namecache"); 503 504 static u_long __read_mostly ncnegfactor = 5; /* ratio of negative entries */ 505 SYSCTL_ULONG(_vfs_cache_param, OID_AUTO, negfactor, CTLFLAG_RW, &ncnegfactor, 0, 506 "Ratio of negative namecache entries"); 507 508 /* 509 * Negative entry % of namecache capacity above which automatic eviction is allowed. 510 * 511 * Check cache_neg_evict_cond for details. 512 */ 513 static u_int ncnegminpct = 3; 514 515 static u_int __read_mostly neg_min; /* the above recomputed against ncsize */ 516 SYSCTL_UINT(_vfs_cache_param, OID_AUTO, negmin, CTLFLAG_RD, &neg_min, 0, 517 "Negative entry count above which automatic eviction is allowed"); 518 519 /* 520 * Structures associated with name caching. 521 */ 522 #define NCHHASH(hash) \ 523 (&nchashtbl[(hash) & nchash]) 524 static __read_mostly CK_SLIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */ 525 static u_long __read_mostly nchash; /* size of hash table */ 526 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, 527 "Size of namecache hash table"); 528 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */ 529 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */ 530 531 struct nchstats nchstats; /* cache effectiveness statistics */ 532 533 static u_int __exclusive_cache_line neg_cycle; 534 535 #define ncneghash 3 536 #define numneglists (ncneghash + 1) 537 538 struct neglist { 539 struct mtx nl_evict_lock; 540 struct mtx nl_lock __aligned(CACHE_LINE_SIZE); 541 TAILQ_HEAD(, namecache) nl_list; 542 TAILQ_HEAD(, namecache) nl_hotlist; 543 u_long nl_hotnum; 544 } __aligned(CACHE_LINE_SIZE); 545 546 static struct neglist neglists[numneglists]; 547 548 static inline struct neglist * 549 NCP2NEGLIST(struct namecache *ncp) 550 { 551 552 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]); 553 } 554 555 static inline struct negstate * 556 NCP2NEGSTATE(struct namecache *ncp) 557 { 558 559 MPASS(atomic_load_char(&ncp->nc_flag) & NCF_NEGATIVE); 560 return (&ncp->nc_neg); 561 } 562 563 #define numbucketlocks (ncbuckethash + 1) 564 static u_int __read_mostly ncbuckethash; 565 static struct mtx_padalign __read_mostly *bucketlocks; 566 #define HASH2BUCKETLOCK(hash) \ 567 ((struct mtx *)(&bucketlocks[((hash) & ncbuckethash)])) 568 569 #define numvnodelocks (ncvnodehash + 1) 570 static u_int __read_mostly ncvnodehash; 571 static struct mtx __read_mostly *vnodelocks; 572 static inline struct mtx * 573 VP2VNODELOCK(struct vnode *vp) 574 { 575 576 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]); 577 } 578 579 static void 580 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) 581 { 582 struct namecache_ts *ncp_ts; 583 584 KASSERT((ncp->nc_flag & NCF_TS) != 0 || 585 (tsp == NULL && ticksp == NULL), 586 ("No NCF_TS")); 587 588 if (tsp == NULL) 589 return; 590 591 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 592 *tsp = ncp_ts->nc_time; 593 *ticksp = ncp_ts->nc_ticks; 594 } 595 596 #ifdef DEBUG_CACHE 597 static int __read_mostly doingcache = 1; /* 1 => enable the cache */ 598 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, 599 "VFS namecache enabled"); 600 #endif 601 602 /* Export size information to userland */ 603 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, 604 sizeof(struct namecache), "sizeof(struct namecache)"); 605 606 /* 607 * The new name cache statistics 608 */ 609 static SYSCTL_NODE(_vfs_cache, OID_AUTO, stats, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 610 "Name cache statistics"); 611 612 #define STATNODE_ULONG(name, varname, descr) \ 613 SYSCTL_ULONG(_vfs_cache_stats, OID_AUTO, name, CTLFLAG_RD, &varname, 0, descr); 614 #define STATNODE_COUNTER(name, varname, descr) \ 615 static COUNTER_U64_DEFINE_EARLY(varname); \ 616 SYSCTL_COUNTER_U64(_vfs_cache_stats, OID_AUTO, name, CTLFLAG_RD, &varname, \ 617 descr); 618 STATNODE_ULONG(neg, numneg, "Number of negative cache entries"); 619 STATNODE_ULONG(count, numcache, "Number of cache entries"); 620 STATNODE_COUNTER(heldvnodes, numcachehv, "Number of namecache entries with vnodes held"); 621 STATNODE_COUNTER(drops, numdrops, "Number of dropped entries due to reaching the limit"); 622 STATNODE_COUNTER(miss, nummiss, "Number of cache misses"); 623 STATNODE_COUNTER(misszap, nummisszap, "Number of cache misses we do not want to cache"); 624 STATNODE_COUNTER(poszaps, numposzaps, 625 "Number of cache hits (positive) we do not want to cache"); 626 STATNODE_COUNTER(poshits, numposhits, "Number of cache hits (positive)"); 627 STATNODE_COUNTER(negzaps, numnegzaps, 628 "Number of cache hits (negative) we do not want to cache"); 629 STATNODE_COUNTER(neghits, numneghits, "Number of cache hits (negative)"); 630 /* These count for vn_getcwd(), too. */ 631 STATNODE_COUNTER(fullpathcalls, numfullpathcalls, "Number of fullpath search calls"); 632 STATNODE_COUNTER(fullpathfail2, numfullpathfail2, 633 "Number of fullpath search errors (VOP_VPTOCNP failures)"); 634 STATNODE_COUNTER(fullpathfail4, numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); 635 STATNODE_COUNTER(fullpathfound, numfullpathfound, "Number of successful fullpath calls"); 636 STATNODE_COUNTER(symlinktoobig, symlinktoobig, "Number of times symlink did not fit the cache"); 637 638 /* 639 * Debug or developer statistics. 640 */ 641 static SYSCTL_NODE(_vfs_cache, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 642 "Name cache debugging"); 643 #define DEBUGNODE_ULONG(name, varname, descr) \ 644 SYSCTL_ULONG(_vfs_cache_debug, OID_AUTO, name, CTLFLAG_RD, &varname, 0, descr); 645 static u_long zap_bucket_relock_success; 646 DEBUGNODE_ULONG(zap_bucket_relock_success, zap_bucket_relock_success, 647 "Number of successful removals after relocking"); 648 static u_long zap_bucket_fail; 649 DEBUGNODE_ULONG(zap_bucket_fail, zap_bucket_fail, ""); 650 static u_long zap_bucket_fail2; 651 DEBUGNODE_ULONG(zap_bucket_fail2, zap_bucket_fail2, ""); 652 static u_long cache_lock_vnodes_cel_3_failures; 653 DEBUGNODE_ULONG(vnodes_cel_3_failures, cache_lock_vnodes_cel_3_failures, 654 "Number of times 3-way vnode locking failed"); 655 656 static void cache_zap_locked(struct namecache *ncp); 657 static int vn_fullpath_any_smr(struct vnode *vp, struct vnode *rdir, char *buf, 658 char **retbuf, size_t *buflen, size_t addend); 659 static int vn_fullpath_any(struct vnode *vp, struct vnode *rdir, char *buf, 660 char **retbuf, size_t *buflen); 661 static int vn_fullpath_dir(struct vnode *vp, struct vnode *rdir, char *buf, 662 char **retbuf, size_t *len, size_t addend); 663 664 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 665 666 static inline void 667 cache_assert_vlp_locked(struct mtx *vlp) 668 { 669 670 if (vlp != NULL) 671 mtx_assert(vlp, MA_OWNED); 672 } 673 674 static inline void 675 cache_assert_vnode_locked(struct vnode *vp) 676 { 677 struct mtx *vlp; 678 679 vlp = VP2VNODELOCK(vp); 680 cache_assert_vlp_locked(vlp); 681 } 682 683 /* 684 * Directory vnodes with entries are held for two reasons: 685 * 1. make them less of a target for reclamation in vnlru 686 * 2. suffer smaller performance penalty in locked lookup as requeieing is avoided 687 * 688 * It will be feasible to stop doing it altogether if all filesystems start 689 * supporting lockless lookup. 690 */ 691 static void 692 cache_hold_vnode(struct vnode *vp) 693 { 694 695 cache_assert_vnode_locked(vp); 696 VNPASS(LIST_EMPTY(&vp->v_cache_src), vp); 697 vhold(vp); 698 counter_u64_add(numcachehv, 1); 699 } 700 701 static void 702 cache_drop_vnode(struct vnode *vp) 703 { 704 705 /* 706 * Called after all locks are dropped, meaning we can't assert 707 * on the state of v_cache_src. 708 */ 709 vdrop(vp); 710 counter_u64_add(numcachehv, -1); 711 } 712 713 /* 714 * UMA zones. 715 */ 716 static uma_zone_t __read_mostly cache_zone_small; 717 static uma_zone_t __read_mostly cache_zone_small_ts; 718 static uma_zone_t __read_mostly cache_zone_large; 719 static uma_zone_t __read_mostly cache_zone_large_ts; 720 721 char * 722 cache_symlink_alloc(size_t size, int flags) 723 { 724 725 if (size < CACHE_ZONE_SMALL_SIZE) { 726 return (uma_zalloc_smr(cache_zone_small, flags)); 727 } 728 if (size < CACHE_ZONE_LARGE_SIZE) { 729 return (uma_zalloc_smr(cache_zone_large, flags)); 730 } 731 counter_u64_add(symlinktoobig, 1); 732 SDT_PROBE1(vfs, namecache, symlink, alloc__fail, size); 733 return (NULL); 734 } 735 736 void 737 cache_symlink_free(char *string, size_t size) 738 { 739 740 MPASS(string != NULL); 741 KASSERT(size < CACHE_ZONE_LARGE_SIZE, 742 ("%s: size %zu too big", __func__, size)); 743 744 if (size < CACHE_ZONE_SMALL_SIZE) { 745 uma_zfree_smr(cache_zone_small, string); 746 return; 747 } 748 if (size < CACHE_ZONE_LARGE_SIZE) { 749 uma_zfree_smr(cache_zone_large, string); 750 return; 751 } 752 __assert_unreachable(); 753 } 754 755 static struct namecache * 756 cache_alloc_uma(int len, bool ts) 757 { 758 struct namecache_ts *ncp_ts; 759 struct namecache *ncp; 760 761 if (__predict_false(ts)) { 762 if (len <= CACHE_PATH_CUTOFF) 763 ncp_ts = uma_zalloc_smr(cache_zone_small_ts, M_WAITOK); 764 else 765 ncp_ts = uma_zalloc_smr(cache_zone_large_ts, M_WAITOK); 766 ncp = &ncp_ts->nc_nc; 767 } else { 768 if (len <= CACHE_PATH_CUTOFF) 769 ncp = uma_zalloc_smr(cache_zone_small, M_WAITOK); 770 else 771 ncp = uma_zalloc_smr(cache_zone_large, M_WAITOK); 772 } 773 return (ncp); 774 } 775 776 static void 777 cache_free_uma(struct namecache *ncp) 778 { 779 struct namecache_ts *ncp_ts; 780 781 if (__predict_false(ncp->nc_flag & NCF_TS)) { 782 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 783 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 784 uma_zfree_smr(cache_zone_small_ts, ncp_ts); 785 else 786 uma_zfree_smr(cache_zone_large_ts, ncp_ts); 787 } else { 788 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) 789 uma_zfree_smr(cache_zone_small, ncp); 790 else 791 uma_zfree_smr(cache_zone_large, ncp); 792 } 793 } 794 795 static struct namecache * 796 cache_alloc(int len, bool ts) 797 { 798 u_long lnumcache; 799 800 /* 801 * Avoid blowout in namecache entries. 802 * 803 * Bugs: 804 * 1. filesystems may end up trying to add an already existing entry 805 * (for example this can happen after a cache miss during concurrent 806 * lookup), in which case we will call cache_neg_evict despite not 807 * adding anything. 808 * 2. the routine may fail to free anything and no provisions are made 809 * to make it try harder (see the inside for failure modes) 810 * 3. it only ever looks at negative entries. 811 */ 812 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1; 813 if (cache_neg_evict_cond(lnumcache)) { 814 lnumcache = atomic_load_long(&numcache); 815 } 816 if (__predict_false(lnumcache >= ncsize)) { 817 atomic_subtract_long(&numcache, 1); 818 counter_u64_add(numdrops, 1); 819 return (NULL); 820 } 821 return (cache_alloc_uma(len, ts)); 822 } 823 824 static void 825 cache_free(struct namecache *ncp) 826 { 827 828 MPASS(ncp != NULL); 829 if ((ncp->nc_flag & NCF_DVDROP) != 0) { 830 cache_drop_vnode(ncp->nc_dvp); 831 } 832 cache_free_uma(ncp); 833 atomic_subtract_long(&numcache, 1); 834 } 835 836 static void 837 cache_free_batch(struct cache_freebatch *batch) 838 { 839 struct namecache *ncp, *nnp; 840 int i; 841 842 i = 0; 843 if (TAILQ_EMPTY(batch)) 844 goto out; 845 TAILQ_FOREACH_SAFE(ncp, batch, nc_dst, nnp) { 846 if ((ncp->nc_flag & NCF_DVDROP) != 0) { 847 cache_drop_vnode(ncp->nc_dvp); 848 } 849 cache_free_uma(ncp); 850 i++; 851 } 852 atomic_subtract_long(&numcache, i); 853 out: 854 SDT_PROBE1(vfs, namecache, purge, batch, i); 855 } 856 857 /* 858 * Hashing. 859 * 860 * The code was made to use FNV in 2001 and this choice needs to be revisited. 861 * 862 * Short summary of the difficulty: 863 * The longest name which can be inserted is NAME_MAX characters in length (or 864 * 255 at the time of writing this comment), while majority of names used in 865 * practice are significantly shorter (mostly below 10). More importantly 866 * majority of lookups performed find names are even shorter than that. 867 * 868 * This poses a problem where hashes which do better than FNV past word size 869 * (or so) tend to come with additional overhead when finalizing the result, 870 * making them noticeably slower for the most commonly used range. 871 * 872 * Consider a path like: /usr/obj/usr/src/sys/amd64/GENERIC/vnode_if.c 873 * 874 * When looking it up the most time consuming part by a large margin (at least 875 * on amd64) is hashing. Replacing FNV with something which pessimizes short 876 * input would make the slowest part stand out even more. 877 */ 878 879 /* 880 * TODO: With the value stored we can do better than computing the hash based 881 * on the address. 882 */ 883 static void 884 cache_prehash(struct vnode *vp) 885 { 886 887 vp->v_nchash = fnv_32_buf(&vp, sizeof(vp), FNV1_32_INIT); 888 } 889 890 static uint32_t 891 cache_get_hash(char *name, u_char len, struct vnode *dvp) 892 { 893 894 return (fnv_32_buf(name, len, dvp->v_nchash)); 895 } 896 897 static uint32_t 898 cache_get_hash_iter_start(struct vnode *dvp) 899 { 900 901 return (dvp->v_nchash); 902 } 903 904 static uint32_t 905 cache_get_hash_iter(char c, uint32_t hash) 906 { 907 908 return (fnv_32_buf(&c, 1, hash)); 909 } 910 911 static uint32_t 912 cache_get_hash_iter_finish(uint32_t hash) 913 { 914 915 return (hash); 916 } 917 918 static inline struct nchashhead * 919 NCP2BUCKET(struct namecache *ncp) 920 { 921 uint32_t hash; 922 923 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 924 return (NCHHASH(hash)); 925 } 926 927 static inline struct mtx * 928 NCP2BUCKETLOCK(struct namecache *ncp) 929 { 930 uint32_t hash; 931 932 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp); 933 return (HASH2BUCKETLOCK(hash)); 934 } 935 936 #ifdef INVARIANTS 937 static void 938 cache_assert_bucket_locked(struct namecache *ncp) 939 { 940 struct mtx *blp; 941 942 blp = NCP2BUCKETLOCK(ncp); 943 mtx_assert(blp, MA_OWNED); 944 } 945 946 static void 947 cache_assert_bucket_unlocked(struct namecache *ncp) 948 { 949 struct mtx *blp; 950 951 blp = NCP2BUCKETLOCK(ncp); 952 mtx_assert(blp, MA_NOTOWNED); 953 } 954 #else 955 #define cache_assert_bucket_locked(x) do { } while (0) 956 #define cache_assert_bucket_unlocked(x) do { } while (0) 957 #endif 958 959 #define cache_sort_vnodes(x, y) _cache_sort_vnodes((void **)(x), (void **)(y)) 960 static void 961 _cache_sort_vnodes(void **p1, void **p2) 962 { 963 void *tmp; 964 965 MPASS(*p1 != NULL || *p2 != NULL); 966 967 if (*p1 > *p2) { 968 tmp = *p2; 969 *p2 = *p1; 970 *p1 = tmp; 971 } 972 } 973 974 static void 975 cache_lock_all_buckets(void) 976 { 977 u_int i; 978 979 for (i = 0; i < numbucketlocks; i++) 980 mtx_lock(&bucketlocks[i]); 981 } 982 983 static void 984 cache_unlock_all_buckets(void) 985 { 986 u_int i; 987 988 for (i = 0; i < numbucketlocks; i++) 989 mtx_unlock(&bucketlocks[i]); 990 } 991 992 static void 993 cache_lock_all_vnodes(void) 994 { 995 u_int i; 996 997 for (i = 0; i < numvnodelocks; i++) 998 mtx_lock(&vnodelocks[i]); 999 } 1000 1001 static void 1002 cache_unlock_all_vnodes(void) 1003 { 1004 u_int i; 1005 1006 for (i = 0; i < numvnodelocks; i++) 1007 mtx_unlock(&vnodelocks[i]); 1008 } 1009 1010 static int 1011 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 1012 { 1013 1014 cache_sort_vnodes(&vlp1, &vlp2); 1015 1016 if (vlp1 != NULL) { 1017 if (!mtx_trylock(vlp1)) 1018 return (EAGAIN); 1019 } 1020 if (!mtx_trylock(vlp2)) { 1021 if (vlp1 != NULL) 1022 mtx_unlock(vlp1); 1023 return (EAGAIN); 1024 } 1025 1026 return (0); 1027 } 1028 1029 static void 1030 cache_lock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 1031 { 1032 1033 MPASS(vlp1 != NULL || vlp2 != NULL); 1034 MPASS(vlp1 <= vlp2); 1035 1036 if (vlp1 != NULL) 1037 mtx_lock(vlp1); 1038 if (vlp2 != NULL) 1039 mtx_lock(vlp2); 1040 } 1041 1042 static void 1043 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2) 1044 { 1045 1046 MPASS(vlp1 != NULL || vlp2 != NULL); 1047 1048 if (vlp1 != NULL) 1049 mtx_unlock(vlp1); 1050 if (vlp2 != NULL) 1051 mtx_unlock(vlp2); 1052 } 1053 1054 static int 1055 sysctl_nchstats(SYSCTL_HANDLER_ARGS) 1056 { 1057 struct nchstats snap; 1058 1059 if (req->oldptr == NULL) 1060 return (SYSCTL_OUT(req, 0, sizeof(snap))); 1061 1062 snap = nchstats; 1063 snap.ncs_goodhits = counter_u64_fetch(numposhits); 1064 snap.ncs_neghits = counter_u64_fetch(numneghits); 1065 snap.ncs_badhits = counter_u64_fetch(numposzaps) + 1066 counter_u64_fetch(numnegzaps); 1067 snap.ncs_miss = counter_u64_fetch(nummisszap) + 1068 counter_u64_fetch(nummiss); 1069 1070 return (SYSCTL_OUT(req, &snap, sizeof(snap))); 1071 } 1072 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD | 1073 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU", 1074 "VFS cache effectiveness statistics"); 1075 1076 static void 1077 cache_recalc_neg_min(void) 1078 { 1079 1080 neg_min = (ncsize * ncnegminpct) / 100; 1081 } 1082 1083 static int 1084 sysctl_negminpct(SYSCTL_HANDLER_ARGS) 1085 { 1086 u_int val; 1087 int error; 1088 1089 val = ncnegminpct; 1090 error = sysctl_handle_int(oidp, &val, 0, req); 1091 if (error != 0 || req->newptr == NULL) 1092 return (error); 1093 1094 if (val == ncnegminpct) 1095 return (0); 1096 if (val < 0 || val > 99) 1097 return (EINVAL); 1098 ncnegminpct = val; 1099 cache_recalc_neg_min(); 1100 return (0); 1101 } 1102 1103 SYSCTL_PROC(_vfs_cache_param, OID_AUTO, negminpct, 1104 CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0, sysctl_negminpct, 1105 "I", "Negative entry \% of namecache capacity above which automatic eviction is allowed"); 1106 1107 #ifdef DEBUG_CACHE 1108 /* 1109 * Grab an atomic snapshot of the name cache hash chain lengths 1110 */ 1111 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, 1112 CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 1113 "hash table stats"); 1114 1115 static int 1116 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) 1117 { 1118 struct nchashhead *ncpp; 1119 struct namecache *ncp; 1120 int i, error, n_nchash, *cntbuf; 1121 1122 retry: 1123 n_nchash = nchash + 1; /* nchash is max index, not count */ 1124 if (req->oldptr == NULL) 1125 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); 1126 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK); 1127 cache_lock_all_buckets(); 1128 if (n_nchash != nchash + 1) { 1129 cache_unlock_all_buckets(); 1130 free(cntbuf, M_TEMP); 1131 goto retry; 1132 } 1133 /* Scan hash tables counting entries */ 1134 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++) 1135 CK_SLIST_FOREACH(ncp, ncpp, nc_hash) 1136 cntbuf[i]++; 1137 cache_unlock_all_buckets(); 1138 for (error = 0, i = 0; i < n_nchash; i++) 1139 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0) 1140 break; 1141 free(cntbuf, M_TEMP); 1142 return (error); 1143 } 1144 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| 1145 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", 1146 "nchash chain lengths"); 1147 1148 static int 1149 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) 1150 { 1151 int error; 1152 struct nchashhead *ncpp; 1153 struct namecache *ncp; 1154 int n_nchash; 1155 int count, maxlength, used, pct; 1156 1157 if (!req->oldptr) 1158 return SYSCTL_OUT(req, 0, 4 * sizeof(int)); 1159 1160 cache_lock_all_buckets(); 1161 n_nchash = nchash + 1; /* nchash is max index, not count */ 1162 used = 0; 1163 maxlength = 0; 1164 1165 /* Scan hash tables for applicable entries */ 1166 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { 1167 count = 0; 1168 CK_SLIST_FOREACH(ncp, ncpp, nc_hash) { 1169 count++; 1170 } 1171 if (count) 1172 used++; 1173 if (maxlength < count) 1174 maxlength = count; 1175 } 1176 n_nchash = nchash + 1; 1177 cache_unlock_all_buckets(); 1178 pct = (used * 100) / (n_nchash / 100); 1179 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); 1180 if (error) 1181 return (error); 1182 error = SYSCTL_OUT(req, &used, sizeof(used)); 1183 if (error) 1184 return (error); 1185 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); 1186 if (error) 1187 return (error); 1188 error = SYSCTL_OUT(req, &pct, sizeof(pct)); 1189 if (error) 1190 return (error); 1191 return (0); 1192 } 1193 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| 1194 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", 1195 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); 1196 #endif 1197 1198 /* 1199 * Negative entries management 1200 * 1201 * Various workloads create plenty of negative entries and barely use them 1202 * afterwards. Moreover malicious users can keep performing bogus lookups 1203 * adding even more entries. For example "make tinderbox" as of writing this 1204 * comment ends up with 2.6M namecache entries in total, 1.2M of which are 1205 * negative. 1206 * 1207 * As such, a rather aggressive eviction method is needed. The currently 1208 * employed method is a placeholder. 1209 * 1210 * Entries are split over numneglists separate lists, each of which is further 1211 * split into hot and cold entries. Entries get promoted after getting a hit. 1212 * Eviction happens on addition of new entry. 1213 */ 1214 static SYSCTL_NODE(_vfs_cache, OID_AUTO, neg, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 1215 "Name cache negative entry statistics"); 1216 1217 SYSCTL_ULONG(_vfs_cache_neg, OID_AUTO, count, CTLFLAG_RD, &numneg, 0, 1218 "Number of negative cache entries"); 1219 1220 static COUNTER_U64_DEFINE_EARLY(neg_created); 1221 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, created, CTLFLAG_RD, &neg_created, 1222 "Number of created negative entries"); 1223 1224 static COUNTER_U64_DEFINE_EARLY(neg_evicted); 1225 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evicted, CTLFLAG_RD, &neg_evicted, 1226 "Number of evicted negative entries"); 1227 1228 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_empty); 1229 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_empty, CTLFLAG_RD, 1230 &neg_evict_skipped_empty, 1231 "Number of times evicting failed due to lack of entries"); 1232 1233 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_missed); 1234 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_missed, CTLFLAG_RD, 1235 &neg_evict_skipped_missed, 1236 "Number of times evicting failed due to target entry disappearing"); 1237 1238 static COUNTER_U64_DEFINE_EARLY(neg_evict_skipped_contended); 1239 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, evict_skipped_contended, CTLFLAG_RD, 1240 &neg_evict_skipped_contended, 1241 "Number of times evicting failed due to contention"); 1242 1243 SYSCTL_COUNTER_U64(_vfs_cache_neg, OID_AUTO, hits, CTLFLAG_RD, &numneghits, 1244 "Number of cache hits (negative)"); 1245 1246 static int 1247 sysctl_neg_hot(SYSCTL_HANDLER_ARGS) 1248 { 1249 int i, out; 1250 1251 out = 0; 1252 for (i = 0; i < numneglists; i++) 1253 out += neglists[i].nl_hotnum; 1254 1255 return (SYSCTL_OUT(req, &out, sizeof(out))); 1256 } 1257 SYSCTL_PROC(_vfs_cache_neg, OID_AUTO, hot, CTLTYPE_INT | CTLFLAG_RD | 1258 CTLFLAG_MPSAFE, 0, 0, sysctl_neg_hot, "I", 1259 "Number of hot negative entries"); 1260 1261 static void 1262 cache_neg_init(struct namecache *ncp) 1263 { 1264 struct negstate *ns; 1265 1266 ncp->nc_flag |= NCF_NEGATIVE; 1267 ns = NCP2NEGSTATE(ncp); 1268 ns->neg_flag = 0; 1269 ns->neg_hit = 0; 1270 counter_u64_add(neg_created, 1); 1271 } 1272 1273 #define CACHE_NEG_PROMOTION_THRESH 2 1274 1275 static bool 1276 cache_neg_hit_prep(struct namecache *ncp) 1277 { 1278 struct negstate *ns; 1279 u_char n; 1280 1281 ns = NCP2NEGSTATE(ncp); 1282 n = atomic_load_char(&ns->neg_hit); 1283 for (;;) { 1284 if (n >= CACHE_NEG_PROMOTION_THRESH) 1285 return (false); 1286 if (atomic_fcmpset_8(&ns->neg_hit, &n, n + 1)) 1287 break; 1288 } 1289 return (n + 1 == CACHE_NEG_PROMOTION_THRESH); 1290 } 1291 1292 /* 1293 * Nothing to do here but it is provided for completeness as some 1294 * cache_neg_hit_prep callers may end up returning without even 1295 * trying to promote. 1296 */ 1297 #define cache_neg_hit_abort(ncp) do { } while (0) 1298 1299 static void 1300 cache_neg_hit_finish(struct namecache *ncp) 1301 { 1302 1303 SDT_PROBE2(vfs, namecache, lookup, hit__negative, ncp->nc_dvp, ncp->nc_name); 1304 counter_u64_add(numneghits, 1); 1305 } 1306 1307 /* 1308 * Move a negative entry to the hot list. 1309 */ 1310 static void 1311 cache_neg_promote_locked(struct namecache *ncp) 1312 { 1313 struct neglist *nl; 1314 struct negstate *ns; 1315 1316 ns = NCP2NEGSTATE(ncp); 1317 nl = NCP2NEGLIST(ncp); 1318 mtx_assert(&nl->nl_lock, MA_OWNED); 1319 if ((ns->neg_flag & NEG_HOT) == 0) { 1320 TAILQ_REMOVE(&nl->nl_list, ncp, nc_dst); 1321 TAILQ_INSERT_TAIL(&nl->nl_hotlist, ncp, nc_dst); 1322 nl->nl_hotnum++; 1323 ns->neg_flag |= NEG_HOT; 1324 } 1325 } 1326 1327 /* 1328 * Move a hot negative entry to the cold list. 1329 */ 1330 static void 1331 cache_neg_demote_locked(struct namecache *ncp) 1332 { 1333 struct neglist *nl; 1334 struct negstate *ns; 1335 1336 ns = NCP2NEGSTATE(ncp); 1337 nl = NCP2NEGLIST(ncp); 1338 mtx_assert(&nl->nl_lock, MA_OWNED); 1339 MPASS(ns->neg_flag & NEG_HOT); 1340 TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst); 1341 TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst); 1342 nl->nl_hotnum--; 1343 ns->neg_flag &= ~NEG_HOT; 1344 atomic_store_char(&ns->neg_hit, 0); 1345 } 1346 1347 /* 1348 * Move a negative entry to the hot list if it matches the lookup. 1349 * 1350 * We have to take locks, but they may be contended and in the worst 1351 * case we may need to go off CPU. We don't want to spin within the 1352 * smr section and we can't block with it. Exiting the section means 1353 * the found entry could have been evicted. We are going to look it 1354 * up again. 1355 */ 1356 static bool 1357 cache_neg_promote_cond(struct vnode *dvp, struct componentname *cnp, 1358 struct namecache *oncp, uint32_t hash) 1359 { 1360 struct namecache *ncp; 1361 struct neglist *nl; 1362 u_char nc_flag; 1363 1364 nl = NCP2NEGLIST(oncp); 1365 1366 mtx_lock(&nl->nl_lock); 1367 /* 1368 * For hash iteration. 1369 */ 1370 vfs_smr_enter(); 1371 1372 /* 1373 * Avoid all surprises by only succeeding if we got the same entry and 1374 * bailing completely otherwise. 1375 * XXX There are no provisions to keep the vnode around, meaning we may 1376 * end up promoting a negative entry for a *new* vnode and returning 1377 * ENOENT on its account. This is the error we want to return anyway 1378 * and promotion is harmless. 1379 * 1380 * In particular at this point there can be a new ncp which matches the 1381 * search but hashes to a different neglist. 1382 */ 1383 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1384 if (ncp == oncp) 1385 break; 1386 } 1387 1388 /* 1389 * No match to begin with. 1390 */ 1391 if (__predict_false(ncp == NULL)) { 1392 goto out_abort; 1393 } 1394 1395 /* 1396 * The newly found entry may be something different... 1397 */ 1398 if (!(ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1399 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))) { 1400 goto out_abort; 1401 } 1402 1403 /* 1404 * ... and not even negative. 1405 */ 1406 nc_flag = atomic_load_char(&ncp->nc_flag); 1407 if ((nc_flag & NCF_NEGATIVE) == 0) { 1408 goto out_abort; 1409 } 1410 1411 if (!cache_ncp_canuse(ncp)) { 1412 goto out_abort; 1413 } 1414 1415 cache_neg_promote_locked(ncp); 1416 cache_neg_hit_finish(ncp); 1417 vfs_smr_exit(); 1418 mtx_unlock(&nl->nl_lock); 1419 return (true); 1420 out_abort: 1421 vfs_smr_exit(); 1422 mtx_unlock(&nl->nl_lock); 1423 return (false); 1424 } 1425 1426 static void 1427 cache_neg_promote(struct namecache *ncp) 1428 { 1429 struct neglist *nl; 1430 1431 nl = NCP2NEGLIST(ncp); 1432 mtx_lock(&nl->nl_lock); 1433 cache_neg_promote_locked(ncp); 1434 mtx_unlock(&nl->nl_lock); 1435 } 1436 1437 static void 1438 cache_neg_insert(struct namecache *ncp) 1439 { 1440 struct neglist *nl; 1441 1442 MPASS(ncp->nc_flag & NCF_NEGATIVE); 1443 cache_assert_bucket_locked(ncp); 1444 nl = NCP2NEGLIST(ncp); 1445 mtx_lock(&nl->nl_lock); 1446 TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst); 1447 mtx_unlock(&nl->nl_lock); 1448 atomic_add_long(&numneg, 1); 1449 } 1450 1451 static void 1452 cache_neg_remove(struct namecache *ncp) 1453 { 1454 struct neglist *nl; 1455 struct negstate *ns; 1456 1457 cache_assert_bucket_locked(ncp); 1458 nl = NCP2NEGLIST(ncp); 1459 ns = NCP2NEGSTATE(ncp); 1460 mtx_lock(&nl->nl_lock); 1461 if ((ns->neg_flag & NEG_HOT) != 0) { 1462 TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst); 1463 nl->nl_hotnum--; 1464 } else { 1465 TAILQ_REMOVE(&nl->nl_list, ncp, nc_dst); 1466 } 1467 mtx_unlock(&nl->nl_lock); 1468 atomic_subtract_long(&numneg, 1); 1469 } 1470 1471 static struct neglist * 1472 cache_neg_evict_select_list(void) 1473 { 1474 struct neglist *nl; 1475 u_int c; 1476 1477 c = atomic_fetchadd_int(&neg_cycle, 1) + 1; 1478 nl = &neglists[c % numneglists]; 1479 if (!mtx_trylock(&nl->nl_evict_lock)) { 1480 counter_u64_add(neg_evict_skipped_contended, 1); 1481 return (NULL); 1482 } 1483 return (nl); 1484 } 1485 1486 static struct namecache * 1487 cache_neg_evict_select_entry(struct neglist *nl) 1488 { 1489 struct namecache *ncp, *lncp; 1490 struct negstate *ns, *lns; 1491 int i; 1492 1493 mtx_assert(&nl->nl_evict_lock, MA_OWNED); 1494 mtx_assert(&nl->nl_lock, MA_OWNED); 1495 ncp = TAILQ_FIRST(&nl->nl_list); 1496 if (ncp == NULL) 1497 return (NULL); 1498 lncp = ncp; 1499 lns = NCP2NEGSTATE(lncp); 1500 for (i = 1; i < 4; i++) { 1501 ncp = TAILQ_NEXT(ncp, nc_dst); 1502 if (ncp == NULL) 1503 break; 1504 ns = NCP2NEGSTATE(ncp); 1505 if (ns->neg_hit < lns->neg_hit) { 1506 lncp = ncp; 1507 lns = ns; 1508 } 1509 } 1510 return (lncp); 1511 } 1512 1513 static bool 1514 cache_neg_evict(void) 1515 { 1516 struct namecache *ncp, *ncp2; 1517 struct neglist *nl; 1518 struct vnode *dvp; 1519 struct mtx *dvlp; 1520 struct mtx *blp; 1521 uint32_t hash; 1522 u_char nlen; 1523 bool evicted; 1524 1525 nl = cache_neg_evict_select_list(); 1526 if (nl == NULL) { 1527 return (false); 1528 } 1529 1530 mtx_lock(&nl->nl_lock); 1531 ncp = TAILQ_FIRST(&nl->nl_hotlist); 1532 if (ncp != NULL) { 1533 cache_neg_demote_locked(ncp); 1534 } 1535 ncp = cache_neg_evict_select_entry(nl); 1536 if (ncp == NULL) { 1537 counter_u64_add(neg_evict_skipped_empty, 1); 1538 mtx_unlock(&nl->nl_lock); 1539 mtx_unlock(&nl->nl_evict_lock); 1540 return (false); 1541 } 1542 nlen = ncp->nc_nlen; 1543 dvp = ncp->nc_dvp; 1544 hash = cache_get_hash(ncp->nc_name, nlen, dvp); 1545 dvlp = VP2VNODELOCK(dvp); 1546 blp = HASH2BUCKETLOCK(hash); 1547 mtx_unlock(&nl->nl_lock); 1548 mtx_unlock(&nl->nl_evict_lock); 1549 mtx_lock(dvlp); 1550 mtx_lock(blp); 1551 /* 1552 * Note that since all locks were dropped above, the entry may be 1553 * gone or reallocated to be something else. 1554 */ 1555 CK_SLIST_FOREACH(ncp2, (NCHHASH(hash)), nc_hash) { 1556 if (ncp2 == ncp && ncp2->nc_dvp == dvp && 1557 ncp2->nc_nlen == nlen && (ncp2->nc_flag & NCF_NEGATIVE) != 0) 1558 break; 1559 } 1560 if (ncp2 == NULL) { 1561 counter_u64_add(neg_evict_skipped_missed, 1); 1562 ncp = NULL; 1563 evicted = false; 1564 } else { 1565 MPASS(dvlp == VP2VNODELOCK(ncp->nc_dvp)); 1566 MPASS(blp == NCP2BUCKETLOCK(ncp)); 1567 SDT_PROBE2(vfs, namecache, evict_negative, done, ncp->nc_dvp, 1568 ncp->nc_name); 1569 cache_zap_locked(ncp); 1570 counter_u64_add(neg_evicted, 1); 1571 evicted = true; 1572 } 1573 mtx_unlock(blp); 1574 mtx_unlock(dvlp); 1575 if (ncp != NULL) 1576 cache_free(ncp); 1577 return (evicted); 1578 } 1579 1580 /* 1581 * Maybe evict a negative entry to create more room. 1582 * 1583 * The ncnegfactor parameter limits what fraction of the total count 1584 * can comprise of negative entries. However, if the cache is just 1585 * warming up this leads to excessive evictions. As such, ncnegminpct 1586 * (recomputed to neg_min) dictates whether the above should be 1587 * applied. 1588 * 1589 * Try evicting if the cache is close to full capacity regardless of 1590 * other considerations. 1591 */ 1592 static bool 1593 cache_neg_evict_cond(u_long lnumcache) 1594 { 1595 u_long lnumneg; 1596 1597 if (ncsize - 1000 < lnumcache) 1598 goto out_evict; 1599 lnumneg = atomic_load_long(&numneg); 1600 if (lnumneg < neg_min) 1601 return (false); 1602 if (lnumneg * ncnegfactor < lnumcache) 1603 return (false); 1604 out_evict: 1605 return (cache_neg_evict()); 1606 } 1607 1608 /* 1609 * cache_zap_locked(): 1610 * 1611 * Removes a namecache entry from cache, whether it contains an actual 1612 * pointer to a vnode or if it is just a negative cache entry. 1613 */ 1614 static void 1615 cache_zap_locked(struct namecache *ncp) 1616 { 1617 struct nchashhead *ncpp; 1618 struct vnode *dvp, *vp; 1619 1620 dvp = ncp->nc_dvp; 1621 vp = ncp->nc_vp; 1622 1623 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1624 cache_assert_vnode_locked(vp); 1625 cache_assert_vnode_locked(dvp); 1626 cache_assert_bucket_locked(ncp); 1627 1628 cache_ncp_invalidate(ncp); 1629 1630 ncpp = NCP2BUCKET(ncp); 1631 CK_SLIST_REMOVE(ncpp, ncp, namecache, nc_hash); 1632 if (!(ncp->nc_flag & NCF_NEGATIVE)) { 1633 SDT_PROBE3(vfs, namecache, zap, done, dvp, ncp->nc_name, vp); 1634 TAILQ_REMOVE(&vp->v_cache_dst, ncp, nc_dst); 1635 if (ncp == vp->v_cache_dd) { 1636 atomic_store_ptr(&vp->v_cache_dd, NULL); 1637 } 1638 } else { 1639 SDT_PROBE2(vfs, namecache, zap_negative, done, dvp, ncp->nc_name); 1640 cache_neg_remove(ncp); 1641 } 1642 if (ncp->nc_flag & NCF_ISDOTDOT) { 1643 if (ncp == dvp->v_cache_dd) { 1644 atomic_store_ptr(&dvp->v_cache_dd, NULL); 1645 } 1646 } else { 1647 LIST_REMOVE(ncp, nc_src); 1648 if (LIST_EMPTY(&dvp->v_cache_src)) { 1649 ncp->nc_flag |= NCF_DVDROP; 1650 } 1651 } 1652 } 1653 1654 static void 1655 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) 1656 { 1657 struct mtx *blp; 1658 1659 MPASS(ncp->nc_dvp == vp); 1660 MPASS(ncp->nc_flag & NCF_NEGATIVE); 1661 cache_assert_vnode_locked(vp); 1662 1663 blp = NCP2BUCKETLOCK(ncp); 1664 mtx_lock(blp); 1665 cache_zap_locked(ncp); 1666 mtx_unlock(blp); 1667 } 1668 1669 static bool 1670 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, 1671 struct mtx **vlpp) 1672 { 1673 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock; 1674 struct mtx *blp; 1675 1676 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp); 1677 cache_assert_vnode_locked(vp); 1678 1679 if (ncp->nc_flag & NCF_NEGATIVE) { 1680 if (*vlpp != NULL) { 1681 mtx_unlock(*vlpp); 1682 *vlpp = NULL; 1683 } 1684 cache_zap_negative_locked_vnode_kl(ncp, vp); 1685 return (true); 1686 } 1687 1688 pvlp = VP2VNODELOCK(vp); 1689 blp = NCP2BUCKETLOCK(ncp); 1690 vlp1 = VP2VNODELOCK(ncp->nc_dvp); 1691 vlp2 = VP2VNODELOCK(ncp->nc_vp); 1692 1693 if (*vlpp == vlp1 || *vlpp == vlp2) { 1694 to_unlock = *vlpp; 1695 *vlpp = NULL; 1696 } else { 1697 if (*vlpp != NULL) { 1698 mtx_unlock(*vlpp); 1699 *vlpp = NULL; 1700 } 1701 cache_sort_vnodes(&vlp1, &vlp2); 1702 if (vlp1 == pvlp) { 1703 mtx_lock(vlp2); 1704 to_unlock = vlp2; 1705 } else { 1706 if (!mtx_trylock(vlp1)) 1707 goto out_relock; 1708 to_unlock = vlp1; 1709 } 1710 } 1711 mtx_lock(blp); 1712 cache_zap_locked(ncp); 1713 mtx_unlock(blp); 1714 if (to_unlock != NULL) 1715 mtx_unlock(to_unlock); 1716 return (true); 1717 1718 out_relock: 1719 mtx_unlock(vlp2); 1720 mtx_lock(vlp1); 1721 mtx_lock(vlp2); 1722 MPASS(*vlpp == NULL); 1723 *vlpp = vlp1; 1724 return (false); 1725 } 1726 1727 /* 1728 * If trylocking failed we can get here. We know enough to take all needed locks 1729 * in the right order and re-lookup the entry. 1730 */ 1731 static int 1732 cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, 1733 struct vnode *dvp, struct mtx *dvlp, struct mtx *vlp, uint32_t hash, 1734 struct mtx *blp) 1735 { 1736 struct namecache *rncp; 1737 struct mtx *rvlp; 1738 1739 cache_assert_bucket_unlocked(ncp); 1740 1741 cache_sort_vnodes(&dvlp, &vlp); 1742 cache_lock_vnodes(dvlp, vlp); 1743 mtx_lock(blp); 1744 CK_SLIST_FOREACH(rncp, (NCHHASH(hash)), nc_hash) { 1745 if (rncp == ncp && rncp->nc_dvp == dvp && 1746 rncp->nc_nlen == cnp->cn_namelen && 1747 !bcmp(rncp->nc_name, cnp->cn_nameptr, rncp->nc_nlen)) 1748 break; 1749 } 1750 1751 if (rncp == NULL) 1752 goto out_mismatch; 1753 1754 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1755 rvlp = VP2VNODELOCK(rncp->nc_vp); 1756 else 1757 rvlp = NULL; 1758 if (rvlp != vlp) 1759 goto out_mismatch; 1760 1761 cache_zap_locked(rncp); 1762 mtx_unlock(blp); 1763 cache_unlock_vnodes(dvlp, vlp); 1764 atomic_add_long(&zap_bucket_relock_success, 1); 1765 return (0); 1766 1767 out_mismatch: 1768 mtx_unlock(blp); 1769 cache_unlock_vnodes(dvlp, vlp); 1770 return (EAGAIN); 1771 } 1772 1773 static int __noinline 1774 cache_zap_locked_bucket(struct namecache *ncp, struct componentname *cnp, 1775 uint32_t hash, struct mtx *blp) 1776 { 1777 struct mtx *dvlp, *vlp; 1778 struct vnode *dvp; 1779 1780 cache_assert_bucket_locked(ncp); 1781 1782 dvlp = VP2VNODELOCK(ncp->nc_dvp); 1783 vlp = NULL; 1784 if (!(ncp->nc_flag & NCF_NEGATIVE)) 1785 vlp = VP2VNODELOCK(ncp->nc_vp); 1786 if (cache_trylock_vnodes(dvlp, vlp) == 0) { 1787 cache_zap_locked(ncp); 1788 mtx_unlock(blp); 1789 cache_unlock_vnodes(dvlp, vlp); 1790 return (0); 1791 } 1792 1793 dvp = ncp->nc_dvp; 1794 mtx_unlock(blp); 1795 return (cache_zap_unlocked_bucket(ncp, cnp, dvp, dvlp, vlp, hash, blp)); 1796 } 1797 1798 static __noinline int 1799 cache_remove_cnp(struct vnode *dvp, struct componentname *cnp) 1800 { 1801 struct namecache *ncp; 1802 struct mtx *blp; 1803 struct mtx *dvlp, *dvlp2; 1804 uint32_t hash; 1805 int error; 1806 1807 if (cnp->cn_namelen == 2 && 1808 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') { 1809 dvlp = VP2VNODELOCK(dvp); 1810 dvlp2 = NULL; 1811 mtx_lock(dvlp); 1812 retry_dotdot: 1813 ncp = dvp->v_cache_dd; 1814 if (ncp == NULL) { 1815 mtx_unlock(dvlp); 1816 if (dvlp2 != NULL) 1817 mtx_unlock(dvlp2); 1818 SDT_PROBE2(vfs, namecache, removecnp, miss, dvp, cnp); 1819 return (0); 1820 } 1821 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1822 if (!cache_zap_locked_vnode_kl2(ncp, dvp, &dvlp2)) 1823 goto retry_dotdot; 1824 MPASS(dvp->v_cache_dd == NULL); 1825 mtx_unlock(dvlp); 1826 if (dvlp2 != NULL) 1827 mtx_unlock(dvlp2); 1828 cache_free(ncp); 1829 } else { 1830 atomic_store_ptr(&dvp->v_cache_dd, NULL); 1831 mtx_unlock(dvlp); 1832 if (dvlp2 != NULL) 1833 mtx_unlock(dvlp2); 1834 } 1835 SDT_PROBE2(vfs, namecache, removecnp, hit, dvp, cnp); 1836 return (1); 1837 } 1838 1839 /* 1840 * XXX note that access here is completely unlocked with no provisions 1841 * to keep the hash allocated. If one is sufficiently unlucky a 1842 * parallel cache resize can reallocate the hash, unmap backing pages 1843 * and cause the empty check below to fault. 1844 * 1845 * Fixing this has epsilon priority, but can be done with no overhead 1846 * for this codepath with sufficient effort. 1847 */ 1848 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 1849 blp = HASH2BUCKETLOCK(hash); 1850 retry: 1851 if (CK_SLIST_EMPTY(NCHHASH(hash))) 1852 goto out_no_entry; 1853 1854 mtx_lock(blp); 1855 1856 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 1857 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 1858 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 1859 break; 1860 } 1861 1862 if (ncp == NULL) { 1863 mtx_unlock(blp); 1864 goto out_no_entry; 1865 } 1866 1867 error = cache_zap_locked_bucket(ncp, cnp, hash, blp); 1868 if (__predict_false(error != 0)) { 1869 atomic_add_long(&zap_bucket_fail, 1); 1870 goto retry; 1871 } 1872 counter_u64_add(numposzaps, 1); 1873 SDT_PROBE2(vfs, namecache, removecnp, hit, dvp, cnp); 1874 cache_free(ncp); 1875 return (1); 1876 out_no_entry: 1877 counter_u64_add(nummisszap, 1); 1878 SDT_PROBE2(vfs, namecache, removecnp, miss, dvp, cnp); 1879 return (0); 1880 } 1881 1882 static int __noinline 1883 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1884 struct timespec *tsp, int *ticksp) 1885 { 1886 int ltype; 1887 1888 *vpp = dvp; 1889 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp); 1890 if (tsp != NULL) 1891 timespecclear(tsp); 1892 if (ticksp != NULL) 1893 *ticksp = ticks; 1894 vrefact(*vpp); 1895 /* 1896 * When we lookup "." we still can be asked to lock it 1897 * differently... 1898 */ 1899 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 1900 if (ltype != VOP_ISLOCKED(*vpp)) { 1901 if (ltype == LK_EXCLUSIVE) { 1902 vn_lock(*vpp, LK_UPGRADE | LK_RETRY); 1903 if (VN_IS_DOOMED((*vpp))) { 1904 /* forced unmount */ 1905 vrele(*vpp); 1906 *vpp = NULL; 1907 return (ENOENT); 1908 } 1909 } else 1910 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); 1911 } 1912 return (-1); 1913 } 1914 1915 static int __noinline 1916 cache_lookup_dotdot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 1917 struct timespec *tsp, int *ticksp) 1918 { 1919 struct namecache_ts *ncp_ts; 1920 struct namecache *ncp; 1921 struct mtx *dvlp; 1922 enum vgetstate vs; 1923 int error, ltype; 1924 bool whiteout; 1925 1926 MPASS((cnp->cn_flags & ISDOTDOT) != 0); 1927 1928 if ((cnp->cn_flags & MAKEENTRY) == 0) { 1929 cache_remove_cnp(dvp, cnp); 1930 return (0); 1931 } 1932 1933 retry: 1934 dvlp = VP2VNODELOCK(dvp); 1935 mtx_lock(dvlp); 1936 ncp = dvp->v_cache_dd; 1937 if (ncp == NULL) { 1938 SDT_PROBE2(vfs, namecache, lookup, miss, dvp, ".."); 1939 mtx_unlock(dvlp); 1940 return (0); 1941 } 1942 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) { 1943 if (ncp->nc_flag & NCF_NEGATIVE) 1944 *vpp = NULL; 1945 else 1946 *vpp = ncp->nc_vp; 1947 } else 1948 *vpp = ncp->nc_dvp; 1949 if (*vpp == NULL) 1950 goto negative_success; 1951 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..", *vpp); 1952 cache_out_ts(ncp, tsp, ticksp); 1953 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == 1954 NCF_DTS && tsp != NULL) { 1955 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 1956 *tsp = ncp_ts->nc_dotdottime; 1957 } 1958 1959 MPASS(dvp != *vpp); 1960 ltype = VOP_ISLOCKED(dvp); 1961 VOP_UNLOCK(dvp); 1962 vs = vget_prep(*vpp); 1963 mtx_unlock(dvlp); 1964 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 1965 vn_lock(dvp, ltype | LK_RETRY); 1966 if (VN_IS_DOOMED(dvp)) { 1967 if (error == 0) 1968 vput(*vpp); 1969 *vpp = NULL; 1970 return (ENOENT); 1971 } 1972 if (error) { 1973 *vpp = NULL; 1974 goto retry; 1975 } 1976 return (-1); 1977 negative_success: 1978 if (__predict_false(cnp->cn_nameiop == CREATE)) { 1979 if (cnp->cn_flags & ISLASTCN) { 1980 counter_u64_add(numnegzaps, 1); 1981 cache_zap_negative_locked_vnode_kl(ncp, dvp); 1982 mtx_unlock(dvlp); 1983 cache_free(ncp); 1984 return (0); 1985 } 1986 } 1987 1988 whiteout = (ncp->nc_flag & NCF_WHITE); 1989 cache_out_ts(ncp, tsp, ticksp); 1990 if (cache_neg_hit_prep(ncp)) 1991 cache_neg_promote(ncp); 1992 else 1993 cache_neg_hit_finish(ncp); 1994 mtx_unlock(dvlp); 1995 if (whiteout) 1996 cnp->cn_flags |= ISWHITEOUT; 1997 return (ENOENT); 1998 } 1999 2000 /** 2001 * Lookup a name in the name cache 2002 * 2003 * # Arguments 2004 * 2005 * - dvp: Parent directory in which to search. 2006 * - vpp: Return argument. Will contain desired vnode on cache hit. 2007 * - cnp: Parameters of the name search. The most interesting bits of 2008 * the cn_flags field have the following meanings: 2009 * - MAKEENTRY: If clear, free an entry from the cache rather than look 2010 * it up. 2011 * - ISDOTDOT: Must be set if and only if cn_nameptr == ".." 2012 * - tsp: Return storage for cache timestamp. On a successful (positive 2013 * or negative) lookup, tsp will be filled with any timespec that 2014 * was stored when this cache entry was created. However, it will 2015 * be clear for "." entries. 2016 * - ticks: Return storage for alternate cache timestamp. On a successful 2017 * (positive or negative) lookup, it will contain the ticks value 2018 * that was current when the cache entry was created, unless cnp 2019 * was ".". 2020 * 2021 * Either both tsp and ticks have to be provided or neither of them. 2022 * 2023 * # Returns 2024 * 2025 * - -1: A positive cache hit. vpp will contain the desired vnode. 2026 * - ENOENT: A negative cache hit, or dvp was recycled out from under us due 2027 * to a forced unmount. vpp will not be modified. If the entry 2028 * is a whiteout, then the ISWHITEOUT flag will be set in 2029 * cnp->cn_flags. 2030 * - 0: A cache miss. vpp will not be modified. 2031 * 2032 * # Locking 2033 * 2034 * On a cache hit, vpp will be returned locked and ref'd. If we're looking up 2035 * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the 2036 * lock is not recursively acquired. 2037 */ 2038 static int __noinline 2039 cache_lookup_fallback(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 2040 struct timespec *tsp, int *ticksp) 2041 { 2042 struct namecache *ncp; 2043 struct mtx *blp; 2044 uint32_t hash; 2045 enum vgetstate vs; 2046 int error; 2047 bool whiteout; 2048 2049 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 2050 MPASS((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) != 0); 2051 2052 retry: 2053 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 2054 blp = HASH2BUCKETLOCK(hash); 2055 mtx_lock(blp); 2056 2057 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 2058 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 2059 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 2060 break; 2061 } 2062 2063 if (__predict_false(ncp == NULL)) { 2064 mtx_unlock(blp); 2065 SDT_PROBE2(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr); 2066 counter_u64_add(nummiss, 1); 2067 return (0); 2068 } 2069 2070 if (ncp->nc_flag & NCF_NEGATIVE) 2071 goto negative_success; 2072 2073 counter_u64_add(numposhits, 1); 2074 *vpp = ncp->nc_vp; 2075 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp); 2076 cache_out_ts(ncp, tsp, ticksp); 2077 MPASS(dvp != *vpp); 2078 vs = vget_prep(*vpp); 2079 mtx_unlock(blp); 2080 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 2081 if (error) { 2082 *vpp = NULL; 2083 goto retry; 2084 } 2085 return (-1); 2086 negative_success: 2087 /* 2088 * We don't get here with regular lookup apart from corner cases. 2089 */ 2090 if (__predict_true(cnp->cn_nameiop == CREATE)) { 2091 if (cnp->cn_flags & ISLASTCN) { 2092 counter_u64_add(numnegzaps, 1); 2093 error = cache_zap_locked_bucket(ncp, cnp, hash, blp); 2094 if (__predict_false(error != 0)) { 2095 atomic_add_long(&zap_bucket_fail2, 1); 2096 goto retry; 2097 } 2098 cache_free(ncp); 2099 return (0); 2100 } 2101 } 2102 2103 whiteout = (ncp->nc_flag & NCF_WHITE); 2104 cache_out_ts(ncp, tsp, ticksp); 2105 if (cache_neg_hit_prep(ncp)) 2106 cache_neg_promote(ncp); 2107 else 2108 cache_neg_hit_finish(ncp); 2109 mtx_unlock(blp); 2110 if (whiteout) 2111 cnp->cn_flags |= ISWHITEOUT; 2112 return (ENOENT); 2113 } 2114 2115 int 2116 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, 2117 struct timespec *tsp, int *ticksp) 2118 { 2119 struct namecache *ncp; 2120 uint32_t hash; 2121 enum vgetstate vs; 2122 int error; 2123 bool whiteout, neg_promote; 2124 u_short nc_flag; 2125 2126 MPASS((tsp == NULL && ticksp == NULL) || (tsp != NULL && ticksp != NULL)); 2127 2128 #ifdef DEBUG_CACHE 2129 if (__predict_false(!doingcache)) { 2130 cnp->cn_flags &= ~MAKEENTRY; 2131 return (0); 2132 } 2133 #endif 2134 2135 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 2136 if (cnp->cn_namelen == 1) 2137 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp)); 2138 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') 2139 return (cache_lookup_dotdot(dvp, vpp, cnp, tsp, ticksp)); 2140 } 2141 2142 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 2143 2144 if ((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) == 0) { 2145 cache_remove_cnp(dvp, cnp); 2146 return (0); 2147 } 2148 2149 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 2150 vfs_smr_enter(); 2151 2152 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 2153 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 2154 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 2155 break; 2156 } 2157 2158 if (__predict_false(ncp == NULL)) { 2159 vfs_smr_exit(); 2160 SDT_PROBE2(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr); 2161 counter_u64_add(nummiss, 1); 2162 return (0); 2163 } 2164 2165 nc_flag = atomic_load_char(&ncp->nc_flag); 2166 if (nc_flag & NCF_NEGATIVE) 2167 goto negative_success; 2168 2169 counter_u64_add(numposhits, 1); 2170 *vpp = ncp->nc_vp; 2171 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp); 2172 cache_out_ts(ncp, tsp, ticksp); 2173 MPASS(dvp != *vpp); 2174 if (!cache_ncp_canuse(ncp)) { 2175 vfs_smr_exit(); 2176 *vpp = NULL; 2177 goto out_fallback; 2178 } 2179 vs = vget_prep_smr(*vpp); 2180 vfs_smr_exit(); 2181 if (__predict_false(vs == VGET_NONE)) { 2182 *vpp = NULL; 2183 goto out_fallback; 2184 } 2185 error = vget_finish(*vpp, cnp->cn_lkflags, vs); 2186 if (error) { 2187 *vpp = NULL; 2188 goto out_fallback; 2189 } 2190 return (-1); 2191 negative_success: 2192 if (cnp->cn_nameiop == CREATE) { 2193 if (cnp->cn_flags & ISLASTCN) { 2194 vfs_smr_exit(); 2195 goto out_fallback; 2196 } 2197 } 2198 2199 cache_out_ts(ncp, tsp, ticksp); 2200 whiteout = (atomic_load_char(&ncp->nc_flag) & NCF_WHITE); 2201 neg_promote = cache_neg_hit_prep(ncp); 2202 if (!cache_ncp_canuse(ncp)) { 2203 cache_neg_hit_abort(ncp); 2204 vfs_smr_exit(); 2205 goto out_fallback; 2206 } 2207 if (neg_promote) { 2208 vfs_smr_exit(); 2209 if (!cache_neg_promote_cond(dvp, cnp, ncp, hash)) 2210 goto out_fallback; 2211 } else { 2212 cache_neg_hit_finish(ncp); 2213 vfs_smr_exit(); 2214 } 2215 if (whiteout) 2216 cnp->cn_flags |= ISWHITEOUT; 2217 return (ENOENT); 2218 out_fallback: 2219 return (cache_lookup_fallback(dvp, vpp, cnp, tsp, ticksp)); 2220 } 2221 2222 struct celockstate { 2223 struct mtx *vlp[3]; 2224 struct mtx *blp[2]; 2225 }; 2226 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3)); 2227 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2)); 2228 2229 static inline void 2230 cache_celockstate_init(struct celockstate *cel) 2231 { 2232 2233 bzero(cel, sizeof(*cel)); 2234 } 2235 2236 static void 2237 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp, 2238 struct vnode *dvp) 2239 { 2240 struct mtx *vlp1, *vlp2; 2241 2242 MPASS(cel->vlp[0] == NULL); 2243 MPASS(cel->vlp[1] == NULL); 2244 MPASS(cel->vlp[2] == NULL); 2245 2246 MPASS(vp != NULL || dvp != NULL); 2247 2248 vlp1 = VP2VNODELOCK(vp); 2249 vlp2 = VP2VNODELOCK(dvp); 2250 cache_sort_vnodes(&vlp1, &vlp2); 2251 2252 if (vlp1 != NULL) { 2253 mtx_lock(vlp1); 2254 cel->vlp[0] = vlp1; 2255 } 2256 mtx_lock(vlp2); 2257 cel->vlp[1] = vlp2; 2258 } 2259 2260 static void 2261 cache_unlock_vnodes_cel(struct celockstate *cel) 2262 { 2263 2264 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL); 2265 2266 if (cel->vlp[0] != NULL) 2267 mtx_unlock(cel->vlp[0]); 2268 if (cel->vlp[1] != NULL) 2269 mtx_unlock(cel->vlp[1]); 2270 if (cel->vlp[2] != NULL) 2271 mtx_unlock(cel->vlp[2]); 2272 } 2273 2274 static bool 2275 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp) 2276 { 2277 struct mtx *vlp; 2278 bool ret; 2279 2280 cache_assert_vlp_locked(cel->vlp[0]); 2281 cache_assert_vlp_locked(cel->vlp[1]); 2282 MPASS(cel->vlp[2] == NULL); 2283 2284 MPASS(vp != NULL); 2285 vlp = VP2VNODELOCK(vp); 2286 2287 ret = true; 2288 if (vlp >= cel->vlp[1]) { 2289 mtx_lock(vlp); 2290 } else { 2291 if (mtx_trylock(vlp)) 2292 goto out; 2293 cache_unlock_vnodes_cel(cel); 2294 atomic_add_long(&cache_lock_vnodes_cel_3_failures, 1); 2295 if (vlp < cel->vlp[0]) { 2296 mtx_lock(vlp); 2297 mtx_lock(cel->vlp[0]); 2298 mtx_lock(cel->vlp[1]); 2299 } else { 2300 if (cel->vlp[0] != NULL) 2301 mtx_lock(cel->vlp[0]); 2302 mtx_lock(vlp); 2303 mtx_lock(cel->vlp[1]); 2304 } 2305 ret = false; 2306 } 2307 out: 2308 cel->vlp[2] = vlp; 2309 return (ret); 2310 } 2311 2312 static void 2313 cache_lock_buckets_cel(struct celockstate *cel, struct mtx *blp1, 2314 struct mtx *blp2) 2315 { 2316 2317 MPASS(cel->blp[0] == NULL); 2318 MPASS(cel->blp[1] == NULL); 2319 2320 cache_sort_vnodes(&blp1, &blp2); 2321 2322 if (blp1 != NULL) { 2323 mtx_lock(blp1); 2324 cel->blp[0] = blp1; 2325 } 2326 mtx_lock(blp2); 2327 cel->blp[1] = blp2; 2328 } 2329 2330 static void 2331 cache_unlock_buckets_cel(struct celockstate *cel) 2332 { 2333 2334 if (cel->blp[0] != NULL) 2335 mtx_unlock(cel->blp[0]); 2336 mtx_unlock(cel->blp[1]); 2337 } 2338 2339 /* 2340 * Lock part of the cache affected by the insertion. 2341 * 2342 * This means vnodelocks for dvp, vp and the relevant bucketlock. 2343 * However, insertion can result in removal of an old entry. In this 2344 * case we have an additional vnode and bucketlock pair to lock. 2345 * 2346 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while 2347 * preserving the locking order (smaller address first). 2348 */ 2349 static void 2350 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 2351 uint32_t hash) 2352 { 2353 struct namecache *ncp; 2354 struct mtx *blps[2]; 2355 u_char nc_flag; 2356 2357 blps[0] = HASH2BUCKETLOCK(hash); 2358 for (;;) { 2359 blps[1] = NULL; 2360 cache_lock_vnodes_cel(cel, dvp, vp); 2361 if (vp == NULL || vp->v_type != VDIR) 2362 break; 2363 ncp = atomic_load_consume_ptr(&vp->v_cache_dd); 2364 if (ncp == NULL) 2365 break; 2366 nc_flag = atomic_load_char(&ncp->nc_flag); 2367 if ((nc_flag & NCF_ISDOTDOT) == 0) 2368 break; 2369 MPASS(ncp->nc_dvp == vp); 2370 blps[1] = NCP2BUCKETLOCK(ncp); 2371 if ((nc_flag & NCF_NEGATIVE) != 0) 2372 break; 2373 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 2374 break; 2375 /* 2376 * All vnodes got re-locked. Re-validate the state and if 2377 * nothing changed we are done. Otherwise restart. 2378 */ 2379 if (ncp == vp->v_cache_dd && 2380 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 2381 blps[1] == NCP2BUCKETLOCK(ncp) && 2382 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 2383 break; 2384 cache_unlock_vnodes_cel(cel); 2385 cel->vlp[0] = NULL; 2386 cel->vlp[1] = NULL; 2387 cel->vlp[2] = NULL; 2388 } 2389 cache_lock_buckets_cel(cel, blps[0], blps[1]); 2390 } 2391 2392 static void 2393 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp, 2394 uint32_t hash) 2395 { 2396 struct namecache *ncp; 2397 struct mtx *blps[2]; 2398 u_char nc_flag; 2399 2400 blps[0] = HASH2BUCKETLOCK(hash); 2401 for (;;) { 2402 blps[1] = NULL; 2403 cache_lock_vnodes_cel(cel, dvp, vp); 2404 ncp = atomic_load_consume_ptr(&dvp->v_cache_dd); 2405 if (ncp == NULL) 2406 break; 2407 nc_flag = atomic_load_char(&ncp->nc_flag); 2408 if ((nc_flag & NCF_ISDOTDOT) == 0) 2409 break; 2410 MPASS(ncp->nc_dvp == dvp); 2411 blps[1] = NCP2BUCKETLOCK(ncp); 2412 if ((nc_flag & NCF_NEGATIVE) != 0) 2413 break; 2414 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp)) 2415 break; 2416 if (ncp == dvp->v_cache_dd && 2417 (ncp->nc_flag & NCF_ISDOTDOT) != 0 && 2418 blps[1] == NCP2BUCKETLOCK(ncp) && 2419 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2]) 2420 break; 2421 cache_unlock_vnodes_cel(cel); 2422 cel->vlp[0] = NULL; 2423 cel->vlp[1] = NULL; 2424 cel->vlp[2] = NULL; 2425 } 2426 cache_lock_buckets_cel(cel, blps[0], blps[1]); 2427 } 2428 2429 static void 2430 cache_enter_unlock(struct celockstate *cel) 2431 { 2432 2433 cache_unlock_buckets_cel(cel); 2434 cache_unlock_vnodes_cel(cel); 2435 } 2436 2437 static void __noinline 2438 cache_enter_dotdot_prep(struct vnode *dvp, struct vnode *vp, 2439 struct componentname *cnp) 2440 { 2441 struct celockstate cel; 2442 struct namecache *ncp; 2443 uint32_t hash; 2444 int len; 2445 2446 if (atomic_load_ptr(&dvp->v_cache_dd) == NULL) 2447 return; 2448 len = cnp->cn_namelen; 2449 cache_celockstate_init(&cel); 2450 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 2451 cache_enter_lock_dd(&cel, dvp, vp, hash); 2452 ncp = dvp->v_cache_dd; 2453 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT)) { 2454 KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent")); 2455 cache_zap_locked(ncp); 2456 } else { 2457 ncp = NULL; 2458 } 2459 atomic_store_ptr(&dvp->v_cache_dd, NULL); 2460 cache_enter_unlock(&cel); 2461 if (ncp != NULL) 2462 cache_free(ncp); 2463 } 2464 2465 /* 2466 * Add an entry to the cache. 2467 */ 2468 void 2469 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 2470 struct timespec *tsp, struct timespec *dtsp) 2471 { 2472 struct celockstate cel; 2473 struct namecache *ncp, *n2, *ndd; 2474 struct namecache_ts *ncp_ts; 2475 struct nchashhead *ncpp; 2476 uint32_t hash; 2477 int flag; 2478 int len; 2479 2480 KASSERT(cnp->cn_namelen <= NAME_MAX, 2481 ("%s: passed len %ld exceeds NAME_MAX (%d)", __func__, cnp->cn_namelen, 2482 NAME_MAX)); 2483 VNPASS(!VN_IS_DOOMED(dvp), dvp); 2484 VNPASS(dvp->v_type != VNON, dvp); 2485 if (vp != NULL) { 2486 VNPASS(!VN_IS_DOOMED(vp), vp); 2487 VNPASS(vp->v_type != VNON, vp); 2488 } 2489 if (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') { 2490 KASSERT(dvp == vp, 2491 ("%s: different vnodes for dot entry (%p; %p)\n", __func__, 2492 dvp, vp)); 2493 } else { 2494 KASSERT(dvp != vp, 2495 ("%s: same vnode for non-dot entry [%s] (%p)\n", __func__, 2496 cnp->cn_nameptr, dvp)); 2497 } 2498 2499 #ifdef DEBUG_CACHE 2500 if (__predict_false(!doingcache)) 2501 return; 2502 #endif 2503 2504 flag = 0; 2505 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 2506 if (cnp->cn_namelen == 1) 2507 return; 2508 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 2509 cache_enter_dotdot_prep(dvp, vp, cnp); 2510 flag = NCF_ISDOTDOT; 2511 } 2512 } 2513 2514 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); 2515 if (ncp == NULL) 2516 return; 2517 2518 cache_celockstate_init(&cel); 2519 ndd = NULL; 2520 ncp_ts = NULL; 2521 2522 /* 2523 * Calculate the hash key and setup as much of the new 2524 * namecache entry as possible before acquiring the lock. 2525 */ 2526 ncp->nc_flag = flag | NCF_WIP; 2527 ncp->nc_vp = vp; 2528 if (vp == NULL) 2529 cache_neg_init(ncp); 2530 ncp->nc_dvp = dvp; 2531 if (tsp != NULL) { 2532 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc); 2533 ncp_ts->nc_time = *tsp; 2534 ncp_ts->nc_ticks = ticks; 2535 ncp_ts->nc_nc.nc_flag |= NCF_TS; 2536 if (dtsp != NULL) { 2537 ncp_ts->nc_dotdottime = *dtsp; 2538 ncp_ts->nc_nc.nc_flag |= NCF_DTS; 2539 } 2540 } 2541 len = ncp->nc_nlen = cnp->cn_namelen; 2542 hash = cache_get_hash(cnp->cn_nameptr, len, dvp); 2543 memcpy(ncp->nc_name, cnp->cn_nameptr, len); 2544 ncp->nc_name[len] = '\0'; 2545 cache_enter_lock(&cel, dvp, vp, hash); 2546 2547 /* 2548 * See if this vnode or negative entry is already in the cache 2549 * with this name. This can happen with concurrent lookups of 2550 * the same path name. 2551 */ 2552 ncpp = NCHHASH(hash); 2553 CK_SLIST_FOREACH(n2, ncpp, nc_hash) { 2554 if (n2->nc_dvp == dvp && 2555 n2->nc_nlen == cnp->cn_namelen && 2556 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { 2557 MPASS(cache_ncp_canuse(n2)); 2558 if ((n2->nc_flag & NCF_NEGATIVE) != 0) 2559 KASSERT(vp == NULL, 2560 ("%s: found entry pointing to a different vnode (%p != %p) ; name [%s]", 2561 __func__, NULL, vp, cnp->cn_nameptr)); 2562 else 2563 KASSERT(n2->nc_vp == vp, 2564 ("%s: found entry pointing to a different vnode (%p != %p) ; name [%s]", 2565 __func__, n2->nc_vp, vp, cnp->cn_nameptr)); 2566 /* 2567 * Entries are supposed to be immutable unless in the 2568 * process of getting destroyed. Accommodating for 2569 * changing timestamps is possible but not worth it. 2570 * This should be harmless in terms of correctness, in 2571 * the worst case resulting in an earlier expiration. 2572 * Alternatively, the found entry can be replaced 2573 * altogether. 2574 */ 2575 MPASS((n2->nc_flag & (NCF_TS | NCF_DTS)) == (ncp->nc_flag & (NCF_TS | NCF_DTS))); 2576 #if 0 2577 if (tsp != NULL) { 2578 KASSERT((n2->nc_flag & NCF_TS) != 0, 2579 ("no NCF_TS")); 2580 n2_ts = __containerof(n2, struct namecache_ts, nc_nc); 2581 n2_ts->nc_time = ncp_ts->nc_time; 2582 n2_ts->nc_ticks = ncp_ts->nc_ticks; 2583 if (dtsp != NULL) { 2584 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime; 2585 n2_ts->nc_nc.nc_flag |= NCF_DTS; 2586 } 2587 } 2588 #endif 2589 SDT_PROBE3(vfs, namecache, enter, duplicate, dvp, ncp->nc_name, 2590 vp); 2591 goto out_unlock_free; 2592 } 2593 } 2594 2595 if (flag == NCF_ISDOTDOT) { 2596 /* 2597 * See if we are trying to add .. entry, but some other lookup 2598 * has populated v_cache_dd pointer already. 2599 */ 2600 if (dvp->v_cache_dd != NULL) 2601 goto out_unlock_free; 2602 KASSERT(vp == NULL || vp->v_type == VDIR, 2603 ("wrong vnode type %p", vp)); 2604 atomic_thread_fence_rel(); 2605 atomic_store_ptr(&dvp->v_cache_dd, ncp); 2606 } 2607 2608 if (vp != NULL) { 2609 if (flag != NCF_ISDOTDOT) { 2610 /* 2611 * For this case, the cache entry maps both the 2612 * directory name in it and the name ".." for the 2613 * directory's parent. 2614 */ 2615 if ((ndd = vp->v_cache_dd) != NULL) { 2616 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) 2617 cache_zap_locked(ndd); 2618 else 2619 ndd = NULL; 2620 } 2621 atomic_thread_fence_rel(); 2622 atomic_store_ptr(&vp->v_cache_dd, ncp); 2623 } else if (vp->v_type != VDIR) { 2624 if (vp->v_cache_dd != NULL) { 2625 atomic_store_ptr(&vp->v_cache_dd, NULL); 2626 } 2627 } 2628 } 2629 2630 if (flag != NCF_ISDOTDOT) { 2631 if (LIST_EMPTY(&dvp->v_cache_src)) { 2632 cache_hold_vnode(dvp); 2633 } 2634 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 2635 } 2636 2637 /* 2638 * If the entry is "negative", we place it into the 2639 * "negative" cache queue, otherwise, we place it into the 2640 * destination vnode's cache entries queue. 2641 */ 2642 if (vp != NULL) { 2643 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 2644 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name, 2645 vp); 2646 } else { 2647 if (cnp->cn_flags & ISWHITEOUT) 2648 atomic_store_char(&ncp->nc_flag, ncp->nc_flag | NCF_WHITE); 2649 cache_neg_insert(ncp); 2650 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp, 2651 ncp->nc_name); 2652 } 2653 2654 /* 2655 * Insert the new namecache entry into the appropriate chain 2656 * within the cache entries table. 2657 */ 2658 CK_SLIST_INSERT_HEAD(ncpp, ncp, nc_hash); 2659 2660 atomic_thread_fence_rel(); 2661 /* 2662 * Mark the entry as fully constructed. 2663 * It is immutable past this point until its removal. 2664 */ 2665 atomic_store_char(&ncp->nc_flag, ncp->nc_flag & ~NCF_WIP); 2666 2667 cache_enter_unlock(&cel); 2668 if (ndd != NULL) 2669 cache_free(ndd); 2670 return; 2671 out_unlock_free: 2672 cache_enter_unlock(&cel); 2673 cache_free(ncp); 2674 return; 2675 } 2676 2677 /* 2678 * A variant of the above accepting flags. 2679 * 2680 * - VFS_CACHE_DROPOLD -- if a conflicting entry is found, drop it. 2681 * 2682 * TODO: this routine is a hack. It blindly removes the old entry, even if it 2683 * happens to match and it is doing it in an inefficient manner. It was added 2684 * to accommodate NFS which runs into a case where the target for a given name 2685 * may change from under it. Note this does nothing to solve the following 2686 * race: 2 callers of cache_enter_time_flags pass a different target vnode for 2687 * the same [dvp, cnp]. It may be argued that code doing this is broken. 2688 */ 2689 void 2690 cache_enter_time_flags(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, 2691 struct timespec *tsp, struct timespec *dtsp, int flags) 2692 { 2693 2694 MPASS((flags & ~(VFS_CACHE_DROPOLD)) == 0); 2695 2696 if (flags & VFS_CACHE_DROPOLD) 2697 cache_remove_cnp(dvp, cnp); 2698 cache_enter_time(dvp, vp, cnp, tsp, dtsp); 2699 } 2700 2701 static u_long 2702 cache_roundup_2(u_long val) 2703 { 2704 u_long res; 2705 2706 for (res = 1; res <= val; res <<= 1) 2707 continue; 2708 2709 return (res); 2710 } 2711 2712 static struct nchashhead * 2713 nchinittbl(u_long elements, u_long *hashmask) 2714 { 2715 struct nchashhead *hashtbl; 2716 u_long hashsize, i; 2717 2718 hashsize = cache_roundup_2(elements) / 2; 2719 2720 hashtbl = malloc(hashsize * sizeof(*hashtbl), M_VFSCACHE, M_WAITOK); 2721 for (i = 0; i < hashsize; i++) 2722 CK_SLIST_INIT(&hashtbl[i]); 2723 *hashmask = hashsize - 1; 2724 return (hashtbl); 2725 } 2726 2727 static void 2728 ncfreetbl(struct nchashhead *hashtbl) 2729 { 2730 2731 free(hashtbl, M_VFSCACHE); 2732 } 2733 2734 /* 2735 * Name cache initialization, from vfs_init() when we are booting 2736 */ 2737 static void 2738 nchinit(void *dummy __unused) 2739 { 2740 u_int i; 2741 2742 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL_SIZE, 2743 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2744 cache_zone_small_ts = uma_zcreate("STS VFS Cache", CACHE_ZONE_SMALL_TS_SIZE, 2745 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2746 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE_SIZE, 2747 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2748 cache_zone_large_ts = uma_zcreate("LTS VFS Cache", CACHE_ZONE_LARGE_TS_SIZE, 2749 NULL, NULL, NULL, NULL, CACHE_ZONE_ALIGNMENT, UMA_ZONE_ZINIT); 2750 2751 VFS_SMR_ZONE_SET(cache_zone_small); 2752 VFS_SMR_ZONE_SET(cache_zone_small_ts); 2753 VFS_SMR_ZONE_SET(cache_zone_large); 2754 VFS_SMR_ZONE_SET(cache_zone_large_ts); 2755 2756 ncsize = desiredvnodes * ncsizefactor; 2757 cache_recalc_neg_min(); 2758 nchashtbl = nchinittbl(desiredvnodes * 2, &nchash); 2759 ncbuckethash = cache_roundup_2(mp_ncpus * mp_ncpus) - 1; 2760 if (ncbuckethash < 7) /* arbitrarily chosen to avoid having one lock */ 2761 ncbuckethash = 7; 2762 if (ncbuckethash > nchash) 2763 ncbuckethash = nchash; 2764 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE, 2765 M_WAITOK | M_ZERO); 2766 for (i = 0; i < numbucketlocks; i++) 2767 mtx_init(&bucketlocks[i], "ncbuc", NULL, MTX_DUPOK | MTX_RECURSE); 2768 ncvnodehash = ncbuckethash; 2769 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE, 2770 M_WAITOK | M_ZERO); 2771 for (i = 0; i < numvnodelocks; i++) 2772 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE); 2773 2774 for (i = 0; i < numneglists; i++) { 2775 mtx_init(&neglists[i].nl_evict_lock, "ncnege", NULL, MTX_DEF); 2776 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF); 2777 TAILQ_INIT(&neglists[i].nl_list); 2778 TAILQ_INIT(&neglists[i].nl_hotlist); 2779 } 2780 } 2781 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); 2782 2783 void 2784 cache_vnode_init(struct vnode *vp) 2785 { 2786 2787 LIST_INIT(&vp->v_cache_src); 2788 TAILQ_INIT(&vp->v_cache_dst); 2789 vp->v_cache_dd = NULL; 2790 cache_prehash(vp); 2791 } 2792 2793 /* 2794 * Induce transient cache misses for lockless operation in cache_lookup() by 2795 * using a temporary hash table. 2796 * 2797 * This will force a fs lookup. 2798 * 2799 * Synchronisation is done in 2 steps, calling vfs_smr_synchronize each time 2800 * to observe all CPUs not performing the lookup. 2801 */ 2802 static void 2803 cache_changesize_set_temp(struct nchashhead *temptbl, u_long temphash) 2804 { 2805 2806 MPASS(temphash < nchash); 2807 /* 2808 * Change the size. The new size is smaller and can safely be used 2809 * against the existing table. All lookups which now hash wrong will 2810 * result in a cache miss, which all callers are supposed to know how 2811 * to handle. 2812 */ 2813 atomic_store_long(&nchash, temphash); 2814 atomic_thread_fence_rel(); 2815 vfs_smr_synchronize(); 2816 /* 2817 * At this point everyone sees the updated hash value, but they still 2818 * see the old table. 2819 */ 2820 atomic_store_ptr(&nchashtbl, temptbl); 2821 atomic_thread_fence_rel(); 2822 vfs_smr_synchronize(); 2823 /* 2824 * At this point everyone sees the updated table pointer and size pair. 2825 */ 2826 } 2827 2828 /* 2829 * Set the new hash table. 2830 * 2831 * Similarly to cache_changesize_set_temp(), this has to synchronize against 2832 * lockless operation in cache_lookup(). 2833 */ 2834 static void 2835 cache_changesize_set_new(struct nchashhead *new_tbl, u_long new_hash) 2836 { 2837 2838 MPASS(nchash < new_hash); 2839 /* 2840 * Change the pointer first. This wont result in out of bounds access 2841 * since the temporary table is guaranteed to be smaller. 2842 */ 2843 atomic_store_ptr(&nchashtbl, new_tbl); 2844 atomic_thread_fence_rel(); 2845 vfs_smr_synchronize(); 2846 /* 2847 * At this point everyone sees the updated pointer value, but they 2848 * still see the old size. 2849 */ 2850 atomic_store_long(&nchash, new_hash); 2851 atomic_thread_fence_rel(); 2852 vfs_smr_synchronize(); 2853 /* 2854 * At this point everyone sees the updated table pointer and size pair. 2855 */ 2856 } 2857 2858 void 2859 cache_changesize(u_long newmaxvnodes) 2860 { 2861 struct nchashhead *new_nchashtbl, *old_nchashtbl, *temptbl; 2862 u_long new_nchash, old_nchash, temphash; 2863 struct namecache *ncp; 2864 uint32_t hash; 2865 u_long newncsize; 2866 u_long i; 2867 2868 newncsize = newmaxvnodes * ncsizefactor; 2869 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2); 2870 if (newmaxvnodes < numbucketlocks) 2871 newmaxvnodes = numbucketlocks; 2872 2873 new_nchashtbl = nchinittbl(newmaxvnodes, &new_nchash); 2874 /* If same hash table size, nothing to do */ 2875 if (nchash == new_nchash) { 2876 ncfreetbl(new_nchashtbl); 2877 return; 2878 } 2879 2880 temptbl = nchinittbl(1, &temphash); 2881 2882 /* 2883 * Move everything from the old hash table to the new table. 2884 * None of the namecache entries in the table can be removed 2885 * because to do so, they have to be removed from the hash table. 2886 */ 2887 cache_lock_all_vnodes(); 2888 cache_lock_all_buckets(); 2889 old_nchashtbl = nchashtbl; 2890 old_nchash = nchash; 2891 cache_changesize_set_temp(temptbl, temphash); 2892 for (i = 0; i <= old_nchash; i++) { 2893 while ((ncp = CK_SLIST_FIRST(&old_nchashtbl[i])) != NULL) { 2894 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, 2895 ncp->nc_dvp); 2896 CK_SLIST_REMOVE(&old_nchashtbl[i], ncp, namecache, nc_hash); 2897 CK_SLIST_INSERT_HEAD(&new_nchashtbl[hash & new_nchash], ncp, nc_hash); 2898 } 2899 } 2900 ncsize = newncsize; 2901 cache_recalc_neg_min(); 2902 cache_changesize_set_new(new_nchashtbl, new_nchash); 2903 cache_unlock_all_buckets(); 2904 cache_unlock_all_vnodes(); 2905 ncfreetbl(old_nchashtbl); 2906 ncfreetbl(temptbl); 2907 } 2908 2909 /* 2910 * Remove all entries from and to a particular vnode. 2911 */ 2912 static void 2913 cache_purge_impl(struct vnode *vp) 2914 { 2915 struct cache_freebatch batch; 2916 struct namecache *ncp; 2917 struct mtx *vlp, *vlp2; 2918 2919 TAILQ_INIT(&batch); 2920 vlp = VP2VNODELOCK(vp); 2921 vlp2 = NULL; 2922 mtx_lock(vlp); 2923 retry: 2924 while (!LIST_EMPTY(&vp->v_cache_src)) { 2925 ncp = LIST_FIRST(&vp->v_cache_src); 2926 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2927 goto retry; 2928 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2929 } 2930 while (!TAILQ_EMPTY(&vp->v_cache_dst)) { 2931 ncp = TAILQ_FIRST(&vp->v_cache_dst); 2932 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2933 goto retry; 2934 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2935 } 2936 ncp = vp->v_cache_dd; 2937 if (ncp != NULL) { 2938 KASSERT(ncp->nc_flag & NCF_ISDOTDOT, 2939 ("lost dotdot link")); 2940 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2)) 2941 goto retry; 2942 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 2943 } 2944 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); 2945 mtx_unlock(vlp); 2946 if (vlp2 != NULL) 2947 mtx_unlock(vlp2); 2948 cache_free_batch(&batch); 2949 } 2950 2951 /* 2952 * Opportunistic check to see if there is anything to do. 2953 */ 2954 static bool 2955 cache_has_entries(struct vnode *vp) 2956 { 2957 2958 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) && 2959 atomic_load_ptr(&vp->v_cache_dd) == NULL) 2960 return (false); 2961 return (true); 2962 } 2963 2964 void 2965 cache_purge(struct vnode *vp) 2966 { 2967 2968 SDT_PROBE1(vfs, namecache, purge, done, vp); 2969 if (!cache_has_entries(vp)) 2970 return; 2971 cache_purge_impl(vp); 2972 } 2973 2974 /* 2975 * Only to be used by vgone. 2976 */ 2977 void 2978 cache_purge_vgone(struct vnode *vp) 2979 { 2980 struct mtx *vlp; 2981 2982 VNPASS(VN_IS_DOOMED(vp), vp); 2983 if (cache_has_entries(vp)) { 2984 cache_purge_impl(vp); 2985 return; 2986 } 2987 2988 /* 2989 * Serialize against a potential thread doing cache_purge. 2990 */ 2991 vlp = VP2VNODELOCK(vp); 2992 mtx_wait_unlocked(vlp); 2993 if (cache_has_entries(vp)) { 2994 cache_purge_impl(vp); 2995 return; 2996 } 2997 return; 2998 } 2999 3000 /* 3001 * Remove all negative entries for a particular directory vnode. 3002 */ 3003 void 3004 cache_purge_negative(struct vnode *vp) 3005 { 3006 struct cache_freebatch batch; 3007 struct namecache *ncp, *nnp; 3008 struct mtx *vlp; 3009 3010 SDT_PROBE1(vfs, namecache, purge_negative, done, vp); 3011 if (LIST_EMPTY(&vp->v_cache_src)) 3012 return; 3013 TAILQ_INIT(&batch); 3014 vlp = VP2VNODELOCK(vp); 3015 mtx_lock(vlp); 3016 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) { 3017 if (!(ncp->nc_flag & NCF_NEGATIVE)) 3018 continue; 3019 cache_zap_negative_locked_vnode_kl(ncp, vp); 3020 TAILQ_INSERT_TAIL(&batch, ncp, nc_dst); 3021 } 3022 mtx_unlock(vlp); 3023 cache_free_batch(&batch); 3024 } 3025 3026 /* 3027 * Entry points for modifying VOP operations. 3028 */ 3029 void 3030 cache_vop_rename(struct vnode *fdvp, struct vnode *fvp, struct vnode *tdvp, 3031 struct vnode *tvp, struct componentname *fcnp, struct componentname *tcnp) 3032 { 3033 3034 ASSERT_VOP_IN_SEQC(fdvp); 3035 ASSERT_VOP_IN_SEQC(fvp); 3036 ASSERT_VOP_IN_SEQC(tdvp); 3037 if (tvp != NULL) 3038 ASSERT_VOP_IN_SEQC(tvp); 3039 3040 cache_purge(fvp); 3041 if (tvp != NULL) { 3042 cache_purge(tvp); 3043 KASSERT(!cache_remove_cnp(tdvp, tcnp), 3044 ("%s: lingering negative entry", __func__)); 3045 } else { 3046 cache_remove_cnp(tdvp, tcnp); 3047 } 3048 3049 /* 3050 * TODO 3051 * 3052 * Historically renaming was always purging all revelang entries, 3053 * but that's quite wasteful. In particular turns out that in many cases 3054 * the target file is immediately accessed after rename, inducing a cache 3055 * miss. 3056 * 3057 * Recode this to reduce relocking and reuse the existing entry (if any) 3058 * instead of just removing it above and allocating a new one here. 3059 */ 3060 cache_enter(tdvp, fvp, tcnp); 3061 } 3062 3063 void 3064 cache_vop_rmdir(struct vnode *dvp, struct vnode *vp) 3065 { 3066 3067 ASSERT_VOP_IN_SEQC(dvp); 3068 ASSERT_VOP_IN_SEQC(vp); 3069 cache_purge(vp); 3070 } 3071 3072 #ifdef INVARIANTS 3073 /* 3074 * Validate that if an entry exists it matches. 3075 */ 3076 void 3077 cache_validate(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) 3078 { 3079 struct namecache *ncp; 3080 struct mtx *blp; 3081 uint32_t hash; 3082 3083 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); 3084 if (CK_SLIST_EMPTY(NCHHASH(hash))) 3085 return; 3086 blp = HASH2BUCKETLOCK(hash); 3087 mtx_lock(blp); 3088 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 3089 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 3090 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) { 3091 if (ncp->nc_vp != vp) 3092 panic("%s: mismatch (%p != %p); ncp %p [%s] dvp %p\n", 3093 __func__, vp, ncp->nc_vp, ncp, ncp->nc_name, ncp->nc_dvp); 3094 } 3095 } 3096 mtx_unlock(blp); 3097 } 3098 3099 void 3100 cache_assert_no_entries(struct vnode *vp) 3101 { 3102 3103 VNPASS(TAILQ_EMPTY(&vp->v_cache_dst), vp); 3104 VNPASS(LIST_EMPTY(&vp->v_cache_src), vp); 3105 VNPASS(vp->v_cache_dd == NULL, vp); 3106 } 3107 #endif 3108 3109 /* 3110 * Flush all entries referencing a particular filesystem. 3111 */ 3112 void 3113 cache_purgevfs(struct mount *mp) 3114 { 3115 struct vnode *vp, *mvp; 3116 size_t visited __sdt_used, purged __sdt_used; 3117 3118 visited = purged = 0; 3119 /* 3120 * Somewhat wasteful iteration over all vnodes. Would be better to 3121 * support filtering and avoid the interlock to begin with. 3122 */ 3123 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) { 3124 visited++; 3125 if (!cache_has_entries(vp)) { 3126 VI_UNLOCK(vp); 3127 continue; 3128 } 3129 vholdl(vp); 3130 VI_UNLOCK(vp); 3131 cache_purge(vp); 3132 purged++; 3133 vdrop(vp); 3134 } 3135 3136 SDT_PROBE3(vfs, namecache, purgevfs, done, mp, visited, purged); 3137 } 3138 3139 /* 3140 * Perform canonical checks and cache lookup and pass on to filesystem 3141 * through the vop_cachedlookup only if needed. 3142 */ 3143 3144 int 3145 vfs_cache_lookup(struct vop_lookup_args *ap) 3146 { 3147 struct vnode *dvp; 3148 int error; 3149 struct vnode **vpp = ap->a_vpp; 3150 struct componentname *cnp = ap->a_cnp; 3151 int flags = cnp->cn_flags; 3152 3153 *vpp = NULL; 3154 dvp = ap->a_dvp; 3155 3156 if (dvp->v_type != VDIR) 3157 return (ENOTDIR); 3158 3159 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 3160 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 3161 return (EROFS); 3162 3163 error = vn_dir_check_exec(dvp, cnp); 3164 if (error != 0) 3165 return (error); 3166 3167 error = cache_lookup(dvp, vpp, cnp, NULL, NULL); 3168 if (error == 0) 3169 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 3170 if (error == -1) 3171 return (0); 3172 return (error); 3173 } 3174 3175 /* Implementation of the getcwd syscall. */ 3176 int 3177 sys___getcwd(struct thread *td, struct __getcwd_args *uap) 3178 { 3179 char *buf, *retbuf; 3180 size_t buflen; 3181 int error; 3182 3183 buflen = uap->buflen; 3184 if (__predict_false(buflen < 2)) 3185 return (EINVAL); 3186 if (buflen > MAXPATHLEN) 3187 buflen = MAXPATHLEN; 3188 3189 buf = uma_zalloc(namei_zone, M_WAITOK); 3190 error = vn_getcwd(buf, &retbuf, &buflen); 3191 if (error == 0) 3192 error = copyout(retbuf, uap->buf, buflen); 3193 uma_zfree(namei_zone, buf); 3194 return (error); 3195 } 3196 3197 int 3198 vn_getcwd(char *buf, char **retbuf, size_t *buflen) 3199 { 3200 struct pwd *pwd; 3201 int error; 3202 3203 vfs_smr_enter(); 3204 pwd = pwd_get_smr(); 3205 error = vn_fullpath_any_smr(pwd->pwd_cdir, pwd->pwd_rdir, buf, retbuf, 3206 buflen, 0); 3207 VFS_SMR_ASSERT_NOT_ENTERED(); 3208 if (error < 0) { 3209 pwd = pwd_hold(curthread); 3210 error = vn_fullpath_any(pwd->pwd_cdir, pwd->pwd_rdir, buf, 3211 retbuf, buflen); 3212 pwd_drop(pwd); 3213 } 3214 3215 #ifdef KTRACE 3216 if (KTRPOINT(curthread, KTR_NAMEI) && error == 0) 3217 ktrnamei(*retbuf); 3218 #endif 3219 return (error); 3220 } 3221 3222 /* 3223 * Canonicalize a path by walking it forward and back. 3224 * 3225 * BUGS: 3226 * - Nothing guarantees the integrity of the entire chain. Consider the case 3227 * where the path "foo/bar/baz/qux" is passed, but "bar" is moved out of 3228 * "foo" into "quux" during the backwards walk. The result will be 3229 * "quux/bar/baz/qux", which could not have been obtained by an incremental 3230 * walk in userspace. Moreover, the path we return is inaccessible if the 3231 * calling thread lacks permission to traverse "quux". 3232 */ 3233 static int 3234 kern___realpathat(struct thread *td, int fd, const char *path, char *buf, 3235 size_t size, int flags, enum uio_seg pathseg) 3236 { 3237 struct nameidata nd; 3238 char *retbuf, *freebuf; 3239 int error; 3240 3241 if (flags != 0) 3242 return (EINVAL); 3243 NDINIT_ATRIGHTS(&nd, LOOKUP, FOLLOW | WANTPARENT | AUDITVNODE1, 3244 pathseg, path, fd, &cap_fstat_rights); 3245 if ((error = namei(&nd)) != 0) 3246 return (error); 3247 3248 if (nd.ni_vp->v_type == VREG && nd.ni_dvp->v_type != VDIR && 3249 (nd.ni_vp->v_vflag & VV_ROOT) != 0) { 3250 /* 3251 * This happens if vp is a file mount. The call to 3252 * vn_fullpath_hardlink can panic if path resolution can't be 3253 * handled without the directory. 3254 * 3255 * To resolve this, we find the vnode which was mounted on - 3256 * this should have a unique global path since we disallow 3257 * mounting on linked files. 3258 */ 3259 struct vnode *covered_vp; 3260 error = vn_lock(nd.ni_vp, LK_SHARED); 3261 if (error != 0) 3262 goto out; 3263 covered_vp = nd.ni_vp->v_mount->mnt_vnodecovered; 3264 vref(covered_vp); 3265 VOP_UNLOCK(nd.ni_vp); 3266 error = vn_fullpath(covered_vp, &retbuf, &freebuf); 3267 vrele(covered_vp); 3268 } else { 3269 error = vn_fullpath_hardlink(nd.ni_vp, nd.ni_dvp, nd.ni_cnd.cn_nameptr, 3270 nd.ni_cnd.cn_namelen, &retbuf, &freebuf, &size); 3271 } 3272 if (error == 0) { 3273 error = copyout(retbuf, buf, size); 3274 free(freebuf, M_TEMP); 3275 } 3276 out: 3277 vrele(nd.ni_vp); 3278 vrele(nd.ni_dvp); 3279 NDFREE_PNBUF(&nd); 3280 return (error); 3281 } 3282 3283 int 3284 sys___realpathat(struct thread *td, struct __realpathat_args *uap) 3285 { 3286 3287 return (kern___realpathat(td, uap->fd, uap->path, uap->buf, uap->size, 3288 uap->flags, UIO_USERSPACE)); 3289 } 3290 3291 /* 3292 * Retrieve the full filesystem path that correspond to a vnode from the name 3293 * cache (if available) 3294 */ 3295 int 3296 vn_fullpath(struct vnode *vp, char **retbuf, char **freebuf) 3297 { 3298 struct pwd *pwd; 3299 char *buf; 3300 size_t buflen; 3301 int error; 3302 3303 if (__predict_false(vp == NULL)) 3304 return (EINVAL); 3305 3306 buflen = MAXPATHLEN; 3307 buf = malloc(buflen, M_TEMP, M_WAITOK); 3308 vfs_smr_enter(); 3309 pwd = pwd_get_smr(); 3310 error = vn_fullpath_any_smr(vp, pwd->pwd_rdir, buf, retbuf, &buflen, 0); 3311 VFS_SMR_ASSERT_NOT_ENTERED(); 3312 if (error < 0) { 3313 pwd = pwd_hold(curthread); 3314 error = vn_fullpath_any(vp, pwd->pwd_rdir, buf, retbuf, &buflen); 3315 pwd_drop(pwd); 3316 } 3317 if (error == 0) 3318 *freebuf = buf; 3319 else 3320 free(buf, M_TEMP); 3321 return (error); 3322 } 3323 3324 /* 3325 * This function is similar to vn_fullpath, but it attempts to lookup the 3326 * pathname relative to the global root mount point. This is required for the 3327 * auditing sub-system, as audited pathnames must be absolute, relative to the 3328 * global root mount point. 3329 */ 3330 int 3331 vn_fullpath_global(struct vnode *vp, char **retbuf, char **freebuf) 3332 { 3333 char *buf; 3334 size_t buflen; 3335 int error; 3336 3337 if (__predict_false(vp == NULL)) 3338 return (EINVAL); 3339 buflen = MAXPATHLEN; 3340 buf = malloc(buflen, M_TEMP, M_WAITOK); 3341 vfs_smr_enter(); 3342 error = vn_fullpath_any_smr(vp, rootvnode, buf, retbuf, &buflen, 0); 3343 VFS_SMR_ASSERT_NOT_ENTERED(); 3344 if (error < 0) { 3345 error = vn_fullpath_any(vp, rootvnode, buf, retbuf, &buflen); 3346 } 3347 if (error == 0) 3348 *freebuf = buf; 3349 else 3350 free(buf, M_TEMP); 3351 return (error); 3352 } 3353 3354 static struct namecache * 3355 vn_dd_from_dst(struct vnode *vp) 3356 { 3357 struct namecache *ncp; 3358 3359 cache_assert_vnode_locked(vp); 3360 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) { 3361 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 3362 return (ncp); 3363 } 3364 return (NULL); 3365 } 3366 3367 int 3368 vn_vptocnp(struct vnode **vp, char *buf, size_t *buflen) 3369 { 3370 struct vnode *dvp; 3371 struct namecache *ncp; 3372 struct mtx *vlp; 3373 int error; 3374 3375 vlp = VP2VNODELOCK(*vp); 3376 mtx_lock(vlp); 3377 ncp = (*vp)->v_cache_dd; 3378 if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT) == 0) { 3379 KASSERT(ncp == vn_dd_from_dst(*vp), 3380 ("%s: mismatch for dd entry (%p != %p)", __func__, 3381 ncp, vn_dd_from_dst(*vp))); 3382 } else { 3383 ncp = vn_dd_from_dst(*vp); 3384 } 3385 if (ncp != NULL) { 3386 if (*buflen < ncp->nc_nlen) { 3387 mtx_unlock(vlp); 3388 vrele(*vp); 3389 counter_u64_add(numfullpathfail4, 1); 3390 error = ENOMEM; 3391 SDT_PROBE3(vfs, namecache, fullpath, return, error, 3392 vp, NULL); 3393 return (error); 3394 } 3395 *buflen -= ncp->nc_nlen; 3396 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 3397 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp, 3398 ncp->nc_name, vp); 3399 dvp = *vp; 3400 *vp = ncp->nc_dvp; 3401 vref(*vp); 3402 mtx_unlock(vlp); 3403 vrele(dvp); 3404 return (0); 3405 } 3406 SDT_PROBE1(vfs, namecache, fullpath, miss, vp); 3407 3408 mtx_unlock(vlp); 3409 vn_lock(*vp, LK_SHARED | LK_RETRY); 3410 error = VOP_VPTOCNP(*vp, &dvp, buf, buflen); 3411 vput(*vp); 3412 if (error) { 3413 counter_u64_add(numfullpathfail2, 1); 3414 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 3415 return (error); 3416 } 3417 3418 *vp = dvp; 3419 if (VN_IS_DOOMED(dvp)) { 3420 /* forced unmount */ 3421 vrele(dvp); 3422 error = ENOENT; 3423 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL); 3424 return (error); 3425 } 3426 /* 3427 * *vp has its use count incremented still. 3428 */ 3429 3430 return (0); 3431 } 3432 3433 /* 3434 * Resolve a directory to a pathname. 3435 * 3436 * The name of the directory can always be found in the namecache or fetched 3437 * from the filesystem. There is also guaranteed to be only one parent, meaning 3438 * we can just follow vnodes up until we find the root. 3439 * 3440 * The vnode must be referenced. 3441 */ 3442 static int 3443 vn_fullpath_dir(struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, 3444 size_t *len, size_t addend) 3445 { 3446 #ifdef KDTRACE_HOOKS 3447 struct vnode *startvp = vp; 3448 #endif 3449 struct vnode *vp1; 3450 size_t buflen; 3451 int error; 3452 bool slash_prefixed; 3453 3454 VNPASS(vp->v_type == VDIR || VN_IS_DOOMED(vp), vp); 3455 VNPASS(vp->v_usecount > 0, vp); 3456 3457 buflen = *len; 3458 3459 slash_prefixed = true; 3460 if (addend == 0) { 3461 MPASS(*len >= 2); 3462 buflen--; 3463 buf[buflen] = '\0'; 3464 slash_prefixed = false; 3465 } 3466 3467 error = 0; 3468 3469 SDT_PROBE1(vfs, namecache, fullpath, entry, vp); 3470 counter_u64_add(numfullpathcalls, 1); 3471 while (vp != rdir && vp != rootvnode) { 3472 /* 3473 * The vp vnode must be already fully constructed, 3474 * since it is either found in namecache or obtained 3475 * from VOP_VPTOCNP(). We may test for VV_ROOT safely 3476 * without obtaining the vnode lock. 3477 */ 3478 if ((vp->v_vflag & VV_ROOT) != 0) { 3479 vn_lock(vp, LK_RETRY | LK_SHARED); 3480 3481 /* 3482 * With the vnode locked, check for races with 3483 * unmount, forced or not. Note that we 3484 * already verified that vp is not equal to 3485 * the root vnode, which means that 3486 * mnt_vnodecovered can be NULL only for the 3487 * case of unmount. 3488 */ 3489 if (VN_IS_DOOMED(vp) || 3490 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL || 3491 vp1->v_mountedhere != vp->v_mount) { 3492 vput(vp); 3493 error = ENOENT; 3494 SDT_PROBE3(vfs, namecache, fullpath, return, 3495 error, vp, NULL); 3496 break; 3497 } 3498 3499 vref(vp1); 3500 vput(vp); 3501 vp = vp1; 3502 continue; 3503 } 3504 VNPASS(vp->v_type == VDIR || VN_IS_DOOMED(vp), vp); 3505 error = vn_vptocnp(&vp, buf, &buflen); 3506 if (error) 3507 break; 3508 if (buflen == 0) { 3509 vrele(vp); 3510 error = ENOMEM; 3511 SDT_PROBE3(vfs, namecache, fullpath, return, error, 3512 startvp, NULL); 3513 break; 3514 } 3515 buf[--buflen] = '/'; 3516 slash_prefixed = true; 3517 } 3518 if (error) 3519 return (error); 3520 if (!slash_prefixed) { 3521 if (buflen == 0) { 3522 vrele(vp); 3523 counter_u64_add(numfullpathfail4, 1); 3524 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM, 3525 startvp, NULL); 3526 return (ENOMEM); 3527 } 3528 buf[--buflen] = '/'; 3529 } 3530 counter_u64_add(numfullpathfound, 1); 3531 vrele(vp); 3532 3533 *retbuf = buf + buflen; 3534 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, *retbuf); 3535 *len -= buflen; 3536 *len += addend; 3537 return (0); 3538 } 3539 3540 /* 3541 * Resolve an arbitrary vnode to a pathname. 3542 * 3543 * Note 2 caveats: 3544 * - hardlinks are not tracked, thus if the vnode is not a directory this can 3545 * resolve to a different path than the one used to find it 3546 * - namecache is not mandatory, meaning names are not guaranteed to be added 3547 * (in which case resolving fails) 3548 */ 3549 static void __inline 3550 cache_rev_failed_impl(int *reason, int line) 3551 { 3552 3553 *reason = line; 3554 } 3555 #define cache_rev_failed(var) cache_rev_failed_impl((var), __LINE__) 3556 3557 static int 3558 vn_fullpath_any_smr(struct vnode *vp, struct vnode *rdir, char *buf, 3559 char **retbuf, size_t *buflen, size_t addend) 3560 { 3561 #ifdef KDTRACE_HOOKS 3562 struct vnode *startvp = vp; 3563 #endif 3564 struct vnode *tvp; 3565 struct mount *mp; 3566 struct namecache *ncp; 3567 size_t orig_buflen; 3568 int reason; 3569 int error; 3570 #ifdef KDTRACE_HOOKS 3571 int i; 3572 #endif 3573 seqc_t vp_seqc, tvp_seqc; 3574 u_char nc_flag; 3575 3576 VFS_SMR_ASSERT_ENTERED(); 3577 3578 if (!atomic_load_char(&cache_fast_lookup_enabled)) { 3579 vfs_smr_exit(); 3580 return (-1); 3581 } 3582 3583 orig_buflen = *buflen; 3584 3585 if (addend == 0) { 3586 MPASS(*buflen >= 2); 3587 *buflen -= 1; 3588 buf[*buflen] = '\0'; 3589 } 3590 3591 if (vp == rdir || vp == rootvnode) { 3592 if (addend == 0) { 3593 *buflen -= 1; 3594 buf[*buflen] = '/'; 3595 } 3596 goto out_ok; 3597 } 3598 3599 #ifdef KDTRACE_HOOKS 3600 i = 0; 3601 #endif 3602 error = -1; 3603 ncp = NULL; /* for sdt probe down below */ 3604 vp_seqc = vn_seqc_read_any(vp); 3605 if (seqc_in_modify(vp_seqc)) { 3606 cache_rev_failed(&reason); 3607 goto out_abort; 3608 } 3609 3610 for (;;) { 3611 #ifdef KDTRACE_HOOKS 3612 i++; 3613 #endif 3614 if ((vp->v_vflag & VV_ROOT) != 0) { 3615 mp = atomic_load_ptr(&vp->v_mount); 3616 if (mp == NULL) { 3617 cache_rev_failed(&reason); 3618 goto out_abort; 3619 } 3620 tvp = atomic_load_ptr(&mp->mnt_vnodecovered); 3621 tvp_seqc = vn_seqc_read_any(tvp); 3622 if (seqc_in_modify(tvp_seqc)) { 3623 cache_rev_failed(&reason); 3624 goto out_abort; 3625 } 3626 if (!vn_seqc_consistent(vp, vp_seqc)) { 3627 cache_rev_failed(&reason); 3628 goto out_abort; 3629 } 3630 vp = tvp; 3631 vp_seqc = tvp_seqc; 3632 continue; 3633 } 3634 ncp = atomic_load_consume_ptr(&vp->v_cache_dd); 3635 if (ncp == NULL) { 3636 cache_rev_failed(&reason); 3637 goto out_abort; 3638 } 3639 nc_flag = atomic_load_char(&ncp->nc_flag); 3640 if ((nc_flag & NCF_ISDOTDOT) != 0) { 3641 cache_rev_failed(&reason); 3642 goto out_abort; 3643 } 3644 if (ncp->nc_nlen >= *buflen) { 3645 cache_rev_failed(&reason); 3646 error = ENOMEM; 3647 goto out_abort; 3648 } 3649 *buflen -= ncp->nc_nlen; 3650 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen); 3651 *buflen -= 1; 3652 buf[*buflen] = '/'; 3653 tvp = ncp->nc_dvp; 3654 tvp_seqc = vn_seqc_read_any(tvp); 3655 if (seqc_in_modify(tvp_seqc)) { 3656 cache_rev_failed(&reason); 3657 goto out_abort; 3658 } 3659 if (!vn_seqc_consistent(vp, vp_seqc)) { 3660 cache_rev_failed(&reason); 3661 goto out_abort; 3662 } 3663 /* 3664 * Acquire fence provided by vn_seqc_read_any above. 3665 */ 3666 if (__predict_false(atomic_load_ptr(&vp->v_cache_dd) != ncp)) { 3667 cache_rev_failed(&reason); 3668 goto out_abort; 3669 } 3670 if (!cache_ncp_canuse(ncp)) { 3671 cache_rev_failed(&reason); 3672 goto out_abort; 3673 } 3674 vp = tvp; 3675 vp_seqc = tvp_seqc; 3676 if (vp == rdir || vp == rootvnode) 3677 break; 3678 } 3679 out_ok: 3680 vfs_smr_exit(); 3681 *retbuf = buf + *buflen; 3682 *buflen = orig_buflen - *buflen + addend; 3683 SDT_PROBE2(vfs, namecache, fullpath_smr, hit, startvp, *retbuf); 3684 return (0); 3685 3686 out_abort: 3687 *buflen = orig_buflen; 3688 SDT_PROBE4(vfs, namecache, fullpath_smr, miss, startvp, ncp, reason, i); 3689 vfs_smr_exit(); 3690 return (error); 3691 } 3692 3693 static int 3694 vn_fullpath_any(struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, 3695 size_t *buflen) 3696 { 3697 size_t orig_buflen, addend; 3698 int error; 3699 3700 if (*buflen < 2) 3701 return (EINVAL); 3702 3703 orig_buflen = *buflen; 3704 3705 vref(vp); 3706 addend = 0; 3707 if (vp->v_type != VDIR) { 3708 *buflen -= 1; 3709 buf[*buflen] = '\0'; 3710 error = vn_vptocnp(&vp, buf, buflen); 3711 if (error) 3712 return (error); 3713 if (*buflen == 0) { 3714 vrele(vp); 3715 return (ENOMEM); 3716 } 3717 *buflen -= 1; 3718 buf[*buflen] = '/'; 3719 addend = orig_buflen - *buflen; 3720 } 3721 3722 return (vn_fullpath_dir(vp, rdir, buf, retbuf, buflen, addend)); 3723 } 3724 3725 /* 3726 * Resolve an arbitrary vnode to a pathname (taking care of hardlinks). 3727 * 3728 * Since the namecache does not track hardlinks, the caller is expected to 3729 * first look up the target vnode with WANTPARENT flag passed to namei to get 3730 * dvp and vp. 3731 * 3732 * Then we have 2 cases: 3733 * - if the found vnode is a directory, the path can be constructed just by 3734 * following names up the chain 3735 * - otherwise we populate the buffer with the saved name and start resolving 3736 * from the parent 3737 */ 3738 int 3739 vn_fullpath_hardlink(struct vnode *vp, struct vnode *dvp, 3740 const char *hrdl_name, size_t hrdl_name_length, 3741 char **retbuf, char **freebuf, size_t *buflen) 3742 { 3743 char *buf, *tmpbuf; 3744 struct pwd *pwd; 3745 size_t addend; 3746 int error; 3747 __enum_uint8(vtype) type; 3748 3749 if (*buflen < 2) 3750 return (EINVAL); 3751 if (*buflen > MAXPATHLEN) 3752 *buflen = MAXPATHLEN; 3753 3754 buf = malloc(*buflen, M_TEMP, M_WAITOK); 3755 3756 addend = 0; 3757 3758 /* 3759 * Check for VBAD to work around the vp_crossmp bug in lookup(). 3760 * 3761 * For example consider tmpfs on /tmp and realpath /tmp. ni_vp will be 3762 * set to mount point's root vnode while ni_dvp will be vp_crossmp. 3763 * If the type is VDIR (like in this very case) we can skip looking 3764 * at ni_dvp in the first place. However, since vnodes get passed here 3765 * unlocked the target may transition to doomed state (type == VBAD) 3766 * before we get to evaluate the condition. If this happens, we will 3767 * populate part of the buffer and descend to vn_fullpath_dir with 3768 * vp == vp_crossmp. Prevent the problem by checking for VBAD. 3769 */ 3770 type = atomic_load_8(&vp->v_type); 3771 if (type == VBAD) { 3772 error = ENOENT; 3773 goto out_bad; 3774 } 3775 if (type != VDIR) { 3776 addend = hrdl_name_length + 2; 3777 if (*buflen < addend) { 3778 error = ENOMEM; 3779 goto out_bad; 3780 } 3781 *buflen -= addend; 3782 tmpbuf = buf + *buflen; 3783 tmpbuf[0] = '/'; 3784 memcpy(&tmpbuf[1], hrdl_name, hrdl_name_length); 3785 tmpbuf[addend - 1] = '\0'; 3786 vp = dvp; 3787 } 3788 3789 vfs_smr_enter(); 3790 pwd = pwd_get_smr(); 3791 error = vn_fullpath_any_smr(vp, pwd->pwd_rdir, buf, retbuf, buflen, 3792 addend); 3793 VFS_SMR_ASSERT_NOT_ENTERED(); 3794 if (error < 0) { 3795 pwd = pwd_hold(curthread); 3796 vref(vp); 3797 error = vn_fullpath_dir(vp, pwd->pwd_rdir, buf, retbuf, buflen, 3798 addend); 3799 pwd_drop(pwd); 3800 } 3801 if (error != 0) 3802 goto out_bad; 3803 3804 *freebuf = buf; 3805 3806 return (0); 3807 out_bad: 3808 free(buf, M_TEMP); 3809 return (error); 3810 } 3811 3812 struct vnode * 3813 vn_dir_dd_ino(struct vnode *vp) 3814 { 3815 struct namecache *ncp; 3816 struct vnode *ddvp; 3817 struct mtx *vlp; 3818 enum vgetstate vs; 3819 3820 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); 3821 vlp = VP2VNODELOCK(vp); 3822 mtx_lock(vlp); 3823 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { 3824 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) 3825 continue; 3826 ddvp = ncp->nc_dvp; 3827 vs = vget_prep(ddvp); 3828 mtx_unlock(vlp); 3829 if (vget_finish(ddvp, LK_SHARED | LK_NOWAIT, vs)) 3830 return (NULL); 3831 return (ddvp); 3832 } 3833 mtx_unlock(vlp); 3834 return (NULL); 3835 } 3836 3837 int 3838 vn_commname(struct vnode *vp, char *buf, u_int buflen) 3839 { 3840 struct namecache *ncp; 3841 struct mtx *vlp; 3842 int l; 3843 3844 vlp = VP2VNODELOCK(vp); 3845 mtx_lock(vlp); 3846 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) 3847 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) 3848 break; 3849 if (ncp == NULL) { 3850 mtx_unlock(vlp); 3851 return (ENOENT); 3852 } 3853 l = min(ncp->nc_nlen, buflen - 1); 3854 memcpy(buf, ncp->nc_name, l); 3855 mtx_unlock(vlp); 3856 buf[l] = '\0'; 3857 return (0); 3858 } 3859 3860 /* 3861 * This function updates path string to vnode's full global path 3862 * and checks the size of the new path string against the pathlen argument. 3863 * 3864 * Requires a locked, referenced vnode. 3865 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 3866 * 3867 * If vp is a directory, the call to vn_fullpath_global() always succeeds 3868 * because it falls back to the ".." lookup if the namecache lookup fails. 3869 */ 3870 int 3871 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, 3872 u_int pathlen) 3873 { 3874 struct nameidata nd; 3875 struct vnode *vp1; 3876 char *rpath, *fbuf; 3877 int error; 3878 3879 ASSERT_VOP_ELOCKED(vp, __func__); 3880 3881 /* Construct global filesystem path from vp. */ 3882 VOP_UNLOCK(vp); 3883 error = vn_fullpath_global(vp, &rpath, &fbuf); 3884 3885 if (error != 0) { 3886 vrele(vp); 3887 return (error); 3888 } 3889 3890 if (strlen(rpath) >= pathlen) { 3891 vrele(vp); 3892 error = ENAMETOOLONG; 3893 goto out; 3894 } 3895 3896 /* 3897 * Re-lookup the vnode by path to detect a possible rename. 3898 * As a side effect, the vnode is relocked. 3899 * If vnode was renamed, return ENOENT. 3900 */ 3901 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE, path); 3902 error = namei(&nd); 3903 if (error != 0) { 3904 vrele(vp); 3905 goto out; 3906 } 3907 NDFREE_PNBUF(&nd); 3908 vp1 = nd.ni_vp; 3909 vrele(vp); 3910 if (vp1 == vp) 3911 strcpy(path, rpath); 3912 else { 3913 vput(vp1); 3914 error = ENOENT; 3915 } 3916 3917 out: 3918 free(fbuf, M_TEMP); 3919 return (error); 3920 } 3921 3922 /* 3923 * This is similar to vn_path_to_global_path but allows for regular 3924 * files which may not be present in the cache. 3925 * 3926 * Requires a locked, referenced vnode. 3927 * Vnode is re-locked on success or ENODEV, otherwise unlocked. 3928 */ 3929 int 3930 vn_path_to_global_path_hardlink(struct thread *td, struct vnode *vp, 3931 struct vnode *dvp, char *path, u_int pathlen, const char *leaf_name, 3932 size_t leaf_length) 3933 { 3934 struct nameidata nd; 3935 struct vnode *vp1; 3936 char *rpath, *fbuf; 3937 size_t len; 3938 int error; 3939 3940 ASSERT_VOP_ELOCKED(vp, __func__); 3941 3942 /* 3943 * Construct global filesystem path from dvp, vp and leaf 3944 * name. 3945 */ 3946 VOP_UNLOCK(vp); 3947 len = pathlen; 3948 error = vn_fullpath_hardlink(vp, dvp, leaf_name, leaf_length, 3949 &rpath, &fbuf, &len); 3950 3951 if (error != 0) { 3952 vrele(vp); 3953 return (error); 3954 } 3955 3956 if (strlen(rpath) >= pathlen) { 3957 vrele(vp); 3958 error = ENAMETOOLONG; 3959 goto out; 3960 } 3961 3962 /* 3963 * Re-lookup the vnode by path to detect a possible rename. 3964 * As a side effect, the vnode is relocked. 3965 * If vnode was renamed, return ENOENT. 3966 */ 3967 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE, path); 3968 error = namei(&nd); 3969 if (error != 0) { 3970 vrele(vp); 3971 goto out; 3972 } 3973 NDFREE_PNBUF(&nd); 3974 vp1 = nd.ni_vp; 3975 vrele(vp); 3976 if (vp1 == vp) 3977 strcpy(path, rpath); 3978 else { 3979 vput(vp1); 3980 error = ENOENT; 3981 } 3982 3983 out: 3984 free(fbuf, M_TEMP); 3985 return (error); 3986 } 3987 3988 #ifdef DDB 3989 static void 3990 db_print_vpath(struct vnode *vp) 3991 { 3992 3993 while (vp != NULL) { 3994 db_printf("%p: ", vp); 3995 if (vp == rootvnode) { 3996 db_printf("/"); 3997 vp = NULL; 3998 } else { 3999 if (vp->v_vflag & VV_ROOT) { 4000 db_printf("<mount point>"); 4001 vp = vp->v_mount->mnt_vnodecovered; 4002 } else { 4003 struct namecache *ncp; 4004 char *ncn; 4005 int i; 4006 4007 ncp = TAILQ_FIRST(&vp->v_cache_dst); 4008 if (ncp != NULL) { 4009 ncn = ncp->nc_name; 4010 for (i = 0; i < ncp->nc_nlen; i++) 4011 db_printf("%c", *ncn++); 4012 vp = ncp->nc_dvp; 4013 } else { 4014 vp = NULL; 4015 } 4016 } 4017 } 4018 db_printf("\n"); 4019 } 4020 4021 return; 4022 } 4023 4024 DB_SHOW_COMMAND(vpath, db_show_vpath) 4025 { 4026 struct vnode *vp; 4027 4028 if (!have_addr) { 4029 db_printf("usage: show vpath <struct vnode *>\n"); 4030 return; 4031 } 4032 4033 vp = (struct vnode *)addr; 4034 db_print_vpath(vp); 4035 } 4036 4037 #endif 4038 4039 static int cache_fast_lookup = 1; 4040 4041 #define CACHE_FPL_FAILED -2020 4042 4043 static int 4044 cache_vop_bad_vexec(struct vop_fplookup_vexec_args *v) 4045 { 4046 vn_printf(v->a_vp, "no proper vop_fplookup_vexec\n"); 4047 panic("no proper vop_fplookup_vexec"); 4048 } 4049 4050 static int 4051 cache_vop_bad_symlink(struct vop_fplookup_symlink_args *v) 4052 { 4053 vn_printf(v->a_vp, "no proper vop_fplookup_symlink\n"); 4054 panic("no proper vop_fplookup_symlink"); 4055 } 4056 4057 void 4058 cache_vop_vector_register(struct vop_vector *v) 4059 { 4060 size_t ops; 4061 4062 ops = 0; 4063 if (v->vop_fplookup_vexec != NULL) { 4064 ops++; 4065 } 4066 if (v->vop_fplookup_symlink != NULL) { 4067 ops++; 4068 } 4069 4070 if (ops == 2) { 4071 return; 4072 } 4073 4074 if (ops == 0) { 4075 v->vop_fplookup_vexec = cache_vop_bad_vexec; 4076 v->vop_fplookup_symlink = cache_vop_bad_symlink; 4077 return; 4078 } 4079 4080 printf("%s: invalid vop vector %p -- either all or none fplookup vops " 4081 "need to be provided", __func__, v); 4082 if (v->vop_fplookup_vexec == NULL) { 4083 printf("%s: missing vop_fplookup_vexec\n", __func__); 4084 } 4085 if (v->vop_fplookup_symlink == NULL) { 4086 printf("%s: missing vop_fplookup_symlink\n", __func__); 4087 } 4088 panic("bad vop vector %p", v); 4089 } 4090 4091 #ifdef INVARIANTS 4092 void 4093 cache_validate_vop_vector(struct mount *mp, struct vop_vector *vops) 4094 { 4095 if (mp == NULL) 4096 return; 4097 4098 if ((mp->mnt_kern_flag & MNTK_FPLOOKUP) == 0) 4099 return; 4100 4101 if (vops->vop_fplookup_vexec == NULL || 4102 vops->vop_fplookup_vexec == cache_vop_bad_vexec) 4103 panic("bad vop_fplookup_vexec on vector %p for filesystem %s", 4104 vops, mp->mnt_vfc->vfc_name); 4105 4106 if (vops->vop_fplookup_symlink == NULL || 4107 vops->vop_fplookup_symlink == cache_vop_bad_symlink) 4108 panic("bad vop_fplookup_symlink on vector %p for filesystem %s", 4109 vops, mp->mnt_vfc->vfc_name); 4110 } 4111 #endif 4112 4113 void 4114 cache_fast_lookup_enabled_recalc(void) 4115 { 4116 int lookup_flag; 4117 int mac_on; 4118 4119 #ifdef MAC 4120 mac_on = mac_vnode_check_lookup_enabled(); 4121 mac_on |= mac_vnode_check_readlink_enabled(); 4122 #else 4123 mac_on = 0; 4124 #endif 4125 4126 lookup_flag = atomic_load_int(&cache_fast_lookup); 4127 if (lookup_flag && !mac_on) { 4128 atomic_store_char(&cache_fast_lookup_enabled, true); 4129 } else { 4130 atomic_store_char(&cache_fast_lookup_enabled, false); 4131 } 4132 } 4133 4134 static int 4135 syscal_vfs_cache_fast_lookup(SYSCTL_HANDLER_ARGS) 4136 { 4137 int error, old; 4138 4139 old = atomic_load_int(&cache_fast_lookup); 4140 error = sysctl_handle_int(oidp, arg1, arg2, req); 4141 if (error == 0 && req->newptr && old != atomic_load_int(&cache_fast_lookup)) 4142 cache_fast_lookup_enabled_recalc(); 4143 return (error); 4144 } 4145 SYSCTL_PROC(_vfs_cache_param, OID_AUTO, fast_lookup, CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 4146 &cache_fast_lookup, 0, syscal_vfs_cache_fast_lookup, "IU", ""); 4147 4148 /* 4149 * Components of nameidata (or objects it can point to) which may 4150 * need restoring in case fast path lookup fails. 4151 */ 4152 struct nameidata_outer { 4153 size_t ni_pathlen; 4154 int cn_flags; 4155 }; 4156 4157 struct nameidata_saved { 4158 #ifdef INVARIANTS 4159 char *cn_nameptr; 4160 size_t ni_pathlen; 4161 #endif 4162 }; 4163 4164 #ifdef INVARIANTS 4165 struct cache_fpl_debug { 4166 size_t ni_pathlen; 4167 }; 4168 #endif 4169 4170 struct cache_fpl { 4171 struct nameidata *ndp; 4172 struct componentname *cnp; 4173 char *nulchar; 4174 struct vnode *dvp; 4175 struct vnode *tvp; 4176 seqc_t dvp_seqc; 4177 seqc_t tvp_seqc; 4178 uint32_t hash; 4179 struct nameidata_saved snd; 4180 struct nameidata_outer snd_outer; 4181 int line; 4182 enum cache_fpl_status status:8; 4183 bool in_smr; 4184 bool fsearch; 4185 struct pwd **pwd; 4186 #ifdef INVARIANTS 4187 struct cache_fpl_debug debug; 4188 #endif 4189 }; 4190 4191 static bool cache_fplookup_mp_supported(struct mount *mp); 4192 static bool cache_fplookup_is_mp(struct cache_fpl *fpl); 4193 static int cache_fplookup_cross_mount(struct cache_fpl *fpl); 4194 static int cache_fplookup_partial_setup(struct cache_fpl *fpl); 4195 static int cache_fplookup_skip_slashes(struct cache_fpl *fpl); 4196 static int cache_fplookup_trailingslash(struct cache_fpl *fpl); 4197 static void cache_fpl_pathlen_dec(struct cache_fpl *fpl); 4198 static void cache_fpl_pathlen_inc(struct cache_fpl *fpl); 4199 static void cache_fpl_pathlen_add(struct cache_fpl *fpl, size_t n); 4200 static void cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n); 4201 4202 static void 4203 cache_fpl_cleanup_cnp(struct componentname *cnp) 4204 { 4205 4206 uma_zfree(namei_zone, cnp->cn_pnbuf); 4207 cnp->cn_pnbuf = NULL; 4208 cnp->cn_nameptr = NULL; 4209 } 4210 4211 static struct vnode * 4212 cache_fpl_handle_root(struct cache_fpl *fpl) 4213 { 4214 struct nameidata *ndp; 4215 struct componentname *cnp; 4216 4217 ndp = fpl->ndp; 4218 cnp = fpl->cnp; 4219 4220 MPASS(*(cnp->cn_nameptr) == '/'); 4221 cnp->cn_nameptr++; 4222 cache_fpl_pathlen_dec(fpl); 4223 4224 if (__predict_false(*(cnp->cn_nameptr) == '/')) { 4225 do { 4226 cnp->cn_nameptr++; 4227 cache_fpl_pathlen_dec(fpl); 4228 } while (*(cnp->cn_nameptr) == '/'); 4229 } 4230 4231 return (ndp->ni_rootdir); 4232 } 4233 4234 static void 4235 cache_fpl_checkpoint_outer(struct cache_fpl *fpl) 4236 { 4237 4238 fpl->snd_outer.ni_pathlen = fpl->ndp->ni_pathlen; 4239 fpl->snd_outer.cn_flags = fpl->ndp->ni_cnd.cn_flags; 4240 } 4241 4242 static void 4243 cache_fpl_checkpoint(struct cache_fpl *fpl) 4244 { 4245 4246 #ifdef INVARIANTS 4247 fpl->snd.cn_nameptr = fpl->ndp->ni_cnd.cn_nameptr; 4248 fpl->snd.ni_pathlen = fpl->debug.ni_pathlen; 4249 #endif 4250 } 4251 4252 static void 4253 cache_fpl_restore_partial(struct cache_fpl *fpl) 4254 { 4255 4256 fpl->ndp->ni_cnd.cn_flags = fpl->snd_outer.cn_flags; 4257 #ifdef INVARIANTS 4258 fpl->debug.ni_pathlen = fpl->snd.ni_pathlen; 4259 #endif 4260 } 4261 4262 static void 4263 cache_fpl_restore_abort(struct cache_fpl *fpl) 4264 { 4265 4266 cache_fpl_restore_partial(fpl); 4267 /* 4268 * It is 0 on entry by API contract. 4269 */ 4270 fpl->ndp->ni_resflags = 0; 4271 fpl->ndp->ni_cnd.cn_nameptr = fpl->ndp->ni_cnd.cn_pnbuf; 4272 fpl->ndp->ni_pathlen = fpl->snd_outer.ni_pathlen; 4273 } 4274 4275 #ifdef INVARIANTS 4276 #define cache_fpl_smr_assert_entered(fpl) ({ \ 4277 struct cache_fpl *_fpl = (fpl); \ 4278 MPASS(_fpl->in_smr == true); \ 4279 VFS_SMR_ASSERT_ENTERED(); \ 4280 }) 4281 #define cache_fpl_smr_assert_not_entered(fpl) ({ \ 4282 struct cache_fpl *_fpl = (fpl); \ 4283 MPASS(_fpl->in_smr == false); \ 4284 VFS_SMR_ASSERT_NOT_ENTERED(); \ 4285 }) 4286 static void 4287 cache_fpl_assert_status(struct cache_fpl *fpl) 4288 { 4289 4290 switch (fpl->status) { 4291 case CACHE_FPL_STATUS_UNSET: 4292 __assert_unreachable(); 4293 break; 4294 case CACHE_FPL_STATUS_DESTROYED: 4295 case CACHE_FPL_STATUS_ABORTED: 4296 case CACHE_FPL_STATUS_PARTIAL: 4297 case CACHE_FPL_STATUS_HANDLED: 4298 break; 4299 } 4300 } 4301 #else 4302 #define cache_fpl_smr_assert_entered(fpl) do { } while (0) 4303 #define cache_fpl_smr_assert_not_entered(fpl) do { } while (0) 4304 #define cache_fpl_assert_status(fpl) do { } while (0) 4305 #endif 4306 4307 #define cache_fpl_smr_enter_initial(fpl) ({ \ 4308 struct cache_fpl *_fpl = (fpl); \ 4309 vfs_smr_enter(); \ 4310 _fpl->in_smr = true; \ 4311 }) 4312 4313 #define cache_fpl_smr_enter(fpl) ({ \ 4314 struct cache_fpl *_fpl = (fpl); \ 4315 MPASS(_fpl->in_smr == false); \ 4316 vfs_smr_enter(); \ 4317 _fpl->in_smr = true; \ 4318 }) 4319 4320 #define cache_fpl_smr_exit(fpl) ({ \ 4321 struct cache_fpl *_fpl = (fpl); \ 4322 MPASS(_fpl->in_smr == true); \ 4323 vfs_smr_exit(); \ 4324 _fpl->in_smr = false; \ 4325 }) 4326 4327 static int 4328 cache_fpl_aborted_early_impl(struct cache_fpl *fpl, int line) 4329 { 4330 4331 if (fpl->status != CACHE_FPL_STATUS_UNSET) { 4332 KASSERT(fpl->status == CACHE_FPL_STATUS_PARTIAL, 4333 ("%s: converting to abort from %d at %d, set at %d\n", 4334 __func__, fpl->status, line, fpl->line)); 4335 } 4336 cache_fpl_smr_assert_not_entered(fpl); 4337 fpl->status = CACHE_FPL_STATUS_ABORTED; 4338 fpl->line = line; 4339 return (CACHE_FPL_FAILED); 4340 } 4341 4342 #define cache_fpl_aborted_early(x) cache_fpl_aborted_early_impl((x), __LINE__) 4343 4344 static int __noinline 4345 cache_fpl_aborted_impl(struct cache_fpl *fpl, int line) 4346 { 4347 struct nameidata *ndp; 4348 struct componentname *cnp; 4349 4350 ndp = fpl->ndp; 4351 cnp = fpl->cnp; 4352 4353 if (fpl->status != CACHE_FPL_STATUS_UNSET) { 4354 KASSERT(fpl->status == CACHE_FPL_STATUS_PARTIAL, 4355 ("%s: converting to abort from %d at %d, set at %d\n", 4356 __func__, fpl->status, line, fpl->line)); 4357 } 4358 fpl->status = CACHE_FPL_STATUS_ABORTED; 4359 fpl->line = line; 4360 if (fpl->in_smr) 4361 cache_fpl_smr_exit(fpl); 4362 cache_fpl_restore_abort(fpl); 4363 /* 4364 * Resolving symlinks overwrites data passed by the caller. 4365 * Let namei know. 4366 */ 4367 if (ndp->ni_loopcnt > 0) { 4368 fpl->status = CACHE_FPL_STATUS_DESTROYED; 4369 cache_fpl_cleanup_cnp(cnp); 4370 } 4371 return (CACHE_FPL_FAILED); 4372 } 4373 4374 #define cache_fpl_aborted(x) cache_fpl_aborted_impl((x), __LINE__) 4375 4376 static int __noinline 4377 cache_fpl_partial_impl(struct cache_fpl *fpl, int line) 4378 { 4379 4380 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET, 4381 ("%s: setting to partial at %d, but already set to %d at %d\n", 4382 __func__, line, fpl->status, fpl->line)); 4383 cache_fpl_smr_assert_entered(fpl); 4384 fpl->status = CACHE_FPL_STATUS_PARTIAL; 4385 fpl->line = line; 4386 return (cache_fplookup_partial_setup(fpl)); 4387 } 4388 4389 #define cache_fpl_partial(x) cache_fpl_partial_impl((x), __LINE__) 4390 4391 static int 4392 cache_fpl_handled_impl(struct cache_fpl *fpl, int line) 4393 { 4394 4395 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET, 4396 ("%s: setting to handled at %d, but already set to %d at %d\n", 4397 __func__, line, fpl->status, fpl->line)); 4398 cache_fpl_smr_assert_not_entered(fpl); 4399 fpl->status = CACHE_FPL_STATUS_HANDLED; 4400 fpl->line = line; 4401 return (0); 4402 } 4403 4404 #define cache_fpl_handled(x) cache_fpl_handled_impl((x), __LINE__) 4405 4406 static int 4407 cache_fpl_handled_error_impl(struct cache_fpl *fpl, int error, int line) 4408 { 4409 4410 KASSERT(fpl->status == CACHE_FPL_STATUS_UNSET, 4411 ("%s: setting to handled at %d, but already set to %d at %d\n", 4412 __func__, line, fpl->status, fpl->line)); 4413 MPASS(error != 0); 4414 MPASS(error != CACHE_FPL_FAILED); 4415 cache_fpl_smr_assert_not_entered(fpl); 4416 fpl->status = CACHE_FPL_STATUS_HANDLED; 4417 fpl->line = line; 4418 fpl->dvp = NULL; 4419 fpl->tvp = NULL; 4420 return (error); 4421 } 4422 4423 #define cache_fpl_handled_error(x, e) cache_fpl_handled_error_impl((x), (e), __LINE__) 4424 4425 static bool 4426 cache_fpl_terminated(struct cache_fpl *fpl) 4427 { 4428 4429 return (fpl->status != CACHE_FPL_STATUS_UNSET); 4430 } 4431 4432 #define CACHE_FPL_SUPPORTED_CN_FLAGS \ 4433 (NC_NOMAKEENTRY | NC_KEEPPOSENTRY | LOCKLEAF | LOCKPARENT | WANTPARENT | \ 4434 FAILIFEXISTS | FOLLOW | EMPTYPATH | LOCKSHARED | ISRESTARTED | WILLBEDIR | \ 4435 ISOPEN | NOMACCHECK | AUDITVNODE1 | AUDITVNODE2 | NOCAPCHECK | OPENREAD | \ 4436 OPENWRITE | WANTIOCTLCAPS) 4437 4438 #define CACHE_FPL_INTERNAL_CN_FLAGS \ 4439 (ISDOTDOT | MAKEENTRY | ISLASTCN) 4440 4441 _Static_assert((CACHE_FPL_SUPPORTED_CN_FLAGS & CACHE_FPL_INTERNAL_CN_FLAGS) == 0, 4442 "supported and internal flags overlap"); 4443 4444 static bool 4445 cache_fpl_islastcn(struct nameidata *ndp) 4446 { 4447 4448 return (*ndp->ni_next == 0); 4449 } 4450 4451 static bool 4452 cache_fpl_istrailingslash(struct cache_fpl *fpl) 4453 { 4454 4455 MPASS(fpl->nulchar > fpl->cnp->cn_pnbuf); 4456 return (*(fpl->nulchar - 1) == '/'); 4457 } 4458 4459 static bool 4460 cache_fpl_isdotdot(struct componentname *cnp) 4461 { 4462 4463 if (cnp->cn_namelen == 2 && 4464 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 4465 return (true); 4466 return (false); 4467 } 4468 4469 static bool 4470 cache_can_fplookup(struct cache_fpl *fpl) 4471 { 4472 struct nameidata *ndp; 4473 struct componentname *cnp; 4474 struct thread *td; 4475 4476 ndp = fpl->ndp; 4477 cnp = fpl->cnp; 4478 td = curthread; 4479 4480 if (!atomic_load_char(&cache_fast_lookup_enabled)) { 4481 cache_fpl_aborted_early(fpl); 4482 return (false); 4483 } 4484 if ((cnp->cn_flags & ~CACHE_FPL_SUPPORTED_CN_FLAGS) != 0) { 4485 cache_fpl_aborted_early(fpl); 4486 return (false); 4487 } 4488 if (IN_CAPABILITY_MODE(td)) { 4489 cache_fpl_aborted_early(fpl); 4490 return (false); 4491 } 4492 if (AUDITING_TD(td)) { 4493 cache_fpl_aborted_early(fpl); 4494 return (false); 4495 } 4496 if (ndp->ni_startdir != NULL) { 4497 cache_fpl_aborted_early(fpl); 4498 return (false); 4499 } 4500 return (true); 4501 } 4502 4503 static int __noinline 4504 cache_fplookup_dirfd(struct cache_fpl *fpl, struct vnode **vpp) 4505 { 4506 struct nameidata *ndp; 4507 struct componentname *cnp; 4508 int error; 4509 bool fsearch; 4510 4511 ndp = fpl->ndp; 4512 cnp = fpl->cnp; 4513 4514 error = fgetvp_lookup_smr(ndp->ni_dirfd, ndp, vpp, &fsearch); 4515 if (__predict_false(error != 0)) { 4516 return (cache_fpl_aborted(fpl)); 4517 } 4518 fpl->fsearch = fsearch; 4519 if ((*vpp)->v_type != VDIR) { 4520 if (!((cnp->cn_flags & EMPTYPATH) != 0 && cnp->cn_pnbuf[0] == '\0')) { 4521 cache_fpl_smr_exit(fpl); 4522 return (cache_fpl_handled_error(fpl, ENOTDIR)); 4523 } 4524 } 4525 return (0); 4526 } 4527 4528 static int __noinline 4529 cache_fplookup_negative_promote(struct cache_fpl *fpl, struct namecache *oncp, 4530 uint32_t hash) 4531 { 4532 struct componentname *cnp; 4533 struct vnode *dvp; 4534 4535 cnp = fpl->cnp; 4536 dvp = fpl->dvp; 4537 4538 cache_fpl_smr_exit(fpl); 4539 if (cache_neg_promote_cond(dvp, cnp, oncp, hash)) 4540 return (cache_fpl_handled_error(fpl, ENOENT)); 4541 else 4542 return (cache_fpl_aborted(fpl)); 4543 } 4544 4545 /* 4546 * The target vnode is not supported, prepare for the slow path to take over. 4547 */ 4548 static int __noinline 4549 cache_fplookup_partial_setup(struct cache_fpl *fpl) 4550 { 4551 struct nameidata *ndp; 4552 struct componentname *cnp; 4553 enum vgetstate dvs; 4554 struct vnode *dvp; 4555 struct pwd *pwd; 4556 seqc_t dvp_seqc; 4557 4558 ndp = fpl->ndp; 4559 cnp = fpl->cnp; 4560 pwd = *(fpl->pwd); 4561 dvp = fpl->dvp; 4562 dvp_seqc = fpl->dvp_seqc; 4563 4564 if (!pwd_hold_smr(pwd)) { 4565 return (cache_fpl_aborted(fpl)); 4566 } 4567 4568 /* 4569 * Note that seqc is checked before the vnode is locked, so by 4570 * the time regular lookup gets to it it may have moved. 4571 * 4572 * Ultimately this does not affect correctness, any lookup errors 4573 * are userspace racing with itself. It is guaranteed that any 4574 * path which ultimately gets found could also have been found 4575 * by regular lookup going all the way in absence of concurrent 4576 * modifications. 4577 */ 4578 dvs = vget_prep_smr(dvp); 4579 cache_fpl_smr_exit(fpl); 4580 if (__predict_false(dvs == VGET_NONE)) { 4581 pwd_drop(pwd); 4582 return (cache_fpl_aborted(fpl)); 4583 } 4584 4585 vget_finish_ref(dvp, dvs); 4586 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4587 vrele(dvp); 4588 pwd_drop(pwd); 4589 return (cache_fpl_aborted(fpl)); 4590 } 4591 4592 cache_fpl_restore_partial(fpl); 4593 #ifdef INVARIANTS 4594 if (cnp->cn_nameptr != fpl->snd.cn_nameptr) { 4595 panic("%s: cn_nameptr mismatch (%p != %p) full [%s]\n", __func__, 4596 cnp->cn_nameptr, fpl->snd.cn_nameptr, cnp->cn_pnbuf); 4597 } 4598 #endif 4599 4600 ndp->ni_startdir = dvp; 4601 cnp->cn_flags |= MAKEENTRY; 4602 if (cache_fpl_islastcn(ndp)) 4603 cnp->cn_flags |= ISLASTCN; 4604 if (cache_fpl_isdotdot(cnp)) 4605 cnp->cn_flags |= ISDOTDOT; 4606 4607 /* 4608 * Skip potential extra slashes parsing did not take care of. 4609 * cache_fplookup_skip_slashes explains the mechanism. 4610 */ 4611 if (__predict_false(*(cnp->cn_nameptr) == '/')) { 4612 do { 4613 cnp->cn_nameptr++; 4614 cache_fpl_pathlen_dec(fpl); 4615 } while (*(cnp->cn_nameptr) == '/'); 4616 } 4617 4618 ndp->ni_pathlen = fpl->nulchar - cnp->cn_nameptr + 1; 4619 #ifdef INVARIANTS 4620 if (ndp->ni_pathlen != fpl->debug.ni_pathlen) { 4621 panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n", 4622 __func__, ndp->ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar, 4623 cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf); 4624 } 4625 #endif 4626 return (0); 4627 } 4628 4629 static int 4630 cache_fplookup_final_child(struct cache_fpl *fpl, enum vgetstate tvs) 4631 { 4632 struct componentname *cnp; 4633 struct vnode *tvp; 4634 seqc_t tvp_seqc; 4635 int error, lkflags; 4636 4637 cnp = fpl->cnp; 4638 tvp = fpl->tvp; 4639 tvp_seqc = fpl->tvp_seqc; 4640 4641 if ((cnp->cn_flags & LOCKLEAF) != 0) { 4642 lkflags = LK_SHARED; 4643 if ((cnp->cn_flags & LOCKSHARED) == 0) 4644 lkflags = LK_EXCLUSIVE; 4645 error = vget_finish(tvp, lkflags, tvs); 4646 if (__predict_false(error != 0)) { 4647 return (cache_fpl_aborted(fpl)); 4648 } 4649 } else { 4650 vget_finish_ref(tvp, tvs); 4651 } 4652 4653 if (!vn_seqc_consistent(tvp, tvp_seqc)) { 4654 if ((cnp->cn_flags & LOCKLEAF) != 0) 4655 vput(tvp); 4656 else 4657 vrele(tvp); 4658 return (cache_fpl_aborted(fpl)); 4659 } 4660 4661 return (cache_fpl_handled(fpl)); 4662 } 4663 4664 /* 4665 * They want to possibly modify the state of the namecache. 4666 */ 4667 static int __noinline 4668 cache_fplookup_final_modifying(struct cache_fpl *fpl) 4669 { 4670 struct nameidata *ndp __diagused; 4671 struct componentname *cnp; 4672 enum vgetstate dvs; 4673 struct vnode *dvp, *tvp; 4674 struct mount *mp; 4675 seqc_t dvp_seqc; 4676 int error; 4677 bool docache; 4678 4679 ndp = fpl->ndp; 4680 cnp = fpl->cnp; 4681 dvp = fpl->dvp; 4682 dvp_seqc = fpl->dvp_seqc; 4683 4684 MPASS(*(cnp->cn_nameptr) != '/'); 4685 MPASS(cache_fpl_islastcn(ndp)); 4686 if ((cnp->cn_flags & LOCKPARENT) == 0) 4687 MPASS((cnp->cn_flags & WANTPARENT) != 0); 4688 MPASS((cnp->cn_flags & TRAILINGSLASH) == 0); 4689 MPASS(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == DELETE || 4690 cnp->cn_nameiop == RENAME); 4691 MPASS((cnp->cn_flags & MAKEENTRY) == 0); 4692 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 4693 4694 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 4695 if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) 4696 docache = false; 4697 4698 /* 4699 * Regular lookup nulifies the slash, which we don't do here. 4700 * Don't take chances with filesystem routines seeing it for 4701 * the last entry. 4702 */ 4703 if (cache_fpl_istrailingslash(fpl)) { 4704 return (cache_fpl_partial(fpl)); 4705 } 4706 4707 mp = atomic_load_ptr(&dvp->v_mount); 4708 if (__predict_false(mp == NULL)) { 4709 return (cache_fpl_aborted(fpl)); 4710 } 4711 4712 if (__predict_false(mp->mnt_flag & MNT_RDONLY)) { 4713 cache_fpl_smr_exit(fpl); 4714 /* 4715 * Original code keeps not checking for CREATE which 4716 * might be a bug. For now let the old lookup decide. 4717 */ 4718 if (cnp->cn_nameiop == CREATE) { 4719 return (cache_fpl_aborted(fpl)); 4720 } 4721 return (cache_fpl_handled_error(fpl, EROFS)); 4722 } 4723 4724 if (fpl->tvp != NULL && (cnp->cn_flags & FAILIFEXISTS) != 0) { 4725 cache_fpl_smr_exit(fpl); 4726 return (cache_fpl_handled_error(fpl, EEXIST)); 4727 } 4728 4729 /* 4730 * Secure access to dvp; check cache_fplookup_partial_setup for 4731 * reasoning. 4732 * 4733 * XXX At least UFS requires its lookup routine to be called for 4734 * the last path component, which leads to some level of complication 4735 * and inefficiency: 4736 * - the target routine always locks the target vnode, but our caller 4737 * may not need it locked 4738 * - some of the VOP machinery asserts that the parent is locked, which 4739 * once more may be not required 4740 * 4741 * TODO: add a flag for filesystems which don't need this. 4742 */ 4743 dvs = vget_prep_smr(dvp); 4744 cache_fpl_smr_exit(fpl); 4745 if (__predict_false(dvs == VGET_NONE)) { 4746 return (cache_fpl_aborted(fpl)); 4747 } 4748 4749 vget_finish_ref(dvp, dvs); 4750 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4751 vrele(dvp); 4752 return (cache_fpl_aborted(fpl)); 4753 } 4754 4755 error = vn_lock(dvp, LK_EXCLUSIVE); 4756 if (__predict_false(error != 0)) { 4757 vrele(dvp); 4758 return (cache_fpl_aborted(fpl)); 4759 } 4760 4761 tvp = NULL; 4762 cnp->cn_flags |= ISLASTCN; 4763 if (docache) 4764 cnp->cn_flags |= MAKEENTRY; 4765 if (cache_fpl_isdotdot(cnp)) 4766 cnp->cn_flags |= ISDOTDOT; 4767 cnp->cn_lkflags = LK_EXCLUSIVE; 4768 error = VOP_LOOKUP(dvp, &tvp, cnp); 4769 switch (error) { 4770 case EJUSTRETURN: 4771 case 0: 4772 break; 4773 case ENOTDIR: 4774 case ENOENT: 4775 vput(dvp); 4776 return (cache_fpl_handled_error(fpl, error)); 4777 default: 4778 vput(dvp); 4779 return (cache_fpl_aborted(fpl)); 4780 } 4781 4782 fpl->tvp = tvp; 4783 4784 if (tvp == NULL) { 4785 MPASS(error == EJUSTRETURN); 4786 if ((cnp->cn_flags & LOCKPARENT) == 0) { 4787 VOP_UNLOCK(dvp); 4788 } 4789 return (cache_fpl_handled(fpl)); 4790 } 4791 4792 /* 4793 * There are very hairy corner cases concerning various flag combinations 4794 * and locking state. In particular here we only hold one lock instead of 4795 * two. 4796 * 4797 * Skip the complexity as it is of no significance for normal workloads. 4798 */ 4799 if (__predict_false(tvp == dvp)) { 4800 vput(dvp); 4801 vrele(tvp); 4802 return (cache_fpl_aborted(fpl)); 4803 } 4804 4805 /* 4806 * If they want the symlink itself we are fine, but if they want to 4807 * follow it regular lookup has to be engaged. 4808 */ 4809 if (tvp->v_type == VLNK) { 4810 if ((cnp->cn_flags & FOLLOW) != 0) { 4811 vput(dvp); 4812 vput(tvp); 4813 return (cache_fpl_aborted(fpl)); 4814 } 4815 } 4816 4817 /* 4818 * Since we expect this to be the terminal vnode it should almost never 4819 * be a mount point. 4820 */ 4821 if (__predict_false(cache_fplookup_is_mp(fpl))) { 4822 vput(dvp); 4823 vput(tvp); 4824 return (cache_fpl_aborted(fpl)); 4825 } 4826 4827 if ((cnp->cn_flags & FAILIFEXISTS) != 0) { 4828 vput(dvp); 4829 vput(tvp); 4830 return (cache_fpl_handled_error(fpl, EEXIST)); 4831 } 4832 4833 if ((cnp->cn_flags & LOCKLEAF) == 0) { 4834 VOP_UNLOCK(tvp); 4835 } 4836 4837 if ((cnp->cn_flags & LOCKPARENT) == 0) { 4838 VOP_UNLOCK(dvp); 4839 } 4840 4841 return (cache_fpl_handled(fpl)); 4842 } 4843 4844 static int __noinline 4845 cache_fplookup_modifying(struct cache_fpl *fpl) 4846 { 4847 struct nameidata *ndp; 4848 4849 ndp = fpl->ndp; 4850 4851 if (!cache_fpl_islastcn(ndp)) { 4852 return (cache_fpl_partial(fpl)); 4853 } 4854 return (cache_fplookup_final_modifying(fpl)); 4855 } 4856 4857 static int __noinline 4858 cache_fplookup_final_withparent(struct cache_fpl *fpl) 4859 { 4860 struct componentname *cnp; 4861 enum vgetstate dvs, tvs; 4862 struct vnode *dvp, *tvp; 4863 seqc_t dvp_seqc; 4864 int error; 4865 4866 cnp = fpl->cnp; 4867 dvp = fpl->dvp; 4868 dvp_seqc = fpl->dvp_seqc; 4869 tvp = fpl->tvp; 4870 4871 MPASS((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0); 4872 4873 /* 4874 * This is less efficient than it can be for simplicity. 4875 */ 4876 dvs = vget_prep_smr(dvp); 4877 if (__predict_false(dvs == VGET_NONE)) { 4878 return (cache_fpl_aborted(fpl)); 4879 } 4880 tvs = vget_prep_smr(tvp); 4881 if (__predict_false(tvs == VGET_NONE)) { 4882 cache_fpl_smr_exit(fpl); 4883 vget_abort(dvp, dvs); 4884 return (cache_fpl_aborted(fpl)); 4885 } 4886 4887 cache_fpl_smr_exit(fpl); 4888 4889 if ((cnp->cn_flags & LOCKPARENT) != 0) { 4890 error = vget_finish(dvp, LK_EXCLUSIVE, dvs); 4891 if (__predict_false(error != 0)) { 4892 vget_abort(tvp, tvs); 4893 return (cache_fpl_aborted(fpl)); 4894 } 4895 } else { 4896 vget_finish_ref(dvp, dvs); 4897 } 4898 4899 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4900 vget_abort(tvp, tvs); 4901 if ((cnp->cn_flags & LOCKPARENT) != 0) 4902 vput(dvp); 4903 else 4904 vrele(dvp); 4905 return (cache_fpl_aborted(fpl)); 4906 } 4907 4908 error = cache_fplookup_final_child(fpl, tvs); 4909 if (__predict_false(error != 0)) { 4910 MPASS(fpl->status == CACHE_FPL_STATUS_ABORTED || 4911 fpl->status == CACHE_FPL_STATUS_DESTROYED); 4912 if ((cnp->cn_flags & LOCKPARENT) != 0) 4913 vput(dvp); 4914 else 4915 vrele(dvp); 4916 return (error); 4917 } 4918 4919 MPASS(fpl->status == CACHE_FPL_STATUS_HANDLED); 4920 return (0); 4921 } 4922 4923 static int 4924 cache_fplookup_final(struct cache_fpl *fpl) 4925 { 4926 struct componentname *cnp; 4927 enum vgetstate tvs; 4928 struct vnode *dvp, *tvp; 4929 seqc_t dvp_seqc; 4930 4931 cnp = fpl->cnp; 4932 dvp = fpl->dvp; 4933 dvp_seqc = fpl->dvp_seqc; 4934 tvp = fpl->tvp; 4935 4936 MPASS(*(cnp->cn_nameptr) != '/'); 4937 4938 if (cnp->cn_nameiop != LOOKUP) { 4939 return (cache_fplookup_final_modifying(fpl)); 4940 } 4941 4942 if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0) 4943 return (cache_fplookup_final_withparent(fpl)); 4944 4945 tvs = vget_prep_smr(tvp); 4946 if (__predict_false(tvs == VGET_NONE)) { 4947 return (cache_fpl_partial(fpl)); 4948 } 4949 4950 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 4951 cache_fpl_smr_exit(fpl); 4952 vget_abort(tvp, tvs); 4953 return (cache_fpl_aborted(fpl)); 4954 } 4955 4956 cache_fpl_smr_exit(fpl); 4957 return (cache_fplookup_final_child(fpl, tvs)); 4958 } 4959 4960 /* 4961 * Comment from locked lookup: 4962 * Check for degenerate name (e.g. / or "") which is a way of talking about a 4963 * directory, e.g. like "/." or ".". 4964 */ 4965 static int __noinline 4966 cache_fplookup_degenerate(struct cache_fpl *fpl) 4967 { 4968 struct componentname *cnp; 4969 struct vnode *dvp; 4970 enum vgetstate dvs; 4971 int error, lkflags; 4972 #ifdef INVARIANTS 4973 char *cp; 4974 #endif 4975 4976 fpl->tvp = fpl->dvp; 4977 fpl->tvp_seqc = fpl->dvp_seqc; 4978 4979 cnp = fpl->cnp; 4980 dvp = fpl->dvp; 4981 4982 #ifdef INVARIANTS 4983 for (cp = cnp->cn_pnbuf; *cp != '\0'; cp++) { 4984 KASSERT(*cp == '/', 4985 ("%s: encountered non-slash; string [%s]\n", __func__, 4986 cnp->cn_pnbuf)); 4987 } 4988 #endif 4989 4990 if (__predict_false(cnp->cn_nameiop != LOOKUP)) { 4991 cache_fpl_smr_exit(fpl); 4992 return (cache_fpl_handled_error(fpl, EISDIR)); 4993 } 4994 4995 if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0) { 4996 return (cache_fplookup_final_withparent(fpl)); 4997 } 4998 4999 dvs = vget_prep_smr(dvp); 5000 cache_fpl_smr_exit(fpl); 5001 if (__predict_false(dvs == VGET_NONE)) { 5002 return (cache_fpl_aborted(fpl)); 5003 } 5004 5005 if ((cnp->cn_flags & LOCKLEAF) != 0) { 5006 lkflags = LK_SHARED; 5007 if ((cnp->cn_flags & LOCKSHARED) == 0) 5008 lkflags = LK_EXCLUSIVE; 5009 error = vget_finish(dvp, lkflags, dvs); 5010 if (__predict_false(error != 0)) { 5011 return (cache_fpl_aborted(fpl)); 5012 } 5013 } else { 5014 vget_finish_ref(dvp, dvs); 5015 } 5016 return (cache_fpl_handled(fpl)); 5017 } 5018 5019 static int __noinline 5020 cache_fplookup_emptypath(struct cache_fpl *fpl) 5021 { 5022 struct nameidata *ndp; 5023 struct componentname *cnp; 5024 enum vgetstate tvs; 5025 struct vnode *tvp; 5026 int error, lkflags; 5027 5028 fpl->tvp = fpl->dvp; 5029 fpl->tvp_seqc = fpl->dvp_seqc; 5030 5031 ndp = fpl->ndp; 5032 cnp = fpl->cnp; 5033 tvp = fpl->tvp; 5034 5035 MPASS(*cnp->cn_pnbuf == '\0'); 5036 5037 if (__predict_false((cnp->cn_flags & EMPTYPATH) == 0)) { 5038 cache_fpl_smr_exit(fpl); 5039 return (cache_fpl_handled_error(fpl, ENOENT)); 5040 } 5041 5042 MPASS((cnp->cn_flags & (LOCKPARENT | WANTPARENT)) == 0); 5043 5044 tvs = vget_prep_smr(tvp); 5045 cache_fpl_smr_exit(fpl); 5046 if (__predict_false(tvs == VGET_NONE)) { 5047 return (cache_fpl_aborted(fpl)); 5048 } 5049 5050 if ((cnp->cn_flags & LOCKLEAF) != 0) { 5051 lkflags = LK_SHARED; 5052 if ((cnp->cn_flags & LOCKSHARED) == 0) 5053 lkflags = LK_EXCLUSIVE; 5054 error = vget_finish(tvp, lkflags, tvs); 5055 if (__predict_false(error != 0)) { 5056 return (cache_fpl_aborted(fpl)); 5057 } 5058 } else { 5059 vget_finish_ref(tvp, tvs); 5060 } 5061 5062 ndp->ni_resflags |= NIRES_EMPTYPATH; 5063 return (cache_fpl_handled(fpl)); 5064 } 5065 5066 static int __noinline 5067 cache_fplookup_noentry(struct cache_fpl *fpl) 5068 { 5069 struct nameidata *ndp; 5070 struct componentname *cnp; 5071 enum vgetstate dvs; 5072 struct vnode *dvp, *tvp; 5073 seqc_t dvp_seqc; 5074 int error; 5075 5076 ndp = fpl->ndp; 5077 cnp = fpl->cnp; 5078 dvp = fpl->dvp; 5079 dvp_seqc = fpl->dvp_seqc; 5080 5081 MPASS((cnp->cn_flags & MAKEENTRY) == 0); 5082 MPASS((cnp->cn_flags & ISDOTDOT) == 0); 5083 if (cnp->cn_nameiop == LOOKUP) 5084 MPASS((cnp->cn_flags & NOCACHE) == 0); 5085 MPASS(!cache_fpl_isdotdot(cnp)); 5086 5087 /* 5088 * Hack: delayed name len checking. 5089 */ 5090 if (__predict_false(cnp->cn_namelen > NAME_MAX)) { 5091 cache_fpl_smr_exit(fpl); 5092 return (cache_fpl_handled_error(fpl, ENAMETOOLONG)); 5093 } 5094 5095 if (cnp->cn_nameptr[0] == '/') { 5096 return (cache_fplookup_skip_slashes(fpl)); 5097 } 5098 5099 if (cnp->cn_pnbuf[0] == '\0') { 5100 return (cache_fplookup_emptypath(fpl)); 5101 } 5102 5103 if (cnp->cn_nameptr[0] == '\0') { 5104 if (fpl->tvp == NULL) { 5105 return (cache_fplookup_degenerate(fpl)); 5106 } 5107 return (cache_fplookup_trailingslash(fpl)); 5108 } 5109 5110 if (cnp->cn_nameiop != LOOKUP) { 5111 fpl->tvp = NULL; 5112 return (cache_fplookup_modifying(fpl)); 5113 } 5114 5115 /* 5116 * Only try to fill in the component if it is the last one, 5117 * otherwise not only there may be several to handle but the 5118 * walk may be complicated. 5119 */ 5120 if (!cache_fpl_islastcn(ndp)) { 5121 return (cache_fpl_partial(fpl)); 5122 } 5123 5124 /* 5125 * Regular lookup nulifies the slash, which we don't do here. 5126 * Don't take chances with filesystem routines seeing it for 5127 * the last entry. 5128 */ 5129 if (cache_fpl_istrailingslash(fpl)) { 5130 return (cache_fpl_partial(fpl)); 5131 } 5132 5133 /* 5134 * Secure access to dvp; check cache_fplookup_partial_setup for 5135 * reasoning. 5136 */ 5137 dvs = vget_prep_smr(dvp); 5138 cache_fpl_smr_exit(fpl); 5139 if (__predict_false(dvs == VGET_NONE)) { 5140 return (cache_fpl_aborted(fpl)); 5141 } 5142 5143 vget_finish_ref(dvp, dvs); 5144 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 5145 vrele(dvp); 5146 return (cache_fpl_aborted(fpl)); 5147 } 5148 5149 error = vn_lock(dvp, LK_SHARED); 5150 if (__predict_false(error != 0)) { 5151 vrele(dvp); 5152 return (cache_fpl_aborted(fpl)); 5153 } 5154 5155 tvp = NULL; 5156 /* 5157 * TODO: provide variants which don't require locking either vnode. 5158 */ 5159 cnp->cn_flags |= ISLASTCN | MAKEENTRY; 5160 cnp->cn_lkflags = LK_SHARED; 5161 if ((cnp->cn_flags & LOCKSHARED) == 0) { 5162 cnp->cn_lkflags = LK_EXCLUSIVE; 5163 } 5164 error = VOP_LOOKUP(dvp, &tvp, cnp); 5165 switch (error) { 5166 case EJUSTRETURN: 5167 case 0: 5168 break; 5169 case ENOTDIR: 5170 case ENOENT: 5171 vput(dvp); 5172 return (cache_fpl_handled_error(fpl, error)); 5173 default: 5174 vput(dvp); 5175 return (cache_fpl_aborted(fpl)); 5176 } 5177 5178 fpl->tvp = tvp; 5179 5180 if (tvp == NULL) { 5181 MPASS(error == EJUSTRETURN); 5182 if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) { 5183 vput(dvp); 5184 } else if ((cnp->cn_flags & LOCKPARENT) == 0) { 5185 VOP_UNLOCK(dvp); 5186 } 5187 return (cache_fpl_handled(fpl)); 5188 } 5189 5190 if (tvp->v_type == VLNK) { 5191 if ((cnp->cn_flags & FOLLOW) != 0) { 5192 vput(dvp); 5193 vput(tvp); 5194 return (cache_fpl_aborted(fpl)); 5195 } 5196 } 5197 5198 if (__predict_false(cache_fplookup_is_mp(fpl))) { 5199 vput(dvp); 5200 vput(tvp); 5201 return (cache_fpl_aborted(fpl)); 5202 } 5203 5204 if ((cnp->cn_flags & LOCKLEAF) == 0) { 5205 VOP_UNLOCK(tvp); 5206 } 5207 5208 if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) { 5209 vput(dvp); 5210 } else if ((cnp->cn_flags & LOCKPARENT) == 0) { 5211 VOP_UNLOCK(dvp); 5212 } 5213 return (cache_fpl_handled(fpl)); 5214 } 5215 5216 static int __noinline 5217 cache_fplookup_dot(struct cache_fpl *fpl) 5218 { 5219 int error; 5220 5221 MPASS(!seqc_in_modify(fpl->dvp_seqc)); 5222 5223 if (__predict_false(fpl->dvp->v_type != VDIR)) { 5224 cache_fpl_smr_exit(fpl); 5225 return (cache_fpl_handled_error(fpl, ENOTDIR)); 5226 } 5227 5228 /* 5229 * Just re-assign the value. seqc will be checked later for the first 5230 * non-dot path component in line and/or before deciding to return the 5231 * vnode. 5232 */ 5233 fpl->tvp = fpl->dvp; 5234 fpl->tvp_seqc = fpl->dvp_seqc; 5235 5236 SDT_PROBE3(vfs, namecache, lookup, hit, fpl->dvp, ".", fpl->dvp); 5237 5238 error = 0; 5239 if (cache_fplookup_is_mp(fpl)) { 5240 error = cache_fplookup_cross_mount(fpl); 5241 } 5242 return (error); 5243 } 5244 5245 static int __noinline 5246 cache_fplookup_dotdot(struct cache_fpl *fpl) 5247 { 5248 struct nameidata *ndp; 5249 struct componentname *cnp; 5250 struct namecache *ncp; 5251 struct vnode *dvp; 5252 struct prison *pr; 5253 u_char nc_flag; 5254 5255 ndp = fpl->ndp; 5256 cnp = fpl->cnp; 5257 dvp = fpl->dvp; 5258 5259 MPASS(cache_fpl_isdotdot(cnp)); 5260 5261 /* 5262 * XXX this is racy the same way regular lookup is 5263 */ 5264 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 5265 pr = pr->pr_parent) 5266 if (dvp == pr->pr_root) 5267 break; 5268 5269 if (dvp == ndp->ni_rootdir || 5270 dvp == ndp->ni_topdir || 5271 dvp == rootvnode || 5272 pr != NULL) { 5273 fpl->tvp = dvp; 5274 fpl->tvp_seqc = vn_seqc_read_any(dvp); 5275 if (seqc_in_modify(fpl->tvp_seqc)) { 5276 return (cache_fpl_aborted(fpl)); 5277 } 5278 return (0); 5279 } 5280 5281 if ((dvp->v_vflag & VV_ROOT) != 0) { 5282 /* 5283 * TODO 5284 * The opposite of climb mount is needed here. 5285 */ 5286 return (cache_fpl_partial(fpl)); 5287 } 5288 5289 if (__predict_false(dvp->v_type != VDIR)) { 5290 cache_fpl_smr_exit(fpl); 5291 return (cache_fpl_handled_error(fpl, ENOTDIR)); 5292 } 5293 5294 ncp = atomic_load_consume_ptr(&dvp->v_cache_dd); 5295 if (ncp == NULL) { 5296 return (cache_fpl_aborted(fpl)); 5297 } 5298 5299 nc_flag = atomic_load_char(&ncp->nc_flag); 5300 if ((nc_flag & NCF_ISDOTDOT) != 0) { 5301 if ((nc_flag & NCF_NEGATIVE) != 0) 5302 return (cache_fpl_aborted(fpl)); 5303 fpl->tvp = ncp->nc_vp; 5304 } else { 5305 fpl->tvp = ncp->nc_dvp; 5306 } 5307 5308 fpl->tvp_seqc = vn_seqc_read_any(fpl->tvp); 5309 if (seqc_in_modify(fpl->tvp_seqc)) { 5310 return (cache_fpl_partial(fpl)); 5311 } 5312 5313 /* 5314 * Acquire fence provided by vn_seqc_read_any above. 5315 */ 5316 if (__predict_false(atomic_load_ptr(&dvp->v_cache_dd) != ncp)) { 5317 return (cache_fpl_aborted(fpl)); 5318 } 5319 5320 if (!cache_ncp_canuse(ncp)) { 5321 return (cache_fpl_aborted(fpl)); 5322 } 5323 5324 return (0); 5325 } 5326 5327 static int __noinline 5328 cache_fplookup_neg(struct cache_fpl *fpl, struct namecache *ncp, uint32_t hash) 5329 { 5330 u_char nc_flag __diagused; 5331 bool neg_promote; 5332 5333 #ifdef INVARIANTS 5334 nc_flag = atomic_load_char(&ncp->nc_flag); 5335 MPASS((nc_flag & NCF_NEGATIVE) != 0); 5336 #endif 5337 /* 5338 * If they want to create an entry we need to replace this one. 5339 */ 5340 if (__predict_false(fpl->cnp->cn_nameiop != LOOKUP)) { 5341 fpl->tvp = NULL; 5342 return (cache_fplookup_modifying(fpl)); 5343 } 5344 neg_promote = cache_neg_hit_prep(ncp); 5345 if (!cache_fpl_neg_ncp_canuse(ncp)) { 5346 cache_neg_hit_abort(ncp); 5347 return (cache_fpl_partial(fpl)); 5348 } 5349 if (neg_promote) { 5350 return (cache_fplookup_negative_promote(fpl, ncp, hash)); 5351 } 5352 cache_neg_hit_finish(ncp); 5353 cache_fpl_smr_exit(fpl); 5354 return (cache_fpl_handled_error(fpl, ENOENT)); 5355 } 5356 5357 /* 5358 * Resolve a symlink. Called by filesystem-specific routines. 5359 * 5360 * Code flow is: 5361 * ... -> cache_fplookup_symlink -> VOP_FPLOOKUP_SYMLINK -> cache_symlink_resolve 5362 */ 5363 int 5364 cache_symlink_resolve(struct cache_fpl *fpl, const char *string, size_t len) 5365 { 5366 struct nameidata *ndp; 5367 struct componentname *cnp; 5368 size_t adjust; 5369 5370 ndp = fpl->ndp; 5371 cnp = fpl->cnp; 5372 5373 if (__predict_false(len == 0)) { 5374 return (ENOENT); 5375 } 5376 5377 if (__predict_false(len > MAXPATHLEN - 2)) { 5378 if (cache_fpl_istrailingslash(fpl)) { 5379 return (EAGAIN); 5380 } 5381 } 5382 5383 ndp->ni_pathlen = fpl->nulchar - cnp->cn_nameptr - cnp->cn_namelen + 1; 5384 #ifdef INVARIANTS 5385 if (ndp->ni_pathlen != fpl->debug.ni_pathlen) { 5386 panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n", 5387 __func__, ndp->ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar, 5388 cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf); 5389 } 5390 #endif 5391 5392 if (__predict_false(len + ndp->ni_pathlen > MAXPATHLEN)) { 5393 return (ENAMETOOLONG); 5394 } 5395 5396 if (__predict_false(ndp->ni_loopcnt++ >= MAXSYMLINKS)) { 5397 return (ELOOP); 5398 } 5399 5400 adjust = len; 5401 if (ndp->ni_pathlen > 1) { 5402 bcopy(ndp->ni_next, cnp->cn_pnbuf + len, ndp->ni_pathlen); 5403 } else { 5404 if (cache_fpl_istrailingslash(fpl)) { 5405 adjust = len + 1; 5406 cnp->cn_pnbuf[len] = '/'; 5407 cnp->cn_pnbuf[len + 1] = '\0'; 5408 } else { 5409 cnp->cn_pnbuf[len] = '\0'; 5410 } 5411 } 5412 bcopy(string, cnp->cn_pnbuf, len); 5413 5414 ndp->ni_pathlen += adjust; 5415 cache_fpl_pathlen_add(fpl, adjust); 5416 cnp->cn_nameptr = cnp->cn_pnbuf; 5417 fpl->nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1]; 5418 fpl->tvp = NULL; 5419 return (0); 5420 } 5421 5422 static int __noinline 5423 cache_fplookup_symlink(struct cache_fpl *fpl) 5424 { 5425 struct mount *mp; 5426 struct nameidata *ndp; 5427 struct componentname *cnp; 5428 struct vnode *dvp, *tvp; 5429 int error; 5430 5431 ndp = fpl->ndp; 5432 cnp = fpl->cnp; 5433 dvp = fpl->dvp; 5434 tvp = fpl->tvp; 5435 5436 if (cache_fpl_islastcn(ndp)) { 5437 if ((cnp->cn_flags & FOLLOW) == 0) { 5438 return (cache_fplookup_final(fpl)); 5439 } 5440 } 5441 5442 mp = atomic_load_ptr(&dvp->v_mount); 5443 if (__predict_false(mp == NULL)) { 5444 return (cache_fpl_aborted(fpl)); 5445 } 5446 5447 /* 5448 * Note this check races against setting the flag just like regular 5449 * lookup. 5450 */ 5451 if (__predict_false((mp->mnt_flag & MNT_NOSYMFOLLOW) != 0)) { 5452 cache_fpl_smr_exit(fpl); 5453 return (cache_fpl_handled_error(fpl, EACCES)); 5454 } 5455 5456 error = VOP_FPLOOKUP_SYMLINK(tvp, fpl); 5457 if (__predict_false(error != 0)) { 5458 switch (error) { 5459 case EAGAIN: 5460 return (cache_fpl_partial(fpl)); 5461 case ENOENT: 5462 case ENAMETOOLONG: 5463 case ELOOP: 5464 cache_fpl_smr_exit(fpl); 5465 return (cache_fpl_handled_error(fpl, error)); 5466 default: 5467 return (cache_fpl_aborted(fpl)); 5468 } 5469 } 5470 5471 if (*(cnp->cn_nameptr) == '/') { 5472 fpl->dvp = cache_fpl_handle_root(fpl); 5473 fpl->dvp_seqc = vn_seqc_read_any(fpl->dvp); 5474 if (seqc_in_modify(fpl->dvp_seqc)) { 5475 return (cache_fpl_aborted(fpl)); 5476 } 5477 /* 5478 * The main loop assumes that ->dvp points to a vnode belonging 5479 * to a filesystem which can do lockless lookup, but the absolute 5480 * symlink can be wandering off to one which does not. 5481 */ 5482 mp = atomic_load_ptr(&fpl->dvp->v_mount); 5483 if (__predict_false(mp == NULL)) { 5484 return (cache_fpl_aborted(fpl)); 5485 } 5486 if (!cache_fplookup_mp_supported(mp)) { 5487 cache_fpl_checkpoint(fpl); 5488 return (cache_fpl_partial(fpl)); 5489 } 5490 } 5491 return (0); 5492 } 5493 5494 static int 5495 cache_fplookup_next(struct cache_fpl *fpl) 5496 { 5497 struct componentname *cnp; 5498 struct namecache *ncp; 5499 struct vnode *dvp, *tvp; 5500 u_char nc_flag; 5501 uint32_t hash; 5502 int error; 5503 5504 cnp = fpl->cnp; 5505 dvp = fpl->dvp; 5506 hash = fpl->hash; 5507 5508 if (__predict_false(cnp->cn_nameptr[0] == '.')) { 5509 if (cnp->cn_namelen == 1) { 5510 return (cache_fplookup_dot(fpl)); 5511 } 5512 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 5513 return (cache_fplookup_dotdot(fpl)); 5514 } 5515 } 5516 5517 MPASS(!cache_fpl_isdotdot(cnp)); 5518 5519 CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 5520 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 5521 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 5522 break; 5523 } 5524 5525 if (__predict_false(ncp == NULL)) { 5526 return (cache_fplookup_noentry(fpl)); 5527 } 5528 5529 tvp = atomic_load_ptr(&ncp->nc_vp); 5530 nc_flag = atomic_load_char(&ncp->nc_flag); 5531 if ((nc_flag & NCF_NEGATIVE) != 0) { 5532 return (cache_fplookup_neg(fpl, ncp, hash)); 5533 } 5534 5535 if (!cache_ncp_canuse(ncp)) { 5536 return (cache_fpl_partial(fpl)); 5537 } 5538 5539 fpl->tvp = tvp; 5540 fpl->tvp_seqc = vn_seqc_read_any(tvp); 5541 if (seqc_in_modify(fpl->tvp_seqc)) { 5542 return (cache_fpl_partial(fpl)); 5543 } 5544 5545 counter_u64_add(numposhits, 1); 5546 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, tvp); 5547 5548 error = 0; 5549 if (cache_fplookup_is_mp(fpl)) { 5550 error = cache_fplookup_cross_mount(fpl); 5551 } 5552 return (error); 5553 } 5554 5555 static bool 5556 cache_fplookup_mp_supported(struct mount *mp) 5557 { 5558 5559 MPASS(mp != NULL); 5560 if ((mp->mnt_kern_flag & MNTK_FPLOOKUP) == 0) 5561 return (false); 5562 return (true); 5563 } 5564 5565 /* 5566 * Walk up the mount stack (if any). 5567 * 5568 * Correctness is provided in the following ways: 5569 * - all vnodes are protected from freeing with SMR 5570 * - struct mount objects are type stable making them always safe to access 5571 * - stability of the particular mount is provided by busying it 5572 * - relationship between the vnode which is mounted on and the mount is 5573 * verified with the vnode sequence counter after busying 5574 * - association between root vnode of the mount and the mount is protected 5575 * by busy 5576 * 5577 * From that point on we can read the sequence counter of the root vnode 5578 * and get the next mount on the stack (if any) using the same protection. 5579 * 5580 * By the end of successful walk we are guaranteed the reached state was 5581 * indeed present at least at some point which matches the regular lookup. 5582 */ 5583 static int __noinline 5584 cache_fplookup_climb_mount(struct cache_fpl *fpl) 5585 { 5586 struct mount *mp, *prev_mp; 5587 struct mount_pcpu *mpcpu, *prev_mpcpu; 5588 struct vnode *vp; 5589 seqc_t vp_seqc; 5590 5591 vp = fpl->tvp; 5592 vp_seqc = fpl->tvp_seqc; 5593 5594 VNPASS(vp->v_type == VDIR || vp->v_type == VREG || vp->v_type == VBAD, vp); 5595 mp = atomic_load_ptr(&vp->v_mountedhere); 5596 if (__predict_false(mp == NULL)) { 5597 return (0); 5598 } 5599 5600 prev_mp = NULL; 5601 for (;;) { 5602 if (!vfs_op_thread_enter_crit(mp, mpcpu)) { 5603 if (prev_mp != NULL) 5604 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu); 5605 return (cache_fpl_partial(fpl)); 5606 } 5607 if (prev_mp != NULL) 5608 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu); 5609 if (!vn_seqc_consistent(vp, vp_seqc)) { 5610 vfs_op_thread_exit_crit(mp, mpcpu); 5611 return (cache_fpl_partial(fpl)); 5612 } 5613 if (!cache_fplookup_mp_supported(mp)) { 5614 vfs_op_thread_exit_crit(mp, mpcpu); 5615 return (cache_fpl_partial(fpl)); 5616 } 5617 vp = atomic_load_ptr(&mp->mnt_rootvnode); 5618 if (vp == NULL) { 5619 vfs_op_thread_exit_crit(mp, mpcpu); 5620 return (cache_fpl_partial(fpl)); 5621 } 5622 vp_seqc = vn_seqc_read_any(vp); 5623 if (seqc_in_modify(vp_seqc)) { 5624 vfs_op_thread_exit_crit(mp, mpcpu); 5625 return (cache_fpl_partial(fpl)); 5626 } 5627 prev_mp = mp; 5628 prev_mpcpu = mpcpu; 5629 mp = atomic_load_ptr(&vp->v_mountedhere); 5630 if (mp == NULL) 5631 break; 5632 } 5633 5634 vfs_op_thread_exit_crit(prev_mp, prev_mpcpu); 5635 fpl->tvp = vp; 5636 fpl->tvp_seqc = vp_seqc; 5637 return (0); 5638 } 5639 5640 static int __noinline 5641 cache_fplookup_cross_mount(struct cache_fpl *fpl) 5642 { 5643 struct mount *mp; 5644 struct mount_pcpu *mpcpu; 5645 struct vnode *vp; 5646 seqc_t vp_seqc; 5647 5648 vp = fpl->tvp; 5649 vp_seqc = fpl->tvp_seqc; 5650 5651 VNPASS(vp->v_type == VDIR || vp->v_type == VREG || vp->v_type == VBAD, vp); 5652 mp = atomic_load_ptr(&vp->v_mountedhere); 5653 if (__predict_false(mp == NULL)) { 5654 return (0); 5655 } 5656 5657 if (!vfs_op_thread_enter_crit(mp, mpcpu)) { 5658 return (cache_fpl_partial(fpl)); 5659 } 5660 if (!vn_seqc_consistent(vp, vp_seqc)) { 5661 vfs_op_thread_exit_crit(mp, mpcpu); 5662 return (cache_fpl_partial(fpl)); 5663 } 5664 if (!cache_fplookup_mp_supported(mp)) { 5665 vfs_op_thread_exit_crit(mp, mpcpu); 5666 return (cache_fpl_partial(fpl)); 5667 } 5668 vp = atomic_load_ptr(&mp->mnt_rootvnode); 5669 if (__predict_false(vp == NULL)) { 5670 vfs_op_thread_exit_crit(mp, mpcpu); 5671 return (cache_fpl_partial(fpl)); 5672 } 5673 vp_seqc = vn_seqc_read_any(vp); 5674 vfs_op_thread_exit_crit(mp, mpcpu); 5675 if (seqc_in_modify(vp_seqc)) { 5676 return (cache_fpl_partial(fpl)); 5677 } 5678 mp = atomic_load_ptr(&vp->v_mountedhere); 5679 if (__predict_false(mp != NULL)) { 5680 /* 5681 * There are possibly more mount points on top. 5682 * Normally this does not happen so for simplicity just start 5683 * over. 5684 */ 5685 return (cache_fplookup_climb_mount(fpl)); 5686 } 5687 5688 fpl->tvp = vp; 5689 fpl->tvp_seqc = vp_seqc; 5690 return (0); 5691 } 5692 5693 /* 5694 * Check if a vnode is mounted on. 5695 */ 5696 static bool 5697 cache_fplookup_is_mp(struct cache_fpl *fpl) 5698 { 5699 struct vnode *vp; 5700 5701 vp = fpl->tvp; 5702 return ((vn_irflag_read(vp) & VIRF_MOUNTPOINT) != 0); 5703 } 5704 5705 /* 5706 * Parse the path. 5707 * 5708 * The code was originally copy-pasted from regular lookup and despite 5709 * clean ups leaves performance on the table. Any modifications here 5710 * must take into account that in case off fallback the resulting 5711 * nameidata state has to be compatible with the original. 5712 */ 5713 5714 /* 5715 * Debug ni_pathlen tracking. 5716 */ 5717 #ifdef INVARIANTS 5718 static void 5719 cache_fpl_pathlen_add(struct cache_fpl *fpl, size_t n) 5720 { 5721 5722 fpl->debug.ni_pathlen += n; 5723 KASSERT(fpl->debug.ni_pathlen <= PATH_MAX, 5724 ("%s: pathlen overflow to %zd\n", __func__, fpl->debug.ni_pathlen)); 5725 } 5726 5727 static void 5728 cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n) 5729 { 5730 5731 fpl->debug.ni_pathlen -= n; 5732 KASSERT(fpl->debug.ni_pathlen <= PATH_MAX, 5733 ("%s: pathlen underflow to %zd\n", __func__, fpl->debug.ni_pathlen)); 5734 } 5735 5736 static void 5737 cache_fpl_pathlen_inc(struct cache_fpl *fpl) 5738 { 5739 5740 cache_fpl_pathlen_add(fpl, 1); 5741 } 5742 5743 static void 5744 cache_fpl_pathlen_dec(struct cache_fpl *fpl) 5745 { 5746 5747 cache_fpl_pathlen_sub(fpl, 1); 5748 } 5749 #else 5750 static void 5751 cache_fpl_pathlen_add(struct cache_fpl *fpl, size_t n) 5752 { 5753 } 5754 5755 static void 5756 cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n) 5757 { 5758 } 5759 5760 static void 5761 cache_fpl_pathlen_inc(struct cache_fpl *fpl) 5762 { 5763 } 5764 5765 static void 5766 cache_fpl_pathlen_dec(struct cache_fpl *fpl) 5767 { 5768 } 5769 #endif 5770 5771 static void 5772 cache_fplookup_parse(struct cache_fpl *fpl) 5773 { 5774 struct nameidata *ndp; 5775 struct componentname *cnp; 5776 struct vnode *dvp; 5777 char *cp; 5778 uint32_t hash; 5779 5780 ndp = fpl->ndp; 5781 cnp = fpl->cnp; 5782 dvp = fpl->dvp; 5783 5784 /* 5785 * Find the end of this path component, it is either / or nul. 5786 * 5787 * Store / as a temporary sentinel so that we only have one character 5788 * to test for. Pathnames tend to be short so this should not be 5789 * resulting in cache misses. 5790 * 5791 * TODO: fix this to be word-sized. 5792 */ 5793 MPASS(&cnp->cn_nameptr[fpl->debug.ni_pathlen - 1] >= cnp->cn_pnbuf); 5794 KASSERT(&cnp->cn_nameptr[fpl->debug.ni_pathlen - 1] == fpl->nulchar, 5795 ("%s: mismatch between pathlen (%zu) and nulchar (%p != %p), string [%s]\n", 5796 __func__, fpl->debug.ni_pathlen, &cnp->cn_nameptr[fpl->debug.ni_pathlen - 1], 5797 fpl->nulchar, cnp->cn_pnbuf)); 5798 KASSERT(*fpl->nulchar == '\0', 5799 ("%s: expected nul at %p; string [%s]\n", __func__, fpl->nulchar, 5800 cnp->cn_pnbuf)); 5801 hash = cache_get_hash_iter_start(dvp); 5802 *fpl->nulchar = '/'; 5803 for (cp = cnp->cn_nameptr; *cp != '/'; cp++) { 5804 KASSERT(*cp != '\0', 5805 ("%s: encountered unexpected nul; string [%s]\n", __func__, 5806 cnp->cn_nameptr)); 5807 hash = cache_get_hash_iter(*cp, hash); 5808 continue; 5809 } 5810 *fpl->nulchar = '\0'; 5811 fpl->hash = cache_get_hash_iter_finish(hash); 5812 5813 cnp->cn_namelen = cp - cnp->cn_nameptr; 5814 cache_fpl_pathlen_sub(fpl, cnp->cn_namelen); 5815 5816 #ifdef INVARIANTS 5817 /* 5818 * cache_get_hash only accepts lengths up to NAME_MAX. This is fine since 5819 * we are going to fail this lookup with ENAMETOOLONG (see below). 5820 */ 5821 if (cnp->cn_namelen <= NAME_MAX) { 5822 if (fpl->hash != cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp)) { 5823 panic("%s: mismatched hash for [%s] len %ld", __func__, 5824 cnp->cn_nameptr, cnp->cn_namelen); 5825 } 5826 } 5827 #endif 5828 5829 /* 5830 * Hack: we have to check if the found path component's length exceeds 5831 * NAME_MAX. However, the condition is very rarely true and check can 5832 * be elided in the common case -- if an entry was found in the cache, 5833 * then it could not have been too long to begin with. 5834 */ 5835 ndp->ni_next = cp; 5836 } 5837 5838 static void 5839 cache_fplookup_parse_advance(struct cache_fpl *fpl) 5840 { 5841 struct nameidata *ndp; 5842 struct componentname *cnp; 5843 5844 ndp = fpl->ndp; 5845 cnp = fpl->cnp; 5846 5847 cnp->cn_nameptr = ndp->ni_next; 5848 KASSERT(*(cnp->cn_nameptr) == '/', 5849 ("%s: should have seen slash at %p ; buf %p [%s]\n", __func__, 5850 cnp->cn_nameptr, cnp->cn_pnbuf, cnp->cn_pnbuf)); 5851 cnp->cn_nameptr++; 5852 cache_fpl_pathlen_dec(fpl); 5853 } 5854 5855 /* 5856 * Skip spurious slashes in a pathname (e.g., "foo///bar") and retry. 5857 * 5858 * Lockless lookup tries to elide checking for spurious slashes and should they 5859 * be present is guaranteed to fail to find an entry. In this case the caller 5860 * must check if the name starts with a slash and call this routine. It is 5861 * going to fast forward across the spurious slashes and set the state up for 5862 * retry. 5863 */ 5864 static int __noinline 5865 cache_fplookup_skip_slashes(struct cache_fpl *fpl) 5866 { 5867 struct nameidata *ndp; 5868 struct componentname *cnp; 5869 5870 ndp = fpl->ndp; 5871 cnp = fpl->cnp; 5872 5873 MPASS(*(cnp->cn_nameptr) == '/'); 5874 do { 5875 cnp->cn_nameptr++; 5876 cache_fpl_pathlen_dec(fpl); 5877 } while (*(cnp->cn_nameptr) == '/'); 5878 5879 /* 5880 * Go back to one slash so that cache_fplookup_parse_advance has 5881 * something to skip. 5882 */ 5883 cnp->cn_nameptr--; 5884 cache_fpl_pathlen_inc(fpl); 5885 5886 /* 5887 * cache_fplookup_parse_advance starts from ndp->ni_next 5888 */ 5889 ndp->ni_next = cnp->cn_nameptr; 5890 5891 /* 5892 * See cache_fplookup_dot. 5893 */ 5894 fpl->tvp = fpl->dvp; 5895 fpl->tvp_seqc = fpl->dvp_seqc; 5896 5897 return (0); 5898 } 5899 5900 /* 5901 * Handle trailing slashes (e.g., "foo/"). 5902 * 5903 * If a trailing slash is found the terminal vnode must be a directory. 5904 * Regular lookup shortens the path by nulifying the first trailing slash and 5905 * sets the TRAILINGSLASH flag to denote this took place. There are several 5906 * checks on it performed later. 5907 * 5908 * Similarly to spurious slashes, lockless lookup handles this in a speculative 5909 * manner relying on an invariant that a non-directory vnode will get a miss. 5910 * In this case cn_nameptr[0] == '\0' and cn_namelen == 0. 5911 * 5912 * Thus for a path like "foo/bar/" the code unwinds the state back to "bar/" 5913 * and denotes this is the last path component, which avoids looping back. 5914 * 5915 * Only plain lookups are supported for now to restrict corner cases to handle. 5916 */ 5917 static int __noinline 5918 cache_fplookup_trailingslash(struct cache_fpl *fpl) 5919 { 5920 #ifdef INVARIANTS 5921 size_t ni_pathlen; 5922 #endif 5923 struct nameidata *ndp; 5924 struct componentname *cnp; 5925 struct namecache *ncp; 5926 struct vnode *tvp; 5927 char *cn_nameptr_orig, *cn_nameptr_slash; 5928 seqc_t tvp_seqc; 5929 u_char nc_flag; 5930 5931 ndp = fpl->ndp; 5932 cnp = fpl->cnp; 5933 tvp = fpl->tvp; 5934 tvp_seqc = fpl->tvp_seqc; 5935 5936 MPASS(fpl->dvp == fpl->tvp); 5937 KASSERT(cache_fpl_istrailingslash(fpl), 5938 ("%s: expected trailing slash at %p; string [%s]\n", __func__, fpl->nulchar - 1, 5939 cnp->cn_pnbuf)); 5940 KASSERT(cnp->cn_nameptr[0] == '\0', 5941 ("%s: expected nul char at %p; string [%s]\n", __func__, &cnp->cn_nameptr[0], 5942 cnp->cn_pnbuf)); 5943 KASSERT(cnp->cn_namelen == 0, 5944 ("%s: namelen 0 but got %ld; string [%s]\n", __func__, cnp->cn_namelen, 5945 cnp->cn_pnbuf)); 5946 MPASS(cnp->cn_nameptr > cnp->cn_pnbuf); 5947 5948 if (cnp->cn_nameiop != LOOKUP) { 5949 return (cache_fpl_aborted(fpl)); 5950 } 5951 5952 if (__predict_false(tvp->v_type != VDIR)) { 5953 if (!vn_seqc_consistent(tvp, tvp_seqc)) { 5954 return (cache_fpl_aborted(fpl)); 5955 } 5956 cache_fpl_smr_exit(fpl); 5957 return (cache_fpl_handled_error(fpl, ENOTDIR)); 5958 } 5959 5960 /* 5961 * Denote the last component. 5962 */ 5963 ndp->ni_next = &cnp->cn_nameptr[0]; 5964 MPASS(cache_fpl_islastcn(ndp)); 5965 5966 /* 5967 * Unwind trailing slashes. 5968 */ 5969 cn_nameptr_orig = cnp->cn_nameptr; 5970 while (cnp->cn_nameptr >= cnp->cn_pnbuf) { 5971 cnp->cn_nameptr--; 5972 if (cnp->cn_nameptr[0] != '/') { 5973 break; 5974 } 5975 } 5976 5977 /* 5978 * Unwind to the beginning of the path component. 5979 * 5980 * Note the path may or may not have started with a slash. 5981 */ 5982 cn_nameptr_slash = cnp->cn_nameptr; 5983 while (cnp->cn_nameptr > cnp->cn_pnbuf) { 5984 cnp->cn_nameptr--; 5985 if (cnp->cn_nameptr[0] == '/') { 5986 break; 5987 } 5988 } 5989 if (cnp->cn_nameptr[0] == '/') { 5990 cnp->cn_nameptr++; 5991 } 5992 5993 cnp->cn_namelen = cn_nameptr_slash - cnp->cn_nameptr + 1; 5994 cache_fpl_pathlen_add(fpl, cn_nameptr_orig - cnp->cn_nameptr); 5995 cache_fpl_checkpoint(fpl); 5996 5997 #ifdef INVARIANTS 5998 ni_pathlen = fpl->nulchar - cnp->cn_nameptr + 1; 5999 if (ni_pathlen != fpl->debug.ni_pathlen) { 6000 panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n", 6001 __func__, ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar, 6002 cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf); 6003 } 6004 #endif 6005 6006 /* 6007 * If this was a "./" lookup the parent directory is already correct. 6008 */ 6009 if (cnp->cn_nameptr[0] == '.' && cnp->cn_namelen == 1) { 6010 return (0); 6011 } 6012 6013 /* 6014 * Otherwise we need to look it up. 6015 */ 6016 tvp = fpl->tvp; 6017 ncp = atomic_load_consume_ptr(&tvp->v_cache_dd); 6018 if (__predict_false(ncp == NULL)) { 6019 return (cache_fpl_aborted(fpl)); 6020 } 6021 nc_flag = atomic_load_char(&ncp->nc_flag); 6022 if ((nc_flag & NCF_ISDOTDOT) != 0) { 6023 return (cache_fpl_aborted(fpl)); 6024 } 6025 fpl->dvp = ncp->nc_dvp; 6026 fpl->dvp_seqc = vn_seqc_read_any(fpl->dvp); 6027 if (seqc_in_modify(fpl->dvp_seqc)) { 6028 return (cache_fpl_aborted(fpl)); 6029 } 6030 return (0); 6031 } 6032 6033 /* 6034 * See the API contract for VOP_FPLOOKUP_VEXEC. 6035 */ 6036 static int __noinline 6037 cache_fplookup_failed_vexec(struct cache_fpl *fpl, int error) 6038 { 6039 struct componentname *cnp; 6040 struct vnode *dvp; 6041 seqc_t dvp_seqc; 6042 6043 cnp = fpl->cnp; 6044 dvp = fpl->dvp; 6045 dvp_seqc = fpl->dvp_seqc; 6046 6047 /* 6048 * Hack: delayed empty path checking. 6049 */ 6050 if (cnp->cn_pnbuf[0] == '\0') { 6051 return (cache_fplookup_emptypath(fpl)); 6052 } 6053 6054 /* 6055 * TODO: Due to ignoring trailing slashes lookup will perform a 6056 * permission check on the last dir when it should not be doing it. It 6057 * may fail, but said failure should be ignored. It is possible to fix 6058 * it up fully without resorting to regular lookup, but for now just 6059 * abort. 6060 */ 6061 if (cache_fpl_istrailingslash(fpl)) { 6062 return (cache_fpl_aborted(fpl)); 6063 } 6064 6065 /* 6066 * Hack: delayed degenerate path checking. 6067 */ 6068 if (cnp->cn_nameptr[0] == '\0' && fpl->tvp == NULL) { 6069 return (cache_fplookup_degenerate(fpl)); 6070 } 6071 6072 /* 6073 * Hack: delayed name len checking. 6074 */ 6075 if (__predict_false(cnp->cn_namelen > NAME_MAX)) { 6076 cache_fpl_smr_exit(fpl); 6077 return (cache_fpl_handled_error(fpl, ENAMETOOLONG)); 6078 } 6079 6080 /* 6081 * Hack: they may be looking up foo/bar, where foo is not a directory. 6082 * In such a case we need to return ENOTDIR, but we may happen to get 6083 * here with a different error. 6084 */ 6085 if (dvp->v_type != VDIR) { 6086 error = ENOTDIR; 6087 } 6088 6089 /* 6090 * Hack: handle O_SEARCH. 6091 * 6092 * Open Group Base Specifications Issue 7, 2018 edition states: 6093 * <quote> 6094 * If the access mode of the open file description associated with the 6095 * file descriptor is not O_SEARCH, the function shall check whether 6096 * directory searches are permitted using the current permissions of 6097 * the directory underlying the file descriptor. If the access mode is 6098 * O_SEARCH, the function shall not perform the check. 6099 * </quote> 6100 * 6101 * Regular lookup tests for the NOEXECCHECK flag for every path 6102 * component to decide whether to do the permission check. However, 6103 * since most lookups never have the flag (and when they do it is only 6104 * present for the first path component), lockless lookup only acts on 6105 * it if there is a permission problem. Here the flag is represented 6106 * with a boolean so that we don't have to clear it on the way out. 6107 * 6108 * For simplicity this always aborts. 6109 * TODO: check if this is the first lookup and ignore the permission 6110 * problem. Note the flag has to survive fallback (if it happens to be 6111 * performed). 6112 */ 6113 if (fpl->fsearch) { 6114 return (cache_fpl_aborted(fpl)); 6115 } 6116 6117 switch (error) { 6118 case EAGAIN: 6119 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 6120 error = cache_fpl_aborted(fpl); 6121 } else { 6122 cache_fpl_partial(fpl); 6123 } 6124 break; 6125 default: 6126 if (!vn_seqc_consistent(dvp, dvp_seqc)) { 6127 error = cache_fpl_aborted(fpl); 6128 } else { 6129 cache_fpl_smr_exit(fpl); 6130 cache_fpl_handled_error(fpl, error); 6131 } 6132 break; 6133 } 6134 return (error); 6135 } 6136 6137 static int 6138 cache_fplookup_impl(struct vnode *dvp, struct cache_fpl *fpl) 6139 { 6140 struct nameidata *ndp; 6141 struct componentname *cnp; 6142 struct mount *mp; 6143 int error; 6144 6145 ndp = fpl->ndp; 6146 cnp = fpl->cnp; 6147 6148 cache_fpl_checkpoint(fpl); 6149 6150 /* 6151 * The vnode at hand is almost always stable, skip checking for it. 6152 * Worst case this postpones the check towards the end of the iteration 6153 * of the main loop. 6154 */ 6155 fpl->dvp = dvp; 6156 fpl->dvp_seqc = vn_seqc_read_notmodify(fpl->dvp); 6157 6158 mp = atomic_load_ptr(&dvp->v_mount); 6159 if (__predict_false(mp == NULL || !cache_fplookup_mp_supported(mp))) { 6160 return (cache_fpl_aborted(fpl)); 6161 } 6162 6163 MPASS(fpl->tvp == NULL); 6164 6165 for (;;) { 6166 cache_fplookup_parse(fpl); 6167 6168 error = VOP_FPLOOKUP_VEXEC(fpl->dvp, cnp->cn_cred); 6169 if (__predict_false(error != 0)) { 6170 error = cache_fplookup_failed_vexec(fpl, error); 6171 break; 6172 } 6173 6174 error = cache_fplookup_next(fpl); 6175 if (__predict_false(cache_fpl_terminated(fpl))) { 6176 break; 6177 } 6178 6179 VNPASS(!seqc_in_modify(fpl->tvp_seqc), fpl->tvp); 6180 6181 if (fpl->tvp->v_type == VLNK) { 6182 error = cache_fplookup_symlink(fpl); 6183 if (cache_fpl_terminated(fpl)) { 6184 break; 6185 } 6186 } else { 6187 if (cache_fpl_islastcn(ndp)) { 6188 error = cache_fplookup_final(fpl); 6189 break; 6190 } 6191 6192 if (!vn_seqc_consistent(fpl->dvp, fpl->dvp_seqc)) { 6193 error = cache_fpl_aborted(fpl); 6194 break; 6195 } 6196 6197 fpl->dvp = fpl->tvp; 6198 fpl->dvp_seqc = fpl->tvp_seqc; 6199 cache_fplookup_parse_advance(fpl); 6200 } 6201 6202 cache_fpl_checkpoint(fpl); 6203 } 6204 6205 return (error); 6206 } 6207 6208 /* 6209 * Fast path lookup protected with SMR and sequence counters. 6210 * 6211 * Note: all VOP_FPLOOKUP_VEXEC routines have a comment referencing this one. 6212 * 6213 * Filesystems can opt in by setting the MNTK_FPLOOKUP flag and meeting criteria 6214 * outlined below. 6215 * 6216 * Traditional vnode lookup conceptually looks like this: 6217 * 6218 * vn_lock(current); 6219 * for (;;) { 6220 * next = find(); 6221 * vn_lock(next); 6222 * vn_unlock(current); 6223 * current = next; 6224 * if (last) 6225 * break; 6226 * } 6227 * return (current); 6228 * 6229 * Each jump to the next vnode is safe memory-wise and atomic with respect to 6230 * any modifications thanks to holding respective locks. 6231 * 6232 * The same guarantee can be provided with a combination of safe memory 6233 * reclamation and sequence counters instead. If all operations which affect 6234 * the relationship between the current vnode and the one we are looking for 6235 * also modify the counter, we can verify whether all the conditions held as 6236 * we made the jump. This includes things like permissions, mount points etc. 6237 * Counter modification is provided by enclosing relevant places in 6238 * vn_seqc_write_begin()/end() calls. 6239 * 6240 * Thus this translates to: 6241 * 6242 * vfs_smr_enter(); 6243 * dvp_seqc = seqc_read_any(dvp); 6244 * if (seqc_in_modify(dvp_seqc)) // someone is altering the vnode 6245 * abort(); 6246 * for (;;) { 6247 * tvp = find(); 6248 * tvp_seqc = seqc_read_any(tvp); 6249 * if (seqc_in_modify(tvp_seqc)) // someone is altering the target vnode 6250 * abort(); 6251 * if (!seqc_consistent(dvp, dvp_seqc) // someone is altering the vnode 6252 * abort(); 6253 * dvp = tvp; // we know nothing of importance has changed 6254 * dvp_seqc = tvp_seqc; // store the counter for the tvp iteration 6255 * if (last) 6256 * break; 6257 * } 6258 * vget(); // secure the vnode 6259 * if (!seqc_consistent(tvp, tvp_seqc) // final check 6260 * abort(); 6261 * // at this point we know nothing has changed for any parent<->child pair 6262 * // as they were crossed during the lookup, meaning we matched the guarantee 6263 * // of the locked variant 6264 * return (tvp); 6265 * 6266 * The API contract for VOP_FPLOOKUP_VEXEC routines is as follows: 6267 * - they are called while within vfs_smr protection which they must never exit 6268 * - EAGAIN can be returned to denote checking could not be performed, it is 6269 * always valid to return it 6270 * - if the sequence counter has not changed the result must be valid 6271 * - if the sequence counter has changed both false positives and false negatives 6272 * are permitted (since the result will be rejected later) 6273 * - for simple cases of unix permission checks vaccess_vexec_smr can be used 6274 * 6275 * Caveats to watch out for: 6276 * - vnodes are passed unlocked and unreferenced with nothing stopping 6277 * VOP_RECLAIM, in turn meaning that ->v_data can become NULL. It is advised 6278 * to use atomic_load_ptr to fetch it. 6279 * - the aforementioned object can also get freed, meaning absent other means it 6280 * should be protected with vfs_smr 6281 * - either safely checking permissions as they are modified or guaranteeing 6282 * their stability is left to the routine 6283 */ 6284 int 6285 cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status, 6286 struct pwd **pwdp) 6287 { 6288 struct cache_fpl fpl; 6289 struct pwd *pwd; 6290 struct vnode *dvp; 6291 struct componentname *cnp; 6292 int error; 6293 6294 fpl.status = CACHE_FPL_STATUS_UNSET; 6295 fpl.in_smr = false; 6296 fpl.ndp = ndp; 6297 fpl.cnp = cnp = &ndp->ni_cnd; 6298 MPASS(ndp->ni_lcf == 0); 6299 KASSERT ((cnp->cn_flags & CACHE_FPL_INTERNAL_CN_FLAGS) == 0, 6300 ("%s: internal flags found in cn_flags %" PRIx64, __func__, 6301 cnp->cn_flags)); 6302 MPASS(cnp->cn_nameptr == cnp->cn_pnbuf); 6303 MPASS(ndp->ni_resflags == 0); 6304 6305 if (__predict_false(!cache_can_fplookup(&fpl))) { 6306 *status = fpl.status; 6307 SDT_PROBE3(vfs, fplookup, lookup, done, ndp, fpl.line, fpl.status); 6308 return (EOPNOTSUPP); 6309 } 6310 6311 cache_fpl_checkpoint_outer(&fpl); 6312 6313 cache_fpl_smr_enter_initial(&fpl); 6314 #ifdef INVARIANTS 6315 fpl.debug.ni_pathlen = ndp->ni_pathlen; 6316 #endif 6317 fpl.nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1]; 6318 fpl.fsearch = false; 6319 fpl.tvp = NULL; /* for degenerate path handling */ 6320 fpl.pwd = pwdp; 6321 pwd = pwd_get_smr(); 6322 *(fpl.pwd) = pwd; 6323 namei_setup_rootdir(ndp, cnp, pwd); 6324 ndp->ni_topdir = pwd->pwd_jdir; 6325 6326 if (cnp->cn_pnbuf[0] == '/') { 6327 dvp = cache_fpl_handle_root(&fpl); 6328 ndp->ni_resflags = NIRES_ABS; 6329 } else { 6330 if (ndp->ni_dirfd == AT_FDCWD) { 6331 dvp = pwd->pwd_cdir; 6332 } else { 6333 error = cache_fplookup_dirfd(&fpl, &dvp); 6334 if (__predict_false(error != 0)) { 6335 goto out; 6336 } 6337 } 6338 } 6339 6340 SDT_PROBE4(vfs, namei, lookup, entry, dvp, cnp->cn_pnbuf, cnp->cn_flags, true); 6341 error = cache_fplookup_impl(dvp, &fpl); 6342 out: 6343 cache_fpl_smr_assert_not_entered(&fpl); 6344 cache_fpl_assert_status(&fpl); 6345 *status = fpl.status; 6346 if (SDT_PROBES_ENABLED()) { 6347 SDT_PROBE3(vfs, fplookup, lookup, done, ndp, fpl.line, fpl.status); 6348 if (fpl.status == CACHE_FPL_STATUS_HANDLED) 6349 SDT_PROBE4(vfs, namei, lookup, return, error, ndp->ni_vp, true, 6350 ndp); 6351 } 6352 6353 if (__predict_true(fpl.status == CACHE_FPL_STATUS_HANDLED)) { 6354 MPASS(error != CACHE_FPL_FAILED); 6355 if (error != 0) { 6356 cache_fpl_cleanup_cnp(fpl.cnp); 6357 MPASS(fpl.dvp == NULL); 6358 MPASS(fpl.tvp == NULL); 6359 } 6360 ndp->ni_dvp = fpl.dvp; 6361 ndp->ni_vp = fpl.tvp; 6362 } 6363 return (error); 6364 } 6365