| 1 | /* |
| 2 | * Copyright (c) 2003,2004,2009 The DragonFly Project. All rights reserved. |
| 3 | * |
| 4 | * This code is derived from software contributed to The DragonFly Project |
| 5 | * by Matthew Dillon <dillon@backplane.com> |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in |
| 15 | * the documentation and/or other materials provided with the |
| 16 | * distribution. |
| 17 | * 3. Neither the name of The DragonFly Project nor the names of its |
| 18 | * contributors may be used to endorse or promote products derived |
| 19 | * from this software without specific, prior written permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 23 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 24 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 25 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 26 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 27 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 28 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 29 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 30 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| 31 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 32 | * SUCH DAMAGE. |
| 33 | * |
| 34 | * Copyright (c) 1989, 1993, 1995 |
| 35 | * The Regents of the University of California. All rights reserved. |
| 36 | * |
| 37 | * This code is derived from software contributed to Berkeley by |
| 38 | * Poul-Henning Kamp of the FreeBSD Project. |
| 39 | * |
| 40 | * Redistribution and use in source and binary forms, with or without |
| 41 | * modification, are permitted provided that the following conditions |
| 42 | * are met: |
| 43 | * 1. Redistributions of source code must retain the above copyright |
| 44 | * notice, this list of conditions and the following disclaimer. |
| 45 | * 2. Redistributions in binary form must reproduce the above copyright |
| 46 | * notice, this list of conditions and the following disclaimer in the |
| 47 | * documentation and/or other materials provided with the distribution. |
| 48 | * 3. All advertising materials mentioning features or use of this software |
| 49 | * must display the following acknowledgement: |
| 50 | * This product includes software developed by the University of |
| 51 | * California, Berkeley and its contributors. |
| 52 | * 4. Neither the name of the University nor the names of its contributors |
| 53 | * may be used to endorse or promote products derived from this software |
| 54 | * without specific prior written permission. |
| 55 | * |
| 56 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 57 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 58 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 59 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 60 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 61 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 62 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 63 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 64 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 65 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 66 | * SUCH DAMAGE. |
| 67 | */ |
| 68 | |
| 69 | #include <sys/param.h> |
| 70 | #include <sys/systm.h> |
| 71 | #include <sys/kernel.h> |
| 72 | #include <sys/sysctl.h> |
| 73 | #include <sys/mount.h> |
| 74 | #include <sys/vnode.h> |
| 75 | #include <sys/malloc.h> |
| 76 | #include <sys/sysproto.h> |
| 77 | #include <sys/spinlock.h> |
| 78 | #include <sys/proc.h> |
| 79 | #include <sys/namei.h> |
| 80 | #include <sys/nlookup.h> |
| 81 | #include <sys/filedesc.h> |
| 82 | #include <sys/fnv_hash.h> |
| 83 | #include <sys/globaldata.h> |
| 84 | #include <sys/kern_syscall.h> |
| 85 | #include <sys/dirent.h> |
| 86 | #include <ddb/ddb.h> |
| 87 | |
| 88 | #include <sys/sysref2.h> |
| 89 | #include <sys/spinlock2.h> |
| 90 | #include <sys/mplock2.h> |
| 91 | |
| 92 | #define MAX_RECURSION_DEPTH 64 |
| 93 | |
| 94 | /* |
| 95 | * Random lookups in the cache are accomplished with a hash table using |
| 96 | * a hash key of (nc_src_vp, name). Each hash chain has its own spin lock. |
| 97 | * |
| 98 | * Negative entries may exist and correspond to resolved namecache |
| 99 | * structures where nc_vp is NULL. In a negative entry, NCF_WHITEOUT |
| 100 | * will be set if the entry corresponds to a whited-out directory entry |
| 101 | * (verses simply not finding the entry at all). ncneglist is locked |
| 102 | * with a global spinlock (ncspin). |
| 103 | * |
| 104 | * MPSAFE RULES: |
| 105 | * |
| 106 | * (1) A ncp must be referenced before it can be locked. |
| 107 | * |
| 108 | * (2) A ncp must be locked in order to modify it. |
| 109 | * |
| 110 | * (3) ncp locks are always ordered child -> parent. That may seem |
| 111 | * backwards but forward scans use the hash table and thus can hold |
| 112 | * the parent unlocked when traversing downward. |
| 113 | * |
| 114 | * This allows insert/rename/delete/dot-dot and other operations |
| 115 | * to use ncp->nc_parent links. |
| 116 | * |
| 117 | * This also prevents a locked up e.g. NFS node from creating a |
| 118 | * chain reaction all the way back to the root vnode / namecache. |
| 119 | * |
| 120 | * (4) parent linkages require both the parent and child to be locked. |
| 121 | */ |
| 122 | |
| 123 | /* |
| 124 | * Structures associated with name cacheing. |
| 125 | */ |
| 126 | #define NCHHASH(hash) (&nchashtbl[(hash) & nchash]) |
| 127 | #define MINNEG 1024 |
| 128 | #define MINPOS 1024 |
| 129 | |
| 130 | MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); |
| 131 | |
| 132 | LIST_HEAD(nchash_list, namecache); |
| 133 | |
| 134 | struct nchash_head { |
| 135 | struct nchash_list list; |
| 136 | struct spinlock spin; |
| 137 | }; |
| 138 | |
| 139 | static struct nchash_head *nchashtbl; |
| 140 | static struct namecache_list ncneglist; |
| 141 | static struct spinlock ncspin; |
| 142 | |
| 143 | /* |
| 144 | * ncvp_debug - debug cache_fromvp(). This is used by the NFS server |
| 145 | * to create the namecache infrastructure leading to a dangling vnode. |
| 146 | * |
| 147 | * 0 Only errors are reported |
| 148 | * 1 Successes are reported |
| 149 | * 2 Successes + the whole directory scan is reported |
| 150 | * 3 Force the directory scan code run as if the parent vnode did not |
| 151 | * have a namecache record, even if it does have one. |
| 152 | */ |
| 153 | static int ncvp_debug; |
| 154 | SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, |
| 155 | "Namecache debug level (0-3)"); |
| 156 | |
| 157 | static u_long nchash; /* size of hash table */ |
| 158 | SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, |
| 159 | "Size of namecache hash table"); |
| 160 | |
| 161 | static int ncnegfactor = 16; /* ratio of negative entries */ |
| 162 | SYSCTL_INT(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, |
| 163 | "Ratio of namecache negative entries"); |
| 164 | |
| 165 | static int nclockwarn; /* warn on locked entries in ticks */ |
| 166 | SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, |
| 167 | "Warn on locked namecache entries in ticks"); |
| 168 | |
| 169 | static int numdefered; /* number of cache entries allocated */ |
| 170 | SYSCTL_INT(_debug, OID_AUTO, numdefered, CTLFLAG_RD, &numdefered, 0, |
| 171 | "Number of cache entries allocated"); |
| 172 | |
| 173 | static int ncposlimit; /* number of cache entries allocated */ |
| 174 | SYSCTL_INT(_debug, OID_AUTO, ncposlimit, CTLFLAG_RW, &ncposlimit, 0, |
| 175 | "Number of cache entries allocated"); |
| 176 | |
| 177 | SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), |
| 178 | "sizeof(struct vnode)"); |
| 179 | SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), |
| 180 | "sizeof(struct namecache)"); |
| 181 | |
| 182 | static int cache_resolve_mp(struct mount *mp); |
| 183 | static struct vnode *cache_dvpref(struct namecache *ncp); |
| 184 | static void _cache_lock(struct namecache *ncp); |
| 185 | static void _cache_setunresolved(struct namecache *ncp); |
| 186 | static void _cache_cleanneg(int count); |
| 187 | static void _cache_cleanpos(int count); |
| 188 | static void _cache_cleandefered(void); |
| 189 | |
| 190 | /* |
| 191 | * The new name cache statistics |
| 192 | */ |
| 193 | SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); |
| 194 | static int numneg; |
| 195 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, |
| 196 | "Number of negative namecache entries"); |
| 197 | static int numcache; |
| 198 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, |
| 199 | "Number of namecaches entries"); |
| 200 | static u_long numcalls; |
| 201 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcalls, CTLFLAG_RD, &numcalls, 0, |
| 202 | "Number of namecache lookups"); |
| 203 | static u_long numchecks; |
| 204 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numchecks, CTLFLAG_RD, &numchecks, 0, |
| 205 | "Number of checked entries in namecache lookups"); |
| 206 | |
| 207 | struct nchstats nchstats[SMP_MAXCPU]; |
| 208 | /* |
| 209 | * Export VFS cache effectiveness statistics to user-land. |
| 210 | * |
| 211 | * The statistics are left for aggregation to user-land so |
| 212 | * neat things can be achieved, like observing per-CPU cache |
| 213 | * distribution. |
| 214 | */ |
| 215 | static int |
| 216 | sysctl_nchstats(SYSCTL_HANDLER_ARGS) |
| 217 | { |
| 218 | struct globaldata *gd; |
| 219 | int i, error; |
| 220 | |
| 221 | error = 0; |
| 222 | for (i = 0; i < ncpus; ++i) { |
| 223 | gd = globaldata_find(i); |
| 224 | if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats), |
| 225 | sizeof(struct nchstats)))) |
| 226 | break; |
| 227 | } |
| 228 | |
| 229 | return (error); |
| 230 | } |
| 231 | SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD, |
| 232 | 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics"); |
| 233 | |
| 234 | static struct namecache *cache_zap(struct namecache *ncp, int nonblock); |
| 235 | |
| 236 | /* |
| 237 | * Namespace locking. The caller must already hold a reference to the |
| 238 | * namecache structure in order to lock/unlock it. This function prevents |
| 239 | * the namespace from being created or destroyed by accessors other then |
| 240 | * the lock holder. |
| 241 | * |
| 242 | * Note that holding a locked namecache structure prevents other threads |
| 243 | * from making namespace changes (e.g. deleting or creating), prevents |
| 244 | * vnode association state changes by other threads, and prevents the |
| 245 | * namecache entry from being resolved or unresolved by other threads. |
| 246 | * |
| 247 | * The lock owner has full authority to associate/disassociate vnodes |
| 248 | * and resolve/unresolve the locked ncp. |
| 249 | * |
| 250 | * The primary lock field is nc_exlocks. nc_locktd is set after the |
| 251 | * fact (when locking) or cleared prior to unlocking. |
| 252 | * |
| 253 | * WARNING! Holding a locked ncp will prevent a vnode from being destroyed |
| 254 | * or recycled, but it does NOT help you if the vnode had already |
| 255 | * initiated a recyclement. If this is important, use cache_get() |
| 256 | * rather then cache_lock() (and deal with the differences in the |
| 257 | * way the refs counter is handled). Or, alternatively, make an |
| 258 | * unconditional call to cache_validate() or cache_resolve() |
| 259 | * after cache_lock() returns. |
| 260 | * |
| 261 | * MPSAFE |
| 262 | */ |
| 263 | static |
| 264 | void |
| 265 | _cache_lock(struct namecache *ncp) |
| 266 | { |
| 267 | thread_t td; |
| 268 | int didwarn; |
| 269 | int error; |
| 270 | u_int count; |
| 271 | |
| 272 | KKASSERT(ncp->nc_refs != 0); |
| 273 | didwarn = 0; |
| 274 | td = curthread; |
| 275 | |
| 276 | for (;;) { |
| 277 | count = ncp->nc_exlocks; |
| 278 | |
| 279 | if (count == 0) { |
| 280 | if (atomic_cmpset_int(&ncp->nc_exlocks, 0, 1)) { |
| 281 | /* |
| 282 | * The vp associated with a locked ncp must |
| 283 | * be held to prevent it from being recycled. |
| 284 | * |
| 285 | * WARNING! If VRECLAIMED is set the vnode |
| 286 | * could already be in the middle of a recycle. |
| 287 | * Callers must use cache_vref() or |
| 288 | * cache_vget() on the locked ncp to |
| 289 | * validate the vp or set the cache entry |
| 290 | * to unresolved. |
| 291 | * |
| 292 | * NOTE! vhold() is allowed if we hold a |
| 293 | * lock on the ncp (which we do). |
| 294 | */ |
| 295 | ncp->nc_locktd = td; |
| 296 | if (ncp->nc_vp) |
| 297 | vhold(ncp->nc_vp); /* MPSAFE */ |
| 298 | break; |
| 299 | } |
| 300 | /* cmpset failed */ |
| 301 | continue; |
| 302 | } |
| 303 | if (ncp->nc_locktd == td) { |
| 304 | if (atomic_cmpset_int(&ncp->nc_exlocks, count, |
| 305 | count + 1)) { |
| 306 | break; |
| 307 | } |
| 308 | /* cmpset failed */ |
| 309 | continue; |
| 310 | } |
| 311 | tsleep_interlock(ncp, 0); |
| 312 | if (atomic_cmpset_int(&ncp->nc_exlocks, count, |
| 313 | count | NC_EXLOCK_REQ) == 0) { |
| 314 | /* cmpset failed */ |
| 315 | continue; |
| 316 | } |
| 317 | error = tsleep(ncp, PINTERLOCKED, "clock", nclockwarn); |
| 318 | if (error == EWOULDBLOCK) { |
| 319 | if (didwarn == 0) { |
| 320 | didwarn = ticks; |
| 321 | kprintf("[diagnostic] cache_lock: blocked " |
| 322 | "on %p", |
| 323 | ncp); |
| 324 | kprintf(" \"%*.*s\"\n", |
| 325 | ncp->nc_nlen, ncp->nc_nlen, |
| 326 | ncp->nc_name); |
| 327 | } |
| 328 | } |
| 329 | } |
| 330 | if (didwarn) { |
| 331 | kprintf("[diagnostic] cache_lock: unblocked %*.*s after " |
| 332 | "%d secs\n", |
| 333 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name, |
| 334 | (int)(ticks - didwarn) / hz); |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | /* |
| 339 | * NOTE: nc_refs may be zero if the ncp is interlocked by circumstance, |
| 340 | * such as the case where one of its children is locked. |
| 341 | * |
| 342 | * MPSAFE |
| 343 | */ |
| 344 | static |
| 345 | int |
| 346 | _cache_lock_nonblock(struct namecache *ncp) |
| 347 | { |
| 348 | thread_t td; |
| 349 | u_int count; |
| 350 | |
| 351 | td = curthread; |
| 352 | |
| 353 | for (;;) { |
| 354 | count = ncp->nc_exlocks; |
| 355 | |
| 356 | if (count == 0) { |
| 357 | if (atomic_cmpset_int(&ncp->nc_exlocks, 0, 1)) { |
| 358 | /* |
| 359 | * The vp associated with a locked ncp must |
| 360 | * be held to prevent it from being recycled. |
| 361 | * |
| 362 | * WARNING! If VRECLAIMED is set the vnode |
| 363 | * could already be in the middle of a recycle. |
| 364 | * Callers must use cache_vref() or |
| 365 | * cache_vget() on the locked ncp to |
| 366 | * validate the vp or set the cache entry |
| 367 | * to unresolved. |
| 368 | * |
| 369 | * NOTE! vhold() is allowed if we hold a |
| 370 | * lock on the ncp (which we do). |
| 371 | */ |
| 372 | ncp->nc_locktd = td; |
| 373 | if (ncp->nc_vp) |
| 374 | vhold(ncp->nc_vp); /* MPSAFE */ |
| 375 | break; |
| 376 | } |
| 377 | /* cmpset failed */ |
| 378 | continue; |
| 379 | } |
| 380 | if (ncp->nc_locktd == td) { |
| 381 | if (atomic_cmpset_int(&ncp->nc_exlocks, count, |
| 382 | count + 1)) { |
| 383 | break; |
| 384 | } |
| 385 | /* cmpset failed */ |
| 386 | continue; |
| 387 | } |
| 388 | return(EWOULDBLOCK); |
| 389 | } |
| 390 | return(0); |
| 391 | } |
| 392 | |
| 393 | /* |
| 394 | * Helper function |
| 395 | * |
| 396 | * NOTE: nc_refs can be 0 (degenerate case during _cache_drop). |
| 397 | * |
| 398 | * nc_locktd must be NULLed out prior to nc_exlocks getting cleared. |
| 399 | * |
| 400 | * MPSAFE |
| 401 | */ |
| 402 | static |
| 403 | void |
| 404 | _cache_unlock(struct namecache *ncp) |
| 405 | { |
| 406 | thread_t td __debugvar = curthread; |
| 407 | u_int count; |
| 408 | |
| 409 | KKASSERT(ncp->nc_refs >= 0); |
| 410 | KKASSERT(ncp->nc_exlocks > 0); |
| 411 | KKASSERT(ncp->nc_locktd == td); |
| 412 | |
| 413 | count = ncp->nc_exlocks; |
| 414 | if ((count & ~NC_EXLOCK_REQ) == 1) { |
| 415 | ncp->nc_locktd = NULL; |
| 416 | if (ncp->nc_vp) |
| 417 | vdrop(ncp->nc_vp); |
| 418 | } |
| 419 | for (;;) { |
| 420 | if ((count & ~NC_EXLOCK_REQ) == 1) { |
| 421 | if (atomic_cmpset_int(&ncp->nc_exlocks, count, 0)) { |
| 422 | if (count & NC_EXLOCK_REQ) |
| 423 | wakeup(ncp); |
| 424 | break; |
| 425 | } |
| 426 | } else { |
| 427 | if (atomic_cmpset_int(&ncp->nc_exlocks, count, |
| 428 | count - 1)) { |
| 429 | break; |
| 430 | } |
| 431 | } |
| 432 | count = ncp->nc_exlocks; |
| 433 | } |
| 434 | } |
| 435 | |
| 436 | |
| 437 | /* |
| 438 | * cache_hold() and cache_drop() prevent the premature deletion of a |
| 439 | * namecache entry but do not prevent operations (such as zapping) on |
| 440 | * that namecache entry. |
| 441 | * |
| 442 | * This routine may only be called from outside this source module if |
| 443 | * nc_refs is already at least 1. |
| 444 | * |
| 445 | * This is a rare case where callers are allowed to hold a spinlock, |
| 446 | * so we can't ourselves. |
| 447 | * |
| 448 | * MPSAFE |
| 449 | */ |
| 450 | static __inline |
| 451 | struct namecache * |
| 452 | _cache_hold(struct namecache *ncp) |
| 453 | { |
| 454 | atomic_add_int(&ncp->nc_refs, 1); |
| 455 | return(ncp); |
| 456 | } |
| 457 | |
| 458 | /* |
| 459 | * Drop a cache entry, taking care to deal with races. |
| 460 | * |
| 461 | * For potential 1->0 transitions we must hold the ncp lock to safely |
| 462 | * test its flags. An unresolved entry with no children must be zapped |
| 463 | * to avoid leaks. |
| 464 | * |
| 465 | * The call to cache_zap() itself will handle all remaining races and |
| 466 | * will decrement the ncp's refs regardless. If we are resolved or |
| 467 | * have children nc_refs can safely be dropped to 0 without having to |
| 468 | * zap the entry. |
| 469 | * |
| 470 | * NOTE: cache_zap() will re-check nc_refs and nc_list in a MPSAFE fashion. |
| 471 | * |
| 472 | * NOTE: cache_zap() may return a non-NULL referenced parent which must |
| 473 | * be dropped in a loop. |
| 474 | * |
| 475 | * MPSAFE |
| 476 | */ |
| 477 | static __inline |
| 478 | void |
| 479 | _cache_drop(struct namecache *ncp) |
| 480 | { |
| 481 | int refs; |
| 482 | |
| 483 | while (ncp) { |
| 484 | KKASSERT(ncp->nc_refs > 0); |
| 485 | refs = ncp->nc_refs; |
| 486 | |
| 487 | if (refs == 1) { |
| 488 | if (_cache_lock_nonblock(ncp) == 0) { |
| 489 | ncp->nc_flag &= ~NCF_DEFEREDZAP; |
| 490 | if ((ncp->nc_flag & NCF_UNRESOLVED) && |
| 491 | TAILQ_EMPTY(&ncp->nc_list)) { |
| 492 | ncp = cache_zap(ncp, 1); |
| 493 | continue; |
| 494 | } |
| 495 | if (atomic_cmpset_int(&ncp->nc_refs, 1, 0)) { |
| 496 | _cache_unlock(ncp); |
| 497 | break; |
| 498 | } |
| 499 | _cache_unlock(ncp); |
| 500 | } |
| 501 | } else { |
| 502 | if (atomic_cmpset_int(&ncp->nc_refs, refs, refs - 1)) |
| 503 | break; |
| 504 | } |
| 505 | cpu_pause(); |
| 506 | } |
| 507 | } |
| 508 | |
| 509 | /* |
| 510 | * Link a new namecache entry to its parent and to the hash table. Be |
| 511 | * careful to avoid races if vhold() blocks in the future. |
| 512 | * |
| 513 | * Both ncp and par must be referenced and locked. |
| 514 | * |
| 515 | * NOTE: The hash table spinlock is likely held during this call, we |
| 516 | * can't do anything fancy. |
| 517 | * |
| 518 | * MPSAFE |
| 519 | */ |
| 520 | static void |
| 521 | _cache_link_parent(struct namecache *ncp, struct namecache *par, |
| 522 | struct nchash_head *nchpp) |
| 523 | { |
| 524 | KKASSERT(ncp->nc_parent == NULL); |
| 525 | ncp->nc_parent = par; |
| 526 | ncp->nc_head = nchpp; |
| 527 | |
| 528 | /* |
| 529 | * Set inheritance flags. Note that the parent flags may be |
| 530 | * stale due to getattr potentially not having been run yet |
| 531 | * (it gets run during nlookup()'s). |
| 532 | */ |
| 533 | ncp->nc_flag &= ~(NCF_SF_PNOCACHE | NCF_UF_PCACHE); |
| 534 | if (par->nc_flag & (NCF_SF_NOCACHE | NCF_SF_PNOCACHE)) |
| 535 | ncp->nc_flag |= NCF_SF_PNOCACHE; |
| 536 | if (par->nc_flag & (NCF_UF_CACHE | NCF_UF_PCACHE)) |
| 537 | ncp->nc_flag |= NCF_UF_PCACHE; |
| 538 | |
| 539 | LIST_INSERT_HEAD(&nchpp->list, ncp, nc_hash); |
| 540 | |
| 541 | if (TAILQ_EMPTY(&par->nc_list)) { |
| 542 | TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); |
| 543 | /* |
| 544 | * Any vp associated with an ncp which has children must |
| 545 | * be held to prevent it from being recycled. |
| 546 | */ |
| 547 | if (par->nc_vp) |
| 548 | vhold(par->nc_vp); |
| 549 | } else { |
| 550 | TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); |
| 551 | } |
| 552 | } |
| 553 | |
| 554 | /* |
| 555 | * Remove the parent and hash associations from a namecache structure. |
| 556 | * If this is the last child of the parent the cache_drop(par) will |
| 557 | * attempt to recursively zap the parent. |
| 558 | * |
| 559 | * ncp must be locked. This routine will acquire a temporary lock on |
| 560 | * the parent as wlel as the appropriate hash chain. |
| 561 | * |
| 562 | * MPSAFE |
| 563 | */ |
| 564 | static void |
| 565 | _cache_unlink_parent(struct namecache *ncp) |
| 566 | { |
| 567 | struct namecache *par; |
| 568 | struct vnode *dropvp; |
| 569 | |
| 570 | if ((par = ncp->nc_parent) != NULL) { |
| 571 | KKASSERT(ncp->nc_parent == par); |
| 572 | _cache_hold(par); |
| 573 | _cache_lock(par); |
| 574 | spin_lock(&ncp->nc_head->spin); |
| 575 | LIST_REMOVE(ncp, nc_hash); |
| 576 | TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); |
| 577 | dropvp = NULL; |
| 578 | if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) |
| 579 | dropvp = par->nc_vp; |
| 580 | spin_unlock(&ncp->nc_head->spin); |
| 581 | ncp->nc_parent = NULL; |
| 582 | ncp->nc_head = NULL; |
| 583 | _cache_unlock(par); |
| 584 | _cache_drop(par); |
| 585 | |
| 586 | /* |
| 587 | * We can only safely vdrop with no spinlocks held. |
| 588 | */ |
| 589 | if (dropvp) |
| 590 | vdrop(dropvp); |
| 591 | } |
| 592 | } |
| 593 | |
| 594 | /* |
| 595 | * Allocate a new namecache structure. Most of the code does not require |
| 596 | * zero-termination of the string but it makes vop_compat_ncreate() easier. |
| 597 | * |
| 598 | * MPSAFE |
| 599 | */ |
| 600 | static struct namecache * |
| 601 | cache_alloc(int nlen) |
| 602 | { |
| 603 | struct namecache *ncp; |
| 604 | |
| 605 | ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); |
| 606 | if (nlen) |
| 607 | ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK); |
| 608 | ncp->nc_nlen = nlen; |
| 609 | ncp->nc_flag = NCF_UNRESOLVED; |
| 610 | ncp->nc_error = ENOTCONN; /* needs to be resolved */ |
| 611 | ncp->nc_refs = 1; |
| 612 | |
| 613 | TAILQ_INIT(&ncp->nc_list); |
| 614 | _cache_lock(ncp); |
| 615 | return(ncp); |
| 616 | } |
| 617 | |
| 618 | /* |
| 619 | * Can only be called for the case where the ncp has never been |
| 620 | * associated with anything (so no spinlocks are needed). |
| 621 | * |
| 622 | * MPSAFE |
| 623 | */ |
| 624 | static void |
| 625 | _cache_free(struct namecache *ncp) |
| 626 | { |
| 627 | KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); |
| 628 | if (ncp->nc_name) |
| 629 | kfree(ncp->nc_name, M_VFSCACHE); |
| 630 | kfree(ncp, M_VFSCACHE); |
| 631 | } |
| 632 | |
| 633 | /* |
| 634 | * MPSAFE |
| 635 | */ |
| 636 | void |
| 637 | cache_zero(struct nchandle *nch) |
| 638 | { |
| 639 | nch->ncp = NULL; |
| 640 | nch->mount = NULL; |
| 641 | } |
| 642 | |
| 643 | /* |
| 644 | * Ref and deref a namecache structure. |
| 645 | * |
| 646 | * The caller must specify a stable ncp pointer, typically meaning the |
| 647 | * ncp is already referenced but this can also occur indirectly through |
| 648 | * e.g. holding a lock on a direct child. |
| 649 | * |
| 650 | * WARNING: Caller may hold an unrelated read spinlock, which means we can't |
| 651 | * use read spinlocks here. |
| 652 | * |
| 653 | * MPSAFE if nch is |
| 654 | */ |
| 655 | struct nchandle * |
| 656 | cache_hold(struct nchandle *nch) |
| 657 | { |
| 658 | _cache_hold(nch->ncp); |
| 659 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 660 | return(nch); |
| 661 | } |
| 662 | |
| 663 | /* |
| 664 | * Create a copy of a namecache handle for an already-referenced |
| 665 | * entry. |
| 666 | * |
| 667 | * MPSAFE if nch is |
| 668 | */ |
| 669 | void |
| 670 | cache_copy(struct nchandle *nch, struct nchandle *target) |
| 671 | { |
| 672 | *target = *nch; |
| 673 | if (target->ncp) |
| 674 | _cache_hold(target->ncp); |
| 675 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 676 | } |
| 677 | |
| 678 | /* |
| 679 | * MPSAFE if nch is |
| 680 | */ |
| 681 | void |
| 682 | cache_changemount(struct nchandle *nch, struct mount *mp) |
| 683 | { |
| 684 | atomic_add_int(&nch->mount->mnt_refs, -1); |
| 685 | nch->mount = mp; |
| 686 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 687 | } |
| 688 | |
| 689 | /* |
| 690 | * MPSAFE |
| 691 | */ |
| 692 | void |
| 693 | cache_drop(struct nchandle *nch) |
| 694 | { |
| 695 | atomic_add_int(&nch->mount->mnt_refs, -1); |
| 696 | _cache_drop(nch->ncp); |
| 697 | nch->ncp = NULL; |
| 698 | nch->mount = NULL; |
| 699 | } |
| 700 | |
| 701 | /* |
| 702 | * MPSAFE |
| 703 | */ |
| 704 | void |
| 705 | cache_lock(struct nchandle *nch) |
| 706 | { |
| 707 | _cache_lock(nch->ncp); |
| 708 | } |
| 709 | |
| 710 | /* |
| 711 | * Relock nch1 given an unlocked nch1 and a locked nch2. The caller |
| 712 | * is responsible for checking both for validity on return as they |
| 713 | * may have become invalid. |
| 714 | * |
| 715 | * We have to deal with potential deadlocks here, just ping pong |
| 716 | * the lock until we get it (we will always block somewhere when |
| 717 | * looping so this is not cpu-intensive). |
| 718 | * |
| 719 | * which = 0 nch1 not locked, nch2 is locked |
| 720 | * which = 1 nch1 is locked, nch2 is not locked |
| 721 | */ |
| 722 | void |
| 723 | cache_relock(struct nchandle *nch1, struct ucred *cred1, |
| 724 | struct nchandle *nch2, struct ucred *cred2) |
| 725 | { |
| 726 | int which; |
| 727 | |
| 728 | which = 0; |
| 729 | |
| 730 | for (;;) { |
| 731 | if (which == 0) { |
| 732 | if (cache_lock_nonblock(nch1) == 0) { |
| 733 | cache_resolve(nch1, cred1); |
| 734 | break; |
| 735 | } |
| 736 | cache_unlock(nch2); |
| 737 | cache_lock(nch1); |
| 738 | cache_resolve(nch1, cred1); |
| 739 | which = 1; |
| 740 | } else { |
| 741 | if (cache_lock_nonblock(nch2) == 0) { |
| 742 | cache_resolve(nch2, cred2); |
| 743 | break; |
| 744 | } |
| 745 | cache_unlock(nch1); |
| 746 | cache_lock(nch2); |
| 747 | cache_resolve(nch2, cred2); |
| 748 | which = 0; |
| 749 | } |
| 750 | } |
| 751 | } |
| 752 | |
| 753 | /* |
| 754 | * MPSAFE |
| 755 | */ |
| 756 | int |
| 757 | cache_lock_nonblock(struct nchandle *nch) |
| 758 | { |
| 759 | return(_cache_lock_nonblock(nch->ncp)); |
| 760 | } |
| 761 | |
| 762 | |
| 763 | /* |
| 764 | * MPSAFE |
| 765 | */ |
| 766 | void |
| 767 | cache_unlock(struct nchandle *nch) |
| 768 | { |
| 769 | _cache_unlock(nch->ncp); |
| 770 | } |
| 771 | |
| 772 | /* |
| 773 | * ref-and-lock, unlock-and-deref functions. |
| 774 | * |
| 775 | * This function is primarily used by nlookup. Even though cache_lock |
| 776 | * holds the vnode, it is possible that the vnode may have already |
| 777 | * initiated a recyclement. |
| 778 | * |
| 779 | * We want cache_get() to return a definitively usable vnode or a |
| 780 | * definitively unresolved ncp. |
| 781 | * |
| 782 | * MPSAFE |
| 783 | */ |
| 784 | static |
| 785 | struct namecache * |
| 786 | _cache_get(struct namecache *ncp) |
| 787 | { |
| 788 | _cache_hold(ncp); |
| 789 | _cache_lock(ncp); |
| 790 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 791 | _cache_setunresolved(ncp); |
| 792 | return(ncp); |
| 793 | } |
| 794 | |
| 795 | /* |
| 796 | * This is a special form of _cache_lock() which only succeeds if |
| 797 | * it can get a pristine, non-recursive lock. The caller must have |
| 798 | * already ref'd the ncp. |
| 799 | * |
| 800 | * On success the ncp will be locked, on failure it will not. The |
| 801 | * ref count does not change either way. |
| 802 | * |
| 803 | * We want _cache_lock_special() (on success) to return a definitively |
| 804 | * usable vnode or a definitively unresolved ncp. |
| 805 | * |
| 806 | * MPSAFE |
| 807 | */ |
| 808 | static int |
| 809 | _cache_lock_special(struct namecache *ncp) |
| 810 | { |
| 811 | if (_cache_lock_nonblock(ncp) == 0) { |
| 812 | if ((ncp->nc_exlocks & ~NC_EXLOCK_REQ) == 1) { |
| 813 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 814 | _cache_setunresolved(ncp); |
| 815 | return(0); |
| 816 | } |
| 817 | _cache_unlock(ncp); |
| 818 | } |
| 819 | return(EWOULDBLOCK); |
| 820 | } |
| 821 | |
| 822 | |
| 823 | /* |
| 824 | * NOTE: The same nchandle can be passed for both arguments. |
| 825 | * |
| 826 | * MPSAFE |
| 827 | */ |
| 828 | void |
| 829 | cache_get(struct nchandle *nch, struct nchandle *target) |
| 830 | { |
| 831 | KKASSERT(nch->ncp->nc_refs > 0); |
| 832 | target->mount = nch->mount; |
| 833 | target->ncp = _cache_get(nch->ncp); |
| 834 | atomic_add_int(&target->mount->mnt_refs, 1); |
| 835 | } |
| 836 | |
| 837 | /* |
| 838 | * MPSAFE |
| 839 | */ |
| 840 | static __inline |
| 841 | void |
| 842 | _cache_put(struct namecache *ncp) |
| 843 | { |
| 844 | _cache_unlock(ncp); |
| 845 | _cache_drop(ncp); |
| 846 | } |
| 847 | |
| 848 | /* |
| 849 | * MPSAFE |
| 850 | */ |
| 851 | void |
| 852 | cache_put(struct nchandle *nch) |
| 853 | { |
| 854 | atomic_add_int(&nch->mount->mnt_refs, -1); |
| 855 | _cache_put(nch->ncp); |
| 856 | nch->ncp = NULL; |
| 857 | nch->mount = NULL; |
| 858 | } |
| 859 | |
| 860 | /* |
| 861 | * Resolve an unresolved ncp by associating a vnode with it. If the |
| 862 | * vnode is NULL, a negative cache entry is created. |
| 863 | * |
| 864 | * The ncp should be locked on entry and will remain locked on return. |
| 865 | * |
| 866 | * MPSAFE |
| 867 | */ |
| 868 | static |
| 869 | void |
| 870 | _cache_setvp(struct mount *mp, struct namecache *ncp, struct vnode *vp) |
| 871 | { |
| 872 | KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); |
| 873 | |
| 874 | if (vp != NULL) { |
| 875 | /* |
| 876 | * Any vp associated with an ncp which has children must |
| 877 | * be held. Any vp associated with a locked ncp must be held. |
| 878 | */ |
| 879 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 880 | vhold(vp); |
| 881 | spin_lock(&vp->v_spin); |
| 882 | ncp->nc_vp = vp; |
| 883 | TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); |
| 884 | spin_unlock(&vp->v_spin); |
| 885 | if (ncp->nc_exlocks) |
| 886 | vhold(vp); |
| 887 | |
| 888 | /* |
| 889 | * Set auxiliary flags |
| 890 | */ |
| 891 | switch(vp->v_type) { |
| 892 | case VDIR: |
| 893 | ncp->nc_flag |= NCF_ISDIR; |
| 894 | break; |
| 895 | case VLNK: |
| 896 | ncp->nc_flag |= NCF_ISSYMLINK; |
| 897 | /* XXX cache the contents of the symlink */ |
| 898 | break; |
| 899 | default: |
| 900 | break; |
| 901 | } |
| 902 | atomic_add_int(&numcache, 1); |
| 903 | ncp->nc_error = 0; |
| 904 | /* XXX: this is a hack to work-around the lack of a real pfs vfs |
| 905 | * implementation*/ |
| 906 | if (mp != NULL) |
| 907 | vp->v_pfsmp = mp; |
| 908 | } else { |
| 909 | /* |
| 910 | * When creating a negative cache hit we set the |
| 911 | * namecache_gen. A later resolve will clean out the |
| 912 | * negative cache hit if the mount point's namecache_gen |
| 913 | * has changed. Used by devfs, could also be used by |
| 914 | * other remote FSs. |
| 915 | */ |
| 916 | ncp->nc_vp = NULL; |
| 917 | spin_lock(&ncspin); |
| 918 | TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); |
| 919 | ++numneg; |
| 920 | spin_unlock(&ncspin); |
| 921 | ncp->nc_error = ENOENT; |
| 922 | if (mp) |
| 923 | ncp->nc_namecache_gen = mp->mnt_namecache_gen; |
| 924 | } |
| 925 | ncp->nc_flag &= ~(NCF_UNRESOLVED | NCF_DEFEREDZAP); |
| 926 | } |
| 927 | |
| 928 | /* |
| 929 | * MPSAFE |
| 930 | */ |
| 931 | void |
| 932 | cache_setvp(struct nchandle *nch, struct vnode *vp) |
| 933 | { |
| 934 | _cache_setvp(nch->mount, nch->ncp, vp); |
| 935 | } |
| 936 | |
| 937 | /* |
| 938 | * MPSAFE |
| 939 | */ |
| 940 | void |
| 941 | cache_settimeout(struct nchandle *nch, int nticks) |
| 942 | { |
| 943 | struct namecache *ncp = nch->ncp; |
| 944 | |
| 945 | if ((ncp->nc_timeout = ticks + nticks) == 0) |
| 946 | ncp->nc_timeout = 1; |
| 947 | } |
| 948 | |
| 949 | /* |
| 950 | * Disassociate the vnode or negative-cache association and mark a |
| 951 | * namecache entry as unresolved again. Note that the ncp is still |
| 952 | * left in the hash table and still linked to its parent. |
| 953 | * |
| 954 | * The ncp should be locked and refd on entry and will remain locked and refd |
| 955 | * on return. |
| 956 | * |
| 957 | * This routine is normally never called on a directory containing children. |
| 958 | * However, NFS often does just that in its rename() code as a cop-out to |
| 959 | * avoid complex namespace operations. This disconnects a directory vnode |
| 960 | * from its namecache and can cause the OLDAPI and NEWAPI to get out of |
| 961 | * sync. |
| 962 | * |
| 963 | * MPSAFE |
| 964 | */ |
| 965 | static |
| 966 | void |
| 967 | _cache_setunresolved(struct namecache *ncp) |
| 968 | { |
| 969 | struct vnode *vp; |
| 970 | |
| 971 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 972 | ncp->nc_flag |= NCF_UNRESOLVED; |
| 973 | ncp->nc_timeout = 0; |
| 974 | ncp->nc_error = ENOTCONN; |
| 975 | if ((vp = ncp->nc_vp) != NULL) { |
| 976 | atomic_add_int(&numcache, -1); |
| 977 | spin_lock(&vp->v_spin); |
| 978 | ncp->nc_vp = NULL; |
| 979 | TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); |
| 980 | spin_unlock(&vp->v_spin); |
| 981 | |
| 982 | /* |
| 983 | * Any vp associated with an ncp with children is |
| 984 | * held by that ncp. Any vp associated with a locked |
| 985 | * ncp is held by that ncp. These conditions must be |
| 986 | * undone when the vp is cleared out from the ncp. |
| 987 | */ |
| 988 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 989 | vdrop(vp); |
| 990 | if (ncp->nc_exlocks) |
| 991 | vdrop(vp); |
| 992 | } else { |
| 993 | spin_lock(&ncspin); |
| 994 | TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); |
| 995 | --numneg; |
| 996 | spin_unlock(&ncspin); |
| 997 | } |
| 998 | ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK); |
| 999 | } |
| 1000 | } |
| 1001 | |
| 1002 | /* |
| 1003 | * The cache_nresolve() code calls this function to automatically |
| 1004 | * set a resolved cache element to unresolved if it has timed out |
| 1005 | * or if it is a negative cache hit and the mount point namecache_gen |
| 1006 | * has changed. |
| 1007 | * |
| 1008 | * MPSAFE |
| 1009 | */ |
| 1010 | static __inline void |
| 1011 | _cache_auto_unresolve(struct mount *mp, struct namecache *ncp) |
| 1012 | { |
| 1013 | /* |
| 1014 | * Already in an unresolved state, nothing to do. |
| 1015 | */ |
| 1016 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 1017 | return; |
| 1018 | |
| 1019 | /* |
| 1020 | * Try to zap entries that have timed out. We have |
| 1021 | * to be careful here because locked leafs may depend |
| 1022 | * on the vnode remaining intact in a parent, so only |
| 1023 | * do this under very specific conditions. |
| 1024 | */ |
| 1025 | if (ncp->nc_timeout && (int)(ncp->nc_timeout - ticks) < 0 && |
| 1026 | TAILQ_EMPTY(&ncp->nc_list)) { |
| 1027 | _cache_setunresolved(ncp); |
| 1028 | return; |
| 1029 | } |
| 1030 | |
| 1031 | /* |
| 1032 | * If a resolved negative cache hit is invalid due to |
| 1033 | * the mount's namecache generation being bumped, zap it. |
| 1034 | */ |
| 1035 | if (ncp->nc_vp == NULL && |
| 1036 | ncp->nc_namecache_gen != mp->mnt_namecache_gen) { |
| 1037 | _cache_setunresolved(ncp); |
| 1038 | return; |
| 1039 | } |
| 1040 | } |
| 1041 | |
| 1042 | /* |
| 1043 | * MPSAFE |
| 1044 | */ |
| 1045 | void |
| 1046 | cache_setunresolved(struct nchandle *nch) |
| 1047 | { |
| 1048 | _cache_setunresolved(nch->ncp); |
| 1049 | } |
| 1050 | |
| 1051 | /* |
| 1052 | * Determine if we can clear NCF_ISMOUNTPT by scanning the mountlist |
| 1053 | * looking for matches. This flag tells the lookup code when it must |
| 1054 | * check for a mount linkage and also prevents the directories in question |
| 1055 | * from being deleted or renamed. |
| 1056 | * |
| 1057 | * MPSAFE |
| 1058 | */ |
| 1059 | static |
| 1060 | int |
| 1061 | cache_clrmountpt_callback(struct mount *mp, void *data) |
| 1062 | { |
| 1063 | struct nchandle *nch = data; |
| 1064 | |
| 1065 | if (mp->mnt_ncmounton.ncp == nch->ncp) |
| 1066 | return(1); |
| 1067 | if (mp->mnt_ncmountpt.ncp == nch->ncp) |
| 1068 | return(1); |
| 1069 | return(0); |
| 1070 | } |
| 1071 | |
| 1072 | /* |
| 1073 | * MPSAFE |
| 1074 | */ |
| 1075 | void |
| 1076 | cache_clrmountpt(struct nchandle *nch) |
| 1077 | { |
| 1078 | int count; |
| 1079 | |
| 1080 | count = mountlist_scan(cache_clrmountpt_callback, nch, |
| 1081 | MNTSCAN_FORWARD|MNTSCAN_NOBUSY); |
| 1082 | if (count == 0) |
| 1083 | nch->ncp->nc_flag &= ~NCF_ISMOUNTPT; |
| 1084 | } |
| 1085 | |
| 1086 | /* |
| 1087 | * Invalidate portions of the namecache topology given a starting entry. |
| 1088 | * The passed ncp is set to an unresolved state and: |
| 1089 | * |
| 1090 | * The passed ncp must be referencxed and locked. The routine may unlock |
| 1091 | * and relock ncp several times, and will recheck the children and loop |
| 1092 | * to catch races. When done the passed ncp will be returned with the |
| 1093 | * reference and lock intact. |
| 1094 | * |
| 1095 | * CINV_DESTROY - Set a flag in the passed ncp entry indicating |
| 1096 | * that the physical underlying nodes have been |
| 1097 | * destroyed... as in deleted. For example, when |
| 1098 | * a directory is removed. This will cause record |
| 1099 | * lookups on the name to no longer be able to find |
| 1100 | * the record and tells the resolver to return failure |
| 1101 | * rather then trying to resolve through the parent. |
| 1102 | * |
| 1103 | * The topology itself, including ncp->nc_name, |
| 1104 | * remains intact. |
| 1105 | * |
| 1106 | * This only applies to the passed ncp, if CINV_CHILDREN |
| 1107 | * is specified the children are not flagged. |
| 1108 | * |
| 1109 | * CINV_CHILDREN - Set all children (recursively) to an unresolved |
| 1110 | * state as well. |
| 1111 | * |
| 1112 | * Note that this will also have the side effect of |
| 1113 | * cleaning out any unreferenced nodes in the topology |
| 1114 | * from the leaves up as the recursion backs out. |
| 1115 | * |
| 1116 | * Note that the topology for any referenced nodes remains intact, but |
| 1117 | * the nodes will be marked as having been destroyed and will be set |
| 1118 | * to an unresolved state. |
| 1119 | * |
| 1120 | * It is possible for cache_inval() to race a cache_resolve(), meaning that |
| 1121 | * the namecache entry may not actually be invalidated on return if it was |
| 1122 | * revalidated while recursing down into its children. This code guarentees |
| 1123 | * that the node(s) will go through an invalidation cycle, but does not |
| 1124 | * guarentee that they will remain in an invalidated state. |
| 1125 | * |
| 1126 | * Returns non-zero if a revalidation was detected during the invalidation |
| 1127 | * recursion, zero otherwise. Note that since only the original ncp is |
| 1128 | * locked the revalidation ultimately can only indicate that the original ncp |
| 1129 | * *MIGHT* no have been reresolved. |
| 1130 | * |
| 1131 | * DEEP RECURSION HANDLING - If a recursive invalidation recurses deeply we |
| 1132 | * have to avoid blowing out the kernel stack. We do this by saving the |
| 1133 | * deep namecache node and aborting the recursion, then re-recursing at that |
| 1134 | * node using a depth-first algorithm in order to allow multiple deep |
| 1135 | * recursions to chain through each other, then we restart the invalidation |
| 1136 | * from scratch. |
| 1137 | * |
| 1138 | * MPSAFE |
| 1139 | */ |
| 1140 | |
| 1141 | struct cinvtrack { |
| 1142 | struct namecache *resume_ncp; |
| 1143 | int depth; |
| 1144 | }; |
| 1145 | |
| 1146 | static int _cache_inval_internal(struct namecache *, int, struct cinvtrack *); |
| 1147 | |
| 1148 | static |
| 1149 | int |
| 1150 | _cache_inval(struct namecache *ncp, int flags) |
| 1151 | { |
| 1152 | struct cinvtrack track; |
| 1153 | struct namecache *ncp2; |
| 1154 | int r; |
| 1155 | |
| 1156 | track.depth = 0; |
| 1157 | track.resume_ncp = NULL; |
| 1158 | |
| 1159 | for (;;) { |
| 1160 | r = _cache_inval_internal(ncp, flags, &track); |
| 1161 | if (track.resume_ncp == NULL) |
| 1162 | break; |
| 1163 | kprintf("Warning: deep namecache recursion at %s\n", |
| 1164 | ncp->nc_name); |
| 1165 | _cache_unlock(ncp); |
| 1166 | while ((ncp2 = track.resume_ncp) != NULL) { |
| 1167 | track.resume_ncp = NULL; |
| 1168 | _cache_lock(ncp2); |
| 1169 | _cache_inval_internal(ncp2, flags & ~CINV_DESTROY, |
| 1170 | &track); |
| 1171 | _cache_put(ncp2); |
| 1172 | } |
| 1173 | _cache_lock(ncp); |
| 1174 | } |
| 1175 | return(r); |
| 1176 | } |
| 1177 | |
| 1178 | int |
| 1179 | cache_inval(struct nchandle *nch, int flags) |
| 1180 | { |
| 1181 | return(_cache_inval(nch->ncp, flags)); |
| 1182 | } |
| 1183 | |
| 1184 | /* |
| 1185 | * Helper for _cache_inval(). The passed ncp is refd and locked and |
| 1186 | * remains that way on return, but may be unlocked/relocked multiple |
| 1187 | * times by the routine. |
| 1188 | */ |
| 1189 | static int |
| 1190 | _cache_inval_internal(struct namecache *ncp, int flags, struct cinvtrack *track) |
| 1191 | { |
| 1192 | struct namecache *kid; |
| 1193 | struct namecache *nextkid; |
| 1194 | int rcnt = 0; |
| 1195 | |
| 1196 | KKASSERT(ncp->nc_exlocks); |
| 1197 | |
| 1198 | _cache_setunresolved(ncp); |
| 1199 | if (flags & CINV_DESTROY) |
| 1200 | ncp->nc_flag |= NCF_DESTROYED; |
| 1201 | if ((flags & CINV_CHILDREN) && |
| 1202 | (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL |
| 1203 | ) { |
| 1204 | _cache_hold(kid); |
| 1205 | if (++track->depth > MAX_RECURSION_DEPTH) { |
| 1206 | track->resume_ncp = ncp; |
| 1207 | _cache_hold(ncp); |
| 1208 | ++rcnt; |
| 1209 | } |
| 1210 | _cache_unlock(ncp); |
| 1211 | while (kid) { |
| 1212 | if (track->resume_ncp) { |
| 1213 | _cache_drop(kid); |
| 1214 | break; |
| 1215 | } |
| 1216 | if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) |
| 1217 | _cache_hold(nextkid); |
| 1218 | if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || |
| 1219 | TAILQ_FIRST(&kid->nc_list) |
| 1220 | ) { |
| 1221 | _cache_lock(kid); |
| 1222 | rcnt += _cache_inval_internal(kid, flags & ~CINV_DESTROY, track); |
| 1223 | _cache_unlock(kid); |
| 1224 | } |
| 1225 | _cache_drop(kid); |
| 1226 | kid = nextkid; |
| 1227 | } |
| 1228 | --track->depth; |
| 1229 | _cache_lock(ncp); |
| 1230 | } |
| 1231 | |
| 1232 | /* |
| 1233 | * Someone could have gotten in there while ncp was unlocked, |
| 1234 | * retry if so. |
| 1235 | */ |
| 1236 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) |
| 1237 | ++rcnt; |
| 1238 | return (rcnt); |
| 1239 | } |
| 1240 | |
| 1241 | /* |
| 1242 | * Invalidate a vnode's namecache associations. To avoid races against |
| 1243 | * the resolver we do not invalidate a node which we previously invalidated |
| 1244 | * but which was then re-resolved while we were in the invalidation loop. |
| 1245 | * |
| 1246 | * Returns non-zero if any namecache entries remain after the invalidation |
| 1247 | * loop completed. |
| 1248 | * |
| 1249 | * NOTE: Unlike the namecache topology which guarentees that ncp's will not |
| 1250 | * be ripped out of the topology while held, the vnode's v_namecache |
| 1251 | * list has no such restriction. NCP's can be ripped out of the list |
| 1252 | * at virtually any time if not locked, even if held. |
| 1253 | * |
| 1254 | * In addition, the v_namecache list itself must be locked via |
| 1255 | * the vnode's spinlock. |
| 1256 | * |
| 1257 | * MPSAFE |
| 1258 | */ |
| 1259 | int |
| 1260 | cache_inval_vp(struct vnode *vp, int flags) |
| 1261 | { |
| 1262 | struct namecache *ncp; |
| 1263 | struct namecache *next; |
| 1264 | |
| 1265 | restart: |
| 1266 | spin_lock(&vp->v_spin); |
| 1267 | ncp = TAILQ_FIRST(&vp->v_namecache); |
| 1268 | if (ncp) |
| 1269 | _cache_hold(ncp); |
| 1270 | while (ncp) { |
| 1271 | /* loop entered with ncp held and vp spin-locked */ |
| 1272 | if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) |
| 1273 | _cache_hold(next); |
| 1274 | spin_unlock(&vp->v_spin); |
| 1275 | _cache_lock(ncp); |
| 1276 | if (ncp->nc_vp != vp) { |
| 1277 | kprintf("Warning: cache_inval_vp: race-A detected on " |
| 1278 | "%s\n", ncp->nc_name); |
| 1279 | _cache_put(ncp); |
| 1280 | if (next) |
| 1281 | _cache_drop(next); |
| 1282 | goto restart; |
| 1283 | } |
| 1284 | _cache_inval(ncp, flags); |
| 1285 | _cache_put(ncp); /* also releases reference */ |
| 1286 | ncp = next; |
| 1287 | spin_lock(&vp->v_spin); |
| 1288 | if (ncp && ncp->nc_vp != vp) { |
| 1289 | spin_unlock(&vp->v_spin); |
| 1290 | kprintf("Warning: cache_inval_vp: race-B detected on " |
| 1291 | "%s\n", ncp->nc_name); |
| 1292 | _cache_drop(ncp); |
| 1293 | goto restart; |
| 1294 | } |
| 1295 | } |
| 1296 | spin_unlock(&vp->v_spin); |
| 1297 | return(TAILQ_FIRST(&vp->v_namecache) != NULL); |
| 1298 | } |
| 1299 | |
| 1300 | /* |
| 1301 | * This routine is used instead of the normal cache_inval_vp() when we |
| 1302 | * are trying to recycle otherwise good vnodes. |
| 1303 | * |
| 1304 | * Return 0 on success, non-zero if not all namecache records could be |
| 1305 | * disassociated from the vnode (for various reasons). |
| 1306 | * |
| 1307 | * MPSAFE |
| 1308 | */ |
| 1309 | int |
| 1310 | cache_inval_vp_nonblock(struct vnode *vp) |
| 1311 | { |
| 1312 | struct namecache *ncp; |
| 1313 | struct namecache *next; |
| 1314 | |
| 1315 | spin_lock(&vp->v_spin); |
| 1316 | ncp = TAILQ_FIRST(&vp->v_namecache); |
| 1317 | if (ncp) |
| 1318 | _cache_hold(ncp); |
| 1319 | while (ncp) { |
| 1320 | /* loop entered with ncp held */ |
| 1321 | if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) |
| 1322 | _cache_hold(next); |
| 1323 | spin_unlock(&vp->v_spin); |
| 1324 | if (_cache_lock_nonblock(ncp)) { |
| 1325 | _cache_drop(ncp); |
| 1326 | if (next) |
| 1327 | _cache_drop(next); |
| 1328 | goto done; |
| 1329 | } |
| 1330 | if (ncp->nc_vp != vp) { |
| 1331 | kprintf("Warning: cache_inval_vp: race-A detected on " |
| 1332 | "%s\n", ncp->nc_name); |
| 1333 | _cache_put(ncp); |
| 1334 | if (next) |
| 1335 | _cache_drop(next); |
| 1336 | goto done; |
| 1337 | } |
| 1338 | _cache_inval(ncp, 0); |
| 1339 | _cache_put(ncp); /* also releases reference */ |
| 1340 | ncp = next; |
| 1341 | spin_lock(&vp->v_spin); |
| 1342 | if (ncp && ncp->nc_vp != vp) { |
| 1343 | spin_unlock(&vp->v_spin); |
| 1344 | kprintf("Warning: cache_inval_vp: race-B detected on " |
| 1345 | "%s\n", ncp->nc_name); |
| 1346 | _cache_drop(ncp); |
| 1347 | goto done; |
| 1348 | } |
| 1349 | } |
| 1350 | spin_unlock(&vp->v_spin); |
| 1351 | done: |
| 1352 | return(TAILQ_FIRST(&vp->v_namecache) != NULL); |
| 1353 | } |
| 1354 | |
| 1355 | /* |
| 1356 | * The source ncp has been renamed to the target ncp. Both fncp and tncp |
| 1357 | * must be locked. The target ncp is destroyed (as a normal rename-over |
| 1358 | * would destroy the target file or directory). |
| 1359 | * |
| 1360 | * Because there may be references to the source ncp we cannot copy its |
| 1361 | * contents to the target. Instead the source ncp is relinked as the target |
| 1362 | * and the target ncp is removed from the namecache topology. |
| 1363 | * |
| 1364 | * MPSAFE |
| 1365 | */ |
| 1366 | void |
| 1367 | cache_rename(struct nchandle *fnch, struct nchandle *tnch) |
| 1368 | { |
| 1369 | struct namecache *fncp = fnch->ncp; |
| 1370 | struct namecache *tncp = tnch->ncp; |
| 1371 | struct namecache *tncp_par; |
| 1372 | struct nchash_head *nchpp; |
| 1373 | u_int32_t hash; |
| 1374 | char *oname; |
| 1375 | |
| 1376 | /* |
| 1377 | * Rename fncp (unlink) |
| 1378 | */ |
| 1379 | _cache_unlink_parent(fncp); |
| 1380 | oname = fncp->nc_name; |
| 1381 | fncp->nc_name = tncp->nc_name; |
| 1382 | fncp->nc_nlen = tncp->nc_nlen; |
| 1383 | tncp_par = tncp->nc_parent; |
| 1384 | _cache_hold(tncp_par); |
| 1385 | _cache_lock(tncp_par); |
| 1386 | |
| 1387 | /* |
| 1388 | * Rename fncp (relink) |
| 1389 | */ |
| 1390 | hash = fnv_32_buf(fncp->nc_name, fncp->nc_nlen, FNV1_32_INIT); |
| 1391 | hash = fnv_32_buf(&tncp_par, sizeof(tncp_par), hash); |
| 1392 | nchpp = NCHHASH(hash); |
| 1393 | |
| 1394 | spin_lock(&nchpp->spin); |
| 1395 | _cache_link_parent(fncp, tncp_par, nchpp); |
| 1396 | spin_unlock(&nchpp->spin); |
| 1397 | |
| 1398 | _cache_put(tncp_par); |
| 1399 | |
| 1400 | /* |
| 1401 | * Get rid of the overwritten tncp (unlink) |
| 1402 | */ |
| 1403 | _cache_setunresolved(tncp); |
| 1404 | _cache_unlink_parent(tncp); |
| 1405 | tncp->nc_name = NULL; |
| 1406 | tncp->nc_nlen = 0; |
| 1407 | |
| 1408 | if (oname) |
| 1409 | kfree(oname, M_VFSCACHE); |
| 1410 | } |
| 1411 | |
| 1412 | /* |
| 1413 | * vget the vnode associated with the namecache entry. Resolve the namecache |
| 1414 | * entry if necessary. The passed ncp must be referenced and locked. |
| 1415 | * |
| 1416 | * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked |
| 1417 | * (depending on the passed lk_type) will be returned in *vpp with an error |
| 1418 | * of 0, or NULL will be returned in *vpp with a non-0 error code. The |
| 1419 | * most typical error is ENOENT, meaning that the ncp represents a negative |
| 1420 | * cache hit and there is no vnode to retrieve, but other errors can occur |
| 1421 | * too. |
| 1422 | * |
| 1423 | * The vget() can race a reclaim. If this occurs we re-resolve the |
| 1424 | * namecache entry. |
| 1425 | * |
| 1426 | * There are numerous places in the kernel where vget() is called on a |
| 1427 | * vnode while one or more of its namecache entries is locked. Releasing |
| 1428 | * a vnode never deadlocks against locked namecache entries (the vnode |
| 1429 | * will not get recycled while referenced ncp's exist). This means we |
| 1430 | * can safely acquire the vnode. In fact, we MUST NOT release the ncp |
| 1431 | * lock when acquiring the vp lock or we might cause a deadlock. |
| 1432 | * |
| 1433 | * MPSAFE |
| 1434 | */ |
| 1435 | int |
| 1436 | cache_vget(struct nchandle *nch, struct ucred *cred, |
| 1437 | int lk_type, struct vnode **vpp) |
| 1438 | { |
| 1439 | struct namecache *ncp; |
| 1440 | struct vnode *vp; |
| 1441 | int error; |
| 1442 | |
| 1443 | ncp = nch->ncp; |
| 1444 | KKASSERT(ncp->nc_locktd == curthread); |
| 1445 | again: |
| 1446 | vp = NULL; |
| 1447 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 1448 | error = cache_resolve(nch, cred); |
| 1449 | else |
| 1450 | error = 0; |
| 1451 | |
| 1452 | if (error == 0 && (vp = ncp->nc_vp) != NULL) { |
| 1453 | error = vget(vp, lk_type); |
| 1454 | if (error) { |
| 1455 | /* |
| 1456 | * VRECLAIM race |
| 1457 | */ |
| 1458 | if (error == ENOENT) { |
| 1459 | kprintf("Warning: vnode reclaim race detected " |
| 1460 | "in cache_vget on %p (%s)\n", |
| 1461 | vp, ncp->nc_name); |
| 1462 | _cache_setunresolved(ncp); |
| 1463 | goto again; |
| 1464 | } |
| 1465 | |
| 1466 | /* |
| 1467 | * Not a reclaim race, some other error. |
| 1468 | */ |
| 1469 | KKASSERT(ncp->nc_vp == vp); |
| 1470 | vp = NULL; |
| 1471 | } else { |
| 1472 | KKASSERT(ncp->nc_vp == vp); |
| 1473 | KKASSERT((vp->v_flag & VRECLAIMED) == 0); |
| 1474 | } |
| 1475 | } |
| 1476 | if (error == 0 && vp == NULL) |
| 1477 | error = ENOENT; |
| 1478 | *vpp = vp; |
| 1479 | return(error); |
| 1480 | } |
| 1481 | |
| 1482 | int |
| 1483 | cache_vref(struct nchandle *nch, struct ucred *cred, struct vnode **vpp) |
| 1484 | { |
| 1485 | struct namecache *ncp; |
| 1486 | struct vnode *vp; |
| 1487 | int error; |
| 1488 | |
| 1489 | ncp = nch->ncp; |
| 1490 | KKASSERT(ncp->nc_locktd == curthread); |
| 1491 | again: |
| 1492 | vp = NULL; |
| 1493 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 1494 | error = cache_resolve(nch, cred); |
| 1495 | else |
| 1496 | error = 0; |
| 1497 | |
| 1498 | if (error == 0 && (vp = ncp->nc_vp) != NULL) { |
| 1499 | error = vget(vp, LK_SHARED); |
| 1500 | if (error) { |
| 1501 | /* |
| 1502 | * VRECLAIM race |
| 1503 | */ |
| 1504 | if (error == ENOENT) { |
| 1505 | kprintf("Warning: vnode reclaim race detected " |
| 1506 | "in cache_vget on %p (%s)\n", |
| 1507 | vp, ncp->nc_name); |
| 1508 | _cache_setunresolved(ncp); |
| 1509 | goto again; |
| 1510 | } |
| 1511 | |
| 1512 | /* |
| 1513 | * Not a reclaim race, some other error. |
| 1514 | */ |
| 1515 | KKASSERT(ncp->nc_vp == vp); |
| 1516 | vp = NULL; |
| 1517 | } else { |
| 1518 | KKASSERT(ncp->nc_vp == vp); |
| 1519 | KKASSERT((vp->v_flag & VRECLAIMED) == 0); |
| 1520 | /* caller does not want a lock */ |
| 1521 | vn_unlock(vp); |
| 1522 | } |
| 1523 | } |
| 1524 | if (error == 0 && vp == NULL) |
| 1525 | error = ENOENT; |
| 1526 | *vpp = vp; |
| 1527 | return(error); |
| 1528 | } |
| 1529 | |
| 1530 | /* |
| 1531 | * Return a referenced vnode representing the parent directory of |
| 1532 | * ncp. |
| 1533 | * |
| 1534 | * Because the caller has locked the ncp it should not be possible for |
| 1535 | * the parent ncp to go away. However, the parent can unresolve its |
| 1536 | * dvp at any time so we must be able to acquire a lock on the parent |
| 1537 | * to safely access nc_vp. |
| 1538 | * |
| 1539 | * We have to leave par unlocked when vget()ing dvp to avoid a deadlock, |
| 1540 | * so use vhold()/vdrop() while holding the lock to prevent dvp from |
| 1541 | * getting destroyed. |
| 1542 | * |
| 1543 | * MPSAFE - Note vhold() is allowed when dvp has 0 refs if we hold a |
| 1544 | * lock on the ncp in question.. |
| 1545 | */ |
| 1546 | static struct vnode * |
| 1547 | cache_dvpref(struct namecache *ncp) |
| 1548 | { |
| 1549 | struct namecache *par; |
| 1550 | struct vnode *dvp; |
| 1551 | |
| 1552 | dvp = NULL; |
| 1553 | if ((par = ncp->nc_parent) != NULL) { |
| 1554 | _cache_hold(par); |
| 1555 | _cache_lock(par); |
| 1556 | if ((par->nc_flag & NCF_UNRESOLVED) == 0) { |
| 1557 | if ((dvp = par->nc_vp) != NULL) |
| 1558 | vhold(dvp); |
| 1559 | } |
| 1560 | _cache_unlock(par); |
| 1561 | if (dvp) { |
| 1562 | if (vget(dvp, LK_SHARED) == 0) { |
| 1563 | vn_unlock(dvp); |
| 1564 | vdrop(dvp); |
| 1565 | /* return refd, unlocked dvp */ |
| 1566 | } else { |
| 1567 | vdrop(dvp); |
| 1568 | dvp = NULL; |
| 1569 | } |
| 1570 | } |
| 1571 | _cache_drop(par); |
| 1572 | } |
| 1573 | return(dvp); |
| 1574 | } |
| 1575 | |
| 1576 | /* |
| 1577 | * Convert a directory vnode to a namecache record without any other |
| 1578 | * knowledge of the topology. This ONLY works with directory vnodes and |
| 1579 | * is ONLY used by the NFS server. dvp must be refd but unlocked, and the |
| 1580 | * returned ncp (if not NULL) will be held and unlocked. |
| 1581 | * |
| 1582 | * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. |
| 1583 | * If 'makeit' is 1 we attempt to track-down and create the namecache topology |
| 1584 | * for dvp. This will fail only if the directory has been deleted out from |
| 1585 | * under the caller. |
| 1586 | * |
| 1587 | * Callers must always check for a NULL return no matter the value of 'makeit'. |
| 1588 | * |
| 1589 | * To avoid underflowing the kernel stack each recursive call increments |
| 1590 | * the makeit variable. |
| 1591 | */ |
| 1592 | |
| 1593 | static int cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, |
| 1594 | struct vnode *dvp, char *fakename); |
| 1595 | static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, |
| 1596 | struct vnode **saved_dvp); |
| 1597 | |
| 1598 | int |
| 1599 | cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit, |
| 1600 | struct nchandle *nch) |
| 1601 | { |
| 1602 | struct vnode *saved_dvp; |
| 1603 | struct vnode *pvp; |
| 1604 | char *fakename; |
| 1605 | int error; |
| 1606 | |
| 1607 | nch->ncp = NULL; |
| 1608 | nch->mount = dvp->v_mount; |
| 1609 | saved_dvp = NULL; |
| 1610 | fakename = NULL; |
| 1611 | |
| 1612 | /* |
| 1613 | * Handle the makeit == 0 degenerate case |
| 1614 | */ |
| 1615 | if (makeit == 0) { |
| 1616 | spin_lock(&dvp->v_spin); |
| 1617 | nch->ncp = TAILQ_FIRST(&dvp->v_namecache); |
| 1618 | if (nch->ncp) |
| 1619 | cache_hold(nch); |
| 1620 | spin_unlock(&dvp->v_spin); |
| 1621 | } |
| 1622 | |
| 1623 | /* |
| 1624 | * Loop until resolution, inside code will break out on error. |
| 1625 | */ |
| 1626 | while (makeit) { |
| 1627 | /* |
| 1628 | * Break out if we successfully acquire a working ncp. |
| 1629 | */ |
| 1630 | spin_lock(&dvp->v_spin); |
| 1631 | nch->ncp = TAILQ_FIRST(&dvp->v_namecache); |
| 1632 | if (nch->ncp) { |
| 1633 | cache_hold(nch); |
| 1634 | spin_unlock(&dvp->v_spin); |
| 1635 | break; |
| 1636 | } |
| 1637 | spin_unlock(&dvp->v_spin); |
| 1638 | |
| 1639 | /* |
| 1640 | * If dvp is the root of its filesystem it should already |
| 1641 | * have a namecache pointer associated with it as a side |
| 1642 | * effect of the mount, but it may have been disassociated. |
| 1643 | */ |
| 1644 | if (dvp->v_flag & VROOT) { |
| 1645 | nch->ncp = _cache_get(nch->mount->mnt_ncmountpt.ncp); |
| 1646 | error = cache_resolve_mp(nch->mount); |
| 1647 | _cache_put(nch->ncp); |
| 1648 | if (ncvp_debug) { |
| 1649 | kprintf("cache_fromdvp: resolve root of mount %p error %d", |
| 1650 | dvp->v_mount, error); |
| 1651 | } |
| 1652 | if (error) { |
| 1653 | if (ncvp_debug) |
| 1654 | kprintf(" failed\n"); |
| 1655 | nch->ncp = NULL; |
| 1656 | break; |
| 1657 | } |
| 1658 | if (ncvp_debug) |
| 1659 | kprintf(" succeeded\n"); |
| 1660 | continue; |
| 1661 | } |
| 1662 | |
| 1663 | /* |
| 1664 | * If we are recursed too deeply resort to an O(n^2) |
| 1665 | * algorithm to resolve the namecache topology. The |
| 1666 | * resolved pvp is left referenced in saved_dvp to |
| 1667 | * prevent the tree from being destroyed while we loop. |
| 1668 | */ |
| 1669 | if (makeit > 20) { |
| 1670 | error = cache_fromdvp_try(dvp, cred, &saved_dvp); |
| 1671 | if (error) { |
| 1672 | kprintf("lookupdotdot(longpath) failed %d " |
| 1673 | "dvp %p\n", error, dvp); |
| 1674 | nch->ncp = NULL; |
| 1675 | break; |
| 1676 | } |
| 1677 | continue; |
| 1678 | } |
| 1679 | |
| 1680 | /* |
| 1681 | * Get the parent directory and resolve its ncp. |
| 1682 | */ |
| 1683 | if (fakename) { |
| 1684 | kfree(fakename, M_TEMP); |
| 1685 | fakename = NULL; |
| 1686 | } |
| 1687 | error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred, |
| 1688 | &fakename); |
| 1689 | if (error) { |
| 1690 | kprintf("lookupdotdot failed %d dvp %p\n", error, dvp); |
| 1691 | break; |
| 1692 | } |
| 1693 | vn_unlock(pvp); |
| 1694 | |
| 1695 | /* |
| 1696 | * Reuse makeit as a recursion depth counter. On success |
| 1697 | * nch will be fully referenced. |
| 1698 | */ |
| 1699 | cache_fromdvp(pvp, cred, makeit + 1, nch); |
| 1700 | vrele(pvp); |
| 1701 | if (nch->ncp == NULL) |
| 1702 | break; |
| 1703 | |
| 1704 | /* |
| 1705 | * Do an inefficient scan of pvp (embodied by ncp) to look |
| 1706 | * for dvp. This will create a namecache record for dvp on |
| 1707 | * success. We loop up to recheck on success. |
| 1708 | * |
| 1709 | * ncp and dvp are both held but not locked. |
| 1710 | */ |
| 1711 | error = cache_inefficient_scan(nch, cred, dvp, fakename); |
| 1712 | if (error) { |
| 1713 | kprintf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", |
| 1714 | pvp, nch->ncp->nc_name, dvp); |
| 1715 | cache_drop(nch); |
| 1716 | /* nch was NULLed out, reload mount */ |
| 1717 | nch->mount = dvp->v_mount; |
| 1718 | break; |
| 1719 | } |
| 1720 | if (ncvp_debug) { |
| 1721 | kprintf("cache_fromdvp: scan %p (%s) succeeded\n", |
| 1722 | pvp, nch->ncp->nc_name); |
| 1723 | } |
| 1724 | cache_drop(nch); |
| 1725 | /* nch was NULLed out, reload mount */ |
| 1726 | nch->mount = dvp->v_mount; |
| 1727 | } |
| 1728 | |
| 1729 | /* |
| 1730 | * If nch->ncp is non-NULL it will have been held already. |
| 1731 | */ |
| 1732 | if (fakename) |
| 1733 | kfree(fakename, M_TEMP); |
| 1734 | if (saved_dvp) |
| 1735 | vrele(saved_dvp); |
| 1736 | if (nch->ncp) |
| 1737 | return (0); |
| 1738 | return (EINVAL); |
| 1739 | } |
| 1740 | |
| 1741 | /* |
| 1742 | * Go up the chain of parent directories until we find something |
| 1743 | * we can resolve into the namecache. This is very inefficient. |
| 1744 | */ |
| 1745 | static |
| 1746 | int |
| 1747 | cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, |
| 1748 | struct vnode **saved_dvp) |
| 1749 | { |
| 1750 | struct nchandle nch; |
| 1751 | struct vnode *pvp; |
| 1752 | int error; |
| 1753 | static time_t last_fromdvp_report; |
| 1754 | char *fakename; |
| 1755 | |
| 1756 | /* |
| 1757 | * Loop getting the parent directory vnode until we get something we |
| 1758 | * can resolve in the namecache. |
| 1759 | */ |
| 1760 | vref(dvp); |
| 1761 | nch.mount = dvp->v_mount; |
| 1762 | nch.ncp = NULL; |
| 1763 | fakename = NULL; |
| 1764 | |
| 1765 | for (;;) { |
| 1766 | if (fakename) { |
| 1767 | kfree(fakename, M_TEMP); |
| 1768 | fakename = NULL; |
| 1769 | } |
| 1770 | error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred, |
| 1771 | &fakename); |
| 1772 | if (error) { |
| 1773 | vrele(dvp); |
| 1774 | break; |
| 1775 | } |
| 1776 | vn_unlock(pvp); |
| 1777 | spin_lock(&pvp->v_spin); |
| 1778 | if ((nch.ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) { |
| 1779 | _cache_hold(nch.ncp); |
| 1780 | spin_unlock(&pvp->v_spin); |
| 1781 | vrele(pvp); |
| 1782 | break; |
| 1783 | } |
| 1784 | spin_unlock(&pvp->v_spin); |
| 1785 | if (pvp->v_flag & VROOT) { |
| 1786 | nch.ncp = _cache_get(pvp->v_mount->mnt_ncmountpt.ncp); |
| 1787 | error = cache_resolve_mp(nch.mount); |
| 1788 | _cache_unlock(nch.ncp); |
| 1789 | vrele(pvp); |
| 1790 | if (error) { |
| 1791 | _cache_drop(nch.ncp); |
| 1792 | nch.ncp = NULL; |
| 1793 | vrele(dvp); |
| 1794 | } |
| 1795 | break; |
| 1796 | } |
| 1797 | vrele(dvp); |
| 1798 | dvp = pvp; |
| 1799 | } |
| 1800 | if (error == 0) { |
| 1801 | if (last_fromdvp_report != time_second) { |
| 1802 | last_fromdvp_report = time_second; |
| 1803 | kprintf("Warning: extremely inefficient path " |
| 1804 | "resolution on %s\n", |
| 1805 | nch.ncp->nc_name); |
| 1806 | } |
| 1807 | error = cache_inefficient_scan(&nch, cred, dvp, fakename); |
| 1808 | |
| 1809 | /* |
| 1810 | * Hopefully dvp now has a namecache record associated with |
| 1811 | * it. Leave it referenced to prevent the kernel from |
| 1812 | * recycling the vnode. Otherwise extremely long directory |
| 1813 | * paths could result in endless recycling. |
| 1814 | */ |
| 1815 | if (*saved_dvp) |
| 1816 | vrele(*saved_dvp); |
| 1817 | *saved_dvp = dvp; |
| 1818 | _cache_drop(nch.ncp); |
| 1819 | } |
| 1820 | if (fakename) |
| 1821 | kfree(fakename, M_TEMP); |
| 1822 | return (error); |
| 1823 | } |
| 1824 | |
| 1825 | /* |
| 1826 | * Do an inefficient scan of the directory represented by ncp looking for |
| 1827 | * the directory vnode dvp. ncp must be held but not locked on entry and |
| 1828 | * will be held on return. dvp must be refd but not locked on entry and |
| 1829 | * will remain refd on return. |
| 1830 | * |
| 1831 | * Why do this at all? Well, due to its stateless nature the NFS server |
| 1832 | * converts file handles directly to vnodes without necessarily going through |
| 1833 | * the namecache ops that would otherwise create the namecache topology |
| 1834 | * leading to the vnode. We could either (1) Change the namecache algorithms |
| 1835 | * to allow disconnect namecache records that are re-merged opportunistically, |
| 1836 | * or (2) Make the NFS server backtrack and scan to recover a connected |
| 1837 | * namecache topology in order to then be able to issue new API lookups. |
| 1838 | * |
| 1839 | * It turns out that (1) is a huge mess. It takes a nice clean set of |
| 1840 | * namecache algorithms and introduces a lot of complication in every subsystem |
| 1841 | * that calls into the namecache to deal with the re-merge case, especially |
| 1842 | * since we are using the namecache to placehold negative lookups and the |
| 1843 | * vnode might not be immediately assigned. (2) is certainly far less |
| 1844 | * efficient then (1), but since we are only talking about directories here |
| 1845 | * (which are likely to remain cached), the case does not actually run all |
| 1846 | * that often and has the supreme advantage of not polluting the namecache |
| 1847 | * algorithms. |
| 1848 | * |
| 1849 | * If a fakename is supplied just construct a namecache entry using the |
| 1850 | * fake name. |
| 1851 | */ |
| 1852 | static int |
| 1853 | cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, |
| 1854 | struct vnode *dvp, char *fakename) |
| 1855 | { |
| 1856 | struct nlcomponent nlc; |
| 1857 | struct nchandle rncp; |
| 1858 | struct dirent *den; |
| 1859 | struct vnode *pvp; |
| 1860 | struct vattr vat; |
| 1861 | struct iovec iov; |
| 1862 | struct uio uio; |
| 1863 | int blksize; |
| 1864 | int eofflag; |
| 1865 | int bytes; |
| 1866 | char *rbuf; |
| 1867 | int error; |
| 1868 | |
| 1869 | vat.va_blocksize = 0; |
| 1870 | if ((error = VOP_GETATTR(dvp, &vat)) != 0) |
| 1871 | return (error); |
| 1872 | cache_lock(nch); |
| 1873 | error = cache_vref(nch, cred, &pvp); |
| 1874 | cache_unlock(nch); |
| 1875 | if (error) |
| 1876 | return (error); |
| 1877 | if (ncvp_debug) { |
| 1878 | kprintf("inefficient_scan: directory iosize %ld " |
| 1879 | "vattr fileid = %lld\n", |
| 1880 | vat.va_blocksize, |
| 1881 | (long long)vat.va_fileid); |
| 1882 | } |
| 1883 | |
| 1884 | /* |
| 1885 | * Use the supplied fakename if not NULL. Fake names are typically |
| 1886 | * not in the actual filesystem hierarchy. This is used by HAMMER |
| 1887 | * to glue @@timestamp recursions together. |
| 1888 | */ |
| 1889 | if (fakename) { |
| 1890 | nlc.nlc_nameptr = fakename; |
| 1891 | nlc.nlc_namelen = strlen(fakename); |
| 1892 | rncp = cache_nlookup(nch, &nlc); |
| 1893 | goto done; |
| 1894 | } |
| 1895 | |
| 1896 | if ((blksize = vat.va_blocksize) == 0) |
| 1897 | blksize = DEV_BSIZE; |
| 1898 | rbuf = kmalloc(blksize, M_TEMP, M_WAITOK); |
| 1899 | rncp.ncp = NULL; |
| 1900 | |
| 1901 | eofflag = 0; |
| 1902 | uio.uio_offset = 0; |
| 1903 | again: |
| 1904 | iov.iov_base = rbuf; |
| 1905 | iov.iov_len = blksize; |
| 1906 | uio.uio_iov = &iov; |
| 1907 | uio.uio_iovcnt = 1; |
| 1908 | uio.uio_resid = blksize; |
| 1909 | uio.uio_segflg = UIO_SYSSPACE; |
| 1910 | uio.uio_rw = UIO_READ; |
| 1911 | uio.uio_td = curthread; |
| 1912 | |
| 1913 | if (ncvp_debug >= 2) |
| 1914 | kprintf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); |
| 1915 | error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); |
| 1916 | if (error == 0) { |
| 1917 | den = (struct dirent *)rbuf; |
| 1918 | bytes = blksize - uio.uio_resid; |
| 1919 | |
| 1920 | while (bytes > 0) { |
| 1921 | if (ncvp_debug >= 2) { |
| 1922 | kprintf("cache_inefficient_scan: %*.*s\n", |
| 1923 | den->d_namlen, den->d_namlen, |
| 1924 | den->d_name); |
| 1925 | } |
| 1926 | if (den->d_type != DT_WHT && |
| 1927 | den->d_ino == vat.va_fileid) { |
| 1928 | if (ncvp_debug) { |
| 1929 | kprintf("cache_inefficient_scan: " |
| 1930 | "MATCHED inode %lld path %s/%*.*s\n", |
| 1931 | (long long)vat.va_fileid, |
| 1932 | nch->ncp->nc_name, |
| 1933 | den->d_namlen, den->d_namlen, |
| 1934 | den->d_name); |
| 1935 | } |
| 1936 | nlc.nlc_nameptr = den->d_name; |
| 1937 | nlc.nlc_namelen = den->d_namlen; |
| 1938 | rncp = cache_nlookup(nch, &nlc); |
| 1939 | KKASSERT(rncp.ncp != NULL); |
| 1940 | break; |
| 1941 | } |
| 1942 | bytes -= _DIRENT_DIRSIZ(den); |
| 1943 | den = _DIRENT_NEXT(den); |
| 1944 | } |
| 1945 | if (rncp.ncp == NULL && eofflag == 0 && uio.uio_resid != blksize) |
| 1946 | goto again; |
| 1947 | } |
| 1948 | kfree(rbuf, M_TEMP); |
| 1949 | done: |
| 1950 | vrele(pvp); |
| 1951 | if (rncp.ncp) { |
| 1952 | if (rncp.ncp->nc_flag & NCF_UNRESOLVED) { |
| 1953 | _cache_setvp(rncp.mount, rncp.ncp, dvp); |
| 1954 | if (ncvp_debug >= 2) { |
| 1955 | kprintf("cache_inefficient_scan: setvp %s/%s = %p\n", |
| 1956 | nch->ncp->nc_name, rncp.ncp->nc_name, dvp); |
| 1957 | } |
| 1958 | } else { |
| 1959 | if (ncvp_debug >= 2) { |
| 1960 | kprintf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", |
| 1961 | nch->ncp->nc_name, rncp.ncp->nc_name, dvp, |
| 1962 | rncp.ncp->nc_vp); |
| 1963 | } |
| 1964 | } |
| 1965 | if (rncp.ncp->nc_vp == NULL) |
| 1966 | error = rncp.ncp->nc_error; |
| 1967 | /* |
| 1968 | * Release rncp after a successful nlookup. rncp was fully |
| 1969 | * referenced. |
| 1970 | */ |
| 1971 | cache_put(&rncp); |
| 1972 | } else { |
| 1973 | kprintf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", |
| 1974 | dvp, nch->ncp->nc_name); |
| 1975 | error = ENOENT; |
| 1976 | } |
| 1977 | return (error); |
| 1978 | } |
| 1979 | |
| 1980 | /* |
| 1981 | * Zap a namecache entry. The ncp is unconditionally set to an unresolved |
| 1982 | * state, which disassociates it from its vnode or ncneglist. |
| 1983 | * |
| 1984 | * Then, if there are no additional references to the ncp and no children, |
| 1985 | * the ncp is removed from the topology and destroyed. |
| 1986 | * |
| 1987 | * References and/or children may exist if the ncp is in the middle of the |
| 1988 | * topology, preventing the ncp from being destroyed. |
| 1989 | * |
| 1990 | * This function must be called with the ncp held and locked and will unlock |
| 1991 | * and drop it during zapping. |
| 1992 | * |
| 1993 | * If nonblock is non-zero and the parent ncp cannot be locked we give up. |
| 1994 | * This case can occur in the cache_drop() path. |
| 1995 | * |
| 1996 | * This function may returned a held (but NOT locked) parent node which the |
| 1997 | * caller must drop. We do this so _cache_drop() can loop, to avoid |
| 1998 | * blowing out the kernel stack. |
| 1999 | * |
| 2000 | * WARNING! For MPSAFE operation this routine must acquire up to three |
| 2001 | * spin locks to be able to safely test nc_refs. Lock order is |
| 2002 | * very important. |
| 2003 | * |
| 2004 | * hash spinlock if on hash list |
| 2005 | * parent spinlock if child of parent |
| 2006 | * (the ncp is unresolved so there is no vnode association) |
| 2007 | */ |
| 2008 | static struct namecache * |
| 2009 | cache_zap(struct namecache *ncp, int nonblock) |
| 2010 | { |
| 2011 | struct namecache *par; |
| 2012 | struct vnode *dropvp; |
| 2013 | int refs; |
| 2014 | |
| 2015 | /* |
| 2016 | * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. |
| 2017 | */ |
| 2018 | _cache_setunresolved(ncp); |
| 2019 | |
| 2020 | /* |
| 2021 | * Try to scrap the entry and possibly tail-recurse on its parent. |
| 2022 | * We only scrap unref'd (other then our ref) unresolved entries, |
| 2023 | * we do not scrap 'live' entries. |
| 2024 | * |
| 2025 | * Note that once the spinlocks are acquired if nc_refs == 1 no |
| 2026 | * other references are possible. If it isn't, however, we have |
| 2027 | * to decrement but also be sure to avoid a 1->0 transition. |
| 2028 | */ |
| 2029 | KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); |
| 2030 | KKASSERT(ncp->nc_refs > 0); |
| 2031 | |
| 2032 | /* |
| 2033 | * Acquire locks. Note that the parent can't go away while we hold |
| 2034 | * a child locked. |
| 2035 | */ |
| 2036 | if ((par = ncp->nc_parent) != NULL) { |
| 2037 | if (nonblock) { |
| 2038 | for (;;) { |
| 2039 | if (_cache_lock_nonblock(par) == 0) |
| 2040 | break; |
| 2041 | refs = ncp->nc_refs; |
| 2042 | ncp->nc_flag |= NCF_DEFEREDZAP; |
| 2043 | ++numdefered; /* MP race ok */ |
| 2044 | if (atomic_cmpset_int(&ncp->nc_refs, |
| 2045 | refs, refs - 1)) { |
| 2046 | _cache_unlock(ncp); |
| 2047 | return(NULL); |
| 2048 | } |
| 2049 | cpu_pause(); |
| 2050 | } |
| 2051 | _cache_hold(par); |
| 2052 | } else { |
| 2053 | _cache_hold(par); |
| 2054 | _cache_lock(par); |
| 2055 | } |
| 2056 | spin_lock(&ncp->nc_head->spin); |
| 2057 | } |
| 2058 | |
| 2059 | /* |
| 2060 | * If someone other then us has a ref or we have children |
| 2061 | * we cannot zap the entry. The 1->0 transition and any |
| 2062 | * further list operation is protected by the spinlocks |
| 2063 | * we have acquired but other transitions are not. |
| 2064 | */ |
| 2065 | for (;;) { |
| 2066 | refs = ncp->nc_refs; |
| 2067 | if (refs == 1 && TAILQ_EMPTY(&ncp->nc_list)) |
| 2068 | break; |
| 2069 | if (atomic_cmpset_int(&ncp->nc_refs, refs, refs - 1)) { |
| 2070 | if (par) { |
| 2071 | spin_unlock(&ncp->nc_head->spin); |
| 2072 | _cache_put(par); |
| 2073 | } |
| 2074 | _cache_unlock(ncp); |
| 2075 | return(NULL); |
| 2076 | } |
| 2077 | cpu_pause(); |
| 2078 | } |
| 2079 | |
| 2080 | /* |
| 2081 | * We are the only ref and with the spinlocks held no further |
| 2082 | * refs can be acquired by others. |
| 2083 | * |
| 2084 | * Remove us from the hash list and parent list. We have to |
| 2085 | * drop a ref on the parent's vp if the parent's list becomes |
| 2086 | * empty. |
| 2087 | */ |
| 2088 | dropvp = NULL; |
| 2089 | if (par) { |
| 2090 | struct nchash_head *nchpp = ncp->nc_head; |
| 2091 | |
| 2092 | KKASSERT(nchpp != NULL); |
| 2093 | LIST_REMOVE(ncp, nc_hash); |
| 2094 | TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); |
| 2095 | if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) |
| 2096 | dropvp = par->nc_vp; |
| 2097 | ncp->nc_head = NULL; |
| 2098 | ncp->nc_parent = NULL; |
| 2099 | spin_unlock(&nchpp->spin); |
| 2100 | _cache_unlock(par); |
| 2101 | } else { |
| 2102 | KKASSERT(ncp->nc_head == NULL); |
| 2103 | } |
| 2104 | |
| 2105 | /* |
| 2106 | * ncp should not have picked up any refs. Physically |
| 2107 | * destroy the ncp. |
| 2108 | */ |
| 2109 | KKASSERT(ncp->nc_refs == 1); |
| 2110 | /* _cache_unlock(ncp) not required */ |
| 2111 | ncp->nc_refs = -1; /* safety */ |
| 2112 | if (ncp->nc_name) |
| 2113 | kfree(ncp->nc_name, M_VFSCACHE); |
| 2114 | kfree(ncp, M_VFSCACHE); |
| 2115 | |
| 2116 | /* |
| 2117 | * Delayed drop (we had to release our spinlocks) |
| 2118 | * |
| 2119 | * The refed parent (if not NULL) must be dropped. The |
| 2120 | * caller is responsible for looping. |
| 2121 | */ |
| 2122 | if (dropvp) |
| 2123 | vdrop(dropvp); |
| 2124 | return(par); |
| 2125 | } |
| 2126 | |
| 2127 | /* |
| 2128 | * Clean up dangling negative cache and defered-drop entries in the |
| 2129 | * namecache. |
| 2130 | */ |
| 2131 | typedef enum { CHI_LOW, CHI_HIGH } cache_hs_t; |
| 2132 | |
| 2133 | static cache_hs_t neg_cache_hysteresis_state = CHI_LOW; |
| 2134 | static cache_hs_t pos_cache_hysteresis_state = CHI_LOW; |
| 2135 | |
| 2136 | void |
| 2137 | cache_hysteresis(void) |
| 2138 | { |
| 2139 | int poslimit; |
| 2140 | |
| 2141 | /* |
| 2142 | * Don't cache too many negative hits. We use hysteresis to reduce |
| 2143 | * the impact on the critical path. |
| 2144 | */ |
| 2145 | switch(neg_cache_hysteresis_state) { |
| 2146 | case CHI_LOW: |
| 2147 | if (numneg > MINNEG && numneg * ncnegfactor > numcache) { |
| 2148 | _cache_cleanneg(10); |
| 2149 | neg_cache_hysteresis_state = CHI_HIGH; |
| 2150 | } |
| 2151 | break; |
| 2152 | case CHI_HIGH: |
| 2153 | if (numneg > MINNEG * 9 / 10 && |
| 2154 | numneg * ncnegfactor * 9 / 10 > numcache |
| 2155 | ) { |
| 2156 | _cache_cleanneg(10); |
| 2157 | } else { |
| 2158 | neg_cache_hysteresis_state = CHI_LOW; |
| 2159 | } |
| 2160 | break; |
| 2161 | } |
| 2162 | |
| 2163 | /* |
| 2164 | * Don't cache too many positive hits. We use hysteresis to reduce |
| 2165 | * the impact on the critical path. |
| 2166 | * |
| 2167 | * Excessive positive hits can accumulate due to large numbers of |
| 2168 | * hardlinks (the vnode cache will not prevent hl ncps from growing |
| 2169 | * into infinity). |
| 2170 | */ |
| 2171 | if ((poslimit = ncposlimit) == 0) |
| 2172 | poslimit = desiredvnodes * 2; |
| 2173 | |
| 2174 | switch(pos_cache_hysteresis_state) { |
| 2175 | case CHI_LOW: |
| 2176 | if (numcache > poslimit && numcache > MINPOS) { |
| 2177 | _cache_cleanpos(10); |
| 2178 | pos_cache_hysteresis_state = CHI_HIGH; |
| 2179 | } |
| 2180 | break; |
| 2181 | case CHI_HIGH: |
| 2182 | if (numcache > poslimit * 5 / 6 && numcache > MINPOS) { |
| 2183 | _cache_cleanpos(10); |
| 2184 | } else { |
| 2185 | pos_cache_hysteresis_state = CHI_LOW; |
| 2186 | } |
| 2187 | break; |
| 2188 | } |
| 2189 | |
| 2190 | /* |
| 2191 | * Clean out dangling defered-zap ncps which could not |
| 2192 | * be cleanly dropped if too many build up. Note |
| 2193 | * that numdefered is not an exact number as such ncps |
| 2194 | * can be reused and the counter is not handled in a MP |
| 2195 | * safe manner by design. |
| 2196 | */ |
| 2197 | if (numdefered * ncnegfactor > numcache) { |
| 2198 | _cache_cleandefered(); |
| 2199 | } |
| 2200 | } |
| 2201 | |
| 2202 | /* |
| 2203 | * NEW NAMECACHE LOOKUP API |
| 2204 | * |
| 2205 | * Lookup an entry in the namecache. The passed par_nch must be referenced |
| 2206 | * and unlocked. A referenced and locked nchandle with a non-NULL nch.ncp |
| 2207 | * is ALWAYS returned, eve if the supplied component is illegal. |
| 2208 | * |
| 2209 | * The resulting namecache entry should be returned to the system with |
| 2210 | * cache_put() or cache_unlock() + cache_drop(). |
| 2211 | * |
| 2212 | * namecache locks are recursive but care must be taken to avoid lock order |
| 2213 | * reversals (hence why the passed par_nch must be unlocked). Locking |
| 2214 | * rules are to order for parent traversals, not for child traversals. |
| 2215 | * |
| 2216 | * Nobody else will be able to manipulate the associated namespace (e.g. |
| 2217 | * create, delete, rename, rename-target) until the caller unlocks the |
| 2218 | * entry. |
| 2219 | * |
| 2220 | * The returned entry will be in one of three states: positive hit (non-null |
| 2221 | * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). |
| 2222 | * Unresolved entries must be resolved through the filesystem to associate the |
| 2223 | * vnode and/or determine whether a positive or negative hit has occured. |
| 2224 | * |
| 2225 | * It is not necessary to lock a directory in order to lock namespace under |
| 2226 | * that directory. In fact, it is explicitly not allowed to do that. A |
| 2227 | * directory is typically only locked when being created, renamed, or |
| 2228 | * destroyed. |
| 2229 | * |
| 2230 | * The directory (par) may be unresolved, in which case any returned child |
| 2231 | * will likely also be marked unresolved. Likely but not guarenteed. Since |
| 2232 | * the filesystem lookup requires a resolved directory vnode the caller is |
| 2233 | * responsible for resolving the namecache chain top-down. This API |
| 2234 | * specifically allows whole chains to be created in an unresolved state. |
| 2235 | */ |
| 2236 | struct nchandle |
| 2237 | cache_nlookup(struct nchandle *par_nch, struct nlcomponent *nlc) |
| 2238 | { |
| 2239 | struct nchandle nch; |
| 2240 | struct namecache *ncp; |
| 2241 | struct namecache *new_ncp; |
| 2242 | struct nchash_head *nchpp; |
| 2243 | struct mount *mp; |
| 2244 | u_int32_t hash; |
| 2245 | globaldata_t gd; |
| 2246 | int par_locked; |
| 2247 | |
| 2248 | numcalls++; |
| 2249 | gd = mycpu; |
| 2250 | mp = par_nch->mount; |
| 2251 | par_locked = 0; |
| 2252 | |
| 2253 | /* |
| 2254 | * This is a good time to call it, no ncp's are locked by |
| 2255 | * the caller or us. |
| 2256 | */ |
| 2257 | cache_hysteresis(); |
| 2258 | |
| 2259 | /* |
| 2260 | * Try to locate an existing entry |
| 2261 | */ |
| 2262 | hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); |
| 2263 | hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); |
| 2264 | new_ncp = NULL; |
| 2265 | nchpp = NCHHASH(hash); |
| 2266 | restart: |
| 2267 | spin_lock(&nchpp->spin); |
| 2268 | LIST_FOREACH(ncp, &nchpp->list, nc_hash) { |
| 2269 | numchecks++; |
| 2270 | |
| 2271 | /* |
| 2272 | * Break out if we find a matching entry. Note that |
| 2273 | * UNRESOLVED entries may match, but DESTROYED entries |
| 2274 | * do not. |
| 2275 | */ |
| 2276 | if (ncp->nc_parent == par_nch->ncp && |
| 2277 | ncp->nc_nlen == nlc->nlc_namelen && |
| 2278 | bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && |
| 2279 | (ncp->nc_flag & NCF_DESTROYED) == 0 |
| 2280 | ) { |
| 2281 | _cache_hold(ncp); |
| 2282 | spin_unlock(&nchpp->spin); |
| 2283 | if (par_locked) { |
| 2284 | _cache_unlock(par_nch->ncp); |
| 2285 | par_locked = 0; |
| 2286 | } |
| 2287 | if (_cache_lock_special(ncp) == 0) { |
| 2288 | _cache_auto_unresolve(mp, ncp); |
| 2289 | if (new_ncp) |
| 2290 | _cache_free(new_ncp); |
| 2291 | goto found; |
| 2292 | } |
| 2293 | _cache_get(ncp); |
| 2294 | _cache_put(ncp); |
| 2295 | _cache_drop(ncp); |
| 2296 | goto restart; |
| 2297 | } |
| 2298 | } |
| 2299 | |
| 2300 | /* |
| 2301 | * We failed to locate an entry, create a new entry and add it to |
| 2302 | * the cache. The parent ncp must also be locked so we |
| 2303 | * can link into it. |
| 2304 | * |
| 2305 | * We have to relookup after possibly blocking in kmalloc or |
| 2306 | * when locking par_nch. |
| 2307 | * |
| 2308 | * NOTE: nlc_namelen can be 0 and nlc_nameptr NULL as a special |
| 2309 | * mount case, in which case nc_name will be NULL. |
| 2310 | */ |
| 2311 | if (new_ncp == NULL) { |
| 2312 | spin_unlock(&nchpp->spin); |
| 2313 | new_ncp = cache_alloc(nlc->nlc_namelen); |
| 2314 | if (nlc->nlc_namelen) { |
| 2315 | bcopy(nlc->nlc_nameptr, new_ncp->nc_name, |
| 2316 | nlc->nlc_namelen); |
| 2317 | new_ncp->nc_name[nlc->nlc_namelen] = 0; |
| 2318 | } |
| 2319 | goto restart; |
| 2320 | } |
| 2321 | if (par_locked == 0) { |
| 2322 | spin_unlock(&nchpp->spin); |
| 2323 | _cache_lock(par_nch->ncp); |
| 2324 | par_locked = 1; |
| 2325 | goto restart; |
| 2326 | } |
| 2327 | |
| 2328 | /* |
| 2329 | * WARNING! We still hold the spinlock. We have to set the hash |
| 2330 | * table entry atomically. |
| 2331 | */ |
| 2332 | ncp = new_ncp; |
| 2333 | _cache_link_parent(ncp, par_nch->ncp, nchpp); |
| 2334 | spin_unlock(&nchpp->spin); |
| 2335 | _cache_unlock(par_nch->ncp); |
| 2336 | /* par_locked = 0 - not used */ |
| 2337 | found: |
| 2338 | /* |
| 2339 | * stats and namecache size management |
| 2340 | */ |
| 2341 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 2342 | ++gd->gd_nchstats->ncs_miss; |
| 2343 | else if (ncp->nc_vp) |
| 2344 | ++gd->gd_nchstats->ncs_goodhits; |
| 2345 | else |
| 2346 | ++gd->gd_nchstats->ncs_neghits; |
| 2347 | nch.mount = mp; |
| 2348 | nch.ncp = ncp; |
| 2349 | atomic_add_int(&nch.mount->mnt_refs, 1); |
| 2350 | return(nch); |
| 2351 | } |
| 2352 | |
| 2353 | /* |
| 2354 | * This is a non-blocking verison of cache_nlookup() used by |
| 2355 | * nfs_readdirplusrpc_uio(). It can fail for any reason and |
| 2356 | * will return nch.ncp == NULL in that case. |
| 2357 | */ |
| 2358 | struct nchandle |
| 2359 | cache_nlookup_nonblock(struct nchandle *par_nch, struct nlcomponent *nlc) |
| 2360 | { |
| 2361 | struct nchandle nch; |
| 2362 | struct namecache *ncp; |
| 2363 | struct namecache *new_ncp; |
| 2364 | struct nchash_head *nchpp; |
| 2365 | struct mount *mp; |
| 2366 | u_int32_t hash; |
| 2367 | globaldata_t gd; |
| 2368 | int par_locked; |
| 2369 | |
| 2370 | numcalls++; |
| 2371 | gd = mycpu; |
| 2372 | mp = par_nch->mount; |
| 2373 | par_locked = 0; |
| 2374 | |
| 2375 | /* |
| 2376 | * Try to locate an existing entry |
| 2377 | */ |
| 2378 | hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); |
| 2379 | hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); |
| 2380 | new_ncp = NULL; |
| 2381 | nchpp = NCHHASH(hash); |
| 2382 | restart: |
| 2383 | spin_lock(&nchpp->spin); |
| 2384 | LIST_FOREACH(ncp, &nchpp->list, nc_hash) { |
| 2385 | numchecks++; |
| 2386 | |
| 2387 | /* |
| 2388 | * Break out if we find a matching entry. Note that |
| 2389 | * UNRESOLVED entries may match, but DESTROYED entries |
| 2390 | * do not. |
| 2391 | */ |
| 2392 | if (ncp->nc_parent == par_nch->ncp && |
| 2393 | ncp->nc_nlen == nlc->nlc_namelen && |
| 2394 | bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && |
| 2395 | (ncp->nc_flag & NCF_DESTROYED) == 0 |
| 2396 | ) { |
| 2397 | _cache_hold(ncp); |
| 2398 | spin_unlock(&nchpp->spin); |
| 2399 | if (par_locked) { |
| 2400 | _cache_unlock(par_nch->ncp); |
| 2401 | par_locked = 0; |
| 2402 | } |
| 2403 | if (_cache_lock_special(ncp) == 0) { |
| 2404 | _cache_auto_unresolve(mp, ncp); |
| 2405 | if (new_ncp) { |
| 2406 | _cache_free(new_ncp); |
| 2407 | new_ncp = NULL; |
| 2408 | } |
| 2409 | goto found; |
| 2410 | } |
| 2411 | _cache_drop(ncp); |
| 2412 | goto failed; |
| 2413 | } |
| 2414 | } |
| 2415 | |
| 2416 | /* |
| 2417 | * We failed to locate an entry, create a new entry and add it to |
| 2418 | * the cache. The parent ncp must also be locked so we |
| 2419 | * can link into it. |
| 2420 | * |
| 2421 | * We have to relookup after possibly blocking in kmalloc or |
| 2422 | * when locking par_nch. |
| 2423 | * |
| 2424 | * NOTE: nlc_namelen can be 0 and nlc_nameptr NULL as a special |
| 2425 | * mount case, in which case nc_name will be NULL. |
| 2426 | */ |
| 2427 | if (new_ncp == NULL) { |
| 2428 | spin_unlock(&nchpp->spin); |
| 2429 | new_ncp = cache_alloc(nlc->nlc_namelen); |
| 2430 | if (nlc->nlc_namelen) { |
| 2431 | bcopy(nlc->nlc_nameptr, new_ncp->nc_name, |
| 2432 | nlc->nlc_namelen); |
| 2433 | new_ncp->nc_name[nlc->nlc_namelen] = 0; |
| 2434 | } |
| 2435 | goto restart; |
| 2436 | } |
| 2437 | if (par_locked == 0) { |
| 2438 | spin_unlock(&nchpp->spin); |
| 2439 | if (_cache_lock_nonblock(par_nch->ncp) == 0) { |
| 2440 | par_locked = 1; |
| 2441 | goto restart; |
| 2442 | } |
| 2443 | goto failed; |
| 2444 | } |
| 2445 | |
| 2446 | /* |
| 2447 | * WARNING! We still hold the spinlock. We have to set the hash |
| 2448 | * table entry atomically. |
| 2449 | */ |
| 2450 | ncp = new_ncp; |
| 2451 | _cache_link_parent(ncp, par_nch->ncp, nchpp); |
| 2452 | spin_unlock(&nchpp->spin); |
| 2453 | _cache_unlock(par_nch->ncp); |
| 2454 | /* par_locked = 0 - not used */ |
| 2455 | found: |
| 2456 | /* |
| 2457 | * stats and namecache size management |
| 2458 | */ |
| 2459 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 2460 | ++gd->gd_nchstats->ncs_miss; |
| 2461 | else if (ncp->nc_vp) |
| 2462 | ++gd->gd_nchstats->ncs_goodhits; |
| 2463 | else |
| 2464 | ++gd->gd_nchstats->ncs_neghits; |
| 2465 | nch.mount = mp; |
| 2466 | nch.ncp = ncp; |
| 2467 | atomic_add_int(&nch.mount->mnt_refs, 1); |
| 2468 | return(nch); |
| 2469 | failed: |
| 2470 | if (new_ncp) { |
| 2471 | _cache_free(new_ncp); |
| 2472 | new_ncp = NULL; |
| 2473 | } |
| 2474 | nch.mount = NULL; |
| 2475 | nch.ncp = NULL; |
| 2476 | return(nch); |
| 2477 | } |
| 2478 | |
| 2479 | /* |
| 2480 | * The namecache entry is marked as being used as a mount point. |
| 2481 | * Locate the mount if it is visible to the caller. |
| 2482 | */ |
| 2483 | struct findmount_info { |
| 2484 | struct mount *result; |
| 2485 | struct mount *nch_mount; |
| 2486 | struct namecache *nch_ncp; |
| 2487 | }; |
| 2488 | |
| 2489 | static |
| 2490 | int |
| 2491 | cache_findmount_callback(struct mount *mp, void *data) |
| 2492 | { |
| 2493 | struct findmount_info *info = data; |
| 2494 | |
| 2495 | /* |
| 2496 | * Check the mount's mounted-on point against the passed nch. |
| 2497 | */ |
| 2498 | if (mp->mnt_ncmounton.mount == info->nch_mount && |
| 2499 | mp->mnt_ncmounton.ncp == info->nch_ncp |
| 2500 | ) { |
| 2501 | info->result = mp; |
| 2502 | atomic_add_int(&mp->mnt_refs, 1); |
| 2503 | return(-1); |
| 2504 | } |
| 2505 | return(0); |
| 2506 | } |
| 2507 | |
| 2508 | struct mount * |
| 2509 | cache_findmount(struct nchandle *nch) |
| 2510 | { |
| 2511 | struct findmount_info info; |
| 2512 | |
| 2513 | info.result = NULL; |
| 2514 | info.nch_mount = nch->mount; |
| 2515 | info.nch_ncp = nch->ncp; |
| 2516 | mountlist_scan(cache_findmount_callback, &info, |
| 2517 | MNTSCAN_FORWARD|MNTSCAN_NOBUSY); |
| 2518 | return(info.result); |
| 2519 | } |
| 2520 | |
| 2521 | void |
| 2522 | cache_dropmount(struct mount *mp) |
| 2523 | { |
| 2524 | atomic_add_int(&mp->mnt_refs, -1); |
| 2525 | } |
| 2526 | |
| 2527 | /* |
| 2528 | * Resolve an unresolved namecache entry, generally by looking it up. |
| 2529 | * The passed ncp must be locked and refd. |
| 2530 | * |
| 2531 | * Theoretically since a vnode cannot be recycled while held, and since |
| 2532 | * the nc_parent chain holds its vnode as long as children exist, the |
| 2533 | * direct parent of the cache entry we are trying to resolve should |
| 2534 | * have a valid vnode. If not then generate an error that we can |
| 2535 | * determine is related to a resolver bug. |
| 2536 | * |
| 2537 | * However, if a vnode was in the middle of a recyclement when the NCP |
| 2538 | * got locked, ncp->nc_vp might point to a vnode that is about to become |
| 2539 | * invalid. cache_resolve() handles this case by unresolving the entry |
| 2540 | * and then re-resolving it. |
| 2541 | * |
| 2542 | * Note that successful resolution does not necessarily return an error |
| 2543 | * code of 0. If the ncp resolves to a negative cache hit then ENOENT |
| 2544 | * will be returned. |
| 2545 | * |
| 2546 | * MPSAFE |
| 2547 | */ |
| 2548 | int |
| 2549 | cache_resolve(struct nchandle *nch, struct ucred *cred) |
| 2550 | { |
| 2551 | struct namecache *par_tmp; |
| 2552 | struct namecache *par; |
| 2553 | struct namecache *ncp; |
| 2554 | struct nchandle nctmp; |
| 2555 | struct mount *mp; |
| 2556 | struct vnode *dvp; |
| 2557 | int error; |
| 2558 | |
| 2559 | ncp = nch->ncp; |
| 2560 | mp = nch->mount; |
| 2561 | restart: |
| 2562 | /* |
| 2563 | * If the ncp is already resolved we have nothing to do. However, |
| 2564 | * we do want to guarentee that a usable vnode is returned when |
| 2565 | * a vnode is present, so make sure it hasn't been reclaimed. |
| 2566 | */ |
| 2567 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 2568 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 2569 | _cache_setunresolved(ncp); |
| 2570 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) |
| 2571 | return (ncp->nc_error); |
| 2572 | } |
| 2573 | |
| 2574 | /* |
| 2575 | * Mount points need special handling because the parent does not |
| 2576 | * belong to the same filesystem as the ncp. |
| 2577 | */ |
| 2578 | if (ncp == mp->mnt_ncmountpt.ncp) |
| 2579 | return (cache_resolve_mp(mp)); |
| 2580 | |
| 2581 | /* |
| 2582 | * We expect an unbroken chain of ncps to at least the mount point, |
| 2583 | * and even all the way to root (but this code doesn't have to go |
| 2584 | * past the mount point). |
| 2585 | */ |
| 2586 | if (ncp->nc_parent == NULL) { |
| 2587 | kprintf("EXDEV case 1 %p %*.*s\n", ncp, |
| 2588 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 2589 | ncp->nc_error = EXDEV; |
| 2590 | return(ncp->nc_error); |
| 2591 | } |
| 2592 | |
| 2593 | /* |
| 2594 | * The vp's of the parent directories in the chain are held via vhold() |
| 2595 | * due to the existance of the child, and should not disappear. |
| 2596 | * However, there are cases where they can disappear: |
| 2597 | * |
| 2598 | * - due to filesystem I/O errors. |
| 2599 | * - due to NFS being stupid about tracking the namespace and |
| 2600 | * destroys the namespace for entire directories quite often. |
| 2601 | * - due to forced unmounts. |
| 2602 | * - due to an rmdir (parent will be marked DESTROYED) |
| 2603 | * |
| 2604 | * When this occurs we have to track the chain backwards and resolve |
| 2605 | * it, looping until the resolver catches up to the current node. We |
| 2606 | * could recurse here but we might run ourselves out of kernel stack |
| 2607 | * so we do it in a more painful manner. This situation really should |
| 2608 | * not occur all that often, or if it does not have to go back too |
| 2609 | * many nodes to resolve the ncp. |
| 2610 | */ |
| 2611 | while ((dvp = cache_dvpref(ncp)) == NULL) { |
| 2612 | /* |
| 2613 | * This case can occur if a process is CD'd into a |
| 2614 | * directory which is then rmdir'd. If the parent is marked |
| 2615 | * destroyed there is no point trying to resolve it. |
| 2616 | */ |
| 2617 | if (ncp->nc_parent->nc_flag & NCF_DESTROYED) |
| 2618 | return(ENOENT); |
| 2619 | par = ncp->nc_parent; |
| 2620 | _cache_hold(par); |
| 2621 | _cache_lock(par); |
| 2622 | while ((par_tmp = par->nc_parent) != NULL && |
| 2623 | par_tmp->nc_vp == NULL) { |
| 2624 | _cache_hold(par_tmp); |
| 2625 | _cache_lock(par_tmp); |
| 2626 | _cache_put(par); |
| 2627 | par = par_tmp; |
| 2628 | } |
| 2629 | if (par->nc_parent == NULL) { |
| 2630 | kprintf("EXDEV case 2 %*.*s\n", |
| 2631 | par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2632 | _cache_put(par); |
| 2633 | return (EXDEV); |
| 2634 | } |
| 2635 | kprintf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", |
| 2636 | par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2637 | /* |
| 2638 | * The parent is not set in stone, ref and lock it to prevent |
| 2639 | * it from disappearing. Also note that due to renames it |
| 2640 | * is possible for our ncp to move and for par to no longer |
| 2641 | * be one of its parents. We resolve it anyway, the loop |
| 2642 | * will handle any moves. |
| 2643 | */ |
| 2644 | _cache_get(par); /* additional hold/lock */ |
| 2645 | _cache_put(par); /* from earlier hold/lock */ |
| 2646 | if (par == nch->mount->mnt_ncmountpt.ncp) { |
| 2647 | cache_resolve_mp(nch->mount); |
| 2648 | } else if ((dvp = cache_dvpref(par)) == NULL) { |
| 2649 | kprintf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2650 | _cache_put(par); |
| 2651 | continue; |
| 2652 | } else { |
| 2653 | if (par->nc_flag & NCF_UNRESOLVED) { |
| 2654 | nctmp.mount = mp; |
| 2655 | nctmp.ncp = par; |
| 2656 | par->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); |
| 2657 | } |
| 2658 | vrele(dvp); |
| 2659 | } |
| 2660 | if ((error = par->nc_error) != 0) { |
| 2661 | if (par->nc_error != EAGAIN) { |
| 2662 | kprintf("EXDEV case 3 %*.*s error %d\n", |
| 2663 | par->nc_nlen, par->nc_nlen, par->nc_name, |
| 2664 | par->nc_error); |
| 2665 | _cache_put(par); |
| 2666 | return(error); |
| 2667 | } |
| 2668 | kprintf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", |
| 2669 | par, par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2670 | } |
| 2671 | _cache_put(par); |
| 2672 | /* loop */ |
| 2673 | } |
| 2674 | |
| 2675 | /* |
| 2676 | * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected |
| 2677 | * ncp's and reattach them. If this occurs the original ncp is marked |
| 2678 | * EAGAIN to force a relookup. |
| 2679 | * |
| 2680 | * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed |
| 2681 | * ncp must already be resolved. |
| 2682 | */ |
| 2683 | if (dvp) { |
| 2684 | nctmp.mount = mp; |
| 2685 | nctmp.ncp = ncp; |
| 2686 | ncp->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); |
| 2687 | vrele(dvp); |
| 2688 | } else { |
| 2689 | ncp->nc_error = EPERM; |
| 2690 | } |
| 2691 | if (ncp->nc_error == EAGAIN) { |
| 2692 | kprintf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", |
| 2693 | ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 2694 | goto restart; |
| 2695 | } |
| 2696 | return(ncp->nc_error); |
| 2697 | } |
| 2698 | |
| 2699 | /* |
| 2700 | * Resolve the ncp associated with a mount point. Such ncp's almost always |
| 2701 | * remain resolved and this routine is rarely called. NFS MPs tends to force |
| 2702 | * re-resolution more often due to its mac-truck-smash-the-namecache |
| 2703 | * method of tracking namespace changes. |
| 2704 | * |
| 2705 | * The semantics for this call is that the passed ncp must be locked on |
| 2706 | * entry and will be locked on return. However, if we actually have to |
| 2707 | * resolve the mount point we temporarily unlock the entry in order to |
| 2708 | * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of |
| 2709 | * the unlock we have to recheck the flags after we relock. |
| 2710 | */ |
| 2711 | static int |
| 2712 | cache_resolve_mp(struct mount *mp) |
| 2713 | { |
| 2714 | struct namecache *ncp = mp->mnt_ncmountpt.ncp; |
| 2715 | struct vnode *vp; |
| 2716 | int error; |
| 2717 | |
| 2718 | KKASSERT(mp != NULL); |
| 2719 | |
| 2720 | /* |
| 2721 | * If the ncp is already resolved we have nothing to do. However, |
| 2722 | * we do want to guarentee that a usable vnode is returned when |
| 2723 | * a vnode is present, so make sure it hasn't been reclaimed. |
| 2724 | */ |
| 2725 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 2726 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 2727 | _cache_setunresolved(ncp); |
| 2728 | } |
| 2729 | |
| 2730 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 2731 | _cache_unlock(ncp); |
| 2732 | while (vfs_busy(mp, 0)) |
| 2733 | ; |
| 2734 | error = VFS_ROOT(mp, &vp); |
| 2735 | _cache_lock(ncp); |
| 2736 | |
| 2737 | /* |
| 2738 | * recheck the ncp state after relocking. |
| 2739 | */ |
| 2740 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 2741 | ncp->nc_error = error; |
| 2742 | if (error == 0) { |
| 2743 | _cache_setvp(mp, ncp, vp); |
| 2744 | vput(vp); |
| 2745 | } else { |
| 2746 | kprintf("[diagnostic] cache_resolve_mp: failed" |
| 2747 | " to resolve mount %p err=%d ncp=%p\n", |
| 2748 | mp, error, ncp); |
| 2749 | _cache_setvp(mp, ncp, NULL); |
| 2750 | } |
| 2751 | } else if (error == 0) { |
| 2752 | vput(vp); |
| 2753 | } |
| 2754 | vfs_unbusy(mp); |
| 2755 | } |
| 2756 | return(ncp->nc_error); |
| 2757 | } |
| 2758 | |
| 2759 | /* |
| 2760 | * Clean out negative cache entries when too many have accumulated. |
| 2761 | * |
| 2762 | * MPSAFE |
| 2763 | */ |
| 2764 | static void |
| 2765 | _cache_cleanneg(int count) |
| 2766 | { |
| 2767 | struct namecache *ncp; |
| 2768 | |
| 2769 | /* |
| 2770 | * Attempt to clean out the specified number of negative cache |
| 2771 | * entries. |
| 2772 | */ |
| 2773 | while (count) { |
| 2774 | spin_lock(&ncspin); |
| 2775 | ncp = TAILQ_FIRST(&ncneglist); |
| 2776 | if (ncp == NULL) { |
| 2777 | spin_unlock(&ncspin); |
| 2778 | break; |
| 2779 | } |
| 2780 | TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); |
| 2781 | TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); |
| 2782 | _cache_hold(ncp); |
| 2783 | spin_unlock(&ncspin); |
| 2784 | if (_cache_lock_special(ncp) == 0) { |
| 2785 | ncp = cache_zap(ncp, 1); |
| 2786 | if (ncp) |
| 2787 | _cache_drop(ncp); |
| 2788 | } else { |
| 2789 | _cache_drop(ncp); |
| 2790 | } |
| 2791 | --count; |
| 2792 | } |
| 2793 | } |
| 2794 | |
| 2795 | /* |
| 2796 | * Clean out positive cache entries when too many have accumulated. |
| 2797 | * |
| 2798 | * MPSAFE |
| 2799 | */ |
| 2800 | static void |
| 2801 | _cache_cleanpos(int count) |
| 2802 | { |
| 2803 | static volatile int rover; |
| 2804 | struct nchash_head *nchpp; |
| 2805 | struct namecache *ncp; |
| 2806 | int rover_copy; |
| 2807 | |
| 2808 | /* |
| 2809 | * Attempt to clean out the specified number of negative cache |
| 2810 | * entries. |
| 2811 | */ |
| 2812 | while (count) { |
| 2813 | rover_copy = ++rover; /* MPSAFEENOUGH */ |
| 2814 | cpu_ccfence(); |
| 2815 | nchpp = NCHHASH(rover_copy); |
| 2816 | |
| 2817 | spin_lock(&nchpp->spin); |
| 2818 | ncp = LIST_FIRST(&nchpp->list); |
| 2819 | if (ncp) |
| 2820 | _cache_hold(ncp); |
| 2821 | spin_unlock(&nchpp->spin); |
| 2822 | |
| 2823 | if (ncp) { |
| 2824 | if (_cache_lock_special(ncp) == 0) { |
| 2825 | ncp = cache_zap(ncp, 1); |
| 2826 | if (ncp) |
| 2827 | _cache_drop(ncp); |
| 2828 | } else { |
| 2829 | _cache_drop(ncp); |
| 2830 | } |
| 2831 | } |
| 2832 | --count; |
| 2833 | } |
| 2834 | } |
| 2835 | |
| 2836 | /* |
| 2837 | * This is a kitchen sink function to clean out ncps which we |
| 2838 | * tried to zap from cache_drop() but failed because we were |
| 2839 | * unable to acquire the parent lock. |
| 2840 | * |
| 2841 | * Such entries can also be removed via cache_inval_vp(), such |
| 2842 | * as when unmounting. |
| 2843 | * |
| 2844 | * MPSAFE |
| 2845 | */ |
| 2846 | static void |
| 2847 | _cache_cleandefered(void) |
| 2848 | { |
| 2849 | struct nchash_head *nchpp; |
| 2850 | struct namecache *ncp; |
| 2851 | struct namecache dummy; |
| 2852 | int i; |
| 2853 | |
| 2854 | numdefered = 0; |
| 2855 | bzero(&dummy, sizeof(dummy)); |
| 2856 | dummy.nc_flag = NCF_DESTROYED; |
| 2857 | |
| 2858 | for (i = 0; i <= nchash; ++i) { |
| 2859 | nchpp = &nchashtbl[i]; |
| 2860 | |
| 2861 | spin_lock(&nchpp->spin); |
| 2862 | LIST_INSERT_HEAD(&nchpp->list, &dummy, nc_hash); |
| 2863 | ncp = &dummy; |
| 2864 | while ((ncp = LIST_NEXT(ncp, nc_hash)) != NULL) { |
| 2865 | if ((ncp->nc_flag & NCF_DEFEREDZAP) == 0) |
| 2866 | continue; |
| 2867 | LIST_REMOVE(&dummy, nc_hash); |
| 2868 | LIST_INSERT_AFTER(ncp, &dummy, nc_hash); |
| 2869 | _cache_hold(ncp); |
| 2870 | spin_unlock(&nchpp->spin); |
| 2871 | if (_cache_lock_nonblock(ncp) == 0) { |
| 2872 | ncp->nc_flag &= ~NCF_DEFEREDZAP; |
| 2873 | _cache_unlock(ncp); |
| 2874 | } |
| 2875 | _cache_drop(ncp); |
| 2876 | spin_lock(&nchpp->spin); |
| 2877 | ncp = &dummy; |
| 2878 | } |
| 2879 | LIST_REMOVE(&dummy, nc_hash); |
| 2880 | spin_unlock(&nchpp->spin); |
| 2881 | } |
| 2882 | } |
| 2883 | |
| 2884 | /* |
| 2885 | * Name cache initialization, from vfsinit() when we are booting |
| 2886 | */ |
| 2887 | void |
| 2888 | nchinit(void) |
| 2889 | { |
| 2890 | int i; |
| 2891 | globaldata_t gd; |
| 2892 | |
| 2893 | /* initialise per-cpu namecache effectiveness statistics. */ |
| 2894 | for (i = 0; i < ncpus; ++i) { |
| 2895 | gd = globaldata_find(i); |
| 2896 | gd->gd_nchstats = &nchstats[i]; |
| 2897 | } |
| 2898 | TAILQ_INIT(&ncneglist); |
| 2899 | spin_init(&ncspin); |
| 2900 | nchashtbl = hashinit_ext(desiredvnodes / 2, |
| 2901 | sizeof(struct nchash_head), |
| 2902 | M_VFSCACHE, &nchash); |
| 2903 | for (i = 0; i <= (int)nchash; ++i) { |
| 2904 | LIST_INIT(&nchashtbl[i].list); |
| 2905 | spin_init(&nchashtbl[i].spin); |
| 2906 | } |
| 2907 | nclockwarn = 5 * hz; |
| 2908 | } |
| 2909 | |
| 2910 | /* |
| 2911 | * Called from start_init() to bootstrap the root filesystem. Returns |
| 2912 | * a referenced, unlocked namecache record. |
| 2913 | */ |
| 2914 | void |
| 2915 | cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp) |
| 2916 | { |
| 2917 | nch->ncp = cache_alloc(0); |
| 2918 | nch->mount = mp; |
| 2919 | atomic_add_int(&mp->mnt_refs, 1); |
| 2920 | if (vp) |
| 2921 | _cache_setvp(nch->mount, nch->ncp, vp); |
| 2922 | } |
| 2923 | |
| 2924 | /* |
| 2925 | * vfs_cache_setroot() |
| 2926 | * |
| 2927 | * Create an association between the root of our namecache and |
| 2928 | * the root vnode. This routine may be called several times during |
| 2929 | * booting. |
| 2930 | * |
| 2931 | * If the caller intends to save the returned namecache pointer somewhere |
| 2932 | * it must cache_hold() it. |
| 2933 | */ |
| 2934 | void |
| 2935 | vfs_cache_setroot(struct vnode *nvp, struct nchandle *nch) |
| 2936 | { |
| 2937 | struct vnode *ovp; |
| 2938 | struct nchandle onch; |
| 2939 | |
| 2940 | ovp = rootvnode; |
| 2941 | onch = rootnch; |
| 2942 | rootvnode = nvp; |
| 2943 | if (nch) |
| 2944 | rootnch = *nch; |
| 2945 | else |
| 2946 | cache_zero(&rootnch); |
| 2947 | if (ovp) |
| 2948 | vrele(ovp); |
| 2949 | if (onch.ncp) |
| 2950 | cache_drop(&onch); |
| 2951 | } |
| 2952 | |
| 2953 | /* |
| 2954 | * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache |
| 2955 | * topology and is being removed as quickly as possible. The new VOP_N*() |
| 2956 | * API calls are required to make specific adjustments using the supplied |
| 2957 | * ncp pointers rather then just bogusly purging random vnodes. |
| 2958 | * |
| 2959 | * Invalidate all namecache entries to a particular vnode as well as |
| 2960 | * any direct children of that vnode in the namecache. This is a |
| 2961 | * 'catch all' purge used by filesystems that do not know any better. |
| 2962 | * |
| 2963 | * Note that the linkage between the vnode and its namecache entries will |
| 2964 | * be removed, but the namecache entries themselves might stay put due to |
| 2965 | * active references from elsewhere in the system or due to the existance of |
| 2966 | * the children. The namecache topology is left intact even if we do not |
| 2967 | * know what the vnode association is. Such entries will be marked |
| 2968 | * NCF_UNRESOLVED. |
| 2969 | */ |
| 2970 | void |
| 2971 | cache_purge(struct vnode *vp) |
| 2972 | { |
| 2973 | cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN); |
| 2974 | } |
| 2975 | |
| 2976 | /* |
| 2977 | * Flush all entries referencing a particular filesystem. |
| 2978 | * |
| 2979 | * Since we need to check it anyway, we will flush all the invalid |
| 2980 | * entries at the same time. |
| 2981 | */ |
| 2982 | #if 0 |
| 2983 | |
| 2984 | void |
| 2985 | cache_purgevfs(struct mount *mp) |
| 2986 | { |
| 2987 | struct nchash_head *nchpp; |
| 2988 | struct namecache *ncp, *nnp; |
| 2989 | |
| 2990 | /* |
| 2991 | * Scan hash tables for applicable entries. |
| 2992 | */ |
| 2993 | for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { |
| 2994 | spin_lock_wr(&nchpp->spin); XXX |
| 2995 | ncp = LIST_FIRST(&nchpp->list); |
| 2996 | if (ncp) |
| 2997 | _cache_hold(ncp); |
| 2998 | while (ncp) { |
| 2999 | nnp = LIST_NEXT(ncp, nc_hash); |
| 3000 | if (nnp) |
| 3001 | _cache_hold(nnp); |
| 3002 | if (ncp->nc_mount == mp) { |
| 3003 | _cache_lock(ncp); |
| 3004 | ncp = cache_zap(ncp, 0); |
| 3005 | if (ncp) |
| 3006 | _cache_drop(ncp); |
| 3007 | } else { |
| 3008 | _cache_drop(ncp); |
| 3009 | } |
| 3010 | ncp = nnp; |
| 3011 | } |
| 3012 | spin_unlock_wr(&nchpp->spin); XXX |
| 3013 | } |
| 3014 | } |
| 3015 | |
| 3016 | #endif |
| 3017 | |
| 3018 | static int disablecwd; |
| 3019 | SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, |
| 3020 | "Disable getcwd"); |
| 3021 | |
| 3022 | static u_long numcwdcalls; |
| 3023 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdcalls, CTLFLAG_RD, &numcwdcalls, 0, |
| 3024 | "Number of current directory resolution calls"); |
| 3025 | static u_long numcwdfailnf; |
| 3026 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdfailnf, CTLFLAG_RD, &numcwdfailnf, 0, |
| 3027 | "Number of current directory failures due to lack of file"); |
| 3028 | static u_long numcwdfailsz; |
| 3029 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdfailsz, CTLFLAG_RD, &numcwdfailsz, 0, |
| 3030 | "Number of current directory failures due to large result"); |
| 3031 | static u_long numcwdfound; |
| 3032 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdfound, CTLFLAG_RD, &numcwdfound, 0, |
| 3033 | "Number of current directory resolution successes"); |
| 3034 | |
| 3035 | /* |
| 3036 | * MPALMOSTSAFE |
| 3037 | */ |
| 3038 | int |
| 3039 | sys___getcwd(struct __getcwd_args *uap) |
| 3040 | { |
| 3041 | u_int buflen; |
| 3042 | int error; |
| 3043 | char *buf; |
| 3044 | char *bp; |
| 3045 | |
| 3046 | if (disablecwd) |
| 3047 | return (ENODEV); |
| 3048 | |
| 3049 | buflen = uap->buflen; |
| 3050 | if (buflen == 0) |
| 3051 | return (EINVAL); |
| 3052 | if (buflen > MAXPATHLEN) |
| 3053 | buflen = MAXPATHLEN; |
| 3054 | |
| 3055 | buf = kmalloc(buflen, M_TEMP, M_WAITOK); |
| 3056 | get_mplock(); |
| 3057 | bp = kern_getcwd(buf, buflen, &error); |
| 3058 | rel_mplock(); |
| 3059 | if (error == 0) |
| 3060 | error = copyout(bp, uap->buf, strlen(bp) + 1); |
| 3061 | kfree(buf, M_TEMP); |
| 3062 | return (error); |
| 3063 | } |
| 3064 | |
| 3065 | char * |
| 3066 | kern_getcwd(char *buf, size_t buflen, int *error) |
| 3067 | { |
| 3068 | struct proc *p = curproc; |
| 3069 | char *bp; |
| 3070 | int i, slash_prefixed; |
| 3071 | struct filedesc *fdp; |
| 3072 | struct nchandle nch; |
| 3073 | struct namecache *ncp; |
| 3074 | |
| 3075 | numcwdcalls++; |
| 3076 | bp = buf; |
| 3077 | bp += buflen - 1; |
| 3078 | *bp = '\0'; |
| 3079 | fdp = p->p_fd; |
| 3080 | slash_prefixed = 0; |
| 3081 | |
| 3082 | nch = fdp->fd_ncdir; |
| 3083 | ncp = nch.ncp; |
| 3084 | if (ncp) |
| 3085 | _cache_hold(ncp); |
| 3086 | |
| 3087 | while (ncp && (ncp != fdp->fd_nrdir.ncp || |
| 3088 | nch.mount != fdp->fd_nrdir.mount) |
| 3089 | ) { |
| 3090 | /* |
| 3091 | * While traversing upwards if we encounter the root |
| 3092 | * of the current mount we have to skip to the mount point |
| 3093 | * in the underlying filesystem. |
| 3094 | */ |
| 3095 | if (ncp == nch.mount->mnt_ncmountpt.ncp) { |
| 3096 | nch = nch.mount->mnt_ncmounton; |
| 3097 | _cache_drop(ncp); |
| 3098 | ncp = nch.ncp; |
| 3099 | if (ncp) |
| 3100 | _cache_hold(ncp); |
| 3101 | continue; |
| 3102 | } |
| 3103 | |
| 3104 | /* |
| 3105 | * Prepend the path segment |
| 3106 | */ |
| 3107 | for (i = ncp->nc_nlen - 1; i >= 0; i--) { |
| 3108 | if (bp == buf) { |
| 3109 | numcwdfailsz++; |
| 3110 | *error = ERANGE; |
| 3111 | bp = NULL; |
| 3112 | goto done; |
| 3113 | } |
| 3114 | *--bp = ncp->nc_name[i]; |
| 3115 | } |
| 3116 | if (bp == buf) { |
| 3117 | numcwdfailsz++; |
| 3118 | *error = ERANGE; |
| 3119 | bp = NULL; |
| 3120 | goto done; |
| 3121 | } |
| 3122 | *--bp = '/'; |
| 3123 | slash_prefixed = 1; |
| 3124 | |
| 3125 | /* |
| 3126 | * Go up a directory. This isn't a mount point so we don't |
| 3127 | * have to check again. |
| 3128 | */ |
| 3129 | while ((nch.ncp = ncp->nc_parent) != NULL) { |
| 3130 | _cache_lock(ncp); |
| 3131 | if (nch.ncp != ncp->nc_parent) { |
| 3132 | _cache_unlock(ncp); |
| 3133 | continue; |
| 3134 | } |
| 3135 | _cache_hold(nch.ncp); |
| 3136 | _cache_unlock(ncp); |
| 3137 | break; |
| 3138 | } |
| 3139 | _cache_drop(ncp); |
| 3140 | ncp = nch.ncp; |
| 3141 | } |
| 3142 | if (ncp == NULL) { |
| 3143 | numcwdfailnf++; |
| 3144 | *error = ENOENT; |
| 3145 | bp = NULL; |
| 3146 | goto done; |
| 3147 | } |
| 3148 | if (!slash_prefixed) { |
| 3149 | if (bp == buf) { |
| 3150 | numcwdfailsz++; |
| 3151 | *error = ERANGE; |
| 3152 | bp = NULL; |
| 3153 | goto done; |
| 3154 | } |
| 3155 | *--bp = '/'; |
| 3156 | } |
| 3157 | numcwdfound++; |
| 3158 | *error = 0; |
| 3159 | done: |
| 3160 | if (ncp) |
| 3161 | _cache_drop(ncp); |
| 3162 | return (bp); |
| 3163 | } |
| 3164 | |
| 3165 | /* |
| 3166 | * Thus begins the fullpath magic. |
| 3167 | * |
| 3168 | * The passed nchp is referenced but not locked. |
| 3169 | */ |
| 3170 | static int disablefullpath; |
| 3171 | SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, |
| 3172 | &disablefullpath, 0, |
| 3173 | "Disable fullpath lookups"); |
| 3174 | |
| 3175 | static u_int numfullpathcalls; |
| 3176 | SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathcalls, CTLFLAG_RD, |
| 3177 | &numfullpathcalls, 0, |
| 3178 | "Number of full path resolutions in progress"); |
| 3179 | static u_int numfullpathfailnf; |
| 3180 | SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathfailnf, CTLFLAG_RD, |
| 3181 | &numfullpathfailnf, 0, |
| 3182 | "Number of full path resolution failures due to lack of file"); |
| 3183 | static u_int numfullpathfailsz; |
| 3184 | SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathfailsz, CTLFLAG_RD, |
| 3185 | &numfullpathfailsz, 0, |
| 3186 | "Number of full path resolution failures due to insufficient memory"); |
| 3187 | static u_int numfullpathfound; |
| 3188 | SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathfound, CTLFLAG_RD, |
| 3189 | &numfullpathfound, 0, |
| 3190 | "Number of full path resolution successes"); |
| 3191 | |
| 3192 | int |
| 3193 | cache_fullpath(struct proc *p, struct nchandle *nchp, |
| 3194 | char **retbuf, char **freebuf, int guess) |
| 3195 | { |
| 3196 | struct nchandle fd_nrdir; |
| 3197 | struct nchandle nch; |
| 3198 | struct namecache *ncp; |
| 3199 | struct mount *mp, *new_mp; |
| 3200 | char *bp, *buf; |
| 3201 | int slash_prefixed; |
| 3202 | int error = 0; |
| 3203 | int i; |
| 3204 | |
| 3205 | atomic_add_int(&numfullpathcalls, -1); |
| 3206 | |
| 3207 | *retbuf = NULL; |
| 3208 | *freebuf = NULL; |
| 3209 | |
| 3210 | buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK); |
| 3211 | bp = buf + MAXPATHLEN - 1; |
| 3212 | *bp = '\0'; |
| 3213 | if (p != NULL) |
| 3214 | fd_nrdir = p->p_fd->fd_nrdir; |
| 3215 | else |
| 3216 | fd_nrdir = rootnch; |
| 3217 | slash_prefixed = 0; |
| 3218 | nch = *nchp; |
| 3219 | ncp = nch.ncp; |
| 3220 | if (ncp) |
| 3221 | _cache_hold(ncp); |
| 3222 | mp = nch.mount; |
| 3223 | |
| 3224 | while (ncp && (ncp != fd_nrdir.ncp || mp != fd_nrdir.mount)) { |
| 3225 | new_mp = NULL; |
| 3226 | |
| 3227 | /* |
| 3228 | * If we are asked to guess the upwards path, we do so whenever |
| 3229 | * we encounter an ncp marked as a mountpoint. We try to find |
| 3230 | * the actual mountpoint by finding the mountpoint with this ncp. |
| 3231 | */ |
| 3232 | if (guess && (ncp->nc_flag & NCF_ISMOUNTPT)) { |
| 3233 | new_mp = mount_get_by_nc(ncp); |
| 3234 | } |
| 3235 | /* |
| 3236 | * While traversing upwards if we encounter the root |
| 3237 | * of the current mount we have to skip to the mount point. |
| 3238 | */ |
| 3239 | if (ncp == mp->mnt_ncmountpt.ncp) { |
| 3240 | new_mp = mp; |
| 3241 | } |
| 3242 | if (new_mp) { |
| 3243 | nch = new_mp->mnt_ncmounton; |
| 3244 | _cache_drop(ncp); |
| 3245 | ncp = nch.ncp; |
| 3246 | if (ncp) |
| 3247 | _cache_hold(ncp); |
| 3248 | mp = nch.mount; |
| 3249 | continue; |
| 3250 | } |
| 3251 | |
| 3252 | /* |
| 3253 | * Prepend the path segment |
| 3254 | */ |
| 3255 | for (i = ncp->nc_nlen - 1; i >= 0; i--) { |
| 3256 | if (bp == buf) { |
| 3257 | numfullpathfailsz++; |
| 3258 | kfree(buf, M_TEMP); |
| 3259 | error = ENOMEM; |
| 3260 | goto done; |
| 3261 | } |
| 3262 | *--bp = ncp->nc_name[i]; |
| 3263 | } |
| 3264 | if (bp == buf) { |
| 3265 | numfullpathfailsz++; |
| 3266 | kfree(buf, M_TEMP); |
| 3267 | error = ENOMEM; |
| 3268 | goto done; |
| 3269 | } |
| 3270 | *--bp = '/'; |
| 3271 | slash_prefixed = 1; |
| 3272 | |
| 3273 | /* |
| 3274 | * Go up a directory. This isn't a mount point so we don't |
| 3275 | * have to check again. |
| 3276 | * |
| 3277 | * We can only safely access nc_parent with ncp held locked. |
| 3278 | */ |
| 3279 | while ((nch.ncp = ncp->nc_parent) != NULL) { |
| 3280 | _cache_lock(ncp); |
| 3281 | if (nch.ncp != ncp->nc_parent) { |
| 3282 | _cache_unlock(ncp); |
| 3283 | continue; |
| 3284 | } |
| 3285 | _cache_hold(nch.ncp); |
| 3286 | _cache_unlock(ncp); |
| 3287 | break; |
| 3288 | } |
| 3289 | _cache_drop(ncp); |
| 3290 | ncp = nch.ncp; |
| 3291 | } |
| 3292 | if (ncp == NULL) { |
| 3293 | numfullpathfailnf++; |
| 3294 | kfree(buf, M_TEMP); |
| 3295 | error = ENOENT; |
| 3296 | goto done; |
| 3297 | } |
| 3298 | |
| 3299 | if (!slash_prefixed) { |
| 3300 | if (bp == buf) { |
| 3301 | numfullpathfailsz++; |
| 3302 | kfree(buf, M_TEMP); |
| 3303 | error = ENOMEM; |
| 3304 | goto done; |
| 3305 | } |
| 3306 | *--bp = '/'; |
| 3307 | } |
| 3308 | numfullpathfound++; |
| 3309 | *retbuf = bp; |
| 3310 | *freebuf = buf; |
| 3311 | error = 0; |
| 3312 | done: |
| 3313 | if (ncp) |
| 3314 | _cache_drop(ncp); |
| 3315 | return(error); |
| 3316 | } |
| 3317 | |
| 3318 | int |
| 3319 | vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf, |
| 3320 | int guess) |
| 3321 | { |
| 3322 | struct namecache *ncp; |
| 3323 | struct nchandle nch; |
| 3324 | int error; |
| 3325 | |
| 3326 | *freebuf = NULL; |
| 3327 | atomic_add_int(&numfullpathcalls, 1); |
| 3328 | if (disablefullpath) |
| 3329 | return (ENODEV); |
| 3330 | |
| 3331 | if (p == NULL) |
| 3332 | return (EINVAL); |
| 3333 | |
| 3334 | /* vn is NULL, client wants us to use p->p_textvp */ |
| 3335 | if (vn == NULL) { |
| 3336 | if ((vn = p->p_textvp) == NULL) |
| 3337 | return (EINVAL); |
| 3338 | } |
| 3339 | spin_lock(&vn->v_spin); |
| 3340 | TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { |
| 3341 | if (ncp->nc_nlen) |
| 3342 | break; |
| 3343 | } |
| 3344 | if (ncp == NULL) { |
| 3345 | spin_unlock(&vn->v_spin); |
| 3346 | return (EINVAL); |
| 3347 | } |
| 3348 | _cache_hold(ncp); |
| 3349 | spin_unlock(&vn->v_spin); |
| 3350 | |
| 3351 | atomic_add_int(&numfullpathcalls, -1); |
| 3352 | nch.ncp = ncp;; |
| 3353 | nch.mount = vn->v_mount; |
| 3354 | error = cache_fullpath(p, &nch, retbuf, freebuf, guess); |
| 3355 | _cache_drop(ncp); |
| 3356 | return (error); |
| 3357 | } |