| 1 | /* |
| 2 | * Copyright (c) 2003,2004 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 | * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 |
| 69 | * $FreeBSD: src/sys/kern/vfs_cache.c,v 1.42.2.6 2001/10/05 20:07:03 dillon Exp $ |
| 70 | * $DragonFly: src/sys/kern/vfs_cache.c,v 1.91 2008/06/14 05:34:06 dillon Exp $ |
| 71 | */ |
| 72 | |
| 73 | #include <sys/param.h> |
| 74 | #include <sys/systm.h> |
| 75 | #include <sys/kernel.h> |
| 76 | #include <sys/sysctl.h> |
| 77 | #include <sys/mount.h> |
| 78 | #include <sys/vnode.h> |
| 79 | #include <sys/malloc.h> |
| 80 | #include <sys/sysproto.h> |
| 81 | #include <sys/proc.h> |
| 82 | #include <sys/namei.h> |
| 83 | #include <sys/nlookup.h> |
| 84 | #include <sys/filedesc.h> |
| 85 | #include <sys/fnv_hash.h> |
| 86 | #include <sys/globaldata.h> |
| 87 | #include <sys/kern_syscall.h> |
| 88 | #include <sys/dirent.h> |
| 89 | #include <ddb/ddb.h> |
| 90 | |
| 91 | #include <sys/sysref2.h> |
| 92 | #include <sys/mplock2.h> |
| 93 | |
| 94 | #define MAX_RECURSION_DEPTH 64 |
| 95 | |
| 96 | /* |
| 97 | * Random lookups in the cache are accomplished with a hash table using |
| 98 | * a hash key of (nc_src_vp, name). |
| 99 | * |
| 100 | * Negative entries may exist and correspond to structures where nc_vp |
| 101 | * is NULL. In a negative entry, NCF_WHITEOUT will be set if the entry |
| 102 | * corresponds to a whited-out directory entry (verses simply not finding the |
| 103 | * entry at all). |
| 104 | * |
| 105 | * Upon reaching the last segment of a path, if the reference is for DELETE, |
| 106 | * or NOCACHE is set (rewrite), and the name is located in the cache, it |
| 107 | * will be dropped. |
| 108 | */ |
| 109 | |
| 110 | /* |
| 111 | * Structures associated with name cacheing. |
| 112 | */ |
| 113 | #define NCHHASH(hash) (&nchashtbl[(hash) & nchash]) |
| 114 | #define MINNEG 1024 |
| 115 | |
| 116 | MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); |
| 117 | |
| 118 | static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ |
| 119 | static struct namecache_list ncneglist; /* instead of vnode */ |
| 120 | |
| 121 | /* |
| 122 | * ncvp_debug - debug cache_fromvp(). This is used by the NFS server |
| 123 | * to create the namecache infrastructure leading to a dangling vnode. |
| 124 | * |
| 125 | * 0 Only errors are reported |
| 126 | * 1 Successes are reported |
| 127 | * 2 Successes + the whole directory scan is reported |
| 128 | * 3 Force the directory scan code run as if the parent vnode did not |
| 129 | * have a namecache record, even if it does have one. |
| 130 | */ |
| 131 | static int ncvp_debug; |
| 132 | SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, ""); |
| 133 | |
| 134 | static u_long nchash; /* size of hash table */ |
| 135 | SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); |
| 136 | |
| 137 | static u_long ncnegfactor = 16; /* ratio of negative entries */ |
| 138 | SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); |
| 139 | |
| 140 | static int nclockwarn; /* warn on locked entries in ticks */ |
| 141 | SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, ""); |
| 142 | |
| 143 | static u_long numneg; /* number of cache entries allocated */ |
| 144 | SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); |
| 145 | |
| 146 | static u_long numcache; /* number of cache entries allocated */ |
| 147 | SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); |
| 148 | |
| 149 | static u_long numunres; /* number of unresolved entries */ |
| 150 | SYSCTL_ULONG(_debug, OID_AUTO, numunres, CTLFLAG_RD, &numunres, 0, ""); |
| 151 | |
| 152 | SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); |
| 153 | SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); |
| 154 | |
| 155 | static int cache_resolve_mp(struct mount *mp); |
| 156 | static struct vnode *cache_dvpref(struct namecache *ncp); |
| 157 | static void _cache_rehash(struct namecache *ncp); |
| 158 | static void _cache_lock(struct namecache *ncp); |
| 159 | static void _cache_setunresolved(struct namecache *ncp); |
| 160 | |
| 161 | /* |
| 162 | * The new name cache statistics |
| 163 | */ |
| 164 | SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); |
| 165 | #define STATNODE(mode, name, var) \ |
| 166 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); |
| 167 | STATNODE(CTLFLAG_RD, numneg, &numneg); |
| 168 | STATNODE(CTLFLAG_RD, numcache, &numcache); |
| 169 | static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); |
| 170 | static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); |
| 171 | static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); |
| 172 | static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); |
| 173 | static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); |
| 174 | static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); |
| 175 | static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); |
| 176 | static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); |
| 177 | static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); |
| 178 | static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); |
| 179 | |
| 180 | struct nchstats nchstats[SMP_MAXCPU]; |
| 181 | /* |
| 182 | * Export VFS cache effectiveness statistics to user-land. |
| 183 | * |
| 184 | * The statistics are left for aggregation to user-land so |
| 185 | * neat things can be achieved, like observing per-CPU cache |
| 186 | * distribution. |
| 187 | */ |
| 188 | static int |
| 189 | sysctl_nchstats(SYSCTL_HANDLER_ARGS) |
| 190 | { |
| 191 | struct globaldata *gd; |
| 192 | int i, error; |
| 193 | |
| 194 | error = 0; |
| 195 | for (i = 0; i < ncpus; ++i) { |
| 196 | gd = globaldata_find(i); |
| 197 | if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats), |
| 198 | sizeof(struct nchstats)))) |
| 199 | break; |
| 200 | } |
| 201 | |
| 202 | return (error); |
| 203 | } |
| 204 | SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD, |
| 205 | 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics"); |
| 206 | |
| 207 | static void cache_zap(struct namecache *ncp); |
| 208 | |
| 209 | /* |
| 210 | * cache_hold() and cache_drop() prevent the premature deletion of a |
| 211 | * namecache entry but do not prevent operations (such as zapping) on |
| 212 | * that namecache entry. |
| 213 | * |
| 214 | * This routine may only be called from outside this source module if |
| 215 | * nc_refs is already at least 1. |
| 216 | * |
| 217 | * This is a rare case where callers are allowed to hold a spinlock, |
| 218 | * so we can't ourselves. |
| 219 | * |
| 220 | * MPSAFE |
| 221 | */ |
| 222 | static __inline |
| 223 | struct namecache * |
| 224 | _cache_hold(struct namecache *ncp) |
| 225 | { |
| 226 | atomic_add_int(&ncp->nc_refs, 1); |
| 227 | return(ncp); |
| 228 | } |
| 229 | |
| 230 | /* |
| 231 | * When dropping an entry, if only one ref remains and the entry has not |
| 232 | * been resolved, zap it. Since the one reference is being dropped the |
| 233 | * entry had better not be locked. |
| 234 | */ |
| 235 | static __inline |
| 236 | void |
| 237 | _cache_drop(struct namecache *ncp) |
| 238 | { |
| 239 | KKASSERT(ncp->nc_refs > 0); |
| 240 | if (ncp->nc_refs == 1 && |
| 241 | (ncp->nc_flag & NCF_UNRESOLVED) && |
| 242 | TAILQ_EMPTY(&ncp->nc_list) |
| 243 | ) { |
| 244 | KKASSERT(ncp->nc_exlocks == 0); |
| 245 | _cache_lock(ncp); |
| 246 | cache_zap(ncp); |
| 247 | } else { |
| 248 | atomic_subtract_int(&ncp->nc_refs, 1); |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | /* |
| 253 | * Link a new namecache entry to its parent. Be careful to avoid races |
| 254 | * if vhold() blocks in the future. |
| 255 | */ |
| 256 | static void |
| 257 | cache_link_parent(struct namecache *ncp, struct namecache *par) |
| 258 | { |
| 259 | KKASSERT(ncp->nc_parent == NULL); |
| 260 | ncp->nc_parent = par; |
| 261 | if (TAILQ_EMPTY(&par->nc_list)) { |
| 262 | TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); |
| 263 | /* |
| 264 | * Any vp associated with an ncp which has children must |
| 265 | * be held to prevent it from being recycled. |
| 266 | */ |
| 267 | if (par->nc_vp) |
| 268 | vhold(par->nc_vp); |
| 269 | } else { |
| 270 | TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); |
| 271 | } |
| 272 | } |
| 273 | |
| 274 | /* |
| 275 | * Remove the parent association from a namecache structure. If this is |
| 276 | * the last child of the parent the cache_drop(par) will attempt to |
| 277 | * recursively zap the parent. |
| 278 | */ |
| 279 | static void |
| 280 | cache_unlink_parent(struct namecache *ncp) |
| 281 | { |
| 282 | struct namecache *par; |
| 283 | |
| 284 | if ((par = ncp->nc_parent) != NULL) { |
| 285 | ncp->nc_parent = NULL; |
| 286 | par = _cache_hold(par); |
| 287 | TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); |
| 288 | if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) |
| 289 | vdrop(par->nc_vp); |
| 290 | _cache_drop(par); |
| 291 | } |
| 292 | } |
| 293 | |
| 294 | /* |
| 295 | * Allocate a new namecache structure. Most of the code does not require |
| 296 | * zero-termination of the string but it makes vop_compat_ncreate() easier. |
| 297 | */ |
| 298 | static struct namecache * |
| 299 | cache_alloc(int nlen) |
| 300 | { |
| 301 | struct namecache *ncp; |
| 302 | |
| 303 | ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); |
| 304 | if (nlen) |
| 305 | ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK); |
| 306 | ncp->nc_nlen = nlen; |
| 307 | ncp->nc_flag = NCF_UNRESOLVED; |
| 308 | ncp->nc_error = ENOTCONN; /* needs to be resolved */ |
| 309 | ncp->nc_refs = 1; |
| 310 | |
| 311 | /* |
| 312 | * Construct a fake FSMID based on the time of day and a 32 bit |
| 313 | * roller for uniqueness. This is used to generate a useful |
| 314 | * FSMID for filesystems which do not support it. |
| 315 | */ |
| 316 | ncp->nc_fsmid = cache_getnewfsmid(); |
| 317 | TAILQ_INIT(&ncp->nc_list); |
| 318 | _cache_lock(ncp); |
| 319 | return(ncp); |
| 320 | } |
| 321 | |
| 322 | static void |
| 323 | _cache_free(struct namecache *ncp) |
| 324 | { |
| 325 | KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); |
| 326 | if (ncp->nc_name) |
| 327 | kfree(ncp->nc_name, M_VFSCACHE); |
| 328 | kfree(ncp, M_VFSCACHE); |
| 329 | } |
| 330 | |
| 331 | void |
| 332 | cache_zero(struct nchandle *nch) |
| 333 | { |
| 334 | nch->ncp = NULL; |
| 335 | nch->mount = NULL; |
| 336 | } |
| 337 | |
| 338 | /* |
| 339 | * Ref and deref a namecache structure. |
| 340 | * |
| 341 | * Warning: caller may hold an unrelated read spinlock, which means we can't |
| 342 | * use read spinlocks here. |
| 343 | * |
| 344 | * MPSAFE if nch is |
| 345 | */ |
| 346 | struct nchandle * |
| 347 | cache_hold(struct nchandle *nch) |
| 348 | { |
| 349 | _cache_hold(nch->ncp); |
| 350 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 351 | return(nch); |
| 352 | } |
| 353 | |
| 354 | /* |
| 355 | * Create a copy of a namecache handle for an already-referenced |
| 356 | * entry. |
| 357 | * |
| 358 | * MPSAFE if nch is |
| 359 | */ |
| 360 | void |
| 361 | cache_copy(struct nchandle *nch, struct nchandle *target) |
| 362 | { |
| 363 | *target = *nch; |
| 364 | _cache_hold(target->ncp); |
| 365 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 366 | } |
| 367 | |
| 368 | /* |
| 369 | * MPSAFE if nch is |
| 370 | */ |
| 371 | void |
| 372 | cache_changemount(struct nchandle *nch, struct mount *mp) |
| 373 | { |
| 374 | atomic_add_int(&nch->mount->mnt_refs, -1); |
| 375 | nch->mount = mp; |
| 376 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 377 | } |
| 378 | |
| 379 | void |
| 380 | cache_drop(struct nchandle *nch) |
| 381 | { |
| 382 | atomic_add_int(&nch->mount->mnt_refs, -1); |
| 383 | _cache_drop(nch->ncp); |
| 384 | nch->ncp = NULL; |
| 385 | nch->mount = NULL; |
| 386 | } |
| 387 | |
| 388 | /* |
| 389 | * Namespace locking. The caller must already hold a reference to the |
| 390 | * namecache structure in order to lock/unlock it. This function prevents |
| 391 | * the namespace from being created or destroyed by accessors other then |
| 392 | * the lock holder. |
| 393 | * |
| 394 | * Note that holding a locked namecache structure prevents other threads |
| 395 | * from making namespace changes (e.g. deleting or creating), prevents |
| 396 | * vnode association state changes by other threads, and prevents the |
| 397 | * namecache entry from being resolved or unresolved by other threads. |
| 398 | * |
| 399 | * The lock owner has full authority to associate/disassociate vnodes |
| 400 | * and resolve/unresolve the locked ncp. |
| 401 | * |
| 402 | * WARNING! Holding a locked ncp will prevent a vnode from being destroyed |
| 403 | * or recycled, but it does NOT help you if the vnode had already initiated |
| 404 | * a recyclement. If this is important, use cache_get() rather then |
| 405 | * cache_lock() (and deal with the differences in the way the refs counter |
| 406 | * is handled). Or, alternatively, make an unconditional call to |
| 407 | * cache_validate() or cache_resolve() after cache_lock() returns. |
| 408 | */ |
| 409 | static |
| 410 | void |
| 411 | _cache_lock(struct namecache *ncp) |
| 412 | { |
| 413 | thread_t td; |
| 414 | int didwarn; |
| 415 | |
| 416 | KKASSERT(ncp->nc_refs != 0); |
| 417 | didwarn = 0; |
| 418 | td = curthread; |
| 419 | |
| 420 | for (;;) { |
| 421 | if (ncp->nc_exlocks == 0) { |
| 422 | ncp->nc_exlocks = 1; |
| 423 | ncp->nc_locktd = td; |
| 424 | /* |
| 425 | * The vp associated with a locked ncp must be held |
| 426 | * to prevent it from being recycled (which would |
| 427 | * cause the ncp to become unresolved). |
| 428 | * |
| 429 | * WARNING! If VRECLAIMED is set the vnode could |
| 430 | * already be in the middle of a recycle. Callers |
| 431 | * should not assume that nc_vp is usable when |
| 432 | * not NULL. cache_vref() or cache_vget() must be |
| 433 | * called. |
| 434 | * |
| 435 | * XXX loop on race for later MPSAFE work. |
| 436 | */ |
| 437 | if (ncp->nc_vp) |
| 438 | vhold(ncp->nc_vp); |
| 439 | break; |
| 440 | } |
| 441 | if (ncp->nc_locktd == td) { |
| 442 | ++ncp->nc_exlocks; |
| 443 | break; |
| 444 | } |
| 445 | ncp->nc_flag |= NCF_LOCKREQ; |
| 446 | if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) { |
| 447 | if (didwarn) |
| 448 | continue; |
| 449 | didwarn = 1; |
| 450 | kprintf("[diagnostic] cache_lock: blocked on %p", ncp); |
| 451 | kprintf(" \"%*.*s\"\n", |
| 452 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 453 | } |
| 454 | } |
| 455 | |
| 456 | if (didwarn == 1) { |
| 457 | kprintf("[diagnostic] cache_lock: unblocked %*.*s\n", |
| 458 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 459 | } |
| 460 | } |
| 461 | |
| 462 | void |
| 463 | cache_lock(struct nchandle *nch) |
| 464 | { |
| 465 | _cache_lock(nch->ncp); |
| 466 | } |
| 467 | |
| 468 | static |
| 469 | int |
| 470 | _cache_lock_nonblock(struct namecache *ncp) |
| 471 | { |
| 472 | thread_t td; |
| 473 | |
| 474 | KKASSERT(ncp->nc_refs != 0); |
| 475 | td = curthread; |
| 476 | if (ncp->nc_exlocks == 0) { |
| 477 | ncp->nc_exlocks = 1; |
| 478 | ncp->nc_locktd = td; |
| 479 | /* |
| 480 | * The vp associated with a locked ncp must be held |
| 481 | * to prevent it from being recycled (which would |
| 482 | * cause the ncp to become unresolved). |
| 483 | * |
| 484 | * WARNING! If VRECLAIMED is set the vnode could |
| 485 | * already be in the middle of a recycle. Callers |
| 486 | * should not assume that nc_vp is usable when |
| 487 | * not NULL. cache_vref() or cache_vget() must be |
| 488 | * called. |
| 489 | * |
| 490 | * XXX loop on race for later MPSAFE work. |
| 491 | */ |
| 492 | if (ncp->nc_vp) |
| 493 | vhold(ncp->nc_vp); |
| 494 | return(0); |
| 495 | } else { |
| 496 | return(EWOULDBLOCK); |
| 497 | } |
| 498 | } |
| 499 | |
| 500 | int |
| 501 | cache_lock_nonblock(struct nchandle *nch) |
| 502 | { |
| 503 | return(_cache_lock_nonblock(nch->ncp)); |
| 504 | } |
| 505 | |
| 506 | static |
| 507 | void |
| 508 | _cache_unlock(struct namecache *ncp) |
| 509 | { |
| 510 | thread_t td __debugvar = curthread; |
| 511 | |
| 512 | KKASSERT(ncp->nc_refs > 0); |
| 513 | KKASSERT(ncp->nc_exlocks > 0); |
| 514 | KKASSERT(ncp->nc_locktd == td); |
| 515 | if (--ncp->nc_exlocks == 0) { |
| 516 | if (ncp->nc_vp) |
| 517 | vdrop(ncp->nc_vp); |
| 518 | ncp->nc_locktd = NULL; |
| 519 | if (ncp->nc_flag & NCF_LOCKREQ) { |
| 520 | ncp->nc_flag &= ~NCF_LOCKREQ; |
| 521 | wakeup(ncp); |
| 522 | } |
| 523 | } |
| 524 | } |
| 525 | |
| 526 | void |
| 527 | cache_unlock(struct nchandle *nch) |
| 528 | { |
| 529 | _cache_unlock(nch->ncp); |
| 530 | } |
| 531 | |
| 532 | /* |
| 533 | * ref-and-lock, unlock-and-deref functions. |
| 534 | * |
| 535 | * This function is primarily used by nlookup. Even though cache_lock |
| 536 | * holds the vnode, it is possible that the vnode may have already |
| 537 | * initiated a recyclement. We want cache_get() to return a definitively |
| 538 | * usable vnode or a definitively unresolved ncp. |
| 539 | */ |
| 540 | static |
| 541 | struct namecache * |
| 542 | _cache_get(struct namecache *ncp) |
| 543 | { |
| 544 | _cache_hold(ncp); |
| 545 | _cache_lock(ncp); |
| 546 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 547 | _cache_setunresolved(ncp); |
| 548 | return(ncp); |
| 549 | } |
| 550 | |
| 551 | /* |
| 552 | * note: the same nchandle can be passed for both arguments. |
| 553 | */ |
| 554 | void |
| 555 | cache_get(struct nchandle *nch, struct nchandle *target) |
| 556 | { |
| 557 | target->mount = nch->mount; |
| 558 | target->ncp = _cache_get(nch->ncp); |
| 559 | atomic_add_int(&target->mount->mnt_refs, 1); |
| 560 | } |
| 561 | |
| 562 | static int |
| 563 | _cache_get_nonblock(struct namecache *ncp) |
| 564 | { |
| 565 | /* XXX MP */ |
| 566 | if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) { |
| 567 | _cache_hold(ncp); |
| 568 | _cache_lock(ncp); |
| 569 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 570 | _cache_setunresolved(ncp); |
| 571 | return(0); |
| 572 | } |
| 573 | return(EWOULDBLOCK); |
| 574 | } |
| 575 | |
| 576 | int |
| 577 | cache_get_nonblock(struct nchandle *nch) |
| 578 | { |
| 579 | int error; |
| 580 | |
| 581 | if ((error = _cache_get_nonblock(nch->ncp)) == 0) |
| 582 | atomic_add_int(&nch->mount->mnt_refs, 1); |
| 583 | return (error); |
| 584 | } |
| 585 | |
| 586 | static __inline |
| 587 | void |
| 588 | _cache_put(struct namecache *ncp) |
| 589 | { |
| 590 | _cache_unlock(ncp); |
| 591 | _cache_drop(ncp); |
| 592 | } |
| 593 | |
| 594 | void |
| 595 | cache_put(struct nchandle *nch) |
| 596 | { |
| 597 | atomic_add_int(&nch->mount->mnt_refs, -1); |
| 598 | _cache_put(nch->ncp); |
| 599 | nch->ncp = NULL; |
| 600 | nch->mount = NULL; |
| 601 | } |
| 602 | |
| 603 | /* |
| 604 | * Resolve an unresolved ncp by associating a vnode with it. If the |
| 605 | * vnode is NULL, a negative cache entry is created. |
| 606 | * |
| 607 | * The ncp should be locked on entry and will remain locked on return. |
| 608 | */ |
| 609 | static |
| 610 | void |
| 611 | _cache_setvp(struct mount *mp, struct namecache *ncp, struct vnode *vp) |
| 612 | { |
| 613 | KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); |
| 614 | ncp->nc_vp = vp; |
| 615 | if (vp != NULL) { |
| 616 | /* |
| 617 | * Any vp associated with an ncp which has children must |
| 618 | * be held. Any vp associated with a locked ncp must be held. |
| 619 | */ |
| 620 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 621 | vhold(vp); |
| 622 | TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); |
| 623 | if (ncp->nc_exlocks) |
| 624 | vhold(vp); |
| 625 | |
| 626 | /* |
| 627 | * Set auxiliary flags |
| 628 | */ |
| 629 | switch(vp->v_type) { |
| 630 | case VDIR: |
| 631 | ncp->nc_flag |= NCF_ISDIR; |
| 632 | break; |
| 633 | case VLNK: |
| 634 | ncp->nc_flag |= NCF_ISSYMLINK; |
| 635 | /* XXX cache the contents of the symlink */ |
| 636 | break; |
| 637 | default: |
| 638 | break; |
| 639 | } |
| 640 | ++numcache; |
| 641 | ncp->nc_error = 0; |
| 642 | } else { |
| 643 | /* |
| 644 | * When creating a negative cache hit we set the |
| 645 | * namecache_gen. A later resolve will clean out the |
| 646 | * negative cache hit if the mount point's namecache_gen |
| 647 | * has changed. Used by devfs, could also be used by |
| 648 | * other remote FSs. |
| 649 | */ |
| 650 | TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); |
| 651 | ++numneg; |
| 652 | ncp->nc_error = ENOENT; |
| 653 | if (mp) |
| 654 | ncp->nc_namecache_gen = mp->mnt_namecache_gen; |
| 655 | } |
| 656 | ncp->nc_flag &= ~NCF_UNRESOLVED; |
| 657 | } |
| 658 | |
| 659 | void |
| 660 | cache_setvp(struct nchandle *nch, struct vnode *vp) |
| 661 | { |
| 662 | _cache_setvp(nch->mount, nch->ncp, vp); |
| 663 | } |
| 664 | |
| 665 | void |
| 666 | cache_settimeout(struct nchandle *nch, int nticks) |
| 667 | { |
| 668 | struct namecache *ncp = nch->ncp; |
| 669 | |
| 670 | if ((ncp->nc_timeout = ticks + nticks) == 0) |
| 671 | ncp->nc_timeout = 1; |
| 672 | } |
| 673 | |
| 674 | /* |
| 675 | * Disassociate the vnode or negative-cache association and mark a |
| 676 | * namecache entry as unresolved again. Note that the ncp is still |
| 677 | * left in the hash table and still linked to its parent. |
| 678 | * |
| 679 | * The ncp should be locked and refd on entry and will remain locked and refd |
| 680 | * on return. |
| 681 | * |
| 682 | * This routine is normally never called on a directory containing children. |
| 683 | * However, NFS often does just that in its rename() code as a cop-out to |
| 684 | * avoid complex namespace operations. This disconnects a directory vnode |
| 685 | * from its namecache and can cause the OLDAPI and NEWAPI to get out of |
| 686 | * sync. |
| 687 | * |
| 688 | * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as |
| 689 | * in a create, properly propogates flag up the chain. |
| 690 | */ |
| 691 | static |
| 692 | void |
| 693 | _cache_setunresolved(struct namecache *ncp) |
| 694 | { |
| 695 | struct vnode *vp; |
| 696 | |
| 697 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 698 | ncp->nc_flag |= NCF_UNRESOLVED; |
| 699 | ncp->nc_timeout = 0; |
| 700 | ncp->nc_error = ENOTCONN; |
| 701 | ++numunres; |
| 702 | if ((vp = ncp->nc_vp) != NULL) { |
| 703 | --numcache; |
| 704 | ncp->nc_vp = NULL; |
| 705 | TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); |
| 706 | |
| 707 | /* |
| 708 | * Any vp associated with an ncp with children is |
| 709 | * held by that ncp. Any vp associated with a locked |
| 710 | * ncp is held by that ncp. These conditions must be |
| 711 | * undone when the vp is cleared out from the ncp. |
| 712 | */ |
| 713 | if (ncp->nc_flag & NCF_FSMID) |
| 714 | vupdatefsmid(vp); |
| 715 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 716 | vdrop(vp); |
| 717 | if (ncp->nc_exlocks) |
| 718 | vdrop(vp); |
| 719 | } else { |
| 720 | TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); |
| 721 | --numneg; |
| 722 | } |
| 723 | ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK| |
| 724 | NCF_FSMID); |
| 725 | } |
| 726 | } |
| 727 | |
| 728 | /* |
| 729 | * The cache_nresolve() code calls this function to automatically |
| 730 | * set a resolved cache element to unresolved if it has timed out |
| 731 | * or if it is a negative cache hit and the mount point namecache_gen |
| 732 | * has changed. |
| 733 | */ |
| 734 | static __inline void |
| 735 | _cache_auto_unresolve(struct mount *mp, struct namecache *ncp) |
| 736 | { |
| 737 | /* |
| 738 | * Already in an unresolved state, nothing to do. |
| 739 | */ |
| 740 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 741 | return; |
| 742 | |
| 743 | /* |
| 744 | * Try to zap entries that have timed out. We have |
| 745 | * to be careful here because locked leafs may depend |
| 746 | * on the vnode remaining intact in a parent, so only |
| 747 | * do this under very specific conditions. |
| 748 | */ |
| 749 | if (ncp->nc_timeout && (int)(ncp->nc_timeout - ticks) < 0 && |
| 750 | TAILQ_EMPTY(&ncp->nc_list)) { |
| 751 | _cache_setunresolved(ncp); |
| 752 | return; |
| 753 | } |
| 754 | |
| 755 | /* |
| 756 | * If a resolved negative cache hit is invalid due to |
| 757 | * the mount's namecache generation being bumped, zap it. |
| 758 | */ |
| 759 | if (ncp->nc_vp == NULL && |
| 760 | ncp->nc_namecache_gen != mp->mnt_namecache_gen) { |
| 761 | _cache_setunresolved(ncp); |
| 762 | return; |
| 763 | } |
| 764 | } |
| 765 | |
| 766 | void |
| 767 | cache_setunresolved(struct nchandle *nch) |
| 768 | { |
| 769 | _cache_setunresolved(nch->ncp); |
| 770 | } |
| 771 | |
| 772 | /* |
| 773 | * Determine if we can clear NCF_ISMOUNTPT by scanning the mountlist |
| 774 | * looking for matches. This flag tells the lookup code when it must |
| 775 | * check for a mount linkage and also prevents the directories in question |
| 776 | * from being deleted or renamed. |
| 777 | */ |
| 778 | static |
| 779 | int |
| 780 | cache_clrmountpt_callback(struct mount *mp, void *data) |
| 781 | { |
| 782 | struct nchandle *nch = data; |
| 783 | |
| 784 | if (mp->mnt_ncmounton.ncp == nch->ncp) |
| 785 | return(1); |
| 786 | if (mp->mnt_ncmountpt.ncp == nch->ncp) |
| 787 | return(1); |
| 788 | return(0); |
| 789 | } |
| 790 | |
| 791 | void |
| 792 | cache_clrmountpt(struct nchandle *nch) |
| 793 | { |
| 794 | int count; |
| 795 | |
| 796 | count = mountlist_scan(cache_clrmountpt_callback, nch, |
| 797 | MNTSCAN_FORWARD|MNTSCAN_NOBUSY); |
| 798 | if (count == 0) |
| 799 | nch->ncp->nc_flag &= ~NCF_ISMOUNTPT; |
| 800 | } |
| 801 | |
| 802 | /* |
| 803 | * Invalidate portions of the namecache topology given a starting entry. |
| 804 | * The passed ncp is set to an unresolved state and: |
| 805 | * |
| 806 | * The passed ncp must be locked. |
| 807 | * |
| 808 | * CINV_DESTROY - Set a flag in the passed ncp entry indicating |
| 809 | * that the physical underlying nodes have been |
| 810 | * destroyed... as in deleted. For example, when |
| 811 | * a directory is removed. This will cause record |
| 812 | * lookups on the name to no longer be able to find |
| 813 | * the record and tells the resolver to return failure |
| 814 | * rather then trying to resolve through the parent. |
| 815 | * |
| 816 | * The topology itself, including ncp->nc_name, |
| 817 | * remains intact. |
| 818 | * |
| 819 | * This only applies to the passed ncp, if CINV_CHILDREN |
| 820 | * is specified the children are not flagged. |
| 821 | * |
| 822 | * CINV_CHILDREN - Set all children (recursively) to an unresolved |
| 823 | * state as well. |
| 824 | * |
| 825 | * Note that this will also have the side effect of |
| 826 | * cleaning out any unreferenced nodes in the topology |
| 827 | * from the leaves up as the recursion backs out. |
| 828 | * |
| 829 | * Note that the topology for any referenced nodes remains intact. |
| 830 | * |
| 831 | * It is possible for cache_inval() to race a cache_resolve(), meaning that |
| 832 | * the namecache entry may not actually be invalidated on return if it was |
| 833 | * revalidated while recursing down into its children. This code guarentees |
| 834 | * that the node(s) will go through an invalidation cycle, but does not |
| 835 | * guarentee that they will remain in an invalidated state. |
| 836 | * |
| 837 | * Returns non-zero if a revalidation was detected during the invalidation |
| 838 | * recursion, zero otherwise. Note that since only the original ncp is |
| 839 | * locked the revalidation ultimately can only indicate that the original ncp |
| 840 | * *MIGHT* no have been reresolved. |
| 841 | * |
| 842 | * DEEP RECURSION HANDLING - If a recursive invalidation recurses deeply we |
| 843 | * have to avoid blowing out the kernel stack. We do this by saving the |
| 844 | * deep namecache node and aborting the recursion, then re-recursing at that |
| 845 | * node using a depth-first algorithm in order to allow multiple deep |
| 846 | * recursions to chain through each other, then we restart the invalidation |
| 847 | * from scratch. |
| 848 | */ |
| 849 | |
| 850 | struct cinvtrack { |
| 851 | struct namecache *resume_ncp; |
| 852 | int depth; |
| 853 | }; |
| 854 | |
| 855 | static int _cache_inval_internal(struct namecache *, int, struct cinvtrack *); |
| 856 | |
| 857 | static |
| 858 | int |
| 859 | _cache_inval(struct namecache *ncp, int flags) |
| 860 | { |
| 861 | struct cinvtrack track; |
| 862 | struct namecache *ncp2; |
| 863 | int r; |
| 864 | |
| 865 | track.depth = 0; |
| 866 | track.resume_ncp = NULL; |
| 867 | |
| 868 | for (;;) { |
| 869 | r = _cache_inval_internal(ncp, flags, &track); |
| 870 | if (track.resume_ncp == NULL) |
| 871 | break; |
| 872 | kprintf("Warning: deep namecache recursion at %s\n", |
| 873 | ncp->nc_name); |
| 874 | _cache_unlock(ncp); |
| 875 | while ((ncp2 = track.resume_ncp) != NULL) { |
| 876 | track.resume_ncp = NULL; |
| 877 | _cache_lock(ncp2); |
| 878 | _cache_inval_internal(ncp2, flags & ~CINV_DESTROY, |
| 879 | &track); |
| 880 | _cache_put(ncp2); |
| 881 | } |
| 882 | _cache_lock(ncp); |
| 883 | } |
| 884 | return(r); |
| 885 | } |
| 886 | |
| 887 | int |
| 888 | cache_inval(struct nchandle *nch, int flags) |
| 889 | { |
| 890 | return(_cache_inval(nch->ncp, flags)); |
| 891 | } |
| 892 | |
| 893 | static int |
| 894 | _cache_inval_internal(struct namecache *ncp, int flags, struct cinvtrack *track) |
| 895 | { |
| 896 | struct namecache *kid; |
| 897 | struct namecache *nextkid; |
| 898 | int rcnt = 0; |
| 899 | |
| 900 | KKASSERT(ncp->nc_exlocks); |
| 901 | |
| 902 | _cache_setunresolved(ncp); |
| 903 | if (flags & CINV_DESTROY) |
| 904 | ncp->nc_flag |= NCF_DESTROYED; |
| 905 | |
| 906 | if ((flags & CINV_CHILDREN) && |
| 907 | (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL |
| 908 | ) { |
| 909 | if (++track->depth > MAX_RECURSION_DEPTH) { |
| 910 | track->resume_ncp = ncp; |
| 911 | _cache_hold(ncp); |
| 912 | ++rcnt; |
| 913 | } |
| 914 | _cache_hold(kid); |
| 915 | _cache_unlock(ncp); |
| 916 | while (kid) { |
| 917 | if (track->resume_ncp) { |
| 918 | _cache_drop(kid); |
| 919 | break; |
| 920 | } |
| 921 | if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) |
| 922 | _cache_hold(nextkid); |
| 923 | if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || |
| 924 | TAILQ_FIRST(&kid->nc_list) |
| 925 | ) { |
| 926 | _cache_lock(kid); |
| 927 | rcnt += _cache_inval_internal(kid, flags & ~CINV_DESTROY, track); |
| 928 | _cache_unlock(kid); |
| 929 | } |
| 930 | _cache_drop(kid); |
| 931 | kid = nextkid; |
| 932 | } |
| 933 | --track->depth; |
| 934 | _cache_lock(ncp); |
| 935 | } |
| 936 | |
| 937 | /* |
| 938 | * Someone could have gotten in there while ncp was unlocked, |
| 939 | * retry if so. |
| 940 | */ |
| 941 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) |
| 942 | ++rcnt; |
| 943 | return (rcnt); |
| 944 | } |
| 945 | |
| 946 | /* |
| 947 | * Invalidate a vnode's namecache associations. To avoid races against |
| 948 | * the resolver we do not invalidate a node which we previously invalidated |
| 949 | * but which was then re-resolved while we were in the invalidation loop. |
| 950 | * |
| 951 | * Returns non-zero if any namecache entries remain after the invalidation |
| 952 | * loop completed. |
| 953 | * |
| 954 | * NOTE: unlike the namecache topology which guarentees that ncp's will not |
| 955 | * be ripped out of the topology while held, the vnode's v_namecache list |
| 956 | * has no such restriction. NCP's can be ripped out of the list at virtually |
| 957 | * any time if not locked, even if held. |
| 958 | */ |
| 959 | int |
| 960 | cache_inval_vp(struct vnode *vp, int flags) |
| 961 | { |
| 962 | struct namecache *ncp; |
| 963 | struct namecache *next; |
| 964 | |
| 965 | restart: |
| 966 | ncp = TAILQ_FIRST(&vp->v_namecache); |
| 967 | if (ncp) |
| 968 | _cache_hold(ncp); |
| 969 | while (ncp) { |
| 970 | /* loop entered with ncp held */ |
| 971 | if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) |
| 972 | _cache_hold(next); |
| 973 | _cache_lock(ncp); |
| 974 | if (ncp->nc_vp != vp) { |
| 975 | kprintf("Warning: cache_inval_vp: race-A detected on " |
| 976 | "%s\n", ncp->nc_name); |
| 977 | _cache_put(ncp); |
| 978 | if (next) |
| 979 | _cache_drop(next); |
| 980 | goto restart; |
| 981 | } |
| 982 | _cache_inval(ncp, flags); |
| 983 | _cache_put(ncp); /* also releases reference */ |
| 984 | ncp = next; |
| 985 | if (ncp && ncp->nc_vp != vp) { |
| 986 | kprintf("Warning: cache_inval_vp: race-B detected on " |
| 987 | "%s\n", ncp->nc_name); |
| 988 | _cache_drop(ncp); |
| 989 | goto restart; |
| 990 | } |
| 991 | } |
| 992 | return(TAILQ_FIRST(&vp->v_namecache) != NULL); |
| 993 | } |
| 994 | |
| 995 | /* |
| 996 | * This routine is used instead of the normal cache_inval_vp() when we |
| 997 | * are trying to recycle otherwise good vnodes. |
| 998 | * |
| 999 | * Return 0 on success, non-zero if not all namecache records could be |
| 1000 | * disassociated from the vnode (for various reasons). |
| 1001 | */ |
| 1002 | int |
| 1003 | cache_inval_vp_nonblock(struct vnode *vp) |
| 1004 | { |
| 1005 | struct namecache *ncp; |
| 1006 | struct namecache *next; |
| 1007 | |
| 1008 | ncp = TAILQ_FIRST(&vp->v_namecache); |
| 1009 | if (ncp) |
| 1010 | _cache_hold(ncp); |
| 1011 | while (ncp) { |
| 1012 | /* loop entered with ncp held */ |
| 1013 | if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) |
| 1014 | _cache_hold(next); |
| 1015 | if (_cache_lock_nonblock(ncp)) { |
| 1016 | _cache_drop(ncp); |
| 1017 | if (next) |
| 1018 | _cache_drop(next); |
| 1019 | break; |
| 1020 | } |
| 1021 | if (ncp->nc_vp != vp) { |
| 1022 | kprintf("Warning: cache_inval_vp: race-A detected on " |
| 1023 | "%s\n", ncp->nc_name); |
| 1024 | _cache_put(ncp); |
| 1025 | if (next) |
| 1026 | _cache_drop(next); |
| 1027 | break; |
| 1028 | } |
| 1029 | _cache_inval(ncp, 0); |
| 1030 | _cache_put(ncp); /* also releases reference */ |
| 1031 | ncp = next; |
| 1032 | if (ncp && ncp->nc_vp != vp) { |
| 1033 | kprintf("Warning: cache_inval_vp: race-B detected on " |
| 1034 | "%s\n", ncp->nc_name); |
| 1035 | _cache_drop(ncp); |
| 1036 | break; |
| 1037 | } |
| 1038 | } |
| 1039 | return(TAILQ_FIRST(&vp->v_namecache) != NULL); |
| 1040 | } |
| 1041 | |
| 1042 | /* |
| 1043 | * The source ncp has been renamed to the target ncp. Both fncp and tncp |
| 1044 | * must be locked. The target ncp is destroyed (as a normal rename-over |
| 1045 | * would destroy the target file or directory). |
| 1046 | * |
| 1047 | * Because there may be references to the source ncp we cannot copy its |
| 1048 | * contents to the target. Instead the source ncp is relinked as the target |
| 1049 | * and the target ncp is removed from the namecache topology. |
| 1050 | */ |
| 1051 | void |
| 1052 | cache_rename(struct nchandle *fnch, struct nchandle *tnch) |
| 1053 | { |
| 1054 | struct namecache *fncp = fnch->ncp; |
| 1055 | struct namecache *tncp = tnch->ncp; |
| 1056 | char *oname; |
| 1057 | |
| 1058 | _cache_setunresolved(tncp); |
| 1059 | cache_unlink_parent(fncp); |
| 1060 | cache_link_parent(fncp, tncp->nc_parent); |
| 1061 | cache_unlink_parent(tncp); |
| 1062 | oname = fncp->nc_name; |
| 1063 | fncp->nc_name = tncp->nc_name; |
| 1064 | fncp->nc_nlen = tncp->nc_nlen; |
| 1065 | tncp->nc_name = NULL; |
| 1066 | tncp->nc_nlen = 0; |
| 1067 | if (fncp->nc_flag & NCF_HASHED) |
| 1068 | _cache_rehash(fncp); |
| 1069 | if (tncp->nc_flag & NCF_HASHED) |
| 1070 | _cache_rehash(tncp); |
| 1071 | if (oname) |
| 1072 | kfree(oname, M_VFSCACHE); |
| 1073 | } |
| 1074 | |
| 1075 | /* |
| 1076 | * vget the vnode associated with the namecache entry. Resolve the namecache |
| 1077 | * entry if necessary and deal with namecache/vp races. The passed ncp must |
| 1078 | * be referenced and may be locked. The ncp's ref/locking state is not |
| 1079 | * effected by this call. |
| 1080 | * |
| 1081 | * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked |
| 1082 | * (depending on the passed lk_type) will be returned in *vpp with an error |
| 1083 | * of 0, or NULL will be returned in *vpp with a non-0 error code. The |
| 1084 | * most typical error is ENOENT, meaning that the ncp represents a negative |
| 1085 | * cache hit and there is no vnode to retrieve, but other errors can occur |
| 1086 | * too. |
| 1087 | * |
| 1088 | * The main race we have to deal with are namecache zaps. The ncp itself |
| 1089 | * will not disappear since it is referenced, and it turns out that the |
| 1090 | * validity of the vp pointer can be checked simply by rechecking the |
| 1091 | * contents of ncp->nc_vp. |
| 1092 | */ |
| 1093 | int |
| 1094 | cache_vget(struct nchandle *nch, struct ucred *cred, |
| 1095 | int lk_type, struct vnode **vpp) |
| 1096 | { |
| 1097 | struct namecache *ncp; |
| 1098 | struct vnode *vp; |
| 1099 | int error; |
| 1100 | |
| 1101 | ncp = nch->ncp; |
| 1102 | again: |
| 1103 | vp = NULL; |
| 1104 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 1105 | _cache_lock(ncp); |
| 1106 | error = cache_resolve(nch, cred); |
| 1107 | _cache_unlock(ncp); |
| 1108 | } else { |
| 1109 | error = 0; |
| 1110 | } |
| 1111 | if (error == 0 && (vp = ncp->nc_vp) != NULL) { |
| 1112 | /* |
| 1113 | * Accessing the vnode from the namecache is a bit |
| 1114 | * dangerous. Because there are no refs on the vnode, it |
| 1115 | * could be in the middle of a reclaim. |
| 1116 | */ |
| 1117 | if (vp->v_flag & VRECLAIMED) { |
| 1118 | kprintf("Warning: vnode reclaim race detected in cache_vget on %p (%s)\n", vp, ncp->nc_name); |
| 1119 | _cache_lock(ncp); |
| 1120 | _cache_setunresolved(ncp); |
| 1121 | _cache_unlock(ncp); |
| 1122 | goto again; |
| 1123 | } |
| 1124 | error = vget(vp, lk_type); |
| 1125 | if (error) { |
| 1126 | if (vp != ncp->nc_vp) |
| 1127 | goto again; |
| 1128 | vp = NULL; |
| 1129 | } else if (vp != ncp->nc_vp) { |
| 1130 | vput(vp); |
| 1131 | goto again; |
| 1132 | } else if (vp->v_flag & VRECLAIMED) { |
| 1133 | panic("vget succeeded on a VRECLAIMED node! vp %p", vp); |
| 1134 | } |
| 1135 | } |
| 1136 | if (error == 0 && vp == NULL) |
| 1137 | error = ENOENT; |
| 1138 | *vpp = vp; |
| 1139 | return(error); |
| 1140 | } |
| 1141 | |
| 1142 | int |
| 1143 | cache_vref(struct nchandle *nch, struct ucred *cred, struct vnode **vpp) |
| 1144 | { |
| 1145 | struct namecache *ncp; |
| 1146 | struct vnode *vp; |
| 1147 | int error; |
| 1148 | |
| 1149 | ncp = nch->ncp; |
| 1150 | |
| 1151 | again: |
| 1152 | vp = NULL; |
| 1153 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 1154 | _cache_lock(ncp); |
| 1155 | error = cache_resolve(nch, cred); |
| 1156 | _cache_unlock(ncp); |
| 1157 | } else { |
| 1158 | error = 0; |
| 1159 | } |
| 1160 | if (error == 0 && (vp = ncp->nc_vp) != NULL) { |
| 1161 | /* |
| 1162 | * Since we did not obtain any locks, a cache zap |
| 1163 | * race can occur here if the vnode is in the middle |
| 1164 | * of being reclaimed and has not yet been able to |
| 1165 | * clean out its cache node. If that case occurs, |
| 1166 | * we must lock and unresolve the cache, then loop |
| 1167 | * to retry. |
| 1168 | */ |
| 1169 | if ((error = vget(vp, LK_SHARED)) != 0) { |
| 1170 | if (error == ENOENT) { |
| 1171 | kprintf("Warning: vnode reclaim race detected on cache_vref %p (%s)\n", vp, ncp->nc_name); |
| 1172 | _cache_lock(ncp); |
| 1173 | _cache_setunresolved(ncp); |
| 1174 | _cache_unlock(ncp); |
| 1175 | goto again; |
| 1176 | } |
| 1177 | /* fatal error */ |
| 1178 | } else { |
| 1179 | /* caller does not want a lock */ |
| 1180 | vn_unlock(vp); |
| 1181 | } |
| 1182 | } |
| 1183 | if (error == 0 && vp == NULL) |
| 1184 | error = ENOENT; |
| 1185 | *vpp = vp; |
| 1186 | return(error); |
| 1187 | } |
| 1188 | |
| 1189 | /* |
| 1190 | * Return a referenced vnode representing the parent directory of |
| 1191 | * ncp. Because the caller has locked the ncp it should not be possible for |
| 1192 | * the parent ncp to go away. |
| 1193 | * |
| 1194 | * However, we might race against the parent dvp and not be able to |
| 1195 | * reference it. If we race, return NULL. |
| 1196 | */ |
| 1197 | static struct vnode * |
| 1198 | cache_dvpref(struct namecache *ncp) |
| 1199 | { |
| 1200 | struct namecache *par; |
| 1201 | struct vnode *dvp; |
| 1202 | |
| 1203 | dvp = NULL; |
| 1204 | if ((par = ncp->nc_parent) != NULL) { |
| 1205 | if ((par->nc_flag & NCF_UNRESOLVED) == 0) { |
| 1206 | if ((dvp = par->nc_vp) != NULL) { |
| 1207 | if (vget(dvp, LK_SHARED) == 0) { |
| 1208 | vn_unlock(dvp); |
| 1209 | /* return referenced, unlocked dvp */ |
| 1210 | } else { |
| 1211 | dvp = NULL; |
| 1212 | } |
| 1213 | } |
| 1214 | } |
| 1215 | } |
| 1216 | return(dvp); |
| 1217 | } |
| 1218 | |
| 1219 | /* |
| 1220 | * Recursively set the FSMID update flag for namecache nodes leading |
| 1221 | * to root. This will cause the next getattr or reclaim to increment the |
| 1222 | * fsmid and mark the inode for lazy updating. |
| 1223 | * |
| 1224 | * Stop recursing when we hit a node whos NCF_FSMID flag is already set. |
| 1225 | * This makes FSMIDs work in an Einsteinian fashion - where the observation |
| 1226 | * effects the result. In this case a program monitoring a higher level |
| 1227 | * node will have detected some prior change and started its scan (clearing |
| 1228 | * NCF_FSMID in higher level nodes), but since it has not yet observed the |
| 1229 | * node where we find NCF_FSMID still set, we can safely make the related |
| 1230 | * modification without interfering with the theorized program. |
| 1231 | * |
| 1232 | * This also means that FSMIDs cannot represent time-domain quantities |
| 1233 | * in a hierarchical sense. But the main reason for doing it this way |
| 1234 | * is to reduce the amount of recursion that occurs in the critical path |
| 1235 | * when e.g. a program is writing to a file that sits deep in a directory |
| 1236 | * hierarchy. |
| 1237 | */ |
| 1238 | void |
| 1239 | cache_update_fsmid(struct nchandle *nch) |
| 1240 | { |
| 1241 | struct namecache *ncp; |
| 1242 | struct namecache *scan; |
| 1243 | struct vnode *vp; |
| 1244 | |
| 1245 | ncp = nch->ncp; |
| 1246 | |
| 1247 | /* |
| 1248 | * Warning: even if we get a non-NULL vp it could still be in the |
| 1249 | * middle of a recyclement. Don't do anything fancy, just set |
| 1250 | * NCF_FSMID. |
| 1251 | */ |
| 1252 | if ((vp = ncp->nc_vp) != NULL) { |
| 1253 | TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { |
| 1254 | for (scan = ncp; scan; scan = scan->nc_parent) { |
| 1255 | if (scan->nc_flag & NCF_FSMID) |
| 1256 | break; |
| 1257 | scan->nc_flag |= NCF_FSMID; |
| 1258 | } |
| 1259 | } |
| 1260 | } else { |
| 1261 | while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) { |
| 1262 | ncp->nc_flag |= NCF_FSMID; |
| 1263 | ncp = ncp->nc_parent; |
| 1264 | } |
| 1265 | } |
| 1266 | } |
| 1267 | |
| 1268 | void |
| 1269 | cache_update_fsmid_vp(struct vnode *vp) |
| 1270 | { |
| 1271 | struct namecache *ncp; |
| 1272 | struct namecache *scan; |
| 1273 | |
| 1274 | TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { |
| 1275 | for (scan = ncp; scan; scan = scan->nc_parent) { |
| 1276 | if (scan->nc_flag & NCF_FSMID) |
| 1277 | break; |
| 1278 | scan->nc_flag |= NCF_FSMID; |
| 1279 | } |
| 1280 | } |
| 1281 | } |
| 1282 | |
| 1283 | /* |
| 1284 | * If getattr is called on a vnode (e.g. a stat call), the filesystem |
| 1285 | * may call this routine to determine if the namecache has the hierarchical |
| 1286 | * change flag set, requiring the fsmid to be updated. |
| 1287 | * |
| 1288 | * Since 0 indicates no support, make sure the filesystem fsmid is at least |
| 1289 | * 1. |
| 1290 | */ |
| 1291 | int |
| 1292 | cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid) |
| 1293 | { |
| 1294 | struct namecache *ncp; |
| 1295 | int changed = 0; |
| 1296 | |
| 1297 | TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { |
| 1298 | if (ncp->nc_flag & NCF_FSMID) { |
| 1299 | ncp->nc_flag &= ~NCF_FSMID; |
| 1300 | changed = 1; |
| 1301 | } |
| 1302 | } |
| 1303 | if (*fsmid == 0) |
| 1304 | ++*fsmid; |
| 1305 | if (changed) |
| 1306 | ++*fsmid; |
| 1307 | return(changed); |
| 1308 | } |
| 1309 | |
| 1310 | /* |
| 1311 | * Obtain the FSMID for a vnode for filesystems which do not support |
| 1312 | * a built-in FSMID. |
| 1313 | */ |
| 1314 | int64_t |
| 1315 | cache_sync_fsmid_vp(struct vnode *vp) |
| 1316 | { |
| 1317 | struct namecache *ncp; |
| 1318 | |
| 1319 | if ((ncp = TAILQ_FIRST(&vp->v_namecache)) != NULL) { |
| 1320 | if (ncp->nc_flag & NCF_FSMID) { |
| 1321 | ncp->nc_flag &= ~NCF_FSMID; |
| 1322 | ++ncp->nc_fsmid; |
| 1323 | } |
| 1324 | return(ncp->nc_fsmid); |
| 1325 | } |
| 1326 | return(VNOVAL); |
| 1327 | } |
| 1328 | |
| 1329 | /* |
| 1330 | * Convert a directory vnode to a namecache record without any other |
| 1331 | * knowledge of the topology. This ONLY works with directory vnodes and |
| 1332 | * is ONLY used by the NFS server. dvp must be refd but unlocked, and the |
| 1333 | * returned ncp (if not NULL) will be held and unlocked. |
| 1334 | * |
| 1335 | * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. |
| 1336 | * If 'makeit' is 1 we attempt to track-down and create the namecache topology |
| 1337 | * for dvp. This will fail only if the directory has been deleted out from |
| 1338 | * under the caller. |
| 1339 | * |
| 1340 | * Callers must always check for a NULL return no matter the value of 'makeit'. |
| 1341 | * |
| 1342 | * To avoid underflowing the kernel stack each recursive call increments |
| 1343 | * the makeit variable. |
| 1344 | */ |
| 1345 | |
| 1346 | static int cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, |
| 1347 | struct vnode *dvp, char *fakename); |
| 1348 | static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, |
| 1349 | struct vnode **saved_dvp); |
| 1350 | |
| 1351 | int |
| 1352 | cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit, |
| 1353 | struct nchandle *nch) |
| 1354 | { |
| 1355 | struct vnode *saved_dvp; |
| 1356 | struct vnode *pvp; |
| 1357 | char *fakename; |
| 1358 | int error; |
| 1359 | |
| 1360 | nch->ncp = NULL; |
| 1361 | nch->mount = dvp->v_mount; |
| 1362 | saved_dvp = NULL; |
| 1363 | fakename = NULL; |
| 1364 | |
| 1365 | /* |
| 1366 | * Temporary debugging code to force the directory scanning code |
| 1367 | * to be exercised. |
| 1368 | */ |
| 1369 | if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) { |
| 1370 | nch->ncp = TAILQ_FIRST(&dvp->v_namecache); |
| 1371 | kprintf("cache_fromdvp: forcing %s\n", nch->ncp->nc_name); |
| 1372 | goto force; |
| 1373 | } |
| 1374 | |
| 1375 | /* |
| 1376 | * Loop until resolution, inside code will break out on error. |
| 1377 | */ |
| 1378 | while ((nch->ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) { |
| 1379 | force: |
| 1380 | /* |
| 1381 | * If dvp is the root of its filesystem it should already |
| 1382 | * have a namecache pointer associated with it as a side |
| 1383 | * effect of the mount, but it may have been disassociated. |
| 1384 | */ |
| 1385 | if (dvp->v_flag & VROOT) { |
| 1386 | nch->ncp = _cache_get(nch->mount->mnt_ncmountpt.ncp); |
| 1387 | error = cache_resolve_mp(nch->mount); |
| 1388 | _cache_put(nch->ncp); |
| 1389 | if (ncvp_debug) { |
| 1390 | kprintf("cache_fromdvp: resolve root of mount %p error %d", |
| 1391 | dvp->v_mount, error); |
| 1392 | } |
| 1393 | if (error) { |
| 1394 | if (ncvp_debug) |
| 1395 | kprintf(" failed\n"); |
| 1396 | nch->ncp = NULL; |
| 1397 | break; |
| 1398 | } |
| 1399 | if (ncvp_debug) |
| 1400 | kprintf(" succeeded\n"); |
| 1401 | continue; |
| 1402 | } |
| 1403 | |
| 1404 | /* |
| 1405 | * If we are recursed too deeply resort to an O(n^2) |
| 1406 | * algorithm to resolve the namecache topology. The |
| 1407 | * resolved pvp is left referenced in saved_dvp to |
| 1408 | * prevent the tree from being destroyed while we loop. |
| 1409 | */ |
| 1410 | if (makeit > 20) { |
| 1411 | error = cache_fromdvp_try(dvp, cred, &saved_dvp); |
| 1412 | if (error) { |
| 1413 | kprintf("lookupdotdot(longpath) failed %d " |
| 1414 | "dvp %p\n", error, dvp); |
| 1415 | nch->ncp = NULL; |
| 1416 | break; |
| 1417 | } |
| 1418 | continue; |
| 1419 | } |
| 1420 | |
| 1421 | /* |
| 1422 | * Get the parent directory and resolve its ncp. |
| 1423 | */ |
| 1424 | if (fakename) { |
| 1425 | kfree(fakename, M_TEMP); |
| 1426 | fakename = NULL; |
| 1427 | } |
| 1428 | error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred, |
| 1429 | &fakename); |
| 1430 | if (error) { |
| 1431 | kprintf("lookupdotdot failed %d dvp %p\n", error, dvp); |
| 1432 | break; |
| 1433 | } |
| 1434 | vn_unlock(pvp); |
| 1435 | |
| 1436 | /* |
| 1437 | * Reuse makeit as a recursion depth counter. On success |
| 1438 | * nch will be fully referenced. |
| 1439 | */ |
| 1440 | cache_fromdvp(pvp, cred, makeit + 1, nch); |
| 1441 | vrele(pvp); |
| 1442 | if (nch->ncp == NULL) |
| 1443 | break; |
| 1444 | |
| 1445 | /* |
| 1446 | * Do an inefficient scan of pvp (embodied by ncp) to look |
| 1447 | * for dvp. This will create a namecache record for dvp on |
| 1448 | * success. We loop up to recheck on success. |
| 1449 | * |
| 1450 | * ncp and dvp are both held but not locked. |
| 1451 | */ |
| 1452 | error = cache_inefficient_scan(nch, cred, dvp, fakename); |
| 1453 | if (error) { |
| 1454 | kprintf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", |
| 1455 | pvp, nch->ncp->nc_name, dvp); |
| 1456 | cache_drop(nch); |
| 1457 | /* nch was NULLed out, reload mount */ |
| 1458 | nch->mount = dvp->v_mount; |
| 1459 | break; |
| 1460 | } |
| 1461 | if (ncvp_debug) { |
| 1462 | kprintf("cache_fromdvp: scan %p (%s) succeeded\n", |
| 1463 | pvp, nch->ncp->nc_name); |
| 1464 | } |
| 1465 | cache_drop(nch); |
| 1466 | /* nch was NULLed out, reload mount */ |
| 1467 | nch->mount = dvp->v_mount; |
| 1468 | } |
| 1469 | |
| 1470 | if (fakename) |
| 1471 | kfree(fakename, M_TEMP); |
| 1472 | |
| 1473 | /* |
| 1474 | * hold it for real so the mount gets a ref |
| 1475 | */ |
| 1476 | if (nch->ncp) |
| 1477 | cache_hold(nch); |
| 1478 | if (saved_dvp) |
| 1479 | vrele(saved_dvp); |
| 1480 | if (nch->ncp) |
| 1481 | return (0); |
| 1482 | return (EINVAL); |
| 1483 | } |
| 1484 | |
| 1485 | /* |
| 1486 | * Go up the chain of parent directories until we find something |
| 1487 | * we can resolve into the namecache. This is very inefficient. |
| 1488 | */ |
| 1489 | static |
| 1490 | int |
| 1491 | cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, |
| 1492 | struct vnode **saved_dvp) |
| 1493 | { |
| 1494 | struct nchandle nch; |
| 1495 | struct vnode *pvp; |
| 1496 | int error; |
| 1497 | static time_t last_fromdvp_report; |
| 1498 | char *fakename; |
| 1499 | |
| 1500 | /* |
| 1501 | * Loop getting the parent directory vnode until we get something we |
| 1502 | * can resolve in the namecache. |
| 1503 | */ |
| 1504 | vref(dvp); |
| 1505 | nch.mount = dvp->v_mount; |
| 1506 | nch.ncp = NULL; |
| 1507 | fakename = NULL; |
| 1508 | |
| 1509 | for (;;) { |
| 1510 | if (fakename) { |
| 1511 | kfree(fakename, M_TEMP); |
| 1512 | fakename = NULL; |
| 1513 | } |
| 1514 | error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred, |
| 1515 | &fakename); |
| 1516 | if (error) { |
| 1517 | vrele(dvp); |
| 1518 | break; |
| 1519 | } |
| 1520 | vn_unlock(pvp); |
| 1521 | if ((nch.ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) { |
| 1522 | _cache_hold(nch.ncp); |
| 1523 | vrele(pvp); |
| 1524 | break; |
| 1525 | } |
| 1526 | if (pvp->v_flag & VROOT) { |
| 1527 | nch.ncp = _cache_get(pvp->v_mount->mnt_ncmountpt.ncp); |
| 1528 | error = cache_resolve_mp(nch.mount); |
| 1529 | _cache_unlock(nch.ncp); |
| 1530 | vrele(pvp); |
| 1531 | if (error) { |
| 1532 | _cache_drop(nch.ncp); |
| 1533 | nch.ncp = NULL; |
| 1534 | vrele(dvp); |
| 1535 | } |
| 1536 | break; |
| 1537 | } |
| 1538 | vrele(dvp); |
| 1539 | dvp = pvp; |
| 1540 | } |
| 1541 | if (error == 0) { |
| 1542 | if (last_fromdvp_report != time_second) { |
| 1543 | last_fromdvp_report = time_second; |
| 1544 | kprintf("Warning: extremely inefficient path " |
| 1545 | "resolution on %s\n", |
| 1546 | nch.ncp->nc_name); |
| 1547 | } |
| 1548 | error = cache_inefficient_scan(&nch, cred, dvp, fakename); |
| 1549 | |
| 1550 | /* |
| 1551 | * Hopefully dvp now has a namecache record associated with |
| 1552 | * it. Leave it referenced to prevent the kernel from |
| 1553 | * recycling the vnode. Otherwise extremely long directory |
| 1554 | * paths could result in endless recycling. |
| 1555 | */ |
| 1556 | if (*saved_dvp) |
| 1557 | vrele(*saved_dvp); |
| 1558 | *saved_dvp = dvp; |
| 1559 | _cache_drop(nch.ncp); |
| 1560 | } |
| 1561 | if (fakename) |
| 1562 | kfree(fakename, M_TEMP); |
| 1563 | return (error); |
| 1564 | } |
| 1565 | |
| 1566 | /* |
| 1567 | * Do an inefficient scan of the directory represented by ncp looking for |
| 1568 | * the directory vnode dvp. ncp must be held but not locked on entry and |
| 1569 | * will be held on return. dvp must be refd but not locked on entry and |
| 1570 | * will remain refd on return. |
| 1571 | * |
| 1572 | * Why do this at all? Well, due to its stateless nature the NFS server |
| 1573 | * converts file handles directly to vnodes without necessarily going through |
| 1574 | * the namecache ops that would otherwise create the namecache topology |
| 1575 | * leading to the vnode. We could either (1) Change the namecache algorithms |
| 1576 | * to allow disconnect namecache records that are re-merged opportunistically, |
| 1577 | * or (2) Make the NFS server backtrack and scan to recover a connected |
| 1578 | * namecache topology in order to then be able to issue new API lookups. |
| 1579 | * |
| 1580 | * It turns out that (1) is a huge mess. It takes a nice clean set of |
| 1581 | * namecache algorithms and introduces a lot of complication in every subsystem |
| 1582 | * that calls into the namecache to deal with the re-merge case, especially |
| 1583 | * since we are using the namecache to placehold negative lookups and the |
| 1584 | * vnode might not be immediately assigned. (2) is certainly far less |
| 1585 | * efficient then (1), but since we are only talking about directories here |
| 1586 | * (which are likely to remain cached), the case does not actually run all |
| 1587 | * that often and has the supreme advantage of not polluting the namecache |
| 1588 | * algorithms. |
| 1589 | * |
| 1590 | * If a fakename is supplied just construct a namecache entry using the |
| 1591 | * fake name. |
| 1592 | */ |
| 1593 | static int |
| 1594 | cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, |
| 1595 | struct vnode *dvp, char *fakename) |
| 1596 | { |
| 1597 | struct nlcomponent nlc; |
| 1598 | struct nchandle rncp; |
| 1599 | struct dirent *den; |
| 1600 | struct vnode *pvp; |
| 1601 | struct vattr vat; |
| 1602 | struct iovec iov; |
| 1603 | struct uio uio; |
| 1604 | int blksize; |
| 1605 | int eofflag; |
| 1606 | int bytes; |
| 1607 | char *rbuf; |
| 1608 | int error; |
| 1609 | |
| 1610 | vat.va_blocksize = 0; |
| 1611 | if ((error = VOP_GETATTR(dvp, &vat)) != 0) |
| 1612 | return (error); |
| 1613 | if ((error = cache_vref(nch, cred, &pvp)) != 0) |
| 1614 | return (error); |
| 1615 | if (ncvp_debug) { |
| 1616 | kprintf("inefficient_scan: directory iosize %ld " |
| 1617 | "vattr fileid = %lld\n", |
| 1618 | vat.va_blocksize, |
| 1619 | (long long)vat.va_fileid); |
| 1620 | } |
| 1621 | |
| 1622 | /* |
| 1623 | * Use the supplied fakename if not NULL. Fake names are typically |
| 1624 | * not in the actual filesystem hierarchy. This is used by HAMMER |
| 1625 | * to glue @@timestamp recursions together. |
| 1626 | */ |
| 1627 | if (fakename) { |
| 1628 | nlc.nlc_nameptr = fakename; |
| 1629 | nlc.nlc_namelen = strlen(fakename); |
| 1630 | rncp = cache_nlookup(nch, &nlc); |
| 1631 | goto done; |
| 1632 | } |
| 1633 | |
| 1634 | if ((blksize = vat.va_blocksize) == 0) |
| 1635 | blksize = DEV_BSIZE; |
| 1636 | rbuf = kmalloc(blksize, M_TEMP, M_WAITOK); |
| 1637 | rncp.ncp = NULL; |
| 1638 | |
| 1639 | eofflag = 0; |
| 1640 | uio.uio_offset = 0; |
| 1641 | again: |
| 1642 | iov.iov_base = rbuf; |
| 1643 | iov.iov_len = blksize; |
| 1644 | uio.uio_iov = &iov; |
| 1645 | uio.uio_iovcnt = 1; |
| 1646 | uio.uio_resid = blksize; |
| 1647 | uio.uio_segflg = UIO_SYSSPACE; |
| 1648 | uio.uio_rw = UIO_READ; |
| 1649 | uio.uio_td = curthread; |
| 1650 | |
| 1651 | if (ncvp_debug >= 2) |
| 1652 | kprintf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); |
| 1653 | error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); |
| 1654 | if (error == 0) { |
| 1655 | den = (struct dirent *)rbuf; |
| 1656 | bytes = blksize - uio.uio_resid; |
| 1657 | |
| 1658 | while (bytes > 0) { |
| 1659 | if (ncvp_debug >= 2) { |
| 1660 | kprintf("cache_inefficient_scan: %*.*s\n", |
| 1661 | den->d_namlen, den->d_namlen, |
| 1662 | den->d_name); |
| 1663 | } |
| 1664 | if (den->d_type != DT_WHT && |
| 1665 | den->d_ino == vat.va_fileid) { |
| 1666 | if (ncvp_debug) { |
| 1667 | kprintf("cache_inefficient_scan: " |
| 1668 | "MATCHED inode %lld path %s/%*.*s\n", |
| 1669 | (long long)vat.va_fileid, |
| 1670 | nch->ncp->nc_name, |
| 1671 | den->d_namlen, den->d_namlen, |
| 1672 | den->d_name); |
| 1673 | } |
| 1674 | nlc.nlc_nameptr = den->d_name; |
| 1675 | nlc.nlc_namelen = den->d_namlen; |
| 1676 | rncp = cache_nlookup(nch, &nlc); |
| 1677 | KKASSERT(rncp.ncp != NULL); |
| 1678 | break; |
| 1679 | } |
| 1680 | bytes -= _DIRENT_DIRSIZ(den); |
| 1681 | den = _DIRENT_NEXT(den); |
| 1682 | } |
| 1683 | if (rncp.ncp == NULL && eofflag == 0 && uio.uio_resid != blksize) |
| 1684 | goto again; |
| 1685 | } |
| 1686 | kfree(rbuf, M_TEMP); |
| 1687 | done: |
| 1688 | vrele(pvp); |
| 1689 | if (rncp.ncp) { |
| 1690 | if (rncp.ncp->nc_flag & NCF_UNRESOLVED) { |
| 1691 | _cache_setvp(rncp.mount, rncp.ncp, dvp); |
| 1692 | if (ncvp_debug >= 2) { |
| 1693 | kprintf("cache_inefficient_scan: setvp %s/%s = %p\n", |
| 1694 | nch->ncp->nc_name, rncp.ncp->nc_name, dvp); |
| 1695 | } |
| 1696 | } else { |
| 1697 | if (ncvp_debug >= 2) { |
| 1698 | kprintf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", |
| 1699 | nch->ncp->nc_name, rncp.ncp->nc_name, dvp, |
| 1700 | rncp.ncp->nc_vp); |
| 1701 | } |
| 1702 | } |
| 1703 | if (rncp.ncp->nc_vp == NULL) |
| 1704 | error = rncp.ncp->nc_error; |
| 1705 | /* |
| 1706 | * Release rncp after a successful nlookup. rncp was fully |
| 1707 | * referenced. |
| 1708 | */ |
| 1709 | cache_put(&rncp); |
| 1710 | } else { |
| 1711 | kprintf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", |
| 1712 | dvp, nch->ncp->nc_name); |
| 1713 | error = ENOENT; |
| 1714 | } |
| 1715 | return (error); |
| 1716 | } |
| 1717 | |
| 1718 | /* |
| 1719 | * Zap a namecache entry. The ncp is unconditionally set to an unresolved |
| 1720 | * state, which disassociates it from its vnode or ncneglist. |
| 1721 | * |
| 1722 | * Then, if there are no additional references to the ncp and no children, |
| 1723 | * the ncp is removed from the topology and destroyed. This function will |
| 1724 | * also run through the nc_parent chain and destroy parent ncps if possible. |
| 1725 | * As a side benefit, it turns out the only conditions that allow running |
| 1726 | * up the chain are also the conditions to ensure no deadlock will occur. |
| 1727 | * |
| 1728 | * References and/or children may exist if the ncp is in the middle of the |
| 1729 | * topology, preventing the ncp from being destroyed. |
| 1730 | * |
| 1731 | * This function must be called with the ncp held and locked and will unlock |
| 1732 | * and drop it during zapping. |
| 1733 | */ |
| 1734 | static void |
| 1735 | cache_zap(struct namecache *ncp) |
| 1736 | { |
| 1737 | struct namecache *par; |
| 1738 | |
| 1739 | /* |
| 1740 | * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. |
| 1741 | */ |
| 1742 | _cache_setunresolved(ncp); |
| 1743 | |
| 1744 | /* |
| 1745 | * Try to scrap the entry and possibly tail-recurse on its parent. |
| 1746 | * We only scrap unref'd (other then our ref) unresolved entries, |
| 1747 | * we do not scrap 'live' entries. |
| 1748 | */ |
| 1749 | while (ncp->nc_flag & NCF_UNRESOLVED) { |
| 1750 | /* |
| 1751 | * Someone other then us has a ref, stop. |
| 1752 | */ |
| 1753 | if (ncp->nc_refs > 1) |
| 1754 | goto done; |
| 1755 | |
| 1756 | /* |
| 1757 | * We have children, stop. |
| 1758 | */ |
| 1759 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 1760 | goto done; |
| 1761 | |
| 1762 | /* |
| 1763 | * Remove ncp from the topology: hash table and parent linkage. |
| 1764 | */ |
| 1765 | if (ncp->nc_flag & NCF_HASHED) { |
| 1766 | ncp->nc_flag &= ~NCF_HASHED; |
| 1767 | LIST_REMOVE(ncp, nc_hash); |
| 1768 | } |
| 1769 | if ((par = ncp->nc_parent) != NULL) { |
| 1770 | par = _cache_hold(par); |
| 1771 | TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); |
| 1772 | ncp->nc_parent = NULL; |
| 1773 | if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) |
| 1774 | vdrop(par->nc_vp); |
| 1775 | } |
| 1776 | |
| 1777 | /* |
| 1778 | * ncp should not have picked up any refs. Physically |
| 1779 | * destroy the ncp. |
| 1780 | */ |
| 1781 | KKASSERT(ncp->nc_refs == 1); |
| 1782 | --numunres; |
| 1783 | /* _cache_unlock(ncp) not required */ |
| 1784 | ncp->nc_refs = -1; /* safety */ |
| 1785 | if (ncp->nc_name) |
| 1786 | kfree(ncp->nc_name, M_VFSCACHE); |
| 1787 | kfree(ncp, M_VFSCACHE); |
| 1788 | |
| 1789 | /* |
| 1790 | * Loop on the parent (it may be NULL). Only bother looping |
| 1791 | * if the parent has a single ref (ours), which also means |
| 1792 | * we can lock it trivially. |
| 1793 | */ |
| 1794 | ncp = par; |
| 1795 | if (ncp == NULL) |
| 1796 | return; |
| 1797 | if (ncp->nc_refs != 1) { |
| 1798 | _cache_drop(ncp); |
| 1799 | return; |
| 1800 | } |
| 1801 | KKASSERT(par->nc_exlocks == 0); |
| 1802 | _cache_lock(ncp); |
| 1803 | } |
| 1804 | done: |
| 1805 | _cache_unlock(ncp); |
| 1806 | atomic_subtract_int(&ncp->nc_refs, 1); |
| 1807 | } |
| 1808 | |
| 1809 | static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW; |
| 1810 | |
| 1811 | static __inline |
| 1812 | void |
| 1813 | cache_hysteresis(void) |
| 1814 | { |
| 1815 | /* |
| 1816 | * Don't cache too many negative hits. We use hysteresis to reduce |
| 1817 | * the impact on the critical path. |
| 1818 | */ |
| 1819 | switch(cache_hysteresis_state) { |
| 1820 | case CHI_LOW: |
| 1821 | if (numneg > MINNEG && numneg * ncnegfactor > numcache) { |
| 1822 | cache_cleanneg(10); |
| 1823 | cache_hysteresis_state = CHI_HIGH; |
| 1824 | } |
| 1825 | break; |
| 1826 | case CHI_HIGH: |
| 1827 | if (numneg > MINNEG * 9 / 10 && |
| 1828 | numneg * ncnegfactor * 9 / 10 > numcache |
| 1829 | ) { |
| 1830 | cache_cleanneg(10); |
| 1831 | } else { |
| 1832 | cache_hysteresis_state = CHI_LOW; |
| 1833 | } |
| 1834 | break; |
| 1835 | } |
| 1836 | } |
| 1837 | |
| 1838 | /* |
| 1839 | * NEW NAMECACHE LOOKUP API |
| 1840 | * |
| 1841 | * Lookup an entry in the cache. A locked, referenced, non-NULL |
| 1842 | * entry is *always* returned, even if the supplied component is illegal. |
| 1843 | * The resulting namecache entry should be returned to the system with |
| 1844 | * cache_put() or _cache_unlock() + cache_drop(). |
| 1845 | * |
| 1846 | * namecache locks are recursive but care must be taken to avoid lock order |
| 1847 | * reversals. |
| 1848 | * |
| 1849 | * Nobody else will be able to manipulate the associated namespace (e.g. |
| 1850 | * create, delete, rename, rename-target) until the caller unlocks the |
| 1851 | * entry. |
| 1852 | * |
| 1853 | * The returned entry will be in one of three states: positive hit (non-null |
| 1854 | * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). |
| 1855 | * Unresolved entries must be resolved through the filesystem to associate the |
| 1856 | * vnode and/or determine whether a positive or negative hit has occured. |
| 1857 | * |
| 1858 | * It is not necessary to lock a directory in order to lock namespace under |
| 1859 | * that directory. In fact, it is explicitly not allowed to do that. A |
| 1860 | * directory is typically only locked when being created, renamed, or |
| 1861 | * destroyed. |
| 1862 | * |
| 1863 | * The directory (par) may be unresolved, in which case any returned child |
| 1864 | * will likely also be marked unresolved. Likely but not guarenteed. Since |
| 1865 | * the filesystem lookup requires a resolved directory vnode the caller is |
| 1866 | * responsible for resolving the namecache chain top-down. This API |
| 1867 | * specifically allows whole chains to be created in an unresolved state. |
| 1868 | */ |
| 1869 | struct nchandle |
| 1870 | cache_nlookup(struct nchandle *par_nch, struct nlcomponent *nlc) |
| 1871 | { |
| 1872 | struct nchandle nch; |
| 1873 | struct namecache *ncp; |
| 1874 | struct namecache *new_ncp; |
| 1875 | struct nchashhead *nchpp; |
| 1876 | struct mount *mp; |
| 1877 | u_int32_t hash; |
| 1878 | globaldata_t gd; |
| 1879 | |
| 1880 | numcalls++; |
| 1881 | gd = mycpu; |
| 1882 | mp = par_nch->mount; |
| 1883 | |
| 1884 | /* |
| 1885 | * Try to locate an existing entry |
| 1886 | */ |
| 1887 | hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); |
| 1888 | hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); |
| 1889 | new_ncp = NULL; |
| 1890 | restart: |
| 1891 | LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { |
| 1892 | numchecks++; |
| 1893 | |
| 1894 | /* |
| 1895 | * Break out if we find a matching entry. Note that |
| 1896 | * UNRESOLVED entries may match, but DESTROYED entries |
| 1897 | * do not. |
| 1898 | */ |
| 1899 | if (ncp->nc_parent == par_nch->ncp && |
| 1900 | ncp->nc_nlen == nlc->nlc_namelen && |
| 1901 | bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && |
| 1902 | (ncp->nc_flag & NCF_DESTROYED) == 0 |
| 1903 | ) { |
| 1904 | if (_cache_get_nonblock(ncp) == 0) { |
| 1905 | _cache_auto_unresolve(mp, ncp); |
| 1906 | if (new_ncp) |
| 1907 | _cache_free(new_ncp); |
| 1908 | goto found; |
| 1909 | } |
| 1910 | _cache_get(ncp); |
| 1911 | _cache_put(ncp); |
| 1912 | goto restart; |
| 1913 | } |
| 1914 | } |
| 1915 | |
| 1916 | /* |
| 1917 | * We failed to locate an entry, create a new entry and add it to |
| 1918 | * the cache. We have to relookup after possibly blocking in |
| 1919 | * malloc. |
| 1920 | */ |
| 1921 | if (new_ncp == NULL) { |
| 1922 | new_ncp = cache_alloc(nlc->nlc_namelen); |
| 1923 | goto restart; |
| 1924 | } |
| 1925 | |
| 1926 | ncp = new_ncp; |
| 1927 | |
| 1928 | /* |
| 1929 | * Initialize as a new UNRESOLVED entry, lock (non-blocking), |
| 1930 | * and link to the parent. The mount point is usually inherited |
| 1931 | * from the parent unless this is a special case such as a mount |
| 1932 | * point where nlc_namelen is 0. If nlc_namelen is 0 nc_name will |
| 1933 | * be NULL. |
| 1934 | */ |
| 1935 | if (nlc->nlc_namelen) { |
| 1936 | bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen); |
| 1937 | ncp->nc_name[nlc->nlc_namelen] = 0; |
| 1938 | } |
| 1939 | nchpp = NCHHASH(hash); |
| 1940 | LIST_INSERT_HEAD(nchpp, ncp, nc_hash); |
| 1941 | ncp->nc_flag |= NCF_HASHED; |
| 1942 | cache_link_parent(ncp, par_nch->ncp); |
| 1943 | found: |
| 1944 | /* |
| 1945 | * stats and namecache size management |
| 1946 | */ |
| 1947 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 1948 | ++gd->gd_nchstats->ncs_miss; |
| 1949 | else if (ncp->nc_vp) |
| 1950 | ++gd->gd_nchstats->ncs_goodhits; |
| 1951 | else |
| 1952 | ++gd->gd_nchstats->ncs_neghits; |
| 1953 | cache_hysteresis(); |
| 1954 | nch.mount = mp; |
| 1955 | nch.ncp = ncp; |
| 1956 | atomic_add_int(&nch.mount->mnt_refs, 1); |
| 1957 | return(nch); |
| 1958 | } |
| 1959 | |
| 1960 | /* |
| 1961 | * The namecache entry is marked as being used as a mount point. |
| 1962 | * Locate the mount if it is visible to the caller. |
| 1963 | */ |
| 1964 | struct findmount_info { |
| 1965 | struct mount *result; |
| 1966 | struct mount *nch_mount; |
| 1967 | struct namecache *nch_ncp; |
| 1968 | }; |
| 1969 | |
| 1970 | static |
| 1971 | int |
| 1972 | cache_findmount_callback(struct mount *mp, void *data) |
| 1973 | { |
| 1974 | struct findmount_info *info = data; |
| 1975 | |
| 1976 | /* |
| 1977 | * Check the mount's mounted-on point against the passed nch. |
| 1978 | */ |
| 1979 | if (mp->mnt_ncmounton.mount == info->nch_mount && |
| 1980 | mp->mnt_ncmounton.ncp == info->nch_ncp |
| 1981 | ) { |
| 1982 | info->result = mp; |
| 1983 | return(-1); |
| 1984 | } |
| 1985 | return(0); |
| 1986 | } |
| 1987 | |
| 1988 | struct mount * |
| 1989 | cache_findmount(struct nchandle *nch) |
| 1990 | { |
| 1991 | struct findmount_info info; |
| 1992 | |
| 1993 | info.result = NULL; |
| 1994 | info.nch_mount = nch->mount; |
| 1995 | info.nch_ncp = nch->ncp; |
| 1996 | mountlist_scan(cache_findmount_callback, &info, |
| 1997 | MNTSCAN_FORWARD|MNTSCAN_NOBUSY); |
| 1998 | return(info.result); |
| 1999 | } |
| 2000 | |
| 2001 | /* |
| 2002 | * Resolve an unresolved namecache entry, generally by looking it up. |
| 2003 | * The passed ncp must be locked and refd. |
| 2004 | * |
| 2005 | * Theoretically since a vnode cannot be recycled while held, and since |
| 2006 | * the nc_parent chain holds its vnode as long as children exist, the |
| 2007 | * direct parent of the cache entry we are trying to resolve should |
| 2008 | * have a valid vnode. If not then generate an error that we can |
| 2009 | * determine is related to a resolver bug. |
| 2010 | * |
| 2011 | * However, if a vnode was in the middle of a recyclement when the NCP |
| 2012 | * got locked, ncp->nc_vp might point to a vnode that is about to become |
| 2013 | * invalid. cache_resolve() handles this case by unresolving the entry |
| 2014 | * and then re-resolving it. |
| 2015 | * |
| 2016 | * Note that successful resolution does not necessarily return an error |
| 2017 | * code of 0. If the ncp resolves to a negative cache hit then ENOENT |
| 2018 | * will be returned. |
| 2019 | */ |
| 2020 | int |
| 2021 | cache_resolve(struct nchandle *nch, struct ucred *cred) |
| 2022 | { |
| 2023 | struct namecache *par; |
| 2024 | struct namecache *ncp; |
| 2025 | struct nchandle nctmp; |
| 2026 | struct mount *mp; |
| 2027 | struct vnode *dvp; |
| 2028 | int error; |
| 2029 | |
| 2030 | ncp = nch->ncp; |
| 2031 | mp = nch->mount; |
| 2032 | restart: |
| 2033 | /* |
| 2034 | * If the ncp is already resolved we have nothing to do. However, |
| 2035 | * we do want to guarentee that a usable vnode is returned when |
| 2036 | * a vnode is present, so make sure it hasn't been reclaimed. |
| 2037 | */ |
| 2038 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 2039 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 2040 | _cache_setunresolved(ncp); |
| 2041 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) |
| 2042 | return (ncp->nc_error); |
| 2043 | } |
| 2044 | |
| 2045 | /* |
| 2046 | * Mount points need special handling because the parent does not |
| 2047 | * belong to the same filesystem as the ncp. |
| 2048 | */ |
| 2049 | if (ncp == mp->mnt_ncmountpt.ncp) |
| 2050 | return (cache_resolve_mp(mp)); |
| 2051 | |
| 2052 | /* |
| 2053 | * We expect an unbroken chain of ncps to at least the mount point, |
| 2054 | * and even all the way to root (but this code doesn't have to go |
| 2055 | * past the mount point). |
| 2056 | */ |
| 2057 | if (ncp->nc_parent == NULL) { |
| 2058 | kprintf("EXDEV case 1 %p %*.*s\n", ncp, |
| 2059 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 2060 | ncp->nc_error = EXDEV; |
| 2061 | return(ncp->nc_error); |
| 2062 | } |
| 2063 | |
| 2064 | /* |
| 2065 | * The vp's of the parent directories in the chain are held via vhold() |
| 2066 | * due to the existance of the child, and should not disappear. |
| 2067 | * However, there are cases where they can disappear: |
| 2068 | * |
| 2069 | * - due to filesystem I/O errors. |
| 2070 | * - due to NFS being stupid about tracking the namespace and |
| 2071 | * destroys the namespace for entire directories quite often. |
| 2072 | * - due to forced unmounts. |
| 2073 | * - due to an rmdir (parent will be marked DESTROYED) |
| 2074 | * |
| 2075 | * When this occurs we have to track the chain backwards and resolve |
| 2076 | * it, looping until the resolver catches up to the current node. We |
| 2077 | * could recurse here but we might run ourselves out of kernel stack |
| 2078 | * so we do it in a more painful manner. This situation really should |
| 2079 | * not occur all that often, or if it does not have to go back too |
| 2080 | * many nodes to resolve the ncp. |
| 2081 | */ |
| 2082 | while ((dvp = cache_dvpref(ncp)) == NULL) { |
| 2083 | /* |
| 2084 | * This case can occur if a process is CD'd into a |
| 2085 | * directory which is then rmdir'd. If the parent is marked |
| 2086 | * destroyed there is no point trying to resolve it. |
| 2087 | */ |
| 2088 | if (ncp->nc_parent->nc_flag & NCF_DESTROYED) |
| 2089 | return(ENOENT); |
| 2090 | |
| 2091 | par = ncp->nc_parent; |
| 2092 | while (par->nc_parent && par->nc_parent->nc_vp == NULL) |
| 2093 | par = par->nc_parent; |
| 2094 | if (par->nc_parent == NULL) { |
| 2095 | kprintf("EXDEV case 2 %*.*s\n", |
| 2096 | par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2097 | return (EXDEV); |
| 2098 | } |
| 2099 | kprintf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", |
| 2100 | par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2101 | /* |
| 2102 | * The parent is not set in stone, ref and lock it to prevent |
| 2103 | * it from disappearing. Also note that due to renames it |
| 2104 | * is possible for our ncp to move and for par to no longer |
| 2105 | * be one of its parents. We resolve it anyway, the loop |
| 2106 | * will handle any moves. |
| 2107 | */ |
| 2108 | _cache_get(par); |
| 2109 | if (par == nch->mount->mnt_ncmountpt.ncp) { |
| 2110 | cache_resolve_mp(nch->mount); |
| 2111 | } else if ((dvp = cache_dvpref(par)) == NULL) { |
| 2112 | kprintf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2113 | _cache_put(par); |
| 2114 | continue; |
| 2115 | } else { |
| 2116 | if (par->nc_flag & NCF_UNRESOLVED) { |
| 2117 | nctmp.mount = mp; |
| 2118 | nctmp.ncp = par; |
| 2119 | par->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); |
| 2120 | } |
| 2121 | vrele(dvp); |
| 2122 | } |
| 2123 | if ((error = par->nc_error) != 0) { |
| 2124 | if (par->nc_error != EAGAIN) { |
| 2125 | kprintf("EXDEV case 3 %*.*s error %d\n", |
| 2126 | par->nc_nlen, par->nc_nlen, par->nc_name, |
| 2127 | par->nc_error); |
| 2128 | _cache_put(par); |
| 2129 | return(error); |
| 2130 | } |
| 2131 | kprintf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", |
| 2132 | par, par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2133 | } |
| 2134 | _cache_put(par); |
| 2135 | /* loop */ |
| 2136 | } |
| 2137 | |
| 2138 | /* |
| 2139 | * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected |
| 2140 | * ncp's and reattach them. If this occurs the original ncp is marked |
| 2141 | * EAGAIN to force a relookup. |
| 2142 | * |
| 2143 | * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed |
| 2144 | * ncp must already be resolved. |
| 2145 | */ |
| 2146 | if (dvp) { |
| 2147 | nctmp.mount = mp; |
| 2148 | nctmp.ncp = ncp; |
| 2149 | ncp->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); |
| 2150 | vrele(dvp); |
| 2151 | } else { |
| 2152 | ncp->nc_error = EPERM; |
| 2153 | } |
| 2154 | if (ncp->nc_error == EAGAIN) { |
| 2155 | kprintf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", |
| 2156 | ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 2157 | goto restart; |
| 2158 | } |
| 2159 | return(ncp->nc_error); |
| 2160 | } |
| 2161 | |
| 2162 | /* |
| 2163 | * Resolve the ncp associated with a mount point. Such ncp's almost always |
| 2164 | * remain resolved and this routine is rarely called. NFS MPs tends to force |
| 2165 | * re-resolution more often due to its mac-truck-smash-the-namecache |
| 2166 | * method of tracking namespace changes. |
| 2167 | * |
| 2168 | * The semantics for this call is that the passed ncp must be locked on |
| 2169 | * entry and will be locked on return. However, if we actually have to |
| 2170 | * resolve the mount point we temporarily unlock the entry in order to |
| 2171 | * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of |
| 2172 | * the unlock we have to recheck the flags after we relock. |
| 2173 | */ |
| 2174 | static int |
| 2175 | cache_resolve_mp(struct mount *mp) |
| 2176 | { |
| 2177 | struct namecache *ncp = mp->mnt_ncmountpt.ncp; |
| 2178 | struct vnode *vp; |
| 2179 | int error; |
| 2180 | |
| 2181 | KKASSERT(mp != NULL); |
| 2182 | |
| 2183 | /* |
| 2184 | * If the ncp is already resolved we have nothing to do. However, |
| 2185 | * we do want to guarentee that a usable vnode is returned when |
| 2186 | * a vnode is present, so make sure it hasn't been reclaimed. |
| 2187 | */ |
| 2188 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 2189 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 2190 | _cache_setunresolved(ncp); |
| 2191 | } |
| 2192 | |
| 2193 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 2194 | _cache_unlock(ncp); |
| 2195 | while (vfs_busy(mp, 0)) |
| 2196 | ; |
| 2197 | error = VFS_ROOT(mp, &vp); |
| 2198 | _cache_lock(ncp); |
| 2199 | |
| 2200 | /* |
| 2201 | * recheck the ncp state after relocking. |
| 2202 | */ |
| 2203 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 2204 | ncp->nc_error = error; |
| 2205 | if (error == 0) { |
| 2206 | _cache_setvp(mp, ncp, vp); |
| 2207 | vput(vp); |
| 2208 | } else { |
| 2209 | kprintf("[diagnostic] cache_resolve_mp: failed" |
| 2210 | " to resolve mount %p err=%d ncp=%p\n", |
| 2211 | mp, error, ncp); |
| 2212 | _cache_setvp(mp, ncp, NULL); |
| 2213 | } |
| 2214 | } else if (error == 0) { |
| 2215 | vput(vp); |
| 2216 | } |
| 2217 | vfs_unbusy(mp); |
| 2218 | } |
| 2219 | return(ncp->nc_error); |
| 2220 | } |
| 2221 | |
| 2222 | void |
| 2223 | cache_cleanneg(int count) |
| 2224 | { |
| 2225 | struct namecache *ncp; |
| 2226 | |
| 2227 | /* |
| 2228 | * Automode from the vnlru proc - clean out 10% of the negative cache |
| 2229 | * entries. |
| 2230 | */ |
| 2231 | if (count == 0) |
| 2232 | count = numneg / 10 + 1; |
| 2233 | |
| 2234 | /* |
| 2235 | * Attempt to clean out the specified number of negative cache |
| 2236 | * entries. |
| 2237 | */ |
| 2238 | while (count) { |
| 2239 | ncp = TAILQ_FIRST(&ncneglist); |
| 2240 | if (ncp == NULL) { |
| 2241 | KKASSERT(numneg == 0); |
| 2242 | break; |
| 2243 | } |
| 2244 | TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); |
| 2245 | TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); |
| 2246 | if (_cache_get_nonblock(ncp) == 0) |
| 2247 | cache_zap(ncp); |
| 2248 | --count; |
| 2249 | } |
| 2250 | } |
| 2251 | |
| 2252 | /* |
| 2253 | * Rehash a ncp. Rehashing is typically required if the name changes (should |
| 2254 | * not generally occur) or the parent link changes. This function will |
| 2255 | * unhash the ncp if the ncp is no longer hashable. |
| 2256 | */ |
| 2257 | static void |
| 2258 | _cache_rehash(struct namecache *ncp) |
| 2259 | { |
| 2260 | struct nchashhead *nchpp; |
| 2261 | u_int32_t hash; |
| 2262 | |
| 2263 | if (ncp->nc_flag & NCF_HASHED) { |
| 2264 | ncp->nc_flag &= ~NCF_HASHED; |
| 2265 | LIST_REMOVE(ncp, nc_hash); |
| 2266 | } |
| 2267 | if (ncp->nc_nlen && ncp->nc_parent) { |
| 2268 | hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT); |
| 2269 | hash = fnv_32_buf(&ncp->nc_parent, |
| 2270 | sizeof(ncp->nc_parent), hash); |
| 2271 | nchpp = NCHHASH(hash); |
| 2272 | LIST_INSERT_HEAD(nchpp, ncp, nc_hash); |
| 2273 | ncp->nc_flag |= NCF_HASHED; |
| 2274 | } |
| 2275 | } |
| 2276 | |
| 2277 | /* |
| 2278 | * Name cache initialization, from vfsinit() when we are booting |
| 2279 | */ |
| 2280 | void |
| 2281 | nchinit(void) |
| 2282 | { |
| 2283 | int i; |
| 2284 | globaldata_t gd; |
| 2285 | |
| 2286 | /* initialise per-cpu namecache effectiveness statistics. */ |
| 2287 | for (i = 0; i < ncpus; ++i) { |
| 2288 | gd = globaldata_find(i); |
| 2289 | gd->gd_nchstats = &nchstats[i]; |
| 2290 | } |
| 2291 | TAILQ_INIT(&ncneglist); |
| 2292 | nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash); |
| 2293 | nclockwarn = 5 * hz; |
| 2294 | } |
| 2295 | |
| 2296 | /* |
| 2297 | * Called from start_init() to bootstrap the root filesystem. Returns |
| 2298 | * a referenced, unlocked namecache record. |
| 2299 | */ |
| 2300 | void |
| 2301 | cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp) |
| 2302 | { |
| 2303 | nch->ncp = cache_alloc(0); |
| 2304 | nch->mount = mp; |
| 2305 | atomic_add_int(&mp->mnt_refs, 1); |
| 2306 | if (vp) |
| 2307 | _cache_setvp(nch->mount, nch->ncp, vp); |
| 2308 | } |
| 2309 | |
| 2310 | /* |
| 2311 | * vfs_cache_setroot() |
| 2312 | * |
| 2313 | * Create an association between the root of our namecache and |
| 2314 | * the root vnode. This routine may be called several times during |
| 2315 | * booting. |
| 2316 | * |
| 2317 | * If the caller intends to save the returned namecache pointer somewhere |
| 2318 | * it must cache_hold() it. |
| 2319 | */ |
| 2320 | void |
| 2321 | vfs_cache_setroot(struct vnode *nvp, struct nchandle *nch) |
| 2322 | { |
| 2323 | struct vnode *ovp; |
| 2324 | struct nchandle onch; |
| 2325 | |
| 2326 | ovp = rootvnode; |
| 2327 | onch = rootnch; |
| 2328 | rootvnode = nvp; |
| 2329 | if (nch) |
| 2330 | rootnch = *nch; |
| 2331 | else |
| 2332 | cache_zero(&rootnch); |
| 2333 | if (ovp) |
| 2334 | vrele(ovp); |
| 2335 | if (onch.ncp) |
| 2336 | cache_drop(&onch); |
| 2337 | } |
| 2338 | |
| 2339 | /* |
| 2340 | * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache |
| 2341 | * topology and is being removed as quickly as possible. The new VOP_N*() |
| 2342 | * API calls are required to make specific adjustments using the supplied |
| 2343 | * ncp pointers rather then just bogusly purging random vnodes. |
| 2344 | * |
| 2345 | * Invalidate all namecache entries to a particular vnode as well as |
| 2346 | * any direct children of that vnode in the namecache. This is a |
| 2347 | * 'catch all' purge used by filesystems that do not know any better. |
| 2348 | * |
| 2349 | * Note that the linkage between the vnode and its namecache entries will |
| 2350 | * be removed, but the namecache entries themselves might stay put due to |
| 2351 | * active references from elsewhere in the system or due to the existance of |
| 2352 | * the children. The namecache topology is left intact even if we do not |
| 2353 | * know what the vnode association is. Such entries will be marked |
| 2354 | * NCF_UNRESOLVED. |
| 2355 | */ |
| 2356 | void |
| 2357 | cache_purge(struct vnode *vp) |
| 2358 | { |
| 2359 | cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN); |
| 2360 | } |
| 2361 | |
| 2362 | /* |
| 2363 | * Flush all entries referencing a particular filesystem. |
| 2364 | * |
| 2365 | * Since we need to check it anyway, we will flush all the invalid |
| 2366 | * entries at the same time. |
| 2367 | */ |
| 2368 | #if 0 |
| 2369 | |
| 2370 | void |
| 2371 | cache_purgevfs(struct mount *mp) |
| 2372 | { |
| 2373 | struct nchashhead *nchpp; |
| 2374 | struct namecache *ncp, *nnp; |
| 2375 | |
| 2376 | /* |
| 2377 | * Scan hash tables for applicable entries. |
| 2378 | */ |
| 2379 | for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { |
| 2380 | ncp = LIST_FIRST(nchpp); |
| 2381 | if (ncp) |
| 2382 | _cache_hold(ncp); |
| 2383 | while (ncp) { |
| 2384 | nnp = LIST_NEXT(ncp, nc_hash); |
| 2385 | if (nnp) |
| 2386 | _cache_hold(nnp); |
| 2387 | if (ncp->nc_mount == mp) { |
| 2388 | _cache_lock(ncp); |
| 2389 | cache_zap(ncp); |
| 2390 | } else { |
| 2391 | _cache_drop(ncp); |
| 2392 | } |
| 2393 | ncp = nnp; |
| 2394 | } |
| 2395 | } |
| 2396 | } |
| 2397 | |
| 2398 | #endif |
| 2399 | |
| 2400 | /* |
| 2401 | * Create a new (theoretically) unique fsmid |
| 2402 | */ |
| 2403 | int64_t |
| 2404 | cache_getnewfsmid(void) |
| 2405 | { |
| 2406 | static int fsmid_roller; |
| 2407 | int64_t fsmid; |
| 2408 | |
| 2409 | ++fsmid_roller; |
| 2410 | fsmid = ((int64_t)time_second << 32) | |
| 2411 | (fsmid_roller & 0x7FFFFFFF); |
| 2412 | return (fsmid); |
| 2413 | } |
| 2414 | |
| 2415 | |
| 2416 | static int disablecwd; |
| 2417 | SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); |
| 2418 | |
| 2419 | static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); |
| 2420 | static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); |
| 2421 | static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); |
| 2422 | static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); |
| 2423 | static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); |
| 2424 | static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); |
| 2425 | |
| 2426 | /* |
| 2427 | * MPALMOSTSAFE |
| 2428 | */ |
| 2429 | int |
| 2430 | sys___getcwd(struct __getcwd_args *uap) |
| 2431 | { |
| 2432 | int buflen; |
| 2433 | int error; |
| 2434 | char *buf; |
| 2435 | char *bp; |
| 2436 | |
| 2437 | if (disablecwd) |
| 2438 | return (ENODEV); |
| 2439 | |
| 2440 | buflen = uap->buflen; |
| 2441 | if (buflen == 0) |
| 2442 | return (EINVAL); |
| 2443 | if (buflen > MAXPATHLEN) |
| 2444 | buflen = MAXPATHLEN; |
| 2445 | |
| 2446 | buf = kmalloc(buflen, M_TEMP, M_WAITOK); |
| 2447 | get_mplock(); |
| 2448 | bp = kern_getcwd(buf, buflen, &error); |
| 2449 | rel_mplock(); |
| 2450 | if (error == 0) |
| 2451 | error = copyout(bp, uap->buf, strlen(bp) + 1); |
| 2452 | kfree(buf, M_TEMP); |
| 2453 | return (error); |
| 2454 | } |
| 2455 | |
| 2456 | char * |
| 2457 | kern_getcwd(char *buf, size_t buflen, int *error) |
| 2458 | { |
| 2459 | struct proc *p = curproc; |
| 2460 | char *bp; |
| 2461 | int i, slash_prefixed; |
| 2462 | struct filedesc *fdp; |
| 2463 | struct nchandle nch; |
| 2464 | |
| 2465 | numcwdcalls++; |
| 2466 | bp = buf; |
| 2467 | bp += buflen - 1; |
| 2468 | *bp = '\0'; |
| 2469 | fdp = p->p_fd; |
| 2470 | slash_prefixed = 0; |
| 2471 | |
| 2472 | nch = fdp->fd_ncdir; |
| 2473 | while (nch.ncp && (nch.ncp != fdp->fd_nrdir.ncp || |
| 2474 | nch.mount != fdp->fd_nrdir.mount) |
| 2475 | ) { |
| 2476 | /* |
| 2477 | * While traversing upwards if we encounter the root |
| 2478 | * of the current mount we have to skip to the mount point |
| 2479 | * in the underlying filesystem. |
| 2480 | */ |
| 2481 | if (nch.ncp == nch.mount->mnt_ncmountpt.ncp) { |
| 2482 | nch = nch.mount->mnt_ncmounton; |
| 2483 | continue; |
| 2484 | } |
| 2485 | |
| 2486 | /* |
| 2487 | * Prepend the path segment |
| 2488 | */ |
| 2489 | for (i = nch.ncp->nc_nlen - 1; i >= 0; i--) { |
| 2490 | if (bp == buf) { |
| 2491 | numcwdfail4++; |
| 2492 | *error = ERANGE; |
| 2493 | return(NULL); |
| 2494 | } |
| 2495 | *--bp = nch.ncp->nc_name[i]; |
| 2496 | } |
| 2497 | if (bp == buf) { |
| 2498 | numcwdfail4++; |
| 2499 | *error = ERANGE; |
| 2500 | return(NULL); |
| 2501 | } |
| 2502 | *--bp = '/'; |
| 2503 | slash_prefixed = 1; |
| 2504 | |
| 2505 | /* |
| 2506 | * Go up a directory. This isn't a mount point so we don't |
| 2507 | * have to check again. |
| 2508 | */ |
| 2509 | nch.ncp = nch.ncp->nc_parent; |
| 2510 | } |
| 2511 | if (nch.ncp == NULL) { |
| 2512 | numcwdfail2++; |
| 2513 | *error = ENOENT; |
| 2514 | return(NULL); |
| 2515 | } |
| 2516 | if (!slash_prefixed) { |
| 2517 | if (bp == buf) { |
| 2518 | numcwdfail4++; |
| 2519 | *error = ERANGE; |
| 2520 | return(NULL); |
| 2521 | } |
| 2522 | *--bp = '/'; |
| 2523 | } |
| 2524 | numcwdfound++; |
| 2525 | *error = 0; |
| 2526 | return (bp); |
| 2527 | } |
| 2528 | |
| 2529 | /* |
| 2530 | * Thus begins the fullpath magic. |
| 2531 | */ |
| 2532 | |
| 2533 | #undef STATNODE |
| 2534 | #define STATNODE(name) \ |
| 2535 | static u_int name; \ |
| 2536 | SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") |
| 2537 | |
| 2538 | static int disablefullpath; |
| 2539 | SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, |
| 2540 | &disablefullpath, 0, ""); |
| 2541 | |
| 2542 | STATNODE(numfullpathcalls); |
| 2543 | STATNODE(numfullpathfail1); |
| 2544 | STATNODE(numfullpathfail2); |
| 2545 | STATNODE(numfullpathfail3); |
| 2546 | STATNODE(numfullpathfail4); |
| 2547 | STATNODE(numfullpathfound); |
| 2548 | |
| 2549 | int |
| 2550 | cache_fullpath(struct proc *p, struct nchandle *nchp, char **retbuf, char **freebuf) |
| 2551 | { |
| 2552 | char *bp, *buf; |
| 2553 | int i, slash_prefixed; |
| 2554 | struct nchandle fd_nrdir; |
| 2555 | struct nchandle nch; |
| 2556 | |
| 2557 | numfullpathcalls--; |
| 2558 | |
| 2559 | *retbuf = NULL; |
| 2560 | *freebuf = NULL; |
| 2561 | |
| 2562 | buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK); |
| 2563 | bp = buf + MAXPATHLEN - 1; |
| 2564 | *bp = '\0'; |
| 2565 | if (p != NULL) |
| 2566 | fd_nrdir = p->p_fd->fd_nrdir; |
| 2567 | else |
| 2568 | fd_nrdir = rootnch; |
| 2569 | slash_prefixed = 0; |
| 2570 | nch = *nchp; |
| 2571 | |
| 2572 | while (nch.ncp && |
| 2573 | (nch.ncp != fd_nrdir.ncp || nch.mount != fd_nrdir.mount) |
| 2574 | ) { |
| 2575 | /* |
| 2576 | * While traversing upwards if we encounter the root |
| 2577 | * of the current mount we have to skip to the mount point. |
| 2578 | */ |
| 2579 | if (nch.ncp == nch.mount->mnt_ncmountpt.ncp) { |
| 2580 | nch = nch.mount->mnt_ncmounton; |
| 2581 | continue; |
| 2582 | } |
| 2583 | |
| 2584 | /* |
| 2585 | * Prepend the path segment |
| 2586 | */ |
| 2587 | for (i = nch.ncp->nc_nlen - 1; i >= 0; i--) { |
| 2588 | if (bp == buf) { |
| 2589 | numfullpathfail4++; |
| 2590 | kfree(buf, M_TEMP); |
| 2591 | return(ENOMEM); |
| 2592 | } |
| 2593 | *--bp = nch.ncp->nc_name[i]; |
| 2594 | } |
| 2595 | if (bp == buf) { |
| 2596 | numfullpathfail4++; |
| 2597 | kfree(buf, M_TEMP); |
| 2598 | return(ENOMEM); |
| 2599 | } |
| 2600 | *--bp = '/'; |
| 2601 | slash_prefixed = 1; |
| 2602 | |
| 2603 | /* |
| 2604 | * Go up a directory. This isn't a mount point so we don't |
| 2605 | * have to check again. |
| 2606 | */ |
| 2607 | nch.ncp = nch.ncp->nc_parent; |
| 2608 | } |
| 2609 | if (nch.ncp == NULL) { |
| 2610 | numfullpathfail2++; |
| 2611 | kfree(buf, M_TEMP); |
| 2612 | return(ENOENT); |
| 2613 | } |
| 2614 | |
| 2615 | if (!slash_prefixed) { |
| 2616 | if (bp == buf) { |
| 2617 | numfullpathfail4++; |
| 2618 | kfree(buf, M_TEMP); |
| 2619 | return(ENOMEM); |
| 2620 | } |
| 2621 | *--bp = '/'; |
| 2622 | } |
| 2623 | numfullpathfound++; |
| 2624 | *retbuf = bp; |
| 2625 | *freebuf = buf; |
| 2626 | |
| 2627 | return(0); |
| 2628 | } |
| 2629 | |
| 2630 | int |
| 2631 | vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf) |
| 2632 | { |
| 2633 | struct namecache *ncp; |
| 2634 | struct nchandle nch; |
| 2635 | |
| 2636 | numfullpathcalls++; |
| 2637 | if (disablefullpath) |
| 2638 | return (ENODEV); |
| 2639 | |
| 2640 | if (p == NULL) |
| 2641 | return (EINVAL); |
| 2642 | |
| 2643 | /* vn is NULL, client wants us to use p->p_textvp */ |
| 2644 | if (vn == NULL) { |
| 2645 | if ((vn = p->p_textvp) == NULL) |
| 2646 | return (EINVAL); |
| 2647 | } |
| 2648 | TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { |
| 2649 | if (ncp->nc_nlen) |
| 2650 | break; |
| 2651 | } |
| 2652 | if (ncp == NULL) |
| 2653 | return (EINVAL); |
| 2654 | |
| 2655 | numfullpathcalls--; |
| 2656 | nch.ncp = ncp;; |
| 2657 | nch.mount = vn->v_mount; |
| 2658 | return(cache_fullpath(p, &nch, retbuf, freebuf)); |
| 2659 | } |