| 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 1.85 2007/11/02 19:52:25 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 | |
| 93 | #define MAX_RECURSION_DEPTH 64 |
| 94 | |
| 95 | /* |
| 96 | * Random lookups in the cache are accomplished with a hash table using |
| 97 | * a hash key of (nc_src_vp, name). |
| 98 | * |
| 99 | * Negative entries may exist and correspond to structures where nc_vp |
| 100 | * is NULL. In a negative entry, NCF_WHITEOUT will be set if the entry |
| 101 | * corresponds to a whited-out directory entry (verses simply not finding the |
| 102 | * entry at all). |
| 103 | * |
| 104 | * Upon reaching the last segment of a path, if the reference is for DELETE, |
| 105 | * or NOCACHE is set (rewrite), and the name is located in the cache, it |
| 106 | * will be dropped. |
| 107 | */ |
| 108 | |
| 109 | /* |
| 110 | * Structures associated with name cacheing. |
| 111 | */ |
| 112 | #define NCHHASH(hash) (&nchashtbl[(hash) & nchash]) |
| 113 | #define MINNEG 1024 |
| 114 | |
| 115 | MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); |
| 116 | |
| 117 | static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ |
| 118 | static struct namecache_list ncneglist; /* instead of vnode */ |
| 119 | |
| 120 | /* |
| 121 | * ncvp_debug - debug cache_fromvp(). This is used by the NFS server |
| 122 | * to create the namecache infrastructure leading to a dangling vnode. |
| 123 | * |
| 124 | * 0 Only errors are reported |
| 125 | * 1 Successes are reported |
| 126 | * 2 Successes + the whole directory scan is reported |
| 127 | * 3 Force the directory scan code run as if the parent vnode did not |
| 128 | * have a namecache record, even if it does have one. |
| 129 | */ |
| 130 | static int ncvp_debug; |
| 131 | SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, ""); |
| 132 | |
| 133 | static u_long nchash; /* size of hash table */ |
| 134 | SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); |
| 135 | |
| 136 | static u_long ncnegfactor = 16; /* ratio of negative entries */ |
| 137 | SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); |
| 138 | |
| 139 | static int nclockwarn; /* warn on locked entries in ticks */ |
| 140 | SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, ""); |
| 141 | |
| 142 | static u_long numneg; /* number of cache entries allocated */ |
| 143 | SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); |
| 144 | |
| 145 | static u_long numcache; /* number of cache entries allocated */ |
| 146 | SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); |
| 147 | |
| 148 | static u_long numunres; /* number of unresolved entries */ |
| 149 | SYSCTL_ULONG(_debug, OID_AUTO, numunres, CTLFLAG_RD, &numunres, 0, ""); |
| 150 | |
| 151 | SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); |
| 152 | SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); |
| 153 | |
| 154 | static int cache_resolve_mp(struct mount *mp); |
| 155 | static void _cache_rehash(struct namecache *ncp); |
| 156 | static void _cache_lock(struct namecache *ncp); |
| 157 | static void _cache_setunresolved(struct namecache *ncp); |
| 158 | |
| 159 | /* |
| 160 | * The new name cache statistics |
| 161 | */ |
| 162 | SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); |
| 163 | #define STATNODE(mode, name, var) \ |
| 164 | SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); |
| 165 | STATNODE(CTLFLAG_RD, numneg, &numneg); |
| 166 | STATNODE(CTLFLAG_RD, numcache, &numcache); |
| 167 | static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); |
| 168 | static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); |
| 169 | static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); |
| 170 | static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); |
| 171 | static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); |
| 172 | static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); |
| 173 | static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); |
| 174 | static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); |
| 175 | static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); |
| 176 | static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); |
| 177 | |
| 178 | struct nchstats nchstats[SMP_MAXCPU]; |
| 179 | /* |
| 180 | * Export VFS cache effectiveness statistics to user-land. |
| 181 | * |
| 182 | * The statistics are left for aggregation to user-land so |
| 183 | * neat things can be achieved, like observing per-CPU cache |
| 184 | * distribution. |
| 185 | */ |
| 186 | static int |
| 187 | sysctl_nchstats(SYSCTL_HANDLER_ARGS) |
| 188 | { |
| 189 | struct globaldata *gd; |
| 190 | int i, error; |
| 191 | |
| 192 | error = 0; |
| 193 | for (i = 0; i < ncpus; ++i) { |
| 194 | gd = globaldata_find(i); |
| 195 | if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats), |
| 196 | sizeof(struct nchstats)))) |
| 197 | break; |
| 198 | } |
| 199 | |
| 200 | return (error); |
| 201 | } |
| 202 | SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD, |
| 203 | 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics"); |
| 204 | |
| 205 | static void cache_zap(struct namecache *ncp); |
| 206 | |
| 207 | /* |
| 208 | * cache_hold() and cache_drop() prevent the premature deletion of a |
| 209 | * namecache entry but do not prevent operations (such as zapping) on |
| 210 | * that namecache entry. |
| 211 | * |
| 212 | * This routine may only be called from outside this source module if |
| 213 | * nc_refs is already at least 1. |
| 214 | * |
| 215 | * This is a rare case where callers are allowed to hold a spinlock, |
| 216 | * so we can't ourselves. |
| 217 | */ |
| 218 | static __inline |
| 219 | struct namecache * |
| 220 | _cache_hold(struct namecache *ncp) |
| 221 | { |
| 222 | atomic_add_int(&ncp->nc_refs, 1); |
| 223 | return(ncp); |
| 224 | } |
| 225 | |
| 226 | /* |
| 227 | * When dropping an entry, if only one ref remains and the entry has not |
| 228 | * been resolved, zap it. Since the one reference is being dropped the |
| 229 | * entry had better not be locked. |
| 230 | */ |
| 231 | static __inline |
| 232 | void |
| 233 | _cache_drop(struct namecache *ncp) |
| 234 | { |
| 235 | KKASSERT(ncp->nc_refs > 0); |
| 236 | if (ncp->nc_refs == 1 && |
| 237 | (ncp->nc_flag & NCF_UNRESOLVED) && |
| 238 | TAILQ_EMPTY(&ncp->nc_list) |
| 239 | ) { |
| 240 | KKASSERT(ncp->nc_exlocks == 0); |
| 241 | _cache_lock(ncp); |
| 242 | cache_zap(ncp); |
| 243 | } else { |
| 244 | atomic_subtract_int(&ncp->nc_refs, 1); |
| 245 | } |
| 246 | } |
| 247 | |
| 248 | /* |
| 249 | * Link a new namecache entry to its parent. Be careful to avoid races |
| 250 | * if vhold() blocks in the future. |
| 251 | */ |
| 252 | static void |
| 253 | cache_link_parent(struct namecache *ncp, struct namecache *par) |
| 254 | { |
| 255 | KKASSERT(ncp->nc_parent == NULL); |
| 256 | ncp->nc_parent = par; |
| 257 | if (TAILQ_EMPTY(&par->nc_list)) { |
| 258 | TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); |
| 259 | /* |
| 260 | * Any vp associated with an ncp which has children must |
| 261 | * be held to prevent it from being recycled. |
| 262 | */ |
| 263 | if (par->nc_vp) |
| 264 | vhold(par->nc_vp); |
| 265 | } else { |
| 266 | TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry); |
| 267 | } |
| 268 | } |
| 269 | |
| 270 | /* |
| 271 | * Remove the parent association from a namecache structure. If this is |
| 272 | * the last child of the parent the cache_drop(par) will attempt to |
| 273 | * recursively zap the parent. |
| 274 | */ |
| 275 | static void |
| 276 | cache_unlink_parent(struct namecache *ncp) |
| 277 | { |
| 278 | struct namecache *par; |
| 279 | |
| 280 | if ((par = ncp->nc_parent) != NULL) { |
| 281 | ncp->nc_parent = NULL; |
| 282 | par = _cache_hold(par); |
| 283 | TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); |
| 284 | if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) |
| 285 | vdrop(par->nc_vp); |
| 286 | _cache_drop(par); |
| 287 | } |
| 288 | } |
| 289 | |
| 290 | /* |
| 291 | * Allocate a new namecache structure. Most of the code does not require |
| 292 | * zero-termination of the string but it makes vop_compat_ncreate() easier. |
| 293 | */ |
| 294 | static struct namecache * |
| 295 | cache_alloc(int nlen) |
| 296 | { |
| 297 | struct namecache *ncp; |
| 298 | |
| 299 | ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO); |
| 300 | if (nlen) |
| 301 | ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK); |
| 302 | ncp->nc_nlen = nlen; |
| 303 | ncp->nc_flag = NCF_UNRESOLVED; |
| 304 | ncp->nc_error = ENOTCONN; /* needs to be resolved */ |
| 305 | ncp->nc_refs = 1; |
| 306 | |
| 307 | /* |
| 308 | * Construct a fake FSMID based on the time of day and a 32 bit |
| 309 | * roller for uniqueness. This is used to generate a useful |
| 310 | * FSMID for filesystems which do not support it. |
| 311 | */ |
| 312 | ncp->nc_fsmid = cache_getnewfsmid(); |
| 313 | TAILQ_INIT(&ncp->nc_list); |
| 314 | _cache_lock(ncp); |
| 315 | return(ncp); |
| 316 | } |
| 317 | |
| 318 | static void |
| 319 | _cache_free(struct namecache *ncp) |
| 320 | { |
| 321 | KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1); |
| 322 | if (ncp->nc_name) |
| 323 | kfree(ncp->nc_name, M_VFSCACHE); |
| 324 | kfree(ncp, M_VFSCACHE); |
| 325 | } |
| 326 | |
| 327 | void |
| 328 | cache_zero(struct nchandle *nch) |
| 329 | { |
| 330 | nch->ncp = NULL; |
| 331 | nch->mount = NULL; |
| 332 | } |
| 333 | |
| 334 | /* |
| 335 | * Ref and deref a namecache structure. |
| 336 | * |
| 337 | * Warning: caller may hold an unrelated read spinlock, which means we can't |
| 338 | * use read spinlocks here. |
| 339 | */ |
| 340 | struct nchandle * |
| 341 | cache_hold(struct nchandle *nch) |
| 342 | { |
| 343 | _cache_hold(nch->ncp); |
| 344 | ++nch->mount->mnt_refs; |
| 345 | return(nch); |
| 346 | } |
| 347 | |
| 348 | void |
| 349 | cache_copy(struct nchandle *nch, struct nchandle *target) |
| 350 | { |
| 351 | *target = *nch; |
| 352 | _cache_hold(target->ncp); |
| 353 | ++nch->mount->mnt_refs; |
| 354 | } |
| 355 | |
| 356 | void |
| 357 | cache_changemount(struct nchandle *nch, struct mount *mp) |
| 358 | { |
| 359 | --nch->mount->mnt_refs; |
| 360 | nch->mount = mp; |
| 361 | ++nch->mount->mnt_refs; |
| 362 | } |
| 363 | |
| 364 | void |
| 365 | cache_drop(struct nchandle *nch) |
| 366 | { |
| 367 | --nch->mount->mnt_refs; |
| 368 | _cache_drop(nch->ncp); |
| 369 | nch->ncp = NULL; |
| 370 | nch->mount = NULL; |
| 371 | } |
| 372 | |
| 373 | /* |
| 374 | * Namespace locking. The caller must already hold a reference to the |
| 375 | * namecache structure in order to lock/unlock it. This function prevents |
| 376 | * the namespace from being created or destroyed by accessors other then |
| 377 | * the lock holder. |
| 378 | * |
| 379 | * Note that holding a locked namecache structure prevents other threads |
| 380 | * from making namespace changes (e.g. deleting or creating), prevents |
| 381 | * vnode association state changes by other threads, and prevents the |
| 382 | * namecache entry from being resolved or unresolved by other threads. |
| 383 | * |
| 384 | * The lock owner has full authority to associate/disassociate vnodes |
| 385 | * and resolve/unresolve the locked ncp. |
| 386 | * |
| 387 | * WARNING! Holding a locked ncp will prevent a vnode from being destroyed |
| 388 | * or recycled, but it does NOT help you if the vnode had already initiated |
| 389 | * a recyclement. If this is important, use cache_get() rather then |
| 390 | * cache_lock() (and deal with the differences in the way the refs counter |
| 391 | * is handled). Or, alternatively, make an unconditional call to |
| 392 | * cache_validate() or cache_resolve() after cache_lock() returns. |
| 393 | */ |
| 394 | static |
| 395 | void |
| 396 | _cache_lock(struct namecache *ncp) |
| 397 | { |
| 398 | thread_t td; |
| 399 | int didwarn; |
| 400 | |
| 401 | KKASSERT(ncp->nc_refs != 0); |
| 402 | didwarn = 0; |
| 403 | td = curthread; |
| 404 | |
| 405 | for (;;) { |
| 406 | if (ncp->nc_exlocks == 0) { |
| 407 | ncp->nc_exlocks = 1; |
| 408 | ncp->nc_locktd = td; |
| 409 | /* |
| 410 | * The vp associated with a locked ncp must be held |
| 411 | * to prevent it from being recycled (which would |
| 412 | * cause the ncp to become unresolved). |
| 413 | * |
| 414 | * WARNING! If VRECLAIMED is set the vnode could |
| 415 | * already be in the middle of a recycle. Callers |
| 416 | * should not assume that nc_vp is usable when |
| 417 | * not NULL. cache_vref() or cache_vget() must be |
| 418 | * called. |
| 419 | * |
| 420 | * XXX loop on race for later MPSAFE work. |
| 421 | */ |
| 422 | if (ncp->nc_vp) |
| 423 | vhold(ncp->nc_vp); |
| 424 | break; |
| 425 | } |
| 426 | if (ncp->nc_locktd == td) { |
| 427 | ++ncp->nc_exlocks; |
| 428 | break; |
| 429 | } |
| 430 | ncp->nc_flag |= NCF_LOCKREQ; |
| 431 | if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) { |
| 432 | if (didwarn) |
| 433 | continue; |
| 434 | didwarn = 1; |
| 435 | kprintf("[diagnostic] cache_lock: blocked on %p", ncp); |
| 436 | kprintf(" \"%*.*s\"\n", |
| 437 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 438 | } |
| 439 | } |
| 440 | |
| 441 | if (didwarn == 1) { |
| 442 | kprintf("[diagnostic] cache_lock: unblocked %*.*s\n", |
| 443 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 444 | } |
| 445 | } |
| 446 | |
| 447 | void |
| 448 | cache_lock(struct nchandle *nch) |
| 449 | { |
| 450 | _cache_lock(nch->ncp); |
| 451 | } |
| 452 | |
| 453 | static |
| 454 | int |
| 455 | _cache_lock_nonblock(struct namecache *ncp) |
| 456 | { |
| 457 | thread_t td; |
| 458 | |
| 459 | KKASSERT(ncp->nc_refs != 0); |
| 460 | td = curthread; |
| 461 | if (ncp->nc_exlocks == 0) { |
| 462 | ncp->nc_exlocks = 1; |
| 463 | ncp->nc_locktd = td; |
| 464 | /* |
| 465 | * The vp associated with a locked ncp must be held |
| 466 | * to prevent it from being recycled (which would |
| 467 | * cause the ncp to become unresolved). |
| 468 | * |
| 469 | * WARNING! If VRECLAIMED is set the vnode could |
| 470 | * already be in the middle of a recycle. Callers |
| 471 | * should not assume that nc_vp is usable when |
| 472 | * not NULL. cache_vref() or cache_vget() must be |
| 473 | * called. |
| 474 | * |
| 475 | * XXX loop on race for later MPSAFE work. |
| 476 | */ |
| 477 | if (ncp->nc_vp) |
| 478 | vhold(ncp->nc_vp); |
| 479 | return(0); |
| 480 | } else { |
| 481 | return(EWOULDBLOCK); |
| 482 | } |
| 483 | } |
| 484 | |
| 485 | int |
| 486 | cache_lock_nonblock(struct nchandle *nch) |
| 487 | { |
| 488 | return(_cache_lock_nonblock(nch->ncp)); |
| 489 | } |
| 490 | |
| 491 | static |
| 492 | void |
| 493 | _cache_unlock(struct namecache *ncp) |
| 494 | { |
| 495 | thread_t td = curthread; |
| 496 | |
| 497 | KKASSERT(ncp->nc_refs > 0); |
| 498 | KKASSERT(ncp->nc_exlocks > 0); |
| 499 | KKASSERT(ncp->nc_locktd == td); |
| 500 | if (--ncp->nc_exlocks == 0) { |
| 501 | if (ncp->nc_vp) |
| 502 | vdrop(ncp->nc_vp); |
| 503 | ncp->nc_locktd = NULL; |
| 504 | if (ncp->nc_flag & NCF_LOCKREQ) { |
| 505 | ncp->nc_flag &= ~NCF_LOCKREQ; |
| 506 | wakeup(ncp); |
| 507 | } |
| 508 | } |
| 509 | } |
| 510 | |
| 511 | void |
| 512 | cache_unlock(struct nchandle *nch) |
| 513 | { |
| 514 | _cache_unlock(nch->ncp); |
| 515 | } |
| 516 | |
| 517 | /* |
| 518 | * ref-and-lock, unlock-and-deref functions. |
| 519 | * |
| 520 | * This function is primarily used by nlookup. Even though cache_lock |
| 521 | * holds the vnode, it is possible that the vnode may have already |
| 522 | * initiated a recyclement. We want cache_get() to return a definitively |
| 523 | * usable vnode or a definitively unresolved ncp. |
| 524 | */ |
| 525 | static |
| 526 | struct namecache * |
| 527 | _cache_get(struct namecache *ncp) |
| 528 | { |
| 529 | _cache_hold(ncp); |
| 530 | _cache_lock(ncp); |
| 531 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 532 | _cache_setunresolved(ncp); |
| 533 | return(ncp); |
| 534 | } |
| 535 | |
| 536 | /* |
| 537 | * note: the same nchandle can be passed for both arguments. |
| 538 | */ |
| 539 | void |
| 540 | cache_get(struct nchandle *nch, struct nchandle *target) |
| 541 | { |
| 542 | target->mount = nch->mount; |
| 543 | target->ncp = _cache_get(nch->ncp); |
| 544 | ++target->mount->mnt_refs; |
| 545 | } |
| 546 | |
| 547 | static int |
| 548 | _cache_get_nonblock(struct namecache *ncp) |
| 549 | { |
| 550 | /* XXX MP */ |
| 551 | if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) { |
| 552 | _cache_hold(ncp); |
| 553 | _cache_lock(ncp); |
| 554 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 555 | _cache_setunresolved(ncp); |
| 556 | return(0); |
| 557 | } |
| 558 | return(EWOULDBLOCK); |
| 559 | } |
| 560 | |
| 561 | int |
| 562 | cache_get_nonblock(struct nchandle *nch) |
| 563 | { |
| 564 | return(_cache_get_nonblock(nch->ncp)); |
| 565 | } |
| 566 | |
| 567 | static __inline |
| 568 | void |
| 569 | _cache_put(struct namecache *ncp) |
| 570 | { |
| 571 | _cache_unlock(ncp); |
| 572 | _cache_drop(ncp); |
| 573 | } |
| 574 | |
| 575 | void |
| 576 | cache_put(struct nchandle *nch) |
| 577 | { |
| 578 | --nch->mount->mnt_refs; |
| 579 | _cache_put(nch->ncp); |
| 580 | nch->ncp = NULL; |
| 581 | nch->mount = NULL; |
| 582 | } |
| 583 | |
| 584 | /* |
| 585 | * Resolve an unresolved ncp by associating a vnode with it. If the |
| 586 | * vnode is NULL, a negative cache entry is created. |
| 587 | * |
| 588 | * The ncp should be locked on entry and will remain locked on return. |
| 589 | */ |
| 590 | static |
| 591 | void |
| 592 | _cache_setvp(struct namecache *ncp, struct vnode *vp) |
| 593 | { |
| 594 | KKASSERT(ncp->nc_flag & NCF_UNRESOLVED); |
| 595 | ncp->nc_vp = vp; |
| 596 | if (vp != NULL) { |
| 597 | /* |
| 598 | * Any vp associated with an ncp which has children must |
| 599 | * be held. Any vp associated with a locked ncp must be held. |
| 600 | */ |
| 601 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 602 | vhold(vp); |
| 603 | TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode); |
| 604 | if (ncp->nc_exlocks) |
| 605 | vhold(vp); |
| 606 | |
| 607 | /* |
| 608 | * Set auxiliary flags |
| 609 | */ |
| 610 | switch(vp->v_type) { |
| 611 | case VDIR: |
| 612 | ncp->nc_flag |= NCF_ISDIR; |
| 613 | break; |
| 614 | case VLNK: |
| 615 | ncp->nc_flag |= NCF_ISSYMLINK; |
| 616 | /* XXX cache the contents of the symlink */ |
| 617 | break; |
| 618 | default: |
| 619 | break; |
| 620 | } |
| 621 | ++numcache; |
| 622 | ncp->nc_error = 0; |
| 623 | } else { |
| 624 | TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); |
| 625 | ++numneg; |
| 626 | ncp->nc_error = ENOENT; |
| 627 | } |
| 628 | ncp->nc_flag &= ~NCF_UNRESOLVED; |
| 629 | } |
| 630 | |
| 631 | void |
| 632 | cache_setvp(struct nchandle *nch, struct vnode *vp) |
| 633 | { |
| 634 | _cache_setvp(nch->ncp, vp); |
| 635 | } |
| 636 | |
| 637 | void |
| 638 | cache_settimeout(struct nchandle *nch, int nticks) |
| 639 | { |
| 640 | struct namecache *ncp = nch->ncp; |
| 641 | |
| 642 | if ((ncp->nc_timeout = ticks + nticks) == 0) |
| 643 | ncp->nc_timeout = 1; |
| 644 | } |
| 645 | |
| 646 | /* |
| 647 | * Disassociate the vnode or negative-cache association and mark a |
| 648 | * namecache entry as unresolved again. Note that the ncp is still |
| 649 | * left in the hash table and still linked to its parent. |
| 650 | * |
| 651 | * The ncp should be locked and refd on entry and will remain locked and refd |
| 652 | * on return. |
| 653 | * |
| 654 | * This routine is normally never called on a directory containing children. |
| 655 | * However, NFS often does just that in its rename() code as a cop-out to |
| 656 | * avoid complex namespace operations. This disconnects a directory vnode |
| 657 | * from its namecache and can cause the OLDAPI and NEWAPI to get out of |
| 658 | * sync. |
| 659 | * |
| 660 | * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as |
| 661 | * in a create, properly propogates flag up the chain. |
| 662 | */ |
| 663 | static |
| 664 | void |
| 665 | _cache_setunresolved(struct namecache *ncp) |
| 666 | { |
| 667 | struct vnode *vp; |
| 668 | |
| 669 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 670 | ncp->nc_flag |= NCF_UNRESOLVED; |
| 671 | ncp->nc_timeout = 0; |
| 672 | ncp->nc_error = ENOTCONN; |
| 673 | ++numunres; |
| 674 | if ((vp = ncp->nc_vp) != NULL) { |
| 675 | --numcache; |
| 676 | ncp->nc_vp = NULL; |
| 677 | TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode); |
| 678 | |
| 679 | /* |
| 680 | * Any vp associated with an ncp with children is |
| 681 | * held by that ncp. Any vp associated with a locked |
| 682 | * ncp is held by that ncp. These conditions must be |
| 683 | * undone when the vp is cleared out from the ncp. |
| 684 | */ |
| 685 | if (ncp->nc_flag & NCF_FSMID) |
| 686 | vupdatefsmid(vp); |
| 687 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 688 | vdrop(vp); |
| 689 | if (ncp->nc_exlocks) |
| 690 | vdrop(vp); |
| 691 | } else { |
| 692 | TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); |
| 693 | --numneg; |
| 694 | } |
| 695 | ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK| |
| 696 | NCF_FSMID); |
| 697 | } |
| 698 | } |
| 699 | |
| 700 | void |
| 701 | cache_setunresolved(struct nchandle *nch) |
| 702 | { |
| 703 | _cache_setunresolved(nch->ncp); |
| 704 | } |
| 705 | |
| 706 | /* |
| 707 | * Determine if we can clear NCF_ISMOUNTPT by scanning the mountlist |
| 708 | * looking for matches. This flag tells the lookup code when it must |
| 709 | * check for a mount linkage and also prevents the directories in question |
| 710 | * from being deleted or renamed. |
| 711 | */ |
| 712 | static |
| 713 | int |
| 714 | cache_clrmountpt_callback(struct mount *mp, void *data) |
| 715 | { |
| 716 | struct nchandle *nch = data; |
| 717 | |
| 718 | if (mp->mnt_ncmounton.ncp == nch->ncp) |
| 719 | return(1); |
| 720 | if (mp->mnt_ncmountpt.ncp == nch->ncp) |
| 721 | return(1); |
| 722 | return(0); |
| 723 | } |
| 724 | |
| 725 | void |
| 726 | cache_clrmountpt(struct nchandle *nch) |
| 727 | { |
| 728 | int count; |
| 729 | |
| 730 | count = mountlist_scan(cache_clrmountpt_callback, nch, |
| 731 | MNTSCAN_FORWARD|MNTSCAN_NOBUSY); |
| 732 | if (count == 0) |
| 733 | nch->ncp->nc_flag &= ~NCF_ISMOUNTPT; |
| 734 | } |
| 735 | |
| 736 | /* |
| 737 | * Invalidate portions of the namecache topology given a starting entry. |
| 738 | * The passed ncp is set to an unresolved state and: |
| 739 | * |
| 740 | * The passed ncp must be locked. |
| 741 | * |
| 742 | * CINV_DESTROY - Set a flag in the passed ncp entry indicating |
| 743 | * that the physical underlying nodes have been |
| 744 | * destroyed... as in deleted. For example, when |
| 745 | * a directory is removed. This will cause record |
| 746 | * lookups on the name to no longer be able to find |
| 747 | * the record and tells the resolver to return failure |
| 748 | * rather then trying to resolve through the parent. |
| 749 | * |
| 750 | * The topology itself, including ncp->nc_name, |
| 751 | * remains intact. |
| 752 | * |
| 753 | * This only applies to the passed ncp, if CINV_CHILDREN |
| 754 | * is specified the children are not flagged. |
| 755 | * |
| 756 | * CINV_CHILDREN - Set all children (recursively) to an unresolved |
| 757 | * state as well. |
| 758 | * |
| 759 | * Note that this will also have the side effect of |
| 760 | * cleaning out any unreferenced nodes in the topology |
| 761 | * from the leaves up as the recursion backs out. |
| 762 | * |
| 763 | * Note that the topology for any referenced nodes remains intact. |
| 764 | * |
| 765 | * It is possible for cache_inval() to race a cache_resolve(), meaning that |
| 766 | * the namecache entry may not actually be invalidated on return if it was |
| 767 | * revalidated while recursing down into its children. This code guarentees |
| 768 | * that the node(s) will go through an invalidation cycle, but does not |
| 769 | * guarentee that they will remain in an invalidated state. |
| 770 | * |
| 771 | * Returns non-zero if a revalidation was detected during the invalidation |
| 772 | * recursion, zero otherwise. Note that since only the original ncp is |
| 773 | * locked the revalidation ultimately can only indicate that the original ncp |
| 774 | * *MIGHT* no have been reresolved. |
| 775 | * |
| 776 | * DEEP RECURSION HANDLING - If a recursive invalidation recurses deeply we |
| 777 | * have to avoid blowing out the kernel stack. We do this by saving the |
| 778 | * deep namecache node and aborting the recursion, then re-recursing at that |
| 779 | * node using a depth-first algorithm in order to allow multiple deep |
| 780 | * recursions to chain through each other, then we restart the invalidation |
| 781 | * from scratch. |
| 782 | */ |
| 783 | |
| 784 | struct cinvtrack { |
| 785 | struct namecache *resume_ncp; |
| 786 | int depth; |
| 787 | }; |
| 788 | |
| 789 | static int _cache_inval_internal(struct namecache *, int, struct cinvtrack *); |
| 790 | |
| 791 | static |
| 792 | int |
| 793 | _cache_inval(struct namecache *ncp, int flags) |
| 794 | { |
| 795 | struct cinvtrack track; |
| 796 | struct namecache *ncp2; |
| 797 | int r; |
| 798 | |
| 799 | track.depth = 0; |
| 800 | track.resume_ncp = NULL; |
| 801 | |
| 802 | for (;;) { |
| 803 | r = _cache_inval_internal(ncp, flags, &track); |
| 804 | if (track.resume_ncp == NULL) |
| 805 | break; |
| 806 | kprintf("Warning: deep namecache recursion at %s\n", |
| 807 | ncp->nc_name); |
| 808 | _cache_unlock(ncp); |
| 809 | while ((ncp2 = track.resume_ncp) != NULL) { |
| 810 | track.resume_ncp = NULL; |
| 811 | _cache_lock(ncp2); |
| 812 | _cache_inval_internal(ncp2, flags & ~CINV_DESTROY, |
| 813 | &track); |
| 814 | _cache_put(ncp2); |
| 815 | } |
| 816 | _cache_lock(ncp); |
| 817 | } |
| 818 | return(r); |
| 819 | } |
| 820 | |
| 821 | int |
| 822 | cache_inval(struct nchandle *nch, int flags) |
| 823 | { |
| 824 | return(_cache_inval(nch->ncp, flags)); |
| 825 | } |
| 826 | |
| 827 | static int |
| 828 | _cache_inval_internal(struct namecache *ncp, int flags, struct cinvtrack *track) |
| 829 | { |
| 830 | struct namecache *kid; |
| 831 | struct namecache *nextkid; |
| 832 | int rcnt = 0; |
| 833 | |
| 834 | KKASSERT(ncp->nc_exlocks); |
| 835 | |
| 836 | _cache_setunresolved(ncp); |
| 837 | if (flags & CINV_DESTROY) |
| 838 | ncp->nc_flag |= NCF_DESTROYED; |
| 839 | |
| 840 | if ((flags & CINV_CHILDREN) && |
| 841 | (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL |
| 842 | ) { |
| 843 | if (++track->depth > MAX_RECURSION_DEPTH) { |
| 844 | track->resume_ncp = ncp; |
| 845 | _cache_hold(ncp); |
| 846 | ++rcnt; |
| 847 | } |
| 848 | _cache_hold(kid); |
| 849 | _cache_unlock(ncp); |
| 850 | while (kid) { |
| 851 | if (track->resume_ncp) { |
| 852 | _cache_drop(kid); |
| 853 | break; |
| 854 | } |
| 855 | if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL) |
| 856 | _cache_hold(nextkid); |
| 857 | if ((kid->nc_flag & NCF_UNRESOLVED) == 0 || |
| 858 | TAILQ_FIRST(&kid->nc_list) |
| 859 | ) { |
| 860 | _cache_lock(kid); |
| 861 | rcnt += _cache_inval_internal(kid, flags & ~CINV_DESTROY, track); |
| 862 | _cache_unlock(kid); |
| 863 | } |
| 864 | _cache_drop(kid); |
| 865 | kid = nextkid; |
| 866 | } |
| 867 | --track->depth; |
| 868 | _cache_lock(ncp); |
| 869 | } |
| 870 | |
| 871 | /* |
| 872 | * Someone could have gotten in there while ncp was unlocked, |
| 873 | * retry if so. |
| 874 | */ |
| 875 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) |
| 876 | ++rcnt; |
| 877 | return (rcnt); |
| 878 | } |
| 879 | |
| 880 | /* |
| 881 | * Invalidate a vnode's namecache associations. To avoid races against |
| 882 | * the resolver we do not invalidate a node which we previously invalidated |
| 883 | * but which was then re-resolved while we were in the invalidation loop. |
| 884 | * |
| 885 | * Returns non-zero if any namecache entries remain after the invalidation |
| 886 | * loop completed. |
| 887 | * |
| 888 | * NOTE: unlike the namecache topology which guarentees that ncp's will not |
| 889 | * be ripped out of the topology while held, the vnode's v_namecache list |
| 890 | * has no such restriction. NCP's can be ripped out of the list at virtually |
| 891 | * any time if not locked, even if held. |
| 892 | */ |
| 893 | int |
| 894 | cache_inval_vp(struct vnode *vp, int flags) |
| 895 | { |
| 896 | struct namecache *ncp; |
| 897 | struct namecache *next; |
| 898 | |
| 899 | restart: |
| 900 | ncp = TAILQ_FIRST(&vp->v_namecache); |
| 901 | if (ncp) |
| 902 | _cache_hold(ncp); |
| 903 | while (ncp) { |
| 904 | /* loop entered with ncp held */ |
| 905 | if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) |
| 906 | _cache_hold(next); |
| 907 | _cache_lock(ncp); |
| 908 | if (ncp->nc_vp != vp) { |
| 909 | kprintf("Warning: cache_inval_vp: race-A detected on " |
| 910 | "%s\n", ncp->nc_name); |
| 911 | _cache_put(ncp); |
| 912 | if (next) |
| 913 | _cache_drop(next); |
| 914 | goto restart; |
| 915 | } |
| 916 | _cache_inval(ncp, flags); |
| 917 | _cache_put(ncp); /* also releases reference */ |
| 918 | ncp = next; |
| 919 | if (ncp && ncp->nc_vp != vp) { |
| 920 | kprintf("Warning: cache_inval_vp: race-B detected on " |
| 921 | "%s\n", ncp->nc_name); |
| 922 | _cache_drop(ncp); |
| 923 | goto restart; |
| 924 | } |
| 925 | } |
| 926 | return(TAILQ_FIRST(&vp->v_namecache) != NULL); |
| 927 | } |
| 928 | |
| 929 | /* |
| 930 | * This routine is used instead of the normal cache_inval_vp() when we |
| 931 | * are trying to recycle otherwise good vnodes. |
| 932 | * |
| 933 | * Return 0 on success, non-zero if not all namecache records could be |
| 934 | * disassociated from the vnode (for various reasons). |
| 935 | */ |
| 936 | int |
| 937 | cache_inval_vp_nonblock(struct vnode *vp) |
| 938 | { |
| 939 | struct namecache *ncp; |
| 940 | struct namecache *next; |
| 941 | |
| 942 | ncp = TAILQ_FIRST(&vp->v_namecache); |
| 943 | if (ncp) |
| 944 | _cache_hold(ncp); |
| 945 | while (ncp) { |
| 946 | /* loop entered with ncp held */ |
| 947 | if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL) |
| 948 | _cache_hold(next); |
| 949 | if (_cache_lock_nonblock(ncp)) { |
| 950 | _cache_drop(ncp); |
| 951 | if (next) |
| 952 | _cache_drop(next); |
| 953 | break; |
| 954 | } |
| 955 | if (ncp->nc_vp != vp) { |
| 956 | kprintf("Warning: cache_inval_vp: race-A detected on " |
| 957 | "%s\n", ncp->nc_name); |
| 958 | _cache_put(ncp); |
| 959 | if (next) |
| 960 | _cache_drop(next); |
| 961 | break; |
| 962 | } |
| 963 | _cache_inval(ncp, 0); |
| 964 | _cache_put(ncp); /* also releases reference */ |
| 965 | ncp = next; |
| 966 | if (ncp && ncp->nc_vp != vp) { |
| 967 | kprintf("Warning: cache_inval_vp: race-B detected on " |
| 968 | "%s\n", ncp->nc_name); |
| 969 | _cache_drop(ncp); |
| 970 | break; |
| 971 | } |
| 972 | } |
| 973 | return(TAILQ_FIRST(&vp->v_namecache) != NULL); |
| 974 | } |
| 975 | |
| 976 | /* |
| 977 | * The source ncp has been renamed to the target ncp. Both fncp and tncp |
| 978 | * must be locked. Both will be set to unresolved, any children of tncp |
| 979 | * will be disconnected (the prior contents of the target is assumed to be |
| 980 | * destroyed by the rename operation, e.g. renaming over an empty directory), |
| 981 | * and all children of fncp will be moved to tncp. |
| 982 | * |
| 983 | * XXX the disconnection could pose a problem, check code paths to make |
| 984 | * sure any code that blocks can handle the parent being changed out from |
| 985 | * under it. Maybe we should lock the children (watch out for deadlocks) ? |
| 986 | * |
| 987 | * After we return the caller has the option of calling cache_setvp() if |
| 988 | * the vnode of the new target ncp is known. |
| 989 | * |
| 990 | * Any process CD'd into any of the children will no longer be able to ".." |
| 991 | * back out. An rm -rf can cause this situation to occur. |
| 992 | */ |
| 993 | void |
| 994 | cache_rename(struct nchandle *fnch, struct nchandle *tnch) |
| 995 | { |
| 996 | struct namecache *fncp = fnch->ncp; |
| 997 | struct namecache *tncp = tnch->ncp; |
| 998 | struct namecache *scan; |
| 999 | int didwarn = 0; |
| 1000 | |
| 1001 | _cache_setunresolved(fncp); |
| 1002 | _cache_setunresolved(tncp); |
| 1003 | while (_cache_inval(tncp, CINV_CHILDREN) != 0) { |
| 1004 | if (didwarn++ % 10 == 0) { |
| 1005 | kprintf("Warning: cache_rename: race during " |
| 1006 | "rename %s->%s\n", |
| 1007 | fncp->nc_name, tncp->nc_name); |
| 1008 | } |
| 1009 | tsleep(tncp, 0, "mvrace", hz / 10); |
| 1010 | _cache_setunresolved(tncp); |
| 1011 | } |
| 1012 | while ((scan = TAILQ_FIRST(&fncp->nc_list)) != NULL) { |
| 1013 | _cache_hold(scan); |
| 1014 | cache_unlink_parent(scan); |
| 1015 | cache_link_parent(scan, tncp); |
| 1016 | if (scan->nc_flag & NCF_HASHED) |
| 1017 | _cache_rehash(scan); |
| 1018 | _cache_drop(scan); |
| 1019 | } |
| 1020 | } |
| 1021 | |
| 1022 | /* |
| 1023 | * vget the vnode associated with the namecache entry. Resolve the namecache |
| 1024 | * entry if necessary and deal with namecache/vp races. The passed ncp must |
| 1025 | * be referenced and may be locked. The ncp's ref/locking state is not |
| 1026 | * effected by this call. |
| 1027 | * |
| 1028 | * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked |
| 1029 | * (depending on the passed lk_type) will be returned in *vpp with an error |
| 1030 | * of 0, or NULL will be returned in *vpp with a non-0 error code. The |
| 1031 | * most typical error is ENOENT, meaning that the ncp represents a negative |
| 1032 | * cache hit and there is no vnode to retrieve, but other errors can occur |
| 1033 | * too. |
| 1034 | * |
| 1035 | * The main race we have to deal with are namecache zaps. The ncp itself |
| 1036 | * will not disappear since it is referenced, and it turns out that the |
| 1037 | * validity of the vp pointer can be checked simply by rechecking the |
| 1038 | * contents of ncp->nc_vp. |
| 1039 | */ |
| 1040 | int |
| 1041 | cache_vget(struct nchandle *nch, struct ucred *cred, |
| 1042 | int lk_type, struct vnode **vpp) |
| 1043 | { |
| 1044 | struct namecache *ncp; |
| 1045 | struct vnode *vp; |
| 1046 | int error; |
| 1047 | |
| 1048 | ncp = nch->ncp; |
| 1049 | again: |
| 1050 | vp = NULL; |
| 1051 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 1052 | _cache_lock(ncp); |
| 1053 | error = cache_resolve(nch, cred); |
| 1054 | _cache_unlock(ncp); |
| 1055 | } else { |
| 1056 | error = 0; |
| 1057 | } |
| 1058 | if (error == 0 && (vp = ncp->nc_vp) != NULL) { |
| 1059 | /* |
| 1060 | * Accessing the vnode from the namecache is a bit |
| 1061 | * dangerous. Because there are no refs on the vnode, it |
| 1062 | * could be in the middle of a reclaim. |
| 1063 | */ |
| 1064 | if (vp->v_flag & VRECLAIMED) { |
| 1065 | kprintf("Warning: vnode reclaim race detected in cache_vget on %p (%s)\n", vp, ncp->nc_name); |
| 1066 | _cache_lock(ncp); |
| 1067 | _cache_setunresolved(ncp); |
| 1068 | _cache_unlock(ncp); |
| 1069 | goto again; |
| 1070 | } |
| 1071 | error = vget(vp, lk_type); |
| 1072 | if (error) { |
| 1073 | if (vp != ncp->nc_vp) |
| 1074 | goto again; |
| 1075 | vp = NULL; |
| 1076 | } else if (vp != ncp->nc_vp) { |
| 1077 | vput(vp); |
| 1078 | goto again; |
| 1079 | } else if (vp->v_flag & VRECLAIMED) { |
| 1080 | panic("vget succeeded on a VRECLAIMED node! vp %p", vp); |
| 1081 | } |
| 1082 | } |
| 1083 | if (error == 0 && vp == NULL) |
| 1084 | error = ENOENT; |
| 1085 | *vpp = vp; |
| 1086 | return(error); |
| 1087 | } |
| 1088 | |
| 1089 | int |
| 1090 | cache_vref(struct nchandle *nch, struct ucred *cred, struct vnode **vpp) |
| 1091 | { |
| 1092 | struct namecache *ncp; |
| 1093 | struct vnode *vp; |
| 1094 | int error; |
| 1095 | |
| 1096 | ncp = nch->ncp; |
| 1097 | |
| 1098 | again: |
| 1099 | vp = NULL; |
| 1100 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 1101 | _cache_lock(ncp); |
| 1102 | error = cache_resolve(nch, cred); |
| 1103 | _cache_unlock(ncp); |
| 1104 | } else { |
| 1105 | error = 0; |
| 1106 | } |
| 1107 | if (error == 0 && (vp = ncp->nc_vp) != NULL) { |
| 1108 | /* |
| 1109 | * Since we did not obtain any locks, a cache zap |
| 1110 | * race can occur here if the vnode is in the middle |
| 1111 | * of being reclaimed and has not yet been able to |
| 1112 | * clean out its cache node. If that case occurs, |
| 1113 | * we must lock and unresolve the cache, then loop |
| 1114 | * to retry. |
| 1115 | */ |
| 1116 | if ((error = vget(vp, LK_SHARED)) != 0) { |
| 1117 | if (error == ENOENT) { |
| 1118 | kprintf("Warning: vnode reclaim race detected on cache_vref %p (%s)\n", vp, ncp->nc_name); |
| 1119 | _cache_lock(ncp); |
| 1120 | _cache_setunresolved(ncp); |
| 1121 | _cache_unlock(ncp); |
| 1122 | goto again; |
| 1123 | } |
| 1124 | /* fatal error */ |
| 1125 | } else { |
| 1126 | /* caller does not want a lock */ |
| 1127 | vn_unlock(vp); |
| 1128 | } |
| 1129 | } |
| 1130 | if (error == 0 && vp == NULL) |
| 1131 | error = ENOENT; |
| 1132 | *vpp = vp; |
| 1133 | return(error); |
| 1134 | } |
| 1135 | |
| 1136 | /* |
| 1137 | * Recursively set the FSMID update flag for namecache nodes leading |
| 1138 | * to root. This will cause the next getattr or reclaim to increment the |
| 1139 | * fsmid and mark the inode for lazy updating. |
| 1140 | * |
| 1141 | * Stop recursing when we hit a node whos NCF_FSMID flag is already set. |
| 1142 | * This makes FSMIDs work in an Einsteinian fashion - where the observation |
| 1143 | * effects the result. In this case a program monitoring a higher level |
| 1144 | * node will have detected some prior change and started its scan (clearing |
| 1145 | * NCF_FSMID in higher level nodes), but since it has not yet observed the |
| 1146 | * node where we find NCF_FSMID still set, we can safely make the related |
| 1147 | * modification without interfering with the theorized program. |
| 1148 | * |
| 1149 | * This also means that FSMIDs cannot represent time-domain quantities |
| 1150 | * in a hierarchical sense. But the main reason for doing it this way |
| 1151 | * is to reduce the amount of recursion that occurs in the critical path |
| 1152 | * when e.g. a program is writing to a file that sits deep in a directory |
| 1153 | * hierarchy. |
| 1154 | */ |
| 1155 | void |
| 1156 | cache_update_fsmid(struct nchandle *nch) |
| 1157 | { |
| 1158 | struct namecache *ncp; |
| 1159 | struct namecache *scan; |
| 1160 | struct vnode *vp; |
| 1161 | |
| 1162 | ncp = nch->ncp; |
| 1163 | |
| 1164 | /* |
| 1165 | * Warning: even if we get a non-NULL vp it could still be in the |
| 1166 | * middle of a recyclement. Don't do anything fancy, just set |
| 1167 | * NCF_FSMID. |
| 1168 | */ |
| 1169 | if ((vp = ncp->nc_vp) != NULL) { |
| 1170 | TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { |
| 1171 | for (scan = ncp; scan; scan = scan->nc_parent) { |
| 1172 | if (scan->nc_flag & NCF_FSMID) |
| 1173 | break; |
| 1174 | scan->nc_flag |= NCF_FSMID; |
| 1175 | } |
| 1176 | } |
| 1177 | } else { |
| 1178 | while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) { |
| 1179 | ncp->nc_flag |= NCF_FSMID; |
| 1180 | ncp = ncp->nc_parent; |
| 1181 | } |
| 1182 | } |
| 1183 | } |
| 1184 | |
| 1185 | void |
| 1186 | cache_update_fsmid_vp(struct vnode *vp) |
| 1187 | { |
| 1188 | struct namecache *ncp; |
| 1189 | struct namecache *scan; |
| 1190 | |
| 1191 | TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { |
| 1192 | for (scan = ncp; scan; scan = scan->nc_parent) { |
| 1193 | if (scan->nc_flag & NCF_FSMID) |
| 1194 | break; |
| 1195 | scan->nc_flag |= NCF_FSMID; |
| 1196 | } |
| 1197 | } |
| 1198 | } |
| 1199 | |
| 1200 | /* |
| 1201 | * If getattr is called on a vnode (e.g. a stat call), the filesystem |
| 1202 | * may call this routine to determine if the namecache has the hierarchical |
| 1203 | * change flag set, requiring the fsmid to be updated. |
| 1204 | * |
| 1205 | * Since 0 indicates no support, make sure the filesystem fsmid is at least |
| 1206 | * 1. |
| 1207 | */ |
| 1208 | int |
| 1209 | cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid) |
| 1210 | { |
| 1211 | struct namecache *ncp; |
| 1212 | int changed = 0; |
| 1213 | |
| 1214 | TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { |
| 1215 | if (ncp->nc_flag & NCF_FSMID) { |
| 1216 | ncp->nc_flag &= ~NCF_FSMID; |
| 1217 | changed = 1; |
| 1218 | } |
| 1219 | } |
| 1220 | if (*fsmid == 0) |
| 1221 | ++*fsmid; |
| 1222 | if (changed) |
| 1223 | ++*fsmid; |
| 1224 | return(changed); |
| 1225 | } |
| 1226 | |
| 1227 | /* |
| 1228 | * Obtain the FSMID for a vnode for filesystems which do not support |
| 1229 | * a built-in FSMID. |
| 1230 | */ |
| 1231 | int64_t |
| 1232 | cache_sync_fsmid_vp(struct vnode *vp) |
| 1233 | { |
| 1234 | struct namecache *ncp; |
| 1235 | |
| 1236 | if ((ncp = TAILQ_FIRST(&vp->v_namecache)) != NULL) { |
| 1237 | if (ncp->nc_flag & NCF_FSMID) { |
| 1238 | ncp->nc_flag &= ~NCF_FSMID; |
| 1239 | ++ncp->nc_fsmid; |
| 1240 | } |
| 1241 | return(ncp->nc_fsmid); |
| 1242 | } |
| 1243 | return(VNOVAL); |
| 1244 | } |
| 1245 | |
| 1246 | /* |
| 1247 | * Convert a directory vnode to a namecache record without any other |
| 1248 | * knowledge of the topology. This ONLY works with directory vnodes and |
| 1249 | * is ONLY used by the NFS server. dvp must be refd but unlocked, and the |
| 1250 | * returned ncp (if not NULL) will be held and unlocked. |
| 1251 | * |
| 1252 | * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned. |
| 1253 | * If 'makeit' is 1 we attempt to track-down and create the namecache topology |
| 1254 | * for dvp. This will fail only if the directory has been deleted out from |
| 1255 | * under the caller. |
| 1256 | * |
| 1257 | * Callers must always check for a NULL return no matter the value of 'makeit'. |
| 1258 | * |
| 1259 | * To avoid underflowing the kernel stack each recursive call increments |
| 1260 | * the makeit variable. |
| 1261 | */ |
| 1262 | |
| 1263 | static int cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, |
| 1264 | struct vnode *dvp); |
| 1265 | static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, |
| 1266 | struct vnode **saved_dvp); |
| 1267 | |
| 1268 | int |
| 1269 | cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit, |
| 1270 | struct nchandle *nch) |
| 1271 | { |
| 1272 | struct vnode *saved_dvp; |
| 1273 | struct vnode *pvp; |
| 1274 | int error; |
| 1275 | |
| 1276 | nch->ncp = NULL; |
| 1277 | nch->mount = dvp->v_mount; |
| 1278 | saved_dvp = NULL; |
| 1279 | |
| 1280 | /* |
| 1281 | * Temporary debugging code to force the directory scanning code |
| 1282 | * to be exercised. |
| 1283 | */ |
| 1284 | if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) { |
| 1285 | nch->ncp = TAILQ_FIRST(&dvp->v_namecache); |
| 1286 | kprintf("cache_fromdvp: forcing %s\n", nch->ncp->nc_name); |
| 1287 | goto force; |
| 1288 | } |
| 1289 | |
| 1290 | /* |
| 1291 | * Loop until resolution, inside code will break out on error. |
| 1292 | */ |
| 1293 | while ((nch->ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) { |
| 1294 | force: |
| 1295 | /* |
| 1296 | * If dvp is the root of its filesystem it should already |
| 1297 | * have a namecache pointer associated with it as a side |
| 1298 | * effect of the mount, but it may have been disassociated. |
| 1299 | */ |
| 1300 | if (dvp->v_flag & VROOT) { |
| 1301 | nch->ncp = _cache_get(nch->mount->mnt_ncmountpt.ncp); |
| 1302 | error = cache_resolve_mp(nch->mount); |
| 1303 | _cache_put(nch->ncp); |
| 1304 | if (ncvp_debug) { |
| 1305 | kprintf("cache_fromdvp: resolve root of mount %p error %d", |
| 1306 | dvp->v_mount, error); |
| 1307 | } |
| 1308 | if (error) { |
| 1309 | if (ncvp_debug) |
| 1310 | kprintf(" failed\n"); |
| 1311 | nch->ncp = NULL; |
| 1312 | break; |
| 1313 | } |
| 1314 | if (ncvp_debug) |
| 1315 | kprintf(" succeeded\n"); |
| 1316 | continue; |
| 1317 | } |
| 1318 | |
| 1319 | /* |
| 1320 | * If we are recursed too deeply resort to an O(n^2) |
| 1321 | * algorithm to resolve the namecache topology. The |
| 1322 | * resolved pvp is left referenced in saved_dvp to |
| 1323 | * prevent the tree from being destroyed while we loop. |
| 1324 | */ |
| 1325 | if (makeit > 20) { |
| 1326 | error = cache_fromdvp_try(dvp, cred, &saved_dvp); |
| 1327 | if (error) { |
| 1328 | kprintf("lookupdotdot(longpath) failed %d " |
| 1329 | "dvp %p\n", error, dvp); |
| 1330 | break; |
| 1331 | } |
| 1332 | continue; |
| 1333 | } |
| 1334 | |
| 1335 | /* |
| 1336 | * Get the parent directory and resolve its ncp. |
| 1337 | */ |
| 1338 | error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); |
| 1339 | if (error) { |
| 1340 | kprintf("lookupdotdot failed %d dvp %p\n", error, dvp); |
| 1341 | break; |
| 1342 | } |
| 1343 | vn_unlock(pvp); |
| 1344 | |
| 1345 | /* |
| 1346 | * Reuse makeit as a recursion depth counter. |
| 1347 | */ |
| 1348 | cache_fromdvp(pvp, cred, makeit + 1, nch); |
| 1349 | vrele(pvp); |
| 1350 | if (nch->ncp == NULL) |
| 1351 | break; |
| 1352 | |
| 1353 | /* |
| 1354 | * Do an inefficient scan of pvp (embodied by ncp) to look |
| 1355 | * for dvp. This will create a namecache record for dvp on |
| 1356 | * success. We loop up to recheck on success. |
| 1357 | * |
| 1358 | * ncp and dvp are both held but not locked. |
| 1359 | */ |
| 1360 | error = cache_inefficient_scan(nch, cred, dvp); |
| 1361 | _cache_drop(nch->ncp); |
| 1362 | if (error) { |
| 1363 | kprintf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n", |
| 1364 | pvp, nch->ncp->nc_name, dvp); |
| 1365 | nch->ncp = NULL; |
| 1366 | break; |
| 1367 | } |
| 1368 | if (ncvp_debug) { |
| 1369 | kprintf("cache_fromdvp: scan %p (%s) succeeded\n", |
| 1370 | pvp, nch->ncp->nc_name); |
| 1371 | } |
| 1372 | } |
| 1373 | |
| 1374 | /* |
| 1375 | * hold it for real so the mount gets a ref |
| 1376 | */ |
| 1377 | if (nch->ncp) |
| 1378 | cache_hold(nch); |
| 1379 | if (saved_dvp) |
| 1380 | vrele(saved_dvp); |
| 1381 | if (nch->ncp) |
| 1382 | return (0); |
| 1383 | return (EINVAL); |
| 1384 | } |
| 1385 | |
| 1386 | /* |
| 1387 | * Go up the chain of parent directories until we find something |
| 1388 | * we can resolve into the namecache. This is very inefficient. |
| 1389 | */ |
| 1390 | static |
| 1391 | int |
| 1392 | cache_fromdvp_try(struct vnode *dvp, struct ucred *cred, |
| 1393 | struct vnode **saved_dvp) |
| 1394 | { |
| 1395 | struct nchandle nch; |
| 1396 | struct vnode *pvp; |
| 1397 | int error; |
| 1398 | static time_t last_fromdvp_report; |
| 1399 | |
| 1400 | /* |
| 1401 | * Loop getting the parent directory vnode until we get something we |
| 1402 | * can resolve in the namecache. |
| 1403 | */ |
| 1404 | vref(dvp); |
| 1405 | nch.mount = dvp->v_mount; |
| 1406 | |
| 1407 | for (;;) { |
| 1408 | error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred); |
| 1409 | if (error) { |
| 1410 | vrele(dvp); |
| 1411 | return (error); |
| 1412 | } |
| 1413 | vn_unlock(pvp); |
| 1414 | if ((nch.ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) { |
| 1415 | _cache_hold(nch.ncp); |
| 1416 | vrele(pvp); |
| 1417 | break; |
| 1418 | } |
| 1419 | if (pvp->v_flag & VROOT) { |
| 1420 | nch.ncp = _cache_get(pvp->v_mount->mnt_ncmountpt.ncp); |
| 1421 | error = cache_resolve_mp(nch.mount); |
| 1422 | _cache_unlock(nch.ncp); |
| 1423 | vrele(pvp); |
| 1424 | if (error) { |
| 1425 | _cache_drop(nch.ncp); |
| 1426 | vrele(dvp); |
| 1427 | return (error); |
| 1428 | } |
| 1429 | break; |
| 1430 | } |
| 1431 | vrele(dvp); |
| 1432 | dvp = pvp; |
| 1433 | } |
| 1434 | if (last_fromdvp_report != time_second) { |
| 1435 | last_fromdvp_report = time_second; |
| 1436 | kprintf("Warning: extremely inefficient path resolution on %s\n", |
| 1437 | nch.ncp->nc_name); |
| 1438 | } |
| 1439 | error = cache_inefficient_scan(&nch, cred, dvp); |
| 1440 | |
| 1441 | /* |
| 1442 | * Hopefully dvp now has a namecache record associated with it. |
| 1443 | * Leave it referenced to prevent the kernel from recycling the |
| 1444 | * vnode. Otherwise extremely long directory paths could result |
| 1445 | * in endless recycling. |
| 1446 | */ |
| 1447 | if (*saved_dvp) |
| 1448 | vrele(*saved_dvp); |
| 1449 | *saved_dvp = dvp; |
| 1450 | return (error); |
| 1451 | } |
| 1452 | |
| 1453 | |
| 1454 | /* |
| 1455 | * Do an inefficient scan of the directory represented by ncp looking for |
| 1456 | * the directory vnode dvp. ncp must be held but not locked on entry and |
| 1457 | * will be held on return. dvp must be refd but not locked on entry and |
| 1458 | * will remain refd on return. |
| 1459 | * |
| 1460 | * Why do this at all? Well, due to its stateless nature the NFS server |
| 1461 | * converts file handles directly to vnodes without necessarily going through |
| 1462 | * the namecache ops that would otherwise create the namecache topology |
| 1463 | * leading to the vnode. We could either (1) Change the namecache algorithms |
| 1464 | * to allow disconnect namecache records that are re-merged opportunistically, |
| 1465 | * or (2) Make the NFS server backtrack and scan to recover a connected |
| 1466 | * namecache topology in order to then be able to issue new API lookups. |
| 1467 | * |
| 1468 | * It turns out that (1) is a huge mess. It takes a nice clean set of |
| 1469 | * namecache algorithms and introduces a lot of complication in every subsystem |
| 1470 | * that calls into the namecache to deal with the re-merge case, especially |
| 1471 | * since we are using the namecache to placehold negative lookups and the |
| 1472 | * vnode might not be immediately assigned. (2) is certainly far less |
| 1473 | * efficient then (1), but since we are only talking about directories here |
| 1474 | * (which are likely to remain cached), the case does not actually run all |
| 1475 | * that often and has the supreme advantage of not polluting the namecache |
| 1476 | * algorithms. |
| 1477 | */ |
| 1478 | static int |
| 1479 | cache_inefficient_scan(struct nchandle *nch, struct ucred *cred, |
| 1480 | struct vnode *dvp) |
| 1481 | { |
| 1482 | struct nlcomponent nlc; |
| 1483 | struct nchandle rncp; |
| 1484 | struct dirent *den; |
| 1485 | struct vnode *pvp; |
| 1486 | struct vattr vat; |
| 1487 | struct iovec iov; |
| 1488 | struct uio uio; |
| 1489 | int blksize; |
| 1490 | int eofflag; |
| 1491 | int bytes; |
| 1492 | char *rbuf; |
| 1493 | int error; |
| 1494 | |
| 1495 | vat.va_blocksize = 0; |
| 1496 | if ((error = VOP_GETATTR(dvp, &vat)) != 0) |
| 1497 | return (error); |
| 1498 | if ((error = cache_vref(nch, cred, &pvp)) != 0) |
| 1499 | return (error); |
| 1500 | if (ncvp_debug) |
| 1501 | kprintf("inefficient_scan: directory iosize %ld vattr fileid = %lld\n", vat.va_blocksize, vat.va_fileid); |
| 1502 | if ((blksize = vat.va_blocksize) == 0) |
| 1503 | blksize = DEV_BSIZE; |
| 1504 | rbuf = kmalloc(blksize, M_TEMP, M_WAITOK); |
| 1505 | rncp.ncp = NULL; |
| 1506 | |
| 1507 | eofflag = 0; |
| 1508 | uio.uio_offset = 0; |
| 1509 | again: |
| 1510 | iov.iov_base = rbuf; |
| 1511 | iov.iov_len = blksize; |
| 1512 | uio.uio_iov = &iov; |
| 1513 | uio.uio_iovcnt = 1; |
| 1514 | uio.uio_resid = blksize; |
| 1515 | uio.uio_segflg = UIO_SYSSPACE; |
| 1516 | uio.uio_rw = UIO_READ; |
| 1517 | uio.uio_td = curthread; |
| 1518 | |
| 1519 | if (ncvp_debug >= 2) |
| 1520 | kprintf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset); |
| 1521 | error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL); |
| 1522 | if (error == 0) { |
| 1523 | den = (struct dirent *)rbuf; |
| 1524 | bytes = blksize - uio.uio_resid; |
| 1525 | |
| 1526 | while (bytes > 0) { |
| 1527 | if (ncvp_debug >= 2) { |
| 1528 | kprintf("cache_inefficient_scan: %*.*s\n", |
| 1529 | den->d_namlen, den->d_namlen, |
| 1530 | den->d_name); |
| 1531 | } |
| 1532 | if (den->d_type != DT_WHT && |
| 1533 | den->d_ino == vat.va_fileid) { |
| 1534 | if (ncvp_debug) { |
| 1535 | kprintf("cache_inefficient_scan: " |
| 1536 | "MATCHED inode %lld path %s/%*.*s\n", |
| 1537 | vat.va_fileid, nch->ncp->nc_name, |
| 1538 | den->d_namlen, den->d_namlen, |
| 1539 | den->d_name); |
| 1540 | } |
| 1541 | nlc.nlc_nameptr = den->d_name; |
| 1542 | nlc.nlc_namelen = den->d_namlen; |
| 1543 | rncp = cache_nlookup(nch, &nlc); |
| 1544 | KKASSERT(rncp.ncp != NULL); |
| 1545 | break; |
| 1546 | } |
| 1547 | bytes -= _DIRENT_DIRSIZ(den); |
| 1548 | den = _DIRENT_NEXT(den); |
| 1549 | } |
| 1550 | if (rncp.ncp == NULL && eofflag == 0 && uio.uio_resid != blksize) |
| 1551 | goto again; |
| 1552 | } |
| 1553 | vrele(pvp); |
| 1554 | if (rncp.ncp) { |
| 1555 | if (rncp.ncp->nc_flag & NCF_UNRESOLVED) { |
| 1556 | _cache_setvp(rncp.ncp, dvp); |
| 1557 | if (ncvp_debug >= 2) { |
| 1558 | kprintf("cache_inefficient_scan: setvp %s/%s = %p\n", |
| 1559 | nch->ncp->nc_name, rncp.ncp->nc_name, dvp); |
| 1560 | } |
| 1561 | } else { |
| 1562 | if (ncvp_debug >= 2) { |
| 1563 | kprintf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n", |
| 1564 | nch->ncp->nc_name, rncp.ncp->nc_name, dvp, |
| 1565 | rncp.ncp->nc_vp); |
| 1566 | } |
| 1567 | } |
| 1568 | if (rncp.ncp->nc_vp == NULL) |
| 1569 | error = rncp.ncp->nc_error; |
| 1570 | _cache_put(rncp.ncp); |
| 1571 | } else { |
| 1572 | kprintf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n", |
| 1573 | dvp, nch->ncp->nc_name); |
| 1574 | error = ENOENT; |
| 1575 | } |
| 1576 | kfree(rbuf, M_TEMP); |
| 1577 | return (error); |
| 1578 | } |
| 1579 | |
| 1580 | /* |
| 1581 | * Zap a namecache entry. The ncp is unconditionally set to an unresolved |
| 1582 | * state, which disassociates it from its vnode or ncneglist. |
| 1583 | * |
| 1584 | * Then, if there are no additional references to the ncp and no children, |
| 1585 | * the ncp is removed from the topology and destroyed. This function will |
| 1586 | * also run through the nc_parent chain and destroy parent ncps if possible. |
| 1587 | * As a side benefit, it turns out the only conditions that allow running |
| 1588 | * up the chain are also the conditions to ensure no deadlock will occur. |
| 1589 | * |
| 1590 | * References and/or children may exist if the ncp is in the middle of the |
| 1591 | * topology, preventing the ncp from being destroyed. |
| 1592 | * |
| 1593 | * This function must be called with the ncp held and locked and will unlock |
| 1594 | * and drop it during zapping. |
| 1595 | */ |
| 1596 | static void |
| 1597 | cache_zap(struct namecache *ncp) |
| 1598 | { |
| 1599 | struct namecache *par; |
| 1600 | |
| 1601 | /* |
| 1602 | * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED. |
| 1603 | */ |
| 1604 | _cache_setunresolved(ncp); |
| 1605 | |
| 1606 | /* |
| 1607 | * Try to scrap the entry and possibly tail-recurse on its parent. |
| 1608 | * We only scrap unref'd (other then our ref) unresolved entries, |
| 1609 | * we do not scrap 'live' entries. |
| 1610 | */ |
| 1611 | while (ncp->nc_flag & NCF_UNRESOLVED) { |
| 1612 | /* |
| 1613 | * Someone other then us has a ref, stop. |
| 1614 | */ |
| 1615 | if (ncp->nc_refs > 1) |
| 1616 | goto done; |
| 1617 | |
| 1618 | /* |
| 1619 | * We have children, stop. |
| 1620 | */ |
| 1621 | if (!TAILQ_EMPTY(&ncp->nc_list)) |
| 1622 | goto done; |
| 1623 | |
| 1624 | /* |
| 1625 | * Remove ncp from the topology: hash table and parent linkage. |
| 1626 | */ |
| 1627 | if (ncp->nc_flag & NCF_HASHED) { |
| 1628 | ncp->nc_flag &= ~NCF_HASHED; |
| 1629 | LIST_REMOVE(ncp, nc_hash); |
| 1630 | } |
| 1631 | if ((par = ncp->nc_parent) != NULL) { |
| 1632 | par = _cache_hold(par); |
| 1633 | TAILQ_REMOVE(&par->nc_list, ncp, nc_entry); |
| 1634 | ncp->nc_parent = NULL; |
| 1635 | if (par->nc_vp && TAILQ_EMPTY(&par->nc_list)) |
| 1636 | vdrop(par->nc_vp); |
| 1637 | } |
| 1638 | |
| 1639 | /* |
| 1640 | * ncp should not have picked up any refs. Physically |
| 1641 | * destroy the ncp. |
| 1642 | */ |
| 1643 | KKASSERT(ncp->nc_refs == 1); |
| 1644 | --numunres; |
| 1645 | /* _cache_unlock(ncp) not required */ |
| 1646 | ncp->nc_refs = -1; /* safety */ |
| 1647 | if (ncp->nc_name) |
| 1648 | kfree(ncp->nc_name, M_VFSCACHE); |
| 1649 | kfree(ncp, M_VFSCACHE); |
| 1650 | |
| 1651 | /* |
| 1652 | * Loop on the parent (it may be NULL). Only bother looping |
| 1653 | * if the parent has a single ref (ours), which also means |
| 1654 | * we can lock it trivially. |
| 1655 | */ |
| 1656 | ncp = par; |
| 1657 | if (ncp == NULL) |
| 1658 | return; |
| 1659 | if (ncp->nc_refs != 1) { |
| 1660 | _cache_drop(ncp); |
| 1661 | return; |
| 1662 | } |
| 1663 | KKASSERT(par->nc_exlocks == 0); |
| 1664 | _cache_lock(ncp); |
| 1665 | } |
| 1666 | done: |
| 1667 | _cache_unlock(ncp); |
| 1668 | atomic_subtract_int(&ncp->nc_refs, 1); |
| 1669 | } |
| 1670 | |
| 1671 | static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW; |
| 1672 | |
| 1673 | static __inline |
| 1674 | void |
| 1675 | cache_hysteresis(void) |
| 1676 | { |
| 1677 | /* |
| 1678 | * Don't cache too many negative hits. We use hysteresis to reduce |
| 1679 | * the impact on the critical path. |
| 1680 | */ |
| 1681 | switch(cache_hysteresis_state) { |
| 1682 | case CHI_LOW: |
| 1683 | if (numneg > MINNEG && numneg * ncnegfactor > numcache) { |
| 1684 | cache_cleanneg(10); |
| 1685 | cache_hysteresis_state = CHI_HIGH; |
| 1686 | } |
| 1687 | break; |
| 1688 | case CHI_HIGH: |
| 1689 | if (numneg > MINNEG * 9 / 10 && |
| 1690 | numneg * ncnegfactor * 9 / 10 > numcache |
| 1691 | ) { |
| 1692 | cache_cleanneg(10); |
| 1693 | } else { |
| 1694 | cache_hysteresis_state = CHI_LOW; |
| 1695 | } |
| 1696 | break; |
| 1697 | } |
| 1698 | } |
| 1699 | |
| 1700 | /* |
| 1701 | * NEW NAMECACHE LOOKUP API |
| 1702 | * |
| 1703 | * Lookup an entry in the cache. A locked, referenced, non-NULL |
| 1704 | * entry is *always* returned, even if the supplied component is illegal. |
| 1705 | * The resulting namecache entry should be returned to the system with |
| 1706 | * cache_put() or _cache_unlock() + cache_drop(). |
| 1707 | * |
| 1708 | * namecache locks are recursive but care must be taken to avoid lock order |
| 1709 | * reversals. |
| 1710 | * |
| 1711 | * Nobody else will be able to manipulate the associated namespace (e.g. |
| 1712 | * create, delete, rename, rename-target) until the caller unlocks the |
| 1713 | * entry. |
| 1714 | * |
| 1715 | * The returned entry will be in one of three states: positive hit (non-null |
| 1716 | * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set). |
| 1717 | * Unresolved entries must be resolved through the filesystem to associate the |
| 1718 | * vnode and/or determine whether a positive or negative hit has occured. |
| 1719 | * |
| 1720 | * It is not necessary to lock a directory in order to lock namespace under |
| 1721 | * that directory. In fact, it is explicitly not allowed to do that. A |
| 1722 | * directory is typically only locked when being created, renamed, or |
| 1723 | * destroyed. |
| 1724 | * |
| 1725 | * The directory (par) may be unresolved, in which case any returned child |
| 1726 | * will likely also be marked unresolved. Likely but not guarenteed. Since |
| 1727 | * the filesystem lookup requires a resolved directory vnode the caller is |
| 1728 | * responsible for resolving the namecache chain top-down. This API |
| 1729 | * specifically allows whole chains to be created in an unresolved state. |
| 1730 | */ |
| 1731 | struct nchandle |
| 1732 | cache_nlookup(struct nchandle *par_nch, struct nlcomponent *nlc) |
| 1733 | { |
| 1734 | struct nchandle nch; |
| 1735 | struct namecache *ncp; |
| 1736 | struct namecache *new_ncp; |
| 1737 | struct nchashhead *nchpp; |
| 1738 | u_int32_t hash; |
| 1739 | globaldata_t gd; |
| 1740 | |
| 1741 | numcalls++; |
| 1742 | gd = mycpu; |
| 1743 | |
| 1744 | /* |
| 1745 | * Try to locate an existing entry |
| 1746 | */ |
| 1747 | hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT); |
| 1748 | hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash); |
| 1749 | new_ncp = NULL; |
| 1750 | restart: |
| 1751 | LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { |
| 1752 | numchecks++; |
| 1753 | |
| 1754 | /* |
| 1755 | * Try to zap entries that have timed out. We have |
| 1756 | * to be careful here because locked leafs may depend |
| 1757 | * on the vnode remaining intact in a parent, so only |
| 1758 | * do this under very specific conditions. |
| 1759 | */ |
| 1760 | if (ncp->nc_timeout && |
| 1761 | (int)(ncp->nc_timeout - ticks) < 0 && |
| 1762 | (ncp->nc_flag & NCF_UNRESOLVED) == 0 && |
| 1763 | ncp->nc_exlocks == 0 && |
| 1764 | TAILQ_EMPTY(&ncp->nc_list) |
| 1765 | ) { |
| 1766 | cache_zap(_cache_get(ncp)); |
| 1767 | goto restart; |
| 1768 | } |
| 1769 | |
| 1770 | /* |
| 1771 | * Break out if we find a matching entry. Note that |
| 1772 | * UNRESOLVED entries may match, but DESTROYED entries |
| 1773 | * do not. |
| 1774 | */ |
| 1775 | if (ncp->nc_parent == par_nch->ncp && |
| 1776 | ncp->nc_nlen == nlc->nlc_namelen && |
| 1777 | bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 && |
| 1778 | (ncp->nc_flag & NCF_DESTROYED) == 0 |
| 1779 | ) { |
| 1780 | if (_cache_get_nonblock(ncp) == 0) { |
| 1781 | if (new_ncp) |
| 1782 | _cache_free(new_ncp); |
| 1783 | goto found; |
| 1784 | } |
| 1785 | _cache_get(ncp); |
| 1786 | _cache_put(ncp); |
| 1787 | goto restart; |
| 1788 | } |
| 1789 | } |
| 1790 | |
| 1791 | /* |
| 1792 | * We failed to locate an entry, create a new entry and add it to |
| 1793 | * the cache. We have to relookup after possibly blocking in |
| 1794 | * malloc. |
| 1795 | */ |
| 1796 | if (new_ncp == NULL) { |
| 1797 | new_ncp = cache_alloc(nlc->nlc_namelen); |
| 1798 | goto restart; |
| 1799 | } |
| 1800 | |
| 1801 | ncp = new_ncp; |
| 1802 | |
| 1803 | /* |
| 1804 | * Initialize as a new UNRESOLVED entry, lock (non-blocking), |
| 1805 | * and link to the parent. The mount point is usually inherited |
| 1806 | * from the parent unless this is a special case such as a mount |
| 1807 | * point where nlc_namelen is 0. If nlc_namelen is 0 nc_name will |
| 1808 | * be NULL. |
| 1809 | */ |
| 1810 | if (nlc->nlc_namelen) { |
| 1811 | bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen); |
| 1812 | ncp->nc_name[nlc->nlc_namelen] = 0; |
| 1813 | } |
| 1814 | nchpp = NCHHASH(hash); |
| 1815 | LIST_INSERT_HEAD(nchpp, ncp, nc_hash); |
| 1816 | ncp->nc_flag |= NCF_HASHED; |
| 1817 | cache_link_parent(ncp, par_nch->ncp); |
| 1818 | found: |
| 1819 | /* |
| 1820 | * stats and namecache size management |
| 1821 | */ |
| 1822 | if (ncp->nc_flag & NCF_UNRESOLVED) |
| 1823 | ++gd->gd_nchstats->ncs_miss; |
| 1824 | else if (ncp->nc_vp) |
| 1825 | ++gd->gd_nchstats->ncs_goodhits; |
| 1826 | else |
| 1827 | ++gd->gd_nchstats->ncs_neghits; |
| 1828 | cache_hysteresis(); |
| 1829 | nch.mount = par_nch->mount; |
| 1830 | nch.ncp = ncp; |
| 1831 | ++nch.mount->mnt_refs; |
| 1832 | return(nch); |
| 1833 | } |
| 1834 | |
| 1835 | /* |
| 1836 | * The namecache entry is marked as being used as a mount point. |
| 1837 | * Locate the mount if it is visible to the caller. |
| 1838 | */ |
| 1839 | struct findmount_info { |
| 1840 | struct mount *result; |
| 1841 | struct mount *nch_mount; |
| 1842 | struct namecache *nch_ncp; |
| 1843 | }; |
| 1844 | |
| 1845 | static |
| 1846 | int |
| 1847 | cache_findmount_callback(struct mount *mp, void *data) |
| 1848 | { |
| 1849 | struct findmount_info *info = data; |
| 1850 | |
| 1851 | /* |
| 1852 | * Check the mount's mounted-on point against the passed nch. |
| 1853 | */ |
| 1854 | if (mp->mnt_ncmounton.mount == info->nch_mount && |
| 1855 | mp->mnt_ncmounton.ncp == info->nch_ncp |
| 1856 | ) { |
| 1857 | info->result = mp; |
| 1858 | return(-1); |
| 1859 | } |
| 1860 | return(0); |
| 1861 | } |
| 1862 | |
| 1863 | struct mount * |
| 1864 | cache_findmount(struct nchandle *nch) |
| 1865 | { |
| 1866 | struct findmount_info info; |
| 1867 | |
| 1868 | info.result = NULL; |
| 1869 | info.nch_mount = nch->mount; |
| 1870 | info.nch_ncp = nch->ncp; |
| 1871 | mountlist_scan(cache_findmount_callback, &info, |
| 1872 | MNTSCAN_FORWARD|MNTSCAN_NOBUSY); |
| 1873 | return(info.result); |
| 1874 | } |
| 1875 | |
| 1876 | /* |
| 1877 | * Resolve an unresolved namecache entry, generally by looking it up. |
| 1878 | * The passed ncp must be locked and refd. |
| 1879 | * |
| 1880 | * Theoretically since a vnode cannot be recycled while held, and since |
| 1881 | * the nc_parent chain holds its vnode as long as children exist, the |
| 1882 | * direct parent of the cache entry we are trying to resolve should |
| 1883 | * have a valid vnode. If not then generate an error that we can |
| 1884 | * determine is related to a resolver bug. |
| 1885 | * |
| 1886 | * However, if a vnode was in the middle of a recyclement when the NCP |
| 1887 | * got locked, ncp->nc_vp might point to a vnode that is about to become |
| 1888 | * invalid. cache_resolve() handles this case by unresolving the entry |
| 1889 | * and then re-resolving it. |
| 1890 | * |
| 1891 | * Note that successful resolution does not necessarily return an error |
| 1892 | * code of 0. If the ncp resolves to a negative cache hit then ENOENT |
| 1893 | * will be returned. |
| 1894 | */ |
| 1895 | int |
| 1896 | cache_resolve(struct nchandle *nch, struct ucred *cred) |
| 1897 | { |
| 1898 | struct namecache *par; |
| 1899 | struct namecache *ncp; |
| 1900 | struct nchandle nctmp; |
| 1901 | struct mount *mp; |
| 1902 | struct vnode *dvp; |
| 1903 | int error; |
| 1904 | |
| 1905 | ncp = nch->ncp; |
| 1906 | mp = nch->mount; |
| 1907 | restart: |
| 1908 | /* |
| 1909 | * If the ncp is already resolved we have nothing to do. However, |
| 1910 | * we do want to guarentee that a usable vnode is returned when |
| 1911 | * a vnode is present, so make sure it hasn't been reclaimed. |
| 1912 | */ |
| 1913 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 1914 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 1915 | _cache_setunresolved(ncp); |
| 1916 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) |
| 1917 | return (ncp->nc_error); |
| 1918 | } |
| 1919 | |
| 1920 | /* |
| 1921 | * Mount points need special handling because the parent does not |
| 1922 | * belong to the same filesystem as the ncp. |
| 1923 | */ |
| 1924 | if (ncp == mp->mnt_ncmountpt.ncp) |
| 1925 | return (cache_resolve_mp(mp)); |
| 1926 | |
| 1927 | /* |
| 1928 | * We expect an unbroken chain of ncps to at least the mount point, |
| 1929 | * and even all the way to root (but this code doesn't have to go |
| 1930 | * past the mount point). |
| 1931 | */ |
| 1932 | if (ncp->nc_parent == NULL) { |
| 1933 | kprintf("EXDEV case 1 %p %*.*s\n", ncp, |
| 1934 | ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 1935 | ncp->nc_error = EXDEV; |
| 1936 | return(ncp->nc_error); |
| 1937 | } |
| 1938 | |
| 1939 | /* |
| 1940 | * The vp's of the parent directories in the chain are held via vhold() |
| 1941 | * due to the existance of the child, and should not disappear. |
| 1942 | * However, there are cases where they can disappear: |
| 1943 | * |
| 1944 | * - due to filesystem I/O errors. |
| 1945 | * - due to NFS being stupid about tracking the namespace and |
| 1946 | * destroys the namespace for entire directories quite often. |
| 1947 | * - due to forced unmounts. |
| 1948 | * - due to an rmdir (parent will be marked DESTROYED) |
| 1949 | * |
| 1950 | * When this occurs we have to track the chain backwards and resolve |
| 1951 | * it, looping until the resolver catches up to the current node. We |
| 1952 | * could recurse here but we might run ourselves out of kernel stack |
| 1953 | * so we do it in a more painful manner. This situation really should |
| 1954 | * not occur all that often, or if it does not have to go back too |
| 1955 | * many nodes to resolve the ncp. |
| 1956 | */ |
| 1957 | while (ncp->nc_parent->nc_vp == NULL) { |
| 1958 | /* |
| 1959 | * This case can occur if a process is CD'd into a |
| 1960 | * directory which is then rmdir'd. If the parent is marked |
| 1961 | * destroyed there is no point trying to resolve it. |
| 1962 | */ |
| 1963 | if (ncp->nc_parent->nc_flag & NCF_DESTROYED) |
| 1964 | return(ENOENT); |
| 1965 | |
| 1966 | par = ncp->nc_parent; |
| 1967 | while (par->nc_parent && par->nc_parent->nc_vp == NULL) |
| 1968 | par = par->nc_parent; |
| 1969 | if (par->nc_parent == NULL) { |
| 1970 | kprintf("EXDEV case 2 %*.*s\n", |
| 1971 | par->nc_nlen, par->nc_nlen, par->nc_name); |
| 1972 | return (EXDEV); |
| 1973 | } |
| 1974 | kprintf("[diagnostic] cache_resolve: had to recurse on %*.*s\n", |
| 1975 | par->nc_nlen, par->nc_nlen, par->nc_name); |
| 1976 | /* |
| 1977 | * The parent is not set in stone, ref and lock it to prevent |
| 1978 | * it from disappearing. Also note that due to renames it |
| 1979 | * is possible for our ncp to move and for par to no longer |
| 1980 | * be one of its parents. We resolve it anyway, the loop |
| 1981 | * will handle any moves. |
| 1982 | */ |
| 1983 | _cache_get(par); |
| 1984 | if (par == nch->mount->mnt_ncmountpt.ncp) { |
| 1985 | cache_resolve_mp(nch->mount); |
| 1986 | } else if ((dvp = par->nc_parent->nc_vp) == NULL) { |
| 1987 | kprintf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name); |
| 1988 | _cache_put(par); |
| 1989 | continue; |
| 1990 | } else if (par->nc_flag & NCF_UNRESOLVED) { |
| 1991 | /* vhold(dvp); - DVP can't go away */ |
| 1992 | nctmp.mount = mp; |
| 1993 | nctmp.ncp = par; |
| 1994 | par->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); |
| 1995 | /* vdrop(dvp); */ |
| 1996 | } |
| 1997 | if ((error = par->nc_error) != 0) { |
| 1998 | if (par->nc_error != EAGAIN) { |
| 1999 | kprintf("EXDEV case 3 %*.*s error %d\n", |
| 2000 | par->nc_nlen, par->nc_nlen, par->nc_name, |
| 2001 | par->nc_error); |
| 2002 | _cache_put(par); |
| 2003 | return(error); |
| 2004 | } |
| 2005 | kprintf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n", |
| 2006 | par, par->nc_nlen, par->nc_nlen, par->nc_name); |
| 2007 | } |
| 2008 | _cache_put(par); |
| 2009 | /* loop */ |
| 2010 | } |
| 2011 | |
| 2012 | /* |
| 2013 | * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected |
| 2014 | * ncp's and reattach them. If this occurs the original ncp is marked |
| 2015 | * EAGAIN to force a relookup. |
| 2016 | * |
| 2017 | * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed |
| 2018 | * ncp must already be resolved. |
| 2019 | */ |
| 2020 | dvp = ncp->nc_parent->nc_vp; |
| 2021 | /* vhold(dvp); - dvp can't go away */ |
| 2022 | nctmp.mount = mp; |
| 2023 | nctmp.ncp = ncp; |
| 2024 | ncp->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred); |
| 2025 | /* vdrop(dvp); */ |
| 2026 | if (ncp->nc_error == EAGAIN) { |
| 2027 | kprintf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n", |
| 2028 | ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name); |
| 2029 | goto restart; |
| 2030 | } |
| 2031 | return(ncp->nc_error); |
| 2032 | } |
| 2033 | |
| 2034 | /* |
| 2035 | * Resolve the ncp associated with a mount point. Such ncp's almost always |
| 2036 | * remain resolved and this routine is rarely called. NFS MPs tends to force |
| 2037 | * re-resolution more often due to its mac-truck-smash-the-namecache |
| 2038 | * method of tracking namespace changes. |
| 2039 | * |
| 2040 | * The semantics for this call is that the passed ncp must be locked on |
| 2041 | * entry and will be locked on return. However, if we actually have to |
| 2042 | * resolve the mount point we temporarily unlock the entry in order to |
| 2043 | * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of |
| 2044 | * the unlock we have to recheck the flags after we relock. |
| 2045 | */ |
| 2046 | static int |
| 2047 | cache_resolve_mp(struct mount *mp) |
| 2048 | { |
| 2049 | struct namecache *ncp = mp->mnt_ncmountpt.ncp; |
| 2050 | struct vnode *vp; |
| 2051 | int error; |
| 2052 | |
| 2053 | KKASSERT(mp != NULL); |
| 2054 | |
| 2055 | /* |
| 2056 | * If the ncp is already resolved we have nothing to do. However, |
| 2057 | * we do want to guarentee that a usable vnode is returned when |
| 2058 | * a vnode is present, so make sure it hasn't been reclaimed. |
| 2059 | */ |
| 2060 | if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) { |
| 2061 | if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) |
| 2062 | _cache_setunresolved(ncp); |
| 2063 | } |
| 2064 | |
| 2065 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 2066 | _cache_unlock(ncp); |
| 2067 | while (vfs_busy(mp, 0)) |
| 2068 | ; |
| 2069 | error = VFS_ROOT(mp, &vp); |
| 2070 | _cache_lock(ncp); |
| 2071 | |
| 2072 | /* |
| 2073 | * recheck the ncp state after relocking. |
| 2074 | */ |
| 2075 | if (ncp->nc_flag & NCF_UNRESOLVED) { |
| 2076 | ncp->nc_error = error; |
| 2077 | if (error == 0) { |
| 2078 | _cache_setvp(ncp, vp); |
| 2079 | vput(vp); |
| 2080 | } else { |
| 2081 | kprintf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp); |
| 2082 | _cache_setvp(ncp, NULL); |
| 2083 | } |
| 2084 | } else if (error == 0) { |
| 2085 | vput(vp); |
| 2086 | } |
| 2087 | vfs_unbusy(mp); |
| 2088 | } |
| 2089 | return(ncp->nc_error); |
| 2090 | } |
| 2091 | |
| 2092 | void |
| 2093 | cache_cleanneg(int count) |
| 2094 | { |
| 2095 | struct namecache *ncp; |
| 2096 | |
| 2097 | /* |
| 2098 | * Automode from the vnlru proc - clean out 10% of the negative cache |
| 2099 | * entries. |
| 2100 | */ |
| 2101 | if (count == 0) |
| 2102 | count = numneg / 10 + 1; |
| 2103 | |
| 2104 | /* |
| 2105 | * Attempt to clean out the specified number of negative cache |
| 2106 | * entries. |
| 2107 | */ |
| 2108 | while (count) { |
| 2109 | ncp = TAILQ_FIRST(&ncneglist); |
| 2110 | if (ncp == NULL) { |
| 2111 | KKASSERT(numneg == 0); |
| 2112 | break; |
| 2113 | } |
| 2114 | TAILQ_REMOVE(&ncneglist, ncp, nc_vnode); |
| 2115 | TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode); |
| 2116 | if (_cache_get_nonblock(ncp) == 0) |
| 2117 | cache_zap(ncp); |
| 2118 | --count; |
| 2119 | } |
| 2120 | } |
| 2121 | |
| 2122 | /* |
| 2123 | * Rehash a ncp. Rehashing is typically required if the name changes (should |
| 2124 | * not generally occur) or the parent link changes. This function will |
| 2125 | * unhash the ncp if the ncp is no longer hashable. |
| 2126 | */ |
| 2127 | static void |
| 2128 | _cache_rehash(struct namecache *ncp) |
| 2129 | { |
| 2130 | struct nchashhead *nchpp; |
| 2131 | u_int32_t hash; |
| 2132 | |
| 2133 | if (ncp->nc_flag & NCF_HASHED) { |
| 2134 | ncp->nc_flag &= ~NCF_HASHED; |
| 2135 | LIST_REMOVE(ncp, nc_hash); |
| 2136 | } |
| 2137 | if (ncp->nc_nlen && ncp->nc_parent) { |
| 2138 | hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT); |
| 2139 | hash = fnv_32_buf(&ncp->nc_parent, |
| 2140 | sizeof(ncp->nc_parent), hash); |
| 2141 | nchpp = NCHHASH(hash); |
| 2142 | LIST_INSERT_HEAD(nchpp, ncp, nc_hash); |
| 2143 | ncp->nc_flag |= NCF_HASHED; |
| 2144 | } |
| 2145 | } |
| 2146 | |
| 2147 | /* |
| 2148 | * Name cache initialization, from vfsinit() when we are booting |
| 2149 | */ |
| 2150 | void |
| 2151 | nchinit(void) |
| 2152 | { |
| 2153 | int i; |
| 2154 | globaldata_t gd; |
| 2155 | |
| 2156 | /* initialise per-cpu namecache effectiveness statistics. */ |
| 2157 | for (i = 0; i < ncpus; ++i) { |
| 2158 | gd = globaldata_find(i); |
| 2159 | gd->gd_nchstats = &nchstats[i]; |
| 2160 | } |
| 2161 | TAILQ_INIT(&ncneglist); |
| 2162 | nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash); |
| 2163 | nclockwarn = 1 * hz; |
| 2164 | } |
| 2165 | |
| 2166 | /* |
| 2167 | * Called from start_init() to bootstrap the root filesystem. Returns |
| 2168 | * a referenced, unlocked namecache record. |
| 2169 | */ |
| 2170 | void |
| 2171 | cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp) |
| 2172 | { |
| 2173 | nch->ncp = cache_alloc(0); |
| 2174 | nch->mount = mp; |
| 2175 | ++mp->mnt_refs; |
| 2176 | if (vp) |
| 2177 | _cache_setvp(nch->ncp, vp); |
| 2178 | } |
| 2179 | |
| 2180 | /* |
| 2181 | * vfs_cache_setroot() |
| 2182 | * |
| 2183 | * Create an association between the root of our namecache and |
| 2184 | * the root vnode. This routine may be called several times during |
| 2185 | * booting. |
| 2186 | * |
| 2187 | * If the caller intends to save the returned namecache pointer somewhere |
| 2188 | * it must cache_hold() it. |
| 2189 | */ |
| 2190 | void |
| 2191 | vfs_cache_setroot(struct vnode *nvp, struct nchandle *nch) |
| 2192 | { |
| 2193 | struct vnode *ovp; |
| 2194 | struct nchandle onch; |
| 2195 | |
| 2196 | ovp = rootvnode; |
| 2197 | onch = rootnch; |
| 2198 | rootvnode = nvp; |
| 2199 | if (nch) |
| 2200 | rootnch = *nch; |
| 2201 | else |
| 2202 | cache_zero(&rootnch); |
| 2203 | if (ovp) |
| 2204 | vrele(ovp); |
| 2205 | if (onch.ncp) |
| 2206 | cache_drop(&onch); |
| 2207 | } |
| 2208 | |
| 2209 | /* |
| 2210 | * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache |
| 2211 | * topology and is being removed as quickly as possible. The new VOP_N*() |
| 2212 | * API calls are required to make specific adjustments using the supplied |
| 2213 | * ncp pointers rather then just bogusly purging random vnodes. |
| 2214 | * |
| 2215 | * Invalidate all namecache entries to a particular vnode as well as |
| 2216 | * any direct children of that vnode in the namecache. This is a |
| 2217 | * 'catch all' purge used by filesystems that do not know any better. |
| 2218 | * |
| 2219 | * Note that the linkage between the vnode and its namecache entries will |
| 2220 | * be removed, but the namecache entries themselves might stay put due to |
| 2221 | * active references from elsewhere in the system or due to the existance of |
| 2222 | * the children. The namecache topology is left intact even if we do not |
| 2223 | * know what the vnode association is. Such entries will be marked |
| 2224 | * NCF_UNRESOLVED. |
| 2225 | */ |
| 2226 | void |
| 2227 | cache_purge(struct vnode *vp) |
| 2228 | { |
| 2229 | cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN); |
| 2230 | } |
| 2231 | |
| 2232 | /* |
| 2233 | * Flush all entries referencing a particular filesystem. |
| 2234 | * |
| 2235 | * Since we need to check it anyway, we will flush all the invalid |
| 2236 | * entries at the same time. |
| 2237 | */ |
| 2238 | #if 0 |
| 2239 | |
| 2240 | void |
| 2241 | cache_purgevfs(struct mount *mp) |
| 2242 | { |
| 2243 | struct nchashhead *nchpp; |
| 2244 | struct namecache *ncp, *nnp; |
| 2245 | |
| 2246 | /* |
| 2247 | * Scan hash tables for applicable entries. |
| 2248 | */ |
| 2249 | for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) { |
| 2250 | ncp = LIST_FIRST(nchpp); |
| 2251 | if (ncp) |
| 2252 | _cache_hold(ncp); |
| 2253 | while (ncp) { |
| 2254 | nnp = LIST_NEXT(ncp, nc_hash); |
| 2255 | if (nnp) |
| 2256 | _cache_hold(nnp); |
| 2257 | if (ncp->nc_mount == mp) { |
| 2258 | _cache_lock(ncp); |
| 2259 | cache_zap(ncp); |
| 2260 | } else { |
| 2261 | _cache_drop(ncp); |
| 2262 | } |
| 2263 | ncp = nnp; |
| 2264 | } |
| 2265 | } |
| 2266 | } |
| 2267 | |
| 2268 | #endif |
| 2269 | |
| 2270 | /* |
| 2271 | * Create a new (theoretically) unique fsmid |
| 2272 | */ |
| 2273 | int64_t |
| 2274 | cache_getnewfsmid(void) |
| 2275 | { |
| 2276 | static int fsmid_roller; |
| 2277 | int64_t fsmid; |
| 2278 | |
| 2279 | ++fsmid_roller; |
| 2280 | fsmid = ((int64_t)time_second << 32) | |
| 2281 | (fsmid_roller & 0x7FFFFFFF); |
| 2282 | return (fsmid); |
| 2283 | } |
| 2284 | |
| 2285 | |
| 2286 | static int disablecwd; |
| 2287 | SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); |
| 2288 | |
| 2289 | static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); |
| 2290 | static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); |
| 2291 | static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); |
| 2292 | static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); |
| 2293 | static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); |
| 2294 | static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); |
| 2295 | |
| 2296 | int |
| 2297 | sys___getcwd(struct __getcwd_args *uap) |
| 2298 | { |
| 2299 | int buflen; |
| 2300 | int error; |
| 2301 | char *buf; |
| 2302 | char *bp; |
| 2303 | |
| 2304 | if (disablecwd) |
| 2305 | return (ENODEV); |
| 2306 | |
| 2307 | buflen = uap->buflen; |
| 2308 | if (buflen < 2) |
| 2309 | return (EINVAL); |
| 2310 | if (buflen > MAXPATHLEN) |
| 2311 | buflen = MAXPATHLEN; |
| 2312 | |
| 2313 | buf = kmalloc(buflen, M_TEMP, M_WAITOK); |
| 2314 | bp = kern_getcwd(buf, buflen, &error); |
| 2315 | if (error == 0) |
| 2316 | error = copyout(bp, uap->buf, strlen(bp) + 1); |
| 2317 | kfree(buf, M_TEMP); |
| 2318 | return (error); |
| 2319 | } |
| 2320 | |
| 2321 | char * |
| 2322 | kern_getcwd(char *buf, size_t buflen, int *error) |
| 2323 | { |
| 2324 | struct proc *p = curproc; |
| 2325 | char *bp; |
| 2326 | int i, slash_prefixed; |
| 2327 | struct filedesc *fdp; |
| 2328 | struct nchandle nch; |
| 2329 | |
| 2330 | numcwdcalls++; |
| 2331 | bp = buf; |
| 2332 | bp += buflen - 1; |
| 2333 | *bp = '\0'; |
| 2334 | fdp = p->p_fd; |
| 2335 | slash_prefixed = 0; |
| 2336 | |
| 2337 | nch = fdp->fd_ncdir; |
| 2338 | while (nch.ncp && (nch.ncp != fdp->fd_nrdir.ncp || |
| 2339 | nch.mount != fdp->fd_nrdir.mount) |
| 2340 | ) { |
| 2341 | /* |
| 2342 | * While traversing upwards if we encounter the root |
| 2343 | * of the current mount we have to skip to the mount point |
| 2344 | * in the underlying filesystem. |
| 2345 | */ |
| 2346 | if (nch.ncp == nch.mount->mnt_ncmountpt.ncp) { |
| 2347 | nch = nch.mount->mnt_ncmounton; |
| 2348 | continue; |
| 2349 | } |
| 2350 | |
| 2351 | /* |
| 2352 | * Prepend the path segment |
| 2353 | */ |
| 2354 | for (i = nch.ncp->nc_nlen - 1; i >= 0; i--) { |
| 2355 | if (bp == buf) { |
| 2356 | numcwdfail4++; |
| 2357 | *error = ENOMEM; |
| 2358 | return(NULL); |
| 2359 | } |
| 2360 | *--bp = nch.ncp->nc_name[i]; |
| 2361 | } |
| 2362 | if (bp == buf) { |
| 2363 | numcwdfail4++; |
| 2364 | *error = ENOMEM; |
| 2365 | return(NULL); |
| 2366 | } |
| 2367 | *--bp = '/'; |
| 2368 | slash_prefixed = 1; |
| 2369 | |
| 2370 | /* |
| 2371 | * Go up a directory. This isn't a mount point so we don't |
| 2372 | * have to check again. |
| 2373 | */ |
| 2374 | nch.ncp = nch.ncp->nc_parent; |
| 2375 | } |
| 2376 | if (nch.ncp == NULL) { |
| 2377 | numcwdfail2++; |
| 2378 | *error = ENOENT; |
| 2379 | return(NULL); |
| 2380 | } |
| 2381 | if (!slash_prefixed) { |
| 2382 | if (bp == buf) { |
| 2383 | numcwdfail4++; |
| 2384 | *error = ENOMEM; |
| 2385 | return(NULL); |
| 2386 | } |
| 2387 | *--bp = '/'; |
| 2388 | } |
| 2389 | numcwdfound++; |
| 2390 | *error = 0; |
| 2391 | return (bp); |
| 2392 | } |
| 2393 | |
| 2394 | /* |
| 2395 | * Thus begins the fullpath magic. |
| 2396 | */ |
| 2397 | |
| 2398 | #undef STATNODE |
| 2399 | #define STATNODE(name) \ |
| 2400 | static u_int name; \ |
| 2401 | SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") |
| 2402 | |
| 2403 | static int disablefullpath; |
| 2404 | SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, |
| 2405 | &disablefullpath, 0, ""); |
| 2406 | |
| 2407 | STATNODE(numfullpathcalls); |
| 2408 | STATNODE(numfullpathfail1); |
| 2409 | STATNODE(numfullpathfail2); |
| 2410 | STATNODE(numfullpathfail3); |
| 2411 | STATNODE(numfullpathfail4); |
| 2412 | STATNODE(numfullpathfound); |
| 2413 | |
| 2414 | int |
| 2415 | cache_fullpath(struct proc *p, struct nchandle *nchp, char **retbuf, char **freebuf) |
| 2416 | { |
| 2417 | char *bp, *buf; |
| 2418 | int i, slash_prefixed; |
| 2419 | struct nchandle fd_nrdir; |
| 2420 | struct nchandle nch; |
| 2421 | |
| 2422 | numfullpathcalls--; |
| 2423 | |
| 2424 | *retbuf = NULL; |
| 2425 | *freebuf = NULL; |
| 2426 | |
| 2427 | buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK); |
| 2428 | bp = buf + MAXPATHLEN - 1; |
| 2429 | *bp = '\0'; |
| 2430 | if (p != NULL) |
| 2431 | fd_nrdir = p->p_fd->fd_nrdir; |
| 2432 | else |
| 2433 | fd_nrdir = rootnch; |
| 2434 | slash_prefixed = 0; |
| 2435 | nch = *nchp; |
| 2436 | |
| 2437 | while (nch.ncp && |
| 2438 | (nch.ncp != fd_nrdir.ncp || nch.mount != fd_nrdir.mount) |
| 2439 | ) { |
| 2440 | /* |
| 2441 | * While traversing upwards if we encounter the root |
| 2442 | * of the current mount we have to skip to the mount point. |
| 2443 | */ |
| 2444 | if (nch.ncp == nch.mount->mnt_ncmountpt.ncp) { |
| 2445 | nch = nch.mount->mnt_ncmounton; |
| 2446 | continue; |
| 2447 | } |
| 2448 | |
| 2449 | /* |
| 2450 | * Prepend the path segment |
| 2451 | */ |
| 2452 | for (i = nch.ncp->nc_nlen - 1; i >= 0; i--) { |
| 2453 | if (bp == buf) { |
| 2454 | numfullpathfail4++; |
| 2455 | kfree(buf, M_TEMP); |
| 2456 | return(ENOMEM); |
| 2457 | } |
| 2458 | *--bp = nch.ncp->nc_name[i]; |
| 2459 | } |
| 2460 | if (bp == buf) { |
| 2461 | numfullpathfail4++; |
| 2462 | kfree(buf, M_TEMP); |
| 2463 | return(ENOMEM); |
| 2464 | } |
| 2465 | *--bp = '/'; |
| 2466 | slash_prefixed = 1; |
| 2467 | |
| 2468 | /* |
| 2469 | * Go up a directory. This isn't a mount point so we don't |
| 2470 | * have to check again. |
| 2471 | */ |
| 2472 | nch.ncp = nch.ncp->nc_parent; |
| 2473 | } |
| 2474 | if (nch.ncp == NULL) { |
| 2475 | numfullpathfail2++; |
| 2476 | kfree(buf, M_TEMP); |
| 2477 | return(ENOENT); |
| 2478 | } |
| 2479 | |
| 2480 | if (!slash_prefixed) { |
| 2481 | if (bp == buf) { |
| 2482 | numfullpathfail4++; |
| 2483 | kfree(buf, M_TEMP); |
| 2484 | return(ENOMEM); |
| 2485 | } |
| 2486 | *--bp = '/'; |
| 2487 | } |
| 2488 | numfullpathfound++; |
| 2489 | *retbuf = bp; |
| 2490 | *freebuf = buf; |
| 2491 | |
| 2492 | return(0); |
| 2493 | } |
| 2494 | |
| 2495 | int |
| 2496 | vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf) |
| 2497 | { |
| 2498 | struct namecache *ncp; |
| 2499 | struct nchandle nch; |
| 2500 | |
| 2501 | numfullpathcalls++; |
| 2502 | if (disablefullpath) |
| 2503 | return (ENODEV); |
| 2504 | |
| 2505 | if (p == NULL) |
| 2506 | return (EINVAL); |
| 2507 | |
| 2508 | /* vn is NULL, client wants us to use p->p_textvp */ |
| 2509 | if (vn == NULL) { |
| 2510 | if ((vn = p->p_textvp) == NULL) |
| 2511 | return (EINVAL); |
| 2512 | } |
| 2513 | TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) { |
| 2514 | if (ncp->nc_nlen) |
| 2515 | break; |
| 2516 | } |
| 2517 | if (ncp == NULL) |
| 2518 | return (EINVAL); |
| 2519 | |
| 2520 | numfullpathcalls--; |
| 2521 | nch.ncp = ncp;; |
| 2522 | nch.mount = vn->v_mount; |
| 2523 | return(cache_fullpath(p, &nch, retbuf, freebuf)); |
| 2524 | } |