1 /* 2 * Copyright (c) 1989, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Poul-Henning Kamp of the FreeBSD Project. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 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 the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 37 * $FreeBSD: src/sys/kern/vfs_cache.c,v 1.42.2.6 2001/10/05 20:07:03 dillon Exp $ 38 * $DragonFly: src/sys/kern/vfs_cache.c,v 1.5 2003/07/24 01:41:25 dillon Exp $ 39 */ 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/kernel.h> 44 #include <sys/sysctl.h> 45 #include <sys/mount.h> 46 #include <sys/vnode.h> 47 #include <sys/malloc.h> 48 #include <sys/sysproto.h> 49 #include <sys/proc.h> 50 #include <sys/namei.h> 51 #include <sys/filedesc.h> 52 #include <sys/fnv_hash.h> 53 54 /* 55 * This structure describes the elements in the cache of recent 56 * names looked up by namei. 57 */ 58 59 struct namecache { 60 LIST_ENTRY(namecache) nc_hash; /* hash chain */ 61 LIST_ENTRY(namecache) nc_src; /* source vnode list */ 62 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ 63 struct vnode *nc_dvp; /* vnode of parent of name */ 64 struct vnode *nc_vp; /* vnode the name refers to */ 65 u_char nc_flag; /* flag bits */ 66 u_char nc_nlen; /* length of name */ 67 char nc_name[0]; /* segment name */ 68 }; 69 70 /* 71 * Name caching works as follows: 72 * 73 * Names found by directory scans are retained in a cache 74 * for future reference. It is managed LRU, so frequently 75 * used names will hang around. Cache is indexed by hash value 76 * obtained from (vp, name) where vp refers to the directory 77 * containing name. 78 * 79 * If it is a "negative" entry, (i.e. for a name that is known NOT to 80 * exist) the vnode pointer will be NULL. 81 * 82 * Upon reaching the last segment of a path, if the reference 83 * is for DELETE, or NOCACHE is set (rewrite), and the 84 * name is located in the cache, it will be dropped. 85 */ 86 87 /* 88 * Structures associated with name cacheing. 89 */ 90 #define NCHHASH(hash) \ 91 (&nchashtbl[(hash) & nchash]) 92 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ 93 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ 94 static u_long nchash; /* size of hash table */ 95 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); 96 static u_long ncnegfactor = 16; /* ratio of negative entries */ 97 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); 98 static u_long numneg; /* number of cache entries allocated */ 99 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); 100 static u_long numcache; /* number of cache entries allocated */ 101 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); 102 struct nchstats nchstats; /* cache effectiveness statistics */ 103 104 static int doingcache = 1; /* 1 => enable the cache */ 105 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, ""); 106 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), ""); 107 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), ""); 108 109 /* 110 * The new name cache statistics 111 */ 112 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); 113 #define STATNODE(mode, name, var) \ 114 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); 115 STATNODE(CTLFLAG_RD, numneg, &numneg); 116 STATNODE(CTLFLAG_RD, numcache, &numcache); 117 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); 118 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); 119 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); 120 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); 121 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); 122 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); 123 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); 124 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); 125 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); 126 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); 127 128 129 static void cache_zap __P((struct namecache *ncp)); 130 131 MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); 132 133 /* 134 * Flags in namecache.nc_flag 135 */ 136 #define NCF_WHITE 1 137 /* 138 * Delete an entry from its hash list and move it to the front 139 * of the LRU list for immediate reuse. 140 */ 141 static void 142 cache_zap(ncp) 143 struct namecache *ncp; 144 { 145 LIST_REMOVE(ncp, nc_hash); 146 LIST_REMOVE(ncp, nc_src); 147 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) 148 vdrop(ncp->nc_dvp); 149 if (ncp->nc_vp) { 150 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); 151 } else { 152 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 153 numneg--; 154 } 155 numcache--; 156 free(ncp, M_VFSCACHE); 157 } 158 159 /* 160 * Lookup an entry in the cache 161 * 162 * We don't do this if the segment name is long, simply so the cache 163 * can avoid holding long names (which would either waste space, or 164 * add greatly to the complexity). 165 * 166 * Lookup is called with dvp pointing to the directory to search, 167 * cnp pointing to the name of the entry being sought. If the lookup 168 * succeeds, the vnode is returned in *vpp, and a status of -1 is 169 * returned. If the lookup determines that the name does not exist 170 * (negative cacheing), a status of ENOENT is returned. If the lookup 171 * fails, a status of zero is returned. 172 */ 173 174 int 175 cache_lookup(dvp, vpp, cnp) 176 struct vnode *dvp; 177 struct vnode **vpp; 178 struct componentname *cnp; 179 { 180 struct namecache *ncp; 181 u_int32_t hash; 182 183 if (!doingcache) { 184 cnp->cn_flags &= ~MAKEENTRY; 185 return (0); 186 } 187 188 numcalls++; 189 190 if (cnp->cn_nameptr[0] == '.') { 191 if (cnp->cn_namelen == 1) { 192 *vpp = dvp; 193 dothits++; 194 return (-1); 195 } 196 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 197 dotdothits++; 198 if (dvp->v_dd->v_id != dvp->v_ddid || 199 (cnp->cn_flags & MAKEENTRY) == 0) { 200 dvp->v_ddid = 0; 201 return (0); 202 } 203 *vpp = dvp->v_dd; 204 return (-1); 205 } 206 } 207 208 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); 209 hash = fnv_32_buf(&dvp->v_id, sizeof(dvp->v_id), hash); 210 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { 211 numchecks++; 212 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && 213 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) 214 break; 215 } 216 217 /* We failed to find an entry */ 218 if (ncp == 0) { 219 if ((cnp->cn_flags & MAKEENTRY) == 0) { 220 nummisszap++; 221 } else { 222 nummiss++; 223 } 224 nchstats.ncs_miss++; 225 return (0); 226 } 227 228 /* We don't want to have an entry, so dump it */ 229 if ((cnp->cn_flags & MAKEENTRY) == 0) { 230 numposzaps++; 231 nchstats.ncs_badhits++; 232 cache_zap(ncp); 233 return (0); 234 } 235 236 /* We found a "positive" match, return the vnode */ 237 if (ncp->nc_vp) { 238 numposhits++; 239 nchstats.ncs_goodhits++; 240 *vpp = ncp->nc_vp; 241 return (-1); 242 } 243 244 /* We found a negative match, and want to create it, so purge */ 245 if (cnp->cn_nameiop == CREATE) { 246 numnegzaps++; 247 nchstats.ncs_badhits++; 248 cache_zap(ncp); 249 return (0); 250 } 251 252 numneghits++; 253 /* 254 * We found a "negative" match, ENOENT notifies client of this match. 255 * The nc_vpid field records whether this is a whiteout. 256 */ 257 TAILQ_REMOVE(&ncneg, ncp, nc_dst); 258 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 259 nchstats.ncs_neghits++; 260 if (ncp->nc_flag & NCF_WHITE) 261 cnp->cn_flags |= ISWHITEOUT; 262 return (ENOENT); 263 } 264 265 /* 266 * Add an entry to the cache. 267 */ 268 void 269 cache_enter(dvp, vp, cnp) 270 struct vnode *dvp; 271 struct vnode *vp; 272 struct componentname *cnp; 273 { 274 struct namecache *ncp; 275 struct nchashhead *ncpp; 276 u_int32_t hash; 277 int len; 278 279 if (!doingcache) 280 return; 281 282 if (cnp->cn_nameptr[0] == '.') { 283 if (cnp->cn_namelen == 1) { 284 return; 285 } 286 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { 287 if (vp) { 288 dvp->v_dd = vp; 289 dvp->v_ddid = vp->v_id; 290 } else { 291 dvp->v_dd = dvp; 292 dvp->v_ddid = 0; 293 } 294 return; 295 } 296 } 297 298 ncp = (struct namecache *) 299 malloc(sizeof *ncp + cnp->cn_namelen, M_VFSCACHE, M_WAITOK); 300 bzero((char *)ncp, sizeof *ncp); 301 numcache++; 302 if (!vp) { 303 numneg++; 304 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; 305 } else if (vp->v_type == VDIR) { 306 vp->v_dd = dvp; 307 vp->v_ddid = dvp->v_id; 308 } 309 310 /* 311 * Fill in cache info, if vp is NULL this is a "negative" cache entry. 312 * For negative entries, we have to record whether it is a whiteout. 313 * the whiteout flag is stored in the nc_vpid field which is 314 * otherwise unused. 315 */ 316 ncp->nc_vp = vp; 317 ncp->nc_dvp = dvp; 318 len = ncp->nc_nlen = cnp->cn_namelen; 319 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); 320 bcopy(cnp->cn_nameptr, ncp->nc_name, len); 321 hash = fnv_32_buf(&dvp->v_id, sizeof(dvp->v_id), hash); 322 ncpp = NCHHASH(hash); 323 LIST_INSERT_HEAD(ncpp, ncp, nc_hash); 324 if (LIST_EMPTY(&dvp->v_cache_src)) 325 vhold(dvp); 326 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); 327 if (vp) { 328 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); 329 } else { 330 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); 331 } 332 if (numneg * ncnegfactor > numcache) { 333 ncp = TAILQ_FIRST(&ncneg); 334 cache_zap(ncp); 335 } 336 } 337 338 /* 339 * Name cache initialization, from vfs_init() when we are booting 340 */ 341 void 342 nchinit() 343 { 344 345 TAILQ_INIT(&ncneg); 346 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash); 347 } 348 349 /* 350 * Invalidate all entries to a particular vnode. 351 * 352 * Remove all entries in the namecache relating to this vnode and 353 * change the v_id. We take the v_id from a global counter, since 354 * it becomes a handy sequence number in crash-dumps that way. 355 * No valid vnode will ever have (v_id == 0). 356 * 357 * XXX: Only time and the size of v_id prevents this from failing: 358 * XXX: In theory we should hunt down all (struct vnode*, v_id) 359 * XXX: soft references and nuke them, at least on the global 360 * XXX: v_id wraparound. The period of resistance can be extended 361 * XXX: by incrementing each vnodes v_id individually instead of 362 * XXX: using the global v_id. 363 */ 364 365 void 366 cache_purge(vp) 367 struct vnode *vp; 368 { 369 static u_long nextid; 370 371 while (!LIST_EMPTY(&vp->v_cache_src)) 372 cache_zap(LIST_FIRST(&vp->v_cache_src)); 373 while (!TAILQ_EMPTY(&vp->v_cache_dst)) 374 cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); 375 376 do 377 nextid++; 378 while (nextid == vp->v_id || !nextid); 379 vp->v_id = nextid; 380 vp->v_dd = vp; 381 vp->v_ddid = 0; 382 } 383 384 /* 385 * Flush all entries referencing a particular filesystem. 386 * 387 * Since we need to check it anyway, we will flush all the invalid 388 * entries at the same time. 389 */ 390 void 391 cache_purgevfs(mp) 392 struct mount *mp; 393 { 394 struct nchashhead *ncpp; 395 struct namecache *ncp, *nnp; 396 397 /* Scan hash tables for applicable entries */ 398 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { 399 for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) { 400 nnp = LIST_NEXT(ncp, nc_hash); 401 if (ncp->nc_dvp->v_mount == mp) { 402 cache_zap(ncp); 403 } 404 } 405 } 406 } 407 408 /* 409 * cache_leaf_test() 410 * 411 * Test whether this (directory) vnode's namei cache entry contains 412 * subdirectories or not. Used to determine whether the directory is 413 * a leaf in the namei cache or not. Note: the directory may still 414 * contain files in the namei cache. 415 * 416 * Returns 0 if the directory is a leaf, -1 if it isn't. 417 */ 418 int 419 cache_leaf_test(struct vnode *vp) 420 { 421 struct namecache *ncpc; 422 423 for (ncpc = LIST_FIRST(&vp->v_cache_src); 424 ncpc != NULL; 425 ncpc = LIST_NEXT(ncpc, nc_src) 426 ) { 427 if (ncpc->nc_vp != NULL && ncpc->nc_vp->v_type == VDIR) 428 return(-1); 429 } 430 return(0); 431 } 432 433 /* 434 * Perform canonical checks and cache lookup and pass on to filesystem 435 * through the vop_cachedlookup only if needed. 436 */ 437 438 int 439 vfs_cache_lookup(ap) 440 struct vop_lookup_args /* { 441 struct vnode *a_dvp; 442 struct vnode **a_vpp; 443 struct componentname *a_cnp; 444 } */ *ap; 445 { 446 struct vnode *dvp, *vp; 447 int lockparent; 448 int error; 449 struct vnode **vpp = ap->a_vpp; 450 struct componentname *cnp = ap->a_cnp; 451 struct ucred *cred = cnp->cn_cred; 452 int flags = cnp->cn_flags; 453 struct thread *td = cnp->cn_td; 454 u_long vpid; /* capability number of vnode */ 455 456 *vpp = NULL; 457 dvp = ap->a_dvp; 458 lockparent = flags & LOCKPARENT; 459 460 if (dvp->v_type != VDIR) 461 return (ENOTDIR); 462 463 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 464 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 465 return (EROFS); 466 467 error = VOP_ACCESS(dvp, VEXEC, cred, td); 468 469 if (error) 470 return (error); 471 472 error = cache_lookup(dvp, vpp, cnp); 473 474 if (!error) 475 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 476 477 if (error == ENOENT) 478 return (error); 479 480 vp = *vpp; 481 vpid = vp->v_id; 482 cnp->cn_flags &= ~PDIRUNLOCK; 483 if (dvp == vp) { /* lookup on "." */ 484 VREF(vp); 485 error = 0; 486 } else if (flags & ISDOTDOT) { 487 VOP_UNLOCK(dvp, 0, td); 488 cnp->cn_flags |= PDIRUNLOCK; 489 error = vget(vp, LK_EXCLUSIVE, td); 490 if (!error && lockparent && (flags & ISLASTCN)) { 491 if ((error = vn_lock(dvp, LK_EXCLUSIVE, td)) == 0) 492 cnp->cn_flags &= ~PDIRUNLOCK; 493 } 494 } else { 495 error = vget(vp, LK_EXCLUSIVE, td); 496 if (!lockparent || error || !(flags & ISLASTCN)) { 497 VOP_UNLOCK(dvp, 0, td); 498 cnp->cn_flags |= PDIRUNLOCK; 499 } 500 } 501 /* 502 * Check that the capability number did not change 503 * while we were waiting for the lock. 504 */ 505 if (!error) { 506 if (vpid == vp->v_id) 507 return (0); 508 vput(vp); 509 if (lockparent && dvp != vp && (flags & ISLASTCN)) { 510 VOP_UNLOCK(dvp, 0, td); 511 cnp->cn_flags |= PDIRUNLOCK; 512 } 513 } 514 if (cnp->cn_flags & PDIRUNLOCK) { 515 error = vn_lock(dvp, LK_EXCLUSIVE, td); 516 if (error) 517 return (error); 518 cnp->cn_flags &= ~PDIRUNLOCK; 519 } 520 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); 521 } 522 523 static int disablecwd; 524 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, ""); 525 526 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls); 527 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1); 528 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); 529 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); 530 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); 531 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); 532 533 int 534 __getcwd(struct __getcwd_args *uap) 535 { 536 struct proc *p = curproc; 537 char *bp, *buf; 538 int error, i, slash_prefixed; 539 struct filedesc *fdp; 540 struct namecache *ncp; 541 struct vnode *vp; 542 543 numcwdcalls++; 544 if (disablecwd) 545 return (ENODEV); 546 if (uap->buflen < 2) 547 return (EINVAL); 548 if (uap->buflen > MAXPATHLEN) 549 uap->buflen = MAXPATHLEN; 550 buf = bp = malloc(uap->buflen, M_TEMP, M_WAITOK); 551 bp += uap->buflen - 1; 552 *bp = '\0'; 553 fdp = p->p_fd; 554 slash_prefixed = 0; 555 for (vp = fdp->fd_cdir; vp != fdp->fd_rdir && vp != rootvnode;) { 556 if (vp->v_flag & VROOT) { 557 if (vp->v_mount == NULL) { /* forced unmount */ 558 free(buf, M_TEMP); 559 return (EBADF); 560 } 561 vp = vp->v_mount->mnt_vnodecovered; 562 continue; 563 } 564 if (vp->v_dd->v_id != vp->v_ddid) { 565 numcwdfail1++; 566 free(buf, M_TEMP); 567 return (ENOTDIR); 568 } 569 ncp = TAILQ_FIRST(&vp->v_cache_dst); 570 if (!ncp) { 571 numcwdfail2++; 572 free(buf, M_TEMP); 573 return (ENOENT); 574 } 575 if (ncp->nc_dvp != vp->v_dd) { 576 numcwdfail3++; 577 free(buf, M_TEMP); 578 return (EBADF); 579 } 580 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 581 if (bp == buf) { 582 numcwdfail4++; 583 free(buf, M_TEMP); 584 return (ENOMEM); 585 } 586 *--bp = ncp->nc_name[i]; 587 } 588 if (bp == buf) { 589 numcwdfail4++; 590 free(buf, M_TEMP); 591 return (ENOMEM); 592 } 593 *--bp = '/'; 594 slash_prefixed = 1; 595 vp = vp->v_dd; 596 } 597 if (!slash_prefixed) { 598 if (bp == buf) { 599 numcwdfail4++; 600 free(buf, M_TEMP); 601 return (ENOMEM); 602 } 603 *--bp = '/'; 604 } 605 numcwdfound++; 606 error = copyout(bp, uap->buf, strlen(bp) + 1); 607 free(buf, M_TEMP); 608 return (error); 609 } 610 611 /* 612 * Thus begins the fullpath magic. 613 */ 614 615 #undef STATNODE 616 #define STATNODE(name) \ 617 static u_int name; \ 618 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") 619 620 static int disablefullpath; 621 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, 622 &disablefullpath, 0, ""); 623 624 STATNODE(numfullpathcalls); 625 STATNODE(numfullpathfail1); 626 STATNODE(numfullpathfail2); 627 STATNODE(numfullpathfail3); 628 STATNODE(numfullpathfail4); 629 STATNODE(numfullpathfound); 630 631 int 632 textvp_fullpath(struct proc *p, char **retbuf, char **retfreebuf) { 633 char *bp, *buf; 634 int i, slash_prefixed; 635 struct filedesc *fdp; 636 struct namecache *ncp; 637 struct vnode *vp, *textvp; 638 639 numfullpathcalls++; 640 if (disablefullpath) 641 return (ENODEV); 642 textvp = p->p_textvp; 643 if (textvp == NULL) 644 return (EINVAL); 645 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 646 bp = buf + MAXPATHLEN - 1; 647 *bp = '\0'; 648 fdp = p->p_fd; 649 slash_prefixed = 0; 650 for (vp = textvp; vp != fdp->fd_rdir && vp != rootvnode;) { 651 if (vp->v_flag & VROOT) { 652 if (vp->v_mount == NULL) { /* forced unmount */ 653 free(buf, M_TEMP); 654 return (EBADF); 655 } 656 vp = vp->v_mount->mnt_vnodecovered; 657 continue; 658 } 659 if (vp != textvp && vp->v_dd->v_id != vp->v_ddid) { 660 numfullpathfail1++; 661 free(buf, M_TEMP); 662 return (ENOTDIR); 663 } 664 ncp = TAILQ_FIRST(&vp->v_cache_dst); 665 if (!ncp) { 666 numfullpathfail2++; 667 free(buf, M_TEMP); 668 return (ENOENT); 669 } 670 if (vp != textvp && ncp->nc_dvp != vp->v_dd) { 671 numfullpathfail3++; 672 free(buf, M_TEMP); 673 return (EBADF); 674 } 675 for (i = ncp->nc_nlen - 1; i >= 0; i--) { 676 if (bp == buf) { 677 numfullpathfail4++; 678 free(buf, M_TEMP); 679 return (ENOMEM); 680 } 681 *--bp = ncp->nc_name[i]; 682 } 683 if (bp == buf) { 684 numfullpathfail4++; 685 free(buf, M_TEMP); 686 return (ENOMEM); 687 } 688 *--bp = '/'; 689 slash_prefixed = 1; 690 vp = ncp->nc_dvp; 691 } 692 if (!slash_prefixed) { 693 if (bp == buf) { 694 numfullpathfail4++; 695 free(buf, M_TEMP); 696 return (ENOMEM); 697 } 698 *--bp = '/'; 699 } 700 numfullpathfound++; 701 *retbuf = bp; 702 *retfreebuf = buf; 703 return (0); 704 } 705