proc->thread stage 4: rework the VFS and DEVICE subsystems to take thread
[dragonfly.git] / sys / kern / vfs_cache.c
CommitLineData
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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 $
dadab5e9 38 * $DragonFly: src/sys/kern/vfs_cache.c,v 1.4 2003/06/25 03:55:57 dillon Exp $
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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>
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47#include <sys/malloc.h>
48#include <sys/sysproto.h>
49#include <sys/proc.h>
dadab5e9 50#include <sys/namei.h>
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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
59struct 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])
92static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
93static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */
94static u_long nchash; /* size of hash table */
95SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "");
96static u_long ncnegfactor = 16; /* ratio of negative entries */
97SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "");
98static u_long numneg; /* number of cache entries allocated */
99SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "");
100static u_long numcache; /* number of cache entries allocated */
101SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "");
102struct nchstats nchstats; /* cache effectiveness statistics */
103
104static int doingcache = 1; /* 1 => enable the cache */
105SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, "");
106SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), "");
107SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), "");
108
109/*
110 * The new name cache statistics
111 */
112SYSCTL_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, "");
115STATNODE(CTLFLAG_RD, numneg, &numneg);
116STATNODE(CTLFLAG_RD, numcache, &numcache);
117static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls);
118static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits);
119static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits);
120static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks);
121static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss);
122static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap);
123static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps);
124static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits);
125static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps);
126static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits);
127
128
129static void cache_zap __P((struct namecache *ncp));
130
131MALLOC_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 */
141static void
142cache_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
174int
175cache_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 */
268void
269cache_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 */
341void
342nchinit()
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
365void
366cache_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 */
390void
391cache_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 */
418int
419cache_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
438int
439vfs_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;
dadab5e9 453 struct thread *td = cnp->cn_td;
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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
dadab5e9 467 error = VOP_ACCESS(dvp, VEXEC, cred, td);
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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) {
dadab5e9 487 VOP_UNLOCK(dvp, 0, td);
984263bc 488 cnp->cn_flags |= PDIRUNLOCK;
dadab5e9 489 error = vget(vp, LK_EXCLUSIVE, td);
984263bc 490 if (!error && lockparent && (flags & ISLASTCN)) {
dadab5e9 491 if ((error = vn_lock(dvp, LK_EXCLUSIVE, td)) == 0)
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492 cnp->cn_flags &= ~PDIRUNLOCK;
493 }
494 } else {
dadab5e9 495 error = vget(vp, LK_EXCLUSIVE, td);
984263bc 496 if (!lockparent || error || !(flags & ISLASTCN)) {
dadab5e9 497 VOP_UNLOCK(dvp, 0, td);
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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)) {
dadab5e9 510 VOP_UNLOCK(dvp, 0, td);
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511 cnp->cn_flags |= PDIRUNLOCK;
512 }
513 }
514 if (cnp->cn_flags & PDIRUNLOCK) {
dadab5e9 515 error = vn_lock(dvp, LK_EXCLUSIVE, td);
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516 if (error)
517 return (error);
518 cnp->cn_flags &= ~PDIRUNLOCK;
519 }
520 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
521}
522
523
524#ifndef _SYS_SYSPROTO_H_
525struct __getcwd_args {
526 u_char *buf;
527 u_int buflen;
528};
529#endif
530
531static int disablecwd;
532SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "");
533
534static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls);
535static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1);
536static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2);
537static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3);
538static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4);
539static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound);
41c20dac 540
984263bc 541int
41c20dac 542__getcwd(struct __getcwd_args *uap)
984263bc 543{
41c20dac 544 struct proc *p = curproc;
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545 char *bp, *buf;
546 int error, i, slash_prefixed;
547 struct filedesc *fdp;
548 struct namecache *ncp;
549 struct vnode *vp;
550
551 numcwdcalls++;
552 if (disablecwd)
553 return (ENODEV);
554 if (uap->buflen < 2)
555 return (EINVAL);
556 if (uap->buflen > MAXPATHLEN)
557 uap->buflen = MAXPATHLEN;
558 buf = bp = malloc(uap->buflen, M_TEMP, M_WAITOK);
559 bp += uap->buflen - 1;
560 *bp = '\0';
561 fdp = p->p_fd;
562 slash_prefixed = 0;
563 for (vp = fdp->fd_cdir; vp != fdp->fd_rdir && vp != rootvnode;) {
564 if (vp->v_flag & VROOT) {
565 if (vp->v_mount == NULL) { /* forced unmount */
566 free(buf, M_TEMP);
567 return (EBADF);
568 }
569 vp = vp->v_mount->mnt_vnodecovered;
570 continue;
571 }
572 if (vp->v_dd->v_id != vp->v_ddid) {
573 numcwdfail1++;
574 free(buf, M_TEMP);
575 return (ENOTDIR);
576 }
577 ncp = TAILQ_FIRST(&vp->v_cache_dst);
578 if (!ncp) {
579 numcwdfail2++;
580 free(buf, M_TEMP);
581 return (ENOENT);
582 }
583 if (ncp->nc_dvp != vp->v_dd) {
584 numcwdfail3++;
585 free(buf, M_TEMP);
586 return (EBADF);
587 }
588 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
589 if (bp == buf) {
590 numcwdfail4++;
591 free(buf, M_TEMP);
592 return (ENOMEM);
593 }
594 *--bp = ncp->nc_name[i];
595 }
596 if (bp == buf) {
597 numcwdfail4++;
598 free(buf, M_TEMP);
599 return (ENOMEM);
600 }
601 *--bp = '/';
602 slash_prefixed = 1;
603 vp = vp->v_dd;
604 }
605 if (!slash_prefixed) {
606 if (bp == buf) {
607 numcwdfail4++;
608 free(buf, M_TEMP);
609 return (ENOMEM);
610 }
611 *--bp = '/';
612 }
613 numcwdfound++;
614 error = copyout(bp, uap->buf, strlen(bp) + 1);
615 free(buf, M_TEMP);
616 return (error);
617}
618
619/*
620 * Thus begins the fullpath magic.
621 */
622
623#undef STATNODE
624#define STATNODE(name) \
625 static u_int name; \
626 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
627
628static int disablefullpath;
629SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW,
630 &disablefullpath, 0, "");
631
632STATNODE(numfullpathcalls);
633STATNODE(numfullpathfail1);
634STATNODE(numfullpathfail2);
635STATNODE(numfullpathfail3);
636STATNODE(numfullpathfail4);
637STATNODE(numfullpathfound);
638
639int
640textvp_fullpath(struct proc *p, char **retbuf, char **retfreebuf) {
641 char *bp, *buf;
642 int i, slash_prefixed;
643 struct filedesc *fdp;
644 struct namecache *ncp;
645 struct vnode *vp, *textvp;
646
647 numfullpathcalls++;
648 if (disablefullpath)
649 return (ENODEV);
650 textvp = p->p_textvp;
651 if (textvp == NULL)
652 return (EINVAL);
653 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
654 bp = buf + MAXPATHLEN - 1;
655 *bp = '\0';
656 fdp = p->p_fd;
657 slash_prefixed = 0;
658 for (vp = textvp; vp != fdp->fd_rdir && vp != rootvnode;) {
659 if (vp->v_flag & VROOT) {
660 if (vp->v_mount == NULL) { /* forced unmount */
661 free(buf, M_TEMP);
662 return (EBADF);
663 }
664 vp = vp->v_mount->mnt_vnodecovered;
665 continue;
666 }
667 if (vp != textvp && vp->v_dd->v_id != vp->v_ddid) {
668 numfullpathfail1++;
669 free(buf, M_TEMP);
670 return (ENOTDIR);
671 }
672 ncp = TAILQ_FIRST(&vp->v_cache_dst);
673 if (!ncp) {
674 numfullpathfail2++;
675 free(buf, M_TEMP);
676 return (ENOENT);
677 }
678 if (vp != textvp && ncp->nc_dvp != vp->v_dd) {
679 numfullpathfail3++;
680 free(buf, M_TEMP);
681 return (EBADF);
682 }
683 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
684 if (bp == buf) {
685 numfullpathfail4++;
686 free(buf, M_TEMP);
687 return (ENOMEM);
688 }
689 *--bp = ncp->nc_name[i];
690 }
691 if (bp == buf) {
692 numfullpathfail4++;
693 free(buf, M_TEMP);
694 return (ENOMEM);
695 }
696 *--bp = '/';
697 slash_prefixed = 1;
698 vp = ncp->nc_dvp;
699 }
700 if (!slash_prefixed) {
701 if (bp == buf) {
702 numfullpathfail4++;
703 free(buf, M_TEMP);
704 return (ENOMEM);
705 }
706 *--bp = '/';
707 }
708 numfullpathfound++;
709 *retbuf = bp;
710 *retfreebuf = buf;
711 return (0);
712}