/*- * Copyright (c) 1989, 1993, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Poul-Henning Kamp of the FreeBSD Project. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * This structure describes the elements in the cache of recent * names looked up by namei. */ struct namecache { LIST_ENTRY(namecache) nc_hash; /* hash chain */ LIST_ENTRY(namecache) nc_src; /* source vnode list */ TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ struct vnode *nc_dvp; /* vnode of parent of name */ struct vnode *nc_vp; /* vnode the name refers to */ u_char nc_flag; /* flag bits */ u_char nc_nlen; /* length of name */ char nc_name[0]; /* segment name */ }; /* * Name caching works as follows: * * Names found by directory scans are retained in a cache * for future reference. It is managed LRU, so frequently * used names will hang around. Cache is indexed by hash value * obtained from (vp, name) where vp refers to the directory * containing name. * * If it is a "negative" entry, (i.e. for a name that is known NOT to * exist) the vnode pointer will be NULL. * * Upon reaching the last segment of a path, if the reference * is for DELETE, or NOCACHE is set (rewrite), and the * name is located in the cache, it will be dropped. */ /* * Structures associated with name cacheing. */ #define NCHHASH(hash) \ (&nchashtbl[(hash) & nchash]) static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ static u_long nchash; /* size of hash table */ SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, ""); static u_long ncnegfactor = 16; /* ratio of negative entries */ SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, ""); static u_long numneg; /* number of cache entries allocated */ SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, ""); static u_long numcache; /* number of cache entries allocated */ SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, ""); static u_long numcachehv; /* number of cache entries with vnodes held */ SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, ""); #if 0 static u_long numcachepl; /* number of cache purge for leaf entries */ SYSCTL_ULONG(_debug, OID_AUTO, numcachepl, CTLFLAG_RD, &numcachepl, 0, ""); #endif struct nchstats nchstats; /* cache effectiveness statistics */ static struct mtx cache_lock; MTX_SYSINIT(vfscache, &cache_lock, "Name Cache", MTX_DEF); #define CACHE_LOCK() mtx_lock(&cache_lock) #define CACHE_UNLOCK() mtx_unlock(&cache_lock) /* * UMA zones for the VFS cache. * * The small cache is used for entries with short names, which are the * most common. The large cache is used for entries which are too big to * fit in the small cache. */ static uma_zone_t cache_zone_small; static uma_zone_t cache_zone_large; #define CACHE_PATH_CUTOFF 32 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF) #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX) #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \ cache_zone_small : cache_zone_large, M_WAITOK) #define cache_free(ncp) do { \ if (ncp != NULL) \ uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \ cache_zone_small : cache_zone_large, (ncp)); \ } while (0) static int doingcache = 1; /* 1 => enable the cache */ SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, ""); /* Export size information to userland */ SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0, sizeof(struct namecache), ""); /* * The new name cache statistics */ static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); #define STATNODE(mode, name, var) \ SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, ""); STATNODE(CTLFLAG_RD, numneg, &numneg); STATNODE(CTLFLAG_RD, numcache, &numcache); static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls); static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits); static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits); static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks); static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss); static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap); static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps); static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits); static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps); static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits); SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats, sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); static void cache_zap(struct namecache *ncp); static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, u_int buflen); static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); /* * Flags in namecache.nc_flag */ #define NCF_WHITE 1 /* * Grab an atomic snapshot of the name cache hash chain lengths */ SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); static int sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) { int error; struct nchashhead *ncpp; struct namecache *ncp; int n_nchash; int count; n_nchash = nchash + 1; /* nchash is max index, not count */ if (!req->oldptr) return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); /* Scan hash tables for applicable entries */ for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { CACHE_LOCK(); count = 0; LIST_FOREACH(ncp, ncpp, nc_hash) { count++; } CACHE_UNLOCK(); error = SYSCTL_OUT(req, &count, sizeof(count)); if (error) return (error); } return (0); } SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); static int sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) { int error; struct nchashhead *ncpp; struct namecache *ncp; int n_nchash; int count, maxlength, used, pct; if (!req->oldptr) return SYSCTL_OUT(req, 0, 4 * sizeof(int)); n_nchash = nchash + 1; /* nchash is max index, not count */ used = 0; maxlength = 0; /* Scan hash tables for applicable entries */ for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { count = 0; CACHE_LOCK(); LIST_FOREACH(ncp, ncpp, nc_hash) { count++; } CACHE_UNLOCK(); if (count) used++; if (maxlength < count) maxlength = count; } n_nchash = nchash + 1; pct = (used * 100 * 100) / n_nchash; error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); if (error) return (error); error = SYSCTL_OUT(req, &used, sizeof(used)); if (error) return (error); error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); if (error) return (error); error = SYSCTL_OUT(req, &pct, sizeof(pct)); if (error) return (error); return (0); } SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths"); /* * cache_zap(): * * Removes a namecache entry from cache, whether it contains an actual * pointer to a vnode or if it is just a negative cache entry. */ static void cache_zap(ncp) struct namecache *ncp; { struct vnode *vp; mtx_assert(&cache_lock, MA_OWNED); CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); vp = NULL; LIST_REMOVE(ncp, nc_hash); LIST_REMOVE(ncp, nc_src); if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { vp = ncp->nc_dvp; numcachehv--; } if (ncp->nc_vp) { TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); ncp->nc_vp->v_dd = NULL; } else { TAILQ_REMOVE(&ncneg, ncp, nc_dst); numneg--; } numcache--; cache_free(ncp); if (vp) vdrop(vp); } /* * Lookup an entry in the cache * * Lookup is called with dvp pointing to the directory to search, * cnp pointing to the name of the entry being sought. If the lookup * succeeds, the vnode is returned in *vpp, and a status of -1 is * returned. If the lookup determines that the name does not exist * (negative cacheing), a status of ENOENT is returned. If the lookup * fails, a status of zero is returned. If the directory vnode is * recycled out from under us due to a forced unmount, a status of * EBADF is returned. * * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is * unlocked. If we're looking up . an extra ref is taken, but the lock is * not recursively acquired. */ int cache_lookup(dvp, vpp, cnp) struct vnode *dvp; struct vnode **vpp; struct componentname *cnp; { struct namecache *ncp; u_int32_t hash; int error, ltype; if (!doingcache) { cnp->cn_flags &= ~MAKEENTRY; return (0); } retry: CACHE_LOCK(); numcalls++; if (cnp->cn_nameptr[0] == '.') { if (cnp->cn_namelen == 1) { *vpp = dvp; CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", dvp, cnp->cn_nameptr); dothits++; goto success; } if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { dotdothits++; if (dvp->v_dd == NULL || (cnp->cn_flags & MAKEENTRY) == 0) { CACHE_UNLOCK(); return (0); } *vpp = dvp->v_dd; CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", dvp, cnp->cn_nameptr, *vpp); goto success; } } hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); hash = fnv_32_buf(&dvp, sizeof(dvp), hash); LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { numchecks++; if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen)) break; } /* We failed to find an entry */ if (ncp == 0) { if ((cnp->cn_flags & MAKEENTRY) == 0) { nummisszap++; } else { nummiss++; } nchstats.ncs_miss++; CACHE_UNLOCK(); return (0); } /* We don't want to have an entry, so dump it */ if ((cnp->cn_flags & MAKEENTRY) == 0) { numposzaps++; nchstats.ncs_badhits++; cache_zap(ncp); CACHE_UNLOCK(); return (0); } /* We found a "positive" match, return the vnode */ if (ncp->nc_vp) { numposhits++; nchstats.ncs_goodhits++; *vpp = ncp->nc_vp; CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", dvp, cnp->cn_nameptr, *vpp, ncp); goto success; } /* We found a negative match, and want to create it, so purge */ if (cnp->cn_nameiop == CREATE) { numnegzaps++; nchstats.ncs_badhits++; cache_zap(ncp); CACHE_UNLOCK(); return (0); } numneghits++; /* * We found a "negative" match, so we shift it to the end of * the "negative" cache entries queue to satisfy LRU. Also, * check to see if the entry is a whiteout; indicate this to * the componentname, if so. */ TAILQ_REMOVE(&ncneg, ncp, nc_dst); TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); nchstats.ncs_neghits++; if (ncp->nc_flag & NCF_WHITE) cnp->cn_flags |= ISWHITEOUT; CACHE_UNLOCK(); return (ENOENT); success: /* * On success we return a locked and ref'd vnode as per the lookup * protocol. */ if (dvp == *vpp) { /* lookup on "." */ VREF(*vpp); CACHE_UNLOCK(); /* * When we lookup "." we still can be asked to lock it * differently... */ ltype = cnp->cn_lkflags & LK_TYPE_MASK; if (ltype != VOP_ISLOCKED(*vpp)) { if (ltype == LK_EXCLUSIVE) { vn_lock(*vpp, LK_UPGRADE | LK_RETRY); if ((*vpp)->v_iflag & VI_DOOMED) { /* forced unmount */ vrele(*vpp); *vpp = NULL; return (EBADF); } } else vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); } return (-1); } ltype = 0; /* silence gcc warning */ if (cnp->cn_flags & ISDOTDOT) { ltype = VOP_ISLOCKED(dvp); VOP_UNLOCK(dvp, 0); } VI_LOCK(*vpp); CACHE_UNLOCK(); error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); if (cnp->cn_flags & ISDOTDOT) vn_lock(dvp, ltype | LK_RETRY); if (error) { *vpp = NULL; goto retry; } if ((cnp->cn_flags & ISLASTCN) && (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); } return (-1); } /* * Add an entry to the cache. */ void cache_enter(dvp, vp, cnp) struct vnode *dvp; struct vnode *vp; struct componentname *cnp; { struct namecache *ncp; struct nchashhead *ncpp; u_int32_t hash; int hold; int zap; int len; CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, ("cahe_enter: Adding a doomed vnode")); if (!doingcache) return; if (cnp->cn_nameptr[0] == '.') { if (cnp->cn_namelen == 1) { return; } /* * For dotdot lookups only cache the v_dd pointer if the * directory has a link back to its parent via v_cache_dst. * Without this an unlinked directory would keep a soft * reference to its parent which could not be NULLd at * cache_purge() time. */ if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { CACHE_LOCK(); if (!TAILQ_EMPTY(&dvp->v_cache_dst)) dvp->v_dd = vp; CACHE_UNLOCK(); return; } } hold = 0; zap = 0; /* * Calculate the hash key and setup as much of the new * namecache entry as possible before acquiring the lock. */ ncp = cache_alloc(cnp->cn_namelen); ncp->nc_vp = vp; ncp->nc_dvp = dvp; len = ncp->nc_nlen = cnp->cn_namelen; hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); bcopy(cnp->cn_nameptr, ncp->nc_name, len); hash = fnv_32_buf(&dvp, sizeof(dvp), hash); CACHE_LOCK(); /* * See if this vnode is already in the cache with this name. * This can happen with concurrent lookups of the same path * name. */ if (vp) { struct namecache *n2; TAILQ_FOREACH(n2, &vp->v_cache_dst, nc_dst) { if (n2->nc_dvp == dvp && n2->nc_nlen == cnp->cn_namelen && !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) { CACHE_UNLOCK(); cache_free(ncp); return; } } } numcache++; if (!vp) { numneg++; ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; } else if (vp->v_type == VDIR) { vp->v_dd = dvp; } else { vp->v_dd = NULL; } /* * Insert the new namecache entry into the appropriate chain * within the cache entries table. */ ncpp = NCHHASH(hash); LIST_INSERT_HEAD(ncpp, ncp, nc_hash); if (LIST_EMPTY(&dvp->v_cache_src)) { hold = 1; numcachehv++; } LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); /* * If the entry is "negative", we place it into the * "negative" cache queue, otherwise, we place it into the * destination vnode's cache entries queue. */ if (vp) { TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); } else { TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); } if (numneg * ncnegfactor > numcache) { ncp = TAILQ_FIRST(&ncneg); zap = 1; } if (hold) vhold(dvp); if (zap) cache_zap(ncp); CACHE_UNLOCK(); } /* * Name cache initialization, from vfs_init() when we are booting */ static void nchinit(void *dummy __unused) { TAILQ_INIT(&ncneg); cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); } SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); /* * Invalidate all entries to a particular vnode. */ void cache_purge(vp) struct vnode *vp; { CTR1(KTR_VFS, "cache_purge(%p)", vp); CACHE_LOCK(); while (!LIST_EMPTY(&vp->v_cache_src)) cache_zap(LIST_FIRST(&vp->v_cache_src)); while (!TAILQ_EMPTY(&vp->v_cache_dst)) cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); vp->v_dd = NULL; CACHE_UNLOCK(); } /* * Flush all entries referencing a particular filesystem. */ void cache_purgevfs(mp) struct mount *mp; { struct nchashhead *ncpp; struct namecache *ncp, *nnp; /* Scan hash tables for applicable entries */ CACHE_LOCK(); for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { if (ncp->nc_dvp->v_mount == mp) cache_zap(ncp); } } CACHE_UNLOCK(); } /* * Perform canonical checks and cache lookup and pass on to filesystem * through the vop_cachedlookup only if needed. */ int vfs_cache_lookup(ap) struct vop_lookup_args /* { struct vnode *a_dvp; struct vnode **a_vpp; struct componentname *a_cnp; } */ *ap; { struct vnode *dvp; int error; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; struct ucred *cred = cnp->cn_cred; int flags = cnp->cn_flags; struct thread *td = cnp->cn_thread; *vpp = NULL; dvp = ap->a_dvp; if (dvp->v_type != VDIR) return (ENOTDIR); if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); error = VOP_ACCESS(dvp, VEXEC, cred, td); if (error) return (error); error = cache_lookup(dvp, vpp, cnp); if (error == 0) return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); if (error == -1) return (0); return (error); } #ifndef _SYS_SYSPROTO_H_ struct __getcwd_args { u_char *buf; u_int buflen; }; #endif /* * XXX All of these sysctls would probably be more productive dead. */ static int disablecwd; SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "Disable the getcwd syscall"); /* Implementation of the getcwd syscall. */ int __getcwd(td, uap) struct thread *td; struct __getcwd_args *uap; { return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); } int kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen) { char *bp, *tmpbuf; struct filedesc *fdp; struct vnode *cdir, *rdir; int error, vfslocked; if (disablecwd) return (ENODEV); if (buflen < 2) return (EINVAL); if (buflen > MAXPATHLEN) buflen = MAXPATHLEN; tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); cdir = fdp->fd_cdir; VREF(cdir); rdir = fdp->fd_rdir; VREF(rdir); FILEDESC_SUNLOCK(fdp); error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); vfslocked = VFS_LOCK_GIANT(rdir->v_mount); vrele(rdir); VFS_UNLOCK_GIANT(vfslocked); vfslocked = VFS_LOCK_GIANT(cdir->v_mount); vrele(cdir); VFS_UNLOCK_GIANT(vfslocked); if (!error) { if (bufseg == UIO_SYSSPACE) bcopy(bp, buf, strlen(bp) + 1); else error = copyout(bp, buf, strlen(bp) + 1); } free(tmpbuf, M_TEMP); return (error); } /* * Thus begins the fullpath magic. */ #undef STATNODE #define STATNODE(name) \ static u_int name; \ SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "") static int disablefullpath; SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, "Disable the vn_fullpath function"); /* These count for kern___getcwd(), too. */ STATNODE(numfullpathcalls); STATNODE(numfullpathfail1); STATNODE(numfullpathfail2); STATNODE(numfullpathfail4); STATNODE(numfullpathfound); /* * Retrieve the full filesystem path that correspond to a vnode from the name * cache (if available) */ int vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) { char *buf; struct filedesc *fdp; struct vnode *rdir; int error, vfslocked; if (disablefullpath) return (ENODEV); if (vn == NULL) return (EINVAL); buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); rdir = fdp->fd_rdir; VREF(rdir); FILEDESC_SUNLOCK(fdp); error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); vfslocked = VFS_LOCK_GIANT(rdir->v_mount); vrele(rdir); VFS_UNLOCK_GIANT(vfslocked); if (!error) *freebuf = buf; else free(buf, M_TEMP); return (error); } /* * This function is similar to vn_fullpath, but it attempts to lookup the * pathname relative to the global root mount point. This is required for the * auditing sub-system, as audited pathnames must be absolute, relative to the * global root mount point. */ int vn_fullpath_global(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) { char *buf; int error; if (disablefullpath) return (ENODEV); if (vn == NULL) return (EINVAL); buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); if (!error) *freebuf = buf; else free(buf, M_TEMP); return (error); } /* * The magic behind kern___getcwd() and vn_fullpath(). */ static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, u_int buflen) { char *bp; int error, i, slash_prefixed; struct namecache *ncp; bp = buf + buflen - 1; *bp = '\0'; error = 0; slash_prefixed = 0; CACHE_LOCK(); numfullpathcalls++; if (vp->v_type != VDIR) { ncp = TAILQ_FIRST(&vp->v_cache_dst); if (!ncp) { numfullpathfail2++; CACHE_UNLOCK(); return (ENOENT); } for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--) *--bp = ncp->nc_name[i]; if (bp == buf) { numfullpathfail4++; CACHE_UNLOCK(); return (ENOMEM); } *--bp = '/'; slash_prefixed = 1; vp = ncp->nc_dvp; } while (vp != rdir && vp != rootvnode) { if (vp->v_vflag & VV_ROOT) { if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ error = EBADF; break; } vp = vp->v_mount->mnt_vnodecovered; continue; } if (vp->v_dd == NULL) { numfullpathfail1++; error = ENOTDIR; break; } ncp = TAILQ_FIRST(&vp->v_cache_dst); if (!ncp) { numfullpathfail2++; error = ENOENT; break; } MPASS(ncp->nc_dvp == vp->v_dd); for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) *--bp = ncp->nc_name[i]; if (bp == buf) { numfullpathfail4++; error = ENOMEM; break; } *--bp = '/'; slash_prefixed = 1; vp = ncp->nc_dvp; } if (error) { CACHE_UNLOCK(); return (error); } if (!slash_prefixed) { if (bp == buf) { numfullpathfail4++; CACHE_UNLOCK(); return (ENOMEM); } else { *--bp = '/'; } } numfullpathfound++; CACHE_UNLOCK(); *retbuf = bp; return (0); } int vn_commname(struct vnode *vp, char *buf, u_int buflen) { struct namecache *ncp; int l; CACHE_LOCK(); ncp = TAILQ_FIRST(&vp->v_cache_dst); if (!ncp) { CACHE_UNLOCK(); return (ENOENT); } l = min(ncp->nc_nlen, buflen - 1); memcpy(buf, ncp->nc_name, l); CACHE_UNLOCK(); buf[l] = '\0'; return (0); }