diff options
Diffstat (limited to 'sys/kern/vfs_cache.c')
| -rw-r--r-- | sys/kern/vfs_cache.c | 1486 |
1 files changed, 1486 insertions, 0 deletions
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c new file mode 100644 index 0000000..31ed545 --- /dev/null +++ b/sys/kern/vfs_cache.c @@ -0,0 +1,1486 @@ +/*- + * 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 <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_kdtrace.h" +#include "opt_ktrace.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/filedesc.h> +#include <sys/fnv_hash.h> +#include <sys/kernel.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/fcntl.h> +#include <sys/mount.h> +#include <sys/namei.h> +#include <sys/proc.h> +#include <sys/rwlock.h> +#include <sys/sdt.h> +#include <sys/syscallsubr.h> +#include <sys/sysctl.h> +#include <sys/sysproto.h> +#include <sys/vnode.h> +#ifdef KTRACE +#include <sys/ktrace.h> +#endif + +#include <vm/uma.h> + +SDT_PROVIDER_DECLARE(vfs); +SDT_PROBE_DEFINE3(vfs, namecache, enter, done, done, "struct vnode *", "char *", + "struct vnode *"); +SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, done, "struct vnode *", + "char *"); +SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, entry, "struct vnode *"); +SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, hit, "struct vnode *", + "char *", "struct vnode *"); +SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, miss, "struct vnode *"); +SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, return, "int", + "struct vnode *", "char *"); +SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, hit, "struct vnode *", "char *", + "struct vnode *"); +SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit_negative, hit-negative, + "struct vnode *", "char *"); +SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, miss, "struct vnode *", + "char *"); +SDT_PROBE_DEFINE1(vfs, namecache, purge, done, done, "struct vnode *"); +SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, done, "struct vnode *"); +SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, done, "struct mount *"); +SDT_PROBE_DEFINE3(vfs, namecache, zap, done, done, "struct vnode *", "char *", + "struct vnode *"); +SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, done, "struct vnode *", + "char *"); + +/* + * 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 + nul */ +}; + +/* + * struct namecache_ts repeats struct namecache layout up to the + * nc_nlen member. + * struct namecache_ts is used in place of struct namecache when time(s) need + * to be stored. The nc_dotdottime field is used when a cache entry is mapping + * both a non-dotdot directory name plus dotdot for the directory's + * parent. + */ +struct namecache_ts { + 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 */ + struct timespec nc_time; /* timespec provided by fs */ + struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ + int nc_ticks; /* ticks value when entry was added */ + char nc_name[0]; /* segment name + nul */ +}; + +/* + * Flags in namecache.nc_flag + */ +#define NCF_WHITE 0x01 +#define NCF_ISDOTDOT 0x02 +#define NCF_TS 0x04 +#define NCF_DTS 0x08 + +/* + * 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, + "Size of namecache hash table"); +static u_long ncnegfactor = 16; /* ratio of negative entries */ +SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, + "Ratio of negative namecache entries"); +static u_long numneg; /* number of negative entries allocated */ +SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, + "Number of negative entries in namecache"); +static u_long numcache; /* number of cache entries allocated */ +SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, + "Number of namecache entries"); +static u_long numcachehv; /* number of cache entries with vnodes held */ +SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, + "Number of namecache entries with vnodes held"); +static u_int ncsizefactor = 2; +SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, + "Size factor for namecache"); + +struct nchstats nchstats; /* cache effectiveness statistics */ + +static struct rwlock cache_lock; +RW_SYSINIT(vfscache, &cache_lock, "Name Cache"); + +#define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock) +#define CACHE_RLOCK() rw_rlock(&cache_lock) +#define CACHE_RUNLOCK() rw_runlock(&cache_lock) +#define CACHE_WLOCK() rw_wlock(&cache_lock) +#define CACHE_WUNLOCK() rw_wunlock(&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_small_ts; +static uma_zone_t cache_zone_large; +static uma_zone_t cache_zone_large_ts; + +#define CACHE_PATH_CUTOFF 35 + +static struct namecache * +cache_alloc(int len, int ts) +{ + + if (len > CACHE_PATH_CUTOFF) { + if (ts) + return (uma_zalloc(cache_zone_large_ts, M_WAITOK)); + else + return (uma_zalloc(cache_zone_large, M_WAITOK)); + } + if (ts) + return (uma_zalloc(cache_zone_small_ts, M_WAITOK)); + else + return (uma_zalloc(cache_zone_small, M_WAITOK)); +} + +static void +cache_free(struct namecache *ncp) +{ + int ts; + + if (ncp == NULL) + return; + ts = ncp->nc_flag & NCF_TS; + if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) { + if (ts) + uma_zfree(cache_zone_small_ts, ncp); + else + uma_zfree(cache_zone_small, ncp); + } else if (ts) + uma_zfree(cache_zone_large_ts, ncp); + else + uma_zfree(cache_zone_large, ncp); +} + +static char * +nc_get_name(struct namecache *ncp) +{ + struct namecache_ts *ncp_ts; + + if ((ncp->nc_flag & NCF_TS) == 0) + return (ncp->nc_name); + ncp_ts = (struct namecache_ts *)ncp; + return (ncp_ts->nc_name); +} + +static void +cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) +{ + + KASSERT((ncp->nc_flag & NCF_TS) != 0 || + (tsp == NULL && ticksp == NULL), + ("No NCF_TS")); + + if (tsp != NULL) + *tsp = ((struct namecache_ts *)ncp)->nc_time; + if (ticksp != NULL) + *ticksp = ((struct namecache_ts *)ncp)->nc_ticks; +} + +static int doingcache = 1; /* 1 => enable the cache */ +SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, + "VFS namecache enabled"); + +/* Export size information to userland */ +SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0, + sizeof(struct namecache), "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, descr) \ + SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, descr); +STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries"); +STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries"); +static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls, + "Number of cache lookups"); +static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits, + "Number of '.' hits"); +static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits, + "Number of '..' hits"); +static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks, + "Number of checks in lookup"); +static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss, + "Number of cache misses"); +static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap, + "Number of cache misses we do not want to cache"); +static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps, + "Number of cache hits (positive) we do not want to cache"); +static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits, + "Number of cache hits (positive)"); +static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps, + "Number of cache hits (negative) we do not want to cache"); +static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits, + "Number of cache hits (negative)"); +static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades, + "Number of updates of the cache after lookup (write lock + retry)"); + +SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE, + &nchstats, sizeof(nchstats), "LU", + "VFS cache effectiveness statistics"); + + + +static void cache_zap(struct namecache *ncp); +static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, + u_int *buflen); +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"); + +#ifdef DIAGNOSTIC +/* + * Grab an atomic snapshot of the name cache hash chain lengths + */ +static 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_RLOCK(); + count = 0; + LIST_FOREACH(ncp, ncpp, nc_hash) { + count++; + } + CACHE_RUNLOCK(); + error = SYSCTL_OUT(req, &count, sizeof(count)); + if (error) + return (error); + } + return (0); +} +SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| + CTLFLAG_MPSAFE, 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_RLOCK(); + LIST_FOREACH(ncp, ncpp, nc_hash) { + count++; + } + CACHE_RUNLOCK(); + if (count) + used++; + if (maxlength < count) + maxlength = count; + } + n_nchash = nchash + 1; + pct = (used * 100) / (n_nchash / 100); + 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| + CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", + "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); +#endif + +/* + * 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; + + rw_assert(&cache_lock, RA_WLOCKED); + CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); +#ifdef KDTRACE_HOOKS + if (ncp->nc_vp != NULL) { + SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp, + nc_get_name(ncp), ncp->nc_vp, 0, 0); + } else { + SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp, + nc_get_name(ncp), 0, 0, 0); + } +#endif + vp = NULL; + LIST_REMOVE(ncp, nc_hash); + if (ncp->nc_flag & NCF_ISDOTDOT) { + if (ncp == ncp->nc_dvp->v_cache_dd) + ncp->nc_dvp->v_cache_dd = NULL; + } else { + 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); + if (ncp == ncp->nc_vp->v_cache_dd) + ncp->nc_vp->v_cache_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 + * ENOENT 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, tsp, ticksp) + struct vnode *dvp; + struct vnode **vpp; + struct componentname *cnp; + struct timespec *tsp; + int *ticksp; +{ + struct namecache *ncp; + uint32_t hash; + int error, ltype, wlocked; + + if (!doingcache) { + cnp->cn_flags &= ~MAKEENTRY; + return (0); + } +retry: + CACHE_RLOCK(); + wlocked = 0; + numcalls++; + error = 0; + +retry_wlocked: + 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++; + SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".", + *vpp, 0, 0); + if (tsp != NULL) + timespecclear(tsp); + if (ticksp != NULL) + *ticksp = ticks; + goto success; + } + if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { + dotdothits++; + if (dvp->v_cache_dd == NULL) { + SDT_PROBE(vfs, namecache, lookup, miss, dvp, + "..", NULL, 0, 0); + goto unlock; + } + if ((cnp->cn_flags & MAKEENTRY) == 0) { + if (!wlocked && !CACHE_UPGRADE_LOCK()) + goto wlock; + if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) + cache_zap(dvp->v_cache_dd); + dvp->v_cache_dd = NULL; + CACHE_WUNLOCK(); + return (0); + } + ncp = dvp->v_cache_dd; + if (ncp->nc_flag & NCF_ISDOTDOT) + *vpp = ncp->nc_vp; + else + *vpp = ncp->nc_dvp; + /* Return failure if negative entry was found. */ + if (*vpp == NULL) + goto negative_success; + CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", + dvp, cnp->cn_nameptr, *vpp); + SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..", + *vpp, 0, 0); + cache_out_ts(ncp, tsp, ticksp); + if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == + NCF_DTS && tsp != NULL) + *tsp = ((struct namecache_ts *)ncp)-> + nc_dotdottime; + 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(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) + break; + } + + /* We failed to find an entry */ + if (ncp == NULL) { + SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, + NULL, 0, 0); + if ((cnp->cn_flags & MAKEENTRY) == 0) { + nummisszap++; + } else { + nummiss++; + } + nchstats.ncs_miss++; + goto unlock; + } + + /* We don't want to have an entry, so dump it */ + if ((cnp->cn_flags & MAKEENTRY) == 0) { + numposzaps++; + nchstats.ncs_badhits++; + if (!wlocked && !CACHE_UPGRADE_LOCK()) + goto wlock; + cache_zap(ncp); + CACHE_WUNLOCK(); + 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); + SDT_PROBE(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), + *vpp, 0, 0); + cache_out_ts(ncp, tsp, ticksp); + goto success; + } + +negative_success: + /* We found a negative match, and want to create it, so purge */ + if (cnp->cn_nameiop == CREATE) { + numnegzaps++; + nchstats.ncs_badhits++; + if (!wlocked && !CACHE_UPGRADE_LOCK()) + goto wlock; + cache_zap(ncp); + CACHE_WUNLOCK(); + return (0); + } + + if (!wlocked && !CACHE_UPGRADE_LOCK()) + goto wlock; + 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; + SDT_PROBE(vfs, namecache, lookup, hit_negative, dvp, nc_get_name(ncp), + 0, 0, 0); + cache_out_ts(ncp, tsp, ticksp); + CACHE_WUNLOCK(); + return (ENOENT); + +wlock: + /* + * We need to update the cache after our lookup, so upgrade to + * a write lock and retry the operation. + */ + CACHE_RUNLOCK(); + CACHE_WLOCK(); + numupgrades++; + wlocked = 1; + goto retry_wlocked; + +success: + /* + * On success we return a locked and ref'd vnode as per the lookup + * protocol. + */ + if (dvp == *vpp) { /* lookup on "." */ + VREF(*vpp); + if (wlocked) + CACHE_WUNLOCK(); + else + CACHE_RUNLOCK(); + /* + * 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 (ENOENT); + } + } 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); + if (wlocked) + CACHE_WUNLOCK(); + else + CACHE_RUNLOCK(); + error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); + if (cnp->cn_flags & ISDOTDOT) { + vn_lock(dvp, ltype | LK_RETRY); + if (dvp->v_iflag & VI_DOOMED) { + if (error == 0) + vput(*vpp); + *vpp = NULL; + return (ENOENT); + } + } + 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); + +unlock: + if (wlocked) + CACHE_WUNLOCK(); + else + CACHE_RUNLOCK(); + return (0); +} + +/* + * Add an entry to the cache. + */ +void +cache_enter_time(dvp, vp, cnp, tsp, dtsp) + struct vnode *dvp; + struct vnode *vp; + struct componentname *cnp; + struct timespec *tsp; + struct timespec *dtsp; +{ + struct namecache *ncp, *n2; + struct namecache_ts *n3; + struct nchashhead *ncpp; + uint32_t hash; + int flag; + 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, + ("cache_enter: Adding a doomed vnode")); + VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, + ("cache_enter: Doomed vnode used as src")); + + if (!doingcache) + return; + + /* + * Avoid blowout in namecache entries. + */ + if (numcache >= desiredvnodes * ncsizefactor) + return; + + flag = 0; + if (cnp->cn_nameptr[0] == '.') { + if (cnp->cn_namelen == 1) + return; + if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { + CACHE_WLOCK(); + /* + * If dotdot entry already exists, just retarget it + * to new parent vnode, otherwise continue with new + * namecache entry allocation. + */ + if ((ncp = dvp->v_cache_dd) != NULL && + ncp->nc_flag & NCF_ISDOTDOT) { + KASSERT(ncp->nc_dvp == dvp, + ("wrong isdotdot parent")); + if (ncp->nc_vp != NULL) + TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, + ncp, nc_dst); + else + TAILQ_REMOVE(&ncneg, ncp, nc_dst); + if (vp != NULL) + TAILQ_INSERT_HEAD(&vp->v_cache_dst, + ncp, nc_dst); + else + TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); + ncp->nc_vp = vp; + CACHE_WUNLOCK(); + return; + } + dvp->v_cache_dd = NULL; + SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp, + 0, 0); + CACHE_WUNLOCK(); + flag = NCF_ISDOTDOT; + } + } + + 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, tsp != NULL); + ncp->nc_vp = vp; + ncp->nc_dvp = dvp; + ncp->nc_flag = flag; + if (tsp != NULL) { + n3 = (struct namecache_ts *)ncp; + n3->nc_time = *tsp; + n3->nc_ticks = ticks; + n3->nc_flag |= NCF_TS; + if (dtsp != NULL) { + n3->nc_dotdottime = *dtsp; + n3->nc_flag |= NCF_DTS; + } + } + len = ncp->nc_nlen = cnp->cn_namelen; + hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); + strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); + hash = fnv_32_buf(&dvp, sizeof(dvp), hash); + CACHE_WLOCK(); + + /* + * See if this vnode or negative entry is already in the cache + * with this name. This can happen with concurrent lookups of + * the same path name. + */ + ncpp = NCHHASH(hash); + LIST_FOREACH(n2, ncpp, nc_hash) { + if (n2->nc_dvp == dvp && + n2->nc_nlen == cnp->cn_namelen && + !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { + if (tsp != NULL) { + KASSERT((n2->nc_flag & NCF_TS) != 0, + ("no NCF_TS")); + n3 = (struct namecache_ts *)n2; + n3->nc_time = + ((struct namecache_ts *)ncp)->nc_time; + n3->nc_ticks = + ((struct namecache_ts *)ncp)->nc_ticks; + if (dtsp != NULL) { + n3->nc_dotdottime = + ((struct namecache_ts *)ncp)-> + nc_dotdottime; + n3->nc_flag |= NCF_DTS; + } + } + CACHE_WUNLOCK(); + cache_free(ncp); + return; + } + } + + if (flag == NCF_ISDOTDOT) { + /* + * See if we are trying to add .. entry, but some other lookup + * has populated v_cache_dd pointer already. + */ + if (dvp->v_cache_dd != NULL) { + CACHE_WUNLOCK(); + cache_free(ncp); + return; + } + KASSERT(vp == NULL || vp->v_type == VDIR, + ("wrong vnode type %p", vp)); + dvp->v_cache_dd = ncp; + } + + numcache++; + if (!vp) { + numneg++; + if (cnp->cn_flags & ISWHITEOUT) + ncp->nc_flag |= NCF_WHITE; + } else if (vp->v_type == VDIR) { + if (flag != NCF_ISDOTDOT) { + /* + * For this case, the cache entry maps both the + * directory name in it and the name ".." for the + * directory's parent. + */ + if ((n2 = vp->v_cache_dd) != NULL && + (n2->nc_flag & NCF_ISDOTDOT) != 0) + cache_zap(n2); + vp->v_cache_dd = ncp; + } + } else { + vp->v_cache_dd = NULL; + } + + /* + * Insert the new namecache entry into the appropriate chain + * within the cache entries table. + */ + LIST_INSERT_HEAD(ncpp, ncp, nc_hash); + if (flag != NCF_ISDOTDOT) { + 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); + SDT_PROBE(vfs, namecache, enter, done, dvp, nc_get_name(ncp), + vp, 0, 0); + } else { + TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); + SDT_PROBE(vfs, namecache, enter_negative, done, dvp, + nc_get_name(ncp), 0, 0, 0); + } + if (numneg * ncnegfactor > numcache) { + ncp = TAILQ_FIRST(&ncneg); + zap = 1; + } + if (hold) + vhold(dvp); + if (zap) + cache_zap(ncp); + CACHE_WUNLOCK(); +} + +/* + * 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", + sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, + NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); + cache_zone_small_ts = uma_zcreate("STS VFS Cache", + sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, + NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); + cache_zone_large = uma_zcreate("L VFS Cache", + sizeof(struct namecache) + NAME_MAX + 1, + NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); + cache_zone_large_ts = uma_zcreate("LTS VFS Cache", + sizeof(struct namecache_ts) + NAME_MAX + 1, + 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); + SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0); + CACHE_WLOCK(); + 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)); + if (vp->v_cache_dd != NULL) { + KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, + ("lost dotdot link")); + cache_zap(vp->v_cache_dd); + } + KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); + CACHE_WUNLOCK(); +} + +/* + * Invalidate all negative entries for a particular directory vnode. + */ +void +cache_purge_negative(vp) + struct vnode *vp; +{ + struct namecache *cp, *ncp; + + CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); + SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0); + CACHE_WLOCK(); + LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) { + if (cp->nc_vp == NULL) + cache_zap(cp); + } + CACHE_WUNLOCK(); +} + +/* + * 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 */ + SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0); + CACHE_WLOCK(); + 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_WUNLOCK(); +} + +/* + * 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, NULL, NULL); + 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 +sys___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; + + 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); + vrele(rdir); + vrele(cdir); + + if (!error) { + if (bufseg == UIO_SYSSPACE) + bcopy(bp, buf, strlen(bp) + 1); + else + error = copyout(bp, buf, strlen(bp) + 1); +#ifdef KTRACE + if (KTRPOINT(curthread, KTR_NAMEI)) + ktrnamei(bp); +#endif + } + free(tmpbuf, M_TEMP); + return (error); +} + +/* + * Thus begins the fullpath magic. + */ + +#undef STATNODE +#define STATNODE(name, descr) \ + static u_int name; \ + SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr) + +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, "Number of fullpath search calls"); +STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); +STATNODE(numfullpathfail2, + "Number of fullpath search errors (VOP_VPTOCNP failures)"); +STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); +STATNODE(numfullpathfound, "Number of successful fullpath calls"); + +/* + * 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; + + 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); + vrele(rdir); + + 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); +} + +int +vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) +{ + int error; + + CACHE_RLOCK(); + error = vn_vptocnp_locked(vp, cred, buf, buflen); + if (error == 0) + CACHE_RUNLOCK(); + return (error); +} + +static int +vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, + u_int *buflen) +{ + struct vnode *dvp; + struct namecache *ncp; + int error; + + TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { + if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) + break; + } + if (ncp != NULL) { + if (*buflen < ncp->nc_nlen) { + CACHE_RUNLOCK(); + vrele(*vp); + numfullpathfail4++; + error = ENOMEM; + SDT_PROBE(vfs, namecache, fullpath, return, error, + vp, NULL, 0, 0); + return (error); + } + *buflen -= ncp->nc_nlen; + memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); + SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp, + nc_get_name(ncp), vp, 0, 0); + dvp = *vp; + *vp = ncp->nc_dvp; + vref(*vp); + CACHE_RUNLOCK(); + vrele(dvp); + CACHE_RLOCK(); + return (0); + } + SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0); + + CACHE_RUNLOCK(); + vn_lock(*vp, LK_SHARED | LK_RETRY); + error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); + vput(*vp); + if (error) { + numfullpathfail2++; + SDT_PROBE(vfs, namecache, fullpath, return, error, vp, + NULL, 0, 0); + return (error); + } + + *vp = dvp; + CACHE_RLOCK(); + if (dvp->v_iflag & VI_DOOMED) { + /* forced unmount */ + CACHE_RUNLOCK(); + vrele(dvp); + error = ENOENT; + SDT_PROBE(vfs, namecache, fullpath, return, error, vp, + NULL, 0, 0); + return (error); + } + /* + * *vp has its use count incremented still. + */ + + return (0); +} + +/* + * 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) +{ + int error, slash_prefixed; +#ifdef KDTRACE_HOOKS + struct vnode *startvp = vp; +#endif + struct vnode *vp1; + + buflen--; + buf[buflen] = '\0'; + error = 0; + slash_prefixed = 0; + + SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0); + numfullpathcalls++; + vref(vp); + CACHE_RLOCK(); + if (vp->v_type != VDIR) { + error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); + if (error) + return (error); + if (buflen == 0) { + CACHE_RUNLOCK(); + vrele(vp); + return (ENOMEM); + } + buf[--buflen] = '/'; + slash_prefixed = 1; + } + while (vp != rdir && vp != rootvnode) { + if (vp->v_vflag & VV_ROOT) { + if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ + CACHE_RUNLOCK(); + vrele(vp); + error = ENOENT; + SDT_PROBE(vfs, namecache, fullpath, return, + error, vp, NULL, 0, 0); + break; + } + vp1 = vp->v_mount->mnt_vnodecovered; + vref(vp1); + CACHE_RUNLOCK(); + vrele(vp); + vp = vp1; + CACHE_RLOCK(); + continue; + } + if (vp->v_type != VDIR) { + CACHE_RUNLOCK(); + vrele(vp); + numfullpathfail1++; + error = ENOTDIR; + SDT_PROBE(vfs, namecache, fullpath, return, + error, vp, NULL, 0, 0); + break; + } + error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); + if (error) + break; + if (buflen == 0) { + CACHE_RUNLOCK(); + vrele(vp); + error = ENOMEM; + SDT_PROBE(vfs, namecache, fullpath, return, error, + startvp, NULL, 0, 0); + break; + } + buf[--buflen] = '/'; + slash_prefixed = 1; + } + if (error) + return (error); + if (!slash_prefixed) { + if (buflen == 0) { + CACHE_RUNLOCK(); + vrele(vp); + numfullpathfail4++; + SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM, + startvp, NULL, 0, 0); + return (ENOMEM); + } + buf[--buflen] = '/'; + } + numfullpathfound++; + CACHE_RUNLOCK(); + vrele(vp); + + SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen, + 0, 0); + *retbuf = buf + buflen; + return (0); +} + +struct vnode * +vn_dir_dd_ino(struct vnode *vp) +{ + struct namecache *ncp; + struct vnode *ddvp; + + ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); + CACHE_RLOCK(); + TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { + if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) + continue; + ddvp = ncp->nc_dvp; + VI_LOCK(ddvp); + CACHE_RUNLOCK(); + if (vget(ddvp, LK_INTERLOCK | LK_SHARED | LK_NOWAIT, curthread)) + return (NULL); + return (ddvp); + } + CACHE_RUNLOCK(); + return (NULL); +} + +int +vn_commname(struct vnode *vp, char *buf, u_int buflen) +{ + struct namecache *ncp; + int l; + + CACHE_RLOCK(); + TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) + if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) + break; + if (ncp == NULL) { + CACHE_RUNLOCK(); + return (ENOENT); + } + l = min(ncp->nc_nlen, buflen - 1); + memcpy(buf, nc_get_name(ncp), l); + CACHE_RUNLOCK(); + buf[l] = '\0'; + return (0); +} + +/* ABI compat shims for old kernel modules. */ +#undef cache_enter + +void cache_enter(struct vnode *dvp, struct vnode *vp, + struct componentname *cnp); + +void +cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) +{ + + cache_enter_time(dvp, vp, cnp, NULL, NULL); +} + +/* + * This function updates path string to vnode's full global path + * and checks the size of the new path string against the pathlen argument. + * + * Requires a locked, referenced vnode and GIANT lock held. + * Vnode is re-locked on success or ENODEV, otherwise unlocked. + * + * If sysctl debug.disablefullpath is set, ENODEV is returned, + * vnode is left locked and path remain untouched. + * + * If vp is a directory, the call to vn_fullpath_global() always succeeds + * because it falls back to the ".." lookup if the namecache lookup fails. + */ +int +vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, + u_int pathlen) +{ + struct nameidata nd; + struct vnode *vp1; + char *rpath, *fbuf; + int error; + + ASSERT_VOP_ELOCKED(vp, __func__); + + /* Return ENODEV if sysctl debug.disablefullpath==1 */ + if (disablefullpath) + return (ENODEV); + + /* Construct global filesystem path from vp. */ + VOP_UNLOCK(vp, 0); + error = vn_fullpath_global(td, vp, &rpath, &fbuf); + + if (error != 0) { + vrele(vp); + return (error); + } + + if (strlen(rpath) >= pathlen) { + vrele(vp); + error = ENAMETOOLONG; + goto out; + } + + /* + * Re-lookup the vnode by path to detect a possible rename. + * As a side effect, the vnode is relocked. + * If vnode was renamed, return ENOENT. + */ + NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, + UIO_SYSSPACE, path, td); + error = namei(&nd); + if (error != 0) { + vrele(vp); + goto out; + } + NDFREE(&nd, NDF_ONLY_PNBUF); + vp1 = nd.ni_vp; + vrele(vp); + if (vp1 == vp) + strcpy(path, rpath); + else { + vput(vp1); + error = ENOENT; + } + +out: + free(fbuf, M_TEMP); + return (error); +} |
