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freebsd-dev/sys/kern/vfs_cache.c
Andriy Gapon 4633a4c379 namecache sdt: freebsd doesn't support structured characters yet 
:-)

MFC after:	 7 days
2013-07-09 08:58:34 +00:00

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/*-
* 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);
}
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