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freebsd-dev/sys/kern/vfs_cache.c
Mateusz Guzik 1d2541fd1a cache: get rid of the global lock 
Add a table of vnode locks and use them along with bucketlocks to provide
concurrent modification support. The approach taken is to preserve the
current behaviour of the namecache and just lock all relevant parts before
any changes are made.

Lookups still require the relevant bucket to be locked.

Discussed with:		kib
Tested by:	pho
2016-09-23 04:45:11 +00:00

2243 lines
56 KiB
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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.
* 3. 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_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/counter.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/smp.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, "struct vnode *", "char *",
"struct vnode *");
SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
"char *");
SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
"char *", "struct vnode *");
SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int",
"struct vnode *", "char *");
SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
"struct vnode *");
SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative,
"struct vnode *", "char *");
SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
"char *");
SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *");
SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
"struct vnode *");
SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, 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
#define NCF_DVDROP 0x10
/*
* 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.
*
* These locks are used (in the order in which they can be taken):
* NAME TYPE ROLE
* vnodelock mtx vnode lists and v_cache_dd field protection
* bucketlock rwlock for access to given set of hash buckets
* ncneg_mtx mtx negative entry LRU management
*
* Additionally, ncneg_shrink_lock mtx is used to have at most one thread
* shrinking the LRU list.
*
* It is legal to take multiple vnodelock and bucketlock locks. The locking
* order is lower address first. Both are recursive.
*
* "." lookups are lockless.
*
* ".." and vnode -> name lookups require vnodelock.
*
* name -> vnode lookup requires the relevant bucketlock to be held for reading.
*
* Insertions and removals of entries require involved vnodes and bucketlocks
* to be write-locked to prevent other threads from seeing the entry.
*
* Some lookups result in removal of the found entry (e.g. getting rid of a
* negative entry with the intent to create a positive one), which poses a
* problem when multiple threads reach the state. Similarly, two different
* threads can purge two different vnodes and try to remove the same name.
*
* If the already held vnode lock is lower than the second required lock, we
* can just take the other lock. However, in the opposite case, this could
* deadlock. As such, this is resolved by trylocking and if that fails unlocking
* the first node, locking everything in order and revalidating the state.
*/
/*
* Structures associated with name caching.
*/
#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");
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 mtx ncneg_shrink_lock;
MTX_SYSINIT(vfscache_shrink_neg, &ncneg_shrink_lock, "Name Cache shrink neg",
MTX_DEF);
static struct mtx_padalign ncneg_mtx;
MTX_SYSINIT(vfscache_neg, &ncneg_mtx, "ncneg", MTX_DEF);
static u_int numbucketlocks;
static struct rwlock_padalign *bucketlocks;
#define HASH2BUCKETLOCK(hash) \
((struct rwlock *)(&bucketlocks[((hash) % numbucketlocks)]))
static u_int numvnodelocks;
static struct mtx *vnodelocks;
static inline struct mtx *
VP2VNODELOCK(struct vnode *vp)
{
struct mtx *vlp;
if (vp == NULL)
return (NULL);
vlp = &vnodelocks[(((uintptr_t)(vp) >> 8) % numvnodelocks)];
return (vlp);
}
/*
* 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_flag & NCF_DVDROP) != 0)
vdrop(ncp->nc_dvp);
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, SYSCTL_NULL_INT_PTR,
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_ULONG(name, descr) \
SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr);
#define STATNODE_COUNTER(name, descr) \
static counter_u64_t name; \
SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr);
STATNODE_ULONG(numneg, "Number of negative cache entries");
STATNODE_ULONG(numcache, "Number of cache entries");
STATNODE_COUNTER(numcalls, "Number of cache lookups");
STATNODE_COUNTER(dothits, "Number of '.' hits");
STATNODE_COUNTER(dotdothits, "Number of '..' hits");
STATNODE_COUNTER(numchecks, "Number of checks in lookup");
STATNODE_COUNTER(nummiss, "Number of cache misses");
STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache");
STATNODE_COUNTER(numposzaps,
"Number of cache hits (positive) we do not want to cache");
STATNODE_COUNTER(numposhits, "Number of cache hits (positive)");
STATNODE_COUNTER(numnegzaps,
"Number of cache hits (negative) we do not want to cache");
STATNODE_COUNTER(numneghits, "Number of cache hits (negative)");
/* These count for kern___getcwd(), too. */
STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls");
STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
STATNODE_COUNTER(numfullpathfail2,
"Number of fullpath search errors (VOP_VPTOCNP failures)");
STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)");
STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls");
static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail,
"Number of times zap_and_exit failed to lock");
static long cache_lock_vnodes_cel_3_failures;
STATNODE_ULONG(cache_lock_vnodes_cel_3_failures,
"Number of times 3-way vnode locking failed");
static void cache_zap_locked(struct namecache *ncp, bool neg_locked);
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");
static int cache_yield;
SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0,
"Number of times cache called yield");
static void
cache_maybe_yield(void)
{
if (should_yield()) {
cache_yield++;
kern_yield(PRI_USER);
}
}
static inline void
cache_assert_vlp_locked(struct mtx *vlp)
{
if (vlp != NULL)
mtx_assert(vlp, MA_OWNED);
}
static inline void
cache_assert_vnode_locked(struct vnode *vp)
{
struct mtx *vlp;
vlp = VP2VNODELOCK(vp);
cache_assert_vlp_locked(vlp);
}
static uint32_t
cache_get_hash(char *name, u_char len, struct vnode *dvp)
{
uint32_t hash;
hash = fnv_32_buf(name, len, FNV1_32_INIT);
hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
return (hash);
}
static inline struct rwlock *
NCP2BUCKETLOCK(struct namecache *ncp)
{
uint32_t hash;
hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, ncp->nc_dvp);
return (HASH2BUCKETLOCK(hash));
}
#ifdef INVARIANTS
static void
cache_assert_bucket_locked(struct namecache *ncp, int mode)
{
struct rwlock *blp;
blp = NCP2BUCKETLOCK(ncp);
rw_assert(blp, mode);
}
#else
#define cache_assert_bucket_locked(x, y) do { } while (0)
#endif
#define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y))
static void
_cache_sort(void **p1, void **p2)
{
void *tmp;
if (*p1 > *p2) {
tmp = *p2;
*p2 = *p1;
*p1 = tmp;
}
}
static void
cache_lock_all_buckets(void)
{
u_int i;
for (i = 0; i < numbucketlocks; i++)
rw_wlock(&bucketlocks[i]);
}
static void
cache_unlock_all_buckets(void)
{
u_int i;
for (i = 0; i < numbucketlocks; i++)
rw_wunlock(&bucketlocks[i]);
}
static void
cache_lock_all_vnodes(void)
{
u_int i;
for (i = 0; i < numvnodelocks; i++)
mtx_lock(&vnodelocks[i]);
}
static void
cache_unlock_all_vnodes(void)
{
u_int i;
for (i = 0; i < numvnodelocks; i++)
mtx_unlock(&vnodelocks[i]);
}
static int
cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
{
cache_sort(&vlp1, &vlp2);
MPASS(vlp2 != NULL);
if (vlp1 != NULL) {
if (!mtx_trylock(vlp1))
return (EAGAIN);
}
if (!mtx_trylock(vlp2)) {
if (vlp1 != NULL)
mtx_unlock(vlp1);
return (EAGAIN);
}
return (0);
}
static void
cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
{
MPASS(vlp1 != NULL || vlp2 != NULL);
if (vlp1 != NULL)
mtx_unlock(vlp1);
if (vlp2 != NULL)
mtx_unlock(vlp2);
}
static int
sysctl_nchstats(SYSCTL_HANDLER_ARGS)
{
struct nchstats snap;
if (req->oldptr == NULL)
return (SYSCTL_OUT(req, 0, sizeof(snap)));
snap = nchstats;
snap.ncs_goodhits = counter_u64_fetch(numposhits);
snap.ncs_neghits = counter_u64_fetch(numneghits);
snap.ncs_badhits = counter_u64_fetch(numposzaps) +
counter_u64_fetch(numnegzaps);
snap.ncs_miss = counter_u64_fetch(nummisszap) +
counter_u64_fetch(nummiss);
return (SYSCTL_OUT(req, &snap, sizeof(snap)));
}
SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD |
CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU",
"VFS cache effectiveness statistics");
#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)
{
struct nchashhead *ncpp;
struct namecache *ncp;
int i, error, n_nchash, *cntbuf;
retry:
n_nchash = nchash + 1; /* nchash is max index, not count */
if (req->oldptr == NULL)
return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK);
cache_lock_all_buckets();
if (n_nchash != nchash + 1) {
cache_unlock_all_buckets();
free(cntbuf, M_TEMP);
goto retry;
}
/* Scan hash tables counting entries */
for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++)
LIST_FOREACH(ncp, ncpp, nc_hash)
cntbuf[i]++;
cache_unlock_all_buckets();
for (error = 0, i = 0; i < n_nchash; i++)
if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0)
break;
free(cntbuf, M_TEMP);
return (error);
}
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));
cache_lock_all_buckets();
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;
LIST_FOREACH(ncp, ncpp, nc_hash) {
count++;
}
if (count)
used++;
if (maxlength < count)
maxlength = count;
}
n_nchash = nchash + 1;
cache_unlock_all_buckets();
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
/*
* Negative entries management
*/
static void
cache_negative_hit(struct namecache *ncp)
{
MPASS(ncp->nc_vp == NULL);
mtx_lock(&ncneg_mtx);
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
mtx_unlock(&ncneg_mtx);
}
static void
cache_negative_insert(struct namecache *ncp)
{
MPASS(ncp->nc_vp == NULL);
cache_assert_bucket_locked(ncp, RA_WLOCKED);
mtx_lock(&ncneg_mtx);
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
numneg++;
mtx_unlock(&ncneg_mtx);
}
static void
cache_negative_remove(struct namecache *ncp, bool neg_locked)
{
MPASS(ncp->nc_vp == NULL);
cache_assert_bucket_locked(ncp, RA_WLOCKED);
if (!neg_locked)
mtx_lock(&ncneg_mtx);
else
mtx_assert(&ncneg_mtx, MA_OWNED);
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
numneg--;
if (!neg_locked)
mtx_unlock(&ncneg_mtx);
}
static void
cache_negative_zap_one(void)
{
struct namecache *ncp, *ncp2;
struct mtx *dvlp;
struct rwlock *blp;
if (!mtx_trylock(&ncneg_shrink_lock))
return;
mtx_lock(&ncneg_mtx);
ncp = TAILQ_FIRST(&ncneg);
if (ncp == NULL) {
mtx_unlock(&ncneg_mtx);
goto out;
}
MPASS(ncp->nc_vp == NULL);
dvlp = VP2VNODELOCK(ncp->nc_dvp);
blp = NCP2BUCKETLOCK(ncp);
mtx_unlock(&ncneg_mtx);
mtx_lock(dvlp);
rw_wlock(blp);
mtx_lock(&ncneg_mtx);
ncp2 = TAILQ_FIRST(&ncneg);
if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) ||
blp != NCP2BUCKETLOCK(ncp2) || ncp2->nc_vp != NULL) {
ncp = NULL;
goto out_unlock_all;
}
cache_zap_locked(ncp, true);
out_unlock_all:
mtx_unlock(&ncneg_mtx);
rw_wunlock(blp);
mtx_unlock(dvlp);
out:
mtx_unlock(&ncneg_shrink_lock);
cache_free(ncp);
}
/*
* cache_zap_locked():
*
* 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_locked(struct namecache *ncp, bool neg_locked)
{
cache_assert_vnode_locked(ncp->nc_vp);
cache_assert_vnode_locked(ncp->nc_dvp);
cache_assert_bucket_locked(ncp, RA_WLOCKED);
CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp);
if (ncp->nc_vp != NULL) {
SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp,
nc_get_name(ncp), ncp->nc_vp);
} else {
SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp,
nc_get_name(ncp));
}
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)) {
ncp->nc_flag |= NCF_DVDROP;
atomic_subtract_rel_long(&numcachehv, 1);
}
}
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 {
cache_negative_remove(ncp, neg_locked);
}
atomic_subtract_rel_long(&numcache, 1);
}
static void
cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp)
{
struct rwlock *blp;
MPASS(ncp->nc_dvp == vp);
MPASS(ncp->nc_vp == NULL);
cache_assert_vnode_locked(vp);
blp = NCP2BUCKETLOCK(ncp);
rw_wlock(blp);
cache_zap_locked(ncp, false);
rw_wunlock(blp);
}
static bool
cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp,
struct mtx **vlpp)
{
struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
struct rwlock *blp;
MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
cache_assert_vnode_locked(vp);
if (ncp->nc_vp == NULL) {
if (*vlpp != NULL) {
mtx_unlock(*vlpp);
*vlpp = NULL;
}
cache_zap_negative_locked_vnode_kl(ncp, vp);
return (true);
}
pvlp = VP2VNODELOCK(vp);
blp = NCP2BUCKETLOCK(ncp);
vlp1 = VP2VNODELOCK(ncp->nc_dvp);
vlp2 = VP2VNODELOCK(ncp->nc_vp);
if (*vlpp == vlp1 || *vlpp == vlp2) {
to_unlock = *vlpp;
*vlpp = NULL;
} else {
if (*vlpp != NULL) {
mtx_unlock(*vlpp);
*vlpp = NULL;
}
cache_sort(&vlp1, &vlp2);
if (vlp1 == pvlp) {
mtx_lock(vlp2);
to_unlock = vlp2;
} else {
if (!mtx_trylock(vlp1))
goto out_relock;
to_unlock = vlp1;
}
}
rw_wlock(blp);
cache_zap_locked(ncp, false);
rw_wunlock(blp);
if (to_unlock != NULL)
mtx_unlock(to_unlock);
return (true);
out_relock:
mtx_unlock(vlp2);
mtx_lock(vlp1);
mtx_lock(vlp2);
MPASS(*vlpp == NULL);
*vlpp = vlp1;
return (false);
}
static int
cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp)
{
struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
struct rwlock *blp;
int error = 0;
MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
cache_assert_vnode_locked(vp);
pvlp = VP2VNODELOCK(vp);
if (ncp->nc_vp == NULL) {
cache_zap_negative_locked_vnode_kl(ncp, vp);
goto out;
}
blp = NCP2BUCKETLOCK(ncp);
vlp1 = VP2VNODELOCK(ncp->nc_dvp);
vlp2 = VP2VNODELOCK(ncp->nc_vp);
cache_sort(&vlp1, &vlp2);
if (vlp1 == pvlp) {
mtx_lock(vlp2);
to_unlock = vlp2;
} else {
if (!mtx_trylock(vlp1)) {
error = EAGAIN;
goto out;
}
to_unlock = vlp1;
}
rw_wlock(blp);
cache_zap_locked(ncp, false);
rw_wunlock(blp);
mtx_unlock(to_unlock);
out:
mtx_unlock(pvlp);
return (error);
}
static int
cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp)
{
struct mtx *dvlp, *vlp;
cache_assert_bucket_locked(ncp, RA_RLOCKED);
dvlp = VP2VNODELOCK(ncp->nc_dvp);
vlp = VP2VNODELOCK(ncp->nc_vp);
if (cache_trylock_vnodes(dvlp, vlp) == 0) {
rw_runlock(blp);
rw_wlock(blp);
cache_zap_locked(ncp, false);
rw_wunlock(blp);
cache_unlock_vnodes(dvlp, vlp);
return (0);
}
rw_runlock(blp);
return (EAGAIN);
}
static int
cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp,
struct mtx **vlpp1, struct mtx **vlpp2)
{
struct mtx *dvlp, *vlp;
cache_assert_bucket_locked(ncp, RA_WLOCKED);
dvlp = VP2VNODELOCK(ncp->nc_dvp);
vlp = VP2VNODELOCK(ncp->nc_vp);
cache_sort(&dvlp, &vlp);
if (*vlpp1 == dvlp && *vlpp2 == vlp) {
cache_zap_locked(ncp, false);
cache_unlock_vnodes(dvlp, vlp);
*vlpp1 = NULL;
*vlpp2 = NULL;
return (0);
}
if (*vlpp1 != NULL)
mtx_unlock(*vlpp1);
if (*vlpp2 != NULL)
mtx_unlock(*vlpp2);
*vlpp1 = NULL;
*vlpp2 = NULL;
if (cache_trylock_vnodes(dvlp, vlp) == 0) {
cache_zap_locked(ncp, false);
cache_unlock_vnodes(dvlp, vlp);
return (0);
}
rw_wunlock(blp);
*vlpp1 = dvlp;
*vlpp2 = vlp;
if (*vlpp1 != NULL)
mtx_lock(*vlpp1);
mtx_lock(*vlpp2);
rw_wlock(blp);
return (EAGAIN);
}
static void
cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp)
{
if (blp != NULL) {
rw_runlock(blp);
mtx_assert(vlp, MA_NOTOWNED);
} else {
mtx_unlock(vlp);
}
}
/*
* 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 caching), 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(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
struct timespec *tsp, int *ticksp)
{
struct namecache *ncp;
struct rwlock *blp;
struct mtx *dvlp, *dvlp2;
uint32_t hash;
int error, ltype;
if (!doingcache) {
cnp->cn_flags &= ~MAKEENTRY;
return (0);
}
retry:
blp = NULL;
dvlp = VP2VNODELOCK(dvp);
error = 0;
counter_u64_add(numcalls, 1);
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);
counter_u64_add(dothits, 1);
SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
if (tsp != NULL)
timespecclear(tsp);
if (ticksp != NULL)
*ticksp = ticks;
VREF(*vpp);
/*
* 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);
}
if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
counter_u64_add(dotdothits, 1);
dvlp2 = NULL;
mtx_lock(dvlp);
retry_dotdot:
ncp = dvp->v_cache_dd;
if (ncp == NULL) {
SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
"..", NULL);
mtx_unlock(dvlp);
return (0);
}
if ((cnp->cn_flags & MAKEENTRY) == 0) {
if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
if (ncp->nc_dvp != dvp)
panic("dvp %p v_cache_dd %p\n", dvp, ncp);
if (!cache_zap_locked_vnode_kl2(ncp,
dvp, &dvlp2))
goto retry_dotdot;
MPASS(dvp->v_cache_dd == NULL);
mtx_unlock(dvlp);
if (dvlp2 != NULL)
mtx_unlock(dvlp2);
cache_free(ncp);
} else {
dvp->v_cache_dd = NULL;
mtx_unlock(dvlp);
if (dvlp2 != NULL)
mtx_unlock(dvlp2);
}
return (0);
}
if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
*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_PROBE3(vfs, namecache, lookup, hit, dvp, "..",
*vpp);
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 = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
blp = HASH2BUCKETLOCK(hash);
rw_rlock(blp);
LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
counter_u64_add(numchecks, 1);
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_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
NULL);
if ((cnp->cn_flags & MAKEENTRY) == 0) {
counter_u64_add(nummisszap, 1);
} else {
counter_u64_add(nummiss, 1);
}
goto unlock;
}
/* We don't want to have an entry, so dump it */
if ((cnp->cn_flags & MAKEENTRY) == 0) {
counter_u64_add(numposzaps, 1);
goto zap_and_exit;
}
/* We found a "positive" match, return the vnode */
if (ncp->nc_vp) {
counter_u64_add(numposhits, 1);
*vpp = ncp->nc_vp;
CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
dvp, cnp->cn_nameptr, *vpp, ncp);
SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp),
*vpp);
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) {
counter_u64_add(numnegzaps, 1);
goto zap_and_exit;
}
counter_u64_add(numneghits, 1);
cache_negative_hit(ncp);
if (ncp->nc_flag & NCF_WHITE)
cnp->cn_flags |= ISWHITEOUT;
SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp,
nc_get_name(ncp));
cache_out_ts(ncp, tsp, ticksp);
cache_lookup_unlock(blp, dvlp);
return (ENOENT);
success:
/*
* On success we return a locked and ref'd vnode as per the lookup
* protocol.
*/
MPASS(dvp != *vpp);
ltype = 0; /* silence gcc warning */
if (cnp->cn_flags & ISDOTDOT) {
ltype = VOP_ISLOCKED(dvp);
VOP_UNLOCK(dvp, 0);
}
vhold(*vpp);
cache_lookup_unlock(blp, dvlp);
error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, 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:
cache_lookup_unlock(blp, dvlp);
return (0);
zap_and_exit:
if (blp != NULL)
error = cache_zap_rlocked_bucket(ncp, blp);
else
error = cache_zap_locked_vnode(ncp, dvp);
if (error != 0) {
zap_and_exit_bucket_fail++;
cache_maybe_yield();
goto retry;
}
cache_free(ncp);
return (0);
}
struct celockstate {
struct mtx *vlp[3];
struct rwlock *blp[2];
};
CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3));
CTASSERT((nitems(((struct celockstate *)0)->blp) == 2));
static inline void
cache_celockstate_init(struct celockstate *cel)
{
bzero(cel, sizeof(*cel));
}
static void
cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp,
struct vnode *dvp)
{
struct mtx *vlp1, *vlp2;
MPASS(cel->vlp[0] == NULL);
MPASS(cel->vlp[1] == NULL);
MPASS(cel->vlp[2] == NULL);
MPASS(vp != NULL || dvp != NULL);
vlp1 = VP2VNODELOCK(vp);
vlp2 = VP2VNODELOCK(dvp);
cache_sort(&vlp1, &vlp2);
if (vlp1 != NULL) {
mtx_lock(vlp1);
cel->vlp[0] = vlp1;
}
mtx_lock(vlp2);
cel->vlp[1] = vlp2;
}
static void
cache_unlock_vnodes_cel(struct celockstate *cel)
{
MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL);
if (cel->vlp[0] != NULL)
mtx_unlock(cel->vlp[0]);
if (cel->vlp[1] != NULL)
mtx_unlock(cel->vlp[1]);
if (cel->vlp[2] != NULL)
mtx_unlock(cel->vlp[2]);
}
static bool
cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp)
{
struct mtx *vlp;
bool ret;
cache_assert_vlp_locked(cel->vlp[0]);
cache_assert_vlp_locked(cel->vlp[1]);
MPASS(cel->vlp[2] == NULL);
vlp = VP2VNODELOCK(vp);
if (vlp == NULL)
return (true);
ret = true;
if (vlp >= cel->vlp[1]) {
mtx_lock(vlp);
} else {
if (mtx_trylock(vlp))
goto out;
cache_lock_vnodes_cel_3_failures++;
cache_unlock_vnodes_cel(cel);
if (vlp < cel->vlp[0]) {
mtx_lock(vlp);
mtx_lock(cel->vlp[0]);
mtx_lock(cel->vlp[1]);
} else {
if (cel->vlp[0] != NULL)
mtx_lock(cel->vlp[0]);
mtx_lock(vlp);
mtx_lock(cel->vlp[1]);
}
ret = false;
}
out:
cel->vlp[2] = vlp;
return (ret);
}
static void
cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1,
struct rwlock *blp2)
{
MPASS(cel->blp[0] == NULL);
MPASS(cel->blp[1] == NULL);
cache_sort(&blp1, &blp2);
if (blp1 != NULL) {
rw_wlock(blp1);
cel->blp[0] = blp1;
}
rw_wlock(blp2);
cel->blp[1] = blp2;
}
static void
cache_unlock_buckets_cel(struct celockstate *cel)
{
if (cel->blp[0] != NULL)
rw_wunlock(cel->blp[0]);
rw_wunlock(cel->blp[1]);
}
/*
* Lock part of the cache affected by the insertion.
*
* This means vnodelocks for dvp, vp and the relevant bucketlock.
* However, insertion can result in removal of an old entry. In this
* case we have an additional vnode and bucketlock pair to lock. If the
* entry is negative, ncelock is locked instead of the vnode.
*
* That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while
* preserving the locking order (smaller address first).
*/
static void
cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
uint32_t hash)
{
struct namecache *ncp;
struct rwlock *blps[2];
blps[0] = HASH2BUCKETLOCK(hash);
for (;;) {
blps[1] = NULL;
cache_lock_vnodes_cel(cel, dvp, vp);
if (vp == NULL || vp->v_type != VDIR)
break;
ncp = vp->v_cache_dd;
if (ncp == NULL)
break;
if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
break;
MPASS(ncp->nc_dvp == vp);
blps[1] = NCP2BUCKETLOCK(ncp);
if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
break;
/*
* All vnodes got re-locked. Re-validate the state and if
* nothing changed we are done. Otherwise restart.
*/
if (ncp == vp->v_cache_dd &&
(ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
blps[1] == NCP2BUCKETLOCK(ncp) &&
VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
break;
cache_unlock_vnodes_cel(cel);
cel->vlp[0] = NULL;
cel->vlp[1] = NULL;
cel->vlp[2] = NULL;
}
cache_lock_buckets_cel(cel, blps[0], blps[1]);
}
static void
cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
uint32_t hash)
{
struct namecache *ncp;
struct rwlock *blps[2];
blps[0] = HASH2BUCKETLOCK(hash);
for (;;) {
blps[1] = NULL;
cache_lock_vnodes_cel(cel, dvp, vp);
ncp = dvp->v_cache_dd;
if (ncp == NULL)
break;
if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
break;
MPASS(ncp->nc_dvp == dvp);
blps[1] = NCP2BUCKETLOCK(ncp);
if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
break;
if (ncp == dvp->v_cache_dd &&
(ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
blps[1] == NCP2BUCKETLOCK(ncp) &&
VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
break;
cache_unlock_vnodes_cel(cel);
cel->vlp[0] = NULL;
cel->vlp[1] = NULL;
cel->vlp[2] = NULL;
}
cache_lock_buckets_cel(cel, blps[0], blps[1]);
}
static void
cache_enter_unlock(struct celockstate *cel)
{
cache_unlock_buckets_cel(cel);
cache_unlock_vnodes_cel(cel);
}
/*
* Add an entry to the cache.
*/
void
cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
struct timespec *tsp, struct timespec *dtsp)
{
struct celockstate cel;
struct namecache *ncp, *n2, *ndd;
struct namecache_ts *n3;
struct nchashhead *ncpp;
uint32_t hash;
int flag;
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;
cache_celockstate_init(&cel);
ndd = NULL;
flag = 0;
if (cnp->cn_nameptr[0] == '.') {
if (cnp->cn_namelen == 1)
return;
if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
len = cnp->cn_namelen;
hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
cache_enter_lock_dd(&cel, dvp, vp, hash);
/*
* 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 {
cache_negative_remove(ncp, false);
}
if (vp != NULL) {
TAILQ_INSERT_HEAD(&vp->v_cache_dst,
ncp, nc_dst);
} else {
cache_negative_insert(ncp);
}
ncp->nc_vp = vp;
cache_enter_unlock(&cel);
return;
}
dvp->v_cache_dd = NULL;
cache_enter_unlock(&cel);
cache_celockstate_init(&cel);
SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp);
flag = NCF_ISDOTDOT;
}
}
/*
* 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 = cache_get_hash(cnp->cn_nameptr, len, dvp);
strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1);
cache_enter_lock(&cel, dvp, vp, hash);
/*
* 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;
}
}
goto out_unlock_free;
}
}
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)
goto out_unlock_free;
KASSERT(vp == NULL || vp->v_type == VDIR,
("wrong vnode type %p", vp));
dvp->v_cache_dd = ncp;
}
atomic_add_rel_long(&numcache, 1);
if (vp != NULL) {
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 ((ndd = vp->v_cache_dd) != NULL) {
if ((ndd->nc_flag & NCF_ISDOTDOT) != 0)
cache_zap_locked(ndd, false);
else
ndd = NULL;
}
vp->v_cache_dd = ncp;
}
} else {
vp->v_cache_dd = NULL;
}
}
if (flag != NCF_ISDOTDOT) {
if (LIST_EMPTY(&dvp->v_cache_src)) {
vhold(dvp);
atomic_add_rel_long(&numcachehv, 1);
}
LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
}
/*
* Insert the new namecache entry into the appropriate chain
* within the cache entries table.
*/
LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
/*
* 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 != NULL) {
TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp),
vp);
} else {
if (cnp->cn_flags & ISWHITEOUT)
ncp->nc_flag |= NCF_WHITE;
cache_negative_insert(ncp);
SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
nc_get_name(ncp));
}
cache_enter_unlock(&cel);
if (numneg * ncnegfactor > numcache)
cache_negative_zap_one();
cache_free(ndd);
return;
out_unlock_free:
cache_enter_unlock(&cel);
cache_free(ncp);
return;
}
static u_int
cache_roundup_2(u_int val)
{
u_int res;
for (res = 1; res <= val; res <<= 1)
continue;
return (res);
}
/*
* Name cache initialization, from vfs_init() when we are booting
*/
static void
nchinit(void *dummy __unused)
{
u_int i;
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);
numbucketlocks = cache_roundup_2(mp_ncpus * 64);
bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numbucketlocks; i++)
rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE);
numvnodelocks = cache_roundup_2(mp_ncpus * 64);
vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numvnodelocks; i++)
mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE);
numcalls = counter_u64_alloc(M_WAITOK);
dothits = counter_u64_alloc(M_WAITOK);
dotdothits = counter_u64_alloc(M_WAITOK);
numchecks = counter_u64_alloc(M_WAITOK);
nummiss = counter_u64_alloc(M_WAITOK);
nummisszap = counter_u64_alloc(M_WAITOK);
numposzaps = counter_u64_alloc(M_WAITOK);
numposhits = counter_u64_alloc(M_WAITOK);
numnegzaps = counter_u64_alloc(M_WAITOK);
numneghits = counter_u64_alloc(M_WAITOK);
numfullpathcalls = counter_u64_alloc(M_WAITOK);
numfullpathfail1 = counter_u64_alloc(M_WAITOK);
numfullpathfail2 = counter_u64_alloc(M_WAITOK);
numfullpathfail4 = counter_u64_alloc(M_WAITOK);
numfullpathfound = counter_u64_alloc(M_WAITOK);
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
void
cache_changesize(int newmaxvnodes)
{
struct nchashhead *new_nchashtbl, *old_nchashtbl;
u_long new_nchash, old_nchash;
struct namecache *ncp;
uint32_t hash;
int i;
new_nchashtbl = hashinit(newmaxvnodes * 2, M_VFSCACHE, &new_nchash);
/* If same hash table size, nothing to do */
if (nchash == new_nchash) {
free(new_nchashtbl, M_VFSCACHE);
return;
}
/*
* Move everything from the old hash table to the new table.
* None of the namecache entries in the table can be removed
* because to do so, they have to be removed from the hash table.
*/
cache_lock_all_vnodes();
cache_lock_all_buckets();
old_nchashtbl = nchashtbl;
old_nchash = nchash;
nchashtbl = new_nchashtbl;
nchash = new_nchash;
for (i = 0; i <= old_nchash; i++) {
while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) {
hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen,
ncp->nc_dvp);
LIST_REMOVE(ncp, nc_hash);
LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash);
}
}
cache_unlock_all_buckets();
cache_unlock_all_vnodes();
free(old_nchashtbl, M_VFSCACHE);
}
/*
* Invalidate all entries to a particular vnode.
*/
void
cache_purge(struct vnode *vp)
{
TAILQ_HEAD(, namecache) ncps;
struct namecache *ncp, *nnp;
struct mtx *vlp, *vlp2;
CTR1(KTR_VFS, "cache_purge(%p)", vp);
SDT_PROBE1(vfs, namecache, purge, done, vp);
if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) &&
vp->v_cache_dd == NULL)
return;
TAILQ_INIT(&ncps);
vlp = VP2VNODELOCK(vp);
vlp2 = NULL;
mtx_lock(vlp);
retry:
while (!LIST_EMPTY(&vp->v_cache_src)) {
ncp = LIST_FIRST(&vp->v_cache_src);
if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
goto retry;
TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
}
while (!TAILQ_EMPTY(&vp->v_cache_dst)) {
ncp = TAILQ_FIRST(&vp->v_cache_dst);
if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
goto retry;
TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
}
ncp = vp->v_cache_dd;
if (ncp != NULL) {
KASSERT(ncp->nc_flag & NCF_ISDOTDOT,
("lost dotdot link"));
if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
goto retry;
TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
}
KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
mtx_unlock(vlp);
if (vlp2 != NULL)
mtx_unlock(vlp2);
TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
cache_free(ncp);
}
}
/*
* Invalidate all negative entries for a particular directory vnode.
*/
void
cache_purge_negative(struct vnode *vp)
{
TAILQ_HEAD(, namecache) ncps;
struct namecache *ncp, *nnp;
struct mtx *vlp;
CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
SDT_PROBE1(vfs, namecache, purge_negative, done, vp);
TAILQ_INIT(&ncps);
vlp = VP2VNODELOCK(vp);
mtx_lock(vlp);
LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) {
if (ncp->nc_vp != NULL)
continue;
cache_zap_negative_locked_vnode_kl(ncp, vp);
TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
}
mtx_unlock(vlp);
TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
cache_free(ncp);
}
}
/*
* Flush all entries referencing a particular filesystem.
*/
void
cache_purgevfs(struct mount *mp)
{
TAILQ_HEAD(, namecache) ncps;
struct mtx *vlp1, *vlp2;
struct rwlock *blp;
struct nchashhead *bucket;
struct namecache *ncp, *nnp;
u_long i, j, n_nchash;
int error;
/* Scan hash tables for applicable entries */
SDT_PROBE1(vfs, namecache, purgevfs, done, mp);
TAILQ_INIT(&ncps);
n_nchash = nchash + 1;
vlp1 = vlp2 = NULL;
for (i = 0; i < numbucketlocks; i++) {
blp = (struct rwlock *)&bucketlocks[i];
rw_wlock(blp);
for (j = i; j < n_nchash; j += numbucketlocks) {
retry:
bucket = &nchashtbl[j];
LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) {
cache_assert_bucket_locked(ncp, RA_WLOCKED);
if (ncp->nc_dvp->v_mount != mp)
continue;
error = cache_zap_wlocked_bucket_kl(ncp, blp,
&vlp1, &vlp2);
if (error != 0)
goto retry;
TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst);
}
}
rw_wunlock(blp);
if (vlp1 == NULL && vlp2 == NULL)
cache_maybe_yield();
}
if (vlp1 != NULL)
mtx_unlock(vlp1);
if (vlp2 != NULL)
mtx_unlock(vlp2);
TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
cache_free(ncp);
}
}
/*
* Perform canonical checks and cache lookup and pass on to filesystem
* through the vop_cachedlookup only if needed.
*/
int
vfs_cache_lookup(struct vop_lookup_args *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);
}
/*
* 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(struct thread *td, struct __getcwd_args *uap)
{
return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen,
MAXPATHLEN));
}
int
kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen,
u_int path_max)
{
char *bp, *tmpbuf;
struct filedesc *fdp;
struct vnode *cdir, *rdir;
int error;
if (disablecwd)
return (ENODEV);
if (buflen < 2)
return (EINVAL);
if (buflen > path_max)
buflen = path_max;
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.
*/
static int disablefullpath;
SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
"Disable the vn_fullpath function");
/*
* 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)
{
struct vnode *dvp;
struct namecache *ncp;
struct mtx *vlp;
int error;
vlp = VP2VNODELOCK(*vp);
mtx_lock(vlp);
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) {
mtx_unlock(vlp);
vrele(*vp);
counter_u64_add(numfullpathfail4, 1);
error = ENOMEM;
SDT_PROBE3(vfs, namecache, fullpath, return, error,
vp, NULL);
return (error);
}
*buflen -= ncp->nc_nlen;
memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen);
SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp,
nc_get_name(ncp), vp);
dvp = *vp;
*vp = ncp->nc_dvp;
vref(*vp);
mtx_unlock(vlp);
vrele(dvp);
return (0);
}
SDT_PROBE1(vfs, namecache, fullpath, miss, vp);
mtx_unlock(vlp);
vn_lock(*vp, LK_SHARED | LK_RETRY);
error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
vput(*vp);
if (error) {
counter_u64_add(numfullpathfail2, 1);
SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
return (error);
}
*vp = dvp;
if (dvp->v_iflag & VI_DOOMED) {
/* forced unmount */
vrele(dvp);
error = ENOENT;
SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
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_PROBE1(vfs, namecache, fullpath, entry, vp);
counter_u64_add(numfullpathcalls, 1);
vref(vp);
if (vp->v_type != VDIR) {
error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
if (error)
return (error);
if (buflen == 0) {
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 */
vrele(vp);
error = ENOENT;
SDT_PROBE3(vfs, namecache, fullpath, return,
error, vp, NULL);
break;
}
vp1 = vp->v_mount->mnt_vnodecovered;
vref(vp1);
vrele(vp);
vp = vp1;
continue;
}
if (vp->v_type != VDIR) {
vrele(vp);
counter_u64_add(numfullpathfail1, 1);
error = ENOTDIR;
SDT_PROBE3(vfs, namecache, fullpath, return,
error, vp, NULL);
break;
}
error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
if (error)
break;
if (buflen == 0) {
vrele(vp);
error = ENOMEM;
SDT_PROBE3(vfs, namecache, fullpath, return, error,
startvp, NULL);
break;
}
buf[--buflen] = '/';
slash_prefixed = 1;
}
if (error)
return (error);
if (!slash_prefixed) {
if (buflen == 0) {
vrele(vp);
counter_u64_add(numfullpathfail4, 1);
SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM,
startvp, NULL);
return (ENOMEM);
}
buf[--buflen] = '/';
}
counter_u64_add(numfullpathfound, 1);
vrele(vp);
SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen);
*retbuf = buf + buflen;
return (0);
}
struct vnode *
vn_dir_dd_ino(struct vnode *vp)
{
struct namecache *ncp;
struct vnode *ddvp;
struct mtx *vlp;
ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
vlp = VP2VNODELOCK(vp);
mtx_lock(vlp);
TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
continue;
ddvp = ncp->nc_dvp;
vhold(ddvp);
mtx_unlock(vlp);
if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread))
return (NULL);
return (ddvp);
}
mtx_unlock(vlp);
return (NULL);
}
int
vn_commname(struct vnode *vp, char *buf, u_int buflen)
{
struct namecache *ncp;
struct mtx *vlp;
int l;
vlp = VP2VNODELOCK(vp);
mtx_lock(vlp);
TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
break;
if (ncp == NULL) {
mtx_unlock(vlp);
return (ENOENT);
}
l = min(ncp->nc_nlen, buflen - 1);
memcpy(buf, nc_get_name(ncp), l);
mtx_unlock(vlp);
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.
* 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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