baf33bb569
Reviewed by: rwatson Pointy hat to: me
1221 lines
31 KiB
C
1221 lines
31 KiB
C
/*-
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* Copyright (c) 1989, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Poul-Henning Kamp of the FreeBSD Project.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kdtrace.h"
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/filedesc.h>
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#include <sys/fnv_hash.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/namei.h>
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#include <sys/proc.h>
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#include <sys/rwlock.h>
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#include <sys/sdt.h>
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#include <sys/syscallsubr.h>
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#include <sys/sysctl.h>
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#include <sys/sysproto.h>
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#include <sys/systm.h>
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#include <sys/vnode.h>
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#ifdef KTRACE
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#include <sys/ktrace.h>
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#endif
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#include <vm/uma.h>
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SDT_PROVIDER_DECLARE(vfs);
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SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *",
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"struct vnode *");
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SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
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"char *");
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SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
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SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
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"struct char *", "struct vnode *");
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SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
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SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", "struct vnode *",
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"struct char *");
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SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
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"struct vnode *");
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SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit_negative, "struct vnode *",
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"char *");
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SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
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"char *");
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SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *");
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SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
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SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
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SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
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"struct vnode *");
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SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *",
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"char *");
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/*
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* This structure describes the elements in the cache of recent
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* names looked up by namei.
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*/
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struct namecache {
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LIST_ENTRY(namecache) nc_hash; /* hash chain */
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LIST_ENTRY(namecache) nc_src; /* source vnode list */
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TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
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struct vnode *nc_dvp; /* vnode of parent of name */
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struct vnode *nc_vp; /* vnode the name refers to */
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u_char nc_flag; /* flag bits */
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u_char nc_nlen; /* length of name */
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char nc_name[0]; /* segment name + nul */
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};
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/*
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* Name caching works as follows:
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*
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* Names found by directory scans are retained in a cache
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* for future reference. It is managed LRU, so frequently
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* used names will hang around. Cache is indexed by hash value
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* obtained from (vp, name) where vp refers to the directory
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* containing name.
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*
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* If it is a "negative" entry, (i.e. for a name that is known NOT to
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* exist) the vnode pointer will be NULL.
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*
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* Upon reaching the last segment of a path, if the reference
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* is for DELETE, or NOCACHE is set (rewrite), and the
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* name is located in the cache, it will be dropped.
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*/
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/*
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* Structures associated with name cacheing.
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*/
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#define NCHHASH(hash) \
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(&nchashtbl[(hash) & nchash])
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static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
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static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */
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static u_long nchash; /* size of hash table */
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SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "");
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static u_long ncnegfactor = 16; /* ratio of negative entries */
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SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "");
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static u_long numneg; /* number of cache entries allocated */
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SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "");
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static u_long numcache; /* number of cache entries allocated */
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SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "");
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static u_long numcachehv; /* number of cache entries with vnodes held */
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SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, "");
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#if 0
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static u_long numcachepl; /* number of cache purge for leaf entries */
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SYSCTL_ULONG(_debug, OID_AUTO, numcachepl, CTLFLAG_RD, &numcachepl, 0, "");
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#endif
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struct nchstats nchstats; /* cache effectiveness statistics */
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static struct rwlock cache_lock;
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RW_SYSINIT(vfscache, &cache_lock, "Name Cache");
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#define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock)
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#define CACHE_RLOCK() rw_rlock(&cache_lock)
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#define CACHE_RUNLOCK() rw_runlock(&cache_lock)
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#define CACHE_WLOCK() rw_wlock(&cache_lock)
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#define CACHE_WUNLOCK() rw_wunlock(&cache_lock)
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/*
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* UMA zones for the VFS cache.
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*
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* The small cache is used for entries with short names, which are the
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* most common. The large cache is used for entries which are too big to
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* fit in the small cache.
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*/
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static uma_zone_t cache_zone_small;
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static uma_zone_t cache_zone_large;
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#define CACHE_PATH_CUTOFF 35
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#define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF \
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+ 1)
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#define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX + 1)
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#define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \
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cache_zone_small : cache_zone_large, M_WAITOK)
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#define cache_free(ncp) do { \
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if (ncp != NULL) \
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uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \
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cache_zone_small : cache_zone_large, (ncp)); \
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} while (0)
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static int doingcache = 1; /* 1 => enable the cache */
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SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, "");
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/* Export size information to userland */
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SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0,
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sizeof(struct namecache), "");
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/*
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* The new name cache statistics
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*/
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static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics");
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#define STATNODE(mode, name, var) \
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SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, "");
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STATNODE(CTLFLAG_RD, numneg, &numneg);
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STATNODE(CTLFLAG_RD, numcache, &numcache);
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static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls);
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static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits);
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static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits);
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static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks);
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static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss);
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static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap);
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static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps);
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static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits);
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static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps);
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static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits);
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static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades);
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SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE,
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&nchstats, sizeof(nchstats), "LU", "VFS cache effectiveness statistics");
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static void cache_zap(struct namecache *ncp);
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static int vn_vptocnp_locked(struct vnode **vp, char *buf, u_int *buflen);
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static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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char *buf, char **retbuf, u_int buflen);
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static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
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/*
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* Flags in namecache.nc_flag
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*/
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#define NCF_WHITE 0x01
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#define NCF_ISDOTDOT 0x02
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#ifdef DIAGNOSTIC
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/*
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* Grab an atomic snapshot of the name cache hash chain lengths
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*/
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SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats");
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static int
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sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
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{
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int error;
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struct nchashhead *ncpp;
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struct namecache *ncp;
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int n_nchash;
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int count;
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n_nchash = nchash + 1; /* nchash is max index, not count */
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if (!req->oldptr)
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return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
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/* Scan hash tables for applicable entries */
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for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
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CACHE_RLOCK();
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count = 0;
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LIST_FOREACH(ncp, ncpp, nc_hash) {
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count++;
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}
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CACHE_RUNLOCK();
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error = SYSCTL_OUT(req, &count, sizeof(count));
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if (error)
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return (error);
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}
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return (0);
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}
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SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD|
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CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int",
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"nchash chain lengths");
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static int
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sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)
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{
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int error;
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struct nchashhead *ncpp;
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struct namecache *ncp;
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int n_nchash;
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int count, maxlength, used, pct;
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if (!req->oldptr)
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return SYSCTL_OUT(req, 0, 4 * sizeof(int));
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n_nchash = nchash + 1; /* nchash is max index, not count */
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used = 0;
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maxlength = 0;
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/* Scan hash tables for applicable entries */
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for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
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count = 0;
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CACHE_RLOCK();
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LIST_FOREACH(ncp, ncpp, nc_hash) {
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count++;
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}
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CACHE_RUNLOCK();
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if (count)
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used++;
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if (maxlength < count)
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maxlength = count;
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}
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n_nchash = nchash + 1;
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pct = (used * 100 * 100) / n_nchash;
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error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
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if (error)
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return (error);
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error = SYSCTL_OUT(req, &used, sizeof(used));
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if (error)
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return (error);
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error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength));
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if (error)
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return (error);
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error = SYSCTL_OUT(req, &pct, sizeof(pct));
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if (error)
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return (error);
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return (0);
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}
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SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD|
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CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I",
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"nchash chain lengths");
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#endif
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/*
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* cache_zap():
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*
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* Removes a namecache entry from cache, whether it contains an actual
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* pointer to a vnode or if it is just a negative cache entry.
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*/
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static void
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cache_zap(ncp)
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struct namecache *ncp;
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{
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struct vnode *vp;
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rw_assert(&cache_lock, RA_WLOCKED);
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CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp);
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#ifdef KDTRACE_HOOKS
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if (ncp->nc_vp != NULL) {
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SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp,
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ncp->nc_name, ncp->nc_vp, 0, 0);
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} else {
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SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp,
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ncp->nc_name, 0, 0, 0);
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}
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#endif
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vp = NULL;
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LIST_REMOVE(ncp, nc_hash);
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if (ncp->nc_flag & NCF_ISDOTDOT) {
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if (ncp == ncp->nc_dvp->v_cache_dd)
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ncp->nc_dvp->v_cache_dd = NULL;
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} else {
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LIST_REMOVE(ncp, nc_src);
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if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) {
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vp = ncp->nc_dvp;
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numcachehv--;
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}
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}
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if (ncp->nc_vp) {
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TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst);
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if (ncp == ncp->nc_vp->v_cache_dd)
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ncp->nc_vp->v_cache_dd = NULL;
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} else {
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TAILQ_REMOVE(&ncneg, ncp, nc_dst);
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numneg--;
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}
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numcache--;
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cache_free(ncp);
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if (vp)
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vdrop(vp);
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}
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/*
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* Lookup an entry in the cache
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*
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* Lookup is called with dvp pointing to the directory to search,
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* cnp pointing to the name of the entry being sought. If the lookup
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* succeeds, the vnode is returned in *vpp, and a status of -1 is
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* returned. If the lookup determines that the name does not exist
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* (negative cacheing), a status of ENOENT is returned. If the lookup
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* fails, a status of zero is returned. If the directory vnode is
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* recycled out from under us due to a forced unmount, a status of
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* ENOENT is returned.
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*
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* vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
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* unlocked. If we're looking up . an extra ref is taken, but the lock is
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* not recursively acquired.
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*/
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int
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cache_lookup(dvp, vpp, cnp)
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struct vnode *dvp;
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struct vnode **vpp;
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struct componentname *cnp;
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{
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struct namecache *ncp;
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u_int32_t hash;
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int error, ltype, wlocked;
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if (!doingcache) {
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cnp->cn_flags &= ~MAKEENTRY;
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return (0);
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}
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retry:
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CACHE_RLOCK();
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wlocked = 0;
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numcalls++;
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error = 0;
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retry_wlocked:
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if (cnp->cn_nameptr[0] == '.') {
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if (cnp->cn_namelen == 1) {
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*vpp = dvp;
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CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
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dvp, cnp->cn_nameptr);
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dothits++;
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SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".",
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*vpp, 0, 0);
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goto success;
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}
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if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
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dotdothits++;
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if (dvp->v_cache_dd == NULL) {
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SDT_PROBE(vfs, namecache, lookup, miss, dvp,
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"..", NULL, 0, 0);
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goto unlock;
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}
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if ((cnp->cn_flags & MAKEENTRY) == 0) {
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if (!wlocked && !CACHE_UPGRADE_LOCK())
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goto wlock;
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if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT)
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cache_zap(dvp->v_cache_dd);
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dvp->v_cache_dd = NULL;
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goto unlock;
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}
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if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT)
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*vpp = dvp->v_cache_dd->nc_vp;
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else
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*vpp = dvp->v_cache_dd->nc_dvp;
|
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/* Return failure if negative entry was found. */
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if (*vpp == NULL) {
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ncp = dvp->v_cache_dd;
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goto negative_success;
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}
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CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
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dvp, cnp->cn_nameptr, *vpp);
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SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..",
|
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*vpp, 0, 0);
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goto success;
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}
|
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}
|
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|
|
hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT);
|
|
hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
|
|
LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
|
|
numchecks++;
|
|
if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
|
|
!bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
|
|
break;
|
|
}
|
|
|
|
/* We failed to find an entry */
|
|
if (ncp == 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, ncp->nc_name,
|
|
*vpp, 0, 0);
|
|
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, ncp->nc_name,
|
|
0, 0, 0);
|
|
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(dvp, vp, cnp)
|
|
struct vnode *dvp;
|
|
struct vnode *vp;
|
|
struct componentname *cnp;
|
|
{
|
|
struct namecache *ncp, *n2;
|
|
struct nchashhead *ncpp;
|
|
u_int32_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,
|
|
("cahe_enter: Adding a doomed vnode"));
|
|
|
|
if (!doingcache)
|
|
return;
|
|
|
|
/*
|
|
* Avoid blowout in namecache entries.
|
|
*/
|
|
if (numcache >= desiredvnodes * 2)
|
|
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);
|
|
ncp->nc_vp = vp;
|
|
ncp->nc_dvp = dvp;
|
|
ncp->nc_flag = flag;
|
|
len = ncp->nc_nlen = cnp->cn_namelen;
|
|
hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
|
|
strlcpy(ncp->nc_name, 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(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) {
|
|
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) {
|
|
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, ncp->nc_name, vp,
|
|
0, 0);
|
|
} else {
|
|
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
|
|
SDT_PROBE(vfs, namecache, enter_negative, done, dvp,
|
|
ncp->nc_name, 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", CACHE_ZONE_SMALL, NULL,
|
|
NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
|
|
cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL,
|
|
NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
|
|
|
|
nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
|
|
}
|
|
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
|
|
|
|
|
|
/*
|
|
* Invalidate all entries to a particular vnode.
|
|
*/
|
|
void
|
|
cache_purge(vp)
|
|
struct vnode *vp;
|
|
{
|
|
|
|
CTR1(KTR_VFS, "cache_purge(%p)", vp);
|
|
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);
|
|
if (error == 0)
|
|
return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
|
|
if (error == -1)
|
|
return (0);
|
|
return (error);
|
|
}
|
|
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct __getcwd_args {
|
|
u_char *buf;
|
|
u_int buflen;
|
|
};
|
|
#endif
|
|
|
|
/*
|
|
* XXX All of these sysctls would probably be more productive dead.
|
|
*/
|
|
static int disablecwd;
|
|
SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
|
|
"Disable the getcwd syscall");
|
|
|
|
/* Implementation of the getcwd syscall. */
|
|
int
|
|
__getcwd(td, uap)
|
|
struct thread *td;
|
|
struct __getcwd_args *uap;
|
|
{
|
|
|
|
return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen));
|
|
}
|
|
|
|
int
|
|
kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen)
|
|
{
|
|
char *bp, *tmpbuf;
|
|
struct filedesc *fdp;
|
|
struct vnode *cdir, *rdir;
|
|
int error, vfslocked;
|
|
|
|
if (disablecwd)
|
|
return (ENODEV);
|
|
if (buflen < 2)
|
|
return (EINVAL);
|
|
if (buflen > MAXPATHLEN)
|
|
buflen = MAXPATHLEN;
|
|
|
|
tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
|
|
fdp = td->td_proc->p_fd;
|
|
FILEDESC_SLOCK(fdp);
|
|
cdir = fdp->fd_cdir;
|
|
VREF(cdir);
|
|
rdir = fdp->fd_rdir;
|
|
VREF(rdir);
|
|
FILEDESC_SUNLOCK(fdp);
|
|
error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen);
|
|
vfslocked = VFS_LOCK_GIANT(rdir->v_mount);
|
|
vrele(rdir);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
vfslocked = VFS_LOCK_GIANT(cdir->v_mount);
|
|
vrele(cdir);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
|
|
if (!error) {
|
|
if (bufseg == UIO_SYSSPACE)
|
|
bcopy(bp, buf, strlen(bp) + 1);
|
|
else
|
|
error = copyout(bp, buf, strlen(bp) + 1);
|
|
#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) \
|
|
static u_int name; \
|
|
SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
|
|
|
|
static int disablefullpath;
|
|
SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
|
|
"Disable the vn_fullpath function");
|
|
|
|
/* These count for kern___getcwd(), too. */
|
|
STATNODE(numfullpathcalls);
|
|
STATNODE(numfullpathfail1);
|
|
STATNODE(numfullpathfail2);
|
|
STATNODE(numfullpathfail4);
|
|
STATNODE(numfullpathfound);
|
|
|
|
/*
|
|
* Retrieve the full filesystem path that correspond to a vnode from the name
|
|
* cache (if available)
|
|
*/
|
|
int
|
|
vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
|
|
{
|
|
char *buf;
|
|
struct filedesc *fdp;
|
|
struct vnode *rdir;
|
|
int error, vfslocked;
|
|
|
|
if (disablefullpath)
|
|
return (ENODEV);
|
|
if (vn == NULL)
|
|
return (EINVAL);
|
|
|
|
buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
|
|
fdp = td->td_proc->p_fd;
|
|
FILEDESC_SLOCK(fdp);
|
|
rdir = fdp->fd_rdir;
|
|
VREF(rdir);
|
|
FILEDESC_SUNLOCK(fdp);
|
|
error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN);
|
|
vfslocked = VFS_LOCK_GIANT(rdir->v_mount);
|
|
vrele(rdir);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
|
|
if (!error)
|
|
*freebuf = buf;
|
|
else
|
|
free(buf, M_TEMP);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* This function is similar to vn_fullpath, but it attempts to lookup the
|
|
* pathname relative to the global root mount point. This is required for the
|
|
* auditing sub-system, as audited pathnames must be absolute, relative to the
|
|
* global root mount point.
|
|
*/
|
|
int
|
|
vn_fullpath_global(struct thread *td, struct vnode *vn,
|
|
char **retbuf, char **freebuf)
|
|
{
|
|
char *buf;
|
|
int error;
|
|
|
|
if (disablefullpath)
|
|
return (ENODEV);
|
|
if (vn == NULL)
|
|
return (EINVAL);
|
|
buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
|
|
error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN);
|
|
if (!error)
|
|
*freebuf = buf;
|
|
else
|
|
free(buf, M_TEMP);
|
|
return (error);
|
|
}
|
|
|
|
int
|
|
vn_vptocnp(struct vnode **vp, char *buf, u_int *buflen)
|
|
{
|
|
int error;
|
|
|
|
CACHE_RLOCK();
|
|
error = vn_vptocnp_locked(vp, buf, buflen);
|
|
if (error == 0) {
|
|
/*
|
|
* vn_vptocnp_locked() dropped hold acquired by
|
|
* VOP_VPTOCNP immediately after locking the
|
|
* cache. Since we are going to drop the cache rlock,
|
|
* re-hold the result.
|
|
*/
|
|
vhold(*vp);
|
|
CACHE_RUNLOCK();
|
|
}
|
|
return (error);
|
|
}
|
|
|
|
static int
|
|
vn_vptocnp_locked(struct vnode **vp, char *buf, u_int *buflen)
|
|
{
|
|
struct vnode *dvp;
|
|
struct namecache *ncp;
|
|
int error, vfslocked;
|
|
|
|
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();
|
|
numfullpathfail4++;
|
|
error = ENOMEM;
|
|
SDT_PROBE(vfs, namecache, fullpath, return, error,
|
|
vp, NULL, 0, 0);
|
|
return (error);
|
|
}
|
|
*buflen -= ncp->nc_nlen;
|
|
memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen);
|
|
SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
|
|
ncp->nc_name, vp, 0, 0);
|
|
*vp = ncp->nc_dvp;
|
|
return (0);
|
|
}
|
|
SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0);
|
|
|
|
vhold(*vp);
|
|
CACHE_RUNLOCK();
|
|
vfslocked = VFS_LOCK_GIANT((*vp)->v_mount);
|
|
vn_lock(*vp, LK_SHARED | LK_RETRY);
|
|
error = VOP_VPTOCNP(*vp, &dvp, buf, buflen);
|
|
VOP_UNLOCK(*vp, 0);
|
|
vdrop(*vp);
|
|
VFS_UNLOCK_GIANT(vfslocked);
|
|
if (error) {
|
|
numfullpathfail2++;
|
|
SDT_PROBE(vfs, namecache, fullpath, return, error, vp,
|
|
NULL, 0, 0);
|
|
return (error);
|
|
}
|
|
|
|
*vp = dvp;
|
|
CACHE_RLOCK();
|
|
if ((*vp)->v_iflag & VI_DOOMED) {
|
|
/* forced unmount */
|
|
CACHE_RUNLOCK();
|
|
vdrop(*vp);
|
|
error = ENOENT;
|
|
SDT_PROBE(vfs, namecache, fullpath, return, error, vp,
|
|
NULL, 0, 0);
|
|
return (error);
|
|
}
|
|
vdrop(*vp);
|
|
|
|
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
|
|
|
|
buflen--;
|
|
buf[buflen] = '\0';
|
|
error = 0;
|
|
slash_prefixed = 0;
|
|
|
|
SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0);
|
|
numfullpathcalls++;
|
|
CACHE_RLOCK();
|
|
if (vp->v_type != VDIR) {
|
|
error = vn_vptocnp_locked(&vp, buf, &buflen);
|
|
if (error)
|
|
return (error);
|
|
if (buflen == 0)
|
|
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();
|
|
error = ENOENT;
|
|
SDT_PROBE(vfs, namecache, fullpath, return,
|
|
error, vp, NULL, 0, 0);
|
|
break;
|
|
}
|
|
vp = vp->v_mount->mnt_vnodecovered;
|
|
continue;
|
|
}
|
|
if (vp->v_type != VDIR) {
|
|
CACHE_RUNLOCK();
|
|
numfullpathfail1++;
|
|
error = ENOTDIR;
|
|
SDT_PROBE(vfs, namecache, fullpath, return,
|
|
error, vp, NULL, 0, 0);
|
|
break;
|
|
}
|
|
error = vn_vptocnp_locked(&vp, buf, &buflen);
|
|
if (error)
|
|
break;
|
|
if (buflen == 0) {
|
|
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();
|
|
numfullpathfail4++;
|
|
SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM,
|
|
startvp, NULL, 0, 0);
|
|
return (ENOMEM);
|
|
}
|
|
buf[--buflen] = '/';
|
|
}
|
|
numfullpathfound++;
|
|
CACHE_RUNLOCK();
|
|
|
|
SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen,
|
|
0, 0);
|
|
*retbuf = buf + buflen;
|
|
return (0);
|
|
}
|
|
|
|
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, ncp->nc_name, l);
|
|
CACHE_RUNLOCK();
|
|
buf[l] = '\0';
|
|
return (0);
|
|
}
|