588 lines
16 KiB
C
588 lines
16 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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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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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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/mount.h>
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#include <sys/vnode.h>
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#include <sys/namei.h>
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#include <sys/malloc.h>
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#include <sys/sysproto.h>
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#include <sys/proc.h>
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#include <sys/filedesc.h>
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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 */
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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(dvp, hash) \
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(&nchashtbl[((dvp)->v_id + (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_INT(_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_INT(_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_INT(_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_INT(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "");
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struct nchstats nchstats; /* cache effectiveness statistics */
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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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SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), "");
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SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), "");
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/*
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* The new name cache statistics
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*/
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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_INT(_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 void cache_zap __P((struct namecache *ncp));
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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 1
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/*
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* Delete an entry from its hash list and move it to the front
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* of the LRU list for immediate reuse.
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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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LIST_REMOVE(ncp, nc_hash);
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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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vdrop(ncp->nc_dvp);
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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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} 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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free(ncp, M_VFSCACHE);
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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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* We don't do this if the segment name is long, simply so the cache
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* can avoid holding long names (which would either waste space, or
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* add greatly to the complexity).
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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.
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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_long hash;
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u_char *cp;
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int len;
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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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numcalls++;
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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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dothits++;
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return (-1);
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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_dd->v_id != dvp->v_ddid ||
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(cnp->cn_flags & MAKEENTRY) == 0) {
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dvp->v_ddid = 0;
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return (0);
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}
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*vpp = dvp->v_dd;
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return (-1);
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}
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}
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hash = 0;
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len = cnp->cn_namelen;
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for (cp = cnp->cn_nameptr; len; len--, cp++)
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hash += *cp;
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LIST_FOREACH(ncp, (NCHHASH(dvp, hash)), nc_hash) {
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numchecks++;
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if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
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!bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
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break;
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}
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/* We failed to find an entry */
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if (ncp == 0) {
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if ((cnp->cn_flags & MAKEENTRY) == 0) {
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nummisszap++;
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} else {
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nummiss++;
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}
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nchstats.ncs_miss++;
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return (0);
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}
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/* We don't want to have an entry, so dump it */
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if ((cnp->cn_flags & MAKEENTRY) == 0) {
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numposzaps++;
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nchstats.ncs_badhits++;
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cache_zap(ncp);
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return (0);
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}
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/* We found a "positive" match, return the vnode */
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if (ncp->nc_vp) {
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numposhits++;
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nchstats.ncs_goodhits++;
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*vpp = ncp->nc_vp;
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return (-1);
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}
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/* We found a negative match, and want to create it, so purge */
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if (cnp->cn_nameiop == CREATE) {
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numnegzaps++;
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nchstats.ncs_badhits++;
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cache_zap(ncp);
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return (0);
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}
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numneghits++;
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/*
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* We found a "negative" match, ENOENT notifies client of this match.
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* The nc_vpid field records whether this is a whiteout.
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*/
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TAILQ_REMOVE(&ncneg, ncp, nc_dst);
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TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
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nchstats.ncs_neghits++;
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if (ncp->nc_flag & NCF_WHITE)
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cnp->cn_flags |= ISWHITEOUT;
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return (ENOENT);
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}
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/*
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* Add an entry to the cache.
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*/
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void
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cache_enter(dvp, vp, cnp)
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struct vnode *dvp;
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struct vnode *vp;
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struct componentname *cnp;
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{
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struct namecache *ncp;
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struct nchashhead *ncpp;
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u_long hash;
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u_char *cp, *dp;
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int len;
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if (!doingcache)
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return;
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if (cnp->cn_nameptr[0] == '.') {
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if (cnp->cn_namelen == 1) {
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return;
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}
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if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
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if (vp) {
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dvp->v_dd = vp;
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dvp->v_ddid = vp->v_id;
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} else {
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dvp->v_dd = dvp;
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dvp->v_ddid = 0;
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}
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return;
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}
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}
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ncp = (struct namecache *)
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malloc(sizeof *ncp + cnp->cn_namelen, M_VFSCACHE, M_WAITOK);
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bzero((char *)ncp, sizeof *ncp);
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numcache++;
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if (!vp) {
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numneg++;
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ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0;
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} else if (vp->v_type == VDIR) {
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vp->v_dd = dvp;
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vp->v_ddid = dvp->v_id;
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}
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/*
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* Fill in cache info, if vp is NULL this is a "negative" cache entry.
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* For negative entries, we have to record whether it is a whiteout.
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* the whiteout flag is stored in the nc_vpid field which is
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* otherwise unused.
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*/
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ncp->nc_vp = vp;
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ncp->nc_dvp = dvp;
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len = ncp->nc_nlen = cnp->cn_namelen;
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hash = 0;
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dp = ncp->nc_name;
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for (cp = cnp->cn_nameptr; len; len--, cp++, dp++)
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hash += (*dp = *cp);
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ncpp = NCHHASH(dvp, hash);
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LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
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if (LIST_EMPTY(&dvp->v_cache_src))
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vhold(dvp);
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LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
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if (vp) {
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TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
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} else {
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TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
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}
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if (numneg * ncnegfactor > numcache) {
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ncp = TAILQ_FIRST(&ncneg);
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cache_zap(ncp);
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}
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}
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/*
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* Name cache initialization, from vfs_init() when we are booting
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*/
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void
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nchinit()
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{
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TAILQ_INIT(&ncneg);
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nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash);
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}
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/*
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* Invalidate all entries to a particular vnode.
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*
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* Remove all entries in the namecache relating to this vnode and
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* change the v_id. We take the v_id from a global counter, since
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* it becomes a handy sequence number in crash-dumps that way.
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* No valid vnode will ever have (v_id == 0).
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*
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* XXX: Only time and the size of v_id prevents this from failing:
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* XXX: In theory we should hunt down all (struct vnode*, v_id)
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* XXX: soft references and nuke them, at least on the global
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* XXX: v_id wraparound. The period of resistance can be extended
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* XXX: by incrementing each vnodes v_id individually instead of
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* XXX: using the global v_id.
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*/
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void
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cache_purge(vp)
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struct vnode *vp;
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{
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static u_long nextid;
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while (!LIST_EMPTY(&vp->v_cache_src))
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cache_zap(LIST_FIRST(&vp->v_cache_src));
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while (!TAILQ_EMPTY(&vp->v_cache_dst))
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cache_zap(TAILQ_FIRST(&vp->v_cache_dst));
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do
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nextid++;
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while (nextid == vp->v_id || !nextid);
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vp->v_id = nextid;
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vp->v_dd = vp;
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vp->v_ddid = 0;
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}
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/*
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* Flush all entries referencing a particular filesystem.
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*
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* Since we need to check it anyway, we will flush all the invalid
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* entries at the same time.
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*/
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void
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cache_purgevfs(mp)
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struct mount *mp;
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{
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struct nchashhead *ncpp;
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struct namecache *ncp, *nnp;
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/* Scan hash tables for applicable entries */
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for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
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for (ncp = LIST_FIRST(ncpp); ncp != 0; ncp = nnp) {
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nnp = LIST_NEXT(ncp, nc_hash);
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if (ncp->nc_dvp->v_mount == mp) {
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cache_zap(ncp);
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}
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}
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}
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}
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/*
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* Perform canonical checks and cache lookup and pass on to filesystem
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* through the vop_cachedlookup only if needed.
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*/
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int
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vfs_cache_lookup(ap)
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struct vop_lookup_args /* {
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struct vnode *a_dvp;
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struct vnode **a_vpp;
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struct componentname *a_cnp;
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} */ *ap;
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{
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struct vnode *vdp;
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struct vnode *pdp;
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int lockparent;
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int error;
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struct vnode **vpp = ap->a_vpp;
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struct componentname *cnp = ap->a_cnp;
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struct ucred *cred = cnp->cn_cred;
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int flags = cnp->cn_flags;
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struct proc *p = cnp->cn_proc;
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u_long vpid; /* capability number of vnode */
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*vpp = NULL;
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vdp = ap->a_dvp;
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lockparent = flags & LOCKPARENT;
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if (vdp->v_type != VDIR)
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return (ENOTDIR);
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if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
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(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
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return (EROFS);
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error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc);
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if (error)
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return (error);
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error = cache_lookup(vdp, vpp, cnp);
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if (!error)
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return (VOP_CACHEDLOOKUP(ap->a_dvp, ap->a_vpp, ap->a_cnp));
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if (error == ENOENT)
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return (error);
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pdp = vdp;
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vdp = *vpp;
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vpid = vdp->v_id;
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if (pdp == vdp) { /* lookup on "." */
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VREF(vdp);
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error = 0;
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} else if (flags & ISDOTDOT) {
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VOP_UNLOCK(pdp, 0, p);
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error = vget(vdp, LK_EXCLUSIVE, p);
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if (!error && lockparent && (flags & ISLASTCN))
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error = vn_lock(pdp, LK_EXCLUSIVE, p);
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} else {
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error = vget(vdp, LK_EXCLUSIVE, p);
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if (!lockparent || error || !(flags & ISLASTCN))
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VOP_UNLOCK(pdp, 0, p);
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}
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/*
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* Check that the capability number did not change
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* while we were waiting for the lock.
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*/
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if (!error) {
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if (vpid == vdp->v_id)
|
|
return (0);
|
|
vput(vdp);
|
|
if (lockparent && pdp != vdp && (flags & ISLASTCN))
|
|
VOP_UNLOCK(pdp, 0, p);
|
|
}
|
|
error = vn_lock(pdp, LK_EXCLUSIVE, p);
|
|
if (error)
|
|
return (error);
|
|
return (VOP_CACHEDLOOKUP(ap->a_dvp, ap->a_vpp, ap->a_cnp));
|
|
}
|
|
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct __getcwd_args {
|
|
u_char *buf;
|
|
u_int buflen;
|
|
};
|
|
#endif
|
|
|
|
#define STATNODE(mode, name, var) \
|
|
SYSCTL_INT(_vfs_cache, OID_AUTO, name, mode, var, 0, "");
|
|
|
|
static int disablecwd;
|
|
SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "");
|
|
|
|
static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls);
|
|
static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1);
|
|
static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2);
|
|
static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3);
|
|
static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4);
|
|
static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound);
|
|
int
|
|
__getcwd(p, uap)
|
|
struct proc *p;
|
|
struct __getcwd_args *uap;
|
|
{
|
|
char *bp, *buf;
|
|
int error, i, slash_prefixed;
|
|
struct filedesc *fdp;
|
|
struct namecache *ncp;
|
|
struct vnode *vp;
|
|
|
|
numcwdcalls++;
|
|
if (disablecwd)
|
|
return (ENODEV);
|
|
if (uap->buflen < 2)
|
|
return (EINVAL);
|
|
if (uap->buflen > MAXPATHLEN)
|
|
uap->buflen = MAXPATHLEN;
|
|
buf = bp = malloc(uap->buflen, M_TEMP, M_WAITOK);
|
|
bp += uap->buflen - 1;
|
|
*bp = '\0';
|
|
fdp = p->p_fd;
|
|
slash_prefixed = 0;
|
|
for (vp = fdp->fd_cdir; vp != fdp->fd_rdir && vp != rootvnode;) {
|
|
if (vp->v_flag & VROOT) {
|
|
vp = vp->v_mount->mnt_vnodecovered;
|
|
continue;
|
|
}
|
|
if (vp->v_dd->v_id != vp->v_ddid) {
|
|
numcwdfail1++;
|
|
free(buf, M_TEMP);
|
|
return (ENOTDIR);
|
|
}
|
|
ncp = TAILQ_FIRST(&vp->v_cache_dst);
|
|
if (!ncp) {
|
|
numcwdfail2++;
|
|
free(buf, M_TEMP);
|
|
return (ENOENT);
|
|
}
|
|
if (ncp->nc_dvp != vp->v_dd) {
|
|
numcwdfail3++;
|
|
free(buf, M_TEMP);
|
|
return (EBADF);
|
|
}
|
|
for (i = ncp->nc_nlen - 1; i >= 0; i--) {
|
|
if (bp == buf) {
|
|
numcwdfail4++;
|
|
free(buf, M_TEMP);
|
|
return (ENOMEM);
|
|
}
|
|
*--bp = ncp->nc_name[i];
|
|
}
|
|
if (bp == buf) {
|
|
numcwdfail4++;
|
|
free(buf, M_TEMP);
|
|
return (ENOMEM);
|
|
}
|
|
*--bp = '/';
|
|
slash_prefixed = 1;
|
|
vp = vp->v_dd;
|
|
}
|
|
if (!slash_prefixed) {
|
|
if (bp == buf) {
|
|
numcwdfail4++;
|
|
free(buf, M_TEMP);
|
|
return (ENOMEM);
|
|
}
|
|
*--bp = '/';
|
|
}
|
|
numcwdfound++;
|
|
error = copyout(bp, uap->buf, strlen(bp) + 1);
|
|
free(buf, M_TEMP);
|
|
return (error);
|
|
}
|
|
|