138ec1f71a
1. Use the default function to access all the specfs operations. 2. Use the default function to access all the fifofs operations. 3. Use the default function to access all the ufs operations. 4. Fix VCALL usage in vfs_cache.c 5. Use VOCALL to access specfs functions in devfs_vnops.c 6. Staticize most of the spec and fifofs vnops functions. 7. Make UFS panic if it lacks bits of the underlying storage handling.
456 lines
13 KiB
C
456 lines
13 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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* $Id: vfs_cache.c,v 1.33 1997/09/24 15:54:10 phk Exp $
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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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/*
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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, cnp) \
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(&nchashtbl[((dvp)->v_id + (cnp)->cn_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, CTL_VFS, cache, CTLFLAG_RW, 0,
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"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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/*
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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_CACHE);
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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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register struct namecache *ncp, *nnp;
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register struct nchashhead *ncpp;
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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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LIST_FOREACH(ncp, (NCHHASH(dvp, cnp)), 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, (u_int)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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register struct namecache *ncp;
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register struct nchashhead *ncpp;
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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_CACHE, 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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ncp->nc_nlen = cnp->cn_namelen;
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bcopy(cnp->cn_nameptr, ncp->nc_name, (unsigned)ncp->nc_nlen);
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ncpp = NCHHASH(dvp, cnp);
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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_CACHE, &nchash);
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}
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/*
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* Invalidate all entries to particular vnode.
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*
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* We actually just increment the v_id, that will do it. The stale entries
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* will be purged by lookup as they get found. If the v_id wraps around, we
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* need to ditch the entire cache, to avoid confusion. No valid vnode will
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* ever have (v_id == 0).
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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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struct namecache *ncp;
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struct nchashhead *ncpp;
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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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nextid++;
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while (nextid == vp->v_id || !nextid)
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continue;
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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)
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return (0);
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vput(vdp);
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if (lockparent && pdp != vdp && (flags & ISLASTCN))
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VOP_UNLOCK(pdp, 0, p);
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}
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error = vn_lock(pdp, LK_EXCLUSIVE, p);
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if (error)
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return (error);
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return (VCALL(vdp, VOFFSET(vop_cachedlookup),
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(struct vop_cachedlookup_args *)ap));
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}
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