bff1f1d0dd
1. We always keep one 16th of the vnodes on the freelist, so that the namecache doesn't get trashed. It used to be that it wasn't a problem, but the only vnodes getting released these days are directories and things which Clean up and improve the namecache. 1. We always keep one 16th of the vnodes on the freelist, so that the namecache doesn't get trashed. It used to be that it wasn't a problem, but the only vnodes getting released these days are directories and things which gets forced out of the VM/cache. The latter is not numerous enough to keep the pool of vnodes needed for the namecache sufficiently big. 2. Purge invalid entries in the namecache as soon as we notice them. This avoids a stale entry pushing out a valid entry on the LRU list. 3. Speed up the lookup in the namecache by avoid a special case branch. 4. Make the cache purge routines do the thing they're supposed to, and in a decently efficient manner. 5. Make the size of the namecache follow the number of vnodes, so that we can always point to all the vnodes we have in core. 6. Readability has gone way up. 7. Added a "options NCH_STATISTICS" feature that will gather more detailed statistics on the performance of the namecache. Reviewed by: davidg
201 lines
7.5 KiB
C
201 lines
7.5 KiB
C
/*
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* Copyright (c) 1985, 1989, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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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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* @(#)namei.h 8.2 (Berkeley) 1/4/94
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* $Id: namei.h,v 1.4 1995/03/06 06:45:47 phk Exp $
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*/
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#ifndef _SYS_NAMEI_H_
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#define _SYS_NAMEI_H_
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#include <sys/queue.h>
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/*
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* Encapsulation of namei parameters.
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*/
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struct nameidata {
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/*
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* Arguments to namei/lookup.
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*/
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caddr_t ni_dirp; /* pathname pointer */
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enum uio_seg ni_segflg; /* location of pathname */
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/* u_long ni_nameiop; namei operation */
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/* u_long ni_flags; flags to namei */
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/* struct proc *ni_proc; process requesting lookup */
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/*
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* Arguments to lookup.
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*/
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/* struct ucred *ni_cred; credentials */
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struct vnode *ni_startdir; /* starting directory */
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struct vnode *ni_rootdir; /* logical root directory */
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/*
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* Results: returned from/manipulated by lookup
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*/
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struct vnode *ni_vp; /* vnode of result */
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struct vnode *ni_dvp; /* vnode of intermediate directory */
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/*
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* Shared between namei and lookup/commit routines.
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*/
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long ni_pathlen; /* remaining chars in path */
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char *ni_next; /* next location in pathname */
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u_long ni_loopcnt; /* count of symlinks encountered */
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/*
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* Lookup parameters: this structure describes the subset of
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* information from the nameidata structure that is passed
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* through the VOP interface.
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*/
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struct componentname {
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/*
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* Arguments to lookup.
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*/
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u_long cn_nameiop; /* namei operation */
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u_long cn_flags; /* flags to namei */
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struct proc *cn_proc; /* process requesting lookup */
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struct ucred *cn_cred; /* credentials */
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/*
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* Shared between lookup and commit routines.
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*/
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char *cn_pnbuf; /* pathname buffer */
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char *cn_nameptr; /* pointer to looked up name */
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long cn_namelen; /* length of looked up component */
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u_long cn_hash; /* hash value of looked up name */
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long cn_consume; /* chars to consume in lookup() */
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} ni_cnd;
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};
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#ifdef KERNEL
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/*
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* namei operations
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*/
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#define LOOKUP 0 /* perform name lookup only */
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#define CREATE 1 /* setup for file creation */
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#define DELETE 2 /* setup for file deletion */
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#define RENAME 3 /* setup for file renaming */
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#define OPMASK 3 /* mask for operation */
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/*
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* namei operational modifier flags, stored in ni_cnd.flags
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*/
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#define LOCKLEAF 0x0004 /* lock inode on return */
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#define LOCKPARENT 0x0008 /* want parent vnode returned locked */
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#define WANTPARENT 0x0010 /* want parent vnode returned unlocked */
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#define NOCACHE 0x0020 /* name must not be left in cache */
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#define FOLLOW 0x0040 /* follow symbolic links */
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#define NOFOLLOW 0x0000 /* do not follow symbolic links (pseudo) */
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#define MODMASK 0x00fc /* mask of operational modifiers */
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/*
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* Namei parameter descriptors.
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*
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* SAVENAME may be set by either the callers of namei or by VOP_LOOKUP.
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* If the caller of namei sets the flag (for example execve wants to
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* know the name of the program that is being executed), then it must
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* free the buffer. If VOP_LOOKUP sets the flag, then the buffer must
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* be freed by either the commit routine or the VOP_ABORT routine.
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* SAVESTART is set only by the callers of namei. It implies SAVENAME
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* plus the addition of saving the parent directory that contains the
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* name in ni_startdir. It allows repeated calls to lookup for the
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* name being sought. The caller is responsible for releasing the
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* buffer and for vrele'ing ni_startdir.
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*/
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#define NOCROSSMOUNT 0x00100 /* do not cross mount points */
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#define RDONLY 0x00200 /* lookup with read-only semantics */
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#define HASBUF 0x00400 /* has allocated pathname buffer */
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#define SAVENAME 0x00800 /* save pathanme buffer */
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#define SAVESTART 0x01000 /* save starting directory */
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#define ISDOTDOT 0x02000 /* current component name is .. */
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#define MAKEENTRY 0x04000 /* entry is to be added to name cache */
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#define ISLASTCN 0x08000 /* this is last component of pathname */
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#define ISSYMLINK 0x10000 /* symlink needs interpretation */
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#define PARAMASK 0xfff00 /* mask of parameter descriptors */
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/*
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* Initialization of an nameidata structure.
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*/
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#define NDINIT(ndp, op, flags, segflg, namep, p) { \
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(ndp)->ni_cnd.cn_nameiop = op; \
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(ndp)->ni_cnd.cn_flags = flags; \
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(ndp)->ni_segflg = segflg; \
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(ndp)->ni_dirp = namep; \
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(ndp)->ni_cnd.cn_proc = p; \
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}
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#endif
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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. NCHNAMLEN is sized to make structure
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* size a power of two to optimize malloc's. Minimum reasonable
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* size is 15.
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*/
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#ifdef NCH_STATISTICS
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#define NCHNAMLEN 23 /* maximum name segment length we bother with */
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#else
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#define NCHNAMLEN 31 /* maximum name segment length we bother with */
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#endif
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struct namecache {
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LIST_ENTRY(namecache) nc_hash; /* hash chain */
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TAILQ_ENTRY(namecache) nc_lru; /* LRU chain */
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struct vnode *nc_dvp; /* vnode of parent of name */
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u_long nc_dvpid; /* capability number of nc_dvp */
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struct vnode *nc_vp; /* vnode the name refers to */
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u_long nc_vpid; /* capability number of nc_vp */
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#ifdef NCH_STATISTICS
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u_long nc_nbr; /* a serial number */
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u_long nc_hits; /* how many times we got hit */
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#endif
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char nc_nlen; /* length of name */
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char nc_name[NCHNAMLEN]; /* segment name */
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};
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#ifdef KERNEL
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u_long nextvnodeid;
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u_long numvnodes, numcache;
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int namei __P((struct nameidata *ndp));
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int lookup __P((struct nameidata *ndp));
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int relookup __P((struct vnode *dvp, struct vnode **vpp,
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struct componentname *cnp));
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#endif
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/*
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* Stats on usefulness of namei caches.
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*/
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struct nchstats {
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long ncs_goodhits; /* hits that we can really use */
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long ncs_neghits; /* negative hits that we can use */
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long ncs_badhits; /* hits we must drop */
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long ncs_falsehits; /* hits with id mismatch */
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long ncs_miss; /* misses */
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long ncs_long; /* long names that ignore cache */
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long ncs_pass2; /* names found with passes == 2 */
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long ncs_2passes; /* number of times we attempt it */
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};
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#endif /* !_SYS_NAMEI_H_ */
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