345 lines
9.4 KiB
C
345 lines
9.4 KiB
C
/*
|
|
* Copyright (c) 1989, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)vfs_cache.c 8.1 (Berkeley) 6/10/93
|
|
* $Id: vfs_cache.c,v 1.3 1994/08/02 07:43:15 davidg Exp $
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/time.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/namei.h>
|
|
#include <sys/errno.h>
|
|
#include <sys/malloc.h>
|
|
|
|
/*
|
|
* Name caching works as follows:
|
|
*
|
|
* Names found by directory scans are retained in a cache
|
|
* for future reference. It is managed LRU, so frequently
|
|
* used names will hang around. Cache is indexed by hash value
|
|
* obtained from (vp, name) where vp refers to the directory
|
|
* containing name.
|
|
*
|
|
* For simplicity (and economy of storage), names longer than
|
|
* a maximum length of NCHNAMLEN are not cached; they occur
|
|
* infrequently in any case, and are almost never of interest.
|
|
*
|
|
* Upon reaching the last segment of a path, if the reference
|
|
* is for DELETE, or NOCACHE is set (rewrite), and the
|
|
* name is located in the cache, it will be dropped.
|
|
*/
|
|
|
|
/*
|
|
* Structures associated with name cacheing.
|
|
*/
|
|
struct namecache **nchashtbl;
|
|
u_long nchash; /* size of hash table - 1 */
|
|
long numcache; /* number of cache entries allocated */
|
|
struct namecache *nchhead, **nchtail; /* LRU chain pointers */
|
|
struct nchstats nchstats; /* cache effectiveness statistics */
|
|
|
|
int doingcache = 1; /* 1 => enable the cache */
|
|
|
|
/*
|
|
* Look for a the name in the cache. We don't do this
|
|
* if the segment name is long, simply so the cache can avoid
|
|
* holding long names (which would either waste space, or
|
|
* add greatly to the complexity).
|
|
*
|
|
* Lookup is called with ni_dvp pointing to the directory to search,
|
|
* ni_ptr pointing to the name of the entry being sought, ni_namelen
|
|
* tells the length of the name, and ni_hash contains a hash of
|
|
* the name. If the lookup succeeds, the vnode is returned in ni_vp
|
|
* and a status of -1 is returned. If the lookup determines that
|
|
* the name does not exist (negative cacheing), a status of ENOENT
|
|
* is returned. If the lookup fails, a status of zero is returned.
|
|
*/
|
|
int
|
|
cache_lookup(dvp, vpp, cnp)
|
|
struct vnode *dvp;
|
|
struct vnode **vpp;
|
|
struct componentname *cnp;
|
|
{
|
|
register struct namecache *ncp, *ncq, **ncpp;
|
|
|
|
if (!doingcache)
|
|
return (0);
|
|
if (cnp->cn_namelen > NCHNAMLEN) {
|
|
nchstats.ncs_long++;
|
|
cnp->cn_flags &= ~MAKEENTRY;
|
|
return (0);
|
|
}
|
|
ncpp = &nchashtbl[cnp->cn_hash & nchash];
|
|
for (ncp = *ncpp; ncp; ncp = ncp->nc_forw) {
|
|
if (ncp->nc_dvp == dvp &&
|
|
ncp->nc_dvpid == dvp->v_id &&
|
|
ncp->nc_nlen == cnp->cn_namelen &&
|
|
!bcmp(ncp->nc_name, cnp->cn_nameptr, (u_int)ncp->nc_nlen))
|
|
break;
|
|
}
|
|
if (ncp == NULL) {
|
|
nchstats.ncs_miss++;
|
|
return (0);
|
|
}
|
|
if (!(cnp->cn_flags & MAKEENTRY)) {
|
|
nchstats.ncs_badhits++;
|
|
} else if (ncp->nc_vp == NULL) {
|
|
if (cnp->cn_nameiop != CREATE) {
|
|
nchstats.ncs_neghits++;
|
|
/*
|
|
* Move this slot to end of LRU chain,
|
|
* if not already there.
|
|
*/
|
|
if (ncp->nc_nxt) {
|
|
/* remove from LRU chain */
|
|
*ncp->nc_prev = ncp->nc_nxt;
|
|
ncp->nc_nxt->nc_prev = ncp->nc_prev;
|
|
/* and replace at end of it */
|
|
ncp->nc_nxt = NULL;
|
|
ncp->nc_prev = nchtail;
|
|
*nchtail = ncp;
|
|
nchtail = &ncp->nc_nxt;
|
|
}
|
|
return (ENOENT);
|
|
}
|
|
} else if (ncp->nc_vpid != ncp->nc_vp->v_id) {
|
|
nchstats.ncs_falsehits++;
|
|
} else {
|
|
nchstats.ncs_goodhits++;
|
|
/*
|
|
* move this slot to end of LRU chain, if not already there
|
|
*/
|
|
if (ncp->nc_nxt) {
|
|
/* remove from LRU chain */
|
|
*ncp->nc_prev = ncp->nc_nxt;
|
|
ncp->nc_nxt->nc_prev = ncp->nc_prev;
|
|
/* and replace at end of it */
|
|
ncp->nc_nxt = NULL;
|
|
ncp->nc_prev = nchtail;
|
|
*nchtail = ncp;
|
|
nchtail = &ncp->nc_nxt;
|
|
}
|
|
*vpp = ncp->nc_vp;
|
|
return (-1);
|
|
}
|
|
|
|
/*
|
|
* Last component and we are renaming or deleting,
|
|
* the cache entry is invalid, or otherwise don't
|
|
* want cache entry to exist.
|
|
*/
|
|
/* remove from LRU chain */
|
|
ncq = ncp->nc_nxt;
|
|
if (ncq)
|
|
ncq->nc_prev = ncp->nc_prev;
|
|
else
|
|
nchtail = ncp->nc_prev;
|
|
*ncp->nc_prev = ncq;
|
|
/* remove from hash chain */
|
|
ncq = ncp->nc_forw;
|
|
if (ncq)
|
|
ncq->nc_back = ncp->nc_back;
|
|
*ncp->nc_back = ncq;
|
|
/* and make a dummy hash chain */
|
|
ncp->nc_forw = NULL;
|
|
ncp->nc_back = NULL;
|
|
/* insert at head of LRU list (first to grab) */
|
|
ncq = nchhead;
|
|
if (ncq)
|
|
ncq->nc_prev = &ncp->nc_nxt;
|
|
else
|
|
nchtail = &ncp->nc_nxt;
|
|
nchhead = ncp;
|
|
ncp->nc_nxt = ncq;
|
|
ncp->nc_prev = &nchhead;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Add an entry to the cache
|
|
*/
|
|
void
|
|
cache_enter(dvp, vp, cnp)
|
|
struct vnode *dvp;
|
|
struct vnode *vp;
|
|
struct componentname *cnp;
|
|
{
|
|
register struct namecache *ncp, *ncq, **ncpp;
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if (cnp->cn_namelen > NCHNAMLEN)
|
|
panic("cache_enter: name too long");
|
|
#endif
|
|
if (!doingcache)
|
|
return;
|
|
/*
|
|
* Free the cache slot at head of lru chain.
|
|
*/
|
|
if (numcache < desiredvnodes) {
|
|
ncp = (struct namecache *)
|
|
malloc((u_long)sizeof *ncp, M_CACHE, M_WAITOK);
|
|
bzero((char *)ncp, sizeof *ncp);
|
|
numcache++;
|
|
} else if (!nchhead) {
|
|
return;
|
|
} else {
|
|
ncp = nchhead;
|
|
/* remove from lru chain */
|
|
ncq = ncp->nc_nxt;
|
|
if (ncq)
|
|
ncq->nc_prev = ncp->nc_prev;
|
|
else
|
|
nchtail = ncp->nc_prev;
|
|
*ncp->nc_prev = ncq;
|
|
/* remove from old hash chain, if on one */
|
|
if (ncp->nc_back) {
|
|
ncq = ncp->nc_forw;
|
|
if (ncq)
|
|
ncq->nc_back = ncp->nc_back;
|
|
*ncp->nc_back = ncq;
|
|
ncp->nc_forw = NULL;
|
|
ncp->nc_back = NULL;
|
|
}
|
|
}
|
|
/* grab the vnode we just found */
|
|
ncp->nc_vp = vp;
|
|
if (vp)
|
|
ncp->nc_vpid = vp->v_id;
|
|
else
|
|
ncp->nc_vpid = 0;
|
|
/* fill in cache info */
|
|
ncp->nc_dvp = dvp;
|
|
ncp->nc_dvpid = dvp->v_id;
|
|
ncp->nc_nlen = cnp->cn_namelen;
|
|
bcopy(cnp->cn_nameptr, ncp->nc_name, (unsigned)ncp->nc_nlen);
|
|
/* link at end of lru chain */
|
|
ncp->nc_nxt = NULL;
|
|
ncp->nc_prev = nchtail;
|
|
*nchtail = ncp;
|
|
nchtail = &ncp->nc_nxt;
|
|
/* and insert on hash chain */
|
|
ncpp = &nchashtbl[cnp->cn_hash & nchash];
|
|
ncq = *ncpp;
|
|
if (ncq)
|
|
ncq->nc_back = &ncp->nc_forw;
|
|
ncp->nc_forw = ncq;
|
|
ncp->nc_back = ncpp;
|
|
*ncpp = ncp;
|
|
}
|
|
|
|
/*
|
|
* Name cache initialization, from vfs_init() when we are booting
|
|
*/
|
|
void
|
|
nchinit()
|
|
{
|
|
|
|
nchtail = &nchhead;
|
|
nchashtbl = hashinit(desiredvnodes, M_CACHE, &nchash);
|
|
}
|
|
|
|
/*
|
|
* Cache flush, a particular vnode; called when a vnode is renamed to
|
|
* hide entries that would now be invalid
|
|
*/
|
|
void
|
|
cache_purge(vp)
|
|
struct vnode *vp;
|
|
{
|
|
struct namecache *ncp, **ncpp;
|
|
|
|
vp->v_id = ++nextvnodeid;
|
|
if (nextvnodeid != 0)
|
|
return;
|
|
for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
|
|
for (ncp = *ncpp; ncp; ncp = ncp->nc_forw) {
|
|
ncp->nc_vpid = 0;
|
|
ncp->nc_dvpid = 0;
|
|
}
|
|
}
|
|
vp->v_id = ++nextvnodeid;
|
|
}
|
|
|
|
/*
|
|
* Cache flush, a whole filesystem; called when filesys is umounted to
|
|
* remove entries that would now be invalid
|
|
*
|
|
* The line "nxtcp = nchhead" near the end is to avoid potential problems
|
|
* if the cache lru chain is modified while we are dumping the
|
|
* inode. This makes the algorithm O(n^2), but do you think I care?
|
|
*/
|
|
void
|
|
cache_purgevfs(mp)
|
|
struct mount *mp;
|
|
{
|
|
register struct namecache *ncp, *nxtcp;
|
|
|
|
for (ncp = nchhead; ncp; ncp = nxtcp) {
|
|
if (ncp->nc_dvp == NULL || ncp->nc_dvp->v_mount != mp) {
|
|
nxtcp = ncp->nc_nxt;
|
|
continue;
|
|
}
|
|
/* free the resources we had */
|
|
ncp->nc_vp = NULL;
|
|
ncp->nc_dvp = NULL;
|
|
/* remove from old hash chain, if on one */
|
|
if (ncp->nc_back) {
|
|
nxtcp = ncp->nc_forw;
|
|
if (nxtcp)
|
|
nxtcp->nc_back = ncp->nc_back;
|
|
*ncp->nc_back = nxtcp;
|
|
ncp->nc_forw = NULL;
|
|
ncp->nc_back = NULL;
|
|
}
|
|
/* delete this entry from LRU chain */
|
|
nxtcp = ncp->nc_nxt;
|
|
if (nxtcp)
|
|
nxtcp->nc_prev = ncp->nc_prev;
|
|
else
|
|
nchtail = ncp->nc_prev;
|
|
*ncp->nc_prev = nxtcp;
|
|
/* cause rescan of list, it may have altered */
|
|
/* also put the now-free entry at head of LRU */
|
|
nxtcp = nchhead;
|
|
if (nxtcp)
|
|
nxtcp->nc_prev = &ncp->nc_nxt;
|
|
else
|
|
nchtail = &ncp->nc_nxt;
|
|
nchhead = ncp;
|
|
ncp->nc_nxt = nxtcp;
|
|
ncp->nc_prev = &nchhead;
|
|
}
|
|
}
|