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cache_lookup: avoid to grab two vnode's v_interlock.

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just hold a reference (usecount) to a vnode instead.
This commit is contained in:
yamt 2004-06-19 18:49:47 +00:00
parent b2563527a8
commit 8a2c13021f
1 changed files with 10 additions and 12 deletions
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22
sys/kern/vfs_cache.c
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@ -1,4 +1,4 @@
/* $NetBSD: vfs_cache.c,v 1.59 2004/05/07 12:05:41 yamt Exp $ */
/* $NetBSD: vfs_cache.c,v 1.60 2004/06/19 18:49:47 yamt Exp $ */
/*
* Copyright (c) 1989, 1993
@ -32,7 +32,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.59 2004/05/07 12:05:41 yamt Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.60 2004/06/19 18:49:47 yamt Exp $");
#include "opt_ddb.h"
#include "opt_revcache.h"
@ -234,10 +234,9 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
}
if (vp != dvp)
simple_lock(&vp->v_interlock);
error = vget(vp, LK_NOWAIT);
/* Release the name cache mutex while we acquire vnode locks */
/* Release the name cache mutex while we get reference to the vnode */
simple_unlock(&namecache_slock);
#ifdef DEBUG
@ -248,24 +247,23 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
ncp = NULL;
#endif /* DEBUG */
if (vp != dvp && __predict_false(vp->v_flag & VXLOCK)) {
if (error) {
KASSERT(error == EBUSY);
/*
* this vnode is being cleaned out.
*/
simple_unlock(&vp->v_interlock);
nchstats.ncs_falsehits++; /* XXX badhits? */
goto fail;
}
if (vp == dvp) { /* lookup on "." */
VREF(dvp);
error = 0;
} else if (cnp->cn_flags & ISDOTDOT) {
VOP_UNLOCK(dvp, 0);
cnp->cn_flags |= PDIRUNLOCK;
error = vget(vp, LK_EXCLUSIVE | LK_INTERLOCK);
error = vn_lock(vp, LK_EXCLUSIVE);
/*
* If the above vget() succeeded and both LOCKPARENT and
* If the above vn_lock() succeeded and both LOCKPARENT and
* ISLASTCN is set, lock the directory vnode as well.
*/
if (!error && (~cnp->cn_flags & (LOCKPARENT|ISLASTCN)) == 0) {
@ -276,9 +274,9 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
cnp->cn_flags &= ~PDIRUNLOCK;
}
} else {
error = vget(vp, LK_EXCLUSIVE | LK_INTERLOCK);
error = vn_lock(vp, LK_EXCLUSIVE);
/*
* If the above vget() failed or either of LOCKPARENT or
* If the above vn_lock() failed or either of LOCKPARENT or
* ISLASTCN is set, unlock the directory vnode.
*/
if (error || (~cnp->cn_flags & (LOCKPARENT|ISLASTCN)) != 0) {