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Oops, actually MFC 1.89 (by kan) which was missed in previous commit:

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Handle a race condition where NULLFS vnode can be cleaned while threads
can still be asleep waiting for lowervp lock.

Tested by:	kkenn
Discussed with: ssouhlal, jeffr

(this is an early MFC for inclusion in the upcoming 6.0-BETA5)

Approved by:	re (scottl)
This commit is contained in:
delphij 2005-09-17 15:51:41 +00:00
parent 2adf020846
commit 80a9b1b6e7
1 changed files with 28 additions and 4 deletions
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32
sys/fs/nullfs/null_vnops.c
View File

@ -180,6 +180,7 @@
#include <sys/namei.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/kdb.h>
#include <fs/nullfs/null.h>
@ -545,6 +546,30 @@ null_lock(struct vop_lock_args *ap)
*/
vholdl(lvp);
error = VOP_LOCK(lvp, flags, td);
/*
* We might have slept to get the lock and someone might have
* clean our vnode already, switching vnode lock from one in
* lowervp to v_lock in our own vnode structure. Handle this
* case by reacquiring correct lock in requested mode.
*/
if (VTONULL(vp) == NULL && error == 0) {
ap->a_flags &= ~(LK_TYPE_MASK | LK_INTERLOCK);
switch (flags & LK_TYPE_MASK) {
case LK_SHARED:
ap->a_flags |= LK_SHARED;
break;
case LK_UPGRADE:
case LK_EXCLUSIVE:
ap->a_flags |= LK_EXCLUSIVE;
break;
default:
panic("Unsupported lock request %d\n",
ap->a_flags);
}
VOP_LOCK(lvp, LK_RELEASE, td);
error = vop_stdlock(ap);
}
vdrop(lvp);
} else
error = vop_stdlock(ap);
@ -633,14 +658,13 @@ null_reclaim(struct vop_reclaim_args *ap)
*/
VI_LOCK(vp);
vp->v_data = NULL;
VI_UNLOCK(vp);
vnlock = vp->v_vnlock;
vp->v_vnlock = &vp->v_lock;
lockmgr(vp->v_vnlock, LK_EXCLUSIVE|LK_INTERLOCK, VI_MTX(vp), curthread);
if (lowervp)
null_hashrem(xp);
vp->v_object = NULL;
vnlock = vp->v_vnlock;
vp->v_vnlock = &vp->v_lock;
lockmgr(vp->v_vnlock, LK_EXCLUSIVE, NULL, curthread);
if (lowervp) {
vput(lowervp);
} else