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- Greatly simplify vget() by removing the guarantee that any new

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references to a vnode with VI_OWEINACT set will force the vinactive()
   call.  The kernel makes no guarantees about which reference was the
   last to close a file or when the actual inactive processing will
   happen.  The previous code was designed to preserve existing semantics
   in the face of shared locks, however, this was unnecessary.

Discussed with:	mckusick
This commit is contained in:
Jeff Roberson 2008-03-24 04:22:58 +00:00
parent 804e60d4cf
commit 0ee6cecc9d
1 changed files with 18 additions and 32 deletions
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50
sys/kern/vfs_subr.c
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@ -2030,57 +2030,43 @@ v_decr_useonly(struct vnode *vp)
/*
* Grab a particular vnode from the free list, increment its
* reference count and lock it. The vnode lock bit is set if the
* vnode is being eliminated in vgone. The process is awakened
* when the transition is completed, and an error returned to
* indicate that the vnode is no longer usable (possibly having
* been changed to a new filesystem type).
* reference count and lock it. VI_DOOMED is set if the vnode
* is being destroyed. Only callers who specify LK_RETRY will
* see doomed vnodes. If inactive processing was delayed in
* vput try to do it here.
*/
int
vget(struct vnode *vp, int flags, struct thread *td)
{
int oweinact;
int oldflags;
int error;
error = 0;
oldflags = flags;
oweinact = 0;
VFS_ASSERT_GIANT(vp->v_mount);
if ((flags & LK_INTERLOCK) == 0)
VI_LOCK(vp);
/*
* If the inactive call was deferred because vput() was called
* with a shared lock, we have to do it here before another thread
* gets a reference to data that should be dead.
*/
if (vp->v_iflag & VI_OWEINACT) {
if (flags & LK_NOWAIT) {
VI_UNLOCK(vp);
return (EBUSY);
}
flags &= ~LK_TYPE_MASK;
flags |= LK_EXCLUSIVE;
oweinact = 1;
}
vholdl(vp);
if ((error = vn_lock(vp, flags | LK_INTERLOCK)) != 0) {
vdrop(vp);
return (error);
}
if (vp->v_iflag & VI_DOOMED && (flags & LK_RETRY) == 0)
panic("vget: vn_lock failed to return ENOENT\n");
VI_LOCK(vp);
/* Upgrade our holdcnt to a usecount. */
v_upgrade_usecount(vp);
if (vp->v_iflag & VI_DOOMED && (flags & LK_RETRY) == 0)
panic("vget: vn_lock failed to return ENOENT\n");
if (oweinact) {
if (vp->v_iflag & VI_OWEINACT)
/*
* We don't guarantee that any particular close will
* trigger inactive processing so just make a best effort
* here at preventing a reference to a removed file. If
* we don't succeed no harm is done.
*/
if (vp->v_iflag & VI_OWEINACT) {
if (VOP_ISLOCKED(vp) == LK_EXCLUSIVE &&
(flags & LK_NOWAIT) == 0)
vinactive(vp, td);
VI_UNLOCK(vp);
if ((oldflags & LK_TYPE_MASK) == 0)
VOP_UNLOCK(vp, 0);
} else
VI_UNLOCK(vp);
vp->v_iflag &= ~VI_OWEINACT;
}
VI_UNLOCK(vp);
return (0);
}