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Restructure union_lock() to always lock before testing for dead node. 

Add two little helpers to lock or unlock a node.  Use "vp" for the
union node and "lockvp" for the node to be locked.  Use ISSET() to
test flags, add assertions.
This commit is contained in:
hannken 2014-03-12 09:40:05 +00:00
parent a8b05c0ddf
commit 5e8d36ac30
1 changed files with 58 additions and 45 deletions
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103
sys/fs/union/union_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: union_vnops.c,v 1.57 2014/02/27 16:51:38 hannken Exp $ */
/* $NetBSD: union_vnops.c,v 1.58 2014/03/12 09:40:05 hannken Exp $ */
/*
* Copyright (c) 1992, 1993, 1994, 1995
@ -72,7 +72,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: union_vnops.c,v 1.57 2014/02/27 16:51:38 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: union_vnops.c,v 1.58 2014/03/12 09:40:05 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -1590,6 +1590,31 @@ union_reclaim(void *v)
return (0);
}
static int
union_lock1(struct vnode *vp, struct vnode *lockvp, int flags)
{
struct vop_lock_args ap;
if (lockvp == vp) {
ap.a_vp = vp;
ap.a_flags = flags;
return genfs_lock(&ap);
} else
return VOP_LOCK(lockvp, flags);
}
static int
union_unlock1(struct vnode *vp, struct vnode *lockvp)
{
struct vop_unlock_args ap;
if (lockvp == vp) {
ap.a_vp = vp;
return genfs_unlock(&ap);
} else
return VOP_UNLOCK(lockvp);
}
int
union_lock(void *v)
{
@ -1597,66 +1622,57 @@ union_lock(void *v)
struct vnode *a_vp;
int a_flags;
} */ *ap = v;
struct vnode *vp;
struct union_node *un = VTOUNION(ap->a_vp);
struct vnode *vp = ap->a_vp, *lockvp;
struct union_node *un = VTOUNION(vp);
int flags = ap->a_flags;
int error;
if ((flags & LK_NOWAIT) != 0) {
if (!mutex_tryenter(&un->un_lock))
return EBUSY;
vp = LOCKVP(ap->a_vp);
if (!mutex_tryenter(vp->v_interlock)) {
mutex_exit(&un->un_lock);
return EBUSY;
}
if ((vp->v_iflag & (VI_XLOCK | VI_CLEAN)) != 0) {
mutex_exit(vp->v_interlock);
mutex_exit(&un->un_lock);
return EBUSY;
}
mutex_exit(vp->v_interlock);
if (vp == ap->a_vp)
error = genfs_lock(ap);
else
error = VOP_LOCK(vp, flags);
lockvp = LOCKVP(vp);
error = union_lock1(vp, lockvp, flags);
mutex_exit(&un->un_lock);
if (error)
return error;
if (mutex_tryenter(vp->v_interlock)) {
if (ISSET(vp->v_iflag, VI_XLOCK))
error = EBUSY;
else if (ISSET(vp->v_iflag, VI_CLEAN))
error = ENOENT;
else
error = 0;
mutex_exit(vp->v_interlock);
} else
error = EBUSY;
if (error)
union_unlock1(vp, lockvp);
return error;
}
mutex_enter(&un->un_lock);
for (;;) {
vp = LOCKVP(ap->a_vp);
lockvp = LOCKVP(vp);
mutex_exit(&un->un_lock);
if (vp == ap->a_vp)
error = genfs_lock(ap);
else
error = VOP_LOCK(vp, ap->a_flags);
error = union_lock1(vp, lockvp, flags);
if (error != 0)
return error;
mutex_enter(&un->un_lock);
if (vp == LOCKVP(ap->a_vp))
if (lockvp == LOCKVP(vp))
break;
if (vp == ap->a_vp)
genfs_unlock(ap);
else
VOP_UNLOCK(vp);
union_unlock1(vp, lockvp);
}
mutex_exit(&un->un_lock);
mutex_enter(vp->v_interlock);
if ((vp->v_iflag & (VI_XLOCK | VI_CLEAN)) != 0) {
if (vp == ap->a_vp)
genfs_unlock(ap);
else
VOP_UNLOCK(vp);
if ((vp->v_iflag & VI_XLOCK))
vwait(vp, VI_XLOCK);
if (ISSET(vp->v_iflag, VI_XLOCK) || ISSET(vp->v_iflag, VI_CLEAN)) {
union_unlock1(vp, lockvp);
vwait(vp, VI_XLOCK);
KASSERT(ISSET(vp->v_iflag, VI_CLEAN));
mutex_exit(vp->v_interlock);
mutex_exit(&un->un_lock);
return ENOENT;
}
mutex_exit(vp->v_interlock);
mutex_exit(&un->un_lock);
return 0;
}
@ -1667,13 +1683,10 @@ union_unlock(void *v)
struct vnode *a_vp;
int a_flags;
} */ *ap = v;
struct vnode *vp;
struct vnode *vp = ap->a_vp, *lockvp;
vp = LOCKVP(ap->a_vp);
if (vp == ap->a_vp)
genfs_unlock(ap);
else
VOP_UNLOCK(vp);
lockvp = LOCKVP(vp);
union_unlock1(vp, lockvp);
return 0;
}