solve the biggest problem with concurrent buflist access; makes mfs on

SMP machines reliable. few corner cases remain, which will be
dealt with later; ok deraadt@ millert@

2 files changed, 14 insertions, 4 deletions

diff --git a/sys/ufs/mfs/mfs_vfsops.c b/sys/ufs/mfs/mfs_vfsops.c
index 6264f1a0aef..894534ae7b1 100644
--- a/sys/ufs/mfs/mfs_vfsops.c
+++ b/sys/ufs/mfs/mfs_vfsops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mfs_vfsops.c,v 1.37 2007/12/04 19:32:13 otto Exp $	*/
+/*	$OpenBSD: mfs_vfsops.c,v 1.38 2007/12/06 21:49:37 otto Exp $	*/
 /*	$NetBSD: mfs_vfsops.c,v 1.10 1996/02/09 22:31:28 christos Exp $	*/
 
 /*
@@ -172,11 +172,18 @@ mfs_start(struct mount *mp, int flags, struct proc *p)
 	struct vnode *vp = VFSTOUFS(mp)->um_devvp;
 	struct mfsnode *mfsp = VTOMFS(vp);
 	struct buf *bp;
-	int sleepreturn = 0;
+	int sleepreturn = 0, s;
 
 	while (mfsp->mfs_buflist != (struct buf *)-1) {
-		while ((bp = mfsp->mfs_buflist) != NULL) {
+		while (1) {
+			s = splbio();
+			bp = mfsp->mfs_buflist;
+			if (bp == NULL) {
+				splx(s);
+				break;
+			}
 			mfsp->mfs_buflist = bp->b_actf;
+			splx(s);
 			mfs_doio(mfsp, bp);
 			wakeup((caddr_t)bp);
 		}
diff --git a/sys/ufs/mfs/mfs_vnops.c b/sys/ufs/mfs/mfs_vnops.c
index 1a28d53a378..f9dd66574d3 100644
--- a/sys/ufs/mfs/mfs_vnops.c
+++ b/sys/ufs/mfs/mfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mfs_vnops.c,v 1.30 2007/12/04 19:32:13 otto Exp $	*/
+/*	$OpenBSD: mfs_vnops.c,v 1.31 2007/12/06 21:49:37 otto Exp $	*/
 /*	$NetBSD: mfs_vnops.c,v 1.8 1996/03/17 02:16:32 christos Exp $	*/
 
 /*
@@ -140,6 +140,7 @@ mfs_strategy(void *v)
 	struct mfsnode *mfsp;
 	struct vnode *vp;
 	struct proc *p = curproc;
+	int s;
 
 	if (!vfinddev(bp->b_dev, VBLK, &vp) || vp->v_usecount == 0)
 		panic("mfs_strategy: bad dev");
@@ -148,8 +149,10 @@ mfs_strategy(void *v)
 	if (p != NULL && mfsp->mfs_pid == p->p_pid) {
 		mfs_doio(mfsp, bp);
 	} else {
+		s = splbio();
 		bp->b_actf = mfsp->mfs_buflist;
 		mfsp->mfs_buflist = bp;
+		splx(s);
 		wakeup((caddr_t)vp);
 	}
 	return (0);