From: matthew <matthew@openbsd.org>
Date: Tue, 3 Aug 2010 04:10:16 +0000 (+0000)
Subject: If an asynchronous request invalidates a buf, then we might remove it
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=68b1adfeabd7627ee019b45160095fa1f6a8bc77;p=openbsd

If an asynchronous request invalidates a buf, then we might remove it
from its vnode's buffer cache in an interrupt context.  Therefore we
need interrupt protection when searching the buffer red-black tree.

ok deraadt@, thib@, art@
---

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 774dfc794ff..0b7b2ccde22 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_bio.c,v 1.124 2010/07/01 16:23:09 thib Exp $	*/
+/*	$OpenBSD: vfs_bio.c,v 1.125 2010/08/03 04:10:16 matthew Exp $	*/
 /*	$NetBSD: vfs_bio.c,v 1.44 1996/06/11 11:15:36 pk Exp $	*/
 
 /*
@@ -873,12 +873,17 @@ incore(struct vnode *vp, daddr64_t blkno)
 {
 	struct buf *bp;
 	struct buf b;
+	int s;
+
+	s = splbio();
 
 	/* Search buf lookup tree */
 	b.b_lblkno = blkno;
 	bp = RB_FIND(buf_rb_bufs, &vp->v_bufs_tree, &b);
-	if (bp && !ISSET(bp->b_flags, B_INVAL))
-		return(bp);
+	if (bp != NULL && ISSET(bp->b_flags, B_INVAL))
+		bp = NULL;
+
+	splx(s);
 	return(NULL);
 }
 
@@ -908,11 +913,10 @@ getblk(struct vnode *vp, daddr64_t blkno, int size, int slpflag, int slptimeo)
 	 * the block until the write is finished.
 	 */
 start:
+	s = splbio();
 	b.b_lblkno = blkno;
 	bp = RB_FIND(buf_rb_bufs, &vp->v_bufs_tree, &b);
 	if (bp != NULL) {
-
-		s = splbio();
 		if (ISSET(bp->b_flags, B_BUSY)) {
 			SET(bp->b_flags, B_WANTED);
 			error = tsleep(bp, slpflag | (PRIBIO + 1), "getblk",
@@ -931,8 +935,8 @@ start:
 			splx(s);
 			return (bp);
 		}
-		splx(s);
 	}
+	splx(s);
 
 	if ((bp = buf_get(vp, blkno, size)) == NULL)
 		goto start;