CVS commit: src/sys/ufs/ffs

[Taylor R Campbell]

Module Name:    src
Committed By:   riastradh
Date:           Fri Sep  8 23:21:55 UTC 2023

Modified Files:
        src/sys/ufs/ffs: ffs_vfsops.c

Log Message:
ffs_sync: Avoid unlocked access to v_numoutput/v_dirtyblkhd.

Found by lockdoc.

PR kern/57606


To generate a diff of this commit:
cvs rdiff -u -r1.381 -r1.382 src/sys/ufs/ffs/ffs_vfsops.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.


Modified files:

Index: src/sys/ufs/ffs/ffs_vfsops.c
diff -u src/sys/ufs/ffs/ffs_vfsops.c:1.381 src/sys/ufs/ffs/ffs_vfsops.c:1.382
--- src/sys/ufs/ffs/ffs_vfsops.c:1.381	Thu Jun 15 09:15:54 2023
+++ src/sys/ufs/ffs/ffs_vfsops.c	Fri Sep  8 23:21:55 2023
@@ -1,4 +1,4 @@
-/*	$NetBSD: ffs_vfsops.c,v 1.381 2023/06/15 09:15:54 hannken Exp $	*/
+/*	$NetBSD: ffs_vfsops.c,v 1.382 2023/09/08 23:21:55 riastradh Exp $	*/
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -61,7 +61,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_vfsops.c,v 1.381 2023/06/15 09:15:54 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_vfsops.c,v 1.382 2023/09/08 23:21:55 riastradh Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_ffs.h"
@@ -2021,14 +2021,25 @@ ffs_sync(struct mount *mp, int waitfor, 
 	/*
 	 * Force stale file system control information to be flushed.
 	 */
-	if (waitfor != MNT_LAZY && (ump->um_devvp->v_numoutput > 0 ||
-	    !LIST_EMPTY(&ump->um_devvp->v_dirtyblkhd))) {
-		vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY);
-		if ((error = VOP_FSYNC(ump->um_devvp, cred,
-		    (waitfor == MNT_WAIT ? FSYNC_WAIT : 0) | FSYNC_NOLOG,
-		    0, 0)) != 0)
-			allerror = error;
-		VOP_UNLOCK(ump->um_devvp);
+	if (waitfor != MNT_LAZY)  {
+		bool need_devvp_fsync;
+
+		mutex_enter(ump->um_devvp->v_interlock);
+		need_devvp_fsync = (ump->um_devvp->v_numoutput > 0 ||
+		    !LIST_EMPTY(&ump->um_devvp->v_dirtyblkhd));
+		mutex_exit(ump->um_devvp->v_interlock);
+		if (need_devvp_fsync) {
+			int flags = FSYNC_NOLOG;
+
+			if (waitfor == MNT_WAIT)
+				flags |= FSYNC_WAIT;
+
+			vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY);
+			if ((error = VOP_FSYNC(ump->um_devvp, cred, flags, 0,
+				    0)) != 0)
+				allerror = error;
+			VOP_UNLOCK(ump->um_devvp);
+		}
 	}
 #if defined(QUOTA) || defined(QUOTA2)
 	qsync(mp);