From: Eric Sandeen <sandeen@redhat.com>
Subject: Re: [RHEL5 PATCH] ext3: handle orphan inodes vs. readonly snapshots
Date: Fri, 13 Apr 2007 12:40:02 -0500
Bugzilla: 231553
Message-Id: <461FC072.8040608@redhat.com>
Changelog: [ext3] handle orphan inodes vs. readonly snapshots

[PATCH] ext3: refuse ro to rw remount of fs with orphan inodes

In the rare case where we have skipped orphan inode processing due to a
readonly block device, and the block device subsequently changes back to
read-write, disallow a remount,rw transition of the filesystem when we have an
unprocessed orphan inodes as this would corrupt the list.

Ideally we should process the orphan inode list during the remount, but that's
trickier, and this plugs the hole for now.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

Index: linux-2.6.18-13.el5/fs/ext3/super.c
===================================================================
--- linux-2.6.18-13.el5.orig/fs/ext3/super.c
+++ linux-2.6.18-13.el5/fs/ext3/super.c
@@ -1264,6 +1264,12 @@ static void ext3_orphan_cleanup (struct 
 		return;
 	}
 
+	if (bdev_read_only(sb->s_bdev)) {
+		printk(KERN_ERR "EXT3-fs: write access "
+			"unavailable, skipping orphan cleanup.\n");
+		return;
+	}
+
 	if (EXT3_SB(sb)->s_mount_state & EXT3_ERROR_FS) {
 		if (es->s_last_orphan)
 			jbd_debug(1, "Errors on filesystem, "
@@ -2339,6 +2345,20 @@ static int ext3_remount (struct super_bl
 				err = -EROFS;
 				goto restore_opts;
 			}
+ 			/*
+			 * If we have an unprocessed orphan list hanging
+			 * around from a previously readonly bdev mount,
+			 * require a full umount/remount for now.
+			 */
+			if (es->s_last_orphan) {
+				printk(KERN_WARNING "EXT3-fs: %s: couldn't "
+				       "remount RDWR because of unprocessed "
+				       "orphan inode list.  Please "
+				       "umount/remount instead.\n",
+				       sb->s_id);
+				err = -EINVAL;
+				goto restore_opts;
+			}
 			/*
 			 * Mounting a RDONLY partition read-write, so reread
 			 * and store the current valid flag.  (It may have