From 1acd6831d98779c88cd57f0a5826d6df0b09f3fa Mon Sep 17 00:00:00 2001 From: Stefan Behrens Date: Mon, 5 Nov 2012 17:11:06 +0100 Subject: [PATCH] Btrfs: avoid risk of a deadlock in btrfs_handle_error Remove the attempt to cancel a running scrub or device replace operation in btrfs_handle_error() because it adds the risk of a deadlock. The only penalty of not canceling the operation is that some I/O remains active until the procedure completes. This is basically the same thing that happens to other tasks that are running in user mode context, they are not affected or stopped in btrfs_handle_error(), these tasks just need to handle write errors correctly. Signed-off-by: Stefan Behrens Signed-off-by: Chris Mason --- fs/btrfs/super.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index a1a6c296ddcd..ef2415896b06 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -116,7 +116,16 @@ static void btrfs_handle_error(struct btrfs_fs_info *fs_info) if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { sb->s_flags |= MS_RDONLY; printk(KERN_INFO "btrfs is forced readonly\n"); - btrfs_scrub_cancel(fs_info); + /* + * Note that a running device replace operation is not + * canceled here although there is no way to update + * the progress. It would add the risk of a deadlock, + * therefore the canceling is ommited. The only penalty + * is that some I/O remains active until the procedure + * completes. The next time when the filesystem is + * mounted writeable again, the device replace + * operation continues. + */ // WARN_ON(1); } }