FAILED: patch "[PATCH] btrfs: drop the lock on error in btrfs_dev_replace_cancel" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 669e859b5ea7c6f4fce0149d3907c64e550c294b Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 11 Feb 2019 21:32:10 +0300
Subject: [PATCH] btrfs: drop the lock on error in btrfs_dev_replace_cancel

We should drop the lock on this error path.  This has been found by a
static tool.

The lock needs to be released, it's there to protect access to the
dev_replace members and is not supposed to be left locked. The value of
state that's being switched would need to be artifically changed to an
invalid value so the default: branch is taken.

Fixes: d189dd70e255 ("btrfs: fix use-after-free due to race between replace start and cancel")
CC: stable@vger.kernel.org # 5.0+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 13863354ff9d..ee193c5222b2 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -862,6 +862,7 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 			btrfs_destroy_dev_replace_tgtdev(tgt_device);
 		break;
 	default:
+		up_write(&dev_replace->rwsem);
 		result = -EINVAL;
 	}