The patch below does not apply to the 4.4-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 315bf8ef914f31d51d084af950703aa1e09a728c Mon Sep 17 00:00:00 2001

From: Josef Bacik josef@toxicpanda.com Date: Thu, 13 Feb 2020 10:47:28 -0500 Subject: [PATCH] btrfs: reset fs_root to NULL on error in open_ctree

While running my error injection script I hit a panic when we tried to clean up the fs_root when freeing the fs_root. This is because fs_info->fs_root == PTR_ERR(-EIO), which isn't great. Fix this by setting fs_info->fs_root = NULL; if we fail to read the root.

CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Nikolay Borisov nborisov@suse.com Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Reviewed-by: Qu Wenruo wqu@suse.com Signed-off-by: Josef Bacik josef@toxicpanda.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index d7fec89974cb..197352f23534 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3200,6 +3200,7 @@ int __cold open_ctree(struct super_block *sb, if (IS_ERR(fs_info->fs_root)) { err = PTR_ERR(fs_info->fs_root); btrfs_warn(fs_info, "failed to read fs tree: %d", err); + fs_info->fs_root = NULL; goto fail_qgroup; }