FAILED: patch "[PATCH] btrfs: mark resumed async balance as writing" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-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 <[email protected]>.

thanks,

greg k-h

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

From a690e5f2db4d1dca742ce734aaff9f3112d63764 Mon Sep 17 00:00:00 2001
From: Naohiro Aota <[email protected]>
Date: Tue, 29 Mar 2022 15:55:58 +0900
Subject: [PATCH] btrfs: mark resumed async balance as writing

When btrfs balance is interrupted with umount, the background balance resumes on the next mount. There is a potential deadlock with FS freezing here like as described in commit 26559780b953 ("btrfs: zoned: mark relocation as writing"). Mark the process as sb_writing to avoid it.

index 2cfbc74a3b4e..a8cc736731fd 100644
@@ -4430,10 +4430,12 @@ static int balance_kthread(void *data)
 	struct btrfs_fs_info *fs_info = data;
 	int ret = 0;
 
+	sb_start_write(fs_info->sb);
 	mutex_lock(&fs_info->balance_mutex);
 	if (fs_info->balance_ctl)
 		ret = btrfs_balance(fs_info, fs_info->balance_ctl, NULL);
 	mutex_unlock(&fs_info->balance_mutex);
+	sb_end_write(fs_info->sb);
 
 	return ret;
 }