From: Nikolay Borisov <nborisov@suse.com>
Date: Tue, 23 Feb 2021 15:17:43 +0200
Subject: btrfs: Unlock extents in btrfs_zero_range in case of errors
Patch-mainline: Submitted, 23.02.2021 - btrfs mailing list
References: bsc#1182047

If btrfs_qgroup_reserve_data returns an error (i.e quota limit reached)
the handling logic directly goes to the 'out' label without first
unlocking the extent range between lockstart, lockend. This results in
deadlocks as processes try to lock the same extent.

Fixes: a7f8b1c2ac21 ("btrfs: file: reserve qgroup space after the hole punch range is locked")

Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/file.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3154,8 +3154,11 @@ reserve_space:
 			goto out;
 		ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
 						alloc_start, bytes_to_reserve);
-		if (ret)
+		if (ret) {
+			unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
+					     lockend, &cached_state);
 			goto out;
+		}
 		ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
 						alloc_end - alloc_start,
 						i_blocksize(inode),