btrfs: do not free data reservation in fallback from inline due to -ENOSPC

If we fail to create an inline extent due to -ENOSPC, we will attempt to
go through the normal COW path, reserve an extent, create an ordered
extent, etc. However we were always freeing the reserved qgroup data,
which is wrong since we will use data. Fix this by freeing the reserved
qgroup data in __cow_file_range_inline() only if we are not doing the
fallback (ret is <= 0).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/inode.c

@@ -673,8 +673,12 @@ static noinline int __cow_file_range_inline(struct btrfs_inode *inode,
 	 * it won't count as data extent, free them directly here.
 	 * And at reserve time, it's always aligned to page size, so
 	 * just free one page here.
+	 *
+	 * If we fallback to non-inline (ret == 1) due to -ENOSPC, then we need
+	 * to keep the data reservation.
 	 */
-	btrfs_qgroup_free_data(inode, NULL, 0, fs_info->sectorsize, NULL);
+	if (ret <= 0)
+		btrfs_qgroup_free_data(inode, NULL, 0, fs_info->sectorsize, NULL);
 	btrfs_free_path(path);
 	btrfs_end_transaction(trans);
 	return ret;