[PATCH 5.16 028/227] btrfs: dont hold CPU for too long when defragging a file

Greg Kroah-Hartman
2022-02-21T09:48:09Z

From: Qu Wenruo <wqu@suse.com>

commit ea0eba69a2a8125229b1b6011644598039bc53aa upstream.

There is a user report about "btrfs filesystem defrag" causing 120s
timeout problem.

For btrfs_defrag_file() it will iterate all file extents if called from
defrag ioctl, thus it can take a long time.

There is no reason not to release the CPU during such a long operation.

Add cond_resched() after defragged one cluster.

CC: stable@vger.kernel.org # 5.16
Link: https://lore.kernel.org/linux-btrfs/10e51417-2203-f0a4-2021-86c8511cc367@gmx.com
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/ioctl.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1603,6 +1603,7 @@ int btrfs_defrag_file(struct inode *inod
ret = 0;
break;
}
+ cond_resched();
}

if (ra_allocated)