On Tue, Oct 19, 2021 at 06:38:20PM +0800, Anand Jain wrote:

From: Josef Bacik <redacted>

Commit b5e6c3e170b77025b5f6174258c7ad71eed2d4de upstream.

There's a priority inversion that exists currently with btrfs fsync.  In
some cases we will collect outstanding ordered extents onto a list and
only wait on them at the very last second.  However this "very last
second" falls inside of a transaction handle, so if we are in a lower
priority cgroup we can end up holding the transaction open for longer
than needed, so if a high priority cgroup is also trying to fsync()
it'll see latency.

Signed-off-by: Josef Bacik <redacted>
Reviewed-by: Filipe Manana <redacted>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Anand Jain <redacted>
---
 fs/btrfs/file.c | 56 ++++---------------------------------------------
 1 file changed, 4 insertions(+), 52 deletions(-)

Now applied, thanks.

greg k-h