On Tue, Jan 08, 2019 at 11:44:41AM +0000, fdman...@kernel.org wrote:
> From: Filipe Manana <fdman...@suse.com>
>
> When modifying the free space tree we can end up COWing one of its extent
> buffers which in turn might result in allocating a new chunk, which in
> turn can result in flushing (finish creation) of pending block groups. If
> that happens we can deadlock because creating a pending block group needs
> to update the free space tree, and if any of the updates tries to modify
> the same extent buffer that we are COWing, we end up in a deadlock since
> we try to write lock twice the same extent buffer.
>
> So fix this by skipping pending block group creation if we are COWing an
> extent buffer from the free space tree. This is a case missed by commit
> 5ce555578e091 ("Btrfs: fix deadlock when writing out free space caches").
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202173
> Fixes: 5ce555578e091 ("Btrfs: fix deadlock when writing out free space caches
> Signed-off-by: Filipe Manana <fdman...@suse.com>
Lighweight Reviewed-by, as the bug is in 4.19.x I'm going to push the
fix to 5.0. Thanks.
