Re: [PATCH] iomap: Fix broken data integrity guarantees for O_SYNC writes

[Ritesh Harjani (IBM) <ritesh.list@gmail.com>]

Jan Kara <jack@suse.cz> writes:

> Commit d279c80e0bac ("iomap: inline iomap_dio_bio_opflags()") has broken
> the logic in iomap_dio_bio_iter() in a way that when the device does
> support FUA (or has no writeback cache) and the direct IO happens to
> freshly allocated or unwritten extents, we will *not* issue fsync after
> completing direct IO O_SYNC / O_DSYNC write because the
> IOMAP_DIO_WRITE_THROUGH flag stays mistakenly set. Fix the problem by
> clearing IOMAP_DIO_WRITE_THROUGH whenever we do not perform FUA write as
> it was originally intended.
>
> CC: John Garry <john.g.garry@oracle.com>
> CC: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
> Fixes: d279c80e0bac ("iomap: inline iomap_dio_bio_opflags()")
> CC: stable@vger.kernel.org
> Signed-off-by: Jan Kara <jack@suse.cz>


Nice catch. It's been there since v6.15 I guess. Looks like it didn't
get caught in xfstests either then. 

We have generic/737, but looks like it only covers O_SYNC dio writes. Let
me enhance that to cover O_DYSNC dio writes too.

Looks good to me. Please feel free to add:

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>

-ritesh