Re: [Cluster-devel] [PATCH 05/12] gfs2: fix O_SYNC write handling

[Andreas Gruenbacher]

Hi Christoph,

thanks for this patch, and sorry for taking so long to react.

On Tue, Jan 14, 2020 at 5:54 PM Christoph Hellwig <hch@xxxxxx> wrote:
> Don't ignore the return value from generic_write_sync for the direct to
> buffered I/O callback case when written is non-zero.  Also don't bother
> to call generic_write_sync for the pure direct I/O case, as iomap_dio_rw
> already takes care of that.

I like the idea, but the patch as is doesn't quite work: iomap_dio_rw
already bumps iocb->ki_pos, so we end up with the wrong value by
adding the (direct + buffered) write size again.
We'd probably also be better served by replacing
filemap_write_and_wait_range with generic_write_sync + IOCB_DSYNC in
the buffered fallback case. I'll send an update that you'll hopefully
like.

Andreas