Re: [PATCH 11/15] iomap: allow file systems to hook into buffered read bio submission

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Jan 22, 2026 at 07:01:14AM +0100, Christoph Hellwig wrote:
> On Wed, Jan 21, 2026 at 04:49:33PM -0800, Darrick J. Wong wrote:
> > > verifying data checksums.  Allow file systems to hook into submission
> > > of the bio to allow for this processing by replacing the direct
> > > submit_bio call in iomap_read_alloc_bio with a call into ->submit_read
> > > and exporting iomap_read_alloc_bio.  Also add a new field to
> > > struct iomap_read_folio_ctx to track the file logic offset of the current
> > > read context.
> > 
> > Basically you're enabling filesystems to know what's the offset of a
> > read bio that iomap is about to start?
> 
> Yes.
> 
> > I guess that enables btrfs to
> > stash that info somewhere so that when the bio completes, it can go look
> > up the checksum or something, and compare?
> 
> Yes, where something in this series is the ioend that the bio is embedded
> into.
> 
> > Or for PI the filesystem can do the PI validation itself and if that
> > fails, decide if it's going to do something evil like ask another
> > replica to try reading the information?
> 
> Yeah.  If your file system can do it.  Nothing in this series does
> that, though.

<nod> and at this point we're never going to circle back to that project
either.  :/

In the meantime I think I've understood this patch well enough to say
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D