Re: [PATCH 7/7] iov_iter: remove iov_iter_is_aligned

[Keith Busch <kbusch@kernel.org>]

On Fri, Aug 01, 2025 at 10:02:49PM -0400, Mike Snitzer wrote:
> On Fri, Aug 01, 2025 at 04:47:36PM -0700, Keith Busch wrote:
> > From: Keith Busch <kbusch@kernel.org>
> > 
> > No more callers.
> > 
> > Signed-off-by: Keith Busch <kbusch@kernel.org>
> 
> You had me up until this last patch.
> 
> I'm actually making use of iov_iter_is_aligned() in a series of
> changes for both NFS and NFSD.  Chuck has included some of the
> NFSD changes in his nfsd-testing branch, see:
> https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/commit/?h=nfsd-testing&id=5d78ac1e674b45f9c9e3769b48efb27c44f4e4d3
> 
> And the balance of my work that is pending review/inclusion is:
> https://lore.kernel.org/linux-nfs/20250731230633.89983-1-snitzer@kernel.org/
> https://lore.kernel.org/linux-nfs/20250801171049.94235-1-snitzer@kernel.org/
> 
> I only need iov_iter_aligned_bvec, but recall I want to relax its
> checking with this patch:
> https://lore.kernel.org/linux-nfs/20250708160619.64800-5-snitzer@kernel.org/
> 
> Should I just add iov_iter_aligned_bvec() to fs/nfs_common/ so that
> both NFS and NFSD can use it?

If at all possible, I recommend finding a place that already walks the
vectors and do an opprotunistic check for the alignments there. This
will save CPU cycles. For example, nfsd_iter_read already iterates the
bvec while setting each page. Could you check the alignment while doing
that instead of iterating a second time immediately after?