[PATCH v4 0/4] NFSD DIRECT: misaligned READs fixup, add handling for misaligned WRITEs

[Mike Snitzer <snitzer@kernel.org>]

Hi,

This series builds on what has been staged in the nfsd-testing branch.

This code has proven to work well during my testing.  Any suggestions
for further refinement are welcome.

Changes since v3:
- fixed nfsd_vfs_write() so work that only needs to happen once, after
  IO is submitted, isn't performed each iteration of the for loop,
  thanks for catching this Chuck.
- updated NFSD's misaligned READ and WRITE handling to not use
  iov_iter_is_aligned() because it will soon be removed upstream.
  - Chuck, provided both you and Jeff agree with patch 1's incremental
    changes, patch 1 should be folded into what you already have in your
    nfsd-testing branch (more justification in patch 1's header)
- dropped the NFSD misaligned DIO NFS reexport patch in favor of
  adding STATX_DIOALIGN support to NFS (the patch to add support will
  be provided in the next NFS DIRECT v7 patchset that I'll post soon).

Changes since v2:
- fixed patch 2 by moving redundant work out of nfsd_vfs_write()'s for
  loop, thanks to Jeff's review.
- added Jeff's Reviewed-by to patches 1-3.
- Left patch 4 in the series because it is pragmatic, but feel free to
  drop it if you'd prefer to see this cat skinned a different way.

Changes since v1:
- switched to using an EVENT_CLASS to create nfsd_analyze_{read,write}_dio
- added 4th patch, if user configured use of NFSD_IO_DIRECT then NFS
  reexports should use it too (in future, with per-export controls
  we'll have the benefit of finer-grained control; but until then we'd
  do well to offer comprehensive use of NFSD_IO_DIRECT if it enabled).

Thanks,
Mike

Mike Snitzer (4):
  NFSD: avoid using iov_iter_is_aligned() in nfsd_iter_read()
  NFSD: refactor nfsd_read_vector_dio to EVENT_CLASS useful for READ and WRITE
  NFSD: prepare nfsd_vfs_write() to use O_DIRECT on misaligned WRITEs
  NFSD: issue WRITEs using O_DIRECT even if IO is misaligned

 fs/nfsd/trace.h |  52 +++++++++----
 fs/nfsd/vfs.c   | 199 +++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 202 insertions(+), 49 deletions(-)

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2.44.0