[PATCH v6 0/6] NFSD direct I/O read

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

The goal is to get the experimental read-side direct I/O
implementation merged sooner. We are still thinking through the
implications of mixing direct and buffered I/O when handling an
NFS WRITE that does not meet the dio alignment requirements.

Changes since v5:
* Rebased on what's now in v6.18-rc1
* getattr failures now properly cleaned up
* Fix patches have been moved to the front of the series

Changes since v4:
* Additional Reviewed-by's; applying v5 to nfsd-testing
* Address Christoph's comments on 4/4
* Suggest a couple of clean-ups for 1/4

Changes since v3:
* Move xdr_reserve_space_vec() call to preserve the page_len value
* Note that "add STATX_DIOALIGN and STATX_DIO_READ_ALIGN ..."
  remains exactly the same as it was in the v3 series

Changes since v2:
* "Add array bounds-checking..." has been applied to nfsd-testing
* Add a page_len check before committing to use direct I/O

Changes since v1:
* Harden the loop that constructs the I/O bvec
* Address review comments

Changes from Mike's v9:
* The LOC introduced by the feature has been reduced considerably.
* A new trace point in nfsd_file_getattr reports each file's dio
  alignment parameters when it is opened.
* The direct I/O path has been taken out-of-line so that it may
  continue to be modified and optimized without perturbing the more
  commonly-used I/O paths.
* When an exported file system does not implement direct I/O, more
  commonly-used modes are employed instead to avoid returning
  EOPNOTSUPP unexpectedly.
* When NFSD_IO_DIRECT is selected, NFS READs of all sizes use direct
  I/O to provide better experimental data about small I/O workloads.

Chuck Lever (4):
  NFSD: Prevent a NULL pointer dereference in fh_getattr()
  NFSD: Recover from vfs_getattr() failure in nfsd_file_get_dio_attrs()
  NFSD: Relocate the xdr_reserve_space_vec() call site
  NFSD: Implement NFSD_IO_DIRECT for NFS READ

Mike Snitzer (1):
  NFSD: pass nfsd_file to nfsd_iter_read()

NeilBrown (1):
  nfsd: fix refcount leak in nfsd_set_fh_dentry()

 fs/nfsd/debugfs.c   |  2 +
 fs/nfsd/filecache.c |  5 ++-
 fs/nfsd/nfs4xdr.c   | 28 ++++++++++----
 fs/nfsd/nfsd.h      |  1 +
 fs/nfsd/nfsfh.c     |  9 ++---
 fs/nfsd/trace.h     |  1 +
 fs/nfsd/vfs.c       | 90 +++++++++++++++++++++++++++++++++++++++++++--
 fs/nfsd/vfs.h       |  2 +-
 8 files changed, 120 insertions(+), 18 deletions(-)

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2.51.0