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[v3,0/5] NFS: Improvements for the NFSv4.2 READ_PLUS operation

Message ID 20220721182135.1885071-1-anna@kernel.org (mailing list archive)
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Series NFS: Improvements for the NFSv4.2 READ_PLUS operation | expand

Message

Anna Schumaker July 21, 2022, 6:21 p.m. UTC 
From: Anna Schumaker <Anna.Schumaker@Netapp.com>

Previously, decoding was a one step process that expanded holes as they
were seen in the buffer. This had a few undesireable side effects:

1) An extra READ_PLUS call was often needed to fetch any data shifted
   off the end of the buffer when the last two segments are a HOLE
   followed by DATA
2) We shifted the entire remaining buffer for each hole, meaning some
   segments would get moved multiple times during one decode pass.

These patches attempt to address this by turning READ_PLUS decoding into
a two-step process. First, we build up a list of each segment returned
by the server, then we walk the list in reverse and move each segment
directly to their target offset. This cuts out all the extra copying,
and means we won't lose any data off of the end of the reply.

Changes in V3:
  - Move the "Introduce xdr_stream_move_subsegment()" patch into this
    series so it can be applied now while work on the server side
    continues.
  - Drop the patch removing the Kconfig option at Trond's suggestion.

Thoughts?
Anna


Anna Schumaker (5):
  SUNRPC: Introduce xdr_stream_move_subsegment()
  SUNRPC: Add a function for directly setting the xdr page len
  SUNRPC: Add a function for zeroing out a portion of an xdr_stream
  NFS: Replace the READ_PLUS decoding code
  SUNRPC: Remove xdr_align_data() and xdr_expand_hole()

 fs/nfs/nfs42xdr.c          | 168 ++++++++++++++++++------------------
 include/linux/sunrpc/xdr.h |   7 +-
 net/sunrpc/xdr.c           | 170 +++++++++++++++++++++++--------------
 3 files changed, 200 insertions(+), 145 deletions(-)