[PATCH 0/5 v3] fuse direct write consolidation and parallel IO

[Bernd Schubert <bschubert@ddn.com>]

This series consolidates DIO writes into a single code path via
fuse_cache_write_iter/generic_file_direct_write. Before
it was only used for O_DIRECT and when writeback cache was not enabled.
For server/daemon dio enforcement (FOPEN_DIRECT_IO) another code
path was used before, but I _think_ that is not needed and
just IOCB_DIRECT needs to be set/enforced.
When writeback-cache was enabled another code path was used, with
a fallback to write-through - for direct IO that should not be
needed either.

So far O_DIRECT through fuse_cache_write_iter also took an exclusive
lock, this should not be needed either, at least when server side
sets FOPEN_PARALLEL_DIRECT_WRITES.

v3:
Addresses review comments
  - Rename fuse_direct_write_extending_i_size to io_past_eof
  - Change to single line conditions in fuse_dio_wr_exclusive_lock
    (also fixes accidental parenthesis).
  - Add another patch to rename fuse_direct_io to fuse_send_dio
  - Add detailed information into the commit message of the patch 
    that consolidates IO paths (5/6, previously 4/5) and also 
    update the subject.

v2: 
The entire v1 approach to route DIO writes through fuse_direct_write_iter
was turned around and fuse_direct_write_iter is removed instead and all
DIO writes are now routed through fuse_cache_write_iter

Cc: Hao Xu <howeyxu@tencent.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Dharmendra Singh <dsingh@ddn.com>
Cc: linux-fsdevel@vger.kernel.org

Bernd Schubert (5):
  fuse: direct IO can use the write-through code path
  fuse: Create helper function if DIO write needs exclusive lock
  fuse: Allow parallel direct writes for O_DIRECT
  [RFC] fuse: Set and use IOCB_DIRECT when FOPEN_DIRECT_IO is set
  fuse: Remove page flush/invaliation in fuse_direct_io

 fs/fuse/file.c  | 122 ++++++++++++++++--------------------------------
 fs/fuse/xattr.c |   8 ++--
 2 files changed, 43 insertions(+), 87 deletions(-)

-- 
2.39.2