[PATCH 0/8] iomap writethrough for O_SYNC writes

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Files opened with O_SYNC (... or similar) are currently handled by writing
to the page, marking it dirty, then finding all dirty pages, clearing
their dirty bit, marking them as writeback and waiting for the writeback
to complete.  This patchset bypasses two of those steps by marking the
pages as writeback from the beginning.  It can also be more precise about
which bytes in the page are dirty, reducing the number of bytes written.

This whole patchset will have to be redone on top of Christoph's recent
iomap_iter patches.  That's OK, but it's partly why I've added some
forward declarations instead of reorganising the file so they're not
needed.

Matthew Wilcox (Oracle) (8):
  iomap: Pass struct iomap to iomap_alloc_ioend()
  iomap: Remove iomap_writepage_ctx from iomap_can_add_to_ioend()
  iomap: Do not pass iomap_writepage_ctx to iomap_add_to_ioend()
  iomap: Accept a NULL iomap_writepage_ctx in iomap_submit_ioend()
  iomap: Pass iomap_write_ctx to iomap_write_actor()
  iomap: Allow a NULL writeback_control argument to iomap_alloc_ioend()
  iomap: Pass a length to iomap_add_to_ioend()
  iomap: Add writethrough for O_SYNC

 fs/iomap/buffered-io.c | 168 +++++++++++++++++++++++++++++------------
 1 file changed, 120 insertions(+), 48 deletions(-)

-- 
2.30.2