[PATCH v2 0/6] Page I/O

[Matthew Wilcox]

Page I/O allows us to read/write pages to storage without allocating any
memory (in particular, it avoids allocating a BIO).  This is nice for
the purposes of swap and reduces overhead for fast storage devices.  The
downside is that it removes all batching from the I/O path, potentially
sending dozens of commands for a large I/O instead of just one.

This iteration of the Page I/O patchset has been tested with xfstests
on ext4 on brd, and there are no unexpected failures.

Changes since v1:

 - Rebased to 3.14-rc7
 - Separate out the clean_buffers() refactoring into its own patch
 - Change the page_endio() interface to take an error code rather than
   a boolean 'success'.  All of its callers prefer this (and my earlier
   patchset got this wrong in one caller).
 - Added kerneldoc to bdev_read_page() and bdev_write_page()
 - bdev_write_page() now does less on failure.  Since its two customers
   (swap and mpage) want to do different things to the page flags on
   failure, let them.
 - Drop the virtio_blk patch, since I don't think it should be included

Keith Busch (1):
  NVMe: Add support for rw_page

Matthew Wilcox (5):
  Factor clean_buffers() out of __mpage_writepage()
  Factor page_endio() out of mpage_end_io()
  Add bdev_read_page() and bdev_write_page()
  swap: Use bdev_read_page() / bdev_write_page()
  brd: Add support for rw_page

 drivers/block/brd.c       |  10 ++++
 drivers/block/nvme-core.c | 129 +++++++++++++++++++++++++++++++++++++---------
 fs/block_dev.c            |  63 ++++++++++++++++++++++
 fs/mpage.c                |  84 +++++++++++++++---------------
 include/linux/blkdev.h    |   4 ++
 include/linux/pagemap.h   |   2 +
 mm/filemap.c              |  25 +++++++++
 mm/page_io.c              |  23 ++++++++-
 8 files changed, 273 insertions(+), 67 deletions(-)

-- 
1.9.0

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