[PATCH 00/10] MM changes to improve swap-over-NFS support

[NeilBrown <neilb@suse.de>]

Assorted improvements for swap-via-filesystem.

This is a resend of these patches, rebased on current HEAD.
The only substantial changes is that swap_dirty_folio has replaced
swap_set_page_dirty.

Currently swap-via-fs (SWP_FS_OPS) doesn't work for any filesystem.  It
has previously worked for NFS but that broke a few releases back.
This series changes to use a new ->swap_rw rather than ->readpage and
->direct_IO.  It also makes other improvements.

There is a companion series already in linux-next which fixes various
issues with NFS.  Once both series land, a final patch is needed which
changes NFS over to use ->swap_rw.

Thanks,
NeilBrown


---

NeilBrown (10):
      MM: create new mm/swap.h header file.
      MM: drop swap_dirty_folio
      MM: move responsibility for setting SWP_FS_OPS to ->swap_activate
      MM: reclaim mustn't enter FS for SWP_FS_OPS swap-space
      MM: introduce ->swap_rw and use it for reads from SWP_FS_OPS swap-space
      MM: perform async writes to SWP_FS_OPS swap-space using ->swap_rw
      DOC: update documentation for swap_activate and swap_rw
      MM: submit multipage reads for SWP_FS_OPS swap-space
      MM: submit multipage write for SWP_FS_OPS swap-space
      VFS: Add FMODE_CAN_ODIRECT file flag


 Documentation/filesystems/locking.rst |  18 +-
 Documentation/filesystems/vfs.rst     |  17 +-
 drivers/block/loop.c                  |   4 +-
 fs/cifs/file.c                        |   7 +-
 fs/fcntl.c                            |   9 +-
 fs/nfs/file.c                         |  20 ++-
 fs/open.c                             |   9 +-
 fs/overlayfs/file.c                   |  13 +-
 include/linux/fs.h                    |   4 +
 include/linux/swap.h                  |   7 +-
 include/linux/writeback.h             |   7 +
 mm/madvise.c                          |   8 +-
 mm/memory.c                           |   2 +-
 mm/page_io.c                          | 247 +++++++++++++++++++-------
 mm/swap.h                             |  30 +++-
 mm/swap_state.c                       |  22 ++-
 mm/swapfile.c                         |  13 +-
 mm/vmscan.c                           |  38 ++--
 18 files changed, 347 insertions(+), 128 deletions(-)

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