improve the bio allocation interface v2

[Christoph Hellwig <hch@xxxxxx>]

Hi Jens,

this series is posted early because it has wide-ranging changes and could use 
some
early ACKs before -rc1.

It changes the interface to the bio allocators to always pass a block_device and
the operation, which is information needed for every bio submitted through
bio_submit.  This means the fields can be directly initialized in bio_init 
instead
of first being zeroed and thus should help to micro-optimize even better than 
the
__bio_set_dev that Pavel proposed while also cleaning up code.

I have a follow on series to also deal with the bio cloning interfaces that need
even more love, and additional cleanups for the callers which might be material
for the next merge window.

Changes since v1:
 - fix bio_add_page return value handling in rnbd-srv
 - fix bio clenup in rnbd-srv
 - fix a few commit message typos
 - fix a bisection hazard in rnbd
 - fix an initialization order issue in bio_alloc_bioset/bio_init

Diffstat:
 block/bio.c                         |   73 ++++++++++++++++++++++++------------
 block/blk-flush.c                   |    4 -
 block/blk-lib.c                     |   32 ++-------------
 block/blk-zoned.c                   |   14 +-----
 block/blk.h                         |    2 
 block/bounce.c                      |    6 --
 block/fops.c                        |   35 +++++++----------
 drivers/block/drbd/drbd_actlog.c    |    5 --
 drivers/block/drbd/drbd_bitmap.c    |    7 +--
 drivers/block/drbd/drbd_receiver.c  |   32 +++------------
 drivers/block/floppy.c              |    4 -
 drivers/block/pktcdvd.c             |    8 ---
 drivers/block/rnbd/rnbd-srv-dev.c   |   61 ------------------------------
 drivers/block/rnbd/rnbd-srv-dev.h   |   18 --------
 drivers/block/rnbd/rnbd-srv.c       |   45 ++++++++--------------
 drivers/block/rnbd/rnbd-srv.h       |    1 
 drivers/block/xen-blkback/blkback.c |   25 ++----------
 drivers/block/zram/zram_drv.c       |   16 ++-----
 drivers/md/bcache/io.c              |    3 -
 drivers/md/bcache/journal.c         |   16 ++-----
 drivers/md/bcache/movinggc.c        |    4 -
 drivers/md/bcache/request.c         |   18 +++-----
 drivers/md/bcache/super.c           |    8 +--
 drivers/md/bcache/writeback.c       |    4 -
 drivers/md/dm-crypt.c               |   27 ++++---------
 drivers/md/dm-io.c                  |    5 --
 drivers/md/dm-log-writes.c          |   39 +++----------------
 drivers/md/dm-snap.c                |   21 ----------
 drivers/md/dm-thin.c                |   41 +++++---------------
 drivers/md/dm-writecache.c          |    7 +--
 drivers/md/dm-zoned-metadata.c      |   26 ++----------
 drivers/md/dm.c                     |   12 ++---
 drivers/md/md-multipath.c           |    2 
 drivers/md/md.c                     |   24 +++++------
 drivers/md/raid1.c                  |    8 +--
 drivers/md/raid10.c                 |   14 ++----
 drivers/md/raid5-cache.c            |   19 +++------
 drivers/md/raid5-ppl.c              |   13 ++----
 drivers/md/raid5.c                  |   12 ++---
 drivers/nvdimm/nd_virtio.c          |    6 +-
 drivers/nvme/target/io-cmd-bdev.c   |   18 +++-----
 drivers/nvme/target/passthru.c      |    7 +--
 drivers/nvme/target/zns.c           |   14 +++---
 drivers/scsi/ufs/ufshpb.c           |    4 -
 drivers/target/target_core_iblock.c |   11 +----
 fs/btrfs/disk-io.c                  |   10 +---
 fs/btrfs/extent_io.c                |    2 
 fs/buffer.c                         |   14 ++----
 fs/crypto/bio.c                     |   13 ++----
 fs/direct-io.c                      |    5 --
 fs/erofs/zdata.c                    |    5 --
 fs/ext4/page-io.c                   |    3 -
 fs/ext4/readpage.c                  |    8 +--
 fs/f2fs/data.c                      |    7 +--
 fs/gfs2/lops.c                      |    8 +--
 fs/gfs2/meta_io.c                   |    4 -
 fs/gfs2/ops_fstype.c                |    4 -
 fs/hfsplus/wrapper.c                |    4 -
 fs/iomap/buffered-io.c              |   26 +++++-------
 fs/iomap/direct-io.c                |    8 ---
 fs/jfs/jfs_logmgr.c                 |   11 -----
 fs/jfs/jfs_metapage.c               |    9 +---
 fs/mpage.c                          |   34 ++--------------
 fs/nfs/blocklayout/blocklayout.c    |   26 +-----------
 fs/nilfs2/segbuf.c                  |   31 +--------------
 fs/ntfs3/fsntfs.c                   |   27 -------------
 fs/ocfs2/cluster/heartbeat.c        |    4 -
 fs/squashfs/block.c                 |   11 ++---
 fs/xfs/xfs_bio_io.c                 |   14 ++----
 fs/xfs/xfs_buf.c                    |    4 -
 fs/xfs/xfs_log.c                    |   14 +++---
 fs/zonefs/super.c                   |    9 +---
 include/linux/bio.h                 |   30 ++++++--------
 kernel/power/swap.c                 |    5 --
 mm/page_io.c                        |   10 +---
 75 files changed, 372 insertions(+), 759 deletions(-)