cleanup bio_kmalloc v3

[Christoph Hellwig <hch@lst.de>]

Hi Jens,

this series finishes off the bio allocation interface cleanups by dealing
with the weirdest member of the famility.  bio_kmalloc combines a kmalloc
for the bio and bio_vecs with a hidden bio_init call and magic cleanup
semantics.

This series moves a few callers away from bio_kmalloc and then turns
bio_kmalloc into a simple wrapper for a slab allocation of a bio and the
inline biovecs.  The callers need to manually call bio_init instead with
all that entails and the magic that turns bio_put into a kfree goes away
as well, allowing for a proper debug check in bio_put that catches
accidental use on a bio_init()ed bio.

Changes since v2:
 - rebased to 5.18-rc1
 - fix bio freeing in squashfs

Changes since v1:
 - update a pre-existing comment per maintainer suggestion

Diffstat:
 block/bio.c                        |   47 ++++++++++++++-----------------------
 block/blk-crypto-fallback.c        |   14 ++++++-----
 block/blk-map.c                    |   42 +++++++++++++++++++++------------
 drivers/block/pktcdvd.c            |   34 +++++++++++---------------
 drivers/md/bcache/debug.c          |   10 ++++---
 drivers/md/dm-bufio.c              |    9 +++----
 drivers/md/raid1.c                 |   12 ++++++---
 drivers/md/raid10.c                |   21 +++++++++++-----
 drivers/target/target_core_pscsi.c |   36 ++++------------------------
 fs/btrfs/disk-io.c                 |    8 +++---
 fs/btrfs/volumes.c                 |   11 --------
 fs/btrfs/volumes.h                 |    2 -
 fs/squashfs/block.c                |   14 +++--------
 include/linux/bio.h                |    2 -
 14 files changed, 116 insertions(+), 146 deletions(-)