[PATCH RFC 0/32] block: Make blkdev_get_by_*() return handle

[Jan Kara <jack@xxxxxxx>]

Hello,

this patch series implements the idea of blkdev_get_by_*() calls returning
bdev_handle which is then passed to blkdev_put() [1]. This makes the get
and put calls for bdevs more obviously matching and allows us to propagate
context from get to put without having to modify all the users (again!).
In particular I need to propagate used open flags to blkdev_put() to be able
count writeable opens and add support for blocking writes to mounted block
devices. I'll send that series separately.

The series is based on Linus' tree as of yesterday + two bcache fixes which are
in the block tree. Patches have passed some basic testing, I plan to test more
users once we agree this is the right way to go.

                                                                Honza

[1] https://lore.kernel.org/all/ZJGNsVDhZx0Xgs2H@xxxxxxxxxxxxx

CC: Alasdair Kergon <agk@xxxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Anna Schumaker <anna@xxxxxxxxxx>
CC: Chao Yu <chao@xxxxxxxxxx>
CC: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
CC: Coly Li <colyli@xxxxxxx
CC: "Darrick J. Wong" <djwong@xxxxxxxxxx>
CC: Dave Kleikamp <shaggy@xxxxxxxxxx>
CC: David Sterba <dsterba@xxxxxxxx>
CC: dm-devel@xxxxxxxxxx
CC: drbd-dev@xxxxxxxxxxxxxxxx
CC: Gao Xiang <xiang@xxxxxxxxxx>
CC: Jack Wang <jinpu.wang@xxxxxxxxx>
CC: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
CC: jfs-discussion@xxxxxxxxxxxxxxxxxxxxx
CC: Joern Engel <joern@xxxxxxxxxxxxxxx>
CC: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
CC: Kent Overstreet <kent.overstreet@xxxxxxxxx>
CC: linux-bcache@xxxxxxxxxxxxxxx
CC: linux-btrfs@xxxxxxxxxxxxxxx
CC: linux-erofs@xxxxxxxxxxxxxxxx
CC: <linux-ext4@xxxxxxxxxxxxxxx>
CC: linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
CC: linux-mm@xxxxxxxxx
CC: linux-mtd@xxxxxxxxxxxxxxxxxxx
CC: linux-nfs@xxxxxxxxxxxxxxx
CC: linux-nilfs@xxxxxxxxxxxxxxx
CC: linux-nvme@xxxxxxxxxxxxxxxxxxx
CC: linux-pm@xxxxxxxxxxxxxxx
CC: linux-raid@xxxxxxxxxxxxxxx
CC: linux-s390@xxxxxxxxxxxxxxx
CC: linux-scsi@xxxxxxxxxxxxxxx
CC: linux-xfs@xxxxxxxxxxxxxxx
CC: "Md. Haris Iqbal" <haris.iqbal@xxxxxxxxx>
CC: Mike Snitzer <snitzer@xxxxxxxxxx>
CC: Minchan Kim <minchan@xxxxxxxxxx>
CC: ocfs2-devel@xxxxxxxxxxxxxx
CC: reiserfs-devel@xxxxxxxxxxxxxxx
CC: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
CC: Song Liu <song@xxxxxxxxxx>
CC: Sven Schnelle <svens@xxxxxxxxxxxxx>
CC: target-devel@xxxxxxxxxxxxxxx
CC: Ted Tso <tytso@xxxxxxx>
CC: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
CC: xen-devel@xxxxxxxxxxxxxxxxxxxx