block: support delayed holder registration

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device mapper needs to register holders before it is ready to do I/O.
Currently it does so by registering the disk early, which can leave
the disk and queue in a weird half state where the queue is registered
with the disk, except for sysfs and the elevator.  And this state has
been a bit promlematic before, and will get more so when sorting out
the responsibilities between the queue and the disk.

Support registering holders on an initialized but not registered disk
instead by delaying the sysfs registration until the disk is registered.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Christoph Hellwig 2021-08-04 11:41:43 +02:00 • committed by Jens Axboe

parent 0dbcfe247f

commit d626338735

3 changed files with 66 additions and 17 deletions

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10

block/genhd.c

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68

block/holder.c

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5

include/linux/genhd.h

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