blk-mq: split out a __blk_mq_get_driver_tag helper

Allocation of the driver tag in the case of using a scheduler shares very
little code with the "normal" tag allocation.  Split out a new helper to
streamline this path, and untangle it from the complex normal tag
allocation.

This way also avoids to fail driver tag allocation because of inactive hctx
during cpu hotplug, and fixes potential hang risk.

Fixes: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline")
Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Tested-by: John Garry <[email protected]>
Cc: Dongli Zhang <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Daniel Wagner <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions