block: add a blk_account_io_merge_bio helper
Move the non-"new_io" branch of blk_account_io_start() into separate
function. Fix merge accounting for discards (they were counted as write
merges).
The new blk_account_io_merge_bio() doesn't call update_io_ticks() unlike
blk_account_io_start(), as there is no reason for that.
[hch: rebased]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
4 files changed