Re: [PATCH 03/18] block: fix elevator init check

On Wed, 2017-01-25 at 18:25 +0100, Christoph Hellwig wrote:

We can't initalize the elevator fields for flushes as flush share space
in struct request with the elevator data.  But currently we can't
commnicate that a request is a flush through blk_get_request as we
can only pass READ or WRITE, and the low-level code looks at the
possible NULL bio to check for a flush.

Fix this by allowing to pass any block op and flags, and by checking for
the flush flags in __get_request.

Reviewed-by: Bart Van Assche <redacted>