Re: [block] allow blk_flush_policy to return REQ_FSEQ_DATA independent of *FLUSH

From: Jens Axboe
Date: Tue Aug 09 2011 - 14:29:37 EST


On 2011-08-09 17:24, Jeff Moyer wrote:
> Hi,
>
> blk_insert_flush has the following check:
>
> /*
> * If there's data but flush is not necessary, the request can be
> * processed directly without going through flush machinery. Queue
> * for normal execution.
> */
> if ((policy & REQ_FSEQ_DATA) &&
> !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
> list_add_tail(&rq->queuelist, &q->queue_head);
> return;
> }
>
> However, blk_flush_policy will not return with policy set to only
> REQ_FSEQ_DATA:
>
> static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq)
> {
> unsigned int policy = 0;
>
> if (fflags & REQ_FLUSH) {
> if (rq->cmd_flags & REQ_FLUSH)
> policy |= REQ_FSEQ_PREFLUSH;
> if (blk_rq_sectors(rq))
> policy |= REQ_FSEQ_DATA;
> if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA))
> policy |= REQ_FSEQ_POSTFLUSH;
> }
> return policy;
> }
>
> Notice that REQ_FSEQ_DATA is only set if REQ_FLUSH is set. Fix this
> mismatch by moving the setting of REQ_FSEQ_DATA outside of the REQ_FLUSH
> check.

Thanks Jeff, applied.

--
Jens Axboe

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