Commit fbbf0556 authored Jun 17, 2010 by Christoph Hellwig Committed by Jens Axboe Jun 17, 2010

block: fix DISCARD_BARRIER requests



Filesystems assume that DISCARD_BARRIER are full barriers, so that they
don't have to track in-progress discard operation when submitting new I/O.
But currently we only treat them as elevator barriers, which don't
actually do the nessecary queue drains.

Also remove the unlikely around both the DISCARD and BARRIER requests -
the happen far too often for a static mispredict.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

parent 79600aad

block/blk-core.c

+2 −5

Original line number	Diff line number	Diff line
		@@ -1149,13 +1149,10 @@ void init_request_from_bio(struct request req, struct bio bio)
		else
		req->cmd_flags \|= bio->bi_rw & REQ_FAILFAST_MASK;

		if (unlikely(bio_rw_flagged(bio, BIO_RW_DISCARD))) {
		if (bio_rw_flagged(bio, BIO_RW_DISCARD))
		req->cmd_flags \|= REQ_DISCARD;
		if (bio_rw_flagged(bio, BIO_RW_BARRIER))
		req->cmd_flags \|= REQ_SOFTBARRIER;
		} else if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER)))
		req->cmd_flags \|= REQ_HARDBARRIER;

		if (bio_rw_flagged(bio, BIO_RW_SYNCIO))
		req->cmd_flags \|= REQ_RW_SYNC;
		if (bio_rw_flagged(bio, BIO_RW_META))