Messages in this thread | | | Date | Mon, 19 Nov 2018 17:20:41 +0800 | From | Ming Lei <> | Subject | Re: [PATCH V10 18/19] block: kill QUEUE_FLAG_NO_SG_MERGE |
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On Fri, Nov 16, 2018 at 02:58:03PM +0100, Christoph Hellwig wrote: > On Thu, Nov 15, 2018 at 04:53:05PM +0800, Ming Lei wrote: > > Since bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"), > > physical segment number is mainly figured out in blk_queue_split() for > > fast path, and the flag of BIO_SEG_VALID is set there too. > > > > Now only blk_recount_segments() and blk_recalc_rq_segments() use this > > flag. > > > > Basically blk_recount_segments() is bypassed in fast path given BIO_SEG_VALID > > is set in blk_queue_split(). > > > > For another user of blk_recalc_rq_segments(): > > > > - run in partial completion branch of blk_update_request, which is an unusual case > > > > - run in blk_cloned_rq_check_limits(), still not a big problem if the flag is killed > > since dm-rq is the only user. > > > > Multi-page bvec is enabled now, QUEUE_FLAG_NO_SG_MERGE doesn't make sense any more. > > > > Cc: Dave Chinner <dchinner@redhat.com> > > Cc: Kent Overstreet <kent.overstreet@gmail.com> > > Cc: Mike Snitzer <snitzer@redhat.com> > > Cc: dm-devel@redhat.com > > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > > Cc: linux-fsdevel@vger.kernel.org > > Cc: Shaohua Li <shli@kernel.org> > > Cc: linux-raid@vger.kernel.org > > Cc: linux-erofs@lists.ozlabs.org > > Cc: David Sterba <dsterba@suse.com> > > Cc: linux-btrfs@vger.kernel.org > > Cc: Darrick J. Wong <darrick.wong@oracle.com> > > Cc: linux-xfs@vger.kernel.org > > Cc: Gao Xiang <gaoxiang25@huawei.com> > > Cc: Christoph Hellwig <hch@lst.de> > > Cc: Theodore Ts'o <tytso@mit.edu> > > Cc: linux-ext4@vger.kernel.org > > Cc: Coly Li <colyli@suse.de> > > Cc: linux-bcache@vger.kernel.org > > Cc: Boaz Harrosh <ooo@electrozaur.com> > > Cc: Bob Peterson <rpeterso@redhat.com> > > Cc: cluster-devel@redhat.com > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > --- > > block/blk-merge.c | 31 ++++++------------------------- > > block/blk-mq-debugfs.c | 1 - > > block/blk-mq.c | 3 --- > > drivers/md/dm-table.c | 13 ------------- > > include/linux/blkdev.h | 1 - > > 5 files changed, 6 insertions(+), 43 deletions(-) > > > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index 153a659fde74..06be298be332 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -351,8 +351,7 @@ void blk_queue_split(struct request_queue *q, struct bio **bio) > > EXPORT_SYMBOL(blk_queue_split); > > > > static unsigned int __blk_recalc_rq_segments(struct request_queue *q, > > - struct bio *bio, > > - bool no_sg_merge) > > + struct bio *bio) > > { > > struct bio_vec bv, bvprv = { NULL }; > > int cluster, prev = 0; > > @@ -379,13 +378,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, > > nr_phys_segs = 0; > > for_each_bio(bio) { > > bio_for_each_bvec(bv, bio, iter) { > > - /* > > - * If SG merging is disabled, each bio vector is > > - * a segment > > - */ > > - if (no_sg_merge) > > - goto new_segment; > > - > > if (prev && cluster) { > > if (seg_size + bv.bv_len > > > queue_max_segment_size(q)) > > @@ -420,27 +412,16 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, > > > > void blk_recalc_rq_segments(struct request *rq) > > { > > - bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, > > - &rq->q->queue_flags); > > - > > - rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, > > - no_sg_merge); > > + rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); > > Can we rename __blk_recalc_rq_segments to blk_recalc_rq_segments > can kill the old blk_recalc_rq_segments now?
Sure.
Thanks, Ming
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