block: respect virtual boundary mask in bvecs

With drivers that are settting a virtual boundary constrain, we are
seeing a lot of bio splitting and smaller I/Os being submitted to the
driver.

This happens because the bio gap detection code does not account cases
where PAGE_SIZE - 1 is bigger than queue_virt_boundary() and thus will
split the bio unnecessarily.

Cc: Jan Kara <jack@suse.cz>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 6b5ad275ed565de274746b1ef473f46a3a20a621..208658a901c65ea1920726701846f1b54dd94c3e 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -46,7 +46,7 @@ static inline bool bio_will_gap(struct request_queue *q,
                bio_get_first_bvec(prev_rq->bio, &pb);
        else
                bio_get_first_bvec(prev, &pb);
-       if (pb.bv_offset)
+       if (pb.bv_offset & queue_virt_boundary(q))
                return true;
 
        /*

diff --git a/block/blk.h b/block/blk.h
index a1841b8ff12963a883047780762229f923989f01..c85e53f21cdd86fa3fee4867dfcc807b1eba0b9e 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -169,7 +169,7 @@ static inline bool biovec_phys_mergeable(struct request_queue *q,
 static inline bool __bvec_gap_to_prev(struct request_queue *q,
                struct bio_vec *bprv, unsigned int offset)
 {
-       return offset ||
+       return (offset & queue_virt_boundary(q)) ||
                ((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q));
 }