From: Ming Lei Date: Wed, 22 Oct 2014 00:30:30 +0000 (+0800) Subject: blk-merge: recaculate segment if it isn't less than max segments X-Git-Tag: v3.18-rc3~32^2~5 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=76d8137a31139f0d69ecc4177497ad6b8d4f016c;p=karo-tx-linux.git blk-merge: recaculate segment if it isn't less than max segments The problem is introduced by commit 764f612c6c3c231b(blk-merge: don't compute bi_phys_segments from bi_vcnt for cloned bio), and merge is needed if number of current segment isn't less than max segments. Strictly speaking, bio->bi_vcnt shouldn't be used here since it may not be accurate in cases of both cloned bio or bio cloned from, but bio_segments() is a bit expensive, and bi_vcnt is still the biggest number, so the approach should work. Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- diff --git a/block/blk-merge.c b/block/blk-merge.c index ba99351c0f58..b3ac40aef46b 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -99,16 +99,17 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio) { bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags); + bool merge_not_need = bio->bi_vcnt < queue_max_segments(q); if (no_sg_merge && !bio_flagged(bio, BIO_CLONED) && - bio->bi_vcnt < queue_max_segments(q)) + merge_not_need) bio->bi_phys_segments = bio->bi_vcnt; else { struct bio *nxt = bio->bi_next; bio->bi_next = NULL; bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, - no_sg_merge); + no_sg_merge && merge_not_need); bio->bi_next = nxt; }