From ad2eb37f6c1ea6bf28dc1ad560b25f92f78bd093 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 16 Jul 2009 15:26:55 +0900 Subject: [PATCH] block: fix failfast merge testing in elv_rq_merge_ok() Commit 5dfc8c8fb7546d8e302ce12711ca18f0eed81dff tries to prevent merge of requests with different failfast settings. In elv_rq_merge_ok(), it compares new bio's failfast flags against the merge target request's. However, the flag testing accessors for bio and blk don't return boolean but the tested bit value directly and FAILFAST on bio and blk don't match, so directly comparing them with == results in false negative unnecessary preventing merge of readahead requests. This patch convert the results to boolean by negating them before comparison. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Boaz Harrosh Cc: FUJITA Tomonori Cc: James Bottomley Cc: Jeff Garzik --- block/elevator.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index 6f2375339a996..2d511f9105e16 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -101,11 +101,16 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio) return 0; /* - * Don't merge if failfast settings don't match + * Don't merge if failfast settings don't match. + * + * FIXME: The negation in front of each condition is necessary + * because bio and request flags use different bit positions + * and the accessors return those bits directly. This + * ugliness will soon go away. */ - if (bio_failfast_dev(bio) != blk_failfast_dev(rq) || - bio_failfast_transport(bio) != blk_failfast_transport(rq) || - bio_failfast_driver(bio) != blk_failfast_driver(rq)) + if (!bio_failfast_dev(bio) != !blk_failfast_dev(rq) || + !bio_failfast_transport(bio) != !blk_failfast_transport(rq) || + !bio_failfast_driver(bio) != !blk_failfast_driver(rq)) return 0; if (!elv_iosched_allow_merge(rq, bio)) -- 2.39.5