From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757171Ab2BGXB7 (ORCPT ); Tue, 7 Feb 2012 18:01:59 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:64079 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756586Ab2BGXB6 (ORCPT ); Tue, 7 Feb 2012 18:01:58 -0500 Date: Tue, 7 Feb 2012 15:01:53 -0800 From: Tejun Heo To: Jens Axboe , Shaohua Li , Vivek Goyal Cc: linux-kernel@vger.kernel.org Subject: [PATCH block/for-linus 1/2] block: separate out blk_rq_merge_ok() and blk_try_merge() from elevator functions Message-ID: <20120207230153.GK21292@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org blk_rq_merge_ok() is the elevator-neutral part of merge eligibility test. blk_try_merge() determines merge direction and expects the caller to have tested elv_rq_merge_ok() previously. elv_rq_merge_ok() now wraps blk_rq_merge_ok() and then calls elv_iosched_allow_merge(). elv_try_merge() is removed and the two callers are updated to call elv_rq_merge_ok() explicitly followed by blk_try_merge(). While at it, make rq_merge_ok() functions return bool. This is to prepare for plug merge update and doesn't introduce any behavior change. This is based on Jens' patch to skip elevator_allow_merge_fn() from plug merge. Signed-off-by: Tejun Heo LKML-Reference: <4F16F3CA.90904@kernel.dk> Original-patch-by: Jens Axboe --- Jens, these two patches fix the easy-to-trigger oops on elevator switch bug. These are based on your previous patch. Thanks. block/blk-core.c | 4 +-- block/blk-merge.c | 37 +++++++++++++++++++++++++++++++ block/blk.h | 2 + block/elevator.c | 55 +++-------------------------------------------- include/linux/elevator.h | 3 -- 5 files changed, 46 insertions(+), 55 deletions(-) Index: work/block/blk-merge.c =================================================================== --- work.orig/block/blk-merge.c +++ work/block/blk-merge.c @@ -471,3 +471,40 @@ int blk_attempt_req_merge(struct request { return attempt_merge(q, rq, next); } + +bool blk_rq_merge_ok(struct request *rq, struct bio *bio) +{ + if (!rq_mergeable(rq)) + return false; + + /* don't merge file system requests and discard requests */ + if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD)) + return false; + + /* don't merge discard requests and secure discard requests */ + if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE)) + return false; + + /* different data direction or already started, don't merge */ + if (bio_data_dir(bio) != rq_data_dir(rq)) + return false; + + /* must be same device and not a special request */ + if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) + return false; + + /* only merge integrity protected bio into ditto rq */ + if (bio_integrity(bio) != blk_integrity_rq(rq)) + return false; + + return true; +} + +int blk_try_merge(struct request *rq, struct bio *bio) +{ + if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_sector) + return ELEVATOR_BACK_MERGE; + else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_sector) + return ELEVATOR_FRONT_MERGE; + return ELEVATOR_NO_MERGE; +} Index: work/block/blk.h =================================================================== --- work.orig/block/blk.h +++ work/block/blk.h @@ -137,6 +137,8 @@ int blk_attempt_req_merge(struct request struct request *next); void blk_recalc_rq_segments(struct request *rq); void blk_rq_set_mixed_merge(struct request *rq); +bool blk_rq_merge_ok(struct request *rq, struct bio *bio); +int blk_try_merge(struct request *rq, struct bio *bio); void blk_queue_congestion_threshold(struct request_queue *q); Index: work/block/elevator.c =================================================================== --- work.orig/block/elevator.c +++ work/block/elevator.c @@ -70,39 +70,9 @@ static int elv_iosched_allow_merge(struc /* * can we safely merge with this request? */ -int elv_rq_merge_ok(struct request *rq, struct bio *bio) +bool elv_rq_merge_ok(struct request *rq, struct bio *bio) { - if (!rq_mergeable(rq)) - return 0; - - /* - * Don't merge file system requests and discard requests - */ - if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD)) - return 0; - - /* - * Don't merge discard requests and secure discard requests - */ - if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE)) - return 0; - - /* - * different data direction or already started, don't merge - */ - if (bio_data_dir(bio) != rq_data_dir(rq)) - return 0; - - /* - * must be same device and not a special request - */ - if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) - return 0; - - /* - * only merge integrity protected bio into ditto rq - */ - if (bio_integrity(bio) != blk_integrity_rq(rq)) + if (!blk_rq_merge_ok(rq, bio)) return 0; if (!elv_iosched_allow_merge(rq, bio)) @@ -112,23 +82,6 @@ int elv_rq_merge_ok(struct request *rq, } EXPORT_SYMBOL(elv_rq_merge_ok); -int elv_try_merge(struct request *__rq, struct bio *bio) -{ - int ret = ELEVATOR_NO_MERGE; - - /* - * we can merge and sequence is ok, check if it's possible - */ - if (elv_rq_merge_ok(__rq, bio)) { - if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) - ret = ELEVATOR_BACK_MERGE; - else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) - ret = ELEVATOR_FRONT_MERGE; - } - - return ret; -} - static struct elevator_type *elevator_find(const char *name) { struct elevator_type *e; @@ -478,8 +431,8 @@ int elv_merge(struct request_queue *q, s /* * First try one-hit cache. */ - if (q->last_merge) { - ret = elv_try_merge(q->last_merge, bio); + if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { + ret = blk_try_merge(q->last_merge, bio); if (ret != ELEVATOR_NO_MERGE) { *req = q->last_merge; return ret; Index: work/include/linux/elevator.h =================================================================== --- work.orig/include/linux/elevator.h +++ work/include/linux/elevator.h @@ -122,7 +122,6 @@ extern void elv_dispatch_add_tail(struct extern void elv_add_request(struct request_queue *, struct request *, int); extern void __elv_add_request(struct request_queue *, struct request *, int); extern int elv_merge(struct request_queue *, struct request **, struct bio *); -extern int elv_try_merge(struct request *, struct bio *); extern void elv_merge_requests(struct request_queue *, struct request *, struct request *); extern void elv_merged_request(struct request_queue *, struct request *, int); @@ -155,7 +154,7 @@ extern ssize_t elv_iosched_store(struct extern int elevator_init(struct request_queue *, char *); extern void elevator_exit(struct elevator_queue *); extern int elevator_change(struct request_queue *, const char *); -extern int elv_rq_merge_ok(struct request *, struct bio *); +extern bool elv_rq_merge_ok(struct request *, struct bio *); /* * Helper functions. Index: work/block/blk-core.c =================================================================== --- work.orig/block/blk-core.c +++ work/block/blk-core.c @@ -1282,10 +1282,10 @@ static bool attempt_plug_merge(struct re (*request_count)++; - if (rq->q != q) + if (rq->q != q || !elv_rq_merge_ok(rq, bio)) continue; - el_ret = elv_try_merge(rq, bio); + el_ret = blk_try_merge(rq, bio); if (el_ret == ELEVATOR_BACK_MERGE) { ret = bio_attempt_back_merge(q, rq, bio); if (ret)