From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH 15/18] z2ram: dequeue in-flight request Date: Sat, 16 May 2009 23:58:27 +0400 Message-ID: <4A0F1AE3.5080105@ru.mvista.com> References: <1241751256-17435-1-git-send-email-tj@kernel.org> <1241751256-17435-16-git-send-email-tj@kernel.org> <4A0EB7A0.10107@ru.mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from h155.mvista.com ([63.81.120.155]:4164 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1756290AbZEPT6n (ORCPT ); Sat, 16 May 2009 15:58:43 -0400 In-Reply-To: <4A0EB7A0.10107@ru.mvista.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Sergei Shtylyov Cc: Tejun Heo , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, rusty@rustcorp.com.au, James.Bottomley@HansenPartnership.com, mike.miller@hp.com, donari75@gmail.com, paul.clements@steeleye.com, tim@cyberelk.net, Geert.Uytterhoeven@sonycom.com, davem@davemloft.net, Laurent@lvivier.info, jgarzik@pobox.com, jeremy@xensource.com, grant.likely@secretlab.ca, adrian@mcmen.demon.co.uk, sfr@canb.auug.org.au, bzolnier@gmail.com, petkovbb@googlemail.com, oakad@yahoo.com, drzeus@drzeus.cx, dwmw2@infradead.org, Markus.Lidel@shadowconnect.com, wein@de.ibm.com, schwidefsky@de.ibm.com, zaitcev@redhat.com, fujita.tomonori@lab.ntt.co.jp, axboe@kernel.dk Hello, I wrote: Oops, sent this message only to Tejun before, so have to repost now... >> z2ram processes requests one-by-one synchronously and can be easily >> converted to dequeueing model. Convert it. >> >> [ Impact: dequeue in-flight request ] >> >> Signed-off-by: Tejun Heo >> --- >> drivers/block/z2ram.c | 19 +++++++++++++++---- >> 1 files changed, 15 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/block/z2ram.c b/drivers/block/z2ram.c >> index 6a13838..c909c1a 100644 >> --- a/drivers/block/z2ram.c >> +++ b/drivers/block/z2ram.c >> @@ -70,15 +70,21 @@ static struct gendisk *z2ram_gendisk; >> static void do_z2_request(struct request_queue *q) >> { >> struct request *req; >> - while ((req = elv_next_request(q)) != NULL) { >> + >> + req = elv_next_request(q); >> + if (req) >> + blkdev_dequeue_request(req); >> + >> + while (req) { >> unsigned long start = blk_rq_pos(req) << 9; >> unsigned long len = blk_rq_cur_bytes(req); >> + int err = 0; >> >> if (start + len > z2ram_size) { >> printk( KERN_ERR DEVICE_NAME ": bad access: block=%lu, >> count=%u\n", >> blk_rq_pos(req), blk_rq_cur_sectors(req)); >> - __blk_end_request_cur(req, -EIO); >> - continue; >> + err = -EIO; >> + goto done; >> } >> while (len) { >> unsigned long addr = start & Z2RAM_CHUNKMASK; >> @@ -93,7 +99,12 @@ static void do_z2_request(struct request_queue *q) >> start += size; >> len -= size; >> } >> - __blk_end_request_cur(req, 0); >> + done: >> + if (!__blk_end_request_cur(req, err)) { >> + req = elv_next_request(q); >> + if (req) >> + blkdev_dequeue_request(req); >> + } >> } >> } >> > > I'm sure this can be made more compact and without duplication (in > many other cases as well): > > @@ -70,15 +70,21 @@ static struct gendisk *z2ram_gendisk; > > static void do_z2_request(struct request_queue *q) > { > struct request *req; > + > while ((req = elv_next_request(q)) != NULL) { > unsigned long start = blk_rq_pos(req) << 9; > unsigned long len = blk_rq_cur_bytes(req); Oops, missed: + int err; + > > + blkdev_dequeue_request(req); > + +again: > if (start + len > z2ram_size) { > printk( KERN_ERR DEVICE_NAME ": bad access: block=%lu, > count=%u\n", > blk_rq_pos(req), blk_rq_cur_sectors(req)); > - __blk_end_request_cur(req, -EIO); > - continue; > + err = -EIO; > + goto done; > } > while (len) { > unsigned long addr = start & Z2RAM_CHUNKMASK; > @@ -93,7 +99,12 @@ static void do_z2_request(struct request_queue *q) > start += size; > len -= size; > } > - __blk_end_request_cur(req, 0); + err = 0; > + done: > + if (__blk_end_request_cur(req, err)); > + break; Oops, should've been: + if (__blk_end_request_cur(req, err)) + goto again; > } > } It can also be: @@ -70,15 +70,21 @@ static struct gendisk *z2ram_gendisk; static void do_z2_request(struct request_queue *q) { - struct request *req; - while ((req = elv_next_request(q)) != NULL) { + while (1) { + struct request *req = elv_next_request(q); + unsigned long start, len; + int err; + + if (req == NULL) + break; + + blkdev_dequeue_request(req); + +again: + start = blk_rq_pos(req) << 9; + len = blk_rq_cur_bytes(req); if (start + len > z2ram_size) { printk( KERN_ERR DEVICE_NAME ": bad access: block=%lu, count=%u\n", blk_rq_pos(req), blk_rq_cur_sectors(req)); - __blk_end_request_cur(req, -EIO); - continue; + err = -EIO; + goto done; } while (len) { unsigned long addr = start & Z2RAM_CHUNKMASK; @@ -93,7 +99,12 @@ static void do_z2_request(struct request_queue *q) start += size; len -= size; } - __blk_end_request_cur(req, 0); + err = 0; + done: + if (__blk_end_request_cur(req, err)) + goto again; } } if you want to get rid of the assignement in the *while* statement... MBR, Sergei