From mboxrd@z Thu Jan 1 00:00:00 1970 From: FUJITA Tomonori Subject: Re: [PATCH 4/4] block: add large command support Date: Thu, 17 Apr 2008 12:59:32 +0900 Message-ID: <20080417123218V.tomof@acm.org> References: <20080416075743R.fujita.tomonori@lab.ntt.co.jp> <20080416083305.GY12774@kernel.dk> <4805C209.6040606@panasas.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4805C209.6040606@panasas.com> Sender: linux-scsi-owner@vger.kernel.org To: bharrosh@panasas.com Cc: jens.axboe@oracle.com, fujita.tomonori@lab.ntt.co.jp, bzolnier@gmail.com, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, akpm@linux-foundation.org List-Id: linux-ide@vger.kernel.org On Wed, 16 Apr 2008 12:08:25 +0300 Boaz Harrosh wrote: > On Wed, Apr 16 2008 at 11:33 +0300, Jens Axboe wrote: > > On Wed, Apr 16 2008, FUJITA Tomonori wrote: > >> On Wed, 16 Apr 2008 00:50:54 +0200 > >> Bartlomiej Zolnierkiewicz wrote: > >> > >>> Hi, > >>> > >>> On Monday 14 April 2008, Jens Axboe wrote: > >>>> On Mon, Apr 14 2008, FUJITA Tomonori wrote: > >>>>> This patch changes rq->cmd from the static array to a pointer to > >>>>> support large commands. > >>>>> > >>>>> We rarely handle large commands. So for optimization, a struct request > >>>>> still has a static array for a command. rq_init sets rq->cmd pointer > >>>>> to the static array. > >>>>> > >>>>> Signed-off-by: FUJITA Tomonori > >>>>> Cc: Jens Axboe > >>>>> --- > >>>>> block/blk-core.c | 1 + > >>>>> drivers/ide/ide-io.c | 1 + > >>>>> include/linux/blkdev.h | 12 ++++++++++-- > >>>>> 3 files changed, 12 insertions(+), 2 deletions(-) > >>>>> > >>>>> diff --git a/block/blk-core.c b/block/blk-core.c > >>>>> index 6669238..6f0968f 100644 > >>>>> --- a/block/blk-core.c > >>>>> +++ b/block/blk-core.c > >>>>> @@ -132,6 +132,7 @@ void rq_init(struct request_queue *q, struct request *rq) > >>>>> rq->errors = 0; > >>>>> rq->ref_count = 1; > >>>>> rq->cmd_len = 0; > >>>>> + rq->cmd = rq->__cmd; > >>>>> memset(rq->cmd, 0, BLK_MAX_CDB); > >>>>> rq->data_len = 0; > >>>>> rq->extra_len = 0; > >>>>> diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c > >>>>> index 7153796..bac5ea1 100644 > >>>>> --- a/drivers/ide/ide-io.c > >>>>> +++ b/drivers/ide/ide-io.c > >>>>> @@ -1595,6 +1595,7 @@ void ide_init_drive_cmd (struct request *rq) > >>>>> { > >>>>> memset(rq, 0, sizeof(*rq)); > >>>>> rq->ref_count = 1; > >>>>> + rq->cmd = rq->__cmd; > >>>>> } > >>> Tomo, some more changes are needed: > >>> > >>> Please think about all _static_/dynamic allocations of 'struct request' > >>> used together with REQ_TYPE_SPECIAL etc., i.e. > >> I think that using struct request allocated statically is wrong from > >> the perspective of the block layer design, that is, you always need to > >> use blk_get_request. I think that except ide, everyone does. > >> > >> I try to convert ide to use blk_get_request properly if you want. > > > > That would be best, but the on-stack allocation has the benefit that > > it'll always work. So until we can completely get rid of that, lets just > > make it a hard rule that ANY rq allocation MUST call rq_init(). It's a > > lot saner than doing a memset() anyway. > > > > Just a patch that I had for ages since the bad old request bidi times, > perhaps is also good today. (rebased to for-2.6.26 branch) > --- > From: Boaz Harrosh > Date: Wed, 16 Apr 2008 12:05:33 +0300 > Subject: [PATCH] Initialize all members of struct request in rq_init > > Before, every member added/removed from struct request would entitle a change > to rq_init, for initialization. Now all members are default to zero and only > the none zero members are specifically initialized. > > Users that need requests on the stack or pre-allocated, must call rq_init() > before use. > > Signed-off-by: Boaz Harrosh > --- > block/blk-core.c | 22 ++-------------------- > 1 files changed, 2 insertions(+), 20 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index 6f0968f..3f4c563 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -113,36 +113,18 @@ EXPORT_SYMBOL(blk_get_backing_dev_info); > */ > void rq_init(struct request_queue *q, struct request *rq) > { > + memset(rq, 0, sizeof(*rq)); Hmm, rq_init comment says: /* * We can't just memset() the structure, since the allocation path * already stored some information in the request. */ I think that we can't initialize rq->cmd_flags here. > INIT_LIST_HEAD(&rq->queuelist); > INIT_LIST_HEAD(&rq->donelist); > rq->q = q; > rq->sector = rq->hard_sector = (sector_t) -1; > - rq->nr_sectors = rq->hard_nr_sectors = 0; > - rq->current_nr_sectors = rq->hard_cur_sectors = 0; > - rq->bio = rq->biotail = NULL; > INIT_HLIST_NODE(&rq->hash); > RB_CLEAR_NODE(&rq->rb_node); > - rq->rq_disk = NULL; > - rq->nr_phys_segments = 0; > - rq->nr_hw_segments = 0; > - rq->ioprio = 0; > - rq->special = NULL; > - rq->buffer = NULL; > rq->tag = -1; > - rq->errors = 0; > rq->ref_count = 1; > - rq->cmd_len = 0; > rq->cmd = rq->__cmd; > - memset(rq->cmd, 0, BLK_MAX_CDB); > - rq->data_len = 0; > - rq->extra_len = 0; > - rq->sense_len = 0; > - rq->data = NULL; > - rq->sense = NULL; > - rq->end_io = NULL; > - rq->end_io_data = NULL; > - rq->next_rq = NULL; > } > +EXPORT_SYMBOL(rq_init); > > static void req_bio_endio(struct request *rq, struct bio *bio, > unsigned int nbytes, int error) > -- > 1.5.3.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html