On Wed, Apr 16 2008, FUJITA Tomonori wrote:
> On Wed, 16 Apr 2008 00:50:54 +0200
> Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx> 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 <fujita.tomonori@xxxxxxxxxxxxx>
> > > > Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
> > > > ---
> > > > 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.
--
Jens Axboe
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
