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;
> }
>
> EXPORT_SYMBOL(ide_init_drive_cmd);
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index b3a58ad..5710ae4 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -215,8 +215,9 @@ struct request {
> /*
> * when request is used as a packet command carrier
> */
> - unsigned int cmd_len;
> - unsigned char cmd[BLK_MAX_CDB];
> + unsigned short cmd_len;
> + unsigned char __cmd[BLK_MAX_CDB];
> + unsigned char *cmd;
>
> unsigned int data_len;
> unsigned int extra_len; /* length of alignment and padding */
> @@ -812,6 +813,13 @@ static inline void put_dev_sector(Sector p)
> page_cache_release(p.v);
> }
>
> +static inline void rq_set_cmd(struct request *rq, unsigned char *cmd,
> + unsigned short cmd_len)
> +{
> + rq->cmd = cmd;
> + rq->cmd_len = cmd_len;
> +}
> +
This is 100% identical to what I suggested be done instead, so of course
I agree with this.
--
Jens Axboe
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