On Wed, 2010-06-02 at 16:33 +0900, FUJITA Tomonori wrote:
> This fixes scsi_get_lba() helper function for PC commands.
>
> Only the block layer is supposed to touch rq->__sector. We could
> create a new accessor for it. But it seems overdoing a bit? Jens?
>
> =
> From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> Subject: [PATCH] scsi: fix scsi_get_lba helper function for pc command
>
> scsi_get_lba() can be used to get the lba info from
> scsi_cmnd. scsi_get_lba() gets the lba info from rq->__sector so
> scsi_get_lba() returns a bogus value for PC commands (we don't use
> rq->__sector for PC commands).
>
> This patch sets rq->__sector in scsi_setup_blk_pc_cmnd() so that
> scsi_get_lba() works with PC commands.
>
> scsi_get_data_transfer_info() is taken from
> scsi_debug. scsi_get_data_transfer_info() looks useful for some
> (scsi_debug, scsi_trace, libata, etc). So I export it. I'll convert
> them to use scsi_get_data_transfer_info().
>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> ---
> drivers/scsi/scsi_lib.c | 54 +++++++++++++++++++++++++++++++++++++++++++++-
> include/scsi/scsi_cmnd.h | 4 +++
> 2 files changed, 57 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 1646fe7..b9b7f40 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -19,6 +19,7 @@
> #include <linux/delay.h>
> #include <linux/hardirq.h>
> #include <linux/scatterlist.h>
> +#include <asm/unaligned.h>
>
> #include <scsi/scsi.h>
> #include <scsi/scsi_cmnd.h>
> @@ -69,6 +70,52 @@ struct kmem_cache *scsi_sdb_cache;
>
> static void scsi_run_queue(struct request_queue *q);
>
> +int scsi_get_data_transfer_info(unsigned char *cmd, unsigned long long *lba,
> + unsigned int *num, unsigned int *ei_lba)
> +{
> + int ret = 0;
> +
> + switch (*cmd) {
> + case VARIABLE_LENGTH_CMD:
> + *lba = get_unaligned_be64(&cmd[12]);
> + *num = get_unaligned_be32(&cmd[28]);
> + *ei_lba = get_unaligned_be32(&cmd[20]);
> + break;
You can't do this ... unless you know the format of the command. For
instance, if you knew this was a 32 byte CDB, then SPC does define where
the LBA is.
> + case WRITE_16:
> + case READ_16:
> + case VERIFY_16:
> + case WRITE_SAME_16:
> + *lba = get_unaligned_be64(&cmd[2]);
> + *num = get_unaligned_be32(&cmd[10]);
> + break;
> + case WRITE_12:
> + case READ_12:
> + case VERIFY_12:
> + *lba = get_unaligned_be32(&cmd[2]);
> + *num = get_unaligned_be32(&cmd[6]);
> + break;
> + case WRITE_10:
> + case READ_10:
> + case XDWRITEREAD_10:
> + case VERIFY:
> + case WRITE_SAME:
> + *lba = get_unaligned_be32(&cmd[2]);
> + *num = get_unaligned_be16(&cmd[7]);
> + break;
> + case WRITE_6:
> + case READ_6:
> + *lba = (u32)cmd[3] | (u32)cmd[2] << 8 |
> + (u32)(cmd[1] & 0x1f) << 16;
> + *num = (0 == cmd[4]) ? 256 : cmd[4];
> + break;
I really wouldn't do it like this because there are going to be
unexpected gaps. What about using the CDB groups instead? Each CDB
group has a well defined location for the LBA. The only problem is the
16 byte commands group because they have two forms: ordinary and long
LBA.
James
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