On Sun, 30 Nov 2008, FUJITA Tomonori wrote:
> This patchset removes the majority of scsi_execute_async in st
> driver. IOW, this converts st driver to use the block layer functions.
>
> We are in the process of removing scsi_execute_async and
> scsi_req_map_sg. scsi_execute_async in sg driver were removed in
> 2.6.27. Now only st and osst drivers use scsi_execute_async().
>
> st driver uses scsi_execute_async for two purposes, performing sort
> management SCSI commands internally and data transfer between user and
> kernel space (st_read and st_write). This patchset converts the
> former.
>
> The former performs SCSI commands synchronously. It uses a liner
> in-kernel buffer (not scatter gather) for data transfer. To perform
> such commands, other upper layer drivers (e.g. sd) use
> scsi_execute_req (internally uses blk_rq_map_kern and and
> blk_execute_rq). scsi_execute_req is not fully fit for st so I adds a
> helper function similar to scsi_execute_req and replace
> scsi_execute_async in st driver (I might modify scsi_execute_req for
> st and remove the helper function later).
>
> I'm still working on converting scsi_execute_async for data transfer
> between user and kernel space but I want to get this first half be
> merged.
>
I have looked at the patches but it is a little difficult to say much
without seeing the other half. I think there should be only one function
in st to handle scsi. If you extend st_scsi_kern_execute to handle also
read and write (as you later indicate you may do) I think that is a good
direction.
I tested the patches in 2.6.28-rc7 and noticed a couple of problems. The
patches do not convert st_int_ioctl. I added simple conversion (at the end
of this message) but after this, the driver did not pass my simple tests.
Looking at st_scsi_kern_execute(), it seems that it does not copy the
sense data to struct st_request.
Thanks,
Kai
--- linux-t1/drivers/scsi/st.c.org 2008-12-02 20:14:11.000000000 +0200
+++ linux-t1/drivers/scsi/st.c 2008-12-02 20:34:49.000000000 +0200
@@ -2872,12 +2872,14 @@ static int st_int_ioctl(struct scsi_tape
return (-ENOSYS);
}
- SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
- timeout, MAX_RETRIES, 1);
+
+ SRpnt = st_allocate_request(STp);
if (!SRpnt)
- return (STp->buffer)->syscall_result;
+ return STp->buffer->syscall_result;
- ioctl_result = (STp->buffer)->syscall_result;
+ ioctl_result = st_scsi_kern_execute(SRpnt, cmd, direction,
+ STp->buffer->b_data, datalen,
+ timeout, MAX_RETRIES);
if (!ioctl_result) { /* SCSI command successful */
st_release_request(SRpnt);
--
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