[stgt] [PATCH] Handle ILI bit via sg backing store

[Mark Harvey]

On 14/04/11 18:54, FUJITA Tomonori wrote:
> Sorry for the delay,
>
> On Fri, 8 Apr 2011 21:43:12 -0700
> Mark Harvey<mark_harvey at symantec.com>  wrote:
>
>> Apologies for the attachment.. Outlook just does its own thing no matter what I want.
>>
>> Basically same patch as before, but replaced Illegal with Invalid.
> Should be 'incorrect length indicator'?
>
I'll double-check the SSC3 spec.
>> Cheers
>> Mark
>>
>>
>> $ git diff
>> diff --git a/usr/bs_sg.c b/usr/bs_sg.c
>> index 69cce9b..a1be14b 100644
>> --- a/usr/bs_sg.c
>> +++ b/usr/bs_sg.c
>> @@ -247,6 +247,7 @@ static void bs_sg_cmd_complete(int fd, int events, void *dat
>>          struct sg_io_hdr io_hdr;
>>          struct scsi_cmd *cmd;
>>          int err;
>> +       unsigned resid;
>>
>>          memset(&io_hdr, 0, sizeof(io_hdr));
>>          io_hdr.interface_id = 'S';
>> @@ -261,9 +262,15 @@ static void bs_sg_cmd_complete(int fd, int events, void *da
>>                  scsi_set_out_resid(cmd, io_hdr.resid);
>>                  scsi_set_in_resid(cmd, io_hdr.resid);
>>          } else {
>> +               /* NO SENSE | ILI (Invalid Length Indicator) set */
>> +               if (io_hdr.sbp[2] == 0x20)
>> +                       resid = io_hdr.dxfer_len - io_hdr.resid;
>> +               else
>> +                       resid = 0;
>> +
>>                  cmd->sense_len = io_hdr.sb_len_wr;
>> -               scsi_set_out_resid_by_actual(cmd, 0);
>> -               scsi_set_in_resid_by_actual(cmd, 0);
>> +               scsi_set_out_resid_by_actual(cmd, resid);
>> +               scsi_set_in_resid_by_actual(cmd, resid);
> This should be
>
> scsi_set_in_resid_by_actual(cmd, io_hdr.resid);
> scsi_set_in_resid_by_actual(cmd, io_hdr.resid);
>
> ?
>
> I thought that sg sets a proper resid value to io_hdr.resid. No?
>
My testing reported 'resid' as the residual that was not returned.
i.e. a "dd if=/dev/nst0 of=/tmp/b1 bs=64k count=1" when reading a 1k 
block will have 63k in 'resid'.

It's the 1k of valid data that needs to be returned to the application 
(NetBackup in this instance).

I did have a though this morning which I did not have time to test today.
i.e. If the tape block size is 64k and the 'dd if=/dev/nst0 of=/tmp/b1 
bs=32k count=1', does the above patch return 32k of data ?
My feeling, is it doesn't. I hope to test and confirm/correct the patch 
sometime tomorrow.

Cheers
Mark
--
To unsubscribe from this list: send the line "unsubscribe stgt" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html