On Tue, 25 Nov 2008 15:27:35 +1100
"Mark Harvey" <markh794@xxxxxxxxx> wrote:
> On Sun, Nov 23, 2008 at 4:26 AM, FUJITA Tomonori
> <fujita.tomonori@xxxxxxxxxxxxx> wrote:
> > On Thu, 13 Nov 2008 10:52:43 +1100
> > "Mark Harvey" <markh794@xxxxxxxxx> wrote:
> >
> > Seems that the attached patch fixes the 512-byte read case, but not
> > 256-byte. I guess that I still misunderstand something...
> >
> >
> >> >> Now test we can read in a 256k block from the tape.
> >> >> # dd if=/dev/st0 of=/tmp/block0 bs=256k count=1
> >> >> 1+0 records in
> >> >> 1+0 records out
> >> >> 262144 bytes (262 kB) copied, 0.00424289 s, 61.8 MB/s
> >> >>
> >> >> Now test if we can read in a partial block (this fails returning no
> >> >> data - we should have read in the 128k)
> >> >> # dd if=/dev/st0 of=/tmp/block0 bs=128k count=1
> >> >> dd: reading `/dev/st0': Input/output error
> >> >> 0+0 records in
> >> >> 0+0 records out
> >> >> 0 bytes (0 B) copied, 0.00249643 s, 0.0 kB/s
> >> >
> >> > Sorry for my dumb question here:
> >> >
> >> > What should stgt return? The first 128 KB of the first block and no
> >> > sense?
> >>
> >> The amount of data requested should be returned. In this example, 128k.
> >>
> >> The sense returned should be :NO SENSE | VALID | ILI (Illegal Length
> >> Indicator) and the overrun values (size of data block - size of data
> >> requested) filled in sense_buffer[3] -> sense_buffer[7].
> >
> > With the patch, stgt returns CHECK CONDITION with a sense (NO SENSE |
> > VALID | ILI ) and the information field sets to 128K.
> >
> > I got (actually, stgt returns 128KB data though...):
> >
> > nemo:/home/fujita# dd if=/dev/st0 of=/tmp/block0 bs=128k count=1
> > 0+0 records in
> > 0+0 records out
> > 0 bytes (0 B) copied, 0.0030381 seconds, 0.0 kB/s
> >
> > But the last line should be something like:
> >
> > 131072 bytes (131 kB) copied...
> >
> > Right?
>
> Just re-tested on real hardware:
> # [2:0:4:2] tape QUANTUM SuperDLT1 2323 /dev/st1 /dev/sg8
> # sg_inq -v /dev/sg8
> inquiry cdb: 12 00 00 00 24 00
> standard INQUIRY:
> inquiry cdb: 12 00 00 00 3a 00
> PQual=0 Device_type=1 RMB=1 version=0x02 [SCSI-2]
> [AERC=0] [TrmTsk=0] NormACA=0 HiSUP=1 Resp_data_format=2
> SCCS=0 ACC=0 TGPS=0 3PC=0 Protect=0 BQue=0
> EncServ=0 MultiP=0 [MChngr=0] [ACKREQQ=0] Addr16=0
> [RelAdr=0] WBus16=0 Sync=0 Linked=0 [TranDis=0] CmdQue=0
> Clocking=0x0 QAS=0 IUS=0
> length=58 (0x3a) Peripheral device type: tape
> Vendor identification: QUANTUM
> Product identification: SuperDLT1
> Product revision level: 2323
> inquiry cdb: 12 01 00 00 fc 00
> inquiry: requested 252 bytes but got 9 bytes
> inquiry cdb: 12 01 80 00 fc 00
> inquiry: requested 252 bytes but got 16 bytes
> Unit serial number: PKB53H0142
That's really helpful, thanks!
> An attempt to read 128k from a 256k block results with an error message:
> # dd if=/dev/st1 bs=128k count=1 of=/tmp/block0
> dd: reading `/dev/st1': Cannot allocate memory
> 0+0 records in
> 0+0 records out
> 0 bytes (0 B) copied, 0.01287 seconds, 0.0 kB/s
>
> And /var/log/messages:
> kernel: st1: Failed to read 262144 byte block with 131072 byte transfer.
I think that this is a kernel message that st driver gives when the
INFORMATION field has a negative value. In this case, the INFORMATION
field had -128K.
I've attached a new patch. The difference from the previous one is
just one line, it sets a negative value to the INFORMATION field when
the requested transfer length is smaller than the actual logical block
length.
> Disclaimer...
> I'm 99.99% positive, last time I tried this I received a different
> message and did in fact read 128k of data. This may be an
> implementation of dd used..
With the same tape drive?
> # rpm -qf `which dd`
> coreutils-5.93-22.14
> # uname -a
> Linux dpg-markh 2.6.16.46-0.12-smp #1 SMP Thu May 17 14:00:09 UTC 2007
> i686 i686 i386 GNU/Linux
>
> >
> >
> >> >> Now test if we can read in a more then a block (this fails returning
> >> >> no data - we should have read in the 256k)
> >> >> # dd if=/dev/st0 of=/tmp/block0 bs=512k count=1
> >> >> dd: reading `/dev/st0': Input/output error
> >> >> 0+0 records in
> >> >> 0+0 records out
> >> >> 0 bytes (0 B) copied, 0.00705821 s, 0.0 kB/s
> >> >
> >> > stgt should return the whole first block without sense, right?
> >> >
> >>
> >> The amount of data successfully read should be returned. In this example, 128k.
> >>
> >> The sense returned should be :NO SENSE | VALID | ILI (Illegal Length
> >> Indicator) and the amount of data NOT successfully returned -> filled
> >> in sense_buffer[3] -> sense_buffer[7]
> >
> > With the patch, stgt returns CHECK CONDITION with a sense (NO SENSE |
> > VALID | ILI ) and the information field sets to 256K.
> >
> > nemo:/home/fujita# dd if=/dev/st0 of=/tmp/block0 bs=512k count=1
> > 0+1 records in
> > 0+1 records out
> > 262144 bytes (262 kB) copied, 0.019265 seconds, 13.6 MB/s
> >
> > This is the right response?
> This is the correct response...
>
>
> Many thanks for having a look at this.
No problem at all. Thanks!
diff --git a/usr/bs_ssc.c b/usr/bs_ssc.c
index 0b9fedb..9ed9e65 100644
--- a/usr/bs_ssc.c
+++ b/usr/bs_ssc.c
@@ -317,15 +317,27 @@ static int resp_var_read(struct scsi_cmd *cmd, uint8_t *buf, uint32_t length,
*transferred = 0;
if (length != h->blk_sz) {
+ uint8_t info[4];
+ int val = length - h->blk_sz;
+
+ put_unaligned_be32(val, info);
+
if (h->blk_type == BLK_EOD)
sense_data_build(cmd, 0x40 | BLANK_CHECK,
NO_ADDITIONAL_SENSE);
else
- sense_data_build(cmd, NO_SENSE, NO_ADDITIONAL_SENSE);
+ ssc_sense_data_build(cmd, NO_SENSE | 0x20,
+ NO_ADDITIONAL_SENSE,
+ info, sizeof(info));
+
+ if (length > h->blk_sz)
+ scsi_set_in_resid_by_actual(cmd, length - h->blk_sz);
+ else
+ scsi_set_in_resid_by_actual(cmd, 0);
length = min(length, h->blk_sz);
+
result = SAM_STAT_CHECK_CONDITION;
- scsi_set_in_resid_by_actual(cmd, length);
if (!length)
goto out;
--
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