On 14-01-24 03:35 AM, kai.makisara@xxxxxxxxxxx wrote:
Matthias Eble [psychotrahe@xxxxxxxxx] kirjoitti:Hi list, When a tape device is reserved with old reserve/release commands, we see inquiry only works on the scsi generic device. For scsi tape devices open() fails already: # lsscsi -g | grep st15 [2:0:6:0] tape HP Ultrium 5-SCSI I5DZ /dev/st15 /dev/sg17 # sg_vpd -vvv /dev/st15 open /dev/st15 with flags=0x800 error opening file: /dev/st15: Input/output error # sg_vpd -vvv /dev/nst15 open /dev/nst15 with flags=0x800 error opening file: /dev/nst15: Input/output error # sg_vpd -vvv /dev/sg17 open /dev/sg17 with flags=0x800 Supported VPD pages VPD page: inquiry cdb: 12 01 00 00 fc 00 duration=2 ms inquiry: requested 252 bytes but got 22 bytes [PQual=0 Peripheral device type: tape] Supported VPD pages [sv] Unit serial number [sn] ... So: should open() fail on a reserved tape device? SPC2 states that INQUIRY should never conflict. Or does that only apply to the generic device? Okay, it doesn't conflict, but open fails. A SunOS st man page I found states, INQUIRY shall be possible with reserved devices.Opening a st device does more than INQUIRY (TEST_UNIT_READY, READ_BLOCK_LIMITS, MODE_SENSE). Can this explain what you see?
TEST UNIT READY is allowed in SPC-4 but there is a note about it being disallowed (i.e. RESERVATION CONFLICT) in SPC-2 and SPC-3. MODE SENSE conflicts with some types of reservations and READ BLOCK LIMITS is allowed. But EIO, arrrrr; that should be banned from the whole storage subsystem. Either that or equate it to "I don't have a clue why this failed". A Reservation Conflict is a very useful piece of information that tells the user twiddling knobs in sysfs ain't going to help. And back to the original question; situations like these are exactly why there needs to be pass-throughs (and bsg should work as well as sg). A pass-through implements a policy of "you asked for it, you got it, and with a minimum of side effects". Doug Gilbert -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
