> On 22. Aug 2023, at 21.14, John Meneghini <jmeneghi@xxxxxxxxxx> wrote: > > Many tape devices will automatically rewind following a poweron/reset. > This can result in data loss as other operations in the driver can write > to the tape when the position is unknown. E.g. MTEOM can write a > filemark at the beginning of the tape. This patch adds code to detect > poweron/reset unit attentions and prevents the driver from writing to > the tape when the position could be unknown. > > Customer reported problem description: > > ... Good catch! I think that, in an ideal world, the lower levels should detect the reset (STp->device->was_reset), but this depends on how you define the model from the user point of view (what the virtual HBA is). But, in the real world, this is a good safeguard and it solves a real problem. Thanks, Kai > Suggested-by: Jeffrey Hutzelman <jhutz@xxxxxxx> > Signed-off-by: John Meneghini <jmeneghi@xxxxxxxxxx> Acked-by: Kai Mäkisara <kai.makisara@xxxxxxxxxxx <mailto:kai.makisara@xxxxxxxxxxx>> > --- > drivers/scsi/st.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c > index 14d7981ddcdd..338aa8c42968 100644 > --- a/drivers/scsi/st.c > +++ b/drivers/scsi/st.c > @@ -414,6 +414,8 @@ static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt) > if (cmdstatp->have_sense && > cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17) > STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */ > + if (cmdstatp->have_sense && scode == UNIT_ATTENTION && cmdstatp->sense_hdr.asc == 0x29) > + STp->pos_unknown = 1; /* ASC => power on / reset */ > > STp->pos_unknown |= STp->device->was_reset; > > -- > 2.39.3 >
