[0/2] scsi: st: Device reset patches

Message

Kai Mäkisara (Kolumbus) Nov. 4, 2024, 11:26 a.m. UTC

These two patches were developed in response to Bugzilla report
https://bugzilla.kernel.org/show_bug.cgi?id=219419

After device reset, the tape driver allows only operations tha don't
write or read anything from tape. The reason for this is that many
(most ?) drives rewind the tape after reset and the subsequent reads
or writes would not be at the tape location the user expects. Reading
and writing is allowed again when the user does something to position the
tape (e.g., rewind).

The Bugzilla report considers the case when a user, after reset, tries
to read the drive status with MTIOCGET ioctl, but it fails. MTIOCGET
does not return much useful data after reset, but it can be allowed.
MTLOAD positions the tape and it should be allowed. The second patch
adds these to the set of allowed operations after device reset. 

The first patch fixes a bug seen when developing the second patch.

Kai Mäkisara (2):
  scsi: st: Don't modify unknown block number in MTIOCGET
  scsi: st: Add MTIOCGET and MTLOAD to ioctls allowed after device reset

 drivers/scsi/st.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

Comments

John Meneghini Nov. 5, 2024, 8:18 p.m. UTC | #1

Thanks for the fix Kai.

While testing these changes with a tape drive I came across one more issue.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219419#c14

I'll send a follow on patch which I think might address that issue.

Martin, please merge these patches... we have a number of customers waiting for this fix.

/John

On 11/4/24 06:26, Kai Mäkisara wrote:
> These two patches were developed in response to Bugzilla report
> https://bugzilla.kernel.org/show_bug.cgi?id=219419
> 
> After device reset, the tape driver allows only operations tha don't
> write or read anything from tape. The reason for this is that many
> (most ?) drives rewind the tape after reset and the subsequent reads
> or writes would not be at the tape location the user expects. Reading
> and writing is allowed again when the user does something to position the
> tape (e.g., rewind).
> 
> The Bugzilla report considers the case when a user, after reset, tries
> to read the drive status with MTIOCGET ioctl, but it fails. MTIOCGET
> does not return much useful data after reset, but it can be allowed.
> MTLOAD positions the tape and it should be allowed. The second patch
> adds these to the set of allowed operations after device reset.
> 
> The first patch fixes a bug seen when developing the second patch.
> 
> Kai Mäkisara (2):
>    scsi: st: Don't modify unknown block number in MTIOCGET
>    scsi: st: Add MTIOCGET and MTLOAD to ioctls allowed after device reset
> 
>   drivers/scsi/st.c | 31 ++++++++++++++++++++++---------
>   1 file changed, 22 insertions(+), 9 deletions(-)
>