Re: Userspace regression with 6baca7601bde ("scsi: target: drop unused pi_prot_format attribute storage")

[Laura Abbott]

On 2/4/19 1:40 AM, David Disseldorp wrote:
> Hi Laura,
>
> Thanks for the report...
>
> On Sun, 3 Feb 2019 17:56:00 +0100, Laura Abbott wrote:
>
> > Fedora got a bug report of a new permission denied error with 5.0-rc2:
> >
> > >    File "/usr/lib/python3.7/site-packages/rtslib_fb/utils.py", line 100, in fread
> > >      with open(path, 'r') as file_fd:
> > > PermissionError: [Errno 13] Permission denied: '/sys/kernel/config/target/core/fileio_28/xxx/attrib/pi_prot_format'
> >
> > This looks like an intentional behavior change with
> >
> > commit 6baca7601bdee2e57f20c45d63eb53b89b33e816
> > Author: David Disseldorp <ddiss@xxxxxxx>
> > Date:   Fri Nov 23 18:36:11 2018 +0100
> >
> >       scsi: target: drop unused pi_prot_format attribute storage
> >       
> >       On write, the pi_prot_format configfs attribute invokes the device
> >       format_prot() callback if present. Read dumps the contents of
> >       se_dev_attrib.pi_prot_format which is always zero.  Make the configfs
> >       attribute write-only, and drop the always zero se_dev_attrib.pi_prot_format
> >       storage.
> >       
> >       Signed-off-by: David Disseldorp <ddiss@xxxxxxx>
> >       Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> >       Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
> >
> >
> > Unfortunately, existing code that's opening with read permissions is now broken.
> > Can this be reverted? Full bug at https://bugzilla.redhat.com/show_bug.cgi?id=1667505
>
> Lee (cc'ed) pinged me a couple of days ago about the same issue.
> My preference would be to add back a dummy read handler without the
> corresponding (unused) se_dev_attrib.pi_prot_format member.
> I'll prepare something tomorrow with this, but if it's urgent then I'd
> also be okay with a straight revert.
>
> Cheers, David

A fix is fine by me. Thanks for the prompt response.

Thanks,
Laura