Re: [RFC][PATCH 7/8] fstests: add support for working with dm-log-writes target

[Josef Bacik <josef@toxicpanda.com>]

On Wed, Aug 23, 2017 at 06:58:38PM +0300, Amir Goldstein wrote:
> On Wed, Aug 23, 2017 at 6:49 PM, Amir Goldstein <amir73il@gmail.com> wrote:
> > Cherry-picked the relevant common bits from commit 70d41e17164b
> > in Josef Bacik's fstests tree (https://github.com/josefbacik/fstests).
> > Quoting from Josef's commit message:
> >
> >   This patch adds the supporting code for using the dm-log-writes
> >   target.  The dmlogwrites code is similar to the dmflakey code, it just
> >   gives us functions to build and tear down a dm-log-writes target.  We
> >   add a new LOGWRITES_DEV variable to take in the device we will use as
> >   the log and add checks for that.
> >
> > [Amir:]
> > - Removed unneeded _test_falloc_support
> > - Moved _require_log_writes to dmlogwrites
> > - Document _require_log_writes
> >
> > Cc: Josef Bacik <jbacik@fb.com>
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> >  README                       |  2 ++
> >  common/dmlogwrites           | 86 ++++++++++++++++++++++++++++++++++++++++++++
> >  doc/requirement-checking.txt | 20 +++++++++++
> >  3 files changed, 108 insertions(+)
> >  create mode 100644 common/dmlogwrites
> >
> 
> ...
> 
> > +
> > +_init_log_writes()
> > +{
> > +       local BLK_DEV_SIZE=`blockdev --getsz $SCRATCH_DEV`
> > +       LOGWRITES_NAME=logwrites-test
> > +       LOGWRITES_DMDEV=/dev/mapper/$LOGWRITES_NAME
> > +       LOGWRITES_TABLE="0 $BLK_DEV_SIZE log-writes $SCRATCH_DEV $LOGWRITES_DEV"
> > +       $DMSETUP_PROG create $LOGWRITES_NAME --table "$LOGWRITES_TABLE" || \
> > +               _fatal "failed to create log-writes device"
> > +       $DMSETUP_PROG mknodes > /dev/null 2>&1
> > +}
> > +
> ...
> > +_cleanup_log_writes()
> > +{
> > +       # If dmsetup load fails then we need to make sure to do resume here
> > +       # otherwise the umount will hang
> 
> Josef,
> 
> Care to explain this comment?
> What do you mean by "resume" here? is this a real concern?
>

I don't know, I think I had this weird suspend/resume thing before but got rid
of it and forgot to remove the comment.  Thanks,

Josef