Re: [PATCH V2] ovl: Allocate anonymous devs for lowerdirs

[Chandan Rajendra <chandan@linux.vnet.ibm.com>]

On Tuesday, June 27, 2017 1:01:17 PM IST Chandan Rajendra wrote:
> On Friday, June 23, 2017 7:04:57 PM IST Amir Goldstein wrote:
> > On Fri, Jun 23, 2017 at 2:01 PM, Chandan Rajendra
> > <chandan@linux.vnet.ibm.com> wrote:
> > > For stat(2) on lowerdir non-dir entries in non-samefs case, this commit
> > > provides unique values for st_dev. The unique values are obtained by
> > > allocating anonymous bdevs for each of the lowerdirs in the overlayfs
> > > instance.
> > >
> > > Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
> > > ---
> > 
> > Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> > Tested-by: Amir Goldstein <amir73il@gmail.com>
> > 
> > Miklos,
> > 
> > I re-created the branch ovl-constino [1] on top of ovl-hardlinks and without
> > the consistent dino patches.
> > 
> > Applied Chandan's patch and resolved conflicts with my patches.
> > Then, applied my patch to relax constant st_ino  for non-samefs on stat(2).
> > 
> > Mutilated unionmount-testsuite layers check [2] to get over the unexpected
> > pseudo dev and now tests pass for non samefs including constant ino
> > verification and persistent ino verification for non-dir.
> > 
> > Chandan,
> > 
> > If you can fix the mutilated unionmount-testsuite check_layer(), that would be
> > nice.
> > 
> 

Hi Amir,

In dentry.created(), we have

        self.__upper = on_upper or not inode or inode.filetype() == "d"

Do you happen to know why we mark the dentry as being present on the upperdir
filesystem when "inode" evaluates to false?

Consider the case of /lowerdir/a/foo101 file being created in
set_up.py. ctx.record_file() ends up creating a new 'dentry' object with no
inode associated with it. Hence self.__upper is set to the value True. Isn't
this incorrect since the file foo101 is actually being created on lowerdir?

I added the following new test scenario to check_layer() code,

   elif dentry.on_upper() and not self.config().is_samefs() and dev != self.upper_fs():
          raise TestError(name + ": Upperdir file has incorrect dev id")

In the above code snippet, dentry.on_upper() incorrectly evaluates to True and
hence we end up raising an exception.

Maybe dentry.created should have the following statement instead,

     self.__upper = on_upper or (inode and inode.filetype() == "d")

-- 
chandan