[RFC] Start using guestfish for U-Boot fs tests

[Tom Rini]

On Fri, Jul 02, 2021 at 11:14:00PM +0300, Alper Nebi Yasak wrote:
> On 02/07/2021 23:03, Alper Nebi Yasak wrote:
> > On 02/07/2021 22:01, Tom Rini wrote:
> >> Hey all,
> >>
> >> I started taking a look at moving to guestfish to see if this resolves
> >> the latest problem I've run in to:
> >> https://source.denx.de/u-boot/u-boot/-/jobs/284763#L307
> >> which I think is due to guestmount not being done in time for the test.
> > 
> > That failing test's setup uses virt-make-fs, different from what you're
> > changing below. I locally only see that failure for the clang build, and
> > it still fails after adding time.sleep(300) after its virt-make-fs
> > calls. I don't think it's an issue in the test setup.
> > 
> >> So I started converting things to use guestfish directly:
> >> diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
> >> index 7325486cdb1a..e8899cfdd118 100644
> >> --- a/test/py/tests/test_fs/conftest.py
> >> +++ b/test/py/tests/test_fs/conftest.py
> >> @@ -265,10 +265,10 @@ def fs_obj_basic(request, u_boot_config):
> >>      fs_ubtype = fstype_to_ubname(fs_type)
> >>      check_ubconfig(u_boot_config, fs_ubtype)
> >>  
> >> -    mount_dir = u_boot_config.persistent_data_dir + '/mnt'
> >> +    data_dir = u_boot_config.persistent_data_dir + '/data'
> >>  
> >> -    small_file = mount_dir + '/' + SMALL_FILE
> >> -    big_file = mount_dir + '/' + BIG_FILE
> >> +    small_file = data_dir + '/' + SMALL_FILE
> >> +    big_file = data_dir + '/' + BIG_FILE
> >>  
> >>      try:
> >>  
> >> @@ -279,26 +279,14 @@ def fs_obj_basic(request, u_boot_config):
> >>          return
> >>  
> >>      try:
> >> -        check_call('mkdir -p %s' % mount_dir, shell=True)
> >> +        check_call('mkdir -p %s' % data_dir, shell=True)
> >>      except CalledProcessError as err:
> >>          pytest.skip('Preparing mount folder failed for filesystem: ' + fs_type + '. {}'.format(err))
> >>          call('rm -f %s' % fs_img, shell=True)
> >>          return
> >>  
> >>      try:
> >> -        # Mount the image so we can populate it.
> >> -        mount_fs(fs_type, fs_img, mount_dir)
> >> -    except CalledProcessError as err:
> >> -        pytest.skip('Mounting to folder failed for filesystem: ' + fs_type + '. {}'.format(err))
> >> -        call('rmdir %s' % mount_dir, shell=True)
> >> -        call('rm -f %s' % fs_img, shell=True)
> >> -        return
> >> -
> >> -    try:
> >> -        # Create a subdirectory.
> >> -        check_call('mkdir %s/SUBDIR' % mount_dir, shell=True)
> >> -
> >> -        # Create big file in this image.
> >> +        # Create big file to copy in to the image.
> >>          # Note that we work only on the start 1MB, couple MBs in the 2GB range
> >>          # and the last 1 MB of the huge 2.5GB file.
> >>          # So, just put random values only in those areas.
> >> @@ -309,10 +297,14 @@ def fs_obj_basic(request, u_boot_config):
> >>          check_call('dd if=/dev/urandom of=%s bs=1M count=1 seek=2499'
> >>              % big_file, shell=True)
> >>  
> >> -        # Create a small file in this image.
> >> +        # Create a small file to copy in to the image.
> >>          check_call('dd if=/dev/urandom of=%s bs=1M count=1'
> >>  	    % small_file, shell=True)
> >>  
> >> +        # Copy the files in to the image and add a subdirectory.
> >> +        # Create a subdirectory.
> >> +        check_call('guestfish add %s : run : mount /dev/sda / : mkdir /SUBDIR : copy-in %s %s /'
> >> +            % (fs_img, big_file, small_file), shell=True)
> > 
> > It could be faster to do things within guestfish as much as possible,
> > instead of preparing the files outside and copying them in.
> > 
> > Also it looks like python bindings are available as python3-guestfs on
> > Debian and Ubuntu, just not on pypi.org.
> > 
> >>          # Delete the small file copies which possibly are written as part of a
> >>          # previous test.
> >>          # check_call('rm -f "%s.w"' % MB1, shell=True)
> >> @@ -357,13 +349,11 @@ def fs_obj_basic(request, u_boot_config):
> >>  
> >>      except CalledProcessError as err:
> >>          pytest.skip('Setup failed for filesystem: ' + fs_type + '. {}'.format(err))
> >> -        umount_fs(mount_dir)
> >>          return
> >>      else:
> >> -        umount_fs(mount_dir)
> >>          yield [fs_ubtype, fs_img, md5val]
> >>      finally:
> >> -        call('rmdir %s' % mount_dir, shell=True)
> >> +        call('rmdir %s' % data_dir, shell=True)
> >>          call('rm -f %s' % fs_img, shell=True)
> >>  
> >>  #
> >>
> >> The problem here is that a test run went from taking about 5 minutes to
> >> taking about 17 minutes.  I can reduce this to closer to 15 minutes with
> >> LIBGUESTFS_BACKEND=direct and using libguestfs-make-fixed-appliance to
> >> make an appliance we reuse.  But that's still too long to be usable.
> >> I'm hoping someone has some ideas here on how to improve things.
> > 
> > If libguestfs is falling back to slow emulation because /dev/kvm isn't
> > available, maybe it's appropriate to check for that and skip the fs tests...
> 
> Also the User-Mode Linux backend might be worth exploring.

Trying to use user-mode-linux under Docker and I'm running in to another
round of failures and annoyances.  This might be easier with a Debian
rather than Ubuntu based container, so I'm not giving up yet, but it's
not a trivial switch anyhow.

-- 
Tom
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