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

[Sean Anderson]

On 7/2/21 3:01 PM, 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.
 > 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)
 >           # 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.

Have we tried using fuse? I've had good results with fuse2fs (although
it does not support the journal), and there is a fusefat package as
well. Example usage:

	mkdir -p root
	truncate -s 1G root.img
	mkfs.ext4 -q $@
	fuse2fs -o fakeroot root.img root
	fakeroot tar -C root -xf rootfs.tar
	fusermount -u root

If you don't need correct permissions, you can skip the fakeroot stuff.

If you want to go one step further, you can also try lklfuse [1], though
I have not used it.

[1] https://github.com/lkl/linux

--Sean