Re: [PATCH RFC] fstests: use MOUNT_OPTIONS to populate TEST_FS_MOUNT_OPTS if possible

On Mon, Jun 01, 2026 at 11:13:01PM -0700, Christoph Hellwig wrote:
> On Tue, Jun 02, 2026 at 09:44:22AM +0930, Qu Wenruo wrote:
> > If the test config only specifies "MOUNT_OPTIONS", but not
> > "TEST_FS_MOUNT_OPTS", the mount for TEST_DIR can have inconsistent flag
> > after _test_cycle_mount().
>
> AFAIK TEST_FS_MOUNT_OPTS gets overriden and isn't even a public option.
> It gets filled by fstype-sepcific options in _common_mount_opts.
> 
> This started to really confuse me lately when I was trying to test with
> mount options on the test fs.
> 
> I've looked at bit into the area but haven't come to a conclusion yet.
> The most recent change in this area is 1dd7395623cb ("common/config:
> Make test and scratch devices use the same mount options"), which didn't
> really make them common, adding to my confusion.
> 
> So I really think we need to fix things here, but right now I'm not sure
> how much of the current situation is intentional, and what our final
> goal is :(

Sorry for this terrible code logic.

AFAIK, TEST_FS_MOUNT_OPTS and MOUNT_OPTIONS serve different purposes:
TEST_FS_MOUNT_OPTS is used for TEST_DEV, while MOUNT_OPTIONS is used for
SCRATCH_DEV as well as loop or dm devices and so on. For instance, _test_mount
only applies TEST_FS_MOUNT_OPTS, whereas _scratch_mount only uses MOUNT_OPTIONS.
I used xfstests for over a decade, I typically configure both variables together
(often to the same values), so I didn't give them too much thought.

About the commit 1dd7395623cb, the subject of it would be better to be
"Make test and scratch devices use the same *default* mount options"
from ${FSTYP}_MOUNT_OPTIONS parameters. The original intent was not to merge
TEST_FS_MOUNT_OPTS and MOUNT_OPTIONS into a single variable.

About documentation, it is true that TEST_FS_MOUNT_OPTS is barely mentioned.
It is completely missing from the main README and only appears in other
sub-documents like README.config-sections. We should definitely clarify the
relationship between TEST_FS_MOUNT_OPTS and TEST_DEV, and metion that they
have no connection to MOUNT_OPTIONS.

Right now, the biggest inconsistent issue is probably with those feature-probing
helpers. They often check TEST_DIR to determine behaviors for SCRATCH_MNT. While
this works fine for features unaffected by mount options, but we might should
handle mount options related features (for TEST_DEV or SCRATCH_DEV) separately.

Thanks,
Zorro

>