Re: [PATCH 01/33] misc: adapt tests to handle the fuse ext[234] drivers

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Oct 30, 2025 at 10:51:06AM +0100, Amir Goldstein wrote:
> On Wed, Oct 29, 2025 at 2:22 AM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > It would be useful to be able to run fstests against the userspace
> > ext[234] driver program fuse2fs.  A convention (at least on Debian)
> > seems to be to install fuse drivers as /sbin/mount.fuse.XXX so that
> > users can run "mount -t fuse.XXX" to start a fuse driver for a
> > disk-based filesystem type XXX.
> >
> > Therefore, we'll adopt the practice of setting FSTYP=fuse.ext4 to
> > test ext4 with fuse2fs.  Change all the library code as needed to handle
> > this new type alongside all the existing ext[234] checks, which seems a
> > little cleaner than FSTYP=fuse FUSE_SUBTYPE=ext4, which also would
> > require even more treewide cleanups to work properly because most
> > fstests code switches on $FSTYP alone.
> >
> 
> I agree that FSTYP=fuse.ext4 is cleaner than
> FSTYP=fuse FUSE_SUBTYPE=ext4
> but it is not extendable to future (e.g. fuse.xfs)
> and it is still a bit ugly.
> 
> Consider:
> FSTYP=fuse.ext4
> MKFSTYP=ext4
> 
> I think this is the correct abstraction -
> fuse2fs/ext4 are formatted that same and mounted differently
> 
> See how some of your patch looks nicer and naturally extends to
> the imaginary fuse.xfs...

Maybe I'd rather do it the other way around for fuse4fs:

FSTYP=ext4
MOUNT_FSTYP=fuse.ext4

(obviously, MOUNT_FSTYP=$FSTYP if the test runner hasn't overridden it)

Where $MOUNT_FSTYP is what you pass to mount -t and what you'd see in
/proc/mounts.  The only weirdness with that is that some of the helpers
will end up with code like:

	case $FSTYP in
	ext4)
		# do ext4 stuff
		;;
	esac

	case $MOUNT_FSTYP in
	fuse.ext4)
		# do fuse4fs stuff that overrides ext4
		;;
	esac

which would be a little weird.

_scratch_mount would end up with:

	$MOUNT_PROG -t $MOUNT_FSTYP ...

and detecting it would be

	grep -q -w $MOUNT_FSTYP /proc/mounts || _fail "booooo"

Hrm?

--D

> 
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  check             |   24 +++++++++++++++++-------
> >  common/casefold   |    4 ++++
> >  common/config     |   11 ++++++++---
> >  common/defrag     |    2 +-
> >  common/encrypt    |   16 ++++++++--------
> >  common/log        |   10 +++++-----
> >  common/populate   |   14 +++++++-------
> >  common/quota      |    9 +++++++++
> >  common/rc         |   50 +++++++++++++++++++++++++++++---------------------
> >  common/report     |    2 +-
> >  common/verity     |    8 ++++----
> >  tests/generic/020 |    2 +-
> >  tests/generic/067 |    2 +-
> >  tests/generic/441 |    2 +-
> >  tests/generic/496 |    2 +-
> >  tests/generic/621 |    2 +-
> >  tests/generic/740 |    2 +-
> >  tests/generic/746 |    4 ++--
> >  tests/generic/765 |    4 ++--
> >  19 files changed, 103 insertions(+), 67 deletions(-)
> >
> >
> > diff --git a/check b/check
> > index 9bb80a22440f97..81cd03f73ce155 100755
> > --- a/check
> > +++ b/check
> > @@ -140,12 +140,25 @@ get_sub_group_list()
> >         echo $grpl
> >  }
> >
> > +get_group_dirs()
> > +{
> > +       local fsgroup="$FSTYP"
> > +
> > +       case "$FSTYP" in
> > +       ext2|ext3|fuse.ext[234])
> > +               fsgroup=ext4
> > +               ;;
> > +       esac
> > +
> > +       echo $SRC_GROUPS
> > +       echo $fsgroup
> > +}
> > +
> >  get_group_list()
> >  {
> >         local grp=$1
> >         local grpl=""
> >         local sub=$(dirname $grp)
> > -       local fsgroup="$FSTYP"
> >
> >         if [ -n "$sub" -a "$sub" != "." -a -d "$SRC_DIR/$sub" ]; then
> >                 # group is given as <subdir>/<group> (e.g. xfs/quick)
> > @@ -154,10 +167,7 @@ get_group_list()
> >                 return
> >         fi
> >
> > -       if [ "$FSTYP" = ext2 -o "$FSTYP" = ext3 ]; then
> > -           fsgroup=ext4
> > -       fi
> > -       for d in $SRC_GROUPS $fsgroup; do
> > +       for d in $(get_group_dirs); do
> >                 if ! test -d "$SRC_DIR/$d" ; then
> >                         continue
> >                 fi
> > @@ -171,7 +181,7 @@ get_group_list()
> >  get_all_tests()
> >  {
> >         touch $tmp.list
> > -       for d in $SRC_GROUPS $FSTYP; do
> > +       for d in $(get_group_dirs); do
> >                 if ! test -d "$SRC_DIR/$d" ; then
> >                         continue
> >                 fi
> > @@ -387,7 +397,7 @@ if [ -n "$FUZZ_REWRITE_DURATION" ]; then
> >  fi
> >
> >  if [ -n "$subdir_xfile" ]; then
> > -       for d in $SRC_GROUPS $FSTYP; do
> > +       for d in $(get_group_dirs); do
> >                 [ -f $SRC_DIR/$d/$subdir_xfile ] || continue
> >                 for f in `sed "s/#.*$//" $SRC_DIR/$d/$subdir_xfile`; do
> >                         exclude_tests+=($d/$f)
> > diff --git a/common/casefold b/common/casefold
> > index 2aae5e5e6c8925..fcdb4d210028ac 100644
> > --- a/common/casefold
> > +++ b/common/casefold
> > @@ -6,6 +6,10 @@
> >  _has_casefold_kernel_support()
> >  {
> >         case $FSTYP in
> > +       fuse.ext[234])
> > +               # fuse2fs does not support casefolding
> > +               false
> > +               ;;
> 
> This would not be needed
> 
> >         ext4)
> >                 test -f '/sys/fs/ext4/features/casefold'
> >                 ;;
> > diff --git a/common/config b/common/config
> > index 7fa97319d7d0ca..0cd2b33c4ade40 100644
> > --- a/common/config
> > +++ b/common/config
> > @@ -386,6 +386,11 @@ _common_mount_opts()
> >         overlay)
> >                 echo $OVERLAY_MOUNT_OPTIONS
> >                 ;;
> > +       fuse.ext[234])
> > +               # fuse sets up secure defaults, so we must explicitly tell
> > +               # fuse2fs to use the more relaxed kernel access behaviors.
> > +               echo "-o kernel $EXT_MOUNT_OPTIONS"
> > +               ;;
> >         ext2|ext3|ext4)
> >                 # acls & xattrs aren't turned on by default on ext$FOO
> >                 echo "-o acl,user_xattr $EXT_MOUNT_OPTIONS"
> > @@ -472,7 +477,7 @@ _mkfs_opts()
> >  _fsck_opts()
> >  {
> >         case $FSTYP in
> 
> This would obviously be $MKFSTYP with no further changes
> 
> > -       ext2|ext3|ext4)
> > +       ext2|ext3|fuse.ext[234]|ext4)
> >                 export FSCK_OPTIONS="-nf"
> >                 ;;
> >         reiser*)
> > @@ -514,11 +519,11 @@ _source_specific_fs()
> >
> >                 . ./common/btrfs
> >                 ;;
> > -       ext4)
> > +       fuse.ext4|ext4)
> >                 [ "$MKFS_EXT4_PROG" = "" ] && _fatal "mkfs.ext4 not found"
> >                 . ./common/ext4
> >                 ;;
> > -       ext2|ext3)
> > +       ext2|ext3|fuse.ext[23])
> >                 . ./common/ext4
> 
> same here
> 
> >                 ;;
> >         f2fs)
> > diff --git a/common/defrag b/common/defrag
> > index 055d0d0e9182c5..c054e62bde6f4d 100644
> > --- a/common/defrag
> > +++ b/common/defrag
> > @@ -12,7 +12,7 @@ _require_defrag()
> >          _require_xfs_io_command "falloc"
> >          DEFRAG_PROG="$XFS_FSR_PROG"
> >         ;;
> > -    ext4)
> > +    fuse.ext4|ext4)
> >         testfile="$TEST_DIR/$$-test.defrag"
> >         donorfile="$TEST_DIR/$$-donor.defrag"
> >         bsize=`_get_block_size $TEST_DIR`
> 
> and here
> 
> > diff --git a/common/encrypt b/common/encrypt
> > index f2687631b214cf..4fa7b6853fd461 100644
> > --- a/common/encrypt
> > +++ b/common/encrypt
> > @@ -191,7 +191,7 @@ _require_hw_wrapped_key_support()
> >  _scratch_mkfs_encrypted()
> >  {
> >         case $FSTYP in
> > -       ext4|f2fs)
> > +       fuse.ext4|ext4|f2fs)
> >                 _scratch_mkfs -O encrypt
> >                 ;;
> 
> and here
> 
> >         ubifs)
> > @@ -210,7 +210,7 @@ _scratch_mkfs_encrypted()
> >  _scratch_mkfs_sized_encrypted()
> >  {
> >         case $FSTYP in
> > -       ext4|f2fs)
> > +       fuse.ext4|ext4|f2fs)
> >                 MKFS_OPTIONS="$MKFS_OPTIONS -O encrypt" _scratch_mkfs_sized $*
> >                 ;;
> 
> and here... I think you got my point.
> 
> Thanks,
> Amir.
>