fstests: add helper _require_scratch_feature

The helper is used to test if a specific filesystem feature can
be enabled. Currently only implemented testing overlayfs features.

Overalyfs features (e.g. redirect_dir, index) are configurable from
Kconfig (the build default), by module parameter (the system default)
and per mount using the mount option ${feature}=[on|off].

The helper is going to be used by overlay tests, which depend
on the inodes index feature.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

diff --git a/common/rc b/common/rc
index b5053659c1c8cd26d17ee407d48b53c8b81b9155..fa1314c649cf2825e7fac065d5c9a722ffcb7d89 100644 (file)
--- a/common/rc
+++ b/common/rc
@@ -3626,6 +3626,54 @@ _get_fs_sysfs_attr()
        cat /sys/fs/${FSTYP}/${dname}/${attr}
 }
 
+# Print the value of a filesystem module parameter
+# at /sys/module/$FSTYP/parameters/$PARAM
+#
+# Usage example (FSTYP=overlay):
+#   _get_fs_module_param index
+_get_fs_module_param()
+{
+       cat /sys/module/${FSTYP}/parameters/${1} 2>/dev/null
+}
+
+# Generic test for specific filesystem feature.
+# Currently only implemented to test overlayfs features.
+_require_scratch_feature()
+{
+       local feature=$1
+
+       case "$FSTYP" in
+       overlay)
+               # overalyfs features (e.g. redirect_dir, index) are
+               # configurable from Kconfig (the build default), by module
+               # parameter (the system default) and per mount by mount
+               # option ${feature}=[on|off].
+               #
+               # If the module parameter does not exist then there is no
+               # point in checking the mount option.
+               local default=`_get_fs_module_param ${feature}`
+               [ "$default" = Y ] || [ "$default" = N ] || \
+                       _notrun "feature '${feature}' not supported by ${FSTYP}"
+
+               _scratch_mkfs > /dev/null 2>&1
+               _scratch_mount -o ${feature}=on || \
+                       _notrun "${FSTYP} feature '${feature}' cannot be enabled on ${SCRATCH_DEV}"
+               # Check options to be sure. For example, Overlayfs will fallback to
+               # index=off if underlying fs does not support file handles.
+               # Overlayfs only displays mount option if it differs from the default.
+               # Overlayfs may enable the feature, but fallback to read-only mount.
+               ((( [ "$default" = N ] && _fs_options $SCRATCH_DEV | grep -q "${feature}=on" ) || \
+                 ( [ "$default" = Y ] && ! _fs_options $SCRATCH_DEV | grep -q "${feature}=off" )) && \
+                   touch $SCRATCH_MNT/foo 2>/dev/null ) || \
+                       _notrun "${FSTYP} feature '${feature}' cannot be enabled on ${SCRATCH_DEV}"
+               _scratch_unmount
+               ;;
+       *)
+               _fail "Test for feature '${feature}' of ${FSTYP} is not implemented"
+               ;;
+       esac
+}
+
 
 init_rc