common/btrfs: add helper _has_btrfs_sysfs_feature_attr

With this helper, btrfs test cases can now check if a particular feature
is implemented in the kernel.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/common/btrfs b/common/btrfs
index c3bffd2ae3..fbc26181f7 100644
--- a/common/btrfs
+++ b/common/btrfs
@@ -753,3 +753,15 @@ _require_scratch_enable_simple_quota()
 					_notrun "simple quotas not available"
 	_scratch_unmount
 }
+
+_has_btrfs_sysfs_feature_attr()
+{
+	local feature_attr=$1
+
+	[ -z $feature_attr ] && \
+		_fail "Missing feature name argument for _has_btrfs_sysfs_attr"
+
+	modprobe btrfs &> /dev/null
+
+	test -e /sys/fs/btrfs/features/$feature_attr
+}