[PATCH v2 1/2] common: support black listing fs in _supported_fs()

[Amir Goldstein <amir73il@gmail.com>]

For example:
_supported_fs ^xfs

There is no need to specify "generic" when using a block list
"all other fs are supported" is implied.

Converted some generic tests that open code this condition without
emitting a meaningful reason.

More generic test like generic/186,187 could use a block list, but
were not converted because they emit some meaningful reason:
  _notrun "Can't fragment free space on btrfs."

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 common/rc         | 30 ++++++++++++++++++++----------
 tests/generic/500 |  3 +--
 tests/generic/631 |  3 +--
 tests/generic/679 |  3 +--
 4 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/common/rc b/common/rc
index 553ae350..ae201f87 100644
--- a/common/rc
+++ b/common/rc
@@ -1580,19 +1580,29 @@ _fail()
 
 # tests whether $FSTYP is one of the supported filesystems for a test
 #
-_supported_fs()
+_check_supported_fs()
 {
-    local f
+	local res=1
+	local f
 
-    for f
-    do
-	if [ "$f" = "$FSTYP" -o "$f" = "generic" ]
-	then
-	    return
-	fi
-    done
+	for f; do
+		# ^FS means black listed fs
+		if [ "$f" = "^$FSTYP" ]; then
+			return 1
+		elif [ "$f" = "generic" ] || [[ "$f" == "^"* ]]; then
+			# ^FS implies "generic ^FS"
+			res=0
+		elif [ "$f" = "$FSTYP" ]; then
+			return 0
+		fi
+	done
+	return $res
+}
 
-    _notrun "not suitable for this filesystem type: $FSTYP"
+_supported_fs()
+{
+	_check_supported_fs $* || \
+		_notrun "not suitable for this filesystem type: $FSTYP"
 }
 
 # check if a FS on a device is mounted
diff --git a/tests/generic/500 b/tests/generic/500
index 0be59934..bc84d219 100755
--- a/tests/generic/500
+++ b/tests/generic/500
@@ -35,7 +35,6 @@ _cleanup()
 . ./common/dmthin
 
 # real QA test starts here
-_supported_fs generic
 _require_scratch_nocheck
 _require_dm_target thin-pool
 
@@ -43,7 +42,7 @@ _require_dm_target thin-pool
 # and since we've filled the thinp device it'll return EIO, which will make
 # btrfs flip read only, making it fail this test when it just won't work right
 # for us in the first place.
-test $FSTYP == "btrfs"  && _notrun "btrfs doesn't work that way lol"
+_supported_fs ^btrfs
 
 # Require underlying device support discard
 _scratch_mkfs >>$seqres.full 2>&1
diff --git a/tests/generic/631 b/tests/generic/631
index 4996bce7..219f7a05 100755
--- a/tests/generic/631
+++ b/tests/generic/631
@@ -36,10 +36,9 @@ _cleanup()
 . ./common/attr
 
 # real QA test starts here
-_supported_fs generic
 _require_scratch
 _require_attrs trusted
-test "$FSTYP" = "overlay" && _notrun "Test does not apply to overlayfs."
+_supported_fs ^overlay
 _require_extra_fs overlay
 
 _scratch_mkfs >> $seqres.full
diff --git a/tests/generic/679 b/tests/generic/679
index 440f0c08..c32d42b9 100755
--- a/tests/generic/679
+++ b/tests/generic/679
@@ -17,7 +17,6 @@ _begin_fstest auto quick prealloc
 
 # real QA test starts here
 
-_supported_fs generic
 _require_scratch
 _require_xfs_io_command "falloc"
 _require_xfs_io_command "fiemap"
@@ -26,7 +25,7 @@ _require_xfs_io_command "fiemap"
 #
 #   https://lore.kernel.org/linux-btrfs/20220315164011.GF8241@magnolia/
 #
-[ $FSTYP == "xfs" ] && _notrun "test not valid for xfs"
+_supported_fs ^xfs
 
 rm -f $seqres.full
 
-- 
2.25.1