[RFC PATCH v2 1/3] common/xfs: add a _require_xfs_shrink helper

[Gao Xiang <hsiangkao@redhat.com>]

In order to detect whether the current kernel supports XFS shrinking.

Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
---
use -D1 rather than -D0 since xfs_growfs would report unchanged size
instead.

 common/xfs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/common/xfs b/common/xfs
index 2156749d..326edacc 100644
--- a/common/xfs
+++ b/common/xfs
@@ -432,6 +432,16 @@ _supports_xfs_scrub()
 	return 0
 }
 
+_require_xfs_shrink()
+{
+	_scratch_mkfs_xfs >/dev/null 2>&1
+
+	_scratch_mount
+	$XFS_GROWFS_PROG -D1 "$SCRATCH_MNT" 2>&1 | grep -q 'Invalid argument' || { \
+		_scratch_unmount; _notrun "kernel does not support shrinking"; }
+	_scratch_unmount
+}
+
 # run xfs_check and friends on a FS.
 _check_xfs_filesystem()
 {
-- 
2.27.0