[PATCH v6 1/3] common/xfs: add _require_xfs_scratch_shrink helper

[Gao Xiang <hsiangkao@redhat.com>]

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

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
---
 common/xfs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/common/xfs b/common/xfs
index 69f76d6e..a0a4032a 100644
--- a/common/xfs
+++ b/common/xfs
@@ -766,6 +766,26 @@ _require_xfs_mkfs_without_validation()
 	fi
 }
 
+_require_xfs_scratch_shrink()
+{
+	_require_scratch
+	_require_command "$XFS_GROWFS_PROG" xfs_growfs
+
+	_scratch_mkfs_xfs | _filter_mkfs 2>$tmp.mkfs >/dev/null
+	. $tmp.mkfs
+	_scratch_mount
+	# here just to check if kernel supports, no need do more extra work
+	errmsg=$($XFS_GROWFS_PROG -D$((dblocks-1)) "$SCRATCH_MNT" 2>&1)
+	if [ "$?" -ne 0 ]; then
+		echo "$errmsg" | grep 'XFS_IOC_FSGROWFSDATA xfsctl failed: Invalid argument' > /dev/null && \
+			_notrun "kernel does not support shrinking"
+		echo "$errmsg" | grep 'data size .* too small, old size is ' > /dev/null && \
+			_notrun "xfsprogs does not support shrinking"
+		_fail "$XFS_GROWFS_PROG failed unexpectedly: $errmsg"
+	fi
+	_scratch_unmount
+}
+
 # XFS ability to change UUIDs on V5/CRC filesystems
 #
 _require_meta_uuid()
-- 
2.27.0