[PATCH v4 1/2] common/rc: add functions to check or write objects under /sys/fs/$FSTYP

[Zorro Lang <zlang@redhat.com>]

XFS add more configurations in /sys/fs/xfs recently. For use
them, this patch add some common functions for:
  1. "require" a file/dir in /sys/fs/${FSTYP}.
  2. write a file in /sys/fs/${FSTYP}.

For common use, these functions can be used by other filesystems.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---

Hi,

V4 did below changes:
1) function name from *_fs_sys_fs to *_fs_sysfs
2) use $UMOUNT_PROG to instead of umount
3) use _short_dev
4) add comments for new functions
5) other little changes

Thanks,
Zorro

 common/rc | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/common/rc b/common/rc
index 51092a0..88c3777 100644
--- a/common/rc
+++ b/common/rc
@@ -3556,6 +3556,48 @@ run_fsx()
 	fi
 }
 
+# Test for the existence of a sysfs entry at /sys/fs/$FSTYP/$DEV/$ENTRY
+_require_fs_sysfs()
+{
+	local dev=$1
+	local entry=$2
+	local tmp_mnt=`mktemp -d`
+
+	if [ ! -b "$dev" -o -z "$entry" ];then
+		_fail "Usage: _require_fs_sysfs <device> <sysfs_path>"
+        fi
+
+	local dname=$(_short_dev $dev)
+	_mount -t $FSTYP `_common_dev_mount_options` $dev $tmp_mnt
+	if [ $? -ne 0 ];then
+		rm -f $tmp_mnt
+		_fail "_require_fs_sysfs: could not mount, mkfs first in your test?"
+	elif [ ! -e /sys/fs/${FSTYP}/${dname}/${entry} ];then
+		$UMOUNT_PROG $tmp_mnt
+		rm -f $tmp_mnt
+		_notrun "/sys/fs/${FSTYP}/${dname}/${entry}: No such file or directory"
+	fi
+	$UMOUNT_PROG $tmp_mnt
+	rm -rf $tmp_mnt
+}
+
+# Write "content" into /sys/fs/$FSTYP/$DEV/$ENTRY
+_set_fs_sysfs_param()
+{
+	local dev=$1
+	shift
+	local entry=$1
+	shift
+	local content="$*"
+
+	if [ ! -b "$dev" -o -z "$entry" -o -z "$content" ];then
+		_fail "Usage: _set_fs_sysfs_param <mounted_device> <entry> <content>"
+	fi
+
+	local dname=$(_short_dev $dev)
+	echo "$content" > /sys/fs/${FSTYP}/${dname}/${entry}
+}
+
 init_rc
 
 ################################################################################
-- 
2.5.5