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

[Zorro Lang <zlang@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 common/rc | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/common/rc b/common/rc
index 51092a0..d5edfef 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 "$content" ];then
+               _fail "Usage: _set_sys_fs_param <mounted_device> <entry> 
<content>"
+       fi
+
+       local dname=$(_short_dev $dev)
+       echo "$content" > /sys/fs/${FSTYP}/${dname}/${entry}
+}
+
 init_rc
 
 
################################################################################
-- 
2.5.5