[PATCH 2/4] usertools: add option to change mount point owner

[Dmitry Kozlyuk]

Per mount(8), the previous owner and mode of the mount point
become invisible as long as this filesystem remains mounted.
Because dpdk-hugepages.py must be run as root,
the new owner would be root.
This is undesirable if the hugepage directory is being set up
by the administrator for an unprivileged user.
Add --owner/-o option to set the owner after mounting.
The benefit over calling chown directly after the script
is that the user does not need to care about this detail
of mount command operation.

Signed-off-by: Dmitry Kozlyuk <dkozlyuk at nvidia.com>
---
 usertools/dpdk-hugepages.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/usertools/dpdk-hugepages.py b/usertools/dpdk-hugepages.py
index 8bab086a2f..1e01ac3d9f 100755
--- a/usertools/dpdk-hugepages.py
+++ b/usertools/dpdk-hugepages.py
@@ -170,7 +170,7 @@ def get_mountpoints():
     return mounted
 
 
-def mount_huge(pagesize, mountpoint):
+def mount_huge(pagesize, mountpoint, owner):
     '''Mount the huge TLB file system'''
     if mountpoint in get_mountpoints():
         print(mountpoint, "already mounted")
@@ -180,6 +180,8 @@ def mount_huge(pagesize, mountpoint):
         cmd += ' -o pagesize={}'.format(pagesize * 1024)
     cmd += ' nodev ' + mountpoint
     os.system(cmd)
+    if owner:
+        os.system('chown {} {}'.format(owner, mountpoint))
 
 
 def umount_huge(mountpoint):
@@ -234,6 +236,11 @@ def main():
         metavar='DIR',
         default=HUGE_MOUNT,
         help='mount point')
+    parser.add_argument(
+        '--owner',
+        '-o',
+        metavar='USER:GROUP',
+        help='change the mounted directory owner')
     parser.add_argument(
         '--node', '-n', help='select numa node to reserve pages on')
     parser.add_argument(
@@ -279,7 +286,7 @@ def main():
         reserve_pages(
             int(reserve_kb / pagesize_kb), pagesize_kb, node=args.node)
     if args.mount:
-        mount_huge(pagesize_kb, args.directory)
+        mount_huge(pagesize_kb, args.directory, args.owner)
     if args.show:
         show_pages()
         print()
-- 
2.25.1