ext4: set lazytime on remount if MS_LAZYTIME is set by mount

ext4: set lazytime on remount if MS_LAZYTIME is set by mount

commit a2fd66d069d86d793e9d39d4079b96f46d13f237 upstream.

Newer versions of mount parse the lazytime feature and pass it to the
mount system call via the flags field in the mount system call,
removing the lazytime string from the mount options list.  So we need
to check for the presence of MS_LAZYTIME and set it in sb->s_flags in
order for this flag to be set on a remount.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>