ocfs2: enable ocfs2_listxattr for special files

For special files in S_IFBLK/S_IFCHR/S_IFIFO type, we already have
ocfs2_setattr and ocfs2_getattr enabled.  It's confusing for user space if
it can use setattr/getattr to control one attribute appointed but can not
list attributes using listxattr for above type files:

$ mknod /mnt/b b 0 0
$ setfattr -h -n trusted.name -v 0xbabe /mnt/b
$ getfattr -n trusted.name  /mnt/b
getfattr: Removing leading '/' from absolute path names
trusted.name=0sur4=

$ getfattr -m trusted  /mnt/b
$

Fix it by enabling ocfs2_listxattr for ocfs2_special_file_iops.  After the
commit, fstests/generic/062 will pass.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Su Yue <[email protected]>
Acked-by: Joseph Qi <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Changwei Ge <[email protected]>
Cc: Gang He <[email protected]>
Cc: Jun Piao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Damenly

fs/ocfs2/file.c

@@ -2763,6 +2763,7 @@ const struct inode_operations ocfs2_file_iops = {
 const struct inode_operations ocfs2_special_file_iops = {
 	.setattr	= ocfs2_setattr,
 	.getattr	= ocfs2_getattr,
+	.listxattr	= ocfs2_listxattr,
 	.permission	= ocfs2_permission,
 	.get_inode_acl	= ocfs2_iop_get_acl,
 	.set_acl	= ocfs2_iop_set_acl,