knfsd: nfsd4: silence a compiler warning in ACL code

Silence a compiler warning in the ACL code, and add a comment making clear the
initialization serves no other purpose.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/nfsd/nfs4acl.c

@@ -183,8 +183,13 @@ static void
 summarize_posix_acl(struct posix_acl *acl, struct posix_acl_summary *pas)
 {
 	struct posix_acl_entry *pa, *pe;
-	pas->users = 0;
-	pas->groups = 0;
+
+	/*
+	 * Only pas.users and pas.groups need initialization; previous
+	 * posix_acl_valid() calls ensure that the other fields will be
+	 * initialized in the following loop.  But, just to placate gcc:
+	 */
+	memset(pas, 0, sizeof(*pas));
 	pas->mask = 07;
 
 	pe = acl->a_entries + acl->a_count;