affs: handle match_strdup failure

fs/affs/super.c (parse_options): Remove useless initialization.  Handle
match_strdup failure.
Signed-off-by: Jim Meyering <meyering@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/affs/super.c

@@ -199,7 +199,6 @@ parse_options(char *options, uid_t *uid, gid_t *gid, int *mode, int *reserved, s
 		case Opt_prefix:
 			/* Free any previous prefix */
 			kfree(*prefix);
-			*prefix = NULL;
 			*prefix = match_strdup(&args[0]);
 			if (!*prefix)
 				return 0;
@@ -233,6 +232,8 @@ parse_options(char *options, uid_t *uid, gid_t *gid, int *mode, int *reserved, s
 			break;
 		case Opt_volume: {
 			char *vol = match_strdup(&args[0]);
+			if (!vol)
+				return 0;
 			strlcpy(volume, vol, 32);
 			kfree(vol);
 			break;