tmpfs: cleanup mpol_parse_str()

mpol_parse_str() made lots 'err' variable related bug.  Because it is ugly
and reviewing unfriendly.

This patch simplifies it.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ravikiran Thirumalai <kiran@scalex86.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -2195,8 +2195,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
 			char *rest = nodelist;
 			while (isdigit(*rest))
 				rest++;
-			if (!*rest)
-				err = 0;
+			if (*rest)
+				goto out;
 		}
 		break;
 	case MPOL_INTERLEAVE:
@@ -2205,7 +2205,6 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
 		 */
 		if (!nodelist)
 			nodes = node_states[N_HIGH_MEMORY];
-		err = 0;
 		break;
 	case MPOL_LOCAL:
 		/*
@@ -2214,7 +2213,6 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
 		if (nodelist)
 			goto out;
 		mode = MPOL_PREFERRED;
-		err = 0;
 		break;
 	case MPOL_DEFAULT:
 		/*
@@ -2229,7 +2227,6 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
 		 */
 		if (!nodelist)
 			goto out;
-		err = 0;
 	}
 
 	mode_flags = 0;
@@ -2243,13 +2240,14 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
 		else if (!strcmp(flags, "relative"))
 			mode_flags |= MPOL_F_RELATIVE_NODES;
 		else
-			err = 1;
+			goto out;
 	}
 
 	new = mpol_new(mode, mode_flags, &nodes);
 	if (IS_ERR(new))
-		err = 1;
-	else {
+		goto out;
+
+	{
 		int ret;
 		NODEMASK_SCRATCH(scratch);
 		if (scratch) {
@@ -2260,13 +2258,15 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
 			ret = -ENOMEM;
 		NODEMASK_SCRATCH_FREE(scratch);
 		if (ret) {
-			err = 1;
 			mpol_put(new);
-		} else if (no_context) {
-			/* save for contextualization */
-			new->w.user_nodemask = nodes;
+			goto out;
 		}
 	}
+	err = 0;
+	if (no_context) {
+		/* save for contextualization */
+		new->w.user_nodemask = nodes;
+	}
 
 out:
 	/* Restore string for error message */