shmem_parse_options(): take handling a single option into a helper

mechanical move.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

mm/shmem.c

@@ -3363,40 +3363,13 @@ static const struct export_operations shmem_export_ops = {
 	.fh_to_dentry	= shmem_fh_to_dentry,
 };
 
-static int shmem_parse_options(char *options, struct shmem_options *ctx)
+static int shmem_parse_one(struct shmem_options *ctx, char *opt, char *value)
 {
-	char *this_char, *value, *rest;
+	char *rest;
 	uid_t uid;
 	gid_t gid;
 
-	while (options != NULL) {
-		this_char = options;
-		for (;;) {
-			/*
-			 * NUL-terminate this option: unfortunately,
-			 * mount options form a comma-separated list,
-			 * but mpol's nodelist may also contain commas.
-			 */
-			options = strchr(options, ',');
-			if (options == NULL)
-				break;
-			options++;
-			if (!isdigit(*options)) {
-				options[-1] = '\0';
-				break;
-			}
-		}
-		if (!*this_char)
-			continue;
-		if ((value = strchr(this_char,'=')) != NULL) {
-			*value++ = 0;
-		} else {
-			pr_err("tmpfs: No value for mount option '%s'\n",
-			       this_char);
-			goto error;
-		}
-
-		if (!strcmp(this_char,"size")) {
+	if (!strcmp(opt, "size")) {
 		unsigned long long size;
 		size = memparse(value,&rest);
 		if (*rest == '%') {
@@ -3409,28 +3382,28 @@ static int shmem_parse_options(char *options, struct shmem_options *ctx)
 			goto bad_val;
 		ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
 		ctx->seen |= SHMEM_SEEN_BLOCKS;
-		} else if (!strcmp(this_char,"nr_blocks")) {
+	} else if (!strcmp(opt, "nr_blocks")) {
 		ctx->blocks = memparse(value, &rest);
 		if (*rest)
 			goto bad_val;
 		ctx->seen |= SHMEM_SEEN_BLOCKS;
-		} else if (!strcmp(this_char,"nr_inodes")) {
+	} else if (!strcmp(opt, "nr_inodes")) {
 		ctx->inodes = memparse(value, &rest);
 		if (*rest)
 			goto bad_val;
 		ctx->seen |= SHMEM_SEEN_INODES;
-		} else if (!strcmp(this_char,"mode")) {
+	} else if (!strcmp(opt, "mode")) {
 		ctx->mode = simple_strtoul(value, &rest, 8) & 07777;
 		if (*rest)
 			goto bad_val;
-		} else if (!strcmp(this_char,"uid")) {
+	} else if (!strcmp(opt, "uid")) {
 		uid = simple_strtoul(value, &rest, 0);
 		if (*rest)
 			goto bad_val;
 		ctx->uid = make_kuid(current_user_ns(), uid);
 		if (!uid_valid(ctx->uid))
 			goto bad_val;
-		} else if (!strcmp(this_char,"gid")) {
+	} else if (!strcmp(opt, "gid")) {
 		gid = simple_strtoul(value, &rest, 0);
 		if (*rest)
 			goto bad_val;
@@ -3438,7 +3411,7 @@ static int shmem_parse_options(char *options, struct shmem_options *ctx)
 		if (!gid_valid(ctx->gid))
 			goto bad_val;
 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
-		} else if (!strcmp(this_char, "huge")) {
+	} else if (!strcmp(opt, "huge")) {
 		int huge;
 		huge = shmem_parse_huge(value);
 		if (huge < 0)
@@ -3450,22 +3423,59 @@ static int shmem_parse_options(char *options, struct shmem_options *ctx)
 		ctx->seen |= SHMEM_SEEN_HUGE;
 #endif
 #ifdef CONFIG_NUMA
-		} else if (!strcmp(this_char,"mpol")) {
+	} else if (!strcmp(opt, "mpol")) {
 		mpol_put(ctx->mpol);
 		ctx->mpol = NULL;
 		if (mpol_parse_str(value, &ctx->mpol))
 			goto bad_val;
 #endif
 	} else {
-			pr_err("tmpfs: Bad mount option %s\n", this_char);
-			goto error;
-		}
+		pr_err("tmpfs: Bad mount option %s\n", opt);
+		return -EINVAL;
 	}
 	return 0;
 
 bad_val:
 	pr_err("tmpfs: Bad value '%s' for mount option '%s'\n",
-	       value, this_char);
+	       value, opt);
+	return -EINVAL;
+}
+
+static int shmem_parse_options(char *options, struct shmem_options *ctx)
+{
+	char *this_char, *value;
+
+	while (options != NULL) {
+		this_char = options;
+		for (;;) {
+			/*
+			 * NUL-terminate this option: unfortunately,
+			 * mount options form a comma-separated list,
+			 * but mpol's nodelist may also contain commas.
+			 */
+			options = strchr(options, ',');
+			if (options == NULL)
+				break;
+			options++;
+			if (!isdigit(*options)) {
+				options[-1] = '\0';
+				break;
+			}
+		}
+		if (!*this_char)
+			continue;
+		if ((value = strchr(this_char,'=')) != NULL) {
+			*value++ = 0;
+		} else {
+			pr_err("tmpfs: No value for mount option '%s'\n",
+			       this_char);
+			goto error;
+		}
+		if (shmem_parse_one(ctx, this_char, value) < 0)
+			goto error;
+	}
+	return 0;
+
 error:
 	mpol_put(ctx->mpol);
 	ctx->mpol = NULL;