[PATCH] md: helper function to match commands written to sysfs files

Commands written to sysfs files may, or my not, be \n terminated.  We want to
accept with case.  For this we use cmd_match.
Signed-off-by: Neil Brown <neilb@suse.de>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

@@ -1525,6 +1525,26 @@ static void md_update_sb(mddev_t * mddev)
 
 }
 
+/* words written to sysfs files may, or my not, be \n terminated.
+ * We want to accept with case. For this we use cmd_match.
+ */
+static int cmd_match(const char *cmd, const char *str)
+{
+	/* See if cmd, written into a sysfs file, matches
+	 * str.  They must either be the same, or cmd can
+	 * have a trailing newline
+	 */
+	while (*cmd && *str && *cmd == *str) {
+		cmd++;
+		str++;
+	}
+	if (*cmd == '\n')
+		cmd++;
+	if (*str || *cmd)
+		return 0;
+	return 1;
+}
+
 struct rdev_sysfs_entry {
 	struct attribute attr;
 	ssize_t (*show)(mdk_rdev_t *, char *);
@@ -1799,7 +1819,7 @@ action_store(mddev_t *mddev, const char *page, size_t len)
 	if (!mddev->pers || !mddev->pers->sync_request)
 		return -EINVAL;
 
-	if (strcmp(page, "idle")==0 || strcmp(page, "idle\n")==0) {
+	if (cmd_match(page, "idle")) {
 		if (mddev->sync_thread) {
 			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 			md_unregister_thread(mddev->sync_thread);
@@ -1812,13 +1832,12 @@ action_store(mddev_t *mddev, const char *page, size_t len)
 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
 	    test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
 		return -EBUSY;
-	if (strcmp(page, "resync")==0 || strcmp(page, "resync\n")==0 ||
-	    strcmp(page, "recover")==0 || strcmp(page, "recover\n")==0)
+	if (cmd_match(page, "resync") || cmd_match(page, "recover"))
 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 	else {
-		if (strcmp(page, "check")==0 || strcmp(page, "check\n")==0)
+		if (cmd_match(page, "check"))
 			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
-		else if (strcmp(page, "repair")!=0 && strcmp(page, "repair\n")!=0)
+		else if (cmd_match(page, "repair"))
 			return -EINVAL;
 		set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
 		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);