f2fs: setting discard option in parse_options()

For the first mount of f2fs image with realtime discard option, we will
disable discard option if device is not supported, but for remount
operation, our discard option can still be set, this should be avoided.

This patch moves configuring of discard option to parse_options() to fix
this issue.
Signed-off-by: NChao Yu <chao2.yu@samsung.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -258,6 +258,7 @@ static void init_once(void *foo)
 static int parse_options(struct super_block *sb, char *options)
 {
 	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct request_queue *q;
 	substring_t args[MAX_OPT_ARGS];
 	char *p, *name;
 	int arg = 0;
@@ -302,7 +303,14 @@ static int parse_options(struct super_block *sb, char *options)
 				return -EINVAL;
 			break;
 		case Opt_discard:
-			set_opt(sbi, DISCARD);
+			q = bdev_get_queue(sb->s_bdev);
+			if (blk_queue_discard(q)) {
+				set_opt(sbi, DISCARD);
+			} else {
+				f2fs_msg(sb, KERN_WARNING,
+					"mounting with \"discard\" option, but "
+					"the device does not support discard");
+			}
 			break;
 		case Opt_noheap:
 			set_opt(sbi, NOHEAP);
@@ -1235,16 +1243,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 		proc_create_data("segment_info", S_IRUGO, sbi->s_proc,
 				 &f2fs_seq_segment_info_fops, sb);
 
-	if (test_opt(sbi, DISCARD)) {
-		struct request_queue *q = bdev_get_queue(sb->s_bdev);
-		if (!blk_queue_discard(q)) {
-			f2fs_msg(sb, KERN_WARNING,
-					"mounting with \"discard\" option, but "
-					"the device does not support discard");
-			clear_opt(sbi, DISCARD);
-		}
-	}
-
 	sbi->s_kobj.kset = f2fs_kset;
 	init_completion(&sbi->s_kobj_unregister);
 	err = kobject_init_and_add(&sbi->s_kobj, &f2fs_ktype, NULL,