f2fs: judge whether discard_unit is section only when have CONFIG_BLK_DEV_ZONED

The current logic, regardless of whether CONFIG_BLK_DEV_ZONED
is enabled or not, will judge whether discard_unit is SECTION,
when f2fs_sb_has_blkzoned.

In fact, when CONFIG_BLK_DEV_ZONED is not enabled, this judgment
is a path that will never be accessed. At this time, -EINVAL will
be returned in the parse_options function, accompanied by the
message "Zoned block device support is not enabled".

Let's wrap this discard_unit judgment with CONFIG_BLK_DEV_ZONED.
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -1294,19 +1294,18 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
 	 * zone alignment optimization. This is optional for host-aware
 	 * devices, but mandatory for host-managed zoned block devices.
 	 */
-#ifndef CONFIG_BLK_DEV_ZONED
-	if (f2fs_sb_has_blkzoned(sbi)) {
-		f2fs_err(sbi, "Zoned block device support is not enabled");
-		return -EINVAL;
-	}
-#endif
 	if (f2fs_sb_has_blkzoned(sbi)) {
+#ifdef CONFIG_BLK_DEV_ZONED
 		if (F2FS_OPTION(sbi).discard_unit !=
 						DISCARD_UNIT_SECTION) {
 			f2fs_info(sbi, "Zoned block device doesn't need small discard, set discard_unit=section by default");
 			F2FS_OPTION(sbi).discard_unit =
 					DISCARD_UNIT_SECTION;
 		}
+#else
+		f2fs_err(sbi, "Zoned block device support is not enabled");
+		return -EINVAL;
+#endif
 	}
 
 #ifdef CONFIG_F2FS_FS_COMPRESSION