f2fs: free meta pages if sanity check for ckpt is failed

This fixes missing freeing meta pages in the error case.
Tested-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -770,7 +770,7 @@ int get_valid_checkpoint(struct f2fs_sb_info *sbi)
 
 	/* Sanity checking of checkpoint */
 	if (sanity_check_ckpt(sbi))
-		goto fail_no_cp;
+		goto free_fail_no_cp;
 
 	if (cur_page == cp1)
 		sbi->cur_cp_pack = 1;
@@ -798,6 +798,9 @@ int get_valid_checkpoint(struct f2fs_sb_info *sbi)
 	f2fs_put_page(cp2, 1);
 	return 0;
 
+free_fail_no_cp:
+	f2fs_put_page(cp1, 1);
+	f2fs_put_page(cp2, 1);
 fail_no_cp:
 	kfree(sbi->ckpt);
 	return -EINVAL;