From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93123C3A59E for ; Tue, 3 Sep 2019 00:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 68EE921881 for ; Tue, 3 Sep 2019 00:01:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727864AbfICAAL (ORCPT ); Mon, 2 Sep 2019 20:00:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54968 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726845AbfICAAK (ORCPT ); Mon, 2 Sep 2019 20:00:10 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 595C5307D90D; Tue, 3 Sep 2019 00:00:10 +0000 (UTC) Received: from dustball.brq.redhat.com (unknown [10.43.17.163]) by smtp.corp.redhat.com (Postfix) with ESMTP id BFA18608AB; Tue, 3 Sep 2019 00:00:07 +0000 (UTC) From: Jan Stancek To: hirofumi@mail.parknet.co.jp Cc: linux-kernel@vger.kernel.org, jstancek@redhat.com Subject: [PATCH] fat: fix corruption in fat_alloc_new_dir() Date: Tue, 3 Sep 2019 01:59:36 +0200 Message-Id: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Tue, 03 Sep 2019 00:00:10 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sb_getblk does not guarantee that buffer_head is uptodate. If there is async read running in parallel for same buffer_head, it can overwrite just initialized msdos_dir_entry, leading to corruption: FAT-fs (loop0): error, corrupted directory (invalid entries) FAT-fs (loop0): Filesystem has been set read-only This can happen for example during LTP statx04, which creates loop device, formats it (mkfs.vfat), mounts it and immediately creates a new directory. In parallel, systemd-udevd is probing new block device, which leads to async read. do_mkdirat ksys_read vfs_mkdir vfs_read vfat_mkdir __vfs_read fat_alloc_new_dir new_sync_read /* init de[0], de[1] */ blkdev_read_iter generic_file_read_iter generic_file_buffered_read blkdev_readpage block_read_full_page Faster reproducer (based on LTP statx04): --------------------------------- 8< --------------------------------- int main(void) { int i, j, ret, fd, loop_fd, ctrl_fd; int loop_num; char loopdev[256], tmp[256], testfile[256]; mkdir("/tmp/mntpoint", 0777); for (i = 0; ; i++) { printf("Iteration: %d\n", i); sprintf(testfile, "/tmp/test.img.%d", getpid()); ctrl_fd = open("/dev/loop-control", O_RDWR); loop_num = ioctl(ctrl_fd, LOOP_CTL_GET_FREE); close(ctrl_fd); sprintf(loopdev, "/dev/loop%d", loop_num); fd = open(testfile, O_WRONLY|O_CREAT|O_TRUNC, 0600); fallocate(fd, 0, 0, 256*1024*1024); close(fd); fd = open(testfile, O_RDWR); loop_fd = open(loopdev, O_RDWR); ioctl(loop_fd, LOOP_SET_FD, fd); close(loop_fd); close(fd); sprintf(tmp, "mkfs.vfat %s", loopdev); system(tmp); mount(loopdev, "/tmp/mntpoint", "vfat", 0, NULL); for (j = 0; j < 200; j++) { sprintf(tmp, "/tmp/mntpoint/testdir%d", j); ret = mkdir(tmp, 0777); if (ret) { perror("mkdir"); break; } } umount("/tmp/mntpoint"); loop_fd = open(loopdev, O_RDWR); ioctl(loop_fd, LOOP_CLR_FD, fd); close(loop_fd); unlink(testfile); if (ret) break; } return 0; } --------------------------------- 8< --------------------------------- Issue triggers within minute on HPE Apollo 70 (arm64, 64GB RAM, 224 CPUs). Signed-off-by: Jan Stancek Cc: OGAWA Hirofumi --- fs/fat/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fat/dir.c b/fs/fat/dir.c index 1bda2ab6745b..474fd6873ec8 100644 --- a/fs/fat/dir.c +++ b/fs/fat/dir.c @@ -1149,7 +1149,7 @@ int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts) goto error; blknr = fat_clus_to_blknr(sbi, cluster); - bhs[0] = sb_getblk(sb, blknr); + bhs[0] = sb_bread(sb, blknr); if (!bhs[0]) { err = -ENOMEM; goto error_free; -- 1.8.3.1