From patchwork Tue Feb 16 14:40:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: fdmanana@kernel.org X-Patchwork-Id: 383701 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 8FB2DC433DB for ; Tue, 16 Feb 2021 14:42:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D01D64E02 for ; Tue, 16 Feb 2021 14:42:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230117AbhBPOm1 (ORCPT ); Tue, 16 Feb 2021 09:42:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:36198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230131AbhBPOmR (ORCPT ); Tue, 16 Feb 2021 09:42:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0086764DF5; Tue, 16 Feb 2021 14:41:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613486496; bh=r5SKLNl9WSrYnlql4Vrvet2zV2hcBh65M0I4PVxdgHE=; h=From:To:Cc:Subject:Date:From; b=PbAeZnvgaYvIPO+FoWR0coptqA/ebtkoqyxxMtKeKENkTNe/igUj4NsFpaMGBlHgq rHGfLmlMBJiwhFCxT97wR5PCffhZF4lV4CcqHw3qbinKgfGWV11W1ecHVdcuWIKhuq tLWBk/5v1yQ5CchszWRC7mGRHDGWstgztQoxBc02G/pZDbGLShu65GgdHoVhpO1LIo K7kKRHg/0EvP72dKN7Mjm4i8QxxZVw7ih8iXmwUJvKiyDpqLbPiCv01WmafQrvS42g ddgZO7kL1+V1th9Bb4Ddh9KbFvVr9QGFn9SeQMzbtgAz2mZsiEnLtoGFuJM8WLayfs XF58LxpeQ6q2Q== From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org, dsterba@suse.cz, Filipe Manana Subject: [PATCH 5.10.x] btrfs: fix crash after non-aligned direct IO write with O_DSYNC Date: Tue, 16 Feb 2021 14:40:31 +0000 Message-Id: <94663c8a2172dc96b760d356a538d45c36f46040.1613062764.git.fdmanana@suse.com> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Filipe Manana Whenever we attempt to do a non-aligned direct IO write with O_DSYNC, we end up triggering an assertion and crashing. Example reproducer: $ cat test.sh #!/bin/bash DEV=/dev/sdj MNT=/mnt/sdj mkfs.btrfs -f $DEV > /dev/null mount $DEV $MNT # Do a direct IO write with O_DSYNC into a non-aligned range... xfs_io -f -d -s -c "pwrite -S 0xab -b 64K 1111 64K" $MNT/foobar umount $MNT When running the reproducer an assertion fails and produces the following trace: [ 2418.403134] assertion failed: !current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA, in fs/btrfs/space-info.c:1467 [ 2418.403745] ------------[ cut here ]------------ [ 2418.404306] kernel BUG at fs/btrfs/ctree.h:3286! [ 2418.404862] invalid opcode: 0000 [#2] PREEMPT SMP DEBUG_PAGEALLOC PTI [ 2418.405451] CPU: 1 PID: 64705 Comm: xfs_io Tainted: G D 5.10.15-btrfs-next-87 #1 [ 2418.406026] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 2418.407228] RIP: 0010:assertfail.constprop.0+0x18/0x26 [btrfs] [ 2418.407835] Code: e6 48 c7 (...) [ 2418.409078] RSP: 0018:ffffb06080d13c98 EFLAGS: 00010246 [ 2418.409696] RAX: 000000000000006c RBX: ffff994c1debbf08 RCX: 0000000000000000 [ 2418.410302] RDX: 0000000000000000 RSI: 0000000000000027 RDI: 00000000ffffffff [ 2418.410904] RBP: ffff994c21770000 R08: 0000000000000000 R09: 0000000000000000 [ 2418.411504] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000010000 [ 2418.412111] R13: ffff994c22198400 R14: ffff994c21770000 R15: 0000000000000000 [ 2418.412713] FS: 00007f54fd7aff00(0000) GS:ffff994d35200000(0000) knlGS:0000000000000000 [ 2418.413326] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2418.413933] CR2: 000056549596d000 CR3: 000000010b928003 CR4: 0000000000370ee0 [ 2418.414528] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 2418.415109] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 2418.415669] Call Trace: [ 2418.416254] btrfs_reserve_data_bytes.cold+0x22/0x22 [btrfs] [ 2418.416812] btrfs_check_data_free_space+0x4c/0xa0 [btrfs] [ 2418.417380] btrfs_buffered_write+0x1b0/0x7f0 [btrfs] [ 2418.418315] btrfs_file_write_iter+0x2a9/0x770 [btrfs] [ 2418.418920] new_sync_write+0x11f/0x1c0 [ 2418.419430] vfs_write+0x2bb/0x3b0 [ 2418.419972] __x64_sys_pwrite64+0x90/0xc0 [ 2418.420486] do_syscall_64+0x33/0x80 [ 2418.420979] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 2418.421486] RIP: 0033:0x7f54fda0b986 [ 2418.421981] Code: 48 c7 c0 (...) [ 2418.423019] RSP: 002b:00007ffc40569c38 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 [ 2418.423547] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f54fda0b986 [ 2418.424075] RDX: 0000000000010000 RSI: 000056549595e000 RDI: 0000000000000003 [ 2418.424596] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000400 [ 2418.425119] R10: 0000000000000400 R11: 0000000000000246 R12: 00000000ffffffff [ 2418.425644] R13: 0000000000000400 R14: 0000000000010000 R15: 0000000000000000 [ 2418.426148] Modules linked in: btrfs blake2b_generic (...) [ 2418.429540] ---[ end trace ef2aeb44dc0afa34 ]--- 1) At btrfs_file_write_iter() we set current->journal_info to BTRFS_DIO_SYNC_STUB; 2) We then call __btrfs_direct_write(), which calls btrfs_direct_IO(); 3) We can't do the direct IO write because it starts at a non-aligned offset (1111). So at btrfs_direct_IO() we return -EINVAL (coming from check_direct_IO() which does the alignment check), but we leave current->journal_info set to BTRFS_DIO_SYNC_STUB - we only clear it at btrfs_dio_iomap_begin(), because we assume we always get there; 4) Then at __btrfs_direct_write() we see that the attempt to do the direct IO write was not successful, 0 bytes written, so we fallback to a buffered write by calling btrfs_buffered_write(); 5) There we call btrfs_check_data_free_space() which in turn calls btrfs_alloc_data_chunk_ondemand() and that calls btrfs_reserve_data_bytes() with flush == BTRFS_RESERVE_FLUSH_DATA; 6) Then at btrfs_reserve_data_bytes() we have current->journal_info set to BTRFS_DIO_SYNC_STUB, therefore not NULL, and flush has the value BTRFS_RESERVE_FLUSH_DATA, triggering the second assertion: int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes, enum btrfs_reserve_flush_enum flush) { struct btrfs_space_info *data_sinfo = fs_info->data_sinfo; int ret; ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA || flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE); ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA); (...) So fix that by setting the journal to NULL whenever check_direct_IO() returns a failure. This bug only affects 5.10 kernels, and the regression was introduced in 5.10-rc1 by commit 0eb79294dbe328 ("btrfs: dio iomap DSYNC workaround"). The bug does not exist in 5.11 kernels due to commit ecfdc08b8cc65d ("btrfs: remove dio iomap DSYNC workaround"), which depends on a large patchset that went into the merge window for 5.11. So this is a fix only for 5.10.x stable kernels, as there are people hitting this bug. Fixes: 0eb79294dbe328 ("btrfs: dio iomap DSYNC workaround") CC: stable@vger.kernel.org # 5.10 (and only 5.10) CC: David Sterba Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1181605 Signed-off-by: Filipe Manana --- fs/btrfs/inode.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index acc47e2ffb46..b536d21541a9 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8026,8 +8026,12 @@ ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) bool relock = false; ssize_t ret; - if (check_direct_IO(fs_info, iter, offset)) + if (check_direct_IO(fs_info, iter, offset)) { + ASSERT(current->journal_info == NULL || + current->journal_info == BTRFS_DIO_SYNC_STUB); + current->journal_info = NULL; return 0; + } count = iov_iter_count(iter); if (iov_iter_rw(iter) == WRITE) {