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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 DE0F3C433E0 for ; Mon, 29 Jun 2020 22:04:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9E6B2065D for ; Mon, 29 Jun 2020 22:04:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593468274; bh=L/UZd5a6IcXtfLJej821jWf2eMKINcIs7qnt+UN8m3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MmbbvwZW/ro9N+xdQxxSvIV7mf06D2DCugM4ZPI69oLx+c6MDtKI+VAv7Z6sosWL4 ZLVIon/ZollNbL9f0TJLvFkx/snEeWNTfC/LMljIlP37K4sJDp5lxhFHSsu5wSub1D lDW1zlXW9ShrpP8JC0IB1q4kfp+MaMPAJmDCqpeo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404429AbgF2WEc (ORCPT ); Mon, 29 Jun 2020 18:04:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:56906 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726180AbgF2SfW (ORCPT ); Mon, 29 Jun 2020 14:35:22 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1BA6A247B3; Mon, 29 Jun 2020 15:21:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593444115; bh=L/UZd5a6IcXtfLJej821jWf2eMKINcIs7qnt+UN8m3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iHzGEEX5U7eFucDSiqKTbxkbLUmuq/X6OFZjQRTpONApPbe2hk6igrdKDEiQenmHz wCd5V7ePvN/ZGcaZ2aguVhFvjoljYmLP9OTYtKtGGKIjOfkJpW/aVFEPMc7cjSAOsy v+D1DGsH5OX0xejXLkZYo7rM2y9RscuOZvJnLs54= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Filipe Manana , David Sterba , Greg Kroah-Hartman Subject: [PATCH 5.7 227/265] btrfs: fix RWF_NOWAIT write not failling when we need to cow Date: Mon, 29 Jun 2020 11:17:40 -0400 Message-Id: <20200629151818.2493727-228-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629151818.2493727-1-sashal@kernel.org> References: <20200629151818.2493727-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.7.7-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.7.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.7.7-rc1 X-KernelTest-Deadline: 2020-07-01T15:14+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Filipe Manana commit 260a63395f90f67d6ab89e4266af9e3dc34a77e9 upstream. If we attempt to do a RWF_NOWAIT write against a file range for which we can only do NOCOW for a part of it, due to the existence of holes or shared extents for example, we proceed with the write as if it were possible to NOCOW the whole range. Example: $ mkfs.btrfs -f /dev/sdb $ mount /dev/sdb /mnt $ touch /mnt/sdj/bar $ chattr +C /mnt/sdj/bar $ xfs_io -d -c "pwrite -S 0xab -b 256K 0 256K" /mnt/bar wrote 262144/262144 bytes at offset 0 256 KiB, 1 ops; 0.0003 sec (694.444 MiB/sec and 2777.7778 ops/sec) $ xfs_io -c "fpunch 64K 64K" /mnt/bar $ sync $ xfs_io -d -c "pwrite -N -V 1 -b 128K -S 0xfe 0 128K" /mnt/bar wrote 131072/131072 bytes at offset 0 128 KiB, 1 ops; 0.0007 sec (160.051 MiB/sec and 1280.4097 ops/sec) This last write should fail with -EAGAIN since the file range from 64K to 128K is a hole. On xfs it fails, as expected, but on ext4 it currently succeeds because apparently it is expensive to check if there are extents allocated for the whole range, but I'll check with the ext4 people. Fix the issue by checking if check_can_nocow() returns a number of NOCOW'able bytes smaller then the requested number of bytes, and if it does return -EAGAIN. Fixes: edf064e7c6fec3 ("btrfs: nowait aio support") CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/file.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 484803f8b2290..52d565ff66e2d 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1912,18 +1912,29 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, pos = iocb->ki_pos; count = iov_iter_count(from); if (iocb->ki_flags & IOCB_NOWAIT) { + size_t nocow_bytes = count; + /* * We will allocate space in case nodatacow is not set, * so bail */ if (!(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)) || - check_can_nocow(BTRFS_I(inode), pos, &count) <= 0) { + check_can_nocow(BTRFS_I(inode), pos, &nocow_bytes) <= 0) { inode_unlock(inode); return -EAGAIN; } /* check_can_nocow() locks the snapshot lock on success */ btrfs_drew_write_unlock(&root->snapshot_lock); + /* + * There are holes in the range or parts of the range that must + * be COWed (shared extents, RO block groups, etc), so just bail + * out. + */ + if (nocow_bytes < count) { + inode_unlock(inode); + return -EAGAIN; + } } current->backing_dev_info = inode_to_bdi(inode); -- 2.25.1