From patchwork Fri Mar 6 17:50:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 11424603 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5858414E3 for ; Fri, 6 Mar 2020 17:50:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A57A2072A for ; Fri, 6 Mar 2020 17:50:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583517020; bh=ZYkeemMkEZkqZyMgk/Znaj3Jks2xSY1tmb7tearz2v0=; h=From:To:Cc:Subject:Date:List-ID:From; b=dUDJKQFMejTGClAWrWlYgquKMGptjztKYKB8Qw4VbBxkUeDBDBN/f1TxGaU1jXS2s HmYHdGhGBNd6svGWouvo5NXjAAz2nmA/lwEjA3UpuEbL6w+Y817q5OxigAfR+ZQQWB unJI2RL8Wa1RqO/1mWBjOEeJUnJ8ldhwbtmEPOhg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726237AbgCFRuT (ORCPT ); Fri, 6 Mar 2020 12:50:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:44046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725835AbgCFRuT (ORCPT ); Fri, 6 Mar 2020 12:50:19 -0500 Received: from debian6.Home (bl8-197-74.dsl.telepac.pt [85.241.197.74]) (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 2EB3520656; Fri, 6 Mar 2020 17:50:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583517018; bh=ZYkeemMkEZkqZyMgk/Znaj3Jks2xSY1tmb7tearz2v0=; h=From:To:Cc:Subject:Date:From; b=uISXpbAcOgseo3ZuhIDnNAvVG5wR1Bw/dn21IdP0f52Tde/qIRKW8jlTWVbFk02I7 i6H01MdgxXmLVsUnkxiorOB4zT8prmIoW8LIH3TG/DKAMRsHadxDMSVZH9goUzKqtu pW+WpqXa4GSEwXWc0d/jOKupZzByqyF/Y8+1C1HQ= From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Cc: josef@toxicpanda.com Subject: [PATCH v2 1/4] Btrfs: fix missing file extent item for hole after ranged fsync Date: Fri, 6 Mar 2020 17:50:16 +0000 Message-Id: <20200306175016.6001-1-fdmanana@kernel.org> X-Mailer: git-send-email 2.11.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Filipe Manana When doing a fast fsync for a range that starts at an offset greater than zero, we can end up with a log that when replayed causes the respective inode miss a file extent item representing a hole if we are not using the NO_HOLES feature. This is because for fast fsyncs we don't log any extents that cover a range different from the one requested in the fsync. Example scenario to trigger it: $ mkfs.btrfs -O ^no-holes -f /dev/sdd $ mount /dev/sdd /mnt # Create a file with a single 256K and fsync it to clear to full sync # bit in the inode - we want the msync below to trigger a fast fsync. $ xfs_io -f -c "pwrite -S 0xab 0 256K" -c "fsync" /mnt/foo # Force a transaction commit and wipe out the log tree. $ sync # Dirty 768K of data, increasing the file size to 1Mb, and flush only # the range from 256K to 512K without updating the log tree # (sync_file_range() does not trigger fsync, it only starts writeback # and waits for it to finish). $ xfs_io -c "pwrite -S 0xcd 256K 768K" /mnt/foo $ xfs_io -c "sync_range -abw 256K 256K" /mnt/foo # Now dirty the range from 768K to 1M again and sync that range. $ xfs_io -c "mmap -w 768K 256K" \ -c "mwrite -S 0xef 768K 256K" \ -c "msync -s 768K 256K" \ -c "munmap" \ /mnt/foo # Mount to replay the log. $ mount /dev/sdd /mnt $ umount /mnt $ btrfs check /dev/sdd Opening filesystem to check... Checking filesystem on /dev/sdd UUID: 482fb574-b288-478e-a190-a9c44a78fca6 [1/7] checking root items [2/7] checking extents [3/7] checking free space cache [4/7] checking fs roots root 5 inode 257 errors 100, file extent discount Found file extent holes: start: 262144, len: 524288 ERROR: errors found in fs roots found 720896 bytes used, error(s) found total csum bytes: 512 total tree bytes: 131072 total fs tree bytes: 32768 total extent tree bytes: 16384 btree space waste bytes: 123514 file data blocks allocated: 589824 referenced 589824 Fix this issue by setting the range start offset to zero when the NO_HOLES feature is not enabled. This results in extra work being done but it gives the guarantee we don't end up with missing holes after replaying the log. Signed-off-by: Filipe Manana --- fs/btrfs/file.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 6ba39f11580c..7b189b9eb228 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2099,9 +2099,14 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) * extent completion for adjacent ranges, and assertion failures during * hole detection. Do this while holding the inode lock, to avoid races * with other tasks. + * + * Also set the range to full if the NO_HOLES feature is not enabled. + * This is to avoid missing file extent items representing holes after + * replaying the log. */ if (test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, - &BTRFS_I(inode)->runtime_flags)) { + &BTRFS_I(inode)->runtime_flags) || + !btrfs_fs_incompat(fs_info, NO_HOLES)) { start = 0; end = LLONG_MAX; }