From patchwork Sun Nov 6 23:23:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 13033668 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 993FFC433FE for ; Sun, 6 Nov 2022 23:23:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230011AbiKFXXr (ORCPT ); Sun, 6 Nov 2022 18:23:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229798AbiKFXXq (ORCPT ); Sun, 6 Nov 2022 18:23:46 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4FB963AD for ; Sun, 6 Nov 2022 15:23:45 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 3808D21A20 for ; Sun, 6 Nov 2022 23:23:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1667777024; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=XAkDCVCVD6l3FaTsko3fq2IUhGXlSFv/Eprnx1NFPrs=; b=cr+Vct4SIXqfU278KTSit+6sEd9kuIDyKctO878cfhNb+wpxFiGXtFVNpmZrgoWAS9yXAH sQQhA8N/Jc8+zMnVxA5kaxDtCWThdo1CEYIprilbV8U1HNaZ3HFKr5Od/BFuR8xJt5ZYxi Wb8e/Frmx1ql8TsBt5mmczRsBkM8R8I= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 8C521132E7 for ; Sun, 6 Nov 2022 23:23:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 9fmPFf9BaGMzQQAAMHmgww (envelope-from ) for ; Sun, 06 Nov 2022 23:23:43 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH] Revert "btrfs: scrub: use larger block size for data extent scrub" Date: Mon, 7 Nov 2022 07:23:26 +0800 Message-Id: <97622c5c2e2dbb2316901c6ebd9792cbf58385fd.1667776994.git.wqu@suse.com> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This reverts commit 786672e9e1a39a231806313e3c445c236588ceef. [BUG] Since commit 786672e9e1a3 ("btrfs: scrub: use larger block size for data extent scrub"), btrfs scrub no longer reports errors if the corruption is not in the first sector of a STRIPE_LEN. The following script can expose the problem: mkfs.btrfs -f $dev mount $dev $mnt xfs_io -f -c "pwrite -S 0xff 0 8k" $mnt/foobar umount $mnt # 13631488 is the logical bytenr of above 8K extent btrfs-map-logical -l 13631488 -b 4096 $dev mirror 1 logical 13631488 physical 13631488 device /dev/test/scratch1 # Corrupt the 2nd sector of that extent xfs_io -f -c "pwrite -S 0x00 13635584 4k" $dev mount $dev $mnt btrfs scrub start -B $mnt scrub done for 54e63f9f-0c30-4c84-a33b-5c56014629b7 Scrub started: Mon Nov 7 07:18:27 2022 Status: finished Duration: 0:00:00 Total to scrub: 536.00MiB Rate: 0.00B/s Error summary: no errors found <<< [CAUSE] That offending commit enlarge the data extent scrub size from sector size to BTRFS_STRIPE_LEN, to avoid extra scrub_block to be allocated. But unfortunately the data extent scrub is still heavily relying on the fact that there is only one scrub_sector per scrub_block. Thus it will only check the first sector, and ignoring the remaining sectors. Furthermore the error reporting is not able to handle multiple sectors either. [FIX] For now just revert the offending commit. The consequence is just extra memory usage during scrub. We will need a proper change to make the remaining data scrub path to handle multiple sectors before we enlarging the data scrub size. Signed-off-by: Qu Wenruo Reported-by: Li Zhang --- fs/btrfs/scrub.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 06c6626eae3d..e5dbf875f6d9 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2691,17 +2691,11 @@ static int scrub_extent(struct scrub_ctx *sctx, struct map_lookup *map, u8 csum[BTRFS_CSUM_SIZE]; u32 blocksize; - /* - * Block size determines how many scrub_block will be allocated. Here - * we use BTRFS_STRIPE_LEN (64KiB) as default limit, so we won't - * allocate too many scrub_block, while still won't cause too large - * bios for large extents. - */ if (flags & BTRFS_EXTENT_FLAG_DATA) { if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) blocksize = map->stripe_len; else - blocksize = BTRFS_STRIPE_LEN; + blocksize = sctx->fs_info->sectorsize; spin_lock(&sctx->stat_lock); sctx->stat.data_extents_scrubbed++; sctx->stat.data_bytes_scrubbed += len;