From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1EDF87347F for ; Thu, 6 Jun 2024 22:55:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717714529; cv=none; b=ikntIj0MBtc7O00tD1oXwfFhWh0urza9UEgv49VCvFVvJDboLnnZDpMeIi2GYa/IHL8cus+3dOVuUzzGgC0BC/7E1p0GE4q4QRfN5uyjSQluf775bgTZaZQC6N0wkZfVHlq1NmG0WGmvP6CtpJNIbrr99a8+vaUwKF3MhKPG2qU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717714529; c=relaxed/simple; bh=LlL9ySvgbQ7LNKW0skHyARbXcYmvl7vJYRiAY1O5mqg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=r2K+xFlJMAugieyJam/F3UVCI/tZ+grvxESomQNFXdNI8pEujrUiBsIM4HCK5fY/G1b2uX9nOX75JCSF2zkEz1Xe0GCfwKRp+x8rsI6xzQ3wWc8gB/M/jn1Mp2p8dR7wsL1+s+SZAzcgy4OcS1FyhexLHzfLXWtg+n2RazFLZEg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=deLoZS7U; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="deLoZS7U" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DB13C2BD10; Thu, 6 Jun 2024 22:55:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717714526; bh=LlL9ySvgbQ7LNKW0skHyARbXcYmvl7vJYRiAY1O5mqg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=deLoZS7UpaG2jTrkpvfbjnB71R1/pVa7jEl9Bbab+rybhGQa7e4JD9Etn/S76vWNb +dvGfr78rqA1Gwy0ReSQmh8Ove6ftcrCJUZr6rnlUSGfhtFA+j4DtZBsshwojWQcIu nshYfogM0fUDtNhhVNSK34BveUIlV4UAVM9rBSI5ar0H09btS7nXf23JO6kH2cNn+Y NtW8wHgeH1rxpQag2x32nMVrdv/DcJjDZW90mEkC/d+fzabNXoalrCSHng7nQdCZtz 4vf7GjXEJBGhYXHfsSAtxdTGAiTJvTiCcS2o8oTgJi7DDw/0XcpJadNKlURHUmWAd/ sW0iUwIV7BRRw== Date: Thu, 6 Jun 2024 15:55:26 -0700 From: "Darrick J. Wong" To: Wengang Wang Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH V4] xfs: make sure sb_fdblocks is non-negative Message-ID: <20240606225526.GQ52987@frogsfrogsfrogs> References: <20240606181157.23901-1-wen.gang.wang@oracle.com> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240606181157.23901-1-wen.gang.wang@oracle.com> On Thu, Jun 06, 2024 at 11:11:57AM -0700, Wengang Wang wrote: > A user with a completely full filesystem experienced an unexpected > shutdown when the filesystem tried to write the superblock during > runtime. > kernel shows the following dmesg: > > [ 8.176281] XFS (dm-4): Metadata corruption detected at xfs_sb_write_verify+0x60/0x120 [xfs], xfs_sb block 0x0 > [ 8.177417] XFS (dm-4): Unmount and run xfs_repair > [ 8.178016] XFS (dm-4): First 128 bytes of corrupted metadata buffer: > [ 8.178703] 00000000: 58 46 53 42 00 00 10 00 00 00 00 00 01 90 00 00 XFSB............ > [ 8.179487] 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > [ 8.180312] 00000020: cf 12 dc 89 ca 26 45 29 92 e6 e3 8d 3b b8 a2 c3 .....&E)....;... > [ 8.181150] 00000030: 00 00 00 00 01 00 00 06 00 00 00 00 00 00 00 80 ................ > [ 8.182003] 00000040: 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 82 ................ > [ 8.182004] 00000050: 00 00 00 01 00 64 00 00 00 00 00 04 00 00 00 00 .....d.......... > [ 8.182004] 00000060: 00 00 64 00 b4 a5 02 00 02 00 00 08 00 00 00 00 ..d............. > [ 8.182005] 00000070: 00 00 00 00 00 00 00 00 0c 09 09 03 17 00 00 19 ................ > [ 8.182008] XFS (dm-4): Corruption of in-memory data detected. Shutting down filesystem > [ 8.182010] XFS (dm-4): Please unmount the filesystem and rectify the problem(s) > > When xfs_log_sb writes super block to disk, b_fdblocks is fetched from > m_fdblocks without any lock. As m_fdblocks can experience a positive -> > negative -> positive changing when the FS reaches fullness (see > xfs_mod_fdblocks). So there is a chance that sb_fdblocks is negative, and > because sb_fdblocks is type of unsigned long long, it reads super big. > And sb_fdblocks being bigger than sb_dblocks is a problem during log > recovery, xfs_validate_sb_write() complains. > > Fix: > As sb_fdblocks will be re-calculated during mount when lazysbcount is > enabled, We just need to make xfs_validate_sb_write() happy -- make sure > sb_fdblocks is not nenative. This patch also takes care of other percpu > counters in xfs_log_sb. > > Signed-off-by: Wengang Wang Seems fine to me, Reviewed-by: Darrick J. Wong --D > --- > V3 -> V4: takes care of other percpu counters > V2 -> V3: break the line to ensure it isn't overly long > V1 -> V2: add problem symptoms in patch description. > --- > fs/xfs/libxfs/xfs_sb.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c > index 09e4bf949bf8..6b56f0f6d4c1 100644 > --- a/fs/xfs/libxfs/xfs_sb.c > +++ b/fs/xfs/libxfs/xfs_sb.c > @@ -1038,11 +1038,12 @@ xfs_log_sb( > * and hence we don't need have to update it here. > */ > if (xfs_has_lazysbcount(mp)) { > - mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount); > + mp->m_sb.sb_icount = percpu_counter_sum_positive(&mp->m_icount); > mp->m_sb.sb_ifree = min_t(uint64_t, > - percpu_counter_sum(&mp->m_ifree), > + percpu_counter_sum_positive(&mp->m_ifree), > mp->m_sb.sb_icount); > - mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks); > + mp->m_sb.sb_fdblocks = > + percpu_counter_sum_positive(&mp->m_fdblocks); > } > > xfs_sb_to_disk(bp->b_addr, &mp->m_sb); > -- > 2.39.3 (Apple Git-146) > >