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 DB02E2E2679; Mon, 11 Aug 2025 15:49:36 +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=1754927377; cv=none; b=cTzShH5tNb+SJ3/JIac9f45M6WQtxUUpMZKbNGGsL3rMEssiOc733gripkspi8NLg0+DLKknscUPz25jO9+mh5CZ504UGmlLYs6zjQED794/un9IAJkgbE2KF5XfP+yfqH7i2HJx9ll4ONi6zJs42WDg9SGv7ozrl4BuxAlmSFo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754927377; c=relaxed/simple; bh=RopHifErAZ/r1bKrzCXHi+tqR8Gd+ZBCOXa63JC3HIU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=duTirGKDQyiGBycyeKkvAiDA+PxmGT2Wcz7Ut5cbO5BRV7AqwSjREhyDzi8h2Th/WNpWnMRTGAWRmROQxHlknjGYXwC7WeG+eCtKFriId2xu/fYYq55rycfWt433MTjdjvFQLaEstZCwKXLvCGb00RSNcMBxMyTf3vLZHxVrRZA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WrGck7Fm; 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="WrGck7Fm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A2FBC4CEED; Mon, 11 Aug 2025 15:49:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754927376; bh=RopHifErAZ/r1bKrzCXHi+tqR8Gd+ZBCOXa63JC3HIU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WrGck7Fmn0StA1HSyOixhZNPLPo5/WRadk5mDshttUOMgrSNgupbE96hta5DvBVj3 apSkCJOnMOECU6/IGLbkJHX2t7Vvbotqor63J18pfGnwia/s6dXE1SreowaY24sO0q wQv5qfqtKahV6w8xGiUAV8eURWno82WnSMRDKSAs2RJK/g/q3HIL3VWC2cB98VCGKW QesWjW+OnVmrp9KDJ2yFVTxfMfuKyTpp+WLHGuakLcpptXpnmJAWXndwyWnOnsF3q+ s8DO7xeTCoaEjnNgQlSddM+52tNVwSnC4BsO8Rmzgvi74GrybIFHuhPemLca0du7Mp yO0DvfspCWAEQ== Date: Mon, 11 Aug 2025 08:49:35 -0700 From: "Darrick J. Wong" To: Qu Wenruo Cc: Zhang Yi , Qu Wenruo , Theodore Ts'o , linux-ext4 , linux-btrfs , "linux-fsdevel@vger.kernel.org" Subject: Re: Ext4 iomap warning during btrfs/136 (yes, it's from btrfs test cases) Message-ID: <20250811154935.GD7942@frogsfrogsfrogs> References: <9b650a52-9672-4604-a765-bb6be55d1e4a@gmx.com> <4ef2476f-50c3-424d-927d-100e305e1f8e@gmx.com> <20250808121659.GC778805@mit.edu> <035ad34e-fb1e-414f-8d3c-839188cfa387@suse.com> <15a4c437-d276-4503-9e30-4d48f5b7a4ff@gmx.com> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <15a4c437-d276-4503-9e30-4d48f5b7a4ff@gmx.com> On Sun, Aug 10, 2025 at 07:36:48AM +0930, Qu Wenruo wrote: > > > 在 2025/8/9 18:39, Zhang Yi 写道: > > On 2025/8/9 6:11, Qu Wenruo wrote: > > > 在 2025/8/8 21:46, Theodore Ts'o 写道: > > > > On Fri, Aug 08, 2025 at 06:20:56PM +0930, Qu Wenruo wrote: > > > > > > > > > > 在 2025/8/8 17:22, Qu Wenruo 写道: > > > > > > Hi, > > > > > > > > > > > > [BACKGROUND] > > > > > > Recently I'm testing btrfs with 16KiB block size. > > > > > > > > > > > > Currently btrfs is artificially limiting subpage block size to 4K. > > > > > > But there is a simple patch to change it to support all block sizes <= > > > > > > page size in my branch: > > > > > > > > > > > > https://github.com/adam900710/linux/tree/larger_bs_support > > > > > > > > > > > > [IOMAP WARNING] > > > > > > And I'm running into a very weird kernel warning at btrfs/136, with 16K > > > > > > block size and 64K page size. > > > > > > > > > > > > The problem is, the problem happens with ext3 (using ext4 modeule) with > > > > > > 16K block size, and no btrfs is involved yet. > > > > > > > > > > > > Thanks for the bug report!  This looks like it's an issue with using > > > > indirect block-mapped file with a 16k block size.  I tried your > > > > reproducer using a 1k block size on an x86_64 system, which is how I > > > > test problem caused by the block size < page size.  It didn't > > > > reproduce there, so it looks like it really needs a 16k block size. > > > > > > > > Can you say something about what system were you running your testing > > > > on --- was it an arm64 system, or a powerpc 64 system (the two most > > > > common systems with page size > 4k)?  (I assume you're not trying to > > > > do this on an Itanic.  :-)   And was the page size 16k or 64k? > > > > > > The architecture is aarch64, the host board is Rock5B (cheap and fast enough), the test machine is a VM on that board, with ovmf as the UEFI firmware. > > > > > > The kernel is configured to use 64K page size, the *ext3* system is using 16K block size. > > > > > > Currently I tried the following combination with 64K page size and ext3, the result looks like the following > > > > > > - 2K block size > > > - 4K block size > > >   All fine > > > > > > - 8K block size > > > - 16K block size > > >   All the same kernel warning and never ending fsstress > > > > > > - 32K block size > > > - 64K block size > > >   All fine > > > > > > I am surprised as you that, not all subpage block size are having problems, just 2 of the less common combinations failed. > > > > > > And the most common ones (4K, page size) are all fine. > > > > > > Finally, if using ext4 not ext3, all combinations above are fine again. > > > > > > So I ran out of ideas why only 2 block sizes fail here... > > > > > > > This issue is caused by an overflow in the calculation of the hole's > > length on the forth-level depth for non-extent inodes. For a file system > > with a 4KB block size, the calculation will not overflow. For a 64KB > > block size, the queried position will not reach the fourth level, so this > > issue only occur on the filesystem with a 8KB and 16KB block size. > > > > Hi, Wenruo, could you try the following fix? > > > > diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c > > index 7de327fa7b1c..d45124318200 100644 > > --- a/fs/ext4/indirect.c > > +++ b/fs/ext4/indirect.c > > @@ -539,7 +539,7 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode, > > int indirect_blks; > > int blocks_to_boundary = 0; > > int depth; > > - int count = 0; > > + u64 count = 0; > > ext4_fsblk_t first_block = 0; > > > > trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags); > > @@ -588,7 +588,7 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode, > > count++; > > /* Fill in size of a hole we found */ > > map->m_pblk = 0; > > - map->m_len = min_t(unsigned int, map->m_len, count); > > + map->m_len = umin(map->m_len, count); > > goto cleanup; > > } > > It indeed solves the problem. > > Tested-by: Qu Wenruo Can we get the relevant chunks of this test turned into a tests/ext4/ fstest so that the ext4 developers have a regression test that doesn't require setting up btrfs, please? --D > Thanks, > Qu > > > Thanks, > > Yi. > > > >