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 6D6BF1E3DF8 for ; Wed, 17 Sep 2025 06:41:42 +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=1758091302; cv=none; b=OnHrKoAcg8QzeSBKFQ5L/GmHkoaVHrJ8JbmDGUrhWWpxtzu+Wpv9uAhV+q+JTKyGDUaAQXKkVPv7bFGrY+NiGzvV68CEL9AJWVNeMwwABlI/aPH2eAlDqbWo3sEbJbPmmY6dCOWvS1cXYmHJ2+3BzUpqHmoxV0KARijyO4VZtKs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758091302; c=relaxed/simple; bh=T0iVRqYjMl2xvDtrQJ16kWmCb8PF43r3K+G5IOGlLhc=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=n5zE+wtclGfBfSb0lKw8T95mwapK3nX+d3AZ7tLkakUpbOYuw63ZfKYVqAAKg9CB/EcaDOepd0YYtkecNm26xyle/WZZUGr4nIo3ubQTNeduFcRfIqsQdOwZxHFrbT9mRnITkDK1nIlceJkWfV+/sFzCCcl7Bxyq3GnB3A4tzMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hMisa/Rv; 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="hMisa/Rv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7B8DC4CEF0; Wed, 17 Sep 2025 06:41:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758091302; bh=T0iVRqYjMl2xvDtrQJ16kWmCb8PF43r3K+G5IOGlLhc=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=hMisa/RvND4bb/dave5KS+GBDAZAZVR5esdP59RdY9gVhIyPdxgVwSOuSpbeVafXi TlFp7W/OFxNNhhcUbThltBYfxCG/mFZdeguy9I6q5MDsBrVdW9RgYbezGwfpBdQmyC LiOC2L9Af4aRVNEllF9IoyH5VXsBdORWLzcoNhJXo7VFe2DY6EyFTzT0Msva73pdaG jX3LLIfRmsoG5HUxHPtxtKMk/PrCsL4ujuQTi9Fre7UPEWNkIQniQvTFS1PJMVIPAS /CvyDs85oKnkj1DzXn2pkiZjLWwR0XL5RZFda12WPzl/IKpHHdknu4QEzkVygw2EpM QtHXV15jRTAJQ== Message-ID: <760669e9-22ec-490f-adc2-2981d2a56709@kernel.org> Date: Wed, 17 Sep 2025 14:41:38 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, bintian.wang@honor.com, feng.han@honor.com Subject: Re: [f2fs-dev] [PATCH v3 1/2] f2fs: fix zero-sized extent for precache extents To: wangzijie , jaegeuk@kernel.org References: <20250917023622.516052-1-wangzijie1@honor.com> Content-Language: en-US From: Chao Yu In-Reply-To: <20250917023622.516052-1-wangzijie1@honor.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/17/25 10:36, wangzijie wrote: > Script to reproduce: > f2fs_io write 1 0 1881 rand dsync testfile > f2fs_io fallocate 0 7708672 4096 testfile > f2fs_io write 1 1881 1 rand buffered testfile > fsync testfile > umount > mount > f2fs_io precache_extents testfile > > When the data layout is something like this: > dnode1: dnode2: > [0] A [0] NEW_ADDR > [1] A+1 [1] 0x0 > ... > [1016] A+1016 > [1017] B (B!=A+1017) [1017] 0x0 > > During precache_extents, we map the last block(valid blkaddr) in dnode1: > map->m_flags |= F2FS_MAP_MAPPED; > map->m_pblk = blkaddr(valid blkaddr); > map->m_len = 1; > then we goto next_dnode, meet the first block in dnode2(hole), goto sync_out: > map->m_flags & F2FS_MAP_MAPPED == true, and we make zero-sized extent: > > map->m_len = 1 > ofs = start_pgofs - map->m_lblk = 1882 - 1881 = 1 > ei.fofs = start_pgofs = 1882 > ei.len = map->m_len - ofs = 1 - 1 = 0 > > > Rebased on patch[1], this patch can cover these cases to avoid zero-sized extent: > A,B,C is valid blkaddr > case1: > dnode1: dnode2: > [0] A [0] NEW_ADDR > [1] A+1 [1] 0x0 > ... .... > [1016] A+1016 > [1017] B (B!=A+1017) [1017] 0x0 > > case2: > dnode1: dnode2: > [0] A [0] C (C!=B+1) > [1] A+1 [1] C+1 > ... .... > [1016] A+1016 > [1017] B (B!=A+1017) [1017] 0x0 > > case3: > dnode1: dnode2: > [0] A [0] C (C!=B+2) > [1] A+1 [1] C+1 > ... .... > [1015] A+1015 > [1016] B (B!=A+1016) > [1017] B+1 [1017] 0x0 > > [1] https://lore.kernel.org/linux-f2fs-devel/20250912081250.44383-1-chao@kernel.org/ > > Fixes: c4020b2da4c9 ("f2fs: support F2FS_IOC_PRECACHE_EXTENTS") > Signed-off-by: wangzijie Reviewed-by: Chao Yu Thanks,