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 24163219FC for ; Tue, 18 Mar 2025 01:18:43 +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=1742260725; cv=none; b=ZyOM79UAPKBD1nFrqRyELGTiqURNhbR5jag7TSX3So2EdXR8ttO6OyggqRG5M8HFnYmXbqoz5mhOtPjclrqv4Po/DvnVZHMCC22lDjaBH38rnS5si/LwXX8CiMkGqcZcGkfQNQqYU7mrYLAhfG4bC+yvN8WeupsSAXKOx4bREiI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742260725; c=relaxed/simple; bh=YSMbJQm0dtkQCgXKxD1IBYJdlWjjJpfSyCN7la2UKg8=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=vEouM6TlxrPwl2x7TB0EgEnTwDWTAXBJuQbVNo20zznnGhvCx71NR6vclAcFuFZrvsSAgKgTPuLIkUB70Cgdx2VFXu8X/15daB0AG4OG87tMxDd7NK/9sYxQIoIhCt6CMJWv0+KCVQyW7e2d0IRT7B9T7RF+VgURktS//yRfLXw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NbQtkQ8s; 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="NbQtkQ8s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7AD1C4CEE3; Tue, 18 Mar 2025 01:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742260723; bh=YSMbJQm0dtkQCgXKxD1IBYJdlWjjJpfSyCN7la2UKg8=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=NbQtkQ8sdbI2EhaGjfAO8JcdK/s5hZsL/zi0FGzYsodq27nzkUlP+cVHPWxqnt/dr 4ZbbTMlB/Ce/7GAo65RwTnz4P71hcrileui7yCA/NZSsn+uMPUKPZ5QcCZ0mMOdUg+ M1pA7DjA58/4fH6DJZCPX7yQUJfF4wcLe5cM5Sm7GPb+8kSf2dRzisdiOcz8NE8hom K8QWHzOPt9CZo1i628dvt1KosDWVUGo0O3tjwTx2/n2J7+6OrFmF23KEysFGhlz2am PwYLxJNnQeyJyWuw8HRvVPMVVT4gFxdi74tUNnBSsj1RkbO1oNHSHuGyFfgX4zU4E7 3qZxCtQIv80Ow== Message-ID: <0cbe2a82-6e1c-425d-a967-85e4de44067d@kernel.org> Date: Tue, 18 Mar 2025 09:18:41 +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 Subject: Re: [PATCH v3] f2fs: fix missing discard for active segments To: Chunhai Guo , jaegeuk@kernel.org References: <20250317101624.3223575-1-guochunhai@vivo.com> Content-Language: en-US From: Chao Yu In-Reply-To: <20250317101624.3223575-1-guochunhai@vivo.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/17/25 18:16, Chunhai Guo wrote: > During a checkpoint, the current active segment X may not be handled > properly. This occurs when segment X has 0 valid blocks and a non-zero > number of discard blocks, for the following reasons: > > locate_dirty_segment() does not mark any active segment as a prefree > segment. As a result, segment X is not included in dirty_segmap[PRE], and > f2fs_clear_prefree_segments() skips it when handling prefree segments. > > add_discard_addrs() skips any segment with 0 valid blocks, so segment X is > also skipped. > > Consequently, no `struct discard_cmd` is actually created for segment X. > However, the ckpt_valid_map and cur_valid_map of segment X are synced by > seg_info_to_raw_sit() during the current checkpoint process. As a result, > it cannot find the missing discard bits even in subsequent checkpoints. > Consequently, the value of sbi->discard_blks remains non-zero. Thus, when > f2fs is umounted, CP_TRIMMED_FLAG will not be set due to the non-zero > sbi->discard_blks. > > Relevant code process: > > f2fs_write_checkpoint() > f2fs_flush_sit_entries() > list_for_each_entry_safe(ses, tmp, head, set_list) { > for_each_set_bit_from(segno, bitmap, end) { > ... > add_discard_addrs(sbi, cpc, false); // skip segment X due to its 0 valid blocks > ... > seg_info_to_raw_sit(); // sync ckpt_valid_map with cur_valid_map for segment X > ... > } > } > f2fs_clear_prefree_segments(); // segment X is not included in dirty_segmap[PRE] and is skipped > > This issue is easy to reproduce with the following operations: > > root # mkfs.f2fs -f /dev/f2fs_dev > root # mount -t f2fs /dev/f2fs_dev /mnt_point > root # dd if=/dev/blk_dev of=/mnt_point/1.bin bs=4k count=256 > root # sync > root # rm /mnt_point/1.bin > root # umount /mnt_point > root # dump.f2fs /dev/f2fs_dev | grep "checkpoint state" > Info: checkpoint state = 45 : crc compacted_summary unmount ---- 'trimmed' flag is missing > > Since add_discard_addrs() can handle active segments with non-zero valid > blocks, it is reasonable to fix this issue by allowing it to also handle > active segments with 0 valid blocks. > > Fixes: b29555505d81 ("f2fs: add key functions for small discards") > Signed-off-by: Chunhai Guo Reviewed-by: Chao Yu Thanks,