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 77AC313C8FF for ; Wed, 3 Sep 2025 01:33:22 +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=1756863202; cv=none; b=bh9GyTCuhcDpGzqb6E8VBFMdMYap9zPwy/pFUlQWdMsyHiYSjN7cK6kNVRni2jY1M/rj+HdrRH/QVvfKELj/AuoMECyDUpK15U3oH29oZy2O0kFOeoE4wHusdXdrBUQnI4m3RdRelgMeKwK0dueKbo+0lOb76NP1Zsufoe/pEiA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756863202; c=relaxed/simple; bh=b37So3j2iYeAd1OR2qYhYUiZfHzafcrukdWRQBjhpms=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=dtXvF9WbzEsYV8brzMW6kiq55XOl9wweVWt3LTt7s3dcwsjnN6Eu3eR/fJHPcumF7RASmWAsxms0Qci+hsy6R95Kw4qhp8MpAnsOrgvAgCvTKvrc1jPzgf28OjHHJSvRLI8VtFuKmb244aIZ54II3kr/I7voQCgNCRJijTq9IoI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T6Erysx2; 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="T6Erysx2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9BE8C4CEED; Wed, 3 Sep 2025 01:33:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756863202; bh=b37So3j2iYeAd1OR2qYhYUiZfHzafcrukdWRQBjhpms=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=T6Erysx2EfgdNWpSAjSuRn+ri//0/IeUcbCaBHwDDedaSLOZImkBPn7I5yLWs5hiK +gf4Y/XTXUq2rP52Jz9F4kcFp3v3m5DueB00JlOs4vz535r0j8+ww3tFxrP4dxR2hh uuKdxg8wIziTBeIccsWHV5RP5kPAwfXQeuzHBWyK04zjvcHXIz8x6QftaQKZplYxDA jz0s29WIuYg85XwC5l6rdBqW6s+3sJkb/FEhJWzotjhDh1PZbT0cnDvilMcOgX+YUT 6i98BhqTsfC0NOIrwN4F22keIoU0NC0oif4pFp2Pni20Av1RyRHKeBFgaclO03NEfh RaokkT3WceZKg== Message-ID: Date: Wed, 3 Sep 2025 09:33:18 +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, jaegeuk@kernel.org, Daeho Jeong , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to avoid migrating empty section To: Zhiguo Niu References: <20250901020416.2172182-1-chao@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 9/3/25 08:04, Zhiguo Niu wrote: > Chao Yu via Linux-f2fs-devel > 于2025年9月1日周一 10:08写道： >> >> It reports a bug from device w/ zufs: >> >> F2FS-fs (dm-64): Inconsistent segment (173822) type [1, 0] in SSA and SIT >> F2FS-fs (dm-64): Stopped filesystem due to reason: 4 >> >> Thread A Thread B >> - f2fs_expand_inode_data >> - f2fs_allocate_pinning_section >> - f2fs_gc_range >> - do_garbage_collect w/ segno #x >> - writepage >> - f2fs_allocate_data_block >> - new_curseg >> - allocate segno #x >> >> The root cause is: fallocate on pinning file may race w/ block allocation >> as above, result in do_garbage_collect() from fallocate() may migrate >> segment which is just allocated by a log, the log will update segment type >> in its in-memory structure, however GC will get segment type from on-disk >> SSA block, once segment type changes by log, we can detect such >> inconsistency, then shutdown filesystem. >> >> In this case, on-disk SSA shows type of segno #173822 is 1 (SUM_TYPE_NODE), >> however segno #173822 was just allocated as data type segment, so in-memory >> SIT shows type of segno #173822 is 0 (SUM_TYPE_DATA). >> >> Change as below to fix this issue: >> - check whether current section is empty before gc >> - add sanity checks on do_garbage_collect() to avoid any race case, result >> in migrating segment used by log. >> - btw, it fixes misc issue in printed logs: "SSA and SIT" -> "SIT and SSA". >> >> Fixes: 9703d69d9d15 ("f2fs: support file pinning for zoned devices") >> Cc: Daeho Jeong >> Signed-off-by: Chao Yu >> --- >> fs/f2fs/gc.c | 16 +++++++++++++++- >> 1 file changed, 15 insertions(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >> index ed3acbfc83ca..a7708cf80c04 100644 >> --- a/fs/f2fs/gc.c >> +++ b/fs/f2fs/gc.c >> @@ -1794,6 +1794,13 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, >> struct folio *sum_folio = filemap_get_folio(META_MAPPING(sbi), >> GET_SUM_BLOCK(sbi, segno)); >> >> + if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno))) { >> + f2fs_err(sbi, "%s: segment %u is used by log", >> + __func__, segno); >> + f2fs_bug_on(sbi, 1); > Hi Chao, > Do we need f2fs_bug_on here? or it is enough to skip current segno > and let gc continue? Zhiguo, I think we should never select in-use segment as GC victim, so I add a f2fs_bug_on() here to detect any potential bugs. Let's see what will we find w/ this. Thanks, > Thanks! >> + goto skip; >> + } >> + >> if (get_valid_blocks(sbi, segno, false) == 0) >> goto freed; >> if (gc_type == BG_GC && __is_large_section(sbi) && >> @@ -1805,7 +1812,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, >> >> sum = folio_address(sum_folio); >> if (type != GET_SUM_TYPE((&sum->footer))) { >> - f2fs_err(sbi, "Inconsistent segment (%u) type [%d, %d] in SSA and SIT", >> + f2fs_err(sbi, "Inconsistent segment (%u) type [%d, %d] in SIT and SSA", >> segno, type, GET_SUM_TYPE((&sum->footer))); >> f2fs_stop_checkpoint(sbi, false, >> STOP_CP_REASON_CORRUPTED_SUMMARY); >> @@ -2068,6 +2075,13 @@ int f2fs_gc_range(struct f2fs_sb_info *sbi, >> .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS), >> }; >> >> + /* >> + * avoid migrating empty section, as it can be allocated by >> + * log in parallel. >> + */ >> + if (!get_valid_blocks(sbi, segno, true)) >> + continue; >> + >> if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno))) >> continue; >> >> -- >> 2.49.0 >> >> >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel