From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 E73E0279DC8 for ; Tue, 13 Jan 2026 15:11:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768317079; cv=none; b=UP+PUhhxfl7Jhmhe2CzI0HmQvLmkZeNAQveXgCxniODwMgQMG3Yd86EteZQVWGr8Ldt/hpHLQs31iyWWzTag6Bb4yCKJY+UlmiBQRx84b9gy2GxprbCKNStjKQYeHN8c1eQYIGbcqsld6fc+MJYF8ZCXeA+eZooTYEEDhNKC8IQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768317079; c=relaxed/simple; bh=sDmVD4QZuZAEKvWMDNO3NVaZLos7S4q4l46YTcCCsmE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ka8qLrxWxpDvY1pofD5Skp4Ez/jhvJFMTuG/IMysiNDGlRSDhfQKdIXrBixs357EUrrkmgc+OnpQN8xSjDxjAb/e94ArTyvBFxqyxE4ZiyahxBuWOZh/aqiOh5jTfFwmjzJco37XQLXC3Nv97l+84em7fCiU9WuVDgiVsjfo668= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=I2eDWNxv; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="I2eDWNxv" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1768317077; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LoXI203kMyBQVpjb5hxEV3UrpIwAgVVC06Qo6MwtPRA=; b=I2eDWNxvz3g7LfAvap0IQm0sgl0I3bHN/1+Dvoj0AcyFfIG7T1pwhJ5aOTmf2AZr+wOFmE 37oXAlZWRw22CtwjrYAqDpU8C5GN5c9IDDgsUUaZ8zUPidTZx3XS+hueBhd3kjjmV3Rh5T UOTOatNB2P30gKDBePOoR3EepVuHhiw= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-584-e921lH47NPC3SQzT9Lbgsw-1; Tue, 13 Jan 2026 10:11:14 -0500 X-MC-Unique: e921lH47NPC3SQzT9Lbgsw-1 X-Mimecast-MFC-AGG-ID: e921lH47NPC3SQzT9Lbgsw_1768317073 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5A7E9180060B; Tue, 13 Jan 2026 15:11:10 +0000 (UTC) Received: from bfoster (unknown [10.22.89.227]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D00331801A45; Tue, 13 Jan 2026 15:11:07 +0000 (UTC) Date: Tue, 13 Jan 2026 10:11:05 -0500 From: Brian Foster To: Baokun Li Cc: linux-ext4@vger.kernel.org Subject: Re: [PATCH v2] ext4: fix dirtyclusters double decrement on fs shutdown Message-ID: References: <20260112143652.8085-1-bfoster@redhat.com> <94ccc367-f631-40fe-a99e-635d1eb0a3dd@huawei.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: <94ccc367-f631-40fe-a99e-635d1eb0a3dd@huawei.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On Tue, Jan 13, 2026 at 09:44:16AM +0800, Baokun Li wrote: > On 2026-01-12 22:36, Brian Foster wrote: > > fstests test generic/388 occasionally reproduces a warning in > > ext4_put_super() associated with the dirty clusters count: > > > > WARNING: CPU: 7 PID: 76064 at fs/ext4/super.c:1324 ext4_put_super+0x48c/0x590 [ext4] > > > > Tracing the failure shows that the warning fires due to an > > s_dirtyclusters_counter value of -1. IOW, this appears to be a > > spurious decrement as opposed to some sort of leak. Further tracing > > of the dirty cluster count deltas and an LLM scan of the resulting > > output identified the cause as a double decrement in the error path > > between ext4_mb_mark_diskspace_used() and the caller > > ext4_mb_new_blocks(). > > > > First, note that generic/388 is a shutdown vs. fsstress test and so > > produces a random set of operations and shutdown injections. In the > > problematic case, the shutdown triggers an error return from the > > ext4_handle_dirty_metadata() call(s) made from > > ext4_mb_mark_context(). The changed value is non-zero at this point, > > so ext4_mb_mark_diskspace_used() does not exit after the error > > bubbles up from ext4_mb_mark_context(). Instead, the former > > decrements both cluster counters and returns the error up to > > ext4_mb_new_blocks(). The latter falls into the !ar->len out path > > which decrements the dirty clusters counter a second time, creating > > the inconsistency. > > > > To avoid this problem and simplify ownership of the cluster > > reservation in this codepath, lift the counter reduction to a single > > place in the caller. This makes it more clear that > > ext4_mb_new_blocks() is responsible for acquiring cluster > > reservation (via ext4_claim_free_clusters()) in the !delalloc case > > as well as releasing it, regardless of whether it ends up consumed > > or returned due to failure. > > > > Fixes: 0087d9fb3f29 ("ext4: Fix s_dirty_blocks_counter if block allocation failed with nodelalloc") > > Signed-off-by: Brian Foster > > Thanks for the patch. > > However, the call site in test_mark_diskspace_used_range() missed the > argument update, which triggered a Kernel Test Robot warning. Also, > I have one nit below. Ugh yeah, I guess I didn't have KUNIT enabled so I missed that one. Will fix. > > > --- > > > > v2: > > - Condense counter update logic instead of modifying return flow. > > - Added Fixes: tag. > > v1: https://lore.kernel.org/linux-ext4/20251212154735.512651-1-bfoster@redhat.com/ > > > > fs/ext4/mballoc.c | 21 +++++---------------- > > 1 file changed, 5 insertions(+), 16 deletions(-) > > > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > > index 56d50fd3310b..b31d7ddc52a9 100644 > > --- a/fs/ext4/mballoc.c > > +++ b/fs/ext4/mballoc.c > > @@ -4185,8 +4185,7 @@ ext4_mb_mark_context(handle_t *handle, struct super_block *sb, bool state, > > * Returns 0 if success or error code > > */ > > static noinline_for_stack int > > -ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac, > > - handle_t *handle, unsigned int reserv_clstrs) > > +ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac, handle_t *handle) > > { > > struct ext4_group_desc *gdp; > > struct ext4_sb_info *sbi; > > @@ -4241,13 +4240,6 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac, > > BUG_ON(changed != ac->ac_b_ex.fe_len); > > #endif > > percpu_counter_sub(&sbi->s_freeclusters_counter, ac->ac_b_ex.fe_len); > > - /* > > - * Now reduce the dirty block count also. Should not go negative > > - */ > > - if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED)) > > - /* release all the reserved blocks if non delalloc */ > > - percpu_counter_sub(&sbi->s_dirtyclusters_counter, > > - reserv_clstrs); > > > > return err; > > } > > @@ -6332,7 +6324,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, > > ext4_mb_pa_put_free(ac); > > } > > if (likely(ac->ac_status == AC_STATUS_FOUND)) { > > - *errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs); > > + *errp = ext4_mb_mark_diskspace_used(ac, handle); > > if (*errp) { > > ext4_discard_allocated_blocks(ac); > > goto errout; > > @@ -6363,12 +6355,9 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, > > out: > > if (inquota && ar->len < inquota) > > dquot_free_block(ar->inode, EXT4_C2B(sbi, inquota - ar->len)); > > - if (!ar->len) { > > - if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0) > > - /* release all the reserved blocks if non delalloc */ > > - percpu_counter_sub(&sbi->s_dirtyclusters_counter, > > - reserv_clstrs); > > - } > > + /* release all the reserved blocks if non delalloc */ > > + if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0) > > Nit: It might be better to check if (reserv_clstrs) directly. It’s more > straightforward and stays robust even if the flag logic changes later. Sure. Brian > > > + percpu_counter_sub(&sbi->s_dirtyclusters_counter, reserv_clstrs); > > > > trace_ext4_allocate_blocks(ar, (unsigned long long)block); > > > >