From: Baokun Li <libaokun1@huawei.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>, <sashal@kernel.org>, <tytso@mit.edu>,
<jack@suse.cz>, <patches@lists.linux.dev>, <yi.zhang@huawei.com>,
<yangerkun@huawei.com>, Baokun Li <libaokun1@huawei.com>
Subject: Re: [PATCH 5.15 2/2] ext4: avoid bb_free and bb_fragments inconsistency in mb_free_blocks()
Date: Tue, 27 Feb 2024 21:42:10 +0800 [thread overview]
Message-ID: <5a95aeb6-d070-fb3e-d619-8f26164b293c@huawei.com> (raw)
In-Reply-To: <2024022725-broadly-gave-6b16@gregkh>
On 2024/2/27 21:06, Greg KH wrote:
> On Tue, Feb 27, 2024 at 09:00:50PM +0800, Baokun Li wrote:
>> commit 2331fd4a49864e1571b4f50aa3aa1536ed6220d0 upstream.
>>
>> After updating bb_free in mb_free_blocks, it is possible to return without
>> updating bb_fragments because the block being freed is found to have
>> already been freed, which leads to inconsistency between bb_free and
>> bb_fragments.
>>
>> Since the group may be unlocked in ext4_grp_locked_error(), this can lead
>> to problems such as dividing by zero when calculating the average fragment
>> length. Hence move the update of bb_free to after the block double-free
>> check guarantees that the corresponding statistics are updated only after
>> the core block bitmap is modified.
>>
>> Fixes: eabe0444df90 ("ext4: speed-up releasing blocks on commit")
>> CC: <stable@vger.kernel.org> # 3.10
>> Suggested-by: Jan Kara <jack@suse.cz>
>> Signed-off-by: Baokun Li <libaokun1@huawei.com>
>> Reviewed-by: Jan Kara <jack@suse.cz>
>> Link: https://lore.kernel.org/r/20240104142040.2835097-5-libaokun1@huawei.com
>> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
>> Signed-off-by: Baokun Li <libaokun1@huawei.com>
>> ---
>> fs/ext4/mballoc.c | 39 +++++++++++++++++++++------------------
>> 1 file changed, 21 insertions(+), 18 deletions(-)
> We also need this for 5.10.y and older, right?
>
> Queued up now, thanks!
>
> greg k-h
>
5.4.y and older will regenerate the buddy on error, so this is not needed.
--
With Best Regards,
Baokun Li
.
prev parent reply other threads:[~2024-02-27 13:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-27 13:00 [PATCH 5.15 1/2] ext4: regenerate buddy after block freeing failed if under fc replay Baokun Li
2024-02-27 13:00 ` [PATCH 5.15 2/2] ext4: avoid bb_free and bb_fragments inconsistency in mb_free_blocks() Baokun Li
2024-02-27 13:06 ` Greg KH
2024-02-27 13:17 ` Baokun Li
2024-02-27 13:42 ` Baokun Li [this message]
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