linux-kernel - Re: [PATCH 02/21] block: Limit atomic writes according to bio and queue limits

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ff43517e-ad30-4608-a8ec-401108129ea5@oracle.com>
Date:   Mon, 4 Dec 2023 09:35:18 +0000
From:   John Garry <john.g.garry@...cle.com>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     axboe@...nel.dk, kbusch@...nel.org, hch@....de, sagi@...mberg.me,
        jejb@...ux.ibm.com, martin.petersen@...cle.com, djwong@...nel.org,
        viro@...iv.linux.org.uk, brauner@...nel.org,
        chandan.babu@...cle.com, dchinner@...hat.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, tytso@....edu, jbongio@...gle.com,
        linux-api@...r.kernel.org
Subject: Re: [PATCH 02/21] block: Limit atomic writes according to bio and
 queue limits

On 04/12/2023 03:55, Ming Lei wrote:

Hi Ming,

> On Mon, Dec 04, 2023 at 11:19:20AM +0800, Ming Lei wrote:
>> On Fri, Sep 29, 2023 at 10:27:07AM +0000, John Garry wrote:
>>> We rely the block layer always being able to send a bio of size
>>> atomic_write_unit_max without being required to split it due to request
>>> queue or other bio limits.
>>>
>>> A bio may contain min(BIO_MAX_VECS, limits->max_segments) vectors,
>>> and each vector is at worst case the device logical block size from
>>> direct IO alignment requirement.
>> Both unit_max and unit_min are applied to FS bio, which is built over
>> single userspace buffer, so only the 1st and last vector can include
> Actually it isn't true for pwritev, and sorry for the noise.

Yeah, I think that it should be:

(max_segments - 2) * PAGE_SIZE

And we need to enforce that any middle vectors are PAGE-aligned.

Thanks,
John