linux-kernel - Re: [PATCH] zonefs: do not use append if device does not support it

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Message-ID: <31ceba83-9d06-8fc6-4688-d568a698a4cc@kernel.org>
Date:   Tue, 27 Jun 2023 13:45:38 +0900
From:   Damien Le Moal <dlemoal@...nel.org>
To:     Christoph Hellwig <hch@...radead.org>,
        Andreas Hindborg <nmi@...aspace.dk>
Cc:     "open list:ZONEFS FILESYSTEM" <linux-fsdevel@...r.kernel.org>,
        gost.dev@...sung.com, Andreas Hindborg <a.hindborg@...sung.com>,
        Naohiro Aota <naohiro.aota@....com>,
        Johannes Thumshirn <jth@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] zonefs: do not use append if device does not support it

On 6/27/23 12:45, Christoph Hellwig wrote:
> On Mon, Jun 26, 2023 at 06:47:52PM +0200, Andreas Hindborg wrote:
>> From: "Andreas Hindborg (Samsung)" <nmi@...aspace.dk>
>>
>> Zonefs will try to use `zonefs_file_dio_append()` for direct sync writes even if
>> device `max_zone_append_sectors` is zero. This will cause the IO to fail as the
>> io vector is truncated to zero. It also causes a call to
>> `invalidate_inode_pages2_range()` with end set to UINT_MAX, which is probably
>> not intentional. Thus, do not use append when device does not support it.
> 
> How do you even manage to hit this code?  Zone Append is a mandatory
> feature and driver need to check it is available.

ublk driver probably is missing that check ? I have not looked at the code for
zone support.

But thinking of it, we probably would be better off having a generic check for
"q->limits.max_zone_append_sectors != 0" in blk_revalidate_disk_zones().

-- 
Damien Le Moal
Western Digital Research