linux-kernel - Re: [PATCH v2 1/4] blk-flush: flush_rq should inherit first_rq's cmd

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]

Date:   Mon, 31 Jul 2023 18:28:01 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     Christoph Hellwig <hch@....de>, chengming.zhou@...ux.dev
Cc:     axboe@...nel.dk, ming.lei@...hat.com, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, zhouchengming@...edance.com
Subject: Re: [PATCH v2 1/4] blk-flush: flush_rq should inherit first_rq's
 cmd_flags

On 7/31/23 08:09, Christoph Hellwig wrote:
> On Tue, Jul 25, 2023 at 09:00:59PM +0800, chengming.zhou@...ux.dev wrote:
>> From: Chengming Zhou <zhouchengming@...edance.com>
>>
>> The cmd_flags in blk_kick_flush() should inherit the original request's
>> cmd_flags, but the current code looks buggy to me:
> 
> Should it?  I know the code is kinda trying to do it, but does it really
> make sense?  Adding Hannes who originally added this inheritance and
> discussing the details below:
> 
Yeah, it does.
The flush machinery is sending flushes before and/or after the original 
request (preflush/postflush). For blocked transports (ie during FC RSCN 
handling) the transport will error out commands depending on the 
FAILFAST setting. If FAILFAST is set the SCSI layer gets an 
STS_TRANSPORT error (causing the I/O to be retried), but STS_ERROR if 
not set (causing I/O to failed).

So if the FAILFAST setting is _not_ aligned between flush_rq and the 
original we'll get an error on the flush rq and a retry on the original 
rq, causing the entire command to fail.

I guess we need to align them.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@...e.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman