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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 2/2] blk-mq: ensure a q_usage_counter reference is held when splitting bios
Date: Fri, 12 Jan 2024 06:46:36 +0100	[thread overview]
Message-ID: <20240112054636.GB6829@lst.de> (raw)
In-Reply-To: <ZaBqQ0jX6ovHITQo@fedora>

On Fri, Jan 12, 2024 at 06:22:59AM +0800, Ming Lei wrote:
> On Thu, Jan 11, 2024 at 02:57:05PM +0100, Christoph Hellwig wrote:
> > q_usage_counter is the only thing preventing us from the limits changing
> > under us in __bio_split_to_limits, but blk_mq_submit_bio doesn't hold it.
> 
> Can you share why the limits change matters wrt. split? If queue is
> live, both new and old one are supposed to work, such as, we don't
> freeze queue when changing `max_sectors_kb` via sysfs.

Hardware reconfigurations for example, which can happen in nvme for
just about every limit, in SCSI for limits controller by the ULD,
and in quite a few places for disabling write zeroes or discard.


  reply	other threads:[~2024-01-12  5:46 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-11 13:57 ensure q_usage_counter is held over bio splits Christoph Hellwig
2024-01-11 13:57 ` [PATCH 1/2] blk-mq: rename blk_mq_can_use_cached_rq Christoph Hellwig
2024-01-11 13:57 ` [PATCH 2/2] blk-mq: ensure a q_usage_counter reference is held when splitting bios Christoph Hellwig
2024-01-11 16:12   ` Jens Axboe
2024-01-11 16:14     ` Christoph Hellwig
2024-01-11 16:17       ` Jens Axboe
2024-01-11 16:18         ` Christoph Hellwig
2024-01-11 17:10         ` Christoph Hellwig
2024-01-11 17:18           ` Jens Axboe
2024-01-11 17:24             ` Christoph Hellwig
2024-01-11 20:06               ` Jens Axboe
2024-01-12  5:44                 ` Christoph Hellwig
2024-01-12 14:22                   ` Jens Axboe
2024-01-12 14:25                     ` Christoph Hellwig
2024-01-12 16:10                       ` Jens Axboe
2024-01-15 11:20                     ` Ulf Hansson
2024-01-22  7:34                       ` mmc vs highmem, was: " Christoph Hellwig
2024-01-22  9:26                         ` Arnd Bergmann
2024-01-22 13:39                           ` Christoph Hellwig
2024-01-22 14:57                             ` Arnd Bergmann
2024-01-23  9:11                               ` Christoph Hellwig
2024-01-24 11:59                                 ` Arnd Bergmann
2024-01-24 12:33                                   ` Linus Walleij
2024-01-24 12:54                                     ` Arnd Bergmann
2024-01-24 13:16                                       ` Linus Walleij
2024-01-24 14:14                                         ` Arnd Bergmann
2024-01-24 12:45                               ` Arnd Bergmann
2024-01-24 13:49                           ` Linus Walleij
2024-01-24 16:35                             ` Arnd Bergmann
2024-01-11 22:22   ` Ming Lei
2024-01-12  5:46     ` Christoph Hellwig [this message]
2024-01-11 16:03 ` ensure q_usage_counter is held over bio splits Jens Axboe
2024-01-14 14:38 ` (subset) " Jens Axboe

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