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From: Christoph Hellwig <hch@infradead.org>
To: Song Liu <song@kernel.org>
Cc: linux-block@vger.kernel.org, linux-raid@vger.kernel.org,
	axboe@kernel.dk, kent.overstreet@linux.dev,
	janpieter.sollie@edpnet.be, colyli@suse.de, bagasdotme@gmail.com
Subject: Re: [PATCH 1/2] block: Check REQ_OP_FLUSH in op_is_flush()
Date: Wed, 20 Dec 2023 22:12:49 -0800	[thread overview]
Message-ID: <ZYPXYdBAdNoKXI8b@infradead.org> (raw)
In-Reply-To: <20231221012715.3048221-2-song@kernel.org>

On Wed, Dec 20, 2023 at 05:27:14PM -0800, Song Liu wrote:
> Upper layer (fs, etc.) may issue flush with something like:
> 
>   bio_reset(bio, bdev, REQ_OP_FLUSH);
>   bio->bi_end_io = xxx;
>   submit_bio(bio);

No, they can't.  REQ_OP_FLUSH is currently only used by request
based drivers and only generated by the flush state machine.

(Not that I particularly like this wart, I'd much prefer file systems
to submit a REQ_OP_FLUSH than an empty write with a preflush flag,
but that's not a trivial change).

  reply	other threads:[~2023-12-21  6:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-21  1:27 [PATCH 0/2] block, md: Better handle REQ_OP_FLUSH Song Liu
2023-12-21  1:27 ` [PATCH 1/2] block: Check REQ_OP_FLUSH in op_is_flush() Song Liu
2023-12-21  6:12   ` Christoph Hellwig [this message]
2023-12-21  7:53     ` Song Liu
2023-12-21  1:27 ` [PATCH 2/2] md: Use op_is_flush() to check flush bio Song Liu
2023-12-21  3:36 ` [PATCH 0/2] block, md: Better handle REQ_OP_FLUSH Ed Tsai (蔡宗軒)
2023-12-21  5:30   ` Kent Overstreet
2023-12-21  7:56     ` Ed Tsai (蔡宗軒)
2023-12-21 19:19       ` Kent Overstreet

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