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From: Kent Overstreet <kent.overstreet@linux.dev>
To: Christoph Hellwig <hch@lst.de>
Cc: bfoster@redhat.com, linux-bcachefs@vger.kernel.org,
	 linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] bcachefs: fix incorrect usage of REQ_OP_FLUSH
Date: Thu, 11 Jan 2024 11:37:09 -0500	[thread overview]
Message-ID: <e6wpysqepf5nfpvugxutqqohkunjvewomk7lkvk2kd2cwkstg2@g7r3qz46txx7> (raw)
In-Reply-To: <20240111073655.2095423-1-hch@lst.de>

On Thu, Jan 11, 2024 at 08:36:55AM +0100, Christoph Hellwig wrote:
> REQ_OP_FLUSH is only for internal use in the blk-mq and request based
> drivers. File systems and other block layer consumers must use
> REQ_OP_WRITE | REQ_PREFLUSH as documented in
> Documentation/block/writeback_cache_control.rst.
> 
> While REQ_OP_FLUSH appears to work for blk-mq drivers it does not
> get the proper flush state machine handling, and completely fails
> for any bio based drivers, including all the stacking drivers.  The
> block layer will also get a check in 6.8 to reject this use case
> entirely.
> 
> [Note: completely untested, but as this never got fixed since the
> original bug report in November:
> 
>    https://bugzilla.kernel.org/show_bug.cgi?id=218184
> 
> and the the discussion in December:
> 
>     https://lore.kernel.org/all/20231221053016.72cqcfg46vxwohcj@moria.home.lan/T/
> 
> this seems to be best way to force it]
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Hey Christoph, thanks - applied.

  reply	other threads:[~2024-01-11 16:37 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-11  7:36 [PATCH] bcachefs: fix incorrect usage of REQ_OP_FLUSH Christoph Hellwig
2024-01-11 16:37 ` Kent Overstreet [this message]
2024-01-19 21:32 ` Kent Overstreet
2024-01-22  6:30   ` Christoph Hellwig
2024-01-22  6:37     ` Kent Overstreet
2024-01-22  6:50       ` Christoph Hellwig
2024-01-22 17:37         ` Kent Overstreet
2024-01-22 17:38           ` Christoph Hellwig
2024-01-22 17:42             ` Kent Overstreet
2024-01-22 18:41               ` Christoph Hellwig
2024-01-23  0:42                 ` Dave Chinner

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