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From: Dan Williams <dan.j.williams@intel.com>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Vishal Verma <vishal.l.verma@intel.com>,
	 Dave Jiang <dave.jiang@intel.com>,
	Mike Snitzer <snitzer@redhat.com>,
	 Matthew Wilcox <willy@infradead.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	 Linux NVDIMM <nvdimm@lists.linux.dev>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	 linux-ext4 <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] dax: remove silly single-page limitation in dax_zero_page_range
Date: Wed, 22 Sep 2021 19:47:08 -0700	[thread overview]
Message-ID: <CAPcyv4i5xYHFkW55eGi8L6mfoPwuMhcH3eFhDTAqzrTNvwTt4A@mail.gmail.com> (raw)
In-Reply-To: <20210923010915.GQ570615@magnolia>

On Wed, Sep 22, 2021 at 6:09 PM Darrick J. Wong <djwong@kernel.org> wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> It's totally silly that the dax zero_page_range implementations are
> required to accept a page count, but one of the four implementations
> silently ignores the page count and the wrapper itself errors out if you
> try to do more than one page.
> Fix the nvdimm implementation to loop over the page count and remove the
> artificial limitation.
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  drivers/dax/super.c   |    7 -------
>  drivers/nvdimm/pmem.c |   14 +++++++++++---
>  2 files changed, 11 insertions(+), 10 deletions(-)
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index fc89e91beea7..ca61a01f9ccd 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -353,13 +353,6 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
>  {
>         if (!dax_alive(dax_dev))
>                 return -ENXIO;
> -       /*
> -        * There are no callers that want to zero more than one page as of now.
> -        * Once users are there, this check can be removed after the
> -        * device mapper code has been updated to split ranges across targets.
> -        */

It's device-mapper that's the issue, you need to make sure that every
device-mapper zero_page_range implementation knows how to route a
multi-page operation. This is part of the motivation to drop that
support and move simple concatenation and striping into the PMEM
driver directly.

      reply	other threads:[~2021-09-23  2:47 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-23  1:09 Darrick J. Wong
2021-09-23  2:47 ` Dan Williams [this message]

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