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Date: Wed, 12 Jun 2024 10:09:51 +0200
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Martin Oliveira <martin.oliveira@eideticom.com>
Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Jason Gunthorpe <jgg@ziepe.ca>,
	Leon Romanovsky <leon@kernel.org>, Tejun Heo <tj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Logan Gunthorpe <logang@deltatee.com>,
	Mike Marciniszyn <mike.marciniszyn@intel.com>,
	Shiraz Saleem <shiraz.saleem@intel.com>,
	Michael Guralnik <michaelgur@nvidia.com>,
	Artemy Kovalyov <artemyko@nvidia.com>
Subject: Re: [PATCH v2 1/4] kernfs: remove page_mkwrite() from
 vm_operations_struct
Message-ID: <2024061242-puzzling-implicit-e64e@gregkh>
References: <20240611182732.360317-1-martin.oliveira@eideticom.com>
 <20240611182732.360317-2-martin.oliveira@eideticom.com>
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In-Reply-To: <20240611182732.360317-2-martin.oliveira@eideticom.com>

On Tue, Jun 11, 2024 at 12:27:29PM -0600, Martin Oliveira wrote:
> The .page_mkwrite operator of kernfs just calls file_update_time().
> This is the same behaviour that the fault code does if .page_mkwrite is
> not set.
> 
> Furthermore, having the page_mkwrite() operator causes
> writable_file_mapping_allowed() to fail due to
> vma_needs_dirty_tracking() on the gup flow, which is a pre-requisite for
> enabling P2PDMA over RDMA.
> 
> There are no users of .page_mkwrite and no known valid use cases, so
> just remove the .page_mkwrite from kernfs_ops and return -EINVAL if an
> mmap() implementation sets .page_mkwrite.
> 
> Co-developed-by: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>
> ---
>  fs/kernfs/file.c | 26 +++-----------------------
>  1 file changed, 3 insertions(+), 23 deletions(-)

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>