Re: [PATCHv2 2/3] i915: convert to new mount API

From: Al Viro <viro@zeniv.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: Hugh Dickins <hughd@google.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	David Howells <dhowells@redhat.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCHv2 2/3] i915: convert to new mount API
Date: Thu, 8 Aug 2019 02:23:14 +0100	[thread overview]
Message-ID: <20190808012314.GK1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190807063002.GG6627@lst.de>

On Wed, Aug 07, 2019 at 08:30:02AM +0200, Christoph Hellwig wrote:
> On Tue, Aug 06, 2019 at 12:50:10AM -0700, Hugh Dickins wrote:
> > Though personally I'm averse to managing "f"objects through
> > "m"interfaces, which can get ridiculous (notably, MADV_HUGEPAGE works
> > on the virtual address of a mapping, but the huge-or-not alignment of
> > that mapping must have been decided previously).  In Google we do use
> > fcntls F_HUGEPAGE and F_NOHUGEPAGE to override on a per-file basis -
> > one day I'll get to upstreaming those.
> 
> Such an interface seems very useful, although the two fcntls seem a bit
> odd.
> 
> But I think the point here is that the i915 has its own somewhat odd
> instance of tmpfs.  If we could pass the equivalent of the huge=*
> options to shmem_file_setup all that garbage (including the
> shmem_file_setup_with_mnt function) could go away.

... or follow shmem_file_super() with whatever that fcntl maps to
internally.  I would really love to get rid of that i915 kludge.