Messages in this thread | | | Date | Sun, 10 Aug 2008 21:30:24 -0400 | From | Christoph Hellwig <> | Subject | Re: [PATCH] Export shmem_file_setup and shmem_getpage for DRM-GEM |
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On Mon, Aug 04, 2008 at 06:09:24PM +0100, Hugh Dickins wrote: > Whether such usage conforms to VFS API I'm not so sure: as I understand > it, it's really for internal use by a filesystem - if it's going to be > used beyond that, we ought to add a check that the filesystem it's used > upon really has a ->readpage method (and I'd rather we add such a check > than you do it at your end, in case we change the implementation later > to use something other than a ->readpage method - Nick, you'll be > nauseated to hear I was looking to see if ->fault with a pseudo-vma > could do it). But if the layering police are happy with this, I am.
Using read_mapping_page is fine on any pagecache backed file. What is much more difficult is actually writing into pagecache on a sub-page level where we don't have proper APIs for anything but the filesystem itself.
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