mm: extend prefault helpers to fault in more than PAGE_SIZE
drm/i915 wants to read/write more than one page in its fastpath and hence needs to prefault more than PAGE_SIZE bytes. Add new functions in filemap.h to make that possible. Also kill a copy&pasted spurious space in both functions while at it. v2: As suggested by Andrew Morton, add a multipage parameter to both functions to avoid the additional branch for the pagemap.c hotpath. My gcc 4.6 here seems to dtrt and indeed reap these branches where not needed. v3: Becaus I couldn't find a way around adding a uaddr += PAGE_SIZE to the filemap.c hotpaths (that the compiler couldn't remove again), let's go with separate new functions for the multipage use-case. v4: Adjust comment to CodingStlye and fix spelling. Acked-by:Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch>
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d174bd64
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