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>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e9cac47..6dc8329 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -416,7 +416,7 @@
mutex_unlock(&dev->struct_mutex);
if (!prefaulted) {
- ret = fault_in_pages_writeable(user_data, remain);
+ ret = fault_in_multipages_writeable(user_data, remain);
/* Userspace is tricking us, but we've already clobbered
* its pages with the prefault and promised to write the
* data up to the first fault. Hence ignore any errors
@@ -809,8 +809,8 @@
args->size))
return -EFAULT;
- ret = fault_in_pages_readable((char __user *)(uintptr_t)args->data_ptr,
- args->size);
+ ret = fault_in_multipages_readable((char __user *)(uintptr_t)args->data_ptr,
+ args->size);
if (ret)
return -EFAULT;