drm/i915: Initialise i915_gem_object_create_from_data() directly

Use pagecache_write to avoid shmemfs clearing the pages prior to us
immediately overwriting them with our data.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170317194648.12468-2-chris@chris-wilson.co.uk
Reviewed-by: Matthew Auld <matthew.auld@intel.com>

1 files changed, 29 insertions, 16 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3492f8d27c32..58e1db77d70e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4953,9 +4953,9 @@ i915_gem_object_create_from_data(struct drm_i915_private *dev_priv,
                                  const void *data, size_t size)
 {
         struct drm_i915_gem_object *obj;
-        struct sg_table *sg;
-        size_t bytes;
-        int ret;
+        struct file *file;
+        size_t offset;
+        int err;
 
         obj = i915_gem_object_create(dev_priv, round_up(size, PAGE_SIZE));
         if (IS_ERR(obj))
@@ -4963,26 +4963,39 @@ i915_gem_object_create_from_data(struct drm_i915_private *dev_priv,
 
         GEM_BUG_ON(obj->base.write_domain != I915_GEM_DOMAIN_CPU);
 
-        ret = i915_gem_object_pin_pages(obj);
-        if (ret)
-                goto fail;
+        file = obj->base.filp;
+        offset = 0;
+        do {
+                unsigned int len = min_t(typeof(size), size, PAGE_SIZE);
+                struct page *page;
+                void *pgdata, *vaddr;
 
-        sg = obj->mm.pages;
-        bytes = sg_copy_from_buffer(sg->sgl, sg->nents, (void *)data, size);
-        obj->mm.dirty = true; /* Backing store is now out of date */
-        i915_gem_object_unpin_pages(obj);
+                err = pagecache_write_begin(file, file->f_mapping,
+                                            offset, len, 0,
+                                            &page, &pgdata);
+                if (err < 0)
+                        goto fail;
 
-        if (WARN_ON(bytes != size)) {
-                DRM_ERROR("Incomplete copy, wrote %zu of %zu", bytes, size);
-                ret = -EFAULT;
-                goto fail;
-        }
+                vaddr = kmap(page);
+                memcpy(vaddr, data, len);
+                kunmap(page);
+
+                err = pagecache_write_end(file, file->f_mapping,
+                                          offset, len, len,
+                                          page, pgdata);
+                if (err < 0)
+                        goto fail;
+
+                size -= len;
+                data += len;
+                offset += len;
+        } while (size);
 
         return obj;
 
 fail:
         i915_gem_object_put(obj);
-        return ERR_PTR(ret);
+        return ERR_PTR(err);
 }
 
 struct scatterlist *