mm: replace get_vaddr_frames() write/force parameters with gup_flags

This removes the 'write' and 'force' from get_vaddr_frames() and
replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 11 insertions, 15 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index aa92decf4233..fbd13fabdf2d 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -488,7 +488,8 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
                 goto err_free;
         }
 
-        ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec);
+        ret = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
+                g2d_userptr->vec);
         if (ret != npages) {
                 DRM_ERROR("failed to get user pages from userptr.\n");
                 if (ret < 0)
diff --git a/drivers/media/platform/omap/omap_vout.c b/drivers/media/platform/omap/omap_vout.c
index e668dde6d857..a31b95cb3b09 100644
--- a/drivers/media/platform/omap/omap_vout.c
+++ b/drivers/media/platform/omap/omap_vout.c
@@ -214,7 +214,7 @@ static int omap_vout_get_userptr(struct videobuf_buffer *vb, u32 virtp,
         if (!vec)
                 return -ENOMEM;
 
-        ret = get_vaddr_frames(virtp, 1, true, false, vec);
+        ret = get_vaddr_frames(virtp, 1, FOLL_WRITE, vec);
         if (ret != 1) {
                 frame_vector_destroy(vec);
                 return -EINVAL;
diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c
index 3c3b517f1d1c..1cd322e939c7 100644
--- a/drivers/media/v4l2-core/videobuf2-memops.c
+++ b/drivers/media/v4l2-core/videobuf2-memops.c
@@ -42,6 +42,10 @@ struct frame_vector *vb2_create_framevec(unsigned long start,
         unsigned long first, last;
         unsigned long nr;
         struct frame_vector *vec;
+        unsigned int flags = FOLL_FORCE;
+
+        if (write)
+                flags |= FOLL_WRITE;
 
         first = start >> PAGE_SHIFT;
         last = (start + length - 1) >> PAGE_SHIFT;
@@ -49,7 +53,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start,
         vec = frame_vector_create(nr);
         if (!vec)
                 return ERR_PTR(-ENOMEM);
-        ret = get_vaddr_frames(start & PAGE_MASK, nr, write, true, vec);
+        ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
         if (ret < 0)
                 goto out_destroy;
         /* We accept only complete set of PFNs */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9fe9b0438169..91cc923ce985 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1305,7 +1305,7 @@ struct frame_vector {
 struct frame_vector *frame_vector_create(unsigned int nr_frames);
 void frame_vector_destroy(struct frame_vector *vec);
 int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
-                     bool write, bool force, struct frame_vector *vec);
+                     unsigned int gup_flags, struct frame_vector *vec);
 void put_vaddr_frames(struct frame_vector *vec);
 int frame_vector_to_pages(struct frame_vector *vec);
 void frame_vector_to_pfns(struct frame_vector *vec);
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 81b67498bb9c..db77dcb38afd 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -11,10 +11,7 @@
  * get_vaddr_frames() - map virtual addresses to pfns
  * @start:      starting user address
  * @nr_frames:  number of pages / pfns from start to map
- * @write:      whether pages will be written to by the caller
- * @force:      whether to force write access even if user mapping is
- *              readonly. See description of the same argument of
-                get_user_pages().
+ * @gup_flags:  flags modifying lookup behaviour
  * @vec:        structure which receives pages / pfns of the addresses mapped.
  *              It should have space for at least nr_frames entries.
  *
@@ -34,23 +31,17 @@
  * This function takes care of grabbing mmap_sem as necessary.
  */
 int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
-                     bool write, bool force, struct frame_vector *vec)
+                     unsigned int gup_flags, struct frame_vector *vec)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
         int ret = 0;
         int err;
         int locked;
-        unsigned int gup_flags = 0;
 
         if (nr_frames == 0)
                 return 0;
 
-        if (write)
-                gup_flags |= FOLL_WRITE;
-        if (force)
-                gup_flags |= FOLL_FORCE;
-
         if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
                 nr_frames = vec->nr_allocated;