[Xen-devel] [PATCH 4/6] xen-gntdev: Use find_vma rather than iterating our vma list manually

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

This should be faster if many mappings exist, and also removes
the only user of vma that is not related to PTE modification.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
 drivers/xen/gntdev.c |   34 ++++++++++------------------------
 1 files changed, 10 insertions(+), 24 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 773b76c..a73f07c 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -74,6 +74,8 @@ struct grant_map {
        struct granted_page pages[0];
 };
 
+static struct vm_operations_struct gntdev_vmops;
+
 /* ------------------------------------------------------------------ */
 
 static void gntdev_print_maps(struct gntdev_priv *priv,
@@ -142,23 +144,6 @@ static struct grant_map *gntdev_find_map_index(struct 
gntdev_priv *priv, int ind
        return NULL;
 }
 
-static struct grant_map *gntdev_find_map_vaddr(struct gntdev_priv *priv,
-                                              unsigned long vaddr)
-{
-       struct grant_map *map;
-
-       list_for_each_entry(map, &priv->maps, next) {
-               if (!map->vma)
-                       continue;
-               if (vaddr < map->vma->vm_start)
-                       continue;
-               if (vaddr >= map->vma->vm_end)
-                       continue;
-               return map;
-       }
-       return NULL;
-}
-
 static int gntdev_del_map(struct grant_map *map)
 {
        int i;
@@ -510,6 +495,7 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct 
gntdev_priv *priv,
                                              struct 
ioctl_gntdev_get_offset_for_vaddr __user *u)
 {
        struct ioctl_gntdev_get_offset_for_vaddr op;
+       struct vm_area_struct *vma;
        struct grant_map *map;
 
        if (copy_from_user(&op, u, sizeof(op)) != 0)
@@ -518,16 +504,16 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct 
gntdev_priv *priv,
                printk("%s: priv %p, offset for vaddr %lx\n", __FUNCTION__, 
priv,
                       (unsigned long)op.vaddr);
 
-       spin_lock(&priv->lock);
-       map = gntdev_find_map_vaddr(priv, op.vaddr);
-       if (map == NULL ||
-           map->vma->vm_start != op.vaddr) {
-               spin_unlock(&priv->lock);
+       vma = find_vma(current->mm, op.vaddr);
+       if (!vma)
                return -EINVAL;
-       }
+
+       map = vma->vm_private_data;
+       if (vma->vm_ops != &gntdev_vmops || !map)
+               return -EINVAL;
+
        op.offset = map->index << PAGE_SHIFT;
        op.count = map->count;
-       spin_unlock(&priv->lock);
 
        if (copy_to_user(u, &op, sizeof(op)) != 0)
                return -EFAULT;
-- 
1.7.2.3


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