[intel-gem] Once mapped, leave buffers mapped.

Mapping and unmapping buffers is expensive, and having the map around isn't
harmful (other than consuming address space). So, once mapped, just leave
buffers mapped in case they get re-used.

src/mesa/drivers/dri/intel/intel_bufmgr_gem.c

@@ -107,7 +107,7 @@ typedef struct _dri_bo_gem {
     dri_bo bo;
 
     int refcount;
-    unsigned int map_count;
+    GLboolean mapped;
     uint32_t gem_handle;
     const char *name;
 
@@ -412,7 +412,8 @@ dri_gem_bo_unreference(dri_bo *bo)
 	struct dri_gem_bo_bucket *bucket;
 	int ret;
 
-	assert(bo_gem->map_count == 0);
+	if (bo_gem->mapped)
+	    munmap (bo_gem->virtual, bo->size);
 
 	if (bo_gem->relocs != NULL) {
 	    int i;
@@ -474,7 +475,7 @@ dri_gem_bo_map(dri_bo *bo, GLboolean write_enable)
     /* Allow recursive mapping. Mesa may recursively map buffers with
      * nested display loops.
      */
-    if (bo_gem->map_count++ == 0) {
+    if (!bo_gem->mapped) {
     
 	assert(bo->virtual == NULL);
     
@@ -496,6 +497,7 @@ dri_gem_bo_map(dri_bo *bo, GLboolean write_enable)
 	    bo_gem->virtual = (void *)(uintptr_t)mmap_arg.addr_ptr;
 	}
 	bo->virtual = bo_gem->virtual;
+	bo_gem->mapped = GL_TRUE;
 	DBG("bo_map: %d (%s) -> %p\n", bo_gem->gem_handle, bo_gem->name, bo_gem->virtual);
     }
 
@@ -519,25 +521,12 @@ dri_gem_bo_map(dri_bo *bo, GLboolean write_enable)
 static int
 dri_gem_bo_unmap(dri_bo *bo)
 {
-    dri_bufmgr_gem *bufmgr_gem;
     dri_bo_gem *bo_gem = (dri_bo_gem *)bo;
 
     if (bo == NULL)
 	return 0;
 
-    assert(bo_gem->map_count != 0);
-    if (--bo_gem->map_count != 0)
-	return 0;
-
-    bufmgr_gem = (dri_bufmgr_gem *)bo->bufmgr;
-
-    assert(bo->virtual != NULL);
-
-    DBG("bo_unmap: %d (%s)\n", bo_gem->gem_handle, bo_gem->name);
-
-    munmap(bo_gem->virtual, bo->size);
-    bo_gem->virtual = NULL;
-    bo->virtual = NULL;
+    assert(bo_gem->mapped);
 
     return 0;
 }