llvmpipe: Allocate texture storage for whole quads.

src/gallium/drivers/llvmpipe/lp_texture.c

    pf_get_block(lpt->base.format, &lpt->base.block);
 
    for (level = 0; level <= pt->last_level; level++) {
+      unsigned nblocksx, nblocksy;
+
       pt->width[level] = width;
       pt->height[level] = height;
       pt->depth[level] = depth;
       pt->nblocksx[level] = pf_get_nblocksx(&pt->block, width);  
-      pt->nblocksy[level] = pf_get_nblocksy(&pt->block, height);  
-      lpt->stride[level] = align(pt->nblocksx[level]*pt->block.size, 16);
+      pt->nblocksy[level] = pf_get_nblocksy(&pt->block, height);
+
+      /* Allocate storage for whole quads. This is particularly important
+       * for depth surfaces, which are currently stored in a swizzled format. */
+      nblocksx = pf_get_nblocksx(&pt->block, align(width, 2));
+      nblocksy = pf_get_nblocksy(&pt->block, align(height, 2));
+
+      lpt->stride[level] = align(nblocksx*pt->block.size, 16);
 
       lpt->level_offset[level] = buffer_size;
 
-      buffer_size += (pt->nblocksy[level] *
+      buffer_size += (nblocksy *
                       ((pt->target == PIPE_TEXTURE_CUBE) ? 6 : depth) *
                       lpt->stride[level]);