[PATCH v5 17/38] scsi: sg: convert mmap hook to mmap_prepare and rework

@@ -1212,85 +1212,72 @@ sg_fasync(int fd, struct file *filp, int mode)
 	return fasync_helper(fd, filp, mode, &sfp->async_qp);
 }
 
-static vm_fault_t
-sg_vma_fault(struct vm_fault *vmf)
+static int sg_discontig_init(void *vm_private_data, void **private)
 {
-	struct vm_area_struct *vma = vmf->vma;
-	Sg_fd *sfp;
-	unsigned long offset, len, sa;
-	Sg_scatter_hold *rsv_schp;
-	int k, length;
-
-	if ((NULL == vma) || (!(sfp = (Sg_fd *) vma->vm_private_data)))
-		return VM_FAULT_SIGBUS;
-	rsv_schp = &sfp->reserve;
-	offset = vmf->pgoff << PAGE_SHIFT;
-	if (offset >= rsv_schp->bufflen)
-		return VM_FAULT_SIGBUS;
-	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
-				      "sg_vma_fault: offset=%lu, scatg=%d\n",
-				      offset, rsv_schp->k_use_sg));
-	sa = vma->vm_start;
-	length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
-	for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
-		len = vma->vm_end - sa;
-		len = (len < length) ? len : length;
-		if (offset < len) {
-			struct page *page = rsv_schp->pages[k] + (offset >> PAGE_SHIFT);
-			get_page(page);	/* increment page count */
-			vmf->page = page;
-			return 0; /* success */
-		}
-		sa += len;
-		offset -= len;
+	const unsigned long req_sz = (unsigned long)*private;
+	Sg_fd *sfp = vm_private_data;
+	Sg_scatter_hold *rsv_schp = &sfp->reserve;
+	int err = 0;
+
+	mutex_lock(&sfp->f_mutex);
+	if (req_sz > rsv_schp->bufflen) {
+		err = -ENOMEM;	/* cannot map more than reserved buffer */
+		goto out;
+	}
+	sfp->mmap_called = 1; /* Prevents changes to buffer size. */
+out:
+	mutex_unlock(&sfp->f_mutex);
+	return err;
+}
+
+static int
+sg_discontig_get(struct discontig_kernel_page_state *state)
+{
+	Sg_fd *sfp = state->vm_private_data;
+	Sg_scatter_hold *rsv_schp = &sfp->reserve;
+	const unsigned int order = rsv_schp->page_order;
+	const pgoff_t nr_pages = state->nr_pages_mapped;
+
+	if (nr_pages >= (rsv_schp->bufflen >> PAGE_SHIFT)) {
+		discontig_kernel_map_abort(state);
+		return 0;
 	}
 
-	return VM_FAULT_SIGBUS;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
+				      "%s: offset=%lu, scatg=%d\n", __func__,
+				      nr_pages << PAGE_SHIFT, rsv_schp->k_use_sg));
+
+	discontig_kernel_map_page(state, rsv_schp->pages[nr_pages >> order]);
+	return 0;
 }
 
-static const struct vm_operations_struct sg_mmap_vm_ops = {
-	.fault = sg_vma_fault,
+static const struct discontig_kernel_page_ops sg_discontig_ops = {
+	.init = sg_discontig_init,
+	.get = sg_discontig_get,
 };
 
 static int
-sg_mmap(struct file *filp, struct vm_area_struct *vma)
+sg_mmap_prepare(struct vm_area_desc *desc)
 {
-	Sg_fd *sfp;
-	unsigned long req_sz, len, sa;
-	Sg_scatter_hold *rsv_schp;
-	int k, length;
-	int ret = 0;
+	Sg_fd *sfp = desc->file->private_data;
+	const unsigned long req_sz = vma_desc_size(desc);
 
-	if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data)))
+	if (!sfp)
 		return -ENXIO;
-	req_sz = vma->vm_end - vma->vm_start;
+
 	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
 				      "sg_mmap starting, vm_start=%p, len=%d\n",
-				      (void *) vma->vm_start, (int) req_sz));
-	if (vma->vm_pgoff)
+				      (void *) desc->start, (int) req_sz));
+
+	if (desc->pgoff)
 		return -EINVAL;	/* want no offset */
-	rsv_schp = &sfp->reserve;
-	mutex_lock(&sfp->f_mutex);
-	if (req_sz > rsv_schp->bufflen) {
-		ret = -ENOMEM;	/* cannot map more than reserved buffer */
-		goto out;
-	}
 
-	sa = vma->vm_start;
-	length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
-	for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
-		len = vma->vm_end - sa;
-		len = (len < length) ? len : length;
-		sa += len;
-	}
+	vma_desc_set_flags(desc, VMA_DONTEXPAND_BIT, VMA_DONTDUMP_BIT);
+	desc->private_data = sfp;
 
-	sfp->mmap_called = 1;
-	vm_flags_set(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP);
-	vma->vm_private_data = sfp;
-	vma->vm_ops = &sg_mmap_vm_ops;
-out:
-	mutex_unlock(&sfp->f_mutex);
-	return ret;
+	mmap_action_map_discontig_kernel_pages(desc, (void *)req_sz,
+					       &sg_discontig_ops);
+	return 0;
 }
 
 static void

@@ -1415,7 +1402,7 @@ static const struct file_operations sg_fops = {
 	.unlocked_ioctl = sg_ioctl,
 	.compat_ioctl = compat_ptr_ioctl,
 	.open = sg_open,
-	.mmap = sg_mmap,
+	.mmap_prepare = sg_mmap_prepare,
 	.release = sg_release,
 	.fasync = sg_fasync,
 };