Re: [patch 10/18] sg: nopage

[Douglas Gilbert <dougg@torque.net>]

For the patch shown below:

Signed-off-by: Douglas Gilbert <dougg@torque.net>



npiggin@suse.de wrote:
Convert SG from nopage to fault.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: dgilbert@interlog.com
Cc: linux-scsi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
  drivers/scsi/sg.c |   23 +++++++++++------------
  1 file changed, 11 insertions(+), 12 deletions(-)

Index: linux-2.6/drivers/scsi/sg.c
===================================================================
--- linux-2.6.orig/drivers/scsi/sg.c
+++ linux-2.6/drivers/scsi/sg.c
@@ -1144,23 +1144,22 @@ sg_fasync(int fd, struct file *filp, int
  	return (retval < 0) ? retval : 0;
  }

-static struct page *
-sg_vma_nopage(struct vm_area_struct *vma, unsigned long addr, int *type)
+static int
+sg_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  {
  	Sg_fd *sfp;
-	struct page *page = NOPAGE_SIGBUS;
  	unsigned long offset, len, sa;
  	Sg_scatter_hold *rsv_schp;
  	struct scatterlist *sg;
  	int k;

  	if ((NULL == vma) || (!(sfp = (Sg_fd *) vma->vm_private_data)))
-		return page;
+		return VM_FAULT_SIGBUS;
  	rsv_schp = &sfp->reserve;
-	offset = addr - vma->vm_start;
+	offset = vmf->pgoff << PAGE_SHIFT;
  	if (offset >= rsv_schp->bufflen)
-		return page;
-	SCSI_LOG_TIMEOUT(3, printk("sg_vma_nopage: offset=%lu, scatg=%d\n",
+		return VM_FAULT_SIGBUS;
+	SCSI_LOG_TIMEOUT(3, printk("sg_vma_fault: offset=%lu, scatg=%d\n",
  				   offset, rsv_schp->k_use_sg));
  	sg = rsv_schp->buffer;
  	sa = vma->vm_start;
@@ -1169,21 +1168,21 @@ sg_vma_nopage(struct vm_area_struct *vma
  		len = vma->vm_end - sa;
  		len = (len < sg->length) ? len : sg->length;
  		if (offset < len) {
+			struct page *page;
  			page = virt_to_page(page_address(sg_page(sg)) + offset);
  			get_page(page);	/* increment page count */
-			break;
+			vmf->page = page;
+			return 0; /* success */
  		}
  		sa += len;
  		offset -= len;
  	}

-	if (type)
-		*type = VM_FAULT_MINOR;
-	return page;
+	return VM_FAULT_SIGBUS;
  }

  static struct vm_operations_struct sg_mmap_vm_ops = {
-	.nopage = sg_vma_nopage,
+	.fault = sg_vma_fault,
  };

  static int