Re: [patch 10/18] sg: nopage

From: Douglas Gilbert
Date: Thu Feb 07 2008 - 22:45:48 EST


For the patch shown below:

Signed-off-by: Douglas Gilbert <dougg@xxxxxxxxxx>



npiggin@xxxxxxx wrote:
Convert SG from nopage to fault.

Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Cc: dgilbert@xxxxxxxxxxxx
Cc: linux-scsi@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
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


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