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Subject[patch 08/18] fb: defio nopage
Convert fb defio from nopage to fault.
Switch from OOM to SIGBUS if the resource is not available.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: linux-fbdev-devel@lists.sourceforge.net
Cc: jayakumar.lkml@gmail.com
Cc: lethal@linux-sh.org
Cc: linux-kernel@vger.kernel.org
---
Documentation/fb/deferred_io.txt | 6 +++---
drivers/video/fb_defio.c | 17 ++++++++---------
2 files changed, 11 insertions(+), 12 deletions(-)

Index: linux-2.6/drivers/video/fb_defio.c
===================================================================
--- linux-2.6.orig/drivers/video/fb_defio.c
+++ linux-2.6/drivers/video/fb_defio.c
@@ -25,8 +25,8 @@
#include <linux/pagemap.h>

/* this is to find and return the vmalloc-ed fb pages */
-static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
- unsigned long vaddr, int *type)
+static int fb_deferred_io_fault(struct vm_area_struct *vma,
+ struct vm_fault *vmf)
{
unsigned long offset;
struct page *page;
@@ -34,18 +34,17 @@ static struct page* fb_deferred_io_nopag
/* info->screen_base is in System RAM */
void *screen_base = (void __force *) info->screen_base;

- offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
+ offset = vmf->pgoff << PAGE_SHIFT;
if (offset >= info->fix.smem_len)
- return NOPAGE_SIGBUS;
+ return VM_FAULT_SIGBUS;

page = vmalloc_to_page(screen_base + offset);
if (!page)
- return NOPAGE_OOM;
+ return VM_FAULT_SIGBUS;

get_page(page);
- if (type)
- *type = VM_FAULT_MINOR;
- return page;
+ vmf->page = page;
+ return 0;
}

int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
@@ -84,7 +83,7 @@ static int fb_deferred_io_mkwrite(struct
}

static struct vm_operations_struct fb_deferred_io_vm_ops = {
- .nopage = fb_deferred_io_nopage,
+ .fault = fb_deferred_io_fault,
.page_mkwrite = fb_deferred_io_mkwrite,
};

Index: linux-2.6/Documentation/fb/deferred_io.txt
===================================================================
--- linux-2.6.orig/Documentation/fb/deferred_io.txt
+++ linux-2.6/Documentation/fb/deferred_io.txt
@@ -7,10 +7,10 @@ IO. The following example may be a usefu
works:

- userspace app like Xfbdev mmaps framebuffer
-- deferred IO and driver sets up nopage and page_mkwrite handlers
+- deferred IO and driver sets up fault and page_mkwrite handlers
- userspace app tries to write to mmaped vaddress
-- we get pagefault and reach nopage handler
-- nopage handler finds and returns physical page
+- we get pagefault and reach fault handler
+- fault handler finds and returns physical page
- we get page_mkwrite where we add this page to a list
- schedule a workqueue task to be run after a delay
- app continues writing to that page with no additional cost. this is
--



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