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SubjectRe: [PATCH] vhost: correctly set bits of dirty pages
On Mon, Nov 29, 2010 at 01:48:20PM +0800, Jason Wang wrote:
> When counting pages we should increase it by 1 instead of VHOST_PAGE_SIZE,
> and also make log_write() can correctly process the request across
> pages with write_address not start at page boundary.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>


Thanks, good catch!
But let's to it in small steps: first, a small patch to fix the bug:
I think this is equivalent, right?

Subject: vhost: correctly set bits of dirty pages

When counting pages we should increase address by 1 instead of
VHOST_PAGE_SIZE, and also make log_write() can correctly process the
request across pages with write_address not starting at page boundary.

Reported-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

---

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 568eb70..d0a3552 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -887,6 +887,7 @@ static int log_write(void __user *log_base,
int r;
if (!write_length)
return 0;
+ write_length += write_address % VHOST_PAGE_SIZE;
write_address /= VHOST_PAGE_SIZE;
for (;;) {
u64 base = (u64)(unsigned long)log_base;
@@ -900,7 +901,7 @@ static int log_write(void __user *log_base,
if (write_length <= VHOST_PAGE_SIZE)
break;
write_length -= VHOST_PAGE_SIZE;
- write_address += VHOST_PAGE_SIZE;
+ write_address += 1;
}
return r;
}

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