From: Michael S. Tsirkin <mst@redhat.com>
Date: Mon, 29 Nov 2010 08:19:07 +0000 (+0200)
Subject: vhost: correctly set bits of dirty pages
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=3bf9be40ff76b6df136f14a497167c116b2b3c53;p=linux-beck.git

vhost: correctly set bits of dirty pages

Fix two bugs in dirty page logging:
When counting pages we should increase address by 1 instead of
VHOST_PAGE_SIZE. Make log_write() correctly process requests
that cross 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 916cdbc279e0..4c256d15c249 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -885,6 +885,7 @@ 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;
@@ -898,7 +899,7 @@ 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;
 }