On Tue, Dec 04, 2007 at 08:01:31AM +0100, Nick Piggin wrote:
> Thanks for the review, I'll post an incremental patch in a sec.
Index: linux-2.6/drivers/block/brd.c
===================================================================
--- linux-2.6.orig/drivers/block/brd.c
+++ linux-2.6/drivers/block/brd.c
@@ -56,7 +56,7 @@ struct brd_device {
*/
static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector)
{
- unsigned long idx;
+ pgoff_t idx;
struct page *page;
/*
@@ -87,13 +87,17 @@ static struct page *brd_lookup_page(stru
*/
static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
{
- unsigned long idx;
+ pgoff_t idx;
struct page *page;
page = brd_lookup_page(brd, sector);
if (page)
return page;
+ /*
+ * Must use NOIO because we don't want to recurse back into the
+ * block or filesystem layers from page reclaim.
+ */
page = alloc_page(GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO);
if (!page)
return NULL;
@@ -148,6 +152,11 @@ static void brd_free_pages(struct brd_de
pos++;
+ /*
+ * This assumes radix_tree_gang_lookup always returns as
+ * many pages as possible. If the radix-tree code changes,
+ * so will this have to.
+ */
} while (nr_pages == FREE_BATCH);
}
@@ -159,7 +168,7 @@ static int copy_to_brd_setup(struct brd_
unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
size_t copy;
- copy = min((unsigned long)n, PAGE_SIZE - offset);
+ copy = min_t(size_t, n, PAGE_SIZE - offset);
if (!brd_insert_page(brd, sector))
return -ENOMEM;
if (copy < n) {
@@ -181,7 +190,7 @@ static void copy_to_brd(struct brd_devic
unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
size_t copy;
- copy = min((unsigned long)n, PAGE_SIZE - offset);
+ copy = min_t(size_t, n, PAGE_SIZE - offset);
page = brd_lookup_page(brd, sector);
BUG_ON(!page);
@@ -213,7 +222,7 @@ static void copy_from_brd(void *dst, str
unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
size_t copy;
- copy = min((unsigned long)n, PAGE_SIZE - offset);
+ copy = min_t(size_t, n, PAGE_SIZE - offset);
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page, KM_USER1);
@@ -318,6 +327,9 @@ static int brd_ioctl(struct inode *inode
/*
* Invalidate the cache first, so it isn't written
* back to the device.
+ *
+ * Another thread might instantiate more buffercache here,
+ * but there is not much we can do to close that race.
*/
invalidate_bh_lrus();
truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
-
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