return pfn from direct_access, for XIP

Alter the block device ->direct_access() API to work with the new
get_xip_mem() API (that requires both kaddr and pfn are returned).

Some architectures will not do the right thing in their virt_to_page() for use
by XIP (to translate from the kernel virtual address returned by
direct_access(), to a user mappable pfn in XIP's page fault handler.

However, we can't switch it to just return the pfn and not the kaddr, because
we have no good way to get a kva from a pfn, and XIP requires the kva for its
read(2) and write(2) handlers.  So we have to return both.

Signed-off-by: Jared Hulbert <jaredeh@gmail.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-mm@kvack.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 7bd7663..e8e38fa 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -319,7 +319,7 @@ out:
 
 #ifdef CONFIG_BLK_DEV_XIP
 static int brd_direct_access (struct block_device *bdev, sector_t sector,
-			unsigned long *data)
+			void **kaddr, unsigned long *pfn)
 {
 	struct brd_device *brd = bdev->bd_disk->private_data;
 	struct page *page;
@@ -333,7 +333,8 @@ static int brd_direct_access (struct block_device *bdev, sector_t sector,
 	page = brd_insert_page(brd, sector);
 	if (!page)
 		return -ENOMEM;
-	*data = (unsigned long)page_address(page);
+	*kaddr = page_address(page);
+	*pfn = page_to_pfn(page);
 
 	return 0;
 }