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, 5 insertions, 3 deletions

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 04787eab1016..bb52d2fbac18 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -36,7 +36,7 @@ static int dcssblk_open(struct inode *inode, struct file *filp);
 static int dcssblk_release(struct inode *inode, struct file *filp);
 static int dcssblk_make_request(struct request_queue *q, struct bio *bio);
 static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
-				 unsigned long *data);
+				 void **kaddr, unsigned long *pfn);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -636,7 +636,7 @@ fail:
 
 static int
 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
-			unsigned long *data)
+			void **kaddr, unsigned long *pfn)
 {
 	struct dcssblk_dev_info *dev_info;
 	unsigned long pgoff;
@@ -649,7 +649,9 @@ dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 	pgoff = secnum / (PAGE_SIZE / 512);
 	if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
 		return -ERANGE;
-	*data = (unsigned long) (dev_info->start+pgoff*PAGE_SIZE);
+	*kaddr = (void *) (dev_info->start+pgoff*PAGE_SIZE);
+	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
+
 	return 0;
 }