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 <[e-mail]>
Signed-off-by: Nick Piggin <[e-mail]>
Cc: Carsten Otte <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: [e-mail]
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/powerpc/sysdev/axonram.c

···
  */
 static int
 axon_ram_direct_access(struct block_device *device, sector_t sector,
-		       unsigned long *data)
+		       void **kaddr, unsigned long *pfn)
 {
 	struct axon_ram_bank *bank = device->bd_disk->private_data;
 	loff_t offset;
···
 		return -ERANGE;
 	}
 
-	*data = bank->ph_addr + offset;
+	*kaddr = (void *)(bank->ph_addr + offset);
+	*pfn = virt_to_phys(kaddr) >> PAGE_SHIFT;
 
 	return 0;
 }

drivers/block/brd.c

···
 
 #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;
···
 	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;
 }

drivers/s390/block/dcssblk.c

···
 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";
 
···
 
 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;
···
 	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;
 }
 

fs/ext2/xip.c

···
 
 static inline int
 __inode_direct_access(struct inode *inode, sector_t sector,
-		      unsigned long *data)
+		      void **kaddr, unsigned long *pfn)
 {
-	BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
-	return inode->i_sb->s_bdev->bd_disk->fops
-		->direct_access(inode->i_sb->s_bdev,sector,data);
+	struct block_device *bdev = inode->i_sb->s_bdev;
+	struct block_device_operations *ops = bdev->bd_disk->fops;
+
+	BUG_ON(!ops->direct_access);
+	return ops->direct_access(bdev, sector, kaddr, pfn);
 }
 
 static inline int
···
 ext2_clear_xip_target(struct inode *inode, int block)
 {
 	sector_t sector = block * (PAGE_SIZE/512);
-	unsigned long data;
+	void *kaddr;
+	unsigned long pfn;
 	int rc;
 
-	rc = __inode_direct_access(inode, sector, &data);
+	rc = __inode_direct_access(inode, sector, &kaddr, &pfn);
 	if (!rc)
-		clear_page((void*)data);
+		clear_page(kaddr);
 	return rc;
 }
 
···
 		   int create)
 {
 	int rc;
-	unsigned long data;
+	void *kaddr;
+	unsigned long pfn;
 	sector_t sector;
 
 	/* first, retrieve the sector number */
···
 
 	/* retrieve address of the target data */
 	rc = __inode_direct_access
-		(mapping->host, sector * (PAGE_SIZE/512), &data);
+		(mapping->host, sector * (PAGE_SIZE/512), &kaddr, &pfn);
 	if (!rc)
-		return virt_to_page(data);
+		return pfn_to_page(pfn);
 
  error:
 	return ERR_PTR(rc);

include/linux/fs.h

···
 	int (*ioctl) (struct inode *, struct file *, unsigned, unsigned long);
 	long (*unlocked_ioctl) (struct file *, unsigned, unsigned long);
 	long (*compat_ioctl) (struct file *, unsigned, unsigned long);
-	int (*direct_access) (struct block_device *, sector_t, unsigned long *);
+	int (*direct_access) (struct block_device *, sector_t,
+						void **, unsigned long *);
 	int (*media_changed) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);
 	int (*getgeo)(struct block_device *, struct hd_geometry *);