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>

5 files changed, 27 insertions, 18 deletions

diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index d359d6e92975..7f59188cd9a1 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -143,7 +143,7 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
  */
 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;
@@ -154,7 +154,8 @@ axon_ram_direct_access(struct block_device *device, sector_t sector,
                 return -ERANGE;
         }
 
-        *data = bank->ph_addr + offset;
+        *kaddr = (void *)(bank->ph_addr + offset);
+        *pfn = virt_to_phys(kaddr) >> PAGE_SHIFT;
 
         return 0;
 }
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 7bd76639544c..e8e38faeafd8 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;
 }
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;
 }
 
diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
index ca7f00312388..430b4c8ee971 100644
--- a/fs/ext2/xip.c
+++ b/fs/ext2/xip.c
@@ -16,11 +16,13 @@
 
 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
@@ -48,12 +50,13 @@ 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;
 }
 
@@ -74,7 +77,8 @@ ext2_get_xip_page(struct address_space *mapping, sector_t offset,
                    int create)
 {
         int rc;
-        unsigned long data;
+        void *kaddr;
+        unsigned long pfn;
         sector_t sector;
 
         /* first, retrieve the sector number */
@@ -84,9 +88,9 @@ ext2_get_xip_page(struct address_space *mapping, sector_t offset,
 
         /* 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);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d6d7c52055c6..bd05f5678045 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1178,7 +1178,8 @@ struct block_device_operations {
         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 *);