block: Change direct_access calling convention

In order to support accesses to larger chunks of memory, pass in a
'size' parameter (counted in bytes), and return the amount available at
that address.

Add a new helper function, bdev_direct_access(), to handle common
functionality including partition handling, checking the length requested
is positive, checking for the sector being page-aligned, and checking
the length of the request does not pass the end of the partition.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 4 insertions, 13 deletions

diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index f532c92bf99d..20f8afe855d1 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -139,26 +139,17 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
  * axon_ram_direct_access - direct_access() method for block device
  * @device, @sector, @data: see block_device_operations method
  */
-static int
+static long
 axon_ram_direct_access(struct block_device *device, sector_t sector,
-                       void **kaddr, unsigned long *pfn)
+                       void **kaddr, unsigned long *pfn, long size)
 {
         struct axon_ram_bank *bank = device->bd_disk->private_data;
-        loff_t offset;
-
-        offset = sector;
-        if (device->bd_part != NULL)
-                offset += device->bd_part->start_sect;
-        offset <<= AXON_RAM_SECTOR_SHIFT;
-        if (offset >= bank->size) {
-                dev_err(&bank->device->dev, "Access outside of address space\n");
-                return -ERANGE;
-        }
+        loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
 
         *kaddr = (void *)(bank->ph_addr + offset);
         *pfn = virt_to_phys(kaddr) >> PAGE_SHIFT;
 
-        return 0;
+        return bank->size - offset;
 }
 
 static const struct block_device_operations axon_ram_devops = {