loop: Rework lo_ioctl() __user argument casting

In preparation for a new ioctl that needs to copy_from_user(); makes the
code easier to read as well.

Signed-off-by: Martijn Coenen <maco@android.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4dc11d9..31f10da 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1634,6 +1634,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
        unsigned int cmd, unsigned long arg)
 {
        struct loop_device *lo = bdev->bd_disk->private_data;
+       void __user *argp = (void __user *) arg;
        int err;
 
        switch (cmd) {
@@ -1646,21 +1647,19 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
        case LOOP_SET_STATUS:
                err = -EPERM;
                if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
-                       err = loop_set_status_old(lo,
-                                       (struct loop_info __user *)arg);
+                       err = loop_set_status_old(lo, argp);
                }
                break;
        case LOOP_GET_STATUS:
-               return loop_get_status_old(lo, (struct loop_info __user *) arg);
+               return loop_get_status_old(lo, argp);
        case LOOP_SET_STATUS64:
                err = -EPERM;
                if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
-                       err = loop_set_status64(lo,
-                                       (struct loop_info64 __user *) arg);
+                       err = loop_set_status64(lo, argp);
                }
                break;
        case LOOP_GET_STATUS64:
-               return loop_get_status64(lo, (struct loop_info64 __user *) arg);
+               return loop_get_status64(lo, argp);
        case LOOP_SET_CAPACITY:
        case LOOP_SET_DIRECT_IO:
        case LOOP_SET_BLOCK_SIZE: