compat_ioctl: block: simplify compat_blkpg_ioctl()

There is no need to go through a compat_alloc_user_space()
copy any more, just wrap the function in a small helper that
works the same way for native and compat mode.

Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/block/ioctl.c b/block/ioctl.c
index f8c4e26..d6911a1 100644 (file)
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -12,12 +12,12 @@
 #include <linux/pr.h>
 #include <linux/uaccess.h>
 
-static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg)
+static int blkpg_do_ioctl(struct block_device *bdev,
+                         struct blkpg_partition __user *upart, int op)
 {
        struct block_device *bdevp;
        struct gendisk *disk;
        struct hd_struct *part, *lpart;
-       struct blkpg_ioctl_arg a;
        struct blkpg_partition p;
        struct disk_part_iter piter;
        long long start, length;
@@ -25,9 +25,7 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
 
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
-       if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
-               return -EFAULT;
-       if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
+       if (copy_from_user(&p, upart, sizeof(struct blkpg_partition)))
                return -EFAULT;
        disk = bdev->bd_disk;
        if (bdev != bdev->bd_contains)
@@ -35,7 +33,7 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
        partno = p.pno;
        if (partno <= 0)
                return -EINVAL;
-       switch (a.op) {
+       switch (op) {
                case BLKPG_ADD_PARTITION:
                        start = p.start >> 9;
                        length = p.length >> 9;
@@ -156,6 +154,39 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
        }
 }
 
+static int blkpg_ioctl(struct block_device *bdev,
+                      struct blkpg_ioctl_arg __user *arg)
+{
+       struct blkpg_partition __user *udata;
+       int op;
+
+       if (get_user(op, &arg->op) || get_user(udata, &arg->data))
+               return -EFAULT;
+
+       return blkpg_do_ioctl(bdev, udata, op);
+}
+
+#ifdef CONFIG_COMPAT
+struct compat_blkpg_ioctl_arg {
+       compat_int_t op;
+       compat_int_t flags;
+       compat_int_t datalen;
+       compat_caddr_t data;
+};
+
+static int compat_blkpg_ioctl(struct block_device *bdev,
+                             struct compat_blkpg_ioctl_arg __user *arg)
+{
+       compat_caddr_t udata;
+       int op;
+
+       if (get_user(op, &arg->op) || get_user(udata, &arg->data))
+               return -EFAULT;
+
+       return blkpg_do_ioctl(bdev, compat_ptr(udata), op);
+}
+#endif
+
 static int blkdev_reread_part(struct block_device *bdev)
 {
        int ret;
@@ -676,35 +707,6 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 EXPORT_SYMBOL_GPL(blkdev_ioctl);
 
 #ifdef CONFIG_COMPAT
-struct compat_blkpg_ioctl_arg {
-       compat_int_t op;
-       compat_int_t flags;
-       compat_int_t datalen;
-       compat_caddr_t data;
-};
-
-static int compat_blkpg_ioctl(struct block_device *bdev, fmode_t mode,
-               unsigned int cmd, struct compat_blkpg_ioctl_arg __user *ua32)
-{
-       struct blkpg_ioctl_arg __user *a = compat_alloc_user_space(sizeof(*a));
-       compat_caddr_t udata;
-       compat_int_t n;
-       int err;
-
-       err = get_user(n, &ua32->op);
-       err |= put_user(n, &a->op);
-       err |= get_user(n, &ua32->flags);
-       err |= put_user(n, &a->flags);
-       err |= get_user(n, &ua32->datalen);
-       err |= put_user(n, &a->datalen);
-       err |= get_user(udata, &ua32->data);
-       err |= put_user(compat_ptr(udata), &a->data);
-       if (err)
-               return err;
-
-       return blkdev_ioctl(bdev, mode, cmd, (unsigned long)a);
-}
-
 #define BLKBSZGET_32           _IOR(0x12, 112, int)
 #define BLKBSZSET_32           _IOW(0x12, 113, int)
 #define BLKGETSIZE64_32                _IOR(0x12, 114, int)
@@ -767,7 +769,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
                return blkdev_ioctl(bdev, mode, BLKBSZSET,
                                (unsigned long)compat_ptr(arg));
        case BLKPG:
-               return compat_blkpg_ioctl(bdev, mode, cmd, compat_ptr(arg));
+               return compat_blkpg_ioctl(bdev, compat_ptr(arg));
        case BLKRAGET:
        case BLKFRAGET:
                if (!arg)