[PATCH] Support compat_ioctl for block devices

Support passing down of compat_ioctl on block devices.  This is needed for
the compat_ioctl conversion of block drivers.
Signed-off-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/block/ioctl.c

@@ -3,6 +3,7 @@
 #include <linux/blkpg.h>
 #include <linux/backing-dev.h>
 #include <linux/buffer_head.h>
+#include <linux/smp_lock.h>
 #include <asm/uaccess.h>
 
 static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg)
@@ -220,3 +221,19 @@ int blkdev_ioctl(struct inode *inode, struct file *file, unsigned cmd,
 	}
 	return -ENOTTY;
 }
+
+/* Most of the generic ioctls are handled in the normal fallback path.
+   This assumes the blkdev's low level compat_ioctl always returns
+   ENOIOCTLCMD for unknown ioctls. */
+long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
+{
+	struct block_device *bdev = file->f_dentry->d_inode->i_bdev;
+	struct gendisk *disk = bdev->bd_disk;
+	int ret = -ENOIOCTLCMD;
+	if (disk->fops->compat_ioctl) {
+		lock_kernel();
+		ret = disk->fops->compat_ioctl(file, cmd, arg);
+		unlock_kernel();
+	}
+	return ret;
+}

fs/block_dev.c

@@ -804,6 +804,9 @@ struct file_operations def_blk_fops = {
 	.mmap		= generic_file_mmap,
 	.fsync		= block_fsync,
 	.ioctl		= block_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= compat_blkdev_ioctl,
+#endif
 	.readv		= generic_file_readv,
 	.writev		= generic_file_write_nolock,
 	.sendfile	= generic_file_sendfile,

include/linux/fs.h

@@ -879,6 +879,7 @@ struct block_device_operations {
 	int (*open) (struct inode *, struct file *);
 	int (*release) (struct inode *, struct file *);
 	int (*ioctl) (struct inode *, struct file *, unsigned, unsigned long);
+	long (*compat_ioctl) (struct file *, unsigned, unsigned long);
 	int (*media_changed) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);
 	struct module *owner;
@@ -1291,6 +1292,7 @@ extern struct file_operations bad_sock_fops;
 extern struct file_operations def_fifo_fops;
 extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
 extern int blkdev_ioctl(struct inode *, struct file *, unsigned, unsigned long);
+extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
 extern int blkdev_get(struct block_device *, mode_t, unsigned);
 extern int blkdev_put(struct block_device *);
 extern int bd_claim(struct block_device *, void *);