Re: [PATCH 01/15] dm: support ioctls on mapped devices

[Alasdair G Kergon]

On Thu, Jun 22, 2006 at 01:29:57AM -0700, Andrew Morton wrote:
> OK.  I do think dm needs to remember /dev/sda's file* to get this right
> though.  That's where the ->ioctl methods are.

> Oh dear.  raw_open() doesn't have a file* for the device.
 
Similar with device-mapper: in normal usage dm only sees major:minor.

Yes, the filp dm passes along is incorrect:

- return blkdev_driver_ioctl(bdev->bd_inode, filp, bdev->bd_disk, cmd, arg);
+ return blkdev_driver_ioctl(bdev->bd_inode, NULL, bdev->bd_disk, cmd, arg);

But should unlocked_ioctl become ?

- long (*unlocked_ioctl) (struct file *, unsigned, unsigned long);
+ long (*unlocked_ioctl) (struct inode *, struct file *, unsigned, unsigned long);

so it can be used for block devices?

See also block/scsi_ioctl.c:201 verify_command()  [scsi_cmd_ioctl]
         * file can be NULL from ioctl_by_bdev()...

Or should we be working towards eliminating interfaces that use device numbers?

Alasdair
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