Messages in this thread | | | Date | Thu, 22 Jun 2006 10:15:30 +0200 | From | Milan Broz <> | Subject | Re: [PATCH 01/15] dm: support ioctls on mapped devices |
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Andrew Morton wrote: > On Wed, 21 Jun 2006 20:31:21 +0100 > Alasdair G Kergon <agk@redhat.com> wrote: > >> From: Milan Broz <mbroz@redhat.com> >> >> Extend the core device-mapper infrastructure to accept arbitrary ioctls >> on a mapped device provided that it has exactly one target and it is >> capable of supporting ioctls. > > I don't understand that. We're taking an ioctl against a dm device and > we're passing it through to an underlying device? Or something else?
Solving this situation: logical volume (say /dev/mapper/lv1) mapped in dm to single device (/dev/sda):
If there is need to send ioctl you must know that /dev/mapper/lv1 is mapped to /dev/sda (and use /dev/sda for ioctl). This is dm work - so send ioctl to /dev/mapper/lv1 directly and let dm decide what to do.
This is supported only for single mapping. If there are more than one target it will return -ENOTTY.
>> [We can't use unlocked_ioctl because we need 'inode': 'file' might be NULL. >> Is it worth changing this?] > > It _should_ be possible to use unlocked_ioctl() - unlocked_ioctl() would be > pretty useless if someone was passing it a NULL file*. More details?
yes, (I prefer change block code to not pass NULL and use unlocked_ioctl, - Alasdair ?)
see
drivers/char/raw.c: 126: return blkdev_ioctl(bdev->bd_inode, *NULL*, command, arg);
and block/ioctl.c: [file = NULL here] 206: if (disk->fops->unlocked_ioctl) 207: return disk->fops->unlocked_ioctl(*file*, cmd, arg);
-- Milan Broz mbroz@redhat.com
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