[dm-devel] device-mapper ioctl interface version 3

Alasdair G Kergon agk at uk.sistina.com
Wed May 28 14:50:02 UTC 2003


On Wed, May 28, 2003 at 02:18:29PM -0500, Kevin Corry wrote:
> I was just wondering if you have a timeframe in mind for when the new ioctl 
> interface will be officially released 

As soon as it has satisfied all our internal tests, which I genuinely hope 
is only a few days away now...

We have still been finding some small things to fix/change before release:
the latest is the addition of the long-awaited command to list the
names of devices, which we just got working a couple of hours ago.


Current interface definition (which could still need tweaking):

  #define DM_LIST_DEVICES  _IOWR(DM_IOCTL, DM_LIST_DEVICES_CMD, struct dm_ioctl)

  struct dm_name_list {
          uint64_t dev;
          uint32_t next;          /* offset to the next record from
                                     the _start_ of this */
          char name[0];
  };

Data comes in repeating struct dm_name_lists the same way as deps, table etc.
It returns names not uuids.  [Enhancement is likely to provide the choice.]

If the whole data won't fit, it returns no data & sets DM_BUFFER_FULL_FLAG.
If there are no mapped devices defined, the first structure's dev is 0.
The last item has next == 0.
(The info fields don't get filled.)

# dmsetup ls
vg1-lvol1	(254, 0)
vg1-lvol2	(254, 1)

# dmsetup ls
No devices found.

Alasdair
-- 
agk at uk.sistina.com




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