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

[Kevin Corry]

On Wednesday 28 May 2003 14:50, Alasdair G Kergon wrote:
> 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.

Cool! I didn't realize you were going to add this command. That should help 
out quite a bit in several error-detection scenarios.

> 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.]

I guess it would just take one extra flag defintion at the bottom of 
dm-ioctl.h to allow the user to choose between names and uuids.

> 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.)

Looks good to me. :)  I suppose there's not much point in returning only part 
of the list if the data won't fit in the buffer. Better to just reallocate 
the buffer and retry the command.

-- 
Kevin Corry
kevcorry at us.ibm.com
http://evms.sourceforge.net/