[dm-devel] [RFC] DM_TARGET_CTL: ioctl interface

[Alasdair G Kergon]

On Tue, May 25, 2004 at 01:55:23PM +0100, Alasdair G Kergon wrote:
> On Mon, May 24, 2004 at 06:00:19PM -0700, Mike Christie wrote:
> > Is there any way
> > I could pass in such a thing when my target is created, so that way dm 
> > multipath
> > would not have any type of command format functions/modules or definitions
> > (it could just be passed in and built like the sg io code).
> We've been talking about a new dm ioctl for passing arbitrary commands 
> to a target, which I think would cover this.  

dm-ioctl.h:
  #define DM_TARGET_CTL	 _IOWR(DM_IOCTL, DM_TARGET_CTL_CMD, struct dm_ioctl)

  struct dm_target_ctl {
	uint64_t sector;	/* Device sector */
	/* Might add size of command string if it simplifies processing */

	char command[0];
  };

Is there any legitimate need to supply a list of dm_target_ctl structs
instead of just one-at-once?

Is there any need to allow a string of data to be returned in addition
to the error code?  [i.e. Are status/table commands sufficient? ]

Alasdair
-- 
agk at redhat.com