Hey, On Tue, Dec 23, 2008 at 12:20 AM, Alasdair G Kergon <agk@xxxxxxxxxx> wrote: > On Mon, Dec 22, 2008 at 10:52:08PM +0530, Sandeep K Sinha wrote: >> After looking at the complete implementation of device mappers, I >> figured out that we can have more than one target for a mapped device >> then why do we have a check for the number of target to be equal to >> one , in dm_blk_ioctl ( ) in drivers/md/dm.c >> >> http://lxr.linux.no/linux+v2.6.27.10/drivers/md/dm.c#L337 > > Because whether or not it makes sense to send any specific ioctl to more > than one target in parallel depends on what that ioctl does. When we > added that code we said that we could add hard-coding for specific > ioctls if the need arose, but so far it hasn't. > No, the philosophy should be that we send the ioctl's to the mapped device and not to the targets underlying that mapped-device. And doing so, I should be able to access the complete map that belongs to that mapped device. If I implement an ioctl of my own and try to serve it, the problem would be that it would never allow me to serve it if has more than one target. > Alasdair > -- > agk@xxxxxxxxxx > -- Regards, Sandeep. "To learn is to change. Education is a process that changes the learner." -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
