Re: [RFC][PATCH] nbd driver for 2.5+: fix locking issues with ioctl UI

[Lou Langholtz <ldl@aros.net>]

Christoph Hellwig wrote:

>On Wed, Jun 25, 2003 at 11:38:43AM -0600, Lou Langholtz wrote:
>  
>
>>Yes. To be fair though, the binary (and the driver too) was broken on 
>>linux 2.5 kernels long before I even proposed any changes to the nbd 
>>driver. I'm trying to fix that.
>>    
>>
>Hey, I didn't say changing the interface is wrong.  But if possible
>do it in a way that the new userspace can still support the old kernel
>driver.
>
Agreed! Will do, but how???

>>NBD_SET_SOCK. That'd tell nbd-tool that the nbd driver thinks something 
>>about the ioctl was invalid but not what. I wanted to return EDEPRECATED 
>>instead but I haven't found that errno yet. I could overload an errno 
>>but that seems ugly too. Or the driver could have a NBD_GET_VERSION 
>>ioctl. Is there precedence for that? I haven't come accross it yet.
>>    
>>
>
>That's one choice.  At least md and device mapper do that.
>  
>
Cool! I'll take a look at these. Is this the prefered way then? There's 
probably a lot of need for this generally speaking. Thought about using 
/proc for this too. And then sysfs is gaining favor so maybe in there? 
Any preference?