Re: BLKSECTGET userland API breakage (2.4 and 2.6 incompatible)

From: David S. Miller
Date: Thu Oct 13 2005 - 23:08:44 EST

From: Alexander Viro <aviro@xxxxxxxxxx>
Date: Thu, 13 Oct 2005 19:49:34 -0400

> all 2.4: BLKSECTGET takes long * and is supported by several block drivers
> bio-14-pre9: Takes BLKSECTGET to drivers/block/blkpg.c, defining it for all
> block drivers *AND* making it take unsigned short *
> 2.5.1-pre2: bio merge
> all 2.[56] kernels since then: BLKSECTGET takes unsigned short *
> 32bit compat: unchanged since 2.4 and thus broken on 2.[56]
> applications: we have seen ones using 2.6 ABI and getting buggered in
> 32bit compat. Most likely there are some using 2.4 ABI...
> IMO the least painful variant is to switch 2.6 compat code to match
> 2.6 native (i.e. use COMPATIBLE_IOCTL()), leave 2.4 as-is and live
> with the fact of userland ABI change between 2.4 and 2.6...

Well, what's the userland state and why in the world did this
happen in the first place?

I guess you're right that keeping the 2.6.x ABI for this ioctl
and fixing up the compat code is probably the least painful
thing to do.
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