Block driver design issue

Block driver design issue

[LA Walsh]

I have a block driver I inherited that I working on that has a problem and
was wondering for cleaner solutions.

The driver can accept written characters from either userspace programs or from
the kernel.  From userspace it uses sys_write.  That in turn calls block_write.
There's almost 100 lines of duplicated code in a copy of the block_write
code in the driver "block_writek" as well as duplicate code in audit_write vs. audit_writek.
The only difference being down in block_write at the "copy_from_user(p,buf,chars); "
which becomes a "memcpy(p,buf,chars)" in the "block_writek" version.  

I find this duplication of code to be inefficient.  Is there a way to dummy up the
the 'buf' address so that the "copy_from_user" will copy the buffer from kernel space?
My assumption is that it wouldn't "just work" (which may also be an invalid assumption).

Suggestions?  Abuse?

Thanks!
-linda

-- 
L A Walsh                    | Trust Technology, Core Linux, SGI
law@sgi.com                      | Voice: (650) 933-5338
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Re: Block driver design issue

[Manfred Spraul]

LA Walsh wrote:
> 
> 
> I find this duplication of code to be inefficient.  Is there a way to dummy up the
> the 'buf' address so that the "copy_from_user" will copy the buffer from kernel space?
> My assumption is that it wouldn't "just work" (which may also be an invalid assumption).
> 
> Suggestions?  Abuse?
>

set_fs(KERNEL_DS)?

After that call copy_from_user() will accept kernel space addresses.

--
	Manfred
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