lkml.org 
[lkml]   [2007]   [Feb]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Block layer: separate out queue-oriented ioctls
On Mon, 19 Feb 2007, Douglas Gilbert wrote:

> Alan,
> The SG_GET_RESERVED_SIZE ioctl is also defined in
> the block layer, see block/scsi_ioctl.c .

Ah, I didn't know that. (Or more likely, I used to know and have since
forgotten.) Thanks for pointing it out.

> I suspect it is just a kludge to fool cdrecord that it
> is talking to a sg device. [One of many kludges in the
> block SG_IO ioctl implementation to that end.]
> So perhaps the block layer versions of SG_SET_RESERVED_SIZE
> and SG_GET_RESERVED_SIZE need to be similarly capped.

Yes. In fact one of them already is, but the other should be too.

> Actually I think that I would default SG_GET_RESERVED_SIZE to
> request_queue->max_sectors * 512 in the block layer
> implementation (as there is no "reserve buffer" associated
> with a block device).

Okay.

Come to think of it, the reserved_size value used when a new sg device is
created should also be capped at max_sectors * 512. Agreed? I can't see
any reason for ever having a larger buffer -- it would be impossible to
make use of the extra space.

Alan Stern

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-02-20 04:51    [W:0.051 / U:0.704 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site