lkml.org 
[lkml]   [2008]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] block: fix residual byte count handling
FUJITA Tomonori wrote:
> sum(sg) == rq->data_len is already broken; sg sends such requests
> (though it would be nice if it doesn't).
>

Actually, I think I was half wrong on that when you asked about
scsi_debug. The scatterlist that sg.c uses is never seen by the block
layer or scsi layer. It is just used as a container to hold segments.
sg.c and st.c use their scatterlist to manage their preallocated
pages/segments. When they pass it to scsi_execute_async, that function
will create a request struct and add bios for the pages.

In 2.6.24 and below, sg.c will send a scatterlist length that does not
match the IO length, and scsi_execute_async will goof up and send a
rq->data_len that does not match the sum of the bios. That is what I was
trying to fix in 2.6.24, but the patch got messed up. In 2.6.25-rc2 and
above that is fixed and scsi_execute_async will catch sg.c doing this
and set rq->data_len and the bio lengths correctly.

So hopefully that helps any fixes you might have planned.


\
 
 \ /
  Last update: 2008-03-02 19:55    [W:0.818 / U:1.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site