On Wed, 2007-06-20 at 17:31 +0900, Masami Hiramatsu wrote:
[...]
> P.S.
> I attached my patch (relay-file-read-overwrite-mode-fix.patch)
> which fixed the problem pointed in previous mail.
>
> Signed-off-by: Masami Hiramatsu <[email protected]>
>
Hi,
Thanks for sending the test case. I wrote my own program that tests for
the same thing, and it also works fine. To make sure it doesn't break
no-overwrite mode, I also ran several tests with blktrace and that looks
good too.
Thanks very much for analyzing the problem and providing the patch!
Just to summarize - the problem this fixes is that in overwrite mode,
the current read code doesn't pick up all the data it could if the whole
buffer is filled - it will leave behind sub-buffers at the beginning.
With this patch, the data in those sub-buffers is read as well.
Acked-by: Tom Zanussi <[email protected]>
> ---
> kernel/relay.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> Index: linux-2.6.22-rc4-mm2/kernel/relay.c
> ===================================================================
> --- linux-2.6.22-rc4-mm2.orig/kernel/relay.c 2007-06-13 20:22:02.000000000 +0900
> +++ linux-2.6.22-rc4-mm2/kernel/relay.c 2007-06-20 10:53:06.000000000 +0900
> @@ -812,7 +812,10 @@
> }
>
> buf->bytes_consumed += bytes_consumed;
> - read_subbuf = read_pos / buf->chan->subbuf_size;
> + if (!read_pos)
> + read_subbuf = buf->subbufs_consumed % n_subbufs;
> + else
> + read_subbuf = read_pos / buf->chan->subbuf_size;
> if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
> if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
> (buf->offset == subbuf_size))
> @@ -841,8 +844,9 @@
> }
>
> if (unlikely(produced - consumed >= n_subbufs)) {
> - consumed = (produced / n_subbufs) * n_subbufs;
> + consumed = produced - n_subbufs + 1;
> buf->subbufs_consumed = consumed;
> + buf->bytes_consumed = 0;
> }
>
> produced = (produced % n_subbufs) * subbuf_size + buf->offset;
>
>
>
>
-
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