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Re: [PATCH] relay-file-read-start-pos-fix.patch
- From: Tom Zanussi <zanussi at us dot ibm dot com>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: David Wilder <dwilder at us dot ibm dot com>, linux-kernel at vger dot kernel dot org, systemtap at sources dot redhat dot com, Yumiko Sugita <yumiko dot sugita dot yf at hitachi dot com>, Satoshi Oshima <soshima at redhat dot com>, Hideo Aoki <haoki at redhat dot com>
- Date: Tue, 19 Jun 2007 00:35:00 -0500
- Subject: Re: [PATCH] relay-file-read-start-pos-fix.patch
- References: <4676109F.8020202@us.ibm.com> <467750E9.4090808@hitachi.com>
On Tue, 2007-06-19 at 12:43 +0900, Masami Hiramatsu wrote:
> Hi David and Tom,
>
> David Wilder wrote:
> > This patch fixes a bug in the relay read interface causing the number
> > of consumed bytes to be set incorrectly.
>
> Thank you. Your patch fixes one of my concerns.
> However there is another bug I found.
> When I use relayfs with "overwrite" mode, read() still set incorrect
> number of consumed bytes.
> I tried to fix that. Please review it.
Hi,
Could you send more info on how to reproduce the problem you're seeing?
And does this patch fix it?
Thanks,
Tom
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>
> ---
> 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 2007-06-18 23:00:54.000000000 +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;
> + 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;
>
>
>
>