Re: [regression?] distcc says: (dcc_pump_sendfile) ERROR: sendfilereturned 0? can't cope (bisected)

From: Tom Zanussi
Date: Thu May 08 2008 - 03:21:41 EST



On Wed, 2008-05-07 at 23:16 +0200, Jens Axboe wrote:
> On Wed, May 07 2008, Dan Williams wrote:
> > Hi Tom, Jens,
> >
> > My build system started reporting these error messages recently.
> > Reverting commit c3270e577c18b3d0e984c3371493205a4807db9d on top of
> > 2.6.26-rc1 gets things working for me again.
>
> Irk, that patch did scare me a bit (hence I asked Tom to double check as
> wel :-). I'll take a look in the morning, all test boxes are off at this
> point in time.
>

I did, and it still looks ok to me, but obviously it's not, so I'll have
to do some more digging.

The only thing I can think of right now that might be a possible cause
would be in splice_direct_to_actor(), if we had an incomplete transfer,
the sd->pos returned and assigned would have the value set by the failed
actor(). Maybe something like the following would take care of that
case, but I haven't had a chance to test it yet - will do that tomorrow
night...

Tom

diff --git a/fs/splice.c b/fs/splice.c
index 633f58e..1bb3f34 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -986,7 +986,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,

while (len) {
size_t read_len;
- loff_t pos = sd->pos;
+ loff_t pos = sd->pos, prev_pos = pos;

ret = do_splice_to(in, &pos, pipe, len, flags);
if (unlikely(ret <= 0))
@@ -1001,8 +1001,10 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
* could get stuck data in the internal pipe:
*/
ret = actor(pipe, sd);
- if (unlikely(ret <= 0))
+ if (unlikely(ret <= 0)) {
+ sd->pos = prev_pos;
goto out_release;
+ }

bytes += ret;
len -= ret;


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