Re: [PATCH] splice: fix wrong __splice_from_pipe() usage

From: Jens Axboe
Date: Mon Jul 16 2007 - 08:38:15 EST


On Mon, Jul 16 2007, OGAWA Hirofumi wrote:
> Jens Axboe <jens.axboe@xxxxxxxxxx> writes:
>
> >> nfsd_vfs_read() path.
> >>
> >> nfsd_vfs_read()
> >> splice_direct_to_actor()
> >> while(len) {
> >> do_splice_to() [update sd->pos]
> >> -> generic_file_splice_read() [read from sd->pos]
> >> nfsd_direct_splice_actor()
> >> -> __splice_from_pipe() [update sd->pos]
> >> }
> >>
> >> do_splice_to() updates sd->pos for read, and pass updated sd to
> >> __splice_from_pipe(), and __splice_from_pipe() updates sd->pos for
> >> write. So, next do_splice_to() read from wrong position.
> >
> > Ah, I see. Copying the structure over would work, but it seems like a
> > big work-around for something that is essentially bad behaviour in the
> > splice core for direct splicing.
> >
> > Can you check if this works for you?
>
> Simple test was done. The patch works for me.

Great, thanks a lot for retesting. I'll get the patch upstream asap.

--
Jens Axboe

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