> > The 'confirm' operation was only used for splicing from page cache, to
> > wait for read on a page to finish. But generic_file_splice_read()
> > already blocks on readahead reads, so it seems logical to block on the
> > rare and slow single page reads too.
> >
> > So wait for readpage to finish inside __generic_file_splice_read() and
> > remove the 'confirm' method.
> >
> > This also fixes short return counts when the filesystem (e.g. fuse)
> > invalidates the page between insertation and removal.
>
> One of the basic goals of splice is to allow the pipe buffer to only be
> consisten when a consumer asks for it, otherwise the filling will always
> be sync. There should be no blocking on reads in the splice-in path,
> only on consumption for splice-out.
What you are ignoring (and I've mentioned in the changelog) is that it
is *already* sync. Look at the code: this starts I/O:
page_cache_sync_readahead(mapping, &in->f_ra, in,
index, req_pages - spd.nr_pages);
And this waits for it to finish:
if (!PageUptodate(page)) {
...
lock_page(page);
The only way it will be async, is if there's no readahead. But do we
want to optmize that case?
Miklos
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
