On Thu, Oct 16, 2014 at 03:51:12PM -0400, Matthew Wilcox wrote:
> On Thu, Oct 16, 2014 at 11:50:27AM +0200, Mathieu Desnoyers wrote:
> > > + if (rw == WRITE) {
> > > + if (!buffer_mapped(bh)) {
> > > + retval = -EIO;
> > > + /* FIXME: fall back to buffered I/O */
> >
> > Fallback on buffered I/O would void guarantee about having data stored
> > into persistent memory after write returns. Not sure we actually want
> > that.
>
> Yeah, I think that comment is just stale. I can't see a way in which
> buffered I/O would succeed after DAX I/O falis.
On further consideration, I think the whole thing is just foolish.
I don't see how get_block(create == 1) can return success *and* a buffer
that is !mapped.
So I did this nice simplification:
- if (rw == WRITE) {
- if (!buffer_mapped(bh)) {
- retval = -EIO;
- /* FIXME: fall back to buffered I/O */
- break;
- }
- hole = false;
- } else {
- hole = !buffer_written(bh);
- }
+ hole = (rw != WRITE) && !buffer_written(bh);
(compile-tested only; I'm going to run all the changes through xfstests
next week when I'm back home before sending out a v12).
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