On Thu, Aug 09, 2012 at 09:41:05AM -0500, Mark Tinguely wrote:
.....
> >+
> >+ /*
> >+ * At lease we found one page. If this is the first time we
> >+ * step into the loop, and if the first page index offset is
> >+ * greater than the given search offset, a hole was found.
> >+ */
> >+ if (type == HOLE_OFF&& lastoff == startoff&&
> >+ lastoff< page_offset(pvec.pages[0])) {
> >+ found = true;
> >+ break;
> >+ }
>
> I played with the code and appreciate the trickiness of the startoff.
> I this can be refined a bit more. see below.
>
> >+
> >+ for (i = 0; i< nr_pages; i++) {
> >+ struct page *page = pvec.pages[i];
> >+ loff_t b_offset;
> >+
> >+ /*
> >+ * Page index is out of range, searching done.
> >+ * If the current offset is not reaches the end
> >+ * of the specified search range, there should
> >+ * be a hole between them.
> >+ */
> >+ if (page->index> end) {
> >+ if (type == HOLE_OFF&& lastoff< endoff) {
> >+ *offset = lastoff;
> >+ found = true;
> >+ }
> >+ goto out;
> >+ }
>
> Before we take the lock, we can check to see if the page starts
> later than expected (a hole). The pre-loop start check can be
> removed and something like the follow added:
Really, we don't need to be that tricky or smart. This is not a
performance critical operation, so we don't need to optimise away
page locks, especially when the risk of getting it wrong is
compromising data integrity...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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