On Mon, Aug 13, 2012 at 09:07:58PM +0800, Jeff Liu wrote:
> helper routine to lookup data or hole offset from page cache for unwritten extents.
>
> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
....
> + unsigned int i;
> +
> + want = min_t(pgoff_t, end - index, (pgoff_t)PAGEVEC_SIZE);
No need for the cast to (pgoff_t) here. That's what the min_t()
macro does for you.
> + 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;
> + }
> +
> + lock_page(page);
> + /*
> + * Page truncated or invalidated(page->mapping == NULL).
> + * We can freely skip it and proceed to check the next
> + * page.
> + */
> + if (unlikely(page->mapping != inode->i_mapping)) {
> + unlock_page(page);
> + continue;
> + }
Still need to check page->index again after locking the page. As
this isn't performance critical, I don't think you need the check
before the page is locked, anyway....
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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