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 <redacted>

....

+		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@fromorbit.com

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