+static noinline_for_stack int writepage_delalloc(struct inode *inode,
+ struct page *page, struct writeback_control *wbc,
+ struct extent_page_data *epd,
+ u64 delalloc_start,
+ unsigned long *nr_written)
+{
+ struct extent_io_tree *tree = epd->tree;
+ u64 page_end = delalloc_start + PAGE_CACHE_SIZE - 1;
+ u64 nr_delalloc;
+ u64 delalloc_to_write = 0;
+ u64 delalloc_end = 0;
+ int ret;
+ int page_started = 0;
+
+ if (epd->extent_locked || !tree->ops || !tree->ops->fill_delalloc)
+ return 0;
+
+ while (delalloc_end < page_end) {
+ nr_delalloc = find_lock_delalloc_range(inode, tree,
+ page,
+ &delalloc_start,
+ &delalloc_end,
+ 128 * 1024 * 1024);
+ if (nr_delalloc == 0) {
+ delalloc_start = delalloc_end + 1;
+ continue;
+ }
+ ret = tree->ops->fill_delalloc(inode, page,
+ delalloc_start,
+ delalloc_end,
+ &page_started,
+ nr_written);
+ /* File system has been set read-only */
+ if (ret) {
+ SetPageError(page);
+ /* fill_delalloc should be return < 0 for error
+ * but just in case, we use > 0 here meaning the
+ * IO is started, so we don't want to return > 0
+ * unless things are going well.
+ */
+ ret = ret < 0 ? ret : -EIO;
+ goto done;
+ }
+ /*
+ * delalloc_end is already one less than the total
+ * length, so we don't subtract one from
+ * PAGE_CACHE_SIZE
+ */
+ delalloc_to_write += (delalloc_end - delalloc_start +
+ PAGE_CACHE_SIZE) >>
+ PAGE_CACHE_SHIFT;
+ delalloc_start = delalloc_end + 1;
+ }
+ if (wbc->nr_to_write < delalloc_to_write) {
+ int thresh = 8192;
+
+ if (delalloc_to_write < thresh * 2)
+ thresh = delalloc_to_write;
+ wbc->nr_to_write = min_t(u64, delalloc_to_write,
+ thresh);
+ }
+
+ /* did the fill delalloc function already unlock and start
+ * the IO?
+ */
+ if (page_started) {
+ /*
+ * we've unlocked the page, so we can't update
+ * the mapping's writeback index, just update
+ * nr_to_write.
+ */
+ wbc->nr_to_write -= *nr_written;
+ return 1;
+ }
+
+ ret = 0;
+
+done:
+ return ret;
+}
+
+/*
+ * helper for __extent_writepage. This calls the writepage start hooks,
+ * and does the loop to map the page into extents and bios.
+ *
+ * We return 1 if the IO is started and the page is unlocked,
+ * 0 if all went well (page still locked)
+ * < 0 if there were errors (page still locked)
+ */
+static noinline_for_stack int __extent_writepage_io(struct inode *inode,
+ struct page *page,
+ struct writeback_control *wbc,
+ struct extent_page_data *epd,
+ loff_t i_size,
+ unsigned long nr_written,
+ int write_flags, int *nr_ret)