+ if (sync) {
+ filemap_write_and_wait(inode->i_mapping);
+ /*
+ * We have to do this because compression doesn't
+ * actually set PG_writeback until it submits the pages
+ * for IO, which happens in an async thread, so we could
+ * race and not actually wait for any writeback pages
+ * because they've not been submitted yet. Technically
+ * this could still be the case for the ordered stuff
+ * since the async thread may not have started to do its
+ * work yet. If this becomes the case then we need to
+ * figure out a way to make sure that in writepage we
+ * wait for any async pages to be submitted before
+ * returning so that fdatawait does what its supposed to
+ * do.
+ */
+ btrfs_wait_ordered_range(inode, 0, (u64)-1);
+ } else {
+ filemap_flush(inode->i_mapping);
+ }