Hello Matthew Wilcox,
The patch 87345c6b1aa8: "page cache: Convert filemap_range_has_page
to XArray" from Jan 16, 2018, leads to the following static checker
warning:
mm/filemap.c:469 filemap_range_has_page()
warn: continue to end of do { ... } while(0); loop
mm/filemap.c
455 bool filemap_range_has_page(struct address_space *mapping,
456 loff_t start_byte, loff_t end_byte)
457 {
458 struct page *page;
459 XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
460 pgoff_t max = end_byte >> PAGE_SHIFT;
461
462 if (end_byte < start_byte)
463 return false;
464
465 rcu_read_lock();
466 do {
467 page = xas_find(&xas, max);
468 if (xas_retry(&xas, page))
469 continue;
^^^^^^^^
470 /* Shadow entries don't count */
471 if (xa_is_value(page))
472 continue;
^^^^^^^^
This is the same as a break because it's a while(0) loop.
473 /*
474 * We don't need to try to pin this page; we're about to
475 * release the RCU lock anyway. It is enough to know that
476 * there was a page here recently.
477 */
478 } while (0);
479 rcu_read_unlock();
480
481 return page != NULL;
482 }
regards,
dan carpenter
