page_cache_next_hole (9) - Linux Man Pages
page_cache_next_hole: find the next hole (not-present entry)
page_cache_next_hole - find the next hole (not-present entry)
pgoff_t page_cache_next_hole(struct address_space
*mapping, pgoff_t index, unsigned long max_scan);
- maximum range to search
the index of the hole if found, otherwise returns an index outside of the set specified (in which case 'return - index >= max_scan' will be true). In rare cases of index wrap-around, 0 will be returned.
page_cache_next_hole may be called under rcu_read_lock. However, like radix_tree_gang_lookup, this will not atomically search a snapshot of the tree at a single point in time. For example, if a hole is created at index 5, then subsequently a hole is created at index 10, page_cache_next_hole covering both indexes may return 10 if called under rcu_read_lock.