centos man page for page_cache_next_hole

PAGE_CACHE_NEXT_HOLE(9) 				    Memory Management in Linux					   PAGE_CACHE_NEXT_HOLE(9)

NAME
       page_cache_next_hole - find the next hole (not-present entry)

SYNOPSIS
       pgoff_t page_cache_next_hole(struct address_space * mapping, pgoff_t index, unsigned long max_scan);

ARGUMENTS
       mapping
	   mapping

       index
	   index

       max_scan
	   maximum range to search

DESCRIPTION
       Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest indexed hole.

RETURNS
       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.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						   PAGE_CACHE_NEXT_HOLE(9)