centos man page for page_cache_prev_hole

PAGE_CACHE_PREV_HOLE(9) 				    Memory Management in Linux					   PAGE_CACHE_PREV_HOLE(9)

NAME
       page_cache_prev_hole - find the prev hole (not-present entry)

SYNOPSIS
       pgoff_t page_cache_prev_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 backwards in the range [max(index-max_scan+1, 0), index] for the first hole.

RETURNS
       the index of the hole if found, otherwise returns an index outside of the set specified (in which case 'index - return >= max_scan' will be
       true). In rare cases of wrap-around, ULONG_MAX will be returned.

       page_cache_prev_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 10, then subsequently a hole is created at index 5,
       page_cache_prev_hole covering both indexes may return 5 if called under rcu_read_lock.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						   PAGE_CACHE_PREV_HOLE(9)