suse man page for truncate_inode_pages_range

TRUNCATE_INODE_PAGES(9) 				    Memory Management in Linux					   TRUNCATE_INODE_PAGES(9)

NAME
       truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets

SYNOPSIS
       void truncate_inode_pages_range(struct address_space * mapping, loff_t lstart, loff_t lend);

ARGUMENTS
       mapping
	   mapping to truncate

       lstart
	   offset from which to truncate

       lend
	   offset to which to truncate

DESCRIPTION
       Truncate the page cache, removing the pages that are between specified offsets (and zeroing out partial page (if lstart is not page
       aligned)).

       Truncate takes two passes - the first pass is nonblocking. It will not block on page locks and it will not block on writeback. The second
       pass will wait. This is to prevent as much IO as possible in the affected region. The first pass will remove most pages, so the search cost
       of the second pass is low.

       When looking at page->index outside the page lock we need to be careful to copy it into a local to avoid races (it could change at any
       time).

       We pass down the cache-hot hint to the page freeing code. Even if the mapping is large, it is probably the case that the final pages are
       the most recently touched, and freeing happens in ascending file offset order.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						   TRUNCATE_INODE_PAGES(9)