centos man page for truncate_pagecache

TRUNCATE_PAGECACHE(9)					    Memory Management in Linux					     TRUNCATE_PAGECACHE(9)

NAME
       truncate_pagecache - unmap and remove pagecache that has been truncated

SYNOPSIS
       void truncate_pagecache(struct inode * inode, loff_t oldsize, loff_t newsize);

ARGUMENTS
       inode
	   inode

       oldsize
	   old file size

       newsize
	   new file size

DESCRIPTION
       inode's new i_size must already be written before truncate_pagecache is called.

       This function should typically be called before the filesystem releases resources associated with the freed range (eg. deallocates blocks).
       This way, pagecache will always stay logically coherent with on-disk format, and the filesystem would not have to deal with situations such
       as writepage being called for a page that has already had its underlying blocks deallocated.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						     TRUNCATE_PAGECACHE(9)