truncate_setsize — update inode and pagecache for a new file size
|struct inode * inode,|
truncate_setsize updates i_size and performs pagecache truncation (if
newsize. It will be typically be called from the filesystem's
setattr function when ATTR_SIZE is passed in.
Must be called with a lock serializing truncates and writes (generally i_mutex but e.g. xfs uses a different lock) and before all filesystem specific block truncation has been performed.