PAGECACHE_ISIZE_EXTE(9)             Memory Management in Linux            PAGECACHE_ISIZE_EXTE(9)



NAME
       pagecache_isize_extended - update pagecache after extension of i_size

SYNOPSIS
       void pagecache_isize_extended(struct inode * inode, loff_t from, loff_t to);

ARGUMENTS
       inode
           inode for which i_size was extended

       from
           original inode size

       to
           new inode size

DESCRIPTION
       Handle extension of inode size either caused by extending truncate or by write starting
       after current i_size. We mark the page straddling current i_size RO so that page_mkwrite
       is called on the nearest write access to the page. This way filesystem can be sure that
       page_mkwrite is called on the page before user writes to the page via mmap after the
       i_size has been changed.

       The function must be called after i_size is updated so that page fault coming after we
       unlock the page will already see the new i_size. The function must be called while we
       still hold i_mutex - this not only makes sure i_size is stable but also that userspace
       cannot observe new i_size value before we are prepared to store mmap writes at new inode
       size.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                   PAGECACHE_ISIZE_EXTE(9)