'\" t
.\"     Title: pagecache_isize_extended
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Memory Management in Linux
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "PAGECACHE_ISIZE_EXTE" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Memory Management in Linux"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
pagecache_isize_extended \- update pagecache after extension of i_size
.SH "SYNOPSIS"
.HP \w'void\ pagecache_isize_extended('u
.BI "void pagecache_isize_extended(struct\ inode\ *\ " "inode" ", loff_t\ " "from" ", loff_t\ " "to" ");"
.SH "ARGUMENTS"
.PP
\fIinode\fR
.RS 4
inode for which i_size was extended
.RE
.PP
\fIfrom\fR
.RS 4
original inode size
.RE
.PP
\fIto\fR
.RS 4
new inode size
.RE
.SH "DESCRIPTION"
.PP
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
\fBpage_mkwrite\fR
is called on the nearest write access to the page\&. This way filesystem can be sure that
\fBpage_mkwrite\fR
is called on the page before user writes to the page via mmap after the i_size has been changed\&.
.PP
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\&.
.SH "COPYRIGHT"
.br