1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>mpage_writepages</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Linux Filesystems API"><link rel="up" href="other_functions.html" title="Other Functions"><link rel="prev" href="API-mpage-readpages.html" title="mpage_readpages"><link rel="next" href="API-generic-permission.html" title="generic_permission"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">mpage_writepages</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-mpage-readpages.html">Prev</a>&#160;</td><th width="60%" align="center">Other Functions</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-generic-permission.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-mpage-writepages"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>mpage_writepages &#8212; 
2     walk the list of dirty pages of the given address space &amp; <code class="function">writepage</code> all of them
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">mpage_writepages </b>(</code></td><td>struct address_space * <var class="pdparam">mapping</var>, </td></tr><tr><td>&#160;</td><td>struct writeback_control * <var class="pdparam">wbc</var>, </td></tr><tr><td>&#160;</td><td>get_block_t <var class="pdparam">get_block</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1102133188"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>mapping</code></em></span></dt><dd><p>
4     address space structure to write
5    </p></dd><dt><span class="term"><em class="parameter"><code>wbc</code></em></span></dt><dd><p>
6     subtract the number of written pages from *<em class="parameter"><code>wbc</code></em>-&gt;nr_to_write
7    </p></dd><dt><span class="term"><em class="parameter"><code>get_block</code></em></span></dt><dd><p>
8     the filesystem's block mapper function.
9     If this is NULL then use a_ops-&gt;writepage.  Otherwise, go
10     direct-to-BIO.
11    </p></dd></dl></div></div><div class="refsect1"><a name="idp1102137260"></a><h2>Description</h2><p>
12   This is a library function, which implements the <code class="function">writepages</code>
13   address_space_operation.
14   </p><p>
15
16   If a page is already under I/O, <code class="function">generic_writepages</code> skips it, even
17   if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
18   but it is INCORRECT for data-integrity system calls such as <code class="function">fsync</code>.  <code class="function">fsync</code>
19   and <code class="function">msync</code> need to guarantee that all the data which was dirty at the time
20   the call was made get new I/O started against them.  If wbc-&gt;sync_mode is
21   WB_SYNC_ALL then we were called for data integrity and we must wait for
22   existing IO to complete.
23</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-mpage-readpages.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="other_functions.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-generic-permission.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">mpage_readpages</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">generic_permission</span></td></tr></table></div></body></html>
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