1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>generic_permission</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-writepages.html" title="mpage_writepages"><link rel="next" href="API---inode-permission.html" title="__inode_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">generic_permission</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-mpage-writepages.html">Prev</a>&#160;</td><th width="60%" align="center">Other Functions</th><td width="20%" align="right">&#160;<a accesskey="n" href="API---inode-permission.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-generic-permission"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>generic_permission &#8212; 
2  check for access rights on a Posix-like filesystem
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">generic_permission </b>(</code></td><td>struct inode * <var class="pdparam">inode</var>, </td></tr><tr><td>&#160;</td><td>int <var class="pdparam">mask</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1102144988"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>inode</code></em></span></dt><dd><p>
4     inode to check access rights for
5    </p></dd><dt><span class="term"><em class="parameter"><code>mask</code></em></span></dt><dd><p>
6     right to check for (<code class="constant">MAY_READ</code>, <code class="constant">MAY_WRITE</code>, <code class="constant">MAY_EXEC</code>, ...)
7    </p></dd></dl></div></div><div class="refsect1"><a name="idp1102148092"></a><h2>Description</h2><p>
8   Used to check for read/write/execute permissions on a file.
9   We use <span class="quote">&#8220;<span class="quote">fsuid</span>&#8221;</span> for this, letting us set arbitrary permissions
10   for filesystem access without changing the <span class="quote">&#8220;<span class="quote">normal</span>&#8221;</span> uids which
11   are used for other things.
12   </p><p>
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14   generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
15   request cannot be satisfied (eg. requires blocking or too much complexity).
16   It would then be called again in ref-walk mode.
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