<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>lock_may_read</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Filesystems API" /><link rel="up" href="ch01s05.html" title="File Locks" /><link rel="prev" href="re65.html" title="vfs_cancel_lock" /><link rel="next" href="re67.html" title="lock_may_write" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>lock_may_read</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re65.html">Prev</a> </td><th width="60%" align="center">File Locks</th><td width="20%" align="right"> <a accesskey="n" href="re67.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="lock_may_read"><a id="API-lock-may-read"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>lock_may_read — checks that the region is free of locks </p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">lock_may_read </b>(</code></td><td>struct inode * <var class="pdparam">inode</var>, </td></tr><tr><td> </td><td>loff_t <var class="pdparam">start</var>, </td></tr><tr><td> </td><td>unsigned long <var class="pdparam">len</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id3106066"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>inode</code></em></span></dt><dd><p> the inode that is being read </p></dd><dt><span class="term"><em class="parameter"><code>start</code></em></span></dt><dd><p> the first byte to read </p></dd><dt><span class="term"><em class="parameter"><code>len</code></em></span></dt><dd><p> the number of bytes to read </p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id3106125"></a><h2>Description</h2><p> Emulates Windows locking requirements. Whole-file mandatory locks (share modes) can prohibit a read and byte-range POSIX locks can prohibit a read if they overlap. </p><p> N.B. this function is only ever called from knfsd and ownership of locks is never checked. </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re65.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch01s05.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re67.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>vfs_cancel_lock</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>lock_may_write</span></td></tr></table></div></body></html>