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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>__generic_make_request</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="The Linux Kernel API" /><link rel="up" href="ch14.html" title="Chapter 14. Block Devices" /><link rel="prev" href="re528.html" title="blk_rq_prep_clone" /><link rel="next" href="re530.html" title="blk_end_bidi_request" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>__generic_make_request</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re528.html">Prev</a> </td><th width="60%" align="center">Chapter 14. Block Devices</th><td width="20%" align="right"> <a accesskey="n" href="re530.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="__generic_make_request"><a id="API---generic-make-request"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>__generic_make_request —
hand a buffer to its device driver for I/O
</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">void <b class="fsfunc">__generic_make_request </b>(</code></td><td>struct bio * <var class="pdparam">bio</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2699882"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>bio</code></em></span></dt><dd><p>
The bio describing the location in memory and on the device.
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2699909"></a><h2>Description</h2><p>
<code class="function">generic_make_request</code> is used to make I/O requests of block
devices. It is passed a <span class="structname">struct bio</span>, which describes the I/O that needs
to be done.
</p><p>
<code class="function">generic_make_request</code> does not return any status. The
success/failure status of the request, along with notification of
completion, is delivered asynchronously through the bio->bi_end_io
function described (one day) else where.
</p><p>
The caller of generic_make_request must make sure that bi_io_vec
are set to describe the memory buffer, and that bi_dev and bi_sector are
set to describe the device address, and the
bi_end_io and optionally bi_private are set to describe how
completion notification should be signaled.
</p><p>
generic_make_request and the drivers it calls may use bi_next if this
bio happens to be merged with someone else, and may change bi_dev and
bi_sector for remaps as it sees fit. So the values of these fields
should NOT be depended on after the call to generic_make_request.
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