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.TH "BLK_INIT_QUEUE" "9" "07 August 2003" "" ""
.SH NAME
blk_init_queue \- prepare a request queue for use with a block device
.SH SYNOPSIS
.sp
\fB
.sp
int blk_init_queue  (request_queue_t * \fIq\fB, request_fn_proc * \fIrfn\fB, spinlock_t * \fIlock\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIq\fB\fR
The &request_queue_t to be initialised
.TP
\fB\fIrfn\fB\fR
The function to be called to process requests that have been
placed on the queue.
.TP
\fB\fIlock\fB\fR
-- undescribed --
.SH "DESCRIPTION"
.PP
If a block device wishes to use the standard request handling procedures,
which sorts requests and coalesces adjacent requests, then it must
call \fBblk_init_queue\fR.  The function \fIrfn\fR will be called when there
are requests on the queue that need to be processed.  If the device
supports plugging, then \fIrfn\fR may not be called immediately when requests
are available on the queue, but may be called at some time later instead.
Plugged queues are generally unplugged when a buffer belonging to one
of the requests on the queue is needed, or due to memory pressure.
.PP
\fIrfn\fR is not required, or even expected, to remove all requests off the
queue, but only as many as it can handle at a time.  If it does leave
requests on the queue, it is responsible for arranging that the requests
get dealt with eventually.
.PP
The queue spin lock must be held while manipulating the requests on the
request queue.
.SH "NOTE"
.PP
\fBblk_init_queue\fR must be paired with a \fBblk_cleanup_queue\fR call
when the block device is deactivated (such as at module unload).
.SH "ABOUT THIS DOCUMENT"
.PP
This documentation is free software; you can redistribute
it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later
version.
.PP
This program is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
.PP
You should have received a copy of the GNU General Public
License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
.PP
For more details see the file COPYING in the source
distribution of Linux.
.PP
If you have comments on the formatting of this manpage, then please contact
Michael Still (mikal@stillhq.com).
.PP
This documentation was generated with kernel version 2.6.0.