134 lines
3.8 KiB
Groff
134 lines
3.8 KiB
Groff
.\" Copyright (c) 2013 Gleb Smirnoff <glebius@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 3, 2013
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.Dt AIO_MLOCK 2
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.Os
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.Sh NAME
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.Nm aio_mlock
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.Nd asynchronous
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.Xr mlock 2
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operation
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In aio.h
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.Ft int
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.Fn aio_mlock "struct aiocb *iocb"
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.Sh DESCRIPTION
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The
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.Fn aio_mlock
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system call allows the calling process to lock into memory the
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physical pages associated with the virtual address range starting at
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.Fa iocb->aio_buf
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for
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.Fa iocb->aio_nbytes
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bytes.
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The call returns immediately after the locking request has
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been enqueued; the operation may or may not have completed at the time
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the call returns.
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.Pp
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The
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.Fa iocb
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pointer may be subsequently used as an argument to
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.Fn aio_return
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and
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.Fn aio_error
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in order to determine return or error status for the enqueued operation
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while it is in progress.
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.Pp
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If the request could not be enqueued (generally due to
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.Xr aio 4
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limits),
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then the call returns without having enqueued the request.
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.Sh RESTRICTIONS
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The Asynchronous I/O Control Block structure pointed to by
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.Fa iocb
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and the buffer that the
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.Fa iocb->aio_buf
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member of that structure references must remain valid until the
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operation has completed.
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For this reason, use of auto (stack) variables
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for these objects is discouraged.
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.Pp
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The asynchronous I/O control buffer
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.Fa iocb
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should be zeroed before the
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.Fn aio_mlock
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call to avoid passing bogus context information to the kernel.
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.Pp
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Modifications of the Asynchronous I/O Control Block structure or the
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buffer contents after the request has been enqueued, but before the
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request has completed, are not allowed.
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.Sh RETURN VALUES
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.Rv -std aio_mlock
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.Sh ERRORS
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The
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.Fn aio_read
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system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.It Bq Er ENOSYS
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The
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.Fn aio_mlock
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system call is not supported.
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.El
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.Pp
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If the request is successfully enqueued, but subsequently cancelled
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or an error occurs, the value returned by the
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.Fn aio_return
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system call is per the
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.Xr mlock 2
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system call, and the value returned by the
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.Fn aio_error
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system call is one of the error returns from the
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.Xr mlock 2
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system call, or
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.Er ECANCELED
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if the request was explicitly cancelled via a call to
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.Fn aio_cancel .
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.Sh SEE ALSO
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.Xr aio_cancel 2 ,
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.Xr aio_error 2 ,
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.Xr aio_return 2 ,
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.Xr mlock 2 ,
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.Xr aio 4
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.Sh PORTABILITY
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The
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.Fn aio_mlock
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system call is a
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.Fx
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extension, and should not be used in portable code.
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.Sh HISTORY
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The
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.Fn aio_mlock
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system call first appeared in
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.Fx 10.0 .
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.Sh AUTHORS
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The system call was introduced by
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.An Gleb Smirnoff Aq glebius@FreeBSD.org .
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