Add new system call - aio_mlock(). The name speaks for itself. It allows

to perform the mlock(2) operation, which can consume a lot of time, under
control of aio(4).

Reviewed by:	kib, jilles
Sponsored by:	Nginx, Inc.

3 files changed, 135 insertions, 0 deletions

diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 8e918bf..4cc87ae 100644
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -85,6 +85,7 @@ MAN+=	abort2.2 \
 	adjtime.2 \
 	aio_cancel.2 \
 	aio_error.2 \
+	aio_mlock.2 \
 	aio_read.2 \
 	aio_return.2 \
 	aio_suspend.2 \
diff --git a/lib/libc/sys/Symbol.map b/lib/libc/sys/Symbol.map
index 24f4621..4f1104e 100644
--- a/lib/libc/sys/Symbol.map
+++ b/lib/libc/sys/Symbol.map
@@ -379,6 +379,7 @@ FBSD_1.2 {
 
 FBSD_1.3 {
 	accept4;
+	aio_mlock;
 	bindat;
 	cap_fcntls_get;
 	cap_fcntls_limit;
diff --git a/lib/libc/sys/aio_mlock.2 b/lib/libc/sys/aio_mlock.2
new file mode 100644
index 0000000..a0aa23c
--- /dev/null
+++ b/lib/libc/sys/aio_mlock.2
@@ -0,0 +1,133 @@
+.\" Copyright (c) 2013 Gleb Smirnoff <glebius@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd June 3, 2013
+.Dt AIO_MLOCK 2
+.Os
+.Sh NAME
+.Nm aio_mlock
+.Nd asynchronous
+.Xr mlock 2
+operation
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In aio.h
+.Ft int
+.Fn aio_mlock "struct aiocb *iocb"
+.Sh DESCRIPTION
+The
+.Fn aio_mlock
+system call allows the calling process to lock into memory the
+physical pages associated with the virtual address range starting at
+.Fa iocb->aio_buf
+for
+.Fa iocb->aio_nbytes
+bytes.
+The call returns immediately after the locking request has
+been enqueued; the operation may or may not have completed at the time
+the call returns.
+.Pp
+The
+.Fa iocb
+pointer may be subsequently used as an argument to
+.Fn aio_return
+and
+.Fn aio_error
+in order to determine return or error status for the enqueued operation
+while it is in progress.
+.Pp
+If the request could not be enqueued (generally due to 
+.Xr aio 4
+limits),
+then the call returns without having enqueued the request.
+.Sh RESTRICTIONS
+The Asynchronous I/O Control Block structure pointed to by
+.Fa iocb
+and the buffer that the
+.Fa iocb->aio_buf
+member of that structure references must remain valid until the
+operation has completed.
+For this reason, use of auto (stack) variables
+for these objects is discouraged.
+.Pp
+The asynchronous I/O control buffer
+.Fa iocb
+should be zeroed before the
+.Fn aio_mlock
+call to avoid passing bogus context information to the kernel.
+.Pp
+Modifications of the Asynchronous I/O Control Block structure or the
+buffer contents after the request has been enqueued, but before the
+request has completed, are not allowed.
+.Sh RETURN VALUES
+.Rv -std aio_mlock
+.Sh ERRORS
+The
+.Fn aio_read
+system call will fail if:
+.Bl -tag -width Er
+.It Bq Er EAGAIN
+The request was not queued because of system resource limitations.
+.It Bq Er ENOSYS
+The
+.Fn aio_mlock
+system call is not supported.
+.El
+.Pp
+If the request is successfully enqueued, but subsequently cancelled
+or an error occurs, the value returned by the
+.Fn aio_return
+system call is per the
+.Xr mlock 2
+system call, and the value returned by the
+.Fn aio_error
+system call is one of the error returns from the
+.Xr mlock 2
+system call, or
+.Er ECANCELED
+if the request was explicitly cancelled via a call to
+.Fn aio_cancel .
+.Sh SEE ALSO
+.Xr aio_cancel 2 ,
+.Xr aio_error 2 ,
+.Xr aio_return 2 ,
+.Xr aio 4 ,
+.Xr mlock 2
+.Sh PORTABILITY
+The
+.Fn aio_mlock
+system call is a
+.Fx
+extension, and should not be used in portable code.
+.Sh HISTORY
+The
+.Fn aio_mlock
+system call first appeared in
+.Fx 10.0 .
+.Sh AUTHORS
+The system call was introduced by
+.An Gleb Smirnoff Aq glebius@FreeBSD.org .