247 lines
7.1 KiB
Groff
247 lines
7.1 KiB
Groff
.\" Copyright (c) 2003 Poul-Henning Kamp
|
|
.\" 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.
|
|
.\" 3. The names of the authors may not be used to endorse or promote
|
|
.\" products derived from this software without specific prior written
|
|
.\" permission.
|
|
.\"
|
|
.\" 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 February 8, 2003
|
|
.Dt LIBGEOM 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm geom_stats_open ,
|
|
.Nm geom_stats_close ,
|
|
.Nm geom_stats_resync ,
|
|
.Nm geom_stats_snapshot_get ,
|
|
.Nm geom_stats_snapshot_free ,
|
|
.Nm geom_stats_snapshot_timestamp ,
|
|
.Nm geom_stats_snapshot_reset ,
|
|
.Nm geom_stats_snapshot_next ,
|
|
.Nm gctl_get_handle ,
|
|
.Nm gctl_ro_param ,
|
|
.Nm gctl_rw_param ,
|
|
.Nm gctl_issue ,
|
|
.Nm gctl_free ,
|
|
.Nm gctl_dump
|
|
.Nd userland API library for kernel GEOM subsystem
|
|
.Sh LIBRARY
|
|
.Lb libgeom
|
|
.Sh SYNOPSIS
|
|
.In libgeom.h
|
|
.Ss "Statistics Functions"
|
|
.Ft void
|
|
.Fn geom_stats_close void
|
|
.Ft int
|
|
.Fn geom_stats_open void
|
|
.Ft void
|
|
.Fn geom_stats_resync void
|
|
.Ft "void *"
|
|
.Fn geom_stats_snapshot_get void
|
|
.Ft void
|
|
.Fn geom_stats_snapshot_free "void *arg"
|
|
.Ft void
|
|
.Fn geom_stats_snapshot_timestamp "void *arg" "struct timespec *tp"
|
|
.Ft void
|
|
.Fn geom_stats_snapshot_reset "void *arg"
|
|
.Ft "struct g_stat *"
|
|
.Fn geom_stats_snapshot_next "void *arg"
|
|
.Ss "Control Functions"
|
|
.Ft "struct gctl_req *"
|
|
.Fn gctl_get_handle "void"
|
|
.Ft void
|
|
.Fn gctl_ro_param "struct gctl_req *req" "const char *name" "int len" "const void *value"
|
|
.Ft void
|
|
.Fn gctl_rw_param "struct gctl_req *req" "const char *name" "int len" "void *value"
|
|
.Ft "const char *"
|
|
.Fn gctl_issue "struct gctl_req *req"
|
|
.Ft void
|
|
.Fn gctl_free "struct gctl_req *req"
|
|
.Ft void
|
|
.Fn gctl_dump "struct gctl_req *req" "FILE *f"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm geom
|
|
library contains the official and publicized API for
|
|
interacting with the GEOM subsystem in the kernel.
|
|
.Ss "Statistics Functions"
|
|
GEOM collects statistics data for all consumers and providers, but does
|
|
not perform any normalization or presentation on the raw data, this is
|
|
left as an excercize for user-land presentation utilities.
|
|
.Pp
|
|
The
|
|
.Fn geom_stats_open
|
|
and
|
|
.Fn geom_stats_close
|
|
functions open and close the necessary pathways to access the raw
|
|
statistics information in the kernel.
|
|
These functions are likely to
|
|
open one or more files and cache the file descriptors locally.
|
|
The
|
|
.Fn geom_stats_open
|
|
function returns zero on success, and sets
|
|
.Va errno
|
|
if not.
|
|
.Pp
|
|
The
|
|
.Fn geom_stats_resync
|
|
function will check if more statistics collection points have been
|
|
added in the kernel since
|
|
.Fn geom_stats_open
|
|
or the previous call to
|
|
.Fn geom_stats_resync .
|
|
.Pp
|
|
The
|
|
.Fn geom_stats_snapshot_get
|
|
function
|
|
will acquire a snapshot of the raw data from the kernel, and while a
|
|
reasonable effort is made to make this snapshot as atomic and consistent
|
|
as possible, no guarantee is given that it will actually be so.
|
|
The snapshot must be freed again using the
|
|
.Fn geom_stats_snapshot_free
|
|
function.
|
|
The
|
|
.Fn geom_stats_snapshot_get
|
|
function returns
|
|
.Dv NULL
|
|
on failure.
|
|
.Pp
|
|
The
|
|
.Fn geom_stats_snapshot_timestamp
|
|
function
|
|
provides access to the timestamp acquired in the snapshot.
|
|
.Pp
|
|
The
|
|
.Fn geom_stats_snapshot_reset
|
|
and
|
|
.Fn geom_stats_snapshot_next
|
|
functions
|
|
provide an iterator over the statistics slots in the snapshot.
|
|
The
|
|
.Fn geom_stats_snapshot_reset
|
|
function
|
|
forces the internal pointer in the snapshot back to before the first item.
|
|
The
|
|
.Fn geom_stats_snapshot_next
|
|
function
|
|
returns the next item, and
|
|
.Dv NULL
|
|
if there are no more items in the snapshot.
|
|
.Ss "Control Functions"
|
|
The
|
|
.Fn gctl_*
|
|
functions are used to send requests to GEOM classes. In order for a GEOM
|
|
class to actually be able to receive these requests, it must have defined a
|
|
"ctlreq" method.
|
|
.Pp
|
|
A
|
|
.Ar struct gctl_req * ,
|
|
obtained with
|
|
.Fn gctl_get_handle ,
|
|
can hold any number of parameters, which must be added to it with
|
|
.Fn gctl_ro_param
|
|
(for read-only parameters) or
|
|
.Fn gctl_rw_param
|
|
(for read/write parameters).
|
|
.Pp
|
|
Both
|
|
.Fn gctl_ro_param
|
|
and
|
|
.Fn gctl_rw_param
|
|
take a string
|
|
.Ar name ,
|
|
which is used to identify the parameter, and a
|
|
.Ar value ,
|
|
which contains - in the read-only case - the data to be passed to the
|
|
GEOM class, or - in the read/write case - a pointer to preallocated memory
|
|
that the GEOM class should fill with the desired data. If
|
|
.Ar len
|
|
is negative, it is assumed that
|
|
.Ar value
|
|
is an ASCII string and the actual length is taken from the string length of
|
|
.Ar value ;
|
|
otherwise it must hold the size of
|
|
.Ar value .
|
|
.Pp
|
|
A parameter with a
|
|
.Ar name
|
|
containing the string "class" is mandatory for each request, and the
|
|
corresponding
|
|
.Ar value
|
|
must hold the name of the GEOM class where the request should be sent to.
|
|
.Pp
|
|
Also mandatory for each request is a parameter with a
|
|
.Ar name
|
|
called "verb", and the corresponding
|
|
.Ar value
|
|
needs to hold the command string that the GEOM class should react upon.
|
|
.Pp
|
|
Once all desired parameters are filled in, the request must be sent to
|
|
the GEOM subsystem with
|
|
.Fn gctl_issue ,
|
|
which returns NULL on success, or a string containing the error message
|
|
on failure.
|
|
.Pp
|
|
After the request is finished, the allocated memory should be released with
|
|
.Fn gctl_free .
|
|
.Pp
|
|
.Fn gctl_dump
|
|
can be used to format the contents of
|
|
.Ar req
|
|
to the open file handle pointed to by
|
|
.Ar f
|
|
for debugging purposes.
|
|
.Pp
|
|
Error handling for the control functions is postponed until the call
|
|
to
|
|
.Fn gctl_issue
|
|
which returns NULL on success or an error message corresponding to the
|
|
first error which happened.
|
|
.Sh EXAMPLES
|
|
Create a request that is to be sent to the CCD class and tell
|
|
it to destroy a specific geom:
|
|
.Bd -literal -offset indent
|
|
H = gctl_get_handle();
|
|
gctl_ro_param(H, "verb", -1, "destroy geom");
|
|
gctl_ro_param(H, "class", -1, "CCD");
|
|
sprintf(buf, "ccd%d", ccd);
|
|
gctl_ro_param(H, "geom", -1, buf);
|
|
errstr = gctl_issue(H);
|
|
if (errstr != NULL)
|
|
err(1, "Could not destroy ccd: %s", errstr);
|
|
gctl_free(H);
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Rs
|
|
http://ezine.daemonnews.org/200308/blueprints.html
|
|
.Re
|
|
.Sh HISTORY
|
|
The
|
|
.Nm geom
|
|
library appeared in
|
|
.Fx 5.1 .
|
|
.Sh AUTHORS
|
|
.An Poul-Henning Kamp Aq phk@FreeBSD.org
|
|
.An Lukas Ertl Aq le@FreeBSD.org
|