aa12cea2cc
Although groff_mdoc(7) gives another impression, this is the ordering most widely used and also required by mdocml/mandoc. Reviewed by: ru Approved by: philip, ed (mentors)
163 lines
5.0 KiB
Groff
163 lines
5.0 KiB
Groff
.\" -*- nroff -*-
|
|
.\"
|
|
.\" Copyright (c) 1996 Doug Rabson
|
|
.\" Copyright 2003, Garrett A. Wollman
|
|
.\"
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This program is free software.
|
|
.\"
|
|
.\" 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 DEVELOPERS ``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 DEVELOPERS 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 September 27, 2003
|
|
.Dt VOP_GETPAGES 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm VOP_GETPAGES ,
|
|
.Nm VOP_PUTPAGES
|
|
.Nd read or write VM pages from a file
|
|
.Sh SYNOPSIS
|
|
.In sys/param.h
|
|
.In sys/vnode.h
|
|
.In vm/vm.h
|
|
.Ft int
|
|
.Fn VOP_GETPAGES "struct vnode *vp" "vm_page_t *m" "int count" "int reqpage" "vm_ooffset_t offset"
|
|
.Ft int
|
|
.Fn VOP_PUTPAGES "struct vnode *vp" "vm_page_t *m" "int count" "int sync" "int *rtvals" "vm_ooffset_t offset"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn VOP_GETPAGES
|
|
method is called to read in pages of virtual memory which are backed by
|
|
ordinary files.
|
|
If other adjacent pages are backed by adjacent regions of the same file,
|
|
.Fn VOP_GETPAGES
|
|
is requested to read those pages as well, although it is not required to
|
|
do so.
|
|
The
|
|
.Fn VOP_PUTPAGES
|
|
method does the converse; that is to say, it writes out adjacent dirty
|
|
pages of virtual memory.
|
|
.Pp
|
|
On entry, the vnode lock is held but neither the page queue nor VM object
|
|
locks are held.
|
|
Both methods return in the same state on both success and error returns.
|
|
.Pp
|
|
The arguments are:
|
|
.Bl -tag -width reqpage
|
|
.It Fa vp
|
|
The file to access.
|
|
.It Fa m
|
|
Pointer to the first element of an array of contiguous pages representing a
|
|
contiguous region of the file to be read or written.
|
|
.It Fa count
|
|
The number of pages in the array.
|
|
.It Fa sync
|
|
.Dv VM_PAGER_PUT_SYNC
|
|
if the write should be synchronous.
|
|
.It Fa rtvals
|
|
An array of VM system result codes indicating the status of each
|
|
page written by
|
|
.Fn VOP_PUTPAGES .
|
|
.It Fa reqpage
|
|
The index in the page array of the requested page; i.e., the one page which
|
|
the implementation of this method must handle.
|
|
.It Fa offset
|
|
Offset in the file at which the mapped pages begin.
|
|
.El
|
|
.Pp
|
|
The status of the
|
|
.Fn VOP_PUTPAGES
|
|
method is returned on a page-by-page basis in the array
|
|
.Fa rtvals[] .
|
|
The possible status values are as follows:
|
|
.Bl -tag -width VM_PAGER_ERROR
|
|
.It Dv VM_PAGER_OK
|
|
The page was successfully written.
|
|
The implementation must call
|
|
.Xr vm_page_undirty 9
|
|
to mark the page as clean.
|
|
.It Dv VM_PAGER_PEND
|
|
The page was scheduled to be written asynchronously.
|
|
When the write completes, the completion callback should
|
|
call
|
|
.Xr vm_object_pip_wakeup 9
|
|
and
|
|
.Xr vm_page_io_finish 9
|
|
to clear the busy flag and awaken any other threads waiting for this page,
|
|
in addition to calling
|
|
.Xr vm_page_undirty 9 .
|
|
.It Dv VM_PAGER_BAD
|
|
The page was entirely beyond the end of the backing file.
|
|
This condition should not be possible if the vnode's file system
|
|
is correctly implemented.
|
|
.It Dv VM_PAGER_ERROR
|
|
The page could not be written because of an error on the underlying storage
|
|
medium or protocol.
|
|
.It Dv VM_PAGER_FAIL
|
|
Treated identically to
|
|
.Dv VM_PAGER_ERROR
|
|
.It Dv VM_PAGER_AGAIN
|
|
The page was not handled by this request.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn VOP_GETPAGES
|
|
method is expected to release any pages in
|
|
.Fa m
|
|
that it does not successfully handle, by calling
|
|
.Xr vm_page_free 9 .
|
|
When it succeeds,
|
|
.Fn VOP_GETPAGES
|
|
must set the valid bits appropriately, clear the dirty bit
|
|
(using
|
|
.Xr vm_page_undirty 9 ) ,
|
|
either activate the page (if its wanted bit is set)
|
|
or deactivate it (otherwise), and finally call
|
|
.Xr vm_page_wakeup 9
|
|
to arouse any threads currently waiting for the page to be faulted in,
|
|
for each page read.
|
|
.Sh RETURN VALUES
|
|
If it successfully reads
|
|
.Fa m[reqpage] ,
|
|
.Fn VOP_GETPAGES
|
|
returns
|
|
.Dv VM_PAGER_OK ;
|
|
otherwise,
|
|
.Dv VM_PAGER_ERROR .
|
|
By convention, the return value of
|
|
.Fn VOP_PUTPAGES
|
|
is
|
|
.Fa rtvals[0] .
|
|
.Sh SEE ALSO
|
|
.Xr vm_object_pip_wakeup 9 ,
|
|
.Xr vm_page_free 9 ,
|
|
.Xr vm_page_io_finish 9 ,
|
|
.Xr vm_page_undirty 9 ,
|
|
.Xr vm_page_wakeup 9 ,
|
|
.Xr vnode 9
|
|
.Sh AUTHORS
|
|
This manual page was written by
|
|
.An Doug Rabson
|
|
and then substantially rewritten by
|
|
.An Garrett Wollman .
|