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Document vunref(9), add some important notes for vrele(9) and vput(9).

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Merge all three manpages to one, removing separate file for vput(9).

MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2010-10-17 16:30:33 +00:00
parent 3f562cce40
commit 251e7dbf42
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=213983
3 changed files with 49 additions and 71 deletions
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3
share/man/man9/Makefile
View File

@ -364,7 +364,6 @@ MAN= accept_filter.9 \
VOP_STRATEGY.9 \
VOP_VPTOCNP.9 \
VOP_VPTOFH.9 \
vput.9 \
vref.9 \
vrefcnt.9 \
vrele.9 \
@ -1366,6 +1365,8 @@ MLINKS+=VOP_RDWR.9 VOP_READ.9 \
VOP_RDWR.9 VOP_WRITE.9
MLINKS+=VOP_REMOVE.9 VOP_RMDIR.9
MLINKS+=vref.9 VREF.9
MLINKS+=vrele.9 vput.9 \
vrele.9 vunref.9
MLINKS+=vslock.9 vsunlock.9
MLINKS+=zero_copy.9 zero_copy_sockets.9
MLINKS+=zone.9 uma.9 \

63
share/man/man9/vput.9
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@ -1,63 +0,0 @@
.\" -*- nroff -*-
.\"
.\" Copyright (c) 1996 Doug Rabson
.\"
.\" 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 July 24, 1996
.Dt VPUT 9
.Os
.Sh NAME
.Nm vput
.Nd "decrement the use count for a vnode and unlock it"
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft void
.Fn vput "struct vnode *vp"
.Sh DESCRIPTION
Decrement the
.Va v_usecount
field of a vnode and unlock the vnode.
.Bl -tag -width 2n
.It Fa vp
the vnode to decrement
.El
.Pp
This operation is functionally equivalent to calling
.Xr VOP_UNLOCK 9
followed by
.Xr vrele 9 .
.Sh SEE ALSO
.Xr vnode 9 ,
.Xr VOP_UNLOCK 9 ,
.Xr vref 9 ,
.Xr vrele 9,
.Xr vrefcnt 9
.Sh AUTHORS
This manual page was written by
.An Doug Rabson .

54
share/man/man9/vrele.9
View File

@ -1,6 +1,7 @@
.\" -*- nroff -*-
.\"
.\" Copyright (c) 1996 Doug Rabson
.\" Copyright (c) 2010 Konstantin Belousov <kib@FreeBSD.org>
.\"
.\" All rights reserved.
.\"
@ -28,17 +29,23 @@
.\"
.\" $FreeBSD$
.\"
.Dd July 24, 1996
.Dd October 17, 2010
.Dt VRELE 9
.Os
.Sh NAME
.Nm vrele
.Nm vput ,
.Nm vrele ,
.Nm vunref
.Nd decrement the use count for a vnode
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft void
.Fn vput "struct vnode *vp"
.Ft void
.Fn vrele "struct vnode *vp"
.Ft void
.Fn vunref "struct vnode *vp"
.Sh DESCRIPTION
Decrement the
.Va v_usecount
@ -48,18 +55,51 @@ field of a vnode.
the vnode to decrement
.El
.Pp
Any code in the system which is using a vnode should call
The
.Fn vrele
when it is finished with the vnode.
function takes an unlocked vnode and returns with the vnode unlocked.
.Pp
.The
.Fn vput
function should be given a locked vnode as argument, the vnode is unlocked
after the function returned.
The
.Fn vput
is operationally equivalent to calling
.Xr VOP_UNLOCK 9
followed by
.Xr vrele 9 ,
with less overhead.
.Pp
The
.Fn vunref
function takes a locked vnode as argument, and returns with the vnode locked.
Nonetheless, the
.Fn vunref
might drop the vnode lock during the operation, so caller should not expect
that non-doomed vnode is still non-doomed after the function returned.
.Pp
Any code in the system which signified its use of a vnode by usecount
should call one of the listed function to decrement use counter.
If the
.Va v_usecount
field of the vnode reaches zero, then it will be placed on the free list.
field of the non-doomed vnode reaches zero, then it will be inactivated
and placed on the free list.
Since the functions might need to call VOPs for the vnode, the
.Va Giant
mutex should be conditionally locked around the call.
.Pp
The hold count for the vnode is always greater or equal to the usecount.
Non-forced unmount fails when mount point owns a vnode that has non-zero
usecount, see
.Xr vflush 9 .
.Sh SEE ALSO
.Xr vget 9 ,
.Xr vnode 9 ,
.Xr vput 9 ,
.Xr vref 9 ,
.Xr vrefcnt 9
.Sh AUTHORS
This manual page was written by
.An Doug Rabson .
.An Doug Rabson
and
.An Konstantin Belousov .