3 .\" Copyright (c) 1996 Doug Rabson
5 .\" All rights reserved.
7 .\" This program is free software.
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10 .\" modification, are permitted provided that the following conditions
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14 .\" 2. Redistributions in binary form must reproduce the above copyright
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18 .\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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20 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 .\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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26 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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29 .\" $FreeBSD: src/share/man/man9/VOP_LOCK.9,v 1.8.2.3 2001/12/17 11:30:18 ru Exp $
30 .\" $DragonFly: src/share/man/man9/VOP_LOCK.9,v 1.4 2003/08/01 17:46:25 dillon Exp $
40 .Nd serialize access to a vnode
46 .Fn VOP_LOCK "struct vnode *vp" "int flags" "struct proc *p"
48 .Fn VOP_UNLOCK "struct vnode *vp" "int flags" "struct proc *p"
50 .Fn VOP_ISLOCKED "struct vnode *vp" "struct proc *p"
52 .Fn vn_lock "struct vnode *vp" "int flags" "struct proc *p"
54 These calls are used to serialize access to the filesystem, such as
55 to prevent two writes to the same file from happening at the
61 the vnode being locked or unlocked
63 One of the lock request types:
64 .Bl -column LK_EXCLUPGRADE -offset indent
65 .It Dv LK_SHARED Ta "Shared lock"
66 .It Dv LK_EXCLUSIVE Ta "Exclusive lock"
67 .It Dv LK_UPGRADE Ta "Shared-to-exclusive upgrade"
68 .It Dv LK_EXCLUPGRADE Ta "First shared-to-exclusive upgrade"
69 .It Dv LK_DOWNGRADE Ta "Exclusive-to-shared downgrade"
70 .It Dv LK_RELEASE Ta "Release any type of lock"
71 .It Dv LK_DRAIN Ta "Wait for all lock activity to end"
76 with these lock flags:
77 .Bl -column LK_CANRECURSE -offset indent
78 .It Dv LK_NOWAIT Ta "Do not sleep to wait for lock"
79 .It Dv LK_SLEEPFAIL Ta "Sleep, then return failure"
80 .It Dv LK_CANRECURSE Ta "Allow recursive exclusive lock"
81 .It Dv LK_REENABLE Ta "Lock is to be reenabled after drain"
82 .It Dv LK_NOPAUSE Ta "No spinloop"
87 with these control flags:
88 .Bl -column LK_INTERLOCK -offset indent
89 .It Dv LK_INTERLOCK Ta "Specify when the caller already has a simple lock \
90 (VOP_LOCK will unlock the simple lock after getting the lock)"
91 .It Dv LK_RETRY Ta "Retry until locked"
92 .It Dv LK_NOOBJ Ta "Don't create object"
95 process context to use for the locks
98 Kernel code should use
100 to lock a vnode rather than calling
104 Zero is returned on success, otherwise an error is returned.
110 * Other filesystem specific data.
116 #define VTOVON(vp) ((struct vopnode *) (vp)->v_data)
119 vop_lock(struct vnode *vp)
124 while (vp->v_flag & VXLOCK) {
125 vp->v_flag |= VXWANT;
126 tsleep((caddr_t)vp, 0, "voplk1", 0);
128 if (vp->v_tag == VT_NON)
132 if (vop->von_flag & VON_LOCKED) {
133 vop->von_flag |= VON_WANTED;
134 tsleep((caddr_t) vop, 0, "voplk2", 0);
138 vop->von_flag |= VON_LOCKED;
144 vop_unlock(struct vnode *vp)
146 struct vopnode *vop = VTOVON(vp);
148 if ((vop->von_flag & VON_LOCKED) == 0) {
149 panic("vop_unlock not locked");
151 vop->von_flag &= ~VON_LOCKED;
152 if (vop->von_flag & VON_WANTED) {
153 vop->von_flag &= ~VON_WANTED;
154 wakeup((caddr_t) vop);
161 vop_islocked(struct vnode *vp)
163 struct vopnode *vop = VTOVON(vp);
165 if (vop->von_flag & VON_LOCKED)
174 This man page was written by