3 .\" Copyright (c) 1996 Doug Rabson
5 .\" All rights reserved.
7 .\" This program is free software.
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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 $
39 .Nd serialize access to a vnode
45 .Fn VOP_LOCK "struct vnode *vp" "int flags" "struct proc *p"
47 .Fn VOP_UNLOCK "struct vnode *vp" "int flags" "struct proc *p"
49 .Fn VOP_ISLOCKED "struct vnode *vp" "struct proc *p"
51 .Fn vn_lock "struct vnode *vp" "int flags" "struct proc *p"
53 These calls are used to serialize access to the filesystem, such as
54 to prevent two writes to the same file from happening at the
60 the vnode being locked or unlocked
62 One of the lock request types:
63 .Bl -column LK_EXCLUPGRADE -offset indent
64 .It Dv LK_SHARED Ta "Shared lock"
65 .It Dv LK_EXCLUSIVE Ta "Exclusive lock"
66 .It Dv LK_UPGRADE Ta "Shared-to-exclusive upgrade"
67 .It Dv LK_EXCLUPGRADE Ta "First shared-to-exclusive upgrade"
68 .It Dv LK_DOWNGRADE Ta "Exclusive-to-shared downgrade"
69 .It Dv LK_RELEASE Ta "Release any type of lock"
70 .It Dv LK_DRAIN Ta "Wait for all lock activity to end"
75 with these lock flags:
76 .Bl -column LK_CANRECURSE -offset indent
77 .It Dv LK_NOWAIT Ta "Do not sleep to wait for lock"
78 .It Dv LK_SLEEPFAIL Ta "Sleep, then return failure"
79 .It Dv LK_CANRECURSE Ta "Allow recursive exclusive lock"
80 .It Dv LK_REENABLE Ta "Lock is to be reenabled after drain"
81 .It Dv LK_NOPAUSE Ta "No spinloop"
86 with these control flags:
87 .Bl -column LK_INTERLOCK -offset indent
88 .It Dv LK_INTERLOCK Ta "Specify when the caller already has a simple lock \
89 (VOP_LOCK will unlock the simple lock after getting the lock)"
90 .It Dv LK_RETRY Ta "Retry until locked"
91 .It Dv LK_NOOBJ Ta "Don't create object"
94 process context to use for the locks
97 Kernel code should use
99 to lock a vnode rather than calling
103 Zero is returned on success, otherwise an error is returned.
109 * Other filesystem specific data.
115 #define VTOVON(vp) ((struct vopnode *) (vp)->v_data)
118 vop_lock(struct vnode *vp)
123 while (vp->v_flag & VXLOCK) {
124 vp->v_flag |= VXWANT;
125 tsleep((caddr_t)vp, PINOD, "voplk1", 0);
127 if (vp->v_tag == VT_NON)
131 if (vop->von_flag & VON_LOCKED) {
132 vop->von_flag |= VON_WANTED;
133 tsleep((caddr_t) vop, PINOD, "voplk2", 0);
137 vop->von_flag |= VON_LOCKED;
143 vop_unlock(struct vnode *vp)
145 struct vopnode *vop = VTOVON(vp);
147 if ((vop->von_flag & VON_LOCKED) == 0) {
148 panic("vop_unlock not locked");
150 vop->von_flag &= ~VON_LOCKED;
151 if (vop->von_flag & VON_WANTED) {
152 vop->von_flag &= ~VON_WANTED;
153 wakeup((caddr_t) vop);
160 vop_islocked(struct vnode *vp)
162 struct vopnode *vop = VTOVON(vp);
164 if (vop->von_flag & VON_LOCKED)
173 This man page was written by