1 .\" Copyright (c) 1996 Doug Rabson
3 .\" All rights reserved.
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27 .\" $FreeBSD: src/share/man/man9/VOP_LOCK.9,v 1.8.2.3 2001/12/17 11:30:18 ru Exp $
28 .\" $DragonFly: src/share/man/man9/VOP_LOCK.9,v 1.5 2004/06/01 11:36:53 hmp Exp $
38 .Nd serialize access to a vnode
44 .Fn VOP_LOCK "struct vnode *vp" "int flags" "struct proc *p"
46 .Fn VOP_UNLOCK "struct vnode *vp" "int flags" "struct proc *p"
48 .Fn VOP_ISLOCKED "struct vnode *vp" "struct proc *p"
50 .Fn vn_lock "struct vnode *vp" "int flags" "struct proc *p"
52 These calls are used to serialize access to the filesystem, such as
53 to prevent two writes to the same file from happening at the
59 the vnode being locked or unlocked
61 One of the lock request types:
62 .Bl -column LK_EXCLUPGRADE -offset indent
63 .It Dv LK_SHARED Ta "Shared lock"
64 .It Dv LK_EXCLUSIVE Ta "Exclusive lock"
65 .It Dv LK_UPGRADE Ta "Shared-to-exclusive upgrade"
66 .It Dv LK_EXCLUPGRADE Ta "First shared-to-exclusive upgrade"
67 .It Dv LK_DOWNGRADE Ta "Exclusive-to-shared downgrade"
68 .It Dv LK_RELEASE Ta "Release any type of lock"
69 .It Dv LK_DRAIN Ta "Wait for all lock activity to end"
74 with these lock flags:
75 .Bl -column LK_CANRECURSE -offset indent
76 .It Dv LK_NOWAIT Ta "Do not sleep to wait for lock"
77 .It Dv LK_SLEEPFAIL Ta "Sleep, then return failure"
78 .It Dv LK_CANRECURSE Ta "Allow recursive exclusive lock"
79 .It Dv LK_REENABLE Ta "Lock is to be reenabled after drain"
80 .It Dv LK_NOPAUSE Ta "No spinloop"
85 with these control flags:
86 .Bl -column LK_INTERLOCK -offset indent
87 .It Dv LK_INTERLOCK Ta "Specify when the caller already has a simple lock \
88 (VOP_LOCK will unlock the simple lock after getting the lock)"
89 .It Dv LK_RETRY Ta "Retry until locked"
90 .It Dv LK_NOOBJ Ta "Don't create object"
93 process context to use for the locks
96 Kernel code should use
98 to lock a vnode rather than calling
102 Zero is returned on success, otherwise an error is returned.
108 * Other filesystem specific data.
114 #define VTOVON(vp) ((struct vopnode *) (vp)->v_data)
117 vop_lock(struct vnode *vp)
122 while (vp->v_flag & VXLOCK) {
123 vp->v_flag |= VXWANT;
124 tsleep((caddr_t)vp, 0, "voplk1", 0);
126 if (vp->v_tag == VT_NON)
130 if (vop->von_flag & VON_LOCKED) {
131 vop->von_flag |= VON_WANTED;
132 tsleep((caddr_t) vop, 0, "voplk2", 0);
136 vop->von_flag |= VON_LOCKED;
142 vop_unlock(struct vnode *vp)
144 struct vopnode *vop = VTOVON(vp);
146 if ((vop->von_flag & VON_LOCKED) == 0) {
147 panic("vop_unlock not locked");
149 vop->von_flag &= ~VON_LOCKED;
150 if (vop->von_flag & VON_WANTED) {
151 vop->von_flag &= ~VON_WANTED;
152 wakeup((caddr_t) vop);
159 vop_islocked(struct vnode *vp)
161 struct vopnode *vop = VTOVON(vp);
163 if (vop->von_flag & VON_LOCKED)
172 This man page was written by