1 .\" Copyright (c) 1996 Doug Rabson
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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 $
37 .Nd serialize access to a vnode
43 .Fn VOP_LOCK "struct vnode *vp" "int flags" "struct proc *p"
45 .Fn VOP_UNLOCK "struct vnode *vp" "int flags" "struct proc *p"
47 .Fn VOP_ISLOCKED "struct vnode *vp" "struct proc *p"
49 .Fn vn_lock "struct vnode *vp" "int flags" "struct proc *p"
51 These calls are used to serialize access to the filesystem, such as
52 to prevent two writes to the same file from happening at the
58 the vnode being locked or unlocked
60 One of the lock request types:
61 .Bl -column ".Dv LK_EXCLUPGRADE" -offset indent
62 .It Dv LK_SHARED Ta "Shared lock"
63 .It Dv LK_EXCLUSIVE Ta "Exclusive lock"
64 .It Dv LK_UPGRADE Ta "Shared-to-exclusive upgrade"
65 .It Dv LK_EXCLUPGRADE Ta "First shared-to-exclusive upgrade"
66 .It Dv LK_DOWNGRADE Ta "Exclusive-to-shared downgrade"
67 .It Dv LK_RELEASE Ta "Release any type of lock"
72 with these lock flags:
73 .Bl -column ".Dv LK_CANRECURSE" -offset indent
74 .It Dv LK_NOWAIT Ta "Do not sleep to wait for lock"
75 .It Dv LK_SLEEPFAIL Ta "Sleep, then return failure"
76 .It Dv LK_CANRECURSE Ta "Allow recursive exclusive lock"
81 with these control flags:
82 .Bl -column ".Dv LK_RETRY" -offset indent
83 .It Dv LK_RETRY Ta "Retry until locked"
84 .It Dv LK_NOOBJ Ta "Don't create object"
87 process context to use for the locks
90 Kernel code should use
92 to lock a vnode rather than calling
96 Zero is returned on success, otherwise an error is returned.
102 * Other filesystem specific data.
108 #define VTOVON(vp) ((struct vopnode *) (vp)->v_data)
111 vop_lock(struct vnode *vp)
116 while (vp->v_flag & VXLOCK) {
117 vp->v_flag |= VXWANT;
118 tsleep((caddr_t)vp, 0, "voplk1", 0);
120 if (vp->v_tag == VT_NON)
124 if (vop->von_flag & VON_LOCKED) {
125 vop->von_flag |= VON_WANTED;
126 tsleep((caddr_t) vop, 0, "voplk2", 0);
130 vop->von_flag |= VON_LOCKED;
136 vop_unlock(struct vnode *vp)
138 struct vopnode *vop = VTOVON(vp);
140 if ((vop->von_flag & VON_LOCKED) == 0) {
141 panic("vop_unlock not locked");
143 vop->von_flag &= ~VON_LOCKED;
144 if (vop->von_flag & VON_WANTED) {
145 vop->von_flag &= ~VON_WANTED;
146 wakeup((caddr_t) vop);
153 vop_islocked(struct vnode *vp)
155 struct vopnode *vop = VTOVON(vp);
157 if (vop->von_flag & VON_LOCKED)
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