3 .\" Copyright (c) 1996 Doug Rabson
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39 .Nd serialize access to a vnode
45 .Fn VOP_LOCK "struct vnode *vp" "int flags"
47 .Fn VOP_UNLOCK "struct vnode *vp" "int flags"
49 .Fn VOP_ISLOCKED "struct vnode *vp"
51 .Fn vn_lock "struct vnode *vp" "int flags"
53 These calls are used to serialize access to the file system, 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:
64 .Bl -tag -width ".Dv LK_CANRECURSE" -offset indent -compact
70 Shared-to-exclusive upgrade.
72 Exclusive-to-shared downgrade.
74 Release any type of lock.
76 Wait for all lock activity to end.
81 with these lock flags:
83 .Bl -tag -width ".Dv LK_CANRECURSE" -offset indent -compact
85 Do not sleep to wait for lock.
87 Sleep, then return failure.
89 Allow recursive exclusive lock.
94 with these control flags:
96 .Bl -tag -width ".Dv LK_CANRECURSE" -offset indent -compact
98 Specify when the caller already has a simple lock
100 will unlock the simple lock after getting the lock).
105 Kernel code should use
107 to lock a vnode rather than calling
111 also does not want a thread specified as argument but it
112 assumes curthread to be used.
114 Zero is returned on success, otherwise an error is returned.
120 * Other file system specific data.
126 #define VTOVON(vp) ((struct vopnode *) (vp)->v_data)
129 vop_lock(struct vnode *vp)
134 while (vp->v_flag & VXLOCK) {
135 vp->v_flag |= VXWANT;
136 tsleep((caddr_t)vp, PINOD, "voplk1", 0);
138 if (vp->v_tag == VT_NON)
142 if (vop->von_flag & VON_LOCKED) {
143 vop->von_flag |= VON_WANTED;
144 tsleep((caddr_t) vop, PINOD, "voplk2", 0);
148 vop->von_flag |= VON_LOCKED;
154 vop_unlock(struct vnode *vp)
156 struct vopnode *vop = VTOVON(vp);
158 if ((vop->von_flag & VON_LOCKED) == 0) {
159 panic("vop_unlock not locked");
161 vop->von_flag &= ~VON_LOCKED;
162 if (vop->von_flag & VON_WANTED) {
163 vop->von_flag &= ~VON_WANTED;
164 wakeup((caddr_t) vop);
171 vop_islocked(struct vnode *vp)
173 struct vopnode *vop = VTOVON(vp);
175 if (vop->von_flag & VON_LOCKED)
184 This manual page was written by