FreeBSD/Linux Kernel Cross Reference
sys/sys/lockf.h
1 /* $NetBSD: lockf.h,v 1.15 2004/04/25 16:42:43 simonb Exp $ */
2
3 /*
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Scooter Morris at Genentech Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)lockf.h 8.2 (Berkeley) 10/26/94
35 */
36
37 #ifndef _SYS_LOCKF_H_
38 #define _SYS_LOCKF_H_
39
40 /*
41 * The lockf structure is a kernel structure which contains the information
42 * associated with a byte range lock. The lockf structures are linked into
43 * the inode structure. Locks are sorted by the starting byte of the lock for
44 * efficiency.
45 *
46 * lf_next is used for two purposes, depending on whether the lock is
47 * being held, or is in conflict with an existing lock. If this lock
48 * is held, it indicates the next lock on the same vnode.
49 * For pending locks, if lock->lf_next is non-NULL, then lock->lf_block
50 * must be queued on the lf_blkhd TAILQ of lock->lf_next.
51 */
52
53 TAILQ_HEAD(locklist, lockf);
54
55 struct lockf {
56 short lf_flags; /* Lock semantics: F_POSIX, F_FLOCK, F_WAIT */
57 short lf_type; /* Lock type: F_RDLCK, F_WRLCK */
58 off_t lf_start; /* The byte # of the start of the lock */
59 off_t lf_end; /* The byte # of the end of the lock (-1=EOF)*/
60 void *lf_id; /* process or file description holding lock */
61 struct lwp *lf_lwp; /* LWP waiting for lock */
62 struct lockf **lf_head; /* Back pointer to the head of lockf list */
63 struct lockf *lf_next; /* Next lock on this vnode, or blocking lock */
64 struct locklist lf_blkhd; /* List of requests blocked on this lock */
65 TAILQ_ENTRY(lockf) lf_block;/* A request waiting for a lock */
66 };
67
68 /* Maximum length of sleep chains to traverse to try and detect deadlock. */
69 #define MAXDEPTH 50
70
71 #ifdef _KERNEL
72 int lf_advlock(struct vop_advlock_args *, struct lockf **, off_t);
73 #endif /* _KERNEL */
74
75 #endif /* !_SYS_LOCKF_H_ */
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