lockf.h revision 177633 
1/*-
2 * Copyright (c) 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Scooter Morris at Genentech Inc.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 *	@(#)lockf.h	8.1 (Berkeley) 6/11/93
33 * $FreeBSD: head/sys/sys/lockf.h 177633 2008-03-26 15:23:12Z dfr $
34 */
35
36#ifndef _SYS_LOCKF_H_
37#define	_SYS_LOCKF_H_
38
39#include <sys/queue.h>
40#include <sys/_lock.h>
41#include <sys/_sx.h>
42
43struct vop_advlock_args;
44struct vop_advlockasync_args;
45
46/*
47 * The lockf_entry structure is a kernel structure which contains the
48 * information associated with a byte range lock.  The lockf_entry
49 * structures are linked into the inode structure. Locks are sorted by
50 * the starting byte of the lock for efficiency.
51 *
52 * Active and pending locks on a vnode are organised into a
53 * graph. Each pending lock has an out-going edge to each active lock
54 * that blocks it.
55 *
56 * Locks:
57 * (i)		locked by the vnode interlock
58 * (s)		locked by state->ls_lock
59 * (S)		locked by lf_lock_states_lock
60 * (c)		const until freeing
61 */
62struct lockf_edge {
63	LIST_ENTRY(lockf_edge) le_outlink; /* (s) link from's out-edge list */
64	LIST_ENTRY(lockf_edge) le_inlink; /* (s) link to's in-edge list */
65	struct lockf_entry *le_from;	/* (c) out-going from here */
66	struct lockf_entry *le_to;	/* (s) in-coming to here */
67};
68LIST_HEAD(lockf_edge_list, lockf_edge);
69
70struct lockf_entry {
71	short	lf_flags;	    /* (c) Semantics: F_POSIX, F_FLOCK, F_WAIT */
72	short	lf_type;	    /* (s) Lock type: F_RDLCK, F_WRLCK */
73	off_t	lf_start;	    /* (s) Byte # of the start of the lock */
74	off_t	lf_end;		    /* (s) Byte # of the end of the lock (OFF_MAX=EOF) */
75	struct	lock_owner *lf_owner; /* (c) Owner of the lock */
76	struct	vnode *lf_vnode;    /* (c) File being locked (only valid for active lock) */
77	struct	inode *lf_inode;    /* (c) Back pointer to the inode */
78	struct	task *lf_async_task;/* (c) Async lock callback */
79	LIST_ENTRY(lockf_entry) lf_link;  /* (s) Linkage for lock lists */
80	struct lockf_edge_list lf_outedges; /* (s) list of out-edges */
81	struct lockf_edge_list lf_inedges; /* (s) list of out-edges */
82};
83LIST_HEAD(lockf_entry_list, lockf_entry);
84
85/*
86 * Filesystem private node structures should include space for a
87 * pointer to a struct lockf_state. This pointer is used by the lock
88 * manager to track the locking state for a file.
89 *
90 * The ls_active list contains the set of active locks on the file. It
91 * is strictly ordered by the lock's lf_start value. Each active lock
92 * will have in-coming edges to any pending lock which it blocks.
93 *
94 * Lock requests which are blocked by some other active lock are
95 * listed in ls_pending with newer requests first in the list. Lock
96 * requests in this list will have out-going edges to each active lock
97 * that blocks then. They will also have out-going edges to each
98 * pending lock that is older in the queue - this helps to ensure
99 * fairness when several processes are contenting to lock the same
100 * record.
101
102 * The value of ls_threads is the number of threads currently using
103 * the state structure (typically either setting/clearing locks or
104 * sleeping waiting to do so). This is used to defer freeing the
105 * structure while some thread is still using it.
106 */
107struct lockf {
108	LIST_ENTRY(lockf) ls_link;	/* (S) all active lockf states */
109	struct	sx	ls_lock;
110	struct	lockf_entry_list ls_active; /* (s) Active locks */
111	struct	lockf_entry_list ls_pending; /* (s) Pending locks */
112	int		ls_threads;	/* (i) Thread count */
113};
114LIST_HEAD(lockf_list, lockf);
115
116int	 lf_advlock(struct vop_advlock_args *, struct lockf **, u_quad_t);
117int	 lf_advlockasync(struct vop_advlockasync_args *, struct lockf **, u_quad_t);
118int	 lf_countlocks(int sysid);
119void	 lf_clearremotesys(int sysid);
120
121#endif /* !_SYS_LOCKF_H_ */
122