lockf.h revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 * 4. 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	8.1 (Berkeley) 6/11/93
35 * $FreeBSD: stable/11/sys/sys/lockf.h 330897 2018-03-14 03:19:51Z eadler $
36 */
37
38#ifndef _SYS_LOCKF_H_
39#define	_SYS_LOCKF_H_
40
41#include <sys/queue.h>
42#include <sys/_lock.h>
43#include <sys/_sx.h>
44
45struct flock;
46struct vop_advlock_args;
47struct vop_advlockasync_args;
48
49/*
50 * The lockf_entry structure is a kernel structure which contains the
51 * information associated with a byte range lock.  The lockf_entry
52 * structures are linked into the inode structure. Locks are sorted by
53 * the starting byte of the lock for efficiency.
54 *
55 * Active and pending locks on a vnode are organised into a
56 * graph. Each pending lock has an out-going edge to each active lock
57 * that blocks it.
58 *
59 * Locks:
60 * (i)		locked by the vnode interlock
61 * (s)		locked by state->ls_lock
62 * (S)		locked by lf_lock_states_lock
63 * (c)		const until freeing
64 */
65struct lockf_edge {
66	LIST_ENTRY(lockf_edge) le_outlink; /* (s) link from's out-edge list */
67	LIST_ENTRY(lockf_edge) le_inlink; /* (s) link to's in-edge list */
68	struct lockf_entry *le_from;	/* (c) out-going from here */
69	struct lockf_entry *le_to;	/* (s) in-coming to here */
70};
71LIST_HEAD(lockf_edge_list, lockf_edge);
72
73struct lockf_entry {
74	short	lf_flags;	    /* (c) Semantics: F_POSIX, F_FLOCK, F_WAIT */
75	short	lf_type;	    /* (s) Lock type: F_RDLCK, F_WRLCK */
76	off_t	lf_start;	    /* (s) Byte # of the start of the lock */
77	off_t	lf_end;		    /* (s) Byte # of the end of the lock (OFF_MAX=EOF) */
78	struct	lock_owner *lf_owner; /* (c) Owner of the lock */
79	struct	vnode *lf_vnode;    /* (c) File being locked (only valid for active lock) */
80	struct	inode *lf_inode;    /* (c) Back pointer to the inode */
81	struct	task *lf_async_task;/* (c) Async lock callback */
82	LIST_ENTRY(lockf_entry) lf_link;  /* (s) Linkage for lock lists */
83	struct lockf_edge_list lf_outedges; /* (s) list of out-edges */
84	struct lockf_edge_list lf_inedges; /* (s) list of out-edges */
85	int	lf_refs;	    /* (s) ref count */
86};
87LIST_HEAD(lockf_entry_list, lockf_entry);
88
89/*
90 * Extra lf_flags bits used by the implementation
91 */
92#define	F_INTR		0x8000	/* lock was interrupted by lf_purgelocks */
93
94/*
95 * Filesystem private node structures should include space for a
96 * pointer to a struct lockf_state. This pointer is used by the lock
97 * manager to track the locking state for a file.
98 *
99 * The ls_active list contains the set of active locks on the file. It
100 * is strictly ordered by the lock's lf_start value. Each active lock
101 * will have in-coming edges to any pending lock which it blocks.
102 *
103 * Lock requests which are blocked by some other active lock are
104 * listed in ls_pending with newer requests first in the list. Lock
105 * requests in this list will have out-going edges to each active lock
106 * that blocks then. They will also have out-going edges to each
107 * pending lock that is older in the queue - this helps to ensure
108 * fairness when several processes are contenting to lock the same
109 * record.
110
111 * The value of ls_threads is the number of threads currently using
112 * the state structure (typically either setting/clearing locks or
113 * sleeping waiting to do so). This is used to defer freeing the
114 * structure while some thread is still using it.
115 */
116struct lockf {
117	LIST_ENTRY(lockf) ls_link;	/* (S) all active lockf states */
118	struct	sx	ls_lock;
119	struct	lockf_entry_list ls_active; /* (s) Active locks */
120	struct	lockf_entry_list ls_pending; /* (s) Pending locks */
121	int		ls_threads;	/* (i) Thread count */
122};
123LIST_HEAD(lockf_list, lockf);
124
125typedef int lf_iterator(struct vnode *, struct flock *, void *);
126
127int	 lf_advlock(struct vop_advlock_args *, struct lockf **, u_quad_t);
128int	 lf_advlockasync(struct vop_advlockasync_args *, struct lockf **, u_quad_t);
129void	 lf_purgelocks(struct vnode *vp, struct lockf **statep);
130int	 lf_iteratelocks_sysid(int sysid, lf_iterator *, void *);
131int	 lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *, void *);
132int	 lf_countlocks(int sysid);
133void	 lf_clearremotesys(int sysid);
134
135#endif /* !_SYS_LOCKF_H_ */
136