FreeBSD/Linux Kernel Cross Reference
sys/sys/lockf.h
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 * 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 8.1 (Berkeley) 6/11/93
35 * $FreeBSD$
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
45 struct flock;
46 struct vop_advlock_args;
47 struct 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 */
65 struct 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 };
71 LIST_HEAD(lockf_edge_list, lockf_edge);
72
73 struct 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 task *lf_async_task;/* (c) Async lock callback */
81 LIST_ENTRY(lockf_entry) lf_link; /* (s) Linkage for lock lists */
82 struct lockf_edge_list lf_outedges; /* (s) list of out-edges */
83 struct lockf_edge_list lf_inedges; /* (s) list of in-edges */
84 int lf_refs; /* (s) ref count */
85 };
86 LIST_HEAD(lockf_entry_list, lockf_entry);
87
88 /*
89 * Extra lf_flags bits used by the implementation
90 */
91 #define F_INTR 0x8000 /* lock was interrupted by lf_purgelocks */
92
93 /*
94 * Filesystem private node structures should include space for a
95 * pointer to a struct lockf_state. This pointer is used by the lock
96 * manager to track the locking state for a file.
97 *
98 * The ls_active list contains the set of active locks on the file. It
99 * is strictly ordered by the lock's lf_start value. Each active lock
100 * will have in-coming edges to any pending lock which it blocks.
101 *
102 * Lock requests which are blocked by some other active lock are
103 * listed in ls_pending with newer requests first in the list. Lock
104 * requests in this list will have out-going edges to each active lock
105 * that blocks then. They will also have out-going edges to each
106 * pending lock that is older in the queue - this helps to ensure
107 * fairness when several processes are contenting to lock the same
108 * record.
109
110 * The value of ls_threads is the number of threads currently using
111 * the state structure (typically either setting/clearing locks or
112 * sleeping waiting to do so). This is used to defer freeing the
113 * structure while some thread is still using it.
114 */
115 struct lockf {
116 LIST_ENTRY(lockf) ls_link; /* (S) all active lockf states */
117 struct sx ls_lock;
118 struct lockf_entry_list ls_active; /* (s) Active locks */
119 struct lockf_entry_list ls_pending; /* (s) Pending locks */
120 int ls_threads; /* (i) Thread count */
121 };
122 LIST_HEAD(lockf_list, lockf);
123
124 typedef int lf_iterator(struct vnode *, struct flock *, void *);
125
126 int lf_advlock(struct vop_advlock_args *, struct lockf **, u_quad_t);
127 int lf_advlockasync(struct vop_advlockasync_args *, struct lockf **, u_quad_t);
128 void lf_purgelocks(struct vnode *vp, struct lockf **statep);
129 int lf_iteratelocks_sysid(int sysid, lf_iterator *, void *);
130 int lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *, void *);
131 int lf_countlocks(int sysid);
132 void lf_clearremotesys(int sysid);
133
134 #endif /* !_SYS_LOCKF_H_ */
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