1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26#ifndef	_SYS_FS_ZFS_RLOCK_H
27#define	_SYS_FS_ZFS_RLOCK_H
28
29#ifdef	__cplusplus
30extern "C" {
31#endif
32
33#ifdef _KERNEL
34
35#include <sys/zfs_znode.h>
36
37typedef enum {
38	RL_READER,
39	RL_WRITER,
40	RL_APPEND
41} rl_type_t;
42
43typedef struct rl {
44	znode_t *r_zp;		/* znode this lock applies to */
45	avl_node_t r_node;	/* avl node link */
46	uint64_t r_off;		/* file range offset */
47	uint64_t r_len;		/* file range length */
48	uint_t r_cnt;		/* range reference count in tree */
49	rl_type_t r_type;	/* range type */
50	kcondvar_t r_wr_cv;	/* cv for waiting writers */
51	kcondvar_t r_rd_cv;	/* cv for waiting readers */
52	uint8_t r_proxy;	/* acting for original range */
53	uint8_t r_write_wanted;	/* writer wants to lock this range */
54	uint8_t r_read_wanted;	/* reader wants to lock this range */
55} rl_t;
56
57/*
58 * Lock a range (offset, length) as either shared (RL_READER)
59 * or exclusive (RL_WRITER or RL_APPEND).  RL_APPEND is a special type that
60 * is converted to RL_WRITER that specified to lock from the start of the
61 * end of file.  Returns the range lock structure.
62 */
63rl_t *zfs_range_lock(znode_t *zp, uint64_t off, uint64_t len, rl_type_t type);
64
65/* Unlock range and destroy range lock structure. */
66void zfs_range_unlock(rl_t *rl);
67
68/*
69 * Reduce range locked as RW_WRITER from whole file to specified range.
70 * Asserts the whole file was previously locked.
71 */
72void zfs_range_reduce(rl_t *rl, uint64_t off, uint64_t len);
73
74/*
75 * AVL comparison function used to order range locks
76 * Locks are ordered on the start offset of the range.
77 */
78int zfs_range_compare(const void *arg1, const void *arg2);
79
80#endif /* _KERNEL */
81
82#ifdef	__cplusplus
83}
84#endif
85
86#endif	/* _SYS_FS_ZFS_RLOCK_H */
87