xref: /titanic_41/usr/src/uts/common/fs/zfs/sys/zfs_rlock.h (revision 6774dc07ebd5a9d69956f033d5ac5a68803bd66b)
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
30 extern "C" {
31 #endif
32 
33 #ifdef _KERNEL
34 
35 #include <sys/zfs_znode.h>
36 
37 typedef enum {
38 	RL_READER,
39 	RL_WRITER,
40 	RL_APPEND
41 } rl_type_t;
42 
43 typedef 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  */
63 rl_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. */
66 void 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  */
72 void 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  */
78 int 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