space_map.h revision 262093 
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 2009 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26/*
27 * Copyright (c) 2013 by Delphix. All rights reserved.
28 */
29
30#ifndef _SYS_SPACE_MAP_H
31#define	_SYS_SPACE_MAP_H
32
33#include <sys/avl.h>
34#include <sys/range_tree.h>
35#include <sys/dmu.h>
36
37#ifdef	__cplusplus
38extern "C" {
39#endif
40
41/*
42 * The size of the space map object has increased to include a histogram.
43 * The SPACE_MAP_SIZE_V0 designates the original size and is used to
44 * maintain backward compatibility.
45 */
46#define	SPACE_MAP_SIZE_V0	(3 * sizeof (uint64_t))
47#define	SPACE_MAP_HISTOGRAM_SIZE(sm)			\
48	(sizeof ((sm)->sm_phys->smp_histogram) /	\
49	sizeof ((sm)->sm_phys->smp_histogram[0]))
50
51/*
52 * The space_map_phys is the on-disk representation of the space map.
53 * Consumers of space maps should never reference any of the members of this
54 * structure directly. These members may only be updated in syncing context.
55 *
56 * Note the smp_object is no longer used but remains in the structure
57 * for backward compatibility.
58 */
59typedef struct space_map_phys {
60	uint64_t	smp_object;	/* on-disk space map object */
61	uint64_t	smp_objsize;	/* size of the object */
62	uint64_t	smp_alloc;	/* space allocated from the map */
63	uint64_t	smp_pad[5];	/* reserved */
64
65	/*
66	 * The smp_histogram maintains a histogram of free regions. Each
67	 * bucket, smp_histogram[i], contains the number of free regions
68	 * whose size is:
69	 * 2^(i+sm_shift) <= size of free region in bytes < 2^(i+sm_shift+1)
70	 */
71	uint64_t	smp_histogram[32]; /* histogram of free space */
72} space_map_phys_t;
73
74/*
75 * The space map object defines a region of space, its size, how much is
76 * allocated, and the on-disk object that stores this information.
77 * Consumers of space maps may only access the members of this structure.
78 */
79typedef struct space_map {
80	uint64_t	sm_start;	/* start of map */
81	uint64_t	sm_size;	/* size of map */
82	uint8_t		sm_shift;	/* unit shift */
83	uint64_t	sm_length;	/* synced length */
84	uint64_t	sm_alloc;	/* synced space allocated */
85	objset_t	*sm_os;		/* objset for this map */
86	uint64_t	sm_object;	/* object id for this map */
87	uint32_t	sm_blksz;	/* block size for space map */
88	dmu_buf_t	*sm_dbuf;	/* space_map_phys_t dbuf */
89	space_map_phys_t *sm_phys;	/* on-disk space map */
90	kmutex_t	*sm_lock;	/* pointer to lock that protects map */
91} space_map_t;
92
93/*
94 * debug entry
95 *
96 *    1      3         10                     50
97 *  ,---+--------+------------+---------------------------------.
98 *  | 1 | action |  syncpass  |        txg (lower bits)         |
99 *  `---+--------+------------+---------------------------------'
100 *   63  62    60 59        50 49                               0
101 *
102 *
103 * non-debug entry
104 *
105 *    1               47                   1           15
106 *  ,-----------------------------------------------------------.
107 *  | 0 |   offset (sm_shift units)    | type |       run       |
108 *  `-----------------------------------------------------------'
109 *   63  62                          17   16   15               0
110 */
111
112/* All this stuff takes and returns bytes */
113#define	SM_RUN_DECODE(x)	(BF64_DECODE(x, 0, 15) + 1)
114#define	SM_RUN_ENCODE(x)	BF64_ENCODE((x) - 1, 0, 15)
115#define	SM_TYPE_DECODE(x)	BF64_DECODE(x, 15, 1)
116#define	SM_TYPE_ENCODE(x)	BF64_ENCODE(x, 15, 1)
117#define	SM_OFFSET_DECODE(x)	BF64_DECODE(x, 16, 47)
118#define	SM_OFFSET_ENCODE(x)	BF64_ENCODE(x, 16, 47)
119#define	SM_DEBUG_DECODE(x)	BF64_DECODE(x, 63, 1)
120#define	SM_DEBUG_ENCODE(x)	BF64_ENCODE(x, 63, 1)
121
122#define	SM_DEBUG_ACTION_DECODE(x)	BF64_DECODE(x, 60, 3)
123#define	SM_DEBUG_ACTION_ENCODE(x)	BF64_ENCODE(x, 60, 3)
124
125#define	SM_DEBUG_SYNCPASS_DECODE(x)	BF64_DECODE(x, 50, 10)
126#define	SM_DEBUG_SYNCPASS_ENCODE(x)	BF64_ENCODE(x, 50, 10)
127
128#define	SM_DEBUG_TXG_DECODE(x)		BF64_DECODE(x, 0, 50)
129#define	SM_DEBUG_TXG_ENCODE(x)		BF64_ENCODE(x, 0, 50)
130
131#define	SM_RUN_MAX			SM_RUN_DECODE(~0ULL)
132
133typedef enum {
134	SM_ALLOC,
135	SM_FREE
136} maptype_t;
137
138/*
139 * The data for a given space map can be kept on blocks of any size.
140 * Larger blocks entail fewer i/o operations, but they also cause the
141 * DMU to keep more data in-core, and also to waste more i/o bandwidth
142 * when only a few blocks have changed since the last transaction group.
143 * Rather than having a fixed block size for all space maps the block size
144 * can adjust as needed (see space_map_max_blksz). Set the initial block
145 * size for the space map to 4k.
146 */
147#define	SPACE_MAP_INITIAL_BLOCKSIZE	(1ULL << 12)
148
149int space_map_load(space_map_t *sm, range_tree_t *rt, maptype_t maptype);
150
151void space_map_histogram_clear(space_map_t *sm);
152void space_map_histogram_add(space_map_t *sm, range_tree_t *rt,
153    dmu_tx_t *tx);
154
155void space_map_update(space_map_t *sm);
156
157uint64_t space_map_object(space_map_t *sm);
158uint64_t space_map_allocated(space_map_t *sm);
159uint64_t space_map_length(space_map_t *sm);
160
161void space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
162    dmu_tx_t *tx);
163void space_map_truncate(space_map_t *sm, dmu_tx_t *tx);
164uint64_t space_map_alloc(objset_t *os, dmu_tx_t *tx);
165void space_map_free(space_map_t *sm, dmu_tx_t *tx);
166
167int space_map_open(space_map_t **smp, objset_t *os, uint64_t object,
168    uint64_t start, uint64_t size, uint8_t shift, kmutex_t *lp);
169void space_map_close(space_map_t *sm);
170
171int64_t space_map_alloc_delta(space_map_t *sm);
172
173#ifdef	__cplusplus
174}
175#endif
176
177#endif	/* _SYS_SPACE_MAP_H */
178