space_map.h revision 269773 
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) 2012, 2014 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	32
48
49/*
50 * The space_map_phys is the on-disk representation of the space map.
51 * Consumers of space maps should never reference any of the members of this
52 * structure directly. These members may only be updated in syncing context.
53 *
54 * Note the smp_object is no longer used but remains in the structure
55 * for backward compatibility.
56 */
57typedef struct space_map_phys {
58	uint64_t	smp_object;	/* on-disk space map object */
59	uint64_t	smp_objsize;	/* size of the object */
60	uint64_t	smp_alloc;	/* space allocated from the map */
61	uint64_t	smp_pad[5];	/* reserved */
62
63	/*
64	 * The smp_histogram maintains a histogram of free regions. Each
65	 * bucket, smp_histogram[i], contains the number of free regions
66	 * whose size is:
67	 * 2^(i+sm_shift) <= size of free region in bytes < 2^(i+sm_shift+1)
68	 */
69	uint64_t	smp_histogram[SPACE_MAP_HISTOGRAM_SIZE];
70} space_map_phys_t;
71
72/*
73 * The space map object defines a region of space, its size, how much is
74 * allocated, and the on-disk object that stores this information.
75 * Consumers of space maps may only access the members of this structure.
76 */
77typedef struct space_map {
78	uint64_t	sm_start;	/* start of map */
79	uint64_t	sm_size;	/* size of map */
80	uint8_t		sm_shift;	/* unit shift */
81	uint64_t	sm_length;	/* synced length */
82	uint64_t	sm_alloc;	/* synced space allocated */
83	objset_t	*sm_os;		/* objset for this map */
84	uint64_t	sm_object;	/* object id for this map */
85	uint32_t	sm_blksz;	/* block size for space map */
86	dmu_buf_t	*sm_dbuf;	/* space_map_phys_t dbuf */
87	space_map_phys_t *sm_phys;	/* on-disk space map */
88	kmutex_t	*sm_lock;	/* pointer to lock that protects map */
89} space_map_t;
90
91/*
92 * debug entry
93 *
94 *    1      3         10                     50
95 *  ,---+--------+------------+---------------------------------.
96 *  | 1 | action |  syncpass  |        txg (lower bits)         |
97 *  `---+--------+------------+---------------------------------'
98 *   63  62    60 59        50 49                               0
99 *
100 *
101 * non-debug entry
102 *
103 *    1               47                   1           15
104 *  ,-----------------------------------------------------------.
105 *  | 0 |   offset (sm_shift units)    | type |       run       |
106 *  `-----------------------------------------------------------'
107 *   63  62                          17   16   15               0
108 */
109
110/* All this stuff takes and returns bytes */
111#define	SM_RUN_DECODE(x)	(BF64_DECODE(x, 0, 15) + 1)
112#define	SM_RUN_ENCODE(x)	BF64_ENCODE((x) - 1, 0, 15)
113#define	SM_TYPE_DECODE(x)	BF64_DECODE(x, 15, 1)
114#define	SM_TYPE_ENCODE(x)	BF64_ENCODE(x, 15, 1)
115#define	SM_OFFSET_DECODE(x)	BF64_DECODE(x, 16, 47)
116#define	SM_OFFSET_ENCODE(x)	BF64_ENCODE(x, 16, 47)
117#define	SM_DEBUG_DECODE(x)	BF64_DECODE(x, 63, 1)
118#define	SM_DEBUG_ENCODE(x)	BF64_ENCODE(x, 63, 1)
119
120#define	SM_DEBUG_ACTION_DECODE(x)	BF64_DECODE(x, 60, 3)
121#define	SM_DEBUG_ACTION_ENCODE(x)	BF64_ENCODE(x, 60, 3)
122
123#define	SM_DEBUG_SYNCPASS_DECODE(x)	BF64_DECODE(x, 50, 10)
124#define	SM_DEBUG_SYNCPASS_ENCODE(x)	BF64_ENCODE(x, 50, 10)
125
126#define	SM_DEBUG_TXG_DECODE(x)		BF64_DECODE(x, 0, 50)
127#define	SM_DEBUG_TXG_ENCODE(x)		BF64_ENCODE(x, 0, 50)
128
129#define	SM_RUN_MAX			SM_RUN_DECODE(~0ULL)
130
131typedef enum {
132	SM_ALLOC,
133	SM_FREE
134} maptype_t;
135
136/*
137 * The data for a given space map can be kept on blocks of any size.
138 * Larger blocks entail fewer i/o operations, but they also cause the
139 * DMU to keep more data in-core, and also to waste more i/o bandwidth
140 * when only a few blocks have changed since the last transaction group.
141 * Rather than having a fixed block size for all space maps the block size
142 * can adjust as needed (see space_map_max_blksz). Set the initial block
143 * size for the space map to 4k.
144 */
145#define	SPACE_MAP_INITIAL_BLOCKSIZE	(1ULL << 12)
146
147int space_map_load(space_map_t *sm, range_tree_t *rt, maptype_t maptype);
148
149void space_map_histogram_clear(space_map_t *sm);
150void space_map_histogram_add(space_map_t *sm, range_tree_t *rt,
151    dmu_tx_t *tx);
152
153void space_map_update(space_map_t *sm);
154
155uint64_t space_map_object(space_map_t *sm);
156uint64_t space_map_allocated(space_map_t *sm);
157uint64_t space_map_length(space_map_t *sm);
158
159void space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
160    dmu_tx_t *tx);
161void space_map_truncate(space_map_t *sm, dmu_tx_t *tx);
162uint64_t space_map_alloc(objset_t *os, dmu_tx_t *tx);
163void space_map_free(space_map_t *sm, dmu_tx_t *tx);
164
165int space_map_open(space_map_t **smp, objset_t *os, uint64_t object,
166    uint64_t start, uint64_t size, uint8_t shift, kmutex_t *lp);
167void space_map_close(space_map_t *sm);
168
169int64_t space_map_alloc_delta(space_map_t *sm);
170
171#ifdef	__cplusplus
172}
173#endif
174
175#endif	/* _SYS_SPACE_MAP_H */
176