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[unleashed.git] / include / sys / fssnap.h
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1 /*
2 * CDDL HEADER START
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
20 * CDDL HEADER END
23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
27 #ifndef _SYS_FSSNAP_H
28 #define _SYS_FSSNAP_H
30 #pragma ident "%Z%%M% %I% %E% SMI"
32 #include <sys/sysmacros.h>
33 #include <sys/devops.h>
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
39 #include <sys/buf.h>
40 #include <sys/taskq.h>
41 #include <sys/fs/ufs_inode.h>
43 /* snapshot backend interfaces, macros, and data structures */
45 #if defined(_KERNEL)
48 * defines for the number of threads used to handle tasks, the maximum
49 * number of chunks in memory at a time, and the maximum number of tasks to
50 * allow before the taskqs start throttling. MAXTASKS should be greater than
51 * or equal to MAX_MEM_CHUNKS.
53 #define FSSNAP_TASKQ_THREADS (2)
54 #define FSSNAP_MAX_MEM_CHUNKS (32)
55 #define FSSNAP_TASKQ_MAXTASKS (FSSNAP_MAX_MEM_CHUNKS)
58 * It is assumed that a chunk is a multiple of a disk sector so that
59 * the chunk size can be reduced before using it as a conversion
60 * factor. Therefore the number of chunks on a file system will
61 * always be less than the number of blocks it occupies, and these
62 * conversions will not overflow. (do not convert to bytes first!)
65 typedef unsigned long long chunknumber_t;
67 /* disk blocks to snapshot chunks */
68 #define dbtocowchunk(cmap, dblkno) ((dblkno) / \
69 ((cmap)->cmap_chunksz >> DEV_BSHIFT))
71 /* snapshot chunks to disk blocks */
72 #define cowchunktodb(cmap, cowchunk) ((cowchunk) * \
73 ((cmap)->cmap_chunksz >> DEV_BSHIFT))
76 * A snapshot_id is the shared structure between the snapshot driver
77 * and the file system.
79 typedef struct snapshot_id {
80 struct snapshot_id *sid_next; /* next snapshot in list */
81 krwlock_t sid_rwlock; /* protects enable/disable */
82 struct cow_info *sid_cowinfo; /* pointer to cow state */
83 uint_t sid_snapnumber; /* snapshot number */
84 uint_t sid_flags; /* general flags */
85 struct vnode *sid_fvp; /* root vnode to snapshot */
86 } snapshot_id_t;
88 /* snapshot_id flags */
89 #define SID_DISABLED (0x01) /* this snapshot has been disabled */
90 #define SID_DISABLING (0x02) /* this snapshot is being disabled */
91 #define SID_BLOCK_BUSY (0x04) /* snapshot block driver is attached */
92 #define SID_CHAR_BUSY (0x08) /* snapshot character driver is attached */
93 #define SID_CREATING (0x10) /* snapshot is being created */
94 #define SID_DELETE (0x20) /* error condition found, delete snapshot */
96 /* true if snapshot device is open */
97 #define SID_BUSY(sidp) (((sidp)->sid_flags & SID_BLOCK_BUSY) || \
98 ((sidp)->sid_flags & SID_CHAR_BUSY))
100 /* true if snapshot can not be used */
101 #define SID_INACTIVE(sidp) (((sidp)->sid_flags & SID_DISABLED) || \
102 ((sidp)->sid_flags & SID_DISABLING) || \
103 ((sidp)->sid_flags & SID_CREATING) || \
104 ((sidp)->sid_flags & SID_DELETE) || \
105 ((sidp)->sid_cowinfo == NULL))
107 /* true if snapshot can be reused now */
108 #define SID_AVAILABLE(sidp) (!SID_BUSY(sidp) && \
109 ((sidp)->sid_flags & SID_DISABLED))
112 * The cow_map keeps track of all translations, and two bitmaps to
113 * determine whether the chunk is eligible for translation, and if so
114 * whether or not it already has a translation. The candidate bitmap
115 * is read-only and does not require a lock, the hastrans bitmap and
116 * the translation table are protected by the cmap_rwlock.
118 typedef struct cow_map {
119 krwlock_t cmap_rwlock; /* protects this structure */
120 ksema_t cmap_throttle_sem; /* used to throttle writes */
121 uint32_t cmap_waiters; /* semaphore waiters */
122 uint_t cmap_chunksz; /* granularity of COW operations */
123 chunknumber_t cmap_chunksperbf; /* chunks in max backing file */
124 chunknumber_t cmap_nchunks; /* number of chunks in backing file */
125 uoff_t cmap_maxsize; /* max bytes allowed (0 is no limit) */
126 size_t cmap_bmsize; /* size of bitmaps (in bytes) */
127 caddr_t cmap_candidate; /* 1 = block is a candidate for COW */
128 caddr_t cmap_hastrans; /* 1 = an entry exists in the table */
129 struct cow_map_node *cmap_table; /* translation table */
130 } cow_map_t;
133 * The cow_map_node keeps track of chunks that are still in memory.
136 typedef struct cow_map_node {
137 struct cow_map_node *cmn_next;
138 struct cow_map_node *cmn_prev;
139 struct snapshot_id *cmn_sid; /* backpointer to snapshot */
140 chunknumber_t cmn_chunk; /* original chunk number */
141 caddr_t cmn_buf; /* the data itself */
142 int release_sem; /* flag to release */
143 /* cmap_throttle_sem */
144 } cow_map_node_t;
147 * The cow_info structure holds basic snapshot state information. It is
148 * mostly read-only once the snapshot is created so no locking is required.
149 * The exception is cow_nextchunk, which is ever-increasing and updated with
150 * atomic_add(). This structure is allocated dynamically, and creation and
151 * deletion of the snapshot is protected by the snapshot_mutex variable.
153 typedef struct cow_info {
154 int cow_backcount; /* number of backing files */
155 vnode_t **cow_backfile_array; /* array of backing files */
156 uoff_t cow_backfile_sz; /* max size of a backfile */
157 taskq_t *cow_taskq; /* task queue for async writes */
158 struct kstat *cow_kstat_mntpt; /* kstat for mount point */
159 struct kstat *cow_kstat_bfname; /* kstat for backing file */
160 struct kstat *cow_kstat_num; /* named numeric kstats */
161 struct cow_map cow_map; /* block translation table */
162 } cow_info_t;
164 /* kstat information */
165 struct cow_kstat_num {
166 kstat_named_t ckn_state; /* state of the snapshot device */
167 kstat_named_t ckn_bfsize; /* sum of sizes of backing files */
168 kstat_named_t ckn_maxsize; /* maximum backing file size */
169 kstat_named_t ckn_createtime; /* snapshot creation time */
170 kstat_named_t ckn_chunksize; /* chunk size */
173 /* ckn_state values */
174 #define COWSTATE_CREATING (0) /* snapshot being created */
175 #define COWSTATE_IDLE (1) /* snapshot exists, but not open */
176 #define COWSTATE_ACTIVE (2) /* snapshot open */
177 #define COWSTATE_DISABLED (3) /* snapshot deleted (pending close) */
179 extern uint_t bypass_snapshot_throttle_key;
181 #endif /* _KERNEL */
183 #ifdef __cplusplus
185 #endif
187 #endif /* _SYS_FSSNAP_H */