Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. |
| 3 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. |
| 4 | * |
| 5 | * Device-mapper snapshot exception store. |
| 6 | * |
| 7 | * This file is released under the GPL. |
| 8 | */ |
| 9 | |
| 10 | #ifndef _LINUX_DM_EXCEPTION_STORE |
| 11 | #define _LINUX_DM_EXCEPTION_STORE |
| 12 | |
| 13 | #include <linux/blkdev.h> |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 14 | #include <linux/device-mapper.h> |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 15 | |
| 16 | /* |
| 17 | * The snapshot code deals with largish chunks of the disk at a |
| 18 | * time. Typically 32k - 512k. |
| 19 | */ |
| 20 | typedef sector_t chunk_t; |
| 21 | |
| 22 | /* |
| 23 | * An exception is used where an old chunk of data has been |
| 24 | * replaced by a new one. |
| 25 | * If chunk_t is 64 bits in size, the top 8 bits of new_chunk hold the number |
| 26 | * of chunks that follow contiguously. Remaining bits hold the number of the |
| 27 | * chunk within the device. |
| 28 | */ |
| 29 | struct dm_snap_exception { |
| 30 | struct list_head hash_list; |
| 31 | |
| 32 | chunk_t old_chunk; |
| 33 | chunk_t new_chunk; |
| 34 | }; |
| 35 | |
| 36 | /* |
| 37 | * Abstraction to handle the meta/layout of exception stores (the |
| 38 | * COW device). |
| 39 | */ |
Jonathan Brassow | b2a1146 | 2009-04-02 19:55:30 +0100 | [diff] [blame] | 40 | struct dm_exception_store; |
| 41 | struct dm_exception_store_type { |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 42 | const char *name; |
| 43 | struct module *module; |
| 44 | |
Jonathan Brassow | b2a1146 | 2009-04-02 19:55:30 +0100 | [diff] [blame] | 45 | int (*ctr) (struct dm_exception_store *store, |
| 46 | unsigned argc, char **argv); |
| 47 | |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 48 | /* |
| 49 | * Destroys this object when you've finished with it. |
| 50 | */ |
Jonathan Brassow | b2a1146 | 2009-04-02 19:55:30 +0100 | [diff] [blame] | 51 | void (*dtr) (struct dm_exception_store *store); |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 52 | |
| 53 | /* |
| 54 | * The target shouldn't read the COW device until this is |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 55 | * called. As exceptions are read from the COW, they are |
| 56 | * reported back via the callback. |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 57 | */ |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 58 | int (*read_metadata) (struct dm_exception_store *store, |
| 59 | int (*callback)(void *callback_context, |
| 60 | chunk_t old, chunk_t new), |
| 61 | void *callback_context); |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 62 | |
| 63 | /* |
| 64 | * Find somewhere to store the next exception. |
| 65 | */ |
Jonathan Brassow | 1ae25f9 | 2009-01-06 03:05:16 +0000 | [diff] [blame] | 66 | int (*prepare_exception) (struct dm_exception_store *store, |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 67 | struct dm_snap_exception *e); |
| 68 | |
| 69 | /* |
| 70 | * Update the metadata with this exception. |
| 71 | */ |
Jonathan Brassow | 1ae25f9 | 2009-01-06 03:05:16 +0000 | [diff] [blame] | 72 | void (*commit_exception) (struct dm_exception_store *store, |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 73 | struct dm_snap_exception *e, |
| 74 | void (*callback) (void *, int success), |
| 75 | void *callback_context); |
| 76 | |
| 77 | /* |
| 78 | * The snapshot is invalid, note this in the metadata. |
| 79 | */ |
Jonathan Brassow | 1ae25f9 | 2009-01-06 03:05:16 +0000 | [diff] [blame] | 80 | void (*drop_snapshot) (struct dm_exception_store *store); |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 81 | |
Jonathan Brassow | 1e302a9 | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 82 | unsigned (*status) (struct dm_exception_store *store, |
| 83 | status_type_t status, char *result, |
| 84 | unsigned maxlen); |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 85 | |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 86 | /* |
| 87 | * Return how full the snapshot is. |
| 88 | */ |
Jonathan Brassow | 1ae25f9 | 2009-01-06 03:05:16 +0000 | [diff] [blame] | 89 | void (*fraction_full) (struct dm_exception_store *store, |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 90 | sector_t *numerator, |
| 91 | sector_t *denominator); |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 92 | |
| 93 | /* For internal device-mapper use only. */ |
| 94 | struct list_head list; |
Jonathan Brassow | b2a1146 | 2009-04-02 19:55:30 +0100 | [diff] [blame] | 95 | }; |
| 96 | |
| 97 | struct dm_exception_store { |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 98 | struct dm_exception_store_type *type; |
Jonathan Brassow | 0cea9c7 | 2009-04-02 19:55:32 +0100 | [diff] [blame] | 99 | struct dm_target *ti; |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 100 | |
Jonathan Brassow | 49beb2b | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 101 | struct dm_dev *cow; |
| 102 | |
Jonathan Brassow | d021684 | 2009-04-02 19:55:32 +0100 | [diff] [blame] | 103 | /* Size of data blocks saved - must be a power of 2 */ |
| 104 | chunk_t chunk_size; |
| 105 | chunk_t chunk_mask; |
| 106 | chunk_t chunk_shift; |
| 107 | |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 108 | void *context; |
| 109 | }; |
| 110 | |
| 111 | /* |
| 112 | * Funtions to manipulate consecutive chunks |
| 113 | */ |
Bartlomiej Zolnierkiewicz | 90c699a | 2009-06-19 08:08:50 +0200 | [diff] [blame] | 114 | # if defined(CONFIG_LBDAF) || (BITS_PER_LONG == 64) |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 115 | # define DM_CHUNK_CONSECUTIVE_BITS 8 |
| 116 | # define DM_CHUNK_NUMBER_BITS 56 |
| 117 | |
| 118 | static inline chunk_t dm_chunk_number(chunk_t chunk) |
| 119 | { |
| 120 | return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL); |
| 121 | } |
| 122 | |
| 123 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) |
| 124 | { |
| 125 | return e->new_chunk >> DM_CHUNK_NUMBER_BITS; |
| 126 | } |
| 127 | |
| 128 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) |
| 129 | { |
| 130 | e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS); |
| 131 | |
| 132 | BUG_ON(!dm_consecutive_chunk_count(e)); |
| 133 | } |
| 134 | |
| 135 | # else |
| 136 | # define DM_CHUNK_CONSECUTIVE_BITS 0 |
| 137 | |
| 138 | static inline chunk_t dm_chunk_number(chunk_t chunk) |
| 139 | { |
| 140 | return chunk; |
| 141 | } |
| 142 | |
| 143 | static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e) |
| 144 | { |
| 145 | return 0; |
| 146 | } |
| 147 | |
| 148 | static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) |
| 149 | { |
| 150 | } |
| 151 | |
| 152 | # endif |
| 153 | |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 154 | /* |
| 155 | * Return the number of sectors in the device. |
| 156 | */ |
| 157 | static inline sector_t get_dev_size(struct block_device *bdev) |
| 158 | { |
Mikulas Patocka | 5657e8f | 2009-06-22 10:12:14 +0100 | [diff] [blame] | 159 | return i_size_read(bdev->bd_inode) >> SECTOR_SHIFT; |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 160 | } |
| 161 | |
| 162 | static inline chunk_t sector_to_chunk(struct dm_exception_store *store, |
| 163 | sector_t sector) |
| 164 | { |
| 165 | return (sector & ~store->chunk_mask) >> store->chunk_shift; |
| 166 | } |
| 167 | |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 168 | int dm_exception_store_type_register(struct dm_exception_store_type *type); |
| 169 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type); |
| 170 | |
Mikulas Patocka | 2defcc3 | 2009-09-04 20:40:41 +0100 | [diff] [blame^] | 171 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, |
| 172 | unsigned long chunk_size_ulong, |
| 173 | char **error); |
| 174 | |
Jonathan Brassow | fee1998 | 2009-04-02 19:55:34 +0100 | [diff] [blame] | 175 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, |
| 176 | unsigned *args_used, |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 177 | struct dm_exception_store **store); |
| 178 | void dm_exception_store_destroy(struct dm_exception_store *store); |
| 179 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 180 | int dm_exception_store_init(void); |
| 181 | void dm_exception_store_exit(void); |
| 182 | |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 183 | /* |
| 184 | * Two exception store implementations. |
| 185 | */ |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 186 | int dm_persistent_snapshot_init(void); |
| 187 | void dm_persistent_snapshot_exit(void); |
| 188 | |
| 189 | int dm_transient_snapshot_init(void); |
| 190 | void dm_transient_snapshot_exit(void); |
| 191 | |
Jonathan Brassow | aea53d9 | 2009-01-06 03:05:15 +0000 | [diff] [blame] | 192 | #endif /* _LINUX_DM_EXCEPTION_STORE */ |