Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. |
| 3 | * Copyright (C) 2006-2008 Red Hat GmbH |
| 4 | * |
| 5 | * This file is released under the GPL. |
| 6 | */ |
| 7 | |
| 8 | #include "dm-exception-store.h" |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 9 | |
| 10 | #include <linux/mm.h> |
| 11 | #include <linux/pagemap.h> |
| 12 | #include <linux/vmalloc.h> |
Paul Gortmaker | daaa5f7 | 2011-05-27 15:50:58 -0400 | [diff] [blame] | 13 | #include <linux/export.h> |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 14 | #include <linux/slab.h> |
| 15 | #include <linux/dm-io.h> |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 16 | #include "dm-bufio.h" |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 17 | |
| 18 | #define DM_MSG_PREFIX "persistent snapshot" |
| 19 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ |
| 20 | |
Mikulas Patocka | 55b082e | 2014-01-13 19:13:05 -0500 | [diff] [blame] | 21 | #define DM_PREFETCH_CHUNKS 12 |
| 22 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 23 | /*----------------------------------------------------------------- |
| 24 | * Persistent snapshots, by persistent we mean that the snapshot |
| 25 | * will survive a reboot. |
| 26 | *---------------------------------------------------------------*/ |
| 27 | |
| 28 | /* |
| 29 | * We need to store a record of which parts of the origin have |
| 30 | * been copied to the snapshot device. The snapshot code |
| 31 | * requires that we copy exception chunks to chunk aligned areas |
| 32 | * of the COW store. It makes sense therefore, to store the |
| 33 | * metadata in chunk size blocks. |
| 34 | * |
| 35 | * There is no backward or forward compatibility implemented, |
| 36 | * snapshots with different disk versions than the kernel will |
| 37 | * not be usable. It is expected that "lvcreate" will blank out |
| 38 | * the start of a fresh COW device before calling the snapshot |
| 39 | * constructor. |
| 40 | * |
| 41 | * The first chunk of the COW device just contains the header. |
| 42 | * After this there is a chunk filled with exception metadata, |
| 43 | * followed by as many exception chunks as can fit in the |
| 44 | * metadata areas. |
| 45 | * |
| 46 | * All on disk structures are in little-endian format. The end |
| 47 | * of the exceptions info is indicated by an exception with a |
| 48 | * new_chunk of 0, which is invalid since it would point to the |
| 49 | * header chunk. |
| 50 | */ |
| 51 | |
| 52 | /* |
| 53 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. |
| 54 | */ |
| 55 | #define SNAP_MAGIC 0x70416e53 |
| 56 | |
| 57 | /* |
| 58 | * The on-disk version of the metadata. |
| 59 | */ |
| 60 | #define SNAPSHOT_DISK_VERSION 1 |
| 61 | |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 62 | #define NUM_SNAPSHOT_HDR_CHUNKS 1 |
| 63 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 64 | struct disk_header { |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 65 | __le32 magic; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 66 | |
| 67 | /* |
| 68 | * Is this snapshot valid. There is no way of recovering |
| 69 | * an invalid snapshot. |
| 70 | */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 71 | __le32 valid; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 72 | |
| 73 | /* |
| 74 | * Simple, incrementing version. no backward |
| 75 | * compatibility. |
| 76 | */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 77 | __le32 version; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 78 | |
| 79 | /* In sectors */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 80 | __le32 chunk_size; |
| 81 | } __packed; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 82 | |
| 83 | struct disk_exception { |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 84 | __le64 old_chunk; |
| 85 | __le64 new_chunk; |
| 86 | } __packed; |
| 87 | |
| 88 | struct core_exception { |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 89 | uint64_t old_chunk; |
| 90 | uint64_t new_chunk; |
| 91 | }; |
| 92 | |
| 93 | struct commit_callback { |
| 94 | void (*callback)(void *, int success); |
| 95 | void *context; |
| 96 | }; |
| 97 | |
| 98 | /* |
| 99 | * The top level structure for a persistent exception store. |
| 100 | */ |
| 101 | struct pstore { |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 102 | struct dm_exception_store *store; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 103 | int version; |
| 104 | int valid; |
| 105 | uint32_t exceptions_per_area; |
| 106 | |
| 107 | /* |
| 108 | * Now that we have an asynchronous kcopyd there is no |
| 109 | * need for large chunk sizes, so it wont hurt to have a |
| 110 | * whole chunks worth of metadata in memory at once. |
| 111 | */ |
| 112 | void *area; |
| 113 | |
| 114 | /* |
| 115 | * An area of zeros used to clear the next area. |
| 116 | */ |
| 117 | void *zero_area; |
| 118 | |
| 119 | /* |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 120 | * An area used for header. The header can be written |
| 121 | * concurrently with metadata (when invalidating the snapshot), |
| 122 | * so it needs a separate buffer. |
| 123 | */ |
| 124 | void *header_area; |
| 125 | |
| 126 | /* |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 127 | * Used to keep track of which metadata area the data in |
| 128 | * 'chunk' refers to. |
| 129 | */ |
| 130 | chunk_t current_area; |
| 131 | |
| 132 | /* |
| 133 | * The next free chunk for an exception. |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 134 | * |
| 135 | * When creating exceptions, all the chunks here and above are |
| 136 | * free. It holds the next chunk to be allocated. On rare |
| 137 | * occasions (e.g. after a system crash) holes can be left in |
| 138 | * the exception store because chunks can be committed out of |
| 139 | * order. |
| 140 | * |
| 141 | * When merging exceptions, it does not necessarily mean all the |
| 142 | * chunks here and above are free. It holds the value it would |
| 143 | * have held if all chunks had been committed in order of |
| 144 | * allocation. Consequently the value may occasionally be |
| 145 | * slightly too low, but since it's only used for 'status' and |
| 146 | * it can never reach its minimum value too early this doesn't |
| 147 | * matter. |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 148 | */ |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 149 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 150 | chunk_t next_free; |
| 151 | |
| 152 | /* |
| 153 | * The index of next free exception in the current |
| 154 | * metadata area. |
| 155 | */ |
| 156 | uint32_t current_committed; |
| 157 | |
| 158 | atomic_t pending_count; |
| 159 | uint32_t callback_count; |
| 160 | struct commit_callback *callbacks; |
| 161 | struct dm_io_client *io_client; |
| 162 | |
| 163 | struct workqueue_struct *metadata_wq; |
| 164 | }; |
| 165 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 166 | static int alloc_area(struct pstore *ps) |
| 167 | { |
| 168 | int r = -ENOMEM; |
| 169 | size_t len; |
| 170 | |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 171 | len = ps->store->chunk_size << SECTOR_SHIFT; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 172 | |
| 173 | /* |
| 174 | * Allocate the chunk_size block of memory that will hold |
| 175 | * a single metadata area. |
| 176 | */ |
| 177 | ps->area = vmalloc(len); |
| 178 | if (!ps->area) |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 179 | goto err_area; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 180 | |
Joe Perches | e29e65a | 2011-08-02 12:32:02 +0100 | [diff] [blame] | 181 | ps->zero_area = vzalloc(len); |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 182 | if (!ps->zero_area) |
| 183 | goto err_zero_area; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 184 | |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 185 | ps->header_area = vmalloc(len); |
| 186 | if (!ps->header_area) |
| 187 | goto err_header_area; |
| 188 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 189 | return 0; |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 190 | |
| 191 | err_header_area: |
| 192 | vfree(ps->zero_area); |
| 193 | |
| 194 | err_zero_area: |
| 195 | vfree(ps->area); |
| 196 | |
| 197 | err_area: |
| 198 | return r; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 199 | } |
| 200 | |
| 201 | static void free_area(struct pstore *ps) |
| 202 | { |
Jonathan Brassow | a32079c | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 203 | if (ps->area) |
| 204 | vfree(ps->area); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 205 | ps->area = NULL; |
Jonathan Brassow | a32079c | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 206 | |
| 207 | if (ps->zero_area) |
| 208 | vfree(ps->zero_area); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 209 | ps->zero_area = NULL; |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 210 | |
| 211 | if (ps->header_area) |
| 212 | vfree(ps->header_area); |
| 213 | ps->header_area = NULL; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 214 | } |
| 215 | |
| 216 | struct mdata_req { |
| 217 | struct dm_io_region *where; |
| 218 | struct dm_io_request *io_req; |
| 219 | struct work_struct work; |
| 220 | int result; |
| 221 | }; |
| 222 | |
| 223 | static void do_metadata(struct work_struct *work) |
| 224 | { |
| 225 | struct mdata_req *req = container_of(work, struct mdata_req, work); |
| 226 | |
| 227 | req->result = dm_io(req->io_req, 1, req->where, NULL); |
| 228 | } |
| 229 | |
| 230 | /* |
| 231 | * Read or write a chunk aligned and sized block of data from a device. |
| 232 | */ |
Mikulas Patocka | 02d2fd3 | 2009-09-04 20:40:37 +0100 | [diff] [blame] | 233 | static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw, |
| 234 | int metadata) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 235 | { |
| 236 | struct dm_io_region where = { |
Mike Snitzer | fc56f6f | 2009-12-10 23:52:12 +0000 | [diff] [blame] | 237 | .bdev = dm_snap_cow(ps->store->snap)->bdev, |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 238 | .sector = ps->store->chunk_size * chunk, |
| 239 | .count = ps->store->chunk_size, |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 240 | }; |
| 241 | struct dm_io_request io_req = { |
| 242 | .bi_rw = rw, |
| 243 | .mem.type = DM_IO_VMA, |
Mikulas Patocka | 02d2fd3 | 2009-09-04 20:40:37 +0100 | [diff] [blame] | 244 | .mem.ptr.vma = area, |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 245 | .client = ps->io_client, |
| 246 | .notify.fn = NULL, |
| 247 | }; |
| 248 | struct mdata_req req; |
| 249 | |
| 250 | if (!metadata) |
| 251 | return dm_io(&io_req, 1, &where, NULL); |
| 252 | |
| 253 | req.where = &where; |
| 254 | req.io_req = &io_req; |
| 255 | |
| 256 | /* |
| 257 | * Issue the synchronous I/O from a different thread |
| 258 | * to avoid generic_make_request recursion. |
| 259 | */ |
Andrew Morton | ca1cab3 | 2010-10-26 14:22:34 -0700 | [diff] [blame] | 260 | INIT_WORK_ONSTACK(&req.work, do_metadata); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 261 | queue_work(ps->metadata_wq, &req.work); |
Mikulas Patocka | 5ea330a | 2013-09-18 19:14:22 -0400 | [diff] [blame] | 262 | flush_workqueue(ps->metadata_wq); |
Chuansheng Liu | c1a6416 | 2014-01-07 16:56:18 +0800 | [diff] [blame] | 263 | destroy_work_on_stack(&req.work); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 264 | |
| 265 | return req.result; |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * Convert a metadata area index to a chunk index. |
| 270 | */ |
| 271 | static chunk_t area_location(struct pstore *ps, chunk_t area) |
| 272 | { |
Tomohiro Kusumi | 87c961c | 2010-08-12 04:13:59 +0100 | [diff] [blame] | 273 | return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 274 | } |
| 275 | |
Mikulas Patocka | e9c6a18 | 2013-10-16 03:17:47 +0100 | [diff] [blame] | 276 | static void skip_metadata(struct pstore *ps) |
| 277 | { |
| 278 | uint32_t stride = ps->exceptions_per_area + 1; |
| 279 | chunk_t next_free = ps->next_free; |
| 280 | if (sector_div(next_free, stride) == NUM_SNAPSHOT_HDR_CHUNKS) |
| 281 | ps->next_free++; |
| 282 | } |
| 283 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 284 | /* |
| 285 | * Read or write a metadata area. Remembering to skip the first |
| 286 | * chunk which holds the header. |
| 287 | */ |
| 288 | static int area_io(struct pstore *ps, int rw) |
| 289 | { |
| 290 | int r; |
| 291 | chunk_t chunk; |
| 292 | |
| 293 | chunk = area_location(ps, ps->current_area); |
| 294 | |
Mikulas Patocka | 02d2fd3 | 2009-09-04 20:40:37 +0100 | [diff] [blame] | 295 | r = chunk_io(ps, ps->area, chunk, rw, 0); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 296 | if (r) |
| 297 | return r; |
| 298 | |
| 299 | return 0; |
| 300 | } |
| 301 | |
| 302 | static void zero_memory_area(struct pstore *ps) |
| 303 | { |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 304 | memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 305 | } |
| 306 | |
| 307 | static int zero_disk_area(struct pstore *ps, chunk_t area) |
| 308 | { |
Mikulas Patocka | 02d2fd3 | 2009-09-04 20:40:37 +0100 | [diff] [blame] | 309 | return chunk_io(ps, ps->zero_area, area_location(ps, area), WRITE, 0); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 310 | } |
| 311 | |
| 312 | static int read_header(struct pstore *ps, int *new_snapshot) |
| 313 | { |
| 314 | int r; |
| 315 | struct disk_header *dh; |
Mikulas Patocka | df96eee | 2009-10-16 23:18:17 +0100 | [diff] [blame] | 316 | unsigned chunk_size; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 317 | int chunk_size_supplied = 1; |
Mikulas Patocka | ae0b744 | 2009-09-04 20:40:43 +0100 | [diff] [blame] | 318 | char *chunk_err; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 319 | |
| 320 | /* |
Mikulas Patocka | df96eee | 2009-10-16 23:18:17 +0100 | [diff] [blame] | 321 | * Use default chunk size (or logical_block_size, if larger) |
| 322 | * if none supplied |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 323 | */ |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 324 | if (!ps->store->chunk_size) { |
| 325 | ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, |
Mike Snitzer | fc56f6f | 2009-12-10 23:52:12 +0000 | [diff] [blame] | 326 | bdev_logical_block_size(dm_snap_cow(ps->store->snap)-> |
| 327 | bdev) >> 9); |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 328 | ps->store->chunk_mask = ps->store->chunk_size - 1; |
| 329 | ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 330 | chunk_size_supplied = 0; |
| 331 | } |
| 332 | |
Mikulas Patocka | bda8efe | 2011-05-29 13:03:09 +0100 | [diff] [blame] | 333 | ps->io_client = dm_io_client_create(); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 334 | if (IS_ERR(ps->io_client)) |
| 335 | return PTR_ERR(ps->io_client); |
| 336 | |
| 337 | r = alloc_area(ps); |
| 338 | if (r) |
| 339 | return r; |
| 340 | |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 341 | r = chunk_io(ps, ps->header_area, 0, READ, 1); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 342 | if (r) |
| 343 | goto bad; |
| 344 | |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 345 | dh = ps->header_area; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 346 | |
| 347 | if (le32_to_cpu(dh->magic) == 0) { |
| 348 | *new_snapshot = 1; |
| 349 | return 0; |
| 350 | } |
| 351 | |
| 352 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { |
| 353 | DMWARN("Invalid or corrupt snapshot"); |
| 354 | r = -ENXIO; |
| 355 | goto bad; |
| 356 | } |
| 357 | |
| 358 | *new_snapshot = 0; |
| 359 | ps->valid = le32_to_cpu(dh->valid); |
| 360 | ps->version = le32_to_cpu(dh->version); |
| 361 | chunk_size = le32_to_cpu(dh->chunk_size); |
| 362 | |
Mikulas Patocka | ae0b744 | 2009-09-04 20:40:43 +0100 | [diff] [blame] | 363 | if (ps->store->chunk_size == chunk_size) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 364 | return 0; |
| 365 | |
Mikulas Patocka | ae0b744 | 2009-09-04 20:40:43 +0100 | [diff] [blame] | 366 | if (chunk_size_supplied) |
Mikulas Patocka | df96eee | 2009-10-16 23:18:17 +0100 | [diff] [blame] | 367 | DMWARN("chunk size %u in device metadata overrides " |
| 368 | "table chunk size of %u.", |
| 369 | chunk_size, ps->store->chunk_size); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 370 | |
| 371 | /* We had a bogus chunk_size. Fix stuff up. */ |
| 372 | free_area(ps); |
| 373 | |
Mikulas Patocka | ae0b744 | 2009-09-04 20:40:43 +0100 | [diff] [blame] | 374 | r = dm_exception_store_set_chunk_size(ps->store, chunk_size, |
| 375 | &chunk_err); |
| 376 | if (r) { |
Mikulas Patocka | df96eee | 2009-10-16 23:18:17 +0100 | [diff] [blame] | 377 | DMERR("invalid on-disk chunk size %u: %s.", |
| 378 | chunk_size, chunk_err); |
Mikulas Patocka | ae0b744 | 2009-09-04 20:40:43 +0100 | [diff] [blame] | 379 | return r; |
| 380 | } |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 381 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 382 | r = alloc_area(ps); |
| 383 | return r; |
| 384 | |
| 385 | bad: |
| 386 | free_area(ps); |
| 387 | return r; |
| 388 | } |
| 389 | |
| 390 | static int write_header(struct pstore *ps) |
| 391 | { |
| 392 | struct disk_header *dh; |
| 393 | |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 394 | memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 395 | |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 396 | dh = ps->header_area; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 397 | dh->magic = cpu_to_le32(SNAP_MAGIC); |
| 398 | dh->valid = cpu_to_le32(ps->valid); |
| 399 | dh->version = cpu_to_le32(ps->version); |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 400 | dh->chunk_size = cpu_to_le32(ps->store->chunk_size); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 401 | |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 402 | return chunk_io(ps, ps->header_area, 0, WRITE, 1); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 403 | } |
| 404 | |
| 405 | /* |
| 406 | * Access functions for the disk exceptions, these do the endian conversions. |
| 407 | */ |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 408 | static struct disk_exception *get_exception(struct pstore *ps, void *ps_area, |
| 409 | uint32_t index) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 410 | { |
| 411 | BUG_ON(index >= ps->exceptions_per_area); |
| 412 | |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 413 | return ((struct disk_exception *) ps_area) + index; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 414 | } |
| 415 | |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 416 | static void read_exception(struct pstore *ps, void *ps_area, |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 417 | uint32_t index, struct core_exception *result) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 418 | { |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 419 | struct disk_exception *de = get_exception(ps, ps_area, index); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 420 | |
| 421 | /* copy it */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 422 | result->old_chunk = le64_to_cpu(de->old_chunk); |
| 423 | result->new_chunk = le64_to_cpu(de->new_chunk); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 424 | } |
| 425 | |
| 426 | static void write_exception(struct pstore *ps, |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 427 | uint32_t index, struct core_exception *e) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 428 | { |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 429 | struct disk_exception *de = get_exception(ps, ps->area, index); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 430 | |
| 431 | /* copy it */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 432 | de->old_chunk = cpu_to_le64(e->old_chunk); |
| 433 | de->new_chunk = cpu_to_le64(e->new_chunk); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 434 | } |
| 435 | |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 436 | static void clear_exception(struct pstore *ps, uint32_t index) |
| 437 | { |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 438 | struct disk_exception *de = get_exception(ps, ps->area, index); |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 439 | |
| 440 | /* clear it */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 441 | de->old_chunk = 0; |
| 442 | de->new_chunk = 0; |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 443 | } |
| 444 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 445 | /* |
| 446 | * Registers the exceptions that are present in the current area. |
| 447 | * 'full' is filled in to indicate if the area has been |
| 448 | * filled. |
| 449 | */ |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 450 | static int insert_exceptions(struct pstore *ps, void *ps_area, |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 451 | int (*callback)(void *callback_context, |
| 452 | chunk_t old, chunk_t new), |
| 453 | void *callback_context, |
| 454 | int *full) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 455 | { |
| 456 | int r; |
| 457 | unsigned int i; |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 458 | struct core_exception e; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 459 | |
| 460 | /* presume the area is full */ |
| 461 | *full = 1; |
| 462 | |
| 463 | for (i = 0; i < ps->exceptions_per_area; i++) { |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 464 | read_exception(ps, ps_area, i, &e); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 465 | |
| 466 | /* |
| 467 | * If the new_chunk is pointing at the start of |
| 468 | * the COW device, where the first metadata area |
| 469 | * is we know that we've hit the end of the |
| 470 | * exceptions. Therefore the area is not full. |
| 471 | */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 472 | if (e.new_chunk == 0LL) { |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 473 | ps->current_committed = i; |
| 474 | *full = 0; |
| 475 | break; |
| 476 | } |
| 477 | |
| 478 | /* |
| 479 | * Keep track of the start of the free chunks. |
| 480 | */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 481 | if (ps->next_free <= e.new_chunk) |
| 482 | ps->next_free = e.new_chunk + 1; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 483 | |
| 484 | /* |
| 485 | * Otherwise we add the exception to the snapshot. |
| 486 | */ |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 487 | r = callback(callback_context, e.old_chunk, e.new_chunk); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 488 | if (r) |
| 489 | return r; |
| 490 | } |
| 491 | |
| 492 | return 0; |
| 493 | } |
| 494 | |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 495 | static int read_exceptions(struct pstore *ps, |
| 496 | int (*callback)(void *callback_context, chunk_t old, |
| 497 | chunk_t new), |
| 498 | void *callback_context) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 499 | { |
| 500 | int r, full = 1; |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 501 | struct dm_bufio_client *client; |
Mikulas Patocka | 55b082e | 2014-01-13 19:13:05 -0500 | [diff] [blame] | 502 | chunk_t prefetch_area = 0; |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 503 | |
| 504 | client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev, |
| 505 | ps->store->chunk_size << SECTOR_SHIFT, |
| 506 | 1, 0, NULL, NULL); |
| 507 | |
| 508 | if (IS_ERR(client)) |
| 509 | return PTR_ERR(client); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 510 | |
| 511 | /* |
Mikulas Patocka | 55b082e | 2014-01-13 19:13:05 -0500 | [diff] [blame] | 512 | * Setup for one current buffer + desired readahead buffers. |
| 513 | */ |
| 514 | dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS); |
| 515 | |
| 516 | /* |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 517 | * Keeping reading chunks and inserting exceptions until |
| 518 | * we find a partially full area. |
| 519 | */ |
| 520 | for (ps->current_area = 0; full; ps->current_area++) { |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 521 | struct dm_buffer *bp; |
| 522 | void *area; |
Mikulas Patocka | 55b082e | 2014-01-13 19:13:05 -0500 | [diff] [blame] | 523 | chunk_t chunk; |
| 524 | |
| 525 | if (unlikely(prefetch_area < ps->current_area)) |
| 526 | prefetch_area = ps->current_area; |
| 527 | |
| 528 | if (DM_PREFETCH_CHUNKS) do { |
| 529 | chunk_t pf_chunk = area_location(ps, prefetch_area); |
| 530 | if (unlikely(pf_chunk >= dm_bufio_get_device_size(client))) |
| 531 | break; |
| 532 | dm_bufio_prefetch(client, pf_chunk, 1); |
| 533 | prefetch_area++; |
| 534 | if (unlikely(!prefetch_area)) |
| 535 | break; |
| 536 | } while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS); |
| 537 | |
| 538 | chunk = area_location(ps, ps->current_area); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 539 | |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 540 | area = dm_bufio_read(client, chunk, &bp); |
| 541 | if (unlikely(IS_ERR(area))) { |
| 542 | r = PTR_ERR(area); |
| 543 | goto ret_destroy_bufio; |
| 544 | } |
| 545 | |
| 546 | r = insert_exceptions(ps, area, callback, callback_context, |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 547 | &full); |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 548 | |
| 549 | dm_bufio_release(bp); |
| 550 | |
| 551 | dm_bufio_forget(client, chunk); |
| 552 | |
| 553 | if (unlikely(r)) |
| 554 | goto ret_destroy_bufio; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 555 | } |
| 556 | |
| 557 | ps->current_area--; |
| 558 | |
Mikulas Patocka | e9c6a18 | 2013-10-16 03:17:47 +0100 | [diff] [blame] | 559 | skip_metadata(ps); |
| 560 | |
Mikulas Patocka | 55494bf | 2014-01-13 19:12:36 -0500 | [diff] [blame] | 561 | r = 0; |
| 562 | |
| 563 | ret_destroy_bufio: |
| 564 | dm_bufio_client_destroy(client); |
| 565 | |
| 566 | return r; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 567 | } |
| 568 | |
| 569 | static struct pstore *get_info(struct dm_exception_store *store) |
| 570 | { |
| 571 | return (struct pstore *) store->context; |
| 572 | } |
| 573 | |
Mike Snitzer | 985903b | 2009-12-10 23:52:11 +0000 | [diff] [blame] | 574 | static void persistent_usage(struct dm_exception_store *store, |
| 575 | sector_t *total_sectors, |
| 576 | sector_t *sectors_allocated, |
| 577 | sector_t *metadata_sectors) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 578 | { |
Mike Snitzer | 985903b | 2009-12-10 23:52:11 +0000 | [diff] [blame] | 579 | struct pstore *ps = get_info(store); |
| 580 | |
| 581 | *sectors_allocated = ps->next_free * store->chunk_size; |
Mike Snitzer | fc56f6f | 2009-12-10 23:52:12 +0000 | [diff] [blame] | 582 | *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev); |
Mike Snitzer | 985903b | 2009-12-10 23:52:11 +0000 | [diff] [blame] | 583 | |
| 584 | /* |
| 585 | * First chunk is the fixed header. |
| 586 | * Then there are (ps->current_area + 1) metadata chunks, each one |
| 587 | * separated from the next by ps->exceptions_per_area data chunks. |
| 588 | */ |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 589 | *metadata_sectors = (ps->current_area + 1 + NUM_SNAPSHOT_HDR_CHUNKS) * |
| 590 | store->chunk_size; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 591 | } |
| 592 | |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 593 | static void persistent_dtr(struct dm_exception_store *store) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 594 | { |
| 595 | struct pstore *ps = get_info(store); |
| 596 | |
| 597 | destroy_workqueue(ps->metadata_wq); |
Jonathan Brassow | a32079c | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 598 | |
| 599 | /* Created in read_header */ |
| 600 | if (ps->io_client) |
| 601 | dm_io_client_destroy(ps->io_client); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 602 | free_area(ps); |
Jonathan Brassow | a32079c | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 603 | |
| 604 | /* Allocated in persistent_read_metadata */ |
| 605 | if (ps->callbacks) |
| 606 | vfree(ps->callbacks); |
| 607 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 608 | kfree(ps); |
| 609 | } |
| 610 | |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 611 | static int persistent_read_metadata(struct dm_exception_store *store, |
| 612 | int (*callback)(void *callback_context, |
| 613 | chunk_t old, chunk_t new), |
| 614 | void *callback_context) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 615 | { |
| 616 | int r, uninitialized_var(new_snapshot); |
| 617 | struct pstore *ps = get_info(store); |
| 618 | |
| 619 | /* |
| 620 | * Read the snapshot header. |
| 621 | */ |
| 622 | r = read_header(ps, &new_snapshot); |
| 623 | if (r) |
| 624 | return r; |
| 625 | |
| 626 | /* |
| 627 | * Now we know correct chunk_size, complete the initialisation. |
| 628 | */ |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 629 | ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) / |
| 630 | sizeof(struct disk_exception); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 631 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, |
Jonathan Brassow | a2d2b03 | 2011-08-02 12:32:03 +0100 | [diff] [blame] | 632 | sizeof(*ps->callbacks)); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 633 | if (!ps->callbacks) |
| 634 | return -ENOMEM; |
| 635 | |
| 636 | /* |
| 637 | * Do we need to setup a new snapshot ? |
| 638 | */ |
| 639 | if (new_snapshot) { |
| 640 | r = write_header(ps); |
| 641 | if (r) { |
| 642 | DMWARN("write_header failed"); |
| 643 | return r; |
| 644 | } |
| 645 | |
| 646 | ps->current_area = 0; |
| 647 | zero_memory_area(ps); |
| 648 | r = zero_disk_area(ps, 0); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 649 | if (r) |
Jon Brassow | f5acc83 | 2009-12-10 23:52:07 +0000 | [diff] [blame] | 650 | DMWARN("zero_disk_area(0) failed"); |
| 651 | return r; |
| 652 | } |
| 653 | /* |
| 654 | * Sanity checks. |
| 655 | */ |
| 656 | if (ps->version != SNAPSHOT_DISK_VERSION) { |
| 657 | DMWARN("unable to handle snapshot disk version %d", |
| 658 | ps->version); |
| 659 | return -EINVAL; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 660 | } |
| 661 | |
Jon Brassow | f5acc83 | 2009-12-10 23:52:07 +0000 | [diff] [blame] | 662 | /* |
| 663 | * Metadata are valid, but snapshot is invalidated |
| 664 | */ |
| 665 | if (!ps->valid) |
| 666 | return 1; |
| 667 | |
| 668 | /* |
| 669 | * Read the metadata. |
| 670 | */ |
| 671 | r = read_exceptions(ps, callback, callback_context); |
| 672 | |
| 673 | return r; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 674 | } |
| 675 | |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 676 | static int persistent_prepare_exception(struct dm_exception_store *store, |
Jon Brassow | 1d4989c | 2009-12-10 23:52:10 +0000 | [diff] [blame] | 677 | struct dm_exception *e) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 678 | { |
| 679 | struct pstore *ps = get_info(store); |
Mike Snitzer | fc56f6f | 2009-12-10 23:52:12 +0000 | [diff] [blame] | 680 | sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 681 | |
| 682 | /* Is there enough room ? */ |
Jonathan Brassow | d021684 | 2009-04-02 19:55:32 +0100 | [diff] [blame] | 683 | if (size < ((ps->next_free + 1) * store->chunk_size)) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 684 | return -ENOSPC; |
| 685 | |
| 686 | e->new_chunk = ps->next_free; |
| 687 | |
| 688 | /* |
| 689 | * Move onto the next free pending, making sure to take |
| 690 | * into account the location of the metadata chunks. |
| 691 | */ |
Mikulas Patocka | e9c6a18 | 2013-10-16 03:17:47 +0100 | [diff] [blame] | 692 | ps->next_free++; |
| 693 | skip_metadata(ps); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 694 | |
| 695 | atomic_inc(&ps->pending_count); |
| 696 | return 0; |
| 697 | } |
| 698 | |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 699 | static void persistent_commit_exception(struct dm_exception_store *store, |
Jon Brassow | 1d4989c | 2009-12-10 23:52:10 +0000 | [diff] [blame] | 700 | struct dm_exception *e, |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 701 | void (*callback) (void *, int success), |
| 702 | void *callback_context) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 703 | { |
| 704 | unsigned int i; |
| 705 | struct pstore *ps = get_info(store); |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 706 | struct core_exception ce; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 707 | struct commit_callback *cb; |
| 708 | |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 709 | ce.old_chunk = e->old_chunk; |
| 710 | ce.new_chunk = e->new_chunk; |
| 711 | write_exception(ps, ps->current_committed++, &ce); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 712 | |
| 713 | /* |
| 714 | * Add the callback to the back of the array. This code |
| 715 | * is the only place where the callback array is |
| 716 | * manipulated, and we know that it will never be called |
| 717 | * multiple times concurrently. |
| 718 | */ |
| 719 | cb = ps->callbacks + ps->callback_count++; |
| 720 | cb->callback = callback; |
| 721 | cb->context = callback_context; |
| 722 | |
| 723 | /* |
| 724 | * If there are exceptions in flight and we have not yet |
| 725 | * filled this metadata area there's nothing more to do. |
| 726 | */ |
| 727 | if (!atomic_dec_and_test(&ps->pending_count) && |
| 728 | (ps->current_committed != ps->exceptions_per_area)) |
| 729 | return; |
| 730 | |
| 731 | /* |
| 732 | * If we completely filled the current area, then wipe the next one. |
| 733 | */ |
| 734 | if ((ps->current_committed == ps->exceptions_per_area) && |
Jonathan Brassow | a2d2b03 | 2011-08-02 12:32:03 +0100 | [diff] [blame] | 735 | zero_disk_area(ps, ps->current_area + 1)) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 736 | ps->valid = 0; |
| 737 | |
| 738 | /* |
| 739 | * Commit exceptions to disk. |
| 740 | */ |
Tejun Heo | d87f4c1 | 2010-09-03 11:56:19 +0200 | [diff] [blame] | 741 | if (ps->valid && area_io(ps, WRITE_FLUSH_FUA)) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 742 | ps->valid = 0; |
| 743 | |
| 744 | /* |
| 745 | * Advance to the next area if this one is full. |
| 746 | */ |
| 747 | if (ps->current_committed == ps->exceptions_per_area) { |
| 748 | ps->current_committed = 0; |
| 749 | ps->current_area++; |
| 750 | zero_memory_area(ps); |
| 751 | } |
| 752 | |
| 753 | for (i = 0; i < ps->callback_count; i++) { |
| 754 | cb = ps->callbacks + i; |
| 755 | cb->callback(cb->context, ps->valid); |
| 756 | } |
| 757 | |
| 758 | ps->callback_count = 0; |
| 759 | } |
| 760 | |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 761 | static int persistent_prepare_merge(struct dm_exception_store *store, |
| 762 | chunk_t *last_old_chunk, |
| 763 | chunk_t *last_new_chunk) |
| 764 | { |
| 765 | struct pstore *ps = get_info(store); |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 766 | struct core_exception ce; |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 767 | int nr_consecutive; |
| 768 | int r; |
| 769 | |
| 770 | /* |
| 771 | * When current area is empty, move back to preceding area. |
| 772 | */ |
| 773 | if (!ps->current_committed) { |
| 774 | /* |
| 775 | * Have we finished? |
| 776 | */ |
| 777 | if (!ps->current_area) |
| 778 | return 0; |
| 779 | |
| 780 | ps->current_area--; |
| 781 | r = area_io(ps, READ); |
| 782 | if (r < 0) |
| 783 | return r; |
| 784 | ps->current_committed = ps->exceptions_per_area; |
| 785 | } |
| 786 | |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 787 | read_exception(ps, ps->area, ps->current_committed - 1, &ce); |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 788 | *last_old_chunk = ce.old_chunk; |
| 789 | *last_new_chunk = ce.new_chunk; |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 790 | |
| 791 | /* |
| 792 | * Find number of consecutive chunks within the current area, |
| 793 | * working backwards. |
| 794 | */ |
| 795 | for (nr_consecutive = 1; nr_consecutive < ps->current_committed; |
| 796 | nr_consecutive++) { |
Mikulas Patocka | 2cadabd | 2014-01-13 19:14:04 -0500 | [diff] [blame] | 797 | read_exception(ps, ps->area, |
| 798 | ps->current_committed - 1 - nr_consecutive, &ce); |
Alasdair G Kergon | 283a832 | 2011-08-02 12:32:01 +0100 | [diff] [blame] | 799 | if (ce.old_chunk != *last_old_chunk - nr_consecutive || |
| 800 | ce.new_chunk != *last_new_chunk - nr_consecutive) |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 801 | break; |
| 802 | } |
| 803 | |
| 804 | return nr_consecutive; |
| 805 | } |
| 806 | |
| 807 | static int persistent_commit_merge(struct dm_exception_store *store, |
| 808 | int nr_merged) |
| 809 | { |
| 810 | int r, i; |
| 811 | struct pstore *ps = get_info(store); |
| 812 | |
| 813 | BUG_ON(nr_merged > ps->current_committed); |
| 814 | |
| 815 | for (i = 0; i < nr_merged; i++) |
| 816 | clear_exception(ps, ps->current_committed - 1 - i); |
| 817 | |
Mikulas Patocka | 762a80d | 2011-08-02 12:32:00 +0100 | [diff] [blame] | 818 | r = area_io(ps, WRITE_FLUSH_FUA); |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 819 | if (r < 0) |
| 820 | return r; |
| 821 | |
| 822 | ps->current_committed -= nr_merged; |
| 823 | |
| 824 | /* |
| 825 | * At this stage, only persistent_usage() uses ps->next_free, so |
| 826 | * we make no attempt to keep ps->next_free strictly accurate |
| 827 | * as exceptions may have been committed out-of-order originally. |
| 828 | * Once a snapshot has become merging, we set it to the value it |
| 829 | * would have held had all the exceptions been committed in order. |
| 830 | * |
| 831 | * ps->current_area does not get reduced by prepare_merge() until |
| 832 | * after commit_merge() has removed the nr_merged previous exceptions. |
| 833 | */ |
Tomohiro Kusumi | 87c961c | 2010-08-12 04:13:59 +0100 | [diff] [blame] | 834 | ps->next_free = area_location(ps, ps->current_area) + |
| 835 | ps->current_committed + 1; |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 836 | |
| 837 | return 0; |
| 838 | } |
| 839 | |
Jonathan Brassow | a159c1a | 2009-01-06 03:05:19 +0000 | [diff] [blame] | 840 | static void persistent_drop_snapshot(struct dm_exception_store *store) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 841 | { |
| 842 | struct pstore *ps = get_info(store); |
| 843 | |
| 844 | ps->valid = 0; |
| 845 | if (write_header(ps)) |
| 846 | DMWARN("write header failed"); |
| 847 | } |
| 848 | |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 849 | static int persistent_ctr(struct dm_exception_store *store, |
| 850 | unsigned argc, char **argv) |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 851 | { |
| 852 | struct pstore *ps; |
| 853 | |
| 854 | /* allocate the pstore */ |
Jonathan Brassow | a32079c | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 855 | ps = kzalloc(sizeof(*ps), GFP_KERNEL); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 856 | if (!ps) |
| 857 | return -ENOMEM; |
| 858 | |
Jonathan Brassow | 71fab00 | 2009-04-02 19:55:33 +0100 | [diff] [blame] | 859 | ps->store = store; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 860 | ps->valid = 1; |
| 861 | ps->version = SNAPSHOT_DISK_VERSION; |
| 862 | ps->area = NULL; |
Mikulas Patocka | 61578dc | 2009-09-04 20:40:39 +0100 | [diff] [blame] | 863 | ps->zero_area = NULL; |
| 864 | ps->header_area = NULL; |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 865 | ps->next_free = NUM_SNAPSHOT_HDR_CHUNKS + 1; /* header and 1st area */ |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 866 | ps->current_committed = 0; |
| 867 | |
| 868 | ps->callback_count = 0; |
| 869 | atomic_set(&ps->pending_count, 0); |
| 870 | ps->callbacks = NULL; |
| 871 | |
Tejun Heo | 239c8dd | 2011-01-13 19:59:59 +0000 | [diff] [blame] | 872 | ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 873 | if (!ps->metadata_wq) { |
| 874 | kfree(ps); |
| 875 | DMERR("couldn't start header metadata update thread"); |
| 876 | return -ENOMEM; |
| 877 | } |
| 878 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 879 | store->context = ps; |
| 880 | |
| 881 | return 0; |
| 882 | } |
| 883 | |
Jonathan Brassow | 1e302a9 | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 884 | static unsigned persistent_status(struct dm_exception_store *store, |
| 885 | status_type_t status, char *result, |
| 886 | unsigned maxlen) |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 887 | { |
Jonathan Brassow | 1e302a9 | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 888 | unsigned sz = 0; |
| 889 | |
| 890 | switch (status) { |
| 891 | case STATUSTYPE_INFO: |
| 892 | break; |
| 893 | case STATUSTYPE_TABLE: |
Mike Snitzer | fc56f6f | 2009-12-10 23:52:12 +0000 | [diff] [blame] | 894 | DMEMIT(" P %llu", (unsigned long long)store->chunk_size); |
Jonathan Brassow | 1e302a9 | 2009-04-02 19:55:35 +0100 | [diff] [blame] | 895 | } |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 896 | |
| 897 | return sz; |
| 898 | } |
| 899 | |
| 900 | static struct dm_exception_store_type _persistent_type = { |
| 901 | .name = "persistent", |
| 902 | .module = THIS_MODULE, |
| 903 | .ctr = persistent_ctr, |
| 904 | .dtr = persistent_dtr, |
| 905 | .read_metadata = persistent_read_metadata, |
| 906 | .prepare_exception = persistent_prepare_exception, |
| 907 | .commit_exception = persistent_commit_exception, |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 908 | .prepare_merge = persistent_prepare_merge, |
| 909 | .commit_merge = persistent_commit_merge, |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 910 | .drop_snapshot = persistent_drop_snapshot, |
Mike Snitzer | 985903b | 2009-12-10 23:52:11 +0000 | [diff] [blame] | 911 | .usage = persistent_usage, |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 912 | .status = persistent_status, |
| 913 | }; |
| 914 | |
| 915 | static struct dm_exception_store_type _persistent_compat_type = { |
| 916 | .name = "P", |
| 917 | .module = THIS_MODULE, |
| 918 | .ctr = persistent_ctr, |
| 919 | .dtr = persistent_dtr, |
| 920 | .read_metadata = persistent_read_metadata, |
| 921 | .prepare_exception = persistent_prepare_exception, |
| 922 | .commit_exception = persistent_commit_exception, |
Mikulas Patocka | 4454a62 | 2009-12-10 23:52:29 +0000 | [diff] [blame] | 923 | .prepare_merge = persistent_prepare_merge, |
| 924 | .commit_merge = persistent_commit_merge, |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 925 | .drop_snapshot = persistent_drop_snapshot, |
Mike Snitzer | 985903b | 2009-12-10 23:52:11 +0000 | [diff] [blame] | 926 | .usage = persistent_usage, |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 927 | .status = persistent_status, |
| 928 | }; |
| 929 | |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 930 | int dm_persistent_snapshot_init(void) |
| 931 | { |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 932 | int r; |
| 933 | |
| 934 | r = dm_exception_store_type_register(&_persistent_type); |
| 935 | if (r) { |
| 936 | DMERR("Unable to register persistent exception store type"); |
| 937 | return r; |
| 938 | } |
| 939 | |
| 940 | r = dm_exception_store_type_register(&_persistent_compat_type); |
| 941 | if (r) { |
| 942 | DMERR("Unable to register old-style persistent exception " |
| 943 | "store type"); |
| 944 | dm_exception_store_type_unregister(&_persistent_type); |
| 945 | return r; |
| 946 | } |
| 947 | |
| 948 | return r; |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 949 | } |
| 950 | |
| 951 | void dm_persistent_snapshot_exit(void) |
| 952 | { |
Jonathan Brassow | 493df71 | 2009-04-02 19:55:31 +0100 | [diff] [blame] | 953 | dm_exception_store_type_unregister(&_persistent_type); |
| 954 | dm_exception_store_type_unregister(&_persistent_compat_type); |
Alasdair G Kergon | 4db6bfe | 2009-01-06 03:05:17 +0000 | [diff] [blame] | 955 | } |