| 1 | /* |
| 2 | linear.c : Multiple Devices driver for Linux |
| 3 | Copyright (C) 1994-96 Marc ZYNGIER |
| 4 | <zyngier@ufr-info-p7.ibp.fr> or |
| 5 | <maz@gloups.fdn.fr> |
| 6 | |
| 7 | Linear mode management functions. |
| 8 | |
| 9 | This program is free software; you can redistribute it and/or modify |
| 10 | it under the terms of the GNU General Public License as published by |
| 11 | the Free Software Foundation; either version 2, or (at your option) |
| 12 | any later version. |
| 13 | |
| 14 | You should have received a copy of the GNU General Public License |
| 15 | (for example /usr/src/linux/COPYING); if not, write to the Free |
| 16 | Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 17 | */ |
| 18 | |
| 19 | #include <linux/blkdev.h> |
| 20 | #include <linux/raid/md_u.h> |
| 21 | #include <linux/seq_file.h> |
| 22 | #include "md.h" |
| 23 | #include "linear.h" |
| 24 | |
| 25 | /* |
| 26 | * find which device holds a particular offset |
| 27 | */ |
| 28 | static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector) |
| 29 | { |
| 30 | int lo, mid, hi; |
| 31 | linear_conf_t *conf; |
| 32 | |
| 33 | lo = 0; |
| 34 | hi = mddev->raid_disks - 1; |
| 35 | conf = rcu_dereference(mddev->private); |
| 36 | |
| 37 | /* |
| 38 | * Binary Search |
| 39 | */ |
| 40 | |
| 41 | while (hi > lo) { |
| 42 | |
| 43 | mid = (hi + lo) / 2; |
| 44 | if (sector < conf->disks[mid].end_sector) |
| 45 | hi = mid; |
| 46 | else |
| 47 | lo = mid + 1; |
| 48 | } |
| 49 | |
| 50 | return conf->disks + lo; |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * linear_mergeable_bvec -- tell bio layer if two requests can be merged |
| 55 | * @q: request queue |
| 56 | * @bvm: properties of new bio |
| 57 | * @biovec: the request that could be merged to it. |
| 58 | * |
| 59 | * Return amount of bytes we can take at this offset |
| 60 | */ |
| 61 | static int linear_mergeable_bvec(struct request_queue *q, |
| 62 | struct bvec_merge_data *bvm, |
| 63 | struct bio_vec *biovec) |
| 64 | { |
| 65 | mddev_t *mddev = q->queuedata; |
| 66 | dev_info_t *dev0; |
| 67 | unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9; |
| 68 | sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); |
| 69 | |
| 70 | rcu_read_lock(); |
| 71 | dev0 = which_dev(mddev, sector); |
| 72 | maxsectors = dev0->end_sector - sector; |
| 73 | rcu_read_unlock(); |
| 74 | |
| 75 | if (maxsectors < bio_sectors) |
| 76 | maxsectors = 0; |
| 77 | else |
| 78 | maxsectors -= bio_sectors; |
| 79 | |
| 80 | if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0) |
| 81 | return biovec->bv_len; |
| 82 | /* The bytes available at this offset could be really big, |
| 83 | * so we cap at 2^31 to avoid overflow */ |
| 84 | if (maxsectors > (1 << (31-9))) |
| 85 | return 1<<31; |
| 86 | return maxsectors << 9; |
| 87 | } |
| 88 | |
| 89 | static void linear_unplug(struct request_queue *q) |
| 90 | { |
| 91 | mddev_t *mddev = q->queuedata; |
| 92 | linear_conf_t *conf; |
| 93 | int i; |
| 94 | |
| 95 | rcu_read_lock(); |
| 96 | conf = rcu_dereference(mddev->private); |
| 97 | |
| 98 | for (i=0; i < mddev->raid_disks; i++) { |
| 99 | struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev); |
| 100 | blk_unplug(r_queue); |
| 101 | } |
| 102 | rcu_read_unlock(); |
| 103 | } |
| 104 | |
| 105 | static int linear_congested(void *data, int bits) |
| 106 | { |
| 107 | mddev_t *mddev = data; |
| 108 | linear_conf_t *conf; |
| 109 | int i, ret = 0; |
| 110 | |
| 111 | rcu_read_lock(); |
| 112 | conf = rcu_dereference(mddev->private); |
| 113 | |
| 114 | for (i = 0; i < mddev->raid_disks && !ret ; i++) { |
| 115 | struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev); |
| 116 | ret |= bdi_congested(&q->backing_dev_info, bits); |
| 117 | } |
| 118 | |
| 119 | rcu_read_unlock(); |
| 120 | return ret; |
| 121 | } |
| 122 | |
| 123 | static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks) |
| 124 | { |
| 125 | linear_conf_t *conf; |
| 126 | sector_t array_sectors; |
| 127 | |
| 128 | rcu_read_lock(); |
| 129 | conf = rcu_dereference(mddev->private); |
| 130 | WARN_ONCE(sectors || raid_disks, |
| 131 | "%s does not support generic reshape\n", __func__); |
| 132 | array_sectors = conf->array_sectors; |
| 133 | rcu_read_unlock(); |
| 134 | |
| 135 | return array_sectors; |
| 136 | } |
| 137 | |
| 138 | static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks) |
| 139 | { |
| 140 | linear_conf_t *conf; |
| 141 | mdk_rdev_t *rdev; |
| 142 | int i, cnt; |
| 143 | |
| 144 | conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t), |
| 145 | GFP_KERNEL); |
| 146 | if (!conf) |
| 147 | return NULL; |
| 148 | |
| 149 | cnt = 0; |
| 150 | conf->array_sectors = 0; |
| 151 | |
| 152 | list_for_each_entry(rdev, &mddev->disks, same_set) { |
| 153 | int j = rdev->raid_disk; |
| 154 | dev_info_t *disk = conf->disks + j; |
| 155 | sector_t sectors; |
| 156 | |
| 157 | if (j < 0 || j >= raid_disks || disk->rdev) { |
| 158 | printk("linear: disk numbering problem. Aborting!\n"); |
| 159 | goto out; |
| 160 | } |
| 161 | |
| 162 | disk->rdev = rdev; |
| 163 | if (mddev->chunk_sectors) { |
| 164 | sectors = rdev->sectors; |
| 165 | sector_div(sectors, mddev->chunk_sectors); |
| 166 | rdev->sectors = sectors * mddev->chunk_sectors; |
| 167 | } |
| 168 | |
| 169 | blk_queue_stack_limits(mddev->queue, |
| 170 | rdev->bdev->bd_disk->queue); |
| 171 | /* as we don't honour merge_bvec_fn, we must never risk |
| 172 | * violating it, so limit ->max_sector to one PAGE, as |
| 173 | * a one page request is never in violation. |
| 174 | */ |
| 175 | if (rdev->bdev->bd_disk->queue->merge_bvec_fn && |
| 176 | queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) |
| 177 | blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); |
| 178 | |
| 179 | conf->array_sectors += rdev->sectors; |
| 180 | cnt++; |
| 181 | |
| 182 | } |
| 183 | if (cnt != raid_disks) { |
| 184 | printk("linear: not enough drives present. Aborting!\n"); |
| 185 | goto out; |
| 186 | } |
| 187 | |
| 188 | /* |
| 189 | * Here we calculate the device offsets. |
| 190 | */ |
| 191 | conf->disks[0].end_sector = conf->disks[0].rdev->sectors; |
| 192 | |
| 193 | for (i = 1; i < raid_disks; i++) |
| 194 | conf->disks[i].end_sector = |
| 195 | conf->disks[i-1].end_sector + |
| 196 | conf->disks[i].rdev->sectors; |
| 197 | |
| 198 | return conf; |
| 199 | |
| 200 | out: |
| 201 | kfree(conf); |
| 202 | return NULL; |
| 203 | } |
| 204 | |
| 205 | static int linear_run (mddev_t *mddev) |
| 206 | { |
| 207 | linear_conf_t *conf; |
| 208 | |
| 209 | if (md_check_no_bitmap(mddev)) |
| 210 | return -EINVAL; |
| 211 | mddev->queue->queue_lock = &mddev->queue->__queue_lock; |
| 212 | conf = linear_conf(mddev, mddev->raid_disks); |
| 213 | |
| 214 | if (!conf) |
| 215 | return 1; |
| 216 | mddev->private = conf; |
| 217 | md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); |
| 218 | |
| 219 | blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec); |
| 220 | mddev->queue->unplug_fn = linear_unplug; |
| 221 | mddev->queue->backing_dev_info.congested_fn = linear_congested; |
| 222 | mddev->queue->backing_dev_info.congested_data = mddev; |
| 223 | return 0; |
| 224 | } |
| 225 | |
| 226 | static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev) |
| 227 | { |
| 228 | /* Adding a drive to a linear array allows the array to grow. |
| 229 | * It is permitted if the new drive has a matching superblock |
| 230 | * already on it, with raid_disk equal to raid_disks. |
| 231 | * It is achieved by creating a new linear_private_data structure |
| 232 | * and swapping it in in-place of the current one. |
| 233 | * The current one is never freed until the array is stopped. |
| 234 | * This avoids races. |
| 235 | */ |
| 236 | linear_conf_t *newconf; |
| 237 | |
| 238 | if (rdev->saved_raid_disk != mddev->raid_disks) |
| 239 | return -EINVAL; |
| 240 | |
| 241 | rdev->raid_disk = rdev->saved_raid_disk; |
| 242 | |
| 243 | newconf = linear_conf(mddev,mddev->raid_disks+1); |
| 244 | |
| 245 | if (!newconf) |
| 246 | return -ENOMEM; |
| 247 | |
| 248 | newconf->prev = mddev->private; |
| 249 | mddev->raid_disks++; |
| 250 | rcu_assign_pointer(mddev->private, newconf); |
| 251 | md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); |
| 252 | set_capacity(mddev->gendisk, mddev->array_sectors); |
| 253 | return 0; |
| 254 | } |
| 255 | |
| 256 | static int linear_stop (mddev_t *mddev) |
| 257 | { |
| 258 | linear_conf_t *conf = mddev->private; |
| 259 | |
| 260 | /* |
| 261 | * We do not require rcu protection here since |
| 262 | * we hold reconfig_mutex for both linear_add and |
| 263 | * linear_stop, so they cannot race. |
| 264 | */ |
| 265 | |
| 266 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ |
| 267 | do { |
| 268 | linear_conf_t *t = conf->prev; |
| 269 | kfree(conf); |
| 270 | conf = t; |
| 271 | } while (conf); |
| 272 | |
| 273 | return 0; |
| 274 | } |
| 275 | |
| 276 | static int linear_make_request (struct request_queue *q, struct bio *bio) |
| 277 | { |
| 278 | const int rw = bio_data_dir(bio); |
| 279 | mddev_t *mddev = q->queuedata; |
| 280 | dev_info_t *tmp_dev; |
| 281 | sector_t start_sector; |
| 282 | int cpu; |
| 283 | |
| 284 | if (unlikely(bio_barrier(bio))) { |
| 285 | bio_endio(bio, -EOPNOTSUPP); |
| 286 | return 0; |
| 287 | } |
| 288 | |
| 289 | cpu = part_stat_lock(); |
| 290 | part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); |
| 291 | part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], |
| 292 | bio_sectors(bio)); |
| 293 | part_stat_unlock(); |
| 294 | |
| 295 | rcu_read_lock(); |
| 296 | tmp_dev = which_dev(mddev, bio->bi_sector); |
| 297 | start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors; |
| 298 | |
| 299 | |
| 300 | if (unlikely(bio->bi_sector >= (tmp_dev->end_sector) |
| 301 | || (bio->bi_sector < start_sector))) { |
| 302 | char b[BDEVNAME_SIZE]; |
| 303 | |
| 304 | printk("linear_make_request: Sector %llu out of bounds on " |
| 305 | "dev %s: %llu sectors, offset %llu\n", |
| 306 | (unsigned long long)bio->bi_sector, |
| 307 | bdevname(tmp_dev->rdev->bdev, b), |
| 308 | (unsigned long long)tmp_dev->rdev->sectors, |
| 309 | (unsigned long long)start_sector); |
| 310 | rcu_read_unlock(); |
| 311 | bio_io_error(bio); |
| 312 | return 0; |
| 313 | } |
| 314 | if (unlikely(bio->bi_sector + (bio->bi_size >> 9) > |
| 315 | tmp_dev->end_sector)) { |
| 316 | /* This bio crosses a device boundary, so we have to |
| 317 | * split it. |
| 318 | */ |
| 319 | struct bio_pair *bp; |
| 320 | sector_t end_sector = tmp_dev->end_sector; |
| 321 | |
| 322 | rcu_read_unlock(); |
| 323 | |
| 324 | bp = bio_split(bio, end_sector - bio->bi_sector); |
| 325 | |
| 326 | if (linear_make_request(q, &bp->bio1)) |
| 327 | generic_make_request(&bp->bio1); |
| 328 | if (linear_make_request(q, &bp->bio2)) |
| 329 | generic_make_request(&bp->bio2); |
| 330 | bio_pair_release(bp); |
| 331 | return 0; |
| 332 | } |
| 333 | |
| 334 | bio->bi_bdev = tmp_dev->rdev->bdev; |
| 335 | bio->bi_sector = bio->bi_sector - start_sector |
| 336 | + tmp_dev->rdev->data_offset; |
| 337 | rcu_read_unlock(); |
| 338 | |
| 339 | return 1; |
| 340 | } |
| 341 | |
| 342 | static void linear_status (struct seq_file *seq, mddev_t *mddev) |
| 343 | { |
| 344 | |
| 345 | seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2); |
| 346 | } |
| 347 | |
| 348 | |
| 349 | static struct mdk_personality linear_personality = |
| 350 | { |
| 351 | .name = "linear", |
| 352 | .level = LEVEL_LINEAR, |
| 353 | .owner = THIS_MODULE, |
| 354 | .make_request = linear_make_request, |
| 355 | .run = linear_run, |
| 356 | .stop = linear_stop, |
| 357 | .status = linear_status, |
| 358 | .hot_add_disk = linear_add, |
| 359 | .size = linear_size, |
| 360 | }; |
| 361 | |
| 362 | static int __init linear_init (void) |
| 363 | { |
| 364 | return register_md_personality (&linear_personality); |
| 365 | } |
| 366 | |
| 367 | static void linear_exit (void) |
| 368 | { |
| 369 | unregister_md_personality (&linear_personality); |
| 370 | } |
| 371 | |
| 372 | |
| 373 | module_init(linear_init); |
| 374 | module_exit(linear_exit); |
| 375 | MODULE_LICENSE("GPL"); |
| 376 | MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/ |
| 377 | MODULE_ALIAS("md-linear"); |
| 378 | MODULE_ALIAS("md-level--1"); |