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1da177e4 LT |
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/module.h> | |
20 | ||
21 | #include <linux/raid/md.h> | |
22 | #include <linux/slab.h> | |
23 | #include <linux/raid/linear.h> | |
24 | ||
25 | #define MAJOR_NR MD_MAJOR | |
26 | #define MD_DRIVER | |
27 | #define MD_PERSONALITY | |
28 | ||
29 | /* | |
30 | * find which device holds a particular offset | |
31 | */ | |
32 | static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector) | |
33 | { | |
34 | dev_info_t *hash; | |
35 | linear_conf_t *conf = mddev_to_conf(mddev); | |
36 | sector_t block = sector >> 1; | |
37 | ||
38 | /* | |
39 | * sector_div(a,b) returns the remainer and sets a to a/b | |
40 | */ | |
15945fee N |
41 | block >>= conf->preshift; |
42 | (void)sector_div(block, conf->hash_spacing); | |
1da177e4 LT |
43 | hash = conf->hash_table[block]; |
44 | ||
6283815d | 45 | while (sector >= hash->num_sectors + hash->start_sector) |
1da177e4 LT |
46 | hash++; |
47 | return hash; | |
48 | } | |
49 | ||
50 | /** | |
15945fee | 51 | * linear_mergeable_bvec -- tell bio layer if two requests can be merged |
1da177e4 | 52 | * @q: request queue |
cc371e66 | 53 | * @bvm: properties of new bio |
1da177e4 LT |
54 | * @biovec: the request that could be merged to it. |
55 | * | |
56 | * Return amount of bytes we can take at this offset | |
57 | */ | |
cc371e66 AK |
58 | static int linear_mergeable_bvec(struct request_queue *q, |
59 | struct bvec_merge_data *bvm, | |
60 | struct bio_vec *biovec) | |
1da177e4 LT |
61 | { |
62 | mddev_t *mddev = q->queuedata; | |
63 | dev_info_t *dev0; | |
cc371e66 AK |
64 | unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9; |
65 | sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); | |
1da177e4 LT |
66 | |
67 | dev0 = which_dev(mddev, sector); | |
6283815d | 68 | maxsectors = dev0->num_sectors - (sector - dev0->start_sector); |
1da177e4 LT |
69 | |
70 | if (maxsectors < bio_sectors) | |
71 | maxsectors = 0; | |
72 | else | |
73 | maxsectors -= bio_sectors; | |
74 | ||
75 | if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0) | |
76 | return biovec->bv_len; | |
77 | /* The bytes available at this offset could be really big, | |
78 | * so we cap at 2^31 to avoid overflow */ | |
79 | if (maxsectors > (1 << (31-9))) | |
80 | return 1<<31; | |
81 | return maxsectors << 9; | |
82 | } | |
83 | ||
165125e1 | 84 | static void linear_unplug(struct request_queue *q) |
1da177e4 LT |
85 | { |
86 | mddev_t *mddev = q->queuedata; | |
87 | linear_conf_t *conf = mddev_to_conf(mddev); | |
88 | int i; | |
89 | ||
90 | for (i=0; i < mddev->raid_disks; i++) { | |
165125e1 | 91 | struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev); |
2ad8b1ef | 92 | blk_unplug(r_queue); |
1da177e4 LT |
93 | } |
94 | } | |
95 | ||
26be34dc N |
96 | static int linear_congested(void *data, int bits) |
97 | { | |
98 | mddev_t *mddev = data; | |
99 | linear_conf_t *conf = mddev_to_conf(mddev); | |
100 | int i, ret = 0; | |
101 | ||
102 | for (i = 0; i < mddev->raid_disks && !ret ; i++) { | |
165125e1 | 103 | struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev); |
26be34dc N |
104 | ret |= bdi_congested(&q->backing_dev_info, bits); |
105 | } | |
106 | return ret; | |
107 | } | |
108 | ||
7c7546cc | 109 | static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks) |
1da177e4 LT |
110 | { |
111 | linear_conf_t *conf; | |
112 | dev_info_t **table; | |
113 | mdk_rdev_t *rdev; | |
114 | int i, nb_zone, cnt; | |
23242fbb | 115 | sector_t min_sectors; |
6283815d | 116 | sector_t curr_sector; |
1da177e4 LT |
117 | struct list_head *tmp; |
118 | ||
7c7546cc | 119 | conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t), |
1da177e4 LT |
120 | GFP_KERNEL); |
121 | if (!conf) | |
7c7546cc N |
122 | return NULL; |
123 | ||
1da177e4 | 124 | cnt = 0; |
d6e22150 | 125 | conf->array_sectors = 0; |
1da177e4 | 126 | |
d089c6af | 127 | rdev_for_each(rdev, tmp, mddev) { |
1da177e4 LT |
128 | int j = rdev->raid_disk; |
129 | dev_info_t *disk = conf->disks + j; | |
130 | ||
13864515 | 131 | if (j < 0 || j >= raid_disks || disk->rdev) { |
1da177e4 LT |
132 | printk("linear: disk numbering problem. Aborting!\n"); |
133 | goto out; | |
134 | } | |
135 | ||
136 | disk->rdev = rdev; | |
137 | ||
138 | blk_queue_stack_limits(mddev->queue, | |
139 | rdev->bdev->bd_disk->queue); | |
140 | /* as we don't honour merge_bvec_fn, we must never risk | |
141 | * violating it, so limit ->max_sector to one PAGE, as | |
142 | * a one page request is never in violation. | |
143 | */ | |
144 | if (rdev->bdev->bd_disk->queue->merge_bvec_fn && | |
145 | mddev->queue->max_sectors > (PAGE_SIZE>>9)) | |
146 | blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); | |
147 | ||
6283815d | 148 | disk->num_sectors = rdev->size * 2; |
d6e22150 | 149 | conf->array_sectors += rdev->size * 2; |
1da177e4 | 150 | |
1da177e4 LT |
151 | cnt++; |
152 | } | |
7c7546cc | 153 | if (cnt != raid_disks) { |
1da177e4 LT |
154 | printk("linear: not enough drives present. Aborting!\n"); |
155 | goto out; | |
156 | } | |
157 | ||
23242fbb AN |
158 | min_sectors = conf->array_sectors; |
159 | sector_div(min_sectors, PAGE_SIZE/sizeof(struct dev_info *)); | |
15945fee | 160 | |
23242fbb | 161 | /* min_sectors is the minimum spacing that will fit the hash |
15945fee N |
162 | * table in one PAGE. This may be much smaller than needed. |
163 | * We find the smallest non-terminal set of consecutive devices | |
23242fbb | 164 | * that is larger than min_sectors and use the size of that as |
15945fee N |
165 | * the actual spacing |
166 | */ | |
d6e22150 | 167 | conf->hash_spacing = conf->array_sectors / 2; |
15945fee | 168 | for (i=0; i < cnt-1 ; i++) { |
23242fbb | 169 | sector_t tmp = 0; |
15945fee | 170 | int j; |
23242fbb AN |
171 | for (j = i; j < cnt - 1 && tmp < min_sectors; j++) |
172 | tmp += conf->disks[j].num_sectors; | |
173 | if (tmp >= min_sectors && tmp < conf->hash_spacing * 2) | |
174 | conf->hash_spacing = tmp / 2; | |
15945fee N |
175 | } |
176 | ||
177 | /* hash_spacing may be too large for sector_div to work with, | |
178 | * so we might need to pre-shift | |
179 | */ | |
180 | conf->preshift = 0; | |
181 | if (sizeof(sector_t) > sizeof(u32)) { | |
182 | sector_t space = conf->hash_spacing; | |
183 | while (space > (sector_t)(~(u32)0)) { | |
184 | space >>= 1; | |
185 | conf->preshift++; | |
186 | } | |
187 | } | |
1da177e4 LT |
188 | /* |
189 | * This code was restructured to work around a gcc-2.95.3 internal | |
190 | * compiler error. Alter it with care. | |
191 | */ | |
192 | { | |
193 | sector_t sz; | |
194 | unsigned round; | |
195 | unsigned long base; | |
196 | ||
d6e22150 | 197 | sz = conf->array_sectors >> (conf->preshift + 1); |
15945fee N |
198 | sz += 1; /* force round-up */ |
199 | base = conf->hash_spacing >> conf->preshift; | |
1da177e4 | 200 | round = sector_div(sz, base); |
15945fee | 201 | nb_zone = sz + (round ? 1 : 0); |
1da177e4 | 202 | } |
15945fee N |
203 | BUG_ON(nb_zone > PAGE_SIZE / sizeof(struct dev_info *)); |
204 | ||
205 | conf->hash_table = kmalloc (sizeof (struct dev_info *) * nb_zone, | |
1da177e4 LT |
206 | GFP_KERNEL); |
207 | if (!conf->hash_table) | |
208 | goto out; | |
209 | ||
210 | /* | |
211 | * Here we generate the linear hash table | |
15945fee | 212 | * First calculate the device offsets. |
1da177e4 | 213 | */ |
6283815d | 214 | conf->disks[0].start_sector = 0; |
a778b73f | 215 | for (i = 1; i < raid_disks; i++) |
6283815d AN |
216 | conf->disks[i].start_sector = |
217 | conf->disks[i-1].start_sector + | |
218 | conf->disks[i-1].num_sectors; | |
15945fee | 219 | |
1da177e4 | 220 | table = conf->hash_table; |
15945fee | 221 | i = 0; |
6283815d AN |
222 | for (curr_sector = 0; |
223 | curr_sector < conf->array_sectors; | |
224 | curr_sector += conf->hash_spacing * 2) { | |
1da177e4 | 225 | |
a778b73f | 226 | while (i < raid_disks-1 && |
6283815d | 227 | curr_sector >= conf->disks[i+1].start_sector) |
15945fee | 228 | i++; |
1da177e4 | 229 | |
15945fee N |
230 | *table ++ = conf->disks + i; |
231 | } | |
232 | ||
233 | if (conf->preshift) { | |
234 | conf->hash_spacing >>= conf->preshift; | |
235 | /* round hash_spacing up so that when we divide by it, | |
236 | * we err on the side of "too-low", which is safest. | |
1da177e4 | 237 | */ |
15945fee | 238 | conf->hash_spacing++; |
1da177e4 | 239 | } |
15945fee N |
240 | |
241 | BUG_ON(table - conf->hash_table > nb_zone); | |
1da177e4 | 242 | |
7c7546cc N |
243 | return conf; |
244 | ||
245 | out: | |
246 | kfree(conf); | |
247 | return NULL; | |
248 | } | |
249 | ||
250 | static int linear_run (mddev_t *mddev) | |
251 | { | |
252 | linear_conf_t *conf; | |
253 | ||
e7e72bf6 | 254 | mddev->queue->queue_lock = &mddev->queue->__queue_lock; |
7c7546cc N |
255 | conf = linear_conf(mddev, mddev->raid_disks); |
256 | ||
257 | if (!conf) | |
258 | return 1; | |
259 | mddev->private = conf; | |
d6e22150 | 260 | mddev->array_sectors = conf->array_sectors; |
7c7546cc | 261 | |
1da177e4 LT |
262 | blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec); |
263 | mddev->queue->unplug_fn = linear_unplug; | |
26be34dc N |
264 | mddev->queue->backing_dev_info.congested_fn = linear_congested; |
265 | mddev->queue->backing_dev_info.congested_data = mddev; | |
1da177e4 | 266 | return 0; |
7c7546cc | 267 | } |
1da177e4 | 268 | |
7c7546cc N |
269 | static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev) |
270 | { | |
271 | /* Adding a drive to a linear array allows the array to grow. | |
272 | * It is permitted if the new drive has a matching superblock | |
273 | * already on it, with raid_disk equal to raid_disks. | |
274 | * It is achieved by creating a new linear_private_data structure | |
275 | * and swapping it in in-place of the current one. | |
276 | * The current one is never freed until the array is stopped. | |
277 | * This avoids races. | |
278 | */ | |
279 | linear_conf_t *newconf; | |
280 | ||
a778b73f | 281 | if (rdev->saved_raid_disk != mddev->raid_disks) |
7c7546cc N |
282 | return -EINVAL; |
283 | ||
a778b73f N |
284 | rdev->raid_disk = rdev->saved_raid_disk; |
285 | ||
7c7546cc N |
286 | newconf = linear_conf(mddev,mddev->raid_disks+1); |
287 | ||
288 | if (!newconf) | |
289 | return -ENOMEM; | |
290 | ||
291 | newconf->prev = mddev_to_conf(mddev); | |
292 | mddev->private = newconf; | |
293 | mddev->raid_disks++; | |
d6e22150 | 294 | mddev->array_sectors = newconf->array_sectors; |
f233ea5c | 295 | set_capacity(mddev->gendisk, mddev->array_sectors); |
7c7546cc | 296 | return 0; |
1da177e4 LT |
297 | } |
298 | ||
299 | static int linear_stop (mddev_t *mddev) | |
300 | { | |
301 | linear_conf_t *conf = mddev_to_conf(mddev); | |
302 | ||
303 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ | |
7c7546cc N |
304 | do { |
305 | linear_conf_t *t = conf->prev; | |
306 | kfree(conf->hash_table); | |
307 | kfree(conf); | |
308 | conf = t; | |
309 | } while (conf); | |
1da177e4 LT |
310 | |
311 | return 0; | |
312 | } | |
313 | ||
165125e1 | 314 | static int linear_make_request (struct request_queue *q, struct bio *bio) |
1da177e4 | 315 | { |
a362357b | 316 | const int rw = bio_data_dir(bio); |
1da177e4 LT |
317 | mddev_t *mddev = q->queuedata; |
318 | dev_info_t *tmp_dev; | |
c9959059 | 319 | int cpu; |
1da177e4 | 320 | |
e5dcdd80 | 321 | if (unlikely(bio_barrier(bio))) { |
6712ecf8 | 322 | bio_endio(bio, -EOPNOTSUPP); |
e5dcdd80 N |
323 | return 0; |
324 | } | |
325 | ||
074a7aca TH |
326 | cpu = part_stat_lock(); |
327 | part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); | |
328 | part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], | |
329 | bio_sectors(bio)); | |
330 | part_stat_unlock(); | |
1da177e4 LT |
331 | |
332 | tmp_dev = which_dev(mddev, bio->bi_sector); | |
1da177e4 | 333 | |
6283815d AN |
334 | if (unlikely(bio->bi_sector >= (tmp_dev->num_sectors + |
335 | tmp_dev->start_sector) | |
336 | || (bio->bi_sector < | |
337 | tmp_dev->start_sector))) { | |
1da177e4 LT |
338 | char b[BDEVNAME_SIZE]; |
339 | ||
6283815d AN |
340 | printk("linear_make_request: Sector %llu out of bounds on " |
341 | "dev %s: %llu sectors, offset %llu\n", | |
342 | (unsigned long long)bio->bi_sector, | |
1da177e4 | 343 | bdevname(tmp_dev->rdev->bdev, b), |
6283815d AN |
344 | (unsigned long long)tmp_dev->num_sectors, |
345 | (unsigned long long)tmp_dev->start_sector); | |
6712ecf8 | 346 | bio_io_error(bio); |
1da177e4 LT |
347 | return 0; |
348 | } | |
349 | if (unlikely(bio->bi_sector + (bio->bi_size >> 9) > | |
6283815d | 350 | tmp_dev->start_sector + tmp_dev->num_sectors)) { |
1da177e4 LT |
351 | /* This bio crosses a device boundary, so we have to |
352 | * split it. | |
353 | */ | |
354 | struct bio_pair *bp; | |
6283815d | 355 | |
6feef531 | 356 | bp = bio_split(bio, |
6283815d AN |
357 | tmp_dev->start_sector + tmp_dev->num_sectors |
358 | - bio->bi_sector); | |
359 | ||
1da177e4 LT |
360 | if (linear_make_request(q, &bp->bio1)) |
361 | generic_make_request(&bp->bio1); | |
362 | if (linear_make_request(q, &bp->bio2)) | |
363 | generic_make_request(&bp->bio2); | |
364 | bio_pair_release(bp); | |
365 | return 0; | |
366 | } | |
367 | ||
368 | bio->bi_bdev = tmp_dev->rdev->bdev; | |
6283815d AN |
369 | bio->bi_sector = bio->bi_sector - tmp_dev->start_sector |
370 | + tmp_dev->rdev->data_offset; | |
1da177e4 LT |
371 | |
372 | return 1; | |
373 | } | |
374 | ||
375 | static void linear_status (struct seq_file *seq, mddev_t *mddev) | |
376 | { | |
377 | ||
1da177e4 LT |
378 | seq_printf(seq, " %dk rounding", mddev->chunk_size/1024); |
379 | } | |
380 | ||
381 | ||
2604b703 | 382 | static struct mdk_personality linear_personality = |
1da177e4 LT |
383 | { |
384 | .name = "linear", | |
2604b703 | 385 | .level = LEVEL_LINEAR, |
1da177e4 LT |
386 | .owner = THIS_MODULE, |
387 | .make_request = linear_make_request, | |
388 | .run = linear_run, | |
389 | .stop = linear_stop, | |
390 | .status = linear_status, | |
7c7546cc | 391 | .hot_add_disk = linear_add, |
1da177e4 LT |
392 | }; |
393 | ||
394 | static int __init linear_init (void) | |
395 | { | |
2604b703 | 396 | return register_md_personality (&linear_personality); |
1da177e4 LT |
397 | } |
398 | ||
399 | static void linear_exit (void) | |
400 | { | |
2604b703 | 401 | unregister_md_personality (&linear_personality); |
1da177e4 LT |
402 | } |
403 | ||
404 | ||
405 | module_init(linear_init); | |
406 | module_exit(linear_exit); | |
407 | MODULE_LICENSE("GPL"); | |
d9d166c2 N |
408 | MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/ |
409 | MODULE_ALIAS("md-linear"); | |
2604b703 | 410 | MODULE_ALIAS("md-level--1"); |