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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 | ||
45 | while ((sector>>1) >= (hash->size + hash->offset)) | |
46 | hash++; | |
47 | return hash; | |
48 | } | |
49 | ||
50 | /** | |
15945fee | 51 | * linear_mergeable_bvec -- tell bio layer if two requests can be merged |
1da177e4 LT |
52 | * @q: request queue |
53 | * @bio: the buffer head that's been built up so far | |
54 | * @biovec: the request that could be merged to it. | |
55 | * | |
56 | * Return amount of bytes we can take at this offset | |
57 | */ | |
58 | static int linear_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec) | |
59 | { | |
60 | mddev_t *mddev = q->queuedata; | |
61 | dev_info_t *dev0; | |
62 | unsigned long maxsectors, bio_sectors = bio->bi_size >> 9; | |
63 | sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); | |
64 | ||
65 | dev0 = which_dev(mddev, sector); | |
66 | maxsectors = (dev0->size << 1) - (sector - (dev0->offset<<1)); | |
67 | ||
68 | if (maxsectors < bio_sectors) | |
69 | maxsectors = 0; | |
70 | else | |
71 | maxsectors -= bio_sectors; | |
72 | ||
73 | if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0) | |
74 | return biovec->bv_len; | |
75 | /* The bytes available at this offset could be really big, | |
76 | * so we cap at 2^31 to avoid overflow */ | |
77 | if (maxsectors > (1 << (31-9))) | |
78 | return 1<<31; | |
79 | return maxsectors << 9; | |
80 | } | |
81 | ||
82 | static void linear_unplug(request_queue_t *q) | |
83 | { | |
84 | mddev_t *mddev = q->queuedata; | |
85 | linear_conf_t *conf = mddev_to_conf(mddev); | |
86 | int i; | |
87 | ||
88 | for (i=0; i < mddev->raid_disks; i++) { | |
89 | request_queue_t *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev); | |
90 | if (r_queue->unplug_fn) | |
91 | r_queue->unplug_fn(r_queue); | |
92 | } | |
93 | } | |
94 | ||
95 | static int linear_issue_flush(request_queue_t *q, struct gendisk *disk, | |
96 | sector_t *error_sector) | |
97 | { | |
98 | mddev_t *mddev = q->queuedata; | |
99 | linear_conf_t *conf = mddev_to_conf(mddev); | |
100 | int i, ret = 0; | |
101 | ||
102 | for (i=0; i < mddev->raid_disks && ret == 0; i++) { | |
103 | struct block_device *bdev = conf->disks[i].rdev->bdev; | |
104 | request_queue_t *r_queue = bdev_get_queue(bdev); | |
105 | ||
106 | if (!r_queue->issue_flush_fn) | |
107 | ret = -EOPNOTSUPP; | |
108 | else | |
109 | ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector); | |
110 | } | |
111 | return ret; | |
112 | } | |
113 | ||
7c7546cc | 114 | static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks) |
1da177e4 LT |
115 | { |
116 | linear_conf_t *conf; | |
117 | dev_info_t **table; | |
118 | mdk_rdev_t *rdev; | |
119 | int i, nb_zone, cnt; | |
15945fee | 120 | sector_t min_spacing; |
1da177e4 LT |
121 | sector_t curr_offset; |
122 | struct list_head *tmp; | |
123 | ||
7c7546cc | 124 | conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t), |
1da177e4 LT |
125 | GFP_KERNEL); |
126 | if (!conf) | |
7c7546cc N |
127 | return NULL; |
128 | ||
1da177e4 LT |
129 | mddev->private = conf; |
130 | ||
1da177e4 | 131 | cnt = 0; |
7c7546cc | 132 | conf->array_size = 0; |
1da177e4 LT |
133 | |
134 | ITERATE_RDEV(mddev,rdev,tmp) { | |
135 | int j = rdev->raid_disk; | |
136 | dev_info_t *disk = conf->disks + j; | |
137 | ||
7c7546cc | 138 | if (j < 0 || j > raid_disks || disk->rdev) { |
1da177e4 LT |
139 | printk("linear: disk numbering problem. Aborting!\n"); |
140 | goto out; | |
141 | } | |
142 | ||
143 | disk->rdev = rdev; | |
144 | ||
145 | blk_queue_stack_limits(mddev->queue, | |
146 | rdev->bdev->bd_disk->queue); | |
147 | /* as we don't honour merge_bvec_fn, we must never risk | |
148 | * violating it, so limit ->max_sector to one PAGE, as | |
149 | * a one page request is never in violation. | |
150 | */ | |
151 | if (rdev->bdev->bd_disk->queue->merge_bvec_fn && | |
152 | mddev->queue->max_sectors > (PAGE_SIZE>>9)) | |
153 | blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); | |
154 | ||
155 | disk->size = rdev->size; | |
7c7546cc | 156 | conf->array_size += rdev->size; |
1da177e4 | 157 | |
1da177e4 LT |
158 | cnt++; |
159 | } | |
7c7546cc | 160 | if (cnt != raid_disks) { |
1da177e4 LT |
161 | printk("linear: not enough drives present. Aborting!\n"); |
162 | goto out; | |
163 | } | |
164 | ||
15945fee N |
165 | min_spacing = mddev->array_size; |
166 | sector_div(min_spacing, PAGE_SIZE/sizeof(struct dev_info *)); | |
167 | ||
168 | /* min_spacing is the minimum spacing that will fit the hash | |
169 | * table in one PAGE. This may be much smaller than needed. | |
170 | * We find the smallest non-terminal set of consecutive devices | |
171 | * that is larger than min_spacing as use the size of that as | |
172 | * the actual spacing | |
173 | */ | |
174 | conf->hash_spacing = mddev->array_size; | |
175 | for (i=0; i < cnt-1 ; i++) { | |
176 | sector_t sz = 0; | |
177 | int j; | |
178 | for (j=i; i<cnt-1 && sz < min_spacing ; j++) | |
179 | sz += conf->disks[j].size; | |
180 | if (sz >= min_spacing && sz < conf->hash_spacing) | |
181 | conf->hash_spacing = sz; | |
182 | } | |
183 | ||
184 | /* hash_spacing may be too large for sector_div to work with, | |
185 | * so we might need to pre-shift | |
186 | */ | |
187 | conf->preshift = 0; | |
188 | if (sizeof(sector_t) > sizeof(u32)) { | |
189 | sector_t space = conf->hash_spacing; | |
190 | while (space > (sector_t)(~(u32)0)) { | |
191 | space >>= 1; | |
192 | conf->preshift++; | |
193 | } | |
194 | } | |
1da177e4 LT |
195 | /* |
196 | * This code was restructured to work around a gcc-2.95.3 internal | |
197 | * compiler error. Alter it with care. | |
198 | */ | |
199 | { | |
200 | sector_t sz; | |
201 | unsigned round; | |
202 | unsigned long base; | |
203 | ||
7c7546cc | 204 | sz = conf->array_size >> conf->preshift; |
15945fee N |
205 | sz += 1; /* force round-up */ |
206 | base = conf->hash_spacing >> conf->preshift; | |
1da177e4 | 207 | round = sector_div(sz, base); |
15945fee | 208 | nb_zone = sz + (round ? 1 : 0); |
1da177e4 | 209 | } |
15945fee N |
210 | BUG_ON(nb_zone > PAGE_SIZE / sizeof(struct dev_info *)); |
211 | ||
212 | conf->hash_table = kmalloc (sizeof (struct dev_info *) * nb_zone, | |
1da177e4 LT |
213 | GFP_KERNEL); |
214 | if (!conf->hash_table) | |
215 | goto out; | |
216 | ||
217 | /* | |
218 | * Here we generate the linear hash table | |
15945fee | 219 | * First calculate the device offsets. |
1da177e4 | 220 | */ |
15945fee N |
221 | conf->disks[0].offset = 0; |
222 | for (i=1; i<mddev->raid_disks; i++) | |
223 | conf->disks[i].offset = | |
224 | conf->disks[i-1].offset + | |
225 | conf->disks[i-1].size; | |
226 | ||
1da177e4 | 227 | table = conf->hash_table; |
1da177e4 | 228 | curr_offset = 0; |
15945fee N |
229 | i = 0; |
230 | for (curr_offset = 0; | |
231 | curr_offset < mddev->array_size; | |
232 | curr_offset += conf->hash_spacing) { | |
1da177e4 | 233 | |
15945fee N |
234 | while (i < mddev->raid_disks-1 && |
235 | curr_offset >= conf->disks[i+1].offset) | |
236 | i++; | |
1da177e4 | 237 | |
15945fee N |
238 | *table ++ = conf->disks + i; |
239 | } | |
240 | ||
241 | if (conf->preshift) { | |
242 | conf->hash_spacing >>= conf->preshift; | |
243 | /* round hash_spacing up so that when we divide by it, | |
244 | * we err on the side of "too-low", which is safest. | |
1da177e4 | 245 | */ |
15945fee | 246 | conf->hash_spacing++; |
1da177e4 | 247 | } |
15945fee N |
248 | |
249 | BUG_ON(table - conf->hash_table > nb_zone); | |
1da177e4 | 250 | |
7c7546cc N |
251 | return conf; |
252 | ||
253 | out: | |
254 | kfree(conf); | |
255 | return NULL; | |
256 | } | |
257 | ||
258 | static int linear_run (mddev_t *mddev) | |
259 | { | |
260 | linear_conf_t *conf; | |
261 | ||
262 | conf = linear_conf(mddev, mddev->raid_disks); | |
263 | ||
264 | if (!conf) | |
265 | return 1; | |
266 | mddev->private = conf; | |
267 | mddev->array_size = conf->array_size; | |
268 | ||
1da177e4 LT |
269 | blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec); |
270 | mddev->queue->unplug_fn = linear_unplug; | |
271 | mddev->queue->issue_flush_fn = linear_issue_flush; | |
272 | return 0; | |
7c7546cc | 273 | } |
1da177e4 | 274 | |
7c7546cc N |
275 | static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev) |
276 | { | |
277 | /* Adding a drive to a linear array allows the array to grow. | |
278 | * It is permitted if the new drive has a matching superblock | |
279 | * already on it, with raid_disk equal to raid_disks. | |
280 | * It is achieved by creating a new linear_private_data structure | |
281 | * and swapping it in in-place of the current one. | |
282 | * The current one is never freed until the array is stopped. | |
283 | * This avoids races. | |
284 | */ | |
285 | linear_conf_t *newconf; | |
286 | ||
287 | if (rdev->raid_disk != mddev->raid_disks) | |
288 | return -EINVAL; | |
289 | ||
290 | newconf = linear_conf(mddev,mddev->raid_disks+1); | |
291 | ||
292 | if (!newconf) | |
293 | return -ENOMEM; | |
294 | ||
295 | newconf->prev = mddev_to_conf(mddev); | |
296 | mddev->private = newconf; | |
297 | mddev->raid_disks++; | |
298 | mddev->array_size = newconf->array_size; | |
299 | set_capacity(mddev->gendisk, mddev->array_size << 1); | |
300 | return 0; | |
1da177e4 LT |
301 | } |
302 | ||
303 | static int linear_stop (mddev_t *mddev) | |
304 | { | |
305 | linear_conf_t *conf = mddev_to_conf(mddev); | |
306 | ||
307 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ | |
7c7546cc N |
308 | do { |
309 | linear_conf_t *t = conf->prev; | |
310 | kfree(conf->hash_table); | |
311 | kfree(conf); | |
312 | conf = t; | |
313 | } while (conf); | |
1da177e4 LT |
314 | |
315 | return 0; | |
316 | } | |
317 | ||
318 | static int linear_make_request (request_queue_t *q, struct bio *bio) | |
319 | { | |
a362357b | 320 | const int rw = bio_data_dir(bio); |
1da177e4 LT |
321 | mddev_t *mddev = q->queuedata; |
322 | dev_info_t *tmp_dev; | |
323 | sector_t block; | |
324 | ||
e5dcdd80 N |
325 | if (unlikely(bio_barrier(bio))) { |
326 | bio_endio(bio, bio->bi_size, -EOPNOTSUPP); | |
327 | return 0; | |
328 | } | |
329 | ||
a362357b JA |
330 | disk_stat_inc(mddev->gendisk, ios[rw]); |
331 | disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio)); | |
1da177e4 LT |
332 | |
333 | tmp_dev = which_dev(mddev, bio->bi_sector); | |
334 | block = bio->bi_sector >> 1; | |
335 | ||
336 | if (unlikely(block >= (tmp_dev->size + tmp_dev->offset) | |
337 | || block < tmp_dev->offset)) { | |
338 | char b[BDEVNAME_SIZE]; | |
339 | ||
340 | printk("linear_make_request: Block %llu out of bounds on " | |
341 | "dev %s size %llu offset %llu\n", | |
342 | (unsigned long long)block, | |
343 | bdevname(tmp_dev->rdev->bdev, b), | |
344 | (unsigned long long)tmp_dev->size, | |
345 | (unsigned long long)tmp_dev->offset); | |
346 | bio_io_error(bio, bio->bi_size); | |
347 | return 0; | |
348 | } | |
349 | if (unlikely(bio->bi_sector + (bio->bi_size >> 9) > | |
350 | (tmp_dev->offset + tmp_dev->size)<<1)) { | |
351 | /* This bio crosses a device boundary, so we have to | |
352 | * split it. | |
353 | */ | |
354 | struct bio_pair *bp; | |
29ac8e05 N |
355 | bp = bio_split(bio, bio_split_pool, |
356 | ((tmp_dev->offset + tmp_dev->size)<<1) - bio->bi_sector); | |
1da177e4 LT |
357 | if (linear_make_request(q, &bp->bio1)) |
358 | generic_make_request(&bp->bio1); | |
359 | if (linear_make_request(q, &bp->bio2)) | |
360 | generic_make_request(&bp->bio2); | |
361 | bio_pair_release(bp); | |
362 | return 0; | |
363 | } | |
364 | ||
365 | bio->bi_bdev = tmp_dev->rdev->bdev; | |
366 | bio->bi_sector = bio->bi_sector - (tmp_dev->offset << 1) + tmp_dev->rdev->data_offset; | |
367 | ||
368 | return 1; | |
369 | } | |
370 | ||
371 | static void linear_status (struct seq_file *seq, mddev_t *mddev) | |
372 | { | |
373 | ||
374 | #undef MD_DEBUG | |
375 | #ifdef MD_DEBUG | |
376 | int j; | |
377 | linear_conf_t *conf = mddev_to_conf(mddev); | |
378 | sector_t s = 0; | |
379 | ||
380 | seq_printf(seq, " "); | |
15945fee | 381 | for (j = 0; j < mddev->raid_disks; j++) |
1da177e4 LT |
382 | { |
383 | char b[BDEVNAME_SIZE]; | |
384 | s += conf->smallest_size; | |
385 | seq_printf(seq, "[%s", | |
386 | bdevname(conf->hash_table[j][0].rdev->bdev,b)); | |
387 | ||
388 | while (s > conf->hash_table[j][0].offset + | |
389 | conf->hash_table[j][0].size) | |
390 | seq_printf(seq, "/%s] ", | |
391 | bdevname(conf->hash_table[j][1].rdev->bdev,b)); | |
392 | else | |
393 | seq_printf(seq, "] "); | |
394 | } | |
395 | seq_printf(seq, "\n"); | |
396 | #endif | |
397 | seq_printf(seq, " %dk rounding", mddev->chunk_size/1024); | |
398 | } | |
399 | ||
400 | ||
2604b703 | 401 | static struct mdk_personality linear_personality = |
1da177e4 LT |
402 | { |
403 | .name = "linear", | |
2604b703 | 404 | .level = LEVEL_LINEAR, |
1da177e4 LT |
405 | .owner = THIS_MODULE, |
406 | .make_request = linear_make_request, | |
407 | .run = linear_run, | |
408 | .stop = linear_stop, | |
409 | .status = linear_status, | |
7c7546cc | 410 | .hot_add_disk = linear_add, |
1da177e4 LT |
411 | }; |
412 | ||
413 | static int __init linear_init (void) | |
414 | { | |
2604b703 | 415 | return register_md_personality (&linear_personality); |
1da177e4 LT |
416 | } |
417 | ||
418 | static void linear_exit (void) | |
419 | { | |
2604b703 | 420 | unregister_md_personality (&linear_personality); |
1da177e4 LT |
421 | } |
422 | ||
423 | ||
424 | module_init(linear_init); | |
425 | module_exit(linear_exit); | |
426 | MODULE_LICENSE("GPL"); | |
d9d166c2 N |
427 | MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/ |
428 | MODULE_ALIAS("md-linear"); | |
2604b703 | 429 | MODULE_ALIAS("md-level--1"); |