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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 | */ | |
41 | (void)sector_div(block, conf->smallest->size); | |
42 | hash = conf->hash_table[block]; | |
43 | ||
44 | while ((sector>>1) >= (hash->size + hash->offset)) | |
45 | hash++; | |
46 | return hash; | |
47 | } | |
48 | ||
49 | /** | |
50 | * linear_mergeable_bvec -- tell bio layer if a two requests can be merged | |
51 | * @q: request queue | |
52 | * @bio: the buffer head that's been built up so far | |
53 | * @biovec: the request that could be merged to it. | |
54 | * | |
55 | * Return amount of bytes we can take at this offset | |
56 | */ | |
57 | static int linear_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec) | |
58 | { | |
59 | mddev_t *mddev = q->queuedata; | |
60 | dev_info_t *dev0; | |
61 | unsigned long maxsectors, bio_sectors = bio->bi_size >> 9; | |
62 | sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); | |
63 | ||
64 | dev0 = which_dev(mddev, sector); | |
65 | maxsectors = (dev0->size << 1) - (sector - (dev0->offset<<1)); | |
66 | ||
67 | if (maxsectors < bio_sectors) | |
68 | maxsectors = 0; | |
69 | else | |
70 | maxsectors -= bio_sectors; | |
71 | ||
72 | if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0) | |
73 | return biovec->bv_len; | |
74 | /* The bytes available at this offset could be really big, | |
75 | * so we cap at 2^31 to avoid overflow */ | |
76 | if (maxsectors > (1 << (31-9))) | |
77 | return 1<<31; | |
78 | return maxsectors << 9; | |
79 | } | |
80 | ||
81 | static void linear_unplug(request_queue_t *q) | |
82 | { | |
83 | mddev_t *mddev = q->queuedata; | |
84 | linear_conf_t *conf = mddev_to_conf(mddev); | |
85 | int i; | |
86 | ||
87 | for (i=0; i < mddev->raid_disks; i++) { | |
88 | request_queue_t *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev); | |
89 | if (r_queue->unplug_fn) | |
90 | r_queue->unplug_fn(r_queue); | |
91 | } | |
92 | } | |
93 | ||
94 | static int linear_issue_flush(request_queue_t *q, struct gendisk *disk, | |
95 | sector_t *error_sector) | |
96 | { | |
97 | mddev_t *mddev = q->queuedata; | |
98 | linear_conf_t *conf = mddev_to_conf(mddev); | |
99 | int i, ret = 0; | |
100 | ||
101 | for (i=0; i < mddev->raid_disks && ret == 0; i++) { | |
102 | struct block_device *bdev = conf->disks[i].rdev->bdev; | |
103 | request_queue_t *r_queue = bdev_get_queue(bdev); | |
104 | ||
105 | if (!r_queue->issue_flush_fn) | |
106 | ret = -EOPNOTSUPP; | |
107 | else | |
108 | ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector); | |
109 | } | |
110 | return ret; | |
111 | } | |
112 | ||
113 | static int linear_run (mddev_t *mddev) | |
114 | { | |
115 | linear_conf_t *conf; | |
116 | dev_info_t **table; | |
117 | mdk_rdev_t *rdev; | |
118 | int i, nb_zone, cnt; | |
119 | sector_t start; | |
120 | sector_t curr_offset; | |
121 | struct list_head *tmp; | |
122 | ||
123 | conf = kmalloc (sizeof (*conf) + mddev->raid_disks*sizeof(dev_info_t), | |
124 | GFP_KERNEL); | |
125 | if (!conf) | |
126 | goto out; | |
127 | memset(conf, 0, sizeof(*conf) + mddev->raid_disks*sizeof(dev_info_t)); | |
128 | mddev->private = conf; | |
129 | ||
130 | /* | |
131 | * Find the smallest device. | |
132 | */ | |
133 | ||
134 | conf->smallest = NULL; | |
135 | cnt = 0; | |
136 | mddev->array_size = 0; | |
137 | ||
138 | ITERATE_RDEV(mddev,rdev,tmp) { | |
139 | int j = rdev->raid_disk; | |
140 | dev_info_t *disk = conf->disks + j; | |
141 | ||
142 | if (j < 0 || j > mddev->raid_disks || disk->rdev) { | |
143 | printk("linear: disk numbering problem. Aborting!\n"); | |
144 | goto out; | |
145 | } | |
146 | ||
147 | disk->rdev = rdev; | |
148 | ||
149 | blk_queue_stack_limits(mddev->queue, | |
150 | rdev->bdev->bd_disk->queue); | |
151 | /* as we don't honour merge_bvec_fn, we must never risk | |
152 | * violating it, so limit ->max_sector to one PAGE, as | |
153 | * a one page request is never in violation. | |
154 | */ | |
155 | if (rdev->bdev->bd_disk->queue->merge_bvec_fn && | |
156 | mddev->queue->max_sectors > (PAGE_SIZE>>9)) | |
157 | blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); | |
158 | ||
159 | disk->size = rdev->size; | |
160 | mddev->array_size += rdev->size; | |
161 | ||
162 | if (!conf->smallest || (disk->size < conf->smallest->size)) | |
163 | conf->smallest = disk; | |
164 | cnt++; | |
165 | } | |
166 | if (cnt != mddev->raid_disks) { | |
167 | printk("linear: not enough drives present. Aborting!\n"); | |
168 | goto out; | |
169 | } | |
170 | ||
171 | /* | |
172 | * This code was restructured to work around a gcc-2.95.3 internal | |
173 | * compiler error. Alter it with care. | |
174 | */ | |
175 | { | |
176 | sector_t sz; | |
177 | unsigned round; | |
178 | unsigned long base; | |
179 | ||
180 | sz = mddev->array_size; | |
181 | base = conf->smallest->size; | |
182 | round = sector_div(sz, base); | |
183 | nb_zone = conf->nr_zones = sz + (round ? 1 : 0); | |
184 | } | |
185 | ||
186 | conf->hash_table = kmalloc (sizeof (dev_info_t*) * nb_zone, | |
187 | GFP_KERNEL); | |
188 | if (!conf->hash_table) | |
189 | goto out; | |
190 | ||
191 | /* | |
192 | * Here we generate the linear hash table | |
193 | */ | |
194 | table = conf->hash_table; | |
195 | start = 0; | |
196 | curr_offset = 0; | |
197 | for (i = 0; i < cnt; i++) { | |
198 | dev_info_t *disk = conf->disks + i; | |
199 | ||
200 | disk->offset = curr_offset; | |
201 | curr_offset += disk->size; | |
202 | ||
203 | /* 'curr_offset' is the end of this disk | |
204 | * 'start' is the start of table | |
205 | */ | |
206 | while (start < curr_offset) { | |
207 | *table++ = disk; | |
208 | start += conf->smallest->size; | |
209 | } | |
210 | } | |
211 | if (table-conf->hash_table != nb_zone) | |
212 | BUG(); | |
213 | ||
214 | blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec); | |
215 | mddev->queue->unplug_fn = linear_unplug; | |
216 | mddev->queue->issue_flush_fn = linear_issue_flush; | |
217 | return 0; | |
218 | ||
219 | out: | |
220 | if (conf) | |
221 | kfree(conf); | |
222 | return 1; | |
223 | } | |
224 | ||
225 | static int linear_stop (mddev_t *mddev) | |
226 | { | |
227 | linear_conf_t *conf = mddev_to_conf(mddev); | |
228 | ||
229 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ | |
230 | kfree(conf->hash_table); | |
231 | kfree(conf); | |
232 | ||
233 | return 0; | |
234 | } | |
235 | ||
236 | static int linear_make_request (request_queue_t *q, struct bio *bio) | |
237 | { | |
238 | mddev_t *mddev = q->queuedata; | |
239 | dev_info_t *tmp_dev; | |
240 | sector_t block; | |
241 | ||
242 | if (bio_data_dir(bio)==WRITE) { | |
243 | disk_stat_inc(mddev->gendisk, writes); | |
244 | disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio)); | |
245 | } else { | |
246 | disk_stat_inc(mddev->gendisk, reads); | |
247 | disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio)); | |
248 | } | |
249 | ||
250 | tmp_dev = which_dev(mddev, bio->bi_sector); | |
251 | block = bio->bi_sector >> 1; | |
252 | ||
253 | if (unlikely(block >= (tmp_dev->size + tmp_dev->offset) | |
254 | || block < tmp_dev->offset)) { | |
255 | char b[BDEVNAME_SIZE]; | |
256 | ||
257 | printk("linear_make_request: Block %llu out of bounds on " | |
258 | "dev %s size %llu offset %llu\n", | |
259 | (unsigned long long)block, | |
260 | bdevname(tmp_dev->rdev->bdev, b), | |
261 | (unsigned long long)tmp_dev->size, | |
262 | (unsigned long long)tmp_dev->offset); | |
263 | bio_io_error(bio, bio->bi_size); | |
264 | return 0; | |
265 | } | |
266 | if (unlikely(bio->bi_sector + (bio->bi_size >> 9) > | |
267 | (tmp_dev->offset + tmp_dev->size)<<1)) { | |
268 | /* This bio crosses a device boundary, so we have to | |
269 | * split it. | |
270 | */ | |
271 | struct bio_pair *bp; | |
272 | bp = bio_split(bio, bio_split_pool, | |
273 | (bio->bi_sector + (bio->bi_size >> 9) - | |
274 | (tmp_dev->offset + tmp_dev->size))<<1); | |
275 | if (linear_make_request(q, &bp->bio1)) | |
276 | generic_make_request(&bp->bio1); | |
277 | if (linear_make_request(q, &bp->bio2)) | |
278 | generic_make_request(&bp->bio2); | |
279 | bio_pair_release(bp); | |
280 | return 0; | |
281 | } | |
282 | ||
283 | bio->bi_bdev = tmp_dev->rdev->bdev; | |
284 | bio->bi_sector = bio->bi_sector - (tmp_dev->offset << 1) + tmp_dev->rdev->data_offset; | |
285 | ||
286 | return 1; | |
287 | } | |
288 | ||
289 | static void linear_status (struct seq_file *seq, mddev_t *mddev) | |
290 | { | |
291 | ||
292 | #undef MD_DEBUG | |
293 | #ifdef MD_DEBUG | |
294 | int j; | |
295 | linear_conf_t *conf = mddev_to_conf(mddev); | |
296 | sector_t s = 0; | |
297 | ||
298 | seq_printf(seq, " "); | |
299 | for (j = 0; j < conf->nr_zones; j++) | |
300 | { | |
301 | char b[BDEVNAME_SIZE]; | |
302 | s += conf->smallest_size; | |
303 | seq_printf(seq, "[%s", | |
304 | bdevname(conf->hash_table[j][0].rdev->bdev,b)); | |
305 | ||
306 | while (s > conf->hash_table[j][0].offset + | |
307 | conf->hash_table[j][0].size) | |
308 | seq_printf(seq, "/%s] ", | |
309 | bdevname(conf->hash_table[j][1].rdev->bdev,b)); | |
310 | else | |
311 | seq_printf(seq, "] "); | |
312 | } | |
313 | seq_printf(seq, "\n"); | |
314 | #endif | |
315 | seq_printf(seq, " %dk rounding", mddev->chunk_size/1024); | |
316 | } | |
317 | ||
318 | ||
319 | static mdk_personality_t linear_personality= | |
320 | { | |
321 | .name = "linear", | |
322 | .owner = THIS_MODULE, | |
323 | .make_request = linear_make_request, | |
324 | .run = linear_run, | |
325 | .stop = linear_stop, | |
326 | .status = linear_status, | |
327 | }; | |
328 | ||
329 | static int __init linear_init (void) | |
330 | { | |
331 | return register_md_personality (LINEAR, &linear_personality); | |
332 | } | |
333 | ||
334 | static void linear_exit (void) | |
335 | { | |
336 | unregister_md_personality (LINEAR); | |
337 | } | |
338 | ||
339 | ||
340 | module_init(linear_init); | |
341 | module_exit(linear_exit); | |
342 | MODULE_LICENSE("GPL"); | |
343 | MODULE_ALIAS("md-personality-1"); /* LINEAR */ |