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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 | if (mddev_congested(mddev, bits)) |
112 | return 1; |
113 | |
114 | rcu_read_lock(); |
115 | conf = rcu_dereference(mddev->private); |
116 | |
117 | for (i = 0; i < mddev->raid_disks && !ret ; i++) { |
118 | struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev); |
119 | ret |= bdi_congested(&q->backing_dev_info, bits); |
120 | } |
121 | |
122 | rcu_read_unlock(); |
123 | return ret; |
124 | } |
125 | |
126 | static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks) |
127 | { |
128 | linear_conf_t *conf; |
129 | sector_t array_sectors; |
130 | |
131 | rcu_read_lock(); |
132 | conf = rcu_dereference(mddev->private); |
133 | WARN_ONCE(sectors || raid_disks, |
134 | "%s does not support generic reshape\n", __func__); |
135 | array_sectors = conf->array_sectors; |
136 | rcu_read_unlock(); |
137 | |
138 | return array_sectors; |
139 | } |
140 | |
141 | static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks) |
142 | { |
143 | linear_conf_t *conf; |
144 | mdk_rdev_t *rdev; |
145 | int i, cnt; |
146 | |
147 | conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t), |
148 | GFP_KERNEL); |
149 | if (!conf) |
150 | return NULL; |
151 | |
152 | cnt = 0; |
153 | conf->array_sectors = 0; |
154 | |
155 | list_for_each_entry(rdev, &mddev->disks, same_set) { |
156 | int j = rdev->raid_disk; |
157 | dev_info_t *disk = conf->disks + j; |
158 | sector_t sectors; |
159 | |
160 | if (j < 0 || j >= raid_disks || disk->rdev) { |
161 | printk("linear: disk numbering problem. Aborting!\n"); |
162 | goto out; |
163 | } |
164 | |
165 | disk->rdev = rdev; |
166 | if (mddev->chunk_sectors) { |
167 | sectors = rdev->sectors; |
168 | sector_div(sectors, mddev->chunk_sectors); |
169 | rdev->sectors = sectors * mddev->chunk_sectors; |
170 | } |
171 | |
172 | disk_stack_limits(mddev->gendisk, rdev->bdev, |
173 | rdev->data_offset << 9); |
174 | /* as we don't honour merge_bvec_fn, we must never risk |
175 | * violating it, so limit ->max_sector to one PAGE, as |
176 | * a one page request is never in violation. |
177 | */ |
178 | if (rdev->bdev->bd_disk->queue->merge_bvec_fn && |
179 | queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) |
180 | blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); |
181 | |
182 | conf->array_sectors += rdev->sectors; |
183 | cnt++; |
184 | |
185 | } |
186 | if (cnt != raid_disks) { |
187 | printk("linear: not enough drives present. Aborting!\n"); |
188 | goto out; |
189 | } |
190 | |
191 | /* |
192 | * Here we calculate the device offsets. |
193 | */ |
194 | conf->disks[0].end_sector = conf->disks[0].rdev->sectors; |
195 | |
196 | for (i = 1; i < raid_disks; i++) |
197 | conf->disks[i].end_sector = |
198 | conf->disks[i-1].end_sector + |
199 | conf->disks[i].rdev->sectors; |
200 | |
201 | return conf; |
202 | |
203 | out: |
204 | kfree(conf); |
205 | return NULL; |
206 | } |
207 | |
208 | static int linear_run (mddev_t *mddev) |
209 | { |
210 | linear_conf_t *conf; |
211 | |
212 | if (md_check_no_bitmap(mddev)) |
213 | return -EINVAL; |
214 | mddev->queue->queue_lock = &mddev->queue->__queue_lock; |
215 | conf = linear_conf(mddev, mddev->raid_disks); |
216 | |
217 | if (!conf) |
218 | return 1; |
219 | mddev->private = conf; |
220 | md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); |
221 | |
222 | blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec); |
223 | mddev->queue->unplug_fn = linear_unplug; |
224 | mddev->queue->backing_dev_info.congested_fn = linear_congested; |
225 | mddev->queue->backing_dev_info.congested_data = mddev; |
226 | md_integrity_register(mddev); |
227 | return 0; |
228 | } |
229 | |
230 | static void free_conf(struct rcu_head *head) |
231 | { |
232 | linear_conf_t *conf = container_of(head, linear_conf_t, rcu); |
233 | kfree(conf); |
234 | } |
235 | |
236 | static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev) |
237 | { |
238 | /* Adding a drive to a linear array allows the array to grow. |
239 | * It is permitted if the new drive has a matching superblock |
240 | * already on it, with raid_disk equal to raid_disks. |
241 | * It is achieved by creating a new linear_private_data structure |
242 | * and swapping it in in-place of the current one. |
243 | * The current one is never freed until the array is stopped. |
244 | * This avoids races. |
245 | */ |
246 | linear_conf_t *newconf, *oldconf; |
247 | |
248 | if (rdev->saved_raid_disk != mddev->raid_disks) |
249 | return -EINVAL; |
250 | |
251 | rdev->raid_disk = rdev->saved_raid_disk; |
252 | |
253 | newconf = linear_conf(mddev,mddev->raid_disks+1); |
254 | |
255 | if (!newconf) |
256 | return -ENOMEM; |
257 | |
258 | oldconf = rcu_dereference(mddev->private); |
259 | mddev->raid_disks++; |
260 | rcu_assign_pointer(mddev->private, newconf); |
261 | md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); |
262 | set_capacity(mddev->gendisk, mddev->array_sectors); |
263 | revalidate_disk(mddev->gendisk); |
264 | call_rcu(&oldconf->rcu, free_conf); |
265 | return 0; |
266 | } |
267 | |
268 | static int linear_stop (mddev_t *mddev) |
269 | { |
270 | linear_conf_t *conf = mddev->private; |
271 | |
272 | /* |
273 | * We do not require rcu protection here since |
274 | * we hold reconfig_mutex for both linear_add and |
275 | * linear_stop, so they cannot race. |
276 | * We should make sure any old 'conf's are properly |
277 | * freed though. |
278 | */ |
279 | rcu_barrier(); |
280 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ |
281 | kfree(conf); |
282 | |
283 | return 0; |
284 | } |
285 | |
286 | static int linear_make_request (struct request_queue *q, struct bio *bio) |
287 | { |
288 | const int rw = bio_data_dir(bio); |
289 | mddev_t *mddev = q->queuedata; |
290 | dev_info_t *tmp_dev; |
291 | sector_t start_sector; |
292 | int cpu; |
293 | |
294 | if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) { |
295 | bio_endio(bio, -EOPNOTSUPP); |
296 | return 0; |
297 | } |
298 | |
299 | cpu = part_stat_lock(); |
300 | part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); |
301 | part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], |
302 | bio_sectors(bio)); |
303 | part_stat_unlock(); |
304 | |
305 | rcu_read_lock(); |
306 | tmp_dev = which_dev(mddev, bio->bi_sector); |
307 | start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors; |
308 | |
309 | |
310 | if (unlikely(bio->bi_sector >= (tmp_dev->end_sector) |
311 | || (bio->bi_sector < start_sector))) { |
312 | char b[BDEVNAME_SIZE]; |
313 | |
314 | printk("linear_make_request: Sector %llu out of bounds on " |
315 | "dev %s: %llu sectors, offset %llu\n", |
316 | (unsigned long long)bio->bi_sector, |
317 | bdevname(tmp_dev->rdev->bdev, b), |
318 | (unsigned long long)tmp_dev->rdev->sectors, |
319 | (unsigned long long)start_sector); |
320 | rcu_read_unlock(); |
321 | bio_io_error(bio); |
322 | return 0; |
323 | } |
324 | if (unlikely(bio->bi_sector + (bio->bi_size >> 9) > |
325 | tmp_dev->end_sector)) { |
326 | /* This bio crosses a device boundary, so we have to |
327 | * split it. |
328 | */ |
329 | struct bio_pair *bp; |
330 | sector_t end_sector = tmp_dev->end_sector; |
331 | |
332 | rcu_read_unlock(); |
333 | |
334 | bp = bio_split(bio, end_sector - bio->bi_sector); |
335 | |
336 | if (linear_make_request(q, &bp->bio1)) |
337 | generic_make_request(&bp->bio1); |
338 | if (linear_make_request(q, &bp->bio2)) |
339 | generic_make_request(&bp->bio2); |
340 | bio_pair_release(bp); |
341 | return 0; |
342 | } |
343 | |
344 | bio->bi_bdev = tmp_dev->rdev->bdev; |
345 | bio->bi_sector = bio->bi_sector - start_sector |
346 | + tmp_dev->rdev->data_offset; |
347 | rcu_read_unlock(); |
348 | |
349 | return 1; |
350 | } |
351 | |
352 | static void linear_status (struct seq_file *seq, mddev_t *mddev) |
353 | { |
354 | |
355 | seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2); |
356 | } |
357 | |
358 | |
359 | static struct mdk_personality linear_personality = |
360 | { |
361 | .name = "linear", |
362 | .level = LEVEL_LINEAR, |
363 | .owner = THIS_MODULE, |
364 | .make_request = linear_make_request, |
365 | .run = linear_run, |
366 | .stop = linear_stop, |
367 | .status = linear_status, |
368 | .hot_add_disk = linear_add, |
369 | .size = linear_size, |
370 | }; |
371 | |
372 | static int __init linear_init (void) |
373 | { |
374 | return register_md_personality (&linear_personality); |
375 | } |
376 | |
377 | static void linear_exit (void) |
378 | { |
379 | unregister_md_personality (&linear_personality); |
380 | } |
381 | |
382 | |
383 | module_init(linear_init); |
384 | module_exit(linear_exit); |
385 | MODULE_LICENSE("GPL"); |
386 | MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/ |
387 | MODULE_ALIAS("md-linear"); |
388 | MODULE_ALIAS("md-level--1"); |
389 |
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