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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 <linux/module.h> | |
23 | #include <linux/slab.h> | |
24 | #include "md.h" | |
25 | #include "linear.h" | |
26 | ||
27 | /* | |
28 | * find which device holds a particular offset | |
29 | */ | |
30 | static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector) | |
31 | { | |
32 | int lo, mid, hi; | |
33 | struct linear_conf *conf; | |
34 | ||
35 | lo = 0; | |
36 | hi = mddev->raid_disks - 1; | |
37 | conf = rcu_dereference(mddev->private); | |
38 | ||
39 | /* | |
40 | * Binary Search | |
41 | */ | |
42 | ||
43 | while (hi > lo) { | |
44 | ||
45 | mid = (hi + lo) / 2; | |
46 | if (sector < conf->disks[mid].end_sector) | |
47 | hi = mid; | |
48 | else | |
49 | lo = mid + 1; | |
50 | } | |
51 | ||
52 | return conf->disks + lo; | |
53 | } | |
54 | ||
55 | /** | |
56 | * linear_mergeable_bvec -- tell bio layer if two requests can be merged | |
57 | * @q: request queue | |
58 | * @bvm: properties of new bio | |
59 | * @biovec: the request that could be merged to it. | |
60 | * | |
61 | * Return amount of bytes we can take at this offset | |
62 | */ | |
63 | static int linear_mergeable_bvec(struct request_queue *q, | |
64 | struct bvec_merge_data *bvm, | |
65 | struct bio_vec *biovec) | |
66 | { | |
67 | struct mddev *mddev = q->queuedata; | |
68 | struct dev_info *dev0; | |
69 | unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9; | |
70 | sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); | |
71 | int maxbytes = biovec->bv_len; | |
72 | struct request_queue *subq; | |
73 | ||
74 | rcu_read_lock(); | |
75 | dev0 = which_dev(mddev, sector); | |
76 | maxsectors = dev0->end_sector - sector; | |
77 | subq = bdev_get_queue(dev0->rdev->bdev); | |
78 | if (subq->merge_bvec_fn) { | |
79 | bvm->bi_bdev = dev0->rdev->bdev; | |
80 | bvm->bi_sector -= dev0->end_sector - dev0->rdev->sectors; | |
81 | maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm, | |
82 | biovec)); | |
83 | } | |
84 | rcu_read_unlock(); | |
85 | ||
86 | if (maxsectors < bio_sectors) | |
87 | maxsectors = 0; | |
88 | else | |
89 | maxsectors -= bio_sectors; | |
90 | ||
91 | if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0) | |
92 | return maxbytes; | |
93 | ||
94 | if (maxsectors > (maxbytes >> 9)) | |
95 | return maxbytes; | |
96 | else | |
97 | return maxsectors << 9; | |
98 | } | |
99 | ||
100 | static int linear_congested(void *data, int bits) | |
101 | { | |
102 | struct mddev *mddev = data; | |
103 | struct linear_conf *conf; | |
104 | int i, ret = 0; | |
105 | ||
106 | if (mddev_congested(mddev, bits)) | |
107 | return 1; | |
108 | ||
109 | rcu_read_lock(); | |
110 | conf = rcu_dereference(mddev->private); | |
111 | ||
112 | for (i = 0; i < mddev->raid_disks && !ret ; i++) { | |
113 | struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev); | |
114 | ret |= bdi_congested(&q->backing_dev_info, bits); | |
115 | } | |
116 | ||
117 | rcu_read_unlock(); | |
118 | return ret; | |
119 | } | |
120 | ||
121 | static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks) | |
122 | { | |
123 | struct linear_conf *conf; | |
124 | sector_t array_sectors; | |
125 | ||
126 | rcu_read_lock(); | |
127 | conf = rcu_dereference(mddev->private); | |
128 | WARN_ONCE(sectors || raid_disks, | |
129 | "%s does not support generic reshape\n", __func__); | |
130 | array_sectors = conf->array_sectors; | |
131 | rcu_read_unlock(); | |
132 | ||
133 | return array_sectors; | |
134 | } | |
135 | ||
136 | static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks) | |
137 | { | |
138 | struct linear_conf *conf; | |
139 | struct md_rdev *rdev; | |
140 | int i, cnt; | |
141 | bool discard_supported = false; | |
142 | ||
143 | conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info), | |
144 | GFP_KERNEL); | |
145 | if (!conf) | |
146 | return NULL; | |
147 | ||
148 | cnt = 0; | |
149 | conf->array_sectors = 0; | |
150 | ||
151 | rdev_for_each(rdev, mddev) { | |
152 | int j = rdev->raid_disk; | |
153 | struct dev_info *disk = conf->disks + j; | |
154 | sector_t sectors; | |
155 | ||
156 | if (j < 0 || j >= raid_disks || disk->rdev) { | |
157 | printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n", | |
158 | mdname(mddev)); | |
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 | disk_stack_limits(mddev->gendisk, rdev->bdev, | |
170 | rdev->data_offset << 9); | |
171 | ||
172 | conf->array_sectors += rdev->sectors; | |
173 | cnt++; | |
174 | ||
175 | if (blk_queue_discard(bdev_get_queue(rdev->bdev))) | |
176 | discard_supported = true; | |
177 | } | |
178 | if (cnt != raid_disks) { | |
179 | printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n", | |
180 | mdname(mddev)); | |
181 | goto out; | |
182 | } | |
183 | ||
184 | if (!discard_supported) | |
185 | queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue); | |
186 | else | |
187 | queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue); | |
188 | ||
189 | /* | |
190 | * Here we calculate the device offsets. | |
191 | */ | |
192 | conf->disks[0].end_sector = conf->disks[0].rdev->sectors; | |
193 | ||
194 | for (i = 1; i < raid_disks; i++) | |
195 | conf->disks[i].end_sector = | |
196 | conf->disks[i-1].end_sector + | |
197 | conf->disks[i].rdev->sectors; | |
198 | ||
199 | return conf; | |
200 | ||
201 | out: | |
202 | kfree(conf); | |
203 | return NULL; | |
204 | } | |
205 | ||
206 | static int linear_run (struct mddev *mddev) | |
207 | { | |
208 | struct linear_conf *conf; | |
209 | int ret; | |
210 | ||
211 | if (md_check_no_bitmap(mddev)) | |
212 | return -EINVAL; | |
213 | conf = linear_conf(mddev, mddev->raid_disks); | |
214 | ||
215 | if (!conf) | |
216 | return 1; | |
217 | mddev->private = conf; | |
218 | md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); | |
219 | ||
220 | blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec); | |
221 | mddev->queue->backing_dev_info.congested_fn = linear_congested; | |
222 | mddev->queue->backing_dev_info.congested_data = mddev; | |
223 | ||
224 | ret = md_integrity_register(mddev); | |
225 | if (ret) { | |
226 | kfree(conf); | |
227 | mddev->private = NULL; | |
228 | } | |
229 | return ret; | |
230 | } | |
231 | ||
232 | static int linear_add(struct mddev *mddev, struct md_rdev *rdev) | |
233 | { | |
234 | /* Adding a drive to a linear array allows the array to grow. | |
235 | * It is permitted if the new drive has a matching superblock | |
236 | * already on it, with raid_disk equal to raid_disks. | |
237 | * It is achieved by creating a new linear_private_data structure | |
238 | * and swapping it in in-place of the current one. | |
239 | * The current one is never freed until the array is stopped. | |
240 | * This avoids races. | |
241 | */ | |
242 | struct linear_conf *newconf, *oldconf; | |
243 | ||
244 | if (rdev->saved_raid_disk != mddev->raid_disks) | |
245 | return -EINVAL; | |
246 | ||
247 | rdev->raid_disk = rdev->saved_raid_disk; | |
248 | rdev->saved_raid_disk = -1; | |
249 | ||
250 | newconf = linear_conf(mddev,mddev->raid_disks+1); | |
251 | ||
252 | if (!newconf) | |
253 | return -ENOMEM; | |
254 | ||
255 | oldconf = rcu_dereference_protected(mddev->private, | |
256 | lockdep_is_held( | |
257 | &mddev->reconfig_mutex)); | |
258 | mddev->raid_disks++; | |
259 | rcu_assign_pointer(mddev->private, newconf); | |
260 | md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); | |
261 | set_capacity(mddev->gendisk, mddev->array_sectors); | |
262 | revalidate_disk(mddev->gendisk); | |
263 | kfree_rcu(oldconf, rcu); | |
264 | return 0; | |
265 | } | |
266 | ||
267 | static int linear_stop (struct mddev *mddev) | |
268 | { | |
269 | struct linear_conf *conf = | |
270 | rcu_dereference_protected(mddev->private, | |
271 | lockdep_is_held( | |
272 | &mddev->reconfig_mutex)); | |
273 | ||
274 | /* | |
275 | * We do not require rcu protection here since | |
276 | * we hold reconfig_mutex for both linear_add and | |
277 | * linear_stop, so they cannot race. | |
278 | * We should make sure any old 'conf's are properly | |
279 | * freed though. | |
280 | */ | |
281 | rcu_barrier(); | |
282 | blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ | |
283 | kfree(conf); | |
284 | mddev->private = NULL; | |
285 | ||
286 | return 0; | |
287 | } | |
288 | ||
289 | static void linear_make_request(struct mddev *mddev, struct bio *bio) | |
290 | { | |
291 | struct dev_info *tmp_dev; | |
292 | sector_t start_sector; | |
293 | ||
294 | if (unlikely(bio->bi_rw & REQ_FLUSH)) { | |
295 | md_flush_request(mddev, bio); | |
296 | return; | |
297 | } | |
298 | ||
299 | rcu_read_lock(); | |
300 | tmp_dev = which_dev(mddev, bio->bi_sector); | |
301 | start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors; | |
302 | ||
303 | ||
304 | if (unlikely(bio->bi_sector >= (tmp_dev->end_sector) | |
305 | || (bio->bi_sector < start_sector))) { | |
306 | char b[BDEVNAME_SIZE]; | |
307 | ||
308 | printk(KERN_ERR | |
309 | "md/linear:%s: make_request: Sector %llu out of bounds on " | |
310 | "dev %s: %llu sectors, offset %llu\n", | |
311 | mdname(mddev), | |
312 | (unsigned long long)bio->bi_sector, | |
313 | bdevname(tmp_dev->rdev->bdev, b), | |
314 | (unsigned long long)tmp_dev->rdev->sectors, | |
315 | (unsigned long long)start_sector); | |
316 | rcu_read_unlock(); | |
317 | bio_io_error(bio); | |
318 | return; | |
319 | } | |
320 | if (unlikely(bio_end_sector(bio) > tmp_dev->end_sector)) { | |
321 | /* This bio crosses a device boundary, so we have to | |
322 | * split it. | |
323 | */ | |
324 | struct bio_pair *bp; | |
325 | sector_t end_sector = tmp_dev->end_sector; | |
326 | ||
327 | rcu_read_unlock(); | |
328 | ||
329 | bp = bio_split(bio, end_sector - bio->bi_sector); | |
330 | ||
331 | linear_make_request(mddev, &bp->bio1); | |
332 | linear_make_request(mddev, &bp->bio2); | |
333 | bio_pair_release(bp); | |
334 | return; | |
335 | } | |
336 | ||
337 | bio->bi_bdev = tmp_dev->rdev->bdev; | |
338 | bio->bi_sector = bio->bi_sector - start_sector | |
339 | + tmp_dev->rdev->data_offset; | |
340 | rcu_read_unlock(); | |
341 | ||
342 | if (unlikely((bio->bi_rw & REQ_DISCARD) && | |
343 | !blk_queue_discard(bdev_get_queue(bio->bi_bdev)))) { | |
344 | /* Just ignore it */ | |
345 | bio_endio(bio, 0); | |
346 | return; | |
347 | } | |
348 | ||
349 | generic_make_request(bio); | |
350 | } | |
351 | ||
352 | static void linear_status (struct seq_file *seq, struct mddev *mddev) | |
353 | { | |
354 | ||
355 | seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2); | |
356 | } | |
357 | ||
358 | ||
359 | static struct md_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_DESCRIPTION("Linear device concatenation personality for MD"); | |
387 | MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/ | |
388 | MODULE_ALIAS("md-linear"); | |
389 | MODULE_ALIAS("md-level--1"); |