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 */
which_dev(struct mddev * mddev,sector_t sector)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 */
linear_mergeable_bvec(struct request_queue * q,struct bvec_merge_data * bvm,struct bio_vec * biovec)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
linear_congested(void * data,int bits)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
linear_size(struct mddev * mddev,sector_t sectors,int raid_disks)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
linear_conf(struct mddev * mddev,int raid_disks)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
142 conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
143 GFP_KERNEL);
144 if (!conf)
145 return NULL;
146
147 cnt = 0;
148 conf->array_sectors = 0;
149
150 rdev_for_each(rdev, mddev) {
151 int j = rdev->raid_disk;
152 struct dev_info *disk = conf->disks + j;
153 sector_t sectors;
154
155 if (j < 0 || j >= raid_disks || disk->rdev) {
156 printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
157 mdname(mddev));
158 goto out;
159 }
160
161 disk->rdev = rdev;
162 if (mddev->chunk_sectors) {
163 sectors = rdev->sectors;
164 sector_div(sectors, mddev->chunk_sectors);
165 rdev->sectors = sectors * mddev->chunk_sectors;
166 }
167
168 disk_stack_limits(mddev->gendisk, rdev->bdev,
169 rdev->data_offset << 9);
170
171 conf->array_sectors += rdev->sectors;
172 cnt++;
173
174 }
175 if (cnt != raid_disks) {
176 printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
177 mdname(mddev));
178 goto out;
179 }
180
181 /*
182 * Here we calculate the device offsets.
183 */
184 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
185
186 for (i = 1; i < raid_disks; i++)
187 conf->disks[i].end_sector =
188 conf->disks[i-1].end_sector +
189 conf->disks[i].rdev->sectors;
190
191 return conf;
192
193 out:
194 kfree(conf);
195 return NULL;
196 }
197
linear_run(struct mddev * mddev)198 static int linear_run (struct mddev *mddev)
199 {
200 struct linear_conf *conf;
201 int ret;
202
203 if (md_check_no_bitmap(mddev))
204 return -EINVAL;
205 conf = linear_conf(mddev, mddev->raid_disks);
206
207 if (!conf)
208 return 1;
209 mddev->private = conf;
210 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
211
212 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
213 mddev->queue->backing_dev_info.congested_fn = linear_congested;
214 mddev->queue->backing_dev_info.congested_data = mddev;
215
216 ret = md_integrity_register(mddev);
217 if (ret) {
218 kfree(conf);
219 mddev->private = NULL;
220 }
221 return ret;
222 }
223
linear_add(struct mddev * mddev,struct md_rdev * rdev)224 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
225 {
226 /* Adding a drive to a linear array allows the array to grow.
227 * It is permitted if the new drive has a matching superblock
228 * already on it, with raid_disk equal to raid_disks.
229 * It is achieved by creating a new linear_private_data structure
230 * and swapping it in in-place of the current one.
231 * The current one is never freed until the array is stopped.
232 * This avoids races.
233 */
234 struct linear_conf *newconf, *oldconf;
235
236 if (rdev->saved_raid_disk != mddev->raid_disks)
237 return -EINVAL;
238
239 rdev->raid_disk = rdev->saved_raid_disk;
240 rdev->saved_raid_disk = -1;
241
242 newconf = linear_conf(mddev,mddev->raid_disks+1);
243
244 if (!newconf)
245 return -ENOMEM;
246
247 oldconf = rcu_dereference(mddev->private);
248 mddev->raid_disks++;
249 rcu_assign_pointer(mddev->private, newconf);
250 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
251 set_capacity(mddev->gendisk, mddev->array_sectors);
252 revalidate_disk(mddev->gendisk);
253 kfree_rcu(oldconf, rcu);
254 return 0;
255 }
256
linear_stop(struct mddev * mddev)257 static int linear_stop (struct mddev *mddev)
258 {
259 struct linear_conf *conf = mddev->private;
260
261 /*
262 * We do not require rcu protection here since
263 * we hold reconfig_mutex for both linear_add and
264 * linear_stop, so they cannot race.
265 * We should make sure any old 'conf's are properly
266 * freed though.
267 */
268 rcu_barrier();
269 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
270 kfree(conf);
271 mddev->private = NULL;
272
273 return 0;
274 }
275
linear_make_request(struct mddev * mddev,struct bio * bio)276 static void linear_make_request(struct mddev *mddev, struct bio *bio)
277 {
278 struct dev_info *tmp_dev;
279 sector_t start_sector;
280
281 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
282 md_flush_request(mddev, bio);
283 return;
284 }
285
286 rcu_read_lock();
287 tmp_dev = which_dev(mddev, bio->bi_sector);
288 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
289
290
291 if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
292 || (bio->bi_sector < start_sector))) {
293 char b[BDEVNAME_SIZE];
294
295 printk(KERN_ERR
296 "md/linear:%s: make_request: Sector %llu out of bounds on "
297 "dev %s: %llu sectors, offset %llu\n",
298 mdname(mddev),
299 (unsigned long long)bio->bi_sector,
300 bdevname(tmp_dev->rdev->bdev, b),
301 (unsigned long long)tmp_dev->rdev->sectors,
302 (unsigned long long)start_sector);
303 rcu_read_unlock();
304 bio_io_error(bio);
305 return;
306 }
307 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
308 tmp_dev->end_sector)) {
309 /* This bio crosses a device boundary, so we have to
310 * split it.
311 */
312 struct bio_pair *bp;
313 sector_t end_sector = tmp_dev->end_sector;
314
315 rcu_read_unlock();
316
317 bp = bio_split(bio, end_sector - bio->bi_sector);
318
319 linear_make_request(mddev, &bp->bio1);
320 linear_make_request(mddev, &bp->bio2);
321 bio_pair_release(bp);
322 return;
323 }
324
325 bio->bi_bdev = tmp_dev->rdev->bdev;
326 bio->bi_sector = bio->bi_sector - start_sector
327 + tmp_dev->rdev->data_offset;
328 rcu_read_unlock();
329 generic_make_request(bio);
330 }
331
linear_status(struct seq_file * seq,struct mddev * mddev)332 static void linear_status (struct seq_file *seq, struct mddev *mddev)
333 {
334
335 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
336 }
337
338
339 static struct md_personality linear_personality =
340 {
341 .name = "linear",
342 .level = LEVEL_LINEAR,
343 .owner = THIS_MODULE,
344 .make_request = linear_make_request,
345 .run = linear_run,
346 .stop = linear_stop,
347 .status = linear_status,
348 .hot_add_disk = linear_add,
349 .size = linear_size,
350 };
351
linear_init(void)352 static int __init linear_init (void)
353 {
354 return register_md_personality (&linear_personality);
355 }
356
linear_exit(void)357 static void linear_exit (void)
358 {
359 unregister_md_personality (&linear_personality);
360 }
361
362
363 module_init(linear_init);
364 module_exit(linear_exit);
365 MODULE_LICENSE("GPL");
366 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
367 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
368 MODULE_ALIAS("md-linear");
369 MODULE_ALIAS("md-level--1");
370