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CommitLineData
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
bff61975
N
19#include <linux/blkdev.h>
20#include <linux/raid/md_u.h>
bff61975 21#include <linux/seq_file.h>
5a0e3ad6 22#include <linux/slab.h>
43b2e5d8 23#include "md.h"
ef740c37 24#include "linear.h"
1da177e4 25
1da177e4
LT
26/*
27 * find which device holds a particular offset
28 */
29static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
30{
aece3d1f 31 int lo, mid, hi;
af11c397 32 linear_conf_t *conf;
1da177e4 33
aece3d1f
SS
34 lo = 0;
35 hi = mddev->raid_disks - 1;
af11c397 36 conf = rcu_dereference(mddev->private);
1da177e4 37
aece3d1f
SS
38 /*
39 * Binary Search
40 */
41
42 while (hi > lo) {
43
44 mid = (hi + lo) / 2;
45 if (sector < conf->disks[mid].end_sector)
46 hi = mid;
47 else
48 lo = mid + 1;
49 }
50
51 return conf->disks + lo;
1da177e4
LT
52}
53
54/**
15945fee 55 * linear_mergeable_bvec -- tell bio layer if two requests can be merged
1da177e4 56 * @q: request queue
cc371e66 57 * @bvm: properties of new bio
1da177e4
LT
58 * @biovec: the request that could be merged to it.
59 *
60 * Return amount of bytes we can take at this offset
61 */
cc371e66
AK
62static int linear_mergeable_bvec(struct request_queue *q,
63 struct bvec_merge_data *bvm,
64 struct bio_vec *biovec)
1da177e4
LT
65{
66 mddev_t *mddev = q->queuedata;
67 dev_info_t *dev0;
cc371e66
AK
68 unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
69 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
1da177e4 70
af11c397 71 rcu_read_lock();
1da177e4 72 dev0 = which_dev(mddev, sector);
4db7cdc8 73 maxsectors = dev0->end_sector - sector;
af11c397 74 rcu_read_unlock();
1da177e4
LT
75
76 if (maxsectors < bio_sectors)
77 maxsectors = 0;
78 else
79 maxsectors -= bio_sectors;
80
81 if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
82 return biovec->bv_len;
83 /* The bytes available at this offset could be really big,
84 * so we cap at 2^31 to avoid overflow */
85 if (maxsectors > (1 << (31-9)))
86 return 1<<31;
87 return maxsectors << 9;
88}
89
165125e1 90static void linear_unplug(struct request_queue *q)
1da177e4
LT
91{
92 mddev_t *mddev = q->queuedata;
af11c397 93 linear_conf_t *conf;
1da177e4
LT
94 int i;
95
af11c397
S
96 rcu_read_lock();
97 conf = rcu_dereference(mddev->private);
98
1da177e4 99 for (i=0; i < mddev->raid_disks; i++) {
165125e1 100 struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
2ad8b1ef 101 blk_unplug(r_queue);
1da177e4 102 }
af11c397 103 rcu_read_unlock();
1da177e4
LT
104}
105
26be34dc
N
106static int linear_congested(void *data, int bits)
107{
108 mddev_t *mddev = data;
af11c397 109 linear_conf_t *conf;
26be34dc
N
110 int i, ret = 0;
111
3fa841d7
N
112 if (mddev_congested(mddev, bits))
113 return 1;
114
af11c397
S
115 rcu_read_lock();
116 conf = rcu_dereference(mddev->private);
117
26be34dc 118 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
165125e1 119 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
26be34dc
N
120 ret |= bdi_congested(&q->backing_dev_info, bits);
121 }
af11c397
S
122
123 rcu_read_unlock();
26be34dc
N
124 return ret;
125}
126
80c3a6ce
DW
127static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks)
128{
af11c397
S
129 linear_conf_t *conf;
130 sector_t array_sectors;
80c3a6ce 131
af11c397
S
132 rcu_read_lock();
133 conf = rcu_dereference(mddev->private);
80c3a6ce
DW
134 WARN_ONCE(sectors || raid_disks,
135 "%s does not support generic reshape\n", __func__);
af11c397
S
136 array_sectors = conf->array_sectors;
137 rcu_read_unlock();
80c3a6ce 138
af11c397 139 return array_sectors;
80c3a6ce
DW
140}
141
7c7546cc 142static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
1da177e4
LT
143{
144 linear_conf_t *conf;
1da177e4 145 mdk_rdev_t *rdev;
45d4582f 146 int i, cnt;
1da177e4 147
7c7546cc 148 conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
1da177e4
LT
149 GFP_KERNEL);
150 if (!conf)
7c7546cc
N
151 return NULL;
152
1da177e4 153 cnt = 0;
d6e22150 154 conf->array_sectors = 0;
1da177e4 155
159ec1fc 156 list_for_each_entry(rdev, &mddev->disks, same_set) {
1da177e4
LT
157 int j = rdev->raid_disk;
158 dev_info_t *disk = conf->disks + j;
13f2682b 159 sector_t sectors;
1da177e4 160
13864515 161 if (j < 0 || j >= raid_disks || disk->rdev) {
2dc40f80
N
162 printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
163 mdname(mddev));
1da177e4
LT
164 goto out;
165 }
166
167 disk->rdev = rdev;
13f2682b
N
168 if (mddev->chunk_sectors) {
169 sectors = rdev->sectors;
170 sector_div(sectors, mddev->chunk_sectors);
171 rdev->sectors = sectors * mddev->chunk_sectors;
172 }
1da177e4 173
8f6c2e4b
MP
174 disk_stack_limits(mddev->gendisk, rdev->bdev,
175 rdev->data_offset << 9);
1da177e4 176 /* as we don't honour merge_bvec_fn, we must never risk
627a2d3c
N
177 * violating it, so limit max_segments to 1 lying within
178 * a single page.
1da177e4 179 */
627a2d3c
N
180 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
181 blk_queue_max_segments(mddev->queue, 1);
182 blk_queue_segment_boundary(mddev->queue,
183 PAGE_CACHE_SIZE - 1);
184 }
1da177e4 185
dd8ac336 186 conf->array_sectors += rdev->sectors;
1da177e4 187 cnt++;
4db7cdc8 188
1da177e4 189 }
7c7546cc 190 if (cnt != raid_disks) {
2dc40f80
N
191 printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
192 mdname(mddev));
1da177e4
LT
193 goto out;
194 }
195
196 /*
45d4582f 197 * Here we calculate the device offsets.
1da177e4 198 */
4db7cdc8
SS
199 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
200
a778b73f 201 for (i = 1; i < raid_disks; i++)
4db7cdc8
SS
202 conf->disks[i].end_sector =
203 conf->disks[i-1].end_sector +
204 conf->disks[i].rdev->sectors;
15945fee 205
7c7546cc
N
206 return conf;
207
208out:
209 kfree(conf);
210 return NULL;
211}
212
213static int linear_run (mddev_t *mddev)
214{
215 linear_conf_t *conf;
216
0894cc30
AN
217 if (md_check_no_bitmap(mddev))
218 return -EINVAL;
e7e72bf6 219 mddev->queue->queue_lock = &mddev->queue->__queue_lock;
7c7546cc
N
220 conf = linear_conf(mddev, mddev->raid_disks);
221
222 if (!conf)
223 return 1;
224 mddev->private = conf;
1f403624 225 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
7c7546cc 226
1da177e4
LT
227 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
228 mddev->queue->unplug_fn = linear_unplug;
26be34dc
N
229 mddev->queue->backing_dev_info.congested_fn = linear_congested;
230 mddev->queue->backing_dev_info.congested_data = mddev;
ac5e7113 231 md_integrity_register(mddev);
1da177e4 232 return 0;
7c7546cc 233}
1da177e4 234
495d3573
N
235static void free_conf(struct rcu_head *head)
236{
237 linear_conf_t *conf = container_of(head, linear_conf_t, rcu);
238 kfree(conf);
239}
240
7c7546cc
N
241static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
242{
243 /* Adding a drive to a linear array allows the array to grow.
244 * It is permitted if the new drive has a matching superblock
245 * already on it, with raid_disk equal to raid_disks.
246 * It is achieved by creating a new linear_private_data structure
247 * and swapping it in in-place of the current one.
248 * The current one is never freed until the array is stopped.
249 * This avoids races.
250 */
495d3573 251 linear_conf_t *newconf, *oldconf;
7c7546cc 252
a778b73f 253 if (rdev->saved_raid_disk != mddev->raid_disks)
7c7546cc
N
254 return -EINVAL;
255
a778b73f
N
256 rdev->raid_disk = rdev->saved_raid_disk;
257
7c7546cc
N
258 newconf = linear_conf(mddev,mddev->raid_disks+1);
259
260 if (!newconf)
261 return -ENOMEM;
262
495d3573 263 oldconf = rcu_dereference(mddev->private);
7c7546cc 264 mddev->raid_disks++;
af11c397 265 rcu_assign_pointer(mddev->private, newconf);
1f403624 266 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
f233ea5c 267 set_capacity(mddev->gendisk, mddev->array_sectors);
449aad3e 268 revalidate_disk(mddev->gendisk);
495d3573 269 call_rcu(&oldconf->rcu, free_conf);
7c7546cc 270 return 0;
1da177e4
LT
271}
272
273static int linear_stop (mddev_t *mddev)
274{
070ec55d 275 linear_conf_t *conf = mddev->private;
af11c397
S
276
277 /*
278 * We do not require rcu protection here since
279 * we hold reconfig_mutex for both linear_add and
280 * linear_stop, so they cannot race.
495d3573
N
281 * We should make sure any old 'conf's are properly
282 * freed though.
af11c397 283 */
495d3573 284 rcu_barrier();
1da177e4 285 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
495d3573 286 kfree(conf);
ef2f80ff 287 mddev->private = NULL;
1da177e4
LT
288
289 return 0;
290}
291
21a52c6d 292static int linear_make_request (mddev_t *mddev, struct bio *bio)
1da177e4 293{
1da177e4 294 dev_info_t *tmp_dev;
4db7cdc8 295 sector_t start_sector;
1da177e4 296
e9c7469b
TH
297 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
298 md_flush_request(mddev, bio);
e5dcdd80
N
299 return 0;
300 }
301
af11c397 302 rcu_read_lock();
1da177e4 303 tmp_dev = which_dev(mddev, bio->bi_sector);
4db7cdc8
SS
304 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
305
af11c397 306
4db7cdc8
SS
307 if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
308 || (bio->bi_sector < start_sector))) {
1da177e4
LT
309 char b[BDEVNAME_SIZE];
310
2dc40f80
N
311 printk(KERN_ERR
312 "md/linear:%s: make_request: Sector %llu out of bounds on "
313 "dev %s: %llu sectors, offset %llu\n",
314 mdname(mddev),
315 (unsigned long long)bio->bi_sector,
316 bdevname(tmp_dev->rdev->bdev, b),
317 (unsigned long long)tmp_dev->rdev->sectors,
318 (unsigned long long)start_sector);
af11c397 319 rcu_read_unlock();
6712ecf8 320 bio_io_error(bio);
1da177e4
LT
321 return 0;
322 }
323 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
4db7cdc8 324 tmp_dev->end_sector)) {
1da177e4
LT
325 /* This bio crosses a device boundary, so we have to
326 * split it.
327 */
328 struct bio_pair *bp;
af11c397
S
329 sector_t end_sector = tmp_dev->end_sector;
330
331 rcu_read_unlock();
6283815d 332
af11c397 333 bp = bio_split(bio, end_sector - bio->bi_sector);
6283815d 334
21a52c6d 335 if (linear_make_request(mddev, &bp->bio1))
1da177e4 336 generic_make_request(&bp->bio1);
21a52c6d 337 if (linear_make_request(mddev, &bp->bio2))
1da177e4
LT
338 generic_make_request(&bp->bio2);
339 bio_pair_release(bp);
340 return 0;
341 }
342
343 bio->bi_bdev = tmp_dev->rdev->bdev;
4db7cdc8 344 bio->bi_sector = bio->bi_sector - start_sector
6283815d 345 + tmp_dev->rdev->data_offset;
af11c397 346 rcu_read_unlock();
1da177e4
LT
347
348 return 1;
349}
350
351static void linear_status (struct seq_file *seq, mddev_t *mddev)
352{
353
9d8f0363 354 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
1da177e4
LT
355}
356
357
2604b703 358static struct mdk_personality linear_personality =
1da177e4
LT
359{
360 .name = "linear",
2604b703 361 .level = LEVEL_LINEAR,
1da177e4
LT
362 .owner = THIS_MODULE,
363 .make_request = linear_make_request,
364 .run = linear_run,
365 .stop = linear_stop,
366 .status = linear_status,
7c7546cc 367 .hot_add_disk = linear_add,
80c3a6ce 368 .size = linear_size,
1da177e4
LT
369};
370
371static int __init linear_init (void)
372{
2604b703 373 return register_md_personality (&linear_personality);
1da177e4
LT
374}
375
376static void linear_exit (void)
377{
2604b703 378 unregister_md_personality (&linear_personality);
1da177e4
LT
379}
380
381
382module_init(linear_init);
383module_exit(linear_exit);
384MODULE_LICENSE("GPL");
0efb9e61 385MODULE_DESCRIPTION("Linear device concatenation personality for MD");
d9d166c2
N
386MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
387MODULE_ALIAS("md-linear");
2604b703 388MODULE_ALIAS("md-level--1");