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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
NeilBrownbff61972009-03-31 14:33:13 +110019#include <linux/blkdev.h>
20#include <linux/raid/md_u.h>
NeilBrownbff61972009-03-31 14:33:13 +110021#include <linux/seq_file.h>
Paul Gortmaker056075c2011-07-03 13:58:33 -040022#include <linux/module.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090023#include <linux/slab.h>
NeilBrown43b2e5d2009-03-31 14:33:13 +110024#include "md.h"
Christoph Hellwigef740c32009-03-31 14:27:03 +110025#include "linear.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
Linus Torvalds1da177e2005-04-16 15:20:36 -070027/*
28 * find which device holds a particular offset
29 */
NeilBrowna7120772011-10-11 16:48:49 +110030static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
Linus Torvalds1da177e2005-04-16 15:20:36 -070031{
Sandeep K Sinhaaece3d12009-06-16 16:57:08 +100032 int lo, mid, hi;
NeilBrowne849b932011-10-11 16:48:54 +110033 struct linear_conf *conf;
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Sandeep K Sinhaaece3d12009-06-16 16:57:08 +100035 lo = 0;
36 hi = mddev->raid_disks - 1;
SandeepKsinhaaf11c392009-06-18 08:49:35 +100037 conf = rcu_dereference(mddev->private);
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
Sandeep K Sinhaaece3d12009-06-16 16:57:08 +100039 /*
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;
Linus Torvalds1da177e2005-04-16 15:20:36 -070053}
54
55/**
NeilBrown15945fe2005-09-09 16:23:47 -070056 * linear_mergeable_bvec -- tell bio layer if two requests can be merged
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 * @q: request queue
Alasdair G Kergoncc371e62008-07-03 09:53:43 +020058 * @bvm: properties of new bio
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 * @biovec: the request that could be merged to it.
60 *
61 * Return amount of bytes we can take at this offset
62 */
Alasdair G Kergoncc371e62008-07-03 09:53:43 +020063static int linear_mergeable_bvec(struct request_queue *q,
64 struct bvec_merge_data *bvm,
65 struct bio_vec *biovec)
Linus Torvalds1da177e2005-04-16 15:20:36 -070066{
NeilBrownfd01b882011-10-11 16:47:53 +110067 struct mddev *mddev = q->queuedata;
NeilBrowna7120772011-10-11 16:48:49 +110068 struct dev_info *dev0;
Alasdair G Kergoncc371e62008-07-03 09:53:43 +020069 unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
70 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
NeilBrownba13da42012-03-19 12:46:39 +110071 int maxbytes = biovec->bv_len;
72 struct request_queue *subq;
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
SandeepKsinhaaf11c392009-06-18 08:49:35 +100074 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 dev0 = which_dev(mddev, sector);
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +100076 maxsectors = dev0->end_sector - sector;
NeilBrownba13da42012-03-19 12:46:39 +110077 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 }
SandeepKsinhaaf11c392009-06-18 08:49:35 +100084 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
86 if (maxsectors < bio_sectors)
87 maxsectors = 0;
88 else
89 maxsectors -= bio_sectors;
90
91 if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
NeilBrownba13da42012-03-19 12:46:39 +110092 return maxbytes;
93
94 if (maxsectors > (maxbytes >> 9))
95 return maxbytes;
96 else
97 return maxsectors << 9;
Linus Torvalds1da177e2005-04-16 15:20:36 -070098}
99
NeilBrown26be34d2006-10-03 01:15:53 -0700100static int linear_congested(void *data, int bits)
101{
NeilBrownfd01b882011-10-11 16:47:53 +1100102 struct mddev *mddev = data;
NeilBrowne849b932011-10-11 16:48:54 +1100103 struct linear_conf *conf;
NeilBrown26be34d2006-10-03 01:15:53 -0700104 int i, ret = 0;
105
NeilBrown3fa841d2009-09-23 18:10:29 +1000106 if (mddev_congested(mddev, bits))
107 return 1;
108
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000109 rcu_read_lock();
110 conf = rcu_dereference(mddev->private);
111
NeilBrown26be34d2006-10-03 01:15:53 -0700112 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
Jens Axboe165125e2007-07-24 09:28:11 +0200113 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
NeilBrown26be34d2006-10-03 01:15:53 -0700114 ret |= bdi_congested(&q->backing_dev_info, bits);
115 }
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000116
117 rcu_read_unlock();
NeilBrown26be34d2006-10-03 01:15:53 -0700118 return ret;
119}
120
NeilBrownfd01b882011-10-11 16:47:53 +1100121static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
Dan Williams80c3a6c2009-03-17 18:10:40 -0700122{
NeilBrowne849b932011-10-11 16:48:54 +1100123 struct linear_conf *conf;
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000124 sector_t array_sectors;
Dan Williams80c3a6c2009-03-17 18:10:40 -0700125
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000126 rcu_read_lock();
127 conf = rcu_dereference(mddev->private);
Dan Williams80c3a6c2009-03-17 18:10:40 -0700128 WARN_ONCE(sectors || raid_disks,
129 "%s does not support generic reshape\n", __func__);
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000130 array_sectors = conf->array_sectors;
131 rcu_read_unlock();
Dan Williams80c3a6c2009-03-17 18:10:40 -0700132
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000133 return array_sectors;
Dan Williams80c3a6c2009-03-17 18:10:40 -0700134}
135
NeilBrowne849b932011-10-11 16:48:54 +1100136static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137{
NeilBrowne849b932011-10-11 16:48:54 +1100138 struct linear_conf *conf;
NeilBrown3cb03002011-10-11 16:45:26 +1100139 struct md_rdev *rdev;
Sandeep K Sinha45d45822009-06-16 16:55:26 +1000140 int i, cnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
NeilBrowna7120772011-10-11 16:48:49 +1100142 conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 GFP_KERNEL);
144 if (!conf)
NeilBrown7c7546c2006-06-26 00:27:41 -0700145 return NULL;
146
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 cnt = 0;
Andre Nolld6e22152008-07-21 17:05:25 +1000148 conf->array_sectors = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
NeilBrowndafb20f2012-03-19 12:46:39 +1100150 rdev_for_each(rdev, mddev) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 int j = rdev->raid_disk;
NeilBrowna7120772011-10-11 16:48:49 +1100152 struct dev_info *disk = conf->disks + j;
NeilBrown13f26822009-06-18 08:48:55 +1000153 sector_t sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Nikanth Karthikesan13864512008-06-28 08:31:19 +1000155 if (j < 0 || j >= raid_disks || disk->rdev) {
NeilBrown2dc40f82010-05-03 15:12:04 +1000156 printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
157 mdname(mddev));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 goto out;
159 }
160
161 disk->rdev = rdev;
NeilBrown13f26822009-06-18 08:48:55 +1000162 if (mddev->chunk_sectors) {
163 sectors = rdev->sectors;
164 sector_div(sectors, mddev->chunk_sectors);
165 rdev->sectors = sectors * mddev->chunk_sectors;
166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167
Martin K. Petersen8f6c2e42009-07-01 11:13:45 +1000168 disk_stack_limits(mddev->gendisk, rdev->bdev,
169 rdev->data_offset << 9);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
Andre Nolldd8ac332009-03-31 14:33:13 +1100171 conf->array_sectors += rdev->sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 cnt++;
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 }
NeilBrown7c7546c2006-06-26 00:27:41 -0700175 if (cnt != raid_disks) {
NeilBrown2dc40f82010-05-03 15:12:04 +1000176 printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
177 mdname(mddev));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 goto out;
179 }
180
181 /*
Sandeep K Sinha45d45822009-06-16 16:55:26 +1000182 * Here we calculate the device offsets.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 */
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000184 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
185
NeilBrowna778b732007-05-23 13:58:10 -0700186 for (i = 1; i < raid_disks; i++)
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000187 conf->disks[i].end_sector =
188 conf->disks[i-1].end_sector +
189 conf->disks[i].rdev->sectors;
NeilBrown15945fe2005-09-09 16:23:47 -0700190
NeilBrown7c7546c2006-06-26 00:27:41 -0700191 return conf;
192
193out:
194 kfree(conf);
195 return NULL;
196}
197
NeilBrownfd01b882011-10-11 16:47:53 +1100198static int linear_run (struct mddev *mddev)
NeilBrown7c7546c2006-06-26 00:27:41 -0700199{
NeilBrowne849b932011-10-11 16:48:54 +1100200 struct linear_conf *conf;
NeilBrown7c7546c2006-06-26 00:27:41 -0700201
Andre Noll0894cc32009-06-18 08:49:23 +1000202 if (md_check_no_bitmap(mddev))
203 return -EINVAL;
NeilBrown7c7546c2006-06-26 00:27:41 -0700204 conf = linear_conf(mddev, mddev->raid_disks);
205
206 if (!conf)
207 return 1;
208 mddev->private = conf;
Dan Williams1f403622009-03-31 14:59:03 +1100209 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
NeilBrown7c7546c2006-06-26 00:27:41 -0700210
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
NeilBrown26be34d2006-10-03 01:15:53 -0700212 mddev->queue->backing_dev_info.congested_fn = linear_congested;
213 mddev->queue->backing_dev_info.congested_data = mddev;
Martin K. Petersena91a2782011-03-17 11:11:05 +0100214 return md_integrity_register(mddev);
NeilBrown7c7546c2006-06-26 00:27:41 -0700215}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
NeilBrownfd01b882011-10-11 16:47:53 +1100217static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
NeilBrown7c7546c2006-06-26 00:27:41 -0700218{
219 /* Adding a drive to a linear array allows the array to grow.
220 * It is permitted if the new drive has a matching superblock
221 * already on it, with raid_disk equal to raid_disks.
222 * It is achieved by creating a new linear_private_data structure
223 * and swapping it in in-place of the current one.
224 * The current one is never freed until the array is stopped.
225 * This avoids races.
226 */
NeilBrowne849b932011-10-11 16:48:54 +1100227 struct linear_conf *newconf, *oldconf;
NeilBrown7c7546c2006-06-26 00:27:41 -0700228
NeilBrowna778b732007-05-23 13:58:10 -0700229 if (rdev->saved_raid_disk != mddev->raid_disks)
NeilBrown7c7546c2006-06-26 00:27:41 -0700230 return -EINVAL;
231
NeilBrowna778b732007-05-23 13:58:10 -0700232 rdev->raid_disk = rdev->saved_raid_disk;
NeilBrown09cd9272011-12-23 09:56:55 +1100233 rdev->saved_raid_disk = -1;
NeilBrowna778b732007-05-23 13:58:10 -0700234
NeilBrown7c7546c2006-06-26 00:27:41 -0700235 newconf = linear_conf(mddev,mddev->raid_disks+1);
236
237 if (!newconf)
238 return -ENOMEM;
239
NeilBrown495d3572009-06-18 08:49:42 +1000240 oldconf = rcu_dereference(mddev->private);
NeilBrown7c7546c2006-06-26 00:27:41 -0700241 mddev->raid_disks++;
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000242 rcu_assign_pointer(mddev->private, newconf);
Dan Williams1f403622009-03-31 14:59:03 +1100243 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
Andre Nollf233ea52008-07-21 17:05:22 +1000244 set_capacity(mddev->gendisk, mddev->array_sectors);
NeilBrown449aad32009-08-03 10:59:58 +1000245 revalidate_disk(mddev->gendisk);
Lai Jiangshanb119cba2011-03-18 11:59:14 +0800246 kfree_rcu(oldconf, rcu);
NeilBrown7c7546c2006-06-26 00:27:41 -0700247 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248}
249
NeilBrownfd01b882011-10-11 16:47:53 +1100250static int linear_stop (struct mddev *mddev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251{
NeilBrowne849b932011-10-11 16:48:54 +1100252 struct linear_conf *conf = mddev->private;
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000253
254 /*
255 * We do not require rcu protection here since
256 * we hold reconfig_mutex for both linear_add and
257 * linear_stop, so they cannot race.
NeilBrown495d3572009-06-18 08:49:42 +1000258 * We should make sure any old 'conf's are properly
259 * freed though.
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000260 */
NeilBrown495d3572009-06-18 08:49:42 +1000261 rcu_barrier();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
NeilBrown495d3572009-06-18 08:49:42 +1000263 kfree(conf);
NeilBrownef2f80f2010-05-17 11:27:00 +1000264 mddev->private = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
266 return 0;
267}
268
Linus Torvaldsb4fdcb02011-11-04 17:06:58 -0700269static void linear_make_request(struct mddev *mddev, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270{
NeilBrowna7120772011-10-11 16:48:49 +1100271 struct dev_info *tmp_dev;
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000272 sector_t start_sector;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Tejun Heoe9c74692010-09-03 11:56:18 +0200274 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
275 md_flush_request(mddev, bio);
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +0200276 return;
NeilBrowne5dcdd82005-09-09 16:23:41 -0700277 }
278
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000279 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 tmp_dev = which_dev(mddev, bio->bi_sector);
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000281 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
282
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000283
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000284 if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
285 || (bio->bi_sector < start_sector))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 char b[BDEVNAME_SIZE];
287
NeilBrown2dc40f82010-05-03 15:12:04 +1000288 printk(KERN_ERR
289 "md/linear:%s: make_request: Sector %llu out of bounds on "
290 "dev %s: %llu sectors, offset %llu\n",
291 mdname(mddev),
292 (unsigned long long)bio->bi_sector,
293 bdevname(tmp_dev->rdev->bdev, b),
294 (unsigned long long)tmp_dev->rdev->sectors,
295 (unsigned long long)start_sector);
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000296 rcu_read_unlock();
NeilBrown6712ecf2007-09-27 12:47:43 +0200297 bio_io_error(bio);
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +0200298 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 }
300 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000301 tmp_dev->end_sector)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 /* This bio crosses a device boundary, so we have to
303 * split it.
304 */
305 struct bio_pair *bp;
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000306 sector_t end_sector = tmp_dev->end_sector;
Andre Noll62838152008-10-13 11:55:12 +1100307
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000308 rcu_read_unlock();
309
310 bp = bio_split(bio, end_sector - bio->bi_sector);
Andre Noll62838152008-10-13 11:55:12 +1100311
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +0200312 linear_make_request(mddev, &bp->bio1);
313 linear_make_request(mddev, &bp->bio2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 bio_pair_release(bp);
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +0200315 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 }
317
318 bio->bi_bdev = tmp_dev->rdev->bdev;
Sandeep K Sinha4db7cdc2009-06-16 16:56:13 +1000319 bio->bi_sector = bio->bi_sector - start_sector
Andre Noll62838152008-10-13 11:55:12 +1100320 + tmp_dev->rdev->data_offset;
SandeepKsinhaaf11c392009-06-18 08:49:35 +1000321 rcu_read_unlock();
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +0200322 generic_make_request(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323}
324
NeilBrownfd01b882011-10-11 16:47:53 +1100325static void linear_status (struct seq_file *seq, struct mddev *mddev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326{
327
Andre Noll9d8f0362009-06-18 08:45:01 +1000328 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329}
330
331
NeilBrown84fc4b52011-10-11 16:49:58 +1100332static struct md_personality linear_personality =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
334 .name = "linear",
NeilBrown2604b702006-01-06 00:20:36 -0800335 .level = LEVEL_LINEAR,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 .owner = THIS_MODULE,
337 .make_request = linear_make_request,
338 .run = linear_run,
339 .stop = linear_stop,
340 .status = linear_status,
NeilBrown7c7546c2006-06-26 00:27:41 -0700341 .hot_add_disk = linear_add,
Dan Williams80c3a6c2009-03-17 18:10:40 -0700342 .size = linear_size,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343};
344
345static int __init linear_init (void)
346{
NeilBrown2604b702006-01-06 00:20:36 -0800347 return register_md_personality (&linear_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348}
349
350static void linear_exit (void)
351{
NeilBrown2604b702006-01-06 00:20:36 -0800352 unregister_md_personality (&linear_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353}
354
355
356module_init(linear_init);
357module_exit(linear_exit);
358MODULE_LICENSE("GPL");
NeilBrown0efb9e62009-12-14 12:49:58 +1100359MODULE_DESCRIPTION("Linear device concatenation personality for MD");
NeilBrownd9d166c2006-01-06 00:20:51 -0800360MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
361MODULE_ALIAS("md-linear");
NeilBrown2604b702006-01-06 00:20:36 -0800362MODULE_ALIAS("md-level--1");