1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * linear.c : Multiple Devices driver for Linux Copyright (C) 1994-96 Marc
4 * ZYNGIER <zyngier@ufr-info-p7.ibp.fr> or <maz@gloups.fdn.fr>
5 */
6
7 #include <linux/blkdev.h>
8 #include <linux/seq_file.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <trace/events/block.h>
12 #include "md.h"
13
14 struct dev_info {
15 struct md_rdev *rdev;
16 sector_t end_sector;
17 };
18
19 struct linear_conf {
20 struct rcu_head rcu;
21 sector_t array_sectors;
22 /* a copy of mddev->raid_disks */
23 int raid_disks;
24 struct dev_info disks[] __counted_by(raid_disks);
25 };
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 = 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
linear_size(struct mddev * mddev,sector_t sectors,int raid_disks)55 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
56 {
57 struct linear_conf *conf;
58 sector_t array_sectors;
59
60 conf = mddev->private;
61 WARN_ONCE(sectors || raid_disks,
62 "%s does not support generic reshape\n", __func__);
63 array_sectors = conf->array_sectors;
64
65 return array_sectors;
66 }
67
linear_set_limits(struct mddev * mddev)68 static int linear_set_limits(struct mddev *mddev)
69 {
70 struct queue_limits lim;
71 int err;
72
73 md_init_stacking_limits(&lim);
74 lim.max_hw_sectors = mddev->chunk_sectors;
75 lim.max_write_zeroes_sectors = mddev->chunk_sectors;
76 lim.io_min = mddev->chunk_sectors << 9;
77 err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
78 if (err)
79 return err;
80
81 return queue_limits_set(mddev->gendisk->queue, &lim);
82 }
83
linear_conf(struct mddev * mddev,int raid_disks)84 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
85 {
86 struct linear_conf *conf;
87 struct md_rdev *rdev;
88 int ret = -EINVAL;
89 int cnt;
90 int i;
91
92 conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
93 if (!conf)
94 return ERR_PTR(-ENOMEM);
95
96 /*
97 * conf->raid_disks is copy of mddev->raid_disks. The reason to
98 * keep a copy of mddev->raid_disks in struct linear_conf is,
99 * mddev->raid_disks may not be consistent with pointers number of
100 * conf->disks[] when it is updated in linear_add() and used to
101 * iterate old conf->disks[] earray in linear_congested().
102 * Here conf->raid_disks is always consitent with number of
103 * pointers in conf->disks[] array, and mddev->private is updated
104 * with rcu_assign_pointer() in linear_addr(), such race can be
105 * avoided.
106 */
107 conf->raid_disks = raid_disks;
108
109 cnt = 0;
110 conf->array_sectors = 0;
111
112 rdev_for_each(rdev, mddev) {
113 int j = rdev->raid_disk;
114 struct dev_info *disk = conf->disks + j;
115 sector_t sectors;
116
117 if (j < 0 || j >= raid_disks || disk->rdev) {
118 pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
119 mdname(mddev));
120 goto out;
121 }
122
123 disk->rdev = rdev;
124 if (mddev->chunk_sectors) {
125 sectors = rdev->sectors;
126 sector_div(sectors, mddev->chunk_sectors);
127 rdev->sectors = sectors * mddev->chunk_sectors;
128 }
129
130 conf->array_sectors += rdev->sectors;
131 cnt++;
132 }
133 if (cnt != raid_disks) {
134 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
135 mdname(mddev));
136 goto out;
137 }
138
139 /*
140 * Here we calculate the device offsets.
141 */
142 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
143
144 for (i = 1; i < raid_disks; i++)
145 conf->disks[i].end_sector =
146 conf->disks[i-1].end_sector +
147 conf->disks[i].rdev->sectors;
148
149 if (!mddev_is_dm(mddev)) {
150 ret = linear_set_limits(mddev);
151 if (ret)
152 goto out;
153 }
154
155 return conf;
156
157 out:
158 kfree(conf);
159 return ERR_PTR(ret);
160 }
161
linear_run(struct mddev * mddev)162 static int linear_run(struct mddev *mddev)
163 {
164 struct linear_conf *conf;
165 int ret;
166
167 if (md_check_no_bitmap(mddev))
168 return -EINVAL;
169
170 conf = linear_conf(mddev, mddev->raid_disks);
171 if (IS_ERR(conf))
172 return PTR_ERR(conf);
173
174 mddev->private = conf;
175 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
176
177 ret = md_integrity_register(mddev);
178 if (ret) {
179 kfree(conf);
180 mddev->private = NULL;
181 }
182 return ret;
183 }
184
linear_add(struct mddev * mddev,struct md_rdev * rdev)185 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
186 {
187 /* Adding a drive to a linear array allows the array to grow.
188 * It is permitted if the new drive has a matching superblock
189 * already on it, with raid_disk equal to raid_disks.
190 * It is achieved by creating a new linear_private_data structure
191 * and swapping it in in-place of the current one.
192 * The current one is never freed until the array is stopped.
193 * This avoids races.
194 */
195 struct linear_conf *newconf, *oldconf;
196
197 if (rdev->saved_raid_disk != mddev->raid_disks)
198 return -EINVAL;
199
200 rdev->raid_disk = rdev->saved_raid_disk;
201 rdev->saved_raid_disk = -1;
202
203 newconf = linear_conf(mddev, mddev->raid_disks + 1);
204 if (IS_ERR(newconf))
205 return PTR_ERR(newconf);
206
207 /* newconf->raid_disks already keeps a copy of * the increased
208 * value of mddev->raid_disks, WARN_ONCE() is just used to make
209 * sure of this. It is possible that oldconf is still referenced
210 * in linear_congested(), therefore kfree_rcu() is used to free
211 * oldconf until no one uses it anymore.
212 */
213 oldconf = rcu_dereference_protected(mddev->private,
214 lockdep_is_held(&mddev->reconfig_mutex));
215 mddev->raid_disks++;
216 WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
217 "copied raid_disks doesn't match mddev->raid_disks");
218 rcu_assign_pointer(mddev->private, newconf);
219 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
220 set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
221 kfree_rcu(oldconf, rcu);
222 return 0;
223 }
224
linear_free(struct mddev * mddev,void * priv)225 static void linear_free(struct mddev *mddev, void *priv)
226 {
227 struct linear_conf *conf = priv;
228
229 kfree(conf);
230 }
231
linear_make_request(struct mddev * mddev,struct bio * bio)232 static bool linear_make_request(struct mddev *mddev, struct bio *bio)
233 {
234 struct dev_info *tmp_dev;
235 sector_t start_sector, end_sector, data_offset;
236 sector_t bio_sector = bio->bi_iter.bi_sector;
237
238 if (unlikely(bio->bi_opf & REQ_PREFLUSH)
239 && md_flush_request(mddev, bio))
240 return true;
241
242 tmp_dev = which_dev(mddev, bio_sector);
243 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
244 end_sector = tmp_dev->end_sector;
245 data_offset = tmp_dev->rdev->data_offset;
246
247 if (unlikely(bio_sector >= end_sector ||
248 bio_sector < start_sector))
249 goto out_of_bounds;
250
251 if (unlikely(is_rdev_broken(tmp_dev->rdev))) {
252 md_error(mddev, tmp_dev->rdev);
253 bio_io_error(bio);
254 return true;
255 }
256
257 if (unlikely(bio_end_sector(bio) > end_sector)) {
258 /* This bio crosses a device boundary, so we have to split it */
259 struct bio *split = bio_split(bio, end_sector - bio_sector,
260 GFP_NOIO, &mddev->bio_set);
261
262 if (IS_ERR(split)) {
263 bio->bi_status = errno_to_blk_status(PTR_ERR(split));
264 bio_endio(bio);
265 return true;
266 }
267
268 bio_chain(split, bio);
269 submit_bio_noacct(bio);
270 bio = split;
271 }
272
273 md_account_bio(mddev, &bio);
274 bio_set_dev(bio, tmp_dev->rdev->bdev);
275 bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
276 start_sector + data_offset;
277
278 if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
279 !bdev_max_discard_sectors(bio->bi_bdev))) {
280 /* Just ignore it */
281 bio_endio(bio);
282 } else {
283 if (mddev->gendisk)
284 trace_block_bio_remap(bio, disk_devt(mddev->gendisk),
285 bio_sector);
286 mddev_check_write_zeroes(mddev, bio);
287 submit_bio_noacct(bio);
288 }
289 return true;
290
291 out_of_bounds:
292 pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %pg: %llu sectors, offset %llu\n",
293 mdname(mddev),
294 (unsigned long long)bio->bi_iter.bi_sector,
295 tmp_dev->rdev->bdev,
296 (unsigned long long)tmp_dev->rdev->sectors,
297 (unsigned long long)start_sector);
298 bio_io_error(bio);
299 return true;
300 }
301
linear_status(struct seq_file * seq,struct mddev * mddev)302 static void linear_status(struct seq_file *seq, struct mddev *mddev)
303 {
304 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
305 }
306
linear_error(struct mddev * mddev,struct md_rdev * rdev)307 static void linear_error(struct mddev *mddev, struct md_rdev *rdev)
308 {
309 if (!test_and_set_bit(MD_BROKEN, &mddev->flags)) {
310 char *md_name = mdname(mddev);
311
312 pr_crit("md/linear%s: Disk failure on %pg detected, failing array.\n",
313 md_name, rdev->bdev);
314 }
315 }
316
linear_quiesce(struct mddev * mddev,int state)317 static void linear_quiesce(struct mddev *mddev, int state)
318 {
319 }
320
321 static struct md_personality linear_personality = {
322 .head = {
323 .type = MD_PERSONALITY,
324 .id = ID_LINEAR,
325 .name = "linear",
326 .owner = THIS_MODULE,
327 },
328
329 .make_request = linear_make_request,
330 .run = linear_run,
331 .free = linear_free,
332 .status = linear_status,
333 .hot_add_disk = linear_add,
334 .size = linear_size,
335 .quiesce = linear_quiesce,
336 .error_handler = linear_error,
337 };
338
linear_init(void)339 static int __init linear_init(void)
340 {
341 return register_md_submodule(&linear_personality.head);
342 }
343
linear_exit(void)344 static void linear_exit(void)
345 {
346 unregister_md_submodule(&linear_personality.head);
347 }
348
349 module_init(linear_init);
350 module_exit(linear_exit);
351 MODULE_LICENSE("GPL");
352 MODULE_DESCRIPTION("Linear device concatenation personality for MD (deprecated)");
353 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
354 MODULE_ALIAS("md-linear");
355 MODULE_ALIAS("md-level--1");
356