1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 linear.c : Multiple Devices driver for Linux
4 Copyright (C) 1994-96 Marc ZYNGIER
5 <zyngier@ufr-info-p7.ibp.fr> or
6 <maz@gloups.fdn.fr>
7
8 Linear mode management functions.
9
10*/
11
12#include <linux/blkdev.h>
13#include <linux/raid/md_u.h>
14#include <linux/seq_file.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <trace/events/block.h>
18#include "md.h"
19#include "md-linear.h"
20
21/*
22 * find which device holds a particular offset
23 */
24static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
25{
26 int lo, mid, hi;
27 struct linear_conf *conf;
28
29 lo = 0;
30 hi = mddev->raid_disks - 1;
31 conf = mddev->private;
32
33 /*
34 * Binary Search
35 */
36
37 while (hi > lo) {
38
39 mid = (hi + lo) / 2;
40 if (sector < conf->disks[mid].end_sector)
41 hi = mid;
42 else
43 lo = mid + 1;
44 }
45
46 return conf->disks + lo;
47}
48
49static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
50{
51 struct linear_conf *conf;
52 sector_t array_sectors;
53
54 conf = mddev->private;
55 WARN_ONCE(sectors || raid_disks,
56 "%s does not support generic reshape\n", __func__);
57 array_sectors = conf->array_sectors;
58
59 return array_sectors;
60}
61
62static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
63{
64 struct linear_conf *conf;
65 struct md_rdev *rdev;
66 int i, cnt;
67
68 conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
69 if (!conf)
70 return NULL;
71
72 /*
73 * conf->raid_disks is copy of mddev->raid_disks. The reason to
74 * keep a copy of mddev->raid_disks in struct linear_conf is,
75 * mddev->raid_disks may not be consistent with pointers number of
76 * conf->disks[] when it is updated in linear_add() and used to
77 * iterate old conf->disks[] earray in linear_congested().
78 * Here conf->raid_disks is always consitent with number of
79 * pointers in conf->disks[] array, and mddev->private is updated
80 * with rcu_assign_pointer() in linear_addr(), such race can be
81 * avoided.
82 */
83 conf->raid_disks = raid_disks;
84
85 cnt = 0;
86 conf->array_sectors = 0;
87
88 rdev_for_each(rdev, mddev) {
89 int j = rdev->raid_disk;
90 struct dev_info *disk = conf->disks + j;
91 sector_t sectors;
92
93 if (j < 0 || j >= raid_disks || disk->rdev) {
94 pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
95 mdname(mddev));
96 goto out;
97 }
98
99 disk->rdev = rdev;
100 if (mddev->chunk_sectors) {
101 sectors = rdev->sectors;
102 sector_div(sectors, mddev->chunk_sectors);
103 rdev->sectors = sectors * mddev->chunk_sectors;
104 }
105
106 disk_stack_limits(disk: mddev->gendisk, bdev: rdev->bdev,
107 offset: rdev->data_offset << 9);
108
109 conf->array_sectors += rdev->sectors;
110 cnt++;
111 }
112 if (cnt != raid_disks) {
113 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
114 mdname(mddev));
115 goto out;
116 }
117
118 /*
119 * Here we calculate the device offsets.
120 */
121 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
122
123 for (i = 1; i < raid_disks; i++)
124 conf->disks[i].end_sector =
125 conf->disks[i-1].end_sector +
126 conf->disks[i].rdev->sectors;
127
128 return conf;
129
130out:
131 kfree(objp: conf);
132 return NULL;
133}
134
135static int linear_run (struct mddev *mddev)
136{
137 struct linear_conf *conf;
138 int ret;
139
140 if (md_check_no_bitmap(mddev))
141 return -EINVAL;
142 conf = linear_conf(mddev, raid_disks: mddev->raid_disks);
143
144 if (!conf)
145 return 1;
146 mddev->private = conf;
147 md_set_array_sectors(mddev, array_sectors: linear_size(mddev, sectors: 0, raid_disks: 0));
148
149 ret = md_integrity_register(mddev);
150 if (ret) {
151 kfree(objp: conf);
152 mddev->private = NULL;
153 }
154 return ret;
155}
156
157static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
158{
159 /* Adding a drive to a linear array allows the array to grow.
160 * It is permitted if the new drive has a matching superblock
161 * already on it, with raid_disk equal to raid_disks.
162 * It is achieved by creating a new linear_private_data structure
163 * and swapping it in in-place of the current one.
164 * The current one is never freed until the array is stopped.
165 * This avoids races.
166 */
167 struct linear_conf *newconf, *oldconf;
168
169 if (rdev->saved_raid_disk != mddev->raid_disks)
170 return -EINVAL;
171
172 rdev->raid_disk = rdev->saved_raid_disk;
173 rdev->saved_raid_disk = -1;
174
175 newconf = linear_conf(mddev,raid_disks: mddev->raid_disks+1);
176
177 if (!newconf)
178 return -ENOMEM;
179
180 /* newconf->raid_disks already keeps a copy of * the increased
181 * value of mddev->raid_disks, WARN_ONCE() is just used to make
182 * sure of this. It is possible that oldconf is still referenced
183 * in linear_congested(), therefore kfree_rcu() is used to free
184 * oldconf until no one uses it anymore.
185 */
186 oldconf = rcu_dereference_protected(mddev->private,
187 lockdep_is_held(&mddev->reconfig_mutex));
188 mddev->raid_disks++;
189 WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
190 "copied raid_disks doesn't match mddev->raid_disks");
191 rcu_assign_pointer(mddev->private, newconf);
192 md_set_array_sectors(mddev, array_sectors: linear_size(mddev, sectors: 0, raid_disks: 0));
193 set_capacity_and_notify(disk: mddev->gendisk, size: mddev->array_sectors);
194 kfree_rcu(oldconf, rcu);
195 return 0;
196}
197
198static void linear_free(struct mddev *mddev, void *priv)
199{
200 struct linear_conf *conf = priv;
201
202 kfree(objp: conf);
203}
204
205static bool linear_make_request(struct mddev *mddev, struct bio *bio)
206{
207 struct dev_info *tmp_dev;
208 sector_t start_sector, end_sector, data_offset;
209 sector_t bio_sector = bio->bi_iter.bi_sector;
210
211 if (unlikely(bio->bi_opf & REQ_PREFLUSH)
212 && md_flush_request(mddev, bio))
213 return true;
214
215 tmp_dev = which_dev(mddev, sector: bio_sector);
216 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
217 end_sector = tmp_dev->end_sector;
218 data_offset = tmp_dev->rdev->data_offset;
219
220 if (unlikely(bio_sector >= end_sector ||
221 bio_sector < start_sector))
222 goto out_of_bounds;
223
224 if (unlikely(is_rdev_broken(tmp_dev->rdev))) {
225 md_error(mddev, rdev: tmp_dev->rdev);
226 bio_io_error(bio);
227 return true;
228 }
229
230 if (unlikely(bio_end_sector(bio) > end_sector)) {
231 /* This bio crosses a device boundary, so we have to split it */
232 struct bio *split = bio_split(bio, sectors: end_sector - bio_sector,
233 GFP_NOIO, bs: &mddev->bio_set);
234 bio_chain(split, bio);
235 submit_bio_noacct(bio);
236 bio = split;
237 }
238
239 md_account_bio(mddev, bio: &bio);
240 bio_set_dev(bio, bdev: tmp_dev->rdev->bdev);
241 bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
242 start_sector + data_offset;
243
244 if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
245 !bdev_max_discard_sectors(bio->bi_bdev))) {
246 /* Just ignore it */
247 bio_endio(bio);
248 } else {
249 if (mddev->gendisk)
250 trace_block_bio_remap(bio, dev: disk_devt(disk: mddev->gendisk),
251 from: bio_sector);
252 mddev_check_write_zeroes(mddev, bio);
253 submit_bio_noacct(bio);
254 }
255 return true;
256
257out_of_bounds:
258 pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %pg: %llu sectors, offset %llu\n",
259 mdname(mddev),
260 (unsigned long long)bio->bi_iter.bi_sector,
261 tmp_dev->rdev->bdev,
262 (unsigned long long)tmp_dev->rdev->sectors,
263 (unsigned long long)start_sector);
264 bio_io_error(bio);
265 return true;
266}
267
268static void linear_status (struct seq_file *seq, struct mddev *mddev)
269{
270 seq_printf(m: seq, fmt: " %dk rounding", mddev->chunk_sectors / 2);
271}
272
273static void linear_error(struct mddev *mddev, struct md_rdev *rdev)
274{
275 if (!test_and_set_bit(nr: MD_BROKEN, addr: &mddev->flags)) {
276 char *md_name = mdname(mddev);
277
278 pr_crit("md/linear%s: Disk failure on %pg detected, failing array.\n",
279 md_name, rdev->bdev);
280 }
281}
282
283static void linear_quiesce(struct mddev *mddev, int state)
284{
285}
286
287static struct md_personality linear_personality =
288{
289 .name = "linear",
290 .level = LEVEL_LINEAR,
291 .owner = THIS_MODULE,
292 .make_request = linear_make_request,
293 .run = linear_run,
294 .free = linear_free,
295 .status = linear_status,
296 .hot_add_disk = linear_add,
297 .size = linear_size,
298 .quiesce = linear_quiesce,
299 .error_handler = linear_error,
300};
301
302static int __init linear_init (void)
303{
304 return register_md_personality (p: &linear_personality);
305}
306
307static void linear_exit (void)
308{
309 unregister_md_personality (p: &linear_personality);
310}
311
312module_init(linear_init);
313module_exit(linear_exit);
314MODULE_LICENSE("GPL");
315MODULE_DESCRIPTION("Linear device concatenation personality for MD (deprecated)");
316MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
317MODULE_ALIAS("md-linear");
318MODULE_ALIAS("md-level--1");
319

source code of linux/drivers/md/md-linear.c