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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 cnt = 0;
73 conf->array_sectors = 0;
74
75 rdev_for_each(rdev, mddev) {
76 int j = rdev->raid_disk;
77 struct dev_info *disk = conf->disks + j;
78 sector_t sectors;
79
80 if (j < 0 || j >= raid_disks || disk->rdev) {
81 pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
82 mdname(mddev));
83 goto out;
84 }
85
86 disk->rdev = rdev;
87 if (mddev->chunk_sectors) {
88 sectors = rdev->sectors;
89 sector_div(sectors, mddev->chunk_sectors);
90 rdev->sectors = sectors * mddev->chunk_sectors;
91 }
92
93 disk_stack_limits(mddev->gendisk, rdev->bdev,
94 rdev->data_offset << 9);
95
96 conf->array_sectors += rdev->sectors;
97 cnt++;
98 }
99 if (cnt != raid_disks) {
100 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
101 mdname(mddev));
102 goto out;
103 }
104
105 /*
106 * Here we calculate the device offsets.
107 */
108 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
109
110 for (i = 1; i < raid_disks; i++)
111 conf->disks[i].end_sector =
112 conf->disks[i-1].end_sector +
113 conf->disks[i].rdev->sectors;
114
115 /*
116 * conf->raid_disks is copy of mddev->raid_disks. The reason to
117 * keep a copy of mddev->raid_disks in struct linear_conf is,
118 * mddev->raid_disks may not be consistent with pointers number of
119 * conf->disks[] when it is updated in linear_add() and used to
120 * iterate old conf->disks[] earray in linear_congested().
121 * Here conf->raid_disks is always consitent with number of
122 * pointers in conf->disks[] array, and mddev->private is updated
123 * with rcu_assign_pointer() in linear_addr(), such race can be
124 * avoided.
125 */
126 conf->raid_disks = raid_disks;
127
128 return conf;
129
130out:
131 kfree(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, mddev->raid_disks);
143
144 if (!conf)
145 return 1;
146 mddev->private = conf;
147 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
148
149 ret = md_integrity_register(mddev);
150 if (ret) {
151 kfree(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,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 mddev_suspend(mddev);
187 oldconf = rcu_dereference_protected(mddev->private,
188 lockdep_is_held(&mddev->reconfig_mutex));
189 mddev->raid_disks++;
190 WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
191 "copied raid_disks doesn't match mddev->raid_disks");
192 rcu_assign_pointer(mddev->private, newconf);
193 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
194 set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
195 mddev_resume(mddev);
196 kfree_rcu(oldconf, rcu);
197 return 0;
198}
199
200static void linear_free(struct mddev *mddev, void *priv)
201{
202 struct linear_conf *conf = priv;
203
204 kfree(conf);
205}
206
207static bool linear_make_request(struct mddev *mddev, struct bio *bio)
208{
209 struct dev_info *tmp_dev;
210 sector_t start_sector, end_sector, data_offset;
211 sector_t bio_sector = bio->bi_iter.bi_sector;
212
213 if (unlikely(bio->bi_opf & REQ_PREFLUSH)
214 && md_flush_request(mddev, bio))
215 return true;
216
217 tmp_dev = which_dev(mddev, bio_sector);
218 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
219 end_sector = tmp_dev->end_sector;
220 data_offset = tmp_dev->rdev->data_offset;
221
222 if (unlikely(bio_sector >= end_sector ||
223 bio_sector < start_sector))
224 goto out_of_bounds;
225
226 if (unlikely(is_mddev_broken(tmp_dev->rdev, "linear"))) {
227 bio_io_error(bio);
228 return true;
229 }
230
231 if (unlikely(bio_end_sector(bio) > end_sector)) {
232 /* This bio crosses a device boundary, so we have to split it */
233 struct bio *split = bio_split(bio, end_sector - bio_sector,
234 GFP_NOIO, &mddev->bio_set);
235 bio_chain(split, bio);
236 submit_bio_noacct(bio);
237 bio = split;
238 }
239
240 bio_set_dev(bio, 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, disk_devt(mddev->gendisk),
251 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(seq, " %dk rounding", mddev->chunk_sectors / 2);
271}
272
273static void linear_quiesce(struct mddev *mddev, int state)
274{
275}
276
277static struct md_personality linear_personality =
278{
279 .name = "linear",
280 .level = LEVEL_LINEAR,
281 .owner = THIS_MODULE,
282 .make_request = linear_make_request,
283 .run = linear_run,
284 .free = linear_free,
285 .status = linear_status,
286 .hot_add_disk = linear_add,
287 .size = linear_size,
288 .quiesce = linear_quiesce,
289};
290
291static int __init linear_init (void)
292{
293 return register_md_personality (&linear_personality);
294}
295
296static void linear_exit (void)
297{
298 unregister_md_personality (&linear_personality);
299}
300
301module_init(linear_init);
302module_exit(linear_exit);
303MODULE_LICENSE("GPL");
304MODULE_DESCRIPTION("Linear device concatenation personality for MD (deprecated)");
305MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
306MODULE_ALIAS("md-linear");
307MODULE_ALIAS("md-level--1");