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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 bool discard_supported = false;
68
69 conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
70 if (!conf)
71 return NULL;
72
73 cnt = 0;
74 conf->array_sectors = 0;
75
76 rdev_for_each(rdev, mddev) {
77 int j = rdev->raid_disk;
78 struct dev_info *disk = conf->disks + j;
79 sector_t sectors;
80
81 if (j < 0 || j >= raid_disks || disk->rdev) {
82 pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
83 mdname(mddev));
84 goto out;
85 }
86
87 disk->rdev = rdev;
88 if (mddev->chunk_sectors) {
89 sectors = rdev->sectors;
90 sector_div(sectors, mddev->chunk_sectors);
91 rdev->sectors = sectors * mddev->chunk_sectors;
92 }
93
94 disk_stack_limits(mddev->gendisk, rdev->bdev,
95 rdev->data_offset << 9);
96
97 conf->array_sectors += rdev->sectors;
98 cnt++;
99
100 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
101 discard_supported = true;
102 }
103 if (cnt != raid_disks) {
104 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
105 mdname(mddev));
106 goto out;
107 }
108
109 if (!discard_supported)
110 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
111 else
112 blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
113
114 /*
115 * Here we calculate the device offsets.
116 */
117 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
118
119 for (i = 1; i < raid_disks; i++)
120 conf->disks[i].end_sector =
121 conf->disks[i-1].end_sector +
122 conf->disks[i].rdev->sectors;
123
124 /*
125 * conf->raid_disks is copy of mddev->raid_disks. The reason to
126 * keep a copy of mddev->raid_disks in struct linear_conf is,
127 * mddev->raid_disks may not be consistent with pointers number of
128 * conf->disks[] when it is updated in linear_add() and used to
129 * iterate old conf->disks[] earray in linear_congested().
130 * Here conf->raid_disks is always consitent with number of
131 * pointers in conf->disks[] array, and mddev->private is updated
132 * with rcu_assign_pointer() in linear_addr(), such race can be
133 * avoided.
134 */
135 conf->raid_disks = raid_disks;
136
137 return conf;
138
139out:
140 kfree(conf);
141 return NULL;
142}
143
144static int linear_run (struct mddev *mddev)
145{
146 struct linear_conf *conf;
147 int ret;
148
149 if (md_check_no_bitmap(mddev))
150 return -EINVAL;
151 conf = linear_conf(mddev, mddev->raid_disks);
152
153 if (!conf)
154 return 1;
155 mddev->private = conf;
156 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
157
158 ret = md_integrity_register(mddev);
159 if (ret) {
160 kfree(conf);
161 mddev->private = NULL;
162 }
163 return ret;
164}
165
166static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
167{
168 /* Adding a drive to a linear array allows the array to grow.
169 * It is permitted if the new drive has a matching superblock
170 * already on it, with raid_disk equal to raid_disks.
171 * It is achieved by creating a new linear_private_data structure
172 * and swapping it in in-place of the current one.
173 * The current one is never freed until the array is stopped.
174 * This avoids races.
175 */
176 struct linear_conf *newconf, *oldconf;
177
178 if (rdev->saved_raid_disk != mddev->raid_disks)
179 return -EINVAL;
180
181 rdev->raid_disk = rdev->saved_raid_disk;
182 rdev->saved_raid_disk = -1;
183
184 newconf = linear_conf(mddev,mddev->raid_disks+1);
185
186 if (!newconf)
187 return -ENOMEM;
188
189 /* newconf->raid_disks already keeps a copy of * the increased
190 * value of mddev->raid_disks, WARN_ONCE() is just used to make
191 * sure of this. It is possible that oldconf is still referenced
192 * in linear_congested(), therefore kfree_rcu() is used to free
193 * oldconf until no one uses it anymore.
194 */
195 mddev_suspend(mddev);
196 oldconf = rcu_dereference_protected(mddev->private,
197 lockdep_is_held(&mddev->reconfig_mutex));
198 mddev->raid_disks++;
199 WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
200 "copied raid_disks doesn't match mddev->raid_disks");
201 rcu_assign_pointer(mddev->private, newconf);
202 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
203 set_capacity(mddev->gendisk, mddev->array_sectors);
204 mddev_resume(mddev);
205 revalidate_disk(mddev->gendisk);
206 kfree_rcu(oldconf, rcu);
207 return 0;
208}
209
210static void linear_free(struct mddev *mddev, void *priv)
211{
212 struct linear_conf *conf = priv;
213
214 kfree(conf);
215}
216
217static bool linear_make_request(struct mddev *mddev, struct bio *bio)
218{
219 char b[BDEVNAME_SIZE];
220 struct dev_info *tmp_dev;
221 sector_t start_sector, end_sector, data_offset;
222 sector_t bio_sector = bio->bi_iter.bi_sector;
223
224 if (unlikely(bio->bi_opf & REQ_PREFLUSH)
225 && md_flush_request(mddev, bio))
226 return true;
227
228 tmp_dev = which_dev(mddev, bio_sector);
229 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
230 end_sector = tmp_dev->end_sector;
231 data_offset = tmp_dev->rdev->data_offset;
232
233 if (unlikely(bio_sector >= end_sector ||
234 bio_sector < start_sector))
235 goto out_of_bounds;
236
237 if (unlikely(is_mddev_broken(tmp_dev->rdev, "linear"))) {
238 bio_io_error(bio);
239 return true;
240 }
241
242 if (unlikely(bio_end_sector(bio) > end_sector)) {
243 /* This bio crosses a device boundary, so we have to split it */
244 struct bio *split = bio_split(bio, end_sector - bio_sector,
245 GFP_NOIO, &mddev->bio_set);
246 bio_chain(split, bio);
247 submit_bio_noacct(bio);
248 bio = split;
249 }
250
251 bio_set_dev(bio, tmp_dev->rdev->bdev);
252 bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
253 start_sector + data_offset;
254
255 if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
256 !blk_queue_discard(bio->bi_disk->queue))) {
257 /* Just ignore it */
258 bio_endio(bio);
259 } else {
260 if (mddev->gendisk)
261 trace_block_bio_remap(bio->bi_disk->queue,
262 bio, disk_devt(mddev->gendisk),
263 bio_sector);
264 mddev_check_writesame(mddev, bio);
265 mddev_check_write_zeroes(mddev, bio);
266 submit_bio_noacct(bio);
267 }
268 return true;
269
270out_of_bounds:
271 pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
272 mdname(mddev),
273 (unsigned long long)bio->bi_iter.bi_sector,
274 bdevname(tmp_dev->rdev->bdev, b),
275 (unsigned long long)tmp_dev->rdev->sectors,
276 (unsigned long long)start_sector);
277 bio_io_error(bio);
278 return true;
279}
280
281static void linear_status (struct seq_file *seq, struct mddev *mddev)
282{
283 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
284}
285
286static void linear_quiesce(struct mddev *mddev, int state)
287{
288}
289
290static struct md_personality linear_personality =
291{
292 .name = "linear",
293 .level = LEVEL_LINEAR,
294 .owner = THIS_MODULE,
295 .make_request = linear_make_request,
296 .run = linear_run,
297 .free = linear_free,
298 .status = linear_status,
299 .hot_add_disk = linear_add,
300 .size = linear_size,
301 .quiesce = linear_quiesce,
302};
303
304static int __init linear_init (void)
305{
306 return register_md_personality (&linear_personality);
307}
308
309static void linear_exit (void)
310{
311 unregister_md_personality (&linear_personality);
312}
313
314module_init(linear_init);
315module_exit(linear_exit);
316MODULE_LICENSE("GPL");
317MODULE_DESCRIPTION("Linear device concatenation personality for MD");
318MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
319MODULE_ALIAS("md-linear");
320MODULE_ALIAS("md-level--1");