1/*
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
19#include <linux/blkdev.h>
20#include <linux/raid/md_u.h>
21#include <linux/seq_file.h>
22#include <linux/module.h>
23#include <linux/slab.h>
24#include "md.h"
25#include "linear.h"
26
27/*
28 * find which device holds a particular offset
29 */
30static 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
55static int linear_congested(struct mddev *mddev, int bits)
56{
57	struct linear_conf *conf;
58	int i, ret = 0;
59
60	conf = mddev->private;
61
62	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
63		struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
64		ret |= bdi_congested(&q->backing_dev_info, bits);
65	}
66
67	return ret;
68}
69
70static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
71{
72	struct linear_conf *conf;
73	sector_t array_sectors;
74
75	conf = mddev->private;
76	WARN_ONCE(sectors || raid_disks,
77		  "%s does not support generic reshape\n", __func__);
78	array_sectors = conf->array_sectors;
79
80	return array_sectors;
81}
82
83static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
84{
85	struct linear_conf *conf;
86	struct md_rdev *rdev;
87	int i, cnt;
88	bool discard_supported = false;
89
90	conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
91			GFP_KERNEL);
92	if (!conf)
93		return NULL;
94
95	cnt = 0;
96	conf->array_sectors = 0;
97
98	rdev_for_each(rdev, mddev) {
99		int j = rdev->raid_disk;
100		struct dev_info *disk = conf->disks + j;
101		sector_t sectors;
102
103		if (j < 0 || j >= raid_disks || disk->rdev) {
104			printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
105			       mdname(mddev));
106			goto out;
107		}
108
109		disk->rdev = rdev;
110		if (mddev->chunk_sectors) {
111			sectors = rdev->sectors;
112			sector_div(sectors, mddev->chunk_sectors);
113			rdev->sectors = sectors * mddev->chunk_sectors;
114		}
115
116		disk_stack_limits(mddev->gendisk, rdev->bdev,
117				  rdev->data_offset << 9);
118
119		conf->array_sectors += rdev->sectors;
120		cnt++;
121
122		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
123			discard_supported = true;
124	}
125	if (cnt != raid_disks) {
126		printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
127		       mdname(mddev));
128		goto out;
129	}
130
131	if (!discard_supported)
132		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
133	else
134		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
135
136	/*
137	 * Here we calculate the device offsets.
138	 */
139	conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
140
141	for (i = 1; i < raid_disks; i++)
142		conf->disks[i].end_sector =
143			conf->disks[i-1].end_sector +
144			conf->disks[i].rdev->sectors;
145
146	return conf;
147
148out:
149	kfree(conf);
150	return NULL;
151}
152
153static int linear_run (struct mddev *mddev)
154{
155	struct linear_conf *conf;
156	int ret;
157
158	if (md_check_no_bitmap(mddev))
159		return -EINVAL;
160	conf = linear_conf(mddev, mddev->raid_disks);
161
162	if (!conf)
163		return 1;
164	mddev->private = conf;
165	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
166
167	ret =  md_integrity_register(mddev);
168	if (ret) {
169		kfree(conf);
170		mddev->private = NULL;
171	}
172	return ret;
173}
174
175static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
176{
177	/* Adding a drive to a linear array allows the array to grow.
178	 * It is permitted if the new drive has a matching superblock
179	 * already on it, with raid_disk equal to raid_disks.
180	 * It is achieved by creating a new linear_private_data structure
181	 * and swapping it in in-place of the current one.
182	 * The current one is never freed until the array is stopped.
183	 * This avoids races.
184	 */
185	struct linear_conf *newconf, *oldconf;
186
187	if (rdev->saved_raid_disk != mddev->raid_disks)
188		return -EINVAL;
189
190	rdev->raid_disk = rdev->saved_raid_disk;
191	rdev->saved_raid_disk = -1;
192
193	newconf = linear_conf(mddev,mddev->raid_disks+1);
194
195	if (!newconf)
196		return -ENOMEM;
197
198	mddev_suspend(mddev);
199	oldconf = mddev->private;
200	mddev->raid_disks++;
201	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(oldconf);
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 void linear_make_request(struct mddev *mddev, struct bio *bio)
218{
219	char b[BDEVNAME_SIZE];
220	struct dev_info *tmp_dev;
221	struct bio *split;
222	sector_t start_sector, end_sector, data_offset;
223
224	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
225		md_flush_request(mddev, bio);
226		return;
227	}
228
229	do {
230		tmp_dev = which_dev(mddev, bio->bi_iter.bi_sector);
231		start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
232		end_sector = tmp_dev->end_sector;
233		data_offset = tmp_dev->rdev->data_offset;
234		bio->bi_bdev = tmp_dev->rdev->bdev;
235
236		if (unlikely(bio->bi_iter.bi_sector >= end_sector ||
237			     bio->bi_iter.bi_sector < start_sector))
238			goto out_of_bounds;
239
240		if (unlikely(bio_end_sector(bio) > end_sector)) {
241			/* This bio crosses a device boundary, so we have to
242			 * split it.
243			 */
244			split = bio_split(bio, end_sector -
245					  bio->bi_iter.bi_sector,
246					  GFP_NOIO, fs_bio_set);
247			bio_chain(split, bio);
248		} else {
249			split = bio;
250		}
251
252		split->bi_iter.bi_sector = split->bi_iter.bi_sector -
253			start_sector + data_offset;
254
255		if (unlikely((split->bi_rw & REQ_DISCARD) &&
256			 !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
257			/* Just ignore it */
258			bio_endio(split);
259		} else
260			generic_make_request(split);
261	} while (split != bio);
262	return;
263
264out_of_bounds:
265	printk(KERN_ERR
266	       "md/linear:%s: make_request: Sector %llu out of bounds on "
267	       "dev %s: %llu sectors, offset %llu\n",
268	       mdname(mddev),
269	       (unsigned long long)bio->bi_iter.bi_sector,
270	       bdevname(tmp_dev->rdev->bdev, b),
271	       (unsigned long long)tmp_dev->rdev->sectors,
272	       (unsigned long long)start_sector);
273	bio_io_error(bio);
274}
275
276static void linear_status (struct seq_file *seq, struct mddev *mddev)
277{
278
279	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
280}
281
282static void linear_quiesce(struct mddev *mddev, int state)
283{
284}
285
286static struct md_personality linear_personality =
287{
288	.name		= "linear",
289	.level		= LEVEL_LINEAR,
290	.owner		= THIS_MODULE,
291	.make_request	= linear_make_request,
292	.run		= linear_run,
293	.free		= linear_free,
294	.status		= linear_status,
295	.hot_add_disk	= linear_add,
296	.size		= linear_size,
297	.quiesce	= linear_quiesce,
298	.congested	= linear_congested,
299};
300
301static int __init linear_init (void)
302{
303	return register_md_personality (&linear_personality);
304}
305
306static void linear_exit (void)
307{
308	unregister_md_personality (&linear_personality);
309}
310
311module_init(linear_init);
312module_exit(linear_exit);
313MODULE_LICENSE("GPL");
314MODULE_DESCRIPTION("Linear device concatenation personality for MD");
315MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
316MODULE_ALIAS("md-linear");
317MODULE_ALIAS("md-level--1");
318