blob: 777585458c8526a68ebaee3d40cb32974c07149a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/module.h>
20
21#include <linux/raid/md.h>
22#include <linux/slab.h>
23#include <linux/raid/linear.h>
24
25#define MAJOR_NR MD_MAJOR
26#define MD_DRIVER
27#define MD_PERSONALITY
28
29/*
30 * find which device holds a particular offset
31 */
32static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
33{
34 dev_info_t *hash;
35 linear_conf_t *conf = mddev_to_conf(mddev);
36 sector_t block = sector >> 1;
37
38 /*
39 * sector_div(a,b) returns the remainer and sets a to a/b
40 */
NeilBrown15945fe2005-09-09 16:23:47 -070041 block >>= conf->preshift;
42 (void)sector_div(block, conf->hash_spacing);
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 hash = conf->hash_table[block];
44
45 while ((sector>>1) >= (hash->size + hash->offset))
46 hash++;
47 return hash;
48}
49
50/**
NeilBrown15945fe2005-09-09 16:23:47 -070051 * linear_mergeable_bvec -- tell bio layer if two requests can be merged
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 * @q: request queue
53 * @bio: the buffer head that's been built up so far
54 * @biovec: the request that could be merged to it.
55 *
56 * Return amount of bytes we can take at this offset
57 */
58static int linear_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
59{
60 mddev_t *mddev = q->queuedata;
61 dev_info_t *dev0;
62 unsigned long maxsectors, bio_sectors = bio->bi_size >> 9;
63 sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
64
65 dev0 = which_dev(mddev, sector);
66 maxsectors = (dev0->size << 1) - (sector - (dev0->offset<<1));
67
68 if (maxsectors < bio_sectors)
69 maxsectors = 0;
70 else
71 maxsectors -= bio_sectors;
72
73 if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
74 return biovec->bv_len;
75 /* The bytes available at this offset could be really big,
76 * so we cap at 2^31 to avoid overflow */
77 if (maxsectors > (1 << (31-9)))
78 return 1<<31;
79 return maxsectors << 9;
80}
81
82static void linear_unplug(request_queue_t *q)
83{
84 mddev_t *mddev = q->queuedata;
85 linear_conf_t *conf = mddev_to_conf(mddev);
86 int i;
87
88 for (i=0; i < mddev->raid_disks; i++) {
89 request_queue_t *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
90 if (r_queue->unplug_fn)
91 r_queue->unplug_fn(r_queue);
92 }
93}
94
95static int linear_issue_flush(request_queue_t *q, struct gendisk *disk,
96 sector_t *error_sector)
97{
98 mddev_t *mddev = q->queuedata;
99 linear_conf_t *conf = mddev_to_conf(mddev);
100 int i, ret = 0;
101
102 for (i=0; i < mddev->raid_disks && ret == 0; i++) {
103 struct block_device *bdev = conf->disks[i].rdev->bdev;
104 request_queue_t *r_queue = bdev_get_queue(bdev);
105
106 if (!r_queue->issue_flush_fn)
107 ret = -EOPNOTSUPP;
108 else
109 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
110 }
111 return ret;
112}
113
114static int linear_run (mddev_t *mddev)
115{
116 linear_conf_t *conf;
117 dev_info_t **table;
118 mdk_rdev_t *rdev;
119 int i, nb_zone, cnt;
NeilBrown15945fe2005-09-09 16:23:47 -0700120 sector_t min_spacing;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 sector_t curr_offset;
122 struct list_head *tmp;
123
NeilBrown9ffae0c2006-01-06 00:20:32 -0800124 conf = kzalloc (sizeof (*conf) + mddev->raid_disks*sizeof(dev_info_t),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 GFP_KERNEL);
126 if (!conf)
127 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 mddev->private = conf;
129
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 cnt = 0;
131 mddev->array_size = 0;
132
133 ITERATE_RDEV(mddev,rdev,tmp) {
134 int j = rdev->raid_disk;
135 dev_info_t *disk = conf->disks + j;
136
137 if (j < 0 || j > mddev->raid_disks || disk->rdev) {
138 printk("linear: disk numbering problem. Aborting!\n");
139 goto out;
140 }
141
142 disk->rdev = rdev;
143
144 blk_queue_stack_limits(mddev->queue,
145 rdev->bdev->bd_disk->queue);
146 /* as we don't honour merge_bvec_fn, we must never risk
147 * violating it, so limit ->max_sector to one PAGE, as
148 * a one page request is never in violation.
149 */
150 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
151 mddev->queue->max_sectors > (PAGE_SIZE>>9))
152 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
153
154 disk->size = rdev->size;
155 mddev->array_size += rdev->size;
156
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 cnt++;
158 }
159 if (cnt != mddev->raid_disks) {
160 printk("linear: not enough drives present. Aborting!\n");
161 goto out;
162 }
163
NeilBrown15945fe2005-09-09 16:23:47 -0700164 min_spacing = mddev->array_size;
165 sector_div(min_spacing, PAGE_SIZE/sizeof(struct dev_info *));
166
167 /* min_spacing is the minimum spacing that will fit the hash
168 * table in one PAGE. This may be much smaller than needed.
169 * We find the smallest non-terminal set of consecutive devices
170 * that is larger than min_spacing as use the size of that as
171 * the actual spacing
172 */
173 conf->hash_spacing = mddev->array_size;
174 for (i=0; i < cnt-1 ; i++) {
175 sector_t sz = 0;
176 int j;
177 for (j=i; i<cnt-1 && sz < min_spacing ; j++)
178 sz += conf->disks[j].size;
179 if (sz >= min_spacing && sz < conf->hash_spacing)
180 conf->hash_spacing = sz;
181 }
182
183 /* hash_spacing may be too large for sector_div to work with,
184 * so we might need to pre-shift
185 */
186 conf->preshift = 0;
187 if (sizeof(sector_t) > sizeof(u32)) {
188 sector_t space = conf->hash_spacing;
189 while (space > (sector_t)(~(u32)0)) {
190 space >>= 1;
191 conf->preshift++;
192 }
193 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 /*
195 * This code was restructured to work around a gcc-2.95.3 internal
196 * compiler error. Alter it with care.
197 */
198 {
199 sector_t sz;
200 unsigned round;
201 unsigned long base;
202
NeilBrown15945fe2005-09-09 16:23:47 -0700203 sz = mddev->array_size >> conf->preshift;
204 sz += 1; /* force round-up */
205 base = conf->hash_spacing >> conf->preshift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 round = sector_div(sz, base);
NeilBrown15945fe2005-09-09 16:23:47 -0700207 nb_zone = sz + (round ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 }
NeilBrown15945fe2005-09-09 16:23:47 -0700209 BUG_ON(nb_zone > PAGE_SIZE / sizeof(struct dev_info *));
210
211 conf->hash_table = kmalloc (sizeof (struct dev_info *) * nb_zone,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 GFP_KERNEL);
213 if (!conf->hash_table)
214 goto out;
215
216 /*
217 * Here we generate the linear hash table
NeilBrown15945fe2005-09-09 16:23:47 -0700218 * First calculate the device offsets.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 */
NeilBrown15945fe2005-09-09 16:23:47 -0700220 conf->disks[0].offset = 0;
221 for (i=1; i<mddev->raid_disks; i++)
222 conf->disks[i].offset =
223 conf->disks[i-1].offset +
224 conf->disks[i-1].size;
225
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 table = conf->hash_table;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 curr_offset = 0;
NeilBrown15945fe2005-09-09 16:23:47 -0700228 i = 0;
229 for (curr_offset = 0;
230 curr_offset < mddev->array_size;
231 curr_offset += conf->hash_spacing) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
NeilBrown15945fe2005-09-09 16:23:47 -0700233 while (i < mddev->raid_disks-1 &&
234 curr_offset >= conf->disks[i+1].offset)
235 i++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
NeilBrown15945fe2005-09-09 16:23:47 -0700237 *table ++ = conf->disks + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 }
NeilBrown15945fe2005-09-09 16:23:47 -0700239
240 if (conf->preshift) {
241 conf->hash_spacing >>= conf->preshift;
242 /* round hash_spacing up so that when we divide by it,
243 * we err on the side of "too-low", which is safest.
244 */
245 conf->hash_spacing++;
246 }
247
248 BUG_ON(table - conf->hash_table > nb_zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249
250 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
251 mddev->queue->unplug_fn = linear_unplug;
252 mddev->queue->issue_flush_fn = linear_issue_flush;
253 return 0;
254
255out:
Jesper Juhl990a8ba2005-06-21 17:17:30 -0700256 kfree(conf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 return 1;
258}
259
260static int linear_stop (mddev_t *mddev)
261{
262 linear_conf_t *conf = mddev_to_conf(mddev);
263
264 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
265 kfree(conf->hash_table);
266 kfree(conf);
267
268 return 0;
269}
270
271static int linear_make_request (request_queue_t *q, struct bio *bio)
272{
Jens Axboea3623572005-11-01 09:26:16 +0100273 const int rw = bio_data_dir(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 mddev_t *mddev = q->queuedata;
275 dev_info_t *tmp_dev;
276 sector_t block;
277
NeilBrowne5dcdd82005-09-09 16:23:41 -0700278 if (unlikely(bio_barrier(bio))) {
279 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
280 return 0;
281 }
282
Jens Axboea3623572005-11-01 09:26:16 +0100283 disk_stat_inc(mddev->gendisk, ios[rw]);
284 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
286 tmp_dev = which_dev(mddev, bio->bi_sector);
287 block = bio->bi_sector >> 1;
288
289 if (unlikely(block >= (tmp_dev->size + tmp_dev->offset)
290 || block < tmp_dev->offset)) {
291 char b[BDEVNAME_SIZE];
292
293 printk("linear_make_request: Block %llu out of bounds on "
294 "dev %s size %llu offset %llu\n",
295 (unsigned long long)block,
296 bdevname(tmp_dev->rdev->bdev, b),
297 (unsigned long long)tmp_dev->size,
298 (unsigned long long)tmp_dev->offset);
299 bio_io_error(bio, bio->bi_size);
300 return 0;
301 }
302 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
303 (tmp_dev->offset + tmp_dev->size)<<1)) {
304 /* This bio crosses a device boundary, so we have to
305 * split it.
306 */
307 struct bio_pair *bp;
NeilBrown29ac8e02005-05-16 21:53:15 -0700308 bp = bio_split(bio, bio_split_pool,
309 ((tmp_dev->offset + tmp_dev->size)<<1) - bio->bi_sector);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 if (linear_make_request(q, &bp->bio1))
311 generic_make_request(&bp->bio1);
312 if (linear_make_request(q, &bp->bio2))
313 generic_make_request(&bp->bio2);
314 bio_pair_release(bp);
315 return 0;
316 }
317
318 bio->bi_bdev = tmp_dev->rdev->bdev;
319 bio->bi_sector = bio->bi_sector - (tmp_dev->offset << 1) + tmp_dev->rdev->data_offset;
320
321 return 1;
322}
323
324static void linear_status (struct seq_file *seq, mddev_t *mddev)
325{
326
327#undef MD_DEBUG
328#ifdef MD_DEBUG
329 int j;
330 linear_conf_t *conf = mddev_to_conf(mddev);
331 sector_t s = 0;
332
333 seq_printf(seq, " ");
NeilBrown15945fe2005-09-09 16:23:47 -0700334 for (j = 0; j < mddev->raid_disks; j++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 {
336 char b[BDEVNAME_SIZE];
337 s += conf->smallest_size;
338 seq_printf(seq, "[%s",
339 bdevname(conf->hash_table[j][0].rdev->bdev,b));
340
341 while (s > conf->hash_table[j][0].offset +
342 conf->hash_table[j][0].size)
343 seq_printf(seq, "/%s] ",
344 bdevname(conf->hash_table[j][1].rdev->bdev,b));
345 else
346 seq_printf(seq, "] ");
347 }
348 seq_printf(seq, "\n");
349#endif
350 seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
351}
352
353
NeilBrown2604b702006-01-06 00:20:36 -0800354static struct mdk_personality linear_personality =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355{
356 .name = "linear",
NeilBrown2604b702006-01-06 00:20:36 -0800357 .level = LEVEL_LINEAR,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 .owner = THIS_MODULE,
359 .make_request = linear_make_request,
360 .run = linear_run,
361 .stop = linear_stop,
362 .status = linear_status,
363};
364
365static int __init linear_init (void)
366{
NeilBrown2604b702006-01-06 00:20:36 -0800367 return register_md_personality (&linear_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368}
369
370static void linear_exit (void)
371{
NeilBrown2604b702006-01-06 00:20:36 -0800372 unregister_md_personality (&linear_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373}
374
375
376module_init(linear_init);
377module_exit(linear_exit);
378MODULE_LICENSE("GPL");
NeilBrownd9d166c2006-01-06 00:20:51 -0800379MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
380MODULE_ALIAS("md-linear");
NeilBrown2604b702006-01-06 00:20:36 -0800381MODULE_ALIAS("md-level--1");