2 linear.c : Multiple Devices driver for Linux
3 Copyright (C) 1994-96 Marc ZYNGIER
4 <zyngier@ufr-info-p7.ibp.fr> or
7 Linear mode management functions.
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)
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.
19 #include <linux/blkdev.h>
20 #include <linux/raid/md_u.h>
21 #include <linux/seq_file.h>
26 * find which device holds a particular offset
28 static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
34 hi = mddev->raid_disks - 1;
35 conf = rcu_dereference(mddev->private);
44 if (sector < conf->disks[mid].end_sector)
50 return conf->disks + lo;
54 * linear_mergeable_bvec -- tell bio layer if two requests can be merged
56 * @bvm: properties of new bio
57 * @biovec: the request that could be merged to it.
59 * Return amount of bytes we can take at this offset
61 static int linear_mergeable_bvec(struct request_queue *q,
62 struct bvec_merge_data *bvm,
63 struct bio_vec *biovec)
65 mddev_t *mddev = q->queuedata;
67 unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
68 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
71 dev0 = which_dev(mddev, sector);
72 maxsectors = dev0->end_sector - sector;
75 if (maxsectors < bio_sectors)
78 maxsectors -= bio_sectors;
80 if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
81 return biovec->bv_len;
82 /* The bytes available at this offset could be really big,
83 * so we cap at 2^31 to avoid overflow */
84 if (maxsectors > (1 << (31-9)))
86 return maxsectors << 9;
89 static void linear_unplug(struct request_queue *q)
91 mddev_t *mddev = q->queuedata;
96 conf = rcu_dereference(mddev->private);
98 for (i=0; i < mddev->raid_disks; i++) {
99 struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
105 static int linear_congested(void *data, int bits)
107 mddev_t *mddev = data;
112 conf = rcu_dereference(mddev->private);
114 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
115 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
116 ret |= bdi_congested(&q->backing_dev_info, bits);
123 static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks)
126 sector_t array_sectors;
129 conf = rcu_dereference(mddev->private);
130 WARN_ONCE(sectors || raid_disks,
131 "%s does not support generic reshape\n", __func__);
132 array_sectors = conf->array_sectors;
135 return array_sectors;
138 static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
144 conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
150 conf->array_sectors = 0;
152 list_for_each_entry(rdev, &mddev->disks, same_set) {
153 int j = rdev->raid_disk;
154 dev_info_t *disk = conf->disks + j;
157 if (j < 0 || j >= raid_disks || disk->rdev) {
158 printk("linear: disk numbering problem. Aborting!\n");
163 if (mddev->chunk_sectors) {
164 sectors = rdev->sectors;
165 sector_div(sectors, mddev->chunk_sectors);
166 rdev->sectors = sectors * mddev->chunk_sectors;
169 blk_queue_stack_limits(mddev->queue,
170 rdev->bdev->bd_disk->queue);
171 /* as we don't honour merge_bvec_fn, we must never risk
172 * violating it, so limit ->max_sector to one PAGE, as
173 * a one page request is never in violation.
175 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
176 queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
177 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
179 conf->array_sectors += rdev->sectors;
183 if (cnt != raid_disks) {
184 printk("linear: not enough drives present. Aborting!\n");
189 * Here we calculate the device offsets.
191 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
193 for (i = 1; i < raid_disks; i++)
194 conf->disks[i].end_sector =
195 conf->disks[i-1].end_sector +
196 conf->disks[i].rdev->sectors;
205 static int linear_run (mddev_t *mddev)
209 if (md_check_no_bitmap(mddev))
211 mddev->queue->queue_lock = &mddev->queue->__queue_lock;
212 conf = linear_conf(mddev, mddev->raid_disks);
216 mddev->private = conf;
217 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
219 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
220 mddev->queue->unplug_fn = linear_unplug;
221 mddev->queue->backing_dev_info.congested_fn = linear_congested;
222 mddev->queue->backing_dev_info.congested_data = mddev;
226 static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
228 /* Adding a drive to a linear array allows the array to grow.
229 * It is permitted if the new drive has a matching superblock
230 * already on it, with raid_disk equal to raid_disks.
231 * It is achieved by creating a new linear_private_data structure
232 * and swapping it in in-place of the current one.
233 * The current one is never freed until the array is stopped.
236 linear_conf_t *newconf;
238 if (rdev->saved_raid_disk != mddev->raid_disks)
241 rdev->raid_disk = rdev->saved_raid_disk;
243 newconf = linear_conf(mddev,mddev->raid_disks+1);
248 newconf->prev = mddev->private;
250 rcu_assign_pointer(mddev->private, newconf);
251 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
252 set_capacity(mddev->gendisk, mddev->array_sectors);
256 static int linear_stop (mddev_t *mddev)
258 linear_conf_t *conf = mddev->private;
261 * We do not require rcu protection here since
262 * we hold reconfig_mutex for both linear_add and
263 * linear_stop, so they cannot race.
266 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
268 linear_conf_t *t = conf->prev;
276 static int linear_make_request (struct request_queue *q, struct bio *bio)
278 const int rw = bio_data_dir(bio);
279 mddev_t *mddev = q->queuedata;
281 sector_t start_sector;
284 if (unlikely(bio_barrier(bio))) {
285 bio_endio(bio, -EOPNOTSUPP);
289 cpu = part_stat_lock();
290 part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
291 part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
296 tmp_dev = which_dev(mddev, bio->bi_sector);
297 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
300 if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
301 || (bio->bi_sector < start_sector))) {
302 char b[BDEVNAME_SIZE];
304 printk("linear_make_request: Sector %llu out of bounds on "
305 "dev %s: %llu sectors, offset %llu\n",
306 (unsigned long long)bio->bi_sector,
307 bdevname(tmp_dev->rdev->bdev, b),
308 (unsigned long long)tmp_dev->rdev->sectors,
309 (unsigned long long)start_sector);
314 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
315 tmp_dev->end_sector)) {
316 /* This bio crosses a device boundary, so we have to
320 sector_t end_sector = tmp_dev->end_sector;
324 bp = bio_split(bio, end_sector - bio->bi_sector);
326 if (linear_make_request(q, &bp->bio1))
327 generic_make_request(&bp->bio1);
328 if (linear_make_request(q, &bp->bio2))
329 generic_make_request(&bp->bio2);
330 bio_pair_release(bp);
334 bio->bi_bdev = tmp_dev->rdev->bdev;
335 bio->bi_sector = bio->bi_sector - start_sector
336 + tmp_dev->rdev->data_offset;
342 static void linear_status (struct seq_file *seq, mddev_t *mddev)
345 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
349 static struct mdk_personality linear_personality =
352 .level = LEVEL_LINEAR,
353 .owner = THIS_MODULE,
354 .make_request = linear_make_request,
357 .status = linear_status,
358 .hot_add_disk = linear_add,
362 static int __init linear_init (void)
364 return register_md_personality (&linear_personality);
367 static void linear_exit (void)
369 unregister_md_personality (&linear_personality);
373 module_init(linear_init);
374 module_exit(linear_exit);
375 MODULE_LICENSE("GPL");
376 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
377 MODULE_ALIAS("md-linear");
378 MODULE_ALIAS("md-level--1");