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)
31 linear_conf_t *conf = mddev->private;
35 while (sector >= hash->num_sectors + hash->start_sector)
41 * linear_mergeable_bvec -- tell bio layer if two requests can be merged
43 * @bvm: properties of new bio
44 * @biovec: the request that could be merged to it.
46 * Return amount of bytes we can take at this offset
48 static int linear_mergeable_bvec(struct request_queue *q,
49 struct bvec_merge_data *bvm,
50 struct bio_vec *biovec)
52 mddev_t *mddev = q->queuedata;
54 unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
55 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
57 dev0 = which_dev(mddev, sector);
58 maxsectors = dev0->num_sectors - (sector - dev0->start_sector);
60 if (maxsectors < bio_sectors)
63 maxsectors -= bio_sectors;
65 if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
66 return biovec->bv_len;
67 /* The bytes available at this offset could be really big,
68 * so we cap at 2^31 to avoid overflow */
69 if (maxsectors > (1 << (31-9)))
71 return maxsectors << 9;
74 static void linear_unplug(struct request_queue *q)
76 mddev_t *mddev = q->queuedata;
77 linear_conf_t *conf = mddev->private;
80 for (i=0; i < mddev->raid_disks; i++) {
81 struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
86 static int linear_congested(void *data, int bits)
88 mddev_t *mddev = data;
89 linear_conf_t *conf = mddev->private;
92 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
93 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
94 ret |= bdi_congested(&q->backing_dev_info, bits);
99 static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks)
101 linear_conf_t *conf = mddev->private;
103 WARN_ONCE(sectors || raid_disks,
104 "%s does not support generic reshape\n", __func__);
106 return conf->array_sectors;
109 static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
115 conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
121 conf->array_sectors = 0;
123 list_for_each_entry(rdev, &mddev->disks, same_set) {
124 int j = rdev->raid_disk;
125 dev_info_t *disk = conf->disks + j;
127 if (j < 0 || j >= raid_disks || disk->rdev) {
128 printk("linear: disk numbering problem. Aborting!\n");
134 blk_queue_stack_limits(mddev->queue,
135 rdev->bdev->bd_disk->queue);
136 /* as we don't honour merge_bvec_fn, we must never risk
137 * violating it, so limit ->max_sector to one PAGE, as
138 * a one page request is never in violation.
140 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
141 queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
142 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
144 disk->num_sectors = rdev->sectors;
145 conf->array_sectors += rdev->sectors;
149 if (cnt != raid_disks) {
150 printk("linear: not enough drives present. Aborting!\n");
155 * Here we calculate the device offsets.
157 conf->disks[0].start_sector = 0;
158 for (i = 1; i < raid_disks; i++)
159 conf->disks[i].start_sector =
160 conf->disks[i-1].start_sector +
161 conf->disks[i-1].num_sectors;
170 static int linear_run (mddev_t *mddev)
174 mddev->queue->queue_lock = &mddev->queue->__queue_lock;
175 conf = linear_conf(mddev, mddev->raid_disks);
179 mddev->private = conf;
180 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
182 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
183 mddev->queue->unplug_fn = linear_unplug;
184 mddev->queue->backing_dev_info.congested_fn = linear_congested;
185 mddev->queue->backing_dev_info.congested_data = mddev;
189 static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
191 /* Adding a drive to a linear array allows the array to grow.
192 * It is permitted if the new drive has a matching superblock
193 * already on it, with raid_disk equal to raid_disks.
194 * It is achieved by creating a new linear_private_data structure
195 * and swapping it in in-place of the current one.
196 * The current one is never freed until the array is stopped.
199 linear_conf_t *newconf;
201 if (rdev->saved_raid_disk != mddev->raid_disks)
204 rdev->raid_disk = rdev->saved_raid_disk;
206 newconf = linear_conf(mddev,mddev->raid_disks+1);
211 newconf->prev = mddev->private;
212 mddev->private = newconf;
214 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
215 set_capacity(mddev->gendisk, mddev->array_sectors);
219 static int linear_stop (mddev_t *mddev)
221 linear_conf_t *conf = mddev->private;
223 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
225 linear_conf_t *t = conf->prev;
233 static int linear_make_request (struct request_queue *q, struct bio *bio)
235 const int rw = bio_data_dir(bio);
236 mddev_t *mddev = q->queuedata;
240 if (unlikely(bio_barrier(bio))) {
241 bio_endio(bio, -EOPNOTSUPP);
245 cpu = part_stat_lock();
246 part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
247 part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
251 tmp_dev = which_dev(mddev, bio->bi_sector);
253 if (unlikely(bio->bi_sector >= (tmp_dev->num_sectors +
254 tmp_dev->start_sector)
256 tmp_dev->start_sector))) {
257 char b[BDEVNAME_SIZE];
259 printk("linear_make_request: Sector %llu out of bounds on "
260 "dev %s: %llu sectors, offset %llu\n",
261 (unsigned long long)bio->bi_sector,
262 bdevname(tmp_dev->rdev->bdev, b),
263 (unsigned long long)tmp_dev->num_sectors,
264 (unsigned long long)tmp_dev->start_sector);
268 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
269 tmp_dev->start_sector + tmp_dev->num_sectors)) {
270 /* This bio crosses a device boundary, so we have to
276 tmp_dev->start_sector + tmp_dev->num_sectors
279 if (linear_make_request(q, &bp->bio1))
280 generic_make_request(&bp->bio1);
281 if (linear_make_request(q, &bp->bio2))
282 generic_make_request(&bp->bio2);
283 bio_pair_release(bp);
287 bio->bi_bdev = tmp_dev->rdev->bdev;
288 bio->bi_sector = bio->bi_sector - tmp_dev->start_sector
289 + tmp_dev->rdev->data_offset;
294 static void linear_status (struct seq_file *seq, mddev_t *mddev)
297 seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
301 static struct mdk_personality linear_personality =
304 .level = LEVEL_LINEAR,
305 .owner = THIS_MODULE,
306 .make_request = linear_make_request,
309 .status = linear_status,
310 .hot_add_disk = linear_add,
314 static int __init linear_init (void)
316 return register_md_personality (&linear_personality);
319 static void linear_exit (void)
321 unregister_md_personality (&linear_personality);
325 module_init(linear_init);
326 module_exit(linear_exit);
327 MODULE_LICENSE("GPL");
328 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
329 MODULE_ALIAS("md-linear");
330 MODULE_ALIAS("md-level--1");