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>
22 #include <linux/slab.h>
27 * find which device holds a particular offset
29 static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
35 hi = mddev->raid_disks - 1;
36 conf = rcu_dereference(mddev->private);
45 if (sector < conf->disks[mid].end_sector)
51 return conf->disks + lo;
55 * linear_mergeable_bvec -- tell bio layer if two requests can be merged
57 * @bvm: properties of new bio
58 * @biovec: the request that could be merged to it.
60 * Return amount of bytes we can take at this offset
62 static int linear_mergeable_bvec(struct request_queue *q,
63 struct bvec_merge_data *bvm,
64 struct bio_vec *biovec)
66 mddev_t *mddev = q->queuedata;
68 unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
69 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
72 dev0 = which_dev(mddev, sector);
73 maxsectors = dev0->end_sector - sector;
76 if (maxsectors < bio_sectors)
79 maxsectors -= bio_sectors;
81 if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
82 return biovec->bv_len;
83 /* The bytes available at this offset could be really big,
84 * so we cap at 2^31 to avoid overflow */
85 if (maxsectors > (1 << (31-9)))
87 return maxsectors << 9;
90 static int linear_congested(void *data, int bits)
92 mddev_t *mddev = data;
96 if (mddev_congested(mddev, bits))
100 conf = rcu_dereference(mddev->private);
102 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
103 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
104 ret |= bdi_congested(&q->backing_dev_info, bits);
111 static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks)
114 sector_t array_sectors;
117 conf = rcu_dereference(mddev->private);
118 WARN_ONCE(sectors || raid_disks,
119 "%s does not support generic reshape\n", __func__);
120 array_sectors = conf->array_sectors;
123 return array_sectors;
126 static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
132 conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
138 conf->array_sectors = 0;
140 list_for_each_entry(rdev, &mddev->disks, same_set) {
141 int j = rdev->raid_disk;
142 dev_info_t *disk = conf->disks + j;
145 if (j < 0 || j >= raid_disks || disk->rdev) {
146 printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
152 if (mddev->chunk_sectors) {
153 sectors = rdev->sectors;
154 sector_div(sectors, mddev->chunk_sectors);
155 rdev->sectors = sectors * mddev->chunk_sectors;
158 disk_stack_limits(mddev->gendisk, rdev->bdev,
159 rdev->data_offset << 9);
160 /* as we don't honour merge_bvec_fn, we must never risk
161 * violating it, so limit max_segments to 1 lying within
164 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
165 blk_queue_max_segments(mddev->queue, 1);
166 blk_queue_segment_boundary(mddev->queue,
167 PAGE_CACHE_SIZE - 1);
170 conf->array_sectors += rdev->sectors;
174 if (cnt != raid_disks) {
175 printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
181 * Here we calculate the device offsets.
183 conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
185 for (i = 1; i < raid_disks; i++)
186 conf->disks[i].end_sector =
187 conf->disks[i-1].end_sector +
188 conf->disks[i].rdev->sectors;
197 static int linear_run (mddev_t *mddev)
201 if (md_check_no_bitmap(mddev))
203 conf = linear_conf(mddev, mddev->raid_disks);
207 mddev->private = conf;
208 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
210 blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
211 mddev->queue->backing_dev_info.congested_fn = linear_congested;
212 mddev->queue->backing_dev_info.congested_data = mddev;
213 return md_integrity_register(mddev);
216 static void free_conf(struct rcu_head *head)
218 linear_conf_t *conf = container_of(head, linear_conf_t, rcu);
222 static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
224 /* Adding a drive to a linear array allows the array to grow.
225 * It is permitted if the new drive has a matching superblock
226 * already on it, with raid_disk equal to raid_disks.
227 * It is achieved by creating a new linear_private_data structure
228 * and swapping it in in-place of the current one.
229 * The current one is never freed until the array is stopped.
232 linear_conf_t *newconf, *oldconf;
234 if (rdev->saved_raid_disk != mddev->raid_disks)
237 rdev->raid_disk = rdev->saved_raid_disk;
239 newconf = linear_conf(mddev,mddev->raid_disks+1);
244 oldconf = rcu_dereference(mddev->private);
246 rcu_assign_pointer(mddev->private, newconf);
247 md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
248 set_capacity(mddev->gendisk, mddev->array_sectors);
249 revalidate_disk(mddev->gendisk);
250 call_rcu(&oldconf->rcu, free_conf);
254 static int linear_stop (mddev_t *mddev)
256 linear_conf_t *conf = mddev->private;
259 * We do not require rcu protection here since
260 * we hold reconfig_mutex for both linear_add and
261 * linear_stop, so they cannot race.
262 * We should make sure any old 'conf's are properly
266 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
268 mddev->private = NULL;
273 static int linear_make_request (mddev_t *mddev, struct bio *bio)
276 sector_t start_sector;
278 if (unlikely(bio->bi_rw & REQ_FLUSH)) {
279 md_flush_request(mddev, bio);
284 tmp_dev = which_dev(mddev, bio->bi_sector);
285 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
288 if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
289 || (bio->bi_sector < start_sector))) {
290 char b[BDEVNAME_SIZE];
293 "md/linear:%s: make_request: Sector %llu out of bounds on "
294 "dev %s: %llu sectors, offset %llu\n",
296 (unsigned long long)bio->bi_sector,
297 bdevname(tmp_dev->rdev->bdev, b),
298 (unsigned long long)tmp_dev->rdev->sectors,
299 (unsigned long long)start_sector);
304 if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
305 tmp_dev->end_sector)) {
306 /* This bio crosses a device boundary, so we have to
310 sector_t end_sector = tmp_dev->end_sector;
314 bp = bio_split(bio, end_sector - bio->bi_sector);
316 if (linear_make_request(mddev, &bp->bio1))
317 generic_make_request(&bp->bio1);
318 if (linear_make_request(mddev, &bp->bio2))
319 generic_make_request(&bp->bio2);
320 bio_pair_release(bp);
324 bio->bi_bdev = tmp_dev->rdev->bdev;
325 bio->bi_sector = bio->bi_sector - start_sector
326 + tmp_dev->rdev->data_offset;
332 static void linear_status (struct seq_file *seq, mddev_t *mddev)
335 seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
339 static struct mdk_personality linear_personality =
342 .level = LEVEL_LINEAR,
343 .owner = THIS_MODULE,
344 .make_request = linear_make_request,
347 .status = linear_status,
348 .hot_add_disk = linear_add,
352 static int __init linear_init (void)
354 return register_md_personality (&linear_personality);
357 static void linear_exit (void)
359 unregister_md_personality (&linear_personality);
363 module_init(linear_init);
364 module_exit(linear_exit);
365 MODULE_LICENSE("GPL");
366 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
367 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
368 MODULE_ALIAS("md-linear");
369 MODULE_ALIAS("md-level--1");