drivers/md/linear.c

   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  */
  30 static 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
  55 static 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
  70 static 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
  83 static 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
 148 out:
 149         kfree(conf);
 150         return NULL;
 151 }
 152
 153 static 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
 175 static 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
 210 static void linear_free(struct mddev *mddev, void *priv)
 211 {
 212         struct linear_conf *conf = priv;
 213
 214         kfree(conf);
 215 }
 216
 217 static 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
 264 out_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
 276 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 277 {
 278
 279         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 280 }
 281
 282 static void linear_quiesce(struct mddev *mddev, int state)
 283 {
 284 }
 285
 286 static 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
 301 static int __init linear_init (void)
 302 {
 303         return register_md_personality (&linear_personality);
 304 }
 305
 306 static void linear_exit (void)
 307 {
 308         unregister_md_personality (&linear_personality);
 309 }
 310
 311 module_init(linear_init);
 312 module_exit(linear_exit);
 313 MODULE_LICENSE("GPL");
 314 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 315 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 316 MODULE_ALIAS("md-linear");
 317 MODULE_ALIAS("md-level--1");