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 <trace/events/block.h>
  25 #include "md.h"
  26 #include "linear.h"
  27
  28 /*
  29  * find which device holds a particular offset
  30  */
  31 static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
  32 {
  33         int lo, mid, hi;
  34         struct linear_conf *conf;
  35
  36         lo = 0;
  37         hi = mddev->raid_disks - 1;
  38         conf = mddev->private;
  39
  40         /*
  41          * Binary Search
  42          */
  43
  44         while (hi > lo) {
  45
  46                 mid = (hi + lo) / 2;
  47                 if (sector < conf->disks[mid].end_sector)
  48                         hi = mid;
  49                 else
  50                         lo = mid + 1;
  51         }
  52
  53         return conf->disks + lo;
  54 }
  55
  56 static int linear_congested(struct mddev *mddev, int bits)
  57 {
  58         struct linear_conf *conf;
  59         int i, ret = 0;
  60
  61         conf = mddev->private;
  62
  63         for (i = 0; i < mddev->raid_disks && !ret ; i++) {
  64                 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
  65                 ret |= bdi_congested(q->backing_dev_info, bits);
  66         }
  67
  68         return ret;
  69 }
  70
  71 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
  72 {
  73         struct linear_conf *conf;
  74         sector_t array_sectors;
  75
  76         conf = mddev->private;
  77         WARN_ONCE(sectors || raid_disks,
  78                   "%s does not support generic reshape\n", __func__);
  79         array_sectors = conf->array_sectors;
  80
  81         return array_sectors;
  82 }
  83
  84 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
  85 {
  86         struct linear_conf *conf;
  87         struct md_rdev *rdev;
  88         int i, cnt;
  89         bool discard_supported = false;
  90
  91         conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
  92                         GFP_KERNEL);
  93         if (!conf)
  94                 return NULL;
  95
  96         cnt = 0;
  97         conf->array_sectors = 0;
  98
  99         rdev_for_each(rdev, mddev) {
 100                 int j = rdev->raid_disk;
 101                 struct dev_info *disk = conf->disks + j;
 102                 sector_t sectors;
 103
 104                 if (j < 0 || j >= raid_disks || disk->rdev) {
 105                         pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
 106                                 mdname(mddev));
 107                         goto out;
 108                 }
 109
 110                 disk->rdev = rdev;
 111                 if (mddev->chunk_sectors) {
 112                         sectors = rdev->sectors;
 113                         sector_div(sectors, mddev->chunk_sectors);
 114                         rdev->sectors = sectors * mddev->chunk_sectors;
 115                 }
 116
 117                 disk_stack_limits(mddev->gendisk, rdev->bdev,
 118                                   rdev->data_offset << 9);
 119
 120                 conf->array_sectors += rdev->sectors;
 121                 cnt++;
 122
 123                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 124                         discard_supported = true;
 125         }
 126         if (cnt != raid_disks) {
 127                 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
 128                         mdname(mddev));
 129                 goto out;
 130         }
 131
 132         if (!discard_supported)
 133                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 134         else
 135                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 136
 137         /*
 138          * Here we calculate the device offsets.
 139          */
 140         conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
 141
 142         for (i = 1; i < raid_disks; i++)
 143                 conf->disks[i].end_sector =
 144                         conf->disks[i-1].end_sector +
 145                         conf->disks[i].rdev->sectors;
 146
 147         return conf;
 148
 149 out:
 150         kfree(conf);
 151         return NULL;
 152 }
 153
 154 static int linear_run (struct mddev *mddev)
 155 {
 156         struct linear_conf *conf;
 157         int ret;
 158
 159         if (md_check_no_bitmap(mddev))
 160                 return -EINVAL;
 161         conf = linear_conf(mddev, mddev->raid_disks);
 162
 163         if (!conf)
 164                 return 1;
 165         mddev->private = conf;
 166         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 167
 168         ret =  md_integrity_register(mddev);
 169         if (ret) {
 170                 kfree(conf);
 171                 mddev->private = NULL;
 172         }
 173         return ret;
 174 }
 175
 176 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
 177 {
 178         /* Adding a drive to a linear array allows the array to grow.
 179          * It is permitted if the new drive has a matching superblock
 180          * already on it, with raid_disk equal to raid_disks.
 181          * It is achieved by creating a new linear_private_data structure
 182          * and swapping it in in-place of the current one.
 183          * The current one is never freed until the array is stopped.
 184          * This avoids races.
 185          */
 186         struct linear_conf *newconf, *oldconf;
 187
 188         if (rdev->saved_raid_disk != mddev->raid_disks)
 189                 return -EINVAL;
 190
 191         rdev->raid_disk = rdev->saved_raid_disk;
 192         rdev->saved_raid_disk = -1;
 193
 194         newconf = linear_conf(mddev,mddev->raid_disks+1);
 195
 196         if (!newconf)
 197                 return -ENOMEM;
 198
 199         mddev_suspend(mddev);
 200         oldconf = mddev->private;
 201         mddev->raid_disks++;
 202         mddev->private = newconf;
 203         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 204         set_capacity(mddev->gendisk, mddev->array_sectors);
 205         mddev_resume(mddev);
 206         revalidate_disk(mddev->gendisk);
 207         kfree(oldconf);
 208         return 0;
 209 }
 210
 211 static void linear_free(struct mddev *mddev, void *priv)
 212 {
 213         struct linear_conf *conf = priv;
 214
 215         kfree(conf);
 216 }
 217
 218 static void linear_make_request(struct mddev *mddev, struct bio *bio)
 219 {
 220         char b[BDEVNAME_SIZE];
 221         struct dev_info *tmp_dev;
 222         struct bio *split;
 223         sector_t start_sector, end_sector, data_offset;
 224
 225         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
 226                 md_flush_request(mddev, bio);
 227                 return;
 228         }
 229
 230         do {
 231                 sector_t bio_sector = bio->bi_iter.bi_sector;
 232                 tmp_dev = which_dev(mddev, bio_sector);
 233                 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
 234                 end_sector = tmp_dev->end_sector;
 235                 data_offset = tmp_dev->rdev->data_offset;
 236                 bio->bi_bdev = tmp_dev->rdev->bdev;
 237
 238                 if (unlikely(bio_sector >= end_sector ||
 239                              bio_sector < start_sector))
 240                         goto out_of_bounds;
 241
 242                 if (unlikely(bio_end_sector(bio) > end_sector)) {
 243                         /* This bio crosses a device boundary, so we have to
 244                          * split it.
 245                          */
 246                         split = bio_split(bio, end_sector - bio_sector,
 247                                           GFP_NOIO, fs_bio_set);
 248                         bio_chain(split, bio);
 249                 } else {
 250                         split = bio;
 251                 }
 252
 253                 split->bi_iter.bi_sector = split->bi_iter.bi_sector -
 254                         start_sector + data_offset;
 255
 256                 if (unlikely((bio_op(split) == REQ_OP_DISCARD) &&
 257                          !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
 258                         /* Just ignore it */
 259                         bio_endio(split);
 260                 } else {
 261                         if (mddev->gendisk)
 262                                 trace_block_bio_remap(bdev_get_queue(split->bi_bdev),
 263                                                       split, disk_devt(mddev->gendisk),
 264                                                       bio_sector);
 265                         generic_make_request(split);
 266                 }
 267         } while (split != bio);
 268         return;
 269
 270 out_of_bounds:
 271         pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
 272                mdname(mddev),
 273                (unsigned long long)bio->bi_iter.bi_sector,
 274                bdevname(tmp_dev->rdev->bdev, b),
 275                (unsigned long long)tmp_dev->rdev->sectors,
 276                (unsigned long long)start_sector);
 277         bio_io_error(bio);
 278 }
 279
 280 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 281 {
 282         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 283 }
 284
 285 static void linear_quiesce(struct mddev *mddev, int state)
 286 {
 287 }
 288
 289 static struct md_personality linear_personality =
 290 {
 291         .name           = "linear",
 292         .level          = LEVEL_LINEAR,
 293         .owner          = THIS_MODULE,
 294         .make_request   = linear_make_request,
 295         .run            = linear_run,
 296         .free           = linear_free,
 297         .status         = linear_status,
 298         .hot_add_disk   = linear_add,
 299         .size           = linear_size,
 300         .quiesce        = linear_quiesce,
 301         .congested      = linear_congested,
 302 };
 303
 304 static int __init linear_init (void)
 305 {
 306         return register_md_personality (&linear_personality);
 307 }
 308
 309 static void linear_exit (void)
 310 {
 311         unregister_md_personality (&linear_personality);
 312 }
 313
 314 module_init(linear_init);
 315 module_exit(linear_exit);
 316 MODULE_LICENSE("GPL");
 317 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 318 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 319 MODULE_ALIAS("md-linear");
 320 MODULE_ALIAS("md-level--1");