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 /*
  57  * In linear_congested() conf->raid_disks is used as a copy of
  58  * mddev->raid_disks to iterate conf->disks[], because conf->raid_disks
  59  * and conf->disks[] are created in linear_conf(), they are always
  60  * consitent with each other, but mddev->raid_disks does not.
  61  */
  62 static int linear_congested(struct mddev *mddev, int bits)
  63 {
  64         struct linear_conf *conf;
  65         int i, ret = 0;
  66
  67         rcu_read_lock();
  68         conf = rcu_dereference(mddev->private);
  69
  70         for (i = 0; i < conf->raid_disks && !ret ; i++) {
  71                 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
  72                 ret |= bdi_congested(q->backing_dev_info, bits);
  73         }
  74
  75         rcu_read_unlock();
  76         return ret;
  77 }
  78
  79 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
  80 {
  81         struct linear_conf *conf;
  82         sector_t array_sectors;
  83
  84         conf = mddev->private;
  85         WARN_ONCE(sectors || raid_disks,
  86                   "%s does not support generic reshape\n", __func__);
  87         array_sectors = conf->array_sectors;
  88
  89         return array_sectors;
  90 }
  91
  92 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
  93 {
  94         struct linear_conf *conf;
  95         struct md_rdev *rdev;
  96         int i, cnt;
  97         bool discard_supported = false;
  98
  99         conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
 100                         GFP_KERNEL);
 101         if (!conf)
 102                 return NULL;
 103
 104         cnt = 0;
 105         conf->array_sectors = 0;
 106
 107         rdev_for_each(rdev, mddev) {
 108                 int j = rdev->raid_disk;
 109                 struct dev_info *disk = conf->disks + j;
 110                 sector_t sectors;
 111
 112                 if (j < 0 || j >= raid_disks || disk->rdev) {
 113                         pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
 114                                 mdname(mddev));
 115                         goto out;
 116                 }
 117
 118                 disk->rdev = rdev;
 119                 if (mddev->chunk_sectors) {
 120                         sectors = rdev->sectors;
 121                         sector_div(sectors, mddev->chunk_sectors);
 122                         rdev->sectors = sectors * mddev->chunk_sectors;
 123                 }
 124
 125                 disk_stack_limits(mddev->gendisk, rdev->bdev,
 126                                   rdev->data_offset << 9);
 127
 128                 conf->array_sectors += rdev->sectors;
 129                 cnt++;
 130
 131                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 132                         discard_supported = true;
 133         }
 134         if (cnt != raid_disks) {
 135                 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
 136                         mdname(mddev));
 137                 goto out;
 138         }
 139
 140         if (!discard_supported)
 141                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 142         else
 143                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 144
 145         /*
 146          * Here we calculate the device offsets.
 147          */
 148         conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
 149
 150         for (i = 1; i < raid_disks; i++)
 151                 conf->disks[i].end_sector =
 152                         conf->disks[i-1].end_sector +
 153                         conf->disks[i].rdev->sectors;
 154
 155         /*
 156          * conf->raid_disks is copy of mddev->raid_disks. The reason to
 157          * keep a copy of mddev->raid_disks in struct linear_conf is,
 158          * mddev->raid_disks may not be consistent with pointers number of
 159          * conf->disks[] when it is updated in linear_add() and used to
 160          * iterate old conf->disks[] earray in linear_congested().
 161          * Here conf->raid_disks is always consitent with number of
 162          * pointers in conf->disks[] array, and mddev->private is updated
 163          * with rcu_assign_pointer() in linear_addr(), such race can be
 164          * avoided.
 165          */
 166         conf->raid_disks = raid_disks;
 167
 168         return conf;
 169
 170 out:
 171         kfree(conf);
 172         return NULL;
 173 }
 174
 175 static int linear_run (struct mddev *mddev)
 176 {
 177         struct linear_conf *conf;
 178         int ret;
 179
 180         if (md_check_no_bitmap(mddev))
 181                 return -EINVAL;
 182         conf = linear_conf(mddev, mddev->raid_disks);
 183
 184         if (!conf)
 185                 return 1;
 186         mddev->private = conf;
 187         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 188
 189         ret =  md_integrity_register(mddev);
 190         if (ret) {
 191                 kfree(conf);
 192                 mddev->private = NULL;
 193         }
 194         return ret;
 195 }
 196
 197 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
 198 {
 199         /* Adding a drive to a linear array allows the array to grow.
 200          * It is permitted if the new drive has a matching superblock
 201          * already on it, with raid_disk equal to raid_disks.
 202          * It is achieved by creating a new linear_private_data structure
 203          * and swapping it in in-place of the current one.
 204          * The current one is never freed until the array is stopped.
 205          * This avoids races.
 206          */
 207         struct linear_conf *newconf, *oldconf;
 208
 209         if (rdev->saved_raid_disk != mddev->raid_disks)
 210                 return -EINVAL;
 211
 212         rdev->raid_disk = rdev->saved_raid_disk;
 213         rdev->saved_raid_disk = -1;
 214
 215         newconf = linear_conf(mddev,mddev->raid_disks+1);
 216
 217         if (!newconf)
 218                 return -ENOMEM;
 219
 220         /* newconf->raid_disks already keeps a copy of * the increased
 221          * value of mddev->raid_disks, WARN_ONCE() is just used to make
 222          * sure of this. It is possible that oldconf is still referenced
 223          * in linear_congested(), therefore kfree_rcu() is used to free
 224          * oldconf until no one uses it anymore.
 225          */
 226         mddev_suspend(mddev);
 227         oldconf = rcu_dereference_protected(mddev->private,
 228                         lockdep_is_held(&mddev->reconfig_mutex));
 229         mddev->raid_disks++;
 230         WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
 231                 "copied raid_disks doesn't match mddev->raid_disks");
 232         rcu_assign_pointer(mddev->private, newconf);
 233         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 234         set_capacity(mddev->gendisk, mddev->array_sectors);
 235         mddev_resume(mddev);
 236         revalidate_disk(mddev->gendisk);
 237         kfree_rcu(oldconf, rcu);
 238         return 0;
 239 }
 240
 241 static void linear_free(struct mddev *mddev, void *priv)
 242 {
 243         struct linear_conf *conf = priv;
 244
 245         kfree(conf);
 246 }
 247
 248 static bool linear_make_request(struct mddev *mddev, struct bio *bio)
 249 {
 250         char b[BDEVNAME_SIZE];
 251         struct dev_info *tmp_dev;
 252         sector_t start_sector, end_sector, data_offset;
 253         sector_t bio_sector = bio->bi_iter.bi_sector;
 254
 255         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
 256                 md_flush_request(mddev, bio);
 257                 return true;
 258         }
 259
 260         tmp_dev = which_dev(mddev, bio_sector);
 261         start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
 262         end_sector = tmp_dev->end_sector;
 263         data_offset = tmp_dev->rdev->data_offset;
 264
 265         if (unlikely(bio_sector >= end_sector ||
 266                      bio_sector < start_sector))
 267                 goto out_of_bounds;
 268
 269         if (unlikely(bio_end_sector(bio) > end_sector)) {
 270                 /* This bio crosses a device boundary, so we have to split it */
 271                 struct bio *split = bio_split(bio, end_sector - bio_sector,
 272                                               GFP_NOIO, mddev->bio_set);
 273                 bio_chain(split, bio);
 274                 generic_make_request(bio);
 275                 bio = split;
 276         }
 277
 278         bio_set_dev(bio, tmp_dev->rdev->bdev);
 279         bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
 280                 start_sector + data_offset;
 281
 282         if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
 283                      !blk_queue_discard(bio->bi_disk->queue))) {
 284                 /* Just ignore it */
 285                 bio_endio(bio);
 286         } else {
 287                 if (mddev->gendisk)
 288                         trace_block_bio_remap(bio->bi_disk->queue,
 289                                               bio, disk_devt(mddev->gendisk),
 290                                               bio_sector);
 291                 mddev_check_writesame(mddev, bio);
 292                 mddev_check_write_zeroes(mddev, bio);
 293                 generic_make_request(bio);
 294         }
 295         return true;
 296
 297 out_of_bounds:
 298         pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
 299                mdname(mddev),
 300                (unsigned long long)bio->bi_iter.bi_sector,
 301                bdevname(tmp_dev->rdev->bdev, b),
 302                (unsigned long long)tmp_dev->rdev->sectors,
 303                (unsigned long long)start_sector);
 304         bio_io_error(bio);
 305         return true;
 306 }
 307
 308 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 309 {
 310         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 311 }
 312
 313 static void linear_quiesce(struct mddev *mddev, int state)
 314 {
 315 }
 316
 317 static struct md_personality linear_personality =
 318 {
 319         .name           = "linear",
 320         .level          = LEVEL_LINEAR,
 321         .owner          = THIS_MODULE,
 322         .make_request   = linear_make_request,
 323         .run            = linear_run,
 324         .free           = linear_free,
 325         .status         = linear_status,
 326         .hot_add_disk   = linear_add,
 327         .size           = linear_size,
 328         .quiesce        = linear_quiesce,
 329         .congested      = linear_congested,
 330 };
 331
 332 static int __init linear_init (void)
 333 {
 334         return register_md_personality (&linear_personality);
 335 }
 336
 337 static void linear_exit (void)
 338 {
 339         unregister_md_personality (&linear_personality);
 340 }
 341
 342 module_init(linear_init);
 343 module_exit(linear_exit);
 344 MODULE_LICENSE("GPL");
 345 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 346 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 347 MODULE_ALIAS("md-linear");
 348 MODULE_ALIAS("md-level--1");