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 /**
  56  *      linear_mergeable_bvec -- tell bio layer if two requests can be merged
  57  *      @q: request queue
  58  *      @bvm: properties of new bio
  59  *      @biovec: the request that could be merged to it.
  60  *
  61  *      Return amount of bytes we can take at this offset
  62  */
  63 static int linear_mergeable_bvec(struct mddev *mddev,
  64                                  struct bvec_merge_data *bvm,
  65                                  struct bio_vec *biovec)
  66 {
  67         struct dev_info *dev0;
  68         unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
  69         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
  70         int maxbytes = biovec->bv_len;
  71         struct request_queue *subq;
  72
  73         dev0 = which_dev(mddev, sector);
  74         maxsectors = dev0->end_sector - sector;
  75         subq = bdev_get_queue(dev0->rdev->bdev);
  76         if (subq->merge_bvec_fn) {
  77                 bvm->bi_bdev = dev0->rdev->bdev;
  78                 bvm->bi_sector -= dev0->end_sector - dev0->rdev->sectors;
  79                 maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,
  80                                                              biovec));
  81         }
  82
  83         if (maxsectors < bio_sectors)
  84                 maxsectors = 0;
  85         else
  86                 maxsectors -= bio_sectors;
  87
  88         if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
  89                 return maxbytes;
  90
  91         if (maxsectors > (maxbytes >> 9))
  92                 return maxbytes;
  93         else
  94                 return maxsectors << 9;
  95 }
  96
  97 static int linear_congested(struct mddev *mddev, int bits)
  98 {
  99         struct linear_conf *conf;
 100         int i, ret = 0;
 101
 102         conf = mddev->private;
 103
 104         for (i = 0; i < mddev->raid_disks && !ret ; i++) {
 105                 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
 106                 ret |= bdi_congested(&q->backing_dev_info, bits);
 107         }
 108
 109         return ret;
 110 }
 111
 112 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 113 {
 114         struct linear_conf *conf;
 115         sector_t array_sectors;
 116
 117         conf = mddev->private;
 118         WARN_ONCE(sectors || raid_disks,
 119                   "%s does not support generic reshape\n", __func__);
 120         array_sectors = conf->array_sectors;
 121
 122         return array_sectors;
 123 }
 124
 125 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
 126 {
 127         struct linear_conf *conf;
 128         struct md_rdev *rdev;
 129         int i, cnt;
 130         bool discard_supported = false;
 131
 132         conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
 133                         GFP_KERNEL);
 134         if (!conf)
 135                 return NULL;
 136
 137         cnt = 0;
 138         conf->array_sectors = 0;
 139
 140         rdev_for_each(rdev, mddev) {
 141                 int j = rdev->raid_disk;
 142                 struct dev_info *disk = conf->disks + j;
 143                 sector_t sectors;
 144
 145                 if (j < 0 || j >= raid_disks || disk->rdev) {
 146                         printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
 147                                mdname(mddev));
 148                         goto out;
 149                 }
 150
 151                 disk->rdev = rdev;
 152                 if (mddev->chunk_sectors) {
 153                         sectors = rdev->sectors;
 154                         sector_div(sectors, mddev->chunk_sectors);
 155                         rdev->sectors = sectors * mddev->chunk_sectors;
 156                 }
 157
 158                 disk_stack_limits(mddev->gendisk, rdev->bdev,
 159                                   rdev->data_offset << 9);
 160
 161                 conf->array_sectors += rdev->sectors;
 162                 cnt++;
 163
 164                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 165                         discard_supported = true;
 166         }
 167         if (cnt != raid_disks) {
 168                 printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
 169                        mdname(mddev));
 170                 goto out;
 171         }
 172
 173         if (!discard_supported)
 174                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 175         else
 176                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 177
 178         /*
 179          * Here we calculate the device offsets.
 180          */
 181         conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
 182
 183         for (i = 1; i < raid_disks; i++)
 184                 conf->disks[i].end_sector =
 185                         conf->disks[i-1].end_sector +
 186                         conf->disks[i].rdev->sectors;
 187
 188         return conf;
 189
 190 out:
 191         kfree(conf);
 192         return NULL;
 193 }
 194
 195 static int linear_run (struct mddev *mddev)
 196 {
 197         struct linear_conf *conf;
 198         int ret;
 199
 200         if (md_check_no_bitmap(mddev))
 201                 return -EINVAL;
 202         conf = linear_conf(mddev, mddev->raid_disks);
 203
 204         if (!conf)
 205                 return 1;
 206         mddev->private = conf;
 207         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 208
 209         ret =  md_integrity_register(mddev);
 210         if (ret) {
 211                 kfree(conf);
 212                 mddev->private = NULL;
 213         }
 214         return ret;
 215 }
 216
 217 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
 218 {
 219         /* Adding a drive to a linear array allows the array to grow.
 220          * It is permitted if the new drive has a matching superblock
 221          * already on it, with raid_disk equal to raid_disks.
 222          * It is achieved by creating a new linear_private_data structure
 223          * and swapping it in in-place of the current one.
 224          * The current one is never freed until the array is stopped.
 225          * This avoids races.
 226          */
 227         struct linear_conf *newconf, *oldconf;
 228
 229         if (rdev->saved_raid_disk != mddev->raid_disks)
 230                 return -EINVAL;
 231
 232         rdev->raid_disk = rdev->saved_raid_disk;
 233         rdev->saved_raid_disk = -1;
 234
 235         newconf = linear_conf(mddev,mddev->raid_disks+1);
 236
 237         if (!newconf)
 238                 return -ENOMEM;
 239
 240         mddev_suspend(mddev);
 241         oldconf = mddev->private;
 242         mddev->raid_disks++;
 243         mddev->private = newconf;
 244         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 245         set_capacity(mddev->gendisk, mddev->array_sectors);
 246         mddev_resume(mddev);
 247         revalidate_disk(mddev->gendisk);
 248         kfree(oldconf);
 249         return 0;
 250 }
 251
 252 static void linear_free(struct mddev *mddev, void *priv)
 253 {
 254         struct linear_conf *conf = priv;
 255
 256         kfree(conf);
 257 }
 258
 259 static void linear_make_request(struct mddev *mddev, struct bio *bio)
 260 {
 261         char b[BDEVNAME_SIZE];
 262         struct dev_info *tmp_dev;
 263         struct bio *split;
 264         sector_t start_sector, end_sector, data_offset;
 265
 266         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 267                 md_flush_request(mddev, bio);
 268                 return;
 269         }
 270
 271         do {
 272                 tmp_dev = which_dev(mddev, bio->bi_iter.bi_sector);
 273                 start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
 274                 end_sector = tmp_dev->end_sector;
 275                 data_offset = tmp_dev->rdev->data_offset;
 276                 bio->bi_bdev = tmp_dev->rdev->bdev;
 277
 278                 if (unlikely(bio->bi_iter.bi_sector >= end_sector ||
 279                              bio->bi_iter.bi_sector < start_sector))
 280                         goto out_of_bounds;
 281
 282                 if (unlikely(bio_end_sector(bio) > end_sector)) {
 283                         /* This bio crosses a device boundary, so we have to
 284                          * split it.
 285                          */
 286                         split = bio_split(bio, end_sector -
 287                                           bio->bi_iter.bi_sector,
 288                                           GFP_NOIO, fs_bio_set);
 289                         bio_chain(split, bio);
 290                 } else {
 291                         split = bio;
 292                 }
 293
 294                 split->bi_iter.bi_sector = split->bi_iter.bi_sector -
 295                         start_sector + data_offset;
 296
 297                 if (unlikely((split->bi_rw & REQ_DISCARD) &&
 298                          !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
 299                         /* Just ignore it */
 300                         bio_endio(split);
 301                 } else
 302                         generic_make_request(split);
 303         } while (split != bio);
 304         return;
 305
 306 out_of_bounds:
 307         printk(KERN_ERR
 308                "md/linear:%s: make_request: Sector %llu out of bounds on "
 309                "dev %s: %llu sectors, offset %llu\n",
 310                mdname(mddev),
 311                (unsigned long long)bio->bi_iter.bi_sector,
 312                bdevname(tmp_dev->rdev->bdev, b),
 313                (unsigned long long)tmp_dev->rdev->sectors,
 314                (unsigned long long)start_sector);
 315         bio_io_error(bio);
 316 }
 317
 318 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 319 {
 320
 321         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 322 }
 323
 324 static void linear_quiesce(struct mddev *mddev, int state)
 325 {
 326 }
 327
 328 static struct md_personality linear_personality =
 329 {
 330         .name           = "linear",
 331         .level          = LEVEL_LINEAR,
 332         .owner          = THIS_MODULE,
 333         .make_request   = linear_make_request,
 334         .run            = linear_run,
 335         .free           = linear_free,
 336         .status         = linear_status,
 337         .hot_add_disk   = linear_add,
 338         .size           = linear_size,
 339         .quiesce        = linear_quiesce,
 340         .congested      = linear_congested,
 341         .mergeable_bvec = linear_mergeable_bvec,
 342 };
 343
 344 static int __init linear_init (void)
 345 {
 346         return register_md_personality (&linear_personality);
 347 }
 348
 349 static void linear_exit (void)
 350 {
 351         unregister_md_personality (&linear_personality);
 352 }
 353
 354 module_init(linear_init);
 355 module_exit(linear_exit);
 356 MODULE_LICENSE("GPL");
 357 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 358 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 359 MODULE_ALIAS("md-linear");
 360 MODULE_ALIAS("md-level--1");