drivers/md/md-linear.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3    linear.c : Multiple Devices driver for Linux
   4               Copyright (C) 1994-96 Marc ZYNGIER
   5               <zyngier@ufr-info-p7.ibp.fr> or
   6               <maz@gloups.fdn.fr>
   7
   8    Linear mode management functions.
   9
  10 */
  11
  12 #include <linux/blkdev.h>
  13 #include <linux/raid/md_u.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <trace/events/block.h>
  18 #include "md.h"
  19 #include "md-linear.h"
  20
  21 /*
  22  * find which device holds a particular offset
  23  */
  24 static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
  25 {
  26         int lo, mid, hi;
  27         struct linear_conf *conf;
  28
  29         lo = 0;
  30         hi = mddev->raid_disks - 1;
  31         conf = mddev->private;
  32
  33         /*
  34          * Binary Search
  35          */
  36
  37         while (hi > lo) {
  38
  39                 mid = (hi + lo) / 2;
  40                 if (sector < conf->disks[mid].end_sector)
  41                         hi = mid;
  42                 else
  43                         lo = mid + 1;
  44         }
  45
  46         return conf->disks + lo;
  47 }
  48
  49 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
  50 {
  51         struct linear_conf *conf;
  52         sector_t array_sectors;
  53
  54         conf = mddev->private;
  55         WARN_ONCE(sectors || raid_disks,
  56                   "%s does not support generic reshape\n", __func__);
  57         array_sectors = conf->array_sectors;
  58
  59         return array_sectors;
  60 }
  61
  62 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
  63 {
  64         struct linear_conf *conf;
  65         struct md_rdev *rdev;
  66         int i, cnt;
  67         bool discard_supported = false;
  68
  69         conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
  70         if (!conf)
  71                 return NULL;
  72
  73         cnt = 0;
  74         conf->array_sectors = 0;
  75
  76         rdev_for_each(rdev, mddev) {
  77                 int j = rdev->raid_disk;
  78                 struct dev_info *disk = conf->disks + j;
  79                 sector_t sectors;
  80
  81                 if (j < 0 || j >= raid_disks || disk->rdev) {
  82                         pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
  83                                 mdname(mddev));
  84                         goto out;
  85                 }
  86
  87                 disk->rdev = rdev;
  88                 if (mddev->chunk_sectors) {
  89                         sectors = rdev->sectors;
  90                         sector_div(sectors, mddev->chunk_sectors);
  91                         rdev->sectors = sectors * mddev->chunk_sectors;
  92                 }
  93
  94                 disk_stack_limits(mddev->gendisk, rdev->bdev,
  95                                   rdev->data_offset << 9);
  96
  97                 conf->array_sectors += rdev->sectors;
  98                 cnt++;
  99
 100                 if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 101                         discard_supported = true;
 102         }
 103         if (cnt != raid_disks) {
 104                 pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
 105                         mdname(mddev));
 106                 goto out;
 107         }
 108
 109         if (!discard_supported)
 110                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
 111         else
 112                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
 113
 114         /*
 115          * Here we calculate the device offsets.
 116          */
 117         conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
 118
 119         for (i = 1; i < raid_disks; i++)
 120                 conf->disks[i].end_sector =
 121                         conf->disks[i-1].end_sector +
 122                         conf->disks[i].rdev->sectors;
 123
 124         /*
 125          * conf->raid_disks is copy of mddev->raid_disks. The reason to
 126          * keep a copy of mddev->raid_disks in struct linear_conf is,
 127          * mddev->raid_disks may not be consistent with pointers number of
 128          * conf->disks[] when it is updated in linear_add() and used to
 129          * iterate old conf->disks[] earray in linear_congested().
 130          * Here conf->raid_disks is always consitent with number of
 131          * pointers in conf->disks[] array, and mddev->private is updated
 132          * with rcu_assign_pointer() in linear_addr(), such race can be
 133          * avoided.
 134          */
 135         conf->raid_disks = raid_disks;
 136
 137         return conf;
 138
 139 out:
 140         kfree(conf);
 141         return NULL;
 142 }
 143
 144 static int linear_run (struct mddev *mddev)
 145 {
 146         struct linear_conf *conf;
 147         int ret;
 148
 149         if (md_check_no_bitmap(mddev))
 150                 return -EINVAL;
 151         conf = linear_conf(mddev, mddev->raid_disks);
 152
 153         if (!conf)
 154                 return 1;
 155         mddev->private = conf;
 156         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 157
 158         ret =  md_integrity_register(mddev);
 159         if (ret) {
 160                 kfree(conf);
 161                 mddev->private = NULL;
 162         }
 163         return ret;
 164 }
 165
 166 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
 167 {
 168         /* Adding a drive to a linear array allows the array to grow.
 169          * It is permitted if the new drive has a matching superblock
 170          * already on it, with raid_disk equal to raid_disks.
 171          * It is achieved by creating a new linear_private_data structure
 172          * and swapping it in in-place of the current one.
 173          * The current one is never freed until the array is stopped.
 174          * This avoids races.
 175          */
 176         struct linear_conf *newconf, *oldconf;
 177
 178         if (rdev->saved_raid_disk != mddev->raid_disks)
 179                 return -EINVAL;
 180
 181         rdev->raid_disk = rdev->saved_raid_disk;
 182         rdev->saved_raid_disk = -1;
 183
 184         newconf = linear_conf(mddev,mddev->raid_disks+1);
 185
 186         if (!newconf)
 187                 return -ENOMEM;
 188
 189         /* newconf->raid_disks already keeps a copy of * the increased
 190          * value of mddev->raid_disks, WARN_ONCE() is just used to make
 191          * sure of this. It is possible that oldconf is still referenced
 192          * in linear_congested(), therefore kfree_rcu() is used to free
 193          * oldconf until no one uses it anymore.
 194          */
 195         mddev_suspend(mddev);
 196         oldconf = rcu_dereference_protected(mddev->private,
 197                         lockdep_is_held(&mddev->reconfig_mutex));
 198         mddev->raid_disks++;
 199         WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
 200                 "copied raid_disks doesn't match mddev->raid_disks");
 201         rcu_assign_pointer(mddev->private, newconf);
 202         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 203         set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
 204         mddev_resume(mddev);
 205         kfree_rcu(oldconf, rcu);
 206         return 0;
 207 }
 208
 209 static void linear_free(struct mddev *mddev, void *priv)
 210 {
 211         struct linear_conf *conf = priv;
 212
 213         kfree(conf);
 214 }
 215
 216 static bool linear_make_request(struct mddev *mddev, struct bio *bio)
 217 {
 218         char b[BDEVNAME_SIZE];
 219         struct dev_info *tmp_dev;
 220         sector_t start_sector, end_sector, data_offset;
 221         sector_t bio_sector = bio->bi_iter.bi_sector;
 222
 223         if (unlikely(bio->bi_opf & REQ_PREFLUSH)
 224             && md_flush_request(mddev, bio))
 225                 return true;
 226
 227         tmp_dev = which_dev(mddev, bio_sector);
 228         start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
 229         end_sector = tmp_dev->end_sector;
 230         data_offset = tmp_dev->rdev->data_offset;
 231
 232         if (unlikely(bio_sector >= end_sector ||
 233                      bio_sector < start_sector))
 234                 goto out_of_bounds;
 235
 236         if (unlikely(is_mddev_broken(tmp_dev->rdev, "linear"))) {
 237                 bio_io_error(bio);
 238                 return true;
 239         }
 240
 241         if (unlikely(bio_end_sector(bio) > end_sector)) {
 242                 /* This bio crosses a device boundary, so we have to split it */
 243                 struct bio *split = bio_split(bio, end_sector - bio_sector,
 244                                               GFP_NOIO, &mddev->bio_set);
 245                 bio_chain(split, bio);
 246                 submit_bio_noacct(bio);
 247                 bio = split;
 248         }
 249
 250         bio_set_dev(bio, tmp_dev->rdev->bdev);
 251         bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
 252                 start_sector + data_offset;
 253
 254         if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
 255                      !blk_queue_discard(bio->bi_disk->queue))) {
 256                 /* Just ignore it */
 257                 bio_endio(bio);
 258         } else {
 259                 if (mddev->gendisk)
 260                         trace_block_bio_remap(bio, disk_devt(mddev->gendisk),
 261                                               bio_sector);
 262                 mddev_check_writesame(mddev, bio);
 263                 mddev_check_write_zeroes(mddev, bio);
 264                 submit_bio_noacct(bio);
 265         }
 266         return true;
 267
 268 out_of_bounds:
 269         pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
 270                mdname(mddev),
 271                (unsigned long long)bio->bi_iter.bi_sector,
 272                bdevname(tmp_dev->rdev->bdev, b),
 273                (unsigned long long)tmp_dev->rdev->sectors,
 274                (unsigned long long)start_sector);
 275         bio_io_error(bio);
 276         return true;
 277 }
 278
 279 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 280 {
 281         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 282 }
 283
 284 static void linear_quiesce(struct mddev *mddev, int state)
 285 {
 286 }
 287
 288 static struct md_personality linear_personality =
 289 {
 290         .name           = "linear",
 291         .level          = LEVEL_LINEAR,
 292         .owner          = THIS_MODULE,
 293         .make_request   = linear_make_request,
 294         .run            = linear_run,
 295         .free           = linear_free,
 296         .status         = linear_status,
 297         .hot_add_disk   = linear_add,
 298         .size           = linear_size,
 299         .quiesce        = linear_quiesce,
 300 };
 301
 302 static int __init linear_init (void)
 303 {
 304         return register_md_personality (&linear_personality);
 305 }
 306
 307 static void linear_exit (void)
 308 {
 309         unregister_md_personality (&linear_personality);
 310 }
 311
 312 module_init(linear_init);
 313 module_exit(linear_exit);
 314 MODULE_LICENSE("GPL");
 315 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 316 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 317 MODULE_ALIAS("md-linear");
 318 MODULE_ALIAS("md-level--1");