root/drivers/md/md-linear.c

DEFINITIONS

1. which_dev
2. linear_congested
3. linear_size
4. linear_run
5. linear_add
6. linear_free
7. linear_make_request
8. linear_status
9. linear_quiesce
10. linear_init
11. linear_exit

   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 /*
  50  * In linear_congested() conf->raid_disks is used as a copy of
  51  * mddev->raid_disks to iterate conf->disks[], because conf->raid_disks
  52  * and conf->disks[] are created in linear_conf(), they are always
  53  * consitent with each other, but mddev->raid_disks does not.
  54  */
  55 static int linear_congested(struct mddev *mddev, int bits)
  56 {
  57         struct linear_conf *conf;
  58         int i, ret = 0;
  59 
  60         rcu_read_lock();
  61         conf = rcu_dereference(mddev->private);
  62 
  63         for (i = 0; i < conf->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         rcu_read_unlock();
  69         return ret;
  70 }
  71 
  72 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
  73 {
  74         struct linear_conf *conf;
  75         sector_t array_sectors;
  76 
  77         conf = mddev->private;
  78         WARN_ONCE(sectors || raid_disks,
  79                   "%s does not support generic reshape\n", __func__);
  80         array_sectors = conf->array_sectors;
  81 
  82         return array_sectors;
  83 }
  84 
  85 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
  86 {
  87         struct linear_conf *conf;
  88         struct md_rdev *rdev;
  89         int i, cnt;
  90         bool discard_supported = false;
  91 
  92         conf = kzalloc(struct_size(conf, disks, raid_disks), 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                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
 134         else
 135                 blk_queue_flag_set(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         /*
 148          * conf->raid_disks is copy of mddev->raid_disks. The reason to
 149          * keep a copy of mddev->raid_disks in struct linear_conf is,
 150          * mddev->raid_disks may not be consistent with pointers number of
 151          * conf->disks[] when it is updated in linear_add() and used to
 152          * iterate old conf->disks[] earray in linear_congested().
 153          * Here conf->raid_disks is always consitent with number of
 154          * pointers in conf->disks[] array, and mddev->private is updated
 155          * with rcu_assign_pointer() in linear_addr(), such race can be
 156          * avoided.
 157          */
 158         conf->raid_disks = raid_disks;
 159 
 160         return conf;
 161 
 162 out:
 163         kfree(conf);
 164         return NULL;
 165 }
 166 
 167 static int linear_run (struct mddev *mddev)
 168 {
 169         struct linear_conf *conf;
 170         int ret;
 171 
 172         if (md_check_no_bitmap(mddev))
 173                 return -EINVAL;
 174         conf = linear_conf(mddev, mddev->raid_disks);
 175 
 176         if (!conf)
 177                 return 1;
 178         mddev->private = conf;
 179         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 180 
 181         ret =  md_integrity_register(mddev);
 182         if (ret) {
 183                 kfree(conf);
 184                 mddev->private = NULL;
 185         }
 186         return ret;
 187 }
 188 
 189 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
 190 {
 191         /* Adding a drive to a linear array allows the array to grow.
 192          * It is permitted if the new drive has a matching superblock
 193          * already on it, with raid_disk equal to raid_disks.
 194          * It is achieved by creating a new linear_private_data structure
 195          * and swapping it in in-place of the current one.
 196          * The current one is never freed until the array is stopped.
 197          * This avoids races.
 198          */
 199         struct linear_conf *newconf, *oldconf;
 200 
 201         if (rdev->saved_raid_disk != mddev->raid_disks)
 202                 return -EINVAL;
 203 
 204         rdev->raid_disk = rdev->saved_raid_disk;
 205         rdev->saved_raid_disk = -1;
 206 
 207         newconf = linear_conf(mddev,mddev->raid_disks+1);
 208 
 209         if (!newconf)
 210                 return -ENOMEM;
 211 
 212         /* newconf->raid_disks already keeps a copy of * the increased
 213          * value of mddev->raid_disks, WARN_ONCE() is just used to make
 214          * sure of this. It is possible that oldconf is still referenced
 215          * in linear_congested(), therefore kfree_rcu() is used to free
 216          * oldconf until no one uses it anymore.
 217          */
 218         mddev_suspend(mddev);
 219         oldconf = rcu_dereference_protected(mddev->private,
 220                         lockdep_is_held(&mddev->reconfig_mutex));
 221         mddev->raid_disks++;
 222         WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
 223                 "copied raid_disks doesn't match mddev->raid_disks");
 224         rcu_assign_pointer(mddev->private, newconf);
 225         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 226         set_capacity(mddev->gendisk, mddev->array_sectors);
 227         mddev_resume(mddev);
 228         revalidate_disk(mddev->gendisk);
 229         kfree_rcu(oldconf, rcu);
 230         return 0;
 231 }
 232 
 233 static void linear_free(struct mddev *mddev, void *priv)
 234 {
 235         struct linear_conf *conf = priv;
 236 
 237         kfree(conf);
 238 }
 239 
 240 static bool linear_make_request(struct mddev *mddev, struct bio *bio)
 241 {
 242         char b[BDEVNAME_SIZE];
 243         struct dev_info *tmp_dev;
 244         sector_t start_sector, end_sector, data_offset;
 245         sector_t bio_sector = bio->bi_iter.bi_sector;
 246 
 247         if (unlikely(bio->bi_opf & REQ_PREFLUSH)
 248             && md_flush_request(mddev, bio))
 249                 return true;
 250 
 251         tmp_dev = which_dev(mddev, bio_sector);
 252         start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
 253         end_sector = tmp_dev->end_sector;
 254         data_offset = tmp_dev->rdev->data_offset;
 255 
 256         if (unlikely(bio_sector >= end_sector ||
 257                      bio_sector < start_sector))
 258                 goto out_of_bounds;
 259 
 260         if (unlikely(is_mddev_broken(tmp_dev->rdev, "linear"))) {
 261                 bio_io_error(bio);
 262                 return true;
 263         }
 264 
 265         if (unlikely(bio_end_sector(bio) > end_sector)) {
 266                 /* This bio crosses a device boundary, so we have to split it */
 267                 struct bio *split = bio_split(bio, end_sector - bio_sector,
 268                                               GFP_NOIO, &mddev->bio_set);
 269                 bio_chain(split, bio);
 270                 generic_make_request(bio);
 271                 bio = split;
 272         }
 273 
 274         bio_set_dev(bio, tmp_dev->rdev->bdev);
 275         bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
 276                 start_sector + data_offset;
 277 
 278         if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
 279                      !blk_queue_discard(bio->bi_disk->queue))) {
 280                 /* Just ignore it */
 281                 bio_endio(bio);
 282         } else {
 283                 if (mddev->gendisk)
 284                         trace_block_bio_remap(bio->bi_disk->queue,
 285                                               bio, disk_devt(mddev->gendisk),
 286                                               bio_sector);
 287                 mddev_check_writesame(mddev, bio);
 288                 mddev_check_write_zeroes(mddev, bio);
 289                 generic_make_request(bio);
 290         }
 291         return true;
 292 
 293 out_of_bounds:
 294         pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
 295                mdname(mddev),
 296                (unsigned long long)bio->bi_iter.bi_sector,
 297                bdevname(tmp_dev->rdev->bdev, b),
 298                (unsigned long long)tmp_dev->rdev->sectors,
 299                (unsigned long long)start_sector);
 300         bio_io_error(bio);
 301         return true;
 302 }
 303 
 304 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 305 {
 306         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 307 }
 308 
 309 static void linear_quiesce(struct mddev *mddev, int state)
 310 {
 311 }
 312 
 313 static struct md_personality linear_personality =
 314 {
 315         .name           = "linear",
 316         .level          = LEVEL_LINEAR,
 317         .owner          = THIS_MODULE,
 318         .make_request   = linear_make_request,
 319         .run            = linear_run,
 320         .free           = linear_free,
 321         .status         = linear_status,
 322         .hot_add_disk   = linear_add,
 323         .size           = linear_size,
 324         .quiesce        = linear_quiesce,
 325         .congested      = linear_congested,
 326 };
 327 
 328 static int __init linear_init (void)
 329 {
 330         return register_md_personality (&linear_personality);
 331 }
 332 
 333 static void linear_exit (void)
 334 {
 335         unregister_md_personality (&linear_personality);
 336 }
 337 
 338 module_init(linear_init);
 339 module_exit(linear_exit);
 340 MODULE_LICENSE("GPL");
 341 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 342 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 343 MODULE_ALIAS("md-linear");
 344 MODULE_ALIAS("md-level--1");