drivers/md/dm-linear.c

   1 /*
   2  * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm.h"
   8
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/bio.h>
  13 #include <linux/slab.h>
  14
  15 /*
  16  * Linear: maps a linear range of a device.
  17  */
  18 struct linear_c {
  19         struct dm_dev *dev;
  20         sector_t start;
  21 };
  22
  23 /*
  24  * Construct a linear mapping: <dev_path> <offset>
  25  */
  26 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  27 {
  28         struct linear_c *lc;
  29
  30         if (argc != 2) {
  31                 ti->error = "dm-linear: Invalid argument count";
  32                 return -EINVAL;
  33         }
  34
  35         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  36         if (lc == NULL) {
  37                 ti->error = "dm-linear: Cannot allocate linear context";
  38                 return -ENOMEM;
  39         }
  40
  41         if (sscanf(argv[1], SECTOR_FORMAT, &lc->start) != 1) {
  42                 ti->error = "dm-linear: Invalid device sector";
  43                 goto bad;
  44         }
  45
  46         if (dm_get_device(ti, argv[0], lc->start, ti->len,
  47                           dm_table_get_mode(ti->table), &lc->dev)) {
  48                 ti->error = "dm-linear: Device lookup failed";
  49                 goto bad;
  50         }
  51
  52         ti->private = lc;
  53         return 0;
  54
  55       bad:
  56         kfree(lc);
  57         return -EINVAL;
  58 }
  59
  60 static void linear_dtr(struct dm_target *ti)
  61 {
  62         struct linear_c *lc = (struct linear_c *) ti->private;
  63
  64         dm_put_device(ti, lc->dev);
  65         kfree(lc);
  66 }
  67
  68 static int linear_map(struct dm_target *ti, struct bio *bio,
  69                       union map_info *map_context)
  70 {
  71         struct linear_c *lc = (struct linear_c *) ti->private;
  72
  73         bio->bi_bdev = lc->dev->bdev;
  74         bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
  75
  76         return 1;
  77 }
  78
  79 static int linear_status(struct dm_target *ti, status_type_t type,
  80                          char *result, unsigned int maxlen)
  81 {
  82         struct linear_c *lc = (struct linear_c *) ti->private;
  83
  84         switch (type) {
  85         case STATUSTYPE_INFO:
  86                 result[0] = '\0';
  87                 break;
  88
  89         case STATUSTYPE_TABLE:
  90                 snprintf(result, maxlen, "%s " SECTOR_FORMAT, lc->dev->name,
  91                          lc->start);
  92                 break;
  93         }
  94         return 0;
  95 }
  96
  97 static struct target_type linear_target = {
  98         .name   = "linear",
  99         .version= {1, 0, 1},
 100         .module = THIS_MODULE,
 101         .ctr    = linear_ctr,
 102         .dtr    = linear_dtr,
 103         .map    = linear_map,
 104         .status = linear_status,
 105 };
 106
 107 int __init dm_linear_init(void)
 108 {
 109         int r = dm_register_target(&linear_target);
 110
 111         if (r < 0)
 112                 DMERR("linear: register failed %d", r);
 113
 114         return r;
 115 }
 116
 117 void dm_linear_exit(void)
 118 {
 119         int r = dm_unregister_target(&linear_target);
 120
 121         if (r < 0)
 122                 DMERR("linear: unregister failed %d", r);
 123 }