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         unsigned long long tmp;
  30
  31         if (argc != 2) {
  32                 ti->error = "dm-linear: Invalid argument count";
  33                 return -EINVAL;
  34         }
  35
  36         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  37         if (lc == NULL) {
  38                 ti->error = "dm-linear: Cannot allocate linear context";
  39                 return -ENOMEM;
  40         }
  41
  42         if (sscanf(argv[1], "%llu", &tmp) != 1) {
  43                 ti->error = "dm-linear: Invalid device sector";
  44                 goto bad;
  45         }
  46         lc->start = tmp;
  47
  48         if (dm_get_device(ti, argv[0], lc->start, ti->len,
  49                           dm_table_get_mode(ti->table), &lc->dev)) {
  50                 ti->error = "dm-linear: Device lookup failed";
  51                 goto bad;
  52         }
  53
  54         ti->private = lc;
  55         return 0;
  56
  57       bad:
  58         kfree(lc);
  59         return -EINVAL;
  60 }
  61
  62 static void linear_dtr(struct dm_target *ti)
  63 {
  64         struct linear_c *lc = (struct linear_c *) ti->private;
  65
  66         dm_put_device(ti, lc->dev);
  67         kfree(lc);
  68 }
  69
  70 static int linear_map(struct dm_target *ti, struct bio *bio,
  71                       union map_info *map_context)
  72 {
  73         struct linear_c *lc = (struct linear_c *) ti->private;
  74
  75         bio->bi_bdev = lc->dev->bdev;
  76         bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
  77
  78         return 1;
  79 }
  80
  81 static int linear_status(struct dm_target *ti, status_type_t type,
  82                          char *result, unsigned int maxlen)
  83 {
  84         struct linear_c *lc = (struct linear_c *) ti->private;
  85
  86         switch (type) {
  87         case STATUSTYPE_INFO:
  88                 result[0] = '\0';
  89                 break;
  90
  91         case STATUSTYPE_TABLE:
  92                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
  93                                 (unsigned long long)lc->start);
  94                 break;
  95         }
  96         return 0;
  97 }
  98
  99 static struct target_type linear_target = {
 100         .name   = "linear",
 101         .version= {1, 0, 1},
 102         .module = THIS_MODULE,
 103         .ctr    = linear_ctr,
 104         .dtr    = linear_dtr,
 105         .map    = linear_map,
 106         .status = linear_status,
 107 };
 108
 109 int __init dm_linear_init(void)
 110 {
 111         int r = dm_register_target(&linear_target);
 112
 113         if (r < 0)
 114                 DMERR("linear: register failed %d", r);
 115
 116         return r;
 117 }
 118
 119 void dm_linear_exit(void)
 120 {
 121         int r = dm_unregister_target(&linear_target);
 122
 123         if (r < 0)
 124                 DMERR("linear: unregister failed %d", r);
 125 }