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 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/bio.h>
  12 #include <linux/slab.h>
  13 #include <linux/device-mapper.h>
  14
  15 #define DM_MSG_PREFIX "linear"
  16
  17 /*
  18  * Linear: maps a linear range of a device.
  19  */
  20 struct linear_c {
  21         struct dm_dev *dev;
  22         sector_t start;
  23 };
  24
  25 /*
  26  * Construct a linear mapping: <dev_path> <offset>
  27  */
  28 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  29 {
  30         struct linear_c *lc;
  31         unsigned long long tmp;
  32
  33         if (argc != 2) {
  34                 ti->error = "Invalid argument count";
  35                 return -EINVAL;
  36         }
  37
  38         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  39         if (lc == NULL) {
  40                 ti->error = "dm-linear: Cannot allocate linear context";
  41                 return -ENOMEM;
  42         }
  43
  44         if (sscanf(argv[1], "%llu", &tmp) != 1) {
  45                 ti->error = "dm-linear: Invalid device sector";
  46                 goto bad;
  47         }
  48         lc->start = tmp;
  49
  50         if (dm_get_device(ti, argv[0], lc->start, ti->len,
  51                           dm_table_get_mode(ti->table), &lc->dev)) {
  52                 ti->error = "dm-linear: Device lookup failed";
  53                 goto bad;
  54         }
  55
  56         ti->private = lc;
  57         return 0;
  58
  59       bad:
  60         kfree(lc);
  61         return -EINVAL;
  62 }
  63
  64 static void linear_dtr(struct dm_target *ti)
  65 {
  66         struct linear_c *lc = (struct linear_c *) ti->private;
  67
  68         dm_put_device(ti, lc->dev);
  69         kfree(lc);
  70 }
  71
  72 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
  73 {
  74         struct linear_c *lc = ti->private;
  75
  76         return lc->start + (bi_sector - ti->begin);
  77 }
  78
  79 static void linear_map_bio(struct dm_target *ti, struct bio *bio)
  80 {
  81         struct linear_c *lc = ti->private;
  82
  83         bio->bi_bdev = lc->dev->bdev;
  84         bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
  85 }
  86
  87 static int linear_map(struct dm_target *ti, struct bio *bio,
  88                       union map_info *map_context)
  89 {
  90         linear_map_bio(ti, bio);
  91
  92         return DM_MAPIO_REMAPPED;
  93 }
  94
  95 static int linear_status(struct dm_target *ti, status_type_t type,
  96                          char *result, unsigned int maxlen)
  97 {
  98         struct linear_c *lc = (struct linear_c *) ti->private;
  99
 100         switch (type) {
 101         case STATUSTYPE_INFO:
 102                 result[0] = '\0';
 103                 break;
 104
 105         case STATUSTYPE_TABLE:
 106                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 107                                 (unsigned long long)lc->start);
 108                 break;
 109         }
 110         return 0;
 111 }
 112
 113 static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
 114                         unsigned long arg)
 115 {
 116         struct linear_c *lc = (struct linear_c *) ti->private;
 117         return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
 118 }
 119
 120 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 121                         struct bio_vec *biovec, int max_size)
 122 {
 123         struct linear_c *lc = ti->private;
 124         struct request_queue *q = bdev_get_queue(lc->dev->bdev);
 125
 126         if (!q->merge_bvec_fn)
 127                 return max_size;
 128
 129         bvm->bi_bdev = lc->dev->bdev;
 130         bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
 131
 132         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 133 }
 134
 135 static struct target_type linear_target = {
 136         .name   = "linear",
 137         .version= {1, 0, 3},
 138         .module = THIS_MODULE,
 139         .ctr    = linear_ctr,
 140         .dtr    = linear_dtr,
 141         .map    = linear_map,
 142         .status = linear_status,
 143         .ioctl  = linear_ioctl,
 144         .merge  = linear_merge,
 145         .features = DM_TARGET_SUPPORTS_BARRIERS,
 146 };
 147
 148 int __init dm_linear_init(void)
 149 {
 150         int r = dm_register_target(&linear_target);
 151
 152         if (r < 0)
 153                 DMERR("register failed %d", r);
 154
 155         return r;
 156 }
 157
 158 void dm_linear_exit(void)
 159 {
 160         dm_unregister_target(&linear_target);
 161 }