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         char dummy;
  33         int ret;
  34
  35         if (argc != 2) {
  36                 ti->error = "Invalid argument count";
  37                 return -EINVAL;
  38         }
  39
  40         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  41         if (lc == NULL) {
  42                 ti->error = "Cannot allocate linear context";
  43                 return -ENOMEM;
  44         }
  45
  46         ret = -EINVAL;
  47         if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
  48                 ti->error = "Invalid device sector";
  49                 goto bad;
  50         }
  51         lc->start = tmp;
  52
  53         ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
  54         if (ret) {
  55                 ti->error = "Device lookup failed";
  56                 goto bad;
  57         }
  58
  59         ti->num_flush_bios = 1;
  60         ti->num_discard_bios = 1;
  61         ti->num_write_same_bios = 1;
  62         ti->private = lc;
  63         return 0;
  64
  65       bad:
  66         kfree(lc);
  67         return ret;
  68 }
  69
  70 static void linear_dtr(struct dm_target *ti)
  71 {
  72         struct linear_c *lc = (struct linear_c *) ti->private;
  73
  74         dm_put_device(ti, lc->dev);
  75         kfree(lc);
  76 }
  77
  78 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
  79 {
  80         struct linear_c *lc = ti->private;
  81
  82         return lc->start + dm_target_offset(ti, bi_sector);
  83 }
  84
  85 static void linear_map_bio(struct dm_target *ti, struct bio *bio)
  86 {
  87         struct linear_c *lc = ti->private;
  88
  89         bio->bi_bdev = lc->dev->bdev;
  90         if (bio_sectors(bio))
  91                 bio->bi_iter.bi_sector =
  92                         linear_map_sector(ti, bio->bi_iter.bi_sector);
  93 }
  94
  95 static int linear_map(struct dm_target *ti, struct bio *bio)
  96 {
  97         linear_map_bio(ti, bio);
  98
  99         return DM_MAPIO_REMAPPED;
 100 }
 101
 102 static void linear_status(struct dm_target *ti, status_type_t type,
 103                           unsigned status_flags, char *result, unsigned maxlen)
 104 {
 105         struct linear_c *lc = (struct linear_c *) ti->private;
 106
 107         switch (type) {
 108         case STATUSTYPE_INFO:
 109                 result[0] = '\0';
 110                 break;
 111
 112         case STATUSTYPE_TABLE:
 113                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 114                                 (unsigned long long)lc->start);
 115                 break;
 116         }
 117 }
 118
 119 static int linear_prepare_ioctl(struct dm_target *ti,
 120                 struct block_device **bdev, fmode_t *mode)
 121 {
 122         struct linear_c *lc = (struct linear_c *) ti->private;
 123         struct dm_dev *dev = lc->dev;
 124
 125         *bdev = dev->bdev;
 126
 127         /*
 128          * Only pass ioctls through if the device sizes match exactly.
 129          */
 130         if (lc->start ||
 131             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
 132                 return 1;
 133         return 0;
 134 }
 135
 136 static int linear_iterate_devices(struct dm_target *ti,
 137                                   iterate_devices_callout_fn fn, void *data)
 138 {
 139         struct linear_c *lc = ti->private;
 140
 141         return fn(ti, lc->dev, lc->start, ti->len, data);
 142 }
 143
 144 static struct target_type linear_target = {
 145         .name   = "linear",
 146         .version = {1, 2, 1},
 147         .module = THIS_MODULE,
 148         .ctr    = linear_ctr,
 149         .dtr    = linear_dtr,
 150         .map    = linear_map,
 151         .status = linear_status,
 152         .prepare_ioctl = linear_prepare_ioctl,
 153         .iterate_devices = linear_iterate_devices,
 154 };
 155
 156 int __init dm_linear_init(void)
 157 {
 158         int r = dm_register_target(&linear_target);
 159
 160         if (r < 0)
 161                 DMERR("register failed %d", r);
 162
 163         return r;
 164 }
 165
 166 void dm_linear_exit(void)
 167 {
 168         dm_unregister_target(&linear_target);
 169 }