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], dm_table_get_mode(ti->table), &lc->dev)) {
  51                 ti->error = "dm-linear: Device lookup failed";
  52                 goto bad;
  53         }
  54
  55         ti->num_flush_requests = 1;
  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         if (bio_sectors(bio))
  85                 bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
  86 }
  87
  88 static int linear_map(struct dm_target *ti, struct bio *bio,
  89                       union map_info *map_context)
  90 {
  91         linear_map_bio(ti, bio);
  92
  93         return DM_MAPIO_REMAPPED;
  94 }
  95
  96 static int linear_status(struct dm_target *ti, status_type_t type,
  97                          char *result, unsigned int maxlen)
  98 {
  99         struct linear_c *lc = (struct linear_c *) ti->private;
 100
 101         switch (type) {
 102         case STATUSTYPE_INFO:
 103                 result[0] = '\0';
 104                 break;
 105
 106         case STATUSTYPE_TABLE:
 107                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 108                                 (unsigned long long)lc->start);
 109                 break;
 110         }
 111         return 0;
 112 }
 113
 114 static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
 115                         unsigned long arg)
 116 {
 117         struct linear_c *lc = (struct linear_c *) ti->private;
 118         return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
 119 }
 120
 121 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 122                         struct bio_vec *biovec, int max_size)
 123 {
 124         struct linear_c *lc = ti->private;
 125         struct request_queue *q = bdev_get_queue(lc->dev->bdev);
 126
 127         if (!q->merge_bvec_fn)
 128                 return max_size;
 129
 130         bvm->bi_bdev = lc->dev->bdev;
 131         bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
 132
 133         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 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, 1, 0},
 147         .module = THIS_MODULE,
 148         .ctr    = linear_ctr,
 149         .dtr    = linear_dtr,
 150         .map    = linear_map,
 151         .status = linear_status,
 152         .ioctl  = linear_ioctl,
 153         .merge  = linear_merge,
 154         .iterate_devices = linear_iterate_devices,
 155 };
 156
 157 int __init dm_linear_init(void)
 158 {
 159         int r = dm_register_target(&linear_target);
 160
 161         if (r < 0)
 162                 DMERR("register failed %d", r);
 163
 164         return r;
 165 }
 166
 167 void dm_linear_exit(void)
 168 {
 169         dm_unregister_target(&linear_target);
 170 }