LXR linux/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#define DM_MSG_PREFIX "linear"
  16
  17/*
  18 * Linear: maps a linear range of a device.
  19 */
  20struct linear_c {
  21        struct dm_dev *dev;
  22        sector_t start;
  23};
  24
  25/*
  26 * Construct a linear mapping: <dev_path> <offset>
  27 */
  28static 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
  64static 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
  72static int linear_map(struct dm_target *ti, struct bio *bio,
  73                      union map_info *map_context)
  74{
  75        struct linear_c *lc = (struct linear_c *) ti->private;
  76
  77        bio->bi_bdev = lc->dev->bdev;
  78        bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
  79
  80        return DM_MAPIO_REMAPPED;
  81}
  82
  83static int linear_status(struct dm_target *ti, status_type_t type,
  84                         char *result, unsigned int maxlen)
  85{
  86        struct linear_c *lc = (struct linear_c *) ti->private;
  87
  88        switch (type) {
  89        case STATUSTYPE_INFO:
  90                result[0] = '\0';
  91                break;
  92
  93        case STATUSTYPE_TABLE:
  94                snprintf(result, maxlen, "%s %llu", lc->dev->name,
  95                                (unsigned long long)lc->start);
  96                break;
  97        }
  98        return 0;
  99}
 100
 101static int linear_ioctl(struct dm_target *ti, struct inode *inode,
 102                        struct file *filp, unsigned int cmd,
 103                        unsigned long arg)
 104{
 105        struct linear_c *lc = (struct linear_c *) ti->private;
 106        struct block_device *bdev = lc->dev->bdev;
 107        struct file fake_file = {};
 108        struct dentry fake_dentry = {};
 109
 110        fake_file.f_mode = lc->dev->mode;
 111        fake_file.f_path.dentry = &fake_dentry;
 112        fake_dentry.d_inode = bdev->bd_inode;
 113
 114        return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
 115}
 116
 117static struct target_type linear_target = {
 118        .name   = "linear",
 119        .version= {1, 0, 2},
 120        .module = THIS_MODULE,
 121        .ctr    = linear_ctr,
 122        .dtr    = linear_dtr,
 123        .map    = linear_map,
 124        .status = linear_status,
 125        .ioctl  = linear_ioctl,
 126};
 127
 128int __init dm_linear_init(void)
 129{
 130        int r = dm_register_target(&linear_target);
 131
 132        if (r < 0)
 133                DMERR("register failed %d", r);
 134
 135        return r;
 136}
 137
 138void dm_linear_exit(void)
 139{
 140        int r = dm_unregister_target(&linear_target);
 141
 142        if (r < 0)
 143                DMERR("unregister failed %d", r);
 144}
 145