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  */
  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 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
  83 static 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
 101 static 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
 117 static 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
 128 int __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
 138 void 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 }