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->num_write_zeroes_bios = 1;
  63         ti->private = lc;
  64         return 0;
  65
  66       bad:
  67         kfree(lc);
  68         return ret;
  69 }
  70
  71 static void linear_dtr(struct dm_target *ti)
  72 {
  73         struct linear_c *lc = (struct linear_c *) ti->private;
  74
  75         dm_put_device(ti, lc->dev);
  76         kfree(lc);
  77 }
  78
  79 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
  80 {
  81         struct linear_c *lc = ti->private;
  82
  83         return lc->start + dm_target_offset(ti, bi_sector);
  84 }
  85
  86 static void linear_map_bio(struct dm_target *ti, struct bio *bio)
  87 {
  88         struct linear_c *lc = ti->private;
  89
  90         bio->bi_bdev = lc->dev->bdev;
  91         if (bio_sectors(bio))
  92                 bio->bi_iter.bi_sector =
  93                         linear_map_sector(ti, bio->bi_iter.bi_sector);
  94 }
  95
  96 static int linear_map(struct dm_target *ti, struct bio *bio)
  97 {
  98         linear_map_bio(ti, bio);
  99
 100         return DM_MAPIO_REMAPPED;
 101 }
 102
 103 static void linear_status(struct dm_target *ti, status_type_t type,
 104                           unsigned status_flags, char *result, unsigned maxlen)
 105 {
 106         struct linear_c *lc = (struct linear_c *) ti->private;
 107
 108         switch (type) {
 109         case STATUSTYPE_INFO:
 110                 result[0] = '\0';
 111                 break;
 112
 113         case STATUSTYPE_TABLE:
 114                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 115                                 (unsigned long long)lc->start);
 116                 break;
 117         }
 118 }
 119
 120 static int linear_prepare_ioctl(struct dm_target *ti,
 121                 struct block_device **bdev, fmode_t *mode)
 122 {
 123         struct linear_c *lc = (struct linear_c *) ti->private;
 124         struct dm_dev *dev = lc->dev;
 125
 126         *bdev = dev->bdev;
 127
 128         /*
 129          * Only pass ioctls through if the device sizes match exactly.
 130          */
 131         if (lc->start ||
 132             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
 133                 return 1;
 134         return 0;
 135 }
 136
 137 static int linear_iterate_devices(struct dm_target *ti,
 138                                   iterate_devices_callout_fn fn, void *data)
 139 {
 140         struct linear_c *lc = ti->private;
 141
 142         return fn(ti, lc->dev, lc->start, ti->len, data);
 143 }
 144
 145 static long linear_direct_access(struct dm_target *ti, sector_t sector,
 146                                  void **kaddr, pfn_t *pfn, long size)
 147 {
 148         struct linear_c *lc = ti->private;
 149         struct block_device *bdev = lc->dev->bdev;
 150         struct blk_dax_ctl dax = {
 151                 .sector = linear_map_sector(ti, sector),
 152                 .size = size,
 153         };
 154         long ret;
 155
 156         ret = bdev_direct_access(bdev, &dax);
 157         *kaddr = dax.addr;
 158         *pfn = dax.pfn;
 159
 160         return ret;
 161 }
 162
 163 static struct target_type linear_target = {
 164         .name   = "linear",
 165         .version = {1, 3, 0},
 166         .features = DM_TARGET_PASSES_INTEGRITY,
 167         .module = THIS_MODULE,
 168         .ctr    = linear_ctr,
 169         .dtr    = linear_dtr,
 170         .map    = linear_map,
 171         .status = linear_status,
 172         .prepare_ioctl = linear_prepare_ioctl,
 173         .iterate_devices = linear_iterate_devices,
 174         .direct_access = linear_direct_access,
 175 };
 176
 177 int __init dm_linear_init(void)
 178 {
 179         int r = dm_register_target(&linear_target);
 180
 181         if (r < 0)
 182                 DMERR("register failed %d", r);
 183
 184         return r;
 185 }
 186
 187 void dm_linear_exit(void)
 188 {
 189         dm_unregister_target(&linear_target);
 190 }