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/dax.h>
  13 #include <linux/slab.h>
  14 #include <linux/device-mapper.h>
  15
  16 #define DM_MSG_PREFIX "linear"
  17
  18 /*
  19  * Linear: maps a linear range of a device.
  20  */
  21 struct linear_c {
  22         struct dm_dev *dev;
  23         sector_t start;
  24 };
  25
  26 /*
  27  * Construct a linear mapping: <dev_path> <offset>
  28  */
  29 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  30 {
  31         struct linear_c *lc;
  32         unsigned long long tmp;
  33         char dummy;
  34         int ret;
  35
  36         if (argc != 2) {
  37                 ti->error = "Invalid argument count";
  38                 return -EINVAL;
  39         }
  40
  41         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  42         if (lc == NULL) {
  43                 ti->error = "Cannot allocate linear context";
  44                 return -ENOMEM;
  45         }
  46
  47         ret = -EINVAL;
  48         if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
  49                 ti->error = "Invalid device sector";
  50                 goto bad;
  51         }
  52         lc->start = tmp;
  53
  54         ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
  55         if (ret) {
  56                 ti->error = "Device lookup failed";
  57                 goto bad;
  58         }
  59
  60         ti->num_flush_bios = 1;
  61         ti->num_discard_bios = 1;
  62         ti->num_write_same_bios = 1;
  63         ti->num_write_zeroes_bios = 1;
  64         ti->private = lc;
  65         return 0;
  66
  67       bad:
  68         kfree(lc);
  69         return ret;
  70 }
  71
  72 static void linear_dtr(struct dm_target *ti)
  73 {
  74         struct linear_c *lc = (struct linear_c *) ti->private;
  75
  76         dm_put_device(ti, lc->dev);
  77         kfree(lc);
  78 }
  79
  80 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
  81 {
  82         struct linear_c *lc = ti->private;
  83
  84         return lc->start + dm_target_offset(ti, bi_sector);
  85 }
  86
  87 static void linear_map_bio(struct dm_target *ti, struct bio *bio)
  88 {
  89         struct linear_c *lc = ti->private;
  90
  91         bio->bi_bdev = lc->dev->bdev;
  92         if (bio_sectors(bio))
  93                 bio->bi_iter.bi_sector =
  94                         linear_map_sector(ti, bio->bi_iter.bi_sector);
  95 }
  96
  97 static int linear_map(struct dm_target *ti, struct bio *bio)
  98 {
  99         linear_map_bio(ti, bio);
 100
 101         return DM_MAPIO_REMAPPED;
 102 }
 103
 104 static void linear_status(struct dm_target *ti, status_type_t type,
 105                           unsigned status_flags, char *result, unsigned maxlen)
 106 {
 107         struct linear_c *lc = (struct linear_c *) ti->private;
 108
 109         switch (type) {
 110         case STATUSTYPE_INFO:
 111                 result[0] = '\0';
 112                 break;
 113
 114         case STATUSTYPE_TABLE:
 115                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 116                                 (unsigned long long)lc->start);
 117                 break;
 118         }
 119 }
 120
 121 static int linear_prepare_ioctl(struct dm_target *ti,
 122                 struct block_device **bdev, fmode_t *mode)
 123 {
 124         struct linear_c *lc = (struct linear_c *) ti->private;
 125         struct dm_dev *dev = lc->dev;
 126
 127         *bdev = dev->bdev;
 128
 129         /*
 130          * Only pass ioctls through if the device sizes match exactly.
 131          */
 132         if (lc->start ||
 133             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
 134                 return 1;
 135         return 0;
 136 }
 137
 138 static int linear_iterate_devices(struct dm_target *ti,
 139                                   iterate_devices_callout_fn fn, void *data)
 140 {
 141         struct linear_c *lc = ti->private;
 142
 143         return fn(ti, lc->dev, lc->start, ti->len, data);
 144 }
 145
 146 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 147                 long nr_pages, void **kaddr, pfn_t *pfn)
 148 {
 149         long ret;
 150         struct linear_c *lc = ti->private;
 151         struct block_device *bdev = lc->dev->bdev;
 152         struct dax_device *dax_dev = lc->dev->dax_dev;
 153         sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 154
 155         dev_sector = linear_map_sector(ti, sector);
 156         ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
 157         if (ret)
 158                 return ret;
 159         return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
 160 }
 161
 162 static struct target_type linear_target = {
 163         .name   = "linear",
 164         .version = {1, 3, 0},
 165         .features = DM_TARGET_PASSES_INTEGRITY,
 166         .module = THIS_MODULE,
 167         .ctr    = linear_ctr,
 168         .dtr    = linear_dtr,
 169         .map    = linear_map,
 170         .status = linear_status,
 171         .prepare_ioctl = linear_prepare_ioctl,
 172         .iterate_devices = linear_iterate_devices,
 173         .direct_access = linear_dax_direct_access,
 174 };
 175
 176 int __init dm_linear_init(void)
 177 {
 178         int r = dm_register_target(&linear_target);
 179
 180         if (r < 0)
 181                 DMERR("register failed %d", r);
 182
 183         return r;
 184 }
 185
 186 void dm_linear_exit(void)
 187 {
 188         dm_unregister_target(&linear_target);
 189 }