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_secure_erase_bios = 1;
  63         ti->num_write_same_bios = 1;
  64         ti->num_write_zeroes_bios = 1;
  65         ti->private = lc;
  66         return 0;
  67
  68       bad:
  69         kfree(lc);
  70         return ret;
  71 }
  72
  73 static void linear_dtr(struct dm_target *ti)
  74 {
  75         struct linear_c *lc = (struct linear_c *) ti->private;
  76
  77         dm_put_device(ti, lc->dev);
  78         kfree(lc);
  79 }
  80
  81 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
  82 {
  83         struct linear_c *lc = ti->private;
  84
  85         return lc->start + dm_target_offset(ti, bi_sector);
  86 }
  87
  88 static void linear_map_bio(struct dm_target *ti, struct bio *bio)
  89 {
  90         struct linear_c *lc = ti->private;
  91
  92         bio_set_dev(bio, lc->dev->bdev);
  93         if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)
  94                 bio->bi_iter.bi_sector =
  95                         linear_map_sector(ti, bio->bi_iter.bi_sector);
  96 }
  97
  98 static int linear_map(struct dm_target *ti, struct bio *bio)
  99 {
 100         linear_map_bio(ti, bio);
 101
 102         return DM_MAPIO_REMAPPED;
 103 }
 104
 105 static int linear_end_io(struct dm_target *ti, struct bio *bio,
 106                          blk_status_t *error)
 107 {
 108         struct linear_c *lc = ti->private;
 109
 110         if (!*error && bio_op(bio) == REQ_OP_ZONE_REPORT)
 111                 dm_remap_zone_report(ti, bio, lc->start);
 112
 113         return DM_ENDIO_DONE;
 114 }
 115
 116 static void linear_status(struct dm_target *ti, status_type_t type,
 117                           unsigned status_flags, char *result, unsigned maxlen)
 118 {
 119         struct linear_c *lc = (struct linear_c *) ti->private;
 120
 121         switch (type) {
 122         case STATUSTYPE_INFO:
 123                 result[0] = '\0';
 124                 break;
 125
 126         case STATUSTYPE_TABLE:
 127                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 128                                 (unsigned long long)lc->start);
 129                 break;
 130         }
 131 }
 132
 133 static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 134 {
 135         struct linear_c *lc = (struct linear_c *) ti->private;
 136         struct dm_dev *dev = lc->dev;
 137
 138         *bdev = dev->bdev;
 139
 140         /*
 141          * Only pass ioctls through if the device sizes match exactly.
 142          */
 143         if (lc->start ||
 144             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
 145                 return 1;
 146         return 0;
 147 }
 148
 149 static int linear_iterate_devices(struct dm_target *ti,
 150                                   iterate_devices_callout_fn fn, void *data)
 151 {
 152         struct linear_c *lc = ti->private;
 153
 154         return fn(ti, lc->dev, lc->start, ti->len, data);
 155 }
 156
 157 #if IS_ENABLED(CONFIG_DAX_DRIVER)
 158 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 159                 long nr_pages, void **kaddr, pfn_t *pfn)
 160 {
 161         long ret;
 162         struct linear_c *lc = ti->private;
 163         struct block_device *bdev = lc->dev->bdev;
 164         struct dax_device *dax_dev = lc->dev->dax_dev;
 165         sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 166
 167         dev_sector = linear_map_sector(ti, sector);
 168         ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
 169         if (ret)
 170                 return ret;
 171         return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
 172 }
 173
 174 static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
 175                 void *addr, size_t bytes, struct iov_iter *i)
 176 {
 177         struct linear_c *lc = ti->private;
 178         struct block_device *bdev = lc->dev->bdev;
 179         struct dax_device *dax_dev = lc->dev->dax_dev;
 180         sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 181
 182         dev_sector = linear_map_sector(ti, sector);
 183         if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
 184                 return 0;
 185         return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 186 }
 187
 188 #else
 189 #define linear_dax_direct_access NULL
 190 #define linear_dax_copy_from_iter NULL
 191 #endif
 192
 193 static struct target_type linear_target = {
 194         .name   = "linear",
 195         .version = {1, 4, 0},
 196         .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM,
 197         .module = THIS_MODULE,
 198         .ctr    = linear_ctr,
 199         .dtr    = linear_dtr,
 200         .map    = linear_map,
 201         .end_io = linear_end_io,
 202         .status = linear_status,
 203         .prepare_ioctl = linear_prepare_ioctl,
 204         .iterate_devices = linear_iterate_devices,
 205         .direct_access = linear_dax_direct_access,
 206         .dax_copy_from_iter = linear_dax_copy_from_iter,
 207 };
 208
 209 int __init dm_linear_init(void)
 210 {
 211         int r = dm_register_target(&linear_target);
 212
 213         if (r < 0)
 214                 DMERR("register failed %d", r);
 215
 216         return r;
 217 }
 218
 219 void dm_linear_exit(void)
 220 {
 221         dm_unregister_target(&linear_target);
 222 }