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 || tmp != (sector_t)tmp) {
  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) || op_is_zone_mgmt(bio_op(bio)))
  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 void linear_status(struct dm_target *ti, status_type_t type,
 106                           unsigned status_flags, char *result, unsigned maxlen)
 107 {
 108         struct linear_c *lc = (struct linear_c *) ti->private;
 109
 110         switch (type) {
 111         case STATUSTYPE_INFO:
 112                 result[0] = '\0';
 113                 break;
 114
 115         case STATUSTYPE_TABLE:
 116                 snprintf(result, maxlen, "%s %llu", lc->dev->name,
 117                                 (unsigned long long)lc->start);
 118                 break;
 119         }
 120 }
 121
 122 static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 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 #ifdef CONFIG_BLK_DEV_ZONED
 139 static int linear_report_zones(struct dm_target *ti,
 140                 struct dm_report_zones_args *args, unsigned int nr_zones)
 141 {
 142         struct linear_c *lc = ti->private;
 143         sector_t sector = linear_map_sector(ti, args->next_sector);
 144
 145         args->start = lc->start;
 146         return blkdev_report_zones(lc->dev->bdev, sector, nr_zones,
 147                                    dm_report_zones_cb, args);
 148 }
 149 #endif
 150
 151 static int linear_iterate_devices(struct dm_target *ti,
 152                                   iterate_devices_callout_fn fn, void *data)
 153 {
 154         struct linear_c *lc = ti->private;
 155
 156         return fn(ti, lc->dev, lc->start, ti->len, data);
 157 }
 158
 159 #if IS_ENABLED(CONFIG_DAX_DRIVER)
 160 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 161                 long nr_pages, void **kaddr, pfn_t *pfn)
 162 {
 163         long ret;
 164         struct linear_c *lc = ti->private;
 165         struct block_device *bdev = lc->dev->bdev;
 166         struct dax_device *dax_dev = lc->dev->dax_dev;
 167         sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 168
 169         dev_sector = linear_map_sector(ti, sector);
 170         ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
 171         if (ret)
 172                 return ret;
 173         return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
 174 }
 175
 176 static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
 177                 void *addr, size_t bytes, struct iov_iter *i)
 178 {
 179         struct linear_c *lc = ti->private;
 180         struct block_device *bdev = lc->dev->bdev;
 181         struct dax_device *dax_dev = lc->dev->dax_dev;
 182         sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 183
 184         dev_sector = linear_map_sector(ti, sector);
 185         if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
 186                 return 0;
 187         return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 188 }
 189
 190 static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
 191                 void *addr, size_t bytes, struct iov_iter *i)
 192 {
 193         struct linear_c *lc = ti->private;
 194         struct block_device *bdev = lc->dev->bdev;
 195         struct dax_device *dax_dev = lc->dev->dax_dev;
 196         sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 197
 198         dev_sector = linear_map_sector(ti, sector);
 199         if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
 200                 return 0;
 201         return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
 202 }
 203
 204 #else
 205 #define linear_dax_direct_access NULL
 206 #define linear_dax_copy_from_iter NULL
 207 #define linear_dax_copy_to_iter NULL
 208 #endif
 209
 210 static struct target_type linear_target = {
 211         .name   = "linear",
 212         .version = {1, 4, 0},
 213 #ifdef CONFIG_BLK_DEV_ZONED
 214         .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM,
 215         .report_zones = linear_report_zones,
 216 #else
 217         .features = DM_TARGET_PASSES_INTEGRITY,
 218 #endif
 219         .module = THIS_MODULE,
 220         .ctr    = linear_ctr,
 221         .dtr    = linear_dtr,
 222         .map    = linear_map,
 223         .status = linear_status,
 224         .prepare_ioctl = linear_prepare_ioctl,
 225         .iterate_devices = linear_iterate_devices,
 226         .direct_access = linear_dax_direct_access,
 227         .dax_copy_from_iter = linear_dax_copy_from_iter,
 228         .dax_copy_to_iter = linear_dax_copy_to_iter,
 229 };
 230
 231 int __init dm_linear_init(void)
 232 {
 233         int r = dm_register_target(&linear_target);
 234
 235         if (r < 0)
 236                 DMERR("register failed %d", r);
 237
 238         return r;
 239 }
 240
 241 void dm_linear_exit(void)
 242 {
 243         dm_unregister_target(&linear_target);
 244 }