drivers/md/dm-linear.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm.h"
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/bio.h>
  13 #include <linux/dax.h>
  14 #include <linux/slab.h>
  15 #include <linux/device-mapper.h>
  16
  17 #define DM_MSG_PREFIX "linear"
  18
  19 /*
  20  * Linear: maps a linear range of a device.
  21  */
  22 struct linear_c {
  23         struct dm_dev *dev;
  24         sector_t start;
  25 };
  26
  27 /*
  28  * Construct a linear mapping: <dev_path> <offset>
  29  */
  30 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  31 {
  32         struct linear_c *lc;
  33         unsigned long long tmp;
  34         char dummy;
  35         int ret;
  36
  37         if (argc != 2) {
  38                 ti->error = "Invalid argument count";
  39                 return -EINVAL;
  40         }
  41
  42         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  43         if (lc == NULL) {
  44                 ti->error = "Cannot allocate linear context";
  45                 return -ENOMEM;
  46         }
  47
  48         ret = -EINVAL;
  49         if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) {
  50                 ti->error = "Invalid device sector";
  51                 goto bad;
  52         }
  53         lc->start = tmp;
  54
  55         ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
  56         if (ret) {
  57                 ti->error = "Device lookup failed";
  58                 goto bad;
  59         }
  60
  61         ti->num_flush_bios = 1;
  62         ti->num_discard_bios = 1;
  63         ti->num_secure_erase_bios = 1;
  64         ti->num_write_zeroes_bios = 1;
  65         ti->flush_bypasses_map = true;
  66         ti->private = lc;
  67         return 0;
  68
  69 bad:
  70         kfree(lc);
  71         return ret;
  72 }
  73
  74 static void linear_dtr(struct dm_target *ti)
  75 {
  76         struct linear_c *lc = ti->private;
  77
  78         dm_put_device(ti, lc->dev);
  79         kfree(lc);
  80 }
  81
  82 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
  83 {
  84         struct linear_c *lc = ti->private;
  85
  86         return lc->start + dm_target_offset(ti, bi_sector);
  87 }
  88
  89 int linear_map(struct dm_target *ti, struct bio *bio)
  90 {
  91         struct linear_c *lc = ti->private;
  92
  93         bio_set_dev(bio, lc->dev->bdev);
  94         bio->bi_iter.bi_sector = linear_map_sector(ti, bio->bi_iter.bi_sector);
  95
  96         return DM_MAPIO_REMAPPED;
  97 }
  98
  99 static void linear_status(struct dm_target *ti, status_type_t type,
 100                           unsigned int status_flags, char *result, unsigned int maxlen)
 101 {
 102         struct linear_c *lc = ti->private;
 103         size_t sz = 0;
 104
 105         switch (type) {
 106         case STATUSTYPE_INFO:
 107                 result[0] = '\0';
 108                 break;
 109
 110         case STATUSTYPE_TABLE:
 111                 DMEMIT("%s %llu", lc->dev->name, (unsigned long long)lc->start);
 112                 break;
 113
 114         case STATUSTYPE_IMA:
 115                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 116                 DMEMIT(",device_name=%s,start=%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 = 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 || ti->len != bdev_nr_sectors(dev->bdev))
 133                 return 1;
 134         return 0;
 135 }
 136
 137 #ifdef CONFIG_BLK_DEV_ZONED
 138 static int linear_report_zones(struct dm_target *ti,
 139                 struct dm_report_zones_args *args, unsigned int nr_zones)
 140 {
 141         struct linear_c *lc = ti->private;
 142
 143         return dm_report_zones(lc->dev->bdev, lc->start,
 144                                linear_map_sector(ti, args->next_sector),
 145                                args, nr_zones);
 146 }
 147 #else
 148 #define linear_report_zones NULL
 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_FS_DAX)
 160 static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
 161 {
 162         struct linear_c *lc = ti->private;
 163         sector_t sector = linear_map_sector(ti, *pgoff << PAGE_SECTORS_SHIFT);
 164
 165         *pgoff = (get_start_sect(lc->dev->bdev) + sector) >> PAGE_SECTORS_SHIFT;
 166         return lc->dev->dax_dev;
 167 }
 168
 169 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 170                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 171                 pfn_t *pfn)
 172 {
 173         struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 174
 175         return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
 176 }
 177
 178 static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
 179                                       size_t nr_pages)
 180 {
 181         struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 182
 183         return dax_zero_page_range(dax_dev, pgoff, nr_pages);
 184 }
 185
 186 static size_t linear_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
 187                 void *addr, size_t bytes, struct iov_iter *i)
 188 {
 189         struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 190
 191         return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
 192 }
 193
 194 #else
 195 #define linear_dax_direct_access NULL
 196 #define linear_dax_zero_page_range NULL
 197 #define linear_dax_recovery_write NULL
 198 #endif
 199
 200 static struct target_type linear_target = {
 201         .name   = "linear",
 202         .version = {1, 4, 0},
 203         .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT |
 204                     DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
 205         .report_zones = linear_report_zones,
 206         .module = THIS_MODULE,
 207         .ctr    = linear_ctr,
 208         .dtr    = linear_dtr,
 209         .map    = linear_map,
 210         .status = linear_status,
 211         .prepare_ioctl = linear_prepare_ioctl,
 212         .iterate_devices = linear_iterate_devices,
 213         .direct_access = linear_dax_direct_access,
 214         .dax_zero_page_range = linear_dax_zero_page_range,
 215         .dax_recovery_write = linear_dax_recovery_write,
 216 };
 217
 218 int __init dm_linear_init(void)
 219 {
 220         int r = dm_register_target(&linear_target);
 221
 222         if (r < 0)
 223                 DMERR("register failed %d", r);
 224
 225         return r;
 226 }
 227
 228 void dm_linear_exit(void)
 229 {
 230         dm_unregister_target(&linear_target);
 231 }