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 unsigned int cmd, unsigned long arg, 124 bool *forward) 125 { 126 struct linear_c *lc = ti->private; 127 struct dm_dev *dev = lc->dev; 128 129 *bdev = dev->bdev; 130 131 /* 132 * Only pass ioctls through if the device sizes match exactly. 133 */ 134 if (lc->start || ti->len != bdev_nr_sectors(dev->bdev)) 135 return 1; 136 return 0; 137 } 138 139 #ifdef CONFIG_BLK_DEV_ZONED 140 static int linear_report_zones(struct dm_target *ti, 141 struct dm_report_zones_args *args, unsigned int nr_zones) 142 { 143 struct linear_c *lc = ti->private; 144 145 return dm_report_zones(lc->dev->bdev, lc->start, 146 linear_map_sector(ti, args->next_sector), 147 args, nr_zones); 148 } 149 #else 150 #define linear_report_zones NULL 151 #endif 152 153 static int linear_iterate_devices(struct dm_target *ti, 154 iterate_devices_callout_fn fn, void *data) 155 { 156 struct linear_c *lc = ti->private; 157 158 return fn(ti, lc->dev, lc->start, ti->len, data); 159 } 160 161 #if IS_ENABLED(CONFIG_FS_DAX) 162 static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff) 163 { 164 struct linear_c *lc = ti->private; 165 sector_t sector = linear_map_sector(ti, *pgoff << PAGE_SECTORS_SHIFT); 166 167 *pgoff = (get_start_sect(lc->dev->bdev) + sector) >> PAGE_SECTORS_SHIFT; 168 return lc->dev->dax_dev; 169 } 170 171 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, 172 long nr_pages, enum dax_access_mode mode, void **kaddr, 173 unsigned long *pfn) 174 { 175 struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff); 176 177 return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn); 178 } 179 180 static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff, 181 size_t nr_pages) 182 { 183 struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff); 184 185 return dax_zero_page_range(dax_dev, pgoff, nr_pages); 186 } 187 188 static size_t linear_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff, 189 void *addr, size_t bytes, struct iov_iter *i) 190 { 191 struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff); 192 193 return dax_recovery_write(dax_dev, pgoff, addr, bytes, i); 194 } 195 196 #else 197 #define linear_dax_direct_access NULL 198 #define linear_dax_zero_page_range NULL 199 #define linear_dax_recovery_write NULL 200 #endif 201 202 static struct target_type linear_target = { 203 .name = "linear", 204 .version = {1, 5, 0}, 205 .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT | 206 DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO | 207 DM_TARGET_ATOMIC_WRITES, 208 .report_zones = linear_report_zones, 209 .module = THIS_MODULE, 210 .ctr = linear_ctr, 211 .dtr = linear_dtr, 212 .map = linear_map, 213 .status = linear_status, 214 .prepare_ioctl = linear_prepare_ioctl, 215 .iterate_devices = linear_iterate_devices, 216 .direct_access = linear_dax_direct_access, 217 .dax_zero_page_range = linear_dax_zero_page_range, 218 .dax_recovery_write = linear_dax_recovery_write, 219 }; 220 221 int __init dm_linear_init(void) 222 { 223 int r = dm_register_target(&linear_target); 224 225 if (r < 0) 226 DMERR("register failed %d", r); 227 228 return r; 229 } 230 231 void dm_linear_exit(void) 232 { 233 dm_unregister_target(&linear_target); 234 } 235