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/slab.h> 13 #include <linux/device-mapper.h> 14 15 #define DM_MSG_PREFIX "linear" 16 17 /* 18 * Linear: maps a linear range of a device. 19 */ 20 struct linear_c { 21 struct dm_dev *dev; 22 sector_t start; 23 }; 24 25 /* 26 * Construct a linear mapping: <dev_path> <offset> 27 */ 28 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv) 29 { 30 struct linear_c *lc; 31 unsigned long long tmp; 32 char dummy; 33 int ret; 34 35 if (argc != 2) { 36 ti->error = "Invalid argument count"; 37 return -EINVAL; 38 } 39 40 lc = kmalloc(sizeof(*lc), GFP_KERNEL); 41 if (lc == NULL) { 42 ti->error = "Cannot allocate linear context"; 43 return -ENOMEM; 44 } 45 46 ret = -EINVAL; 47 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) { 48 ti->error = "Invalid device sector"; 49 goto bad; 50 } 51 lc->start = tmp; 52 53 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev); 54 if (ret) { 55 ti->error = "Device lookup failed"; 56 goto bad; 57 } 58 59 ti->num_flush_bios = 1; 60 ti->num_discard_bios = 1; 61 ti->num_write_same_bios = 1; 62 ti->num_write_zeroes_bios = 1; 63 ti->private = lc; 64 return 0; 65 66 bad: 67 kfree(lc); 68 return ret; 69 } 70 71 static void linear_dtr(struct dm_target *ti) 72 { 73 struct linear_c *lc = (struct linear_c *) ti->private; 74 75 dm_put_device(ti, lc->dev); 76 kfree(lc); 77 } 78 79 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) 80 { 81 struct linear_c *lc = ti->private; 82 83 return lc->start + dm_target_offset(ti, bi_sector); 84 } 85 86 static void linear_map_bio(struct dm_target *ti, struct bio *bio) 87 { 88 struct linear_c *lc = ti->private; 89 90 bio->bi_bdev = lc->dev->bdev; 91 if (bio_sectors(bio)) 92 bio->bi_iter.bi_sector = 93 linear_map_sector(ti, bio->bi_iter.bi_sector); 94 } 95 96 static int linear_map(struct dm_target *ti, struct bio *bio) 97 { 98 linear_map_bio(ti, bio); 99 100 return DM_MAPIO_REMAPPED; 101 } 102 103 static void linear_status(struct dm_target *ti, status_type_t type, 104 unsigned status_flags, char *result, unsigned maxlen) 105 { 106 struct linear_c *lc = (struct linear_c *) ti->private; 107 108 switch (type) { 109 case STATUSTYPE_INFO: 110 result[0] = '\0'; 111 break; 112 113 case STATUSTYPE_TABLE: 114 snprintf(result, maxlen, "%s %llu", lc->dev->name, 115 (unsigned long long)lc->start); 116 break; 117 } 118 } 119 120 static int linear_prepare_ioctl(struct dm_target *ti, 121 struct block_device **bdev, fmode_t *mode) 122 { 123 struct linear_c *lc = (struct linear_c *) ti->private; 124 struct dm_dev *dev = lc->dev; 125 126 *bdev = dev->bdev; 127 128 /* 129 * Only pass ioctls through if the device sizes match exactly. 130 */ 131 if (lc->start || 132 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 133 return 1; 134 return 0; 135 } 136 137 static int linear_iterate_devices(struct dm_target *ti, 138 iterate_devices_callout_fn fn, void *data) 139 { 140 struct linear_c *lc = ti->private; 141 142 return fn(ti, lc->dev, lc->start, ti->len, data); 143 } 144 145 static long linear_direct_access(struct dm_target *ti, sector_t sector, 146 void **kaddr, pfn_t *pfn, long size) 147 { 148 struct linear_c *lc = ti->private; 149 struct block_device *bdev = lc->dev->bdev; 150 struct blk_dax_ctl dax = { 151 .sector = linear_map_sector(ti, sector), 152 .size = size, 153 }; 154 long ret; 155 156 ret = bdev_direct_access(bdev, &dax); 157 *kaddr = dax.addr; 158 *pfn = dax.pfn; 159 160 return ret; 161 } 162 163 static struct target_type linear_target = { 164 .name = "linear", 165 .version = {1, 3, 0}, 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_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 } 190