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_write_same_bios = 1; 63 ti->num_write_zeroes_bios = 1; 64 ti->private = lc; 65 return 0; 66 67 bad: 68 kfree(lc); 69 return ret; 70 } 71 72 static void linear_dtr(struct dm_target *ti) 73 { 74 struct linear_c *lc = (struct linear_c *) ti->private; 75 76 dm_put_device(ti, lc->dev); 77 kfree(lc); 78 } 79 80 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) 81 { 82 struct linear_c *lc = ti->private; 83 84 return lc->start + dm_target_offset(ti, bi_sector); 85 } 86 87 static void linear_map_bio(struct dm_target *ti, struct bio *bio) 88 { 89 struct linear_c *lc = ti->private; 90 91 bio->bi_bdev = lc->dev->bdev; 92 if (bio_sectors(bio)) 93 bio->bi_iter.bi_sector = 94 linear_map_sector(ti, bio->bi_iter.bi_sector); 95 } 96 97 static int linear_map(struct dm_target *ti, struct bio *bio) 98 { 99 linear_map_bio(ti, bio); 100 101 return DM_MAPIO_REMAPPED; 102 } 103 104 static void linear_status(struct dm_target *ti, status_type_t type, 105 unsigned status_flags, char *result, unsigned maxlen) 106 { 107 struct linear_c *lc = (struct linear_c *) ti->private; 108 109 switch (type) { 110 case STATUSTYPE_INFO: 111 result[0] = '\0'; 112 break; 113 114 case STATUSTYPE_TABLE: 115 snprintf(result, maxlen, "%s %llu", lc->dev->name, 116 (unsigned long long)lc->start); 117 break; 118 } 119 } 120 121 static int linear_prepare_ioctl(struct dm_target *ti, 122 struct block_device **bdev, fmode_t *mode) 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 static int linear_iterate_devices(struct dm_target *ti, 139 iterate_devices_callout_fn fn, void *data) 140 { 141 struct linear_c *lc = ti->private; 142 143 return fn(ti, lc->dev, lc->start, ti->len, data); 144 } 145 146 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, 147 long nr_pages, void **kaddr, pfn_t *pfn) 148 { 149 long ret; 150 struct linear_c *lc = ti->private; 151 struct block_device *bdev = lc->dev->bdev; 152 struct dax_device *dax_dev = lc->dev->dax_dev; 153 sector_t dev_sector, sector = pgoff * PAGE_SECTORS; 154 155 dev_sector = linear_map_sector(ti, sector); 156 ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff); 157 if (ret) 158 return ret; 159 return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn); 160 } 161 162 static struct target_type linear_target = { 163 .name = "linear", 164 .version = {1, 3, 0}, 165 .features = DM_TARGET_PASSES_INTEGRITY, 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_dax_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