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 = "dm-linear: 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 = "dm-linear: 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 = "dm-linear: 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->private = lc; 63 return 0; 64 65 bad: 66 kfree(lc); 67 return ret; 68 } 69 70 static void linear_dtr(struct dm_target *ti) 71 { 72 struct linear_c *lc = (struct linear_c *) ti->private; 73 74 dm_put_device(ti, lc->dev); 75 kfree(lc); 76 } 77 78 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) 79 { 80 struct linear_c *lc = ti->private; 81 82 return lc->start + dm_target_offset(ti, bi_sector); 83 } 84 85 static void linear_map_bio(struct dm_target *ti, struct bio *bio) 86 { 87 struct linear_c *lc = ti->private; 88 89 bio->bi_bdev = lc->dev->bdev; 90 if (bio_sectors(bio)) 91 bio->bi_iter.bi_sector = 92 linear_map_sector(ti, bio->bi_iter.bi_sector); 93 } 94 95 static int linear_map(struct dm_target *ti, struct bio *bio) 96 { 97 linear_map_bio(ti, bio); 98 99 return DM_MAPIO_REMAPPED; 100 } 101 102 static void linear_status(struct dm_target *ti, status_type_t type, 103 unsigned status_flags, char *result, unsigned maxlen) 104 { 105 struct linear_c *lc = (struct linear_c *) ti->private; 106 107 switch (type) { 108 case STATUSTYPE_INFO: 109 result[0] = '\0'; 110 break; 111 112 case STATUSTYPE_TABLE: 113 snprintf(result, maxlen, "%s %llu", lc->dev->name, 114 (unsigned long long)lc->start); 115 break; 116 } 117 } 118 119 static int linear_ioctl(struct dm_target *ti, unsigned int cmd, 120 unsigned long arg) 121 { 122 struct linear_c *lc = (struct linear_c *) ti->private; 123 struct dm_dev *dev = lc->dev; 124 int r = 0; 125 126 /* 127 * Only pass ioctls through if the device sizes match exactly. 128 */ 129 if (lc->start || 130 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 131 r = scsi_verify_blk_ioctl(NULL, cmd); 132 133 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg); 134 } 135 136 static int linear_iterate_devices(struct dm_target *ti, 137 iterate_devices_callout_fn fn, void *data) 138 { 139 struct linear_c *lc = ti->private; 140 141 return fn(ti, lc->dev, lc->start, ti->len, data); 142 } 143 144 static struct target_type linear_target = { 145 .name = "linear", 146 .version = {1, 2, 1}, 147 .module = THIS_MODULE, 148 .ctr = linear_ctr, 149 .dtr = linear_dtr, 150 .map = linear_map, 151 .status = linear_status, 152 .ioctl = linear_ioctl, 153 .iterate_devices = linear_iterate_devices, 154 }; 155 156 int __init dm_linear_init(void) 157 { 158 int r = dm_register_target(&linear_target); 159 160 if (r < 0) 161 DMERR("register failed %d", r); 162 163 return r; 164 } 165 166 void dm_linear_exit(void) 167 { 168 dm_unregister_target(&linear_target); 169 } 170