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 34 if (argc != 2) { 35 ti->error = "Invalid argument count"; 36 return -EINVAL; 37 } 38 39 lc = kmalloc(sizeof(*lc), GFP_KERNEL); 40 if (lc == NULL) { 41 ti->error = "dm-linear: Cannot allocate linear context"; 42 return -ENOMEM; 43 } 44 45 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) { 46 ti->error = "dm-linear: Invalid device sector"; 47 goto bad; 48 } 49 lc->start = tmp; 50 51 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev)) { 52 ti->error = "dm-linear: Device lookup failed"; 53 goto bad; 54 } 55 56 ti->num_flush_bios = 1; 57 ti->num_discard_bios = 1; 58 ti->num_write_same_bios = 1; 59 ti->private = lc; 60 return 0; 61 62 bad: 63 kfree(lc); 64 return -EINVAL; 65 } 66 67 static void linear_dtr(struct dm_target *ti) 68 { 69 struct linear_c *lc = (struct linear_c *) ti->private; 70 71 dm_put_device(ti, lc->dev); 72 kfree(lc); 73 } 74 75 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) 76 { 77 struct linear_c *lc = ti->private; 78 79 return lc->start + dm_target_offset(ti, bi_sector); 80 } 81 82 static void linear_map_bio(struct dm_target *ti, struct bio *bio) 83 { 84 struct linear_c *lc = ti->private; 85 86 bio->bi_bdev = lc->dev->bdev; 87 if (bio_sectors(bio)) 88 bio->bi_iter.bi_sector = 89 linear_map_sector(ti, bio->bi_iter.bi_sector); 90 } 91 92 static int linear_map(struct dm_target *ti, struct bio *bio) 93 { 94 linear_map_bio(ti, bio); 95 96 return DM_MAPIO_REMAPPED; 97 } 98 99 static void linear_status(struct dm_target *ti, status_type_t type, 100 unsigned status_flags, char *result, unsigned maxlen) 101 { 102 struct linear_c *lc = (struct linear_c *) ti->private; 103 104 switch (type) { 105 case STATUSTYPE_INFO: 106 result[0] = '\0'; 107 break; 108 109 case STATUSTYPE_TABLE: 110 snprintf(result, maxlen, "%s %llu", lc->dev->name, 111 (unsigned long long)lc->start); 112 break; 113 } 114 } 115 116 static int linear_ioctl(struct dm_target *ti, unsigned int cmd, 117 unsigned long arg) 118 { 119 struct linear_c *lc = (struct linear_c *) ti->private; 120 struct dm_dev *dev = lc->dev; 121 int r = 0; 122 123 /* 124 * Only pass ioctls through if the device sizes match exactly. 125 */ 126 if (lc->start || 127 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 128 r = scsi_verify_blk_ioctl(NULL, cmd); 129 130 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg); 131 } 132 133 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 134 struct bio_vec *biovec, int max_size) 135 { 136 struct linear_c *lc = ti->private; 137 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 138 139 if (!q->merge_bvec_fn) 140 return max_size; 141 142 bvm->bi_bdev = lc->dev->bdev; 143 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector); 144 145 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 146 } 147 148 static int linear_iterate_devices(struct dm_target *ti, 149 iterate_devices_callout_fn fn, void *data) 150 { 151 struct linear_c *lc = ti->private; 152 153 return fn(ti, lc->dev, lc->start, ti->len, data); 154 } 155 156 static struct target_type linear_target = { 157 .name = "linear", 158 .version = {1, 2, 1}, 159 .module = THIS_MODULE, 160 .ctr = linear_ctr, 161 .dtr = linear_dtr, 162 .map = linear_map, 163 .status = linear_status, 164 .ioctl = linear_ioctl, 165 .merge = linear_merge, 166 .iterate_devices = linear_iterate_devices, 167 }; 168 169 int __init dm_linear_init(void) 170 { 171 int r = dm_register_target(&linear_target); 172 173 if (r < 0) 174 DMERR("register failed %d", r); 175 176 return r; 177 } 178 179 void dm_linear_exit(void) 180 { 181 dm_unregister_target(&linear_target); 182 } 183