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 33 if (argc != 2) { 34 ti->error = "Invalid argument count"; 35 return -EINVAL; 36 } 37 38 lc = kmalloc(sizeof(*lc), GFP_KERNEL); 39 if (lc == NULL) { 40 ti->error = "dm-linear: Cannot allocate linear context"; 41 return -ENOMEM; 42 } 43 44 if (sscanf(argv[1], "%llu", &tmp) != 1) { 45 ti->error = "dm-linear: Invalid device sector"; 46 goto bad; 47 } 48 lc->start = tmp; 49 50 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev)) { 51 ti->error = "dm-linear: Device lookup failed"; 52 goto bad; 53 } 54 55 ti->num_flush_requests = 1; 56 ti->private = lc; 57 return 0; 58 59 bad: 60 kfree(lc); 61 return -EINVAL; 62 } 63 64 static void linear_dtr(struct dm_target *ti) 65 { 66 struct linear_c *lc = (struct linear_c *) ti->private; 67 68 dm_put_device(ti, lc->dev); 69 kfree(lc); 70 } 71 72 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) 73 { 74 struct linear_c *lc = ti->private; 75 76 return lc->start + (bi_sector - ti->begin); 77 } 78 79 static void linear_map_bio(struct dm_target *ti, struct bio *bio) 80 { 81 struct linear_c *lc = ti->private; 82 83 bio->bi_bdev = lc->dev->bdev; 84 if (bio_sectors(bio)) 85 bio->bi_sector = linear_map_sector(ti, bio->bi_sector); 86 } 87 88 static int linear_map(struct dm_target *ti, struct bio *bio, 89 union map_info *map_context) 90 { 91 linear_map_bio(ti, bio); 92 93 return DM_MAPIO_REMAPPED; 94 } 95 96 static int linear_status(struct dm_target *ti, status_type_t type, 97 char *result, unsigned int maxlen) 98 { 99 struct linear_c *lc = (struct linear_c *) ti->private; 100 101 switch (type) { 102 case STATUSTYPE_INFO: 103 result[0] = '\0'; 104 break; 105 106 case STATUSTYPE_TABLE: 107 snprintf(result, maxlen, "%s %llu", lc->dev->name, 108 (unsigned long long)lc->start); 109 break; 110 } 111 return 0; 112 } 113 114 static int linear_ioctl(struct dm_target *ti, unsigned int cmd, 115 unsigned long arg) 116 { 117 struct linear_c *lc = (struct linear_c *) ti->private; 118 return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg); 119 } 120 121 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 122 struct bio_vec *biovec, int max_size) 123 { 124 struct linear_c *lc = ti->private; 125 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 126 127 if (!q->merge_bvec_fn) 128 return max_size; 129 130 bvm->bi_bdev = lc->dev->bdev; 131 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector); 132 133 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 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, 1, 0}, 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 .merge = linear_merge, 154 .iterate_devices = linear_iterate_devices, 155 }; 156 157 int __init dm_linear_init(void) 158 { 159 int r = dm_register_target(&linear_target); 160 161 if (r < 0) 162 DMERR("register failed %d", r); 163 164 return r; 165 } 166 167 void dm_linear_exit(void) 168 { 169 dm_unregister_target(&linear_target); 170 } 171