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->num_discard_requests = 1; 57 ti->private = lc; 58 return 0; 59 60 bad: 61 kfree(lc); 62 return -EINVAL; 63 } 64 65 static void linear_dtr(struct dm_target *ti) 66 { 67 struct linear_c *lc = (struct linear_c *) ti->private; 68 69 dm_put_device(ti, lc->dev); 70 kfree(lc); 71 } 72 73 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) 74 { 75 struct linear_c *lc = ti->private; 76 77 return lc->start + dm_target_offset(ti, bi_sector); 78 } 79 80 static void linear_map_bio(struct dm_target *ti, struct bio *bio) 81 { 82 struct linear_c *lc = ti->private; 83 84 bio->bi_bdev = lc->dev->bdev; 85 if (bio_sectors(bio)) 86 bio->bi_sector = linear_map_sector(ti, bio->bi_sector); 87 } 88 89 static int linear_map(struct dm_target *ti, struct bio *bio, 90 union map_info *map_context) 91 { 92 linear_map_bio(ti, bio); 93 94 return DM_MAPIO_REMAPPED; 95 } 96 97 static int linear_status(struct dm_target *ti, status_type_t type, 98 char *result, unsigned int maxlen) 99 { 100 struct linear_c *lc = (struct linear_c *) ti->private; 101 102 switch (type) { 103 case STATUSTYPE_INFO: 104 result[0] = '\0'; 105 break; 106 107 case STATUSTYPE_TABLE: 108 snprintf(result, maxlen, "%s %llu", lc->dev->name, 109 (unsigned long long)lc->start); 110 break; 111 } 112 return 0; 113 } 114 115 static int linear_ioctl(struct dm_target *ti, unsigned int cmd, 116 unsigned long arg) 117 { 118 struct linear_c *lc = (struct linear_c *) ti->private; 119 struct dm_dev *dev = lc->dev; 120 int r = 0; 121 122 /* 123 * Only pass ioctls through if the device sizes match exactly. 124 */ 125 if (lc->start || 126 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 127 r = scsi_verify_blk_ioctl(NULL, cmd); 128 129 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg); 130 } 131 132 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 133 struct bio_vec *biovec, int max_size) 134 { 135 struct linear_c *lc = ti->private; 136 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 137 138 if (!q->merge_bvec_fn) 139 return max_size; 140 141 bvm->bi_bdev = lc->dev->bdev; 142 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector); 143 144 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 145 } 146 147 static int linear_iterate_devices(struct dm_target *ti, 148 iterate_devices_callout_fn fn, void *data) 149 { 150 struct linear_c *lc = ti->private; 151 152 return fn(ti, lc->dev, lc->start, ti->len, data); 153 } 154 155 static struct target_type linear_target = { 156 .name = "linear", 157 .version = {1, 1, 0}, 158 .module = THIS_MODULE, 159 .ctr = linear_ctr, 160 .dtr = linear_dtr, 161 .map = linear_map, 162 .status = linear_status, 163 .ioctl = linear_ioctl, 164 .merge = linear_merge, 165 .iterate_devices = linear_iterate_devices, 166 }; 167 168 int __init dm_linear_init(void) 169 { 170 int r = dm_register_target(&linear_target); 171 172 if (r < 0) 173 DMERR("register failed %d", r); 174 175 return r; 176 } 177 178 void dm_linear_exit(void) 179 { 180 dm_unregister_target(&linear_target); 181 } 182