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 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/blkdev.h> 12 #include <linux/bio.h> 13 #include <linux/slab.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], lc->start, ti->len, 51 dm_table_get_mode(ti->table), &lc->dev)) { 52 ti->error = "dm-linear: Device lookup failed"; 53 goto bad; 54 } 55 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 bio->bi_sector = linear_map_sector(ti, bio->bi_sector); 85 } 86 87 static int linear_map(struct dm_target *ti, struct bio *bio, 88 union map_info *map_context) 89 { 90 linear_map_bio(ti, bio); 91 92 return DM_MAPIO_REMAPPED; 93 } 94 95 static int linear_status(struct dm_target *ti, status_type_t type, 96 char *result, unsigned int maxlen) 97 { 98 struct linear_c *lc = (struct linear_c *) ti->private; 99 100 switch (type) { 101 case STATUSTYPE_INFO: 102 result[0] = '\0'; 103 break; 104 105 case STATUSTYPE_TABLE: 106 snprintf(result, maxlen, "%s %llu", lc->dev->name, 107 (unsigned long long)lc->start); 108 break; 109 } 110 return 0; 111 } 112 113 static int linear_ioctl(struct dm_target *ti, struct inode *inode, 114 struct file *filp, unsigned int cmd, 115 unsigned long arg) 116 { 117 struct linear_c *lc = (struct linear_c *) ti->private; 118 struct block_device *bdev = lc->dev->bdev; 119 struct file fake_file = {}; 120 struct dentry fake_dentry = {}; 121 122 fake_file.f_mode = lc->dev->mode; 123 fake_file.f_path.dentry = &fake_dentry; 124 fake_dentry.d_inode = bdev->bd_inode; 125 126 return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg); 127 } 128 129 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 130 struct bio_vec *biovec, int max_size) 131 { 132 struct linear_c *lc = ti->private; 133 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 134 135 if (!q->merge_bvec_fn) 136 return max_size; 137 138 bvm->bi_bdev = lc->dev->bdev; 139 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector); 140 141 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 142 } 143 144 static struct target_type linear_target = { 145 .name = "linear", 146 .version= {1, 0, 3}, 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 }; 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 int r = dm_unregister_target(&linear_target); 169 170 if (r < 0) 171 DMERR("unregister failed %d", r); 172 } 173