/* * Copyright (C) 2001-2003 Sistina Software (UK) Limited. * * This file is released under the GPL. */ #include "dm.h" #include <linux/module.h> #include <linux/init.h> #include <linux/blkdev.h> #include <linux/bio.h> #include <linux/slab.h> #include <linux/device-mapper.h> #define DM_MSG_PREFIX "linear" /* * Linear: maps a linear range of a device. */ struct linear_c { struct dm_dev *dev; sector_t start; }; /* * Construct a linear mapping: <dev_path> <offset> */ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv) { struct linear_c *lc; unsigned long long tmp; char dummy; if (argc != 2) { ti->error = "Invalid argument count"; return -EINVAL; } lc = kmalloc(sizeof(*lc), GFP_KERNEL); if (lc == NULL) { ti->error = "dm-linear: Cannot allocate linear context"; return -ENOMEM; } if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) { ti->error = "dm-linear: Invalid device sector"; goto bad; } lc->start = tmp; if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev)) { ti->error = "dm-linear: Device lookup failed"; goto bad; } ti->num_flush_bios = 1; ti->num_discard_bios = 1; ti->num_write_same_bios = 1; ti->private = lc; return 0; bad: kfree(lc); return -EINVAL; } static void linear_dtr(struct dm_target *ti) { struct linear_c *lc = (struct linear_c *) ti->private; dm_put_device(ti, lc->dev); kfree(lc); } static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector) { struct linear_c *lc = ti->private; return lc->start + dm_target_offset(ti, bi_sector); } static void linear_map_bio(struct dm_target *ti, struct bio *bio) { struct linear_c *lc = ti->private; bio->bi_bdev = lc->dev->bdev; if (bio_sectors(bio)) bio->bi_iter.bi_sector = linear_map_sector(ti, bio->bi_iter.bi_sector); } static int linear_map(struct dm_target *ti, struct bio *bio) { linear_map_bio(ti, bio); return DM_MAPIO_REMAPPED; } static void linear_status(struct dm_target *ti, status_type_t type, unsigned status_flags, char *result, unsigned maxlen) { struct linear_c *lc = (struct linear_c *) ti->private; switch (type) { case STATUSTYPE_INFO: result[0] = '\0'; break; case STATUSTYPE_TABLE: snprintf(result, maxlen, "%s %llu", lc->dev->name, (unsigned long long)lc->start); break; } } static int linear_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg) { struct linear_c *lc = (struct linear_c *) ti->private; struct dm_dev *dev = lc->dev; int r = 0; /* * Only pass ioctls through if the device sizes match exactly. */ if (lc->start || ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) r = scsi_verify_blk_ioctl(NULL, cmd); return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg); } static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm, struct bio_vec *biovec, int max_size) { struct linear_c *lc = ti->private; struct request_queue *q = bdev_get_queue(lc->dev->bdev); if (!q->merge_bvec_fn) return max_size; bvm->bi_bdev = lc->dev->bdev; bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector); return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); } static int linear_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data) { struct linear_c *lc = ti->private; return fn(ti, lc->dev, lc->start, ti->len, data); } static struct target_type linear_target = { .name = "linear", .version = {1, 2, 1}, .module = THIS_MODULE, .ctr = linear_ctr, .dtr = linear_dtr, .map = linear_map, .status = linear_status, .ioctl = linear_ioctl, .merge = linear_merge, .iterate_devices = linear_iterate_devices, }; int __init dm_linear_init(void) { int r = dm_register_target(&linear_target); if (r < 0) DMERR("register failed %d", r); return r; } void dm_linear_exit(void) { dm_unregister_target(&linear_target); }