diff options
Diffstat (limited to 'drivers/md/dm-linear.c')
| -rw-r--r-- | drivers/md/dm-linear.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c new file mode 100644 index 00000000..3639eeab --- /dev/null +++ b/drivers/md/dm-linear.c @@ -0,0 +1,182 @@ +/* + * 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_requests = 1; + ti->num_discard_requests = 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_sector = linear_map_sector(ti, bio->bi_sector); +} + +static int linear_map(struct dm_target *ti, struct bio *bio, + union map_info *map_context) +{ + linear_map_bio(ti, bio); + + return DM_MAPIO_REMAPPED; +} + +static int linear_status(struct dm_target *ti, status_type_t type, + char *result, unsigned int 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; + } + return 0; +} + +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, 1, 0}, + .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); +} |