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