dm-linear.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
  4 *
  5 * This file is released under the GPL.
  6 */
  7
  8#include "dm.h"
  9#include <linux/module.h>
 10#include <linux/init.h>
 11#include <linux/blkdev.h>
 12#include <linux/bio.h>
 13#include <linux/dax.h>
 14#include <linux/slab.h>
 15#include <linux/device-mapper.h>
 16
 17#define DM_MSG_PREFIX "linear"
 18
 19/*
 20 * Linear: maps a linear range of a device.
 21 */
 22struct linear_c {
 23	struct dm_dev *dev;
 24	sector_t start;
 25};
 26
 27/*
 28 * Construct a linear mapping: <dev_path> <offset>
 29 */
 30static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 31{
 32	struct linear_c *lc;
 33	unsigned long long tmp;
 34	char dummy;
 35	int ret;
 36
 37	if (argc != 2) {
 38		ti->error = "Invalid argument count";
 39		return -EINVAL;
 40	}
 41
 42	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
 43	if (lc == NULL) {
 44		ti->error = "Cannot allocate linear context";
 45		return -ENOMEM;
 46	}
 47
 48	ret = -EINVAL;
 49	if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) {
 50		ti->error = "Invalid device sector";
 51		goto bad;
 52	}
 53	lc->start = tmp;
 54
 55	ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
 56	if (ret) {
 57		ti->error = "Device lookup failed";
 58		goto bad;
 59	}
 60
 61	ti->num_flush_bios = 1;
 62	ti->num_discard_bios = 1;
 63	ti->num_secure_erase_bios = 1;
 64	ti->num_write_zeroes_bios = 1;
 65	ti->flush_bypasses_map = true;
 66	ti->private = lc;
 67	return 0;
 68
 69bad:
 70	kfree(lc);
 71	return ret;
 72}
 73
 74static void linear_dtr(struct dm_target *ti)
 75{
 76	struct linear_c *lc = ti->private;
 77
 78	dm_put_device(ti, lc->dev);
 79	kfree(lc);
 80}
 81
 82static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
 83{
 84	struct linear_c *lc = ti->private;
 85
 86	return lc->start + dm_target_offset(ti, bi_sector);
 87}
 88
 89int linear_map(struct dm_target *ti, struct bio *bio)
 90{
 91	struct linear_c *lc = ti->private;
 92
 93	bio_set_dev(bio, lc->dev->bdev);
 94	bio->bi_iter.bi_sector = linear_map_sector(ti, bio->bi_iter.bi_sector);
 95
 96	return DM_MAPIO_REMAPPED;
 97}
 98
 99static void linear_status(struct dm_target *ti, status_type_t type,
100			  unsigned int status_flags, char *result, unsigned int maxlen)
101{
102	struct linear_c *lc = ti->private;
103	size_t sz = 0;
104
105	switch (type) {
106	case STATUSTYPE_INFO:
107		result[0] = '\0';
108		break;
109
110	case STATUSTYPE_TABLE:
111		DMEMIT("%s %llu", lc->dev->name, (unsigned long long)lc->start);
112		break;
113
114	case STATUSTYPE_IMA:
115		DMEMIT_TARGET_NAME_VERSION(ti->type);
116		DMEMIT(",device_name=%s,start=%llu;", lc->dev->name,
117		       (unsigned long long)lc->start);
118		break;
119	}
120}
121
122static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev,
123				unsigned int cmd, unsigned long arg,
124				bool *forward)
125{
126	struct linear_c *lc = ti->private;
127	struct dm_dev *dev = lc->dev;
128
129	*bdev = dev->bdev;
130
131	/*
132	 * Only pass ioctls through if the device sizes match exactly.
133	 */
134	if (lc->start || ti->len != bdev_nr_sectors(dev->bdev))
135		return 1;
136	return 0;
137}
138
139#ifdef CONFIG_BLK_DEV_ZONED
140static int linear_report_zones(struct dm_target *ti,
141		struct dm_report_zones_args *args, unsigned int nr_zones)
142{
143	struct linear_c *lc = ti->private;
144
145	return dm_report_zones(lc->dev->bdev, lc->start,
146			       linear_map_sector(ti, args->next_sector),
147			       args, nr_zones);
148}
149#else
150#define linear_report_zones NULL
151#endif
152
153static int linear_iterate_devices(struct dm_target *ti,
154				  iterate_devices_callout_fn fn, void *data)
155{
156	struct linear_c *lc = ti->private;
157
158	return fn(ti, lc->dev, lc->start, ti->len, data);
159}
160
161#if IS_ENABLED(CONFIG_FS_DAX)
162static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
163{
164	struct linear_c *lc = ti->private;
165	sector_t sector = linear_map_sector(ti, *pgoff << PAGE_SECTORS_SHIFT);
166
167	*pgoff = (get_start_sect(lc->dev->bdev) + sector) >> PAGE_SECTORS_SHIFT;
168	return lc->dev->dax_dev;
169}
170
171static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
172		long nr_pages, enum dax_access_mode mode, void **kaddr,
173		unsigned long *pfn)
174{
175	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
176
177	return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
178}
179
180static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
181				      size_t nr_pages)
182{
183	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
184
185	return dax_zero_page_range(dax_dev, pgoff, nr_pages);
186}
187
188static size_t linear_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
189		void *addr, size_t bytes, struct iov_iter *i)
190{
191	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
192
193	return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
194}
195
196#else
197#define linear_dax_direct_access NULL
198#define linear_dax_zero_page_range NULL
199#define linear_dax_recovery_write NULL
200#endif
201
202static struct target_type linear_target = {
203	.name   = "linear",
204	.version = {1, 5, 0},
205	.features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT |
206		    DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO |
207		    DM_TARGET_ATOMIC_WRITES,
208	.report_zones = linear_report_zones,
209	.module = THIS_MODULE,
210	.ctr    = linear_ctr,
211	.dtr    = linear_dtr,
212	.map    = linear_map,
213	.status = linear_status,
214	.prepare_ioctl = linear_prepare_ioctl,
215	.iterate_devices = linear_iterate_devices,
216	.direct_access = linear_dax_direct_access,
217	.dax_zero_page_range = linear_dax_zero_page_range,
218	.dax_recovery_write = linear_dax_recovery_write,
219};
220
221int __init dm_linear_init(void)
222{
223	int r = dm_register_target(&linear_target);
224
225	if (r < 0)
226		DMERR("register failed %d", r);
227
228	return r;
229}
230
231void dm_linear_exit(void)
232{
233	dm_unregister_target(&linear_target);
234}