1/*
2 * Copyright (C) 2017 Intel Corporation.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8
9#include <linux/module.h>
10
11struct unstripe_c {
12	struct dm_dev *dev;
13	sector_t physical_start;
14
15	uint32_t stripes;
16
17	uint32_t unstripe;
18	sector_t unstripe_width;
19	sector_t unstripe_offset;
20
21	uint32_t chunk_size;
22	u8 chunk_shift;
23};
24
25#define DM_MSG_PREFIX "unstriped"
26
27static void cleanup_unstripe(struct unstripe_c *uc, struct dm_target *ti)
28{
29	if (uc->dev)
30		dm_put_device(ti, uc->dev);
31	kfree(uc);
32}
33
34/*
35 * Contruct an unstriped mapping.
36 * <number of stripes> <chunk size> <stripe #> <dev_path> <offset>
37 */
38static int unstripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
39{
40	struct unstripe_c *uc;
41	sector_t tmp_len;
42	unsigned long long start;
43	char dummy;
44
45	if (argc != 5) {
46		ti->error = "Invalid number of arguments";
47		return -EINVAL;
48	}
49
50	uc = kzalloc(sizeof(*uc), GFP_KERNEL);
51	if (!uc) {
52		ti->error = "Memory allocation for unstriped context failed";
53		return -ENOMEM;
54	}
55
56	if (kstrtouint(argv[0], 10, &uc->stripes) || !uc->stripes) {
57		ti->error = "Invalid stripe count";
58		goto err;
59	}
60
61	if (kstrtouint(argv[1], 10, &uc->chunk_size) || !uc->chunk_size) {
62		ti->error = "Invalid chunk_size";
63		goto err;
64	}
65
66	if (kstrtouint(argv[2], 10, &uc->unstripe)) {
67		ti->error = "Invalid stripe number";
68		goto err;
69	}
70
71	if (uc->unstripe > uc->stripes && uc->stripes > 1) {
72		ti->error = "Please provide stripe between [0, # of stripes]";
73		goto err;
74	}
75
76	if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &uc->dev)) {
77		ti->error = "Couldn't get striped device";
78		goto err;
79	}
80
81	if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1 || start != (sector_t)start) {
82		ti->error = "Invalid striped device offset";
83		goto err;
84	}
85	uc->physical_start = start;
86
87	uc->unstripe_offset = uc->unstripe * uc->chunk_size;
88	uc->unstripe_width = (uc->stripes - 1) * uc->chunk_size;
89	uc->chunk_shift = is_power_of_2(uc->chunk_size) ? fls(uc->chunk_size) - 1 : 0;
90
91	tmp_len = ti->len;
92	if (sector_div(tmp_len, uc->chunk_size)) {
93		ti->error = "Target length not divisible by chunk size";
94		goto err;
95	}
96
97	if (dm_set_target_max_io_len(ti, uc->chunk_size)) {
98		ti->error = "Failed to set max io len";
99		goto err;
100	}
101
102	ti->private = uc;
103	return 0;
104err:
105	cleanup_unstripe(uc, ti);
106	return -EINVAL;
107}
108
109static void unstripe_dtr(struct dm_target *ti)
110{
111	struct unstripe_c *uc = ti->private;
112
113	cleanup_unstripe(uc, ti);
114}
115
116static sector_t map_to_core(struct dm_target *ti, struct bio *bio)
117{
118	struct unstripe_c *uc = ti->private;
119	sector_t sector = bio->bi_iter.bi_sector;
120	sector_t tmp_sector = sector;
121
122	/* Shift us up to the right "row" on the stripe */
123	if (uc->chunk_shift)
124		tmp_sector >>= uc->chunk_shift;
125	else
126		sector_div(tmp_sector, uc->chunk_size);
127
128	sector += uc->unstripe_width * tmp_sector;
129
130	/* Account for what stripe we're operating on */
131	return sector + uc->unstripe_offset;
132}
133
134static int unstripe_map(struct dm_target *ti, struct bio *bio)
135{
136	struct unstripe_c *uc = ti->private;
137
138	bio_set_dev(bio, uc->dev->bdev);
139	bio->bi_iter.bi_sector = map_to_core(ti, bio) + uc->physical_start;
140
141	return DM_MAPIO_REMAPPED;
142}
143
144static void unstripe_status(struct dm_target *ti, status_type_t type,
145			    unsigned int status_flags, char *result, unsigned int maxlen)
146{
147	struct unstripe_c *uc = ti->private;
148	unsigned int sz = 0;
149
150	switch (type) {
151	case STATUSTYPE_INFO:
152		break;
153
154	case STATUSTYPE_TABLE:
155		DMEMIT("%d %llu %d %s %llu",
156		       uc->stripes, (unsigned long long)uc->chunk_size, uc->unstripe,
157		       uc->dev->name, (unsigned long long)uc->physical_start);
158		break;
159	}
160}
161
162static int unstripe_iterate_devices(struct dm_target *ti,
163				    iterate_devices_callout_fn fn, void *data)
164{
165	struct unstripe_c *uc = ti->private;
166
167	return fn(ti, uc->dev, uc->physical_start, ti->len, data);
168}
169
170static void unstripe_io_hints(struct dm_target *ti,
171			       struct queue_limits *limits)
172{
173	struct unstripe_c *uc = ti->private;
174
175	limits->chunk_sectors = uc->chunk_size;
176}
177
178static struct target_type unstripe_target = {
179	.name = "unstriped",
180	.version = {1, 1, 0},
181	.module = THIS_MODULE,
182	.ctr = unstripe_ctr,
183	.dtr = unstripe_dtr,
184	.map = unstripe_map,
185	.status = unstripe_status,
186	.iterate_devices = unstripe_iterate_devices,
187	.io_hints = unstripe_io_hints,
188};
189
190static int __init dm_unstripe_init(void)
191{
192	return dm_register_target(&unstripe_target);
193}
194
195static void __exit dm_unstripe_exit(void)
196{
197	dm_unregister_target(&unstripe_target);
198}
199
200module_init(dm_unstripe_init);
201module_exit(dm_unstripe_exit);
202
203MODULE_DESCRIPTION(DM_NAME " unstriped target");
204MODULE_ALIAS("dm-unstriped");
205MODULE_AUTHOR("Scott Bauer <scott.bauer@intel.com>");
206MODULE_LICENSE("GPL");
207