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