1/*
2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/blkdev.h>
12#include <linux/bio.h>
13#include <linux/slab.h>
14
15#define DM_MSG_PREFIX "striped"
16
17struct stripe {
18	struct dm_dev *dev;
19	sector_t physical_start;
20};
21
22struct stripe_c {
23	uint32_t stripes;
24
25	/* The size of this target / num. stripes */
26	sector_t stripe_width;
27
28	/* stripe chunk size */
29	uint32_t chunk_shift;
30	sector_t chunk_mask;
31
32	struct stripe stripe[0];
33};
34
35static inline struct stripe_c *alloc_context(unsigned int stripes)
36{
37	size_t len;
38
39	if (array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
40			  stripes))
41		return NULL;
42
43	len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
44
45	return kmalloc(len, GFP_KERNEL);
46}
47
48/*
49 * Parse a single <dev> <sector> pair
50 */
51static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
52		      unsigned int stripe, char **argv)
53{
54	unsigned long long start;
55
56	if (sscanf(argv[1], "%llu", &start) != 1)
57		return -EINVAL;
58
59	if (dm_get_device(ti, argv[0], start, sc->stripe_width,
60			  dm_table_get_mode(ti->table),
61			  &sc->stripe[stripe].dev))
62		return -ENXIO;
63
64	sc->stripe[stripe].physical_start = start;
65	return 0;
66}
67
68/*
69 * Construct a striped mapping.
70 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
71 */
72static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
73{
74	struct stripe_c *sc;
75	sector_t width;
76	uint32_t stripes;
77	uint32_t chunk_size;
78	char *end;
79	int r;
80	unsigned int i;
81
82	if (argc < 2) {
83		ti->error = "Not enough arguments";
84		return -EINVAL;
85	}
86
87	stripes = simple_strtoul(argv[0], &end, 10);
88	if (*end) {
89		ti->error = "Invalid stripe count";
90		return -EINVAL;
91	}
92
93	chunk_size = simple_strtoul(argv[1], &end, 10);
94	if (*end) {
95		ti->error = "Invalid chunk_size";
96		return -EINVAL;
97	}
98
99	/*
100	 * chunk_size is a power of two
101	 */
102	if (!chunk_size || (chunk_size & (chunk_size - 1)) ||
103	    (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
104		ti->error = "Invalid chunk size";
105		return -EINVAL;
106	}
107
108	if (ti->len & (chunk_size - 1)) {
109		ti->error = "Target length not divisible by "
110		    "chunk size";
111		return -EINVAL;
112	}
113
114	width = ti->len;
115	if (sector_div(width, stripes)) {
116		ti->error = "Target length not divisible by "
117		    "number of stripes";
118		return -EINVAL;
119	}
120
121	/*
122	 * Do we have enough arguments for that many stripes ?
123	 */
124	if (argc != (2 + 2 * stripes)) {
125		ti->error = "Not enough destinations "
126			"specified";
127		return -EINVAL;
128	}
129
130	sc = alloc_context(stripes);
131	if (!sc) {
132		ti->error = "Memory allocation for striped context "
133		    "failed";
134		return -ENOMEM;
135	}
136
137	sc->stripes = stripes;
138	sc->stripe_width = width;
139	ti->split_io = chunk_size;
140
141	sc->chunk_mask = ((sector_t) chunk_size) - 1;
142	for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
143		chunk_size >>= 1;
144	sc->chunk_shift--;
145
146	/*
147	 * Get the stripe destinations.
148	 */
149	for (i = 0; i < stripes; i++) {
150		argv += 2;
151
152		r = get_stripe(ti, sc, i, argv);
153		if (r < 0) {
154			ti->error = "Couldn't parse stripe destination";
155			while (i--)
156				dm_put_device(ti, sc->stripe[i].dev);
157			kfree(sc);
158			return r;
159		}
160	}
161
162	ti->private = sc;
163	return 0;
164}
165
166static void stripe_dtr(struct dm_target *ti)
167{
168	unsigned int i;
169	struct stripe_c *sc = (struct stripe_c *) ti->private;
170
171	for (i = 0; i < sc->stripes; i++)
172		dm_put_device(ti, sc->stripe[i].dev);
173
174	kfree(sc);
175}
176
177static int stripe_map(struct dm_target *ti, struct bio *bio,
178		      union map_info *map_context)
179{
180	struct stripe_c *sc = (struct stripe_c *) ti->private;
181
182	sector_t offset = bio->bi_sector - ti->begin;
183	sector_t chunk = offset >> sc->chunk_shift;
184	uint32_t stripe = sector_div(chunk, sc->stripes);
185
186	bio->bi_bdev = sc->stripe[stripe].dev->bdev;
187	bio->bi_sector = sc->stripe[stripe].physical_start +
188	    (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
189	return DM_MAPIO_REMAPPED;
190}
191
192static int stripe_status(struct dm_target *ti,
193			 status_type_t type, char *result, unsigned int maxlen)
194{
195	struct stripe_c *sc = (struct stripe_c *) ti->private;
196	unsigned int sz = 0;
197	unsigned int i;
198
199	switch (type) {
200	case STATUSTYPE_INFO:
201		result[0] = '\0';
202		break;
203
204	case STATUSTYPE_TABLE:
205		DMEMIT("%d %llu", sc->stripes,
206			(unsigned long long)sc->chunk_mask + 1);
207		for (i = 0; i < sc->stripes; i++)
208			DMEMIT(" %s %llu", sc->stripe[i].dev->name,
209			    (unsigned long long)sc->stripe[i].physical_start);
210		break;
211	}
212	return 0;
213}
214
215static struct target_type stripe_target = {
216	.name   = "striped",
217	.version= {1, 0, 2},
218	.module = THIS_MODULE,
219	.ctr    = stripe_ctr,
220	.dtr    = stripe_dtr,
221	.map    = stripe_map,
222	.status = stripe_status,
223};
224
225int __init dm_stripe_init(void)
226{
227	int r;
228
229	r = dm_register_target(&stripe_target);
230	if (r < 0)
231		DMWARN("target registration failed");
232
233	return r;
234}
235
236void dm_stripe_exit(void)
237{
238	if (dm_unregister_target(&stripe_target))
239		DMWARN("target unregistration failed");
240
241	return;
242}
243