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 #include <linux/log2.h>
15
16 #define DM_MSG_PREFIX "striped"
17 #define DM_IO_ERROR_THRESHOLD 15
18
19 struct stripe {
20 struct dm_dev *dev;
21 sector_t physical_start;
22
23 atomic_t error_count;
24 };
25
26 struct stripe_c {
27 uint32_t stripes;
28
29 /* The size of this target / num. stripes */
30 sector_t stripe_width;
31
32 /* stripe chunk size */
33 uint32_t chunk_shift;
34 sector_t chunk_mask;
35
36 /* Needed for handling events */
37 struct dm_target *ti;
38
39 /* Work struct used for triggering events*/
40 struct work_struct kstriped_ws;
41
42 struct stripe stripe[0];
43 };
44
45 static struct workqueue_struct *kstriped;
46
47 /*
48 * An event is triggered whenever a drive
49 * drops out of a stripe volume.
50 */
51 static void trigger_event(struct work_struct *work)
52 {
53 struct stripe_c *sc = container_of(work, struct stripe_c, kstriped_ws);
54
55 dm_table_event(sc->ti->table);
56
57 }
58
59 static inline struct stripe_c *alloc_context(unsigned int stripes)
60 {
61 size_t len;
62
63 if (array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
64 stripes))
65 return NULL;
66
67 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
68
69 return kmalloc(len, GFP_KERNEL);
70 }
71
72 /*
73 * Parse a single <dev> <sector> pair
74 */
75 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
76 unsigned int stripe, char **argv)
77 {
78 unsigned long long start;
79
80 if (sscanf(argv[1], "%llu", &start) != 1)
81 return -EINVAL;
82
83 if (dm_get_device(ti, argv[0], start, sc->stripe_width,
84 dm_table_get_mode(ti->table),
85 &sc->stripe[stripe].dev))
86 return -ENXIO;
87
88 sc->stripe[stripe].physical_start = start;
89
90 return 0;
91 }
92
93 /*
94 * Construct a striped mapping.
95 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
96 */
97 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
98 {
99 struct stripe_c *sc;
100 sector_t width;
101 uint32_t stripes;
102 uint32_t chunk_size;
103 char *end;
104 int r;
105 unsigned int i;
106
107 if (argc < 2) {
108 ti->error = "Not enough arguments";
109 return -EINVAL;
110 }
111
112 stripes = simple_strtoul(argv[0], &end, 10);
113 if (*end) {
114 ti->error = "Invalid stripe count";
115 return -EINVAL;
116 }
117
118 chunk_size = simple_strtoul(argv[1], &end, 10);
119 if (*end) {
120 ti->error = "Invalid chunk_size";
121 return -EINVAL;
122 }
123
124 /*
125 * chunk_size is a power of two
126 */
127 if (!is_power_of_2(chunk_size) ||
128 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
129 ti->error = "Invalid chunk size";
130 return -EINVAL;
131 }
132
133 if (ti->len & (chunk_size - 1)) {
134 ti->error = "Target length not divisible by "
135 "chunk size";
136 return -EINVAL;
137 }
138
139 width = ti->len;
140 if (sector_div(width, stripes)) {
141 ti->error = "Target length not divisible by "
142 "number of stripes";
143 return -EINVAL;
144 }
145
146 /*
147 * Do we have enough arguments for that many stripes ?
148 */
149 if (argc != (2 + 2 * stripes)) {
150 ti->error = "Not enough destinations "
151 "specified";
152 return -EINVAL;
153 }
154
155 sc = alloc_context(stripes);
156 if (!sc) {
157 ti->error = "Memory allocation for striped context "
158 "failed";
159 return -ENOMEM;
160 }
161
162 INIT_WORK(&sc->kstriped_ws, trigger_event);
163
164 /* Set pointer to dm target; used in trigger_event */
165 sc->ti = ti;
166
167 sc->stripes = stripes;
168 sc->stripe_width = width;
169 ti->split_io = chunk_size;
170
171 sc->chunk_mask = ((sector_t) chunk_size) - 1;
172 for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
173 chunk_size >>= 1;
174 sc->chunk_shift--;
175
176 /*
177 * Get the stripe destinations.
178 */
179 for (i = 0; i < stripes; i++) {
180 argv += 2;
181
182 r = get_stripe(ti, sc, i, argv);
183 if (r < 0) {
184 ti->error = "Couldn't parse stripe destination";
185 while (i--)
186 dm_put_device(ti, sc->stripe[i].dev);
187 kfree(sc);
188 return r;
189 }
190 atomic_set(&(sc->stripe[i].error_count), 0);
191 }
192
193 ti->private = sc;
194
195 return 0;
196 }
197
198 static void stripe_dtr(struct dm_target *ti)
199 {
200 unsigned int i;
201 struct stripe_c *sc = (struct stripe_c *) ti->private;
202
203 for (i = 0; i < sc->stripes; i++)
204 dm_put_device(ti, sc->stripe[i].dev);
205
206 flush_workqueue(kstriped);
207 kfree(sc);
208 }
209
210 static int stripe_map(struct dm_target *ti, struct bio *bio,
211 union map_info *map_context)
212 {
213 struct stripe_c *sc = (struct stripe_c *) ti->private;
214
215 sector_t offset = bio->bi_sector - ti->begin;
216 sector_t chunk = offset >> sc->chunk_shift;
217 uint32_t stripe = sector_div(chunk, sc->stripes);
218
219 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
220 bio->bi_sector = sc->stripe[stripe].physical_start +
221 (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
222 return DM_MAPIO_REMAPPED;
223 }
224
225 /*
226 * Stripe status:
227 *
228 * INFO
229 * #stripes [stripe_name <stripe_name>] [group word count]
230 * [error count 'A|D' <error count 'A|D'>]
231 *
232 * TABLE
233 * #stripes [stripe chunk size]
234 * [stripe_name physical_start <stripe_name physical_start>]
235 *
236 */
237
238 static int stripe_status(struct dm_target *ti,
239 status_type_t type, char *result, unsigned int maxlen)
240 {
241 struct stripe_c *sc = (struct stripe_c *) ti->private;
242 char buffer[sc->stripes + 1];
243 unsigned int sz = 0;
244 unsigned int i;
245
246 switch (type) {
247 case STATUSTYPE_INFO:
248 DMEMIT("%d ", sc->stripes);
249 for (i = 0; i < sc->stripes; i++) {
250 DMEMIT("%s ", sc->stripe[i].dev->name);
251 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
252 'D' : 'A';
253 }
254 buffer[i] = '\0';
255 DMEMIT("1 %s", buffer);
256 break;
257
258 case STATUSTYPE_TABLE:
259 DMEMIT("%d %llu", sc->stripes,
260 (unsigned long long)sc->chunk_mask + 1);
261 for (i = 0; i < sc->stripes; i++)
262 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
263 (unsigned long long)sc->stripe[i].physical_start);
264 break;
265 }
266 return 0;
267 }
268
269 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
270 int error, union map_info *map_context)
271 {
272 unsigned i;
273 char major_minor[16];
274 struct stripe_c *sc = ti->private;
275
276 if (!error)
277 return 0; /* I/O complete */
278
279 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
280 return error;
281
282 if (error == -EOPNOTSUPP)
283 return error;
284
285 memset(major_minor, 0, sizeof(major_minor));
286 sprintf(major_minor, "%d:%d",
287 bio->bi_bdev->bd_disk->major,
288 bio->bi_bdev->bd_disk->first_minor);
289
290 /*
291 * Test to see which stripe drive triggered the event
292 * and increment error count for all stripes on that device.
293 * If the error count for a given device exceeds the threshold
294 * value we will no longer trigger any further events.
295 */
296 for (i = 0; i < sc->stripes; i++)
297 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
298 atomic_inc(&(sc->stripe[i].error_count));
299 if (atomic_read(&(sc->stripe[i].error_count)) <
300 DM_IO_ERROR_THRESHOLD)
301 queue_work(kstriped, &sc->kstriped_ws);
302 }
303
304 return error;
305 }
306
307 static struct target_type stripe_target = {
308 .name = "striped",
309 .version = {1, 1, 0},
310 .module = THIS_MODULE,
311 .ctr = stripe_ctr,
312 .dtr = stripe_dtr,
313 .map = stripe_map,
314 .end_io = stripe_end_io,
315 .status = stripe_status,
316 };
317
318 int __init dm_stripe_init(void)
319 {
320 int r;
321
322 r = dm_register_target(&stripe_target);
323 if (r < 0)
324 DMWARN("target registration failed");
325
326 kstriped = create_singlethread_workqueue("kstriped");
327 if (!kstriped) {
328 DMERR("failed to create workqueue kstriped");
329 dm_unregister_target(&stripe_target);
330 return -ENOMEM;
331 }
332
333 return r;
334 }
335
336 void dm_stripe_exit(void)
337 {
338 if (dm_unregister_target(&stripe_target))
339 DMWARN("target unregistration failed");
340
341 destroy_workqueue(kstriped);
342
343 return;
344 }
345
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