2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
4 * This file is released under the GPL.
7 #include <linux/device-mapper.h>
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>
16 #define DM_MSG_PREFIX "striped"
17 #define DM_IO_ERROR_THRESHOLD 15
21 sector_t physical_start;
30 /* The size of this target / num. stripes */
31 sector_t stripe_width;
36 /* Needed for handling events */
39 /* Work struct used for triggering events*/
40 struct work_struct trigger_event;
42 struct stripe stripe[0];
46 * An event is triggered whenever a drive
47 * drops out of a stripe volume.
49 static void trigger_event(struct work_struct *work)
51 struct stripe_c *sc = container_of(work, struct stripe_c,
53 dm_table_event(sc->ti->table);
56 static inline struct stripe_c *alloc_context(unsigned int stripes)
60 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
64 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
66 return kmalloc(len, GFP_KERNEL);
70 * Parse a single <dev> <sector> pair
72 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
73 unsigned int stripe, char **argv)
75 unsigned long long start;
78 if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
81 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
82 &sc->stripe[stripe].dev))
85 sc->stripe[stripe].physical_start = start;
91 * Construct a striped mapping.
92 * <number of stripes> <chunk size> [<dev_path> <offset>]+
94 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
104 ti->error = "Not enough arguments";
108 if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
109 ti->error = "Invalid stripe count";
113 if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
114 ti->error = "Invalid chunk_size";
119 if (sector_div(width, chunk_size)) {
120 ti->error = "Target length not divisible by "
125 if (sector_div(width, stripes)) {
126 ti->error = "Target length not divisible by "
132 * Do we have enough arguments for that many stripes ?
134 if (argc != (2 + 2 * stripes)) {
135 ti->error = "Not enough destinations "
140 sc = alloc_context(stripes);
142 ti->error = "Memory allocation for striped context "
147 INIT_WORK(&sc->trigger_event, trigger_event);
149 /* Set pointer to dm target; used in trigger_event */
151 sc->stripes = stripes;
152 sc->stripe_width = width;
154 if (stripes & (stripes - 1))
155 sc->stripes_shift = -1;
157 sc->stripes_shift = __ffs(stripes);
159 r = dm_set_target_max_io_len(ti, chunk_size);
163 ti->num_flush_requests = stripes;
164 ti->num_discard_requests = stripes;
166 sc->chunk_size = chunk_size;
167 if (chunk_size & (chunk_size - 1))
168 sc->chunk_size_shift = -1;
170 sc->chunk_size_shift = __ffs(chunk_size);
173 * Get the stripe destinations.
175 for (i = 0; i < stripes; i++) {
178 r = get_stripe(ti, sc, i, argv);
180 ti->error = "Couldn't parse stripe destination";
182 dm_put_device(ti, sc->stripe[i].dev);
186 atomic_set(&(sc->stripe[i].error_count), 0);
194 static void stripe_dtr(struct dm_target *ti)
197 struct stripe_c *sc = (struct stripe_c *) ti->private;
199 for (i = 0; i < sc->stripes; i++)
200 dm_put_device(ti, sc->stripe[i].dev);
202 flush_work(&sc->trigger_event);
206 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
207 uint32_t *stripe, sector_t *result)
209 sector_t chunk = dm_target_offset(sc->ti, sector);
210 sector_t chunk_offset;
212 if (sc->chunk_size_shift < 0)
213 chunk_offset = sector_div(chunk, sc->chunk_size);
215 chunk_offset = chunk & (sc->chunk_size - 1);
216 chunk >>= sc->chunk_size_shift;
219 if (sc->stripes_shift < 0)
220 *stripe = sector_div(chunk, sc->stripes);
222 *stripe = chunk & (sc->stripes - 1);
223 chunk >>= sc->stripes_shift;
226 if (sc->chunk_size_shift < 0)
227 chunk *= sc->chunk_size;
229 chunk <<= sc->chunk_size_shift;
231 *result = chunk + chunk_offset;
234 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
235 uint32_t target_stripe, sector_t *result)
239 stripe_map_sector(sc, sector, &stripe, result);
240 if (stripe == target_stripe)
245 if (sc->chunk_size_shift < 0)
246 *result -= sector_div(sector, sc->chunk_size);
248 *result = sector & ~(sector_t)(sc->chunk_size - 1);
250 if (target_stripe < stripe)
251 *result += sc->chunk_size; /* next chunk */
254 static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
255 uint32_t target_stripe)
259 stripe_map_range_sector(sc, bio->bi_sector, target_stripe, &begin);
260 stripe_map_range_sector(sc, bio->bi_sector + bio_sectors(bio),
261 target_stripe, &end);
263 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
264 bio->bi_sector = begin + sc->stripe[target_stripe].physical_start;
265 bio->bi_size = to_bytes(end - begin);
266 return DM_MAPIO_REMAPPED;
268 /* The range doesn't map to the target stripe */
270 return DM_MAPIO_SUBMITTED;
274 static int stripe_map(struct dm_target *ti, struct bio *bio)
276 struct stripe_c *sc = ti->private;
278 unsigned target_request_nr;
280 if (bio->bi_rw & REQ_FLUSH) {
281 target_request_nr = dm_bio_get_target_request_nr(bio);
282 BUG_ON(target_request_nr >= sc->stripes);
283 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
284 return DM_MAPIO_REMAPPED;
286 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
287 target_request_nr = dm_bio_get_target_request_nr(bio);
288 BUG_ON(target_request_nr >= sc->stripes);
289 return stripe_map_discard(sc, bio, target_request_nr);
292 stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
294 bio->bi_sector += sc->stripe[stripe].physical_start;
295 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
297 return DM_MAPIO_REMAPPED;
304 * #stripes [stripe_name <stripe_name>] [group word count]
305 * [error count 'A|D' <error count 'A|D'>]
308 * #stripes [stripe chunk size]
309 * [stripe_name physical_start <stripe_name physical_start>]
313 static int stripe_status(struct dm_target *ti, status_type_t type,
314 unsigned status_flags, char *result, unsigned maxlen)
316 struct stripe_c *sc = (struct stripe_c *) ti->private;
317 char buffer[sc->stripes + 1];
322 case STATUSTYPE_INFO:
323 DMEMIT("%d ", sc->stripes);
324 for (i = 0; i < sc->stripes; i++) {
325 DMEMIT("%s ", sc->stripe[i].dev->name);
326 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
330 DMEMIT("1 %s", buffer);
333 case STATUSTYPE_TABLE:
334 DMEMIT("%d %llu", sc->stripes,
335 (unsigned long long)sc->chunk_size);
336 for (i = 0; i < sc->stripes; i++)
337 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
338 (unsigned long long)sc->stripe[i].physical_start);
344 static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error)
347 char major_minor[16];
348 struct stripe_c *sc = ti->private;
351 return 0; /* I/O complete */
353 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
356 if (error == -EOPNOTSUPP)
359 memset(major_minor, 0, sizeof(major_minor));
360 sprintf(major_minor, "%d:%d",
361 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
362 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
365 * Test to see which stripe drive triggered the event
366 * and increment error count for all stripes on that device.
367 * If the error count for a given device exceeds the threshold
368 * value we will no longer trigger any further events.
370 for (i = 0; i < sc->stripes; i++)
371 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
372 atomic_inc(&(sc->stripe[i].error_count));
373 if (atomic_read(&(sc->stripe[i].error_count)) <
374 DM_IO_ERROR_THRESHOLD)
375 schedule_work(&sc->trigger_event);
381 static int stripe_iterate_devices(struct dm_target *ti,
382 iterate_devices_callout_fn fn, void *data)
384 struct stripe_c *sc = ti->private;
389 ret = fn(ti, sc->stripe[i].dev,
390 sc->stripe[i].physical_start,
391 sc->stripe_width, data);
392 } while (!ret && ++i < sc->stripes);
397 static void stripe_io_hints(struct dm_target *ti,
398 struct queue_limits *limits)
400 struct stripe_c *sc = ti->private;
401 unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
403 blk_limits_io_min(limits, chunk_size);
404 blk_limits_io_opt(limits, chunk_size * sc->stripes);
407 static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
408 struct bio_vec *biovec, int max_size)
410 struct stripe_c *sc = ti->private;
411 sector_t bvm_sector = bvm->bi_sector;
413 struct request_queue *q;
415 stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
417 q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
418 if (!q->merge_bvec_fn)
421 bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
422 bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
424 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
427 static struct target_type stripe_target = {
429 .version = {1, 5, 0},
430 .module = THIS_MODULE,
434 .end_io = stripe_end_io,
435 .status = stripe_status,
436 .iterate_devices = stripe_iterate_devices,
437 .io_hints = stripe_io_hints,
438 .merge = stripe_merge,
441 int __init dm_stripe_init(void)
445 r = dm_register_target(&stripe_target);
447 DMWARN("target registration failed");
454 void dm_stripe_exit(void)
456 dm_unregister_target(&stripe_target);