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;
33 /* stripe chunk size */
37 /* Needed for handling events */
40 /* Work struct used for triggering events*/
41 struct work_struct trigger_event;
43 struct stripe stripe[0];
47 * An event is triggered whenever a drive
48 * drops out of a stripe volume.
50 static void trigger_event(struct work_struct *work)
52 struct stripe_c *sc = container_of(work, struct stripe_c,
54 dm_table_event(sc->ti->table);
57 static inline struct stripe_c *alloc_context(unsigned int stripes)
61 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
65 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
67 return kmalloc(len, GFP_KERNEL);
71 * Parse a single <dev> <sector> pair
73 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
74 unsigned int stripe, char **argv)
76 unsigned long long start;
79 if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
82 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
83 &sc->stripe[stripe].dev))
86 sc->stripe[stripe].physical_start = start;
92 * Construct a striped mapping.
93 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
95 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
105 ti->error = "Not enough arguments";
109 if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
110 ti->error = "Invalid stripe count";
114 if (kstrtouint(argv[1], 10, &chunk_size)) {
115 ti->error = "Invalid chunk_size";
120 * chunk_size is a power of two
122 if (!is_power_of_2(chunk_size) ||
123 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
124 ti->error = "Invalid chunk size";
128 if (ti->len & (chunk_size - 1)) {
129 ti->error = "Target length not divisible by "
134 if (sector_div(width, stripes)) {
135 ti->error = "Target length not divisible by "
141 * Do we have enough arguments for that many stripes ?
143 if (argc != (2 + 2 * stripes)) {
144 ti->error = "Not enough destinations "
149 sc = alloc_context(stripes);
151 ti->error = "Memory allocation for striped context "
156 INIT_WORK(&sc->trigger_event, trigger_event);
158 /* Set pointer to dm target; used in trigger_event */
160 sc->stripes = stripes;
161 sc->stripe_width = width;
163 if (stripes & (stripes - 1))
164 sc->stripes_shift = -1;
166 sc->stripes_shift = __ffs(stripes);
168 r = dm_set_target_max_io_len(ti, chunk_size);
172 ti->num_flush_requests = stripes;
173 ti->num_discard_requests = stripes;
175 sc->chunk_shift = ffs(chunk_size) - 1;
176 sc->chunk_mask = ((sector_t) chunk_size) - 1;
179 * Get the stripe destinations.
181 for (i = 0; i < stripes; i++) {
184 r = get_stripe(ti, sc, i, argv);
186 ti->error = "Couldn't parse stripe destination";
188 dm_put_device(ti, sc->stripe[i].dev);
192 atomic_set(&(sc->stripe[i].error_count), 0);
200 static void stripe_dtr(struct dm_target *ti)
203 struct stripe_c *sc = (struct stripe_c *) ti->private;
205 for (i = 0; i < sc->stripes; i++)
206 dm_put_device(ti, sc->stripe[i].dev);
208 flush_work_sync(&sc->trigger_event);
212 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
213 uint32_t *stripe, sector_t *result)
215 sector_t offset = dm_target_offset(sc->ti, sector);
216 sector_t chunk = offset >> sc->chunk_shift;
218 if (sc->stripes_shift < 0)
219 *stripe = sector_div(chunk, sc->stripes);
221 *stripe = chunk & (sc->stripes - 1);
222 chunk >>= sc->stripes_shift;
225 *result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
228 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
229 uint32_t target_stripe, sector_t *result)
233 stripe_map_sector(sc, sector, &stripe, result);
234 if (stripe == target_stripe)
236 *result &= ~sc->chunk_mask; /* round down */
237 if (target_stripe < stripe)
238 *result += sc->chunk_mask + 1; /* next chunk */
241 static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
242 uint32_t target_stripe)
246 stripe_map_range_sector(sc, bio->bi_sector, target_stripe, &begin);
247 stripe_map_range_sector(sc, bio->bi_sector + bio_sectors(bio),
248 target_stripe, &end);
250 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
251 bio->bi_sector = begin + sc->stripe[target_stripe].physical_start;
252 bio->bi_size = to_bytes(end - begin);
253 return DM_MAPIO_REMAPPED;
255 /* The range doesn't map to the target stripe */
257 return DM_MAPIO_SUBMITTED;
261 static int stripe_map(struct dm_target *ti, struct bio *bio,
262 union map_info *map_context)
264 struct stripe_c *sc = ti->private;
266 unsigned target_request_nr;
268 if (bio->bi_rw & REQ_FLUSH) {
269 target_request_nr = map_context->target_request_nr;
270 BUG_ON(target_request_nr >= sc->stripes);
271 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
272 return DM_MAPIO_REMAPPED;
274 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
275 target_request_nr = map_context->target_request_nr;
276 BUG_ON(target_request_nr >= sc->stripes);
277 return stripe_map_discard(sc, bio, target_request_nr);
280 stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
282 bio->bi_sector += sc->stripe[stripe].physical_start;
283 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
285 return DM_MAPIO_REMAPPED;
292 * #stripes [stripe_name <stripe_name>] [group word count]
293 * [error count 'A|D' <error count 'A|D'>]
296 * #stripes [stripe chunk size]
297 * [stripe_name physical_start <stripe_name physical_start>]
301 static int stripe_status(struct dm_target *ti,
302 status_type_t type, char *result, unsigned int maxlen)
304 struct stripe_c *sc = (struct stripe_c *) ti->private;
305 char buffer[sc->stripes + 1];
310 case STATUSTYPE_INFO:
311 DMEMIT("%d ", sc->stripes);
312 for (i = 0; i < sc->stripes; i++) {
313 DMEMIT("%s ", sc->stripe[i].dev->name);
314 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
318 DMEMIT("1 %s", buffer);
321 case STATUSTYPE_TABLE:
322 DMEMIT("%d %llu", sc->stripes,
323 (unsigned long long)sc->chunk_mask + 1);
324 for (i = 0; i < sc->stripes; i++)
325 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
326 (unsigned long long)sc->stripe[i].physical_start);
332 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
333 int error, union map_info *map_context)
336 char major_minor[16];
337 struct stripe_c *sc = ti->private;
340 return 0; /* I/O complete */
342 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
345 if (error == -EOPNOTSUPP)
348 memset(major_minor, 0, sizeof(major_minor));
349 sprintf(major_minor, "%d:%d",
350 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
351 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
354 * Test to see which stripe drive triggered the event
355 * and increment error count for all stripes on that device.
356 * If the error count for a given device exceeds the threshold
357 * value we will no longer trigger any further events.
359 for (i = 0; i < sc->stripes; i++)
360 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
361 atomic_inc(&(sc->stripe[i].error_count));
362 if (atomic_read(&(sc->stripe[i].error_count)) <
363 DM_IO_ERROR_THRESHOLD)
364 schedule_work(&sc->trigger_event);
370 static int stripe_iterate_devices(struct dm_target *ti,
371 iterate_devices_callout_fn fn, void *data)
373 struct stripe_c *sc = ti->private;
378 ret = fn(ti, sc->stripe[i].dev,
379 sc->stripe[i].physical_start,
380 sc->stripe_width, data);
381 } while (!ret && ++i < sc->stripes);
386 static void stripe_io_hints(struct dm_target *ti,
387 struct queue_limits *limits)
389 struct stripe_c *sc = ti->private;
390 unsigned chunk_size = (sc->chunk_mask + 1) << 9;
392 blk_limits_io_min(limits, chunk_size);
393 blk_limits_io_opt(limits, chunk_size * sc->stripes);
396 static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
397 struct bio_vec *biovec, int max_size)
399 struct stripe_c *sc = ti->private;
400 sector_t bvm_sector = bvm->bi_sector;
402 struct request_queue *q;
404 stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
406 q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
407 if (!q->merge_bvec_fn)
410 bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
411 bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
413 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
416 static struct target_type stripe_target = {
418 .version = {1, 4, 0},
419 .module = THIS_MODULE,
423 .end_io = stripe_end_io,
424 .status = stripe_status,
425 .iterate_devices = stripe_iterate_devices,
426 .io_hints = stripe_io_hints,
427 .merge = stripe_merge,
430 int __init dm_stripe_init(void)
434 r = dm_register_target(&stripe_target);
436 DMWARN("target registration failed");
443 void dm_stripe_exit(void)
445 dm_unregister_target(&stripe_target);