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;
29 sector_t stripes_mask;
31 /* The size of this target / num. stripes */
32 sector_t stripe_width;
34 /* stripe chunk size */
38 /* Needed for handling events */
41 /* Work struct used for triggering events*/
42 struct work_struct trigger_event;
44 struct stripe stripe[0];
48 * An event is triggered whenever a drive
49 * drops out of a stripe volume.
51 static void trigger_event(struct work_struct *work)
53 struct stripe_c *sc = container_of(work, struct stripe_c,
55 dm_table_event(sc->ti->table);
58 static inline struct stripe_c *alloc_context(unsigned int stripes)
62 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
66 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
68 return kmalloc(len, GFP_KERNEL);
72 * Parse a single <dev> <sector> pair
74 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
75 unsigned int stripe, char **argv)
77 unsigned long long start;
80 if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
83 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
84 &sc->stripe[stripe].dev))
87 sc->stripe[stripe].physical_start = start;
93 * Construct a striped mapping.
94 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
96 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
106 ti->error = "Not enough arguments";
110 if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
111 ti->error = "Invalid stripe count";
115 if (kstrtouint(argv[1], 10, &chunk_size)) {
116 ti->error = "Invalid chunk_size";
121 * chunk_size is a power of two
123 if (!is_power_of_2(chunk_size) ||
124 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
125 ti->error = "Invalid chunk size";
129 if (ti->len & (chunk_size - 1)) {
130 ti->error = "Target length not divisible by "
136 if (sector_div(width, stripes)) {
137 ti->error = "Target length not divisible by "
143 * Do we have enough arguments for that many stripes ?
145 if (argc != (2 + 2 * stripes)) {
146 ti->error = "Not enough destinations "
151 sc = alloc_context(stripes);
153 ti->error = "Memory allocation for striped context "
158 INIT_WORK(&sc->trigger_event, trigger_event);
160 /* Set pointer to dm target; used in trigger_event */
162 sc->stripes = stripes;
163 sc->stripe_width = width;
165 if (stripes & (stripes - 1))
166 sc->stripes_shift = -1;
168 sc->stripes_shift = ffs(stripes) - 1;
169 sc->stripes_mask = ((sector_t) stripes) - 1;
172 ti->split_io = chunk_size;
173 ti->num_flush_requests = stripes;
174 ti->num_discard_requests = stripes;
176 sc->chunk_shift = ffs(chunk_size) - 1;
177 sc->chunk_mask = ((sector_t) chunk_size) - 1;
180 * Get the stripe destinations.
182 for (i = 0; i < stripes; i++) {
185 r = get_stripe(ti, sc, i, argv);
187 ti->error = "Couldn't parse stripe destination";
189 dm_put_device(ti, sc->stripe[i].dev);
193 atomic_set(&(sc->stripe[i].error_count), 0);
201 static void stripe_dtr(struct dm_target *ti)
204 struct stripe_c *sc = (struct stripe_c *) ti->private;
206 for (i = 0; i < sc->stripes; i++)
207 dm_put_device(ti, sc->stripe[i].dev);
209 flush_work_sync(&sc->trigger_event);
213 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
214 uint32_t *stripe, sector_t *result)
216 sector_t offset = dm_target_offset(sc->ti, sector);
217 sector_t chunk = offset >> sc->chunk_shift;
219 if (sc->stripes_shift < 0)
220 *stripe = sector_div(chunk, sc->stripes);
222 *stripe = chunk & sc->stripes_mask;
223 chunk >>= sc->stripes_shift;
226 *result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
229 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
230 uint32_t target_stripe, sector_t *result)
234 stripe_map_sector(sc, sector, &stripe, result);
235 if (stripe == target_stripe)
237 *result &= ~sc->chunk_mask; /* round down */
238 if (target_stripe < stripe)
239 *result += sc->chunk_mask + 1; /* next chunk */
242 static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
243 uint32_t target_stripe)
247 stripe_map_range_sector(sc, bio->bi_sector, target_stripe, &begin);
248 stripe_map_range_sector(sc, bio->bi_sector + bio_sectors(bio),
249 target_stripe, &end);
251 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
252 bio->bi_sector = begin + sc->stripe[target_stripe].physical_start;
253 bio->bi_size = to_bytes(end - begin);
254 return DM_MAPIO_REMAPPED;
256 /* The range doesn't map to the target stripe */
258 return DM_MAPIO_SUBMITTED;
262 static int stripe_map(struct dm_target *ti, struct bio *bio,
263 union map_info *map_context)
265 struct stripe_c *sc = ti->private;
267 unsigned target_request_nr;
269 if (bio->bi_rw & REQ_FLUSH) {
270 target_request_nr = map_context->target_request_nr;
271 BUG_ON(target_request_nr >= sc->stripes);
272 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
273 return DM_MAPIO_REMAPPED;
275 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
276 target_request_nr = map_context->target_request_nr;
277 BUG_ON(target_request_nr >= sc->stripes);
278 return stripe_map_discard(sc, bio, target_request_nr);
281 stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
283 bio->bi_sector += sc->stripe[stripe].physical_start;
284 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
286 return DM_MAPIO_REMAPPED;
293 * #stripes [stripe_name <stripe_name>] [group word count]
294 * [error count 'A|D' <error count 'A|D'>]
297 * #stripes [stripe chunk size]
298 * [stripe_name physical_start <stripe_name physical_start>]
302 static int stripe_status(struct dm_target *ti,
303 status_type_t type, char *result, unsigned int maxlen)
305 struct stripe_c *sc = (struct stripe_c *) ti->private;
306 char buffer[sc->stripes + 1];
311 case STATUSTYPE_INFO:
312 DMEMIT("%d ", sc->stripes);
313 for (i = 0; i < sc->stripes; i++) {
314 DMEMIT("%s ", sc->stripe[i].dev->name);
315 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
319 DMEMIT("1 %s", buffer);
322 case STATUSTYPE_TABLE:
323 DMEMIT("%d %llu", sc->stripes,
324 (unsigned long long)sc->chunk_mask + 1);
325 for (i = 0; i < sc->stripes; i++)
326 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
327 (unsigned long long)sc->stripe[i].physical_start);
333 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
334 int error, union map_info *map_context)
337 char major_minor[16];
338 struct stripe_c *sc = ti->private;
341 return 0; /* I/O complete */
343 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
346 if (error == -EOPNOTSUPP)
349 memset(major_minor, 0, sizeof(major_minor));
350 sprintf(major_minor, "%d:%d",
351 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
352 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
355 * Test to see which stripe drive triggered the event
356 * and increment error count for all stripes on that device.
357 * If the error count for a given device exceeds the threshold
358 * value we will no longer trigger any further events.
360 for (i = 0; i < sc->stripes; i++)
361 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
362 atomic_inc(&(sc->stripe[i].error_count));
363 if (atomic_read(&(sc->stripe[i].error_count)) <
364 DM_IO_ERROR_THRESHOLD)
365 schedule_work(&sc->trigger_event);
371 static int stripe_iterate_devices(struct dm_target *ti,
372 iterate_devices_callout_fn fn, void *data)
374 struct stripe_c *sc = ti->private;
379 ret = fn(ti, sc->stripe[i].dev,
380 sc->stripe[i].physical_start,
381 sc->stripe_width, data);
382 } while (!ret && ++i < sc->stripes);
387 static void stripe_io_hints(struct dm_target *ti,
388 struct queue_limits *limits)
390 struct stripe_c *sc = ti->private;
391 unsigned chunk_size = (sc->chunk_mask + 1) << 9;
393 blk_limits_io_min(limits, chunk_size);
394 blk_limits_io_opt(limits, chunk_size * sc->stripes);
397 static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
398 struct bio_vec *biovec, int max_size)
400 struct stripe_c *sc = ti->private;
401 sector_t bvm_sector = bvm->bi_sector;
403 struct request_queue *q;
405 stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
407 q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
408 if (!q->merge_bvec_fn)
411 bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
412 bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
414 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
417 static struct target_type stripe_target = {
419 .version = {1, 4, 0},
420 .module = THIS_MODULE,
424 .end_io = stripe_end_io,
425 .status = stripe_status,
426 .iterate_devices = stripe_iterate_devices,
427 .io_hints = stripe_io_hints,
428 .merge = stripe_merge,
431 int __init dm_stripe_init(void)
435 r = dm_register_target(&stripe_target);
437 DMWARN("target registration failed");
444 void dm_stripe_exit(void)
446 dm_unregister_target(&stripe_target);