2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
4 * This file is released under the GPL.
8 #include <linux/device-mapper.h>
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/blkdev.h>
13 #include <linux/bio.h>
14 #include <linux/dax.h>
15 #include <linux/slab.h>
16 #include <linux/log2.h>
18 #define DM_MSG_PREFIX "striped"
19 #define DM_IO_ERROR_THRESHOLD 15
23 sector_t physical_start;
32 /* The size of this target / num. stripes */
33 sector_t stripe_width;
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;
81 if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
84 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
85 &sc->stripe[stripe].dev);
89 sc->stripe[stripe].physical_start = start;
95 * Construct a striped mapping.
96 * <number of stripes> <chunk size> [<dev_path> <offset>]+
98 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
101 sector_t width, tmp_len;
108 ti->error = "Not enough arguments";
112 if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
113 ti->error = "Invalid stripe count";
117 if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
118 ti->error = "Invalid chunk_size";
123 if (sector_div(width, stripes)) {
124 ti->error = "Target length not divisible by "
130 if (sector_div(tmp_len, chunk_size)) {
131 ti->error = "Target length not divisible by "
137 * Do we have enough arguments for that many stripes ?
139 if (argc != (2 + 2 * stripes)) {
140 ti->error = "Not enough destinations "
145 sc = alloc_context(stripes);
147 ti->error = "Memory allocation for striped context "
152 INIT_WORK(&sc->trigger_event, trigger_event);
154 /* Set pointer to dm target; used in trigger_event */
156 sc->stripes = stripes;
157 sc->stripe_width = width;
159 if (stripes & (stripes - 1))
160 sc->stripes_shift = -1;
162 sc->stripes_shift = __ffs(stripes);
164 r = dm_set_target_max_io_len(ti, chunk_size);
170 ti->num_flush_bios = stripes;
171 ti->num_discard_bios = stripes;
172 ti->num_write_same_bios = stripes;
173 ti->num_write_zeroes_bios = stripes;
175 sc->chunk_size = chunk_size;
176 if (chunk_size & (chunk_size - 1))
177 sc->chunk_size_shift = -1;
179 sc->chunk_size_shift = __ffs(chunk_size);
182 * Get the stripe destinations.
184 for (i = 0; i < stripes; i++) {
187 r = get_stripe(ti, sc, i, argv);
189 ti->error = "Couldn't parse stripe destination";
191 dm_put_device(ti, sc->stripe[i].dev);
195 atomic_set(&(sc->stripe[i].error_count), 0);
203 static void stripe_dtr(struct dm_target *ti)
206 struct stripe_c *sc = (struct stripe_c *) ti->private;
208 for (i = 0; i < sc->stripes; i++)
209 dm_put_device(ti, sc->stripe[i].dev);
211 flush_work(&sc->trigger_event);
215 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
216 uint32_t *stripe, sector_t *result)
218 sector_t chunk = dm_target_offset(sc->ti, sector);
219 sector_t chunk_offset;
221 if (sc->chunk_size_shift < 0)
222 chunk_offset = sector_div(chunk, sc->chunk_size);
224 chunk_offset = chunk & (sc->chunk_size - 1);
225 chunk >>= sc->chunk_size_shift;
228 if (sc->stripes_shift < 0)
229 *stripe = sector_div(chunk, sc->stripes);
231 *stripe = chunk & (sc->stripes - 1);
232 chunk >>= sc->stripes_shift;
235 if (sc->chunk_size_shift < 0)
236 chunk *= sc->chunk_size;
238 chunk <<= sc->chunk_size_shift;
240 *result = chunk + chunk_offset;
243 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
244 uint32_t target_stripe, sector_t *result)
248 stripe_map_sector(sc, sector, &stripe, result);
249 if (stripe == target_stripe)
254 if (sc->chunk_size_shift < 0)
255 *result -= sector_div(sector, sc->chunk_size);
257 *result = sector & ~(sector_t)(sc->chunk_size - 1);
259 if (target_stripe < stripe)
260 *result += sc->chunk_size; /* next chunk */
263 static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
264 uint32_t target_stripe)
268 stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
269 target_stripe, &begin);
270 stripe_map_range_sector(sc, bio_end_sector(bio),
271 target_stripe, &end);
273 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
274 bio->bi_iter.bi_sector = begin +
275 sc->stripe[target_stripe].physical_start;
276 bio->bi_iter.bi_size = to_bytes(end - begin);
277 return DM_MAPIO_REMAPPED;
279 /* The range doesn't map to the target stripe */
281 return DM_MAPIO_SUBMITTED;
285 static int stripe_map(struct dm_target *ti, struct bio *bio)
287 struct stripe_c *sc = ti->private;
289 unsigned target_bio_nr;
291 if (bio->bi_opf & REQ_PREFLUSH) {
292 target_bio_nr = dm_bio_get_target_bio_nr(bio);
293 BUG_ON(target_bio_nr >= sc->stripes);
294 bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev;
295 return DM_MAPIO_REMAPPED;
297 if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
298 unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) ||
299 unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
300 target_bio_nr = dm_bio_get_target_bio_nr(bio);
301 BUG_ON(target_bio_nr >= sc->stripes);
302 return stripe_map_range(sc, bio, target_bio_nr);
305 stripe_map_sector(sc, bio->bi_iter.bi_sector,
306 &stripe, &bio->bi_iter.bi_sector);
308 bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
309 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
311 return DM_MAPIO_REMAPPED;
314 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
315 long nr_pages, void **kaddr, pfn_t *pfn)
317 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
318 struct stripe_c *sc = ti->private;
319 struct dax_device *dax_dev;
320 struct block_device *bdev;
324 stripe_map_sector(sc, sector, &stripe, &dev_sector);
325 dev_sector += sc->stripe[stripe].physical_start;
326 dax_dev = sc->stripe[stripe].dev->dax_dev;
327 bdev = sc->stripe[stripe].dev->bdev;
329 ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
332 return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
339 * #stripes [stripe_name <stripe_name>] [group word count]
340 * [error count 'A|D' <error count 'A|D'>]
343 * #stripes [stripe chunk size]
344 * [stripe_name physical_start <stripe_name physical_start>]
348 static void stripe_status(struct dm_target *ti, status_type_t type,
349 unsigned status_flags, char *result, unsigned maxlen)
351 struct stripe_c *sc = (struct stripe_c *) ti->private;
352 char buffer[sc->stripes + 1];
357 case STATUSTYPE_INFO:
358 DMEMIT("%d ", sc->stripes);
359 for (i = 0; i < sc->stripes; i++) {
360 DMEMIT("%s ", sc->stripe[i].dev->name);
361 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
365 DMEMIT("1 %s", buffer);
368 case STATUSTYPE_TABLE:
369 DMEMIT("%d %llu", sc->stripes,
370 (unsigned long long)sc->chunk_size);
371 for (i = 0; i < sc->stripes; i++)
372 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
373 (unsigned long long)sc->stripe[i].physical_start);
378 static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error)
381 char major_minor[16];
382 struct stripe_c *sc = ti->private;
385 return 0; /* I/O complete */
387 if ((error == -EWOULDBLOCK) && (bio->bi_opf & REQ_RAHEAD))
390 if (error == -EOPNOTSUPP)
393 memset(major_minor, 0, sizeof(major_minor));
394 sprintf(major_minor, "%d:%d",
395 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
396 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
399 * Test to see which stripe drive triggered the event
400 * and increment error count for all stripes on that device.
401 * If the error count for a given device exceeds the threshold
402 * value we will no longer trigger any further events.
404 for (i = 0; i < sc->stripes; i++)
405 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
406 atomic_inc(&(sc->stripe[i].error_count));
407 if (atomic_read(&(sc->stripe[i].error_count)) <
408 DM_IO_ERROR_THRESHOLD)
409 schedule_work(&sc->trigger_event);
415 static int stripe_iterate_devices(struct dm_target *ti,
416 iterate_devices_callout_fn fn, void *data)
418 struct stripe_c *sc = ti->private;
423 ret = fn(ti, sc->stripe[i].dev,
424 sc->stripe[i].physical_start,
425 sc->stripe_width, data);
426 } while (!ret && ++i < sc->stripes);
431 static void stripe_io_hints(struct dm_target *ti,
432 struct queue_limits *limits)
434 struct stripe_c *sc = ti->private;
435 unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
437 blk_limits_io_min(limits, chunk_size);
438 blk_limits_io_opt(limits, chunk_size * sc->stripes);
441 static struct target_type stripe_target = {
443 .version = {1, 6, 0},
444 .features = DM_TARGET_PASSES_INTEGRITY,
445 .module = THIS_MODULE,
449 .end_io = stripe_end_io,
450 .status = stripe_status,
451 .iterate_devices = stripe_iterate_devices,
452 .io_hints = stripe_io_hints,
453 .direct_access = stripe_dax_direct_access,
456 int __init dm_stripe_init(void)
460 r = dm_register_target(&stripe_target);
462 DMWARN("target registration failed");
467 void dm_stripe_exit(void)
469 dm_unregister_target(&stripe_target);