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;
35 /* Needed for handling events */
38 /* Work struct used for triggering events*/
39 struct work_struct trigger_event;
41 struct stripe stripe[0];
45 * An event is triggered whenever a drive
46 * drops out of a stripe volume.
48 static void trigger_event(struct work_struct *work)
50 struct stripe_c *sc = container_of(work, struct stripe_c,
52 dm_table_event(sc->ti->table);
55 static inline struct stripe_c *alloc_context(unsigned int stripes)
59 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
63 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
65 return kmalloc(len, GFP_KERNEL);
69 * Parse a single <dev> <sector> pair
71 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
72 unsigned int stripe, char **argv)
74 unsigned long long start;
77 if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
80 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
81 &sc->stripe[stripe].dev))
84 sc->stripe[stripe].physical_start = start;
90 * Construct a striped mapping.
91 * <number of stripes> <chunk size> [<dev_path> <offset>]+
93 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
103 ti->error = "Not enough arguments";
107 if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
108 ti->error = "Invalid stripe count";
112 if (kstrtouint(argv[1], 10, &chunk_size) ||
113 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
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;
169 * Get the stripe destinations.
171 for (i = 0; i < stripes; i++) {
174 r = get_stripe(ti, sc, i, argv);
176 ti->error = "Couldn't parse stripe destination";
178 dm_put_device(ti, sc->stripe[i].dev);
182 atomic_set(&(sc->stripe[i].error_count), 0);
190 static void stripe_dtr(struct dm_target *ti)
193 struct stripe_c *sc = (struct stripe_c *) ti->private;
195 for (i = 0; i < sc->stripes; i++)
196 dm_put_device(ti, sc->stripe[i].dev);
198 flush_work_sync(&sc->trigger_event);
202 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
203 uint32_t *stripe, sector_t *result)
205 sector_t chunk = dm_target_offset(sc->ti, sector);
206 sector_t chunk_offset = sector_div(chunk, sc->chunk_size);
208 if (sc->stripes_shift < 0)
209 *stripe = sector_div(chunk, sc->stripes);
211 *stripe = chunk & (sc->stripes - 1);
212 chunk >>= sc->stripes_shift;
215 *result = (chunk * sc->chunk_size) + chunk_offset;
218 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
219 uint32_t target_stripe, sector_t *result)
223 stripe_map_sector(sc, sector, &stripe, result);
224 if (stripe == target_stripe)
229 *result -= sector_div(sector, sc->chunk_size);
231 if (target_stripe < stripe)
232 *result += sc->chunk_size; /* next chunk */
235 static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
236 uint32_t target_stripe)
240 stripe_map_range_sector(sc, bio->bi_sector, target_stripe, &begin);
241 stripe_map_range_sector(sc, bio->bi_sector + bio_sectors(bio),
242 target_stripe, &end);
244 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
245 bio->bi_sector = begin + sc->stripe[target_stripe].physical_start;
246 bio->bi_size = to_bytes(end - begin);
247 return DM_MAPIO_REMAPPED;
249 /* The range doesn't map to the target stripe */
251 return DM_MAPIO_SUBMITTED;
255 static int stripe_map(struct dm_target *ti, struct bio *bio,
256 union map_info *map_context)
258 struct stripe_c *sc = ti->private;
260 unsigned target_request_nr;
262 if (bio->bi_rw & REQ_FLUSH) {
263 target_request_nr = map_context->target_request_nr;
264 BUG_ON(target_request_nr >= sc->stripes);
265 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
266 return DM_MAPIO_REMAPPED;
268 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
269 target_request_nr = map_context->target_request_nr;
270 BUG_ON(target_request_nr >= sc->stripes);
271 return stripe_map_discard(sc, bio, target_request_nr);
274 stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
276 bio->bi_sector += sc->stripe[stripe].physical_start;
277 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
279 return DM_MAPIO_REMAPPED;
286 * #stripes [stripe_name <stripe_name>] [group word count]
287 * [error count 'A|D' <error count 'A|D'>]
290 * #stripes [stripe chunk size]
291 * [stripe_name physical_start <stripe_name physical_start>]
295 static int stripe_status(struct dm_target *ti,
296 status_type_t type, char *result, unsigned int maxlen)
298 struct stripe_c *sc = (struct stripe_c *) ti->private;
299 char buffer[sc->stripes + 1];
304 case STATUSTYPE_INFO:
305 DMEMIT("%d ", sc->stripes);
306 for (i = 0; i < sc->stripes; i++) {
307 DMEMIT("%s ", sc->stripe[i].dev->name);
308 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
312 DMEMIT("1 %s", buffer);
315 case STATUSTYPE_TABLE:
316 DMEMIT("%d %llu", sc->stripes,
317 (unsigned long long)sc->chunk_size);
318 for (i = 0; i < sc->stripes; i++)
319 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
320 (unsigned long long)sc->stripe[i].physical_start);
326 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
327 int error, union map_info *map_context)
330 char major_minor[16];
331 struct stripe_c *sc = ti->private;
334 return 0; /* I/O complete */
336 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
339 if (error == -EOPNOTSUPP)
342 memset(major_minor, 0, sizeof(major_minor));
343 sprintf(major_minor, "%d:%d",
344 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
345 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
348 * Test to see which stripe drive triggered the event
349 * and increment error count for all stripes on that device.
350 * If the error count for a given device exceeds the threshold
351 * value we will no longer trigger any further events.
353 for (i = 0; i < sc->stripes; i++)
354 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
355 atomic_inc(&(sc->stripe[i].error_count));
356 if (atomic_read(&(sc->stripe[i].error_count)) <
357 DM_IO_ERROR_THRESHOLD)
358 schedule_work(&sc->trigger_event);
364 static int stripe_iterate_devices(struct dm_target *ti,
365 iterate_devices_callout_fn fn, void *data)
367 struct stripe_c *sc = ti->private;
372 ret = fn(ti, sc->stripe[i].dev,
373 sc->stripe[i].physical_start,
374 sc->stripe_width, data);
375 } while (!ret && ++i < sc->stripes);
380 static void stripe_io_hints(struct dm_target *ti,
381 struct queue_limits *limits)
383 struct stripe_c *sc = ti->private;
384 unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
386 blk_limits_io_min(limits, chunk_size);
387 blk_limits_io_opt(limits, chunk_size * sc->stripes);
390 static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
391 struct bio_vec *biovec, int max_size)
393 struct stripe_c *sc = ti->private;
394 sector_t bvm_sector = bvm->bi_sector;
396 struct request_queue *q;
398 stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
400 q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
401 if (!q->merge_bvec_fn)
404 bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
405 bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
407 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
410 static struct target_type stripe_target = {
412 .version = {1, 5, 0},
413 .module = THIS_MODULE,
417 .end_io = stripe_end_io,
418 .status = stripe_status,
419 .iterate_devices = stripe_iterate_devices,
420 .io_hints = stripe_io_hints,
421 .merge = stripe_merge,
424 int __init dm_stripe_init(void)
428 r = dm_register_target(&stripe_target);
430 DMWARN("target registration failed");
437 void dm_stripe_exit(void)
439 dm_unregister_target(&stripe_target);