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 kstriped_ws;
44 struct stripe stripe[0];
47 static struct workqueue_struct *kstriped;
50 * An event is triggered whenever a drive
51 * drops out of a stripe volume.
53 static void trigger_event(struct work_struct *work)
55 struct stripe_c *sc = container_of(work, struct stripe_c, kstriped_ws);
57 dm_table_event(sc->ti->table);
61 static inline struct stripe_c *alloc_context(unsigned int stripes)
65 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
69 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
71 return kmalloc(len, GFP_KERNEL);
75 * Parse a single <dev> <sector> pair
77 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
78 unsigned int stripe, char **argv)
80 unsigned long long start;
82 if (sscanf(argv[1], "%llu", &start) != 1)
85 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
86 &sc->stripe[stripe].dev))
89 sc->stripe[stripe].physical_start = start;
95 * Construct a striped mapping.
96 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
98 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
109 ti->error = "Not enough arguments";
113 stripes = simple_strtoul(argv[0], &end, 10);
114 if (!stripes || *end) {
115 ti->error = "Invalid stripe count";
119 chunk_size = simple_strtoul(argv[1], &end, 10);
121 ti->error = "Invalid chunk_size";
126 * chunk_size is a power of two
128 if (!is_power_of_2(chunk_size) ||
129 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
130 ti->error = "Invalid chunk size";
134 if (ti->len & (chunk_size - 1)) {
135 ti->error = "Target length not divisible by "
141 if (sector_div(width, stripes)) {
142 ti->error = "Target length not divisible by "
148 * Do we have enough arguments for that many stripes ?
150 if (argc != (2 + 2 * stripes)) {
151 ti->error = "Not enough destinations "
156 sc = alloc_context(stripes);
158 ti->error = "Memory allocation for striped context "
163 INIT_WORK(&sc->kstriped_ws, trigger_event);
165 /* Set pointer to dm target; used in trigger_event */
167 sc->stripes = stripes;
168 sc->stripe_width = width;
170 if (stripes & (stripes - 1))
171 sc->stripes_shift = -1;
173 sc->stripes_shift = ffs(stripes) - 1;
174 sc->stripes_mask = ((sector_t) stripes) - 1;
177 ti->split_io = chunk_size;
178 ti->num_flush_requests = stripes;
180 sc->chunk_shift = ffs(chunk_size) - 1;
181 sc->chunk_mask = ((sector_t) chunk_size) - 1;
184 * Get the stripe destinations.
186 for (i = 0; i < stripes; i++) {
189 r = get_stripe(ti, sc, i, argv);
191 ti->error = "Couldn't parse stripe destination";
193 dm_put_device(ti, sc->stripe[i].dev);
197 atomic_set(&(sc->stripe[i].error_count), 0);
205 static void stripe_dtr(struct dm_target *ti)
208 struct stripe_c *sc = (struct stripe_c *) ti->private;
210 for (i = 0; i < sc->stripes; i++)
211 dm_put_device(ti, sc->stripe[i].dev);
213 flush_workqueue(kstriped);
217 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
218 uint32_t *stripe, sector_t *result)
220 sector_t offset = dm_target_offset(sc->ti, sector);
221 sector_t chunk = offset >> sc->chunk_shift;
223 if (sc->stripes_shift < 0)
224 *stripe = sector_div(chunk, sc->stripes);
226 *stripe = chunk & sc->stripes_mask;
227 chunk >>= sc->stripes_shift;
230 *result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
233 static int stripe_map(struct dm_target *ti, struct bio *bio,
234 union map_info *map_context)
236 struct stripe_c *sc = ti->private;
238 unsigned target_request_nr;
240 if (unlikely(bio_empty_barrier(bio))) {
241 target_request_nr = map_context->target_request_nr;
242 BUG_ON(target_request_nr >= sc->stripes);
243 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
244 return DM_MAPIO_REMAPPED;
247 stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
249 bio->bi_sector += sc->stripe[stripe].physical_start;
250 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
252 return DM_MAPIO_REMAPPED;
259 * #stripes [stripe_name <stripe_name>] [group word count]
260 * [error count 'A|D' <error count 'A|D'>]
263 * #stripes [stripe chunk size]
264 * [stripe_name physical_start <stripe_name physical_start>]
268 static int stripe_status(struct dm_target *ti,
269 status_type_t type, char *result, unsigned int maxlen)
271 struct stripe_c *sc = (struct stripe_c *) ti->private;
272 char buffer[sc->stripes + 1];
277 case STATUSTYPE_INFO:
278 DMEMIT("%d ", sc->stripes);
279 for (i = 0; i < sc->stripes; i++) {
280 DMEMIT("%s ", sc->stripe[i].dev->name);
281 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
285 DMEMIT("1 %s", buffer);
288 case STATUSTYPE_TABLE:
289 DMEMIT("%d %llu", sc->stripes,
290 (unsigned long long)sc->chunk_mask + 1);
291 for (i = 0; i < sc->stripes; i++)
292 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
293 (unsigned long long)sc->stripe[i].physical_start);
299 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
300 int error, union map_info *map_context)
303 char major_minor[16];
304 struct stripe_c *sc = ti->private;
307 return 0; /* I/O complete */
309 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
312 if (error == -EOPNOTSUPP)
315 memset(major_minor, 0, sizeof(major_minor));
316 sprintf(major_minor, "%d:%d",
317 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
318 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
321 * Test to see which stripe drive triggered the event
322 * and increment error count for all stripes on that device.
323 * If the error count for a given device exceeds the threshold
324 * value we will no longer trigger any further events.
326 for (i = 0; i < sc->stripes; i++)
327 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
328 atomic_inc(&(sc->stripe[i].error_count));
329 if (atomic_read(&(sc->stripe[i].error_count)) <
330 DM_IO_ERROR_THRESHOLD)
331 queue_work(kstriped, &sc->kstriped_ws);
337 static int stripe_iterate_devices(struct dm_target *ti,
338 iterate_devices_callout_fn fn, void *data)
340 struct stripe_c *sc = ti->private;
345 ret = fn(ti, sc->stripe[i].dev,
346 sc->stripe[i].physical_start,
347 sc->stripe_width, data);
348 } while (!ret && ++i < sc->stripes);
353 static void stripe_io_hints(struct dm_target *ti,
354 struct queue_limits *limits)
356 struct stripe_c *sc = ti->private;
357 unsigned chunk_size = (sc->chunk_mask + 1) << 9;
359 blk_limits_io_min(limits, chunk_size);
360 blk_limits_io_opt(limits, chunk_size * sc->stripes);
363 static struct target_type stripe_target = {
365 .version = {1, 3, 0},
366 .module = THIS_MODULE,
370 .end_io = stripe_end_io,
371 .status = stripe_status,
372 .iterate_devices = stripe_iterate_devices,
373 .io_hints = stripe_io_hints,
376 int __init dm_stripe_init(void)
380 r = dm_register_target(&stripe_target);
382 DMWARN("target registration failed");
386 kstriped = create_singlethread_workqueue("kstriped");
388 DMERR("failed to create workqueue kstriped");
389 dm_unregister_target(&stripe_target);
396 void dm_stripe_exit(void)
398 dm_unregister_target(&stripe_target);
399 destroy_workqueue(kstriped);