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 /* The size of this target / num. stripes */
30 sector_t stripe_width;
32 /* stripe chunk size */
36 /* Needed for handling events */
39 /* Work struct used for triggering events*/
40 struct work_struct kstriped_ws;
42 struct stripe stripe[0];
45 static struct workqueue_struct *kstriped;
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, kstriped_ws);
55 dm_table_event(sc->ti->table);
59 static inline struct stripe_c *alloc_context(unsigned int stripes)
63 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
67 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
69 return kmalloc(len, GFP_KERNEL);
73 * Parse a single <dev> <sector> pair
75 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
76 unsigned int stripe, char **argv)
78 unsigned long long start;
80 if (sscanf(argv[1], "%llu", &start) != 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)
107 ti->error = "Not enough arguments";
111 stripes = simple_strtoul(argv[0], &end, 10);
112 if (!stripes || *end) {
113 ti->error = "Invalid stripe count";
117 chunk_size = simple_strtoul(argv[1], &end, 10);
119 ti->error = "Invalid chunk_size";
124 * chunk_size is a power of two
126 if (!is_power_of_2(chunk_size) ||
127 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
128 ti->error = "Invalid chunk size";
132 if (ti->len & (chunk_size - 1)) {
133 ti->error = "Target length not divisible by "
139 if (sector_div(width, stripes)) {
140 ti->error = "Target length not divisible by "
146 * Do we have enough arguments for that many stripes ?
148 if (argc != (2 + 2 * stripes)) {
149 ti->error = "Not enough destinations "
154 sc = alloc_context(stripes);
156 ti->error = "Memory allocation for striped context "
161 INIT_WORK(&sc->kstriped_ws, trigger_event);
163 /* Set pointer to dm target; used in trigger_event */
166 sc->stripes = stripes;
167 sc->stripe_width = width;
168 ti->split_io = chunk_size;
169 ti->num_flush_requests = stripes;
171 sc->chunk_mask = ((sector_t) chunk_size) - 1;
172 for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
177 * Get the stripe destinations.
179 for (i = 0; i < stripes; i++) {
182 r = get_stripe(ti, sc, i, argv);
184 ti->error = "Couldn't parse stripe destination";
186 dm_put_device(ti, sc->stripe[i].dev);
190 atomic_set(&(sc->stripe[i].error_count), 0);
198 static void stripe_dtr(struct dm_target *ti)
201 struct stripe_c *sc = (struct stripe_c *) ti->private;
203 for (i = 0; i < sc->stripes; i++)
204 dm_put_device(ti, sc->stripe[i].dev);
206 flush_workqueue(kstriped);
210 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
211 uint32_t *stripe, sector_t *result)
213 sector_t offset = dm_target_offset(sc->ti, sector);
214 sector_t chunk = offset >> sc->chunk_shift;
216 *stripe = sector_div(chunk, sc->stripes);
217 *result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
220 static int stripe_map(struct dm_target *ti, struct bio *bio,
221 union map_info *map_context)
223 struct stripe_c *sc = ti->private;
225 unsigned target_request_nr;
227 if (unlikely(bio_empty_barrier(bio))) {
228 target_request_nr = map_context->target_request_nr;
229 BUG_ON(target_request_nr >= sc->stripes);
230 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
231 return DM_MAPIO_REMAPPED;
234 stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
236 bio->bi_sector += sc->stripe[stripe].physical_start;
237 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
239 return DM_MAPIO_REMAPPED;
246 * #stripes [stripe_name <stripe_name>] [group word count]
247 * [error count 'A|D' <error count 'A|D'>]
250 * #stripes [stripe chunk size]
251 * [stripe_name physical_start <stripe_name physical_start>]
255 static int stripe_status(struct dm_target *ti,
256 status_type_t type, char *result, unsigned int maxlen)
258 struct stripe_c *sc = (struct stripe_c *) ti->private;
259 char buffer[sc->stripes + 1];
264 case STATUSTYPE_INFO:
265 DMEMIT("%d ", sc->stripes);
266 for (i = 0; i < sc->stripes; i++) {
267 DMEMIT("%s ", sc->stripe[i].dev->name);
268 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
272 DMEMIT("1 %s", buffer);
275 case STATUSTYPE_TABLE:
276 DMEMIT("%d %llu", sc->stripes,
277 (unsigned long long)sc->chunk_mask + 1);
278 for (i = 0; i < sc->stripes; i++)
279 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
280 (unsigned long long)sc->stripe[i].physical_start);
286 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
287 int error, union map_info *map_context)
290 char major_minor[16];
291 struct stripe_c *sc = ti->private;
294 return 0; /* I/O complete */
296 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
299 if (error == -EOPNOTSUPP)
302 memset(major_minor, 0, sizeof(major_minor));
303 sprintf(major_minor, "%d:%d",
304 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
305 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
308 * Test to see which stripe drive triggered the event
309 * and increment error count for all stripes on that device.
310 * If the error count for a given device exceeds the threshold
311 * value we will no longer trigger any further events.
313 for (i = 0; i < sc->stripes; i++)
314 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
315 atomic_inc(&(sc->stripe[i].error_count));
316 if (atomic_read(&(sc->stripe[i].error_count)) <
317 DM_IO_ERROR_THRESHOLD)
318 queue_work(kstriped, &sc->kstriped_ws);
324 static int stripe_iterate_devices(struct dm_target *ti,
325 iterate_devices_callout_fn fn, void *data)
327 struct stripe_c *sc = ti->private;
332 ret = fn(ti, sc->stripe[i].dev,
333 sc->stripe[i].physical_start,
334 sc->stripe_width, data);
335 } while (!ret && ++i < sc->stripes);
340 static void stripe_io_hints(struct dm_target *ti,
341 struct queue_limits *limits)
343 struct stripe_c *sc = ti->private;
344 unsigned chunk_size = (sc->chunk_mask + 1) << 9;
346 blk_limits_io_min(limits, chunk_size);
347 blk_limits_io_opt(limits, chunk_size * sc->stripes);
350 static struct target_type stripe_target = {
352 .version = {1, 3, 0},
353 .module = THIS_MODULE,
357 .end_io = stripe_end_io,
358 .status = stripe_status,
359 .iterate_devices = stripe_iterate_devices,
360 .io_hints = stripe_io_hints,
363 int __init dm_stripe_init(void)
367 r = dm_register_target(&stripe_target);
369 DMWARN("target registration failed");
373 kstriped = create_singlethread_workqueue("kstriped");
375 DMERR("failed to create workqueue kstriped");
376 dm_unregister_target(&stripe_target);
383 void dm_stripe_exit(void)
385 dm_unregister_target(&stripe_target);
386 destroy_workqueue(kstriped);