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 int stripe_map(struct dm_target *ti, struct bio *bio,
211 union map_info *map_context)
213 struct stripe_c *sc = (struct stripe_c *) ti->private;
214 sector_t offset, chunk;
216 unsigned target_request_nr;
218 if (unlikely(bio_empty_barrier(bio))) {
219 target_request_nr = map_context->target_request_nr;
220 BUG_ON(target_request_nr >= sc->stripes);
221 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
222 return DM_MAPIO_REMAPPED;
225 offset = bio->bi_sector - ti->begin;
226 chunk = offset >> sc->chunk_shift;
227 stripe = sector_div(chunk, sc->stripes);
229 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
230 bio->bi_sector = sc->stripe[stripe].physical_start +
231 (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
232 return DM_MAPIO_REMAPPED;
239 * #stripes [stripe_name <stripe_name>] [group word count]
240 * [error count 'A|D' <error count 'A|D'>]
243 * #stripes [stripe chunk size]
244 * [stripe_name physical_start <stripe_name physical_start>]
248 static int stripe_status(struct dm_target *ti,
249 status_type_t type, char *result, unsigned int maxlen)
251 struct stripe_c *sc = (struct stripe_c *) ti->private;
252 char buffer[sc->stripes + 1];
257 case STATUSTYPE_INFO:
258 DMEMIT("%d ", sc->stripes);
259 for (i = 0; i < sc->stripes; i++) {
260 DMEMIT("%s ", sc->stripe[i].dev->name);
261 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
265 DMEMIT("1 %s", buffer);
268 case STATUSTYPE_TABLE:
269 DMEMIT("%d %llu", sc->stripes,
270 (unsigned long long)sc->chunk_mask + 1);
271 for (i = 0; i < sc->stripes; i++)
272 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
273 (unsigned long long)sc->stripe[i].physical_start);
279 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
280 int error, union map_info *map_context)
283 char major_minor[16];
284 struct stripe_c *sc = ti->private;
287 return 0; /* I/O complete */
289 if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
292 if (error == -EOPNOTSUPP)
295 memset(major_minor, 0, sizeof(major_minor));
296 sprintf(major_minor, "%d:%d",
297 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
298 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
301 * Test to see which stripe drive triggered the event
302 * and increment error count for all stripes on that device.
303 * If the error count for a given device exceeds the threshold
304 * value we will no longer trigger any further events.
306 for (i = 0; i < sc->stripes; i++)
307 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
308 atomic_inc(&(sc->stripe[i].error_count));
309 if (atomic_read(&(sc->stripe[i].error_count)) <
310 DM_IO_ERROR_THRESHOLD)
311 queue_work(kstriped, &sc->kstriped_ws);
317 static int stripe_iterate_devices(struct dm_target *ti,
318 iterate_devices_callout_fn fn, void *data)
320 struct stripe_c *sc = ti->private;
325 ret = fn(ti, sc->stripe[i].dev,
326 sc->stripe[i].physical_start,
327 sc->stripe_width, data);
328 } while (!ret && ++i < sc->stripes);
333 static void stripe_io_hints(struct dm_target *ti,
334 struct queue_limits *limits)
336 struct stripe_c *sc = ti->private;
337 unsigned chunk_size = (sc->chunk_mask + 1) << 9;
339 blk_limits_io_min(limits, chunk_size);
340 blk_limits_io_opt(limits, chunk_size * sc->stripes);
343 static struct target_type stripe_target = {
345 .version = {1, 3, 0},
346 .module = THIS_MODULE,
350 .end_io = stripe_end_io,
351 .status = stripe_status,
352 .iterate_devices = stripe_iterate_devices,
353 .io_hints = stripe_io_hints,
356 int __init dm_stripe_init(void)
360 r = dm_register_target(&stripe_target);
362 DMWARN("target registration failed");
366 kstriped = create_singlethread_workqueue("kstriped");
368 DMERR("failed to create workqueue kstriped");
369 dm_unregister_target(&stripe_target);
376 void dm_stripe_exit(void)
378 dm_unregister_target(&stripe_target);
379 destroy_workqueue(kstriped);