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], start, sc->stripe_width,
84 dm_table_get_mode(ti->table),
85 &sc->stripe[stripe].dev))
88 sc->stripe[stripe].physical_start = start;
94 * Construct a striped mapping.
95 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
97 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
108 ti->error = "Not enough arguments";
112 stripes = simple_strtoul(argv[0], &end, 10);
114 ti->error = "Invalid stripe count";
118 chunk_size = simple_strtoul(argv[1], &end, 10);
120 ti->error = "Invalid chunk_size";
125 * chunk_size is a power of two
127 if (!is_power_of_2(chunk_size) ||
128 (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
129 ti->error = "Invalid chunk size";
133 if (ti->len & (chunk_size - 1)) {
134 ti->error = "Target length not divisible by "
140 if (sector_div(width, stripes)) {
141 ti->error = "Target length not divisible by "
147 * Do we have enough arguments for that many stripes ?
149 if (argc != (2 + 2 * stripes)) {
150 ti->error = "Not enough destinations "
155 sc = alloc_context(stripes);
157 ti->error = "Memory allocation for striped context "
162 INIT_WORK(&sc->kstriped_ws, trigger_event);
164 /* Set pointer to dm target; used in trigger_event */
167 sc->stripes = stripes;
168 sc->stripe_width = width;
169 ti->split_io = chunk_size;
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;
215 sector_t offset = bio->bi_sector - ti->begin;
216 sector_t chunk = offset >> sc->chunk_shift;
217 uint32_t stripe = sector_div(chunk, sc->stripes);
219 bio->bi_bdev = sc->stripe[stripe].dev->bdev;
220 bio->bi_sector = sc->stripe[stripe].physical_start +
221 (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
222 return DM_MAPIO_REMAPPED;
229 * #stripes [stripe_name <stripe_name>] [group word count]
230 * [error count 'A|D' <error count 'A|D'>]
233 * #stripes [stripe chunk size]
234 * [stripe_name physical_start <stripe_name physical_start>]
238 static int stripe_status(struct dm_target *ti,
239 status_type_t type, char *result, unsigned int maxlen)
241 struct stripe_c *sc = (struct stripe_c *) ti->private;
242 char buffer[sc->stripes + 1];
247 case STATUSTYPE_INFO:
248 DMEMIT("%d ", sc->stripes);
249 for (i = 0; i < sc->stripes; i++) {
250 DMEMIT("%s ", sc->stripe[i].dev->name);
251 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
255 DMEMIT("1 %s", buffer);
258 case STATUSTYPE_TABLE:
259 DMEMIT("%d %llu", sc->stripes,
260 (unsigned long long)sc->chunk_mask + 1);
261 for (i = 0; i < sc->stripes; i++)
262 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
263 (unsigned long long)sc->stripe[i].physical_start);
269 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
270 int error, union map_info *map_context)
273 char major_minor[16];
274 struct stripe_c *sc = ti->private;
277 return 0; /* I/O complete */
279 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
282 if (error == -EOPNOTSUPP)
285 memset(major_minor, 0, sizeof(major_minor));
286 sprintf(major_minor, "%d:%d",
287 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
288 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
291 * Test to see which stripe drive triggered the event
292 * and increment error count for all stripes on that device.
293 * If the error count for a given device exceeds the threshold
294 * value we will no longer trigger any further events.
296 for (i = 0; i < sc->stripes; i++)
297 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
298 atomic_inc(&(sc->stripe[i].error_count));
299 if (atomic_read(&(sc->stripe[i].error_count)) <
300 DM_IO_ERROR_THRESHOLD)
301 queue_work(kstriped, &sc->kstriped_ws);
307 static struct target_type stripe_target = {
309 .version = {1, 1, 0},
310 .module = THIS_MODULE,
314 .end_io = stripe_end_io,
315 .status = stripe_status,
318 int __init dm_stripe_init(void)
322 r = dm_register_target(&stripe_target);
324 DMWARN("target registration failed");
326 kstriped = create_singlethread_workqueue("kstriped");
328 DMERR("failed to create workqueue kstriped");
329 dm_unregister_target(&stripe_target);
336 void dm_stripe_exit(void)
338 if (dm_unregister_target(&stripe_target))
339 DMWARN("target unregistration failed");
341 destroy_workqueue(kstriped);