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/drivers/md/dm-stripe.c

http://github.com/mirrors/linux
C | 528 lines | 394 code | 88 blank | 46 comment | 55 complexity | aba651136abb1b3738669e196629dc87 MD5 | raw file
  1/*
  2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
  3 *
  4 * This file is released under the GPL.
  5 */
  6
  7#include "dm.h"
  8#include <linux/device-mapper.h>
  9
 10#include <linux/module.h>
 11#include <linux/init.h>
 12#include <linux/blkdev.h>
 13#include <linux/bio.h>
 14#include <linux/dax.h>
 15#include <linux/slab.h>
 16#include <linux/log2.h>
 17
 18#define DM_MSG_PREFIX "striped"
 19#define DM_IO_ERROR_THRESHOLD 15
 20
 21struct stripe {
 22	struct dm_dev *dev;
 23	sector_t physical_start;
 24
 25	atomic_t error_count;
 26};
 27
 28struct stripe_c {
 29	uint32_t stripes;
 30	int stripes_shift;
 31
 32	/* The size of this target / num. stripes */
 33	sector_t stripe_width;
 34
 35	uint32_t chunk_size;
 36	int chunk_size_shift;
 37
 38	/* Needed for handling events */
 39	struct dm_target *ti;
 40
 41	/* Work struct used for triggering events*/
 42	struct work_struct trigger_event;
 43
 44	struct stripe stripe[0];
 45};
 46
 47/*
 48 * An event is triggered whenever a drive
 49 * drops out of a stripe volume.
 50 */
 51static void trigger_event(struct work_struct *work)
 52{
 53	struct stripe_c *sc = container_of(work, struct stripe_c,
 54					   trigger_event);
 55	dm_table_event(sc->ti->table);
 56}
 57
 58/*
 59 * Parse a single <dev> <sector> pair
 60 */
 61static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
 62		      unsigned int stripe, char **argv)
 63{
 64	unsigned long long start;
 65	char dummy;
 66	int ret;
 67
 68	if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
 69		return -EINVAL;
 70
 71	ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
 72			    &sc->stripe[stripe].dev);
 73	if (ret)
 74		return ret;
 75
 76	sc->stripe[stripe].physical_start = start;
 77
 78	return 0;
 79}
 80
 81/*
 82 * Construct a striped mapping.
 83 * <number of stripes> <chunk size> [<dev_path> <offset>]+
 84 */
 85static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 86{
 87	struct stripe_c *sc;
 88	sector_t width, tmp_len;
 89	uint32_t stripes;
 90	uint32_t chunk_size;
 91	int r;
 92	unsigned int i;
 93
 94	if (argc < 2) {
 95		ti->error = "Not enough arguments";
 96		return -EINVAL;
 97	}
 98
 99	if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
100		ti->error = "Invalid stripe count";
101		return -EINVAL;
102	}
103
104	if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
105		ti->error = "Invalid chunk_size";
106		return -EINVAL;
107	}
108
109	width = ti->len;
110	if (sector_div(width, stripes)) {
111		ti->error = "Target length not divisible by "
112		    "number of stripes";
113		return -EINVAL;
114	}
115
116	tmp_len = width;
117	if (sector_div(tmp_len, chunk_size)) {
118		ti->error = "Target length not divisible by "
119		    "chunk size";
120		return -EINVAL;
121	}
122
123	/*
124	 * Do we have enough arguments for that many stripes ?
125	 */
126	if (argc != (2 + 2 * stripes)) {
127		ti->error = "Not enough destinations "
128			"specified";
129		return -EINVAL;
130	}
131
132	sc = kmalloc(struct_size(sc, stripe, stripes), GFP_KERNEL);
133	if (!sc) {
134		ti->error = "Memory allocation for striped context "
135		    "failed";
136		return -ENOMEM;
137	}
138
139	INIT_WORK(&sc->trigger_event, trigger_event);
140
141	/* Set pointer to dm target; used in trigger_event */
142	sc->ti = ti;
143	sc->stripes = stripes;
144	sc->stripe_width = width;
145
146	if (stripes & (stripes - 1))
147		sc->stripes_shift = -1;
148	else
149		sc->stripes_shift = __ffs(stripes);
150
151	r = dm_set_target_max_io_len(ti, chunk_size);
152	if (r) {
153		kfree(sc);
154		return r;
155	}
156
157	ti->num_flush_bios = stripes;
158	ti->num_discard_bios = stripes;
159	ti->num_secure_erase_bios = stripes;
160	ti->num_write_same_bios = stripes;
161	ti->num_write_zeroes_bios = stripes;
162
163	sc->chunk_size = chunk_size;
164	if (chunk_size & (chunk_size - 1))
165		sc->chunk_size_shift = -1;
166	else
167		sc->chunk_size_shift = __ffs(chunk_size);
168
169	/*
170	 * Get the stripe destinations.
171	 */
172	for (i = 0; i < stripes; i++) {
173		argv += 2;
174
175		r = get_stripe(ti, sc, i, argv);
176		if (r < 0) {
177			ti->error = "Couldn't parse stripe destination";
178			while (i--)
179				dm_put_device(ti, sc->stripe[i].dev);
180			kfree(sc);
181			return r;
182		}
183		atomic_set(&(sc->stripe[i].error_count), 0);
184	}
185
186	ti->private = sc;
187
188	return 0;
189}
190
191static void stripe_dtr(struct dm_target *ti)
192{
193	unsigned int i;
194	struct stripe_c *sc = (struct stripe_c *) ti->private;
195
196	for (i = 0; i < sc->stripes; i++)
197		dm_put_device(ti, sc->stripe[i].dev);
198
199	flush_work(&sc->trigger_event);
200	kfree(sc);
201}
202
203static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
204			      uint32_t *stripe, sector_t *result)
205{
206	sector_t chunk = dm_target_offset(sc->ti, sector);
207	sector_t chunk_offset;
208
209	if (sc->chunk_size_shift < 0)
210		chunk_offset = sector_div(chunk, sc->chunk_size);
211	else {
212		chunk_offset = chunk & (sc->chunk_size - 1);
213		chunk >>= sc->chunk_size_shift;
214	}
215
216	if (sc->stripes_shift < 0)
217		*stripe = sector_div(chunk, sc->stripes);
218	else {
219		*stripe = chunk & (sc->stripes - 1);
220		chunk >>= sc->stripes_shift;
221	}
222
223	if (sc->chunk_size_shift < 0)
224		chunk *= sc->chunk_size;
225	else
226		chunk <<= sc->chunk_size_shift;
227
228	*result = chunk + chunk_offset;
229}
230
231static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
232				    uint32_t target_stripe, sector_t *result)
233{
234	uint32_t stripe;
235
236	stripe_map_sector(sc, sector, &stripe, result);
237	if (stripe == target_stripe)
238		return;
239
240	/* round down */
241	sector = *result;
242	if (sc->chunk_size_shift < 0)
243		*result -= sector_div(sector, sc->chunk_size);
244	else
245		*result = sector & ~(sector_t)(sc->chunk_size - 1);
246
247	if (target_stripe < stripe)
248		*result += sc->chunk_size;		/* next chunk */
249}
250
251static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
252			    uint32_t target_stripe)
253{
254	sector_t begin, end;
255
256	stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
257				target_stripe, &begin);
258	stripe_map_range_sector(sc, bio_end_sector(bio),
259				target_stripe, &end);
260	if (begin < end) {
261		bio_set_dev(bio, sc->stripe[target_stripe].dev->bdev);
262		bio->bi_iter.bi_sector = begin +
263			sc->stripe[target_stripe].physical_start;
264		bio->bi_iter.bi_size = to_bytes(end - begin);
265		return DM_MAPIO_REMAPPED;
266	} else {
267		/* The range doesn't map to the target stripe */
268		bio_endio(bio);
269		return DM_MAPIO_SUBMITTED;
270	}
271}
272
273static int stripe_map(struct dm_target *ti, struct bio *bio)
274{
275	struct stripe_c *sc = ti->private;
276	uint32_t stripe;
277	unsigned target_bio_nr;
278
279	if (bio->bi_opf & REQ_PREFLUSH) {
280		target_bio_nr = dm_bio_get_target_bio_nr(bio);
281		BUG_ON(target_bio_nr >= sc->stripes);
282		bio_set_dev(bio, sc->stripe[target_bio_nr].dev->bdev);
283		return DM_MAPIO_REMAPPED;
284	}
285	if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
286	    unlikely(bio_op(bio) == REQ_OP_SECURE_ERASE) ||
287	    unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) ||
288	    unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
289		target_bio_nr = dm_bio_get_target_bio_nr(bio);
290		BUG_ON(target_bio_nr >= sc->stripes);
291		return stripe_map_range(sc, bio, target_bio_nr);
292	}
293
294	stripe_map_sector(sc, bio->bi_iter.bi_sector,
295			  &stripe, &bio->bi_iter.bi_sector);
296
297	bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
298	bio_set_dev(bio, sc->stripe[stripe].dev->bdev);
299
300	return DM_MAPIO_REMAPPED;
301}
302
303#if IS_ENABLED(CONFIG_DAX_DRIVER)
304static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
305		long nr_pages, void **kaddr, pfn_t *pfn)
306{
307	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
308	struct stripe_c *sc = ti->private;
309	struct dax_device *dax_dev;
310	struct block_device *bdev;
311	uint32_t stripe;
312	long ret;
313
314	stripe_map_sector(sc, sector, &stripe, &dev_sector);
315	dev_sector += sc->stripe[stripe].physical_start;
316	dax_dev = sc->stripe[stripe].dev->dax_dev;
317	bdev = sc->stripe[stripe].dev->bdev;
318
319	ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
320	if (ret)
321		return ret;
322	return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
323}
324
325static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
326		void *addr, size_t bytes, struct iov_iter *i)
327{
328	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
329	struct stripe_c *sc = ti->private;
330	struct dax_device *dax_dev;
331	struct block_device *bdev;
332	uint32_t stripe;
333
334	stripe_map_sector(sc, sector, &stripe, &dev_sector);
335	dev_sector += sc->stripe[stripe].physical_start;
336	dax_dev = sc->stripe[stripe].dev->dax_dev;
337	bdev = sc->stripe[stripe].dev->bdev;
338
339	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
340		return 0;
341	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
342}
343
344static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
345		void *addr, size_t bytes, struct iov_iter *i)
346{
347	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
348	struct stripe_c *sc = ti->private;
349	struct dax_device *dax_dev;
350	struct block_device *bdev;
351	uint32_t stripe;
352
353	stripe_map_sector(sc, sector, &stripe, &dev_sector);
354	dev_sector += sc->stripe[stripe].physical_start;
355	dax_dev = sc->stripe[stripe].dev->dax_dev;
356	bdev = sc->stripe[stripe].dev->bdev;
357
358	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
359		return 0;
360	return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
361}
362
363static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
364				      size_t nr_pages)
365{
366	int ret;
367	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
368	struct stripe_c *sc = ti->private;
369	struct dax_device *dax_dev;
370	struct block_device *bdev;
371	uint32_t stripe;
372
373	stripe_map_sector(sc, sector, &stripe, &dev_sector);
374	dev_sector += sc->stripe[stripe].physical_start;
375	dax_dev = sc->stripe[stripe].dev->dax_dev;
376	bdev = sc->stripe[stripe].dev->bdev;
377
378	ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
379	if (ret)
380		return ret;
381	return dax_zero_page_range(dax_dev, pgoff, nr_pages);
382}
383
384#else
385#define stripe_dax_direct_access NULL
386#define stripe_dax_copy_from_iter NULL
387#define stripe_dax_copy_to_iter NULL
388#define stripe_dax_zero_page_range NULL
389#endif
390
391/*
392 * Stripe status:
393 *
394 * INFO
395 * #stripes [stripe_name <stripe_name>] [group word count]
396 * [error count 'A|D' <error count 'A|D'>]
397 *
398 * TABLE
399 * #stripes [stripe chunk size]
400 * [stripe_name physical_start <stripe_name physical_start>]
401 *
402 */
403
404static void stripe_status(struct dm_target *ti, status_type_t type,
405			  unsigned status_flags, char *result, unsigned maxlen)
406{
407	struct stripe_c *sc = (struct stripe_c *) ti->private;
408	unsigned int sz = 0;
409	unsigned int i;
410
411	switch (type) {
412	case STATUSTYPE_INFO:
413		DMEMIT("%d ", sc->stripes);
414		for (i = 0; i < sc->stripes; i++)  {
415			DMEMIT("%s ", sc->stripe[i].dev->name);
416		}
417		DMEMIT("1 ");
418		for (i = 0; i < sc->stripes; i++) {
419			DMEMIT("%c", atomic_read(&(sc->stripe[i].error_count)) ?
420			       'D' : 'A');
421		}
422		break;
423
424	case STATUSTYPE_TABLE:
425		DMEMIT("%d %llu", sc->stripes,
426			(unsigned long long)sc->chunk_size);
427		for (i = 0; i < sc->stripes; i++)
428			DMEMIT(" %s %llu", sc->stripe[i].dev->name,
429			    (unsigned long long)sc->stripe[i].physical_start);
430		break;
431	}
432}
433
434static int stripe_end_io(struct dm_target *ti, struct bio *bio,
435		blk_status_t *error)
436{
437	unsigned i;
438	char major_minor[16];
439	struct stripe_c *sc = ti->private;
440
441	if (!*error)
442		return DM_ENDIO_DONE; /* I/O complete */
443
444	if (bio->bi_opf & REQ_RAHEAD)
445		return DM_ENDIO_DONE;
446
447	if (*error == BLK_STS_NOTSUPP)
448		return DM_ENDIO_DONE;
449
450	memset(major_minor, 0, sizeof(major_minor));
451	sprintf(major_minor, "%d:%d", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)));
452
453	/*
454	 * Test to see which stripe drive triggered the event
455	 * and increment error count for all stripes on that device.
456	 * If the error count for a given device exceeds the threshold
457	 * value we will no longer trigger any further events.
458	 */
459	for (i = 0; i < sc->stripes; i++)
460		if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
461			atomic_inc(&(sc->stripe[i].error_count));
462			if (atomic_read(&(sc->stripe[i].error_count)) <
463			    DM_IO_ERROR_THRESHOLD)
464				schedule_work(&sc->trigger_event);
465		}
466
467	return DM_ENDIO_DONE;
468}
469
470static int stripe_iterate_devices(struct dm_target *ti,
471				  iterate_devices_callout_fn fn, void *data)
472{
473	struct stripe_c *sc = ti->private;
474	int ret = 0;
475	unsigned i = 0;
476
477	do {
478		ret = fn(ti, sc->stripe[i].dev,
479			 sc->stripe[i].physical_start,
480			 sc->stripe_width, data);
481	} while (!ret && ++i < sc->stripes);
482
483	return ret;
484}
485
486static void stripe_io_hints(struct dm_target *ti,
487			    struct queue_limits *limits)
488{
489	struct stripe_c *sc = ti->private;
490	unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
491
492	blk_limits_io_min(limits, chunk_size);
493	blk_limits_io_opt(limits, chunk_size * sc->stripes);
494}
495
496static struct target_type stripe_target = {
497	.name   = "striped",
498	.version = {1, 6, 0},
499	.features = DM_TARGET_PASSES_INTEGRITY,
500	.module = THIS_MODULE,
501	.ctr    = stripe_ctr,
502	.dtr    = stripe_dtr,
503	.map    = stripe_map,
504	.end_io = stripe_end_io,
505	.status = stripe_status,
506	.iterate_devices = stripe_iterate_devices,
507	.io_hints = stripe_io_hints,
508	.direct_access = stripe_dax_direct_access,
509	.dax_copy_from_iter = stripe_dax_copy_from_iter,
510	.dax_copy_to_iter = stripe_dax_copy_to_iter,
511	.dax_zero_page_range = stripe_dax_zero_page_range,
512};
513
514int __init dm_stripe_init(void)
515{
516	int r;
517
518	r = dm_register_target(&stripe_target);
519	if (r < 0)
520		DMWARN("target registration failed");
521
522	return r;
523}
524
525void dm_stripe_exit(void)
526{
527	dm_unregister_target(&stripe_target);
528}