1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9#include <linux/device-mapper.h>
10
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/blkdev.h>
14#include <linux/bio.h>
15#include <linux/dax.h>
16#include <linux/slab.h>
17#include <linux/log2.h>
18
19static struct workqueue_struct *dm_stripe_wq;
20
21#define DM_MSG_PREFIX "striped"
22#define DM_IO_ERROR_THRESHOLD 15
23
24struct stripe {
25	struct dm_dev *dev;
26	sector_t physical_start;
27
28	atomic_t error_count;
29};
30
31struct stripe_c {
32	uint32_t stripes;
33	int stripes_shift;
34
35	/* The size of this target / num. stripes */
36	sector_t stripe_width;
37
38	uint32_t chunk_size;
39	int chunk_size_shift;
40
41	/* Needed for handling events */
42	struct dm_target *ti;
43
44	/* Work struct used for triggering events*/
45	struct work_struct trigger_event;
46
47	struct stripe stripe[] __counted_by(stripes);
48};
49
50/*
51 * An event is triggered whenever a drive
52 * drops out of a stripe volume.
53 */
54static void trigger_event(struct work_struct *work)
55{
56	struct stripe_c *sc = container_of(work, struct stripe_c,
57					   trigger_event);
58	dm_table_event(sc->ti->table);
59}
60
61/*
62 * Parse a single <dev> <sector> pair
63 */
64static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
65		      unsigned int stripe, char **argv)
66{
67	unsigned long long start;
68	char dummy;
69	int ret;
70
71	if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
72		return -EINVAL;
73
74	ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
75			    &sc->stripe[stripe].dev);
76	if (ret)
77		return ret;
78
79	sc->stripe[stripe].physical_start = start;
80
81	return 0;
82}
83
84/*
85 * Construct a striped mapping.
86 * <number of stripes> <chunk size> [<dev_path> <offset>]+
87 */
88static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
89{
90	struct stripe_c *sc;
91	sector_t width, tmp_len;
92	uint32_t stripes;
93	uint32_t chunk_size;
94	int r;
95	unsigned int i;
96
97	if (argc < 2) {
98		ti->error = "Not enough arguments";
99		return -EINVAL;
100	}
101
102	if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
103		ti->error = "Invalid stripe count";
104		return -EINVAL;
105	}
106
107	if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
108		ti->error = "Invalid chunk_size";
109		return -EINVAL;
110	}
111
112	width = ti->len;
113	if (sector_div(width, stripes)) {
114		ti->error = "Target length not divisible by number of stripes";
115		return -EINVAL;
116	}
117
118	tmp_len = width;
119	if (sector_div(tmp_len, chunk_size)) {
120		ti->error = "Target length not divisible by chunk size";
121		return -EINVAL;
122	}
123
124	/*
125	 * Do we have enough arguments for that many stripes ?
126	 */
127	if (argc != (2 + 2 * stripes)) {
128		ti->error = "Not enough destinations 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 failed";
135		return -ENOMEM;
136	}
137
138	INIT_WORK(&sc->trigger_event, trigger_event);
139
140	/* Set pointer to dm target; used in trigger_event */
141	sc->ti = ti;
142	sc->stripes = stripes;
143	sc->stripe_width = width;
144
145	if (stripes & (stripes - 1))
146		sc->stripes_shift = -1;
147	else
148		sc->stripes_shift = __ffs(stripes);
149
150	r = dm_set_target_max_io_len(ti, chunk_size);
151	if (r) {
152		kfree(sc);
153		return r;
154	}
155
156	ti->num_flush_bios = stripes;
157	ti->num_discard_bios = stripes;
158	ti->num_secure_erase_bios = stripes;
159	ti->num_write_zeroes_bios = stripes;
160
161	sc->chunk_size = chunk_size;
162	if (chunk_size & (chunk_size - 1))
163		sc->chunk_size_shift = -1;
164	else
165		sc->chunk_size_shift = __ffs(chunk_size);
166
167	/*
168	 * Get the stripe destinations.
169	 */
170	for (i = 0; i < stripes; i++) {
171		argv += 2;
172
173		r = get_stripe(ti, sc, i, argv);
174		if (r < 0) {
175			ti->error = "Couldn't parse stripe destination";
176			while (i--)
177				dm_put_device(ti, sc->stripe[i].dev);
178			kfree(sc);
179			return r;
180		}
181		atomic_set(&(sc->stripe[i].error_count), 0);
182	}
183
184	ti->private = sc;
185
186	return 0;
187}
188
189static void stripe_dtr(struct dm_target *ti)
190{
191	unsigned int i;
192	struct stripe_c *sc = ti->private;
193
194	for (i = 0; i < sc->stripes; i++)
195		dm_put_device(ti, sc->stripe[i].dev);
196
197	flush_work(&sc->trigger_event);
198	kfree(sc);
199}
200
201static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
202			      uint32_t *stripe, sector_t *result)
203{
204	sector_t chunk = dm_target_offset(sc->ti, sector);
205	sector_t chunk_offset;
206
207	if (sc->chunk_size_shift < 0)
208		chunk_offset = sector_div(chunk, sc->chunk_size);
209	else {
210		chunk_offset = chunk & (sc->chunk_size - 1);
211		chunk >>= sc->chunk_size_shift;
212	}
213
214	if (sc->stripes_shift < 0)
215		*stripe = sector_div(chunk, sc->stripes);
216	else {
217		*stripe = chunk & (sc->stripes - 1);
218		chunk >>= sc->stripes_shift;
219	}
220
221	if (sc->chunk_size_shift < 0)
222		chunk *= sc->chunk_size;
223	else
224		chunk <<= sc->chunk_size_shift;
225
226	*result = chunk + chunk_offset;
227}
228
229static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
230				    uint32_t target_stripe, sector_t *result)
231{
232	uint32_t stripe;
233
234	stripe_map_sector(sc, sector, &stripe, result);
235	if (stripe == target_stripe)
236		return;
237
238	/* round down */
239	sector = *result;
240	if (sc->chunk_size_shift < 0)
241		*result -= sector_div(sector, sc->chunk_size);
242	else
243		*result = sector & ~(sector_t)(sc->chunk_size - 1);
244
245	if (target_stripe < stripe)
246		*result += sc->chunk_size;		/* next chunk */
247}
248
249static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
250			    uint32_t target_stripe)
251{
252	sector_t begin, end;
253
254	stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
255				target_stripe, &begin);
256	stripe_map_range_sector(sc, bio_end_sector(bio),
257				target_stripe, &end);
258	if (begin < end) {
259		bio_set_dev(bio, sc->stripe[target_stripe].dev->bdev);
260		bio->bi_iter.bi_sector = begin +
261			sc->stripe[target_stripe].physical_start;
262		bio->bi_iter.bi_size = to_bytes(end - begin);
263		return DM_MAPIO_REMAPPED;
264	}
265
266	/* The range doesn't map to the target stripe */
267	bio_endio(bio);
268	return DM_MAPIO_SUBMITTED;
269}
270
271int stripe_map(struct dm_target *ti, struct bio *bio)
272{
273	struct stripe_c *sc = ti->private;
274	uint32_t stripe;
275	unsigned int target_bio_nr;
276
277	if (bio->bi_opf & REQ_PREFLUSH) {
278		target_bio_nr = dm_bio_get_target_bio_nr(bio);
279		BUG_ON(target_bio_nr >= sc->stripes);
280		bio_set_dev(bio, sc->stripe[target_bio_nr].dev->bdev);
281		return DM_MAPIO_REMAPPED;
282	}
283	if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
284	    unlikely(bio_op(bio) == REQ_OP_SECURE_ERASE) ||
285	    unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES)) {
286		target_bio_nr = dm_bio_get_target_bio_nr(bio);
287		BUG_ON(target_bio_nr >= sc->stripes);
288		return stripe_map_range(sc, bio, target_bio_nr);
289	}
290
291	stripe_map_sector(sc, bio->bi_iter.bi_sector,
292			  &stripe, &bio->bi_iter.bi_sector);
293
294	bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
295	bio_set_dev(bio, sc->stripe[stripe].dev->bdev);
296
297	return DM_MAPIO_REMAPPED;
298}
299
300#if IS_ENABLED(CONFIG_FS_DAX)
301static struct dax_device *stripe_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
302{
303	struct stripe_c *sc = ti->private;
304	struct block_device *bdev;
305	sector_t dev_sector;
306	uint32_t stripe;
307
308	stripe_map_sector(sc, *pgoff * PAGE_SECTORS, &stripe, &dev_sector);
309	dev_sector += sc->stripe[stripe].physical_start;
310	bdev = sc->stripe[stripe].dev->bdev;
311
312	*pgoff = (get_start_sect(bdev) + dev_sector) >> PAGE_SECTORS_SHIFT;
313	return sc->stripe[stripe].dev->dax_dev;
314}
315
316static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
317		long nr_pages, enum dax_access_mode mode, void **kaddr,
318		pfn_t *pfn)
319{
320	struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
321
322	return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
323}
324
325static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
326				      size_t nr_pages)
327{
328	struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
329
330	return dax_zero_page_range(dax_dev, pgoff, nr_pages);
331}
332
333static size_t stripe_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
334		void *addr, size_t bytes, struct iov_iter *i)
335{
336	struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
337
338	return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
339}
340
341#else
342#define stripe_dax_direct_access NULL
343#define stripe_dax_zero_page_range NULL
344#define stripe_dax_recovery_write NULL
345#endif
346
347/*
348 * Stripe status:
349 *
350 * INFO
351 * #stripes [stripe_name <stripe_name>] [group word count]
352 * [error count 'A|D' <error count 'A|D'>]
353 *
354 * TABLE
355 * #stripes [stripe chunk size]
356 * [stripe_name physical_start <stripe_name physical_start>]
357 *
358 */
359
360static void stripe_status(struct dm_target *ti, status_type_t type,
361			  unsigned int status_flags, char *result, unsigned int maxlen)
362{
363	struct stripe_c *sc = ti->private;
364	unsigned int sz = 0;
365	unsigned int i;
366
367	switch (type) {
368	case STATUSTYPE_INFO:
369		DMEMIT("%d ", sc->stripes);
370		for (i = 0; i < sc->stripes; i++)
371			DMEMIT("%s ", sc->stripe[i].dev->name);
372
373		DMEMIT("1 ");
374		for (i = 0; i < sc->stripes; i++)
375			DMEMIT("%c", atomic_read(&(sc->stripe[i].error_count)) ?  'D' : 'A');
376		break;
377
378	case STATUSTYPE_TABLE:
379		DMEMIT("%d %llu", sc->stripes,
380			(unsigned long long)sc->chunk_size);
381		for (i = 0; i < sc->stripes; i++)
382			DMEMIT(" %s %llu", sc->stripe[i].dev->name,
383			    (unsigned long long)sc->stripe[i].physical_start);
384		break;
385
386	case STATUSTYPE_IMA:
387		DMEMIT_TARGET_NAME_VERSION(ti->type);
388		DMEMIT(",stripes=%d,chunk_size=%llu", sc->stripes,
389		       (unsigned long long)sc->chunk_size);
390
391		for (i = 0; i < sc->stripes; i++) {
392			DMEMIT(",stripe_%d_device_name=%s", i, sc->stripe[i].dev->name);
393			DMEMIT(",stripe_%d_physical_start=%llu", i,
394			       (unsigned long long)sc->stripe[i].physical_start);
395			DMEMIT(",stripe_%d_status=%c", i,
396			       atomic_read(&(sc->stripe[i].error_count)) ? 'D' : 'A');
397		}
398		DMEMIT(";");
399		break;
400	}
401}
402
403static int stripe_end_io(struct dm_target *ti, struct bio *bio,
404		blk_status_t *error)
405{
406	unsigned int i;
407	char major_minor[16];
408	struct stripe_c *sc = ti->private;
409
410	if (!*error)
411		return DM_ENDIO_DONE; /* I/O complete */
412
413	if (bio->bi_opf & REQ_RAHEAD)
414		return DM_ENDIO_DONE;
415
416	if (*error == BLK_STS_NOTSUPP)
417		return DM_ENDIO_DONE;
418
419	memset(major_minor, 0, sizeof(major_minor));
420	sprintf(major_minor, "%d:%d", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)));
421
422	/*
423	 * Test to see which stripe drive triggered the event
424	 * and increment error count for all stripes on that device.
425	 * If the error count for a given device exceeds the threshold
426	 * value we will no longer trigger any further events.
427	 */
428	for (i = 0; i < sc->stripes; i++)
429		if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
430			atomic_inc(&(sc->stripe[i].error_count));
431			if (atomic_read(&(sc->stripe[i].error_count)) <
432			    DM_IO_ERROR_THRESHOLD)
433				queue_work(dm_stripe_wq, &sc->trigger_event);
434		}
435
436	return DM_ENDIO_DONE;
437}
438
439static int stripe_iterate_devices(struct dm_target *ti,
440				  iterate_devices_callout_fn fn, void *data)
441{
442	struct stripe_c *sc = ti->private;
443	int ret = 0;
444	unsigned int i = 0;
445
446	do {
447		ret = fn(ti, sc->stripe[i].dev,
448			 sc->stripe[i].physical_start,
449			 sc->stripe_width, data);
450	} while (!ret && ++i < sc->stripes);
451
452	return ret;
453}
454
455static void stripe_io_hints(struct dm_target *ti,
456			    struct queue_limits *limits)
457{
458	struct stripe_c *sc = ti->private;
459	unsigned int chunk_size = sc->chunk_size << SECTOR_SHIFT;
460
461	blk_limits_io_min(limits, chunk_size);
462	blk_limits_io_opt(limits, chunk_size * sc->stripes);
463}
464
465static struct target_type stripe_target = {
466	.name   = "striped",
467	.version = {1, 6, 0},
468	.features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT,
469	.module = THIS_MODULE,
470	.ctr    = stripe_ctr,
471	.dtr    = stripe_dtr,
472	.map    = stripe_map,
473	.end_io = stripe_end_io,
474	.status = stripe_status,
475	.iterate_devices = stripe_iterate_devices,
476	.io_hints = stripe_io_hints,
477	.direct_access = stripe_dax_direct_access,
478	.dax_zero_page_range = stripe_dax_zero_page_range,
479	.dax_recovery_write = stripe_dax_recovery_write,
480};
481
482int __init dm_stripe_init(void)
483{
484	int r;
485
486	dm_stripe_wq = alloc_workqueue("dm_stripe_wq", 0, 0);
487	if (!dm_stripe_wq)
488		return -ENOMEM;
489	r = dm_register_target(&stripe_target);
490	if (r < 0) {
491		destroy_workqueue(dm_stripe_wq);
492		DMWARN("target registration failed");
493	}
494
495	return r;
496}
497
498void dm_stripe_exit(void)
499{
500	dm_unregister_target(&stripe_target);
501	destroy_workqueue(dm_stripe_wq);
502}
503