1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * bcache setup/teardown code, and some metadata io - read a superblock and
4  * figure out what to do with it.
5  *
6  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
7  * Copyright 2012 Google, Inc.
8  */
9 
10 #include "bcache.h"
11 #include "btree.h"
12 #include "debug.h"
13 #include "extents.h"
14 #include "request.h"
15 #include "writeback.h"
16 #include "features.h"
17 
18 #include <linux/blkdev.h>
19 #include <linux/pagemap.h>
20 #include <linux/debugfs.h>
21 #include <linux/idr.h>
22 #include <linux/kthread.h>
23 #include <linux/workqueue.h>
24 #include <linux/module.h>
25 #include <linux/random.h>
26 #include <linux/reboot.h>
27 #include <linux/sysfs.h>
28 
29 unsigned int bch_cutoff_writeback;
30 unsigned int bch_cutoff_writeback_sync;
31 
32 static const char bcache_magic[] = {
33 	0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
34 	0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81
35 };
36 
37 static const char invalid_uuid[] = {
38 	0xa0, 0x3e, 0xf8, 0xed, 0x3e, 0xe1, 0xb8, 0x78,
39 	0xc8, 0x50, 0xfc, 0x5e, 0xcb, 0x16, 0xcd, 0x99
40 };
41 
42 static struct kobject *bcache_kobj;
43 struct mutex bch_register_lock;
44 bool bcache_is_reboot;
45 LIST_HEAD(bch_cache_sets);
46 static LIST_HEAD(uncached_devices);
47 
48 static int bcache_major;
49 static DEFINE_IDA(bcache_device_idx);
50 static wait_queue_head_t unregister_wait;
51 struct workqueue_struct *bcache_wq;
52 struct workqueue_struct *bch_flush_wq;
53 struct workqueue_struct *bch_journal_wq;
54 
55 
56 #define BTREE_MAX_PAGES		(256 * 1024 / PAGE_SIZE)
57 /* limitation of partitions number on single bcache device */
58 #define BCACHE_MINORS		128
59 /* limitation of bcache devices number on single system */
60 #define BCACHE_DEVICE_IDX_MAX	((1U << MINORBITS)/BCACHE_MINORS)
61 
62 /* Superblock */
63 
get_bucket_size(struct cache_sb * sb,struct cache_sb_disk * s)64 static unsigned int get_bucket_size(struct cache_sb *sb, struct cache_sb_disk *s)
65 {
66 	unsigned int bucket_size = le16_to_cpu(s->bucket_size);
67 
68 	if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES) {
69 		if (bch_has_feature_large_bucket(sb)) {
70 			unsigned int max, order;
71 
72 			max = sizeof(unsigned int) * BITS_PER_BYTE - 1;
73 			order = le16_to_cpu(s->bucket_size);
74 			/*
75 			 * bcache tool will make sure the overflow won't
76 			 * happen, an error message here is enough.
77 			 */
78 			if (order > max)
79 				pr_err("Bucket size (1 << %u) overflows\n",
80 					order);
81 			bucket_size = 1 << order;
82 		} else if (bch_has_feature_obso_large_bucket(sb)) {
83 			bucket_size +=
84 				le16_to_cpu(s->obso_bucket_size_hi) << 16;
85 		}
86 	}
87 
88 	return bucket_size;
89 }
90 
read_super_common(struct cache_sb * sb,struct block_device * bdev,struct cache_sb_disk * s)91 static const char *read_super_common(struct cache_sb *sb,  struct block_device *bdev,
92 				     struct cache_sb_disk *s)
93 {
94 	const char *err;
95 	unsigned int i;
96 
97 	sb->first_bucket= le16_to_cpu(s->first_bucket);
98 	sb->nbuckets	= le64_to_cpu(s->nbuckets);
99 	sb->bucket_size	= get_bucket_size(sb, s);
100 
101 	sb->nr_in_set	= le16_to_cpu(s->nr_in_set);
102 	sb->nr_this_dev	= le16_to_cpu(s->nr_this_dev);
103 
104 	err = "Too many journal buckets";
105 	if (sb->keys > SB_JOURNAL_BUCKETS)
106 		goto err;
107 
108 	err = "Too many buckets";
109 	if (sb->nbuckets > LONG_MAX)
110 		goto err;
111 
112 	err = "Not enough buckets";
113 	if (sb->nbuckets < 1 << 7)
114 		goto err;
115 
116 	err = "Bad block size (not power of 2)";
117 	if (!is_power_of_2(sb->block_size))
118 		goto err;
119 
120 	err = "Bad block size (larger than page size)";
121 	if (sb->block_size > PAGE_SECTORS)
122 		goto err;
123 
124 	err = "Bad bucket size (not power of 2)";
125 	if (!is_power_of_2(sb->bucket_size))
126 		goto err;
127 
128 	err = "Bad bucket size (smaller than page size)";
129 	if (sb->bucket_size < PAGE_SECTORS)
130 		goto err;
131 
132 	err = "Invalid superblock: device too small";
133 	if (get_capacity(bdev->bd_disk) <
134 	    sb->bucket_size * sb->nbuckets)
135 		goto err;
136 
137 	err = "Bad UUID";
138 	if (bch_is_zero(sb->set_uuid, 16))
139 		goto err;
140 
141 	err = "Bad cache device number in set";
142 	if (!sb->nr_in_set ||
143 	    sb->nr_in_set <= sb->nr_this_dev ||
144 	    sb->nr_in_set > MAX_CACHES_PER_SET)
145 		goto err;
146 
147 	err = "Journal buckets not sequential";
148 	for (i = 0; i < sb->keys; i++)
149 		if (sb->d[i] != sb->first_bucket + i)
150 			goto err;
151 
152 	err = "Too many journal buckets";
153 	if (sb->first_bucket + sb->keys > sb->nbuckets)
154 		goto err;
155 
156 	err = "Invalid superblock: first bucket comes before end of super";
157 	if (sb->first_bucket * sb->bucket_size < 16)
158 		goto err;
159 
160 	err = NULL;
161 err:
162 	return err;
163 }
164 
165 
read_super(struct cache_sb * sb,struct block_device * bdev,struct cache_sb_disk ** res)166 static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
167 			      struct cache_sb_disk **res)
168 {
169 	const char *err;
170 	struct cache_sb_disk *s;
171 	struct page *page;
172 	unsigned int i;
173 
174 	page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
175 				   SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
176 	if (IS_ERR(page))
177 		return "IO error";
178 	s = page_address(page) + offset_in_page(SB_OFFSET);
179 
180 	sb->offset		= le64_to_cpu(s->offset);
181 	sb->version		= le64_to_cpu(s->version);
182 
183 	memcpy(sb->magic,	s->magic, 16);
184 	memcpy(sb->uuid,	s->uuid, 16);
185 	memcpy(sb->set_uuid,	s->set_uuid, 16);
186 	memcpy(sb->label,	s->label, SB_LABEL_SIZE);
187 
188 	sb->flags		= le64_to_cpu(s->flags);
189 	sb->seq			= le64_to_cpu(s->seq);
190 	sb->last_mount		= le32_to_cpu(s->last_mount);
191 	sb->keys		= le16_to_cpu(s->keys);
192 
193 	for (i = 0; i < SB_JOURNAL_BUCKETS; i++)
194 		sb->d[i] = le64_to_cpu(s->d[i]);
195 
196 	pr_debug("read sb version %llu, flags %llu, seq %llu, journal size %u\n",
197 		 sb->version, sb->flags, sb->seq, sb->keys);
198 
199 	err = "Not a bcache superblock (bad offset)";
200 	if (sb->offset != SB_SECTOR)
201 		goto err;
202 
203 	err = "Not a bcache superblock (bad magic)";
204 	if (memcmp(sb->magic, bcache_magic, 16))
205 		goto err;
206 
207 	err = "Bad checksum";
208 	if (s->csum != csum_set(s))
209 		goto err;
210 
211 	err = "Bad UUID";
212 	if (bch_is_zero(sb->uuid, 16))
213 		goto err;
214 
215 	sb->block_size	= le16_to_cpu(s->block_size);
216 
217 	err = "Superblock block size smaller than device block size";
218 	if (sb->block_size << 9 < bdev_logical_block_size(bdev))
219 		goto err;
220 
221 	switch (sb->version) {
222 	case BCACHE_SB_VERSION_BDEV:
223 		sb->data_offset	= BDEV_DATA_START_DEFAULT;
224 		break;
225 	case BCACHE_SB_VERSION_BDEV_WITH_OFFSET:
226 	case BCACHE_SB_VERSION_BDEV_WITH_FEATURES:
227 		sb->data_offset	= le64_to_cpu(s->data_offset);
228 
229 		err = "Bad data offset";
230 		if (sb->data_offset < BDEV_DATA_START_DEFAULT)
231 			goto err;
232 
233 		break;
234 	case BCACHE_SB_VERSION_CDEV:
235 	case BCACHE_SB_VERSION_CDEV_WITH_UUID:
236 		err = read_super_common(sb, bdev, s);
237 		if (err)
238 			goto err;
239 		break;
240 	case BCACHE_SB_VERSION_CDEV_WITH_FEATURES:
241 		/*
242 		 * Feature bits are needed in read_super_common(),
243 		 * convert them firstly.
244 		 */
245 		sb->feature_compat = le64_to_cpu(s->feature_compat);
246 		sb->feature_incompat = le64_to_cpu(s->feature_incompat);
247 		sb->feature_ro_compat = le64_to_cpu(s->feature_ro_compat);
248 
249 		/* Check incompatible features */
250 		err = "Unsupported compatible feature found";
251 		if (bch_has_unknown_compat_features(sb))
252 			goto err;
253 
254 		err = "Unsupported read-only compatible feature found";
255 		if (bch_has_unknown_ro_compat_features(sb))
256 			goto err;
257 
258 		err = "Unsupported incompatible feature found";
259 		if (bch_has_unknown_incompat_features(sb))
260 			goto err;
261 
262 		err = read_super_common(sb, bdev, s);
263 		if (err)
264 			goto err;
265 		break;
266 	default:
267 		err = "Unsupported superblock version";
268 		goto err;
269 	}
270 
271 	sb->last_mount = (u32)ktime_get_real_seconds();
272 	*res = s;
273 	return NULL;
274 err:
275 	put_page(page);
276 	return err;
277 }
278 
write_bdev_super_endio(struct bio * bio)279 static void write_bdev_super_endio(struct bio *bio)
280 {
281 	struct cached_dev *dc = bio->bi_private;
282 
283 	if (bio->bi_status)
284 		bch_count_backing_io_errors(dc, bio);
285 
286 	closure_put(&dc->sb_write);
287 }
288 
__write_super(struct cache_sb * sb,struct cache_sb_disk * out,struct bio * bio)289 static void __write_super(struct cache_sb *sb, struct cache_sb_disk *out,
290 		struct bio *bio)
291 {
292 	unsigned int i;
293 
294 	bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_META;
295 	bio->bi_iter.bi_sector	= SB_SECTOR;
296 	__bio_add_page(bio, virt_to_page(out), SB_SIZE,
297 			offset_in_page(out));
298 
299 	out->offset		= cpu_to_le64(sb->offset);
300 
301 	memcpy(out->uuid,	sb->uuid, 16);
302 	memcpy(out->set_uuid,	sb->set_uuid, 16);
303 	memcpy(out->label,	sb->label, SB_LABEL_SIZE);
304 
305 	out->flags		= cpu_to_le64(sb->flags);
306 	out->seq		= cpu_to_le64(sb->seq);
307 
308 	out->last_mount		= cpu_to_le32(sb->last_mount);
309 	out->first_bucket	= cpu_to_le16(sb->first_bucket);
310 	out->keys		= cpu_to_le16(sb->keys);
311 
312 	for (i = 0; i < sb->keys; i++)
313 		out->d[i] = cpu_to_le64(sb->d[i]);
314 
315 	if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES) {
316 		out->feature_compat    = cpu_to_le64(sb->feature_compat);
317 		out->feature_incompat  = cpu_to_le64(sb->feature_incompat);
318 		out->feature_ro_compat = cpu_to_le64(sb->feature_ro_compat);
319 	}
320 
321 	out->version		= cpu_to_le64(sb->version);
322 	out->csum = csum_set(out);
323 
324 	pr_debug("ver %llu, flags %llu, seq %llu\n",
325 		 sb->version, sb->flags, sb->seq);
326 
327 	submit_bio(bio);
328 }
329 
bch_write_bdev_super_unlock(struct closure * cl)330 static void bch_write_bdev_super_unlock(struct closure *cl)
331 {
332 	struct cached_dev *dc = container_of(cl, struct cached_dev, sb_write);
333 
334 	up(&dc->sb_write_mutex);
335 }
336 
bch_write_bdev_super(struct cached_dev * dc,struct closure * parent)337 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent)
338 {
339 	struct closure *cl = &dc->sb_write;
340 	struct bio *bio = &dc->sb_bio;
341 
342 	down(&dc->sb_write_mutex);
343 	closure_init(cl, parent);
344 
345 	bio_init(bio, dc->bdev, dc->sb_bv, 1, 0);
346 	bio->bi_end_io	= write_bdev_super_endio;
347 	bio->bi_private = dc;
348 
349 	closure_get(cl);
350 	/* I/O request sent to backing device */
351 	__write_super(&dc->sb, dc->sb_disk, bio);
352 
353 	closure_return_with_destructor(cl, bch_write_bdev_super_unlock);
354 }
355 
write_super_endio(struct bio * bio)356 static void write_super_endio(struct bio *bio)
357 {
358 	struct cache *ca = bio->bi_private;
359 
360 	/* is_read = 0 */
361 	bch_count_io_errors(ca, bio->bi_status, 0,
362 			    "writing superblock");
363 	closure_put(&ca->set->sb_write);
364 }
365 
bcache_write_super_unlock(struct closure * cl)366 static void bcache_write_super_unlock(struct closure *cl)
367 {
368 	struct cache_set *c = container_of(cl, struct cache_set, sb_write);
369 
370 	up(&c->sb_write_mutex);
371 }
372 
bcache_write_super(struct cache_set * c)373 void bcache_write_super(struct cache_set *c)
374 {
375 	struct closure *cl = &c->sb_write;
376 	struct cache *ca = c->cache;
377 	struct bio *bio = &ca->sb_bio;
378 	unsigned int version = BCACHE_SB_VERSION_CDEV_WITH_UUID;
379 
380 	down(&c->sb_write_mutex);
381 	closure_init(cl, &c->cl);
382 
383 	ca->sb.seq++;
384 
385 	if (ca->sb.version < version)
386 		ca->sb.version = version;
387 
388 	bio_init(bio, ca->bdev, ca->sb_bv, 1, 0);
389 	bio->bi_end_io	= write_super_endio;
390 	bio->bi_private = ca;
391 
392 	closure_get(cl);
393 	__write_super(&ca->sb, ca->sb_disk, bio);
394 
395 	closure_return_with_destructor(cl, bcache_write_super_unlock);
396 }
397 
398 /* UUID io */
399 
uuid_endio(struct bio * bio)400 static void uuid_endio(struct bio *bio)
401 {
402 	struct closure *cl = bio->bi_private;
403 	struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
404 
405 	cache_set_err_on(bio->bi_status, c, "accessing uuids");
406 	bch_bbio_free(bio, c);
407 	closure_put(cl);
408 }
409 
uuid_io_unlock(struct closure * cl)410 static void uuid_io_unlock(struct closure *cl)
411 {
412 	struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
413 
414 	up(&c->uuid_write_mutex);
415 }
416 
uuid_io(struct cache_set * c,blk_opf_t opf,struct bkey * k,struct closure * parent)417 static void uuid_io(struct cache_set *c, blk_opf_t opf, struct bkey *k,
418 		    struct closure *parent)
419 {
420 	struct closure *cl = &c->uuid_write;
421 	struct uuid_entry *u;
422 	unsigned int i;
423 	char buf[80];
424 
425 	BUG_ON(!parent);
426 	down(&c->uuid_write_mutex);
427 	closure_init(cl, parent);
428 
429 	for (i = 0; i < KEY_PTRS(k); i++) {
430 		struct bio *bio = bch_bbio_alloc(c);
431 
432 		bio->bi_opf = opf | REQ_SYNC | REQ_META;
433 		bio->bi_iter.bi_size = KEY_SIZE(k) << 9;
434 
435 		bio->bi_end_io	= uuid_endio;
436 		bio->bi_private = cl;
437 		bch_bio_map(bio, c->uuids);
438 
439 		bch_submit_bbio(bio, c, k, i);
440 
441 		if ((opf & REQ_OP_MASK) != REQ_OP_WRITE)
442 			break;
443 	}
444 
445 	bch_extent_to_text(buf, sizeof(buf), k);
446 	pr_debug("%s UUIDs at %s\n", (opf & REQ_OP_MASK) == REQ_OP_WRITE ?
447 		 "wrote" : "read", buf);
448 
449 	for (u = c->uuids; u < c->uuids + c->nr_uuids; u++)
450 		if (!bch_is_zero(u->uuid, 16))
451 			pr_debug("Slot %zi: %pU: %s: 1st: %u last: %u inv: %u\n",
452 				 u - c->uuids, u->uuid, u->label,
453 				 u->first_reg, u->last_reg, u->invalidated);
454 
455 	closure_return_with_destructor(cl, uuid_io_unlock);
456 }
457 
uuid_read(struct cache_set * c,struct jset * j,struct closure * cl)458 static char *uuid_read(struct cache_set *c, struct jset *j, struct closure *cl)
459 {
460 	struct bkey *k = &j->uuid_bucket;
461 
462 	if (__bch_btree_ptr_invalid(c, k))
463 		return "bad uuid pointer";
464 
465 	bkey_copy(&c->uuid_bucket, k);
466 	uuid_io(c, REQ_OP_READ, k, cl);
467 
468 	if (j->version < BCACHE_JSET_VERSION_UUIDv1) {
469 		struct uuid_entry_v0	*u0 = (void *) c->uuids;
470 		struct uuid_entry	*u1 = (void *) c->uuids;
471 		int i;
472 
473 		closure_sync(cl);
474 
475 		/*
476 		 * Since the new uuid entry is bigger than the old, we have to
477 		 * convert starting at the highest memory address and work down
478 		 * in order to do it in place
479 		 */
480 
481 		for (i = c->nr_uuids - 1;
482 		     i >= 0;
483 		     --i) {
484 			memcpy(u1[i].uuid,	u0[i].uuid, 16);
485 			memcpy(u1[i].label,	u0[i].label, 32);
486 
487 			u1[i].first_reg		= u0[i].first_reg;
488 			u1[i].last_reg		= u0[i].last_reg;
489 			u1[i].invalidated	= u0[i].invalidated;
490 
491 			u1[i].flags	= 0;
492 			u1[i].sectors	= 0;
493 		}
494 	}
495 
496 	return NULL;
497 }
498 
__uuid_write(struct cache_set * c)499 static int __uuid_write(struct cache_set *c)
500 {
501 	BKEY_PADDED(key) k;
502 	struct closure cl;
503 	struct cache *ca = c->cache;
504 	unsigned int size;
505 
506 	closure_init_stack(&cl);
507 	lockdep_assert_held(&bch_register_lock);
508 
509 	if (bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, true))
510 		return 1;
511 
512 	size =  meta_bucket_pages(&ca->sb) * PAGE_SECTORS;
513 	SET_KEY_SIZE(&k.key, size);
514 	uuid_io(c, REQ_OP_WRITE, &k.key, &cl);
515 	closure_sync(&cl);
516 
517 	/* Only one bucket used for uuid write */
518 	atomic_long_add(ca->sb.bucket_size, &ca->meta_sectors_written);
519 
520 	bkey_copy(&c->uuid_bucket, &k.key);
521 	bkey_put(c, &k.key);
522 	return 0;
523 }
524 
bch_uuid_write(struct cache_set * c)525 int bch_uuid_write(struct cache_set *c)
526 {
527 	int ret = __uuid_write(c);
528 
529 	if (!ret)
530 		bch_journal_meta(c, NULL);
531 
532 	return ret;
533 }
534 
uuid_find(struct cache_set * c,const char * uuid)535 static struct uuid_entry *uuid_find(struct cache_set *c, const char *uuid)
536 {
537 	struct uuid_entry *u;
538 
539 	for (u = c->uuids;
540 	     u < c->uuids + c->nr_uuids; u++)
541 		if (!memcmp(u->uuid, uuid, 16))
542 			return u;
543 
544 	return NULL;
545 }
546 
uuid_find_empty(struct cache_set * c)547 static struct uuid_entry *uuid_find_empty(struct cache_set *c)
548 {
549 	static const char zero_uuid[16] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
550 
551 	return uuid_find(c, zero_uuid);
552 }
553 
554 /*
555  * Bucket priorities/gens:
556  *
557  * For each bucket, we store on disk its
558  *   8 bit gen
559  *  16 bit priority
560  *
561  * See alloc.c for an explanation of the gen. The priority is used to implement
562  * lru (and in the future other) cache replacement policies; for most purposes
563  * it's just an opaque integer.
564  *
565  * The gens and the priorities don't have a whole lot to do with each other, and
566  * it's actually the gens that must be written out at specific times - it's no
567  * big deal if the priorities don't get written, if we lose them we just reuse
568  * buckets in suboptimal order.
569  *
570  * On disk they're stored in a packed array, and in as many buckets are required
571  * to fit them all. The buckets we use to store them form a list; the journal
572  * header points to the first bucket, the first bucket points to the second
573  * bucket, et cetera.
574  *
575  * This code is used by the allocation code; periodically (whenever it runs out
576  * of buckets to allocate from) the allocation code will invalidate some
577  * buckets, but it can't use those buckets until their new gens are safely on
578  * disk.
579  */
580 
prio_endio(struct bio * bio)581 static void prio_endio(struct bio *bio)
582 {
583 	struct cache *ca = bio->bi_private;
584 
585 	cache_set_err_on(bio->bi_status, ca->set, "accessing priorities");
586 	bch_bbio_free(bio, ca->set);
587 	closure_put(&ca->prio);
588 }
589 
prio_io(struct cache * ca,uint64_t bucket,blk_opf_t opf)590 static void prio_io(struct cache *ca, uint64_t bucket, blk_opf_t opf)
591 {
592 	struct closure *cl = &ca->prio;
593 	struct bio *bio = bch_bbio_alloc(ca->set);
594 
595 	closure_init_stack(cl);
596 
597 	bio->bi_iter.bi_sector	= bucket * ca->sb.bucket_size;
598 	bio_set_dev(bio, ca->bdev);
599 	bio->bi_iter.bi_size	= meta_bucket_bytes(&ca->sb);
600 
601 	bio->bi_end_io	= prio_endio;
602 	bio->bi_private = ca;
603 	bio->bi_opf = opf | REQ_SYNC | REQ_META;
604 	bch_bio_map(bio, ca->disk_buckets);
605 
606 	closure_bio_submit(ca->set, bio, &ca->prio);
607 	closure_sync(cl);
608 }
609 
bch_prio_write(struct cache * ca,bool wait)610 int bch_prio_write(struct cache *ca, bool wait)
611 {
612 	int i;
613 	struct bucket *b;
614 	struct closure cl;
615 
616 	pr_debug("free_prio=%zu, free_none=%zu, free_inc=%zu\n",
617 		 fifo_used(&ca->free[RESERVE_PRIO]),
618 		 fifo_used(&ca->free[RESERVE_NONE]),
619 		 fifo_used(&ca->free_inc));
620 
621 	/*
622 	 * Pre-check if there are enough free buckets. In the non-blocking
623 	 * scenario it's better to fail early rather than starting to allocate
624 	 * buckets and do a cleanup later in case of failure.
625 	 */
626 	if (!wait) {
627 		size_t avail = fifo_used(&ca->free[RESERVE_PRIO]) +
628 			       fifo_used(&ca->free[RESERVE_NONE]);
629 		if (prio_buckets(ca) > avail)
630 			return -ENOMEM;
631 	}
632 
633 	closure_init_stack(&cl);
634 
635 	lockdep_assert_held(&ca->set->bucket_lock);
636 
637 	ca->disk_buckets->seq++;
638 
639 	atomic_long_add(ca->sb.bucket_size * prio_buckets(ca),
640 			&ca->meta_sectors_written);
641 
642 	for (i = prio_buckets(ca) - 1; i >= 0; --i) {
643 		long bucket;
644 		struct prio_set *p = ca->disk_buckets;
645 		struct bucket_disk *d = p->data;
646 		struct bucket_disk *end = d + prios_per_bucket(ca);
647 
648 		for (b = ca->buckets + i * prios_per_bucket(ca);
649 		     b < ca->buckets + ca->sb.nbuckets && d < end;
650 		     b++, d++) {
651 			d->prio = cpu_to_le16(b->prio);
652 			d->gen = b->gen;
653 		}
654 
655 		p->next_bucket	= ca->prio_buckets[i + 1];
656 		p->magic	= pset_magic(&ca->sb);
657 		p->csum		= bch_crc64(&p->magic, meta_bucket_bytes(&ca->sb) - 8);
658 
659 		bucket = bch_bucket_alloc(ca, RESERVE_PRIO, wait);
660 		BUG_ON(bucket == -1);
661 
662 		mutex_unlock(&ca->set->bucket_lock);
663 		prio_io(ca, bucket, REQ_OP_WRITE);
664 		mutex_lock(&ca->set->bucket_lock);
665 
666 		ca->prio_buckets[i] = bucket;
667 		atomic_dec_bug(&ca->buckets[bucket].pin);
668 	}
669 
670 	mutex_unlock(&ca->set->bucket_lock);
671 
672 	bch_journal_meta(ca->set, &cl);
673 	closure_sync(&cl);
674 
675 	mutex_lock(&ca->set->bucket_lock);
676 
677 	/*
678 	 * Don't want the old priorities to get garbage collected until after we
679 	 * finish writing the new ones, and they're journalled
680 	 */
681 	for (i = 0; i < prio_buckets(ca); i++) {
682 		if (ca->prio_last_buckets[i])
683 			__bch_bucket_free(ca,
684 				&ca->buckets[ca->prio_last_buckets[i]]);
685 
686 		ca->prio_last_buckets[i] = ca->prio_buckets[i];
687 	}
688 	return 0;
689 }
690 
prio_read(struct cache * ca,uint64_t bucket)691 static int prio_read(struct cache *ca, uint64_t bucket)
692 {
693 	struct prio_set *p = ca->disk_buckets;
694 	struct bucket_disk *d = p->data + prios_per_bucket(ca), *end = d;
695 	struct bucket *b;
696 	unsigned int bucket_nr = 0;
697 	int ret = -EIO;
698 
699 	for (b = ca->buckets;
700 	     b < ca->buckets + ca->sb.nbuckets;
701 	     b++, d++) {
702 		if (d == end) {
703 			ca->prio_buckets[bucket_nr] = bucket;
704 			ca->prio_last_buckets[bucket_nr] = bucket;
705 			bucket_nr++;
706 
707 			prio_io(ca, bucket, REQ_OP_READ);
708 
709 			if (p->csum !=
710 			    bch_crc64(&p->magic, meta_bucket_bytes(&ca->sb) - 8)) {
711 				pr_warn("bad csum reading priorities\n");
712 				goto out;
713 			}
714 
715 			if (p->magic != pset_magic(&ca->sb)) {
716 				pr_warn("bad magic reading priorities\n");
717 				goto out;
718 			}
719 
720 			bucket = p->next_bucket;
721 			d = p->data;
722 		}
723 
724 		b->prio = le16_to_cpu(d->prio);
725 		b->gen = b->last_gc = d->gen;
726 	}
727 
728 	ret = 0;
729 out:
730 	return ret;
731 }
732 
733 /* Bcache device */
734 
open_dev(struct block_device * b,fmode_t mode)735 static int open_dev(struct block_device *b, fmode_t mode)
736 {
737 	struct bcache_device *d = b->bd_disk->private_data;
738 
739 	if (test_bit(BCACHE_DEV_CLOSING, &d->flags))
740 		return -ENXIO;
741 
742 	closure_get(&d->cl);
743 	return 0;
744 }
745 
release_dev(struct gendisk * b,fmode_t mode)746 static void release_dev(struct gendisk *b, fmode_t mode)
747 {
748 	struct bcache_device *d = b->private_data;
749 
750 	closure_put(&d->cl);
751 }
752 
ioctl_dev(struct block_device * b,fmode_t mode,unsigned int cmd,unsigned long arg)753 static int ioctl_dev(struct block_device *b, fmode_t mode,
754 		     unsigned int cmd, unsigned long arg)
755 {
756 	struct bcache_device *d = b->bd_disk->private_data;
757 
758 	return d->ioctl(d, mode, cmd, arg);
759 }
760 
761 static const struct block_device_operations bcache_cached_ops = {
762 	.submit_bio	= cached_dev_submit_bio,
763 	.open		= open_dev,
764 	.release	= release_dev,
765 	.ioctl		= ioctl_dev,
766 	.owner		= THIS_MODULE,
767 };
768 
769 static const struct block_device_operations bcache_flash_ops = {
770 	.submit_bio	= flash_dev_submit_bio,
771 	.open		= open_dev,
772 	.release	= release_dev,
773 	.ioctl		= ioctl_dev,
774 	.owner		= THIS_MODULE,
775 };
776 
bcache_device_stop(struct bcache_device * d)777 void bcache_device_stop(struct bcache_device *d)
778 {
779 	if (!test_and_set_bit(BCACHE_DEV_CLOSING, &d->flags))
780 		/*
781 		 * closure_fn set to
782 		 * - cached device: cached_dev_flush()
783 		 * - flash dev: flash_dev_flush()
784 		 */
785 		closure_queue(&d->cl);
786 }
787 
bcache_device_unlink(struct bcache_device * d)788 static void bcache_device_unlink(struct bcache_device *d)
789 {
790 	lockdep_assert_held(&bch_register_lock);
791 
792 	if (d->c && !test_and_set_bit(BCACHE_DEV_UNLINK_DONE, &d->flags)) {
793 		struct cache *ca = d->c->cache;
794 
795 		sysfs_remove_link(&d->c->kobj, d->name);
796 		sysfs_remove_link(&d->kobj, "cache");
797 
798 		bd_unlink_disk_holder(ca->bdev, d->disk);
799 	}
800 }
801 
bcache_device_link(struct bcache_device * d,struct cache_set * c,const char * name)802 static void bcache_device_link(struct bcache_device *d, struct cache_set *c,
803 			       const char *name)
804 {
805 	struct cache *ca = c->cache;
806 	int ret;
807 
808 	bd_link_disk_holder(ca->bdev, d->disk);
809 
810 	snprintf(d->name, BCACHEDEVNAME_SIZE,
811 		 "%s%u", name, d->id);
812 
813 	ret = sysfs_create_link(&d->kobj, &c->kobj, "cache");
814 	if (ret < 0)
815 		pr_err("Couldn't create device -> cache set symlink\n");
816 
817 	ret = sysfs_create_link(&c->kobj, &d->kobj, d->name);
818 	if (ret < 0)
819 		pr_err("Couldn't create cache set -> device symlink\n");
820 
821 	clear_bit(BCACHE_DEV_UNLINK_DONE, &d->flags);
822 }
823 
bcache_device_detach(struct bcache_device * d)824 static void bcache_device_detach(struct bcache_device *d)
825 {
826 	lockdep_assert_held(&bch_register_lock);
827 
828 	atomic_dec(&d->c->attached_dev_nr);
829 
830 	if (test_bit(BCACHE_DEV_DETACHING, &d->flags)) {
831 		struct uuid_entry *u = d->c->uuids + d->id;
832 
833 		SET_UUID_FLASH_ONLY(u, 0);
834 		memcpy(u->uuid, invalid_uuid, 16);
835 		u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds());
836 		bch_uuid_write(d->c);
837 	}
838 
839 	bcache_device_unlink(d);
840 
841 	d->c->devices[d->id] = NULL;
842 	closure_put(&d->c->caching);
843 	d->c = NULL;
844 }
845 
bcache_device_attach(struct bcache_device * d,struct cache_set * c,unsigned int id)846 static void bcache_device_attach(struct bcache_device *d, struct cache_set *c,
847 				 unsigned int id)
848 {
849 	d->id = id;
850 	d->c = c;
851 	c->devices[id] = d;
852 
853 	if (id >= c->devices_max_used)
854 		c->devices_max_used = id + 1;
855 
856 	closure_get(&c->caching);
857 }
858 
first_minor_to_idx(int first_minor)859 static inline int first_minor_to_idx(int first_minor)
860 {
861 	return (first_minor/BCACHE_MINORS);
862 }
863 
idx_to_first_minor(int idx)864 static inline int idx_to_first_minor(int idx)
865 {
866 	return (idx * BCACHE_MINORS);
867 }
868 
bcache_device_free(struct bcache_device * d)869 static void bcache_device_free(struct bcache_device *d)
870 {
871 	struct gendisk *disk = d->disk;
872 
873 	lockdep_assert_held(&bch_register_lock);
874 
875 	if (disk)
876 		pr_info("%s stopped\n", disk->disk_name);
877 	else
878 		pr_err("bcache device (NULL gendisk) stopped\n");
879 
880 	if (d->c)
881 		bcache_device_detach(d);
882 
883 	if (disk) {
884 		ida_simple_remove(&bcache_device_idx,
885 				  first_minor_to_idx(disk->first_minor));
886 		put_disk(disk);
887 	}
888 
889 	bioset_exit(&d->bio_split);
890 	kvfree(d->full_dirty_stripes);
891 	kvfree(d->stripe_sectors_dirty);
892 
893 	closure_debug_destroy(&d->cl);
894 }
895 
bcache_device_init(struct bcache_device * d,unsigned int block_size,sector_t sectors,struct block_device * cached_bdev,const struct block_device_operations * ops)896 static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
897 		sector_t sectors, struct block_device *cached_bdev,
898 		const struct block_device_operations *ops)
899 {
900 	struct request_queue *q;
901 	const size_t max_stripes = min_t(size_t, INT_MAX,
902 					 SIZE_MAX / sizeof(atomic_t));
903 	uint64_t n;
904 	int idx;
905 
906 	if (!d->stripe_size)
907 		d->stripe_size = 1 << 31;
908 
909 	n = DIV_ROUND_UP_ULL(sectors, d->stripe_size);
910 	if (!n || n > max_stripes) {
911 		pr_err("nr_stripes too large or invalid: %llu (start sector beyond end of disk?)\n",
912 			n);
913 		return -ENOMEM;
914 	}
915 	d->nr_stripes = n;
916 
917 	n = d->nr_stripes * sizeof(atomic_t);
918 	d->stripe_sectors_dirty = kvzalloc(n, GFP_KERNEL);
919 	if (!d->stripe_sectors_dirty)
920 		return -ENOMEM;
921 
922 	n = BITS_TO_LONGS(d->nr_stripes) * sizeof(unsigned long);
923 	d->full_dirty_stripes = kvzalloc(n, GFP_KERNEL);
924 	if (!d->full_dirty_stripes)
925 		goto out_free_stripe_sectors_dirty;
926 
927 	idx = ida_simple_get(&bcache_device_idx, 0,
928 				BCACHE_DEVICE_IDX_MAX, GFP_KERNEL);
929 	if (idx < 0)
930 		goto out_free_full_dirty_stripes;
931 
932 	if (bioset_init(&d->bio_split, 4, offsetof(struct bbio, bio),
933 			BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER))
934 		goto out_ida_remove;
935 
936 	d->disk = blk_alloc_disk(NUMA_NO_NODE);
937 	if (!d->disk)
938 		goto out_bioset_exit;
939 
940 	set_capacity(d->disk, sectors);
941 	snprintf(d->disk->disk_name, DISK_NAME_LEN, "bcache%i", idx);
942 
943 	d->disk->major		= bcache_major;
944 	d->disk->first_minor	= idx_to_first_minor(idx);
945 	d->disk->minors		= BCACHE_MINORS;
946 	d->disk->fops		= ops;
947 	d->disk->private_data	= d;
948 
949 	q = d->disk->queue;
950 	q->limits.max_hw_sectors	= UINT_MAX;
951 	q->limits.max_sectors		= UINT_MAX;
952 	q->limits.max_segment_size	= UINT_MAX;
953 	q->limits.max_segments		= BIO_MAX_VECS;
954 	blk_queue_max_discard_sectors(q, UINT_MAX);
955 	q->limits.discard_granularity	= 512;
956 	q->limits.io_min		= block_size;
957 	q->limits.logical_block_size	= block_size;
958 	q->limits.physical_block_size	= block_size;
959 
960 	if (q->limits.logical_block_size > PAGE_SIZE && cached_bdev) {
961 		/*
962 		 * This should only happen with BCACHE_SB_VERSION_BDEV.
963 		 * Block/page size is checked for BCACHE_SB_VERSION_CDEV.
964 		 */
965 		pr_info("%s: sb/logical block size (%u) greater than page size (%lu) falling back to device logical block size (%u)\n",
966 			d->disk->disk_name, q->limits.logical_block_size,
967 			PAGE_SIZE, bdev_logical_block_size(cached_bdev));
968 
969 		/* This also adjusts physical block size/min io size if needed */
970 		blk_queue_logical_block_size(q, bdev_logical_block_size(cached_bdev));
971 	}
972 
973 	blk_queue_flag_set(QUEUE_FLAG_NONROT, d->disk->queue);
974 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, d->disk->queue);
975 
976 	blk_queue_write_cache(q, true, true);
977 
978 	return 0;
979 
980 out_bioset_exit:
981 	bioset_exit(&d->bio_split);
982 out_ida_remove:
983 	ida_simple_remove(&bcache_device_idx, idx);
984 out_free_full_dirty_stripes:
985 	kvfree(d->full_dirty_stripes);
986 out_free_stripe_sectors_dirty:
987 	kvfree(d->stripe_sectors_dirty);
988 	return -ENOMEM;
989 
990 }
991 
992 /* Cached device */
993 
calc_cached_dev_sectors(struct cache_set * c)994 static void calc_cached_dev_sectors(struct cache_set *c)
995 {
996 	uint64_t sectors = 0;
997 	struct cached_dev *dc;
998 
999 	list_for_each_entry(dc, &c->cached_devs, list)
1000 		sectors += bdev_nr_sectors(dc->bdev);
1001 
1002 	c->cached_dev_sectors = sectors;
1003 }
1004 
1005 #define BACKING_DEV_OFFLINE_TIMEOUT 5
cached_dev_status_update(void * arg)1006 static int cached_dev_status_update(void *arg)
1007 {
1008 	struct cached_dev *dc = arg;
1009 	struct request_queue *q;
1010 
1011 	/*
1012 	 * If this delayed worker is stopping outside, directly quit here.
1013 	 * dc->io_disable might be set via sysfs interface, so check it
1014 	 * here too.
1015 	 */
1016 	while (!kthread_should_stop() && !dc->io_disable) {
1017 		q = bdev_get_queue(dc->bdev);
1018 		if (blk_queue_dying(q))
1019 			dc->offline_seconds++;
1020 		else
1021 			dc->offline_seconds = 0;
1022 
1023 		if (dc->offline_seconds >= BACKING_DEV_OFFLINE_TIMEOUT) {
1024 			pr_err("%pg: device offline for %d seconds\n",
1025 			       dc->bdev,
1026 			       BACKING_DEV_OFFLINE_TIMEOUT);
1027 			pr_err("%s: disable I/O request due to backing device offline\n",
1028 			       dc->disk.name);
1029 			dc->io_disable = true;
1030 			/* let others know earlier that io_disable is true */
1031 			smp_mb();
1032 			bcache_device_stop(&dc->disk);
1033 			break;
1034 		}
1035 		schedule_timeout_interruptible(HZ);
1036 	}
1037 
1038 	wait_for_kthread_stop();
1039 	return 0;
1040 }
1041 
1042 
bch_cached_dev_run(struct cached_dev * dc)1043 int bch_cached_dev_run(struct cached_dev *dc)
1044 {
1045 	int ret = 0;
1046 	struct bcache_device *d = &dc->disk;
1047 	char *buf = kmemdup_nul(dc->sb.label, SB_LABEL_SIZE, GFP_KERNEL);
1048 	char *env[] = {
1049 		"DRIVER=bcache",
1050 		kasprintf(GFP_KERNEL, "CACHED_UUID=%pU", dc->sb.uuid),
1051 		kasprintf(GFP_KERNEL, "CACHED_LABEL=%s", buf ? : ""),
1052 		NULL,
1053 	};
1054 
1055 	if (dc->io_disable) {
1056 		pr_err("I/O disabled on cached dev %pg\n", dc->bdev);
1057 		ret = -EIO;
1058 		goto out;
1059 	}
1060 
1061 	if (atomic_xchg(&dc->running, 1)) {
1062 		pr_info("cached dev %pg is running already\n", dc->bdev);
1063 		ret = -EBUSY;
1064 		goto out;
1065 	}
1066 
1067 	if (!d->c &&
1068 	    BDEV_STATE(&dc->sb) != BDEV_STATE_NONE) {
1069 		struct closure cl;
1070 
1071 		closure_init_stack(&cl);
1072 
1073 		SET_BDEV_STATE(&dc->sb, BDEV_STATE_STALE);
1074 		bch_write_bdev_super(dc, &cl);
1075 		closure_sync(&cl);
1076 	}
1077 
1078 	ret = add_disk(d->disk);
1079 	if (ret)
1080 		goto out;
1081 	bd_link_disk_holder(dc->bdev, dc->disk.disk);
1082 	/*
1083 	 * won't show up in the uevent file, use udevadm monitor -e instead
1084 	 * only class / kset properties are persistent
1085 	 */
1086 	kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env);
1087 
1088 	if (sysfs_create_link(&d->kobj, &disk_to_dev(d->disk)->kobj, "dev") ||
1089 	    sysfs_create_link(&disk_to_dev(d->disk)->kobj,
1090 			      &d->kobj, "bcache")) {
1091 		pr_err("Couldn't create bcache dev <-> disk sysfs symlinks\n");
1092 		ret = -ENOMEM;
1093 		goto out;
1094 	}
1095 
1096 	dc->status_update_thread = kthread_run(cached_dev_status_update,
1097 					       dc, "bcache_status_update");
1098 	if (IS_ERR(dc->status_update_thread)) {
1099 		pr_warn("failed to create bcache_status_update kthread, continue to run without monitoring backing device status\n");
1100 	}
1101 
1102 out:
1103 	kfree(env[1]);
1104 	kfree(env[2]);
1105 	kfree(buf);
1106 	return ret;
1107 }
1108 
1109 /*
1110  * If BCACHE_DEV_RATE_DW_RUNNING is set, it means routine of the delayed
1111  * work dc->writeback_rate_update is running. Wait until the routine
1112  * quits (BCACHE_DEV_RATE_DW_RUNNING is clear), then continue to
1113  * cancel it. If BCACHE_DEV_RATE_DW_RUNNING is not clear after time_out
1114  * seconds, give up waiting here and continue to cancel it too.
1115  */
cancel_writeback_rate_update_dwork(struct cached_dev * dc)1116 static void cancel_writeback_rate_update_dwork(struct cached_dev *dc)
1117 {
1118 	int time_out = WRITEBACK_RATE_UPDATE_SECS_MAX * HZ;
1119 
1120 	do {
1121 		if (!test_bit(BCACHE_DEV_RATE_DW_RUNNING,
1122 			      &dc->disk.flags))
1123 			break;
1124 		time_out--;
1125 		schedule_timeout_interruptible(1);
1126 	} while (time_out > 0);
1127 
1128 	if (time_out == 0)
1129 		pr_warn("give up waiting for dc->writeback_write_update to quit\n");
1130 
1131 	cancel_delayed_work_sync(&dc->writeback_rate_update);
1132 }
1133 
cached_dev_detach_finish(struct work_struct * w)1134 static void cached_dev_detach_finish(struct work_struct *w)
1135 {
1136 	struct cached_dev *dc = container_of(w, struct cached_dev, detach);
1137 	struct cache_set *c = dc->disk.c;
1138 
1139 	BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags));
1140 	BUG_ON(refcount_read(&dc->count));
1141 
1142 
1143 	if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
1144 		cancel_writeback_rate_update_dwork(dc);
1145 
1146 	if (!IS_ERR_OR_NULL(dc->writeback_thread)) {
1147 		kthread_stop(dc->writeback_thread);
1148 		dc->writeback_thread = NULL;
1149 	}
1150 
1151 	mutex_lock(&bch_register_lock);
1152 
1153 	bcache_device_detach(&dc->disk);
1154 	list_move(&dc->list, &uncached_devices);
1155 	calc_cached_dev_sectors(c);
1156 
1157 	clear_bit(BCACHE_DEV_DETACHING, &dc->disk.flags);
1158 	clear_bit(BCACHE_DEV_UNLINK_DONE, &dc->disk.flags);
1159 
1160 	mutex_unlock(&bch_register_lock);
1161 
1162 	pr_info("Caching disabled for %pg\n", dc->bdev);
1163 
1164 	/* Drop ref we took in cached_dev_detach() */
1165 	closure_put(&dc->disk.cl);
1166 }
1167 
bch_cached_dev_detach(struct cached_dev * dc)1168 void bch_cached_dev_detach(struct cached_dev *dc)
1169 {
1170 	lockdep_assert_held(&bch_register_lock);
1171 
1172 	if (test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
1173 		return;
1174 
1175 	if (test_and_set_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
1176 		return;
1177 
1178 	/*
1179 	 * Block the device from being closed and freed until we're finished
1180 	 * detaching
1181 	 */
1182 	closure_get(&dc->disk.cl);
1183 
1184 	bch_writeback_queue(dc);
1185 
1186 	cached_dev_put(dc);
1187 }
1188 
bch_cached_dev_attach(struct cached_dev * dc,struct cache_set * c,uint8_t * set_uuid)1189 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
1190 			  uint8_t *set_uuid)
1191 {
1192 	uint32_t rtime = cpu_to_le32((u32)ktime_get_real_seconds());
1193 	struct uuid_entry *u;
1194 	struct cached_dev *exist_dc, *t;
1195 	int ret = 0;
1196 
1197 	if ((set_uuid && memcmp(set_uuid, c->set_uuid, 16)) ||
1198 	    (!set_uuid && memcmp(dc->sb.set_uuid, c->set_uuid, 16)))
1199 		return -ENOENT;
1200 
1201 	if (dc->disk.c) {
1202 		pr_err("Can't attach %pg: already attached\n", dc->bdev);
1203 		return -EINVAL;
1204 	}
1205 
1206 	if (test_bit(CACHE_SET_STOPPING, &c->flags)) {
1207 		pr_err("Can't attach %pg: shutting down\n", dc->bdev);
1208 		return -EINVAL;
1209 	}
1210 
1211 	if (dc->sb.block_size < c->cache->sb.block_size) {
1212 		/* Will die */
1213 		pr_err("Couldn't attach %pg: block size less than set's block size\n",
1214 		       dc->bdev);
1215 		return -EINVAL;
1216 	}
1217 
1218 	/* Check whether already attached */
1219 	list_for_each_entry_safe(exist_dc, t, &c->cached_devs, list) {
1220 		if (!memcmp(dc->sb.uuid, exist_dc->sb.uuid, 16)) {
1221 			pr_err("Tried to attach %pg but duplicate UUID already attached\n",
1222 				dc->bdev);
1223 
1224 			return -EINVAL;
1225 		}
1226 	}
1227 
1228 	u = uuid_find(c, dc->sb.uuid);
1229 
1230 	if (u &&
1231 	    (BDEV_STATE(&dc->sb) == BDEV_STATE_STALE ||
1232 	     BDEV_STATE(&dc->sb) == BDEV_STATE_NONE)) {
1233 		memcpy(u->uuid, invalid_uuid, 16);
1234 		u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds());
1235 		u = NULL;
1236 	}
1237 
1238 	if (!u) {
1239 		if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
1240 			pr_err("Couldn't find uuid for %pg in set\n", dc->bdev);
1241 			return -ENOENT;
1242 		}
1243 
1244 		u = uuid_find_empty(c);
1245 		if (!u) {
1246 			pr_err("Not caching %pg, no room for UUID\n", dc->bdev);
1247 			return -EINVAL;
1248 		}
1249 	}
1250 
1251 	/*
1252 	 * Deadlocks since we're called via sysfs...
1253 	 * sysfs_remove_file(&dc->kobj, &sysfs_attach);
1254 	 */
1255 
1256 	if (bch_is_zero(u->uuid, 16)) {
1257 		struct closure cl;
1258 
1259 		closure_init_stack(&cl);
1260 
1261 		memcpy(u->uuid, dc->sb.uuid, 16);
1262 		memcpy(u->label, dc->sb.label, SB_LABEL_SIZE);
1263 		u->first_reg = u->last_reg = rtime;
1264 		bch_uuid_write(c);
1265 
1266 		memcpy(dc->sb.set_uuid, c->set_uuid, 16);
1267 		SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
1268 
1269 		bch_write_bdev_super(dc, &cl);
1270 		closure_sync(&cl);
1271 	} else {
1272 		u->last_reg = rtime;
1273 		bch_uuid_write(c);
1274 	}
1275 
1276 	bcache_device_attach(&dc->disk, c, u - c->uuids);
1277 	list_move(&dc->list, &c->cached_devs);
1278 	calc_cached_dev_sectors(c);
1279 
1280 	/*
1281 	 * dc->c must be set before dc->count != 0 - paired with the mb in
1282 	 * cached_dev_get()
1283 	 */
1284 	smp_wmb();
1285 	refcount_set(&dc->count, 1);
1286 
1287 	/* Block writeback thread, but spawn it */
1288 	down_write(&dc->writeback_lock);
1289 	if (bch_cached_dev_writeback_start(dc)) {
1290 		up_write(&dc->writeback_lock);
1291 		pr_err("Couldn't start writeback facilities for %s\n",
1292 		       dc->disk.disk->disk_name);
1293 		return -ENOMEM;
1294 	}
1295 
1296 	if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
1297 		atomic_set(&dc->has_dirty, 1);
1298 		bch_writeback_queue(dc);
1299 	}
1300 
1301 	bch_sectors_dirty_init(&dc->disk);
1302 
1303 	ret = bch_cached_dev_run(dc);
1304 	if (ret && (ret != -EBUSY)) {
1305 		up_write(&dc->writeback_lock);
1306 		/*
1307 		 * bch_register_lock is held, bcache_device_stop() is not
1308 		 * able to be directly called. The kthread and kworker
1309 		 * created previously in bch_cached_dev_writeback_start()
1310 		 * have to be stopped manually here.
1311 		 */
1312 		kthread_stop(dc->writeback_thread);
1313 		cancel_writeback_rate_update_dwork(dc);
1314 		pr_err("Couldn't run cached device %pg\n", dc->bdev);
1315 		return ret;
1316 	}
1317 
1318 	bcache_device_link(&dc->disk, c, "bdev");
1319 	atomic_inc(&c->attached_dev_nr);
1320 
1321 	if (bch_has_feature_obso_large_bucket(&(c->cache->sb))) {
1322 		pr_err("The obsoleted large bucket layout is unsupported, set the bcache device into read-only\n");
1323 		pr_err("Please update to the latest bcache-tools to create the cache device\n");
1324 		set_disk_ro(dc->disk.disk, 1);
1325 	}
1326 
1327 	/* Allow the writeback thread to proceed */
1328 	up_write(&dc->writeback_lock);
1329 
1330 	pr_info("Caching %pg as %s on set %pU\n",
1331 		dc->bdev,
1332 		dc->disk.disk->disk_name,
1333 		dc->disk.c->set_uuid);
1334 	return 0;
1335 }
1336 
1337 /* when dc->disk.kobj released */
bch_cached_dev_release(struct kobject * kobj)1338 void bch_cached_dev_release(struct kobject *kobj)
1339 {
1340 	struct cached_dev *dc = container_of(kobj, struct cached_dev,
1341 					     disk.kobj);
1342 	kfree(dc);
1343 	module_put(THIS_MODULE);
1344 }
1345 
cached_dev_free(struct closure * cl)1346 static void cached_dev_free(struct closure *cl)
1347 {
1348 	struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
1349 
1350 	if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
1351 		cancel_writeback_rate_update_dwork(dc);
1352 
1353 	if (!IS_ERR_OR_NULL(dc->writeback_thread))
1354 		kthread_stop(dc->writeback_thread);
1355 	if (!IS_ERR_OR_NULL(dc->status_update_thread))
1356 		kthread_stop(dc->status_update_thread);
1357 
1358 	mutex_lock(&bch_register_lock);
1359 
1360 	if (atomic_read(&dc->running)) {
1361 		bd_unlink_disk_holder(dc->bdev, dc->disk.disk);
1362 		del_gendisk(dc->disk.disk);
1363 	}
1364 	bcache_device_free(&dc->disk);
1365 	list_del(&dc->list);
1366 
1367 	mutex_unlock(&bch_register_lock);
1368 
1369 	if (dc->sb_disk)
1370 		put_page(virt_to_page(dc->sb_disk));
1371 
1372 	if (!IS_ERR_OR_NULL(dc->bdev))
1373 		blkdev_put(dc->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
1374 
1375 	wake_up(&unregister_wait);
1376 
1377 	kobject_put(&dc->disk.kobj);
1378 }
1379 
cached_dev_flush(struct closure * cl)1380 static void cached_dev_flush(struct closure *cl)
1381 {
1382 	struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
1383 	struct bcache_device *d = &dc->disk;
1384 
1385 	mutex_lock(&bch_register_lock);
1386 	bcache_device_unlink(d);
1387 	mutex_unlock(&bch_register_lock);
1388 
1389 	bch_cache_accounting_destroy(&dc->accounting);
1390 	kobject_del(&d->kobj);
1391 
1392 	continue_at(cl, cached_dev_free, system_wq);
1393 }
1394 
cached_dev_init(struct cached_dev * dc,unsigned int block_size)1395 static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
1396 {
1397 	int ret;
1398 	struct io *io;
1399 	struct request_queue *q = bdev_get_queue(dc->bdev);
1400 
1401 	__module_get(THIS_MODULE);
1402 	INIT_LIST_HEAD(&dc->list);
1403 	closure_init(&dc->disk.cl, NULL);
1404 	set_closure_fn(&dc->disk.cl, cached_dev_flush, system_wq);
1405 	kobject_init(&dc->disk.kobj, &bch_cached_dev_ktype);
1406 	INIT_WORK(&dc->detach, cached_dev_detach_finish);
1407 	sema_init(&dc->sb_write_mutex, 1);
1408 	INIT_LIST_HEAD(&dc->io_lru);
1409 	spin_lock_init(&dc->io_lock);
1410 	bch_cache_accounting_init(&dc->accounting, &dc->disk.cl);
1411 
1412 	dc->sequential_cutoff		= 4 << 20;
1413 
1414 	for (io = dc->io; io < dc->io + RECENT_IO; io++) {
1415 		list_add(&io->lru, &dc->io_lru);
1416 		hlist_add_head(&io->hash, dc->io_hash + RECENT_IO);
1417 	}
1418 
1419 	dc->disk.stripe_size = q->limits.io_opt >> 9;
1420 
1421 	if (dc->disk.stripe_size)
1422 		dc->partial_stripes_expensive =
1423 			q->limits.raid_partial_stripes_expensive;
1424 
1425 	ret = bcache_device_init(&dc->disk, block_size,
1426 			 bdev_nr_sectors(dc->bdev) - dc->sb.data_offset,
1427 			 dc->bdev, &bcache_cached_ops);
1428 	if (ret)
1429 		return ret;
1430 
1431 	blk_queue_io_opt(dc->disk.disk->queue,
1432 		max(queue_io_opt(dc->disk.disk->queue), queue_io_opt(q)));
1433 
1434 	atomic_set(&dc->io_errors, 0);
1435 	dc->io_disable = false;
1436 	dc->error_limit = DEFAULT_CACHED_DEV_ERROR_LIMIT;
1437 	/* default to auto */
1438 	dc->stop_when_cache_set_failed = BCH_CACHED_DEV_STOP_AUTO;
1439 
1440 	bch_cached_dev_request_init(dc);
1441 	bch_cached_dev_writeback_init(dc);
1442 	return 0;
1443 }
1444 
1445 /* Cached device - bcache superblock */
1446 
register_bdev(struct cache_sb * sb,struct cache_sb_disk * sb_disk,struct block_device * bdev,struct cached_dev * dc)1447 static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
1448 				 struct block_device *bdev,
1449 				 struct cached_dev *dc)
1450 {
1451 	const char *err = "cannot allocate memory";
1452 	struct cache_set *c;
1453 	int ret = -ENOMEM;
1454 
1455 	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
1456 	dc->bdev = bdev;
1457 	dc->bdev->bd_holder = dc;
1458 	dc->sb_disk = sb_disk;
1459 
1460 	if (cached_dev_init(dc, sb->block_size << 9))
1461 		goto err;
1462 
1463 	err = "error creating kobject";
1464 	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
1465 		goto err;
1466 	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
1467 		goto err;
1468 
1469 	pr_info("registered backing device %pg\n", dc->bdev);
1470 
1471 	list_add(&dc->list, &uncached_devices);
1472 	/* attach to a matched cache set if it exists */
1473 	list_for_each_entry(c, &bch_cache_sets, list)
1474 		bch_cached_dev_attach(dc, c, NULL);
1475 
1476 	if (BDEV_STATE(&dc->sb) == BDEV_STATE_NONE ||
1477 	    BDEV_STATE(&dc->sb) == BDEV_STATE_STALE) {
1478 		err = "failed to run cached device";
1479 		ret = bch_cached_dev_run(dc);
1480 		if (ret)
1481 			goto err;
1482 	}
1483 
1484 	return 0;
1485 err:
1486 	pr_notice("error %pg: %s\n", dc->bdev, err);
1487 	bcache_device_stop(&dc->disk);
1488 	return ret;
1489 }
1490 
1491 /* Flash only volumes */
1492 
1493 /* When d->kobj released */
bch_flash_dev_release(struct kobject * kobj)1494 void bch_flash_dev_release(struct kobject *kobj)
1495 {
1496 	struct bcache_device *d = container_of(kobj, struct bcache_device,
1497 					       kobj);
1498 	kfree(d);
1499 }
1500 
flash_dev_free(struct closure * cl)1501 static void flash_dev_free(struct closure *cl)
1502 {
1503 	struct bcache_device *d = container_of(cl, struct bcache_device, cl);
1504 
1505 	mutex_lock(&bch_register_lock);
1506 	atomic_long_sub(bcache_dev_sectors_dirty(d),
1507 			&d->c->flash_dev_dirty_sectors);
1508 	del_gendisk(d->disk);
1509 	bcache_device_free(d);
1510 	mutex_unlock(&bch_register_lock);
1511 	kobject_put(&d->kobj);
1512 }
1513 
flash_dev_flush(struct closure * cl)1514 static void flash_dev_flush(struct closure *cl)
1515 {
1516 	struct bcache_device *d = container_of(cl, struct bcache_device, cl);
1517 
1518 	mutex_lock(&bch_register_lock);
1519 	bcache_device_unlink(d);
1520 	mutex_unlock(&bch_register_lock);
1521 	kobject_del(&d->kobj);
1522 	continue_at(cl, flash_dev_free, system_wq);
1523 }
1524 
flash_dev_run(struct cache_set * c,struct uuid_entry * u)1525 static int flash_dev_run(struct cache_set *c, struct uuid_entry *u)
1526 {
1527 	int err = -ENOMEM;
1528 	struct bcache_device *d = kzalloc(sizeof(struct bcache_device),
1529 					  GFP_KERNEL);
1530 	if (!d)
1531 		goto err_ret;
1532 
1533 	closure_init(&d->cl, NULL);
1534 	set_closure_fn(&d->cl, flash_dev_flush, system_wq);
1535 
1536 	kobject_init(&d->kobj, &bch_flash_dev_ktype);
1537 
1538 	if (bcache_device_init(d, block_bytes(c->cache), u->sectors,
1539 			NULL, &bcache_flash_ops))
1540 		goto err;
1541 
1542 	bcache_device_attach(d, c, u - c->uuids);
1543 	bch_sectors_dirty_init(d);
1544 	bch_flash_dev_request_init(d);
1545 	err = add_disk(d->disk);
1546 	if (err)
1547 		goto err;
1548 
1549 	err = kobject_add(&d->kobj, &disk_to_dev(d->disk)->kobj, "bcache");
1550 	if (err)
1551 		goto err;
1552 
1553 	bcache_device_link(d, c, "volume");
1554 
1555 	if (bch_has_feature_obso_large_bucket(&c->cache->sb)) {
1556 		pr_err("The obsoleted large bucket layout is unsupported, set the bcache device into read-only\n");
1557 		pr_err("Please update to the latest bcache-tools to create the cache device\n");
1558 		set_disk_ro(d->disk, 1);
1559 	}
1560 
1561 	return 0;
1562 err:
1563 	kobject_put(&d->kobj);
1564 err_ret:
1565 	return err;
1566 }
1567 
flash_devs_run(struct cache_set * c)1568 static int flash_devs_run(struct cache_set *c)
1569 {
1570 	int ret = 0;
1571 	struct uuid_entry *u;
1572 
1573 	for (u = c->uuids;
1574 	     u < c->uuids + c->nr_uuids && !ret;
1575 	     u++)
1576 		if (UUID_FLASH_ONLY(u))
1577 			ret = flash_dev_run(c, u);
1578 
1579 	return ret;
1580 }
1581 
bch_flash_dev_create(struct cache_set * c,uint64_t size)1582 int bch_flash_dev_create(struct cache_set *c, uint64_t size)
1583 {
1584 	struct uuid_entry *u;
1585 
1586 	if (test_bit(CACHE_SET_STOPPING, &c->flags))
1587 		return -EINTR;
1588 
1589 	if (!test_bit(CACHE_SET_RUNNING, &c->flags))
1590 		return -EPERM;
1591 
1592 	u = uuid_find_empty(c);
1593 	if (!u) {
1594 		pr_err("Can't create volume, no room for UUID\n");
1595 		return -EINVAL;
1596 	}
1597 
1598 	get_random_bytes(u->uuid, 16);
1599 	memset(u->label, 0, 32);
1600 	u->first_reg = u->last_reg = cpu_to_le32((u32)ktime_get_real_seconds());
1601 
1602 	SET_UUID_FLASH_ONLY(u, 1);
1603 	u->sectors = size >> 9;
1604 
1605 	bch_uuid_write(c);
1606 
1607 	return flash_dev_run(c, u);
1608 }
1609 
bch_cached_dev_error(struct cached_dev * dc)1610 bool bch_cached_dev_error(struct cached_dev *dc)
1611 {
1612 	if (!dc || test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
1613 		return false;
1614 
1615 	dc->io_disable = true;
1616 	/* make others know io_disable is true earlier */
1617 	smp_mb();
1618 
1619 	pr_err("stop %s: too many IO errors on backing device %pg\n",
1620 	       dc->disk.disk->disk_name, dc->bdev);
1621 
1622 	bcache_device_stop(&dc->disk);
1623 	return true;
1624 }
1625 
1626 /* Cache set */
1627 
1628 __printf(2, 3)
bch_cache_set_error(struct cache_set * c,const char * fmt,...)1629 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...)
1630 {
1631 	struct va_format vaf;
1632 	va_list args;
1633 
1634 	if (c->on_error != ON_ERROR_PANIC &&
1635 	    test_bit(CACHE_SET_STOPPING, &c->flags))
1636 		return false;
1637 
1638 	if (test_and_set_bit(CACHE_SET_IO_DISABLE, &c->flags))
1639 		pr_info("CACHE_SET_IO_DISABLE already set\n");
1640 
1641 	/*
1642 	 * XXX: we can be called from atomic context
1643 	 * acquire_console_sem();
1644 	 */
1645 
1646 	va_start(args, fmt);
1647 
1648 	vaf.fmt = fmt;
1649 	vaf.va = &args;
1650 
1651 	pr_err("error on %pU: %pV, disabling caching\n",
1652 	       c->set_uuid, &vaf);
1653 
1654 	va_end(args);
1655 
1656 	if (c->on_error == ON_ERROR_PANIC)
1657 		panic("panic forced after error\n");
1658 
1659 	bch_cache_set_unregister(c);
1660 	return true;
1661 }
1662 
1663 /* When c->kobj released */
bch_cache_set_release(struct kobject * kobj)1664 void bch_cache_set_release(struct kobject *kobj)
1665 {
1666 	struct cache_set *c = container_of(kobj, struct cache_set, kobj);
1667 
1668 	kfree(c);
1669 	module_put(THIS_MODULE);
1670 }
1671 
cache_set_free(struct closure * cl)1672 static void cache_set_free(struct closure *cl)
1673 {
1674 	struct cache_set *c = container_of(cl, struct cache_set, cl);
1675 	struct cache *ca;
1676 
1677 	debugfs_remove(c->debug);
1678 
1679 	bch_open_buckets_free(c);
1680 	bch_btree_cache_free(c);
1681 	bch_journal_free(c);
1682 
1683 	mutex_lock(&bch_register_lock);
1684 	bch_bset_sort_state_free(&c->sort);
1685 	free_pages((unsigned long) c->uuids, ilog2(meta_bucket_pages(&c->cache->sb)));
1686 
1687 	ca = c->cache;
1688 	if (ca) {
1689 		ca->set = NULL;
1690 		c->cache = NULL;
1691 		kobject_put(&ca->kobj);
1692 	}
1693 
1694 
1695 	if (c->moving_gc_wq)
1696 		destroy_workqueue(c->moving_gc_wq);
1697 	bioset_exit(&c->bio_split);
1698 	mempool_exit(&c->fill_iter);
1699 	mempool_exit(&c->bio_meta);
1700 	mempool_exit(&c->search);
1701 	kfree(c->devices);
1702 
1703 	list_del(&c->list);
1704 	mutex_unlock(&bch_register_lock);
1705 
1706 	pr_info("Cache set %pU unregistered\n", c->set_uuid);
1707 	wake_up(&unregister_wait);
1708 
1709 	closure_debug_destroy(&c->cl);
1710 	kobject_put(&c->kobj);
1711 }
1712 
cache_set_flush(struct closure * cl)1713 static void cache_set_flush(struct closure *cl)
1714 {
1715 	struct cache_set *c = container_of(cl, struct cache_set, caching);
1716 	struct cache *ca = c->cache;
1717 	struct btree *b;
1718 
1719 	bch_cache_accounting_destroy(&c->accounting);
1720 
1721 	kobject_put(&c->internal);
1722 	kobject_del(&c->kobj);
1723 
1724 	if (!IS_ERR_OR_NULL(c->gc_thread))
1725 		kthread_stop(c->gc_thread);
1726 
1727 	if (!IS_ERR_OR_NULL(c->root))
1728 		list_add(&c->root->list, &c->btree_cache);
1729 
1730 	/*
1731 	 * Avoid flushing cached nodes if cache set is retiring
1732 	 * due to too many I/O errors detected.
1733 	 */
1734 	if (!test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1735 		list_for_each_entry(b, &c->btree_cache, list) {
1736 			mutex_lock(&b->write_lock);
1737 			if (btree_node_dirty(b))
1738 				__bch_btree_node_write(b, NULL);
1739 			mutex_unlock(&b->write_lock);
1740 		}
1741 
1742 	if (ca->alloc_thread)
1743 		kthread_stop(ca->alloc_thread);
1744 
1745 	if (c->journal.cur) {
1746 		cancel_delayed_work_sync(&c->journal.work);
1747 		/* flush last journal entry if needed */
1748 		c->journal.work.work.func(&c->journal.work.work);
1749 	}
1750 
1751 	closure_return(cl);
1752 }
1753 
1754 /*
1755  * This function is only called when CACHE_SET_IO_DISABLE is set, which means
1756  * cache set is unregistering due to too many I/O errors. In this condition,
1757  * the bcache device might be stopped, it depends on stop_when_cache_set_failed
1758  * value and whether the broken cache has dirty data:
1759  *
1760  * dc->stop_when_cache_set_failed    dc->has_dirty   stop bcache device
1761  *  BCH_CACHED_STOP_AUTO               0               NO
1762  *  BCH_CACHED_STOP_AUTO               1               YES
1763  *  BCH_CACHED_DEV_STOP_ALWAYS         0               YES
1764  *  BCH_CACHED_DEV_STOP_ALWAYS         1               YES
1765  *
1766  * The expected behavior is, if stop_when_cache_set_failed is configured to
1767  * "auto" via sysfs interface, the bcache device will not be stopped if the
1768  * backing device is clean on the broken cache device.
1769  */
conditional_stop_bcache_device(struct cache_set * c,struct bcache_device * d,struct cached_dev * dc)1770 static void conditional_stop_bcache_device(struct cache_set *c,
1771 					   struct bcache_device *d,
1772 					   struct cached_dev *dc)
1773 {
1774 	if (dc->stop_when_cache_set_failed == BCH_CACHED_DEV_STOP_ALWAYS) {
1775 		pr_warn("stop_when_cache_set_failed of %s is \"always\", stop it for failed cache set %pU.\n",
1776 			d->disk->disk_name, c->set_uuid);
1777 		bcache_device_stop(d);
1778 	} else if (atomic_read(&dc->has_dirty)) {
1779 		/*
1780 		 * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO
1781 		 * and dc->has_dirty == 1
1782 		 */
1783 		pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is dirty, stop it to avoid potential data corruption.\n",
1784 			d->disk->disk_name);
1785 		/*
1786 		 * There might be a small time gap that cache set is
1787 		 * released but bcache device is not. Inside this time
1788 		 * gap, regular I/O requests will directly go into
1789 		 * backing device as no cache set attached to. This
1790 		 * behavior may also introduce potential inconsistence
1791 		 * data in writeback mode while cache is dirty.
1792 		 * Therefore before calling bcache_device_stop() due
1793 		 * to a broken cache device, dc->io_disable should be
1794 		 * explicitly set to true.
1795 		 */
1796 		dc->io_disable = true;
1797 		/* make others know io_disable is true earlier */
1798 		smp_mb();
1799 		bcache_device_stop(d);
1800 	} else {
1801 		/*
1802 		 * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO
1803 		 * and dc->has_dirty == 0
1804 		 */
1805 		pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is clean, keep it alive.\n",
1806 			d->disk->disk_name);
1807 	}
1808 }
1809 
__cache_set_unregister(struct closure * cl)1810 static void __cache_set_unregister(struct closure *cl)
1811 {
1812 	struct cache_set *c = container_of(cl, struct cache_set, caching);
1813 	struct cached_dev *dc;
1814 	struct bcache_device *d;
1815 	size_t i;
1816 
1817 	mutex_lock(&bch_register_lock);
1818 
1819 	for (i = 0; i < c->devices_max_used; i++) {
1820 		d = c->devices[i];
1821 		if (!d)
1822 			continue;
1823 
1824 		if (!UUID_FLASH_ONLY(&c->uuids[i]) &&
1825 		    test_bit(CACHE_SET_UNREGISTERING, &c->flags)) {
1826 			dc = container_of(d, struct cached_dev, disk);
1827 			bch_cached_dev_detach(dc);
1828 			if (test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1829 				conditional_stop_bcache_device(c, d, dc);
1830 		} else {
1831 			bcache_device_stop(d);
1832 		}
1833 	}
1834 
1835 	mutex_unlock(&bch_register_lock);
1836 
1837 	continue_at(cl, cache_set_flush, system_wq);
1838 }
1839 
bch_cache_set_stop(struct cache_set * c)1840 void bch_cache_set_stop(struct cache_set *c)
1841 {
1842 	if (!test_and_set_bit(CACHE_SET_STOPPING, &c->flags))
1843 		/* closure_fn set to __cache_set_unregister() */
1844 		closure_queue(&c->caching);
1845 }
1846 
bch_cache_set_unregister(struct cache_set * c)1847 void bch_cache_set_unregister(struct cache_set *c)
1848 {
1849 	set_bit(CACHE_SET_UNREGISTERING, &c->flags);
1850 	bch_cache_set_stop(c);
1851 }
1852 
1853 #define alloc_meta_bucket_pages(gfp, sb)		\
1854 	((void *) __get_free_pages(__GFP_ZERO|__GFP_COMP|gfp, ilog2(meta_bucket_pages(sb))))
1855 
bch_cache_set_alloc(struct cache_sb * sb)1856 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
1857 {
1858 	int iter_size;
1859 	struct cache *ca = container_of(sb, struct cache, sb);
1860 	struct cache_set *c = kzalloc(sizeof(struct cache_set), GFP_KERNEL);
1861 
1862 	if (!c)
1863 		return NULL;
1864 
1865 	__module_get(THIS_MODULE);
1866 	closure_init(&c->cl, NULL);
1867 	set_closure_fn(&c->cl, cache_set_free, system_wq);
1868 
1869 	closure_init(&c->caching, &c->cl);
1870 	set_closure_fn(&c->caching, __cache_set_unregister, system_wq);
1871 
1872 	/* Maybe create continue_at_noreturn() and use it here? */
1873 	closure_set_stopped(&c->cl);
1874 	closure_put(&c->cl);
1875 
1876 	kobject_init(&c->kobj, &bch_cache_set_ktype);
1877 	kobject_init(&c->internal, &bch_cache_set_internal_ktype);
1878 
1879 	bch_cache_accounting_init(&c->accounting, &c->cl);
1880 
1881 	memcpy(c->set_uuid, sb->set_uuid, 16);
1882 
1883 	c->cache		= ca;
1884 	c->cache->set		= c;
1885 	c->bucket_bits		= ilog2(sb->bucket_size);
1886 	c->block_bits		= ilog2(sb->block_size);
1887 	c->nr_uuids		= meta_bucket_bytes(sb) / sizeof(struct uuid_entry);
1888 	c->devices_max_used	= 0;
1889 	atomic_set(&c->attached_dev_nr, 0);
1890 	c->btree_pages		= meta_bucket_pages(sb);
1891 	if (c->btree_pages > BTREE_MAX_PAGES)
1892 		c->btree_pages = max_t(int, c->btree_pages / 4,
1893 				       BTREE_MAX_PAGES);
1894 
1895 	sema_init(&c->sb_write_mutex, 1);
1896 	mutex_init(&c->bucket_lock);
1897 	init_waitqueue_head(&c->btree_cache_wait);
1898 	spin_lock_init(&c->btree_cannibalize_lock);
1899 	init_waitqueue_head(&c->bucket_wait);
1900 	init_waitqueue_head(&c->gc_wait);
1901 	sema_init(&c->uuid_write_mutex, 1);
1902 
1903 	spin_lock_init(&c->btree_gc_time.lock);
1904 	spin_lock_init(&c->btree_split_time.lock);
1905 	spin_lock_init(&c->btree_read_time.lock);
1906 
1907 	bch_moving_init_cache_set(c);
1908 
1909 	INIT_LIST_HEAD(&c->list);
1910 	INIT_LIST_HEAD(&c->cached_devs);
1911 	INIT_LIST_HEAD(&c->btree_cache);
1912 	INIT_LIST_HEAD(&c->btree_cache_freeable);
1913 	INIT_LIST_HEAD(&c->btree_cache_freed);
1914 	INIT_LIST_HEAD(&c->data_buckets);
1915 
1916 	iter_size = ((meta_bucket_pages(sb) * PAGE_SECTORS) / sb->block_size + 1) *
1917 		sizeof(struct btree_iter_set);
1918 
1919 	c->devices = kcalloc(c->nr_uuids, sizeof(void *), GFP_KERNEL);
1920 	if (!c->devices)
1921 		goto err;
1922 
1923 	if (mempool_init_slab_pool(&c->search, 32, bch_search_cache))
1924 		goto err;
1925 
1926 	if (mempool_init_kmalloc_pool(&c->bio_meta, 2,
1927 			sizeof(struct bbio) +
1928 			sizeof(struct bio_vec) * meta_bucket_pages(sb)))
1929 		goto err;
1930 
1931 	if (mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size))
1932 		goto err;
1933 
1934 	if (bioset_init(&c->bio_split, 4, offsetof(struct bbio, bio),
1935 			BIOSET_NEED_RESCUER))
1936 		goto err;
1937 
1938 	c->uuids = alloc_meta_bucket_pages(GFP_KERNEL, sb);
1939 	if (!c->uuids)
1940 		goto err;
1941 
1942 	c->moving_gc_wq = alloc_workqueue("bcache_gc", WQ_MEM_RECLAIM, 0);
1943 	if (!c->moving_gc_wq)
1944 		goto err;
1945 
1946 	if (bch_journal_alloc(c))
1947 		goto err;
1948 
1949 	if (bch_btree_cache_alloc(c))
1950 		goto err;
1951 
1952 	if (bch_open_buckets_alloc(c))
1953 		goto err;
1954 
1955 	if (bch_bset_sort_state_init(&c->sort, ilog2(c->btree_pages)))
1956 		goto err;
1957 
1958 	c->congested_read_threshold_us	= 2000;
1959 	c->congested_write_threshold_us	= 20000;
1960 	c->error_limit	= DEFAULT_IO_ERROR_LIMIT;
1961 	c->idle_max_writeback_rate_enabled = 1;
1962 	WARN_ON(test_and_clear_bit(CACHE_SET_IO_DISABLE, &c->flags));
1963 
1964 	return c;
1965 err:
1966 	bch_cache_set_unregister(c);
1967 	return NULL;
1968 }
1969 
run_cache_set(struct cache_set * c)1970 static int run_cache_set(struct cache_set *c)
1971 {
1972 	const char *err = "cannot allocate memory";
1973 	struct cached_dev *dc, *t;
1974 	struct cache *ca = c->cache;
1975 	struct closure cl;
1976 	LIST_HEAD(journal);
1977 	struct journal_replay *l;
1978 
1979 	closure_init_stack(&cl);
1980 
1981 	c->nbuckets = ca->sb.nbuckets;
1982 	set_gc_sectors(c);
1983 
1984 	if (CACHE_SYNC(&c->cache->sb)) {
1985 		struct bkey *k;
1986 		struct jset *j;
1987 
1988 		err = "cannot allocate memory for journal";
1989 		if (bch_journal_read(c, &journal))
1990 			goto err;
1991 
1992 		pr_debug("btree_journal_read() done\n");
1993 
1994 		err = "no journal entries found";
1995 		if (list_empty(&journal))
1996 			goto err;
1997 
1998 		j = &list_entry(journal.prev, struct journal_replay, list)->j;
1999 
2000 		err = "IO error reading priorities";
2001 		if (prio_read(ca, j->prio_bucket[ca->sb.nr_this_dev]))
2002 			goto err;
2003 
2004 		/*
2005 		 * If prio_read() fails it'll call cache_set_error and we'll
2006 		 * tear everything down right away, but if we perhaps checked
2007 		 * sooner we could avoid journal replay.
2008 		 */
2009 
2010 		k = &j->btree_root;
2011 
2012 		err = "bad btree root";
2013 		if (__bch_btree_ptr_invalid(c, k))
2014 			goto err;
2015 
2016 		err = "error reading btree root";
2017 		c->root = bch_btree_node_get(c, NULL, k,
2018 					     j->btree_level,
2019 					     true, NULL);
2020 		if (IS_ERR_OR_NULL(c->root))
2021 			goto err;
2022 
2023 		list_del_init(&c->root->list);
2024 		rw_unlock(true, c->root);
2025 
2026 		err = uuid_read(c, j, &cl);
2027 		if (err)
2028 			goto err;
2029 
2030 		err = "error in recovery";
2031 		if (bch_btree_check(c))
2032 			goto err;
2033 
2034 		bch_journal_mark(c, &journal);
2035 		bch_initial_gc_finish(c);
2036 		pr_debug("btree_check() done\n");
2037 
2038 		/*
2039 		 * bcache_journal_next() can't happen sooner, or
2040 		 * btree_gc_finish() will give spurious errors about last_gc >
2041 		 * gc_gen - this is a hack but oh well.
2042 		 */
2043 		bch_journal_next(&c->journal);
2044 
2045 		err = "error starting allocator thread";
2046 		if (bch_cache_allocator_start(ca))
2047 			goto err;
2048 
2049 		/*
2050 		 * First place it's safe to allocate: btree_check() and
2051 		 * btree_gc_finish() have to run before we have buckets to
2052 		 * allocate, and bch_bucket_alloc_set() might cause a journal
2053 		 * entry to be written so bcache_journal_next() has to be called
2054 		 * first.
2055 		 *
2056 		 * If the uuids were in the old format we have to rewrite them
2057 		 * before the next journal entry is written:
2058 		 */
2059 		if (j->version < BCACHE_JSET_VERSION_UUID)
2060 			__uuid_write(c);
2061 
2062 		err = "bcache: replay journal failed";
2063 		if (bch_journal_replay(c, &journal))
2064 			goto err;
2065 	} else {
2066 		unsigned int j;
2067 
2068 		pr_notice("invalidating existing data\n");
2069 		ca->sb.keys = clamp_t(int, ca->sb.nbuckets >> 7,
2070 					2, SB_JOURNAL_BUCKETS);
2071 
2072 		for (j = 0; j < ca->sb.keys; j++)
2073 			ca->sb.d[j] = ca->sb.first_bucket + j;
2074 
2075 		bch_initial_gc_finish(c);
2076 
2077 		err = "error starting allocator thread";
2078 		if (bch_cache_allocator_start(ca))
2079 			goto err;
2080 
2081 		mutex_lock(&c->bucket_lock);
2082 		bch_prio_write(ca, true);
2083 		mutex_unlock(&c->bucket_lock);
2084 
2085 		err = "cannot allocate new UUID bucket";
2086 		if (__uuid_write(c))
2087 			goto err;
2088 
2089 		err = "cannot allocate new btree root";
2090 		c->root = __bch_btree_node_alloc(c, NULL, 0, true, NULL);
2091 		if (IS_ERR_OR_NULL(c->root))
2092 			goto err;
2093 
2094 		mutex_lock(&c->root->write_lock);
2095 		bkey_copy_key(&c->root->key, &MAX_KEY);
2096 		bch_btree_node_write(c->root, &cl);
2097 		mutex_unlock(&c->root->write_lock);
2098 
2099 		bch_btree_set_root(c->root);
2100 		rw_unlock(true, c->root);
2101 
2102 		/*
2103 		 * We don't want to write the first journal entry until
2104 		 * everything is set up - fortunately journal entries won't be
2105 		 * written until the SET_CACHE_SYNC() here:
2106 		 */
2107 		SET_CACHE_SYNC(&c->cache->sb, true);
2108 
2109 		bch_journal_next(&c->journal);
2110 		bch_journal_meta(c, &cl);
2111 	}
2112 
2113 	err = "error starting gc thread";
2114 	if (bch_gc_thread_start(c))
2115 		goto err;
2116 
2117 	closure_sync(&cl);
2118 	c->cache->sb.last_mount = (u32)ktime_get_real_seconds();
2119 	bcache_write_super(c);
2120 
2121 	if (bch_has_feature_obso_large_bucket(&c->cache->sb))
2122 		pr_err("Detect obsoleted large bucket layout, all attached bcache device will be read-only\n");
2123 
2124 	list_for_each_entry_safe(dc, t, &uncached_devices, list)
2125 		bch_cached_dev_attach(dc, c, NULL);
2126 
2127 	flash_devs_run(c);
2128 
2129 	bch_journal_space_reserve(&c->journal);
2130 	set_bit(CACHE_SET_RUNNING, &c->flags);
2131 	return 0;
2132 err:
2133 	while (!list_empty(&journal)) {
2134 		l = list_first_entry(&journal, struct journal_replay, list);
2135 		list_del(&l->list);
2136 		kfree(l);
2137 	}
2138 
2139 	closure_sync(&cl);
2140 
2141 	bch_cache_set_error(c, "%s", err);
2142 
2143 	return -EIO;
2144 }
2145 
register_cache_set(struct cache * ca)2146 static const char *register_cache_set(struct cache *ca)
2147 {
2148 	char buf[12];
2149 	const char *err = "cannot allocate memory";
2150 	struct cache_set *c;
2151 
2152 	list_for_each_entry(c, &bch_cache_sets, list)
2153 		if (!memcmp(c->set_uuid, ca->sb.set_uuid, 16)) {
2154 			if (c->cache)
2155 				return "duplicate cache set member";
2156 
2157 			goto found;
2158 		}
2159 
2160 	c = bch_cache_set_alloc(&ca->sb);
2161 	if (!c)
2162 		return err;
2163 
2164 	err = "error creating kobject";
2165 	if (kobject_add(&c->kobj, bcache_kobj, "%pU", c->set_uuid) ||
2166 	    kobject_add(&c->internal, &c->kobj, "internal"))
2167 		goto err;
2168 
2169 	if (bch_cache_accounting_add_kobjs(&c->accounting, &c->kobj))
2170 		goto err;
2171 
2172 	bch_debug_init_cache_set(c);
2173 
2174 	list_add(&c->list, &bch_cache_sets);
2175 found:
2176 	sprintf(buf, "cache%i", ca->sb.nr_this_dev);
2177 	if (sysfs_create_link(&ca->kobj, &c->kobj, "set") ||
2178 	    sysfs_create_link(&c->kobj, &ca->kobj, buf))
2179 		goto err;
2180 
2181 	kobject_get(&ca->kobj);
2182 	ca->set = c;
2183 	ca->set->cache = ca;
2184 
2185 	err = "failed to run cache set";
2186 	if (run_cache_set(c) < 0)
2187 		goto err;
2188 
2189 	return NULL;
2190 err:
2191 	bch_cache_set_unregister(c);
2192 	return err;
2193 }
2194 
2195 /* Cache device */
2196 
2197 /* When ca->kobj released */
bch_cache_release(struct kobject * kobj)2198 void bch_cache_release(struct kobject *kobj)
2199 {
2200 	struct cache *ca = container_of(kobj, struct cache, kobj);
2201 	unsigned int i;
2202 
2203 	if (ca->set) {
2204 		BUG_ON(ca->set->cache != ca);
2205 		ca->set->cache = NULL;
2206 	}
2207 
2208 	free_pages((unsigned long) ca->disk_buckets, ilog2(meta_bucket_pages(&ca->sb)));
2209 	kfree(ca->prio_buckets);
2210 	vfree(ca->buckets);
2211 
2212 	free_heap(&ca->heap);
2213 	free_fifo(&ca->free_inc);
2214 
2215 	for (i = 0; i < RESERVE_NR; i++)
2216 		free_fifo(&ca->free[i]);
2217 
2218 	if (ca->sb_disk)
2219 		put_page(virt_to_page(ca->sb_disk));
2220 
2221 	if (!IS_ERR_OR_NULL(ca->bdev))
2222 		blkdev_put(ca->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2223 
2224 	kfree(ca);
2225 	module_put(THIS_MODULE);
2226 }
2227 
cache_alloc(struct cache * ca)2228 static int cache_alloc(struct cache *ca)
2229 {
2230 	size_t free;
2231 	size_t btree_buckets;
2232 	struct bucket *b;
2233 	int ret = -ENOMEM;
2234 	const char *err = NULL;
2235 
2236 	__module_get(THIS_MODULE);
2237 	kobject_init(&ca->kobj, &bch_cache_ktype);
2238 
2239 	bio_init(&ca->journal.bio, NULL, ca->journal.bio.bi_inline_vecs, 8, 0);
2240 
2241 	/*
2242 	 * when ca->sb.njournal_buckets is not zero, journal exists,
2243 	 * and in bch_journal_replay(), tree node may split,
2244 	 * so bucket of RESERVE_BTREE type is needed,
2245 	 * the worst situation is all journal buckets are valid journal,
2246 	 * and all the keys need to replay,
2247 	 * so the number of  RESERVE_BTREE type buckets should be as much
2248 	 * as journal buckets
2249 	 */
2250 	btree_buckets = ca->sb.njournal_buckets ?: 8;
2251 	free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
2252 	if (!free) {
2253 		ret = -EPERM;
2254 		err = "ca->sb.nbuckets is too small";
2255 		goto err_free;
2256 	}
2257 
2258 	if (!init_fifo(&ca->free[RESERVE_BTREE], btree_buckets,
2259 						GFP_KERNEL)) {
2260 		err = "ca->free[RESERVE_BTREE] alloc failed";
2261 		goto err_btree_alloc;
2262 	}
2263 
2264 	if (!init_fifo_exact(&ca->free[RESERVE_PRIO], prio_buckets(ca),
2265 							GFP_KERNEL)) {
2266 		err = "ca->free[RESERVE_PRIO] alloc failed";
2267 		goto err_prio_alloc;
2268 	}
2269 
2270 	if (!init_fifo(&ca->free[RESERVE_MOVINGGC], free, GFP_KERNEL)) {
2271 		err = "ca->free[RESERVE_MOVINGGC] alloc failed";
2272 		goto err_movinggc_alloc;
2273 	}
2274 
2275 	if (!init_fifo(&ca->free[RESERVE_NONE], free, GFP_KERNEL)) {
2276 		err = "ca->free[RESERVE_NONE] alloc failed";
2277 		goto err_none_alloc;
2278 	}
2279 
2280 	if (!init_fifo(&ca->free_inc, free << 2, GFP_KERNEL)) {
2281 		err = "ca->free_inc alloc failed";
2282 		goto err_free_inc_alloc;
2283 	}
2284 
2285 	if (!init_heap(&ca->heap, free << 3, GFP_KERNEL)) {
2286 		err = "ca->heap alloc failed";
2287 		goto err_heap_alloc;
2288 	}
2289 
2290 	ca->buckets = vzalloc(array_size(sizeof(struct bucket),
2291 			      ca->sb.nbuckets));
2292 	if (!ca->buckets) {
2293 		err = "ca->buckets alloc failed";
2294 		goto err_buckets_alloc;
2295 	}
2296 
2297 	ca->prio_buckets = kzalloc(array3_size(sizeof(uint64_t),
2298 				   prio_buckets(ca), 2),
2299 				   GFP_KERNEL);
2300 	if (!ca->prio_buckets) {
2301 		err = "ca->prio_buckets alloc failed";
2302 		goto err_prio_buckets_alloc;
2303 	}
2304 
2305 	ca->disk_buckets = alloc_meta_bucket_pages(GFP_KERNEL, &ca->sb);
2306 	if (!ca->disk_buckets) {
2307 		err = "ca->disk_buckets alloc failed";
2308 		goto err_disk_buckets_alloc;
2309 	}
2310 
2311 	ca->prio_last_buckets = ca->prio_buckets + prio_buckets(ca);
2312 
2313 	for_each_bucket(b, ca)
2314 		atomic_set(&b->pin, 0);
2315 	return 0;
2316 
2317 err_disk_buckets_alloc:
2318 	kfree(ca->prio_buckets);
2319 err_prio_buckets_alloc:
2320 	vfree(ca->buckets);
2321 err_buckets_alloc:
2322 	free_heap(&ca->heap);
2323 err_heap_alloc:
2324 	free_fifo(&ca->free_inc);
2325 err_free_inc_alloc:
2326 	free_fifo(&ca->free[RESERVE_NONE]);
2327 err_none_alloc:
2328 	free_fifo(&ca->free[RESERVE_MOVINGGC]);
2329 err_movinggc_alloc:
2330 	free_fifo(&ca->free[RESERVE_PRIO]);
2331 err_prio_alloc:
2332 	free_fifo(&ca->free[RESERVE_BTREE]);
2333 err_btree_alloc:
2334 err_free:
2335 	module_put(THIS_MODULE);
2336 	if (err)
2337 		pr_notice("error %pg: %s\n", ca->bdev, err);
2338 	return ret;
2339 }
2340 
register_cache(struct cache_sb * sb,struct cache_sb_disk * sb_disk,struct block_device * bdev,struct cache * ca)2341 static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
2342 				struct block_device *bdev, struct cache *ca)
2343 {
2344 	const char *err = NULL; /* must be set for any error case */
2345 	int ret = 0;
2346 
2347 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
2348 	ca->bdev = bdev;
2349 	ca->bdev->bd_holder = ca;
2350 	ca->sb_disk = sb_disk;
2351 
2352 	if (bdev_max_discard_sectors((bdev)))
2353 		ca->discard = CACHE_DISCARD(&ca->sb);
2354 
2355 	ret = cache_alloc(ca);
2356 	if (ret != 0) {
2357 		/*
2358 		 * If we failed here, it means ca->kobj is not initialized yet,
2359 		 * kobject_put() won't be called and there is no chance to
2360 		 * call blkdev_put() to bdev in bch_cache_release(). So we
2361 		 * explicitly call blkdev_put() here.
2362 		 */
2363 		blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2364 		if (ret == -ENOMEM)
2365 			err = "cache_alloc(): -ENOMEM";
2366 		else if (ret == -EPERM)
2367 			err = "cache_alloc(): cache device is too small";
2368 		else
2369 			err = "cache_alloc(): unknown error";
2370 		goto err;
2371 	}
2372 
2373 	if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
2374 		err = "error calling kobject_add";
2375 		ret = -ENOMEM;
2376 		goto out;
2377 	}
2378 
2379 	mutex_lock(&bch_register_lock);
2380 	err = register_cache_set(ca);
2381 	mutex_unlock(&bch_register_lock);
2382 
2383 	if (err) {
2384 		ret = -ENODEV;
2385 		goto out;
2386 	}
2387 
2388 	pr_info("registered cache device %pg\n", ca->bdev);
2389 
2390 out:
2391 	kobject_put(&ca->kobj);
2392 
2393 err:
2394 	if (err)
2395 		pr_notice("error %pg: %s\n", ca->bdev, err);
2396 
2397 	return ret;
2398 }
2399 
2400 /* Global interfaces/init */
2401 
2402 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
2403 			       const char *buffer, size_t size);
2404 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k,
2405 					 struct kobj_attribute *attr,
2406 					 const char *buffer, size_t size);
2407 
2408 kobj_attribute_write(register,		register_bcache);
2409 kobj_attribute_write(register_quiet,	register_bcache);
2410 kobj_attribute_write(pendings_cleanup,	bch_pending_bdevs_cleanup);
2411 
bch_is_open_backing(dev_t dev)2412 static bool bch_is_open_backing(dev_t dev)
2413 {
2414 	struct cache_set *c, *tc;
2415 	struct cached_dev *dc, *t;
2416 
2417 	list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2418 		list_for_each_entry_safe(dc, t, &c->cached_devs, list)
2419 			if (dc->bdev->bd_dev == dev)
2420 				return true;
2421 	list_for_each_entry_safe(dc, t, &uncached_devices, list)
2422 		if (dc->bdev->bd_dev == dev)
2423 			return true;
2424 	return false;
2425 }
2426 
bch_is_open_cache(dev_t dev)2427 static bool bch_is_open_cache(dev_t dev)
2428 {
2429 	struct cache_set *c, *tc;
2430 
2431 	list_for_each_entry_safe(c, tc, &bch_cache_sets, list) {
2432 		struct cache *ca = c->cache;
2433 
2434 		if (ca->bdev->bd_dev == dev)
2435 			return true;
2436 	}
2437 
2438 	return false;
2439 }
2440 
bch_is_open(dev_t dev)2441 static bool bch_is_open(dev_t dev)
2442 {
2443 	return bch_is_open_cache(dev) || bch_is_open_backing(dev);
2444 }
2445 
2446 struct async_reg_args {
2447 	struct delayed_work reg_work;
2448 	char *path;
2449 	struct cache_sb *sb;
2450 	struct cache_sb_disk *sb_disk;
2451 	struct block_device *bdev;
2452 };
2453 
register_bdev_worker(struct work_struct * work)2454 static void register_bdev_worker(struct work_struct *work)
2455 {
2456 	int fail = false;
2457 	struct async_reg_args *args =
2458 		container_of(work, struct async_reg_args, reg_work.work);
2459 	struct cached_dev *dc;
2460 
2461 	dc = kzalloc(sizeof(*dc), GFP_KERNEL);
2462 	if (!dc) {
2463 		fail = true;
2464 		put_page(virt_to_page(args->sb_disk));
2465 		blkdev_put(args->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
2466 		goto out;
2467 	}
2468 
2469 	mutex_lock(&bch_register_lock);
2470 	if (register_bdev(args->sb, args->sb_disk, args->bdev, dc) < 0)
2471 		fail = true;
2472 	mutex_unlock(&bch_register_lock);
2473 
2474 out:
2475 	if (fail)
2476 		pr_info("error %s: fail to register backing device\n",
2477 			args->path);
2478 	kfree(args->sb);
2479 	kfree(args->path);
2480 	kfree(args);
2481 	module_put(THIS_MODULE);
2482 }
2483 
register_cache_worker(struct work_struct * work)2484 static void register_cache_worker(struct work_struct *work)
2485 {
2486 	int fail = false;
2487 	struct async_reg_args *args =
2488 		container_of(work, struct async_reg_args, reg_work.work);
2489 	struct cache *ca;
2490 
2491 	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2492 	if (!ca) {
2493 		fail = true;
2494 		put_page(virt_to_page(args->sb_disk));
2495 		blkdev_put(args->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
2496 		goto out;
2497 	}
2498 
2499 	/* blkdev_put() will be called in bch_cache_release() */
2500 	if (register_cache(args->sb, args->sb_disk, args->bdev, ca) != 0)
2501 		fail = true;
2502 
2503 out:
2504 	if (fail)
2505 		pr_info("error %s: fail to register cache device\n",
2506 			args->path);
2507 	kfree(args->sb);
2508 	kfree(args->path);
2509 	kfree(args);
2510 	module_put(THIS_MODULE);
2511 }
2512 
register_device_async(struct async_reg_args * args)2513 static void register_device_async(struct async_reg_args *args)
2514 {
2515 	if (SB_IS_BDEV(args->sb))
2516 		INIT_DELAYED_WORK(&args->reg_work, register_bdev_worker);
2517 	else
2518 		INIT_DELAYED_WORK(&args->reg_work, register_cache_worker);
2519 
2520 	/* 10 jiffies is enough for a delay */
2521 	queue_delayed_work(system_wq, &args->reg_work, 10);
2522 }
2523 
register_bcache(struct kobject * k,struct kobj_attribute * attr,const char * buffer,size_t size)2524 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
2525 			       const char *buffer, size_t size)
2526 {
2527 	const char *err;
2528 	char *path = NULL;
2529 	struct cache_sb *sb;
2530 	struct cache_sb_disk *sb_disk;
2531 	struct block_device *bdev;
2532 	ssize_t ret;
2533 	bool async_registration = false;
2534 
2535 #ifdef CONFIG_BCACHE_ASYNC_REGISTRATION
2536 	async_registration = true;
2537 #endif
2538 
2539 	ret = -EBUSY;
2540 	err = "failed to reference bcache module";
2541 	if (!try_module_get(THIS_MODULE))
2542 		goto out;
2543 
2544 	/* For latest state of bcache_is_reboot */
2545 	smp_mb();
2546 	err = "bcache is in reboot";
2547 	if (bcache_is_reboot)
2548 		goto out_module_put;
2549 
2550 	ret = -ENOMEM;
2551 	err = "cannot allocate memory";
2552 	path = kstrndup(buffer, size, GFP_KERNEL);
2553 	if (!path)
2554 		goto out_module_put;
2555 
2556 	sb = kmalloc(sizeof(struct cache_sb), GFP_KERNEL);
2557 	if (!sb)
2558 		goto out_free_path;
2559 
2560 	ret = -EINVAL;
2561 	err = "failed to open device";
2562 	bdev = blkdev_get_by_path(strim(path),
2563 				  FMODE_READ|FMODE_WRITE|FMODE_EXCL,
2564 				  sb);
2565 	if (IS_ERR(bdev)) {
2566 		if (bdev == ERR_PTR(-EBUSY)) {
2567 			dev_t dev;
2568 
2569 			mutex_lock(&bch_register_lock);
2570 			if (lookup_bdev(strim(path), &dev) == 0 &&
2571 			    bch_is_open(dev))
2572 				err = "device already registered";
2573 			else
2574 				err = "device busy";
2575 			mutex_unlock(&bch_register_lock);
2576 			if (attr == &ksysfs_register_quiet)
2577 				goto done;
2578 		}
2579 		goto out_free_sb;
2580 	}
2581 
2582 	err = "failed to set blocksize";
2583 	if (set_blocksize(bdev, 4096))
2584 		goto out_blkdev_put;
2585 
2586 	err = read_super(sb, bdev, &sb_disk);
2587 	if (err)
2588 		goto out_blkdev_put;
2589 
2590 	err = "failed to register device";
2591 
2592 	if (async_registration) {
2593 		/* register in asynchronous way */
2594 		struct async_reg_args *args =
2595 			kzalloc(sizeof(struct async_reg_args), GFP_KERNEL);
2596 
2597 		if (!args) {
2598 			ret = -ENOMEM;
2599 			err = "cannot allocate memory";
2600 			goto out_put_sb_page;
2601 		}
2602 
2603 		args->path	= path;
2604 		args->sb	= sb;
2605 		args->sb_disk	= sb_disk;
2606 		args->bdev	= bdev;
2607 		register_device_async(args);
2608 		/* No wait and returns to user space */
2609 		goto async_done;
2610 	}
2611 
2612 	if (SB_IS_BDEV(sb)) {
2613 		struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL);
2614 
2615 		if (!dc) {
2616 			ret = -ENOMEM;
2617 			err = "cannot allocate memory";
2618 			goto out_put_sb_page;
2619 		}
2620 
2621 		mutex_lock(&bch_register_lock);
2622 		ret = register_bdev(sb, sb_disk, bdev, dc);
2623 		mutex_unlock(&bch_register_lock);
2624 		/* blkdev_put() will be called in cached_dev_free() */
2625 		if (ret < 0)
2626 			goto out_free_sb;
2627 	} else {
2628 		struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2629 
2630 		if (!ca) {
2631 			ret = -ENOMEM;
2632 			err = "cannot allocate memory";
2633 			goto out_put_sb_page;
2634 		}
2635 
2636 		/* blkdev_put() will be called in bch_cache_release() */
2637 		ret = register_cache(sb, sb_disk, bdev, ca);
2638 		if (ret)
2639 			goto out_free_sb;
2640 	}
2641 
2642 done:
2643 	kfree(sb);
2644 	kfree(path);
2645 	module_put(THIS_MODULE);
2646 async_done:
2647 	return size;
2648 
2649 out_put_sb_page:
2650 	put_page(virt_to_page(sb_disk));
2651 out_blkdev_put:
2652 	blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
2653 out_free_sb:
2654 	kfree(sb);
2655 out_free_path:
2656 	kfree(path);
2657 	path = NULL;
2658 out_module_put:
2659 	module_put(THIS_MODULE);
2660 out:
2661 	pr_info("error %s: %s\n", path?path:"", err);
2662 	return ret;
2663 }
2664 
2665 
2666 struct pdev {
2667 	struct list_head list;
2668 	struct cached_dev *dc;
2669 };
2670 
bch_pending_bdevs_cleanup(struct kobject * k,struct kobj_attribute * attr,const char * buffer,size_t size)2671 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k,
2672 					 struct kobj_attribute *attr,
2673 					 const char *buffer,
2674 					 size_t size)
2675 {
2676 	LIST_HEAD(pending_devs);
2677 	ssize_t ret = size;
2678 	struct cached_dev *dc, *tdc;
2679 	struct pdev *pdev, *tpdev;
2680 	struct cache_set *c, *tc;
2681 
2682 	mutex_lock(&bch_register_lock);
2683 	list_for_each_entry_safe(dc, tdc, &uncached_devices, list) {
2684 		pdev = kmalloc(sizeof(struct pdev), GFP_KERNEL);
2685 		if (!pdev)
2686 			break;
2687 		pdev->dc = dc;
2688 		list_add(&pdev->list, &pending_devs);
2689 	}
2690 
2691 	list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) {
2692 		char *pdev_set_uuid = pdev->dc->sb.set_uuid;
2693 		list_for_each_entry_safe(c, tc, &bch_cache_sets, list) {
2694 			char *set_uuid = c->set_uuid;
2695 
2696 			if (!memcmp(pdev_set_uuid, set_uuid, 16)) {
2697 				list_del(&pdev->list);
2698 				kfree(pdev);
2699 				break;
2700 			}
2701 		}
2702 	}
2703 	mutex_unlock(&bch_register_lock);
2704 
2705 	list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) {
2706 		pr_info("delete pdev %p\n", pdev);
2707 		list_del(&pdev->list);
2708 		bcache_device_stop(&pdev->dc->disk);
2709 		kfree(pdev);
2710 	}
2711 
2712 	return ret;
2713 }
2714 
bcache_reboot(struct notifier_block * n,unsigned long code,void * x)2715 static int bcache_reboot(struct notifier_block *n, unsigned long code, void *x)
2716 {
2717 	if (bcache_is_reboot)
2718 		return NOTIFY_DONE;
2719 
2720 	if (code == SYS_DOWN ||
2721 	    code == SYS_HALT ||
2722 	    code == SYS_POWER_OFF) {
2723 		DEFINE_WAIT(wait);
2724 		unsigned long start = jiffies;
2725 		bool stopped = false;
2726 
2727 		struct cache_set *c, *tc;
2728 		struct cached_dev *dc, *tdc;
2729 
2730 		mutex_lock(&bch_register_lock);
2731 
2732 		if (bcache_is_reboot)
2733 			goto out;
2734 
2735 		/* New registration is rejected since now */
2736 		bcache_is_reboot = true;
2737 		/*
2738 		 * Make registering caller (if there is) on other CPU
2739 		 * core know bcache_is_reboot set to true earlier
2740 		 */
2741 		smp_mb();
2742 
2743 		if (list_empty(&bch_cache_sets) &&
2744 		    list_empty(&uncached_devices))
2745 			goto out;
2746 
2747 		mutex_unlock(&bch_register_lock);
2748 
2749 		pr_info("Stopping all devices:\n");
2750 
2751 		/*
2752 		 * The reason bch_register_lock is not held to call
2753 		 * bch_cache_set_stop() and bcache_device_stop() is to
2754 		 * avoid potential deadlock during reboot, because cache
2755 		 * set or bcache device stopping process will acquire
2756 		 * bch_register_lock too.
2757 		 *
2758 		 * We are safe here because bcache_is_reboot sets to
2759 		 * true already, register_bcache() will reject new
2760 		 * registration now. bcache_is_reboot also makes sure
2761 		 * bcache_reboot() won't be re-entered on by other thread,
2762 		 * so there is no race in following list iteration by
2763 		 * list_for_each_entry_safe().
2764 		 */
2765 		list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2766 			bch_cache_set_stop(c);
2767 
2768 		list_for_each_entry_safe(dc, tdc, &uncached_devices, list)
2769 			bcache_device_stop(&dc->disk);
2770 
2771 
2772 		/*
2773 		 * Give an early chance for other kthreads and
2774 		 * kworkers to stop themselves
2775 		 */
2776 		schedule();
2777 
2778 		/* What's a condition variable? */
2779 		while (1) {
2780 			long timeout = start + 10 * HZ - jiffies;
2781 
2782 			mutex_lock(&bch_register_lock);
2783 			stopped = list_empty(&bch_cache_sets) &&
2784 				list_empty(&uncached_devices);
2785 
2786 			if (timeout < 0 || stopped)
2787 				break;
2788 
2789 			prepare_to_wait(&unregister_wait, &wait,
2790 					TASK_UNINTERRUPTIBLE);
2791 
2792 			mutex_unlock(&bch_register_lock);
2793 			schedule_timeout(timeout);
2794 		}
2795 
2796 		finish_wait(&unregister_wait, &wait);
2797 
2798 		if (stopped)
2799 			pr_info("All devices stopped\n");
2800 		else
2801 			pr_notice("Timeout waiting for devices to be closed\n");
2802 out:
2803 		mutex_unlock(&bch_register_lock);
2804 	}
2805 
2806 	return NOTIFY_DONE;
2807 }
2808 
2809 static struct notifier_block reboot = {
2810 	.notifier_call	= bcache_reboot,
2811 	.priority	= INT_MAX, /* before any real devices */
2812 };
2813 
bcache_exit(void)2814 static void bcache_exit(void)
2815 {
2816 	bch_debug_exit();
2817 	bch_request_exit();
2818 	if (bcache_kobj)
2819 		kobject_put(bcache_kobj);
2820 	if (bcache_wq)
2821 		destroy_workqueue(bcache_wq);
2822 	if (bch_journal_wq)
2823 		destroy_workqueue(bch_journal_wq);
2824 	if (bch_flush_wq)
2825 		destroy_workqueue(bch_flush_wq);
2826 	bch_btree_exit();
2827 
2828 	if (bcache_major)
2829 		unregister_blkdev(bcache_major, "bcache");
2830 	unregister_reboot_notifier(&reboot);
2831 	mutex_destroy(&bch_register_lock);
2832 }
2833 
2834 /* Check and fixup module parameters */
check_module_parameters(void)2835 static void check_module_parameters(void)
2836 {
2837 	if (bch_cutoff_writeback_sync == 0)
2838 		bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC;
2839 	else if (bch_cutoff_writeback_sync > CUTOFF_WRITEBACK_SYNC_MAX) {
2840 		pr_warn("set bch_cutoff_writeback_sync (%u) to max value %u\n",
2841 			bch_cutoff_writeback_sync, CUTOFF_WRITEBACK_SYNC_MAX);
2842 		bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC_MAX;
2843 	}
2844 
2845 	if (bch_cutoff_writeback == 0)
2846 		bch_cutoff_writeback = CUTOFF_WRITEBACK;
2847 	else if (bch_cutoff_writeback > CUTOFF_WRITEBACK_MAX) {
2848 		pr_warn("set bch_cutoff_writeback (%u) to max value %u\n",
2849 			bch_cutoff_writeback, CUTOFF_WRITEBACK_MAX);
2850 		bch_cutoff_writeback = CUTOFF_WRITEBACK_MAX;
2851 	}
2852 
2853 	if (bch_cutoff_writeback > bch_cutoff_writeback_sync) {
2854 		pr_warn("set bch_cutoff_writeback (%u) to %u\n",
2855 			bch_cutoff_writeback, bch_cutoff_writeback_sync);
2856 		bch_cutoff_writeback = bch_cutoff_writeback_sync;
2857 	}
2858 }
2859 
bcache_init(void)2860 static int __init bcache_init(void)
2861 {
2862 	static const struct attribute *files[] = {
2863 		&ksysfs_register.attr,
2864 		&ksysfs_register_quiet.attr,
2865 		&ksysfs_pendings_cleanup.attr,
2866 		NULL
2867 	};
2868 
2869 	check_module_parameters();
2870 
2871 	mutex_init(&bch_register_lock);
2872 	init_waitqueue_head(&unregister_wait);
2873 	register_reboot_notifier(&reboot);
2874 
2875 	bcache_major = register_blkdev(0, "bcache");
2876 	if (bcache_major < 0) {
2877 		unregister_reboot_notifier(&reboot);
2878 		mutex_destroy(&bch_register_lock);
2879 		return bcache_major;
2880 	}
2881 
2882 	if (bch_btree_init())
2883 		goto err;
2884 
2885 	bcache_wq = alloc_workqueue("bcache", WQ_MEM_RECLAIM, 0);
2886 	if (!bcache_wq)
2887 		goto err;
2888 
2889 	/*
2890 	 * Let's not make this `WQ_MEM_RECLAIM` for the following reasons:
2891 	 *
2892 	 * 1. It used `system_wq` before which also does no memory reclaim.
2893 	 * 2. With `WQ_MEM_RECLAIM` desktop stalls, increased boot times, and
2894 	 *    reduced throughput can be observed.
2895 	 *
2896 	 * We still want to user our own queue to not congest the `system_wq`.
2897 	 */
2898 	bch_flush_wq = alloc_workqueue("bch_flush", 0, 0);
2899 	if (!bch_flush_wq)
2900 		goto err;
2901 
2902 	bch_journal_wq = alloc_workqueue("bch_journal", WQ_MEM_RECLAIM, 0);
2903 	if (!bch_journal_wq)
2904 		goto err;
2905 
2906 	bcache_kobj = kobject_create_and_add("bcache", fs_kobj);
2907 	if (!bcache_kobj)
2908 		goto err;
2909 
2910 	if (bch_request_init() ||
2911 	    sysfs_create_files(bcache_kobj, files))
2912 		goto err;
2913 
2914 	bch_debug_init();
2915 	closure_debug_init();
2916 
2917 	bcache_is_reboot = false;
2918 
2919 	return 0;
2920 err:
2921 	bcache_exit();
2922 	return -ENOMEM;
2923 }
2924 
2925 /*
2926  * Module hooks
2927  */
2928 module_exit(bcache_exit);
2929 module_init(bcache_init);
2930 
2931 module_param(bch_cutoff_writeback, uint, 0);
2932 MODULE_PARM_DESC(bch_cutoff_writeback, "threshold to cutoff writeback");
2933 
2934 module_param(bch_cutoff_writeback_sync, uint, 0);
2935 MODULE_PARM_DESC(bch_cutoff_writeback_sync, "hard threshold to cutoff writeback");
2936 
2937 MODULE_DESCRIPTION("Bcache: a Linux block layer cache");
2938 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>");
2939 MODULE_LICENSE("GPL");
2940