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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/genhd.h>
22 #include <linux/idr.h>
23 #include <linux/kthread.h>
24 #include <linux/workqueue.h>
25 #include <linux/module.h>
26 #include <linux/random.h>
27 #include <linux/reboot.h>
28 #include <linux/sysfs.h>
29 
30 unsigned int bch_cutoff_writeback;
31 unsigned int bch_cutoff_writeback_sync;
32 
33 static const char bcache_magic[] = {
34 	0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
35 	0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81
36 };
37 
38 static const char invalid_uuid[] = {
39 	0xa0, 0x3e, 0xf8, 0xed, 0x3e, 0xe1, 0xb8, 0x78,
40 	0xc8, 0x50, 0xfc, 0x5e, 0xcb, 0x16, 0xcd, 0x99
41 };
42 
43 static struct kobject *bcache_kobj;
44 struct mutex bch_register_lock;
45 bool bcache_is_reboot;
46 LIST_HEAD(bch_cache_sets);
47 static LIST_HEAD(uncached_devices);
48 
49 static int bcache_major;
50 static DEFINE_IDA(bcache_device_idx);
51 static wait_queue_head_t unregister_wait;
52 struct workqueue_struct *bcache_wq;
53 struct workqueue_struct *bch_flush_wq;
54 struct workqueue_struct *bch_journal_wq;
55 
56 
57 #define BTREE_MAX_PAGES		(256 * 1024 / PAGE_SIZE)
58 /* limitation of partitions number on single bcache device */
59 #define BCACHE_MINORS		128
60 /* limitation of bcache devices number on single system */
61 #define BCACHE_DEVICE_IDX_MAX	((1U << MINORBITS)/BCACHE_MINORS)
62 
63 /* Superblock */
64 
get_bucket_size(struct cache_sb * sb,struct cache_sb_disk * s)65 static unsigned int get_bucket_size(struct cache_sb *sb, struct cache_sb_disk *s)
66 {
67 	unsigned int bucket_size = le16_to_cpu(s->bucket_size);
68 
69 	if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES) {
70 		if (bch_has_feature_large_bucket(sb)) {
71 			unsigned int max, order;
72 
73 			max = sizeof(unsigned int) * BITS_PER_BYTE - 1;
74 			order = le16_to_cpu(s->bucket_size);
75 			/*
76 			 * bcache tool will make sure the overflow won't
77 			 * happen, an error message here is enough.
78 			 */
79 			if (order > max)
80 				pr_err("Bucket size (1 << %u) overflows\n",
81 					order);
82 			bucket_size = 1 << order;
83 		} else if (bch_has_feature_obso_large_bucket(sb)) {
84 			bucket_size +=
85 				le16_to_cpu(s->obso_bucket_size_hi) << 16;
86 		}
87 	}
88 
89 	return bucket_size;
90 }
91 
read_super_common(struct cache_sb * sb,struct block_device * bdev,struct cache_sb_disk * s)92 static const char *read_super_common(struct cache_sb *sb,  struct block_device *bdev,
93 				     struct cache_sb_disk *s)
94 {
95 	const char *err;
96 	unsigned int i;
97 
98 	sb->first_bucket= le16_to_cpu(s->first_bucket);
99 	sb->nbuckets	= le64_to_cpu(s->nbuckets);
100 	sb->bucket_size	= get_bucket_size(sb, s);
101 
102 	sb->nr_in_set	= le16_to_cpu(s->nr_in_set);
103 	sb->nr_this_dev	= le16_to_cpu(s->nr_this_dev);
104 
105 	err = "Too many journal buckets";
106 	if (sb->keys > SB_JOURNAL_BUCKETS)
107 		goto err;
108 
109 	err = "Too many buckets";
110 	if (sb->nbuckets > LONG_MAX)
111 		goto err;
112 
113 	err = "Not enough buckets";
114 	if (sb->nbuckets < 1 << 7)
115 		goto err;
116 
117 	err = "Bad block size (not power of 2)";
118 	if (!is_power_of_2(sb->block_size))
119 		goto err;
120 
121 	err = "Bad block size (larger than page size)";
122 	if (sb->block_size > PAGE_SECTORS)
123 		goto err;
124 
125 	err = "Bad bucket size (not power of 2)";
126 	if (!is_power_of_2(sb->bucket_size))
127 		goto err;
128 
129 	err = "Bad bucket size (smaller than page size)";
130 	if (sb->bucket_size < PAGE_SECTORS)
131 		goto err;
132 
133 	err = "Invalid superblock: device too small";
134 	if (get_capacity(bdev->bd_disk) <
135 	    sb->bucket_size * sb->nbuckets)
136 		goto err;
137 
138 	err = "Bad UUID";
139 	if (bch_is_zero(sb->set_uuid, 16))
140 		goto err;
141 
142 	err = "Bad cache device number in set";
143 	if (!sb->nr_in_set ||
144 	    sb->nr_in_set <= sb->nr_this_dev ||
145 	    sb->nr_in_set > MAX_CACHES_PER_SET)
146 		goto err;
147 
148 	err = "Journal buckets not sequential";
149 	for (i = 0; i < sb->keys; i++)
150 		if (sb->d[i] != sb->first_bucket + i)
151 			goto err;
152 
153 	err = "Too many journal buckets";
154 	if (sb->first_bucket + sb->keys > sb->nbuckets)
155 		goto err;
156 
157 	err = "Invalid superblock: first bucket comes before end of super";
158 	if (sb->first_bucket * sb->bucket_size < 16)
159 		goto err;
160 
161 	err = NULL;
162 err:
163 	return err;
164 }
165 
166 
read_super(struct cache_sb * sb,struct block_device * bdev,struct cache_sb_disk ** res)167 static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
168 			      struct cache_sb_disk **res)
169 {
170 	const char *err;
171 	struct cache_sb_disk *s;
172 	struct page *page;
173 	unsigned int i;
174 
175 	page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
176 				   SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
177 	if (IS_ERR(page))
178 		return "IO error";
179 	s = page_address(page) + offset_in_page(SB_OFFSET);
180 
181 	sb->offset		= le64_to_cpu(s->offset);
182 	sb->version		= le64_to_cpu(s->version);
183 
184 	memcpy(sb->magic,	s->magic, 16);
185 	memcpy(sb->uuid,	s->uuid, 16);
186 	memcpy(sb->set_uuid,	s->set_uuid, 16);
187 	memcpy(sb->label,	s->label, SB_LABEL_SIZE);
188 
189 	sb->flags		= le64_to_cpu(s->flags);
190 	sb->seq			= le64_to_cpu(s->seq);
191 	sb->last_mount		= le32_to_cpu(s->last_mount);
192 	sb->keys		= le16_to_cpu(s->keys);
193 
194 	for (i = 0; i < SB_JOURNAL_BUCKETS; i++)
195 		sb->d[i] = le64_to_cpu(s->d[i]);
196 
197 	pr_debug("read sb version %llu, flags %llu, seq %llu, journal size %u\n",
198 		 sb->version, sb->flags, sb->seq, sb->keys);
199 
200 	err = "Not a bcache superblock (bad offset)";
201 	if (sb->offset != SB_SECTOR)
202 		goto err;
203 
204 	err = "Not a bcache superblock (bad magic)";
205 	if (memcmp(sb->magic, bcache_magic, 16))
206 		goto err;
207 
208 	err = "Bad checksum";
209 	if (s->csum != csum_set(s))
210 		goto err;
211 
212 	err = "Bad UUID";
213 	if (bch_is_zero(sb->uuid, 16))
214 		goto err;
215 
216 	sb->block_size	= le16_to_cpu(s->block_size);
217 
218 	err = "Superblock block size smaller than device block size";
219 	if (sb->block_size << 9 < bdev_logical_block_size(bdev))
220 		goto err;
221 
222 	switch (sb->version) {
223 	case BCACHE_SB_VERSION_BDEV:
224 		sb->data_offset	= BDEV_DATA_START_DEFAULT;
225 		break;
226 	case BCACHE_SB_VERSION_BDEV_WITH_OFFSET:
227 	case BCACHE_SB_VERSION_BDEV_WITH_FEATURES:
228 		sb->data_offset	= le64_to_cpu(s->data_offset);
229 
230 		err = "Bad data offset";
231 		if (sb->data_offset < BDEV_DATA_START_DEFAULT)
232 			goto err;
233 
234 		break;
235 	case BCACHE_SB_VERSION_CDEV:
236 	case BCACHE_SB_VERSION_CDEV_WITH_UUID:
237 		err = read_super_common(sb, bdev, s);
238 		if (err)
239 			goto err;
240 		break;
241 	case BCACHE_SB_VERSION_CDEV_WITH_FEATURES:
242 		/*
243 		 * Feature bits are needed in read_super_common(),
244 		 * convert them firstly.
245 		 */
246 		sb->feature_compat = le64_to_cpu(s->feature_compat);
247 		sb->feature_incompat = le64_to_cpu(s->feature_incompat);
248 		sb->feature_ro_compat = le64_to_cpu(s->feature_ro_compat);
249 
250 		/* Check incompatible features */
251 		err = "Unsupported compatible feature found";
252 		if (bch_has_unknown_compat_features(sb))
253 			goto err;
254 
255 		err = "Unsupported read-only compatible feature found";
256 		if (bch_has_unknown_ro_compat_features(sb))
257 			goto err;
258 
259 		err = "Unsupported incompatible feature found";
260 		if (bch_has_unknown_incompat_features(sb))
261 			goto err;
262 
263 		err = read_super_common(sb, bdev, s);
264 		if (err)
265 			goto err;
266 		break;
267 	default:
268 		err = "Unsupported superblock version";
269 		goto err;
270 	}
271 
272 	sb->last_mount = (u32)ktime_get_real_seconds();
273 	*res = s;
274 	return NULL;
275 err:
276 	put_page(page);
277 	return err;
278 }
279 
write_bdev_super_endio(struct bio * bio)280 static void write_bdev_super_endio(struct bio *bio)
281 {
282 	struct cached_dev *dc = bio->bi_private;
283 
284 	if (bio->bi_status)
285 		bch_count_backing_io_errors(dc, bio);
286 
287 	closure_put(&dc->sb_write);
288 }
289 
__write_super(struct cache_sb * sb,struct cache_sb_disk * out,struct bio * bio)290 static void __write_super(struct cache_sb *sb, struct cache_sb_disk *out,
291 		struct bio *bio)
292 {
293 	unsigned int i;
294 
295 	bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_META;
296 	bio->bi_iter.bi_sector	= SB_SECTOR;
297 	__bio_add_page(bio, virt_to_page(out), SB_SIZE,
298 			offset_in_page(out));
299 
300 	out->offset		= cpu_to_le64(sb->offset);
301 
302 	memcpy(out->uuid,	sb->uuid, 16);
303 	memcpy(out->set_uuid,	sb->set_uuid, 16);
304 	memcpy(out->label,	sb->label, SB_LABEL_SIZE);
305 
306 	out->flags		= cpu_to_le64(sb->flags);
307 	out->seq		= cpu_to_le64(sb->seq);
308 
309 	out->last_mount		= cpu_to_le32(sb->last_mount);
310 	out->first_bucket	= cpu_to_le16(sb->first_bucket);
311 	out->keys		= cpu_to_le16(sb->keys);
312 
313 	for (i = 0; i < sb->keys; i++)
314 		out->d[i] = cpu_to_le64(sb->d[i]);
315 
316 	if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES) {
317 		out->feature_compat    = cpu_to_le64(sb->feature_compat);
318 		out->feature_incompat  = cpu_to_le64(sb->feature_incompat);
319 		out->feature_ro_compat = cpu_to_le64(sb->feature_ro_compat);
320 	}
321 
322 	out->version		= cpu_to_le64(sb->version);
323 	out->csum = csum_set(out);
324 
325 	pr_debug("ver %llu, flags %llu, seq %llu\n",
326 		 sb->version, sb->flags, sb->seq);
327 
328 	submit_bio(bio);
329 }
330 
bch_write_bdev_super_unlock(struct closure * cl)331 static void bch_write_bdev_super_unlock(struct closure *cl)
332 {
333 	struct cached_dev *dc = container_of(cl, struct cached_dev, sb_write);
334 
335 	up(&dc->sb_write_mutex);
336 }
337 
bch_write_bdev_super(struct cached_dev * dc,struct closure * parent)338 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent)
339 {
340 	struct closure *cl = &dc->sb_write;
341 	struct bio *bio = &dc->sb_bio;
342 
343 	down(&dc->sb_write_mutex);
344 	closure_init(cl, parent);
345 
346 	bio_init(bio, dc->sb_bv, 1);
347 	bio_set_dev(bio, dc->bdev);
348 	bio->bi_end_io	= write_bdev_super_endio;
349 	bio->bi_private = dc;
350 
351 	closure_get(cl);
352 	/* I/O request sent to backing device */
353 	__write_super(&dc->sb, dc->sb_disk, bio);
354 
355 	closure_return_with_destructor(cl, bch_write_bdev_super_unlock);
356 }
357 
write_super_endio(struct bio * bio)358 static void write_super_endio(struct bio *bio)
359 {
360 	struct cache *ca = bio->bi_private;
361 
362 	/* is_read = 0 */
363 	bch_count_io_errors(ca, bio->bi_status, 0,
364 			    "writing superblock");
365 	closure_put(&ca->set->sb_write);
366 }
367 
bcache_write_super_unlock(struct closure * cl)368 static void bcache_write_super_unlock(struct closure *cl)
369 {
370 	struct cache_set *c = container_of(cl, struct cache_set, sb_write);
371 
372 	up(&c->sb_write_mutex);
373 }
374 
bcache_write_super(struct cache_set * c)375 void bcache_write_super(struct cache_set *c)
376 {
377 	struct closure *cl = &c->sb_write;
378 	struct cache *ca = c->cache;
379 	struct bio *bio = &ca->sb_bio;
380 	unsigned int version = BCACHE_SB_VERSION_CDEV_WITH_UUID;
381 
382 	down(&c->sb_write_mutex);
383 	closure_init(cl, &c->cl);
384 
385 	ca->sb.seq++;
386 
387 	if (ca->sb.version < version)
388 		ca->sb.version = version;
389 
390 	bio_init(bio, ca->sb_bv, 1);
391 	bio_set_dev(bio, ca->bdev);
392 	bio->bi_end_io	= write_super_endio;
393 	bio->bi_private = ca;
394 
395 	closure_get(cl);
396 	__write_super(&ca->sb, ca->sb_disk, bio);
397 
398 	closure_return_with_destructor(cl, bcache_write_super_unlock);
399 }
400 
401 /* UUID io */
402 
uuid_endio(struct bio * bio)403 static void uuid_endio(struct bio *bio)
404 {
405 	struct closure *cl = bio->bi_private;
406 	struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
407 
408 	cache_set_err_on(bio->bi_status, c, "accessing uuids");
409 	bch_bbio_free(bio, c);
410 	closure_put(cl);
411 }
412 
uuid_io_unlock(struct closure * cl)413 static void uuid_io_unlock(struct closure *cl)
414 {
415 	struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
416 
417 	up(&c->uuid_write_mutex);
418 }
419 
uuid_io(struct cache_set * c,int op,unsigned long op_flags,struct bkey * k,struct closure * parent)420 static void uuid_io(struct cache_set *c, int op, unsigned long op_flags,
421 		    struct bkey *k, struct closure *parent)
422 {
423 	struct closure *cl = &c->uuid_write;
424 	struct uuid_entry *u;
425 	unsigned int i;
426 	char buf[80];
427 
428 	BUG_ON(!parent);
429 	down(&c->uuid_write_mutex);
430 	closure_init(cl, parent);
431 
432 	for (i = 0; i < KEY_PTRS(k); i++) {
433 		struct bio *bio = bch_bbio_alloc(c);
434 
435 		bio->bi_opf = REQ_SYNC | REQ_META | op_flags;
436 		bio->bi_iter.bi_size = KEY_SIZE(k) << 9;
437 
438 		bio->bi_end_io	= uuid_endio;
439 		bio->bi_private = cl;
440 		bio_set_op_attrs(bio, op, REQ_SYNC|REQ_META|op_flags);
441 		bch_bio_map(bio, c->uuids);
442 
443 		bch_submit_bbio(bio, c, k, i);
444 
445 		if (op != REQ_OP_WRITE)
446 			break;
447 	}
448 
449 	bch_extent_to_text(buf, sizeof(buf), k);
450 	pr_debug("%s UUIDs at %s\n", op == REQ_OP_WRITE ? "wrote" : "read", buf);
451 
452 	for (u = c->uuids; u < c->uuids + c->nr_uuids; u++)
453 		if (!bch_is_zero(u->uuid, 16))
454 			pr_debug("Slot %zi: %pU: %s: 1st: %u last: %u inv: %u\n",
455 				 u - c->uuids, u->uuid, u->label,
456 				 u->first_reg, u->last_reg, u->invalidated);
457 
458 	closure_return_with_destructor(cl, uuid_io_unlock);
459 }
460 
uuid_read(struct cache_set * c,struct jset * j,struct closure * cl)461 static char *uuid_read(struct cache_set *c, struct jset *j, struct closure *cl)
462 {
463 	struct bkey *k = &j->uuid_bucket;
464 
465 	if (__bch_btree_ptr_invalid(c, k))
466 		return "bad uuid pointer";
467 
468 	bkey_copy(&c->uuid_bucket, k);
469 	uuid_io(c, REQ_OP_READ, 0, k, cl);
470 
471 	if (j->version < BCACHE_JSET_VERSION_UUIDv1) {
472 		struct uuid_entry_v0	*u0 = (void *) c->uuids;
473 		struct uuid_entry	*u1 = (void *) c->uuids;
474 		int i;
475 
476 		closure_sync(cl);
477 
478 		/*
479 		 * Since the new uuid entry is bigger than the old, we have to
480 		 * convert starting at the highest memory address and work down
481 		 * in order to do it in place
482 		 */
483 
484 		for (i = c->nr_uuids - 1;
485 		     i >= 0;
486 		     --i) {
487 			memcpy(u1[i].uuid,	u0[i].uuid, 16);
488 			memcpy(u1[i].label,	u0[i].label, 32);
489 
490 			u1[i].first_reg		= u0[i].first_reg;
491 			u1[i].last_reg		= u0[i].last_reg;
492 			u1[i].invalidated	= u0[i].invalidated;
493 
494 			u1[i].flags	= 0;
495 			u1[i].sectors	= 0;
496 		}
497 	}
498 
499 	return NULL;
500 }
501 
__uuid_write(struct cache_set * c)502 static int __uuid_write(struct cache_set *c)
503 {
504 	BKEY_PADDED(key) k;
505 	struct closure cl;
506 	struct cache *ca = c->cache;
507 	unsigned int size;
508 
509 	closure_init_stack(&cl);
510 	lockdep_assert_held(&bch_register_lock);
511 
512 	if (bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, true))
513 		return 1;
514 
515 	size =  meta_bucket_pages(&ca->sb) * PAGE_SECTORS;
516 	SET_KEY_SIZE(&k.key, size);
517 	uuid_io(c, REQ_OP_WRITE, 0, &k.key, &cl);
518 	closure_sync(&cl);
519 
520 	/* Only one bucket used for uuid write */
521 	atomic_long_add(ca->sb.bucket_size, &ca->meta_sectors_written);
522 
523 	bkey_copy(&c->uuid_bucket, &k.key);
524 	bkey_put(c, &k.key);
525 	return 0;
526 }
527 
bch_uuid_write(struct cache_set * c)528 int bch_uuid_write(struct cache_set *c)
529 {
530 	int ret = __uuid_write(c);
531 
532 	if (!ret)
533 		bch_journal_meta(c, NULL);
534 
535 	return ret;
536 }
537 
uuid_find(struct cache_set * c,const char * uuid)538 static struct uuid_entry *uuid_find(struct cache_set *c, const char *uuid)
539 {
540 	struct uuid_entry *u;
541 
542 	for (u = c->uuids;
543 	     u < c->uuids + c->nr_uuids; u++)
544 		if (!memcmp(u->uuid, uuid, 16))
545 			return u;
546 
547 	return NULL;
548 }
549 
uuid_find_empty(struct cache_set * c)550 static struct uuid_entry *uuid_find_empty(struct cache_set *c)
551 {
552 	static const char zero_uuid[16] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
553 
554 	return uuid_find(c, zero_uuid);
555 }
556 
557 /*
558  * Bucket priorities/gens:
559  *
560  * For each bucket, we store on disk its
561  *   8 bit gen
562  *  16 bit priority
563  *
564  * See alloc.c for an explanation of the gen. The priority is used to implement
565  * lru (and in the future other) cache replacement policies; for most purposes
566  * it's just an opaque integer.
567  *
568  * The gens and the priorities don't have a whole lot to do with each other, and
569  * it's actually the gens that must be written out at specific times - it's no
570  * big deal if the priorities don't get written, if we lose them we just reuse
571  * buckets in suboptimal order.
572  *
573  * On disk they're stored in a packed array, and in as many buckets are required
574  * to fit them all. The buckets we use to store them form a list; the journal
575  * header points to the first bucket, the first bucket points to the second
576  * bucket, et cetera.
577  *
578  * This code is used by the allocation code; periodically (whenever it runs out
579  * of buckets to allocate from) the allocation code will invalidate some
580  * buckets, but it can't use those buckets until their new gens are safely on
581  * disk.
582  */
583 
prio_endio(struct bio * bio)584 static void prio_endio(struct bio *bio)
585 {
586 	struct cache *ca = bio->bi_private;
587 
588 	cache_set_err_on(bio->bi_status, ca->set, "accessing priorities");
589 	bch_bbio_free(bio, ca->set);
590 	closure_put(&ca->prio);
591 }
592 
prio_io(struct cache * ca,uint64_t bucket,int op,unsigned long op_flags)593 static void prio_io(struct cache *ca, uint64_t bucket, int op,
594 		    unsigned long op_flags)
595 {
596 	struct closure *cl = &ca->prio;
597 	struct bio *bio = bch_bbio_alloc(ca->set);
598 
599 	closure_init_stack(cl);
600 
601 	bio->bi_iter.bi_sector	= bucket * ca->sb.bucket_size;
602 	bio_set_dev(bio, ca->bdev);
603 	bio->bi_iter.bi_size	= meta_bucket_bytes(&ca->sb);
604 
605 	bio->bi_end_io	= prio_endio;
606 	bio->bi_private = ca;
607 	bio_set_op_attrs(bio, op, REQ_SYNC|REQ_META|op_flags);
608 	bch_bio_map(bio, ca->disk_buckets);
609 
610 	closure_bio_submit(ca->set, bio, &ca->prio);
611 	closure_sync(cl);
612 }
613 
bch_prio_write(struct cache * ca,bool wait)614 int bch_prio_write(struct cache *ca, bool wait)
615 {
616 	int i;
617 	struct bucket *b;
618 	struct closure cl;
619 
620 	pr_debug("free_prio=%zu, free_none=%zu, free_inc=%zu\n",
621 		 fifo_used(&ca->free[RESERVE_PRIO]),
622 		 fifo_used(&ca->free[RESERVE_NONE]),
623 		 fifo_used(&ca->free_inc));
624 
625 	/*
626 	 * Pre-check if there are enough free buckets. In the non-blocking
627 	 * scenario it's better to fail early rather than starting to allocate
628 	 * buckets and do a cleanup later in case of failure.
629 	 */
630 	if (!wait) {
631 		size_t avail = fifo_used(&ca->free[RESERVE_PRIO]) +
632 			       fifo_used(&ca->free[RESERVE_NONE]);
633 		if (prio_buckets(ca) > avail)
634 			return -ENOMEM;
635 	}
636 
637 	closure_init_stack(&cl);
638 
639 	lockdep_assert_held(&ca->set->bucket_lock);
640 
641 	ca->disk_buckets->seq++;
642 
643 	atomic_long_add(ca->sb.bucket_size * prio_buckets(ca),
644 			&ca->meta_sectors_written);
645 
646 	for (i = prio_buckets(ca) - 1; i >= 0; --i) {
647 		long bucket;
648 		struct prio_set *p = ca->disk_buckets;
649 		struct bucket_disk *d = p->data;
650 		struct bucket_disk *end = d + prios_per_bucket(ca);
651 
652 		for (b = ca->buckets + i * prios_per_bucket(ca);
653 		     b < ca->buckets + ca->sb.nbuckets && d < end;
654 		     b++, d++) {
655 			d->prio = cpu_to_le16(b->prio);
656 			d->gen = b->gen;
657 		}
658 
659 		p->next_bucket	= ca->prio_buckets[i + 1];
660 		p->magic	= pset_magic(&ca->sb);
661 		p->csum		= bch_crc64(&p->magic, meta_bucket_bytes(&ca->sb) - 8);
662 
663 		bucket = bch_bucket_alloc(ca, RESERVE_PRIO, wait);
664 		BUG_ON(bucket == -1);
665 
666 		mutex_unlock(&ca->set->bucket_lock);
667 		prio_io(ca, bucket, REQ_OP_WRITE, 0);
668 		mutex_lock(&ca->set->bucket_lock);
669 
670 		ca->prio_buckets[i] = bucket;
671 		atomic_dec_bug(&ca->buckets[bucket].pin);
672 	}
673 
674 	mutex_unlock(&ca->set->bucket_lock);
675 
676 	bch_journal_meta(ca->set, &cl);
677 	closure_sync(&cl);
678 
679 	mutex_lock(&ca->set->bucket_lock);
680 
681 	/*
682 	 * Don't want the old priorities to get garbage collected until after we
683 	 * finish writing the new ones, and they're journalled
684 	 */
685 	for (i = 0; i < prio_buckets(ca); i++) {
686 		if (ca->prio_last_buckets[i])
687 			__bch_bucket_free(ca,
688 				&ca->buckets[ca->prio_last_buckets[i]]);
689 
690 		ca->prio_last_buckets[i] = ca->prio_buckets[i];
691 	}
692 	return 0;
693 }
694 
prio_read(struct cache * ca,uint64_t bucket)695 static int prio_read(struct cache *ca, uint64_t bucket)
696 {
697 	struct prio_set *p = ca->disk_buckets;
698 	struct bucket_disk *d = p->data + prios_per_bucket(ca), *end = d;
699 	struct bucket *b;
700 	unsigned int bucket_nr = 0;
701 	int ret = -EIO;
702 
703 	for (b = ca->buckets;
704 	     b < ca->buckets + ca->sb.nbuckets;
705 	     b++, d++) {
706 		if (d == end) {
707 			ca->prio_buckets[bucket_nr] = bucket;
708 			ca->prio_last_buckets[bucket_nr] = bucket;
709 			bucket_nr++;
710 
711 			prio_io(ca, bucket, REQ_OP_READ, 0);
712 
713 			if (p->csum !=
714 			    bch_crc64(&p->magic, meta_bucket_bytes(&ca->sb) - 8)) {
715 				pr_warn("bad csum reading priorities\n");
716 				goto out;
717 			}
718 
719 			if (p->magic != pset_magic(&ca->sb)) {
720 				pr_warn("bad magic reading priorities\n");
721 				goto out;
722 			}
723 
724 			bucket = p->next_bucket;
725 			d = p->data;
726 		}
727 
728 		b->prio = le16_to_cpu(d->prio);
729 		b->gen = b->last_gc = d->gen;
730 	}
731 
732 	ret = 0;
733 out:
734 	return ret;
735 }
736 
737 /* Bcache device */
738 
open_dev(struct block_device * b,fmode_t mode)739 static int open_dev(struct block_device *b, fmode_t mode)
740 {
741 	struct bcache_device *d = b->bd_disk->private_data;
742 
743 	if (test_bit(BCACHE_DEV_CLOSING, &d->flags))
744 		return -ENXIO;
745 
746 	closure_get(&d->cl);
747 	return 0;
748 }
749 
release_dev(struct gendisk * b,fmode_t mode)750 static void release_dev(struct gendisk *b, fmode_t mode)
751 {
752 	struct bcache_device *d = b->private_data;
753 
754 	closure_put(&d->cl);
755 }
756 
ioctl_dev(struct block_device * b,fmode_t mode,unsigned int cmd,unsigned long arg)757 static int ioctl_dev(struct block_device *b, fmode_t mode,
758 		     unsigned int cmd, unsigned long arg)
759 {
760 	struct bcache_device *d = b->bd_disk->private_data;
761 
762 	return d->ioctl(d, mode, cmd, arg);
763 }
764 
765 static const struct block_device_operations bcache_cached_ops = {
766 	.submit_bio	= cached_dev_submit_bio,
767 	.open		= open_dev,
768 	.release	= release_dev,
769 	.ioctl		= ioctl_dev,
770 	.owner		= THIS_MODULE,
771 };
772 
773 static const struct block_device_operations bcache_flash_ops = {
774 	.submit_bio	= flash_dev_submit_bio,
775 	.open		= open_dev,
776 	.release	= release_dev,
777 	.ioctl		= ioctl_dev,
778 	.owner		= THIS_MODULE,
779 };
780 
bcache_device_stop(struct bcache_device * d)781 void bcache_device_stop(struct bcache_device *d)
782 {
783 	if (!test_and_set_bit(BCACHE_DEV_CLOSING, &d->flags))
784 		/*
785 		 * closure_fn set to
786 		 * - cached device: cached_dev_flush()
787 		 * - flash dev: flash_dev_flush()
788 		 */
789 		closure_queue(&d->cl);
790 }
791 
bcache_device_unlink(struct bcache_device * d)792 static void bcache_device_unlink(struct bcache_device *d)
793 {
794 	lockdep_assert_held(&bch_register_lock);
795 
796 	if (d->c && !test_and_set_bit(BCACHE_DEV_UNLINK_DONE, &d->flags)) {
797 		struct cache *ca = d->c->cache;
798 
799 		sysfs_remove_link(&d->c->kobj, d->name);
800 		sysfs_remove_link(&d->kobj, "cache");
801 
802 		bd_unlink_disk_holder(ca->bdev, d->disk);
803 	}
804 }
805 
bcache_device_link(struct bcache_device * d,struct cache_set * c,const char * name)806 static void bcache_device_link(struct bcache_device *d, struct cache_set *c,
807 			       const char *name)
808 {
809 	struct cache *ca = c->cache;
810 	int ret;
811 
812 	bd_link_disk_holder(ca->bdev, d->disk);
813 
814 	snprintf(d->name, BCACHEDEVNAME_SIZE,
815 		 "%s%u", name, d->id);
816 
817 	ret = sysfs_create_link(&d->kobj, &c->kobj, "cache");
818 	if (ret < 0)
819 		pr_err("Couldn't create device -> cache set symlink\n");
820 
821 	ret = sysfs_create_link(&c->kobj, &d->kobj, d->name);
822 	if (ret < 0)
823 		pr_err("Couldn't create cache set -> device symlink\n");
824 
825 	clear_bit(BCACHE_DEV_UNLINK_DONE, &d->flags);
826 }
827 
bcache_device_detach(struct bcache_device * d)828 static void bcache_device_detach(struct bcache_device *d)
829 {
830 	lockdep_assert_held(&bch_register_lock);
831 
832 	atomic_dec(&d->c->attached_dev_nr);
833 
834 	if (test_bit(BCACHE_DEV_DETACHING, &d->flags)) {
835 		struct uuid_entry *u = d->c->uuids + d->id;
836 
837 		SET_UUID_FLASH_ONLY(u, 0);
838 		memcpy(u->uuid, invalid_uuid, 16);
839 		u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds());
840 		bch_uuid_write(d->c);
841 	}
842 
843 	bcache_device_unlink(d);
844 
845 	d->c->devices[d->id] = NULL;
846 	closure_put(&d->c->caching);
847 	d->c = NULL;
848 }
849 
bcache_device_attach(struct bcache_device * d,struct cache_set * c,unsigned int id)850 static void bcache_device_attach(struct bcache_device *d, struct cache_set *c,
851 				 unsigned int id)
852 {
853 	d->id = id;
854 	d->c = c;
855 	c->devices[id] = d;
856 
857 	if (id >= c->devices_max_used)
858 		c->devices_max_used = id + 1;
859 
860 	closure_get(&c->caching);
861 }
862 
first_minor_to_idx(int first_minor)863 static inline int first_minor_to_idx(int first_minor)
864 {
865 	return (first_minor/BCACHE_MINORS);
866 }
867 
idx_to_first_minor(int idx)868 static inline int idx_to_first_minor(int idx)
869 {
870 	return (idx * BCACHE_MINORS);
871 }
872 
bcache_device_free(struct bcache_device * d)873 static void bcache_device_free(struct bcache_device *d)
874 {
875 	struct gendisk *disk = d->disk;
876 
877 	lockdep_assert_held(&bch_register_lock);
878 
879 	if (disk)
880 		pr_info("%s stopped\n", disk->disk_name);
881 	else
882 		pr_err("bcache device (NULL gendisk) stopped\n");
883 
884 	if (d->c)
885 		bcache_device_detach(d);
886 
887 	if (disk) {
888 		ida_simple_remove(&bcache_device_idx,
889 				  first_minor_to_idx(disk->first_minor));
890 		blk_cleanup_disk(disk);
891 	}
892 
893 	bioset_exit(&d->bio_split);
894 	kvfree(d->full_dirty_stripes);
895 	kvfree(d->stripe_sectors_dirty);
896 
897 	closure_debug_destroy(&d->cl);
898 }
899 
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)900 static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
901 		sector_t sectors, struct block_device *cached_bdev,
902 		const struct block_device_operations *ops)
903 {
904 	struct request_queue *q;
905 	const size_t max_stripes = min_t(size_t, INT_MAX,
906 					 SIZE_MAX / sizeof(atomic_t));
907 	uint64_t n;
908 	int idx;
909 
910 	if (!d->stripe_size)
911 		d->stripe_size = 1 << 31;
912 	else if (d->stripe_size < BCH_MIN_STRIPE_SZ)
913 		d->stripe_size = roundup(BCH_MIN_STRIPE_SZ, d->stripe_size);
914 
915 	n = DIV_ROUND_UP_ULL(sectors, d->stripe_size);
916 	if (!n || n > max_stripes) {
917 		pr_err("nr_stripes too large or invalid: %llu (start sector beyond end of disk?)\n",
918 			n);
919 		return -ENOMEM;
920 	}
921 	d->nr_stripes = n;
922 
923 	n = d->nr_stripes * sizeof(atomic_t);
924 	d->stripe_sectors_dirty = kvzalloc(n, GFP_KERNEL);
925 	if (!d->stripe_sectors_dirty)
926 		return -ENOMEM;
927 
928 	n = BITS_TO_LONGS(d->nr_stripes) * sizeof(unsigned long);
929 	d->full_dirty_stripes = kvzalloc(n, GFP_KERNEL);
930 	if (!d->full_dirty_stripes)
931 		goto out_free_stripe_sectors_dirty;
932 
933 	idx = ida_simple_get(&bcache_device_idx, 0,
934 				BCACHE_DEVICE_IDX_MAX, GFP_KERNEL);
935 	if (idx < 0)
936 		goto out_free_full_dirty_stripes;
937 
938 	if (bioset_init(&d->bio_split, 4, offsetof(struct bbio, bio),
939 			BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER))
940 		goto out_ida_remove;
941 
942 	d->disk = blk_alloc_disk(NUMA_NO_NODE);
943 	if (!d->disk)
944 		goto out_bioset_exit;
945 
946 	set_capacity(d->disk, sectors);
947 	snprintf(d->disk->disk_name, DISK_NAME_LEN, "bcache%i", idx);
948 
949 	d->disk->major		= bcache_major;
950 	d->disk->first_minor	= idx_to_first_minor(idx);
951 	d->disk->minors		= BCACHE_MINORS;
952 	d->disk->fops		= ops;
953 	d->disk->private_data	= d;
954 
955 	q = d->disk->queue;
956 	q->limits.max_hw_sectors	= UINT_MAX;
957 	q->limits.max_sectors		= UINT_MAX;
958 	q->limits.max_segment_size	= UINT_MAX;
959 	q->limits.max_segments		= BIO_MAX_VECS;
960 	blk_queue_max_discard_sectors(q, UINT_MAX);
961 	q->limits.discard_granularity	= 512;
962 	q->limits.io_min		= block_size;
963 	q->limits.logical_block_size	= block_size;
964 	q->limits.physical_block_size	= block_size;
965 
966 	if (q->limits.logical_block_size > PAGE_SIZE && cached_bdev) {
967 		/*
968 		 * This should only happen with BCACHE_SB_VERSION_BDEV.
969 		 * Block/page size is checked for BCACHE_SB_VERSION_CDEV.
970 		 */
971 		pr_info("%s: sb/logical block size (%u) greater than page size (%lu) falling back to device logical block size (%u)\n",
972 			d->disk->disk_name, q->limits.logical_block_size,
973 			PAGE_SIZE, bdev_logical_block_size(cached_bdev));
974 
975 		/* This also adjusts physical block size/min io size if needed */
976 		blk_queue_logical_block_size(q, bdev_logical_block_size(cached_bdev));
977 	}
978 
979 	blk_queue_flag_set(QUEUE_FLAG_NONROT, d->disk->queue);
980 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, d->disk->queue);
981 	blk_queue_flag_set(QUEUE_FLAG_DISCARD, d->disk->queue);
982 
983 	blk_queue_write_cache(q, true, true);
984 
985 	return 0;
986 
987 out_bioset_exit:
988 	bioset_exit(&d->bio_split);
989 out_ida_remove:
990 	ida_simple_remove(&bcache_device_idx, idx);
991 out_free_full_dirty_stripes:
992 	kvfree(d->full_dirty_stripes);
993 out_free_stripe_sectors_dirty:
994 	kvfree(d->stripe_sectors_dirty);
995 	return -ENOMEM;
996 
997 }
998 
999 /* Cached device */
1000 
calc_cached_dev_sectors(struct cache_set * c)1001 static void calc_cached_dev_sectors(struct cache_set *c)
1002 {
1003 	uint64_t sectors = 0;
1004 	struct cached_dev *dc;
1005 
1006 	list_for_each_entry(dc, &c->cached_devs, list)
1007 		sectors += bdev_sectors(dc->bdev);
1008 
1009 	c->cached_dev_sectors = sectors;
1010 }
1011 
1012 #define BACKING_DEV_OFFLINE_TIMEOUT 5
cached_dev_status_update(void * arg)1013 static int cached_dev_status_update(void *arg)
1014 {
1015 	struct cached_dev *dc = arg;
1016 	struct request_queue *q;
1017 
1018 	/*
1019 	 * If this delayed worker is stopping outside, directly quit here.
1020 	 * dc->io_disable might be set via sysfs interface, so check it
1021 	 * here too.
1022 	 */
1023 	while (!kthread_should_stop() && !dc->io_disable) {
1024 		q = bdev_get_queue(dc->bdev);
1025 		if (blk_queue_dying(q))
1026 			dc->offline_seconds++;
1027 		else
1028 			dc->offline_seconds = 0;
1029 
1030 		if (dc->offline_seconds >= BACKING_DEV_OFFLINE_TIMEOUT) {
1031 			pr_err("%s: device offline for %d seconds\n",
1032 			       dc->backing_dev_name,
1033 			       BACKING_DEV_OFFLINE_TIMEOUT);
1034 			pr_err("%s: disable I/O request due to backing device offline\n",
1035 			       dc->disk.name);
1036 			dc->io_disable = true;
1037 			/* let others know earlier that io_disable is true */
1038 			smp_mb();
1039 			bcache_device_stop(&dc->disk);
1040 			break;
1041 		}
1042 		schedule_timeout_interruptible(HZ);
1043 	}
1044 
1045 	wait_for_kthread_stop();
1046 	return 0;
1047 }
1048 
1049 
bch_cached_dev_run(struct cached_dev * dc)1050 int bch_cached_dev_run(struct cached_dev *dc)
1051 {
1052 	int ret = 0;
1053 	struct bcache_device *d = &dc->disk;
1054 	char *buf = kmemdup_nul(dc->sb.label, SB_LABEL_SIZE, GFP_KERNEL);
1055 	char *env[] = {
1056 		"DRIVER=bcache",
1057 		kasprintf(GFP_KERNEL, "CACHED_UUID=%pU", dc->sb.uuid),
1058 		kasprintf(GFP_KERNEL, "CACHED_LABEL=%s", buf ? : ""),
1059 		NULL,
1060 	};
1061 
1062 	if (dc->io_disable) {
1063 		pr_err("I/O disabled on cached dev %s\n",
1064 		       dc->backing_dev_name);
1065 		ret = -EIO;
1066 		goto out;
1067 	}
1068 
1069 	if (atomic_xchg(&dc->running, 1)) {
1070 		pr_info("cached dev %s is running already\n",
1071 		       dc->backing_dev_name);
1072 		ret = -EBUSY;
1073 		goto out;
1074 	}
1075 
1076 	if (!d->c &&
1077 	    BDEV_STATE(&dc->sb) != BDEV_STATE_NONE) {
1078 		struct closure cl;
1079 
1080 		closure_init_stack(&cl);
1081 
1082 		SET_BDEV_STATE(&dc->sb, BDEV_STATE_STALE);
1083 		bch_write_bdev_super(dc, &cl);
1084 		closure_sync(&cl);
1085 	}
1086 
1087 	add_disk(d->disk);
1088 	bd_link_disk_holder(dc->bdev, dc->disk.disk);
1089 	/*
1090 	 * won't show up in the uevent file, use udevadm monitor -e instead
1091 	 * only class / kset properties are persistent
1092 	 */
1093 	kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env);
1094 
1095 	if (sysfs_create_link(&d->kobj, &disk_to_dev(d->disk)->kobj, "dev") ||
1096 	    sysfs_create_link(&disk_to_dev(d->disk)->kobj,
1097 			      &d->kobj, "bcache")) {
1098 		pr_err("Couldn't create bcache dev <-> disk sysfs symlinks\n");
1099 		ret = -ENOMEM;
1100 		goto out;
1101 	}
1102 
1103 	dc->status_update_thread = kthread_run(cached_dev_status_update,
1104 					       dc, "bcache_status_update");
1105 	if (IS_ERR(dc->status_update_thread)) {
1106 		pr_warn("failed to create bcache_status_update kthread, continue to run without monitoring backing device status\n");
1107 	}
1108 
1109 out:
1110 	kfree(env[1]);
1111 	kfree(env[2]);
1112 	kfree(buf);
1113 	return ret;
1114 }
1115 
1116 /*
1117  * If BCACHE_DEV_RATE_DW_RUNNING is set, it means routine of the delayed
1118  * work dc->writeback_rate_update is running. Wait until the routine
1119  * quits (BCACHE_DEV_RATE_DW_RUNNING is clear), then continue to
1120  * cancel it. If BCACHE_DEV_RATE_DW_RUNNING is not clear after time_out
1121  * seconds, give up waiting here and continue to cancel it too.
1122  */
cancel_writeback_rate_update_dwork(struct cached_dev * dc)1123 static void cancel_writeback_rate_update_dwork(struct cached_dev *dc)
1124 {
1125 	int time_out = WRITEBACK_RATE_UPDATE_SECS_MAX * HZ;
1126 
1127 	do {
1128 		if (!test_bit(BCACHE_DEV_RATE_DW_RUNNING,
1129 			      &dc->disk.flags))
1130 			break;
1131 		time_out--;
1132 		schedule_timeout_interruptible(1);
1133 	} while (time_out > 0);
1134 
1135 	if (time_out == 0)
1136 		pr_warn("give up waiting for dc->writeback_write_update to quit\n");
1137 
1138 	cancel_delayed_work_sync(&dc->writeback_rate_update);
1139 }
1140 
cached_dev_detach_finish(struct work_struct * w)1141 static void cached_dev_detach_finish(struct work_struct *w)
1142 {
1143 	struct cached_dev *dc = container_of(w, struct cached_dev, detach);
1144 
1145 	BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags));
1146 	BUG_ON(refcount_read(&dc->count));
1147 
1148 
1149 	if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
1150 		cancel_writeback_rate_update_dwork(dc);
1151 
1152 	if (!IS_ERR_OR_NULL(dc->writeback_thread)) {
1153 		kthread_stop(dc->writeback_thread);
1154 		dc->writeback_thread = NULL;
1155 	}
1156 
1157 	mutex_lock(&bch_register_lock);
1158 
1159 	calc_cached_dev_sectors(dc->disk.c);
1160 	bcache_device_detach(&dc->disk);
1161 	list_move(&dc->list, &uncached_devices);
1162 
1163 	clear_bit(BCACHE_DEV_DETACHING, &dc->disk.flags);
1164 	clear_bit(BCACHE_DEV_UNLINK_DONE, &dc->disk.flags);
1165 
1166 	mutex_unlock(&bch_register_lock);
1167 
1168 	pr_info("Caching disabled for %s\n", dc->backing_dev_name);
1169 
1170 	/* Drop ref we took in cached_dev_detach() */
1171 	closure_put(&dc->disk.cl);
1172 }
1173 
bch_cached_dev_detach(struct cached_dev * dc)1174 void bch_cached_dev_detach(struct cached_dev *dc)
1175 {
1176 	lockdep_assert_held(&bch_register_lock);
1177 
1178 	if (test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
1179 		return;
1180 
1181 	if (test_and_set_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
1182 		return;
1183 
1184 	/*
1185 	 * Block the device from being closed and freed until we're finished
1186 	 * detaching
1187 	 */
1188 	closure_get(&dc->disk.cl);
1189 
1190 	bch_writeback_queue(dc);
1191 
1192 	cached_dev_put(dc);
1193 }
1194 
bch_cached_dev_attach(struct cached_dev * dc,struct cache_set * c,uint8_t * set_uuid)1195 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
1196 			  uint8_t *set_uuid)
1197 {
1198 	uint32_t rtime = cpu_to_le32((u32)ktime_get_real_seconds());
1199 	struct uuid_entry *u;
1200 	struct cached_dev *exist_dc, *t;
1201 	int ret = 0;
1202 
1203 	if ((set_uuid && memcmp(set_uuid, c->set_uuid, 16)) ||
1204 	    (!set_uuid && memcmp(dc->sb.set_uuid, c->set_uuid, 16)))
1205 		return -ENOENT;
1206 
1207 	if (dc->disk.c) {
1208 		pr_err("Can't attach %s: already attached\n",
1209 		       dc->backing_dev_name);
1210 		return -EINVAL;
1211 	}
1212 
1213 	if (test_bit(CACHE_SET_STOPPING, &c->flags)) {
1214 		pr_err("Can't attach %s: shutting down\n",
1215 		       dc->backing_dev_name);
1216 		return -EINVAL;
1217 	}
1218 
1219 	if (dc->sb.block_size < c->cache->sb.block_size) {
1220 		/* Will die */
1221 		pr_err("Couldn't attach %s: block size less than set's block size\n",
1222 		       dc->backing_dev_name);
1223 		return -EINVAL;
1224 	}
1225 
1226 	/* Check whether already attached */
1227 	list_for_each_entry_safe(exist_dc, t, &c->cached_devs, list) {
1228 		if (!memcmp(dc->sb.uuid, exist_dc->sb.uuid, 16)) {
1229 			pr_err("Tried to attach %s but duplicate UUID already attached\n",
1230 				dc->backing_dev_name);
1231 
1232 			return -EINVAL;
1233 		}
1234 	}
1235 
1236 	u = uuid_find(c, dc->sb.uuid);
1237 
1238 	if (u &&
1239 	    (BDEV_STATE(&dc->sb) == BDEV_STATE_STALE ||
1240 	     BDEV_STATE(&dc->sb) == BDEV_STATE_NONE)) {
1241 		memcpy(u->uuid, invalid_uuid, 16);
1242 		u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds());
1243 		u = NULL;
1244 	}
1245 
1246 	if (!u) {
1247 		if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
1248 			pr_err("Couldn't find uuid for %s in set\n",
1249 			       dc->backing_dev_name);
1250 			return -ENOENT;
1251 		}
1252 
1253 		u = uuid_find_empty(c);
1254 		if (!u) {
1255 			pr_err("Not caching %s, no room for UUID\n",
1256 			       dc->backing_dev_name);
1257 			return -EINVAL;
1258 		}
1259 	}
1260 
1261 	/*
1262 	 * Deadlocks since we're called via sysfs...
1263 	 * sysfs_remove_file(&dc->kobj, &sysfs_attach);
1264 	 */
1265 
1266 	if (bch_is_zero(u->uuid, 16)) {
1267 		struct closure cl;
1268 
1269 		closure_init_stack(&cl);
1270 
1271 		memcpy(u->uuid, dc->sb.uuid, 16);
1272 		memcpy(u->label, dc->sb.label, SB_LABEL_SIZE);
1273 		u->first_reg = u->last_reg = rtime;
1274 		bch_uuid_write(c);
1275 
1276 		memcpy(dc->sb.set_uuid, c->set_uuid, 16);
1277 		SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
1278 
1279 		bch_write_bdev_super(dc, &cl);
1280 		closure_sync(&cl);
1281 	} else {
1282 		u->last_reg = rtime;
1283 		bch_uuid_write(c);
1284 	}
1285 
1286 	bcache_device_attach(&dc->disk, c, u - c->uuids);
1287 	list_move(&dc->list, &c->cached_devs);
1288 	calc_cached_dev_sectors(c);
1289 
1290 	/*
1291 	 * dc->c must be set before dc->count != 0 - paired with the mb in
1292 	 * cached_dev_get()
1293 	 */
1294 	smp_wmb();
1295 	refcount_set(&dc->count, 1);
1296 
1297 	/* Block writeback thread, but spawn it */
1298 	down_write(&dc->writeback_lock);
1299 	if (bch_cached_dev_writeback_start(dc)) {
1300 		up_write(&dc->writeback_lock);
1301 		pr_err("Couldn't start writeback facilities for %s\n",
1302 		       dc->disk.disk->disk_name);
1303 		return -ENOMEM;
1304 	}
1305 
1306 	if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
1307 		atomic_set(&dc->has_dirty, 1);
1308 		bch_writeback_queue(dc);
1309 	}
1310 
1311 	bch_sectors_dirty_init(&dc->disk);
1312 
1313 	ret = bch_cached_dev_run(dc);
1314 	if (ret && (ret != -EBUSY)) {
1315 		up_write(&dc->writeback_lock);
1316 		/*
1317 		 * bch_register_lock is held, bcache_device_stop() is not
1318 		 * able to be directly called. The kthread and kworker
1319 		 * created previously in bch_cached_dev_writeback_start()
1320 		 * have to be stopped manually here.
1321 		 */
1322 		kthread_stop(dc->writeback_thread);
1323 		cancel_writeback_rate_update_dwork(dc);
1324 		pr_err("Couldn't run cached device %s\n",
1325 		       dc->backing_dev_name);
1326 		return ret;
1327 	}
1328 
1329 	bcache_device_link(&dc->disk, c, "bdev");
1330 	atomic_inc(&c->attached_dev_nr);
1331 
1332 	if (bch_has_feature_obso_large_bucket(&(c->cache->sb))) {
1333 		pr_err("The obsoleted large bucket layout is unsupported, set the bcache device into read-only\n");
1334 		pr_err("Please update to the latest bcache-tools to create the cache device\n");
1335 		set_disk_ro(dc->disk.disk, 1);
1336 	}
1337 
1338 	/* Allow the writeback thread to proceed */
1339 	up_write(&dc->writeback_lock);
1340 
1341 	pr_info("Caching %s as %s on set %pU\n",
1342 		dc->backing_dev_name,
1343 		dc->disk.disk->disk_name,
1344 		dc->disk.c->set_uuid);
1345 	return 0;
1346 }
1347 
1348 /* when dc->disk.kobj released */
bch_cached_dev_release(struct kobject * kobj)1349 void bch_cached_dev_release(struct kobject *kobj)
1350 {
1351 	struct cached_dev *dc = container_of(kobj, struct cached_dev,
1352 					     disk.kobj);
1353 	kfree(dc);
1354 	module_put(THIS_MODULE);
1355 }
1356 
cached_dev_free(struct closure * cl)1357 static void cached_dev_free(struct closure *cl)
1358 {
1359 	struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
1360 
1361 	if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
1362 		cancel_writeback_rate_update_dwork(dc);
1363 
1364 	if (!IS_ERR_OR_NULL(dc->writeback_thread))
1365 		kthread_stop(dc->writeback_thread);
1366 	if (!IS_ERR_OR_NULL(dc->status_update_thread))
1367 		kthread_stop(dc->status_update_thread);
1368 
1369 	mutex_lock(&bch_register_lock);
1370 
1371 	if (atomic_read(&dc->running)) {
1372 		bd_unlink_disk_holder(dc->bdev, dc->disk.disk);
1373 		del_gendisk(dc->disk.disk);
1374 	}
1375 	bcache_device_free(&dc->disk);
1376 	list_del(&dc->list);
1377 
1378 	mutex_unlock(&bch_register_lock);
1379 
1380 	if (dc->sb_disk)
1381 		put_page(virt_to_page(dc->sb_disk));
1382 
1383 	if (!IS_ERR_OR_NULL(dc->bdev))
1384 		blkdev_put(dc->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
1385 
1386 	wake_up(&unregister_wait);
1387 
1388 	kobject_put(&dc->disk.kobj);
1389 }
1390 
cached_dev_flush(struct closure * cl)1391 static void cached_dev_flush(struct closure *cl)
1392 {
1393 	struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
1394 	struct bcache_device *d = &dc->disk;
1395 
1396 	mutex_lock(&bch_register_lock);
1397 	bcache_device_unlink(d);
1398 	mutex_unlock(&bch_register_lock);
1399 
1400 	bch_cache_accounting_destroy(&dc->accounting);
1401 	kobject_del(&d->kobj);
1402 
1403 	continue_at(cl, cached_dev_free, system_wq);
1404 }
1405 
cached_dev_init(struct cached_dev * dc,unsigned int block_size)1406 static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
1407 {
1408 	int ret;
1409 	struct io *io;
1410 	struct request_queue *q = bdev_get_queue(dc->bdev);
1411 
1412 	__module_get(THIS_MODULE);
1413 	INIT_LIST_HEAD(&dc->list);
1414 	closure_init(&dc->disk.cl, NULL);
1415 	set_closure_fn(&dc->disk.cl, cached_dev_flush, system_wq);
1416 	kobject_init(&dc->disk.kobj, &bch_cached_dev_ktype);
1417 	INIT_WORK(&dc->detach, cached_dev_detach_finish);
1418 	sema_init(&dc->sb_write_mutex, 1);
1419 	INIT_LIST_HEAD(&dc->io_lru);
1420 	spin_lock_init(&dc->io_lock);
1421 	bch_cache_accounting_init(&dc->accounting, &dc->disk.cl);
1422 
1423 	dc->sequential_cutoff		= 4 << 20;
1424 
1425 	for (io = dc->io; io < dc->io + RECENT_IO; io++) {
1426 		list_add(&io->lru, &dc->io_lru);
1427 		hlist_add_head(&io->hash, dc->io_hash + RECENT_IO);
1428 	}
1429 
1430 	dc->disk.stripe_size = q->limits.io_opt >> 9;
1431 
1432 	if (dc->disk.stripe_size)
1433 		dc->partial_stripes_expensive =
1434 			q->limits.raid_partial_stripes_expensive;
1435 
1436 	ret = bcache_device_init(&dc->disk, block_size,
1437 			 bdev_nr_sectors(dc->bdev) - dc->sb.data_offset,
1438 			 dc->bdev, &bcache_cached_ops);
1439 	if (ret)
1440 		return ret;
1441 
1442 	blk_queue_io_opt(dc->disk.disk->queue,
1443 		max(queue_io_opt(dc->disk.disk->queue), queue_io_opt(q)));
1444 
1445 	atomic_set(&dc->io_errors, 0);
1446 	dc->io_disable = false;
1447 	dc->error_limit = DEFAULT_CACHED_DEV_ERROR_LIMIT;
1448 	/* default to auto */
1449 	dc->stop_when_cache_set_failed = BCH_CACHED_DEV_STOP_AUTO;
1450 
1451 	bch_cached_dev_request_init(dc);
1452 	bch_cached_dev_writeback_init(dc);
1453 	return 0;
1454 }
1455 
1456 /* Cached device - bcache superblock */
1457 
register_bdev(struct cache_sb * sb,struct cache_sb_disk * sb_disk,struct block_device * bdev,struct cached_dev * dc)1458 static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
1459 				 struct block_device *bdev,
1460 				 struct cached_dev *dc)
1461 {
1462 	const char *err = "cannot allocate memory";
1463 	struct cache_set *c;
1464 	int ret = -ENOMEM;
1465 
1466 	bdevname(bdev, dc->backing_dev_name);
1467 	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
1468 	dc->bdev = bdev;
1469 	dc->bdev->bd_holder = dc;
1470 	dc->sb_disk = sb_disk;
1471 
1472 	if (cached_dev_init(dc, sb->block_size << 9))
1473 		goto err;
1474 
1475 	err = "error creating kobject";
1476 	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
1477 		goto err;
1478 	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
1479 		goto err;
1480 
1481 	pr_info("registered backing device %s\n", dc->backing_dev_name);
1482 
1483 	list_add(&dc->list, &uncached_devices);
1484 	/* attach to a matched cache set if it exists */
1485 	list_for_each_entry(c, &bch_cache_sets, list)
1486 		bch_cached_dev_attach(dc, c, NULL);
1487 
1488 	if (BDEV_STATE(&dc->sb) == BDEV_STATE_NONE ||
1489 	    BDEV_STATE(&dc->sb) == BDEV_STATE_STALE) {
1490 		err = "failed to run cached device";
1491 		ret = bch_cached_dev_run(dc);
1492 		if (ret)
1493 			goto err;
1494 	}
1495 
1496 	return 0;
1497 err:
1498 	pr_notice("error %s: %s\n", dc->backing_dev_name, err);
1499 	bcache_device_stop(&dc->disk);
1500 	return ret;
1501 }
1502 
1503 /* Flash only volumes */
1504 
1505 /* When d->kobj released */
bch_flash_dev_release(struct kobject * kobj)1506 void bch_flash_dev_release(struct kobject *kobj)
1507 {
1508 	struct bcache_device *d = container_of(kobj, struct bcache_device,
1509 					       kobj);
1510 	kfree(d);
1511 }
1512 
flash_dev_free(struct closure * cl)1513 static void flash_dev_free(struct closure *cl)
1514 {
1515 	struct bcache_device *d = container_of(cl, struct bcache_device, cl);
1516 
1517 	mutex_lock(&bch_register_lock);
1518 	atomic_long_sub(bcache_dev_sectors_dirty(d),
1519 			&d->c->flash_dev_dirty_sectors);
1520 	del_gendisk(d->disk);
1521 	bcache_device_free(d);
1522 	mutex_unlock(&bch_register_lock);
1523 	kobject_put(&d->kobj);
1524 }
1525 
flash_dev_flush(struct closure * cl)1526 static void flash_dev_flush(struct closure *cl)
1527 {
1528 	struct bcache_device *d = container_of(cl, struct bcache_device, cl);
1529 
1530 	mutex_lock(&bch_register_lock);
1531 	bcache_device_unlink(d);
1532 	mutex_unlock(&bch_register_lock);
1533 	kobject_del(&d->kobj);
1534 	continue_at(cl, flash_dev_free, system_wq);
1535 }
1536 
flash_dev_run(struct cache_set * c,struct uuid_entry * u)1537 static int flash_dev_run(struct cache_set *c, struct uuid_entry *u)
1538 {
1539 	struct bcache_device *d = kzalloc(sizeof(struct bcache_device),
1540 					  GFP_KERNEL);
1541 	if (!d)
1542 		return -ENOMEM;
1543 
1544 	closure_init(&d->cl, NULL);
1545 	set_closure_fn(&d->cl, flash_dev_flush, system_wq);
1546 
1547 	kobject_init(&d->kobj, &bch_flash_dev_ktype);
1548 
1549 	if (bcache_device_init(d, block_bytes(c->cache), u->sectors,
1550 			NULL, &bcache_flash_ops))
1551 		goto err;
1552 
1553 	bcache_device_attach(d, c, u - c->uuids);
1554 	bch_sectors_dirty_init(d);
1555 	bch_flash_dev_request_init(d);
1556 	add_disk(d->disk);
1557 
1558 	if (kobject_add(&d->kobj, &disk_to_dev(d->disk)->kobj, "bcache"))
1559 		goto err;
1560 
1561 	bcache_device_link(d, c, "volume");
1562 
1563 	if (bch_has_feature_obso_large_bucket(&c->cache->sb)) {
1564 		pr_err("The obsoleted large bucket layout is unsupported, set the bcache device into read-only\n");
1565 		pr_err("Please update to the latest bcache-tools to create the cache device\n");
1566 		set_disk_ro(d->disk, 1);
1567 	}
1568 
1569 	return 0;
1570 err:
1571 	kobject_put(&d->kobj);
1572 	return -ENOMEM;
1573 }
1574 
flash_devs_run(struct cache_set * c)1575 static int flash_devs_run(struct cache_set *c)
1576 {
1577 	int ret = 0;
1578 	struct uuid_entry *u;
1579 
1580 	for (u = c->uuids;
1581 	     u < c->uuids + c->nr_uuids && !ret;
1582 	     u++)
1583 		if (UUID_FLASH_ONLY(u))
1584 			ret = flash_dev_run(c, u);
1585 
1586 	return ret;
1587 }
1588 
bch_flash_dev_create(struct cache_set * c,uint64_t size)1589 int bch_flash_dev_create(struct cache_set *c, uint64_t size)
1590 {
1591 	struct uuid_entry *u;
1592 
1593 	if (test_bit(CACHE_SET_STOPPING, &c->flags))
1594 		return -EINTR;
1595 
1596 	if (!test_bit(CACHE_SET_RUNNING, &c->flags))
1597 		return -EPERM;
1598 
1599 	u = uuid_find_empty(c);
1600 	if (!u) {
1601 		pr_err("Can't create volume, no room for UUID\n");
1602 		return -EINVAL;
1603 	}
1604 
1605 	get_random_bytes(u->uuid, 16);
1606 	memset(u->label, 0, 32);
1607 	u->first_reg = u->last_reg = cpu_to_le32((u32)ktime_get_real_seconds());
1608 
1609 	SET_UUID_FLASH_ONLY(u, 1);
1610 	u->sectors = size >> 9;
1611 
1612 	bch_uuid_write(c);
1613 
1614 	return flash_dev_run(c, u);
1615 }
1616 
bch_cached_dev_error(struct cached_dev * dc)1617 bool bch_cached_dev_error(struct cached_dev *dc)
1618 {
1619 	if (!dc || test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
1620 		return false;
1621 
1622 	dc->io_disable = true;
1623 	/* make others know io_disable is true earlier */
1624 	smp_mb();
1625 
1626 	pr_err("stop %s: too many IO errors on backing device %s\n",
1627 	       dc->disk.disk->disk_name, dc->backing_dev_name);
1628 
1629 	bcache_device_stop(&dc->disk);
1630 	return true;
1631 }
1632 
1633 /* Cache set */
1634 
1635 __printf(2, 3)
bch_cache_set_error(struct cache_set * c,const char * fmt,...)1636 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...)
1637 {
1638 	struct va_format vaf;
1639 	va_list args;
1640 
1641 	if (c->on_error != ON_ERROR_PANIC &&
1642 	    test_bit(CACHE_SET_STOPPING, &c->flags))
1643 		return false;
1644 
1645 	if (test_and_set_bit(CACHE_SET_IO_DISABLE, &c->flags))
1646 		pr_info("CACHE_SET_IO_DISABLE already set\n");
1647 
1648 	/*
1649 	 * XXX: we can be called from atomic context
1650 	 * acquire_console_sem();
1651 	 */
1652 
1653 	va_start(args, fmt);
1654 
1655 	vaf.fmt = fmt;
1656 	vaf.va = &args;
1657 
1658 	pr_err("error on %pU: %pV, disabling caching\n",
1659 	       c->set_uuid, &vaf);
1660 
1661 	va_end(args);
1662 
1663 	if (c->on_error == ON_ERROR_PANIC)
1664 		panic("panic forced after error\n");
1665 
1666 	bch_cache_set_unregister(c);
1667 	return true;
1668 }
1669 
1670 /* When c->kobj released */
bch_cache_set_release(struct kobject * kobj)1671 void bch_cache_set_release(struct kobject *kobj)
1672 {
1673 	struct cache_set *c = container_of(kobj, struct cache_set, kobj);
1674 
1675 	kfree(c);
1676 	module_put(THIS_MODULE);
1677 }
1678 
cache_set_free(struct closure * cl)1679 static void cache_set_free(struct closure *cl)
1680 {
1681 	struct cache_set *c = container_of(cl, struct cache_set, cl);
1682 	struct cache *ca;
1683 
1684 	debugfs_remove(c->debug);
1685 
1686 	bch_open_buckets_free(c);
1687 	bch_btree_cache_free(c);
1688 	bch_journal_free(c);
1689 
1690 	mutex_lock(&bch_register_lock);
1691 	bch_bset_sort_state_free(&c->sort);
1692 	free_pages((unsigned long) c->uuids, ilog2(meta_bucket_pages(&c->cache->sb)));
1693 
1694 	ca = c->cache;
1695 	if (ca) {
1696 		ca->set = NULL;
1697 		c->cache = NULL;
1698 		kobject_put(&ca->kobj);
1699 	}
1700 
1701 
1702 	if (c->moving_gc_wq)
1703 		destroy_workqueue(c->moving_gc_wq);
1704 	bioset_exit(&c->bio_split);
1705 	mempool_exit(&c->fill_iter);
1706 	mempool_exit(&c->bio_meta);
1707 	mempool_exit(&c->search);
1708 	kfree(c->devices);
1709 
1710 	list_del(&c->list);
1711 	mutex_unlock(&bch_register_lock);
1712 
1713 	pr_info("Cache set %pU unregistered\n", c->set_uuid);
1714 	wake_up(&unregister_wait);
1715 
1716 	closure_debug_destroy(&c->cl);
1717 	kobject_put(&c->kobj);
1718 }
1719 
cache_set_flush(struct closure * cl)1720 static void cache_set_flush(struct closure *cl)
1721 {
1722 	struct cache_set *c = container_of(cl, struct cache_set, caching);
1723 	struct cache *ca = c->cache;
1724 	struct btree *b;
1725 
1726 	bch_cache_accounting_destroy(&c->accounting);
1727 
1728 	kobject_put(&c->internal);
1729 	kobject_del(&c->kobj);
1730 
1731 	if (!IS_ERR_OR_NULL(c->gc_thread))
1732 		kthread_stop(c->gc_thread);
1733 
1734 	if (!IS_ERR(c->root))
1735 		list_add(&c->root->list, &c->btree_cache);
1736 
1737 	/*
1738 	 * Avoid flushing cached nodes if cache set is retiring
1739 	 * due to too many I/O errors detected.
1740 	 */
1741 	if (!test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1742 		list_for_each_entry(b, &c->btree_cache, list) {
1743 			mutex_lock(&b->write_lock);
1744 			if (btree_node_dirty(b))
1745 				__bch_btree_node_write(b, NULL);
1746 			mutex_unlock(&b->write_lock);
1747 		}
1748 
1749 	if (ca->alloc_thread)
1750 		kthread_stop(ca->alloc_thread);
1751 
1752 	if (c->journal.cur) {
1753 		cancel_delayed_work_sync(&c->journal.work);
1754 		/* flush last journal entry if needed */
1755 		c->journal.work.work.func(&c->journal.work.work);
1756 	}
1757 
1758 	closure_return(cl);
1759 }
1760 
1761 /*
1762  * This function is only called when CACHE_SET_IO_DISABLE is set, which means
1763  * cache set is unregistering due to too many I/O errors. In this condition,
1764  * the bcache device might be stopped, it depends on stop_when_cache_set_failed
1765  * value and whether the broken cache has dirty data:
1766  *
1767  * dc->stop_when_cache_set_failed    dc->has_dirty   stop bcache device
1768  *  BCH_CACHED_STOP_AUTO               0               NO
1769  *  BCH_CACHED_STOP_AUTO               1               YES
1770  *  BCH_CACHED_DEV_STOP_ALWAYS         0               YES
1771  *  BCH_CACHED_DEV_STOP_ALWAYS         1               YES
1772  *
1773  * The expected behavior is, if stop_when_cache_set_failed is configured to
1774  * "auto" via sysfs interface, the bcache device will not be stopped if the
1775  * backing device is clean on the broken cache device.
1776  */
conditional_stop_bcache_device(struct cache_set * c,struct bcache_device * d,struct cached_dev * dc)1777 static void conditional_stop_bcache_device(struct cache_set *c,
1778 					   struct bcache_device *d,
1779 					   struct cached_dev *dc)
1780 {
1781 	if (dc->stop_when_cache_set_failed == BCH_CACHED_DEV_STOP_ALWAYS) {
1782 		pr_warn("stop_when_cache_set_failed of %s is \"always\", stop it for failed cache set %pU.\n",
1783 			d->disk->disk_name, c->set_uuid);
1784 		bcache_device_stop(d);
1785 	} else if (atomic_read(&dc->has_dirty)) {
1786 		/*
1787 		 * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO
1788 		 * and dc->has_dirty == 1
1789 		 */
1790 		pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is dirty, stop it to avoid potential data corruption.\n",
1791 			d->disk->disk_name);
1792 		/*
1793 		 * There might be a small time gap that cache set is
1794 		 * released but bcache device is not. Inside this time
1795 		 * gap, regular I/O requests will directly go into
1796 		 * backing device as no cache set attached to. This
1797 		 * behavior may also introduce potential inconsistence
1798 		 * data in writeback mode while cache is dirty.
1799 		 * Therefore before calling bcache_device_stop() due
1800 		 * to a broken cache device, dc->io_disable should be
1801 		 * explicitly set to true.
1802 		 */
1803 		dc->io_disable = true;
1804 		/* make others know io_disable is true earlier */
1805 		smp_mb();
1806 		bcache_device_stop(d);
1807 	} else {
1808 		/*
1809 		 * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO
1810 		 * and dc->has_dirty == 0
1811 		 */
1812 		pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is clean, keep it alive.\n",
1813 			d->disk->disk_name);
1814 	}
1815 }
1816 
__cache_set_unregister(struct closure * cl)1817 static void __cache_set_unregister(struct closure *cl)
1818 {
1819 	struct cache_set *c = container_of(cl, struct cache_set, caching);
1820 	struct cached_dev *dc;
1821 	struct bcache_device *d;
1822 	size_t i;
1823 
1824 	mutex_lock(&bch_register_lock);
1825 
1826 	for (i = 0; i < c->devices_max_used; i++) {
1827 		d = c->devices[i];
1828 		if (!d)
1829 			continue;
1830 
1831 		if (!UUID_FLASH_ONLY(&c->uuids[i]) &&
1832 		    test_bit(CACHE_SET_UNREGISTERING, &c->flags)) {
1833 			dc = container_of(d, struct cached_dev, disk);
1834 			bch_cached_dev_detach(dc);
1835 			if (test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1836 				conditional_stop_bcache_device(c, d, dc);
1837 		} else {
1838 			bcache_device_stop(d);
1839 		}
1840 	}
1841 
1842 	mutex_unlock(&bch_register_lock);
1843 
1844 	continue_at(cl, cache_set_flush, system_wq);
1845 }
1846 
bch_cache_set_stop(struct cache_set * c)1847 void bch_cache_set_stop(struct cache_set *c)
1848 {
1849 	if (!test_and_set_bit(CACHE_SET_STOPPING, &c->flags))
1850 		/* closure_fn set to __cache_set_unregister() */
1851 		closure_queue(&c->caching);
1852 }
1853 
bch_cache_set_unregister(struct cache_set * c)1854 void bch_cache_set_unregister(struct cache_set *c)
1855 {
1856 	set_bit(CACHE_SET_UNREGISTERING, &c->flags);
1857 	bch_cache_set_stop(c);
1858 }
1859 
1860 #define alloc_meta_bucket_pages(gfp, sb)		\
1861 	((void *) __get_free_pages(__GFP_ZERO|__GFP_COMP|gfp, ilog2(meta_bucket_pages(sb))))
1862 
bch_cache_set_alloc(struct cache_sb * sb)1863 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
1864 {
1865 	int iter_size;
1866 	struct cache *ca = container_of(sb, struct cache, sb);
1867 	struct cache_set *c = kzalloc(sizeof(struct cache_set), GFP_KERNEL);
1868 
1869 	if (!c)
1870 		return NULL;
1871 
1872 	__module_get(THIS_MODULE);
1873 	closure_init(&c->cl, NULL);
1874 	set_closure_fn(&c->cl, cache_set_free, system_wq);
1875 
1876 	closure_init(&c->caching, &c->cl);
1877 	set_closure_fn(&c->caching, __cache_set_unregister, system_wq);
1878 
1879 	/* Maybe create continue_at_noreturn() and use it here? */
1880 	closure_set_stopped(&c->cl);
1881 	closure_put(&c->cl);
1882 
1883 	kobject_init(&c->kobj, &bch_cache_set_ktype);
1884 	kobject_init(&c->internal, &bch_cache_set_internal_ktype);
1885 
1886 	bch_cache_accounting_init(&c->accounting, &c->cl);
1887 
1888 	memcpy(c->set_uuid, sb->set_uuid, 16);
1889 
1890 	c->cache		= ca;
1891 	c->cache->set		= c;
1892 	c->bucket_bits		= ilog2(sb->bucket_size);
1893 	c->block_bits		= ilog2(sb->block_size);
1894 	c->nr_uuids		= meta_bucket_bytes(sb) / sizeof(struct uuid_entry);
1895 	c->devices_max_used	= 0;
1896 	atomic_set(&c->attached_dev_nr, 0);
1897 	c->btree_pages		= meta_bucket_pages(sb);
1898 	if (c->btree_pages > BTREE_MAX_PAGES)
1899 		c->btree_pages = max_t(int, c->btree_pages / 4,
1900 				       BTREE_MAX_PAGES);
1901 
1902 	sema_init(&c->sb_write_mutex, 1);
1903 	mutex_init(&c->bucket_lock);
1904 	init_waitqueue_head(&c->btree_cache_wait);
1905 	spin_lock_init(&c->btree_cannibalize_lock);
1906 	init_waitqueue_head(&c->bucket_wait);
1907 	init_waitqueue_head(&c->gc_wait);
1908 	sema_init(&c->uuid_write_mutex, 1);
1909 
1910 	spin_lock_init(&c->btree_gc_time.lock);
1911 	spin_lock_init(&c->btree_split_time.lock);
1912 	spin_lock_init(&c->btree_read_time.lock);
1913 
1914 	bch_moving_init_cache_set(c);
1915 
1916 	INIT_LIST_HEAD(&c->list);
1917 	INIT_LIST_HEAD(&c->cached_devs);
1918 	INIT_LIST_HEAD(&c->btree_cache);
1919 	INIT_LIST_HEAD(&c->btree_cache_freeable);
1920 	INIT_LIST_HEAD(&c->btree_cache_freed);
1921 	INIT_LIST_HEAD(&c->data_buckets);
1922 
1923 	iter_size = ((meta_bucket_pages(sb) * PAGE_SECTORS) / sb->block_size + 1) *
1924 		sizeof(struct btree_iter_set);
1925 
1926 	c->devices = kcalloc(c->nr_uuids, sizeof(void *), GFP_KERNEL);
1927 	if (!c->devices)
1928 		goto err;
1929 
1930 	if (mempool_init_slab_pool(&c->search, 32, bch_search_cache))
1931 		goto err;
1932 
1933 	if (mempool_init_kmalloc_pool(&c->bio_meta, 2,
1934 			sizeof(struct bbio) +
1935 			sizeof(struct bio_vec) * meta_bucket_pages(sb)))
1936 		goto err;
1937 
1938 	if (mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size))
1939 		goto err;
1940 
1941 	if (bioset_init(&c->bio_split, 4, offsetof(struct bbio, bio),
1942 			BIOSET_NEED_RESCUER))
1943 		goto err;
1944 
1945 	c->uuids = alloc_meta_bucket_pages(GFP_KERNEL, sb);
1946 	if (!c->uuids)
1947 		goto err;
1948 
1949 	c->moving_gc_wq = alloc_workqueue("bcache_gc", WQ_MEM_RECLAIM, 0);
1950 	if (!c->moving_gc_wq)
1951 		goto err;
1952 
1953 	if (bch_journal_alloc(c))
1954 		goto err;
1955 
1956 	if (bch_btree_cache_alloc(c))
1957 		goto err;
1958 
1959 	if (bch_open_buckets_alloc(c))
1960 		goto err;
1961 
1962 	if (bch_bset_sort_state_init(&c->sort, ilog2(c->btree_pages)))
1963 		goto err;
1964 
1965 	c->congested_read_threshold_us	= 2000;
1966 	c->congested_write_threshold_us	= 20000;
1967 	c->error_limit	= DEFAULT_IO_ERROR_LIMIT;
1968 	c->idle_max_writeback_rate_enabled = 1;
1969 	WARN_ON(test_and_clear_bit(CACHE_SET_IO_DISABLE, &c->flags));
1970 
1971 	return c;
1972 err:
1973 	bch_cache_set_unregister(c);
1974 	return NULL;
1975 }
1976 
run_cache_set(struct cache_set * c)1977 static int run_cache_set(struct cache_set *c)
1978 {
1979 	const char *err = "cannot allocate memory";
1980 	struct cached_dev *dc, *t;
1981 	struct cache *ca = c->cache;
1982 	struct closure cl;
1983 	LIST_HEAD(journal);
1984 	struct journal_replay *l;
1985 
1986 	closure_init_stack(&cl);
1987 
1988 	c->nbuckets = ca->sb.nbuckets;
1989 	set_gc_sectors(c);
1990 
1991 	if (CACHE_SYNC(&c->cache->sb)) {
1992 		struct bkey *k;
1993 		struct jset *j;
1994 
1995 		err = "cannot allocate memory for journal";
1996 		if (bch_journal_read(c, &journal))
1997 			goto err;
1998 
1999 		pr_debug("btree_journal_read() done\n");
2000 
2001 		err = "no journal entries found";
2002 		if (list_empty(&journal))
2003 			goto err;
2004 
2005 		j = &list_entry(journal.prev, struct journal_replay, list)->j;
2006 
2007 		err = "IO error reading priorities";
2008 		if (prio_read(ca, j->prio_bucket[ca->sb.nr_this_dev]))
2009 			goto err;
2010 
2011 		/*
2012 		 * If prio_read() fails it'll call cache_set_error and we'll
2013 		 * tear everything down right away, but if we perhaps checked
2014 		 * sooner we could avoid journal replay.
2015 		 */
2016 
2017 		k = &j->btree_root;
2018 
2019 		err = "bad btree root";
2020 		if (__bch_btree_ptr_invalid(c, k))
2021 			goto err;
2022 
2023 		err = "error reading btree root";
2024 		c->root = bch_btree_node_get(c, NULL, k,
2025 					     j->btree_level,
2026 					     true, NULL);
2027 		if (IS_ERR(c->root))
2028 			goto err;
2029 
2030 		list_del_init(&c->root->list);
2031 		rw_unlock(true, c->root);
2032 
2033 		err = uuid_read(c, j, &cl);
2034 		if (err)
2035 			goto err;
2036 
2037 		err = "error in recovery";
2038 		if (bch_btree_check(c))
2039 			goto err;
2040 
2041 		bch_journal_mark(c, &journal);
2042 		bch_initial_gc_finish(c);
2043 		pr_debug("btree_check() done\n");
2044 
2045 		/*
2046 		 * bcache_journal_next() can't happen sooner, or
2047 		 * btree_gc_finish() will give spurious errors about last_gc >
2048 		 * gc_gen - this is a hack but oh well.
2049 		 */
2050 		bch_journal_next(&c->journal);
2051 
2052 		err = "error starting allocator thread";
2053 		if (bch_cache_allocator_start(ca))
2054 			goto err;
2055 
2056 		/*
2057 		 * First place it's safe to allocate: btree_check() and
2058 		 * btree_gc_finish() have to run before we have buckets to
2059 		 * allocate, and bch_bucket_alloc_set() might cause a journal
2060 		 * entry to be written so bcache_journal_next() has to be called
2061 		 * first.
2062 		 *
2063 		 * If the uuids were in the old format we have to rewrite them
2064 		 * before the next journal entry is written:
2065 		 */
2066 		if (j->version < BCACHE_JSET_VERSION_UUID)
2067 			__uuid_write(c);
2068 
2069 		err = "bcache: replay journal failed";
2070 		if (bch_journal_replay(c, &journal))
2071 			goto err;
2072 	} else {
2073 		unsigned int j;
2074 
2075 		pr_notice("invalidating existing data\n");
2076 		ca->sb.keys = clamp_t(int, ca->sb.nbuckets >> 7,
2077 					2, SB_JOURNAL_BUCKETS);
2078 
2079 		for (j = 0; j < ca->sb.keys; j++)
2080 			ca->sb.d[j] = ca->sb.first_bucket + j;
2081 
2082 		bch_initial_gc_finish(c);
2083 
2084 		err = "error starting allocator thread";
2085 		if (bch_cache_allocator_start(ca))
2086 			goto err;
2087 
2088 		mutex_lock(&c->bucket_lock);
2089 		bch_prio_write(ca, true);
2090 		mutex_unlock(&c->bucket_lock);
2091 
2092 		err = "cannot allocate new UUID bucket";
2093 		if (__uuid_write(c))
2094 			goto err;
2095 
2096 		err = "cannot allocate new btree root";
2097 		c->root = __bch_btree_node_alloc(c, NULL, 0, true, NULL);
2098 		if (IS_ERR(c->root))
2099 			goto err;
2100 
2101 		mutex_lock(&c->root->write_lock);
2102 		bkey_copy_key(&c->root->key, &MAX_KEY);
2103 		bch_btree_node_write(c->root, &cl);
2104 		mutex_unlock(&c->root->write_lock);
2105 
2106 		bch_btree_set_root(c->root);
2107 		rw_unlock(true, c->root);
2108 
2109 		/*
2110 		 * We don't want to write the first journal entry until
2111 		 * everything is set up - fortunately journal entries won't be
2112 		 * written until the SET_CACHE_SYNC() here:
2113 		 */
2114 		SET_CACHE_SYNC(&c->cache->sb, true);
2115 
2116 		bch_journal_next(&c->journal);
2117 		bch_journal_meta(c, &cl);
2118 	}
2119 
2120 	err = "error starting gc thread";
2121 	if (bch_gc_thread_start(c))
2122 		goto err;
2123 
2124 	closure_sync(&cl);
2125 	c->cache->sb.last_mount = (u32)ktime_get_real_seconds();
2126 	bcache_write_super(c);
2127 
2128 	if (bch_has_feature_obso_large_bucket(&c->cache->sb))
2129 		pr_err("Detect obsoleted large bucket layout, all attached bcache device will be read-only\n");
2130 
2131 	list_for_each_entry_safe(dc, t, &uncached_devices, list)
2132 		bch_cached_dev_attach(dc, c, NULL);
2133 
2134 	flash_devs_run(c);
2135 
2136 	bch_journal_space_reserve(&c->journal);
2137 	set_bit(CACHE_SET_RUNNING, &c->flags);
2138 	return 0;
2139 err:
2140 	while (!list_empty(&journal)) {
2141 		l = list_first_entry(&journal, struct journal_replay, list);
2142 		list_del(&l->list);
2143 		kfree(l);
2144 	}
2145 
2146 	closure_sync(&cl);
2147 
2148 	bch_cache_set_error(c, "%s", err);
2149 
2150 	return -EIO;
2151 }
2152 
register_cache_set(struct cache * ca)2153 static const char *register_cache_set(struct cache *ca)
2154 {
2155 	char buf[12];
2156 	const char *err = "cannot allocate memory";
2157 	struct cache_set *c;
2158 
2159 	list_for_each_entry(c, &bch_cache_sets, list)
2160 		if (!memcmp(c->set_uuid, ca->sb.set_uuid, 16)) {
2161 			if (c->cache)
2162 				return "duplicate cache set member";
2163 
2164 			goto found;
2165 		}
2166 
2167 	c = bch_cache_set_alloc(&ca->sb);
2168 	if (!c)
2169 		return err;
2170 
2171 	err = "error creating kobject";
2172 	if (kobject_add(&c->kobj, bcache_kobj, "%pU", c->set_uuid) ||
2173 	    kobject_add(&c->internal, &c->kobj, "internal"))
2174 		goto err;
2175 
2176 	if (bch_cache_accounting_add_kobjs(&c->accounting, &c->kobj))
2177 		goto err;
2178 
2179 	bch_debug_init_cache_set(c);
2180 
2181 	list_add(&c->list, &bch_cache_sets);
2182 found:
2183 	sprintf(buf, "cache%i", ca->sb.nr_this_dev);
2184 	if (sysfs_create_link(&ca->kobj, &c->kobj, "set") ||
2185 	    sysfs_create_link(&c->kobj, &ca->kobj, buf))
2186 		goto err;
2187 
2188 	kobject_get(&ca->kobj);
2189 	ca->set = c;
2190 	ca->set->cache = ca;
2191 
2192 	err = "failed to run cache set";
2193 	if (run_cache_set(c) < 0)
2194 		goto err;
2195 
2196 	return NULL;
2197 err:
2198 	bch_cache_set_unregister(c);
2199 	return err;
2200 }
2201 
2202 /* Cache device */
2203 
2204 /* When ca->kobj released */
bch_cache_release(struct kobject * kobj)2205 void bch_cache_release(struct kobject *kobj)
2206 {
2207 	struct cache *ca = container_of(kobj, struct cache, kobj);
2208 	unsigned int i;
2209 
2210 	if (ca->set) {
2211 		BUG_ON(ca->set->cache != ca);
2212 		ca->set->cache = NULL;
2213 	}
2214 
2215 	free_pages((unsigned long) ca->disk_buckets, ilog2(meta_bucket_pages(&ca->sb)));
2216 	kfree(ca->prio_buckets);
2217 	vfree(ca->buckets);
2218 
2219 	free_heap(&ca->heap);
2220 	free_fifo(&ca->free_inc);
2221 
2222 	for (i = 0; i < RESERVE_NR; i++)
2223 		free_fifo(&ca->free[i]);
2224 
2225 	if (ca->sb_disk)
2226 		put_page(virt_to_page(ca->sb_disk));
2227 
2228 	if (!IS_ERR_OR_NULL(ca->bdev))
2229 		blkdev_put(ca->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2230 
2231 	kfree(ca);
2232 	module_put(THIS_MODULE);
2233 }
2234 
cache_alloc(struct cache * ca)2235 static int cache_alloc(struct cache *ca)
2236 {
2237 	size_t free;
2238 	size_t btree_buckets;
2239 	struct bucket *b;
2240 	int ret = -ENOMEM;
2241 	const char *err = NULL;
2242 
2243 	__module_get(THIS_MODULE);
2244 	kobject_init(&ca->kobj, &bch_cache_ktype);
2245 
2246 	bio_init(&ca->journal.bio, ca->journal.bio.bi_inline_vecs, 8);
2247 
2248 	/*
2249 	 * when ca->sb.njournal_buckets is not zero, journal exists,
2250 	 * and in bch_journal_replay(), tree node may split,
2251 	 * so bucket of RESERVE_BTREE type is needed,
2252 	 * the worst situation is all journal buckets are valid journal,
2253 	 * and all the keys need to replay,
2254 	 * so the number of  RESERVE_BTREE type buckets should be as much
2255 	 * as journal buckets
2256 	 */
2257 	btree_buckets = ca->sb.njournal_buckets ?: 8;
2258 	free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
2259 	if (!free) {
2260 		ret = -EPERM;
2261 		err = "ca->sb.nbuckets is too small";
2262 		goto err_free;
2263 	}
2264 
2265 	if (!init_fifo(&ca->free[RESERVE_BTREE], btree_buckets,
2266 						GFP_KERNEL)) {
2267 		err = "ca->free[RESERVE_BTREE] alloc failed";
2268 		goto err_btree_alloc;
2269 	}
2270 
2271 	if (!init_fifo_exact(&ca->free[RESERVE_PRIO], prio_buckets(ca),
2272 							GFP_KERNEL)) {
2273 		err = "ca->free[RESERVE_PRIO] alloc failed";
2274 		goto err_prio_alloc;
2275 	}
2276 
2277 	if (!init_fifo(&ca->free[RESERVE_MOVINGGC], free, GFP_KERNEL)) {
2278 		err = "ca->free[RESERVE_MOVINGGC] alloc failed";
2279 		goto err_movinggc_alloc;
2280 	}
2281 
2282 	if (!init_fifo(&ca->free[RESERVE_NONE], free, GFP_KERNEL)) {
2283 		err = "ca->free[RESERVE_NONE] alloc failed";
2284 		goto err_none_alloc;
2285 	}
2286 
2287 	if (!init_fifo(&ca->free_inc, free << 2, GFP_KERNEL)) {
2288 		err = "ca->free_inc alloc failed";
2289 		goto err_free_inc_alloc;
2290 	}
2291 
2292 	if (!init_heap(&ca->heap, free << 3, GFP_KERNEL)) {
2293 		err = "ca->heap alloc failed";
2294 		goto err_heap_alloc;
2295 	}
2296 
2297 	ca->buckets = vzalloc(array_size(sizeof(struct bucket),
2298 			      ca->sb.nbuckets));
2299 	if (!ca->buckets) {
2300 		err = "ca->buckets alloc failed";
2301 		goto err_buckets_alloc;
2302 	}
2303 
2304 	ca->prio_buckets = kzalloc(array3_size(sizeof(uint64_t),
2305 				   prio_buckets(ca), 2),
2306 				   GFP_KERNEL);
2307 	if (!ca->prio_buckets) {
2308 		err = "ca->prio_buckets alloc failed";
2309 		goto err_prio_buckets_alloc;
2310 	}
2311 
2312 	ca->disk_buckets = alloc_meta_bucket_pages(GFP_KERNEL, &ca->sb);
2313 	if (!ca->disk_buckets) {
2314 		err = "ca->disk_buckets alloc failed";
2315 		goto err_disk_buckets_alloc;
2316 	}
2317 
2318 	ca->prio_last_buckets = ca->prio_buckets + prio_buckets(ca);
2319 
2320 	for_each_bucket(b, ca)
2321 		atomic_set(&b->pin, 0);
2322 	return 0;
2323 
2324 err_disk_buckets_alloc:
2325 	kfree(ca->prio_buckets);
2326 err_prio_buckets_alloc:
2327 	vfree(ca->buckets);
2328 err_buckets_alloc:
2329 	free_heap(&ca->heap);
2330 err_heap_alloc:
2331 	free_fifo(&ca->free_inc);
2332 err_free_inc_alloc:
2333 	free_fifo(&ca->free[RESERVE_NONE]);
2334 err_none_alloc:
2335 	free_fifo(&ca->free[RESERVE_MOVINGGC]);
2336 err_movinggc_alloc:
2337 	free_fifo(&ca->free[RESERVE_PRIO]);
2338 err_prio_alloc:
2339 	free_fifo(&ca->free[RESERVE_BTREE]);
2340 err_btree_alloc:
2341 err_free:
2342 	module_put(THIS_MODULE);
2343 	if (err)
2344 		pr_notice("error %s: %s\n", ca->cache_dev_name, err);
2345 	return ret;
2346 }
2347 
register_cache(struct cache_sb * sb,struct cache_sb_disk * sb_disk,struct block_device * bdev,struct cache * ca)2348 static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
2349 				struct block_device *bdev, struct cache *ca)
2350 {
2351 	const char *err = NULL; /* must be set for any error case */
2352 	int ret = 0;
2353 
2354 	bdevname(bdev, ca->cache_dev_name);
2355 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
2356 	ca->bdev = bdev;
2357 	ca->bdev->bd_holder = ca;
2358 	ca->sb_disk = sb_disk;
2359 
2360 	if (blk_queue_discard(bdev_get_queue(bdev)))
2361 		ca->discard = CACHE_DISCARD(&ca->sb);
2362 
2363 	ret = cache_alloc(ca);
2364 	if (ret != 0) {
2365 		/*
2366 		 * If we failed here, it means ca->kobj is not initialized yet,
2367 		 * kobject_put() won't be called and there is no chance to
2368 		 * call blkdev_put() to bdev in bch_cache_release(). So we
2369 		 * explicitly call blkdev_put() here.
2370 		 */
2371 		blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2372 		if (ret == -ENOMEM)
2373 			err = "cache_alloc(): -ENOMEM";
2374 		else if (ret == -EPERM)
2375 			err = "cache_alloc(): cache device is too small";
2376 		else
2377 			err = "cache_alloc(): unknown error";
2378 		goto err;
2379 	}
2380 
2381 	if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
2382 		err = "error calling kobject_add";
2383 		ret = -ENOMEM;
2384 		goto out;
2385 	}
2386 
2387 	mutex_lock(&bch_register_lock);
2388 	err = register_cache_set(ca);
2389 	mutex_unlock(&bch_register_lock);
2390 
2391 	if (err) {
2392 		ret = -ENODEV;
2393 		goto out;
2394 	}
2395 
2396 	pr_info("registered cache device %s\n", ca->cache_dev_name);
2397 
2398 out:
2399 	kobject_put(&ca->kobj);
2400 
2401 err:
2402 	if (err)
2403 		pr_notice("error %s: %s\n", ca->cache_dev_name, err);
2404 
2405 	return ret;
2406 }
2407 
2408 /* Global interfaces/init */
2409 
2410 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
2411 			       const char *buffer, size_t size);
2412 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k,
2413 					 struct kobj_attribute *attr,
2414 					 const char *buffer, size_t size);
2415 
2416 kobj_attribute_write(register,		register_bcache);
2417 kobj_attribute_write(register_quiet,	register_bcache);
2418 kobj_attribute_write(pendings_cleanup,	bch_pending_bdevs_cleanup);
2419 
bch_is_open_backing(dev_t dev)2420 static bool bch_is_open_backing(dev_t dev)
2421 {
2422 	struct cache_set *c, *tc;
2423 	struct cached_dev *dc, *t;
2424 
2425 	list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2426 		list_for_each_entry_safe(dc, t, &c->cached_devs, list)
2427 			if (dc->bdev->bd_dev == dev)
2428 				return true;
2429 	list_for_each_entry_safe(dc, t, &uncached_devices, list)
2430 		if (dc->bdev->bd_dev == dev)
2431 			return true;
2432 	return false;
2433 }
2434 
bch_is_open_cache(dev_t dev)2435 static bool bch_is_open_cache(dev_t dev)
2436 {
2437 	struct cache_set *c, *tc;
2438 
2439 	list_for_each_entry_safe(c, tc, &bch_cache_sets, list) {
2440 		struct cache *ca = c->cache;
2441 
2442 		if (ca->bdev->bd_dev == dev)
2443 			return true;
2444 	}
2445 
2446 	return false;
2447 }
2448 
bch_is_open(dev_t dev)2449 static bool bch_is_open(dev_t dev)
2450 {
2451 	return bch_is_open_cache(dev) || bch_is_open_backing(dev);
2452 }
2453 
2454 struct async_reg_args {
2455 	struct delayed_work reg_work;
2456 	char *path;
2457 	struct cache_sb *sb;
2458 	struct cache_sb_disk *sb_disk;
2459 	struct block_device *bdev;
2460 };
2461 
register_bdev_worker(struct work_struct * work)2462 static void register_bdev_worker(struct work_struct *work)
2463 {
2464 	int fail = false;
2465 	struct async_reg_args *args =
2466 		container_of(work, struct async_reg_args, reg_work.work);
2467 	struct cached_dev *dc;
2468 
2469 	dc = kzalloc(sizeof(*dc), GFP_KERNEL);
2470 	if (!dc) {
2471 		fail = true;
2472 		put_page(virt_to_page(args->sb_disk));
2473 		blkdev_put(args->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
2474 		goto out;
2475 	}
2476 
2477 	mutex_lock(&bch_register_lock);
2478 	if (register_bdev(args->sb, args->sb_disk, args->bdev, dc) < 0)
2479 		fail = true;
2480 	mutex_unlock(&bch_register_lock);
2481 
2482 out:
2483 	if (fail)
2484 		pr_info("error %s: fail to register backing device\n",
2485 			args->path);
2486 	kfree(args->sb);
2487 	kfree(args->path);
2488 	kfree(args);
2489 	module_put(THIS_MODULE);
2490 }
2491 
register_cache_worker(struct work_struct * work)2492 static void register_cache_worker(struct work_struct *work)
2493 {
2494 	int fail = false;
2495 	struct async_reg_args *args =
2496 		container_of(work, struct async_reg_args, reg_work.work);
2497 	struct cache *ca;
2498 
2499 	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2500 	if (!ca) {
2501 		fail = true;
2502 		put_page(virt_to_page(args->sb_disk));
2503 		blkdev_put(args->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
2504 		goto out;
2505 	}
2506 
2507 	/* blkdev_put() will be called in bch_cache_release() */
2508 	if (register_cache(args->sb, args->sb_disk, args->bdev, ca) != 0)
2509 		fail = true;
2510 
2511 out:
2512 	if (fail)
2513 		pr_info("error %s: fail to register cache device\n",
2514 			args->path);
2515 	kfree(args->sb);
2516 	kfree(args->path);
2517 	kfree(args);
2518 	module_put(THIS_MODULE);
2519 }
2520 
register_device_async(struct async_reg_args * args)2521 static void register_device_async(struct async_reg_args *args)
2522 {
2523 	if (SB_IS_BDEV(args->sb))
2524 		INIT_DELAYED_WORK(&args->reg_work, register_bdev_worker);
2525 	else
2526 		INIT_DELAYED_WORK(&args->reg_work, register_cache_worker);
2527 
2528 	/* 10 jiffies is enough for a delay */
2529 	queue_delayed_work(system_wq, &args->reg_work, 10);
2530 }
2531 
register_bcache(struct kobject * k,struct kobj_attribute * attr,const char * buffer,size_t size)2532 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
2533 			       const char *buffer, size_t size)
2534 {
2535 	const char *err;
2536 	char *path = NULL;
2537 	struct cache_sb *sb;
2538 	struct cache_sb_disk *sb_disk;
2539 	struct block_device *bdev;
2540 	ssize_t ret;
2541 	bool async_registration = false;
2542 
2543 #ifdef CONFIG_BCACHE_ASYNC_REGISTRATION
2544 	async_registration = true;
2545 #endif
2546 
2547 	ret = -EBUSY;
2548 	err = "failed to reference bcache module";
2549 	if (!try_module_get(THIS_MODULE))
2550 		goto out;
2551 
2552 	/* For latest state of bcache_is_reboot */
2553 	smp_mb();
2554 	err = "bcache is in reboot";
2555 	if (bcache_is_reboot)
2556 		goto out_module_put;
2557 
2558 	ret = -ENOMEM;
2559 	err = "cannot allocate memory";
2560 	path = kstrndup(buffer, size, GFP_KERNEL);
2561 	if (!path)
2562 		goto out_module_put;
2563 
2564 	sb = kmalloc(sizeof(struct cache_sb), GFP_KERNEL);
2565 	if (!sb)
2566 		goto out_free_path;
2567 
2568 	ret = -EINVAL;
2569 	err = "failed to open device";
2570 	bdev = blkdev_get_by_path(strim(path),
2571 				  FMODE_READ|FMODE_WRITE|FMODE_EXCL,
2572 				  sb);
2573 	if (IS_ERR(bdev)) {
2574 		if (bdev == ERR_PTR(-EBUSY)) {
2575 			dev_t dev;
2576 
2577 			mutex_lock(&bch_register_lock);
2578 			if (lookup_bdev(strim(path), &dev) == 0 &&
2579 			    bch_is_open(dev))
2580 				err = "device already registered";
2581 			else
2582 				err = "device busy";
2583 			mutex_unlock(&bch_register_lock);
2584 			if (attr == &ksysfs_register_quiet)
2585 				goto done;
2586 		}
2587 		goto out_free_sb;
2588 	}
2589 
2590 	err = "failed to set blocksize";
2591 	if (set_blocksize(bdev, 4096))
2592 		goto out_blkdev_put;
2593 
2594 	err = read_super(sb, bdev, &sb_disk);
2595 	if (err)
2596 		goto out_blkdev_put;
2597 
2598 	err = "failed to register device";
2599 
2600 	if (async_registration) {
2601 		/* register in asynchronous way */
2602 		struct async_reg_args *args =
2603 			kzalloc(sizeof(struct async_reg_args), GFP_KERNEL);
2604 
2605 		if (!args) {
2606 			ret = -ENOMEM;
2607 			err = "cannot allocate memory";
2608 			goto out_put_sb_page;
2609 		}
2610 
2611 		args->path	= path;
2612 		args->sb	= sb;
2613 		args->sb_disk	= sb_disk;
2614 		args->bdev	= bdev;
2615 		register_device_async(args);
2616 		/* No wait and returns to user space */
2617 		goto async_done;
2618 	}
2619 
2620 	if (SB_IS_BDEV(sb)) {
2621 		struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL);
2622 
2623 		if (!dc)
2624 			goto out_put_sb_page;
2625 
2626 		mutex_lock(&bch_register_lock);
2627 		ret = register_bdev(sb, sb_disk, bdev, dc);
2628 		mutex_unlock(&bch_register_lock);
2629 		/* blkdev_put() will be called in cached_dev_free() */
2630 		if (ret < 0)
2631 			goto out_free_sb;
2632 	} else {
2633 		struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2634 
2635 		if (!ca)
2636 			goto out_put_sb_page;
2637 
2638 		/* blkdev_put() will be called in bch_cache_release() */
2639 		if (register_cache(sb, sb_disk, bdev, ca) != 0)
2640 			goto out_free_sb;
2641 	}
2642 
2643 done:
2644 	kfree(sb);
2645 	kfree(path);
2646 	module_put(THIS_MODULE);
2647 async_done:
2648 	return size;
2649 
2650 out_put_sb_page:
2651 	put_page(virt_to_page(sb_disk));
2652 out_blkdev_put:
2653 	blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
2654 out_free_sb:
2655 	kfree(sb);
2656 out_free_path:
2657 	kfree(path);
2658 	path = NULL;
2659 out_module_put:
2660 	module_put(THIS_MODULE);
2661 out:
2662 	pr_info("error %s: %s\n", path?path:"", err);
2663 	return ret;
2664 }
2665 
2666 
2667 struct pdev {
2668 	struct list_head list;
2669 	struct cached_dev *dc;
2670 };
2671 
bch_pending_bdevs_cleanup(struct kobject * k,struct kobj_attribute * attr,const char * buffer,size_t size)2672 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k,
2673 					 struct kobj_attribute *attr,
2674 					 const char *buffer,
2675 					 size_t size)
2676 {
2677 	LIST_HEAD(pending_devs);
2678 	ssize_t ret = size;
2679 	struct cached_dev *dc, *tdc;
2680 	struct pdev *pdev, *tpdev;
2681 	struct cache_set *c, *tc;
2682 
2683 	mutex_lock(&bch_register_lock);
2684 	list_for_each_entry_safe(dc, tdc, &uncached_devices, list) {
2685 		pdev = kmalloc(sizeof(struct pdev), GFP_KERNEL);
2686 		if (!pdev)
2687 			break;
2688 		pdev->dc = dc;
2689 		list_add(&pdev->list, &pending_devs);
2690 	}
2691 
2692 	list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) {
2693 		char *pdev_set_uuid = pdev->dc->sb.set_uuid;
2694 		list_for_each_entry_safe(c, tc, &bch_cache_sets, list) {
2695 			char *set_uuid = c->set_uuid;
2696 
2697 			if (!memcmp(pdev_set_uuid, set_uuid, 16)) {
2698 				list_del(&pdev->list);
2699 				kfree(pdev);
2700 				break;
2701 			}
2702 		}
2703 	}
2704 	mutex_unlock(&bch_register_lock);
2705 
2706 	list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) {
2707 		pr_info("delete pdev %p\n", pdev);
2708 		list_del(&pdev->list);
2709 		bcache_device_stop(&pdev->dc->disk);
2710 		kfree(pdev);
2711 	}
2712 
2713 	return ret;
2714 }
2715 
bcache_reboot(struct notifier_block * n,unsigned long code,void * x)2716 static int bcache_reboot(struct notifier_block *n, unsigned long code, void *x)
2717 {
2718 	if (bcache_is_reboot)
2719 		return NOTIFY_DONE;
2720 
2721 	if (code == SYS_DOWN ||
2722 	    code == SYS_HALT ||
2723 	    code == SYS_POWER_OFF) {
2724 		DEFINE_WAIT(wait);
2725 		unsigned long start = jiffies;
2726 		bool stopped = false;
2727 
2728 		struct cache_set *c, *tc;
2729 		struct cached_dev *dc, *tdc;
2730 
2731 		mutex_lock(&bch_register_lock);
2732 
2733 		if (bcache_is_reboot)
2734 			goto out;
2735 
2736 		/* New registration is rejected since now */
2737 		bcache_is_reboot = true;
2738 		/*
2739 		 * Make registering caller (if there is) on other CPU
2740 		 * core know bcache_is_reboot set to true earlier
2741 		 */
2742 		smp_mb();
2743 
2744 		if (list_empty(&bch_cache_sets) &&
2745 		    list_empty(&uncached_devices))
2746 			goto out;
2747 
2748 		mutex_unlock(&bch_register_lock);
2749 
2750 		pr_info("Stopping all devices:\n");
2751 
2752 		/*
2753 		 * The reason bch_register_lock is not held to call
2754 		 * bch_cache_set_stop() and bcache_device_stop() is to
2755 		 * avoid potential deadlock during reboot, because cache
2756 		 * set or bcache device stopping process will acqurie
2757 		 * bch_register_lock too.
2758 		 *
2759 		 * We are safe here because bcache_is_reboot sets to
2760 		 * true already, register_bcache() will reject new
2761 		 * registration now. bcache_is_reboot also makes sure
2762 		 * bcache_reboot() won't be re-entered on by other thread,
2763 		 * so there is no race in following list iteration by
2764 		 * list_for_each_entry_safe().
2765 		 */
2766 		list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2767 			bch_cache_set_stop(c);
2768 
2769 		list_for_each_entry_safe(dc, tdc, &uncached_devices, list)
2770 			bcache_device_stop(&dc->disk);
2771 
2772 
2773 		/*
2774 		 * Give an early chance for other kthreads and
2775 		 * kworkers to stop themselves
2776 		 */
2777 		schedule();
2778 
2779 		/* What's a condition variable? */
2780 		while (1) {
2781 			long timeout = start + 10 * HZ - jiffies;
2782 
2783 			mutex_lock(&bch_register_lock);
2784 			stopped = list_empty(&bch_cache_sets) &&
2785 				list_empty(&uncached_devices);
2786 
2787 			if (timeout < 0 || stopped)
2788 				break;
2789 
2790 			prepare_to_wait(&unregister_wait, &wait,
2791 					TASK_UNINTERRUPTIBLE);
2792 
2793 			mutex_unlock(&bch_register_lock);
2794 			schedule_timeout(timeout);
2795 		}
2796 
2797 		finish_wait(&unregister_wait, &wait);
2798 
2799 		if (stopped)
2800 			pr_info("All devices stopped\n");
2801 		else
2802 			pr_notice("Timeout waiting for devices to be closed\n");
2803 out:
2804 		mutex_unlock(&bch_register_lock);
2805 	}
2806 
2807 	return NOTIFY_DONE;
2808 }
2809 
2810 static struct notifier_block reboot = {
2811 	.notifier_call	= bcache_reboot,
2812 	.priority	= INT_MAX, /* before any real devices */
2813 };
2814 
bcache_exit(void)2815 static void bcache_exit(void)
2816 {
2817 	bch_debug_exit();
2818 	bch_request_exit();
2819 	if (bcache_kobj)
2820 		kobject_put(bcache_kobj);
2821 	if (bcache_wq)
2822 		destroy_workqueue(bcache_wq);
2823 	if (bch_journal_wq)
2824 		destroy_workqueue(bch_journal_wq);
2825 	if (bch_flush_wq)
2826 		destroy_workqueue(bch_flush_wq);
2827 	bch_btree_exit();
2828 
2829 	if (bcache_major)
2830 		unregister_blkdev(bcache_major, "bcache");
2831 	unregister_reboot_notifier(&reboot);
2832 	mutex_destroy(&bch_register_lock);
2833 }
2834 
2835 /* Check and fixup module parameters */
check_module_parameters(void)2836 static void check_module_parameters(void)
2837 {
2838 	if (bch_cutoff_writeback_sync == 0)
2839 		bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC;
2840 	else if (bch_cutoff_writeback_sync > CUTOFF_WRITEBACK_SYNC_MAX) {
2841 		pr_warn("set bch_cutoff_writeback_sync (%u) to max value %u\n",
2842 			bch_cutoff_writeback_sync, CUTOFF_WRITEBACK_SYNC_MAX);
2843 		bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC_MAX;
2844 	}
2845 
2846 	if (bch_cutoff_writeback == 0)
2847 		bch_cutoff_writeback = CUTOFF_WRITEBACK;
2848 	else if (bch_cutoff_writeback > CUTOFF_WRITEBACK_MAX) {
2849 		pr_warn("set bch_cutoff_writeback (%u) to max value %u\n",
2850 			bch_cutoff_writeback, CUTOFF_WRITEBACK_MAX);
2851 		bch_cutoff_writeback = CUTOFF_WRITEBACK_MAX;
2852 	}
2853 
2854 	if (bch_cutoff_writeback > bch_cutoff_writeback_sync) {
2855 		pr_warn("set bch_cutoff_writeback (%u) to %u\n",
2856 			bch_cutoff_writeback, bch_cutoff_writeback_sync);
2857 		bch_cutoff_writeback = bch_cutoff_writeback_sync;
2858 	}
2859 }
2860 
bcache_init(void)2861 static int __init bcache_init(void)
2862 {
2863 	static const struct attribute *files[] = {
2864 		&ksysfs_register.attr,
2865 		&ksysfs_register_quiet.attr,
2866 		&ksysfs_pendings_cleanup.attr,
2867 		NULL
2868 	};
2869 
2870 	check_module_parameters();
2871 
2872 	mutex_init(&bch_register_lock);
2873 	init_waitqueue_head(&unregister_wait);
2874 	register_reboot_notifier(&reboot);
2875 
2876 	bcache_major = register_blkdev(0, "bcache");
2877 	if (bcache_major < 0) {
2878 		unregister_reboot_notifier(&reboot);
2879 		mutex_destroy(&bch_register_lock);
2880 		return bcache_major;
2881 	}
2882 
2883 	if (bch_btree_init())
2884 		goto err;
2885 
2886 	bcache_wq = alloc_workqueue("bcache", WQ_MEM_RECLAIM, 0);
2887 	if (!bcache_wq)
2888 		goto err;
2889 
2890 	/*
2891 	 * Let's not make this `WQ_MEM_RECLAIM` for the following reasons:
2892 	 *
2893 	 * 1. It used `system_wq` before which also does no memory reclaim.
2894 	 * 2. With `WQ_MEM_RECLAIM` desktop stalls, increased boot times, and
2895 	 *    reduced throughput can be observed.
2896 	 *
2897 	 * We still want to user our own queue to not congest the `system_wq`.
2898 	 */
2899 	bch_flush_wq = alloc_workqueue("bch_flush", 0, 0);
2900 	if (!bch_flush_wq)
2901 		goto err;
2902 
2903 	bch_journal_wq = alloc_workqueue("bch_journal", WQ_MEM_RECLAIM, 0);
2904 	if (!bch_journal_wq)
2905 		goto err;
2906 
2907 	bcache_kobj = kobject_create_and_add("bcache", fs_kobj);
2908 	if (!bcache_kobj)
2909 		goto err;
2910 
2911 	if (bch_request_init() ||
2912 	    sysfs_create_files(bcache_kobj, files))
2913 		goto err;
2914 
2915 	bch_debug_init();
2916 	closure_debug_init();
2917 
2918 	bcache_is_reboot = false;
2919 
2920 	return 0;
2921 err:
2922 	bcache_exit();
2923 	return -ENOMEM;
2924 }
2925 
2926 /*
2927  * Module hooks
2928  */
2929 module_exit(bcache_exit);
2930 module_init(bcache_init);
2931 
2932 module_param(bch_cutoff_writeback, uint, 0);
2933 MODULE_PARM_DESC(bch_cutoff_writeback, "threshold to cutoff writeback");
2934 
2935 module_param(bch_cutoff_writeback_sync, uint, 0);
2936 MODULE_PARM_DESC(bch_cutoff_writeback_sync, "hard threshold to cutoff writeback");
2937 
2938 MODULE_DESCRIPTION("Bcache: a Linux block layer cache");
2939 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>");
2940 MODULE_LICENSE("GPL");
2941