xref: /openbmc/linux/drivers/md/raid5-cache.c (revision abfbd895)
1 /*
2  * Copyright (C) 2015 Shaohua Li <shli@fb.com>
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms and conditions of the GNU General Public License,
6  * version 2, as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  * more details.
12  *
13  */
14 #include <linux/kernel.h>
15 #include <linux/wait.h>
16 #include <linux/blkdev.h>
17 #include <linux/slab.h>
18 #include <linux/raid/md_p.h>
19 #include <linux/crc32c.h>
20 #include <linux/random.h>
21 #include "md.h"
22 #include "raid5.h"
23 
24 /*
25  * metadata/data stored in disk with 4k size unit (a block) regardless
26  * underneath hardware sector size. only works with PAGE_SIZE == 4096
27  */
28 #define BLOCK_SECTORS (8)
29 
30 /*
31  * reclaim runs every 1/4 disk size or 10G reclaimable space. This can prevent
32  * recovery scans a very long log
33  */
34 #define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */
35 #define RECLAIM_MAX_FREE_SPACE_SHIFT (2)
36 
37 struct r5l_log {
38 	struct md_rdev *rdev;
39 
40 	u32 uuid_checksum;
41 
42 	sector_t device_size;		/* log device size, round to
43 					 * BLOCK_SECTORS */
44 	sector_t max_free_space;	/* reclaim run if free space is at
45 					 * this size */
46 
47 	sector_t last_checkpoint;	/* log tail. where recovery scan
48 					 * starts from */
49 	u64 last_cp_seq;		/* log tail sequence */
50 
51 	sector_t log_start;		/* log head. where new data appends */
52 	u64 seq;			/* log head sequence */
53 
54 	sector_t next_checkpoint;
55 	u64 next_cp_seq;
56 
57 	struct mutex io_mutex;
58 	struct r5l_io_unit *current_io;	/* current io_unit accepting new data */
59 
60 	spinlock_t io_list_lock;
61 	struct list_head running_ios;	/* io_units which are still running,
62 					 * and have not yet been completely
63 					 * written to the log */
64 	struct list_head io_end_ios;	/* io_units which have been completely
65 					 * written to the log but not yet written
66 					 * to the RAID */
67 	struct list_head flushing_ios;	/* io_units which are waiting for log
68 					 * cache flush */
69 	struct list_head finished_ios;	/* io_units which settle down in log disk */
70 	struct bio flush_bio;
71 
72 	struct kmem_cache *io_kc;
73 
74 	struct md_thread *reclaim_thread;
75 	unsigned long reclaim_target;	/* number of space that need to be
76 					 * reclaimed.  if it's 0, reclaim spaces
77 					 * used by io_units which are in
78 					 * IO_UNIT_STRIPE_END state (eg, reclaim
79 					 * dones't wait for specific io_unit
80 					 * switching to IO_UNIT_STRIPE_END
81 					 * state) */
82 	wait_queue_head_t iounit_wait;
83 
84 	struct list_head no_space_stripes; /* pending stripes, log has no space */
85 	spinlock_t no_space_stripes_lock;
86 
87 	bool need_cache_flush;
88 	bool in_teardown;
89 };
90 
91 /*
92  * an IO range starts from a meta data block and end at the next meta data
93  * block. The io unit's the meta data block tracks data/parity followed it. io
94  * unit is written to log disk with normal write, as we always flush log disk
95  * first and then start move data to raid disks, there is no requirement to
96  * write io unit with FLUSH/FUA
97  */
98 struct r5l_io_unit {
99 	struct r5l_log *log;
100 
101 	struct page *meta_page;	/* store meta block */
102 	int meta_offset;	/* current offset in meta_page */
103 
104 	struct bio *current_bio;/* current_bio accepting new data */
105 
106 	atomic_t pending_stripe;/* how many stripes not flushed to raid */
107 	u64 seq;		/* seq number of the metablock */
108 	sector_t log_start;	/* where the io_unit starts */
109 	sector_t log_end;	/* where the io_unit ends */
110 	struct list_head log_sibling; /* log->running_ios */
111 	struct list_head stripe_list; /* stripes added to the io_unit */
112 
113 	int state;
114 	bool need_split_bio;
115 };
116 
117 /* r5l_io_unit state */
118 enum r5l_io_unit_state {
119 	IO_UNIT_RUNNING = 0,	/* accepting new IO */
120 	IO_UNIT_IO_START = 1,	/* io_unit bio start writing to log,
121 				 * don't accepting new bio */
122 	IO_UNIT_IO_END = 2,	/* io_unit bio finish writing to log */
123 	IO_UNIT_STRIPE_END = 3,	/* stripes data finished writing to raid */
124 };
125 
126 static sector_t r5l_ring_add(struct r5l_log *log, sector_t start, sector_t inc)
127 {
128 	start += inc;
129 	if (start >= log->device_size)
130 		start = start - log->device_size;
131 	return start;
132 }
133 
134 static sector_t r5l_ring_distance(struct r5l_log *log, sector_t start,
135 				  sector_t end)
136 {
137 	if (end >= start)
138 		return end - start;
139 	else
140 		return end + log->device_size - start;
141 }
142 
143 static bool r5l_has_free_space(struct r5l_log *log, sector_t size)
144 {
145 	sector_t used_size;
146 
147 	used_size = r5l_ring_distance(log, log->last_checkpoint,
148 					log->log_start);
149 
150 	return log->device_size > used_size + size;
151 }
152 
153 static void r5l_free_io_unit(struct r5l_log *log, struct r5l_io_unit *io)
154 {
155 	__free_page(io->meta_page);
156 	kmem_cache_free(log->io_kc, io);
157 }
158 
159 static void r5l_move_io_unit_list(struct list_head *from, struct list_head *to,
160 				  enum r5l_io_unit_state state)
161 {
162 	struct r5l_io_unit *io;
163 
164 	while (!list_empty(from)) {
165 		io = list_first_entry(from, struct r5l_io_unit, log_sibling);
166 		/* don't change list order */
167 		if (io->state >= state)
168 			list_move_tail(&io->log_sibling, to);
169 		else
170 			break;
171 	}
172 }
173 
174 static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
175 				    enum r5l_io_unit_state state)
176 {
177 	if (WARN_ON(io->state >= state))
178 		return;
179 	io->state = state;
180 }
181 
182 static void r5l_io_run_stripes(struct r5l_io_unit *io)
183 {
184 	struct stripe_head *sh, *next;
185 
186 	list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
187 		list_del_init(&sh->log_list);
188 		set_bit(STRIPE_HANDLE, &sh->state);
189 		raid5_release_stripe(sh);
190 	}
191 }
192 
193 static void r5l_log_run_stripes(struct r5l_log *log)
194 {
195 	struct r5l_io_unit *io, *next;
196 
197 	assert_spin_locked(&log->io_list_lock);
198 
199 	list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
200 		/* don't change list order */
201 		if (io->state < IO_UNIT_IO_END)
202 			break;
203 
204 		list_move_tail(&io->log_sibling, &log->finished_ios);
205 		r5l_io_run_stripes(io);
206 	}
207 }
208 
209 static void r5l_log_endio(struct bio *bio)
210 {
211 	struct r5l_io_unit *io = bio->bi_private;
212 	struct r5l_log *log = io->log;
213 	unsigned long flags;
214 
215 	if (bio->bi_error)
216 		md_error(log->rdev->mddev, log->rdev);
217 
218 	bio_put(bio);
219 
220 	spin_lock_irqsave(&log->io_list_lock, flags);
221 	__r5l_set_io_unit_state(io, IO_UNIT_IO_END);
222 	if (log->need_cache_flush)
223 		r5l_move_io_unit_list(&log->running_ios, &log->io_end_ios,
224 				      IO_UNIT_IO_END);
225 	else
226 		r5l_log_run_stripes(log);
227 	spin_unlock_irqrestore(&log->io_list_lock, flags);
228 
229 	if (log->need_cache_flush)
230 		md_wakeup_thread(log->rdev->mddev->thread);
231 }
232 
233 static void r5l_submit_current_io(struct r5l_log *log)
234 {
235 	struct r5l_io_unit *io = log->current_io;
236 	struct r5l_meta_block *block;
237 	unsigned long flags;
238 	u32 crc;
239 
240 	if (!io)
241 		return;
242 
243 	block = page_address(io->meta_page);
244 	block->meta_size = cpu_to_le32(io->meta_offset);
245 	crc = crc32c_le(log->uuid_checksum, block, PAGE_SIZE);
246 	block->checksum = cpu_to_le32(crc);
247 
248 	log->current_io = NULL;
249 	spin_lock_irqsave(&log->io_list_lock, flags);
250 	__r5l_set_io_unit_state(io, IO_UNIT_IO_START);
251 	spin_unlock_irqrestore(&log->io_list_lock, flags);
252 
253 	submit_bio(WRITE, io->current_bio);
254 }
255 
256 static struct bio *r5l_bio_alloc(struct r5l_log *log)
257 {
258 	struct bio *bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL, BIO_MAX_PAGES);
259 
260 	bio->bi_rw = WRITE;
261 	bio->bi_bdev = log->rdev->bdev;
262 	bio->bi_iter.bi_sector = log->rdev->data_offset + log->log_start;
263 
264 	return bio;
265 }
266 
267 static void r5_reserve_log_entry(struct r5l_log *log, struct r5l_io_unit *io)
268 {
269 	log->log_start = r5l_ring_add(log, log->log_start, BLOCK_SECTORS);
270 
271 	/*
272 	 * If we filled up the log device start from the beginning again,
273 	 * which will require a new bio.
274 	 *
275 	 * Note: for this to work properly the log size needs to me a multiple
276 	 * of BLOCK_SECTORS.
277 	 */
278 	if (log->log_start == 0)
279 		io->need_split_bio = true;
280 
281 	io->log_end = log->log_start;
282 }
283 
284 static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
285 {
286 	struct r5l_io_unit *io;
287 	struct r5l_meta_block *block;
288 
289 	/* We can't handle memory allocate failure so far */
290 	io = kmem_cache_zalloc(log->io_kc, GFP_NOIO | __GFP_NOFAIL);
291 	io->log = log;
292 	INIT_LIST_HEAD(&io->log_sibling);
293 	INIT_LIST_HEAD(&io->stripe_list);
294 	io->state = IO_UNIT_RUNNING;
295 
296 	io->meta_page = alloc_page(GFP_NOIO | __GFP_NOFAIL | __GFP_ZERO);
297 	block = page_address(io->meta_page);
298 	block->magic = cpu_to_le32(R5LOG_MAGIC);
299 	block->version = R5LOG_VERSION;
300 	block->seq = cpu_to_le64(log->seq);
301 	block->position = cpu_to_le64(log->log_start);
302 
303 	io->log_start = log->log_start;
304 	io->meta_offset = sizeof(struct r5l_meta_block);
305 	io->seq = log->seq++;
306 
307 	io->current_bio = r5l_bio_alloc(log);
308 	io->current_bio->bi_end_io = r5l_log_endio;
309 	io->current_bio->bi_private = io;
310 	bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
311 
312 	r5_reserve_log_entry(log, io);
313 
314 	spin_lock_irq(&log->io_list_lock);
315 	list_add_tail(&io->log_sibling, &log->running_ios);
316 	spin_unlock_irq(&log->io_list_lock);
317 
318 	return io;
319 }
320 
321 static int r5l_get_meta(struct r5l_log *log, unsigned int payload_size)
322 {
323 	if (log->current_io &&
324 	    log->current_io->meta_offset + payload_size > PAGE_SIZE)
325 		r5l_submit_current_io(log);
326 
327 	if (!log->current_io)
328 		log->current_io = r5l_new_meta(log);
329 	return 0;
330 }
331 
332 static void r5l_append_payload_meta(struct r5l_log *log, u16 type,
333 				    sector_t location,
334 				    u32 checksum1, u32 checksum2,
335 				    bool checksum2_valid)
336 {
337 	struct r5l_io_unit *io = log->current_io;
338 	struct r5l_payload_data_parity *payload;
339 
340 	payload = page_address(io->meta_page) + io->meta_offset;
341 	payload->header.type = cpu_to_le16(type);
342 	payload->header.flags = cpu_to_le16(0);
343 	payload->size = cpu_to_le32((1 + !!checksum2_valid) <<
344 				    (PAGE_SHIFT - 9));
345 	payload->location = cpu_to_le64(location);
346 	payload->checksum[0] = cpu_to_le32(checksum1);
347 	if (checksum2_valid)
348 		payload->checksum[1] = cpu_to_le32(checksum2);
349 
350 	io->meta_offset += sizeof(struct r5l_payload_data_parity) +
351 		sizeof(__le32) * (1 + !!checksum2_valid);
352 }
353 
354 static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
355 {
356 	struct r5l_io_unit *io = log->current_io;
357 
358 	if (io->need_split_bio) {
359 		struct bio *prev = io->current_bio;
360 
361 		io->current_bio = r5l_bio_alloc(log);
362 		bio_chain(io->current_bio, prev);
363 
364 		submit_bio(WRITE, prev);
365 	}
366 
367 	if (!bio_add_page(io->current_bio, page, PAGE_SIZE, 0))
368 		BUG();
369 
370 	r5_reserve_log_entry(log, io);
371 }
372 
373 static void r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
374 			   int data_pages, int parity_pages)
375 {
376 	int i;
377 	int meta_size;
378 	struct r5l_io_unit *io;
379 
380 	meta_size =
381 		((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
382 		 * data_pages) +
383 		sizeof(struct r5l_payload_data_parity) +
384 		sizeof(__le32) * parity_pages;
385 
386 	r5l_get_meta(log, meta_size);
387 	io = log->current_io;
388 
389 	for (i = 0; i < sh->disks; i++) {
390 		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
391 			continue;
392 		if (i == sh->pd_idx || i == sh->qd_idx)
393 			continue;
394 		r5l_append_payload_meta(log, R5LOG_PAYLOAD_DATA,
395 					raid5_compute_blocknr(sh, i, 0),
396 					sh->dev[i].log_checksum, 0, false);
397 		r5l_append_payload_page(log, sh->dev[i].page);
398 	}
399 
400 	if (sh->qd_idx >= 0) {
401 		r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
402 					sh->sector, sh->dev[sh->pd_idx].log_checksum,
403 					sh->dev[sh->qd_idx].log_checksum, true);
404 		r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
405 		r5l_append_payload_page(log, sh->dev[sh->qd_idx].page);
406 	} else {
407 		r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
408 					sh->sector, sh->dev[sh->pd_idx].log_checksum,
409 					0, false);
410 		r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
411 	}
412 
413 	list_add_tail(&sh->log_list, &io->stripe_list);
414 	atomic_inc(&io->pending_stripe);
415 	sh->log_io = io;
416 }
417 
418 static void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
419 /*
420  * running in raid5d, where reclaim could wait for raid5d too (when it flushes
421  * data from log to raid disks), so we shouldn't wait for reclaim here
422  */
423 int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
424 {
425 	int write_disks = 0;
426 	int data_pages, parity_pages;
427 	int meta_size;
428 	int reserve;
429 	int i;
430 
431 	if (!log)
432 		return -EAGAIN;
433 	/* Don't support stripe batch */
434 	if (sh->log_io || !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
435 	    test_bit(STRIPE_SYNCING, &sh->state)) {
436 		/* the stripe is written to log, we start writing it to raid */
437 		clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
438 		return -EAGAIN;
439 	}
440 
441 	for (i = 0; i < sh->disks; i++) {
442 		void *addr;
443 
444 		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
445 			continue;
446 		write_disks++;
447 		/* checksum is already calculated in last run */
448 		if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
449 			continue;
450 		addr = kmap_atomic(sh->dev[i].page);
451 		sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
452 						    addr, PAGE_SIZE);
453 		kunmap_atomic(addr);
454 	}
455 	parity_pages = 1 + !!(sh->qd_idx >= 0);
456 	data_pages = write_disks - parity_pages;
457 
458 	meta_size =
459 		((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
460 		 * data_pages) +
461 		sizeof(struct r5l_payload_data_parity) +
462 		sizeof(__le32) * parity_pages;
463 	/* Doesn't work with very big raid array */
464 	if (meta_size + sizeof(struct r5l_meta_block) > PAGE_SIZE)
465 		return -EINVAL;
466 
467 	set_bit(STRIPE_LOG_TRAPPED, &sh->state);
468 	/*
469 	 * The stripe must enter state machine again to finish the write, so
470 	 * don't delay.
471 	 */
472 	clear_bit(STRIPE_DELAYED, &sh->state);
473 	atomic_inc(&sh->count);
474 
475 	mutex_lock(&log->io_mutex);
476 	/* meta + data */
477 	reserve = (1 + write_disks) << (PAGE_SHIFT - 9);
478 	if (r5l_has_free_space(log, reserve))
479 		r5l_log_stripe(log, sh, data_pages, parity_pages);
480 	else {
481 		spin_lock(&log->no_space_stripes_lock);
482 		list_add_tail(&sh->log_list, &log->no_space_stripes);
483 		spin_unlock(&log->no_space_stripes_lock);
484 
485 		r5l_wake_reclaim(log, reserve);
486 	}
487 	mutex_unlock(&log->io_mutex);
488 
489 	return 0;
490 }
491 
492 void r5l_write_stripe_run(struct r5l_log *log)
493 {
494 	if (!log)
495 		return;
496 	mutex_lock(&log->io_mutex);
497 	r5l_submit_current_io(log);
498 	mutex_unlock(&log->io_mutex);
499 }
500 
501 int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio)
502 {
503 	if (!log)
504 		return -ENODEV;
505 	/*
506 	 * we flush log disk cache first, then write stripe data to raid disks.
507 	 * So if bio is finished, the log disk cache is flushed already. The
508 	 * recovery guarantees we can recovery the bio from log disk, so we
509 	 * don't need to flush again
510 	 */
511 	if (bio->bi_iter.bi_size == 0) {
512 		bio_endio(bio);
513 		return 0;
514 	}
515 	bio->bi_rw &= ~REQ_FLUSH;
516 	return -EAGAIN;
517 }
518 
519 /* This will run after log space is reclaimed */
520 static void r5l_run_no_space_stripes(struct r5l_log *log)
521 {
522 	struct stripe_head *sh;
523 
524 	spin_lock(&log->no_space_stripes_lock);
525 	while (!list_empty(&log->no_space_stripes)) {
526 		sh = list_first_entry(&log->no_space_stripes,
527 				      struct stripe_head, log_list);
528 		list_del_init(&sh->log_list);
529 		set_bit(STRIPE_HANDLE, &sh->state);
530 		raid5_release_stripe(sh);
531 	}
532 	spin_unlock(&log->no_space_stripes_lock);
533 }
534 
535 static sector_t r5l_reclaimable_space(struct r5l_log *log)
536 {
537 	return r5l_ring_distance(log, log->last_checkpoint,
538 				 log->next_checkpoint);
539 }
540 
541 static bool r5l_complete_finished_ios(struct r5l_log *log)
542 {
543 	struct r5l_io_unit *io, *next;
544 	bool found = false;
545 
546 	assert_spin_locked(&log->io_list_lock);
547 
548 	list_for_each_entry_safe(io, next, &log->finished_ios, log_sibling) {
549 		/* don't change list order */
550 		if (io->state < IO_UNIT_STRIPE_END)
551 			break;
552 
553 		log->next_checkpoint = io->log_start;
554 		log->next_cp_seq = io->seq;
555 
556 		list_del(&io->log_sibling);
557 		r5l_free_io_unit(log, io);
558 
559 		found = true;
560 	}
561 
562 	return found;
563 }
564 
565 static void __r5l_stripe_write_finished(struct r5l_io_unit *io)
566 {
567 	struct r5l_log *log = io->log;
568 	unsigned long flags;
569 
570 	spin_lock_irqsave(&log->io_list_lock, flags);
571 	__r5l_set_io_unit_state(io, IO_UNIT_STRIPE_END);
572 
573 	if (!r5l_complete_finished_ios(log)) {
574 		spin_unlock_irqrestore(&log->io_list_lock, flags);
575 		return;
576 	}
577 
578 	if (r5l_reclaimable_space(log) > log->max_free_space)
579 		r5l_wake_reclaim(log, 0);
580 
581 	spin_unlock_irqrestore(&log->io_list_lock, flags);
582 	wake_up(&log->iounit_wait);
583 }
584 
585 void r5l_stripe_write_finished(struct stripe_head *sh)
586 {
587 	struct r5l_io_unit *io;
588 
589 	io = sh->log_io;
590 	sh->log_io = NULL;
591 
592 	if (io && atomic_dec_and_test(&io->pending_stripe))
593 		__r5l_stripe_write_finished(io);
594 }
595 
596 static void r5l_log_flush_endio(struct bio *bio)
597 {
598 	struct r5l_log *log = container_of(bio, struct r5l_log,
599 		flush_bio);
600 	unsigned long flags;
601 	struct r5l_io_unit *io;
602 
603 	if (bio->bi_error)
604 		md_error(log->rdev->mddev, log->rdev);
605 
606 	spin_lock_irqsave(&log->io_list_lock, flags);
607 	list_for_each_entry(io, &log->flushing_ios, log_sibling)
608 		r5l_io_run_stripes(io);
609 	list_splice_tail_init(&log->flushing_ios, &log->finished_ios);
610 	spin_unlock_irqrestore(&log->io_list_lock, flags);
611 }
612 
613 /*
614  * Starting dispatch IO to raid.
615  * io_unit(meta) consists of a log. There is one situation we want to avoid. A
616  * broken meta in the middle of a log causes recovery can't find meta at the
617  * head of log. If operations require meta at the head persistent in log, we
618  * must make sure meta before it persistent in log too. A case is:
619  *
620  * stripe data/parity is in log, we start write stripe to raid disks. stripe
621  * data/parity must be persistent in log before we do the write to raid disks.
622  *
623  * The solution is we restrictly maintain io_unit list order. In this case, we
624  * only write stripes of an io_unit to raid disks till the io_unit is the first
625  * one whose data/parity is in log.
626  */
627 void r5l_flush_stripe_to_raid(struct r5l_log *log)
628 {
629 	bool do_flush;
630 
631 	if (!log || !log->need_cache_flush)
632 		return;
633 
634 	spin_lock_irq(&log->io_list_lock);
635 	/* flush bio is running */
636 	if (!list_empty(&log->flushing_ios)) {
637 		spin_unlock_irq(&log->io_list_lock);
638 		return;
639 	}
640 	list_splice_tail_init(&log->io_end_ios, &log->flushing_ios);
641 	do_flush = !list_empty(&log->flushing_ios);
642 	spin_unlock_irq(&log->io_list_lock);
643 
644 	if (!do_flush)
645 		return;
646 	bio_reset(&log->flush_bio);
647 	log->flush_bio.bi_bdev = log->rdev->bdev;
648 	log->flush_bio.bi_end_io = r5l_log_flush_endio;
649 	submit_bio(WRITE_FLUSH, &log->flush_bio);
650 }
651 
652 static void r5l_write_super(struct r5l_log *log, sector_t cp);
653 static void r5l_write_super_and_discard_space(struct r5l_log *log,
654 	sector_t end)
655 {
656 	struct block_device *bdev = log->rdev->bdev;
657 	struct mddev *mddev;
658 
659 	r5l_write_super(log, end);
660 
661 	if (!blk_queue_discard(bdev_get_queue(bdev)))
662 		return;
663 
664 	mddev = log->rdev->mddev;
665 	/*
666 	 * This is to avoid a deadlock. r5l_quiesce holds reconfig_mutex and
667 	 * wait for this thread to finish. This thread waits for
668 	 * MD_CHANGE_PENDING clear, which is supposed to be done in
669 	 * md_check_recovery(). md_check_recovery() tries to get
670 	 * reconfig_mutex. Since r5l_quiesce already holds the mutex,
671 	 * md_check_recovery() fails, so the PENDING never get cleared. The
672 	 * in_teardown check workaround this issue.
673 	 */
674 	if (!log->in_teardown) {
675 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
676 		set_bit(MD_CHANGE_PENDING, &mddev->flags);
677 		md_wakeup_thread(mddev->thread);
678 		wait_event(mddev->sb_wait,
679 			!test_bit(MD_CHANGE_PENDING, &mddev->flags) ||
680 			log->in_teardown);
681 		/*
682 		 * r5l_quiesce could run after in_teardown check and hold
683 		 * mutex first. Superblock might get updated twice.
684 		 */
685 		if (log->in_teardown)
686 			md_update_sb(mddev, 1);
687 	} else {
688 		WARN_ON(!mddev_is_locked(mddev));
689 		md_update_sb(mddev, 1);
690 	}
691 
692 	/* discard IO error really doesn't matter, ignore it */
693 	if (log->last_checkpoint < end) {
694 		blkdev_issue_discard(bdev,
695 				log->last_checkpoint + log->rdev->data_offset,
696 				end - log->last_checkpoint, GFP_NOIO, 0);
697 	} else {
698 		blkdev_issue_discard(bdev,
699 				log->last_checkpoint + log->rdev->data_offset,
700 				log->device_size - log->last_checkpoint,
701 				GFP_NOIO, 0);
702 		blkdev_issue_discard(bdev, log->rdev->data_offset, end,
703 				GFP_NOIO, 0);
704 	}
705 }
706 
707 
708 static void r5l_do_reclaim(struct r5l_log *log)
709 {
710 	sector_t reclaim_target = xchg(&log->reclaim_target, 0);
711 	sector_t reclaimable;
712 	sector_t next_checkpoint;
713 	u64 next_cp_seq;
714 
715 	spin_lock_irq(&log->io_list_lock);
716 	/*
717 	 * move proper io_unit to reclaim list. We should not change the order.
718 	 * reclaimable/unreclaimable io_unit can be mixed in the list, we
719 	 * shouldn't reuse space of an unreclaimable io_unit
720 	 */
721 	while (1) {
722 		reclaimable = r5l_reclaimable_space(log);
723 		if (reclaimable >= reclaim_target ||
724 		    (list_empty(&log->running_ios) &&
725 		     list_empty(&log->io_end_ios) &&
726 		     list_empty(&log->flushing_ios) &&
727 		     list_empty(&log->finished_ios)))
728 			break;
729 
730 		md_wakeup_thread(log->rdev->mddev->thread);
731 		wait_event_lock_irq(log->iounit_wait,
732 				    r5l_reclaimable_space(log) > reclaimable,
733 				    log->io_list_lock);
734 	}
735 
736 	next_checkpoint = log->next_checkpoint;
737 	next_cp_seq = log->next_cp_seq;
738 	spin_unlock_irq(&log->io_list_lock);
739 
740 	BUG_ON(reclaimable < 0);
741 	if (reclaimable == 0)
742 		return;
743 
744 	/*
745 	 * write_super will flush cache of each raid disk. We must write super
746 	 * here, because the log area might be reused soon and we don't want to
747 	 * confuse recovery
748 	 */
749 	r5l_write_super_and_discard_space(log, next_checkpoint);
750 
751 	mutex_lock(&log->io_mutex);
752 	log->last_checkpoint = next_checkpoint;
753 	log->last_cp_seq = next_cp_seq;
754 	mutex_unlock(&log->io_mutex);
755 
756 	r5l_run_no_space_stripes(log);
757 }
758 
759 static void r5l_reclaim_thread(struct md_thread *thread)
760 {
761 	struct mddev *mddev = thread->mddev;
762 	struct r5conf *conf = mddev->private;
763 	struct r5l_log *log = conf->log;
764 
765 	if (!log)
766 		return;
767 	r5l_do_reclaim(log);
768 }
769 
770 static void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
771 {
772 	unsigned long target;
773 	unsigned long new = (unsigned long)space; /* overflow in theory */
774 
775 	do {
776 		target = log->reclaim_target;
777 		if (new < target)
778 			return;
779 	} while (cmpxchg(&log->reclaim_target, target, new) != target);
780 	md_wakeup_thread(log->reclaim_thread);
781 }
782 
783 void r5l_quiesce(struct r5l_log *log, int state)
784 {
785 	struct mddev *mddev;
786 	if (!log || state == 2)
787 		return;
788 	if (state == 0) {
789 		log->in_teardown = 0;
790 		log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
791 					log->rdev->mddev, "reclaim");
792 	} else if (state == 1) {
793 		/*
794 		 * at this point all stripes are finished, so io_unit is at
795 		 * least in STRIPE_END state
796 		 */
797 		log->in_teardown = 1;
798 		/* make sure r5l_write_super_and_discard_space exits */
799 		mddev = log->rdev->mddev;
800 		wake_up(&mddev->sb_wait);
801 		r5l_wake_reclaim(log, -1L);
802 		md_unregister_thread(&log->reclaim_thread);
803 		r5l_do_reclaim(log);
804 	}
805 }
806 
807 bool r5l_log_disk_error(struct r5conf *conf)
808 {
809 	/* don't allow write if journal disk is missing */
810 	if (!conf->log)
811 		return test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
812 	return test_bit(Faulty, &conf->log->rdev->flags);
813 }
814 
815 struct r5l_recovery_ctx {
816 	struct page *meta_page;		/* current meta */
817 	sector_t meta_total_blocks;	/* total size of current meta and data */
818 	sector_t pos;			/* recovery position */
819 	u64 seq;			/* recovery position seq */
820 };
821 
822 static int r5l_read_meta_block(struct r5l_log *log,
823 			       struct r5l_recovery_ctx *ctx)
824 {
825 	struct page *page = ctx->meta_page;
826 	struct r5l_meta_block *mb;
827 	u32 crc, stored_crc;
828 
829 	if (!sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page, READ, false))
830 		return -EIO;
831 
832 	mb = page_address(page);
833 	stored_crc = le32_to_cpu(mb->checksum);
834 	mb->checksum = 0;
835 
836 	if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
837 	    le64_to_cpu(mb->seq) != ctx->seq ||
838 	    mb->version != R5LOG_VERSION ||
839 	    le64_to_cpu(mb->position) != ctx->pos)
840 		return -EINVAL;
841 
842 	crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
843 	if (stored_crc != crc)
844 		return -EINVAL;
845 
846 	if (le32_to_cpu(mb->meta_size) > PAGE_SIZE)
847 		return -EINVAL;
848 
849 	ctx->meta_total_blocks = BLOCK_SECTORS;
850 
851 	return 0;
852 }
853 
854 static int r5l_recovery_flush_one_stripe(struct r5l_log *log,
855 					 struct r5l_recovery_ctx *ctx,
856 					 sector_t stripe_sect,
857 					 int *offset, sector_t *log_offset)
858 {
859 	struct r5conf *conf = log->rdev->mddev->private;
860 	struct stripe_head *sh;
861 	struct r5l_payload_data_parity *payload;
862 	int disk_index;
863 
864 	sh = raid5_get_active_stripe(conf, stripe_sect, 0, 0, 0);
865 	while (1) {
866 		payload = page_address(ctx->meta_page) + *offset;
867 
868 		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) {
869 			raid5_compute_sector(conf,
870 					     le64_to_cpu(payload->location), 0,
871 					     &disk_index, sh);
872 
873 			sync_page_io(log->rdev, *log_offset, PAGE_SIZE,
874 				     sh->dev[disk_index].page, READ, false);
875 			sh->dev[disk_index].log_checksum =
876 				le32_to_cpu(payload->checksum[0]);
877 			set_bit(R5_Wantwrite, &sh->dev[disk_index].flags);
878 			ctx->meta_total_blocks += BLOCK_SECTORS;
879 		} else {
880 			disk_index = sh->pd_idx;
881 			sync_page_io(log->rdev, *log_offset, PAGE_SIZE,
882 				     sh->dev[disk_index].page, READ, false);
883 			sh->dev[disk_index].log_checksum =
884 				le32_to_cpu(payload->checksum[0]);
885 			set_bit(R5_Wantwrite, &sh->dev[disk_index].flags);
886 
887 			if (sh->qd_idx >= 0) {
888 				disk_index = sh->qd_idx;
889 				sync_page_io(log->rdev,
890 					     r5l_ring_add(log, *log_offset, BLOCK_SECTORS),
891 					     PAGE_SIZE, sh->dev[disk_index].page,
892 					     READ, false);
893 				sh->dev[disk_index].log_checksum =
894 					le32_to_cpu(payload->checksum[1]);
895 				set_bit(R5_Wantwrite,
896 					&sh->dev[disk_index].flags);
897 			}
898 			ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded;
899 		}
900 
901 		*log_offset = r5l_ring_add(log, *log_offset,
902 					   le32_to_cpu(payload->size));
903 		*offset += sizeof(struct r5l_payload_data_parity) +
904 			sizeof(__le32) *
905 			(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
906 		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_PARITY)
907 			break;
908 	}
909 
910 	for (disk_index = 0; disk_index < sh->disks; disk_index++) {
911 		void *addr;
912 		u32 checksum;
913 
914 		if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
915 			continue;
916 		addr = kmap_atomic(sh->dev[disk_index].page);
917 		checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
918 		kunmap_atomic(addr);
919 		if (checksum != sh->dev[disk_index].log_checksum)
920 			goto error;
921 	}
922 
923 	for (disk_index = 0; disk_index < sh->disks; disk_index++) {
924 		struct md_rdev *rdev, *rrdev;
925 
926 		if (!test_and_clear_bit(R5_Wantwrite,
927 					&sh->dev[disk_index].flags))
928 			continue;
929 
930 		/* in case device is broken */
931 		rdev = rcu_dereference(conf->disks[disk_index].rdev);
932 		if (rdev)
933 			sync_page_io(rdev, stripe_sect, PAGE_SIZE,
934 				     sh->dev[disk_index].page, WRITE, false);
935 		rrdev = rcu_dereference(conf->disks[disk_index].replacement);
936 		if (rrdev)
937 			sync_page_io(rrdev, stripe_sect, PAGE_SIZE,
938 				     sh->dev[disk_index].page, WRITE, false);
939 	}
940 	raid5_release_stripe(sh);
941 	return 0;
942 
943 error:
944 	for (disk_index = 0; disk_index < sh->disks; disk_index++)
945 		sh->dev[disk_index].flags = 0;
946 	raid5_release_stripe(sh);
947 	return -EINVAL;
948 }
949 
950 static int r5l_recovery_flush_one_meta(struct r5l_log *log,
951 				       struct r5l_recovery_ctx *ctx)
952 {
953 	struct r5conf *conf = log->rdev->mddev->private;
954 	struct r5l_payload_data_parity *payload;
955 	struct r5l_meta_block *mb;
956 	int offset;
957 	sector_t log_offset;
958 	sector_t stripe_sector;
959 
960 	mb = page_address(ctx->meta_page);
961 	offset = sizeof(struct r5l_meta_block);
962 	log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
963 
964 	while (offset < le32_to_cpu(mb->meta_size)) {
965 		int dd;
966 
967 		payload = (void *)mb + offset;
968 		stripe_sector = raid5_compute_sector(conf,
969 						     le64_to_cpu(payload->location), 0, &dd, NULL);
970 		if (r5l_recovery_flush_one_stripe(log, ctx, stripe_sector,
971 						  &offset, &log_offset))
972 			return -EINVAL;
973 	}
974 	return 0;
975 }
976 
977 /* copy data/parity from log to raid disks */
978 static void r5l_recovery_flush_log(struct r5l_log *log,
979 				   struct r5l_recovery_ctx *ctx)
980 {
981 	while (1) {
982 		if (r5l_read_meta_block(log, ctx))
983 			return;
984 		if (r5l_recovery_flush_one_meta(log, ctx))
985 			return;
986 		ctx->seq++;
987 		ctx->pos = r5l_ring_add(log, ctx->pos, ctx->meta_total_blocks);
988 	}
989 }
990 
991 static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
992 					  u64 seq)
993 {
994 	struct page *page;
995 	struct r5l_meta_block *mb;
996 	u32 crc;
997 
998 	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
999 	if (!page)
1000 		return -ENOMEM;
1001 	mb = page_address(page);
1002 	mb->magic = cpu_to_le32(R5LOG_MAGIC);
1003 	mb->version = R5LOG_VERSION;
1004 	mb->meta_size = cpu_to_le32(sizeof(struct r5l_meta_block));
1005 	mb->seq = cpu_to_le64(seq);
1006 	mb->position = cpu_to_le64(pos);
1007 	crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
1008 	mb->checksum = cpu_to_le32(crc);
1009 
1010 	if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, WRITE_FUA, false)) {
1011 		__free_page(page);
1012 		return -EIO;
1013 	}
1014 	__free_page(page);
1015 	return 0;
1016 }
1017 
1018 static int r5l_recovery_log(struct r5l_log *log)
1019 {
1020 	struct r5l_recovery_ctx ctx;
1021 
1022 	ctx.pos = log->last_checkpoint;
1023 	ctx.seq = log->last_cp_seq;
1024 	ctx.meta_page = alloc_page(GFP_KERNEL);
1025 	if (!ctx.meta_page)
1026 		return -ENOMEM;
1027 
1028 	r5l_recovery_flush_log(log, &ctx);
1029 	__free_page(ctx.meta_page);
1030 
1031 	/*
1032 	 * we did a recovery. Now ctx.pos points to an invalid meta block. New
1033 	 * log will start here. but we can't let superblock point to last valid
1034 	 * meta block. The log might looks like:
1035 	 * | meta 1| meta 2| meta 3|
1036 	 * meta 1 is valid, meta 2 is invalid. meta 3 could be valid. If
1037 	 * superblock points to meta 1, we write a new valid meta 2n.  if crash
1038 	 * happens again, new recovery will start from meta 1. Since meta 2n is
1039 	 * valid now, recovery will think meta 3 is valid, which is wrong.
1040 	 * The solution is we create a new meta in meta2 with its seq == meta
1041 	 * 1's seq + 10 and let superblock points to meta2. The same recovery will
1042 	 * not think meta 3 is a valid meta, because its seq doesn't match
1043 	 */
1044 	if (ctx.seq > log->last_cp_seq + 1) {
1045 		int ret;
1046 
1047 		ret = r5l_log_write_empty_meta_block(log, ctx.pos, ctx.seq + 10);
1048 		if (ret)
1049 			return ret;
1050 		log->seq = ctx.seq + 11;
1051 		log->log_start = r5l_ring_add(log, ctx.pos, BLOCK_SECTORS);
1052 		r5l_write_super(log, ctx.pos);
1053 	} else {
1054 		log->log_start = ctx.pos;
1055 		log->seq = ctx.seq;
1056 	}
1057 	return 0;
1058 }
1059 
1060 static void r5l_write_super(struct r5l_log *log, sector_t cp)
1061 {
1062 	struct mddev *mddev = log->rdev->mddev;
1063 
1064 	log->rdev->journal_tail = cp;
1065 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
1066 }
1067 
1068 static int r5l_load_log(struct r5l_log *log)
1069 {
1070 	struct md_rdev *rdev = log->rdev;
1071 	struct page *page;
1072 	struct r5l_meta_block *mb;
1073 	sector_t cp = log->rdev->journal_tail;
1074 	u32 stored_crc, expected_crc;
1075 	bool create_super = false;
1076 	int ret;
1077 
1078 	/* Make sure it's valid */
1079 	if (cp >= rdev->sectors || round_down(cp, BLOCK_SECTORS) != cp)
1080 		cp = 0;
1081 	page = alloc_page(GFP_KERNEL);
1082 	if (!page)
1083 		return -ENOMEM;
1084 
1085 	if (!sync_page_io(rdev, cp, PAGE_SIZE, page, READ, false)) {
1086 		ret = -EIO;
1087 		goto ioerr;
1088 	}
1089 	mb = page_address(page);
1090 
1091 	if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
1092 	    mb->version != R5LOG_VERSION) {
1093 		create_super = true;
1094 		goto create;
1095 	}
1096 	stored_crc = le32_to_cpu(mb->checksum);
1097 	mb->checksum = 0;
1098 	expected_crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
1099 	if (stored_crc != expected_crc) {
1100 		create_super = true;
1101 		goto create;
1102 	}
1103 	if (le64_to_cpu(mb->position) != cp) {
1104 		create_super = true;
1105 		goto create;
1106 	}
1107 create:
1108 	if (create_super) {
1109 		log->last_cp_seq = prandom_u32();
1110 		cp = 0;
1111 		/*
1112 		 * Make sure super points to correct address. Log might have
1113 		 * data very soon. If super hasn't correct log tail address,
1114 		 * recovery can't find the log
1115 		 */
1116 		r5l_write_super(log, cp);
1117 	} else
1118 		log->last_cp_seq = le64_to_cpu(mb->seq);
1119 
1120 	log->device_size = round_down(rdev->sectors, BLOCK_SECTORS);
1121 	log->max_free_space = log->device_size >> RECLAIM_MAX_FREE_SPACE_SHIFT;
1122 	if (log->max_free_space > RECLAIM_MAX_FREE_SPACE)
1123 		log->max_free_space = RECLAIM_MAX_FREE_SPACE;
1124 	log->last_checkpoint = cp;
1125 
1126 	__free_page(page);
1127 
1128 	return r5l_recovery_log(log);
1129 ioerr:
1130 	__free_page(page);
1131 	return ret;
1132 }
1133 
1134 int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
1135 {
1136 	struct r5l_log *log;
1137 
1138 	if (PAGE_SIZE != 4096)
1139 		return -EINVAL;
1140 	log = kzalloc(sizeof(*log), GFP_KERNEL);
1141 	if (!log)
1142 		return -ENOMEM;
1143 	log->rdev = rdev;
1144 
1145 	log->need_cache_flush = (rdev->bdev->bd_disk->queue->flush_flags != 0);
1146 
1147 	log->uuid_checksum = crc32c_le(~0, rdev->mddev->uuid,
1148 				       sizeof(rdev->mddev->uuid));
1149 
1150 	mutex_init(&log->io_mutex);
1151 
1152 	spin_lock_init(&log->io_list_lock);
1153 	INIT_LIST_HEAD(&log->running_ios);
1154 	INIT_LIST_HEAD(&log->io_end_ios);
1155 	INIT_LIST_HEAD(&log->flushing_ios);
1156 	INIT_LIST_HEAD(&log->finished_ios);
1157 	bio_init(&log->flush_bio);
1158 
1159 	log->io_kc = KMEM_CACHE(r5l_io_unit, 0);
1160 	if (!log->io_kc)
1161 		goto io_kc;
1162 
1163 	log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
1164 						 log->rdev->mddev, "reclaim");
1165 	if (!log->reclaim_thread)
1166 		goto reclaim_thread;
1167 	init_waitqueue_head(&log->iounit_wait);
1168 
1169 	INIT_LIST_HEAD(&log->no_space_stripes);
1170 	spin_lock_init(&log->no_space_stripes_lock);
1171 
1172 	if (r5l_load_log(log))
1173 		goto error;
1174 
1175 	conf->log = log;
1176 	return 0;
1177 error:
1178 	md_unregister_thread(&log->reclaim_thread);
1179 reclaim_thread:
1180 	kmem_cache_destroy(log->io_kc);
1181 io_kc:
1182 	kfree(log);
1183 	return -EINVAL;
1184 }
1185 
1186 void r5l_exit_log(struct r5l_log *log)
1187 {
1188 	md_unregister_thread(&log->reclaim_thread);
1189 	kmem_cache_destroy(log->io_kc);
1190 	kfree(log);
1191 }
1192