summaryrefslogtreecommitdiffstats
path: root/drivers/lightnvm/pblk-write.c
blob: b9a2aeba95abd39e37709921a5376be4118aefef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2016 CNEX Labs
 * Initial release: Javier Gonzalez <javier@cnexlabs.com>
 *                  Matias Bjorling <matias@cnexlabs.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * pblk-write.c - pblk's write path from write buffer to media
 */

#include "pblk.h"
#include "pblk-trace.h"

static unsigned long pblk_end_w_bio(struct pblk *pblk, struct nvm_rq *rqd,
				    struct pblk_c_ctx *c_ctx)
{
	struct bio *original_bio;
	struct pblk_rb *rwb = &pblk->rwb;
	unsigned long ret;
	int i;

	for (i = 0; i < c_ctx->nr_valid; i++) {
		struct pblk_w_ctx *w_ctx;
		int pos = c_ctx->sentry + i;
		int flags;

		w_ctx = pblk_rb_w_ctx(rwb, pos);
		flags = READ_ONCE(w_ctx->flags);

		if (flags & PBLK_FLUSH_ENTRY) {
			flags &= ~PBLK_FLUSH_ENTRY;
			/* Release flags on context. Protect from writes */
			smp_store_release(&w_ctx->flags, flags);

#ifdef CONFIG_NVM_PBLK_DEBUG
			atomic_dec(&rwb->inflight_flush_point);
#endif
		}

		while ((original_bio = bio_list_pop(&w_ctx->bios)))
			bio_endio(original_bio);
	}

	if (c_ctx->nr_padded)
		pblk_bio_free_pages(pblk, rqd->bio, c_ctx->nr_valid,
							c_ctx->nr_padded);

#ifdef CONFIG_NVM_PBLK_DEBUG
	atomic_long_add(rqd->nr_ppas, &pblk->sync_writes);
#endif

	ret = pblk_rb_sync_advance(&pblk->rwb, c_ctx->nr_valid);

	bio_put(rqd->bio);
	pblk_free_rqd(pblk, rqd, PBLK_WRITE);

	return ret;
}

static unsigned long pblk_end_queued_w_bio(struct pblk *pblk,
					   struct nvm_rq *rqd,
					   struct pblk_c_ctx *c_ctx)
{
	list_del(&c_ctx->list);
	return pblk_end_w_bio(pblk, rqd, c_ctx);
}

static void pblk_complete_write(struct pblk *pblk, struct nvm_rq *rqd,
				struct pblk_c_ctx *c_ctx)
{
	struct pblk_c_ctx *c, *r;
	unsigned long flags;
	unsigned long pos;

#ifdef CONFIG_NVM_PBLK_DEBUG
	atomic_long_sub(c_ctx->nr_valid, &pblk->inflight_writes);
#endif
	pblk_up_rq(pblk, c_ctx->lun_bitmap);

	pos = pblk_rb_sync_init(&pblk->rwb, &flags);
	if (pos == c_ctx->sentry) {
		pos = pblk_end_w_bio(pblk, rqd, c_ctx);

retry:
		list_for_each_entry_safe(c, r, &pblk->compl_list, list) {
			rqd = nvm_rq_from_c_ctx(c);
			if (c->sentry == pos) {
				pos = pblk_end_queued_w_bio(pblk, rqd, c);
				goto retry;
			}
		}
	} else {
		WARN_ON(nvm_rq_from_c_ctx(c_ctx) != rqd);
		list_add_tail(&c_ctx->list, &pblk->compl_list);
	}
	pblk_rb_sync_end(&pblk->rwb, &flags);
}

/* Map remaining sectors in chunk, starting from ppa */
static void pblk_map_remaining(struct pblk *pblk, struct ppa_addr *ppa,
		int rqd_ppas)
{
	struct pblk_line *line;
	struct ppa_addr map_ppa = *ppa;
	__le64 addr_empty = cpu_to_le64(ADDR_EMPTY);
	__le64 *lba_list;
	u64 paddr;
	int done = 0;
	int n = 0;

	line = pblk_ppa_to_line(pblk, *ppa);
	lba_list = emeta_to_lbas(pblk, line->emeta->buf);

	spin_lock(&line->lock);

	while (!done)  {
		paddr = pblk_dev_ppa_to_line_addr(pblk, map_ppa);

		if (!test_and_set_bit(paddr, line->map_bitmap))
			line->left_msecs--;

		if (n < rqd_ppas && lba_list[paddr] != addr_empty)
			line->nr_valid_lbas--;

		lba_list[paddr] = addr_empty;

		if (!test_and_set_bit(paddr, line->invalid_bitmap))
			le32_add_cpu(line->vsc, -1);

		done = nvm_next_ppa_in_chk(pblk->dev, &map_ppa);

		n++;
	}

	line->w_err_gc->has_write_err = 1;
	spin_unlock(&line->lock);
}

static void pblk_prepare_resubmit(struct pblk *pblk, unsigned int sentry,
				  unsigned int nr_entries)
{
	struct pblk_rb *rb = &pblk->rwb;
	struct pblk_rb_entry *entry;
	struct pblk_line *line;
	struct pblk_w_ctx *w_ctx;
	struct ppa_addr ppa_l2p;
	int flags;
	unsigned int i;

	spin_lock(&pblk->trans_lock);
	for (i = 0; i < nr_entries; i++) {
		entry = &rb->entries[pblk_rb_ptr_wrap(rb, sentry, i)];
		w_ctx = &entry->w_ctx;

		/* Check if the lba has been overwritten */
		if (w_ctx->lba != ADDR_EMPTY) {
			ppa_l2p = pblk_trans_map_get(pblk, w_ctx->lba);
			if (!pblk_ppa_comp(ppa_l2p, entry->cacheline))
				w_ctx->lba = ADDR_EMPTY;
		}

		/* Mark up the entry as submittable again */
		flags = READ_ONCE(w_ctx->flags);
		flags |= PBLK_WRITTEN_DATA;
		/* Release flags on write context. Protect from writes */
		smp_store_release(&w_ctx->flags, flags);

		/* Decrease the reference count to the line as we will
		 * re-map these entries
		 */
		line = pblk_ppa_to_line(pblk, w_ctx->ppa);
		atomic_dec(&line->sec_to_update);
		kref_put(&line->ref, pblk_line_put);
	}
	spin_unlock(&pblk->trans_lock);
}

static void pblk_queue_resubmit(struct pblk *pblk, struct pblk_c_ctx *c_ctx)
{
	struct pblk_c_ctx *r_ctx;

	r_ctx = kzalloc(sizeof(struct pblk_c_ctx), GFP_KERNEL);
	if (!r_ctx)
		return;

	r_ctx->lun_bitmap = NULL;
	r_ctx->sentry = c_ctx->sentry;
	r_ctx->nr_valid = c_ctx->nr_valid;
	r_ctx->nr_padded = c_ctx->nr_padded;

	spin_lock(&pblk->resubmit_lock);
	list_add_tail(&r_ctx->list, &pblk->resubmit_list);
	spin_unlock(&pblk->resubmit_lock);

#ifdef CONFIG_NVM_PBLK_DEBUG
	atomic_long_add(c_ctx->nr_valid, &pblk->recov_writes);
#endif
}

static void pblk_submit_rec(struct work_struct *work)
{
	struct pblk_rec_ctx *recovery =
			container_of(work, struct pblk_rec_ctx, ws_rec);
	struct pblk *pblk = recovery->pblk;
	struct nvm_rq *rqd = recovery->rqd;
	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
	struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);

	pblk_log_write_err(pblk, rqd);

	pblk_map_remaining(pblk, ppa_list, rqd->nr_ppas);
	pblk_queue_resubmit(pblk, c_ctx);

	pblk_up_rq(pblk, c_ctx->lun_bitmap);
	if (c_ctx->nr_padded)
		pblk_bio_free_pages(pblk, rqd->bio, c_ctx->nr_valid,
							c_ctx->nr_padded);
	bio_put(rqd->bio);
	pblk_free_rqd(pblk, rqd, PBLK_WRITE);
	mempool_free(recovery, &pblk->rec_pool);

	atomic_dec(&pblk->inflight_io);
	pblk_write_kick(pblk);
}


static void pblk_end_w_fail(struct pblk *pblk, struct nvm_rq *rqd)
{
	struct pblk_rec_ctx *recovery;

	recovery = mempool_alloc(&pblk->rec_pool, GFP_ATOMIC);
	if (!recovery) {
		pblk_err(pblk, "could not allocate recovery work\n");
		return;
	}

	recovery->pblk = pblk;
	recovery->rqd = rqd;

	INIT_WORK(&recovery->ws_rec, pblk_submit_rec);
	queue_work(pblk->close_wq, &recovery->ws_rec);
}

static void pblk_end_io_write(struct nvm_rq *rqd)
{
	struct pblk *pblk = rqd->private;
	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);

	if (rqd->error) {
		pblk_end_w_fail(pblk, rqd);
		return;
	} else {
		if (trace_pblk_chunk_state_enabled())
			pblk_check_chunk_state_update(pblk, rqd);
#ifdef CONFIG_NVM_PBLK_DEBUG
		WARN_ONCE(rqd->bio->bi_status, "pblk: corrupted write error\n");
#endif
	}

	pblk_complete_write(pblk, rqd, c_ctx);
	atomic_dec(&pblk->inflight_io);
}

static void pblk_end_io_write_meta(struct nvm_rq *rqd)
{
	struct pblk *pblk = rqd->private;
	struct pblk_g_ctx *m_ctx = nvm_rq_to_pdu(rqd);
	struct pblk_line *line = m_ctx->private;
	struct pblk_emeta *emeta = line->emeta;
	struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
	int sync;

	pblk_up_chunk(pblk, ppa_list[0]);

	if (rqd->error) {
		pblk_log_write_err(pblk, rqd);
		pblk_err(pblk, "metadata I/O failed. Line %d\n", line->id);
		line->w_err_gc->has_write_err = 1;
	} else {
		if (trace_pblk_chunk_state_enabled())
			pblk_check_chunk_state_update(pblk, rqd);
	}

	sync = atomic_add_return(rqd->nr_ppas, &emeta->sync);
	if (sync == emeta->nr_entries)
		pblk_gen_run_ws(pblk, line, NULL, pblk_line_close_ws,
						GFP_ATOMIC, pblk->close_wq);

	pblk_free_rqd(pblk, rqd, PBLK_WRITE_INT);

	atomic_dec(&pblk->inflight_io);
}

static int pblk_alloc_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
			   unsigned int nr_secs, nvm_end_io_fn(*end_io))
{
	/* Setup write request */
	rqd->opcode = NVM_OP_PWRITE;
	rqd->nr_ppas = nr_secs;
	rqd->is_seq = 1;
	rqd->private = pblk;
	rqd->end_io = end_io;

	return pblk_alloc_rqd_meta(pblk, rqd);
}

static int pblk_setup_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
			   struct ppa_addr *erase_ppa)
{
	struct pblk_line_meta *lm = &pblk->lm;
	struct pblk_line *e_line = pblk_line_get_erase(pblk);
	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
	unsigned int valid = c_ctx->nr_valid;
	unsigned int padded = c_ctx->nr_padded;
	unsigned int nr_secs = valid + padded;
	unsigned long *lun_bitmap;
	int ret;

	lun_bitmap = kzalloc(lm->lun_bitmap_len, GFP_KERNEL);
	if (!lun_bitmap)
		return -ENOMEM;
	c_ctx->lun_bitmap = lun_bitmap;

	ret = pblk_alloc_w_rq(pblk, rqd, nr_secs, pblk_end_io_write);
	if (ret) {
		kfree(lun_bitmap);
		return ret;
	}

	if (likely(!e_line || !atomic_read(&e_line->left_eblks)))
		ret = pblk_map_rq(pblk, rqd, c_ctx->sentry, lun_bitmap,
							valid, 0);
	else
		ret = pblk_map_erase_rq(pblk, rqd, c_ctx->sentry, lun_bitmap,
							valid, erase_ppa);

	return ret;
}

static int pblk_calc_secs_to_sync(struct pblk *pblk, unsigned int secs_avail,
				  unsigned int secs_to_flush)
{
	int secs_to_sync;

	secs_to_sync = pblk_calc_secs(pblk, secs_avail, secs_to_flush, true);

#ifdef CONFIG_NVM_PBLK_DEBUG
	if ((!secs_to_sync && secs_to_flush)
			|| (secs_to_sync < 0)
			|| (secs_to_sync > secs_avail && !secs_to_flush)) {
		pblk_err(pblk, "bad sector calculation (a:%d,s:%d,f:%d)\n",
				secs_avail, secs_to_sync, secs_to_flush);
	}
#endif

	return secs_to_sync;
}

int pblk_submit_meta_io(struct pblk *pblk, struct pblk_line *meta_line)
{
	struct nvm_tgt_dev *dev = pblk->dev;
	struct nvm_geo *geo = &dev->geo;
	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
	struct pblk_line_meta *lm = &pblk->lm;
	struct pblk_emeta *emeta = meta_line->emeta;
	struct ppa_addr *ppa_list;
	struct pblk_g_ctx *m_ctx;
	struct nvm_rq *rqd;
	void *data;
	u64 paddr;
	int rq_ppas = pblk->min_write_pgs;
	int id = meta_line->id;
	int rq_len;
	int i, j;
	int ret;

	rqd = pblk_alloc_rqd(pblk, PBLK_WRITE_INT);

	m_ctx = nvm_rq_to_pdu(rqd);
	m_ctx->private = meta_line;

	rq_len = rq_ppas * geo->csecs;
	data = ((void *)emeta->buf) + emeta->mem;

	ret = pblk_alloc_w_rq(pblk, rqd, rq_ppas, pblk_end_io_write_meta);
	if (ret)
		goto fail_free_rqd;

	ppa_list = nvm_rq_to_ppa_list(rqd);
	for (i = 0; i < rqd->nr_ppas; ) {
		spin_lock(&meta_line->lock);
		paddr = __pblk_alloc_page(pblk, meta_line, rq_ppas);
		spin_unlock(&meta_line->lock);
		for (j = 0; j < rq_ppas; j++, i++, paddr++)
			ppa_list[i] = addr_to_gen_ppa(pblk, paddr, id);
	}

	spin_lock(&l_mg->close_lock);
	emeta->mem += rq_len;
	if (emeta->mem >= lm->emeta_len[0])
		list_del(&meta_line->list);
	spin_unlock(&l_mg->close_lock);

	pblk_down_chunk(pblk, ppa_list[0]);

	ret = pblk_submit_io(pblk, rqd, data);
	if (ret) {
		pblk_err(pblk, "emeta I/O submission failed: %d\n", ret);
		goto fail_rollback;
	}

	return NVM_IO_OK;

fail_rollback:
	pblk_up_chunk(pblk, ppa_list[0]);
	spin_lock(&l_mg->close_lock);
	pblk_dealloc_page(pblk, meta_line, rq_ppas);
	list_add(&meta_line->list, &meta_line->list);
	spin_unlock(&l_mg->close_lock);
fail_free_rqd:
	pblk_free_rqd(pblk, rqd, PBLK_WRITE_INT);
	return ret;
}

static inline bool pblk_valid_meta_ppa(struct pblk *pblk,
				       struct pblk_line *meta_line,
				       struct nvm_rq *data_rqd)
{
	struct nvm_tgt_dev *dev = pblk->dev;
	struct nvm_geo *geo = &dev->geo;
	struct pblk_c_ctx *data_c_ctx = nvm_rq_to_pdu(data_rqd);
	struct pblk_line *data_line = pblk_line_get_data(pblk);
	struct ppa_addr ppa, ppa_opt;
	u64 paddr;
	int pos_opt;

	/* Schedule a metadata I/O that is half the distance from the data I/O
	 * with regards to the number of LUNs forming the pblk instance. This
	 * balances LUN conflicts across every I/O.
	 *
	 * When the LUN configuration changes (e.g., due to GC), this distance
	 * can align, which would result on metadata and data I/Os colliding. In
	 * this case, modify the distance to not be optimal, but move the
	 * optimal in the right direction.
	 */
	paddr = pblk_lookup_page(pblk, meta_line);
	ppa = addr_to_gen_ppa(pblk, paddr, 0);
	ppa_opt = addr_to_gen_ppa(pblk, paddr + data_line->meta_distance, 0);
	pos_opt = pblk_ppa_to_pos(geo, ppa_opt);

	if (test_bit(pos_opt, data_c_ctx->lun_bitmap) ||
				test_bit(pos_opt, data_line->blk_bitmap))
		return true;

	if (unlikely(pblk_ppa_comp(ppa_opt, ppa)))
		data_line->meta_distance--;

	return false;
}

static struct pblk_line *pblk_should_submit_meta_io(struct pblk *pblk,
						    struct nvm_rq *data_rqd)
{
	struct pblk_line_meta *lm = &pblk->lm;
	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
	struct pblk_line *meta_line;

	spin_lock(&l_mg->close_lock);
	if (list_empty(&l_mg->emeta_list)) {
		spin_unlock(&l_mg->close_lock);
		return NULL;
	}
	meta_line = list_first_entry(&l_mg->emeta_list, struct pblk_line, list);
	if (meta_line->emeta->mem >= lm->emeta_len[0]) {
		spin_unlock(&l_mg->close_lock);
		return NULL;
	}
	spin_unlock(&l_mg->close_lock);

	if (!pblk_valid_meta_ppa(pblk, meta_line, data_rqd))
		return NULL;

	return meta_line;
}

static int pblk_submit_io_set(struct pblk *pblk, struct nvm_rq *rqd)
{
	struct ppa_addr erase_ppa;
	struct pblk_line *meta_line;
	int err;

	pblk_ppa_set_empty(&erase_ppa);

	/* Assign lbas to ppas and populate request structure */
	err = pblk_setup_w_rq(pblk, rqd, &erase_ppa);
	if (err) {
		pblk_err(pblk, "could not setup write request: %d\n", err);
		return NVM_IO_ERR;
	}

	meta_line = pblk_should_submit_meta_io(pblk, rqd);

	/* Submit data write for current data line */
	err = pblk_submit_io(pblk, rqd, NULL);
	if (err) {
		pblk_err(pblk, "data I/O submission failed: %d\n", err);
		return NVM_IO_ERR;
	}

	if (!pblk_ppa_empty(erase_ppa)) {
		/* Submit erase for next data line */
		if (pblk_blk_erase_async(pblk, erase_ppa)) {
			struct pblk_line *e_line = pblk_line_get_erase(pblk);
			struct nvm_tgt_dev *dev = pblk->dev;
			struct nvm_geo *geo = &dev->geo;
			int bit;

			atomic_inc(&e_line->left_eblks);
			bit = pblk_ppa_to_pos(geo, erase_ppa);
			WARN_ON(!test_and_clear_bit(bit, e_line->erase_bitmap));
		}
	}

	if (meta_line) {
		/* Submit metadata write for previous data line */
		err = pblk_submit_meta_io(pblk, meta_line);
		if (err) {
			pblk_err(pblk, "metadata I/O submission failed: %d",
					err);
			return NVM_IO_ERR;
		}
	}

	return NVM_IO_OK;
}

static void pblk_free_write_rqd(struct pblk *pblk, struct nvm_rq *rqd)
{
	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
	struct bio *bio = rqd->bio;

	if (c_ctx->nr_padded)
		pblk_bio_free_pages(pblk, bio, c_ctx->nr_valid,
							c_ctx->nr_padded);
}

static int pblk_submit_write(struct pblk *pblk, int *secs_left)
{
	struct bio *bio;
	struct nvm_rq *rqd;
	unsigned int secs_avail, secs_to_sync, secs_to_com;
	unsigned int secs_to_flush, packed_meta_pgs;
	unsigned long pos;
	unsigned int resubmit;

	*secs_left = 0;

	spin_lock(&pblk->resubmit_lock);
	resubmit = !list_empty(&pblk->resubmit_list);
	spin_unlock(&pblk->resubmit_lock);

	/* Resubmit failed writes first */
	if (resubmit) {
		struct pblk_c_ctx *r_ctx;

		spin_lock(&pblk->resubmit_lock);
		r_ctx = list_first_entry(&pblk->resubmit_list,
					struct pblk_c_ctx, list);
		list_del(&r_ctx->list);
		spin_unlock(&pblk->resubmit_lock);

		secs_avail = r_ctx->nr_valid;
		pos = r_ctx->sentry;

		pblk_prepare_resubmit(pblk, pos, secs_avail);
		secs_to_sync = pblk_calc_secs_to_sync(pblk, secs_avail,
				secs_avail);

		kfree(r_ctx);
	} else {
		/* If there are no sectors in the cache,
		 * flushes (bios without data) will be cleared on
		 * the cache threads
		 */
		secs_avail = pblk_rb_read_count(&pblk->rwb);
		if (!secs_avail)
			return 0;

		secs_to_flush = pblk_rb_flush_point_count(&pblk->rwb);
		if (!secs_to_flush && secs_avail < pblk->min_write_pgs_data)
			return 0;

		secs_to_sync = pblk_calc_secs_to_sync(pblk, secs_avail,
					secs_to_flush);
		if (secs_to_sync > pblk->max_write_pgs) {
			pblk_err(pblk, "bad buffer sync calculation\n");
			return 0;
		}

		secs_to_com = (secs_to_sync > secs_avail) ?
			secs_avail : secs_to_sync;
		pos = pblk_rb_read_commit(&pblk->rwb, secs_to_com);
	}

	packed_meta_pgs = (pblk->min_write_pgs - pblk->min_write_pgs_data);
	bio = bio_alloc(GFP_KERNEL, secs_to_sync + packed_meta_pgs);

	bio->bi_iter.bi_sector = 0; /* internal bio */
	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);

	rqd = pblk_alloc_rqd(pblk, PBLK_WRITE);
	rqd->bio = bio;

	if (pblk_rb_read_to_bio(&pblk->rwb, rqd, pos, secs_to_sync,
								secs_avail)) {
		pblk_err(pblk, "corrupted write bio\n");
		goto fail_put_bio;
	}

	if (pblk_submit_io_set(pblk, rqd))
		goto fail_free_bio;

#ifdef CONFIG_NVM_PBLK_DEBUG
	atomic_long_add(secs_to_sync, &pblk->sub_writes);
#endif

	*secs_left = 1;
	return 0;

fail_free_bio:
	pblk_free_write_rqd(pblk, rqd);
fail_put_bio:
	bio_put(bio);
	pblk_free_rqd(pblk, rqd, PBLK_WRITE);

	return -EINTR;
}

int pblk_write_ts(void *data)
{
	struct pblk *pblk = data;
	int secs_left;
	int write_failure = 0;

	while (!kthread_should_stop()) {
		if (!write_failure) {
			write_failure = pblk_submit_write(pblk, &secs_left);

			if (secs_left)
				continue;
		}
		set_current_state(TASK_INTERRUPTIBLE);
		io_schedule();
	}

	return 0;
}