linux - drivers/md/dm-writecache.c

2780 lines · 69.3 KiB

1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* Copyright (C) 2018 Red Hat. All rights reserved.
4	*
5	* This file is released under the GPL.
6	*/
7
8	#include <linux/device-mapper.h>
9	#include <linux/module.h>
10	#include <linux/init.h>
11	#include <linux/vmalloc.h>
12	#include <linux/kthread.h>
13	#include <linux/dm-io.h>
14	#include <linux/dm-kcopyd.h>
15	#include <linux/dax.h>
16	#include <linux/pfn_t.h>
17	#include <linux/libnvdimm.h>
18	#include <linux/delay.h>
19	#include "dm-io-tracker.h"
20
21	#define DM_MSG_PREFIX "writecache"
22
23	#define HIGH_WATERMARK 50
24	#define LOW_WATERMARK 45
25	#define MAX_WRITEBACK_JOBS min(0x10000000 / PAGE_SIZE, totalram_pages() / 16)
26	#define ENDIO_LATENCY 16
27	#define WRITEBACK_LATENCY 64
28	#define AUTOCOMMIT_BLOCKS_SSD 65536
29	#define AUTOCOMMIT_BLOCKS_PMEM 64
30	#define AUTOCOMMIT_MSEC 1000
31	#define MAX_AGE_DIV 16
32	#define MAX_AGE_UNSPECIFIED -1UL
33	#define PAUSE_WRITEBACK (HZ * 3)
34
35	#define BITMAP_GRANULARITY 65536
36	#if BITMAP_GRANULARITY < PAGE_SIZE
37	#undef BITMAP_GRANULARITY
38	#define BITMAP_GRANULARITY PAGE_SIZE
39	#endif
40
41	#if IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_FS_DAX)
42	#define DM_WRITECACHE_HAS_PMEM
43	#endif
44
45	#ifdef DM_WRITECACHE_HAS_PMEM
46	#define pmem_assign(dest, src) \
47	do { \
48	typeof(dest) uniq = (src); \
49	memcpy_flushcache(&(dest), &uniq, sizeof(dest)); \
50	} while (0)
51	#else
52	#define pmem_assign(dest, src) ((dest) = (src))
53	#endif
54
55	#if IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC) && defined(DM_WRITECACHE_HAS_PMEM)
56	#define DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
57	#endif
58
59	#define MEMORY_SUPERBLOCK_MAGIC 0x23489321
60	#define MEMORY_SUPERBLOCK_VERSION 1
61
62	struct wc_memory_entry {
63	__le64 original_sector;
64	__le64 seq_count;
65	};
66
67	struct wc_memory_superblock {
68	union {
69	struct {
70	__le32 magic;
71	__le32 version;
72	__le32 block_size;
73	__le32 pad;
74	__le64 n_blocks;
75	__le64 seq_count;
76	};
77	__le64 padding[8];
78	};
79	struct wc_memory_entry entries[];
80	};
81
82	struct wc_entry {
83	struct rb_node rb_node;
84	struct list_head lru;
85	unsigned short wc_list_contiguous;
86	#if BITS_PER_LONG == 64
87	bool write_in_progress : 1;
88	unsigned long index : 47;
89	#else
90	bool write_in_progress;
91	unsigned long index;
92	#endif
93	unsigned long age;
94	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
95	uint64_t original_sector;
96	uint64_t seq_count;
97	#endif
98	};
99
100	#ifdef DM_WRITECACHE_HAS_PMEM
101	#define WC_MODE_PMEM(wc) ((wc)->pmem_mode)
102	#define WC_MODE_FUA(wc) ((wc)->writeback_fua)
103	#else
104	#define WC_MODE_PMEM(wc) false
105	#define WC_MODE_FUA(wc) false
106	#endif
107	#define WC_MODE_SORT_FREELIST(wc) (!WC_MODE_PMEM(wc))
108
109	struct dm_writecache {
110	struct mutex lock;
111	struct list_head lru;
112	union {
113	struct list_head freelist;
114	struct {
115	struct rb_root freetree;
116	struct wc_entry *current_free;
117	};
118	};
119	struct rb_root tree;
120
121	size_t freelist_size;
122	size_t writeback_size;
123	size_t freelist_high_watermark;
124	size_t freelist_low_watermark;
125	unsigned long max_age;
126	unsigned long pause;
127
128	unsigned int uncommitted_blocks;
129	unsigned int autocommit_blocks;
130	unsigned int max_writeback_jobs;
131
132	int error;
133
134	unsigned long autocommit_jiffies;
135	struct timer_list autocommit_timer;
136	struct wait_queue_head freelist_wait;
137
138	struct timer_list max_age_timer;
139
140	atomic_t bio_in_progress[2];
141	struct wait_queue_head bio_in_progress_wait[2];
142
143	struct dm_target *ti;
144	struct dm_dev *dev;
145	struct dm_dev *ssd_dev;
146	sector_t start_sector;
147	void *memory_map;
148	uint64_t memory_map_size;
149	size_t metadata_sectors;
150	size_t n_blocks;
151	uint64_t seq_count;
152	sector_t data_device_sectors;
153	void *block_start;
154	struct wc_entry *entries;
155	unsigned int block_size;
156	unsigned char block_size_bits;
157
158	bool pmem_mode:1;
159	bool writeback_fua:1;
160
161	bool overwrote_committed:1;
162	bool memory_vmapped:1;
163
164	bool start_sector_set:1;
165	bool high_wm_percent_set:1;
166	bool low_wm_percent_set:1;
167	bool max_writeback_jobs_set:1;
168	bool autocommit_blocks_set:1;
169	bool autocommit_time_set:1;
170	bool max_age_set:1;
171	bool writeback_fua_set:1;
172	bool flush_on_suspend:1;
173	bool cleaner:1;
174	bool cleaner_set:1;
175	bool metadata_only:1;
176	bool pause_set:1;
177
178	unsigned int high_wm_percent_value;
179	unsigned int low_wm_percent_value;
180	unsigned int autocommit_time_value;
181	unsigned int max_age_value;
182	unsigned int pause_value;
183
184	unsigned int writeback_all;
185	struct workqueue_struct *writeback_wq;
186	struct work_struct writeback_work;
187	struct work_struct flush_work;
188
189	struct dm_io_tracker iot;
190
191	struct dm_io_client *dm_io;
192
193	raw_spinlock_t endio_list_lock;
194	struct list_head endio_list;
195	struct task_struct *endio_thread;
196
197	struct task_struct *flush_thread;
198	struct bio_list flush_list;
199
200	struct dm_kcopyd_client *dm_kcopyd;
201	unsigned long *dirty_bitmap;
202	unsigned int dirty_bitmap_size;
203
204	struct bio_set bio_set;
205	mempool_t copy_pool;
206
207	struct {
208	unsigned long long reads;
209	unsigned long long read_hits;
210	unsigned long long writes;
211	unsigned long long write_hits_uncommitted;
212	unsigned long long write_hits_committed;
213	unsigned long long writes_around;
214	unsigned long long writes_allocate;
215	unsigned long long writes_blocked_on_freelist;
216	unsigned long long flushes;
217	unsigned long long discards;
218	} stats;
219	};
220
221	#define WB_LIST_INLINE 16
222
223	struct writeback_struct {
224	struct list_head endio_entry;
225	struct dm_writecache *wc;
226	struct wc_entry **wc_list;
227	unsigned int wc_list_n;
228	struct wc_entry *wc_list_inline[WB_LIST_INLINE];
229	struct bio bio;
230	};
231
232	struct copy_struct {
233	struct list_head endio_entry;
234	struct dm_writecache *wc;
235	struct wc_entry *e;
236	unsigned int n_entries;
237	int error;
238	};
239
240	DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(dm_writecache_throttle,
241	"A percentage of time allocated for data copying");
242
243	static void wc_lock(struct dm_writecache *wc)
244	{
245	mutex_lock(&wc->lock);
246	}
247
248	static void wc_unlock(struct dm_writecache *wc)
249	{
250	mutex_unlock(&wc->lock);
251	}
252
253	#ifdef DM_WRITECACHE_HAS_PMEM
254	static int persistent_memory_claim(struct dm_writecache *wc)
255	{
256	int r;
257	loff_t s;
258	long p, da;
259	pfn_t pfn;
260	int id;
261	struct page **pages;
262	sector_t offset;
263
264	wc->memory_vmapped = false;
265
266	s = wc->memory_map_size;
267	p = s >> PAGE_SHIFT;
268	if (!p) {
269	r = -EINVAL;
270	goto err1;
271	}
272	if (p != s >> PAGE_SHIFT) {
273	r = -EOVERFLOW;
274	goto err1;
275	}
276
277	offset = get_start_sect(wc->ssd_dev->bdev);
278	if (offset & (PAGE_SIZE / 512 - 1)) {
279	r = -EINVAL;
280	goto err1;
281	}
282	offset >>= PAGE_SHIFT - 9;
283
284	id = dax_read_lock();
285
286	da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, DAX_ACCESS,
287	&wc->memory_map, &pfn);
288	if (da < 0) {
289	wc->memory_map = NULL;
290	r = da;
291	goto err2;
292	}
293	if (!pfn_t_has_page(pfn)) {
294	wc->memory_map = NULL;
295	r = -EOPNOTSUPP;
296	goto err2;
297	}
298	if (da != p) {
299	long i;
300
301	wc->memory_map = NULL;
302	pages = vmalloc_array(p, sizeof(struct page *));
303	if (!pages) {
304	r = -ENOMEM;
305	goto err2;
306	}
307	i = 0;
308	do {
309	long daa;
310
311	daa = dax_direct_access(wc->ssd_dev->dax_dev, offset + i,
312	p - i, DAX_ACCESS, NULL, &pfn);
313	if (daa <= 0) {
314	r = daa ? daa : -EINVAL;
315	goto err3;
316	}
317	if (!pfn_t_has_page(pfn)) {
318	r = -EOPNOTSUPP;
319	goto err3;
320	}
321	while (daa-- && i < p) {
322	pages[i++] = pfn_t_to_page(pfn);
323	pfn.val++;
324	if (!(i & 15))
325	cond_resched();
326	}
327	} while (i < p);
328	wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
329	if (!wc->memory_map) {
330	r = -ENOMEM;
331	goto err3;
332	}
333	vfree(pages);
334	wc->memory_vmapped = true;
335	}
336
337	dax_read_unlock(id);
338
339	wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT;
340	wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT;
341
342	return 0;
343	err3:
344	vfree(pages);
345	err2:
346	dax_read_unlock(id);
347	err1:
348	return r;
349	}
350	#else
351	static int persistent_memory_claim(struct dm_writecache *wc)
352	{
353	return -EOPNOTSUPP;
354	}
355	#endif
356
357	static void persistent_memory_release(struct dm_writecache *wc)
358	{
359	if (wc->memory_vmapped)
360	vunmap(wc->memory_map - ((size_t)wc->start_sector << SECTOR_SHIFT));
361	}
362
363	static struct page persistent_memory_page(void addr)
364	{
365	if (is_vmalloc_addr(addr))
366	return vmalloc_to_page(addr);
367	else
368	return virt_to_page(addr);
369	}
370
371	static unsigned int persistent_memory_page_offset(void *addr)
372	{
373	return (unsigned long)addr & (PAGE_SIZE - 1);
374	}
375
376	static void persistent_memory_flush_cache(void *ptr, size_t size)
377	{
378	if (is_vmalloc_addr(ptr))
379	flush_kernel_vmap_range(ptr, size);
380	}
381
382	static void persistent_memory_invalidate_cache(void *ptr, size_t size)
383	{
384	if (is_vmalloc_addr(ptr))
385	invalidate_kernel_vmap_range(ptr, size);
386	}
387
388	static struct wc_memory_superblock sb(struct dm_writecache wc)
389	{
390	return wc->memory_map;
391	}
392
393	static struct wc_memory_entry memory_entry(struct dm_writecache wc, struct wc_entry *e)
394	{
395	return &sb(wc)->entries[e->index];
396	}
397
398	static void memory_data(struct dm_writecache wc, struct wc_entry *e)
399	{
400	return (char *)wc->block_start + (e->index << wc->block_size_bits);
401	}
402
403	static sector_t cache_sector(struct dm_writecache wc, struct wc_entry e)
404	{
405	return wc->start_sector + wc->metadata_sectors +
406	((sector_t)e->index << (wc->block_size_bits - SECTOR_SHIFT));
407	}
408
409	static uint64_t read_original_sector(struct dm_writecache wc, struct wc_entry e)
410	{
411	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
412	return e->original_sector;
413	#else
414	return le64_to_cpu(memory_entry(wc, e)->original_sector);
415	#endif
416	}
417
418	static uint64_t read_seq_count(struct dm_writecache wc, struct wc_entry e)
419	{
420	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
421	return e->seq_count;
422	#else
423	return le64_to_cpu(memory_entry(wc, e)->seq_count);
424	#endif
425	}
426
427	static void clear_seq_count(struct dm_writecache wc, struct wc_entry e)
428	{
429	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
430	e->seq_count = -1;
431	#endif
432	pmem_assign(memory_entry(wc, e)->seq_count, cpu_to_le64(-1));
433	}
434
435	static void write_original_sector_seq_count(struct dm_writecache wc, struct wc_entry e,
436	uint64_t original_sector, uint64_t seq_count)
437	{
438	struct wc_memory_entry me;
439	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
440	e->original_sector = original_sector;
441	e->seq_count = seq_count;
442	#endif
443	me.original_sector = cpu_to_le64(original_sector);
444	me.seq_count = cpu_to_le64(seq_count);
445	pmem_assign(*memory_entry(wc, e), me);
446	}
447
448	#define writecache_error(wc, err, msg, arg...) \
449	do { \
450	if (!cmpxchg(&(wc)->error, 0, err)) \
451	DMERR(msg, ##arg); \
452	wake_up(&(wc)->freelist_wait); \
453	} while (0)
454
455	#define writecache_has_error(wc) (unlikely(READ_ONCE((wc)->error)))
456
457	static void writecache_flush_all_metadata(struct dm_writecache *wc)
458	{
459	if (!WC_MODE_PMEM(wc))
460	memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
461	}
462
463	static void writecache_flush_region(struct dm_writecache wc, void ptr, size_t size)
464	{
465	if (!WC_MODE_PMEM(wc))
466	__set_bit(((char )ptr - (char )wc->memory_map) / BITMAP_GRANULARITY,
467	wc->dirty_bitmap);
468	}
469
470	static void writecache_disk_flush(struct dm_writecache wc, struct dm_dev dev);
471
472	struct io_notify {
473	struct dm_writecache *wc;
474	struct completion c;
475	atomic_t count;
476	};
477
478	static void writecache_notify_io(unsigned long error, void *context)
479	{
480	struct io_notify *endio = context;
481
482	if (unlikely(error != 0))
483	writecache_error(endio->wc, -EIO, "error writing metadata");
484	BUG_ON(atomic_read(&endio->count) <= 0);
485	if (atomic_dec_and_test(&endio->count))
486	complete(&endio->c);
487	}
488
489	static void writecache_wait_for_ios(struct dm_writecache *wc, int direction)
490	{
491	wait_event(wc->bio_in_progress_wait[direction],
492	!atomic_read(&wc->bio_in_progress[direction]));
493	}
494
495	static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
496	{
497	struct dm_io_region region;
498	struct dm_io_request req;
499	struct io_notify endio = {
500	wc,
501	COMPLETION_INITIALIZER_ONSTACK(endio.c),
502	ATOMIC_INIT(1),
503	};
504	unsigned int bitmap_bits = wc->dirty_bitmap_size * 8;
505	unsigned int i = 0;
506
507	while (1) {
508	unsigned int j;
509
510	i = find_next_bit(wc->dirty_bitmap, bitmap_bits, i);
511	if (unlikely(i == bitmap_bits))
512	break;
513	j = find_next_zero_bit(wc->dirty_bitmap, bitmap_bits, i);
514
515	region.bdev = wc->ssd_dev->bdev;
516	region.sector = (sector_t)i * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
517	region.count = (sector_t)(j - i) * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
518
519	if (unlikely(region.sector >= wc->metadata_sectors))
520	break;
521	if (unlikely(region.sector + region.count > wc->metadata_sectors))
522	region.count = wc->metadata_sectors - region.sector;
523
524	region.sector += wc->start_sector;
525	atomic_inc(&endio.count);
526	req.bi_opf = REQ_OP_WRITE \| REQ_SYNC;
527	req.mem.type = DM_IO_VMA;
528	req.mem.ptr.vma = (char )wc->memory_map + (size_t)i BITMAP_GRANULARITY;
529	req.client = wc->dm_io;
530	req.notify.fn = writecache_notify_io;
531	req.notify.context = &endio;
532
533	/* writing via async dm-io (implied by notify.fn above) won't return an error */
534	(void) dm_io(&req, 1, &region, NULL, IOPRIO_DEFAULT);
535	i = j;
536	}
537
538	writecache_notify_io(0, &endio);
539	wait_for_completion_io(&endio.c);
540
541	if (wait_for_ios)
542	writecache_wait_for_ios(wc, WRITE);
543
544	writecache_disk_flush(wc, wc->ssd_dev);
545
546	memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size);
547	}
548
549	static void ssd_commit_superblock(struct dm_writecache *wc)
550	{
551	int r;
552	struct dm_io_region region;
553	struct dm_io_request req;
554
555	region.bdev = wc->ssd_dev->bdev;
556	region.sector = 0;
557	region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT;
558
559	if (unlikely(region.sector + region.count > wc->metadata_sectors))
560	region.count = wc->metadata_sectors - region.sector;
561
562	region.sector += wc->start_sector;
563
564	req.bi_opf = REQ_OP_WRITE \| REQ_SYNC \| REQ_FUA;
565	req.mem.type = DM_IO_VMA;
566	req.mem.ptr.vma = (char *)wc->memory_map;
567	req.client = wc->dm_io;
568	req.notify.fn = NULL;
569	req.notify.context = NULL;
570
571	r = dm_io(&req, 1, &region, NULL, IOPRIO_DEFAULT);
572	if (unlikely(r))
573	writecache_error(wc, r, "error writing superblock");
574	}
575
576	static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
577	{
578	if (WC_MODE_PMEM(wc))
579	pmem_wmb();
580	else
581	ssd_commit_flushed(wc, wait_for_ios);
582	}
583
584	static void writecache_disk_flush(struct dm_writecache wc, struct dm_dev dev)
585	{
586	int r;
587	struct dm_io_region region;
588	struct dm_io_request req;
589
590	region.bdev = dev->bdev;
591	region.sector = 0;
592	region.count = 0;
593	req.bi_opf = REQ_OP_WRITE \| REQ_PREFLUSH;
594	req.mem.type = DM_IO_KMEM;
595	req.mem.ptr.addr = NULL;
596	req.client = wc->dm_io;
597	req.notify.fn = NULL;
598
599	r = dm_io(&req, 1, &region, NULL, IOPRIO_DEFAULT);
600	if (unlikely(r))
601	writecache_error(wc, r, "error flushing metadata: %d", r);
602	}
603
604	#define WFE_RETURN_FOLLOWING 1
605	#define WFE_LOWEST_SEQ 2
606
607	static struct wc_entry writecache_find_entry(struct dm_writecache wc,
608	uint64_t block, int flags)
609	{
610	struct wc_entry *e;
611	struct rb_node *node = wc->tree.rb_node;
612
613	if (unlikely(!node))
614	return NULL;
615
616	while (1) {
617	e = container_of(node, struct wc_entry, rb_node);
618	if (read_original_sector(wc, e) == block)
619	break;
620
621	node = (read_original_sector(wc, e) >= block ?
622	e->rb_node.rb_left : e->rb_node.rb_right);
623	if (unlikely(!node)) {
624	if (!(flags & WFE_RETURN_FOLLOWING))
625	return NULL;
626	if (read_original_sector(wc, e) >= block)
627	return e;
628
629	node = rb_next(&e->rb_node);
630	if (unlikely(!node))
631	return NULL;
632
633	e = container_of(node, struct wc_entry, rb_node);
634	return e;
635	}
636	}
637
638	while (1) {
639	struct wc_entry *e2;
640
641	if (flags & WFE_LOWEST_SEQ)
642	node = rb_prev(&e->rb_node);
643	else
644	node = rb_next(&e->rb_node);
645	if (unlikely(!node))
646	return e;
647	e2 = container_of(node, struct wc_entry, rb_node);
648	if (read_original_sector(wc, e2) != block)
649	return e;
650	e = e2;
651	}
652	}
653
654	static void writecache_insert_entry(struct dm_writecache wc, struct wc_entry ins)
655	{
656	struct wc_entry *e;
657	struct rb_node *node = &wc->tree.rb_node, parent = NULL;
658
659	while (*node) {
660	e = container_of(*node, struct wc_entry, rb_node);
661	parent = &e->rb_node;
662	if (read_original_sector(wc, e) > read_original_sector(wc, ins))
663	node = &parent->rb_left;
664	else
665	node = &parent->rb_right;
666	}
667	rb_link_node(&ins->rb_node, parent, node);
668	rb_insert_color(&ins->rb_node, &wc->tree);
669	list_add(&ins->lru, &wc->lru);
670	ins->age = jiffies;
671	}
672
673	static void writecache_unlink(struct dm_writecache wc, struct wc_entry e)
674	{
675	list_del(&e->lru);
676	rb_erase(&e->rb_node, &wc->tree);
677	}
678
679	static void writecache_add_to_freelist(struct dm_writecache wc, struct wc_entry e)
680	{
681	if (WC_MODE_SORT_FREELIST(wc)) {
682	struct rb_node *node = &wc->freetree.rb_node, parent = NULL;
683
684	if (unlikely(!*node))
685	wc->current_free = e;
686	while (*node) {
687	parent = *node;
688	if (&e->rb_node < *node)
689	node = &parent->rb_left;
690	else
691	node = &parent->rb_right;
692	}
693	rb_link_node(&e->rb_node, parent, node);
694	rb_insert_color(&e->rb_node, &wc->freetree);
695	} else {
696	list_add_tail(&e->lru, &wc->freelist);
697	}
698	wc->freelist_size++;
699	}
700
701	static inline void writecache_verify_watermark(struct dm_writecache *wc)
702	{
703	if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
704	queue_work(wc->writeback_wq, &wc->writeback_work);
705	}
706
707	static void writecache_max_age_timer(struct timer_list *t)
708	{
709	struct dm_writecache *wc = from_timer(wc, t, max_age_timer);
710
711	if (!dm_suspended(wc->ti) && !writecache_has_error(wc)) {
712	queue_work(wc->writeback_wq, &wc->writeback_work);
713	mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
714	}
715	}
716
717	static struct wc_entry writecache_pop_from_freelist(struct dm_writecache wc, sector_t expected_sector)
718	{
719	struct wc_entry *e;
720
721	if (WC_MODE_SORT_FREELIST(wc)) {
722	struct rb_node *next;
723
724	if (unlikely(!wc->current_free))
725	return NULL;
726	e = wc->current_free;
727	if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
728	return NULL;
729	next = rb_next(&e->rb_node);
730	rb_erase(&e->rb_node, &wc->freetree);
731	if (unlikely(!next))
732	next = rb_first(&wc->freetree);
733	wc->current_free = next ? container_of(next, struct wc_entry, rb_node) : NULL;
734	} else {
735	if (unlikely(list_empty(&wc->freelist)))
736	return NULL;
737	e = container_of(wc->freelist.next, struct wc_entry, lru);
738	if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
739	return NULL;
740	list_del(&e->lru);
741	}
742	wc->freelist_size--;
743
744	writecache_verify_watermark(wc);
745
746	return e;
747	}
748
749	static void writecache_free_entry(struct dm_writecache wc, struct wc_entry e)
750	{
751	writecache_unlink(wc, e);
752	writecache_add_to_freelist(wc, e);
753	clear_seq_count(wc, e);
754	writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
755	if (unlikely(waitqueue_active(&wc->freelist_wait)))
756	wake_up(&wc->freelist_wait);
757	}
758
759	static void writecache_wait_on_freelist(struct dm_writecache *wc)
760	{
761	DEFINE_WAIT(wait);
762
763	prepare_to_wait(&wc->freelist_wait, &wait, TASK_UNINTERRUPTIBLE);
764	wc_unlock(wc);
765	io_schedule();
766	finish_wait(&wc->freelist_wait, &wait);
767	wc_lock(wc);
768	}
769
770	static void writecache_poison_lists(struct dm_writecache *wc)
771	{
772	/*
773	* Catch incorrect access to these values while the device is suspended.
774	*/
775	memset(&wc->tree, -1, sizeof(wc->tree));
776	wc->lru.next = LIST_POISON1;
777	wc->lru.prev = LIST_POISON2;
778	wc->freelist.next = LIST_POISON1;
779	wc->freelist.prev = LIST_POISON2;
780	}
781
782	static void writecache_flush_entry(struct dm_writecache wc, struct wc_entry e)
783	{
784	writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
785	if (WC_MODE_PMEM(wc))
786	writecache_flush_region(wc, memory_data(wc, e), wc->block_size);
787	}
788
789	static bool writecache_entry_is_committed(struct dm_writecache wc, struct wc_entry e)
790	{
791	return read_seq_count(wc, e) < wc->seq_count;
792	}
793
794	static void writecache_flush(struct dm_writecache *wc)
795	{
796	struct wc_entry e, e2;
797	bool need_flush_after_free;
798
799	wc->uncommitted_blocks = 0;
800	del_timer(&wc->autocommit_timer);
801
802	if (list_empty(&wc->lru))
803	return;
804
805	e = container_of(wc->lru.next, struct wc_entry, lru);
806	if (writecache_entry_is_committed(wc, e)) {
807	if (wc->overwrote_committed) {
808	writecache_wait_for_ios(wc, WRITE);
809	writecache_disk_flush(wc, wc->ssd_dev);
810	wc->overwrote_committed = false;
811	}
812	return;
813	}
814	while (1) {
815	writecache_flush_entry(wc, e);
816	if (unlikely(e->lru.next == &wc->lru))
817	break;
818	e2 = container_of(e->lru.next, struct wc_entry, lru);
819	if (writecache_entry_is_committed(wc, e2))
820	break;
821	e = e2;
822	cond_resched();
823	}
824	writecache_commit_flushed(wc, true);
825
826	wc->seq_count++;
827	pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
828	if (WC_MODE_PMEM(wc))
829	writecache_commit_flushed(wc, false);
830	else
831	ssd_commit_superblock(wc);
832
833	wc->overwrote_committed = false;
834
835	need_flush_after_free = false;
836	while (1) {
837	/* Free another committed entry with lower seq-count */
838	struct rb_node *rb_node = rb_prev(&e->rb_node);
839
840	if (rb_node) {
841	e2 = container_of(rb_node, struct wc_entry, rb_node);
842	if (read_original_sector(wc, e2) == read_original_sector(wc, e) &&
843	likely(!e2->write_in_progress)) {
844	writecache_free_entry(wc, e2);
845	need_flush_after_free = true;
846	}
847	}
848	if (unlikely(e->lru.prev == &wc->lru))
849	break;
850	e = container_of(e->lru.prev, struct wc_entry, lru);
851	cond_resched();
852	}
853
854	if (need_flush_after_free)
855	writecache_commit_flushed(wc, false);
856	}
857
858	static void writecache_flush_work(struct work_struct *work)
859	{
860	struct dm_writecache *wc = container_of(work, struct dm_writecache, flush_work);
861
862	wc_lock(wc);
863	writecache_flush(wc);
864	wc_unlock(wc);
865	}
866
867	static void writecache_autocommit_timer(struct timer_list *t)
868	{
869	struct dm_writecache *wc = from_timer(wc, t, autocommit_timer);
870
871	if (!writecache_has_error(wc))
872	queue_work(wc->writeback_wq, &wc->flush_work);
873	}
874
875	static void writecache_schedule_autocommit(struct dm_writecache *wc)
876	{
877	if (!timer_pending(&wc->autocommit_timer))
878	mod_timer(&wc->autocommit_timer, jiffies + wc->autocommit_jiffies);
879	}
880
881	static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_t end)
882	{
883	struct wc_entry *e;
884	bool discarded_something = false;
885
886	e = writecache_find_entry(wc, start, WFE_RETURN_FOLLOWING \| WFE_LOWEST_SEQ);
887	if (unlikely(!e))
888	return;
889
890	while (read_original_sector(wc, e) < end) {
891	struct rb_node *node = rb_next(&e->rb_node);
892
893	if (likely(!e->write_in_progress)) {
894	if (!discarded_something) {
895	if (!WC_MODE_PMEM(wc)) {
896	writecache_wait_for_ios(wc, READ);
897	writecache_wait_for_ios(wc, WRITE);
898	}
899	discarded_something = true;
900	}
901	if (!writecache_entry_is_committed(wc, e))
902	wc->uncommitted_blocks--;
903	writecache_free_entry(wc, e);
904	}
905
906	if (unlikely(!node))
907	break;
908
909	e = container_of(node, struct wc_entry, rb_node);
910	}
911
912	if (discarded_something)
913	writecache_commit_flushed(wc, false);
914	}
915
916	static bool writecache_wait_for_writeback(struct dm_writecache *wc)
917	{
918	if (wc->writeback_size) {
919	writecache_wait_on_freelist(wc);
920	return true;
921	}
922	return false;
923	}
924
925	static void writecache_suspend(struct dm_target *ti)
926	{
927	struct dm_writecache *wc = ti->private;
928	bool flush_on_suspend;
929
930	del_timer_sync(&wc->autocommit_timer);
931	del_timer_sync(&wc->max_age_timer);
932
933	wc_lock(wc);
934	writecache_flush(wc);
935	flush_on_suspend = wc->flush_on_suspend;
936	if (flush_on_suspend) {
937	wc->flush_on_suspend = false;
938	wc->writeback_all++;
939	queue_work(wc->writeback_wq, &wc->writeback_work);
940	}
941	wc_unlock(wc);
942
943	drain_workqueue(wc->writeback_wq);
944
945	wc_lock(wc);
946	if (flush_on_suspend)
947	wc->writeback_all--;
948	while (writecache_wait_for_writeback(wc))
949	;
950
951	if (WC_MODE_PMEM(wc))
952	persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
953
954	writecache_poison_lists(wc);
955
956	wc_unlock(wc);
957	}
958
959	static int writecache_alloc_entries(struct dm_writecache *wc)
960	{
961	size_t b;
962
963	if (wc->entries)
964	return 0;
965	wc->entries = vmalloc_array(wc->n_blocks, sizeof(struct wc_entry));
966	if (!wc->entries)
967	return -ENOMEM;
968	for (b = 0; b < wc->n_blocks; b++) {
969	struct wc_entry *e = &wc->entries[b];
970
971	e->index = b;
972	e->write_in_progress = false;
973	cond_resched();
974	}
975
976	return 0;
977	}
978
979	static int writecache_read_metadata(struct dm_writecache *wc, sector_t n_sectors)
980	{
981	struct dm_io_region region;
982	struct dm_io_request req;
983
984	region.bdev = wc->ssd_dev->bdev;
985	region.sector = wc->start_sector;
986	region.count = n_sectors;
987	req.bi_opf = REQ_OP_READ \| REQ_SYNC;
988	req.mem.type = DM_IO_VMA;
989	req.mem.ptr.vma = (char *)wc->memory_map;
990	req.client = wc->dm_io;
991	req.notify.fn = NULL;
992
993	return dm_io(&req, 1, &region, NULL, IOPRIO_DEFAULT);
994	}
995
996	static void writecache_resume(struct dm_target *ti)
997	{
998	struct dm_writecache *wc = ti->private;
999	size_t b;
1000	bool need_flush = false;
1001	__le64 sb_seq_count;
1002	int r;
1003
1004	wc_lock(wc);
1005
1006	wc->data_device_sectors = bdev_nr_sectors(wc->dev->bdev);
1007
1008	if (WC_MODE_PMEM(wc)) {
1009	persistent_memory_invalidate_cache(wc->memory_map, wc->memory_map_size);
1010	} else {
1011	r = writecache_read_metadata(wc, wc->metadata_sectors);
1012	if (r) {
1013	size_t sb_entries_offset;
1014
1015	writecache_error(wc, r, "unable to read metadata: %d", r);
1016	sb_entries_offset = offsetof(struct wc_memory_superblock, entries);
1017	memset((char *)wc->memory_map + sb_entries_offset, -1,
1018	(wc->metadata_sectors << SECTOR_SHIFT) - sb_entries_offset);
1019	}
1020	}
1021
1022	wc->tree = RB_ROOT;
1023	INIT_LIST_HEAD(&wc->lru);
1024	if (WC_MODE_SORT_FREELIST(wc)) {
1025	wc->freetree = RB_ROOT;
1026	wc->current_free = NULL;
1027	} else {
1028	INIT_LIST_HEAD(&wc->freelist);
1029	}
1030	wc->freelist_size = 0;
1031
1032	r = copy_mc_to_kernel(&sb_seq_count, &sb(wc)->seq_count,
1033	sizeof(uint64_t));
1034	if (r) {
1035	writecache_error(wc, r, "hardware memory error when reading superblock: %d", r);
1036	sb_seq_count = cpu_to_le64(0);
1037	}
1038	wc->seq_count = le64_to_cpu(sb_seq_count);
1039
1040	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
1041	for (b = 0; b < wc->n_blocks; b++) {
1042	struct wc_entry *e = &wc->entries[b];
1043	struct wc_memory_entry wme;
1044
1045	if (writecache_has_error(wc)) {
1046	e->original_sector = -1;
1047	e->seq_count = -1;
1048	continue;
1049	}
1050	r = copy_mc_to_kernel(&wme, memory_entry(wc, e),
1051	sizeof(struct wc_memory_entry));
1052	if (r) {
1053	writecache_error(wc, r, "hardware memory error when reading metadata entry %lu: %d",
1054	(unsigned long)b, r);
1055	e->original_sector = -1;
1056	e->seq_count = -1;
1057	} else {
1058	e->original_sector = le64_to_cpu(wme.original_sector);
1059	e->seq_count = le64_to_cpu(wme.seq_count);
1060	}
1061	cond_resched();
1062	}
1063	#endif
1064	for (b = 0; b < wc->n_blocks; b++) {
1065	struct wc_entry *e = &wc->entries[b];
1066
1067	if (!writecache_entry_is_committed(wc, e)) {
1068	if (read_seq_count(wc, e) != -1) {
1069	erase_this:
1070	clear_seq_count(wc, e);
1071	need_flush = true;
1072	}
1073	writecache_add_to_freelist(wc, e);
1074	} else {
1075	struct wc_entry *old;
1076
1077	old = writecache_find_entry(wc, read_original_sector(wc, e), 0);
1078	if (!old) {
1079	writecache_insert_entry(wc, e);
1080	} else {
1081	if (read_seq_count(wc, old) == read_seq_count(wc, e)) {
1082	writecache_error(wc, -EINVAL,
1083	"two identical entries, position %llu, sector %llu, sequence %llu",
1084	(unsigned long long)b, (unsigned long long)read_original_sector(wc, e),
1085	(unsigned long long)read_seq_count(wc, e));
1086	}
1087	if (read_seq_count(wc, old) > read_seq_count(wc, e)) {
1088	goto erase_this;
1089	} else {
1090	writecache_free_entry(wc, old);
1091	writecache_insert_entry(wc, e);
1092	need_flush = true;
1093	}
1094	}
1095	}
1096	cond_resched();
1097	}
1098
1099	if (need_flush) {
1100	writecache_flush_all_metadata(wc);
1101	writecache_commit_flushed(wc, false);
1102	}
1103
1104	writecache_verify_watermark(wc);
1105
1106	if (wc->max_age != MAX_AGE_UNSPECIFIED)
1107	mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
1108
1109	wc_unlock(wc);
1110	}
1111
1112	static int process_flush_mesg(unsigned int argc, char *argv, struct dm_writecache wc)
1113	{
1114	if (argc != 1)
1115	return -EINVAL;
1116
1117	wc_lock(wc);
1118	if (dm_suspended(wc->ti)) {
1119	wc_unlock(wc);
1120	return -EBUSY;
1121	}
1122	if (writecache_has_error(wc)) {
1123	wc_unlock(wc);
1124	return -EIO;
1125	}
1126
1127	writecache_flush(wc);
1128	wc->writeback_all++;
1129	queue_work(wc->writeback_wq, &wc->writeback_work);
1130	wc_unlock(wc);
1131
1132	flush_workqueue(wc->writeback_wq);
1133
1134	wc_lock(wc);
1135	wc->writeback_all--;
1136	if (writecache_has_error(wc)) {
1137	wc_unlock(wc);
1138	return -EIO;
1139	}
1140	wc_unlock(wc);
1141
1142	return 0;
1143	}
1144
1145	static int process_flush_on_suspend_mesg(unsigned int argc, char *argv, struct dm_writecache wc)
1146	{
1147	if (argc != 1)
1148	return -EINVAL;
1149
1150	wc_lock(wc);
1151	wc->flush_on_suspend = true;
1152	wc_unlock(wc);
1153
1154	return 0;
1155	}
1156
1157	static void activate_cleaner(struct dm_writecache *wc)
1158	{
1159	wc->flush_on_suspend = true;
1160	wc->cleaner = true;
1161	wc->freelist_high_watermark = wc->n_blocks;
1162	wc->freelist_low_watermark = wc->n_blocks;
1163	}
1164
1165	static int process_cleaner_mesg(unsigned int argc, char *argv, struct dm_writecache wc)
1166	{
1167	if (argc != 1)
1168	return -EINVAL;
1169
1170	wc_lock(wc);
1171	activate_cleaner(wc);
1172	if (!dm_suspended(wc->ti))
1173	writecache_verify_watermark(wc);
1174	wc_unlock(wc);
1175
1176	return 0;
1177	}
1178
1179	static int process_clear_stats_mesg(unsigned int argc, char *argv, struct dm_writecache wc)
1180	{
1181	if (argc != 1)
1182	return -EINVAL;
1183
1184	wc_lock(wc);
1185	memset(&wc->stats, 0, sizeof(wc->stats));
1186	wc_unlock(wc);
1187
1188	return 0;
1189	}
1190
1191	static int writecache_message(struct dm_target ti, unsigned int argc, char *argv,
1192	char *result, unsigned int maxlen)
1193	{
1194	int r = -EINVAL;
1195	struct dm_writecache *wc = ti->private;
1196
1197	if (!strcasecmp(argv[0], "flush"))
1198	r = process_flush_mesg(argc, argv, wc);
1199	else if (!strcasecmp(argv[0], "flush_on_suspend"))
1200	r = process_flush_on_suspend_mesg(argc, argv, wc);
1201	else if (!strcasecmp(argv[0], "cleaner"))
1202	r = process_cleaner_mesg(argc, argv, wc);
1203	else if (!strcasecmp(argv[0], "clear_stats"))
1204	r = process_clear_stats_mesg(argc, argv, wc);
1205	else
1206	DMERR("unrecognised message received: %s", argv[0]);
1207
1208	return r;
1209	}
1210
1211	static void memcpy_flushcache_optimized(void dest, void source, size_t size)
1212	{
1213	/*
1214	* clflushopt performs better with block size 1024, 2048, 4096
1215	* non-temporal stores perform better with block size 512
1216	*
1217	* block size 512 1024 2048 4096
1218	* movnti 496 MB/s 642 MB/s 725 MB/s 744 MB/s
1219	* clflushopt 373 MB/s 688 MB/s 1.1 GB/s 1.2 GB/s
1220	*
1221	* We see that movnti performs better for 512-byte blocks, and
1222	* clflushopt performs better for 1024-byte and larger blocks. So, we
1223	* prefer clflushopt for sizes >= 768.
1224	*
1225	* NOTE: this happens to be the case now (with dm-writecache's single
1226	* threaded model) but re-evaluate this once memcpy_flushcache() is
1227	* enabled to use movdir64b which might invalidate this performance
1228	* advantage seen with cache-allocating-writes plus flushing.
1229	*/
1230	#ifdef CONFIG_X86
1231	if (static_cpu_has(X86_FEATURE_CLFLUSHOPT) &&
1232	likely(boot_cpu_data.x86_clflush_size == 64) &&
1233	likely(size >= 768)) {
1234	do {
1235	memcpy((void )dest, (void )source, 64);
1236	clflushopt((void *)dest);
1237	dest += 64;
1238	source += 64;
1239	size -= 64;
1240	} while (size >= 64);
1241	return;
1242	}
1243	#endif
1244	memcpy_flushcache(dest, source, size);
1245	}
1246
1247	static void bio_copy_block(struct dm_writecache wc, struct bio bio, void *data)
1248	{
1249	void *buf;
1250	unsigned int size;
1251	int rw = bio_data_dir(bio);
1252	unsigned int remaining_size = wc->block_size;
1253
1254	do {
1255	struct bio_vec bv = bio_iter_iovec(bio, bio->bi_iter);
1256
1257	buf = bvec_kmap_local(&bv);
1258	size = bv.bv_len;
1259	if (unlikely(size > remaining_size))
1260	size = remaining_size;
1261
1262	if (rw == READ) {
1263	int r;
1264
1265	r = copy_mc_to_kernel(buf, data, size);
1266	flush_dcache_page(bio_page(bio));
1267	if (unlikely(r)) {
1268	writecache_error(wc, r, "hardware memory error when reading data: %d", r);
1269	bio->bi_status = BLK_STS_IOERR;
1270	}
1271	} else {
1272	flush_dcache_page(bio_page(bio));
1273	memcpy_flushcache_optimized(data, buf, size);
1274	}
1275
1276	kunmap_local(buf);
1277
1278	data = (char *)data + size;
1279	remaining_size -= size;
1280	bio_advance(bio, size);
1281	} while (unlikely(remaining_size));
1282	}
1283
1284	static int writecache_flush_thread(void *data)
1285	{
1286	struct dm_writecache *wc = data;
1287
1288	while (1) {
1289	struct bio *bio;
1290
1291	wc_lock(wc);
1292	bio = bio_list_pop(&wc->flush_list);
1293	if (!bio) {
1294	set_current_state(TASK_INTERRUPTIBLE);
1295	wc_unlock(wc);
1296
1297	if (unlikely(kthread_should_stop())) {
1298	set_current_state(TASK_RUNNING);
1299	break;
1300	}
1301
1302	schedule();
1303	continue;
1304	}
1305
1306	if (bio_op(bio) == REQ_OP_DISCARD) {
1307	writecache_discard(wc, bio->bi_iter.bi_sector,
1308	bio_end_sector(bio));
1309	wc_unlock(wc);
1310	bio_set_dev(bio, wc->dev->bdev);
1311	submit_bio_noacct(bio);
1312	} else {
1313	writecache_flush(wc);
1314	wc_unlock(wc);
1315	if (writecache_has_error(wc))
1316	bio->bi_status = BLK_STS_IOERR;
1317	bio_endio(bio);
1318	}
1319	}
1320
1321	return 0;
1322	}
1323
1324	static void writecache_offload_bio(struct dm_writecache wc, struct bio bio)
1325	{
1326	if (bio_list_empty(&wc->flush_list))
1327	wake_up_process(wc->flush_thread);
1328	bio_list_add(&wc->flush_list, bio);
1329	}
1330
1331	enum wc_map_op {
1332	WC_MAP_SUBMIT,
1333	WC_MAP_REMAP,
1334	WC_MAP_REMAP_ORIGIN,
1335	WC_MAP_RETURN,
1336	WC_MAP_ERROR,
1337	};
1338
1339	static void writecache_map_remap_origin(struct dm_writecache wc, struct bio bio,
1340	struct wc_entry *e)
1341	{
1342	if (e) {
1343	sector_t next_boundary =
1344	read_original_sector(wc, e) - bio->bi_iter.bi_sector;
1345	if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT)
1346	dm_accept_partial_bio(bio, next_boundary);
1347	}
1348	}
1349
1350	static enum wc_map_op writecache_map_read(struct dm_writecache wc, struct bio bio)
1351	{
1352	enum wc_map_op map_op;
1353	struct wc_entry *e;
1354
1355	read_next_block:
1356	wc->stats.reads++;
1357	e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1358	if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
1359	wc->stats.read_hits++;
1360	if (WC_MODE_PMEM(wc)) {
1361	bio_copy_block(wc, bio, memory_data(wc, e));
1362	if (bio->bi_iter.bi_size)
1363	goto read_next_block;
1364	map_op = WC_MAP_SUBMIT;
1365	} else {
1366	dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
1367	bio_set_dev(bio, wc->ssd_dev->bdev);
1368	bio->bi_iter.bi_sector = cache_sector(wc, e);
1369	if (!writecache_entry_is_committed(wc, e))
1370	writecache_wait_for_ios(wc, WRITE);
1371	map_op = WC_MAP_REMAP;
1372	}
1373	} else {
1374	writecache_map_remap_origin(wc, bio, e);
1375	wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1376	map_op = WC_MAP_REMAP_ORIGIN;
1377	}
1378
1379	return map_op;
1380	}
1381
1382	static void writecache_bio_copy_ssd(struct dm_writecache wc, struct bio bio,
1383	struct wc_entry *e, bool search_used)
1384	{
1385	unsigned int bio_size = wc->block_size;
1386	sector_t start_cache_sec = cache_sector(wc, e);
1387	sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
1388
1389	while (bio_size < bio->bi_iter.bi_size) {
1390	if (!search_used) {
1391	struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
1392
1393	if (!f)
1394	break;
1395	write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
1396	(bio_size >> SECTOR_SHIFT), wc->seq_count);
1397	writecache_insert_entry(wc, f);
1398	wc->uncommitted_blocks++;
1399	} else {
1400	struct wc_entry *f;
1401	struct rb_node *next = rb_next(&e->rb_node);
1402
1403	if (!next)
1404	break;
1405	f = container_of(next, struct wc_entry, rb_node);
1406	if (f != e + 1)
1407	break;
1408	if (read_original_sector(wc, f) !=
1409	read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1410	break;
1411	if (unlikely(f->write_in_progress))
1412	break;
1413	if (writecache_entry_is_committed(wc, f))
1414	wc->overwrote_committed = true;
1415	e = f;
1416	}
1417	bio_size += wc->block_size;
1418	current_cache_sec += wc->block_size >> SECTOR_SHIFT;
1419	}
1420
1421	bio_set_dev(bio, wc->ssd_dev->bdev);
1422	bio->bi_iter.bi_sector = start_cache_sec;
1423	dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
1424
1425	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1426	wc->stats.writes_allocate += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1427
1428	if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
1429	wc->uncommitted_blocks = 0;
1430	queue_work(wc->writeback_wq, &wc->flush_work);
1431	} else {
1432	writecache_schedule_autocommit(wc);
1433	}
1434	}
1435
1436	static enum wc_map_op writecache_map_write(struct dm_writecache wc, struct bio bio)
1437	{
1438	struct wc_entry *e;
1439
1440	do {
1441	bool found_entry = false;
1442	bool search_used = false;
1443
1444	if (writecache_has_error(wc)) {
1445	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1446	return WC_MAP_ERROR;
1447	}
1448	e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
1449	if (e) {
1450	if (!writecache_entry_is_committed(wc, e)) {
1451	wc->stats.write_hits_uncommitted++;
1452	search_used = true;
1453	goto bio_copy;
1454	}
1455	wc->stats.write_hits_committed++;
1456	if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
1457	wc->overwrote_committed = true;
1458	search_used = true;
1459	goto bio_copy;
1460	}
1461	found_entry = true;
1462	} else {
1463	if (unlikely(wc->cleaner) \|\|
1464	(wc->metadata_only && !(bio->bi_opf & REQ_META)))
1465	goto direct_write;
1466	}
1467	e = writecache_pop_from_freelist(wc, (sector_t)-1);
1468	if (unlikely(!e)) {
1469	if (!WC_MODE_PMEM(wc) && !found_entry) {
1470	direct_write:
1471	e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1472	writecache_map_remap_origin(wc, bio, e);
1473	wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
1474	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1475	return WC_MAP_REMAP_ORIGIN;
1476	}
1477	wc->stats.writes_blocked_on_freelist++;
1478	writecache_wait_on_freelist(wc);
1479	continue;
1480	}
1481	write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
1482	writecache_insert_entry(wc, e);
1483	wc->uncommitted_blocks++;
1484	wc->stats.writes_allocate++;
1485	bio_copy:
1486	if (WC_MODE_PMEM(wc)) {
1487	bio_copy_block(wc, bio, memory_data(wc, e));
1488	wc->stats.writes++;
1489	} else {
1490	writecache_bio_copy_ssd(wc, bio, e, search_used);
1491	return WC_MAP_REMAP;
1492	}
1493	} while (bio->bi_iter.bi_size);
1494
1495	if (unlikely(bio->bi_opf & REQ_FUA \|\| wc->uncommitted_blocks >= wc->autocommit_blocks))
1496	writecache_flush(wc);
1497	else
1498	writecache_schedule_autocommit(wc);
1499
1500	return WC_MAP_SUBMIT;
1501	}
1502
1503	static enum wc_map_op writecache_map_flush(struct dm_writecache wc, struct bio bio)
1504	{
1505	if (writecache_has_error(wc))
1506	return WC_MAP_ERROR;
1507
1508	if (WC_MODE_PMEM(wc)) {
1509	wc->stats.flushes++;
1510	writecache_flush(wc);
1511	if (writecache_has_error(wc))
1512	return WC_MAP_ERROR;
1513	else if (unlikely(wc->cleaner) \|\| unlikely(wc->metadata_only))
1514	return WC_MAP_REMAP_ORIGIN;
1515	return WC_MAP_SUBMIT;
1516	}
1517	/* SSD: */
1518	if (dm_bio_get_target_bio_nr(bio))
1519	return WC_MAP_REMAP_ORIGIN;
1520	wc->stats.flushes++;
1521	writecache_offload_bio(wc, bio);
1522	return WC_MAP_RETURN;
1523	}
1524
1525	static enum wc_map_op writecache_map_discard(struct dm_writecache wc, struct bio bio)
1526	{
1527	wc->stats.discards += bio->bi_iter.bi_size >> wc->block_size_bits;
1528
1529	if (writecache_has_error(wc))
1530	return WC_MAP_ERROR;
1531
1532	if (WC_MODE_PMEM(wc)) {
1533	writecache_discard(wc, bio->bi_iter.bi_sector, bio_end_sector(bio));
1534	return WC_MAP_REMAP_ORIGIN;
1535	}
1536	/* SSD: */
1537	writecache_offload_bio(wc, bio);
1538	return WC_MAP_RETURN;
1539	}
1540
1541	static int writecache_map(struct dm_target ti, struct bio bio)
1542	{
1543	struct dm_writecache *wc = ti->private;
1544	enum wc_map_op map_op;
1545
1546	bio->bi_private = NULL;
1547
1548	wc_lock(wc);
1549
1550	if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
1551	map_op = writecache_map_flush(wc, bio);
1552	goto done;
1553	}
1554
1555	bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
1556
1557	if (unlikely((((unsigned int)bio->bi_iter.bi_sector \| bio_sectors(bio)) &
1558	(wc->block_size / 512 - 1)) != 0)) {
1559	DMERR("I/O is not aligned, sector %llu, size %u, block size %u",
1560	(unsigned long long)bio->bi_iter.bi_sector,
1561	bio->bi_iter.bi_size, wc->block_size);
1562	map_op = WC_MAP_ERROR;
1563	goto done;
1564	}
1565
1566	if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
1567	map_op = writecache_map_discard(wc, bio);
1568	goto done;
1569	}
1570
1571	if (bio_data_dir(bio) == READ)
1572	map_op = writecache_map_read(wc, bio);
1573	else
1574	map_op = writecache_map_write(wc, bio);
1575	done:
1576	switch (map_op) {
1577	case WC_MAP_REMAP_ORIGIN:
1578	if (likely(wc->pause != 0)) {
1579	if (bio_op(bio) == REQ_OP_WRITE) {
1580	dm_iot_io_begin(&wc->iot, 1);
1581	bio->bi_private = (void *)2;
1582	}
1583	}
1584	bio_set_dev(bio, wc->dev->bdev);
1585	wc_unlock(wc);
1586	return DM_MAPIO_REMAPPED;
1587
1588	case WC_MAP_REMAP:
1589	/* make sure that writecache_end_io decrements bio_in_progress: */
1590	bio->bi_private = (void *)1;
1591	atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
1592	wc_unlock(wc);
1593	return DM_MAPIO_REMAPPED;
1594
1595	case WC_MAP_SUBMIT:
1596	wc_unlock(wc);
1597	bio_endio(bio);
1598	return DM_MAPIO_SUBMITTED;
1599
1600	case WC_MAP_RETURN:
1601	wc_unlock(wc);
1602	return DM_MAPIO_SUBMITTED;
1603
1604	case WC_MAP_ERROR:
1605	wc_unlock(wc);
1606	bio_io_error(bio);
1607	return DM_MAPIO_SUBMITTED;
1608
1609	default:
1610	BUG();
1611	wc_unlock(wc);
1612	return DM_MAPIO_KILL;
1613	}
1614	}
1615
1616	static int writecache_end_io(struct dm_target ti, struct bio bio, blk_status_t *status)
1617	{
1618	struct dm_writecache *wc = ti->private;
1619
1620	if (bio->bi_private == (void *)1) {
1621	int dir = bio_data_dir(bio);
1622
1623	if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
1624	if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
1625	wake_up(&wc->bio_in_progress_wait[dir]);
1626	} else if (bio->bi_private == (void *)2) {
1627	dm_iot_io_end(&wc->iot, 1);
1628	}
1629	return 0;
1630	}
1631
1632	static int writecache_iterate_devices(struct dm_target *ti,
1633	iterate_devices_callout_fn fn, void *data)
1634	{
1635	struct dm_writecache *wc = ti->private;
1636
1637	return fn(ti, wc->dev, 0, ti->len, data);
1638	}
1639
1640	static void writecache_io_hints(struct dm_target ti, struct queue_limits limits)
1641	{
1642	struct dm_writecache *wc = ti->private;
1643
1644	if (limits->logical_block_size < wc->block_size)
1645	limits->logical_block_size = wc->block_size;
1646
1647	if (limits->physical_block_size < wc->block_size)
1648	limits->physical_block_size = wc->block_size;
1649
1650	if (limits->io_min < wc->block_size)
1651	limits->io_min = wc->block_size;
1652	}
1653
1654
1655	static void writecache_writeback_endio(struct bio *bio)
1656	{
1657	struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
1658	struct dm_writecache *wc = wb->wc;
1659	unsigned long flags;
1660
1661	raw_spin_lock_irqsave(&wc->endio_list_lock, flags);
1662	if (unlikely(list_empty(&wc->endio_list)))
1663	wake_up_process(wc->endio_thread);
1664	list_add_tail(&wb->endio_entry, &wc->endio_list);
1665	raw_spin_unlock_irqrestore(&wc->endio_list_lock, flags);
1666	}
1667
1668	static void writecache_copy_endio(int read_err, unsigned long write_err, void *ptr)
1669	{
1670	struct copy_struct *c = ptr;
1671	struct dm_writecache *wc = c->wc;
1672
1673	c->error = likely(!(read_err \| write_err)) ? 0 : -EIO;
1674
1675	raw_spin_lock_irq(&wc->endio_list_lock);
1676	if (unlikely(list_empty(&wc->endio_list)))
1677	wake_up_process(wc->endio_thread);
1678	list_add_tail(&c->endio_entry, &wc->endio_list);
1679	raw_spin_unlock_irq(&wc->endio_list_lock);
1680	}
1681
1682	static void __writecache_endio_pmem(struct dm_writecache wc, struct list_head list)
1683	{
1684	unsigned int i;
1685	struct writeback_struct *wb;
1686	struct wc_entry *e;
1687	unsigned long n_walked = 0;
1688
1689	do {
1690	wb = list_entry(list->next, struct writeback_struct, endio_entry);
1691	list_del(&wb->endio_entry);
1692
1693	if (unlikely(wb->bio.bi_status != BLK_STS_OK))
1694	writecache_error(wc, blk_status_to_errno(wb->bio.bi_status),
1695	"write error %d", wb->bio.bi_status);
1696	i = 0;
1697	do {
1698	e = wb->wc_list[i];
1699	BUG_ON(!e->write_in_progress);
1700	e->write_in_progress = false;
1701	INIT_LIST_HEAD(&e->lru);
1702	if (!writecache_has_error(wc))
1703	writecache_free_entry(wc, e);
1704	BUG_ON(!wc->writeback_size);
1705	wc->writeback_size--;
1706	n_walked++;
1707	if (unlikely(n_walked >= ENDIO_LATENCY)) {
1708	writecache_commit_flushed(wc, false);
1709	wc_unlock(wc);
1710	wc_lock(wc);
1711	n_walked = 0;
1712	}
1713	} while (++i < wb->wc_list_n);
1714
1715	if (wb->wc_list != wb->wc_list_inline)
1716	kfree(wb->wc_list);
1717	bio_put(&wb->bio);
1718	} while (!list_empty(list));
1719	}
1720
1721	static void __writecache_endio_ssd(struct dm_writecache wc, struct list_head list)
1722	{
1723	struct copy_struct *c;
1724	struct wc_entry *e;
1725
1726	do {
1727	c = list_entry(list->next, struct copy_struct, endio_entry);
1728	list_del(&c->endio_entry);
1729
1730	if (unlikely(c->error))
1731	writecache_error(wc, c->error, "copy error");
1732
1733	e = c->e;
1734	do {
1735	BUG_ON(!e->write_in_progress);
1736	e->write_in_progress = false;
1737	INIT_LIST_HEAD(&e->lru);
1738	if (!writecache_has_error(wc))
1739	writecache_free_entry(wc, e);
1740
1741	BUG_ON(!wc->writeback_size);
1742	wc->writeback_size--;
1743	e++;
1744	} while (--c->n_entries);
1745	mempool_free(c, &wc->copy_pool);
1746	} while (!list_empty(list));
1747	}
1748
1749	static int writecache_endio_thread(void *data)
1750	{
1751	struct dm_writecache *wc = data;
1752
1753	while (1) {
1754	struct list_head list;
1755
1756	raw_spin_lock_irq(&wc->endio_list_lock);
1757	if (!list_empty(&wc->endio_list))
1758	goto pop_from_list;
1759	set_current_state(TASK_INTERRUPTIBLE);
1760	raw_spin_unlock_irq(&wc->endio_list_lock);
1761
1762	if (unlikely(kthread_should_stop())) {
1763	set_current_state(TASK_RUNNING);
1764	break;
1765	}
1766
1767	schedule();
1768
1769	continue;
1770
1771	pop_from_list:
1772	list = wc->endio_list;
1773	list.next->prev = list.prev->next = &list;
1774	INIT_LIST_HEAD(&wc->endio_list);
1775	raw_spin_unlock_irq(&wc->endio_list_lock);
1776
1777	if (!WC_MODE_FUA(wc))
1778	writecache_disk_flush(wc, wc->dev);
1779
1780	wc_lock(wc);
1781
1782	if (WC_MODE_PMEM(wc)) {
1783	__writecache_endio_pmem(wc, &list);
1784	} else {
1785	__writecache_endio_ssd(wc, &list);
1786	writecache_wait_for_ios(wc, READ);
1787	}
1788
1789	writecache_commit_flushed(wc, false);
1790
1791	wc_unlock(wc);
1792	}
1793
1794	return 0;
1795	}
1796
1797	static bool wc_add_block(struct writeback_struct wb, struct wc_entry e)
1798	{
1799	struct dm_writecache *wc = wb->wc;
1800	unsigned int block_size = wc->block_size;
1801	void *address = memory_data(wc, e);
1802
1803	persistent_memory_flush_cache(address, block_size);
1804
1805	if (unlikely(bio_end_sector(&wb->bio) >= wc->data_device_sectors))
1806	return true;
1807
1808	return bio_add_page(&wb->bio, persistent_memory_page(address),
1809	block_size, persistent_memory_page_offset(address)) != 0;
1810	}
1811
1812	struct writeback_list {
1813	struct list_head list;
1814	size_t size;
1815	};
1816
1817	static void __writeback_throttle(struct dm_writecache wc, struct writeback_list wbl)
1818	{
1819	if (unlikely(wc->max_writeback_jobs)) {
1820	if (READ_ONCE(wc->writeback_size) - wbl->size >= wc->max_writeback_jobs) {
1821	wc_lock(wc);
1822	while (wc->writeback_size - wbl->size >= wc->max_writeback_jobs)
1823	writecache_wait_on_freelist(wc);
1824	wc_unlock(wc);
1825	}
1826	}
1827	cond_resched();
1828	}
1829
1830	static void __writecache_writeback_pmem(struct dm_writecache wc, struct writeback_list wbl)
1831	{
1832	struct wc_entry e, f;
1833	struct bio *bio;
1834	struct writeback_struct *wb;
1835	unsigned int max_pages;
1836
1837	while (wbl->size) {
1838	wbl->size--;
1839	e = container_of(wbl->list.prev, struct wc_entry, lru);
1840	list_del(&e->lru);
1841
1842	max_pages = e->wc_list_contiguous;
1843
1844	bio = bio_alloc_bioset(wc->dev->bdev, max_pages, REQ_OP_WRITE,
1845	GFP_NOIO, &wc->bio_set);
1846	wb = container_of(bio, struct writeback_struct, bio);
1847	wb->wc = wc;
1848	bio->bi_end_io = writecache_writeback_endio;
1849	bio->bi_iter.bi_sector = read_original_sector(wc, e);
1850
1851	if (unlikely(max_pages > WB_LIST_INLINE))
1852	wb->wc_list = kmalloc_array(max_pages, sizeof(struct wc_entry *),
1853	GFP_NOIO \| __GFP_NORETRY \|
1854	__GFP_NOMEMALLOC \| __GFP_NOWARN);
1855
1856	if (likely(max_pages <= WB_LIST_INLINE) \|\| unlikely(!wb->wc_list)) {
1857	wb->wc_list = wb->wc_list_inline;
1858	max_pages = WB_LIST_INLINE;
1859	}
1860
1861	BUG_ON(!wc_add_block(wb, e));
1862
1863	wb->wc_list[0] = e;
1864	wb->wc_list_n = 1;
1865
1866	while (wbl->size && wb->wc_list_n < max_pages) {
1867	f = container_of(wbl->list.prev, struct wc_entry, lru);
1868	if (read_original_sector(wc, f) !=
1869	read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1870	break;
1871	if (!wc_add_block(wb, f))
1872	break;
1873	wbl->size--;
1874	list_del(&f->lru);
1875	wb->wc_list[wb->wc_list_n++] = f;
1876	e = f;
1877	}
1878	if (WC_MODE_FUA(wc))
1879	bio->bi_opf \|= REQ_FUA;
1880	if (writecache_has_error(wc)) {
1881	bio->bi_status = BLK_STS_IOERR;
1882	bio_endio(bio);
1883	} else if (unlikely(!bio_sectors(bio))) {
1884	bio->bi_status = BLK_STS_OK;
1885	bio_endio(bio);
1886	} else {
1887	submit_bio(bio);
1888	}
1889
1890	__writeback_throttle(wc, wbl);
1891	}
1892	}
1893
1894	static void __writecache_writeback_ssd(struct dm_writecache wc, struct writeback_list wbl)
1895	{
1896	struct wc_entry e, f;
1897	struct dm_io_region from, to;
1898	struct copy_struct *c;
1899
1900	while (wbl->size) {
1901	unsigned int n_sectors;
1902
1903	wbl->size--;
1904	e = container_of(wbl->list.prev, struct wc_entry, lru);
1905	list_del(&e->lru);
1906
1907	n_sectors = e->wc_list_contiguous << (wc->block_size_bits - SECTOR_SHIFT);
1908
1909	from.bdev = wc->ssd_dev->bdev;
1910	from.sector = cache_sector(wc, e);
1911	from.count = n_sectors;
1912	to.bdev = wc->dev->bdev;
1913	to.sector = read_original_sector(wc, e);
1914	to.count = n_sectors;
1915
1916	c = mempool_alloc(&wc->copy_pool, GFP_NOIO);
1917	c->wc = wc;
1918	c->e = e;
1919	c->n_entries = e->wc_list_contiguous;
1920
1921	while ((n_sectors -= wc->block_size >> SECTOR_SHIFT)) {
1922	wbl->size--;
1923	f = container_of(wbl->list.prev, struct wc_entry, lru);
1924	BUG_ON(f != e + 1);
1925	list_del(&f->lru);
1926	e = f;
1927	}
1928
1929	if (unlikely(to.sector + to.count > wc->data_device_sectors)) {
1930	if (to.sector >= wc->data_device_sectors) {
1931	writecache_copy_endio(0, 0, c);
1932	continue;
1933	}
1934	from.count = to.count = wc->data_device_sectors - to.sector;
1935	}
1936
1937	dm_kcopyd_copy(wc->dm_kcopyd, &from, 1, &to, 0, writecache_copy_endio, c);
1938
1939	__writeback_throttle(wc, wbl);
1940	}
1941	}
1942
1943	static void writecache_writeback(struct work_struct *work)
1944	{
1945	struct dm_writecache *wc = container_of(work, struct dm_writecache, writeback_work);
1946	struct blk_plug plug;
1947	struct wc_entry f, g, *e = NULL;
1948	struct rb_node node, next_node;
1949	struct list_head skipped;
1950	struct writeback_list wbl;
1951	unsigned long n_walked;
1952
1953	if (!WC_MODE_PMEM(wc)) {
1954	/* Wait for any active kcopyd work on behalf of ssd writeback */
1955	dm_kcopyd_client_flush(wc->dm_kcopyd);
1956	}
1957
1958	if (likely(wc->pause != 0)) {
1959	while (1) {
1960	unsigned long idle;
1961
1962	if (unlikely(wc->cleaner) \|\| unlikely(wc->writeback_all) \|\|
1963	unlikely(dm_suspended(wc->ti)))
1964	break;
1965	idle = dm_iot_idle_time(&wc->iot);
1966	if (idle >= wc->pause)
1967	break;
1968	idle = wc->pause - idle;
1969	if (idle > HZ)
1970	idle = HZ;
1971	schedule_timeout_idle(idle);
1972	}
1973	}
1974
1975	wc_lock(wc);
1976	restart:
1977	if (writecache_has_error(wc)) {
1978	wc_unlock(wc);
1979	return;
1980	}
1981
1982	if (unlikely(wc->writeback_all)) {
1983	if (writecache_wait_for_writeback(wc))
1984	goto restart;
1985	}
1986
1987	if (wc->overwrote_committed)
1988	writecache_wait_for_ios(wc, WRITE);
1989
1990	n_walked = 0;
1991	INIT_LIST_HEAD(&skipped);
1992	INIT_LIST_HEAD(&wbl.list);
1993	wbl.size = 0;
1994	while (!list_empty(&wc->lru) &&
1995	(wc->writeback_all \|\|
1996	wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark \|\|
1997	(jiffies - container_of(wc->lru.prev, struct wc_entry, lru)->age >=
1998	wc->max_age - wc->max_age / MAX_AGE_DIV))) {
1999
2000	n_walked++;
2001	if (unlikely(n_walked > WRITEBACK_LATENCY) &&
2002	likely(!wc->writeback_all)) {
2003	if (likely(!dm_suspended(wc->ti)))
2004	queue_work(wc->writeback_wq, &wc->writeback_work);
2005	break;
2006	}
2007
2008	if (unlikely(wc->writeback_all)) {
2009	if (unlikely(!e)) {
2010	writecache_flush(wc);
2011	e = container_of(rb_first(&wc->tree), struct wc_entry, rb_node);
2012	} else
2013	e = g;
2014	} else
2015	e = container_of(wc->lru.prev, struct wc_entry, lru);
2016	BUG_ON(e->write_in_progress);
2017	if (unlikely(!writecache_entry_is_committed(wc, e)))
2018	writecache_flush(wc);
2019
2020	node = rb_prev(&e->rb_node);
2021	if (node) {
2022	f = container_of(node, struct wc_entry, rb_node);
2023	if (unlikely(read_original_sector(wc, f) ==
2024	read_original_sector(wc, e))) {
2025	BUG_ON(!f->write_in_progress);
2026	list_move(&e->lru, &skipped);
2027	cond_resched();
2028	continue;
2029	}
2030	}
2031	wc->writeback_size++;
2032	list_move(&e->lru, &wbl.list);
2033	wbl.size++;
2034	e->write_in_progress = true;
2035	e->wc_list_contiguous = 1;
2036
2037	f = e;
2038
2039	while (1) {
2040	next_node = rb_next(&f->rb_node);
2041	if (unlikely(!next_node))
2042	break;
2043	g = container_of(next_node, struct wc_entry, rb_node);
2044	if (unlikely(read_original_sector(wc, g) ==
2045	read_original_sector(wc, f))) {
2046	f = g;
2047	continue;
2048	}
2049	if (read_original_sector(wc, g) !=
2050	read_original_sector(wc, f) + (wc->block_size >> SECTOR_SHIFT))
2051	break;
2052	if (unlikely(g->write_in_progress))
2053	break;
2054	if (unlikely(!writecache_entry_is_committed(wc, g)))
2055	break;
2056
2057	if (!WC_MODE_PMEM(wc)) {
2058	if (g != f + 1)
2059	break;
2060	}
2061
2062	n_walked++;
2063	//if (unlikely(n_walked > WRITEBACK_LATENCY) && likely(!wc->writeback_all))
2064	// break;
2065
2066	wc->writeback_size++;
2067	list_move(&g->lru, &wbl.list);
2068	wbl.size++;
2069	g->write_in_progress = true;
2070	g->wc_list_contiguous = BIO_MAX_VECS;
2071	f = g;
2072	e->wc_list_contiguous++;
2073	if (unlikely(e->wc_list_contiguous == BIO_MAX_VECS)) {
2074	if (unlikely(wc->writeback_all)) {
2075	next_node = rb_next(&f->rb_node);
2076	if (likely(next_node))
2077	g = container_of(next_node, struct wc_entry, rb_node);
2078	}
2079	break;
2080	}
2081	}
2082	cond_resched();
2083	}
2084
2085	if (!list_empty(&skipped)) {
2086	list_splice_tail(&skipped, &wc->lru);
2087	/*
2088	* If we didn't do any progress, we must wait until some
2089	* writeback finishes to avoid burning CPU in a loop
2090	*/
2091	if (unlikely(!wbl.size))
2092	writecache_wait_for_writeback(wc);
2093	}
2094
2095	wc_unlock(wc);
2096
2097	blk_start_plug(&plug);
2098
2099	if (WC_MODE_PMEM(wc))
2100	__writecache_writeback_pmem(wc, &wbl);
2101	else
2102	__writecache_writeback_ssd(wc, &wbl);
2103
2104	blk_finish_plug(&plug);
2105
2106	if (unlikely(wc->writeback_all)) {
2107	wc_lock(wc);
2108	while (writecache_wait_for_writeback(wc))
2109	;
2110	wc_unlock(wc);
2111	}
2112	}
2113
2114	static int calculate_memory_size(uint64_t device_size, unsigned int block_size,
2115	size_t n_blocks_p, size_t n_metadata_blocks_p)
2116	{
2117	uint64_t n_blocks, offset;
2118	struct wc_entry e;
2119
2120	n_blocks = device_size;
2121	do_div(n_blocks, block_size + sizeof(struct wc_memory_entry));
2122
2123	while (1) {
2124	if (!n_blocks)
2125	return -ENOSPC;
2126	/* Verify the following entries[n_blocks] won't overflow */
2127	if (n_blocks >= ((size_t)-sizeof(struct wc_memory_superblock) /
2128	sizeof(struct wc_memory_entry)))
2129	return -EFBIG;
2130	offset = offsetof(struct wc_memory_superblock, entries[n_blocks]);
2131	offset = (offset + block_size - 1) & ~(uint64_t)(block_size - 1);
2132	if (offset + n_blocks * block_size <= device_size)
2133	break;
2134	n_blocks--;
2135	}
2136
2137	/* check if the bit field overflows */
2138	e.index = n_blocks;
2139	if (e.index != n_blocks)
2140	return -EFBIG;
2141
2142	if (n_blocks_p)
2143	*n_blocks_p = n_blocks;
2144	if (n_metadata_blocks_p)
2145	*n_metadata_blocks_p = offset >> __ffs(block_size);
2146	return 0;
2147	}
2148
2149	static int init_memory(struct dm_writecache *wc)
2150	{
2151	size_t b;
2152	int r;
2153
2154	r = calculate_memory_size(wc->memory_map_size, wc->block_size, &wc->n_blocks, NULL);
2155	if (r)
2156	return r;
2157
2158	r = writecache_alloc_entries(wc);
2159	if (r)
2160	return r;
2161
2162	for (b = 0; b < ARRAY_SIZE(sb(wc)->padding); b++)
2163	pmem_assign(sb(wc)->padding[b], cpu_to_le64(0));
2164	pmem_assign(sb(wc)->version, cpu_to_le32(MEMORY_SUPERBLOCK_VERSION));
2165	pmem_assign(sb(wc)->block_size, cpu_to_le32(wc->block_size));
2166	pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
2167	pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
2168
2169	for (b = 0; b < wc->n_blocks; b++) {
2170	write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
2171	cond_resched();
2172	}
2173
2174	writecache_flush_all_metadata(wc);
2175	writecache_commit_flushed(wc, false);
2176	pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
2177	writecache_flush_region(wc, &sb(wc)->magic, sizeof(sb(wc)->magic));
2178	writecache_commit_flushed(wc, false);
2179
2180	return 0;
2181	}
2182
2183	static void writecache_dtr(struct dm_target *ti)
2184	{
2185	struct dm_writecache *wc = ti->private;
2186
2187	if (!wc)
2188	return;
2189
2190	if (wc->endio_thread)
2191	kthread_stop(wc->endio_thread);
2192
2193	if (wc->flush_thread)
2194	kthread_stop(wc->flush_thread);
2195
2196	bioset_exit(&wc->bio_set);
2197
2198	mempool_exit(&wc->copy_pool);
2199
2200	if (wc->writeback_wq)
2201	destroy_workqueue(wc->writeback_wq);
2202
2203	if (wc->dev)
2204	dm_put_device(ti, wc->dev);
2205
2206	if (wc->ssd_dev)
2207	dm_put_device(ti, wc->ssd_dev);
2208
2209	vfree(wc->entries);
2210
2211	if (wc->memory_map) {
2212	if (WC_MODE_PMEM(wc))
2213	persistent_memory_release(wc);
2214	else
2215	vfree(wc->memory_map);
2216	}
2217
2218	if (wc->dm_kcopyd)
2219	dm_kcopyd_client_destroy(wc->dm_kcopyd);
2220
2221	if (wc->dm_io)
2222	dm_io_client_destroy(wc->dm_io);
2223
2224	vfree(wc->dirty_bitmap);
2225
2226	kfree(wc);
2227	}
2228
2229	static int writecache_ctr(struct dm_target ti, unsigned int argc, char *argv)
2230	{
2231	struct dm_writecache *wc;
2232	struct dm_arg_set as;
2233	const char *string;
2234	unsigned int opt_params;
2235	size_t offset, data_size;
2236	int i, r;
2237	char dummy;
2238	int high_wm_percent = HIGH_WATERMARK;
2239	int low_wm_percent = LOW_WATERMARK;
2240	uint64_t x;
2241	struct wc_memory_superblock s;
2242
2243	static struct dm_arg _args[] = {
2244	{0, 18, "Invalid number of feature args"},
2245	};
2246
2247	as.argc = argc;
2248	as.argv = argv;
2249
2250	wc = kzalloc(sizeof(struct dm_writecache), GFP_KERNEL);
2251	if (!wc) {
2252	ti->error = "Cannot allocate writecache structure";
2253	r = -ENOMEM;
2254	goto bad;
2255	}
2256	ti->private = wc;
2257	wc->ti = ti;
2258
2259	mutex_init(&wc->lock);
2260	wc->max_age = MAX_AGE_UNSPECIFIED;
2261	writecache_poison_lists(wc);
2262	init_waitqueue_head(&wc->freelist_wait);
2263	timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0);
2264	timer_setup(&wc->max_age_timer, writecache_max_age_timer, 0);
2265
2266	for (i = 0; i < 2; i++) {
2267	atomic_set(&wc->bio_in_progress[i], 0);
2268	init_waitqueue_head(&wc->bio_in_progress_wait[i]);
2269	}
2270
2271	wc->dm_io = dm_io_client_create();
2272	if (IS_ERR(wc->dm_io)) {
2273	r = PTR_ERR(wc->dm_io);
2274	ti->error = "Unable to allocate dm-io client";
2275	wc->dm_io = NULL;
2276	goto bad;
2277	}
2278
2279	wc->writeback_wq = alloc_workqueue("writecache-writeback", WQ_MEM_RECLAIM, 1);
2280	if (!wc->writeback_wq) {
2281	r = -ENOMEM;
2282	ti->error = "Could not allocate writeback workqueue";
2283	goto bad;
2284	}
2285	INIT_WORK(&wc->writeback_work, writecache_writeback);
2286	INIT_WORK(&wc->flush_work, writecache_flush_work);
2287
2288	dm_iot_init(&wc->iot);
2289
2290	raw_spin_lock_init(&wc->endio_list_lock);
2291	INIT_LIST_HEAD(&wc->endio_list);
2292	wc->endio_thread = kthread_run(writecache_endio_thread, wc, "writecache_endio");
2293	if (IS_ERR(wc->endio_thread)) {
2294	r = PTR_ERR(wc->endio_thread);
2295	wc->endio_thread = NULL;
2296	ti->error = "Couldn't spawn endio thread";
2297	goto bad;
2298	}
2299
2300	/*
2301	* Parse the mode (pmem or ssd)
2302	*/
2303	string = dm_shift_arg(&as);
2304	if (!string)
2305	goto bad_arguments;
2306
2307	if (!strcasecmp(string, "s")) {
2308	wc->pmem_mode = false;
2309	} else if (!strcasecmp(string, "p")) {
2310	#ifdef DM_WRITECACHE_HAS_PMEM
2311	wc->pmem_mode = true;
2312	wc->writeback_fua = true;
2313	#else
2314	/*
2315	* If the architecture doesn't support persistent memory or
2316	* the kernel doesn't support any DAX drivers, this driver can
2317	* only be used in SSD-only mode.
2318	*/
2319	r = -EOPNOTSUPP;
2320	ti->error = "Persistent memory or DAX not supported on this system";
2321	goto bad;
2322	#endif
2323	} else {
2324	goto bad_arguments;
2325	}
2326
2327	if (WC_MODE_PMEM(wc)) {
2328	r = bioset_init(&wc->bio_set, BIO_POOL_SIZE,
2329	offsetof(struct writeback_struct, bio),
2330	BIOSET_NEED_BVECS);
2331	if (r) {
2332	ti->error = "Could not allocate bio set";
2333	goto bad;
2334	}
2335	} else {
2336	wc->pause = PAUSE_WRITEBACK;
2337	r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
2338	if (r) {
2339	ti->error = "Could not allocate mempool";
2340	goto bad;
2341	}
2342	}
2343
2344	/*
2345	* Parse the origin data device
2346	*/
2347	string = dm_shift_arg(&as);
2348	if (!string)
2349	goto bad_arguments;
2350	r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->dev);
2351	if (r) {
2352	ti->error = "Origin data device lookup failed";
2353	goto bad;
2354	}
2355
2356	/*
2357	* Parse cache data device (be it pmem or ssd)
2358	*/
2359	string = dm_shift_arg(&as);
2360	if (!string)
2361	goto bad_arguments;
2362
2363	r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->ssd_dev);
2364	if (r) {
2365	ti->error = "Cache data device lookup failed";
2366	goto bad;
2367	}
2368	wc->memory_map_size = bdev_nr_bytes(wc->ssd_dev->bdev);
2369
2370	/*
2371	* Parse the cache block size
2372	*/
2373	string = dm_shift_arg(&as);
2374	if (!string)
2375	goto bad_arguments;
2376	if (sscanf(string, "%u%c", &wc->block_size, &dummy) != 1 \|\|
2377	wc->block_size < 512 \|\| wc->block_size > PAGE_SIZE \|\|
2378	(wc->block_size & (wc->block_size - 1))) {
2379	r = -EINVAL;
2380	ti->error = "Invalid block size";
2381	goto bad;
2382	}
2383	if (wc->block_size < bdev_logical_block_size(wc->dev->bdev) \|\|
2384	wc->block_size < bdev_logical_block_size(wc->ssd_dev->bdev)) {
2385	r = -EINVAL;
2386	ti->error = "Block size is smaller than device logical block size";
2387	goto bad;
2388	}
2389	wc->block_size_bits = __ffs(wc->block_size);
2390
2391	wc->max_writeback_jobs = MAX_WRITEBACK_JOBS;
2392	wc->autocommit_blocks = !WC_MODE_PMEM(wc) ? AUTOCOMMIT_BLOCKS_SSD : AUTOCOMMIT_BLOCKS_PMEM;
2393	wc->autocommit_jiffies = msecs_to_jiffies(AUTOCOMMIT_MSEC);
2394
2395	/*
2396	* Parse optional arguments
2397	*/
2398	r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
2399	if (r)
2400	goto bad;
2401
2402	while (opt_params) {
2403	string = dm_shift_arg(&as), opt_params--;
2404	if (!strcasecmp(string, "start_sector") && opt_params >= 1) {
2405	unsigned long long start_sector;
2406
2407	string = dm_shift_arg(&as), opt_params--;
2408	if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
2409	goto invalid_optional;
2410	wc->start_sector = start_sector;
2411	wc->start_sector_set = true;
2412	if (wc->start_sector != start_sector \|\|
2413	wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
2414	goto invalid_optional;
2415	} else if (!strcasecmp(string, "high_watermark") && opt_params >= 1) {
2416	string = dm_shift_arg(&as), opt_params--;
2417	if (sscanf(string, "%d%c", &high_wm_percent, &dummy) != 1)
2418	goto invalid_optional;
2419	if (high_wm_percent < 0 \|\| high_wm_percent > 100)
2420	goto invalid_optional;
2421	wc->high_wm_percent_value = high_wm_percent;
2422	wc->high_wm_percent_set = true;
2423	} else if (!strcasecmp(string, "low_watermark") && opt_params >= 1) {
2424	string = dm_shift_arg(&as), opt_params--;
2425	if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
2426	goto invalid_optional;
2427	if (low_wm_percent < 0 \|\| low_wm_percent > 100)
2428	goto invalid_optional;
2429	wc->low_wm_percent_value = low_wm_percent;
2430	wc->low_wm_percent_set = true;
2431	} else if (!strcasecmp(string, "writeback_jobs") && opt_params >= 1) {
2432	string = dm_shift_arg(&as), opt_params--;
2433	if (sscanf(string, "%u%c", &wc->max_writeback_jobs, &dummy) != 1)
2434	goto invalid_optional;
2435	wc->max_writeback_jobs_set = true;
2436	} else if (!strcasecmp(string, "autocommit_blocks") && opt_params >= 1) {
2437	string = dm_shift_arg(&as), opt_params--;
2438	if (sscanf(string, "%u%c", &wc->autocommit_blocks, &dummy) != 1)
2439	goto invalid_optional;
2440	wc->autocommit_blocks_set = true;
2441	} else if (!strcasecmp(string, "autocommit_time") && opt_params >= 1) {
2442	unsigned int autocommit_msecs;
2443
2444	string = dm_shift_arg(&as), opt_params--;
2445	if (sscanf(string, "%u%c", &autocommit_msecs, &dummy) != 1)
2446	goto invalid_optional;
2447	if (autocommit_msecs > 3600000)
2448	goto invalid_optional;
2449	wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs);
2450	wc->autocommit_time_value = autocommit_msecs;
2451	wc->autocommit_time_set = true;
2452	} else if (!strcasecmp(string, "max_age") && opt_params >= 1) {
2453	unsigned int max_age_msecs;
2454
2455	string = dm_shift_arg(&as), opt_params--;
2456	if (sscanf(string, "%u%c", &max_age_msecs, &dummy) != 1)
2457	goto invalid_optional;
2458	if (max_age_msecs > 86400000)
2459	goto invalid_optional;
2460	wc->max_age = msecs_to_jiffies(max_age_msecs);
2461	wc->max_age_set = true;
2462	wc->max_age_value = max_age_msecs;
2463	} else if (!strcasecmp(string, "cleaner")) {
2464	wc->cleaner_set = true;
2465	wc->cleaner = true;
2466	} else if (!strcasecmp(string, "fua")) {
2467	if (WC_MODE_PMEM(wc)) {
2468	wc->writeback_fua = true;
2469	wc->writeback_fua_set = true;
2470	} else
2471	goto invalid_optional;
2472	} else if (!strcasecmp(string, "nofua")) {
2473	if (WC_MODE_PMEM(wc)) {
2474	wc->writeback_fua = false;
2475	wc->writeback_fua_set = true;
2476	} else
2477	goto invalid_optional;
2478	} else if (!strcasecmp(string, "metadata_only")) {
2479	wc->metadata_only = true;
2480	} else if (!strcasecmp(string, "pause_writeback") && opt_params >= 1) {
2481	unsigned int pause_msecs;
2482
2483	if (WC_MODE_PMEM(wc))
2484	goto invalid_optional;
2485	string = dm_shift_arg(&as), opt_params--;
2486	if (sscanf(string, "%u%c", &pause_msecs, &dummy) != 1)
2487	goto invalid_optional;
2488	if (pause_msecs > 60000)
2489	goto invalid_optional;
2490	wc->pause = msecs_to_jiffies(pause_msecs);
2491	wc->pause_set = true;
2492	wc->pause_value = pause_msecs;
2493	} else {
2494	invalid_optional:
2495	r = -EINVAL;
2496	ti->error = "Invalid optional argument";
2497	goto bad;
2498	}
2499	}
2500
2501	if (high_wm_percent < low_wm_percent) {
2502	r = -EINVAL;
2503	ti->error = "High watermark must be greater than or equal to low watermark";
2504	goto bad;
2505	}
2506
2507	if (WC_MODE_PMEM(wc)) {
2508	if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
2509	r = -EOPNOTSUPP;
2510	ti->error = "Asynchronous persistent memory not supported as pmem cache";
2511	goto bad;
2512	}
2513
2514	r = persistent_memory_claim(wc);
2515	if (r) {
2516	ti->error = "Unable to map persistent memory for cache";
2517	goto bad;
2518	}
2519	} else {
2520	size_t n_blocks, n_metadata_blocks;
2521	uint64_t n_bitmap_bits;
2522
2523	wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
2524
2525	bio_list_init(&wc->flush_list);
2526	wc->flush_thread = kthread_run(writecache_flush_thread, wc, "dm_writecache_flush");
2527	if (IS_ERR(wc->flush_thread)) {
2528	r = PTR_ERR(wc->flush_thread);
2529	wc->flush_thread = NULL;
2530	ti->error = "Couldn't spawn flush thread";
2531	goto bad;
2532	}
2533
2534	r = calculate_memory_size(wc->memory_map_size, wc->block_size,
2535	&n_blocks, &n_metadata_blocks);
2536	if (r) {
2537	ti->error = "Invalid device size";
2538	goto bad;
2539	}
2540
2541	n_bitmap_bits = (((uint64_t)n_metadata_blocks << wc->block_size_bits) +
2542	BITMAP_GRANULARITY - 1) / BITMAP_GRANULARITY;
2543	/* this is limitation of test_bit functions */
2544	if (n_bitmap_bits > 1U << 31) {
2545	r = -EFBIG;
2546	ti->error = "Invalid device size";
2547	goto bad;
2548	}
2549
2550	wc->memory_map = vmalloc(n_metadata_blocks << wc->block_size_bits);
2551	if (!wc->memory_map) {
2552	r = -ENOMEM;
2553	ti->error = "Unable to allocate memory for metadata";
2554	goto bad;
2555	}
2556
2557	wc->dm_kcopyd = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2558	if (IS_ERR(wc->dm_kcopyd)) {
2559	r = PTR_ERR(wc->dm_kcopyd);
2560	ti->error = "Unable to allocate dm-kcopyd client";
2561	wc->dm_kcopyd = NULL;
2562	goto bad;
2563	}
2564
2565	wc->metadata_sectors = n_metadata_blocks << (wc->block_size_bits - SECTOR_SHIFT);
2566	wc->dirty_bitmap_size = (n_bitmap_bits + BITS_PER_LONG - 1) /
2567	BITS_PER_LONG * sizeof(unsigned long);
2568	wc->dirty_bitmap = vzalloc(wc->dirty_bitmap_size);
2569	if (!wc->dirty_bitmap) {
2570	r = -ENOMEM;
2571	ti->error = "Unable to allocate dirty bitmap";
2572	goto bad;
2573	}
2574
2575	r = writecache_read_metadata(wc, wc->block_size >> SECTOR_SHIFT);
2576	if (r) {
2577	ti->error = "Unable to read first block of metadata";
2578	goto bad;
2579	}
2580	}
2581
2582	r = copy_mc_to_kernel(&s, sb(wc), sizeof(struct wc_memory_superblock));
2583	if (r) {
2584	ti->error = "Hardware memory error when reading superblock";
2585	goto bad;
2586	}
2587	if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
2588	r = init_memory(wc);
2589	if (r) {
2590	ti->error = "Unable to initialize device";
2591	goto bad;
2592	}
2593	r = copy_mc_to_kernel(&s, sb(wc),
2594	sizeof(struct wc_memory_superblock));
2595	if (r) {
2596	ti->error = "Hardware memory error when reading superblock";
2597	goto bad;
2598	}
2599	}
2600
2601	if (le32_to_cpu(s.magic) != MEMORY_SUPERBLOCK_MAGIC) {
2602	ti->error = "Invalid magic in the superblock";
2603	r = -EINVAL;
2604	goto bad;
2605	}
2606
2607	if (le32_to_cpu(s.version) != MEMORY_SUPERBLOCK_VERSION) {
2608	ti->error = "Invalid version in the superblock";
2609	r = -EINVAL;
2610	goto bad;
2611	}
2612
2613	if (le32_to_cpu(s.block_size) != wc->block_size) {
2614	ti->error = "Block size does not match superblock";
2615	r = -EINVAL;
2616	goto bad;
2617	}
2618
2619	wc->n_blocks = le64_to_cpu(s.n_blocks);
2620
2621	offset = wc->n_blocks * sizeof(struct wc_memory_entry);
2622	if (offset / sizeof(struct wc_memory_entry) != le64_to_cpu(sb(wc)->n_blocks)) {
2623	overflow:
2624	ti->error = "Overflow in size calculation";
2625	r = -EINVAL;
2626	goto bad;
2627	}
2628	offset += sizeof(struct wc_memory_superblock);
2629	if (offset < sizeof(struct wc_memory_superblock))
2630	goto overflow;
2631	offset = (offset + wc->block_size - 1) & ~(size_t)(wc->block_size - 1);
2632	data_size = wc->n_blocks * (size_t)wc->block_size;
2633	if (!offset \|\| (data_size / wc->block_size != wc->n_blocks) \|\|
2634	(offset + data_size < offset))
2635	goto overflow;
2636	if (offset + data_size > wc->memory_map_size) {
2637	ti->error = "Memory area is too small";
2638	r = -EINVAL;
2639	goto bad;
2640	}
2641
2642	wc->metadata_sectors = offset >> SECTOR_SHIFT;
2643	wc->block_start = (char *)sb(wc) + offset;
2644
2645	x = (uint64_t)wc->n_blocks * (100 - high_wm_percent);
2646	x += 50;
2647	do_div(x, 100);
2648	wc->freelist_high_watermark = x;
2649	x = (uint64_t)wc->n_blocks * (100 - low_wm_percent);
2650	x += 50;
2651	do_div(x, 100);
2652	wc->freelist_low_watermark = x;
2653
2654	if (wc->cleaner)
2655	activate_cleaner(wc);
2656
2657	r = writecache_alloc_entries(wc);
2658	if (r) {
2659	ti->error = "Cannot allocate memory";
2660	goto bad;
2661	}
2662
2663	ti->num_flush_bios = WC_MODE_PMEM(wc) ? 1 : 2;
2664	ti->flush_supported = true;
2665	ti->num_discard_bios = 1;
2666
2667	if (WC_MODE_PMEM(wc))
2668	persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
2669
2670	return 0;
2671
2672	bad_arguments:
2673	r = -EINVAL;
2674	ti->error = "Bad arguments";
2675	bad:
2676	writecache_dtr(ti);
2677	return r;
2678	}
2679
2680	static void writecache_status(struct dm_target *ti, status_type_t type,
2681	unsigned int status_flags, char *result, unsigned int maxlen)
2682	{
2683	struct dm_writecache *wc = ti->private;
2684	unsigned int extra_args;
2685	unsigned int sz = 0;
2686
2687	switch (type) {
2688	case STATUSTYPE_INFO:
2689	DMEMIT("%ld %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu",
2690	writecache_has_error(wc),
2691	(unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
2692	(unsigned long long)wc->writeback_size,
2693	wc->stats.reads,
2694	wc->stats.read_hits,
2695	wc->stats.writes,
2696	wc->stats.write_hits_uncommitted,
2697	wc->stats.write_hits_committed,
2698	wc->stats.writes_around,
2699	wc->stats.writes_allocate,
2700	wc->stats.writes_blocked_on_freelist,
2701	wc->stats.flushes,
2702	wc->stats.discards);
2703	break;
2704	case STATUSTYPE_TABLE:
2705	DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
2706	wc->dev->name, wc->ssd_dev->name, wc->block_size);
2707	extra_args = 0;
2708	if (wc->start_sector_set)
2709	extra_args += 2;
2710	if (wc->high_wm_percent_set)
2711	extra_args += 2;
2712	if (wc->low_wm_percent_set)
2713	extra_args += 2;
2714	if (wc->max_writeback_jobs_set)
2715	extra_args += 2;
2716	if (wc->autocommit_blocks_set)
2717	extra_args += 2;
2718	if (wc->autocommit_time_set)
2719	extra_args += 2;
2720	if (wc->max_age_set)
2721	extra_args += 2;
2722	if (wc->cleaner_set)
2723	extra_args++;
2724	if (wc->writeback_fua_set)
2725	extra_args++;
2726	if (wc->metadata_only)
2727	extra_args++;
2728	if (wc->pause_set)
2729	extra_args += 2;
2730
2731	DMEMIT("%u", extra_args);
2732	if (wc->start_sector_set)
2733	DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
2734	if (wc->high_wm_percent_set)
2735	DMEMIT(" high_watermark %u", wc->high_wm_percent_value);
2736	if (wc->low_wm_percent_set)
2737	DMEMIT(" low_watermark %u", wc->low_wm_percent_value);
2738	if (wc->max_writeback_jobs_set)
2739	DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
2740	if (wc->autocommit_blocks_set)
2741	DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
2742	if (wc->autocommit_time_set)
2743	DMEMIT(" autocommit_time %u", wc->autocommit_time_value);
2744	if (wc->max_age_set)
2745	DMEMIT(" max_age %u", wc->max_age_value);
2746	if (wc->cleaner_set)
2747	DMEMIT(" cleaner");
2748	if (wc->writeback_fua_set)
2749	DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
2750	if (wc->metadata_only)
2751	DMEMIT(" metadata_only");
2752	if (wc->pause_set)
2753	DMEMIT(" pause_writeback %u", wc->pause_value);
2754	break;
2755	case STATUSTYPE_IMA:
2756	*result = '\0';
2757	break;
2758	}
2759	}
2760
2761	static struct target_type writecache_target = {
2762	.name = "writecache",
2763	.version = {1, 6, 0},
2764	.module = THIS_MODULE,
2765	.ctr = writecache_ctr,
2766	.dtr = writecache_dtr,
2767	.status = writecache_status,
2768	.postsuspend = writecache_suspend,
2769	.resume = writecache_resume,
2770	.message = writecache_message,
2771	.map = writecache_map,
2772	.end_io = writecache_end_io,
2773	.iterate_devices = writecache_iterate_devices,
2774	.io_hints = writecache_io_hints,
2775	};
2776	module_dm(writecache);
2777
2778	MODULE_DESCRIPTION(DM_NAME " writecache target");
2779	MODULE_AUTHOR("Mikulas Patocka <[email protected]>");
2780	MODULE_LICENSE("GPL");