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/libnvdimm.h>
17	#include <linux/delay.h>
18	#include "dm-io-tracker.h"
19
20	#define DM_MSG_PREFIX "writecache"
21
22	#define HIGH_WATERMARK 50
23	#define LOW_WATERMARK 45
24	#define MAX_WRITEBACK_JOBS min(0x10000000 / PAGE_SIZE, totalram_pages() / 16)
25	#define ENDIO_LATENCY 16
26	#define WRITEBACK_LATENCY 64
27	#define AUTOCOMMIT_BLOCKS_SSD 65536
28	#define AUTOCOMMIT_BLOCKS_PMEM 64
29	#define AUTOCOMMIT_MSEC 1000
30	#define MAX_AGE_DIV 16
31	#define MAX_AGE_UNSPECIFIED -1UL
32	#define PAUSE_WRITEBACK (HZ * 3)
33
34	#define BITMAP_GRANULARITY 65536
35	#if BITMAP_GRANULARITY < PAGE_SIZE
36	#undef BITMAP_GRANULARITY
37	#define BITMAP_GRANULARITY PAGE_SIZE
38	#endif
39
40	#if IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_FS_DAX)
41	#define DM_WRITECACHE_HAS_PMEM
42	#endif
43
44	#ifdef DM_WRITECACHE_HAS_PMEM
45	#define pmem_assign(dest, src) \
46	do { \
47	typeof(dest) uniq = (src); \
48	memcpy_flushcache(&(dest), &uniq, sizeof(dest)); \
49	} while (0)
50	#else
51	#define pmem_assign(dest, src) ((dest) = (src))
52	#endif
53
54	#if IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC) && defined(DM_WRITECACHE_HAS_PMEM)
55	#define DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
56	#endif
57
58	#define MEMORY_SUPERBLOCK_MAGIC 0x23489321
59	#define MEMORY_SUPERBLOCK_VERSION 1
60
61	struct wc_memory_entry {
62	__le64 original_sector;
63	__le64 seq_count;
64	};
65
66	struct wc_memory_superblock {
67	union {
68	struct {
69	__le32 magic;
70	__le32 version;
71	__le32 block_size;
72	__le32 pad;
73	__le64 n_blocks;
74	__le64 seq_count;
75	};
76	__le64 padding[8];
77	};
78	struct wc_memory_entry entries[];
79	};
80
81	struct wc_entry {
82	struct rb_node rb_node;
83	struct list_head lru;
84	unsigned short wc_list_contiguous;
85	#if BITS_PER_LONG == 64
86	bool write_in_progress : 1;
87	unsigned long index : 47;
88	#else
89	bool write_in_progress;
90	unsigned long index;
91	#endif
92	unsigned long age;
93	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
94	uint64_t original_sector;
95	uint64_t seq_count;
96	#endif
97	};
98
99	#ifdef DM_WRITECACHE_HAS_PMEM
100	#define WC_MODE_PMEM(wc) ((wc)->pmem_mode)
101	#define WC_MODE_FUA(wc) ((wc)->writeback_fua)
102	#else
103	#define WC_MODE_PMEM(wc) false
104	#define WC_MODE_FUA(wc) false
105	#endif
106	#define WC_MODE_SORT_FREELIST(wc) (!WC_MODE_PMEM(wc))
107
108	struct dm_writecache {
109	struct mutex lock;
110	struct list_head lru;
111	union {
112	struct list_head freelist;
113	struct {
114	struct rb_root freetree;
115	struct wc_entry *current_free;
116	};
117	};
118	struct rb_root tree;
119
120	size_t freelist_size;
121	size_t writeback_size;
122	size_t freelist_high_watermark;
123	size_t freelist_low_watermark;
124	unsigned long max_age;
125	unsigned long pause;
126
127	unsigned int uncommitted_blocks;
128	unsigned int autocommit_blocks;
129	unsigned int max_writeback_jobs;
130
131	int error;
132
133	unsigned long autocommit_jiffies;
134	struct timer_list autocommit_timer;
135	struct wait_queue_head freelist_wait;
136
137	struct timer_list max_age_timer;
138
139	atomic_t bio_in_progress[2];
140	struct wait_queue_head bio_in_progress_wait[2];
141
142	struct dm_target *ti;
143	struct dm_dev *dev;
144	struct dm_dev *ssd_dev;
145	sector_t start_sector;
146	void *memory_map;
147	uint64_t memory_map_size;
148	size_t metadata_sectors;
149	size_t n_blocks;
150	uint64_t seq_count;
151	sector_t data_device_sectors;
152	void *block_start;
153	struct wc_entry *entries;
154	unsigned int block_size;
155	unsigned char block_size_bits;
156
157	bool pmem_mode:1;
158	bool writeback_fua:1;
159
160	bool overwrote_committed:1;
161	bool memory_vmapped:1;
162
163	bool start_sector_set:1;
164	bool high_wm_percent_set:1;
165	bool low_wm_percent_set:1;
166	bool max_writeback_jobs_set:1;
167	bool autocommit_blocks_set:1;
168	bool autocommit_time_set:1;
169	bool max_age_set:1;
170	bool writeback_fua_set:1;
171	bool flush_on_suspend:1;
172	bool cleaner:1;
173	bool cleaner_set:1;
174	bool metadata_only:1;
175	bool pause_set:1;
176
177	unsigned int high_wm_percent_value;
178	unsigned int low_wm_percent_value;
179	unsigned int autocommit_time_value;
180	unsigned int max_age_value;
181	unsigned int pause_value;
182
183	unsigned int writeback_all;
184	struct workqueue_struct *writeback_wq;
185	struct work_struct writeback_work;
186	struct work_struct flush_work;
187
188	struct dm_io_tracker iot;
189
190	struct dm_io_client *dm_io;
191
192	raw_spinlock_t endio_list_lock;
193	struct list_head endio_list;
194	struct task_struct *endio_thread;
195
196	struct task_struct *flush_thread;
197	struct bio_list flush_list;
198
199	struct dm_kcopyd_client *dm_kcopyd;
200	unsigned long *dirty_bitmap;
201	unsigned int dirty_bitmap_size;
202
203	struct bio_set bio_set;
204	mempool_t copy_pool;
205
206	struct {
207	unsigned long long reads;
208	unsigned long long read_hits;
209	unsigned long long writes;
210	unsigned long long write_hits_uncommitted;
211	unsigned long long write_hits_committed;
212	unsigned long long writes_around;
213	unsigned long long writes_allocate;
214	unsigned long long writes_blocked_on_freelist;
215	unsigned long long flushes;
216	unsigned long long discards;
217	} stats;
218	};
219
220	#define WB_LIST_INLINE 16
221
222	struct writeback_struct {
223	struct list_head endio_entry;
224	struct dm_writecache *wc;
225	struct wc_entry **wc_list;
226	unsigned int wc_list_n;
227	struct wc_entry *wc_list_inline[WB_LIST_INLINE];
228	struct bio bio;
229	};
230
231	struct copy_struct {
232	struct list_head endio_entry;
233	struct dm_writecache *wc;
234	struct wc_entry *e;
235	unsigned int n_entries;
236	int error;
237	};
238
239	DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(dm_writecache_throttle,
240	"A percentage of time allocated for data copying");
241
242	static void wc_lock(struct dm_writecache *wc)
243	{
244	mutex_lock(&wc->lock);
245	}
246
247	static void wc_unlock(struct dm_writecache *wc)
248	{
249	mutex_unlock(lock: &wc->lock);
250	}
251
252	#ifdef DM_WRITECACHE_HAS_PMEM
253	static int persistent_memory_claim(struct dm_writecache *wc)
254	{
255	int r;
256	loff_t s;
257	long p, da;
258	unsigned long pfn;
259	int id;
260	struct page **pages;
261	sector_t offset;
262
263	wc->memory_vmapped = false;
264
265	s = wc->memory_map_size;
266	p = s >> PAGE_SHIFT;
267	if (!p) {
268	r = -EINVAL;
269	goto err1;
270	}
271	if (p != s >> PAGE_SHIFT) {
272	r = -EOVERFLOW;
273	goto err1;
274	}
275
276	offset = get_start_sect(bdev: wc->ssd_dev->bdev);
277	if (offset & (PAGE_SIZE / 512 - 1)) {
278	r = -EINVAL;
279	goto err1;
280	}
281	offset >>= PAGE_SHIFT - 9;
282
283	id = dax_read_lock();
284
285	da = dax_direct_access(dax_dev: wc->ssd_dev->dax_dev, pgoff: offset, nr_pages: p, mode: DAX_ACCESS,
286	kaddr: &wc->memory_map, pfn: &pfn);
287	if (da < 0) {
288	wc->memory_map = NULL;
289	r = da;
290	goto err2;
291	}
292	if (!pfn_valid(pfn)) {
293	wc->memory_map = NULL;
294	r = -EOPNOTSUPP;
295	goto err2;
296	}
297	if (da != p) {
298	long i;
299
300	wc->memory_map = NULL;
301	pages = vmalloc_array(p, sizeof(struct page *));
302	if (!pages) {
303	r = -ENOMEM;
304	goto err2;
305	}
306	i = 0;
307	do {
308	long daa;
309
310	daa = dax_direct_access(dax_dev: wc->ssd_dev->dax_dev, pgoff: offset + i,
311	nr_pages: p - i, mode: DAX_ACCESS, NULL, pfn: &pfn);
312	if (daa <= 0) {
313	r = daa ? daa : -EINVAL;
314	goto err3;
315	}
316	if (!pfn_valid(pfn)) {
317	r = -EOPNOTSUPP;
318	goto err3;
319	}
320	while (daa-- && i < p) {
321	pages[i++] = pfn_to_page(pfn);
322	pfn++;
323	if (!(i & 15))
324	cond_resched();
325	}
326	} while (i < p);
327	wc->memory_map = vmap(pages, count: p, VM_MAP, PAGE_KERNEL);
328	if (!wc->memory_map) {
329	r = -ENOMEM;
330	goto err3;
331	}
332	vfree(addr: pages);
333	wc->memory_vmapped = true;
334	}
335
336	dax_read_unlock(id);
337
338	wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT;
339	wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT;
340
341	return 0;
342	err3:
343	vfree(addr: pages);
344	err2:
345	dax_read_unlock(id);
346	err1:
347	return r;
348	}
349	#else
350	static int persistent_memory_claim(struct dm_writecache *wc)
351	{
352	return -EOPNOTSUPP;
353	}
354	#endif
355
356	static void persistent_memory_release(struct dm_writecache *wc)
357	{
358	if (wc->memory_vmapped)
359	vunmap(addr: wc->memory_map - ((size_t)wc->start_sector << SECTOR_SHIFT));
360	}
361
362	static struct page *persistent_memory_page(void *addr)
363	{
364	if (is_vmalloc_addr(x: addr))
365	return vmalloc_to_page(addr);
366	else
367	return virt_to_page(addr);
368	}
369
370	static unsigned int persistent_memory_page_offset(void *addr)
371	{
372	return (unsigned long)addr & (PAGE_SIZE - 1);
373	}
374
375	static void persistent_memory_flush_cache(void *ptr, size_t size)
376	{
377	if (is_vmalloc_addr(x: ptr))
378	flush_kernel_vmap_range(vaddr: ptr, size);
379	}
380
381	static void persistent_memory_invalidate_cache(void *ptr, size_t size)
382	{
383	if (is_vmalloc_addr(x: ptr))
384	invalidate_kernel_vmap_range(vaddr: ptr, size);
385	}
386
387	static struct wc_memory_superblock *sb(struct dm_writecache *wc)
388	{
389	return wc->memory_map;
390	}
391
392	static struct wc_memory_entry *memory_entry(struct dm_writecache *wc, struct wc_entry *e)
393	{
394	return &sb(wc)->entries[e->index];
395	}
396
397	static void *memory_data(struct dm_writecache *wc, struct wc_entry *e)
398	{
399	return (char *)wc->block_start + (e->index << wc->block_size_bits);
400	}
401
402	static sector_t cache_sector(struct dm_writecache *wc, struct wc_entry *e)
403	{
404	return wc->start_sector + wc->metadata_sectors +
405	((sector_t)e->index << (wc->block_size_bits - SECTOR_SHIFT));
406	}
407
408	static uint64_t read_original_sector(struct dm_writecache *wc, struct wc_entry *e)
409	{
410	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
411	return e->original_sector;
412	#else
413	return le64_to_cpu(memory_entry(wc, e)->original_sector);
414	#endif
415	}
416
417	static uint64_t read_seq_count(struct dm_writecache *wc, struct wc_entry *e)
418	{
419	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
420	return e->seq_count;
421	#else
422	return le64_to_cpu(memory_entry(wc, e)->seq_count);
423	#endif
424	}
425
426	static void clear_seq_count(struct dm_writecache *wc, struct wc_entry *e)
427	{
428	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
429	e->seq_count = -1;
430	#endif
431	pmem_assign(memory_entry(wc, e)->seq_count, cpu_to_le64(-1));
432	}
433
434	static void write_original_sector_seq_count(struct dm_writecache *wc, struct wc_entry *e,
435	uint64_t original_sector, uint64_t seq_count)
436	{
437	struct wc_memory_entry me;
438	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
439	e->original_sector = original_sector;
440	e->seq_count = seq_count;
441	#endif
442	me.original_sector = cpu_to_le64(original_sector);
443	me.seq_count = cpu_to_le64(seq_count);
444	pmem_assign(*memory_entry(wc, e), me);
445	}
446
447	#define writecache_error(wc, err, msg, arg...) \
448	do { \
449	if (!cmpxchg(&(wc)->error, 0, err)) \
450	DMERR(msg, ##arg); \
451	wake_up(&(wc)->freelist_wait); \
452	} while (0)
453
454	#define writecache_has_error(wc) (unlikely(READ_ONCE((wc)->error)))
455
456	static void writecache_flush_all_metadata(struct dm_writecache *wc)
457	{
458	if (!WC_MODE_PMEM(wc))
459	memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
460	}
461
462	static void writecache_flush_region(struct dm_writecache *wc, void *ptr, size_t size)
463	{
464	if (!WC_MODE_PMEM(wc))
465	__set_bit(((char *)ptr - (char *)wc->memory_map) / BITMAP_GRANULARITY,
466	wc->dirty_bitmap);
467	}
468
469	static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev);
470
471	struct io_notify {
472	struct dm_writecache *wc;
473	struct completion c;
474	atomic_t count;
475	};
476
477	static void writecache_notify_io(unsigned long error, void *context)
478	{
479	struct io_notify *endio = context;
480
481	if (unlikely(error != 0))
482	writecache_error(endio->wc, -EIO, "error writing metadata");
483	BUG_ON(atomic_read(&endio->count) <= 0);
484	if (atomic_dec_and_test(v: &endio->count))
485	complete(&endio->c);
486	}
487
488	static void writecache_wait_for_ios(struct dm_writecache *wc, int direction)
489	{
490	wait_event(wc->bio_in_progress_wait[direction],
491	!atomic_read(&wc->bio_in_progress[direction]));
492	}
493
494	static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
495	{
496	struct dm_io_region region;
497	struct dm_io_request req;
498	struct io_notify endio = {
499	wc,
500	COMPLETION_INITIALIZER_ONSTACK(endio.c),
501	ATOMIC_INIT(1),
502	};
503	unsigned int bitmap_bits = wc->dirty_bitmap_size * 8;
504	unsigned int i = 0;
505
506	while (1) {
507	unsigned int j;
508
509	i = find_next_bit(addr: wc->dirty_bitmap, size: bitmap_bits, offset: i);
510	if (unlikely(i == bitmap_bits))
511	break;
512	j = find_next_zero_bit(addr: wc->dirty_bitmap, size: bitmap_bits, offset: i);
513
514	region.bdev = wc->ssd_dev->bdev;
515	region.sector = (sector_t)i * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
516	region.count = (sector_t)(j - i) * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
517
518	if (unlikely(region.sector >= wc->metadata_sectors))
519	break;
520	if (unlikely(region.sector + region.count > wc->metadata_sectors))
521	region.count = wc->metadata_sectors - region.sector;
522
523	region.sector += wc->start_sector;
524	atomic_inc(v: &endio.count);
525	req.bi_opf = REQ_OP_WRITE | REQ_SYNC;
526	req.mem.type = DM_IO_VMA;
527	req.mem.ptr.vma = (char *)wc->memory_map + (size_t)i * BITMAP_GRANULARITY;
528	req.client = wc->dm_io;
529	req.notify.fn = writecache_notify_io;
530	req.notify.context = &endio;
531
532	/* writing via async dm-io (implied by notify.fn above) won't return an error */
533	(void) dm_io(io_req: &req, num_regions: 1, region: &region, NULL, IOPRIO_DEFAULT);
534	i = j;
535	}
536
537	writecache_notify_io(error: 0, context: &endio);
538	wait_for_completion_io(&endio.c);
539
540	if (wait_for_ios)
541	writecache_wait_for_ios(wc, WRITE);
542
543	writecache_disk_flush(wc, dev: wc->ssd_dev);
544
545	memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size);
546	}
547
548	static void ssd_commit_superblock(struct dm_writecache *wc)
549	{
550	int r;
551	struct dm_io_region region;
552	struct dm_io_request req;
553
554	region.bdev = wc->ssd_dev->bdev;
555	region.sector = 0;
556	region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT;
557
558	if (unlikely(region.sector + region.count > wc->metadata_sectors))
559	region.count = wc->metadata_sectors - region.sector;
560
561	region.sector += wc->start_sector;
562
563	req.bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_FUA;
564	req.mem.type = DM_IO_VMA;
565	req.mem.ptr.vma = (char *)wc->memory_map;
566	req.client = wc->dm_io;
567	req.notify.fn = NULL;
568	req.notify.context = NULL;
569
570	r = dm_io(io_req: &req, num_regions: 1, region: &region, NULL, IOPRIO_DEFAULT);
571	if (unlikely(r))
572	writecache_error(wc, r, "error writing superblock");
573	}
574
575	static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
576	{
577	if (WC_MODE_PMEM(wc))
578	pmem_wmb();
579	else
580	ssd_commit_flushed(wc, wait_for_ios);
581	}
582
583	static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev)
584	{
585	int r;
586	struct dm_io_region region;
587	struct dm_io_request req;
588
589	region.bdev = dev->bdev;
590	region.sector = 0;
591	region.count = 0;
592	req.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
593	req.mem.type = DM_IO_KMEM;
594	req.mem.ptr.addr = NULL;
595	req.client = wc->dm_io;
596	req.notify.fn = NULL;
597
598	r = dm_io(io_req: &req, num_regions: 1, region: &region, NULL, IOPRIO_DEFAULT);
599	if (unlikely(r))
600	writecache_error(wc, r, "error flushing metadata: %d", r);
601	}
602
603	#define WFE_RETURN_FOLLOWING 1
604	#define WFE_LOWEST_SEQ 2
605
606	static struct wc_entry *writecache_find_entry(struct dm_writecache *wc,
607	uint64_t block, int flags)
608	{
609	struct wc_entry *e;
610	struct rb_node *node = wc->tree.rb_node;
611
612	if (unlikely(!node))
613	return NULL;
614
615	while (1) {
616	e = container_of(node, struct wc_entry, rb_node);
617	if (read_original_sector(wc, e) == block)
618	break;
619
620	node = (read_original_sector(wc, e) >= block ?
621	e->rb_node.rb_left : e->rb_node.rb_right);
622	if (unlikely(!node)) {
623	if (!(flags & WFE_RETURN_FOLLOWING))
624	return NULL;
625	if (read_original_sector(wc, e) >= block)
626	return e;
627
628	node = rb_next(&e->rb_node);
629	if (unlikely(!node))
630	return NULL;
631
632	e = container_of(node, struct wc_entry, rb_node);
633	return e;
634	}
635	}
636
637	while (1) {
638	struct wc_entry *e2;
639
640	if (flags & WFE_LOWEST_SEQ)
641	node = rb_prev(&e->rb_node);
642	else
643	node = rb_next(&e->rb_node);
644	if (unlikely(!node))
645	return e;
646	e2 = container_of(node, struct wc_entry, rb_node);
647	if (read_original_sector(wc, e: e2) != block)
648	return e;
649	e = e2;
650	}
651	}
652
653	static void writecache_insert_entry(struct dm_writecache *wc, struct wc_entry *ins)
654	{
655	struct wc_entry *e;
656	struct rb_node **node = &wc->tree.rb_node, *parent = NULL;
657
658	while (*node) {
659	e = container_of(*node, struct wc_entry, rb_node);
660	parent = &e->rb_node;
661	if (read_original_sector(wc, e) > read_original_sector(wc, e: ins))
662	node = &parent->rb_left;
663	else
664	node = &parent->rb_right;
665	}
666	rb_link_node(node: &ins->rb_node, parent, rb_link: node);
667	rb_insert_color(&ins->rb_node, &wc->tree);
668	list_add(new: &ins->lru, head: &wc->lru);
669	ins->age = jiffies;
670	}
671
672	static void writecache_unlink(struct dm_writecache *wc, struct wc_entry *e)
673	{
674	list_del(entry: &e->lru);
675	rb_erase(&e->rb_node, &wc->tree);
676	}
677
678	static void writecache_add_to_freelist(struct dm_writecache *wc, struct wc_entry *e)
679	{
680	if (WC_MODE_SORT_FREELIST(wc)) {
681	struct rb_node **node = &wc->freetree.rb_node, *parent = NULL;
682
683	if (unlikely(!*node))
684	wc->current_free = e;
685	while (*node) {
686	parent = *node;
687	if (&e->rb_node < *node)
688	node = &parent->rb_left;
689	else
690	node = &parent->rb_right;
691	}
692	rb_link_node(node: &e->rb_node, parent, rb_link: node);
693	rb_insert_color(&e->rb_node, &wc->freetree);
694	} else {
695	list_add_tail(new: &e->lru, head: &wc->freelist);
696	}
697	wc->freelist_size++;
698	}
699
700	static inline void writecache_verify_watermark(struct dm_writecache *wc)
701	{
702	if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
703	queue_work(wq: wc->writeback_wq, work: &wc->writeback_work);
704	}
705
706	static void writecache_max_age_timer(struct timer_list *t)
707	{
708	struct dm_writecache *wc = timer_container_of(wc, t, max_age_timer);
709
710	if (!dm_suspended(ti: wc->ti) && !writecache_has_error(wc)) {
711	queue_work(wq: wc->writeback_wq, work: &wc->writeback_work);
712	mod_timer(timer: &wc->max_age_timer, expires: jiffies + wc->max_age / MAX_AGE_DIV);
713	}
714	}
715
716	static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc, sector_t expected_sector)
717	{
718	struct wc_entry *e;
719
720	if (WC_MODE_SORT_FREELIST(wc)) {
721	struct rb_node *next;
722
723	if (unlikely(!wc->current_free))
724	return NULL;
725	e = wc->current_free;
726	if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
727	return NULL;
728	next = rb_next(&e->rb_node);
729	rb_erase(&e->rb_node, &wc->freetree);
730	if (unlikely(!next))
731	next = rb_first(root: &wc->freetree);
732	wc->current_free = next ? container_of(next, struct wc_entry, rb_node) : NULL;
733	} else {
734	if (unlikely(list_empty(&wc->freelist)))
735	return NULL;
736	e = container_of(wc->freelist.next, struct wc_entry, lru);
737	if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
738	return NULL;
739	list_del(entry: &e->lru);
740	}
741	wc->freelist_size--;
742
743	writecache_verify_watermark(wc);
744
745	return e;
746	}
747
748	static void writecache_free_entry(struct dm_writecache *wc, struct wc_entry *e)
749	{
750	writecache_unlink(wc, e);
751	writecache_add_to_freelist(wc, e);
752	clear_seq_count(wc, e);
753	writecache_flush_region(wc, ptr: memory_entry(wc, e), size: sizeof(struct wc_memory_entry));
754	if (unlikely(waitqueue_active(&wc->freelist_wait)))
755	wake_up(&wc->freelist_wait);
756	}
757
758	static void writecache_wait_on_freelist(struct dm_writecache *wc)
759	{
760	DEFINE_WAIT(wait);
761
762	prepare_to_wait(wq_head: &wc->freelist_wait, wq_entry: &wait, TASK_UNINTERRUPTIBLE);
763	wc_unlock(wc);
764	io_schedule();
765	finish_wait(wq_head: &wc->freelist_wait, wq_entry: &wait);
766	wc_lock(wc);
767	}
768
769	static void writecache_poison_lists(struct dm_writecache *wc)
770	{
771	/*
772	* Catch incorrect access to these values while the device is suspended.
773	*/
774	memset(&wc->tree, -1, sizeof(wc->tree));
775	wc->lru.next = LIST_POISON1;
776	wc->lru.prev = LIST_POISON2;
777	wc->freelist.next = LIST_POISON1;
778	wc->freelist.prev = LIST_POISON2;
779	}
780
781	static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
782	{
783	writecache_flush_region(wc, ptr: memory_entry(wc, e), size: sizeof(struct wc_memory_entry));
784	if (WC_MODE_PMEM(wc))
785	writecache_flush_region(wc, ptr: memory_data(wc, e), size: wc->block_size);
786	}
787
788	static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
789	{
790	return read_seq_count(wc, e) < wc->seq_count;
791	}
792
793	static void writecache_flush(struct dm_writecache *wc)
794	{
795	struct wc_entry *e, *e2;
796	bool need_flush_after_free;
797
798	wc->uncommitted_blocks = 0;
799	timer_delete(timer: &wc->autocommit_timer);
800
801	if (list_empty(head: &wc->lru))
802	return;
803
804	e = container_of(wc->lru.next, struct wc_entry, lru);
805	if (writecache_entry_is_committed(wc, e)) {
806	if (wc->overwrote_committed) {
807	writecache_wait_for_ios(wc, WRITE);
808	writecache_disk_flush(wc, dev: wc->ssd_dev);
809	wc->overwrote_committed = false;
810	}
811	return;
812	}
813	while (1) {
814	writecache_flush_entry(wc, e);
815	if (unlikely(e->lru.next == &wc->lru))
816	break;
817	e2 = container_of(e->lru.next, struct wc_entry, lru);
818	if (writecache_entry_is_committed(wc, e: e2))
819	break;
820	e = e2;
821	cond_resched();
822	}
823	writecache_commit_flushed(wc, wait_for_ios: true);
824
825	wc->seq_count++;
826	pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
827	if (WC_MODE_PMEM(wc))
828	writecache_commit_flushed(wc, wait_for_ios: false);
829	else
830	ssd_commit_superblock(wc);
831
832	wc->overwrote_committed = false;
833
834	need_flush_after_free = false;
835	while (1) {
836	/* Free another committed entry with lower seq-count */
837	struct rb_node *rb_node = rb_prev(&e->rb_node);
838
839	if (rb_node) {
840	e2 = container_of(rb_node, struct wc_entry, rb_node);
841	if (read_original_sector(wc, e: e2) == read_original_sector(wc, e) &&
842	likely(!e2->write_in_progress)) {
843	writecache_free_entry(wc, e: e2);
844	need_flush_after_free = true;
845	}
846	}
847	if (unlikely(e->lru.prev == &wc->lru))
848	break;
849	e = container_of(e->lru.prev, struct wc_entry, lru);
850	cond_resched();
851	}
852
853	if (need_flush_after_free)
854	writecache_commit_flushed(wc, wait_for_ios: false);
855	}
856
857	static void writecache_flush_work(struct work_struct *work)
858	{
859	struct dm_writecache *wc = container_of(work, struct dm_writecache, flush_work);
860
861	wc_lock(wc);
862	writecache_flush(wc);
863	wc_unlock(wc);
864	}
865
866	static void writecache_autocommit_timer(struct timer_list *t)
867	{
868	struct dm_writecache *wc = timer_container_of(wc, t, autocommit_timer);
869
870	if (!writecache_has_error(wc))
871	queue_work(wq: wc->writeback_wq, work: &wc->flush_work);
872	}
873
874	static void writecache_schedule_autocommit(struct dm_writecache *wc)
875	{
876	if (!timer_pending(timer: &wc->autocommit_timer))
877	mod_timer(timer: &wc->autocommit_timer, expires: jiffies + wc->autocommit_jiffies);
878	}
879
880	static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_t end)
881	{
882	struct wc_entry *e;
883	bool discarded_something = false;
884
885	e = writecache_find_entry(wc, block: start, WFE_RETURN_FOLLOWING | WFE_LOWEST_SEQ);
886	if (unlikely(!e))
887	return;
888
889	while (read_original_sector(wc, e) < end) {
890	struct rb_node *node = rb_next(&e->rb_node);
891
892	if (likely(!e->write_in_progress)) {
893	if (!discarded_something) {
894	if (!WC_MODE_PMEM(wc)) {
895	writecache_wait_for_ios(wc, READ);
896	writecache_wait_for_ios(wc, WRITE);
897	}
898	discarded_something = true;
899	}
900	if (!writecache_entry_is_committed(wc, e))
901	wc->uncommitted_blocks--;
902	writecache_free_entry(wc, e);
903	}
904
905	if (unlikely(!node))
906	break;
907
908	e = container_of(node, struct wc_entry, rb_node);
909	}
910
911	if (discarded_something)
912	writecache_commit_flushed(wc, wait_for_ios: false);
913	}
914
915	static bool writecache_wait_for_writeback(struct dm_writecache *wc)
916	{
917	if (wc->writeback_size) {
918	writecache_wait_on_freelist(wc);
919	return true;
920	}
921	return false;
922	}
923
924	static void writecache_suspend(struct dm_target *ti)
925	{
926	struct dm_writecache *wc = ti->private;
927	bool flush_on_suspend;
928
929	timer_delete_sync(timer: &wc->autocommit_timer);
930	timer_delete_sync(timer: &wc->max_age_timer);
931
932	wc_lock(wc);
933	writecache_flush(wc);
934	flush_on_suspend = wc->flush_on_suspend;
935	if (flush_on_suspend) {
936	wc->flush_on_suspend = false;
937	wc->writeback_all++;
938	queue_work(wq: wc->writeback_wq, work: &wc->writeback_work);
939	}
940	wc_unlock(wc);
941
942	drain_workqueue(wq: wc->writeback_wq);
943
944	wc_lock(wc);
945	if (flush_on_suspend)
946	wc->writeback_all--;
947	while (writecache_wait_for_writeback(wc))
948	;
949
950	if (WC_MODE_PMEM(wc))
951	persistent_memory_flush_cache(ptr: wc->memory_map, size: wc->memory_map_size);
952
953	writecache_poison_lists(wc);
954
955	wc_unlock(wc);
956	}
957
958	static int writecache_alloc_entries(struct dm_writecache *wc)
959	{
960	size_t b;
961
962	if (wc->entries)
963	return 0;
964	wc->entries = vmalloc_array(wc->n_blocks, sizeof(struct wc_entry));
965	if (!wc->entries)
966	return -ENOMEM;
967	for (b = 0; b < wc->n_blocks; b++) {
968	struct wc_entry *e = &wc->entries[b];
969
970	e->index = b;
971	e->write_in_progress = false;
972	cond_resched();
973	}
974
975	return 0;
976	}
977
978	static int writecache_read_metadata(struct dm_writecache *wc, sector_t n_sectors)
979	{
980	struct dm_io_region region;
981	struct dm_io_request req;
982
983	region.bdev = wc->ssd_dev->bdev;
984	region.sector = wc->start_sector;
985	region.count = n_sectors;
986	req.bi_opf = REQ_OP_READ | REQ_SYNC;
987	req.mem.type = DM_IO_VMA;
988	req.mem.ptr.vma = (char *)wc->memory_map;
989	req.client = wc->dm_io;
990	req.notify.fn = NULL;
991
992	return dm_io(io_req: &req, num_regions: 1, region: &region, NULL, IOPRIO_DEFAULT);
993	}
994
995	static void writecache_resume(struct dm_target *ti)
996	{
997	struct dm_writecache *wc = ti->private;
998	size_t b;
999	bool need_flush = false;
1000	__le64 sb_seq_count;
1001	int r;
1002
1003	wc_lock(wc);
1004
1005	wc->data_device_sectors = bdev_nr_sectors(bdev: wc->dev->bdev);
1006
1007	if (WC_MODE_PMEM(wc)) {
1008	persistent_memory_invalidate_cache(ptr: wc->memory_map, size: wc->memory_map_size);
1009	} else {
1010	r = writecache_read_metadata(wc, n_sectors: wc->metadata_sectors);
1011	if (r) {
1012	size_t sb_entries_offset;
1013
1014	writecache_error(wc, r, "unable to read metadata: %d", r);
1015	sb_entries_offset = offsetof(struct wc_memory_superblock, entries);
1016	memset((char *)wc->memory_map + sb_entries_offset, -1,
1017	(wc->metadata_sectors << SECTOR_SHIFT) - sb_entries_offset);
1018	}
1019	}
1020
1021	wc->tree = RB_ROOT;
1022	INIT_LIST_HEAD(list: &wc->lru);
1023	if (WC_MODE_SORT_FREELIST(wc)) {
1024	wc->freetree = RB_ROOT;
1025	wc->current_free = NULL;
1026	} else {
1027	INIT_LIST_HEAD(list: &wc->freelist);
1028	}
1029	wc->freelist_size = 0;
1030
1031	r = copy_mc_to_kernel(to: &sb_seq_count, from: &sb(wc)->seq_count,
1032	len: sizeof(uint64_t));
1033	if (r) {
1034	writecache_error(wc, r, "hardware memory error when reading superblock: %d", r);
1035	sb_seq_count = cpu_to_le64(0);
1036	}
1037	wc->seq_count = le64_to_cpu(sb_seq_count);
1038
1039	#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
1040	for (b = 0; b < wc->n_blocks; b++) {
1041	struct wc_entry *e = &wc->entries[b];
1042	struct wc_memory_entry wme;
1043
1044	if (writecache_has_error(wc)) {
1045	e->original_sector = -1;
1046	e->seq_count = -1;
1047	continue;
1048	}
1049	r = copy_mc_to_kernel(to: &wme, from: memory_entry(wc, e),
1050	len: sizeof(struct wc_memory_entry));
1051	if (r) {
1052	writecache_error(wc, r, "hardware memory error when reading metadata entry %lu: %d",
1053	(unsigned long)b, r);
1054	e->original_sector = -1;
1055	e->seq_count = -1;
1056	} else {
1057	e->original_sector = le64_to_cpu(wme.original_sector);
1058	e->seq_count = le64_to_cpu(wme.seq_count);
1059	}
1060	cond_resched();
1061	}
1062	#endif
1063	for (b = 0; b < wc->n_blocks; b++) {
1064	struct wc_entry *e = &wc->entries[b];
1065
1066	if (!writecache_entry_is_committed(wc, e)) {
1067	if (read_seq_count(wc, e) != -1) {
1068	erase_this:
1069	clear_seq_count(wc, e);
1070	need_flush = true;
1071	}
1072	writecache_add_to_freelist(wc, e);
1073	} else {
1074	struct wc_entry *old;
1075
1076	old = writecache_find_entry(wc, block: read_original_sector(wc, e), flags: 0);
1077	if (!old) {
1078	writecache_insert_entry(wc, ins: e);
1079	} else {
1080	if (read_seq_count(wc, e: old) == read_seq_count(wc, e)) {
1081	writecache_error(wc, -EINVAL,
1082	"two identical entries, position %llu, sector %llu, sequence %llu",
1083	(unsigned long long)b, (unsigned long long)read_original_sector(wc, e),
1084	(unsigned long long)read_seq_count(wc, e));
1085	}
1086	if (read_seq_count(wc, e: old) > read_seq_count(wc, e)) {
1087	goto erase_this;
1088	} else {
1089	writecache_free_entry(wc, e: old);
1090	writecache_insert_entry(wc, ins: e);
1091	need_flush = true;
1092	}
1093	}
1094	}
1095	cond_resched();
1096	}
1097
1098	if (need_flush) {
1099	writecache_flush_all_metadata(wc);
1100	writecache_commit_flushed(wc, wait_for_ios: false);
1101	}
1102
1103	writecache_verify_watermark(wc);
1104
1105	if (wc->max_age != MAX_AGE_UNSPECIFIED)
1106	mod_timer(timer: &wc->max_age_timer, expires: jiffies + wc->max_age / MAX_AGE_DIV);
1107
1108	wc_unlock(wc);
1109	}
1110
1111	static int process_flush_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1112	{
1113	if (argc != 1)
1114	return -EINVAL;
1115
1116	wc_lock(wc);
1117	if (dm_suspended(ti: wc->ti)) {
1118	wc_unlock(wc);
1119	return -EBUSY;
1120	}
1121	if (writecache_has_error(wc)) {
1122	wc_unlock(wc);
1123	return -EIO;
1124	}
1125
1126	writecache_flush(wc);
1127	wc->writeback_all++;
1128	queue_work(wq: wc->writeback_wq, work: &wc->writeback_work);
1129	wc_unlock(wc);
1130
1131	flush_workqueue(wc->writeback_wq);
1132
1133	wc_lock(wc);
1134	wc->writeback_all--;
1135	if (writecache_has_error(wc)) {
1136	wc_unlock(wc);
1137	return -EIO;
1138	}
1139	wc_unlock(wc);
1140
1141	return 0;
1142	}
1143
1144	static int process_flush_on_suspend_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1145	{
1146	if (argc != 1)
1147	return -EINVAL;
1148
1149	wc_lock(wc);
1150	wc->flush_on_suspend = true;
1151	wc_unlock(wc);
1152
1153	return 0;
1154	}
1155
1156	static void activate_cleaner(struct dm_writecache *wc)
1157	{
1158	wc->flush_on_suspend = true;
1159	wc->cleaner = true;
1160	wc->freelist_high_watermark = wc->n_blocks;
1161	wc->freelist_low_watermark = wc->n_blocks;
1162	}
1163
1164	static int process_cleaner_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1165	{
1166	if (argc != 1)
1167	return -EINVAL;
1168
1169	wc_lock(wc);
1170	activate_cleaner(wc);
1171	if (!dm_suspended(ti: wc->ti))
1172	writecache_verify_watermark(wc);
1173	wc_unlock(wc);
1174
1175	return 0;
1176	}
1177
1178	static int process_clear_stats_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1179	{
1180	if (argc != 1)
1181	return -EINVAL;
1182
1183	wc_lock(wc);
1184	memset(&wc->stats, 0, sizeof(wc->stats));
1185	wc_unlock(wc);
1186
1187	return 0;
1188	}
1189
1190	static int writecache_message(struct dm_target *ti, unsigned int argc, char **argv,
1191	char *result, unsigned int maxlen)
1192	{
1193	int r = -EINVAL;
1194	struct dm_writecache *wc = ti->private;
1195
1196	if (!strcasecmp(s1: argv[0], s2: "flush"))
1197	r = process_flush_mesg(argc, argv, wc);
1198	else if (!strcasecmp(s1: argv[0], s2: "flush_on_suspend"))
1199	r = process_flush_on_suspend_mesg(argc, argv, wc);
1200	else if (!strcasecmp(s1: argv[0], s2: "cleaner"))
1201	r = process_cleaner_mesg(argc, argv, wc);
1202	else if (!strcasecmp(s1: argv[0], s2: "clear_stats"))
1203	r = process_clear_stats_mesg(argc, argv, wc);
1204	else
1205	DMERR("unrecognised message received: %s", argv[0]);
1206
1207	return r;
1208	}
1209
1210	static void memcpy_flushcache_optimized(void *dest, void *source, size_t size)
1211	{
1212	/*
1213	* clflushopt performs better with block size 1024, 2048, 4096
1214	* non-temporal stores perform better with block size 512
1215	*
1216	* block size 512 1024 2048 4096
1217	* movnti 496 MB/s 642 MB/s 725 MB/s 744 MB/s
1218	* clflushopt 373 MB/s 688 MB/s 1.1 GB/s 1.2 GB/s
1219	*
1220	* We see that movnti performs better for 512-byte blocks, and
1221	* clflushopt performs better for 1024-byte and larger blocks. So, we
1222	* prefer clflushopt for sizes >= 768.
1223	*
1224	* NOTE: this happens to be the case now (with dm-writecache's single
1225	* threaded model) but re-evaluate this once memcpy_flushcache() is
1226	* enabled to use movdir64b which might invalidate this performance
1227	* advantage seen with cache-allocating-writes plus flushing.
1228	*/
1229	#ifdef CONFIG_X86
1230	if (static_cpu_has(X86_FEATURE_CLFLUSHOPT) &&
1231	likely(boot_cpu_data.x86_clflush_size == 64) &&
1232	likely(size >= 768)) {
1233	do {
1234	memcpy((void *)dest, (void *)source, 64);
1235	clflushopt(p: (void *)dest);
1236	dest += 64;
1237	source += 64;
1238	size -= 64;
1239	} while (size >= 64);
1240	return;
1241	}
1242	#endif
1243	memcpy_flushcache(dst: dest, src: source, cnt: size);
1244	}
1245
1246	static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data)
1247	{
1248	void *buf;
1249	unsigned int size;
1250	int rw = bio_data_dir(bio);
1251	unsigned int remaining_size = wc->block_size;
1252
1253	do {
1254	struct bio_vec bv = bio_iter_iovec(bio, bio->bi_iter);
1255
1256	buf = bvec_kmap_local(bvec: &bv);
1257	size = bv.bv_len;
1258	if (unlikely(size > remaining_size))
1259	size = remaining_size;
1260
1261	if (rw == READ) {
1262	int r;
1263
1264	r = copy_mc_to_kernel(to: buf, from: data, len: size);
1265	flush_dcache_page(bio_page(bio));
1266	if (unlikely(r)) {
1267	writecache_error(wc, r, "hardware memory error when reading data: %d", r);
1268	bio->bi_status = BLK_STS_IOERR;
1269	}
1270	} else {
1271	flush_dcache_page(bio_page(bio));
1272	memcpy_flushcache_optimized(dest: data, source: buf, size);
1273	}
1274
1275	kunmap_local(buf);
1276
1277	data = (char *)data + size;
1278	remaining_size -= size;
1279	bio_advance(bio, nbytes: size);
1280	} while (unlikely(remaining_size));
1281	}
1282
1283	static int writecache_flush_thread(void *data)
1284	{
1285	struct dm_writecache *wc = data;
1286
1287	while (1) {
1288	struct bio *bio;
1289
1290	wc_lock(wc);
1291	bio = bio_list_pop(bl: &wc->flush_list);
1292	if (!bio) {
1293	set_current_state(TASK_INTERRUPTIBLE);
1294	wc_unlock(wc);
1295
1296	if (unlikely(kthread_should_stop())) {
1297	set_current_state(TASK_RUNNING);
1298	break;
1299	}
1300
1301	schedule();
1302	continue;
1303	}
1304
1305	if (bio_op(bio) == REQ_OP_DISCARD) {
1306	writecache_discard(wc, start: bio->bi_iter.bi_sector,
1307	bio_end_sector(bio));
1308	wc_unlock(wc);
1309	bio_set_dev(bio, bdev: wc->dev->bdev);
1310	submit_bio_noacct(bio);
1311	} else {
1312	writecache_flush(wc);
1313	wc_unlock(wc);
1314	if (writecache_has_error(wc))
1315	bio->bi_status = BLK_STS_IOERR;
1316	bio_endio(bio);
1317	}
1318	}
1319
1320	return 0;
1321	}
1322
1323	static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
1324	{
1325	if (bio_list_empty(bl: &wc->flush_list))
1326	wake_up_process(tsk: wc->flush_thread);
1327	bio_list_add(bl: &wc->flush_list, bio);
1328	}
1329
1330	enum wc_map_op {
1331	WC_MAP_SUBMIT,
1332	WC_MAP_REMAP,
1333	WC_MAP_REMAP_ORIGIN,
1334	WC_MAP_RETURN,
1335	WC_MAP_ERROR,
1336	};
1337
1338	static void writecache_map_remap_origin(struct dm_writecache *wc, struct bio *bio,
1339	struct wc_entry *e)
1340	{
1341	if (e) {
1342	sector_t next_boundary =
1343	read_original_sector(wc, e) - bio->bi_iter.bi_sector;
1344	if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT)
1345	dm_accept_partial_bio(bio, n_sectors: next_boundary);
1346	}
1347	}
1348
1349	static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *bio)
1350	{
1351	enum wc_map_op map_op;
1352	struct wc_entry *e;
1353
1354	read_next_block:
1355	wc->stats.reads++;
1356	e = writecache_find_entry(wc, block: bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1357	if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
1358	wc->stats.read_hits++;
1359	if (WC_MODE_PMEM(wc)) {
1360	bio_copy_block(wc, bio, data: memory_data(wc, e));
1361	if (bio->bi_iter.bi_size)
1362	goto read_next_block;
1363	map_op = WC_MAP_SUBMIT;
1364	} else {
1365	dm_accept_partial_bio(bio, n_sectors: wc->block_size >> SECTOR_SHIFT);
1366	bio_set_dev(bio, bdev: wc->ssd_dev->bdev);
1367	bio->bi_iter.bi_sector = cache_sector(wc, e);
1368	if (!writecache_entry_is_committed(wc, e))
1369	writecache_wait_for_ios(wc, WRITE);
1370	map_op = WC_MAP_REMAP;
1371	}
1372	} else {
1373	writecache_map_remap_origin(wc, bio, e);
1374	wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1375	map_op = WC_MAP_REMAP_ORIGIN;
1376	}
1377
1378	return map_op;
1379	}
1380
1381	static void writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
1382	struct wc_entry *e, bool search_used)
1383	{
1384	unsigned int bio_size = wc->block_size;
1385	sector_t start_cache_sec = cache_sector(wc, e);
1386	sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
1387
1388	while (bio_size < bio->bi_iter.bi_size) {
1389	if (!search_used) {
1390	struct wc_entry *f = writecache_pop_from_freelist(wc, expected_sector: current_cache_sec);
1391
1392	if (!f)
1393	break;
1394	write_original_sector_seq_count(wc, e: f, original_sector: bio->bi_iter.bi_sector +
1395	(bio_size >> SECTOR_SHIFT), seq_count: wc->seq_count);
1396	writecache_insert_entry(wc, ins: f);
1397	wc->uncommitted_blocks++;
1398	} else {
1399	struct wc_entry *f;
1400	struct rb_node *next = rb_next(&e->rb_node);
1401
1402	if (!next)
1403	break;
1404	f = container_of(next, struct wc_entry, rb_node);
1405	if (f != e + 1)
1406	break;
1407	if (read_original_sector(wc, e: f) !=
1408	read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1409	break;
1410	if (unlikely(f->write_in_progress))
1411	break;
1412	if (writecache_entry_is_committed(wc, e: f))
1413	wc->overwrote_committed = true;
1414	e = f;
1415	}
1416	bio_size += wc->block_size;
1417	current_cache_sec += wc->block_size >> SECTOR_SHIFT;
1418	}
1419
1420	bio_set_dev(bio, bdev: wc->ssd_dev->bdev);
1421	bio->bi_iter.bi_sector = start_cache_sec;
1422	dm_accept_partial_bio(bio, n_sectors: bio_size >> SECTOR_SHIFT);
1423
1424	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1425	wc->stats.writes_allocate += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1426
1427	if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
1428	wc->uncommitted_blocks = 0;
1429	queue_work(wq: wc->writeback_wq, work: &wc->flush_work);
1430	} else {
1431	writecache_schedule_autocommit(wc);
1432	}
1433	}
1434
1435	static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
1436	{
1437	struct wc_entry *e;
1438
1439	do {
1440	bool found_entry = false;
1441	bool search_used = false;
1442
1443	if (writecache_has_error(wc)) {
1444	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1445	return WC_MAP_ERROR;
1446	}
1447	e = writecache_find_entry(wc, block: bio->bi_iter.bi_sector, flags: 0);
1448	if (e) {
1449	if (!writecache_entry_is_committed(wc, e)) {
1450	wc->stats.write_hits_uncommitted++;
1451	search_used = true;
1452	goto bio_copy;
1453	}
1454	wc->stats.write_hits_committed++;
1455	if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
1456	wc->overwrote_committed = true;
1457	search_used = true;
1458	goto bio_copy;
1459	}
1460	found_entry = true;
1461	} else {
1462	if (unlikely(wc->cleaner) ||
1463	(wc->metadata_only && !(bio->bi_opf & REQ_META)))
1464	goto direct_write;
1465	}
1466	e = writecache_pop_from_freelist(wc, expected_sector: (sector_t)-1);
1467	if (unlikely(!e)) {
1468	if (!WC_MODE_PMEM(wc) && !found_entry) {
1469	direct_write:
1470	e = writecache_find_entry(wc, block: bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1471	writecache_map_remap_origin(wc, bio, e);
1472	wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
1473	wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1474	return WC_MAP_REMAP_ORIGIN;
1475	}
1476	wc->stats.writes_blocked_on_freelist++;
1477	writecache_wait_on_freelist(wc);
1478	continue;
1479	}
1480	write_original_sector_seq_count(wc, e, original_sector: bio->bi_iter.bi_sector, seq_count: wc->seq_count);
1481	writecache_insert_entry(wc, ins: e);
1482	wc->uncommitted_blocks++;
1483	wc->stats.writes_allocate++;
1484	bio_copy:
1485	if (WC_MODE_PMEM(wc)) {
1486	bio_copy_block(wc, bio, data: memory_data(wc, e));
1487	wc->stats.writes++;
1488	} else {
1489	writecache_bio_copy_ssd(wc, bio, e, search_used);
1490	return WC_MAP_REMAP;
1491	}
1492	} while (bio->bi_iter.bi_size);
1493
1494	if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks))
1495	writecache_flush(wc);
1496	else
1497	writecache_schedule_autocommit(wc);
1498
1499	return WC_MAP_SUBMIT;
1500	}
1501
1502	static enum wc_map_op writecache_map_flush(struct dm_writecache *wc, struct bio *bio)
1503	{
1504	if (writecache_has_error(wc))
1505	return WC_MAP_ERROR;
1506
1507	if (WC_MODE_PMEM(wc)) {
1508	wc->stats.flushes++;
1509	writecache_flush(wc);
1510	if (writecache_has_error(wc))
1511	return WC_MAP_ERROR;
1512	else if (unlikely(wc->cleaner) || unlikely(wc->metadata_only))
1513	return WC_MAP_REMAP_ORIGIN;
1514	return WC_MAP_SUBMIT;
1515	}
1516	/* SSD: */
1517	if (dm_bio_get_target_bio_nr(bio))
1518	return WC_MAP_REMAP_ORIGIN;
1519	wc->stats.flushes++;
1520	writecache_offload_bio(wc, bio);
1521	return WC_MAP_RETURN;
1522	}
1523
1524	static enum wc_map_op writecache_map_discard(struct dm_writecache *wc, struct bio *bio)
1525	{
1526	wc->stats.discards += bio->bi_iter.bi_size >> wc->block_size_bits;
1527
1528	if (writecache_has_error(wc))
1529	return WC_MAP_ERROR;
1530
1531	if (WC_MODE_PMEM(wc)) {
1532	writecache_discard(wc, start: bio->bi_iter.bi_sector, bio_end_sector(bio));
1533	return WC_MAP_REMAP_ORIGIN;
1534	}
1535	/* SSD: */
1536	writecache_offload_bio(wc, bio);
1537	return WC_MAP_RETURN;
1538	}
1539
1540	static int writecache_map(struct dm_target *ti, struct bio *bio)
1541	{
1542	struct dm_writecache *wc = ti->private;
1543	enum wc_map_op map_op;
1544
1545	bio->bi_private = NULL;
1546
1547	wc_lock(wc);
1548
1549	if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
1550	map_op = writecache_map_flush(wc, bio);
1551	goto done;
1552	}
1553
1554	bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
1555
1556	if (unlikely((((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
1557	(wc->block_size / 512 - 1)) != 0)) {
1558	DMERR("I/O is not aligned, sector %llu, size %u, block size %u",
1559	(unsigned long long)bio->bi_iter.bi_sector,
1560	bio->bi_iter.bi_size, wc->block_size);
1561	map_op = WC_MAP_ERROR;
1562	goto done;
1563	}
1564
1565	if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
1566	map_op = writecache_map_discard(wc, bio);
1567	goto done;
1568	}
1569
1570	if (bio_data_dir(bio) == READ)
1571	map_op = writecache_map_read(wc, bio);
1572	else
1573	map_op = writecache_map_write(wc, bio);
1574	done:
1575	switch (map_op) {
1576	case WC_MAP_REMAP_ORIGIN:
1577	if (likely(wc->pause != 0)) {
1578	if (bio_op(bio) == REQ_OP_WRITE) {
1579	dm_iot_io_begin(iot: &wc->iot, len: 1);
1580	bio->bi_private = (void *)2;
1581	}
1582	}
1583	bio_set_dev(bio, bdev: wc->dev->bdev);
1584	wc_unlock(wc);
1585	return DM_MAPIO_REMAPPED;
1586
1587	case WC_MAP_REMAP:
1588	/* make sure that writecache_end_io decrements bio_in_progress: */
1589	bio->bi_private = (void *)1;
1590	atomic_inc(v: &wc->bio_in_progress[bio_data_dir(bio)]);
1591	wc_unlock(wc);
1592	return DM_MAPIO_REMAPPED;
1593
1594	case WC_MAP_SUBMIT:
1595	wc_unlock(wc);
1596	bio_endio(bio);
1597	return DM_MAPIO_SUBMITTED;
1598
1599	case WC_MAP_RETURN:
1600	wc_unlock(wc);
1601	return DM_MAPIO_SUBMITTED;
1602
1603	case WC_MAP_ERROR:
1604	wc_unlock(wc);
1605	bio_io_error(bio);
1606	return DM_MAPIO_SUBMITTED;
1607
1608	default:
1609	BUG();
1610	wc_unlock(wc);
1611	return DM_MAPIO_KILL;
1612	}
1613	}
1614
1615	static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status)
1616	{
1617	struct dm_writecache *wc = ti->private;
1618
1619	if (bio->bi_private == (void *)1) {
1620	int dir = bio_data_dir(bio);
1621
1622	if (atomic_dec_and_test(v: &wc->bio_in_progress[dir]))
1623	if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
1624	wake_up(&wc->bio_in_progress_wait[dir]);
1625	} else if (bio->bi_private == (void *)2) {
1626	dm_iot_io_end(iot: &wc->iot, len: 1);
1627	}
1628	return 0;
1629	}
1630
1631	static int writecache_iterate_devices(struct dm_target *ti,
1632	iterate_devices_callout_fn fn, void *data)
1633	{
1634	struct dm_writecache *wc = ti->private;
1635
1636	return fn(ti, wc->dev, 0, ti->len, data);
1637	}
1638
1639	static void writecache_io_hints(struct dm_target *ti, struct queue_limits *limits)
1640	{
1641	struct dm_writecache *wc = ti->private;
1642
1643	if (limits->logical_block_size < wc->block_size)
1644	limits->logical_block_size = wc->block_size;
1645
1646	if (limits->physical_block_size < wc->block_size)
1647	limits->physical_block_size = wc->block_size;
1648
1649	if (limits->io_min < wc->block_size)
1650	limits->io_min = wc->block_size;
1651	}
1652
1653
1654	static void writecache_writeback_endio(struct bio *bio)
1655	{
1656	struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
1657	struct dm_writecache *wc = wb->wc;
1658	unsigned long flags;
1659
1660	raw_spin_lock_irqsave(&wc->endio_list_lock, flags);
1661	if (unlikely(list_empty(&wc->endio_list)))
1662	wake_up_process(tsk: wc->endio_thread);
1663	list_add_tail(new: &wb->endio_entry, head: &wc->endio_list);
1664	raw_spin_unlock_irqrestore(&wc->endio_list_lock, flags);
1665	}
1666
1667	static void writecache_copy_endio(int read_err, unsigned long write_err, void *ptr)
1668	{
1669	struct copy_struct *c = ptr;
1670	struct dm_writecache *wc = c->wc;
1671
1672	c->error = likely(!(read_err | write_err)) ? 0 : -EIO;
1673
1674	raw_spin_lock_irq(&wc->endio_list_lock);
1675	if (unlikely(list_empty(&wc->endio_list)))
1676	wake_up_process(tsk: wc->endio_thread);
1677	list_add_tail(new: &c->endio_entry, head: &wc->endio_list);
1678	raw_spin_unlock_irq(&wc->endio_list_lock);
1679	}
1680
1681	static void __writecache_endio_pmem(struct dm_writecache *wc, struct list_head *list)
1682	{
1683	unsigned int i;
1684	struct writeback_struct *wb;
1685	struct wc_entry *e;
1686	unsigned long n_walked = 0;
1687
1688	do {
1689	wb = list_entry(list->next, struct writeback_struct, endio_entry);
1690	list_del(entry: &wb->endio_entry);
1691
1692	if (unlikely(wb->bio.bi_status != BLK_STS_OK))
1693	writecache_error(wc, blk_status_to_errno(wb->bio.bi_status),
1694	"write error %d", wb->bio.bi_status);
1695	i = 0;
1696	do {
1697	e = wb->wc_list[i];
1698	BUG_ON(!e->write_in_progress);
1699	e->write_in_progress = false;
1700	INIT_LIST_HEAD(list: &e->lru);
1701	if (!writecache_has_error(wc))
1702	writecache_free_entry(wc, e);
1703	BUG_ON(!wc->writeback_size);
1704	wc->writeback_size--;
1705	n_walked++;
1706	if (unlikely(n_walked >= ENDIO_LATENCY)) {
1707	writecache_commit_flushed(wc, wait_for_ios: false);
1708	wc_unlock(wc);
1709	wc_lock(wc);
1710	n_walked = 0;
1711	}
1712	} while (++i < wb->wc_list_n);
1713
1714	if (wb->wc_list != wb->wc_list_inline)
1715	kfree(objp: wb->wc_list);
1716	bio_put(&wb->bio);
1717	} while (!list_empty(head: list));
1718	}
1719
1720	static void __writecache_endio_ssd(struct dm_writecache *wc, struct list_head *list)
1721	{
1722	struct copy_struct *c;
1723	struct wc_entry *e;
1724
1725	do {
1726	c = list_entry(list->next, struct copy_struct, endio_entry);
1727	list_del(entry: &c->endio_entry);
1728
1729	if (unlikely(c->error))
1730	writecache_error(wc, c->error, "copy error");
1731
1732	e = c->e;
1733	do {
1734	BUG_ON(!e->write_in_progress);
1735	e->write_in_progress = false;
1736	INIT_LIST_HEAD(list: &e->lru);
1737	if (!writecache_has_error(wc))
1738	writecache_free_entry(wc, e);
1739
1740	BUG_ON(!wc->writeback_size);
1741	wc->writeback_size--;
1742	e++;
1743	} while (--c->n_entries);
1744	mempool_free(element: c, pool: &wc->copy_pool);
1745	} while (!list_empty(head: list));
1746	}
1747
1748	static int writecache_endio_thread(void *data)
1749	{
1750	struct dm_writecache *wc = data;
1751
1752	while (1) {
1753	struct list_head list;
1754
1755	raw_spin_lock_irq(&wc->endio_list_lock);
1756	if (!list_empty(head: &wc->endio_list))
1757	goto pop_from_list;
1758	set_current_state(TASK_INTERRUPTIBLE);
1759	raw_spin_unlock_irq(&wc->endio_list_lock);
1760
1761	if (unlikely(kthread_should_stop())) {
1762	set_current_state(TASK_RUNNING);
1763	break;
1764	}
1765
1766	schedule();
1767
1768	continue;
1769
1770	pop_from_list:
1771	list = wc->endio_list;
1772	list.next->prev = list.prev->next = &list;
1773	INIT_LIST_HEAD(list: &wc->endio_list);
1774	raw_spin_unlock_irq(&wc->endio_list_lock);
1775
1776	if (!WC_MODE_FUA(wc))
1777	writecache_disk_flush(wc, dev: wc->dev);
1778
1779	wc_lock(wc);
1780
1781	if (WC_MODE_PMEM(wc)) {
1782	__writecache_endio_pmem(wc, list: &list);
1783	} else {
1784	__writecache_endio_ssd(wc, list: &list);
1785	writecache_wait_for_ios(wc, READ);
1786	}
1787
1788	writecache_commit_flushed(wc, wait_for_ios: false);
1789
1790	wc_unlock(wc);
1791	}
1792
1793	return 0;
1794	}
1795
1796	static bool wc_add_block(struct writeback_struct *wb, struct wc_entry *e)
1797	{
1798	struct dm_writecache *wc = wb->wc;
1799	unsigned int block_size = wc->block_size;
1800	void *address = memory_data(wc, e);
1801
1802	persistent_memory_flush_cache(ptr: address, size: block_size);
1803
1804	if (unlikely(bio_end_sector(&wb->bio) >= wc->data_device_sectors))
1805	return true;
1806
1807	return bio_add_page(bio: &wb->bio, page: persistent_memory_page(addr: address),
1808	len: block_size, off: persistent_memory_page_offset(addr: address)) != 0;
1809	}
1810
1811	struct writeback_list {
1812	struct list_head list;
1813	size_t size;
1814	};
1815
1816	static void __writeback_throttle(struct dm_writecache *wc, struct writeback_list *wbl)
1817	{
1818	if (unlikely(wc->max_writeback_jobs)) {
1819	if (READ_ONCE(wc->writeback_size) - wbl->size >= wc->max_writeback_jobs) {
1820	wc_lock(wc);
1821	while (wc->writeback_size - wbl->size >= wc->max_writeback_jobs)
1822	writecache_wait_on_freelist(wc);
1823	wc_unlock(wc);
1824	}
1825	}
1826	cond_resched();
1827	}
1828
1829	static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeback_list *wbl)
1830	{
1831	struct wc_entry *e, *f;
1832	struct bio *bio;
1833	struct writeback_struct *wb;
1834	unsigned int max_pages;
1835
1836	while (wbl->size) {
1837	wbl->size--;
1838	e = container_of(wbl->list.prev, struct wc_entry, lru);
1839	list_del(entry: &e->lru);
1840
1841	max_pages = e->wc_list_contiguous;
1842
1843	bio = bio_alloc_bioset(bdev: wc->dev->bdev, nr_vecs: max_pages, opf: REQ_OP_WRITE,
1844	GFP_NOIO, bs: &wc->bio_set);
1845	wb = container_of(bio, struct writeback_struct, bio);
1846	wb->wc = wc;
1847	bio->bi_end_io = writecache_writeback_endio;
1848	bio->bi_iter.bi_sector = read_original_sector(wc, e);
1849
1850	if (unlikely(max_pages > WB_LIST_INLINE))
1851	wb->wc_list = kmalloc_array(max_pages, sizeof(struct wc_entry *),
1852	GFP_NOIO | __GFP_NORETRY |
1853	__GFP_NOMEMALLOC | __GFP_NOWARN);
1854
1855	if (likely(max_pages <= WB_LIST_INLINE) || unlikely(!wb->wc_list)) {
1856	wb->wc_list = wb->wc_list_inline;
1857	max_pages = WB_LIST_INLINE;
1858	}
1859
1860	BUG_ON(!wc_add_block(wb, e));
1861
1862	wb->wc_list[0] = e;
1863	wb->wc_list_n = 1;
1864
1865	while (wbl->size && wb->wc_list_n < max_pages) {
1866	f = container_of(wbl->list.prev, struct wc_entry, lru);
1867	if (read_original_sector(wc, e: f) !=
1868	read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1869	break;
1870	if (!wc_add_block(wb, e: f))
1871	break;
1872	wbl->size--;
1873	list_del(entry: &f->lru);
1874	wb->wc_list[wb->wc_list_n++] = f;
1875	e = f;
1876	}
1877	if (WC_MODE_FUA(wc))
1878	bio->bi_opf |= REQ_FUA;
1879	if (writecache_has_error(wc)) {
1880	bio->bi_status = BLK_STS_IOERR;
1881	bio_endio(bio);
1882	} else if (unlikely(!bio_sectors(bio))) {
1883	bio->bi_status = BLK_STS_OK;
1884	bio_endio(bio);
1885	} else {
1886	submit_bio(bio);
1887	}
1888
1889	__writeback_throttle(wc, wbl);
1890	}
1891	}
1892
1893	static void __writecache_writeback_ssd(struct dm_writecache *wc, struct writeback_list *wbl)
1894	{
1895	struct wc_entry *e, *f;
1896	struct dm_io_region from, to;
1897	struct copy_struct *c;
1898
1899	while (wbl->size) {
1900	unsigned int n_sectors;
1901
1902	wbl->size--;
1903	e = container_of(wbl->list.prev, struct wc_entry, lru);
1904	list_del(entry: &e->lru);
1905
1906	n_sectors = e->wc_list_contiguous << (wc->block_size_bits - SECTOR_SHIFT);
1907
1908	from.bdev = wc->ssd_dev->bdev;
1909	from.sector = cache_sector(wc, e);
1910	from.count = n_sectors;
1911	to.bdev = wc->dev->bdev;
1912	to.sector = read_original_sector(wc, e);
1913	to.count = n_sectors;
1914
1915	c = mempool_alloc(&wc->copy_pool, GFP_NOIO);
1916	c->wc = wc;
1917	c->e = e;
1918	c->n_entries = e->wc_list_contiguous;
1919
1920	while ((n_sectors -= wc->block_size >> SECTOR_SHIFT)) {
1921	wbl->size--;
1922	f = container_of(wbl->list.prev, struct wc_entry, lru);
1923	BUG_ON(f != e + 1);
1924	list_del(entry: &f->lru);
1925	e = f;
1926	}
1927
1928	if (unlikely(to.sector + to.count > wc->data_device_sectors)) {
1929	if (to.sector >= wc->data_device_sectors) {
1930	writecache_copy_endio(read_err: 0, write_err: 0, ptr: c);
1931	continue;
1932	}
1933	from.count = to.count = wc->data_device_sectors - to.sector;
1934	}
1935
1936	dm_kcopyd_copy(kc: wc->dm_kcopyd, from: &from, num_dests: 1, dests: &to, flags: 0, fn: writecache_copy_endio, context: c);
1937
1938	__writeback_throttle(wc, wbl);
1939	}
1940	}
1941
1942	static void writecache_writeback(struct work_struct *work)
1943	{
1944	struct dm_writecache *wc = container_of(work, struct dm_writecache, writeback_work);
1945	struct blk_plug plug;
1946	struct wc_entry *f, *g, *e = NULL;
1947	struct rb_node *node, *next_node;
1948	struct list_head skipped;
1949	struct writeback_list wbl;
1950	unsigned long n_walked;
1951
1952	if (!WC_MODE_PMEM(wc)) {
1953	/* Wait for any active kcopyd work on behalf of ssd writeback */
1954	dm_kcopyd_client_flush(kc: wc->dm_kcopyd);
1955	}
1956
1957	if (likely(wc->pause != 0)) {
1958	while (1) {
1959	unsigned long idle;
1960
1961	if (unlikely(wc->cleaner) || unlikely(wc->writeback_all) ||
1962	unlikely(dm_suspended(wc->ti)))
1963	break;
1964	idle = dm_iot_idle_time(iot: &wc->iot);
1965	if (idle >= wc->pause)
1966	break;
1967	idle = wc->pause - idle;
1968	if (idle > HZ)
1969	idle = HZ;
1970	schedule_timeout_idle(timeout: idle);
1971	}
1972	}
1973
1974	wc_lock(wc);
1975	restart:
1976	if (writecache_has_error(wc)) {
1977	wc_unlock(wc);
1978	return;
1979	}
1980
1981	if (unlikely(wc->writeback_all)) {
1982	if (writecache_wait_for_writeback(wc))
1983	goto restart;
1984	}
1985
1986	if (wc->overwrote_committed)
1987	writecache_wait_for_ios(wc, WRITE);
1988
1989	n_walked = 0;
1990	INIT_LIST_HEAD(list: &skipped);
1991	INIT_LIST_HEAD(list: &wbl.list);
1992	wbl.size = 0;
1993	while (!list_empty(head: &wc->lru) &&
1994	(wc->writeback_all ||
1995	wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark ||
1996	(jiffies - container_of(wc->lru.prev, struct wc_entry, lru)->age >=
1997	wc->max_age - wc->max_age / MAX_AGE_DIV))) {
1998
1999	n_walked++;
2000	if (unlikely(n_walked > WRITEBACK_LATENCY) &&
2001	likely(!wc->writeback_all)) {
2002	if (likely(!dm_suspended(wc->ti)))
2003	queue_work(wq: wc->writeback_wq, work: &wc->writeback_work);
2004	break;
2005	}
2006
2007	if (unlikely(wc->writeback_all)) {
2008	if (unlikely(!e)) {
2009	writecache_flush(wc);
2010	e = container_of(rb_first(&wc->tree), struct wc_entry, rb_node);
2011	} else
2012	e = g;
2013	} else
2014	e = container_of(wc->lru.prev, struct wc_entry, lru);
2015	BUG_ON(e->write_in_progress);
2016	if (unlikely(!writecache_entry_is_committed(wc, e)))
2017	writecache_flush(wc);
2018
2019	node = rb_prev(&e->rb_node);
2020	if (node) {
2021	f = container_of(node, struct wc_entry, rb_node);
2022	if (unlikely(read_original_sector(wc, f) ==
2023	read_original_sector(wc, e))) {
2024	BUG_ON(!f->write_in_progress);
2025	list_move(list: &e->lru, head: &skipped);
2026	cond_resched();
2027	continue;
2028	}
2029	}
2030	wc->writeback_size++;
2031	list_move(list: &e->lru, head: &wbl.list);
2032	wbl.size++;
2033	e->write_in_progress = true;
2034	e->wc_list_contiguous = 1;
2035
2036	f = e;
2037
2038	while (1) {
2039	next_node = rb_next(&f->rb_node);
2040	if (unlikely(!next_node))
2041	break;
2042	g = container_of(next_node, struct wc_entry, rb_node);
2043	if (unlikely(read_original_sector(wc, g) ==
2044	read_original_sector(wc, f))) {
2045	f = g;
2046	continue;
2047	}
2048	if (read_original_sector(wc, e: g) !=
2049	read_original_sector(wc, e: f) + (wc->block_size >> SECTOR_SHIFT))
2050	break;
2051	if (unlikely(g->write_in_progress))
2052	break;
2053	if (unlikely(!writecache_entry_is_committed(wc, g)))
2054	break;
2055
2056	if (!WC_MODE_PMEM(wc)) {
2057	if (g != f + 1)
2058	break;
2059	}
2060
2061	n_walked++;
2062	//if (unlikely(n_walked > WRITEBACK_LATENCY) && likely(!wc->writeback_all))
2063	// break;
2064
2065	wc->writeback_size++;
2066	list_move(list: &g->lru, head: &wbl.list);
2067	wbl.size++;
2068	g->write_in_progress = true;
2069	g->wc_list_contiguous = BIO_MAX_VECS;
2070	f = g;
2071	e->wc_list_contiguous++;
2072	if (unlikely(e->wc_list_contiguous == BIO_MAX_VECS)) {
2073	if (unlikely(wc->writeback_all)) {
2074	next_node = rb_next(&f->rb_node);
2075	if (likely(next_node))
2076	g = container_of(next_node, struct wc_entry, rb_node);
2077	}
2078	break;
2079	}
2080	}
2081	cond_resched();
2082	}
2083
2084	if (!list_empty(head: &skipped)) {
2085	list_splice_tail(list: &skipped, head: &wc->lru);
2086	/*
2087	* If we didn't do any progress, we must wait until some
2088	* writeback finishes to avoid burning CPU in a loop
2089	*/
2090	if (unlikely(!wbl.size))
2091	writecache_wait_for_writeback(wc);
2092	}
2093
2094	wc_unlock(wc);
2095
2096	blk_start_plug(&plug);
2097
2098	if (WC_MODE_PMEM(wc))
2099	__writecache_writeback_pmem(wc, wbl: &wbl);
2100	else
2101	__writecache_writeback_ssd(wc, wbl: &wbl);
2102
2103	blk_finish_plug(&plug);
2104
2105	if (unlikely(wc->writeback_all)) {
2106	wc_lock(wc);
2107	while (writecache_wait_for_writeback(wc))
2108	;
2109	wc_unlock(wc);
2110	}
2111	}
2112
2113	static int calculate_memory_size(uint64_t device_size, unsigned int block_size,
2114	size_t *n_blocks_p, size_t *n_metadata_blocks_p)
2115	{
2116	uint64_t n_blocks, offset;
2117	struct wc_entry e;
2118
2119	n_blocks = device_size;
2120	do_div(n_blocks, block_size + sizeof(struct wc_memory_entry));
2121
2122	while (1) {
2123	if (!n_blocks)
2124	return -ENOSPC;
2125	/* Verify the following entries[n_blocks] won't overflow */
2126	if (n_blocks >= ((size_t)-sizeof(struct wc_memory_superblock) /
2127	sizeof(struct wc_memory_entry)))
2128	return -EFBIG;
2129	offset = offsetof(struct wc_memory_superblock, entries[n_blocks]);
2130	offset = (offset + block_size - 1) & ~(uint64_t)(block_size - 1);
2131	if (offset + n_blocks * block_size <= device_size)
2132	break;
2133	n_blocks--;
2134	}
2135
2136	/* check if the bit field overflows */
2137	e.index = n_blocks;
2138	if (e.index != n_blocks)
2139	return -EFBIG;
2140
2141	if (n_blocks_p)
2142	*n_blocks_p = n_blocks;
2143	if (n_metadata_blocks_p)
2144	*n_metadata_blocks_p = offset >> __ffs(block_size);
2145	return 0;
2146	}
2147
2148	static int init_memory(struct dm_writecache *wc)
2149	{
2150	size_t b;
2151	int r;
2152
2153	r = calculate_memory_size(device_size: wc->memory_map_size, block_size: wc->block_size, n_blocks_p: &wc->n_blocks, NULL);
2154	if (r)
2155	return r;
2156
2157	r = writecache_alloc_entries(wc);
2158	if (r)
2159	return r;
2160
2161	for (b = 0; b < ARRAY_SIZE(sb(wc)->padding); b++)
2162	pmem_assign(sb(wc)->padding[b], cpu_to_le64(0));
2163	pmem_assign(sb(wc)->version, cpu_to_le32(MEMORY_SUPERBLOCK_VERSION));
2164	pmem_assign(sb(wc)->block_size, cpu_to_le32(wc->block_size));
2165	pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
2166	pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
2167
2168	for (b = 0; b < wc->n_blocks; b++) {
2169	write_original_sector_seq_count(wc, e: &wc->entries[b], original_sector: -1, seq_count: -1);
2170	cond_resched();
2171	}
2172
2173	writecache_flush_all_metadata(wc);
2174	writecache_commit_flushed(wc, wait_for_ios: false);
2175	pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
2176	writecache_flush_region(wc, ptr: &sb(wc)->magic, size: sizeof(sb(wc)->magic));
2177	writecache_commit_flushed(wc, wait_for_ios: false);
2178
2179	return 0;
2180	}
2181
2182	static void writecache_dtr(struct dm_target *ti)
2183	{
2184	struct dm_writecache *wc = ti->private;
2185
2186	if (!wc)
2187	return;
2188
2189	if (wc->endio_thread)
2190	kthread_stop(k: wc->endio_thread);
2191
2192	if (wc->flush_thread)
2193	kthread_stop(k: wc->flush_thread);
2194
2195	bioset_exit(&wc->bio_set);
2196
2197	mempool_exit(pool: &wc->copy_pool);
2198
2199	if (wc->writeback_wq)
2200	destroy_workqueue(wq: wc->writeback_wq);
2201
2202	if (wc->dev)
2203	dm_put_device(ti, d: wc->dev);
2204
2205	if (wc->ssd_dev)
2206	dm_put_device(ti, d: wc->ssd_dev);
2207
2208	vfree(addr: wc->entries);
2209
2210	if (wc->memory_map) {
2211	if (WC_MODE_PMEM(wc))
2212	persistent_memory_release(wc);
2213	else
2214	vfree(addr: wc->memory_map);
2215	}
2216
2217	if (wc->dm_kcopyd)
2218	dm_kcopyd_client_destroy(kc: wc->dm_kcopyd);
2219
2220	if (wc->dm_io)
2221	dm_io_client_destroy(client: wc->dm_io);
2222
2223	vfree(addr: wc->dirty_bitmap);
2224
2225	kfree(objp: wc);
2226	}
2227
2228	static int writecache_ctr(struct dm_target *ti, unsigned int argc, char **argv)
2229	{
2230	struct dm_writecache *wc;
2231	struct dm_arg_set as;
2232	const char *string;
2233	unsigned int opt_params;
2234	size_t offset, data_size;
2235	int i, r;
2236	char dummy;
2237	int high_wm_percent = HIGH_WATERMARK;
2238	int low_wm_percent = LOW_WATERMARK;
2239	uint64_t x;
2240	struct wc_memory_superblock s;
2241
2242	static struct dm_arg _args[] = {
2243	{0, 18, "Invalid number of feature args"},
2244	};
2245
2246	as.argc = argc;
2247	as.argv = argv;
2248
2249	wc = kzalloc(sizeof(struct dm_writecache), GFP_KERNEL);
2250	if (!wc) {
2251	ti->error = "Cannot allocate writecache structure";
2252	r = -ENOMEM;
2253	goto bad;
2254	}
2255	ti->private = wc;
2256	wc->ti = ti;
2257
2258	mutex_init(&wc->lock);
2259	wc->max_age = MAX_AGE_UNSPECIFIED;
2260	writecache_poison_lists(wc);
2261	init_waitqueue_head(&wc->freelist_wait);
2262	timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0);
2263	timer_setup(&wc->max_age_timer, writecache_max_age_timer, 0);
2264
2265	for (i = 0; i < 2; i++) {
2266	atomic_set(v: &wc->bio_in_progress[i], i: 0);
2267	init_waitqueue_head(&wc->bio_in_progress_wait[i]);
2268	}
2269
2270	wc->dm_io = dm_io_client_create();
2271	if (IS_ERR(ptr: wc->dm_io)) {
2272	r = PTR_ERR(ptr: wc->dm_io);
2273	ti->error = "Unable to allocate dm-io client";
2274	wc->dm_io = NULL;
2275	goto bad;
2276	}
2277
2278	wc->writeback_wq = alloc_workqueue("writecache-writeback", WQ_MEM_RECLAIM, 1);
2279	if (!wc->writeback_wq) {
2280	r = -ENOMEM;
2281	ti->error = "Could not allocate writeback workqueue";
2282	goto bad;
2283	}
2284	INIT_WORK(&wc->writeback_work, writecache_writeback);
2285	INIT_WORK(&wc->flush_work, writecache_flush_work);
2286
2287	dm_iot_init(iot: &wc->iot);
2288
2289	raw_spin_lock_init(&wc->endio_list_lock);
2290	INIT_LIST_HEAD(list: &wc->endio_list);
2291	wc->endio_thread = kthread_run(writecache_endio_thread, wc, "writecache_endio");
2292	if (IS_ERR(ptr: wc->endio_thread)) {
2293	r = PTR_ERR(ptr: wc->endio_thread);
2294	wc->endio_thread = NULL;
2295	ti->error = "Couldn't spawn endio thread";
2296	goto bad;
2297	}
2298
2299	/*
2300	* Parse the mode (pmem or ssd)
2301	*/
2302	string = dm_shift_arg(as: &as);
2303	if (!string)
2304	goto bad_arguments;
2305
2306	if (!strcasecmp(s1: string, s2: "s")) {
2307	wc->pmem_mode = false;
2308	} else if (!strcasecmp(s1: string, s2: "p")) {
2309	#ifdef DM_WRITECACHE_HAS_PMEM
2310	wc->pmem_mode = true;
2311	wc->writeback_fua = true;
2312	#else
2313	/*
2314	* If the architecture doesn't support persistent memory or
2315	* the kernel doesn't support any DAX drivers, this driver can
2316	* only be used in SSD-only mode.
2317	*/
2318	r = -EOPNOTSUPP;
2319	ti->error = "Persistent memory or DAX not supported on this system";
2320	goto bad;
2321	#endif
2322	} else {
2323	goto bad_arguments;
2324	}
2325
2326	if (WC_MODE_PMEM(wc)) {
2327	r = bioset_init(&wc->bio_set, BIO_POOL_SIZE,
2328	offsetof(struct writeback_struct, bio),
2329	flags: BIOSET_NEED_BVECS);
2330	if (r) {
2331	ti->error = "Could not allocate bio set";
2332	goto bad;
2333	}
2334	} else {
2335	wc->pause = PAUSE_WRITEBACK;
2336	r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
2337	if (r) {
2338	ti->error = "Could not allocate mempool";
2339	goto bad;
2340	}
2341	}
2342
2343	/*
2344	* Parse the origin data device
2345	*/
2346	string = dm_shift_arg(as: &as);
2347	if (!string)
2348	goto bad_arguments;
2349	r = dm_get_device(ti, path: string, mode: dm_table_get_mode(t: ti->table), result: &wc->dev);
2350	if (r) {
2351	ti->error = "Origin data device lookup failed";
2352	goto bad;
2353	}
2354
2355	/*
2356	* Parse cache data device (be it pmem or ssd)
2357	*/
2358	string = dm_shift_arg(as: &as);
2359	if (!string)
2360	goto bad_arguments;
2361
2362	r = dm_get_device(ti, path: string, mode: dm_table_get_mode(t: ti->table), result: &wc->ssd_dev);
2363	if (r) {
2364	ti->error = "Cache data device lookup failed";
2365	goto bad;
2366	}
2367	wc->memory_map_size = bdev_nr_bytes(bdev: wc->ssd_dev->bdev);
2368
2369	/*
2370	* Parse the cache block size
2371	*/
2372	string = dm_shift_arg(as: &as);
2373	if (!string)
2374	goto bad_arguments;
2375	if (sscanf(string, "%u%c", &wc->block_size, &dummy) != 1 ||
2376	wc->block_size < 512 || wc->block_size > PAGE_SIZE ||
2377	(wc->block_size & (wc->block_size - 1))) {
2378	r = -EINVAL;
2379	ti->error = "Invalid block size";
2380	goto bad;
2381	}
2382	if (wc->block_size < bdev_logical_block_size(bdev: wc->dev->bdev) ||
2383	wc->block_size < bdev_logical_block_size(bdev: wc->ssd_dev->bdev)) {
2384	r = -EINVAL;
2385	ti->error = "Block size is smaller than device logical block size";
2386	goto bad;
2387	}
2388	wc->block_size_bits = __ffs(wc->block_size);
2389
2390	wc->max_writeback_jobs = MAX_WRITEBACK_JOBS;
2391	wc->autocommit_blocks = !WC_MODE_PMEM(wc) ? AUTOCOMMIT_BLOCKS_SSD : AUTOCOMMIT_BLOCKS_PMEM;
2392	wc->autocommit_jiffies = msecs_to_jiffies(AUTOCOMMIT_MSEC);
2393
2394	/*
2395	* Parse optional arguments
2396	*/
2397	r = dm_read_arg_group(arg: _args, arg_set: &as, num_args: &opt_params, error: &ti->error);
2398	if (r)
2399	goto bad;
2400
2401	while (opt_params) {
2402	string = dm_shift_arg(as: &as), opt_params--;
2403	if (!strcasecmp(s1: string, s2: "start_sector") && opt_params >= 1) {
2404	unsigned long long start_sector;
2405
2406	string = dm_shift_arg(as: &as), opt_params--;
2407	if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
2408	goto invalid_optional;
2409	wc->start_sector = start_sector;
2410	wc->start_sector_set = true;
2411	if (wc->start_sector != start_sector ||
2412	wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
2413	goto invalid_optional;
2414	} else if (!strcasecmp(s1: string, s2: "high_watermark") && opt_params >= 1) {
2415	string = dm_shift_arg(as: &as), opt_params--;
2416	if (sscanf(string, "%d%c", &high_wm_percent, &dummy) != 1)
2417	goto invalid_optional;
2418	if (high_wm_percent < 0 || high_wm_percent > 100)
2419	goto invalid_optional;
2420	wc->high_wm_percent_value = high_wm_percent;
2421	wc->high_wm_percent_set = true;
2422	} else if (!strcasecmp(s1: string, s2: "low_watermark") && opt_params >= 1) {
2423	string = dm_shift_arg(as: &as), opt_params--;
2424	if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
2425	goto invalid_optional;
2426	if (low_wm_percent < 0 || low_wm_percent > 100)
2427	goto invalid_optional;
2428	wc->low_wm_percent_value = low_wm_percent;
2429	wc->low_wm_percent_set = true;
2430	} else if (!strcasecmp(s1: string, s2: "writeback_jobs") && opt_params >= 1) {
2431	string = dm_shift_arg(as: &as), opt_params--;
2432	if (sscanf(string, "%u%c", &wc->max_writeback_jobs, &dummy) != 1)
2433	goto invalid_optional;
2434	wc->max_writeback_jobs_set = true;
2435	} else if (!strcasecmp(s1: string, s2: "autocommit_blocks") && opt_params >= 1) {
2436	string = dm_shift_arg(as: &as), opt_params--;
2437	if (sscanf(string, "%u%c", &wc->autocommit_blocks, &dummy) != 1)
2438	goto invalid_optional;
2439	wc->autocommit_blocks_set = true;
2440	} else if (!strcasecmp(s1: string, s2: "autocommit_time") && opt_params >= 1) {
2441	unsigned int autocommit_msecs;
2442
2443	string = dm_shift_arg(as: &as), opt_params--;
2444	if (sscanf(string, "%u%c", &autocommit_msecs, &dummy) != 1)
2445	goto invalid_optional;
2446	if (autocommit_msecs > 3600000)
2447	goto invalid_optional;
2448	wc->autocommit_jiffies = msecs_to_jiffies(m: autocommit_msecs);
2449	wc->autocommit_time_value = autocommit_msecs;
2450	wc->autocommit_time_set = true;
2451	} else if (!strcasecmp(s1: string, s2: "max_age") && opt_params >= 1) {
2452	unsigned int max_age_msecs;
2453
2454	string = dm_shift_arg(as: &as), opt_params--;
2455	if (sscanf(string, "%u%c", &max_age_msecs, &dummy) != 1)
2456	goto invalid_optional;
2457	if (max_age_msecs > 86400000)
2458	goto invalid_optional;
2459	wc->max_age = msecs_to_jiffies(m: max_age_msecs);
2460	wc->max_age_set = true;
2461	wc->max_age_value = max_age_msecs;
2462	} else if (!strcasecmp(s1: string, s2: "cleaner")) {
2463	wc->cleaner_set = true;
2464	wc->cleaner = true;
2465	} else if (!strcasecmp(s1: string, s2: "fua")) {
2466	if (WC_MODE_PMEM(wc)) {
2467	wc->writeback_fua = true;
2468	wc->writeback_fua_set = true;
2469	} else
2470	goto invalid_optional;
2471	} else if (!strcasecmp(s1: string, s2: "nofua")) {
2472	if (WC_MODE_PMEM(wc)) {
2473	wc->writeback_fua = false;
2474	wc->writeback_fua_set = true;
2475	} else
2476	goto invalid_optional;
2477	} else if (!strcasecmp(s1: string, s2: "metadata_only")) {
2478	wc->metadata_only = true;
2479	} else if (!strcasecmp(s1: string, s2: "pause_writeback") && opt_params >= 1) {
2480	unsigned int pause_msecs;
2481
2482	if (WC_MODE_PMEM(wc))
2483	goto invalid_optional;
2484	string = dm_shift_arg(as: &as), opt_params--;
2485	if (sscanf(string, "%u%c", &pause_msecs, &dummy) != 1)
2486	goto invalid_optional;
2487	if (pause_msecs > 60000)
2488	goto invalid_optional;
2489	wc->pause = msecs_to_jiffies(m: pause_msecs);
2490	wc->pause_set = true;
2491	wc->pause_value = pause_msecs;
2492	} else {
2493	invalid_optional:
2494	r = -EINVAL;
2495	ti->error = "Invalid optional argument";
2496	goto bad;
2497	}
2498	}
2499
2500	if (high_wm_percent < low_wm_percent) {
2501	r = -EINVAL;
2502	ti->error = "High watermark must be greater than or equal to low watermark";
2503	goto bad;
2504	}
2505
2506	if (WC_MODE_PMEM(wc)) {
2507	if (!dax_synchronous(dax_dev: wc->ssd_dev->dax_dev)) {
2508	r = -EOPNOTSUPP;
2509	ti->error = "Asynchronous persistent memory not supported as pmem cache";
2510	goto bad;
2511	}
2512
2513	r = persistent_memory_claim(wc);
2514	if (r) {
2515	ti->error = "Unable to map persistent memory for cache";
2516	goto bad;
2517	}
2518	} else {
2519	size_t n_blocks, n_metadata_blocks;
2520	uint64_t n_bitmap_bits;
2521
2522	wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
2523
2524	bio_list_init(bl: &wc->flush_list);
2525	wc->flush_thread = kthread_run(writecache_flush_thread, wc, "dm_writecache_flush");
2526	if (IS_ERR(ptr: wc->flush_thread)) {
2527	r = PTR_ERR(ptr: wc->flush_thread);
2528	wc->flush_thread = NULL;
2529	ti->error = "Couldn't spawn flush thread";
2530	goto bad;
2531	}
2532
2533	r = calculate_memory_size(device_size: wc->memory_map_size, block_size: wc->block_size,
2534	n_blocks_p: &n_blocks, n_metadata_blocks_p: &n_metadata_blocks);
2535	if (r) {
2536	ti->error = "Invalid device size";
2537	goto bad;
2538	}
2539
2540	n_bitmap_bits = (((uint64_t)n_metadata_blocks << wc->block_size_bits) +
2541	BITMAP_GRANULARITY - 1) / BITMAP_GRANULARITY;
2542	/* this is limitation of test_bit functions */
2543	if (n_bitmap_bits > 1U << 31) {
2544	r = -EFBIG;
2545	ti->error = "Invalid device size";
2546	goto bad;
2547	}
2548
2549	wc->memory_map = vmalloc(n_metadata_blocks << wc->block_size_bits);
2550	if (!wc->memory_map) {
2551	r = -ENOMEM;
2552	ti->error = "Unable to allocate memory for metadata";
2553	goto bad;
2554	}
2555
2556	wc->dm_kcopyd = dm_kcopyd_client_create(throttle: &dm_kcopyd_throttle);
2557	if (IS_ERR(ptr: wc->dm_kcopyd)) {
2558	r = PTR_ERR(ptr: wc->dm_kcopyd);
2559	ti->error = "Unable to allocate dm-kcopyd client";
2560	wc->dm_kcopyd = NULL;
2561	goto bad;
2562	}
2563
2564	wc->metadata_sectors = n_metadata_blocks << (wc->block_size_bits - SECTOR_SHIFT);
2565	wc->dirty_bitmap_size = (n_bitmap_bits + BITS_PER_LONG - 1) /
2566	BITS_PER_LONG * sizeof(unsigned long);
2567	wc->dirty_bitmap = vzalloc(wc->dirty_bitmap_size);
2568	if (!wc->dirty_bitmap) {
2569	r = -ENOMEM;
2570	ti->error = "Unable to allocate dirty bitmap";
2571	goto bad;
2572	}
2573
2574	r = writecache_read_metadata(wc, n_sectors: wc->block_size >> SECTOR_SHIFT);
2575	if (r) {
2576	ti->error = "Unable to read first block of metadata";
2577	goto bad;
2578	}
2579	}
2580
2581	r = copy_mc_to_kernel(to: &s, from: sb(wc), len: sizeof(struct wc_memory_superblock));
2582	if (r) {
2583	ti->error = "Hardware memory error when reading superblock";
2584	goto bad;
2585	}
2586	if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
2587	r = init_memory(wc);
2588	if (r) {
2589	ti->error = "Unable to initialize device";
2590	goto bad;
2591	}
2592	r = copy_mc_to_kernel(to: &s, from: sb(wc),
2593	len: sizeof(struct wc_memory_superblock));
2594	if (r) {
2595	ti->error = "Hardware memory error when reading superblock";
2596	goto bad;
2597	}
2598	}
2599
2600	if (le32_to_cpu(s.magic) != MEMORY_SUPERBLOCK_MAGIC) {
2601	ti->error = "Invalid magic in the superblock";
2602	r = -EINVAL;
2603	goto bad;
2604	}
2605
2606	if (le32_to_cpu(s.version) != MEMORY_SUPERBLOCK_VERSION) {
2607	ti->error = "Invalid version in the superblock";
2608	r = -EINVAL;
2609	goto bad;
2610	}
2611
2612	if (le32_to_cpu(s.block_size) != wc->block_size) {
2613	ti->error = "Block size does not match superblock";
2614	r = -EINVAL;
2615	goto bad;
2616	}
2617
2618	wc->n_blocks = le64_to_cpu(s.n_blocks);
2619
2620	offset = wc->n_blocks * sizeof(struct wc_memory_entry);
2621	if (offset / sizeof(struct wc_memory_entry) != le64_to_cpu(sb(wc)->n_blocks)) {
2622	overflow:
2623	ti->error = "Overflow in size calculation";
2624	r = -EINVAL;
2625	goto bad;
2626	}
2627	offset += sizeof(struct wc_memory_superblock);
2628	if (offset < sizeof(struct wc_memory_superblock))
2629	goto overflow;
2630	offset = (offset + wc->block_size - 1) & ~(size_t)(wc->block_size - 1);
2631	data_size = wc->n_blocks * (size_t)wc->block_size;
2632	if (!offset || (data_size / wc->block_size != wc->n_blocks) ||
2633	(offset + data_size < offset))
2634	goto overflow;
2635	if (offset + data_size > wc->memory_map_size) {
2636	ti->error = "Memory area is too small";
2637	r = -EINVAL;
2638	goto bad;
2639	}
2640
2641	wc->metadata_sectors = offset >> SECTOR_SHIFT;
2642	wc->block_start = (char *)sb(wc) + offset;
2643
2644	x = (uint64_t)wc->n_blocks * (100 - high_wm_percent);
2645	x += 50;
2646	do_div(x, 100);
2647	wc->freelist_high_watermark = x;
2648	x = (uint64_t)wc->n_blocks * (100 - low_wm_percent);
2649	x += 50;
2650	do_div(x, 100);
2651	wc->freelist_low_watermark = x;
2652
2653	if (wc->cleaner)
2654	activate_cleaner(wc);
2655
2656	r = writecache_alloc_entries(wc);
2657	if (r) {
2658	ti->error = "Cannot allocate memory";
2659	goto bad;
2660	}
2661
2662	ti->num_flush_bios = WC_MODE_PMEM(wc) ? 1 : 2;
2663	ti->flush_supported = true;
2664	ti->num_discard_bios = 1;
2665
2666	if (WC_MODE_PMEM(wc))
2667	persistent_memory_flush_cache(ptr: wc->memory_map, size: wc->memory_map_size);
2668
2669	return 0;
2670
2671	bad_arguments:
2672	r = -EINVAL;
2673	ti->error = "Bad arguments";
2674	bad:
2675	writecache_dtr(ti);
2676	return r;
2677	}
2678
2679	static void writecache_status(struct dm_target *ti, status_type_t type,
2680	unsigned int status_flags, char *result, unsigned int maxlen)
2681	{
2682	struct dm_writecache *wc = ti->private;
2683	unsigned int extra_args;
2684	unsigned int sz = 0;
2685
2686	switch (type) {
2687	case STATUSTYPE_INFO:
2688	DMEMIT("%ld %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu",
2689	writecache_has_error(wc),
2690	(unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
2691	(unsigned long long)wc->writeback_size,
2692	wc->stats.reads,
2693	wc->stats.read_hits,
2694	wc->stats.writes,
2695	wc->stats.write_hits_uncommitted,
2696	wc->stats.write_hits_committed,
2697	wc->stats.writes_around,
2698	wc->stats.writes_allocate,
2699	wc->stats.writes_blocked_on_freelist,
2700	wc->stats.flushes,
2701	wc->stats.discards);
2702	break;
2703	case STATUSTYPE_TABLE:
2704	DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
2705	wc->dev->name, wc->ssd_dev->name, wc->block_size);
2706	extra_args = 0;
2707	if (wc->start_sector_set)
2708	extra_args += 2;
2709	if (wc->high_wm_percent_set)
2710	extra_args += 2;
2711	if (wc->low_wm_percent_set)
2712	extra_args += 2;
2713	if (wc->max_writeback_jobs_set)
2714	extra_args += 2;
2715	if (wc->autocommit_blocks_set)
2716	extra_args += 2;
2717	if (wc->autocommit_time_set)
2718	extra_args += 2;
2719	if (wc->max_age_set)
2720	extra_args += 2;
2721	if (wc->cleaner_set)
2722	extra_args++;
2723	if (wc->writeback_fua_set)
2724	extra_args++;
2725	if (wc->metadata_only)
2726	extra_args++;
2727	if (wc->pause_set)
2728	extra_args += 2;
2729
2730	DMEMIT("%u", extra_args);
2731	if (wc->start_sector_set)
2732	DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
2733	if (wc->high_wm_percent_set)
2734	DMEMIT(" high_watermark %u", wc->high_wm_percent_value);
2735	if (wc->low_wm_percent_set)
2736	DMEMIT(" low_watermark %u", wc->low_wm_percent_value);
2737	if (wc->max_writeback_jobs_set)
2738	DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
2739	if (wc->autocommit_blocks_set)
2740	DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
2741	if (wc->autocommit_time_set)
2742	DMEMIT(" autocommit_time %u", wc->autocommit_time_value);
2743	if (wc->max_age_set)
2744	DMEMIT(" max_age %u", wc->max_age_value);
2745	if (wc->cleaner_set)
2746	DMEMIT(" cleaner");
2747	if (wc->writeback_fua_set)
2748	DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
2749	if (wc->metadata_only)
2750	DMEMIT(" metadata_only");
2751	if (wc->pause_set)
2752	DMEMIT(" pause_writeback %u", wc->pause_value);
2753	break;
2754	case STATUSTYPE_IMA:
2755	*result = '\0';
2756	break;
2757	}
2758	}
2759
2760	static struct target_type writecache_target = {
2761	.name = "writecache",
2762	.version = {1, 6, 0},
2763	.module = THIS_MODULE,
2764	.ctr = writecache_ctr,
2765	.dtr = writecache_dtr,
2766	.status = writecache_status,
2767	.postsuspend = writecache_suspend,
2768	.resume = writecache_resume,
2769	.message = writecache_message,
2770	.map = writecache_map,
2771	.end_io = writecache_end_io,
2772	.iterate_devices = writecache_iterate_devices,
2773	.io_hints = writecache_io_hints,
2774	};
2775	module_dm(writecache);
2776
2777	MODULE_DESCRIPTION(DM_NAME " writecache target");
2778	MODULE_AUTHOR("Mikulas Patocka <dm-devel@lists.linux.dev>");
2779	MODULE_LICENSE("GPL");
2780