1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2003 Sistina Software
4 * Copyright (C) 2006 Red Hat GmbH
5 *
6 * This file is released under the GPL.
7 */
8
9#include "dm-core.h"
10
11#include <linux/device-mapper.h>
12
13#include <linux/bio.h>
14#include <linux/completion.h>
15#include <linux/mempool.h>
16#include <linux/module.h>
17#include <linux/sched.h>
18#include <linux/slab.h>
19#include <linux/dm-io.h>
20
21#define DM_MSG_PREFIX "io"
22
23#define DM_IO_MAX_REGIONS	BITS_PER_LONG
24
25struct dm_io_client {
26	mempool_t pool;
27	struct bio_set bios;
28};
29
30/*
31 * Aligning 'struct io' reduces the number of bits required to store
32 * its address.  Refer to store_io_and_region_in_bio() below.
33 */
34struct io {
35	unsigned long error_bits;
36	atomic_t count;
37	struct dm_io_client *client;
38	io_notify_fn callback;
39	void *context;
40	void *vma_invalidate_address;
41	unsigned long vma_invalidate_size;
42} __aligned(DM_IO_MAX_REGIONS);
43
44static struct kmem_cache *_dm_io_cache;
45
46/*
47 * Create a client with mempool and bioset.
48 */
49struct dm_io_client *dm_io_client_create(void)
50{
51	struct dm_io_client *client;
52	unsigned int min_ios = dm_get_reserved_bio_based_ios();
53	int ret;
54
55	client = kzalloc(sizeof(*client), GFP_KERNEL);
56	if (!client)
57		return ERR_PTR(-ENOMEM);
58
59	ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache);
60	if (ret)
61		goto bad;
62
63	ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS);
64	if (ret)
65		goto bad;
66
67	return client;
68
69bad:
70	mempool_exit(&client->pool);
71	kfree(client);
72	return ERR_PTR(ret);
73}
74EXPORT_SYMBOL(dm_io_client_create);
75
76void dm_io_client_destroy(struct dm_io_client *client)
77{
78	mempool_exit(&client->pool);
79	bioset_exit(&client->bios);
80	kfree(client);
81}
82EXPORT_SYMBOL(dm_io_client_destroy);
83
84/*
85 *-------------------------------------------------------------------
86 * We need to keep track of which region a bio is doing io for.
87 * To avoid a memory allocation to store just 5 or 6 bits, we
88 * ensure the 'struct io' pointer is aligned so enough low bits are
89 * always zero and then combine it with the region number directly in
90 * bi_private.
91 *-------------------------------------------------------------------
92 */
93static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
94				       unsigned int region)
95{
96	if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
97		DMCRIT("Unaligned struct io pointer %p", io);
98		BUG();
99	}
100
101	bio->bi_private = (void *)((unsigned long)io | region);
102}
103
104static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
105				       unsigned int *region)
106{
107	unsigned long val = (unsigned long)bio->bi_private;
108
109	*io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
110	*region = val & (DM_IO_MAX_REGIONS - 1);
111}
112
113/*
114 *--------------------------------------------------------------
115 * We need an io object to keep track of the number of bios that
116 * have been dispatched for a particular io.
117 *--------------------------------------------------------------
118 */
119static void complete_io(struct io *io)
120{
121	unsigned long error_bits = io->error_bits;
122	io_notify_fn fn = io->callback;
123	void *context = io->context;
124
125	if (io->vma_invalidate_size)
126		invalidate_kernel_vmap_range(io->vma_invalidate_address,
127					     io->vma_invalidate_size);
128
129	mempool_free(io, &io->client->pool);
130	fn(error_bits, context);
131}
132
133static void dec_count(struct io *io, unsigned int region, blk_status_t error)
134{
135	if (error)
136		set_bit(region, &io->error_bits);
137
138	if (atomic_dec_and_test(&io->count))
139		complete_io(io);
140}
141
142static void endio(struct bio *bio)
143{
144	struct io *io;
145	unsigned int region;
146	blk_status_t error;
147
148	if (bio->bi_status && bio_data_dir(bio) == READ)
149		zero_fill_bio(bio);
150
151	/*
152	 * The bio destructor in bio_put() may use the io object.
153	 */
154	retrieve_io_and_region_from_bio(bio, &io, &region);
155
156	error = bio->bi_status;
157	bio_put(bio);
158
159	dec_count(io, region, error);
160}
161
162/*
163 *--------------------------------------------------------------
164 * These little objects provide an abstraction for getting a new
165 * destination page for io.
166 *--------------------------------------------------------------
167 */
168struct dpages {
169	void (*get_page)(struct dpages *dp,
170			 struct page **p, unsigned long *len, unsigned int *offset);
171	void (*next_page)(struct dpages *dp);
172
173	union {
174		unsigned int context_u;
175		struct bvec_iter context_bi;
176	};
177	void *context_ptr;
178
179	void *vma_invalidate_address;
180	unsigned long vma_invalidate_size;
181};
182
183/*
184 * Functions for getting the pages from a list.
185 */
186static void list_get_page(struct dpages *dp,
187		  struct page **p, unsigned long *len, unsigned int *offset)
188{
189	unsigned int o = dp->context_u;
190	struct page_list *pl = dp->context_ptr;
191
192	*p = pl->page;
193	*len = PAGE_SIZE - o;
194	*offset = o;
195}
196
197static void list_next_page(struct dpages *dp)
198{
199	struct page_list *pl = dp->context_ptr;
200
201	dp->context_ptr = pl->next;
202	dp->context_u = 0;
203}
204
205static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned int offset)
206{
207	dp->get_page = list_get_page;
208	dp->next_page = list_next_page;
209	dp->context_u = offset;
210	dp->context_ptr = pl;
211}
212
213/*
214 * Functions for getting the pages from a bvec.
215 */
216static void bio_get_page(struct dpages *dp, struct page **p,
217			 unsigned long *len, unsigned int *offset)
218{
219	struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr,
220					     dp->context_bi);
221
222	*p = bvec.bv_page;
223	*len = bvec.bv_len;
224	*offset = bvec.bv_offset;
225
226	/* avoid figuring it out again in bio_next_page() */
227	dp->context_bi.bi_sector = (sector_t)bvec.bv_len;
228}
229
230static void bio_next_page(struct dpages *dp)
231{
232	unsigned int len = (unsigned int)dp->context_bi.bi_sector;
233
234	bvec_iter_advance((struct bio_vec *)dp->context_ptr,
235			  &dp->context_bi, len);
236}
237
238static void bio_dp_init(struct dpages *dp, struct bio *bio)
239{
240	dp->get_page = bio_get_page;
241	dp->next_page = bio_next_page;
242
243	/*
244	 * We just use bvec iterator to retrieve pages, so it is ok to
245	 * access the bvec table directly here
246	 */
247	dp->context_ptr = bio->bi_io_vec;
248	dp->context_bi = bio->bi_iter;
249}
250
251/*
252 * Functions for getting the pages from a VMA.
253 */
254static void vm_get_page(struct dpages *dp,
255		 struct page **p, unsigned long *len, unsigned int *offset)
256{
257	*p = vmalloc_to_page(dp->context_ptr);
258	*offset = dp->context_u;
259	*len = PAGE_SIZE - dp->context_u;
260}
261
262static void vm_next_page(struct dpages *dp)
263{
264	dp->context_ptr += PAGE_SIZE - dp->context_u;
265	dp->context_u = 0;
266}
267
268static void vm_dp_init(struct dpages *dp, void *data)
269{
270	dp->get_page = vm_get_page;
271	dp->next_page = vm_next_page;
272	dp->context_u = offset_in_page(data);
273	dp->context_ptr = data;
274}
275
276/*
277 * Functions for getting the pages from kernel memory.
278 */
279static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
280			unsigned int *offset)
281{
282	*p = virt_to_page(dp->context_ptr);
283	*offset = dp->context_u;
284	*len = PAGE_SIZE - dp->context_u;
285}
286
287static void km_next_page(struct dpages *dp)
288{
289	dp->context_ptr += PAGE_SIZE - dp->context_u;
290	dp->context_u = 0;
291}
292
293static void km_dp_init(struct dpages *dp, void *data)
294{
295	dp->get_page = km_get_page;
296	dp->next_page = km_next_page;
297	dp->context_u = offset_in_page(data);
298	dp->context_ptr = data;
299}
300
301/*
302 *---------------------------------------------------------------
303 * IO routines that accept a list of pages.
304 *---------------------------------------------------------------
305 */
306static void do_region(const blk_opf_t opf, unsigned int region,
307		      struct dm_io_region *where, struct dpages *dp,
308		      struct io *io, unsigned short ioprio)
309{
310	struct bio *bio;
311	struct page *page;
312	unsigned long len;
313	unsigned int offset;
314	unsigned int num_bvecs;
315	sector_t remaining = where->count;
316	struct request_queue *q = bdev_get_queue(where->bdev);
317	sector_t num_sectors;
318	unsigned int special_cmd_max_sectors;
319	const enum req_op op = opf & REQ_OP_MASK;
320
321	/*
322	 * Reject unsupported discard and write same requests.
323	 */
324	if (op == REQ_OP_DISCARD)
325		special_cmd_max_sectors = bdev_max_discard_sectors(where->bdev);
326	else if (op == REQ_OP_WRITE_ZEROES)
327		special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
328	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) &&
329	    special_cmd_max_sectors == 0) {
330		atomic_inc(&io->count);
331		dec_count(io, region, BLK_STS_NOTSUPP);
332		return;
333	}
334
335	/*
336	 * where->count may be zero if op holds a flush and we need to
337	 * send a zero-sized flush.
338	 */
339	do {
340		/*
341		 * Allocate a suitably sized-bio.
342		 */
343		switch (op) {
344		case REQ_OP_DISCARD:
345		case REQ_OP_WRITE_ZEROES:
346			num_bvecs = 0;
347			break;
348		default:
349			num_bvecs = bio_max_segs(dm_sector_div_up(remaining,
350						(PAGE_SIZE >> SECTOR_SHIFT)));
351		}
352
353		bio = bio_alloc_bioset(where->bdev, num_bvecs, opf, GFP_NOIO,
354				       &io->client->bios);
355		bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
356		bio->bi_end_io = endio;
357		bio->bi_ioprio = ioprio;
358		store_io_and_region_in_bio(bio, io, region);
359
360		if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) {
361			num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
362			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
363			remaining -= num_sectors;
364		} else {
365			while (remaining) {
366				/*
367				 * Try and add as many pages as possible.
368				 */
369				dp->get_page(dp, &page, &len, &offset);
370				len = min(len, to_bytes(remaining));
371				if (!bio_add_page(bio, page, len, offset))
372					break;
373
374				offset = 0;
375				remaining -= to_sector(len);
376				dp->next_page(dp);
377			}
378		}
379
380		atomic_inc(&io->count);
381		submit_bio(bio);
382	} while (remaining);
383}
384
385static void dispatch_io(blk_opf_t opf, unsigned int num_regions,
386			struct dm_io_region *where, struct dpages *dp,
387			struct io *io, int sync, unsigned short ioprio)
388{
389	int i;
390	struct dpages old_pages = *dp;
391
392	BUG_ON(num_regions > DM_IO_MAX_REGIONS);
393
394	if (sync)
395		opf |= REQ_SYNC;
396
397	/*
398	 * For multiple regions we need to be careful to rewind
399	 * the dp object for each call to do_region.
400	 */
401	for (i = 0; i < num_regions; i++) {
402		*dp = old_pages;
403		if (where[i].count || (opf & REQ_PREFLUSH))
404			do_region(opf, i, where + i, dp, io, ioprio);
405	}
406
407	/*
408	 * Drop the extra reference that we were holding to avoid
409	 * the io being completed too early.
410	 */
411	dec_count(io, 0, 0);
412}
413
414struct sync_io {
415	unsigned long error_bits;
416	struct completion wait;
417};
418
419static void sync_io_complete(unsigned long error, void *context)
420{
421	struct sync_io *sio = context;
422
423	sio->error_bits = error;
424	complete(&sio->wait);
425}
426
427static int sync_io(struct dm_io_client *client, unsigned int num_regions,
428		   struct dm_io_region *where, blk_opf_t opf, struct dpages *dp,
429		   unsigned long *error_bits, unsigned short ioprio)
430{
431	struct io *io;
432	struct sync_io sio;
433
434	if (num_regions > 1 && !op_is_write(opf)) {
435		WARN_ON(1);
436		return -EIO;
437	}
438
439	init_completion(&sio.wait);
440
441	io = mempool_alloc(&client->pool, GFP_NOIO);
442	io->error_bits = 0;
443	atomic_set(&io->count, 1); /* see dispatch_io() */
444	io->client = client;
445	io->callback = sync_io_complete;
446	io->context = &sio;
447
448	io->vma_invalidate_address = dp->vma_invalidate_address;
449	io->vma_invalidate_size = dp->vma_invalidate_size;
450
451	dispatch_io(opf, num_regions, where, dp, io, 1, ioprio);
452
453	wait_for_completion_io(&sio.wait);
454
455	if (error_bits)
456		*error_bits = sio.error_bits;
457
458	return sio.error_bits ? -EIO : 0;
459}
460
461static int async_io(struct dm_io_client *client, unsigned int num_regions,
462		    struct dm_io_region *where, blk_opf_t opf,
463		    struct dpages *dp, io_notify_fn fn, void *context,
464		    unsigned short ioprio)
465{
466	struct io *io;
467
468	if (num_regions > 1 && !op_is_write(opf)) {
469		WARN_ON(1);
470		fn(1, context);
471		return -EIO;
472	}
473
474	io = mempool_alloc(&client->pool, GFP_NOIO);
475	io->error_bits = 0;
476	atomic_set(&io->count, 1); /* see dispatch_io() */
477	io->client = client;
478	io->callback = fn;
479	io->context = context;
480
481	io->vma_invalidate_address = dp->vma_invalidate_address;
482	io->vma_invalidate_size = dp->vma_invalidate_size;
483
484	dispatch_io(opf, num_regions, where, dp, io, 0, ioprio);
485	return 0;
486}
487
488static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
489		   unsigned long size)
490{
491	/* Set up dpages based on memory type */
492
493	dp->vma_invalidate_address = NULL;
494	dp->vma_invalidate_size = 0;
495
496	switch (io_req->mem.type) {
497	case DM_IO_PAGE_LIST:
498		list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
499		break;
500
501	case DM_IO_BIO:
502		bio_dp_init(dp, io_req->mem.ptr.bio);
503		break;
504
505	case DM_IO_VMA:
506		flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
507		if ((io_req->bi_opf & REQ_OP_MASK) == REQ_OP_READ) {
508			dp->vma_invalidate_address = io_req->mem.ptr.vma;
509			dp->vma_invalidate_size = size;
510		}
511		vm_dp_init(dp, io_req->mem.ptr.vma);
512		break;
513
514	case DM_IO_KMEM:
515		km_dp_init(dp, io_req->mem.ptr.addr);
516		break;
517
518	default:
519		return -EINVAL;
520	}
521
522	return 0;
523}
524
525int dm_io(struct dm_io_request *io_req, unsigned int num_regions,
526	  struct dm_io_region *where, unsigned long *sync_error_bits,
527	  unsigned short ioprio)
528{
529	int r;
530	struct dpages dp;
531
532	r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
533	if (r)
534		return r;
535
536	if (!io_req->notify.fn)
537		return sync_io(io_req->client, num_regions, where,
538			       io_req->bi_opf, &dp, sync_error_bits, ioprio);
539
540	return async_io(io_req->client, num_regions, where,
541			io_req->bi_opf, &dp, io_req->notify.fn,
542			io_req->notify.context, ioprio);
543}
544EXPORT_SYMBOL(dm_io);
545
546int __init dm_io_init(void)
547{
548	_dm_io_cache = KMEM_CACHE(io, 0);
549	if (!_dm_io_cache)
550		return -ENOMEM;
551
552	return 0;
553}
554
555void dm_io_exit(void)
556{
557	kmem_cache_destroy(_dm_io_cache);
558	_dm_io_cache = NULL;
559}
560