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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, ®ion);
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)) + 1);
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, 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 /*
395 * For multiple regions we need to be careful to rewind
396 * the dp object for each call to do_region.
397 */
398 for (i = 0; i < num_regions; i++) {
399 *dp = old_pages;
400 if (where[i].count || (opf & REQ_PREFLUSH))
401 do_region(opf, i, where + i, dp, io, ioprio);
402 }
403
404 /*
405 * Drop the extra reference that we were holding to avoid
406 * the io being completed too early.
407 */
408 dec_count(io, 0, 0);
409}
410
411static void async_io(struct dm_io_client *client, unsigned int num_regions,
412 struct dm_io_region *where, blk_opf_t opf,
413 struct dpages *dp, io_notify_fn fn, void *context,
414 unsigned short ioprio)
415{
416 struct io *io;
417
418 io = mempool_alloc(&client->pool, GFP_NOIO);
419 io->error_bits = 0;
420 atomic_set(&io->count, 1); /* see dispatch_io() */
421 io->client = client;
422 io->callback = fn;
423 io->context = context;
424
425 io->vma_invalidate_address = dp->vma_invalidate_address;
426 io->vma_invalidate_size = dp->vma_invalidate_size;
427
428 dispatch_io(opf, num_regions, where, dp, io, ioprio);
429}
430
431struct sync_io {
432 unsigned long error_bits;
433 struct completion wait;
434};
435
436static void sync_io_complete(unsigned long error, void *context)
437{
438 struct sync_io *sio = context;
439
440 sio->error_bits = error;
441 complete(&sio->wait);
442}
443
444static int sync_io(struct dm_io_client *client, unsigned int num_regions,
445 struct dm_io_region *where, blk_opf_t opf, struct dpages *dp,
446 unsigned long *error_bits, unsigned short ioprio)
447{
448 struct sync_io sio;
449
450 init_completion(&sio.wait);
451
452 async_io(client, num_regions, where, opf | REQ_SYNC, dp,
453 sync_io_complete, &sio, ioprio);
454
455 wait_for_completion_io(&sio.wait);
456
457 if (error_bits)
458 *error_bits = sio.error_bits;
459
460 return sio.error_bits ? -EIO : 0;
461}
462
463static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
464 unsigned long size)
465{
466 /* Set up dpages based on memory type */
467
468 dp->vma_invalidate_address = NULL;
469 dp->vma_invalidate_size = 0;
470
471 switch (io_req->mem.type) {
472 case DM_IO_PAGE_LIST:
473 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
474 break;
475
476 case DM_IO_BIO:
477 bio_dp_init(dp, io_req->mem.ptr.bio);
478 break;
479
480 case DM_IO_VMA:
481 flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
482 if ((io_req->bi_opf & REQ_OP_MASK) == REQ_OP_READ) {
483 dp->vma_invalidate_address = io_req->mem.ptr.vma;
484 dp->vma_invalidate_size = size;
485 }
486 vm_dp_init(dp, io_req->mem.ptr.vma);
487 break;
488
489 case DM_IO_KMEM:
490 km_dp_init(dp, io_req->mem.ptr.addr);
491 break;
492
493 default:
494 return -EINVAL;
495 }
496
497 return 0;
498}
499
500int dm_io(struct dm_io_request *io_req, unsigned int num_regions,
501 struct dm_io_region *where, unsigned long *sync_error_bits,
502 unsigned short ioprio)
503{
504 int r;
505 struct dpages dp;
506
507 if (num_regions > 1 && !op_is_write(io_req->bi_opf)) {
508 WARN_ON(1);
509 return -EIO;
510 }
511
512 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
513 if (r)
514 return r;
515
516 if (!io_req->notify.fn)
517 return sync_io(io_req->client, num_regions, where,
518 io_req->bi_opf, &dp, sync_error_bits, ioprio);
519
520 async_io(io_req->client, num_regions, where, io_req->bi_opf, &dp,
521 io_req->notify.fn, io_req->notify.context, ioprio);
522 return 0;
523}
524EXPORT_SYMBOL(dm_io);
525
526int __init dm_io_init(void)
527{
528 _dm_io_cache = KMEM_CACHE(io, 0);
529 if (!_dm_io_cache)
530 return -ENOMEM;
531
532 return 0;
533}
534
535void dm_io_exit(void)
536{
537 kmem_cache_destroy(_dm_io_cache);
538 _dm_io_cache = NULL;
539}
1/*
2 * Copyright (C) 2003 Sistina Software
3 * Copyright (C) 2006 Red Hat GmbH
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9
10#include <linux/device-mapper.h>
11
12#include <linux/bio.h>
13#include <linux/mempool.h>
14#include <linux/module.h>
15#include <linux/sched.h>
16#include <linux/slab.h>
17#include <linux/dm-io.h>
18
19#define DM_MSG_PREFIX "io"
20
21#define DM_IO_MAX_REGIONS BITS_PER_LONG
22#define MIN_IOS 16
23#define MIN_BIOS 16
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 task_struct *sleeper;
38 struct dm_io_client *client;
39 io_notify_fn callback;
40 void *context;
41 void *vma_invalidate_address;
42 unsigned long vma_invalidate_size;
43} __attribute__((aligned(DM_IO_MAX_REGIONS)));
44
45static struct kmem_cache *_dm_io_cache;
46
47/*
48 * Create a client with mempool and bioset.
49 */
50struct dm_io_client *dm_io_client_create(void)
51{
52 struct dm_io_client *client;
53
54 client = kmalloc(sizeof(*client), GFP_KERNEL);
55 if (!client)
56 return ERR_PTR(-ENOMEM);
57
58 client->pool = mempool_create_slab_pool(MIN_IOS, _dm_io_cache);
59 if (!client->pool)
60 goto bad;
61
62 client->bios = bioset_create(MIN_BIOS, 0);
63 if (!client->bios)
64 goto bad;
65
66 return client;
67
68 bad:
69 if (client->pool)
70 mempool_destroy(client->pool);
71 kfree(client);
72 return ERR_PTR(-ENOMEM);
73}
74EXPORT_SYMBOL(dm_io_client_create);
75
76void dm_io_client_destroy(struct dm_io_client *client)
77{
78 mempool_destroy(client->pool);
79 bioset_free(client->bios);
80 kfree(client);
81}
82EXPORT_SYMBOL(dm_io_client_destroy);
83
84/*-----------------------------------------------------------------
85 * We need to keep track of which region a bio is doing io for.
86 * To avoid a memory allocation to store just 5 or 6 bits, we
87 * ensure the 'struct io' pointer is aligned so enough low bits are
88 * always zero and then combine it with the region number directly in
89 * bi_private.
90 *---------------------------------------------------------------*/
91static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
92 unsigned region)
93{
94 if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
95 DMCRIT("Unaligned struct io pointer %p", io);
96 BUG();
97 }
98
99 bio->bi_private = (void *)((unsigned long)io | region);
100}
101
102static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
103 unsigned *region)
104{
105 unsigned long val = (unsigned long)bio->bi_private;
106
107 *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
108 *region = val & (DM_IO_MAX_REGIONS - 1);
109}
110
111/*-----------------------------------------------------------------
112 * We need an io object to keep track of the number of bios that
113 * have been dispatched for a particular io.
114 *---------------------------------------------------------------*/
115static void dec_count(struct io *io, unsigned int region, int error)
116{
117 if (error)
118 set_bit(region, &io->error_bits);
119
120 if (atomic_dec_and_test(&io->count)) {
121 if (io->vma_invalidate_size)
122 invalidate_kernel_vmap_range(io->vma_invalidate_address,
123 io->vma_invalidate_size);
124
125 if (io->sleeper)
126 wake_up_process(io->sleeper);
127
128 else {
129 unsigned long r = io->error_bits;
130 io_notify_fn fn = io->callback;
131 void *context = io->context;
132
133 mempool_free(io, io->client->pool);
134 fn(r, context);
135 }
136 }
137}
138
139static void endio(struct bio *bio, int error)
140{
141 struct io *io;
142 unsigned region;
143
144 if (error && bio_data_dir(bio) == READ)
145 zero_fill_bio(bio);
146
147 /*
148 * The bio destructor in bio_put() may use the io object.
149 */
150 retrieve_io_and_region_from_bio(bio, &io, ®ion);
151
152 bio_put(bio);
153
154 dec_count(io, region, error);
155}
156
157/*-----------------------------------------------------------------
158 * These little objects provide an abstraction for getting a new
159 * destination page for io.
160 *---------------------------------------------------------------*/
161struct dpages {
162 void (*get_page)(struct dpages *dp,
163 struct page **p, unsigned long *len, unsigned *offset);
164 void (*next_page)(struct dpages *dp);
165
166 unsigned context_u;
167 void *context_ptr;
168
169 void *vma_invalidate_address;
170 unsigned long vma_invalidate_size;
171};
172
173/*
174 * Functions for getting the pages from a list.
175 */
176static void list_get_page(struct dpages *dp,
177 struct page **p, unsigned long *len, unsigned *offset)
178{
179 unsigned o = dp->context_u;
180 struct page_list *pl = (struct page_list *) dp->context_ptr;
181
182 *p = pl->page;
183 *len = PAGE_SIZE - o;
184 *offset = o;
185}
186
187static void list_next_page(struct dpages *dp)
188{
189 struct page_list *pl = (struct page_list *) dp->context_ptr;
190 dp->context_ptr = pl->next;
191 dp->context_u = 0;
192}
193
194static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
195{
196 dp->get_page = list_get_page;
197 dp->next_page = list_next_page;
198 dp->context_u = offset;
199 dp->context_ptr = pl;
200}
201
202/*
203 * Functions for getting the pages from a bvec.
204 */
205static void bvec_get_page(struct dpages *dp,
206 struct page **p, unsigned long *len, unsigned *offset)
207{
208 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
209 *p = bvec->bv_page;
210 *len = bvec->bv_len;
211 *offset = bvec->bv_offset;
212}
213
214static void bvec_next_page(struct dpages *dp)
215{
216 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
217 dp->context_ptr = bvec + 1;
218}
219
220static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
221{
222 dp->get_page = bvec_get_page;
223 dp->next_page = bvec_next_page;
224 dp->context_ptr = bvec;
225}
226
227/*
228 * Functions for getting the pages from a VMA.
229 */
230static void vm_get_page(struct dpages *dp,
231 struct page **p, unsigned long *len, unsigned *offset)
232{
233 *p = vmalloc_to_page(dp->context_ptr);
234 *offset = dp->context_u;
235 *len = PAGE_SIZE - dp->context_u;
236}
237
238static void vm_next_page(struct dpages *dp)
239{
240 dp->context_ptr += PAGE_SIZE - dp->context_u;
241 dp->context_u = 0;
242}
243
244static void vm_dp_init(struct dpages *dp, void *data)
245{
246 dp->get_page = vm_get_page;
247 dp->next_page = vm_next_page;
248 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
249 dp->context_ptr = data;
250}
251
252static void dm_bio_destructor(struct bio *bio)
253{
254 unsigned region;
255 struct io *io;
256
257 retrieve_io_and_region_from_bio(bio, &io, ®ion);
258
259 bio_free(bio, io->client->bios);
260}
261
262/*
263 * Functions for getting the pages from kernel memory.
264 */
265static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
266 unsigned *offset)
267{
268 *p = virt_to_page(dp->context_ptr);
269 *offset = dp->context_u;
270 *len = PAGE_SIZE - dp->context_u;
271}
272
273static void km_next_page(struct dpages *dp)
274{
275 dp->context_ptr += PAGE_SIZE - dp->context_u;
276 dp->context_u = 0;
277}
278
279static void km_dp_init(struct dpages *dp, void *data)
280{
281 dp->get_page = km_get_page;
282 dp->next_page = km_next_page;
283 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
284 dp->context_ptr = data;
285}
286
287/*-----------------------------------------------------------------
288 * IO routines that accept a list of pages.
289 *---------------------------------------------------------------*/
290static void do_region(int rw, unsigned region, struct dm_io_region *where,
291 struct dpages *dp, struct io *io)
292{
293 struct bio *bio;
294 struct page *page;
295 unsigned long len;
296 unsigned offset;
297 unsigned num_bvecs;
298 sector_t remaining = where->count;
299
300 /*
301 * where->count may be zero if rw holds a flush and we need to
302 * send a zero-sized flush.
303 */
304 do {
305 /*
306 * Allocate a suitably sized-bio.
307 */
308 num_bvecs = dm_sector_div_up(remaining,
309 (PAGE_SIZE >> SECTOR_SHIFT));
310 num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev), num_bvecs);
311 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
312 bio->bi_sector = where->sector + (where->count - remaining);
313 bio->bi_bdev = where->bdev;
314 bio->bi_end_io = endio;
315 bio->bi_destructor = dm_bio_destructor;
316 store_io_and_region_in_bio(bio, io, region);
317
318 /*
319 * Try and add as many pages as possible.
320 */
321 while (remaining) {
322 dp->get_page(dp, &page, &len, &offset);
323 len = min(len, to_bytes(remaining));
324 if (!bio_add_page(bio, page, len, offset))
325 break;
326
327 offset = 0;
328 remaining -= to_sector(len);
329 dp->next_page(dp);
330 }
331
332 atomic_inc(&io->count);
333 submit_bio(rw, bio);
334 } while (remaining);
335}
336
337static void dispatch_io(int rw, unsigned int num_regions,
338 struct dm_io_region *where, struct dpages *dp,
339 struct io *io, int sync)
340{
341 int i;
342 struct dpages old_pages = *dp;
343
344 BUG_ON(num_regions > DM_IO_MAX_REGIONS);
345
346 if (sync)
347 rw |= REQ_SYNC;
348
349 /*
350 * For multiple regions we need to be careful to rewind
351 * the dp object for each call to do_region.
352 */
353 for (i = 0; i < num_regions; i++) {
354 *dp = old_pages;
355 if (where[i].count || (rw & REQ_FLUSH))
356 do_region(rw, i, where + i, dp, io);
357 }
358
359 /*
360 * Drop the extra reference that we were holding to avoid
361 * the io being completed too early.
362 */
363 dec_count(io, 0, 0);
364}
365
366static int sync_io(struct dm_io_client *client, unsigned int num_regions,
367 struct dm_io_region *where, int rw, struct dpages *dp,
368 unsigned long *error_bits)
369{
370 /*
371 * gcc <= 4.3 can't do the alignment for stack variables, so we must
372 * align it on our own.
373 * volatile prevents the optimizer from removing or reusing
374 * "io_" field from the stack frame (allowed in ANSI C).
375 */
376 volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
377 struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));
378
379 if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
380 WARN_ON(1);
381 return -EIO;
382 }
383
384 io->error_bits = 0;
385 atomic_set(&io->count, 1); /* see dispatch_io() */
386 io->sleeper = current;
387 io->client = client;
388
389 io->vma_invalidate_address = dp->vma_invalidate_address;
390 io->vma_invalidate_size = dp->vma_invalidate_size;
391
392 dispatch_io(rw, num_regions, where, dp, io, 1);
393
394 while (1) {
395 set_current_state(TASK_UNINTERRUPTIBLE);
396
397 if (!atomic_read(&io->count))
398 break;
399
400 io_schedule();
401 }
402 set_current_state(TASK_RUNNING);
403
404 if (error_bits)
405 *error_bits = io->error_bits;
406
407 return io->error_bits ? -EIO : 0;
408}
409
410static int async_io(struct dm_io_client *client, unsigned int num_regions,
411 struct dm_io_region *where, int rw, struct dpages *dp,
412 io_notify_fn fn, void *context)
413{
414 struct io *io;
415
416 if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
417 WARN_ON(1);
418 fn(1, context);
419 return -EIO;
420 }
421
422 io = mempool_alloc(client->pool, GFP_NOIO);
423 io->error_bits = 0;
424 atomic_set(&io->count, 1); /* see dispatch_io() */
425 io->sleeper = NULL;
426 io->client = client;
427 io->callback = fn;
428 io->context = context;
429
430 io->vma_invalidate_address = dp->vma_invalidate_address;
431 io->vma_invalidate_size = dp->vma_invalidate_size;
432
433 dispatch_io(rw, num_regions, where, dp, io, 0);
434 return 0;
435}
436
437static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
438 unsigned long size)
439{
440 /* Set up dpages based on memory type */
441
442 dp->vma_invalidate_address = NULL;
443 dp->vma_invalidate_size = 0;
444
445 switch (io_req->mem.type) {
446 case DM_IO_PAGE_LIST:
447 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
448 break;
449
450 case DM_IO_BVEC:
451 bvec_dp_init(dp, io_req->mem.ptr.bvec);
452 break;
453
454 case DM_IO_VMA:
455 flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
456 if ((io_req->bi_rw & RW_MASK) == READ) {
457 dp->vma_invalidate_address = io_req->mem.ptr.vma;
458 dp->vma_invalidate_size = size;
459 }
460 vm_dp_init(dp, io_req->mem.ptr.vma);
461 break;
462
463 case DM_IO_KMEM:
464 km_dp_init(dp, io_req->mem.ptr.addr);
465 break;
466
467 default:
468 return -EINVAL;
469 }
470
471 return 0;
472}
473
474/*
475 * New collapsed (a)synchronous interface.
476 *
477 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
478 * the queue with blk_unplug() some time later or set REQ_SYNC in
479io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
480 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
481 */
482int dm_io(struct dm_io_request *io_req, unsigned num_regions,
483 struct dm_io_region *where, unsigned long *sync_error_bits)
484{
485 int r;
486 struct dpages dp;
487
488 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
489 if (r)
490 return r;
491
492 if (!io_req->notify.fn)
493 return sync_io(io_req->client, num_regions, where,
494 io_req->bi_rw, &dp, sync_error_bits);
495
496 return async_io(io_req->client, num_regions, where, io_req->bi_rw,
497 &dp, io_req->notify.fn, io_req->notify.context);
498}
499EXPORT_SYMBOL(dm_io);
500
501int __init dm_io_init(void)
502{
503 _dm_io_cache = KMEM_CACHE(io, 0);
504 if (!_dm_io_cache)
505 return -ENOMEM;
506
507 return 0;
508}
509
510void dm_io_exit(void)
511{
512 kmem_cache_destroy(_dm_io_cache);
513 _dm_io_cache = NULL;
514}