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