Line data Source code
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 : */
48 0 : struct dm_io_client *dm_io_client_create(void)
49 : {
50 0 : struct dm_io_client *client;
51 0 : unsigned min_ios = dm_get_reserved_bio_based_ios();
52 0 : int ret;
53 :
54 0 : client = kzalloc(sizeof(*client), GFP_KERNEL);
55 0 : if (!client)
56 0 : return ERR_PTR(-ENOMEM);
57 :
58 0 : ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache);
59 0 : if (ret)
60 0 : goto bad;
61 :
62 0 : ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS);
63 0 : if (ret)
64 0 : goto bad;
65 :
66 : return client;
67 :
68 0 : bad:
69 0 : mempool_exit(&client->pool);
70 0 : kfree(client);
71 0 : return ERR_PTR(ret);
72 : }
73 : EXPORT_SYMBOL(dm_io_client_create);
74 :
75 0 : void dm_io_client_destroy(struct dm_io_client *client)
76 : {
77 0 : mempool_exit(&client->pool);
78 0 : bioset_exit(&client->bios);
79 0 : kfree(client);
80 0 : }
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 : *---------------------------------------------------------------*/
90 0 : static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
91 : unsigned region)
92 : {
93 0 : if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
94 0 : DMCRIT("Unaligned struct io pointer %p", io);
95 0 : BUG();
96 : }
97 :
98 0 : bio->bi_private = (void *)((unsigned long)io | region);
99 0 : }
100 :
101 0 : static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
102 : unsigned *region)
103 : {
104 0 : unsigned long val = (unsigned long)bio->bi_private;
105 :
106 0 : *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
107 0 : *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 : *---------------------------------------------------------------*/
114 0 : static void complete_io(struct io *io)
115 : {
116 0 : unsigned long error_bits = io->error_bits;
117 0 : io_notify_fn fn = io->callback;
118 0 : void *context = io->context;
119 :
120 0 : if (io->vma_invalidate_size)
121 0 : invalidate_kernel_vmap_range(io->vma_invalidate_address,
122 : io->vma_invalidate_size);
123 :
124 0 : mempool_free(io, &io->client->pool);
125 0 : fn(error_bits, context);
126 0 : }
127 :
128 0 : static void dec_count(struct io *io, unsigned int region, blk_status_t error)
129 : {
130 0 : if (error)
131 0 : set_bit(region, &io->error_bits);
132 :
133 0 : if (atomic_dec_and_test(&io->count))
134 0 : complete_io(io);
135 0 : }
136 :
137 0 : static void endio(struct bio *bio)
138 : {
139 0 : struct io *io;
140 0 : unsigned region;
141 0 : blk_status_t error;
142 :
143 0 : if (bio->bi_status && bio_data_dir(bio) == READ)
144 0 : zero_fill_bio(bio);
145 :
146 : /*
147 : * The bio destructor in bio_put() may use the io object.
148 : */
149 0 : retrieve_io_and_region_from_bio(bio, &io, ®ion);
150 :
151 0 : error = bio->bi_status;
152 0 : bio_put(bio);
153 :
154 0 : dec_count(io, region, error);
155 0 : }
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 : */
179 0 : static void list_get_page(struct dpages *dp,
180 : struct page **p, unsigned long *len, unsigned *offset)
181 : {
182 0 : unsigned o = dp->context_u;
183 0 : struct page_list *pl = (struct page_list *) dp->context_ptr;
184 :
185 0 : *p = pl->page;
186 0 : *len = PAGE_SIZE - o;
187 0 : *offset = o;
188 0 : }
189 :
190 0 : static void list_next_page(struct dpages *dp)
191 : {
192 0 : struct page_list *pl = (struct page_list *) dp->context_ptr;
193 0 : dp->context_ptr = pl->next;
194 0 : dp->context_u = 0;
195 0 : }
196 :
197 0 : static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
198 : {
199 0 : dp->get_page = list_get_page;
200 0 : dp->next_page = list_next_page;
201 0 : dp->context_u = offset;
202 0 : dp->context_ptr = pl;
203 0 : }
204 :
205 : /*
206 : * Functions for getting the pages from a bvec.
207 : */
208 0 : static void bio_get_page(struct dpages *dp, struct page **p,
209 : unsigned long *len, unsigned *offset)
210 : {
211 0 : struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr,
212 : dp->context_bi);
213 :
214 0 : *p = bvec.bv_page;
215 0 : *len = bvec.bv_len;
216 0 : *offset = bvec.bv_offset;
217 :
218 : /* avoid figuring it out again in bio_next_page() */
219 0 : dp->context_bi.bi_sector = (sector_t)bvec.bv_len;
220 0 : }
221 :
222 0 : static void bio_next_page(struct dpages *dp)
223 : {
224 0 : unsigned int len = (unsigned int)dp->context_bi.bi_sector;
225 :
226 0 : bvec_iter_advance((struct bio_vec *)dp->context_ptr,
227 : &dp->context_bi, len);
228 0 : }
229 :
230 0 : static void bio_dp_init(struct dpages *dp, struct bio *bio)
231 : {
232 0 : dp->get_page = bio_get_page;
233 0 : 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 0 : dp->context_ptr = bio->bi_io_vec;
240 0 : dp->context_bi = bio->bi_iter;
241 0 : }
242 :
243 : /*
244 : * Functions for getting the pages from a VMA.
245 : */
246 0 : static void vm_get_page(struct dpages *dp,
247 : struct page **p, unsigned long *len, unsigned *offset)
248 : {
249 0 : *p = vmalloc_to_page(dp->context_ptr);
250 0 : *offset = dp->context_u;
251 0 : *len = PAGE_SIZE - dp->context_u;
252 0 : }
253 :
254 0 : static void vm_next_page(struct dpages *dp)
255 : {
256 0 : dp->context_ptr += PAGE_SIZE - dp->context_u;
257 0 : dp->context_u = 0;
258 0 : }
259 :
260 0 : static void vm_dp_init(struct dpages *dp, void *data)
261 : {
262 0 : dp->get_page = vm_get_page;
263 0 : dp->next_page = vm_next_page;
264 0 : dp->context_u = offset_in_page(data);
265 0 : dp->context_ptr = data;
266 0 : }
267 :
268 : /*
269 : * Functions for getting the pages from kernel memory.
270 : */
271 0 : static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
272 : unsigned *offset)
273 : {
274 0 : *p = virt_to_page(dp->context_ptr);
275 0 : *offset = dp->context_u;
276 0 : *len = PAGE_SIZE - dp->context_u;
277 0 : }
278 :
279 0 : static void km_next_page(struct dpages *dp)
280 : {
281 0 : dp->context_ptr += PAGE_SIZE - dp->context_u;
282 0 : dp->context_u = 0;
283 0 : }
284 :
285 0 : static void km_dp_init(struct dpages *dp, void *data)
286 : {
287 0 : dp->get_page = km_get_page;
288 0 : dp->next_page = km_next_page;
289 0 : dp->context_u = offset_in_page(data);
290 0 : dp->context_ptr = data;
291 0 : }
292 :
293 : /*-----------------------------------------------------------------
294 : * IO routines that accept a list of pages.
295 : *---------------------------------------------------------------*/
296 0 : static void do_region(int op, int op_flags, unsigned region,
297 : struct dm_io_region *where, struct dpages *dp,
298 : struct io *io)
299 : {
300 0 : struct bio *bio;
301 0 : struct page *page;
302 0 : unsigned long len;
303 0 : unsigned offset;
304 0 : unsigned num_bvecs;
305 0 : sector_t remaining = where->count;
306 0 : struct request_queue *q = bdev_get_queue(where->bdev);
307 0 : unsigned short logical_block_size = queue_logical_block_size(q);
308 0 : sector_t num_sectors;
309 0 : unsigned int special_cmd_max_sectors;
310 :
311 : /*
312 : * Reject unsupported discard and write same requests.
313 : */
314 0 : if (op == REQ_OP_DISCARD)
315 0 : special_cmd_max_sectors = q->limits.max_discard_sectors;
316 0 : else if (op == REQ_OP_WRITE_ZEROES)
317 0 : special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
318 0 : else if (op == REQ_OP_WRITE_SAME)
319 0 : special_cmd_max_sectors = q->limits.max_write_same_sectors;
320 0 : if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES ||
321 0 : op == REQ_OP_WRITE_SAME) && special_cmd_max_sectors == 0) {
322 0 : atomic_inc(&io->count);
323 0 : dec_count(io, region, BLK_STS_NOTSUPP);
324 0 : return;
325 : }
326 :
327 : /*
328 : * where->count may be zero if op holds a flush and we need to
329 : * send a zero-sized flush.
330 : */
331 0 : do {
332 : /*
333 : * Allocate a suitably sized-bio.
334 : */
335 0 : switch (op) {
336 : case REQ_OP_DISCARD:
337 : case REQ_OP_WRITE_ZEROES:
338 : num_bvecs = 0;
339 : break;
340 0 : case REQ_OP_WRITE_SAME:
341 0 : num_bvecs = 1;
342 0 : break;
343 0 : default:
344 0 : num_bvecs = bio_max_segs(dm_sector_div_up(remaining,
345 : (PAGE_SIZE >> SECTOR_SHIFT)));
346 : }
347 :
348 0 : bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, &io->client->bios);
349 0 : bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
350 0 : bio_set_dev(bio, where->bdev);
351 0 : bio->bi_end_io = endio;
352 0 : bio_set_op_attrs(bio, op, op_flags);
353 0 : store_io_and_region_in_bio(bio, io, region);
354 :
355 0 : if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) {
356 0 : num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
357 0 : bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
358 0 : remaining -= num_sectors;
359 0 : } else if (op == REQ_OP_WRITE_SAME) {
360 : /*
361 : * WRITE SAME only uses a single page.
362 : */
363 0 : dp->get_page(dp, &page, &len, &offset);
364 0 : bio_add_page(bio, page, logical_block_size, offset);
365 0 : num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
366 0 : bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
367 :
368 0 : offset = 0;
369 0 : remaining -= num_sectors;
370 0 : dp->next_page(dp);
371 0 : } else while (remaining) {
372 : /*
373 : * Try and add as many pages as possible.
374 : */
375 0 : dp->get_page(dp, &page, &len, &offset);
376 0 : len = min(len, to_bytes(remaining));
377 0 : if (!bio_add_page(bio, page, len, offset))
378 : break;
379 :
380 0 : offset = 0;
381 0 : remaining -= to_sector(len);
382 0 : dp->next_page(dp);
383 : }
384 :
385 0 : atomic_inc(&io->count);
386 0 : submit_bio(bio);
387 0 : } while (remaining);
388 : }
389 :
390 0 : static void dispatch_io(int op, int op_flags, unsigned int num_regions,
391 : struct dm_io_region *where, struct dpages *dp,
392 : struct io *io, int sync)
393 : {
394 0 : int i;
395 0 : struct dpages old_pages = *dp;
396 :
397 0 : BUG_ON(num_regions > DM_IO_MAX_REGIONS);
398 :
399 0 : if (sync)
400 0 : op_flags |= REQ_SYNC;
401 :
402 : /*
403 : * For multiple regions we need to be careful to rewind
404 : * the dp object for each call to do_region.
405 : */
406 0 : for (i = 0; i < num_regions; i++) {
407 0 : *dp = old_pages;
408 0 : if (where[i].count || (op_flags & REQ_PREFLUSH))
409 0 : do_region(op, op_flags, i, where + i, dp, io);
410 : }
411 :
412 : /*
413 : * Drop the extra reference that we were holding to avoid
414 : * the io being completed too early.
415 : */
416 0 : dec_count(io, 0, 0);
417 0 : }
418 :
419 : struct sync_io {
420 : unsigned long error_bits;
421 : struct completion wait;
422 : };
423 :
424 0 : static void sync_io_complete(unsigned long error, void *context)
425 : {
426 0 : struct sync_io *sio = context;
427 :
428 0 : sio->error_bits = error;
429 0 : complete(&sio->wait);
430 0 : }
431 :
432 0 : static int sync_io(struct dm_io_client *client, unsigned int num_regions,
433 : struct dm_io_region *where, int op, int op_flags,
434 : struct dpages *dp, unsigned long *error_bits)
435 : {
436 0 : struct io *io;
437 0 : struct sync_io sio;
438 :
439 0 : if (num_regions > 1 && !op_is_write(op)) {
440 0 : WARN_ON(1);
441 0 : return -EIO;
442 : }
443 :
444 0 : init_completion(&sio.wait);
445 :
446 0 : io = mempool_alloc(&client->pool, GFP_NOIO);
447 0 : io->error_bits = 0;
448 0 : atomic_set(&io->count, 1); /* see dispatch_io() */
449 0 : io->client = client;
450 0 : io->callback = sync_io_complete;
451 0 : io->context = &sio;
452 :
453 0 : io->vma_invalidate_address = dp->vma_invalidate_address;
454 0 : io->vma_invalidate_size = dp->vma_invalidate_size;
455 :
456 0 : dispatch_io(op, op_flags, num_regions, where, dp, io, 1);
457 :
458 0 : wait_for_completion_io(&sio.wait);
459 :
460 0 : if (error_bits)
461 0 : *error_bits = sio.error_bits;
462 :
463 0 : return sio.error_bits ? -EIO : 0;
464 : }
465 :
466 0 : static int async_io(struct dm_io_client *client, unsigned int num_regions,
467 : struct dm_io_region *where, int op, int op_flags,
468 : struct dpages *dp, io_notify_fn fn, void *context)
469 : {
470 0 : struct io *io;
471 :
472 0 : if (num_regions > 1 && !op_is_write(op)) {
473 0 : WARN_ON(1);
474 0 : fn(1, context);
475 0 : return -EIO;
476 : }
477 :
478 0 : io = mempool_alloc(&client->pool, GFP_NOIO);
479 0 : io->error_bits = 0;
480 0 : atomic_set(&io->count, 1); /* see dispatch_io() */
481 0 : io->client = client;
482 0 : io->callback = fn;
483 0 : io->context = context;
484 :
485 0 : io->vma_invalidate_address = dp->vma_invalidate_address;
486 0 : io->vma_invalidate_size = dp->vma_invalidate_size;
487 :
488 0 : dispatch_io(op, op_flags, num_regions, where, dp, io, 0);
489 0 : return 0;
490 : }
491 :
492 0 : static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
493 : unsigned long size)
494 : {
495 : /* Set up dpages based on memory type */
496 :
497 0 : dp->vma_invalidate_address = NULL;
498 0 : dp->vma_invalidate_size = 0;
499 :
500 0 : switch (io_req->mem.type) {
501 0 : case DM_IO_PAGE_LIST:
502 0 : list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
503 : break;
504 :
505 0 : case DM_IO_BIO:
506 0 : bio_dp_init(dp, io_req->mem.ptr.bio);
507 : break;
508 :
509 0 : case DM_IO_VMA:
510 0 : flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
511 0 : if (io_req->bi_op == REQ_OP_READ) {
512 0 : dp->vma_invalidate_address = io_req->mem.ptr.vma;
513 0 : dp->vma_invalidate_size = size;
514 : }
515 0 : vm_dp_init(dp, io_req->mem.ptr.vma);
516 : break;
517 :
518 0 : case DM_IO_KMEM:
519 0 : km_dp_init(dp, io_req->mem.ptr.addr);
520 : break;
521 :
522 : default:
523 : return -EINVAL;
524 : }
525 :
526 : return 0;
527 : }
528 :
529 : /*
530 : * New collapsed (a)synchronous interface.
531 : *
532 : * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
533 : * the queue with blk_unplug() some time later or set REQ_SYNC in
534 : * io_req->bi_opf. If you fail to do one of these, the IO will be submitted to
535 : * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
536 : */
537 0 : int dm_io(struct dm_io_request *io_req, unsigned num_regions,
538 : struct dm_io_region *where, unsigned long *sync_error_bits)
539 : {
540 0 : int r;
541 0 : struct dpages dp;
542 :
543 0 : r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
544 0 : if (r)
545 : return r;
546 :
547 0 : if (!io_req->notify.fn)
548 0 : return sync_io(io_req->client, num_regions, where,
549 : io_req->bi_op, io_req->bi_op_flags, &dp,
550 : sync_error_bits);
551 :
552 0 : return async_io(io_req->client, num_regions, where, io_req->bi_op,
553 : io_req->bi_op_flags, &dp, io_req->notify.fn,
554 : io_req->notify.context);
555 : }
556 : EXPORT_SYMBOL(dm_io);
557 :
558 1 : int __init dm_io_init(void)
559 : {
560 1 : _dm_io_cache = KMEM_CACHE(io, 0);
561 1 : if (!_dm_io_cache)
562 0 : return -ENOMEM;
563 :
564 : return 0;
565 : }
566 :
567 0 : void dm_io_exit(void)
568 : {
569 0 : kmem_cache_destroy(_dm_io_cache);
570 0 : _dm_io_cache = NULL;
571 0 : }
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