xref: /openbmc/linux/drivers/md/dm-io.c (revision b34e08d5)
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 
23 struct dm_io_client {
24 	mempool_t *pool;
25 	struct bio_set *bios;
26 };
27 
28 /*
29  * Aligning 'struct io' reduces the number of bits required to store
30  * its address.  Refer to store_io_and_region_in_bio() below.
31  */
32 struct io {
33 	unsigned long error_bits;
34 	atomic_t count;
35 	struct task_struct *sleeper;
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 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 
53 	client = kmalloc(sizeof(*client), GFP_KERNEL);
54 	if (!client)
55 		return ERR_PTR(-ENOMEM);
56 
57 	client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache);
58 	if (!client->pool)
59 		goto bad;
60 
61 	client->bios = bioset_create(min_ios, 0);
62 	if (!client->bios)
63 		goto bad;
64 
65 	return client;
66 
67    bad:
68 	if (client->pool)
69 		mempool_destroy(client->pool);
70 	kfree(client);
71 	return ERR_PTR(-ENOMEM);
72 }
73 EXPORT_SYMBOL(dm_io_client_create);
74 
75 void dm_io_client_destroy(struct dm_io_client *client)
76 {
77 	mempool_destroy(client->pool);
78 	bioset_free(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  *---------------------------------------------------------------*/
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 
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  *---------------------------------------------------------------*/
114 static void dec_count(struct io *io, unsigned int region, int error)
115 {
116 	if (error)
117 		set_bit(region, &io->error_bits);
118 
119 	if (atomic_dec_and_test(&io->count)) {
120 		if (io->vma_invalidate_size)
121 			invalidate_kernel_vmap_range(io->vma_invalidate_address,
122 						     io->vma_invalidate_size);
123 
124 		if (io->sleeper)
125 			wake_up_process(io->sleeper);
126 
127 		else {
128 			unsigned long r = io->error_bits;
129 			io_notify_fn fn = io->callback;
130 			void *context = io->context;
131 
132 			mempool_free(io, io->client->pool);
133 			fn(r, context);
134 		}
135 	}
136 }
137 
138 static void endio(struct bio *bio, int error)
139 {
140 	struct io *io;
141 	unsigned region;
142 
143 	if (error && 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, &region);
150 
151 	bio_put(bio);
152 
153 	dec_count(io, region, error);
154 }
155 
156 /*-----------------------------------------------------------------
157  * These little objects provide an abstraction for getting a new
158  * destination page for io.
159  *---------------------------------------------------------------*/
160 struct dpages {
161 	void (*get_page)(struct dpages *dp,
162 			 struct page **p, unsigned long *len, unsigned *offset);
163 	void (*next_page)(struct dpages *dp);
164 
165 	unsigned context_u;
166 	void *context_ptr;
167 
168 	void *vma_invalidate_address;
169 	unsigned long vma_invalidate_size;
170 };
171 
172 /*
173  * Functions for getting the pages from a list.
174  */
175 static void list_get_page(struct dpages *dp,
176 		  struct page **p, unsigned long *len, unsigned *offset)
177 {
178 	unsigned o = dp->context_u;
179 	struct page_list *pl = (struct page_list *) dp->context_ptr;
180 
181 	*p = pl->page;
182 	*len = PAGE_SIZE - o;
183 	*offset = o;
184 }
185 
186 static void list_next_page(struct dpages *dp)
187 {
188 	struct page_list *pl = (struct page_list *) dp->context_ptr;
189 	dp->context_ptr = pl->next;
190 	dp->context_u = 0;
191 }
192 
193 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
194 {
195 	dp->get_page = list_get_page;
196 	dp->next_page = list_next_page;
197 	dp->context_u = offset;
198 	dp->context_ptr = pl;
199 }
200 
201 /*
202  * Functions for getting the pages from a bvec.
203  */
204 static void bio_get_page(struct dpages *dp, struct page **p,
205 			 unsigned long *len, unsigned *offset)
206 {
207 	struct bio_vec *bvec = dp->context_ptr;
208 	*p = bvec->bv_page;
209 	*len = bvec->bv_len - dp->context_u;
210 	*offset = bvec->bv_offset + dp->context_u;
211 }
212 
213 static void bio_next_page(struct dpages *dp)
214 {
215 	struct bio_vec *bvec = dp->context_ptr;
216 	dp->context_ptr = bvec + 1;
217 	dp->context_u = 0;
218 }
219 
220 static void bio_dp_init(struct dpages *dp, struct bio *bio)
221 {
222 	dp->get_page = bio_get_page;
223 	dp->next_page = bio_next_page;
224 	dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
225 	dp->context_u = bio->bi_iter.bi_bvec_done;
226 }
227 
228 /*
229  * Functions for getting the pages from a VMA.
230  */
231 static void vm_get_page(struct dpages *dp,
232 		 struct page **p, unsigned long *len, unsigned *offset)
233 {
234 	*p = vmalloc_to_page(dp->context_ptr);
235 	*offset = dp->context_u;
236 	*len = PAGE_SIZE - dp->context_u;
237 }
238 
239 static void vm_next_page(struct dpages *dp)
240 {
241 	dp->context_ptr += PAGE_SIZE - dp->context_u;
242 	dp->context_u = 0;
243 }
244 
245 static void vm_dp_init(struct dpages *dp, void *data)
246 {
247 	dp->get_page = vm_get_page;
248 	dp->next_page = vm_next_page;
249 	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
250 	dp->context_ptr = data;
251 }
252 
253 /*
254  * Functions for getting the pages from kernel memory.
255  */
256 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
257 			unsigned *offset)
258 {
259 	*p = virt_to_page(dp->context_ptr);
260 	*offset = dp->context_u;
261 	*len = PAGE_SIZE - dp->context_u;
262 }
263 
264 static void km_next_page(struct dpages *dp)
265 {
266 	dp->context_ptr += PAGE_SIZE - dp->context_u;
267 	dp->context_u = 0;
268 }
269 
270 static void km_dp_init(struct dpages *dp, void *data)
271 {
272 	dp->get_page = km_get_page;
273 	dp->next_page = km_next_page;
274 	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
275 	dp->context_ptr = data;
276 }
277 
278 /*-----------------------------------------------------------------
279  * IO routines that accept a list of pages.
280  *---------------------------------------------------------------*/
281 static void do_region(int rw, unsigned region, struct dm_io_region *where,
282 		      struct dpages *dp, struct io *io)
283 {
284 	struct bio *bio;
285 	struct page *page;
286 	unsigned long len;
287 	unsigned offset;
288 	unsigned num_bvecs;
289 	sector_t remaining = where->count;
290 	struct request_queue *q = bdev_get_queue(where->bdev);
291 	unsigned short logical_block_size = queue_logical_block_size(q);
292 	sector_t num_sectors;
293 
294 	/*
295 	 * where->count may be zero if rw holds a flush and we need to
296 	 * send a zero-sized flush.
297 	 */
298 	do {
299 		/*
300 		 * Allocate a suitably sized-bio.
301 		 */
302 		if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
303 			num_bvecs = 1;
304 		else
305 			num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
306 					  dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
307 
308 		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
309 		bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
310 		bio->bi_bdev = where->bdev;
311 		bio->bi_end_io = endio;
312 		store_io_and_region_in_bio(bio, io, region);
313 
314 		if (rw & REQ_DISCARD) {
315 			num_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
316 			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
317 			remaining -= num_sectors;
318 		} else if (rw & REQ_WRITE_SAME) {
319 			/*
320 			 * WRITE SAME only uses a single page.
321 			 */
322 			dp->get_page(dp, &page, &len, &offset);
323 			bio_add_page(bio, page, logical_block_size, offset);
324 			num_sectors = min_t(sector_t, q->limits.max_write_same_sectors, remaining);
325 			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
326 
327 			offset = 0;
328 			remaining -= num_sectors;
329 			dp->next_page(dp);
330 		} else while (remaining) {
331 			/*
332 			 * Try and add as many pages as possible.
333 			 */
334 			dp->get_page(dp, &page, &len, &offset);
335 			len = min(len, to_bytes(remaining));
336 			if (!bio_add_page(bio, page, len, offset))
337 				break;
338 
339 			offset = 0;
340 			remaining -= to_sector(len);
341 			dp->next_page(dp);
342 		}
343 
344 		atomic_inc(&io->count);
345 		submit_bio(rw, bio);
346 	} while (remaining);
347 }
348 
349 static void dispatch_io(int rw, unsigned int num_regions,
350 			struct dm_io_region *where, struct dpages *dp,
351 			struct io *io, int sync)
352 {
353 	int i;
354 	struct dpages old_pages = *dp;
355 
356 	BUG_ON(num_regions > DM_IO_MAX_REGIONS);
357 
358 	if (sync)
359 		rw |= REQ_SYNC;
360 
361 	/*
362 	 * For multiple regions we need to be careful to rewind
363 	 * the dp object for each call to do_region.
364 	 */
365 	for (i = 0; i < num_regions; i++) {
366 		*dp = old_pages;
367 		if (where[i].count || (rw & REQ_FLUSH))
368 			do_region(rw, i, where + i, dp, io);
369 	}
370 
371 	/*
372 	 * Drop the extra reference that we were holding to avoid
373 	 * the io being completed too early.
374 	 */
375 	dec_count(io, 0, 0);
376 }
377 
378 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
379 		   struct dm_io_region *where, int rw, struct dpages *dp,
380 		   unsigned long *error_bits)
381 {
382 	/*
383 	 * gcc <= 4.3 can't do the alignment for stack variables, so we must
384 	 * align it on our own.
385 	 * volatile prevents the optimizer from removing or reusing
386 	 * "io_" field from the stack frame (allowed in ANSI C).
387 	 */
388 	volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
389 	struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));
390 
391 	if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
392 		WARN_ON(1);
393 		return -EIO;
394 	}
395 
396 	io->error_bits = 0;
397 	atomic_set(&io->count, 1); /* see dispatch_io() */
398 	io->sleeper = current;
399 	io->client = client;
400 
401 	io->vma_invalidate_address = dp->vma_invalidate_address;
402 	io->vma_invalidate_size = dp->vma_invalidate_size;
403 
404 	dispatch_io(rw, num_regions, where, dp, io, 1);
405 
406 	while (1) {
407 		set_current_state(TASK_UNINTERRUPTIBLE);
408 
409 		if (!atomic_read(&io->count))
410 			break;
411 
412 		io_schedule();
413 	}
414 	set_current_state(TASK_RUNNING);
415 
416 	if (error_bits)
417 		*error_bits = io->error_bits;
418 
419 	return io->error_bits ? -EIO : 0;
420 }
421 
422 static int async_io(struct dm_io_client *client, unsigned int num_regions,
423 		    struct dm_io_region *where, int rw, struct dpages *dp,
424 		    io_notify_fn fn, void *context)
425 {
426 	struct io *io;
427 
428 	if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
429 		WARN_ON(1);
430 		fn(1, context);
431 		return -EIO;
432 	}
433 
434 	io = mempool_alloc(client->pool, GFP_NOIO);
435 	io->error_bits = 0;
436 	atomic_set(&io->count, 1); /* see dispatch_io() */
437 	io->sleeper = NULL;
438 	io->client = client;
439 	io->callback = fn;
440 	io->context = context;
441 
442 	io->vma_invalidate_address = dp->vma_invalidate_address;
443 	io->vma_invalidate_size = dp->vma_invalidate_size;
444 
445 	dispatch_io(rw, num_regions, where, dp, io, 0);
446 	return 0;
447 }
448 
449 static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
450 		   unsigned long size)
451 {
452 	/* Set up dpages based on memory type */
453 
454 	dp->vma_invalidate_address = NULL;
455 	dp->vma_invalidate_size = 0;
456 
457 	switch (io_req->mem.type) {
458 	case DM_IO_PAGE_LIST:
459 		list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
460 		break;
461 
462 	case DM_IO_BIO:
463 		bio_dp_init(dp, io_req->mem.ptr.bio);
464 		break;
465 
466 	case DM_IO_VMA:
467 		flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
468 		if ((io_req->bi_rw & RW_MASK) == READ) {
469 			dp->vma_invalidate_address = io_req->mem.ptr.vma;
470 			dp->vma_invalidate_size = size;
471 		}
472 		vm_dp_init(dp, io_req->mem.ptr.vma);
473 		break;
474 
475 	case DM_IO_KMEM:
476 		km_dp_init(dp, io_req->mem.ptr.addr);
477 		break;
478 
479 	default:
480 		return -EINVAL;
481 	}
482 
483 	return 0;
484 }
485 
486 /*
487  * New collapsed (a)synchronous interface.
488  *
489  * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
490  * the queue with blk_unplug() some time later or set REQ_SYNC in
491 io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
492  * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
493  */
494 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
495 	  struct dm_io_region *where, unsigned long *sync_error_bits)
496 {
497 	int r;
498 	struct dpages dp;
499 
500 	r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
501 	if (r)
502 		return r;
503 
504 	if (!io_req->notify.fn)
505 		return sync_io(io_req->client, num_regions, where,
506 			       io_req->bi_rw, &dp, sync_error_bits);
507 
508 	return async_io(io_req->client, num_regions, where, io_req->bi_rw,
509 			&dp, io_req->notify.fn, io_req->notify.context);
510 }
511 EXPORT_SYMBOL(dm_io);
512 
513 int __init dm_io_init(void)
514 {
515 	_dm_io_cache = KMEM_CACHE(io, 0);
516 	if (!_dm_io_cache)
517 		return -ENOMEM;
518 
519 	return 0;
520 }
521 
522 void dm_io_exit(void)
523 {
524 	kmem_cache_destroy(_dm_io_cache);
525 	_dm_io_cache = NULL;
526 }
527