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-io.h"
9
10 #include <linux/bio.h>
11 #include <linux/mempool.h>
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/slab.h>
15
16 struct dm_io_client {
17 mempool_t *pool;
18 struct bio_set *bios;
19 };
20
21 /* FIXME: can we shrink this ? */
22 struct io {
23 unsigned long error;
24 atomic_t count;
25 struct task_struct *sleeper;
26 struct dm_io_client *client;
27 io_notify_fn callback;
28 void *context;
29 };
30
31 /*
32 * io contexts are only dynamically allocated for asynchronous
33 * io. Since async io is likely to be the majority of io we'll
34 * have the same number of io contexts as bios! (FIXME: must reduce this).
35 */
36
37 static unsigned int pages_to_ios(unsigned int pages)
38 {
39 return 4 * pages; /* too many ? */
40 }
41
42 /*
43 * Create a client with mempool and bioset.
44 */
45 struct dm_io_client *dm_io_client_create(unsigned num_pages)
46 {
47 unsigned ios = pages_to_ios(num_pages);
48 struct dm_io_client *client;
49
50 client = kmalloc(sizeof(*client), GFP_KERNEL);
51 if (!client)
52 return ERR_PTR(-ENOMEM);
53
54 client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
55 if (!client->pool)
56 goto bad;
57
58 client->bios = bioset_create(16, 16);
59 if (!client->bios)
60 goto bad;
61
62 return client;
63
64 bad:
65 if (client->pool)
66 mempool_destroy(client->pool);
67 kfree(client);
68 return ERR_PTR(-ENOMEM);
69 }
70 EXPORT_SYMBOL(dm_io_client_create);
71
72 int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
73 {
74 return mempool_resize(client->pool, pages_to_ios(num_pages),
75 GFP_KERNEL);
76 }
77 EXPORT_SYMBOL(dm_io_client_resize);
78
79 void dm_io_client_destroy(struct dm_io_client *client)
80 {
81 mempool_destroy(client->pool);
82 bioset_free(client->bios);
83 kfree(client);
84 }
85 EXPORT_SYMBOL(dm_io_client_destroy);
86
87 /*-----------------------------------------------------------------
88 * We need to keep track of which region a bio is doing io for.
89 * In order to save a memory allocation we store this the last
90 * bvec which we know is unused (blech).
91 * XXX This is ugly and can OOPS with some configs... find another way.
92 *---------------------------------------------------------------*/
93 static inline void bio_set_region(struct bio *bio, unsigned region)
94 {
95 bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
96 }
97
98 static inline unsigned bio_get_region(struct bio *bio)
99 {
100 return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
101 }
102
103 /*-----------------------------------------------------------------
104 * We need an io object to keep track of the number of bios that
105 * have been dispatched for a particular io.
106 *---------------------------------------------------------------*/
107 static void dec_count(struct io *io, unsigned int region, int error)
108 {
109 if (error)
110 set_bit(region, &io->error);
111
112 if (atomic_dec_and_test(&io->count)) {
113 if (io->sleeper)
114 wake_up_process(io->sleeper);
115
116 else {
117 unsigned long r = io->error;
118 io_notify_fn fn = io->callback;
119 void *context = io->context;
120
121 mempool_free(io, io->client->pool);
122 fn(r, context);
123 }
124 }
125 }
126
127 static void endio(struct bio *bio, int error)
128 {
129 struct io *io;
130 unsigned region;
131
132 if (error && bio_data_dir(bio) == READ)
133 zero_fill_bio(bio);
134
135 /*
136 * The bio destructor in bio_put() may use the io object.
137 */
138 io = bio->bi_private;
139 region = bio_get_region(bio);
140
141 bio->bi_max_vecs++;
142 bio_put(bio);
143
144 dec_count(io, region, error);
145 }
146
147 /*-----------------------------------------------------------------
148 * These little objects provide an abstraction for getting a new
149 * destination page for io.
150 *---------------------------------------------------------------*/
151 struct dpages {
152 void (*get_page)(struct dpages *dp,
153 struct page **p, unsigned long *len, unsigned *offset);
154 void (*next_page)(struct dpages *dp);
155
156 unsigned context_u;
157 void *context_ptr;
158 };
159
160 /*
161 * Functions for getting the pages from a list.
162 */
163 static void list_get_page(struct dpages *dp,
164 struct page **p, unsigned long *len, unsigned *offset)
165 {
166 unsigned o = dp->context_u;
167 struct page_list *pl = (struct page_list *) dp->context_ptr;
168
169 *p = pl->page;
170 *len = PAGE_SIZE - o;
171 *offset = o;
172 }
173
174 static void list_next_page(struct dpages *dp)
175 {
176 struct page_list *pl = (struct page_list *) dp->context_ptr;
177 dp->context_ptr = pl->next;
178 dp->context_u = 0;
179 }
180
181 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
182 {
183 dp->get_page = list_get_page;
184 dp->next_page = list_next_page;
185 dp->context_u = offset;
186 dp->context_ptr = pl;
187 }
188
189 /*
190 * Functions for getting the pages from a bvec.
191 */
192 static void bvec_get_page(struct dpages *dp,
193 struct page **p, unsigned long *len, unsigned *offset)
194 {
195 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
196 *p = bvec->bv_page;
197 *len = bvec->bv_len;
198 *offset = bvec->bv_offset;
199 }
200
201 static void bvec_next_page(struct dpages *dp)
202 {
203 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
204 dp->context_ptr = bvec + 1;
205 }
206
207 static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
208 {
209 dp->get_page = bvec_get_page;
210 dp->next_page = bvec_next_page;
211 dp->context_ptr = bvec;
212 }
213
214 /*
215 * Functions for getting the pages from a VMA.
216 */
217 static void vm_get_page(struct dpages *dp,
218 struct page **p, unsigned long *len, unsigned *offset)
219 {
220 *p = vmalloc_to_page(dp->context_ptr);
221 *offset = dp->context_u;
222 *len = PAGE_SIZE - dp->context_u;
223 }
224
225 static void vm_next_page(struct dpages *dp)
226 {
227 dp->context_ptr += PAGE_SIZE - dp->context_u;
228 dp->context_u = 0;
229 }
230
231 static void vm_dp_init(struct dpages *dp, void *data)
232 {
233 dp->get_page = vm_get_page;
234 dp->next_page = vm_next_page;
235 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
236 dp->context_ptr = data;
237 }
238
239 static void dm_bio_destructor(struct bio *bio)
240 {
241 struct io *io = bio->bi_private;
242
243 bio_free(bio, io->client->bios);
244 }
245
246 /*
247 * Functions for getting the pages from kernel memory.
248 */
249 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
250 unsigned *offset)
251 {
252 *p = virt_to_page(dp->context_ptr);
253 *offset = dp->context_u;
254 *len = PAGE_SIZE - dp->context_u;
255 }
256
257 static void km_next_page(struct dpages *dp)
258 {
259 dp->context_ptr += PAGE_SIZE - dp->context_u;
260 dp->context_u = 0;
261 }
262
263 static void km_dp_init(struct dpages *dp, void *data)
264 {
265 dp->get_page = km_get_page;
266 dp->next_page = km_next_page;
267 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
268 dp->context_ptr = data;
269 }
270
271 /*-----------------------------------------------------------------
272 * IO routines that accept a list of pages.
273 *---------------------------------------------------------------*/
274 static void do_region(int rw, unsigned int region, struct io_region *where,
275 struct dpages *dp, struct io *io)
276 {
277 struct bio *bio;
278 struct page *page;
279 unsigned long len;
280 unsigned offset;
281 unsigned num_bvecs;
282 sector_t remaining = where->count;
283
284 while (remaining) {
285 /*
286 * Allocate a suitably sized-bio: we add an extra
287 * bvec for bio_get/set_region() and decrement bi_max_vecs
288 * to hide it from bio_add_page().
289 */
290 num_bvecs = dm_sector_div_up(remaining,
291 (PAGE_SIZE >> SECTOR_SHIFT));
292 num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev),
293 num_bvecs);
294 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
295 bio->bi_sector = where->sector + (where->count - remaining);
296 bio->bi_bdev = where->bdev;
297 bio->bi_end_io = endio;
298 bio->bi_private = io;
299 bio->bi_destructor = dm_bio_destructor;
300 bio->bi_max_vecs--;
301 bio_set_region(bio, region);
302
303 /*
304 * Try and add as many pages as possible.
305 */
306 while (remaining) {
307 dp->get_page(dp, &page, &len, &offset);
308 len = min(len, to_bytes(remaining));
309 if (!bio_add_page(bio, page, len, offset))
310 break;
311
312 offset = 0;
313 remaining -= to_sector(len);
314 dp->next_page(dp);
315 }
316
317 atomic_inc(&io->count);
318 submit_bio(rw, bio);
319 }
320 }
321
322 static void dispatch_io(int rw, unsigned int num_regions,
323 struct io_region *where, struct dpages *dp,
324 struct io *io, int sync)
325 {
326 int i;
327 struct dpages old_pages = *dp;
328
329 if (sync)
330 rw |= (1 << BIO_RW_SYNC);
331
332 /*
333 * For multiple regions we need to be careful to rewind
334 * the dp object for each call to do_region.
335 */
336 for (i = 0; i < num_regions; i++) {
337 *dp = old_pages;
338 if (where[i].count)
339 do_region(rw, i, where + i, dp, io);
340 }
341
342 /*
343 * Drop the extra reference that we were holding to avoid
344 * the io being completed too early.
345 */
346 dec_count(io, 0, 0);
347 }
348
349 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
350 struct io_region *where, int rw, struct dpages *dp,
351 unsigned long *error_bits)
352 {
353 struct io io;
354
355 if (num_regions > 1 && rw != WRITE) {
356 WARN_ON(1);
357 return -EIO;
358 }
359
360 io.error = 0;
361 atomic_set(&io.count, 1); /* see dispatch_io() */
362 io.sleeper = current;
363 io.client = client;
364
365 dispatch_io(rw, num_regions, where, dp, &io, 1);
366
367 while (1) {
368 set_current_state(TASK_UNINTERRUPTIBLE);
369
370 if (!atomic_read(&io.count) || signal_pending(current))
371 break;
372
373 io_schedule();
374 }
375 set_current_state(TASK_RUNNING);
376
377 if (atomic_read(&io.count))
378 return -EINTR;
379
380 if (error_bits)
381 *error_bits = io.error;
382
383 return io.error ? -EIO : 0;
384 }
385
386 static int async_io(struct dm_io_client *client, unsigned int num_regions,
387 struct io_region *where, int rw, struct dpages *dp,
388 io_notify_fn fn, void *context)
389 {
390 struct io *io;
391
392 if (num_regions > 1 && rw != WRITE) {
393 WARN_ON(1);
394 fn(1, context);
395 return -EIO;
396 }
397
398 io = mempool_alloc(client->pool, GFP_NOIO);
399 io->error = 0;
400 atomic_set(&io->count, 1); /* see dispatch_io() */
401 io->sleeper = NULL;
402 io->client = client;
403 io->callback = fn;
404 io->context = context;
405
406 dispatch_io(rw, num_regions, where, dp, io, 0);
407 return 0;
408 }
409
410 static int dp_init(struct dm_io_request *io_req, struct dpages *dp)
411 {
412 /* Set up dpages based on memory type */
413 switch (io_req->mem.type) {
414 case DM_IO_PAGE_LIST:
415 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
416 break;
417
418 case DM_IO_BVEC:
419 bvec_dp_init(dp, io_req->mem.ptr.bvec);
420 break;
421
422 case DM_IO_VMA:
423 vm_dp_init(dp, io_req->mem.ptr.vma);
424 break;
425
426 case DM_IO_KMEM:
427 km_dp_init(dp, io_req->mem.ptr.addr);
428 break;
429
430 default:
431 return -EINVAL;
432 }
433
434 return 0;
435 }
436
437 /*
438 * New collapsed (a)synchronous interface
439 */
440 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
441 struct io_region *where, unsigned long *sync_error_bits)
442 {
443 int r;
444 struct dpages dp;
445
446 r = dp_init(io_req, &dp);
447 if (r)
448 return r;
449
450 if (!io_req->notify.fn)
451 return sync_io(io_req->client, num_regions, where,
452 io_req->bi_rw, &dp, sync_error_bits);
453
454 return async_io(io_req->client, num_regions, where, io_req->bi_rw,
455 &dp, io_req->notify.fn, io_req->notify.context);
456 }
457 EXPORT_SYMBOL(dm_io);
458
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