blob: da663d2ff552b4b3a4d44bec0c4ec84e4e904365 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2003 Sistina Software
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm-io.h"
8
9#include <linux/bio.h>
10#include <linux/mempool.h>
11#include <linux/module.h>
12#include <linux/sched.h>
13#include <linux/slab.h>
14
15static struct bio_set *_bios;
16
17/* FIXME: can we shrink this ? */
18struct io {
19 unsigned long error;
20 atomic_t count;
21 struct task_struct *sleeper;
22 io_notify_fn callback;
23 void *context;
24};
25
26/*
27 * io contexts are only dynamically allocated for asynchronous
28 * io. Since async io is likely to be the majority of io we'll
29 * have the same number of io contexts as buffer heads ! (FIXME:
30 * must reduce this).
31 */
32static unsigned _num_ios;
33static mempool_t *_io_pool;
34
Linus Torvalds1da177e2005-04-16 15:20:36 -070035static unsigned int pages_to_ios(unsigned int pages)
36{
37 return 4 * pages; /* too many ? */
38}
39
40static int resize_pool(unsigned int new_ios)
41{
42 int r = 0;
43
44 if (_io_pool) {
45 if (new_ios == 0) {
46 /* free off the pool */
47 mempool_destroy(_io_pool);
48 _io_pool = NULL;
49 bioset_free(_bios);
50
51 } else {
52 /* resize the pool */
53 r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
54 }
55
56 } else {
57 /* create new pool */
Matthew Dobson0eaae62a2006-03-26 01:37:47 -080058 _io_pool = mempool_create_kmalloc_pool(new_ios,
59 sizeof(struct io));
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 if (!_io_pool)
61 return -ENOMEM;
62
63 _bios = bioset_create(16, 16, 4);
64 if (!_bios) {
65 mempool_destroy(_io_pool);
66 _io_pool = NULL;
67 return -ENOMEM;
68 }
69 }
70
71 if (!r)
72 _num_ios = new_ios;
73
74 return r;
75}
76
77int dm_io_get(unsigned int num_pages)
78{
79 return resize_pool(_num_ios + pages_to_ios(num_pages));
80}
81
82void dm_io_put(unsigned int num_pages)
83{
84 resize_pool(_num_ios - pages_to_ios(num_pages));
85}
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 *---------------------------------------------------------------*/
93static inline void bio_set_region(struct bio *bio, unsigned region)
94{
95 bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len = region;
96}
97
98static inline unsigned bio_get_region(struct bio *bio)
99{
100 return bio->bi_io_vec[bio->bi_max_vecs - 1].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 *---------------------------------------------------------------*/
107static 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 int r = io->error;
118 io_notify_fn fn = io->callback;
119 void *context = io->context;
120
121 mempool_free(io, _io_pool);
122 fn(r, context);
123 }
124 }
125}
126
127static int endio(struct bio *bio, unsigned int done, int error)
128{
129 struct io *io = (struct io *) bio->bi_private;
130
131 /* keep going until we've finished */
132 if (bio->bi_size)
133 return 1;
134
135 if (error && bio_data_dir(bio) == READ)
136 zero_fill_bio(bio);
137
138 dec_count(io, bio_get_region(bio), error);
139 bio_put(bio);
140
141 return 0;
142}
143
144/*-----------------------------------------------------------------
145 * These little objects provide an abstraction for getting a new
146 * destination page for io.
147 *---------------------------------------------------------------*/
148struct dpages {
149 void (*get_page)(struct dpages *dp,
150 struct page **p, unsigned long *len, unsigned *offset);
151 void (*next_page)(struct dpages *dp);
152
153 unsigned context_u;
154 void *context_ptr;
155};
156
157/*
158 * Functions for getting the pages from a list.
159 */
160static void list_get_page(struct dpages *dp,
161 struct page **p, unsigned long *len, unsigned *offset)
162{
163 unsigned o = dp->context_u;
164 struct page_list *pl = (struct page_list *) dp->context_ptr;
165
166 *p = pl->page;
167 *len = PAGE_SIZE - o;
168 *offset = o;
169}
170
171static void list_next_page(struct dpages *dp)
172{
173 struct page_list *pl = (struct page_list *) dp->context_ptr;
174 dp->context_ptr = pl->next;
175 dp->context_u = 0;
176}
177
178static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
179{
180 dp->get_page = list_get_page;
181 dp->next_page = list_next_page;
182 dp->context_u = offset;
183 dp->context_ptr = pl;
184}
185
186/*
187 * Functions for getting the pages from a bvec.
188 */
189static void bvec_get_page(struct dpages *dp,
190 struct page **p, unsigned long *len, unsigned *offset)
191{
192 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
193 *p = bvec->bv_page;
194 *len = bvec->bv_len;
195 *offset = bvec->bv_offset;
196}
197
198static void bvec_next_page(struct dpages *dp)
199{
200 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
201 dp->context_ptr = bvec + 1;
202}
203
204static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
205{
206 dp->get_page = bvec_get_page;
207 dp->next_page = bvec_next_page;
208 dp->context_ptr = bvec;
209}
210
211static void vm_get_page(struct dpages *dp,
212 struct page **p, unsigned long *len, unsigned *offset)
213{
214 *p = vmalloc_to_page(dp->context_ptr);
215 *offset = dp->context_u;
216 *len = PAGE_SIZE - dp->context_u;
217}
218
219static void vm_next_page(struct dpages *dp)
220{
221 dp->context_ptr += PAGE_SIZE - dp->context_u;
222 dp->context_u = 0;
223}
224
225static void vm_dp_init(struct dpages *dp, void *data)
226{
227 dp->get_page = vm_get_page;
228 dp->next_page = vm_next_page;
229 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
230 dp->context_ptr = data;
231}
232
Peter Osterlund36763472005-09-06 15:16:42 -0700233static void dm_bio_destructor(struct bio *bio)
234{
235 bio_free(bio, _bios);
236}
237
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238/*-----------------------------------------------------------------
239 * IO routines that accept a list of pages.
240 *---------------------------------------------------------------*/
241static void do_region(int rw, unsigned int region, struct io_region *where,
242 struct dpages *dp, struct io *io)
243{
244 struct bio *bio;
245 struct page *page;
246 unsigned long len;
247 unsigned offset;
248 unsigned num_bvecs;
249 sector_t remaining = where->count;
250
251 while (remaining) {
252 /*
253 * Allocate a suitably sized bio, we add an extra
254 * bvec for bio_get/set_region().
255 */
256 num_bvecs = (remaining / (PAGE_SIZE >> 9)) + 2;
257 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
258 bio->bi_sector = where->sector + (where->count - remaining);
259 bio->bi_bdev = where->bdev;
260 bio->bi_end_io = endio;
261 bio->bi_private = io;
Peter Osterlund36763472005-09-06 15:16:42 -0700262 bio->bi_destructor = dm_bio_destructor;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 bio_set_region(bio, region);
264
265 /*
266 * Try and add as many pages as possible.
267 */
268 while (remaining) {
269 dp->get_page(dp, &page, &len, &offset);
270 len = min(len, to_bytes(remaining));
271 if (!bio_add_page(bio, page, len, offset))
272 break;
273
274 offset = 0;
275 remaining -= to_sector(len);
276 dp->next_page(dp);
277 }
278
279 atomic_inc(&io->count);
280 submit_bio(rw, bio);
281 }
282}
283
284static void dispatch_io(int rw, unsigned int num_regions,
285 struct io_region *where, struct dpages *dp,
286 struct io *io, int sync)
287{
288 int i;
289 struct dpages old_pages = *dp;
290
291 if (sync)
292 rw |= (1 << BIO_RW_SYNC);
293
294 /*
295 * For multiple regions we need to be careful to rewind
296 * the dp object for each call to do_region.
297 */
298 for (i = 0; i < num_regions; i++) {
299 *dp = old_pages;
300 if (where[i].count)
301 do_region(rw, i, where + i, dp, io);
302 }
303
304 /*
305 * Drop the extra refence that we were holding to avoid
306 * the io being completed too early.
307 */
308 dec_count(io, 0, 0);
309}
310
311static int sync_io(unsigned int num_regions, struct io_region *where,
312 int rw, struct dpages *dp, unsigned long *error_bits)
313{
314 struct io io;
315
316 if (num_regions > 1 && rw != WRITE) {
317 WARN_ON(1);
318 return -EIO;
319 }
320
321 io.error = 0;
322 atomic_set(&io.count, 1); /* see dispatch_io() */
323 io.sleeper = current;
324
325 dispatch_io(rw, num_regions, where, dp, &io, 1);
326
327 while (1) {
328 set_current_state(TASK_UNINTERRUPTIBLE);
329
330 if (!atomic_read(&io.count) || signal_pending(current))
331 break;
332
333 io_schedule();
334 }
335 set_current_state(TASK_RUNNING);
336
337 if (atomic_read(&io.count))
338 return -EINTR;
339
340 *error_bits = io.error;
341 return io.error ? -EIO : 0;
342}
343
344static int async_io(unsigned int num_regions, struct io_region *where, int rw,
345 struct dpages *dp, io_notify_fn fn, void *context)
346{
347 struct io *io;
348
349 if (num_regions > 1 && rw != WRITE) {
350 WARN_ON(1);
351 fn(1, context);
352 return -EIO;
353 }
354
355 io = mempool_alloc(_io_pool, GFP_NOIO);
356 io->error = 0;
357 atomic_set(&io->count, 1); /* see dispatch_io() */
358 io->sleeper = NULL;
359 io->callback = fn;
360 io->context = context;
361
362 dispatch_io(rw, num_regions, where, dp, io, 0);
363 return 0;
364}
365
366int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
367 struct page_list *pl, unsigned int offset,
368 unsigned long *error_bits)
369{
370 struct dpages dp;
371 list_dp_init(&dp, pl, offset);
372 return sync_io(num_regions, where, rw, &dp, error_bits);
373}
374
375int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
376 struct bio_vec *bvec, unsigned long *error_bits)
377{
378 struct dpages dp;
379 bvec_dp_init(&dp, bvec);
380 return sync_io(num_regions, where, rw, &dp, error_bits);
381}
382
383int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
384 void *data, unsigned long *error_bits)
385{
386 struct dpages dp;
387 vm_dp_init(&dp, data);
388 return sync_io(num_regions, where, rw, &dp, error_bits);
389}
390
391int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
392 struct page_list *pl, unsigned int offset,
393 io_notify_fn fn, void *context)
394{
395 struct dpages dp;
396 list_dp_init(&dp, pl, offset);
397 return async_io(num_regions, where, rw, &dp, fn, context);
398}
399
400int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
401 struct bio_vec *bvec, io_notify_fn fn, void *context)
402{
403 struct dpages dp;
404 bvec_dp_init(&dp, bvec);
405 return async_io(num_regions, where, rw, &dp, fn, context);
406}
407
408int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
409 void *data, io_notify_fn fn, void *context)
410{
411 struct dpages dp;
412 vm_dp_init(&dp, data);
413 return async_io(num_regions, where, rw, &dp, fn, context);
414}
415
416EXPORT_SYMBOL(dm_io_get);
417EXPORT_SYMBOL(dm_io_put);
418EXPORT_SYMBOL(dm_io_sync);
419EXPORT_SYMBOL(dm_io_async);
420EXPORT_SYMBOL(dm_io_sync_bvec);
421EXPORT_SYMBOL(dm_io_async_bvec);
422EXPORT_SYMBOL(dm_io_sync_vm);
423EXPORT_SYMBOL(dm_io_async_vm);