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95d402f0 MP |
1 | /* |
2 | * Copyright (C) 2009-2011 Red Hat, Inc. | |
3 | * | |
4 | * Author: Mikulas Patocka <mpatocka@redhat.com> | |
5 | * | |
6 | * This file is released under the GPL. | |
7 | */ | |
8 | ||
9 | #include "dm-bufio.h" | |
10 | ||
11 | #include <linux/device-mapper.h> | |
12 | #include <linux/dm-io.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/vmalloc.h> | |
15 | #include <linux/version.h> | |
16 | #include <linux/shrinker.h> | |
17 | ||
18 | #define DM_MSG_PREFIX "bufio" | |
19 | ||
20 | /* | |
21 | * Memory management policy: | |
22 | * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory | |
23 | * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower). | |
24 | * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers. | |
25 | * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT | |
26 | * dirty buffers. | |
27 | */ | |
28 | #define DM_BUFIO_MIN_BUFFERS 8 | |
29 | ||
30 | #define DM_BUFIO_MEMORY_PERCENT 2 | |
31 | #define DM_BUFIO_VMALLOC_PERCENT 25 | |
32 | #define DM_BUFIO_WRITEBACK_PERCENT 75 | |
33 | ||
34 | /* | |
35 | * Check buffer ages in this interval (seconds) | |
36 | */ | |
37 | #define DM_BUFIO_WORK_TIMER_SECS 10 | |
38 | ||
39 | /* | |
40 | * Free buffers when they are older than this (seconds) | |
41 | */ | |
42 | #define DM_BUFIO_DEFAULT_AGE_SECS 60 | |
43 | ||
44 | /* | |
45 | * The number of bvec entries that are embedded directly in the buffer. | |
46 | * If the chunk size is larger, dm-io is used to do the io. | |
47 | */ | |
48 | #define DM_BUFIO_INLINE_VECS 16 | |
49 | ||
50 | /* | |
51 | * Buffer hash | |
52 | */ | |
53 | #define DM_BUFIO_HASH_BITS 20 | |
54 | #define DM_BUFIO_HASH(block) \ | |
55 | ((((block) >> DM_BUFIO_HASH_BITS) ^ (block)) & \ | |
56 | ((1 << DM_BUFIO_HASH_BITS) - 1)) | |
57 | ||
58 | /* | |
59 | * Don't try to use kmem_cache_alloc for blocks larger than this. | |
60 | * For explanation, see alloc_buffer_data below. | |
61 | */ | |
62 | #define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1) | |
63 | #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1)) | |
64 | ||
65 | /* | |
66 | * dm_buffer->list_mode | |
67 | */ | |
68 | #define LIST_CLEAN 0 | |
69 | #define LIST_DIRTY 1 | |
70 | #define LIST_SIZE 2 | |
71 | ||
72 | /* | |
73 | * Linking of buffers: | |
74 | * All buffers are linked to cache_hash with their hash_list field. | |
75 | * | |
76 | * Clean buffers that are not being written (B_WRITING not set) | |
77 | * are linked to lru[LIST_CLEAN] with their lru_list field. | |
78 | * | |
79 | * Dirty and clean buffers that are being written are linked to | |
80 | * lru[LIST_DIRTY] with their lru_list field. When the write | |
81 | * finishes, the buffer cannot be relinked immediately (because we | |
82 | * are in an interrupt context and relinking requires process | |
83 | * context), so some clean-not-writing buffers can be held on | |
84 | * dirty_lru too. They are later added to lru in the process | |
85 | * context. | |
86 | */ | |
87 | struct dm_bufio_client { | |
88 | struct mutex lock; | |
89 | ||
90 | struct list_head lru[LIST_SIZE]; | |
91 | unsigned long n_buffers[LIST_SIZE]; | |
92 | ||
93 | struct block_device *bdev; | |
94 | unsigned block_size; | |
95 | unsigned char sectors_per_block_bits; | |
96 | unsigned char pages_per_block_bits; | |
97 | unsigned char blocks_per_page_bits; | |
98 | unsigned aux_size; | |
99 | void (*alloc_callback)(struct dm_buffer *); | |
100 | void (*write_callback)(struct dm_buffer *); | |
101 | ||
102 | struct dm_io_client *dm_io; | |
103 | ||
104 | struct list_head reserved_buffers; | |
105 | unsigned need_reserved_buffers; | |
106 | ||
107 | struct hlist_head *cache_hash; | |
108 | wait_queue_head_t free_buffer_wait; | |
109 | ||
110 | int async_write_error; | |
111 | ||
112 | struct list_head client_list; | |
113 | struct shrinker shrinker; | |
114 | }; | |
115 | ||
116 | /* | |
117 | * Buffer state bits. | |
118 | */ | |
119 | #define B_READING 0 | |
120 | #define B_WRITING 1 | |
121 | #define B_DIRTY 2 | |
122 | ||
123 | /* | |
124 | * Describes how the block was allocated: | |
125 | * kmem_cache_alloc(), __get_free_pages() or vmalloc(). | |
126 | * See the comment at alloc_buffer_data. | |
127 | */ | |
128 | enum data_mode { | |
129 | DATA_MODE_SLAB = 0, | |
130 | DATA_MODE_GET_FREE_PAGES = 1, | |
131 | DATA_MODE_VMALLOC = 2, | |
132 | DATA_MODE_LIMIT = 3 | |
133 | }; | |
134 | ||
135 | struct dm_buffer { | |
136 | struct hlist_node hash_list; | |
137 | struct list_head lru_list; | |
138 | sector_t block; | |
139 | void *data; | |
140 | enum data_mode data_mode; | |
141 | unsigned char list_mode; /* LIST_* */ | |
142 | unsigned hold_count; | |
143 | int read_error; | |
144 | int write_error; | |
145 | unsigned long state; | |
146 | unsigned long last_accessed; | |
147 | struct dm_bufio_client *c; | |
148 | struct bio bio; | |
149 | struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS]; | |
150 | }; | |
151 | ||
152 | /*----------------------------------------------------------------*/ | |
153 | ||
154 | static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT]; | |
155 | static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT]; | |
156 | ||
157 | static inline int dm_bufio_cache_index(struct dm_bufio_client *c) | |
158 | { | |
159 | unsigned ret = c->blocks_per_page_bits - 1; | |
160 | ||
161 | BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches)); | |
162 | ||
163 | return ret; | |
164 | } | |
165 | ||
166 | #define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)]) | |
167 | #define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)]) | |
168 | ||
169 | #define dm_bufio_in_request() (!!current->bio_list) | |
170 | ||
171 | static void dm_bufio_lock(struct dm_bufio_client *c) | |
172 | { | |
173 | mutex_lock_nested(&c->lock, dm_bufio_in_request()); | |
174 | } | |
175 | ||
176 | static int dm_bufio_trylock(struct dm_bufio_client *c) | |
177 | { | |
178 | return mutex_trylock(&c->lock); | |
179 | } | |
180 | ||
181 | static void dm_bufio_unlock(struct dm_bufio_client *c) | |
182 | { | |
183 | mutex_unlock(&c->lock); | |
184 | } | |
185 | ||
186 | /* | |
187 | * FIXME Move to sched.h? | |
188 | */ | |
189 | #ifdef CONFIG_PREEMPT_VOLUNTARY | |
190 | # define dm_bufio_cond_resched() \ | |
191 | do { \ | |
192 | if (unlikely(need_resched())) \ | |
193 | _cond_resched(); \ | |
194 | } while (0) | |
195 | #else | |
196 | # define dm_bufio_cond_resched() do { } while (0) | |
197 | #endif | |
198 | ||
199 | /*----------------------------------------------------------------*/ | |
200 | ||
201 | /* | |
202 | * Default cache size: available memory divided by the ratio. | |
203 | */ | |
204 | static unsigned long dm_bufio_default_cache_size; | |
205 | ||
206 | /* | |
207 | * Total cache size set by the user. | |
208 | */ | |
209 | static unsigned long dm_bufio_cache_size; | |
210 | ||
211 | /* | |
212 | * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change | |
213 | * at any time. If it disagrees, the user has changed cache size. | |
214 | */ | |
215 | static unsigned long dm_bufio_cache_size_latch; | |
216 | ||
217 | static DEFINE_SPINLOCK(param_spinlock); | |
218 | ||
219 | /* | |
220 | * Buffers are freed after this timeout | |
221 | */ | |
222 | static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS; | |
223 | ||
224 | static unsigned long dm_bufio_peak_allocated; | |
225 | static unsigned long dm_bufio_allocated_kmem_cache; | |
226 | static unsigned long dm_bufio_allocated_get_free_pages; | |
227 | static unsigned long dm_bufio_allocated_vmalloc; | |
228 | static unsigned long dm_bufio_current_allocated; | |
229 | ||
230 | /*----------------------------------------------------------------*/ | |
231 | ||
232 | /* | |
233 | * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count | |
234 | */ | |
235 | static unsigned long dm_bufio_cache_size_per_client; | |
236 | ||
237 | /* | |
238 | * The current number of clients. | |
239 | */ | |
240 | static int dm_bufio_client_count; | |
241 | ||
242 | /* | |
243 | * The list of all clients. | |
244 | */ | |
245 | static LIST_HEAD(dm_bufio_all_clients); | |
246 | ||
247 | /* | |
248 | * This mutex protects dm_bufio_cache_size_latch, | |
249 | * dm_bufio_cache_size_per_client and dm_bufio_client_count | |
250 | */ | |
251 | static DEFINE_MUTEX(dm_bufio_clients_lock); | |
252 | ||
253 | /*----------------------------------------------------------------*/ | |
254 | ||
255 | static void adjust_total_allocated(enum data_mode data_mode, long diff) | |
256 | { | |
257 | static unsigned long * const class_ptr[DATA_MODE_LIMIT] = { | |
258 | &dm_bufio_allocated_kmem_cache, | |
259 | &dm_bufio_allocated_get_free_pages, | |
260 | &dm_bufio_allocated_vmalloc, | |
261 | }; | |
262 | ||
263 | spin_lock(¶m_spinlock); | |
264 | ||
265 | *class_ptr[data_mode] += diff; | |
266 | ||
267 | dm_bufio_current_allocated += diff; | |
268 | ||
269 | if (dm_bufio_current_allocated > dm_bufio_peak_allocated) | |
270 | dm_bufio_peak_allocated = dm_bufio_current_allocated; | |
271 | ||
272 | spin_unlock(¶m_spinlock); | |
273 | } | |
274 | ||
275 | /* | |
276 | * Change the number of clients and recalculate per-client limit. | |
277 | */ | |
278 | static void __cache_size_refresh(void) | |
279 | { | |
280 | BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock)); | |
281 | BUG_ON(dm_bufio_client_count < 0); | |
282 | ||
283 | dm_bufio_cache_size_latch = dm_bufio_cache_size; | |
284 | ||
285 | barrier(); | |
286 | ||
287 | /* | |
288 | * Use default if set to 0 and report the actual cache size used. | |
289 | */ | |
290 | if (!dm_bufio_cache_size_latch) { | |
291 | (void)cmpxchg(&dm_bufio_cache_size, 0, | |
292 | dm_bufio_default_cache_size); | |
293 | dm_bufio_cache_size_latch = dm_bufio_default_cache_size; | |
294 | } | |
295 | ||
296 | dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch / | |
297 | (dm_bufio_client_count ? : 1); | |
298 | } | |
299 | ||
300 | /* | |
301 | * Allocating buffer data. | |
302 | * | |
303 | * Small buffers are allocated with kmem_cache, to use space optimally. | |
304 | * | |
305 | * For large buffers, we choose between get_free_pages and vmalloc. | |
306 | * Each has advantages and disadvantages. | |
307 | * | |
308 | * __get_free_pages can randomly fail if the memory is fragmented. | |
309 | * __vmalloc won't randomly fail, but vmalloc space is limited (it may be | |
310 | * as low as 128M) so using it for caching is not appropriate. | |
311 | * | |
312 | * If the allocation may fail we use __get_free_pages. Memory fragmentation | |
313 | * won't have a fatal effect here, but it just causes flushes of some other | |
314 | * buffers and more I/O will be performed. Don't use __get_free_pages if it | |
315 | * always fails (i.e. order >= MAX_ORDER). | |
316 | * | |
317 | * If the allocation shouldn't fail we use __vmalloc. This is only for the | |
318 | * initial reserve allocation, so there's no risk of wasting all vmalloc | |
319 | * space. | |
320 | */ | |
321 | static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, | |
322 | enum data_mode *data_mode) | |
323 | { | |
324 | if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) { | |
325 | *data_mode = DATA_MODE_SLAB; | |
326 | return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask); | |
327 | } | |
328 | ||
329 | if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT && | |
330 | gfp_mask & __GFP_NORETRY) { | |
331 | *data_mode = DATA_MODE_GET_FREE_PAGES; | |
332 | return (void *)__get_free_pages(gfp_mask, | |
333 | c->pages_per_block_bits); | |
334 | } | |
335 | ||
336 | *data_mode = DATA_MODE_VMALLOC; | |
337 | return __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); | |
338 | } | |
339 | ||
340 | /* | |
341 | * Free buffer's data. | |
342 | */ | |
343 | static void free_buffer_data(struct dm_bufio_client *c, | |
344 | void *data, enum data_mode data_mode) | |
345 | { | |
346 | switch (data_mode) { | |
347 | case DATA_MODE_SLAB: | |
348 | kmem_cache_free(DM_BUFIO_CACHE(c), data); | |
349 | break; | |
350 | ||
351 | case DATA_MODE_GET_FREE_PAGES: | |
352 | free_pages((unsigned long)data, c->pages_per_block_bits); | |
353 | break; | |
354 | ||
355 | case DATA_MODE_VMALLOC: | |
356 | vfree(data); | |
357 | break; | |
358 | ||
359 | default: | |
360 | DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d", | |
361 | data_mode); | |
362 | BUG(); | |
363 | } | |
364 | } | |
365 | ||
366 | /* | |
367 | * Allocate buffer and its data. | |
368 | */ | |
369 | static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) | |
370 | { | |
371 | struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size, | |
372 | gfp_mask); | |
373 | ||
374 | if (!b) | |
375 | return NULL; | |
376 | ||
377 | b->c = c; | |
378 | ||
379 | b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); | |
380 | if (!b->data) { | |
381 | kfree(b); | |
382 | return NULL; | |
383 | } | |
384 | ||
385 | adjust_total_allocated(b->data_mode, (long)c->block_size); | |
386 | ||
387 | return b; | |
388 | } | |
389 | ||
390 | /* | |
391 | * Free buffer and its data. | |
392 | */ | |
393 | static void free_buffer(struct dm_buffer *b) | |
394 | { | |
395 | struct dm_bufio_client *c = b->c; | |
396 | ||
397 | adjust_total_allocated(b->data_mode, -(long)c->block_size); | |
398 | ||
399 | free_buffer_data(c, b->data, b->data_mode); | |
400 | kfree(b); | |
401 | } | |
402 | ||
403 | /* | |
404 | * Link buffer to the hash list and clean or dirty queue. | |
405 | */ | |
406 | static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty) | |
407 | { | |
408 | struct dm_bufio_client *c = b->c; | |
409 | ||
410 | c->n_buffers[dirty]++; | |
411 | b->block = block; | |
412 | b->list_mode = dirty; | |
413 | list_add(&b->lru_list, &c->lru[dirty]); | |
414 | hlist_add_head(&b->hash_list, &c->cache_hash[DM_BUFIO_HASH(block)]); | |
415 | b->last_accessed = jiffies; | |
416 | } | |
417 | ||
418 | /* | |
419 | * Unlink buffer from the hash list and dirty or clean queue. | |
420 | */ | |
421 | static void __unlink_buffer(struct dm_buffer *b) | |
422 | { | |
423 | struct dm_bufio_client *c = b->c; | |
424 | ||
425 | BUG_ON(!c->n_buffers[b->list_mode]); | |
426 | ||
427 | c->n_buffers[b->list_mode]--; | |
428 | hlist_del(&b->hash_list); | |
429 | list_del(&b->lru_list); | |
430 | } | |
431 | ||
432 | /* | |
433 | * Place the buffer to the head of dirty or clean LRU queue. | |
434 | */ | |
435 | static void __relink_lru(struct dm_buffer *b, int dirty) | |
436 | { | |
437 | struct dm_bufio_client *c = b->c; | |
438 | ||
439 | BUG_ON(!c->n_buffers[b->list_mode]); | |
440 | ||
441 | c->n_buffers[b->list_mode]--; | |
442 | c->n_buffers[dirty]++; | |
443 | b->list_mode = dirty; | |
444 | list_del(&b->lru_list); | |
445 | list_add(&b->lru_list, &c->lru[dirty]); | |
446 | } | |
447 | ||
448 | /*---------------------------------------------------------------- | |
449 | * Submit I/O on the buffer. | |
450 | * | |
451 | * Bio interface is faster but it has some problems: | |
452 | * the vector list is limited (increasing this limit increases | |
453 | * memory-consumption per buffer, so it is not viable); | |
454 | * | |
455 | * the memory must be direct-mapped, not vmalloced; | |
456 | * | |
457 | * the I/O driver can reject requests spuriously if it thinks that | |
458 | * the requests are too big for the device or if they cross a | |
459 | * controller-defined memory boundary. | |
460 | * | |
461 | * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and | |
462 | * it is not vmalloced, try using the bio interface. | |
463 | * | |
464 | * If the buffer is big, if it is vmalloced or if the underlying device | |
465 | * rejects the bio because it is too large, use dm-io layer to do the I/O. | |
466 | * The dm-io layer splits the I/O into multiple requests, avoiding the above | |
467 | * shortcomings. | |
468 | *--------------------------------------------------------------*/ | |
469 | ||
470 | /* | |
471 | * dm-io completion routine. It just calls b->bio.bi_end_io, pretending | |
472 | * that the request was handled directly with bio interface. | |
473 | */ | |
474 | static void dmio_complete(unsigned long error, void *context) | |
475 | { | |
476 | struct dm_buffer *b = context; | |
477 | ||
478 | b->bio.bi_end_io(&b->bio, error ? -EIO : 0); | |
479 | } | |
480 | ||
481 | static void use_dmio(struct dm_buffer *b, int rw, sector_t block, | |
482 | bio_end_io_t *end_io) | |
483 | { | |
484 | int r; | |
485 | struct dm_io_request io_req = { | |
486 | .bi_rw = rw, | |
487 | .notify.fn = dmio_complete, | |
488 | .notify.context = b, | |
489 | .client = b->c->dm_io, | |
490 | }; | |
491 | struct dm_io_region region = { | |
492 | .bdev = b->c->bdev, | |
493 | .sector = block << b->c->sectors_per_block_bits, | |
494 | .count = b->c->block_size >> SECTOR_SHIFT, | |
495 | }; | |
496 | ||
497 | if (b->data_mode != DATA_MODE_VMALLOC) { | |
498 | io_req.mem.type = DM_IO_KMEM; | |
499 | io_req.mem.ptr.addr = b->data; | |
500 | } else { | |
501 | io_req.mem.type = DM_IO_VMA; | |
502 | io_req.mem.ptr.vma = b->data; | |
503 | } | |
504 | ||
505 | b->bio.bi_end_io = end_io; | |
506 | ||
507 | r = dm_io(&io_req, 1, ®ion, NULL); | |
508 | if (r) | |
509 | end_io(&b->bio, r); | |
510 | } | |
511 | ||
512 | static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block, | |
513 | bio_end_io_t *end_io) | |
514 | { | |
515 | char *ptr; | |
516 | int len; | |
517 | ||
518 | bio_init(&b->bio); | |
519 | b->bio.bi_io_vec = b->bio_vec; | |
520 | b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS; | |
521 | b->bio.bi_sector = block << b->c->sectors_per_block_bits; | |
522 | b->bio.bi_bdev = b->c->bdev; | |
523 | b->bio.bi_end_io = end_io; | |
524 | ||
525 | /* | |
526 | * We assume that if len >= PAGE_SIZE ptr is page-aligned. | |
527 | * If len < PAGE_SIZE the buffer doesn't cross page boundary. | |
528 | */ | |
529 | ptr = b->data; | |
530 | len = b->c->block_size; | |
531 | ||
532 | if (len >= PAGE_SIZE) | |
533 | BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1)); | |
534 | else | |
535 | BUG_ON((unsigned long)ptr & (len - 1)); | |
536 | ||
537 | do { | |
538 | if (!bio_add_page(&b->bio, virt_to_page(ptr), | |
539 | len < PAGE_SIZE ? len : PAGE_SIZE, | |
540 | virt_to_phys(ptr) & (PAGE_SIZE - 1))) { | |
541 | BUG_ON(b->c->block_size <= PAGE_SIZE); | |
542 | use_dmio(b, rw, block, end_io); | |
543 | return; | |
544 | } | |
545 | ||
546 | len -= PAGE_SIZE; | |
547 | ptr += PAGE_SIZE; | |
548 | } while (len > 0); | |
549 | ||
550 | submit_bio(rw, &b->bio); | |
551 | } | |
552 | ||
553 | static void submit_io(struct dm_buffer *b, int rw, sector_t block, | |
554 | bio_end_io_t *end_io) | |
555 | { | |
556 | if (rw == WRITE && b->c->write_callback) | |
557 | b->c->write_callback(b); | |
558 | ||
559 | if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE && | |
560 | b->data_mode != DATA_MODE_VMALLOC) | |
561 | use_inline_bio(b, rw, block, end_io); | |
562 | else | |
563 | use_dmio(b, rw, block, end_io); | |
564 | } | |
565 | ||
566 | /*---------------------------------------------------------------- | |
567 | * Writing dirty buffers | |
568 | *--------------------------------------------------------------*/ | |
569 | ||
570 | /* | |
571 | * The endio routine for write. | |
572 | * | |
573 | * Set the error, clear B_WRITING bit and wake anyone who was waiting on | |
574 | * it. | |
575 | */ | |
576 | static void write_endio(struct bio *bio, int error) | |
577 | { | |
578 | struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); | |
579 | ||
580 | b->write_error = error; | |
581 | if (error) { | |
582 | struct dm_bufio_client *c = b->c; | |
583 | (void)cmpxchg(&c->async_write_error, 0, error); | |
584 | } | |
585 | ||
586 | BUG_ON(!test_bit(B_WRITING, &b->state)); | |
587 | ||
588 | smp_mb__before_clear_bit(); | |
589 | clear_bit(B_WRITING, &b->state); | |
590 | smp_mb__after_clear_bit(); | |
591 | ||
592 | wake_up_bit(&b->state, B_WRITING); | |
593 | } | |
594 | ||
595 | /* | |
596 | * This function is called when wait_on_bit is actually waiting. | |
597 | */ | |
598 | static int do_io_schedule(void *word) | |
599 | { | |
600 | io_schedule(); | |
601 | ||
602 | return 0; | |
603 | } | |
604 | ||
605 | /* | |
606 | * Initiate a write on a dirty buffer, but don't wait for it. | |
607 | * | |
608 | * - If the buffer is not dirty, exit. | |
609 | * - If there some previous write going on, wait for it to finish (we can't | |
610 | * have two writes on the same buffer simultaneously). | |
611 | * - Submit our write and don't wait on it. We set B_WRITING indicating | |
612 | * that there is a write in progress. | |
613 | */ | |
614 | static void __write_dirty_buffer(struct dm_buffer *b) | |
615 | { | |
616 | if (!test_bit(B_DIRTY, &b->state)) | |
617 | return; | |
618 | ||
619 | clear_bit(B_DIRTY, &b->state); | |
620 | wait_on_bit_lock(&b->state, B_WRITING, | |
621 | do_io_schedule, TASK_UNINTERRUPTIBLE); | |
622 | ||
623 | submit_io(b, WRITE, b->block, write_endio); | |
624 | } | |
625 | ||
626 | /* | |
627 | * Wait until any activity on the buffer finishes. Possibly write the | |
628 | * buffer if it is dirty. When this function finishes, there is no I/O | |
629 | * running on the buffer and the buffer is not dirty. | |
630 | */ | |
631 | static void __make_buffer_clean(struct dm_buffer *b) | |
632 | { | |
633 | BUG_ON(b->hold_count); | |
634 | ||
635 | if (!b->state) /* fast case */ | |
636 | return; | |
637 | ||
638 | wait_on_bit(&b->state, B_READING, do_io_schedule, TASK_UNINTERRUPTIBLE); | |
639 | __write_dirty_buffer(b); | |
640 | wait_on_bit(&b->state, B_WRITING, do_io_schedule, TASK_UNINTERRUPTIBLE); | |
641 | } | |
642 | ||
643 | /* | |
644 | * Find some buffer that is not held by anybody, clean it, unlink it and | |
645 | * return it. | |
646 | */ | |
647 | static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) | |
648 | { | |
649 | struct dm_buffer *b; | |
650 | ||
651 | list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) { | |
652 | BUG_ON(test_bit(B_WRITING, &b->state)); | |
653 | BUG_ON(test_bit(B_DIRTY, &b->state)); | |
654 | ||
655 | if (!b->hold_count) { | |
656 | __make_buffer_clean(b); | |
657 | __unlink_buffer(b); | |
658 | return b; | |
659 | } | |
660 | dm_bufio_cond_resched(); | |
661 | } | |
662 | ||
663 | list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { | |
664 | BUG_ON(test_bit(B_READING, &b->state)); | |
665 | ||
666 | if (!b->hold_count) { | |
667 | __make_buffer_clean(b); | |
668 | __unlink_buffer(b); | |
669 | return b; | |
670 | } | |
671 | dm_bufio_cond_resched(); | |
672 | } | |
673 | ||
674 | return NULL; | |
675 | } | |
676 | ||
677 | /* | |
678 | * Wait until some other threads free some buffer or release hold count on | |
679 | * some buffer. | |
680 | * | |
681 | * This function is entered with c->lock held, drops it and regains it | |
682 | * before exiting. | |
683 | */ | |
684 | static void __wait_for_free_buffer(struct dm_bufio_client *c) | |
685 | { | |
686 | DECLARE_WAITQUEUE(wait, current); | |
687 | ||
688 | add_wait_queue(&c->free_buffer_wait, &wait); | |
689 | set_task_state(current, TASK_UNINTERRUPTIBLE); | |
690 | dm_bufio_unlock(c); | |
691 | ||
692 | io_schedule(); | |
693 | ||
694 | set_task_state(current, TASK_RUNNING); | |
695 | remove_wait_queue(&c->free_buffer_wait, &wait); | |
696 | ||
697 | dm_bufio_lock(c); | |
698 | } | |
699 | ||
700 | /* | |
701 | * Allocate a new buffer. If the allocation is not possible, wait until | |
702 | * some other thread frees a buffer. | |
703 | * | |
704 | * May drop the lock and regain it. | |
705 | */ | |
706 | static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c) | |
707 | { | |
708 | struct dm_buffer *b; | |
709 | ||
710 | /* | |
711 | * dm-bufio is resistant to allocation failures (it just keeps | |
712 | * one buffer reserved in cases all the allocations fail). | |
713 | * So set flags to not try too hard: | |
714 | * GFP_NOIO: don't recurse into the I/O layer | |
715 | * __GFP_NORETRY: don't retry and rather return failure | |
716 | * __GFP_NOMEMALLOC: don't use emergency reserves | |
717 | * __GFP_NOWARN: don't print a warning in case of failure | |
718 | * | |
719 | * For debugging, if we set the cache size to 1, no new buffers will | |
720 | * be allocated. | |
721 | */ | |
722 | while (1) { | |
723 | if (dm_bufio_cache_size_latch != 1) { | |
724 | b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
725 | if (b) | |
726 | return b; | |
727 | } | |
728 | ||
729 | if (!list_empty(&c->reserved_buffers)) { | |
730 | b = list_entry(c->reserved_buffers.next, | |
731 | struct dm_buffer, lru_list); | |
732 | list_del(&b->lru_list); | |
733 | c->need_reserved_buffers++; | |
734 | ||
735 | return b; | |
736 | } | |
737 | ||
738 | b = __get_unclaimed_buffer(c); | |
739 | if (b) | |
740 | return b; | |
741 | ||
742 | __wait_for_free_buffer(c); | |
743 | } | |
744 | } | |
745 | ||
746 | static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c) | |
747 | { | |
748 | struct dm_buffer *b = __alloc_buffer_wait_no_callback(c); | |
749 | ||
750 | if (c->alloc_callback) | |
751 | c->alloc_callback(b); | |
752 | ||
753 | return b; | |
754 | } | |
755 | ||
756 | /* | |
757 | * Free a buffer and wake other threads waiting for free buffers. | |
758 | */ | |
759 | static void __free_buffer_wake(struct dm_buffer *b) | |
760 | { | |
761 | struct dm_bufio_client *c = b->c; | |
762 | ||
763 | if (!c->need_reserved_buffers) | |
764 | free_buffer(b); | |
765 | else { | |
766 | list_add(&b->lru_list, &c->reserved_buffers); | |
767 | c->need_reserved_buffers--; | |
768 | } | |
769 | ||
770 | wake_up(&c->free_buffer_wait); | |
771 | } | |
772 | ||
773 | static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait) | |
774 | { | |
775 | struct dm_buffer *b, *tmp; | |
776 | ||
777 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { | |
778 | BUG_ON(test_bit(B_READING, &b->state)); | |
779 | ||
780 | if (!test_bit(B_DIRTY, &b->state) && | |
781 | !test_bit(B_WRITING, &b->state)) { | |
782 | __relink_lru(b, LIST_CLEAN); | |
783 | continue; | |
784 | } | |
785 | ||
786 | if (no_wait && test_bit(B_WRITING, &b->state)) | |
787 | return; | |
788 | ||
789 | __write_dirty_buffer(b); | |
790 | dm_bufio_cond_resched(); | |
791 | } | |
792 | } | |
793 | ||
794 | /* | |
795 | * Get writeback threshold and buffer limit for a given client. | |
796 | */ | |
797 | static void __get_memory_limit(struct dm_bufio_client *c, | |
798 | unsigned long *threshold_buffers, | |
799 | unsigned long *limit_buffers) | |
800 | { | |
801 | unsigned long buffers; | |
802 | ||
803 | if (dm_bufio_cache_size != dm_bufio_cache_size_latch) { | |
804 | mutex_lock(&dm_bufio_clients_lock); | |
805 | __cache_size_refresh(); | |
806 | mutex_unlock(&dm_bufio_clients_lock); | |
807 | } | |
808 | ||
809 | buffers = dm_bufio_cache_size_per_client >> | |
810 | (c->sectors_per_block_bits + SECTOR_SHIFT); | |
811 | ||
812 | if (buffers < DM_BUFIO_MIN_BUFFERS) | |
813 | buffers = DM_BUFIO_MIN_BUFFERS; | |
814 | ||
815 | *limit_buffers = buffers; | |
816 | *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100; | |
817 | } | |
818 | ||
819 | /* | |
820 | * Check if we're over watermark. | |
821 | * If we are over threshold_buffers, start freeing buffers. | |
822 | * If we're over "limit_buffers", block until we get under the limit. | |
823 | */ | |
824 | static void __check_watermark(struct dm_bufio_client *c) | |
825 | { | |
826 | unsigned long threshold_buffers, limit_buffers; | |
827 | ||
828 | __get_memory_limit(c, &threshold_buffers, &limit_buffers); | |
829 | ||
830 | while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] > | |
831 | limit_buffers) { | |
832 | ||
833 | struct dm_buffer *b = __get_unclaimed_buffer(c); | |
834 | ||
835 | if (!b) | |
836 | return; | |
837 | ||
838 | __free_buffer_wake(b); | |
839 | dm_bufio_cond_resched(); | |
840 | } | |
841 | ||
842 | if (c->n_buffers[LIST_DIRTY] > threshold_buffers) | |
843 | __write_dirty_buffers_async(c, 1); | |
844 | } | |
845 | ||
846 | /* | |
847 | * Find a buffer in the hash. | |
848 | */ | |
849 | static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) | |
850 | { | |
851 | struct dm_buffer *b; | |
852 | struct hlist_node *hn; | |
853 | ||
854 | hlist_for_each_entry(b, hn, &c->cache_hash[DM_BUFIO_HASH(block)], | |
855 | hash_list) { | |
856 | dm_bufio_cond_resched(); | |
857 | if (b->block == block) | |
858 | return b; | |
859 | } | |
860 | ||
861 | return NULL; | |
862 | } | |
863 | ||
864 | /*---------------------------------------------------------------- | |
865 | * Getting a buffer | |
866 | *--------------------------------------------------------------*/ | |
867 | ||
868 | enum new_flag { | |
869 | NF_FRESH = 0, | |
870 | NF_READ = 1, | |
871 | NF_GET = 2 | |
872 | }; | |
873 | ||
874 | static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, | |
875 | enum new_flag nf, struct dm_buffer **bp, | |
876 | int *need_submit) | |
877 | { | |
878 | struct dm_buffer *b, *new_b = NULL; | |
879 | ||
880 | *need_submit = 0; | |
881 | ||
882 | b = __find(c, block); | |
883 | if (b) { | |
884 | b->hold_count++; | |
885 | __relink_lru(b, test_bit(B_DIRTY, &b->state) || | |
886 | test_bit(B_WRITING, &b->state)); | |
887 | return b; | |
888 | } | |
889 | ||
890 | if (nf == NF_GET) | |
891 | return NULL; | |
892 | ||
893 | new_b = __alloc_buffer_wait(c); | |
894 | ||
895 | /* | |
896 | * We've had a period where the mutex was unlocked, so need to | |
897 | * recheck the hash table. | |
898 | */ | |
899 | b = __find(c, block); | |
900 | if (b) { | |
901 | __free_buffer_wake(new_b); | |
902 | b->hold_count++; | |
903 | __relink_lru(b, test_bit(B_DIRTY, &b->state) || | |
904 | test_bit(B_WRITING, &b->state)); | |
905 | return b; | |
906 | } | |
907 | ||
908 | __check_watermark(c); | |
909 | ||
910 | b = new_b; | |
911 | b->hold_count = 1; | |
912 | b->read_error = 0; | |
913 | b->write_error = 0; | |
914 | __link_buffer(b, block, LIST_CLEAN); | |
915 | ||
916 | if (nf == NF_FRESH) { | |
917 | b->state = 0; | |
918 | return b; | |
919 | } | |
920 | ||
921 | b->state = 1 << B_READING; | |
922 | *need_submit = 1; | |
923 | ||
924 | return b; | |
925 | } | |
926 | ||
927 | /* | |
928 | * The endio routine for reading: set the error, clear the bit and wake up | |
929 | * anyone waiting on the buffer. | |
930 | */ | |
931 | static void read_endio(struct bio *bio, int error) | |
932 | { | |
933 | struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); | |
934 | ||
935 | b->read_error = error; | |
936 | ||
937 | BUG_ON(!test_bit(B_READING, &b->state)); | |
938 | ||
939 | smp_mb__before_clear_bit(); | |
940 | clear_bit(B_READING, &b->state); | |
941 | smp_mb__after_clear_bit(); | |
942 | ||
943 | wake_up_bit(&b->state, B_READING); | |
944 | } | |
945 | ||
946 | /* | |
947 | * A common routine for dm_bufio_new and dm_bufio_read. Operation of these | |
948 | * functions is similar except that dm_bufio_new doesn't read the | |
949 | * buffer from the disk (assuming that the caller overwrites all the data | |
950 | * and uses dm_bufio_mark_buffer_dirty to write new data back). | |
951 | */ | |
952 | static void *new_read(struct dm_bufio_client *c, sector_t block, | |
953 | enum new_flag nf, struct dm_buffer **bp) | |
954 | { | |
955 | int need_submit; | |
956 | struct dm_buffer *b; | |
957 | ||
958 | dm_bufio_lock(c); | |
959 | b = __bufio_new(c, block, nf, bp, &need_submit); | |
960 | dm_bufio_unlock(c); | |
961 | ||
962 | if (!b || IS_ERR(b)) | |
963 | return b; | |
964 | ||
965 | if (need_submit) | |
966 | submit_io(b, READ, b->block, read_endio); | |
967 | ||
968 | wait_on_bit(&b->state, B_READING, do_io_schedule, TASK_UNINTERRUPTIBLE); | |
969 | ||
970 | if (b->read_error) { | |
971 | int error = b->read_error; | |
972 | ||
973 | dm_bufio_release(b); | |
974 | ||
975 | return ERR_PTR(error); | |
976 | } | |
977 | ||
978 | *bp = b; | |
979 | ||
980 | return b->data; | |
981 | } | |
982 | ||
983 | void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, | |
984 | struct dm_buffer **bp) | |
985 | { | |
986 | return new_read(c, block, NF_GET, bp); | |
987 | } | |
988 | EXPORT_SYMBOL_GPL(dm_bufio_get); | |
989 | ||
990 | void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, | |
991 | struct dm_buffer **bp) | |
992 | { | |
993 | BUG_ON(dm_bufio_in_request()); | |
994 | ||
995 | return new_read(c, block, NF_READ, bp); | |
996 | } | |
997 | EXPORT_SYMBOL_GPL(dm_bufio_read); | |
998 | ||
999 | void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, | |
1000 | struct dm_buffer **bp) | |
1001 | { | |
1002 | BUG_ON(dm_bufio_in_request()); | |
1003 | ||
1004 | return new_read(c, block, NF_FRESH, bp); | |
1005 | } | |
1006 | EXPORT_SYMBOL_GPL(dm_bufio_new); | |
1007 | ||
1008 | void dm_bufio_release(struct dm_buffer *b) | |
1009 | { | |
1010 | struct dm_bufio_client *c = b->c; | |
1011 | ||
1012 | dm_bufio_lock(c); | |
1013 | ||
1014 | BUG_ON(test_bit(B_READING, &b->state)); | |
1015 | BUG_ON(!b->hold_count); | |
1016 | ||
1017 | b->hold_count--; | |
1018 | if (!b->hold_count) { | |
1019 | wake_up(&c->free_buffer_wait); | |
1020 | ||
1021 | /* | |
1022 | * If there were errors on the buffer, and the buffer is not | |
1023 | * to be written, free the buffer. There is no point in caching | |
1024 | * invalid buffer. | |
1025 | */ | |
1026 | if ((b->read_error || b->write_error) && | |
1027 | !test_bit(B_WRITING, &b->state) && | |
1028 | !test_bit(B_DIRTY, &b->state)) { | |
1029 | __unlink_buffer(b); | |
1030 | __free_buffer_wake(b); | |
1031 | } | |
1032 | } | |
1033 | ||
1034 | dm_bufio_unlock(c); | |
1035 | } | |
1036 | EXPORT_SYMBOL_GPL(dm_bufio_release); | |
1037 | ||
1038 | void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) | |
1039 | { | |
1040 | struct dm_bufio_client *c = b->c; | |
1041 | ||
1042 | dm_bufio_lock(c); | |
1043 | ||
1044 | if (!test_and_set_bit(B_DIRTY, &b->state)) | |
1045 | __relink_lru(b, LIST_DIRTY); | |
1046 | ||
1047 | dm_bufio_unlock(c); | |
1048 | } | |
1049 | EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty); | |
1050 | ||
1051 | void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) | |
1052 | { | |
1053 | BUG_ON(dm_bufio_in_request()); | |
1054 | ||
1055 | dm_bufio_lock(c); | |
1056 | __write_dirty_buffers_async(c, 0); | |
1057 | dm_bufio_unlock(c); | |
1058 | } | |
1059 | EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); | |
1060 | ||
1061 | /* | |
1062 | * For performance, it is essential that the buffers are written asynchronously | |
1063 | * and simultaneously (so that the block layer can merge the writes) and then | |
1064 | * waited upon. | |
1065 | * | |
1066 | * Finally, we flush hardware disk cache. | |
1067 | */ | |
1068 | int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) | |
1069 | { | |
1070 | int a, f; | |
1071 | unsigned long buffers_processed = 0; | |
1072 | struct dm_buffer *b, *tmp; | |
1073 | ||
1074 | dm_bufio_lock(c); | |
1075 | __write_dirty_buffers_async(c, 0); | |
1076 | ||
1077 | again: | |
1078 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { | |
1079 | int dropped_lock = 0; | |
1080 | ||
1081 | if (buffers_processed < c->n_buffers[LIST_DIRTY]) | |
1082 | buffers_processed++; | |
1083 | ||
1084 | BUG_ON(test_bit(B_READING, &b->state)); | |
1085 | ||
1086 | if (test_bit(B_WRITING, &b->state)) { | |
1087 | if (buffers_processed < c->n_buffers[LIST_DIRTY]) { | |
1088 | dropped_lock = 1; | |
1089 | b->hold_count++; | |
1090 | dm_bufio_unlock(c); | |
1091 | wait_on_bit(&b->state, B_WRITING, | |
1092 | do_io_schedule, | |
1093 | TASK_UNINTERRUPTIBLE); | |
1094 | dm_bufio_lock(c); | |
1095 | b->hold_count--; | |
1096 | } else | |
1097 | wait_on_bit(&b->state, B_WRITING, | |
1098 | do_io_schedule, | |
1099 | TASK_UNINTERRUPTIBLE); | |
1100 | } | |
1101 | ||
1102 | if (!test_bit(B_DIRTY, &b->state) && | |
1103 | !test_bit(B_WRITING, &b->state)) | |
1104 | __relink_lru(b, LIST_CLEAN); | |
1105 | ||
1106 | dm_bufio_cond_resched(); | |
1107 | ||
1108 | /* | |
1109 | * If we dropped the lock, the list is no longer consistent, | |
1110 | * so we must restart the search. | |
1111 | * | |
1112 | * In the most common case, the buffer just processed is | |
1113 | * relinked to the clean list, so we won't loop scanning the | |
1114 | * same buffer again and again. | |
1115 | * | |
1116 | * This may livelock if there is another thread simultaneously | |
1117 | * dirtying buffers, so we count the number of buffers walked | |
1118 | * and if it exceeds the total number of buffers, it means that | |
1119 | * someone is doing some writes simultaneously with us. In | |
1120 | * this case, stop, dropping the lock. | |
1121 | */ | |
1122 | if (dropped_lock) | |
1123 | goto again; | |
1124 | } | |
1125 | wake_up(&c->free_buffer_wait); | |
1126 | dm_bufio_unlock(c); | |
1127 | ||
1128 | a = xchg(&c->async_write_error, 0); | |
1129 | f = dm_bufio_issue_flush(c); | |
1130 | if (a) | |
1131 | return a; | |
1132 | ||
1133 | return f; | |
1134 | } | |
1135 | EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers); | |
1136 | ||
1137 | /* | |
1138 | * Use dm-io to send and empty barrier flush the device. | |
1139 | */ | |
1140 | int dm_bufio_issue_flush(struct dm_bufio_client *c) | |
1141 | { | |
1142 | struct dm_io_request io_req = { | |
1143 | .bi_rw = REQ_FLUSH, | |
1144 | .mem.type = DM_IO_KMEM, | |
1145 | .mem.ptr.addr = NULL, | |
1146 | .client = c->dm_io, | |
1147 | }; | |
1148 | struct dm_io_region io_reg = { | |
1149 | .bdev = c->bdev, | |
1150 | .sector = 0, | |
1151 | .count = 0, | |
1152 | }; | |
1153 | ||
1154 | BUG_ON(dm_bufio_in_request()); | |
1155 | ||
1156 | return dm_io(&io_req, 1, &io_reg, NULL); | |
1157 | } | |
1158 | EXPORT_SYMBOL_GPL(dm_bufio_issue_flush); | |
1159 | ||
1160 | /* | |
1161 | * We first delete any other buffer that may be at that new location. | |
1162 | * | |
1163 | * Then, we write the buffer to the original location if it was dirty. | |
1164 | * | |
1165 | * Then, if we are the only one who is holding the buffer, relink the buffer | |
1166 | * in the hash queue for the new location. | |
1167 | * | |
1168 | * If there was someone else holding the buffer, we write it to the new | |
1169 | * location but not relink it, because that other user needs to have the buffer | |
1170 | * at the same place. | |
1171 | */ | |
1172 | void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block) | |
1173 | { | |
1174 | struct dm_bufio_client *c = b->c; | |
1175 | struct dm_buffer *new; | |
1176 | ||
1177 | BUG_ON(dm_bufio_in_request()); | |
1178 | ||
1179 | dm_bufio_lock(c); | |
1180 | ||
1181 | retry: | |
1182 | new = __find(c, new_block); | |
1183 | if (new) { | |
1184 | if (new->hold_count) { | |
1185 | __wait_for_free_buffer(c); | |
1186 | goto retry; | |
1187 | } | |
1188 | ||
1189 | /* | |
1190 | * FIXME: Is there any point waiting for a write that's going | |
1191 | * to be overwritten in a bit? | |
1192 | */ | |
1193 | __make_buffer_clean(new); | |
1194 | __unlink_buffer(new); | |
1195 | __free_buffer_wake(new); | |
1196 | } | |
1197 | ||
1198 | BUG_ON(!b->hold_count); | |
1199 | BUG_ON(test_bit(B_READING, &b->state)); | |
1200 | ||
1201 | __write_dirty_buffer(b); | |
1202 | if (b->hold_count == 1) { | |
1203 | wait_on_bit(&b->state, B_WRITING, | |
1204 | do_io_schedule, TASK_UNINTERRUPTIBLE); | |
1205 | set_bit(B_DIRTY, &b->state); | |
1206 | __unlink_buffer(b); | |
1207 | __link_buffer(b, new_block, LIST_DIRTY); | |
1208 | } else { | |
1209 | sector_t old_block; | |
1210 | wait_on_bit_lock(&b->state, B_WRITING, | |
1211 | do_io_schedule, TASK_UNINTERRUPTIBLE); | |
1212 | /* | |
1213 | * Relink buffer to "new_block" so that write_callback | |
1214 | * sees "new_block" as a block number. | |
1215 | * After the write, link the buffer back to old_block. | |
1216 | * All this must be done in bufio lock, so that block number | |
1217 | * change isn't visible to other threads. | |
1218 | */ | |
1219 | old_block = b->block; | |
1220 | __unlink_buffer(b); | |
1221 | __link_buffer(b, new_block, b->list_mode); | |
1222 | submit_io(b, WRITE, new_block, write_endio); | |
1223 | wait_on_bit(&b->state, B_WRITING, | |
1224 | do_io_schedule, TASK_UNINTERRUPTIBLE); | |
1225 | __unlink_buffer(b); | |
1226 | __link_buffer(b, old_block, b->list_mode); | |
1227 | } | |
1228 | ||
1229 | dm_bufio_unlock(c); | |
1230 | dm_bufio_release(b); | |
1231 | } | |
1232 | EXPORT_SYMBOL_GPL(dm_bufio_release_move); | |
1233 | ||
1234 | unsigned dm_bufio_get_block_size(struct dm_bufio_client *c) | |
1235 | { | |
1236 | return c->block_size; | |
1237 | } | |
1238 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_size); | |
1239 | ||
1240 | sector_t dm_bufio_get_device_size(struct dm_bufio_client *c) | |
1241 | { | |
1242 | return i_size_read(c->bdev->bd_inode) >> | |
1243 | (SECTOR_SHIFT + c->sectors_per_block_bits); | |
1244 | } | |
1245 | EXPORT_SYMBOL_GPL(dm_bufio_get_device_size); | |
1246 | ||
1247 | sector_t dm_bufio_get_block_number(struct dm_buffer *b) | |
1248 | { | |
1249 | return b->block; | |
1250 | } | |
1251 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_number); | |
1252 | ||
1253 | void *dm_bufio_get_block_data(struct dm_buffer *b) | |
1254 | { | |
1255 | return b->data; | |
1256 | } | |
1257 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_data); | |
1258 | ||
1259 | void *dm_bufio_get_aux_data(struct dm_buffer *b) | |
1260 | { | |
1261 | return b + 1; | |
1262 | } | |
1263 | EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data); | |
1264 | ||
1265 | struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) | |
1266 | { | |
1267 | return b->c; | |
1268 | } | |
1269 | EXPORT_SYMBOL_GPL(dm_bufio_get_client); | |
1270 | ||
1271 | static void drop_buffers(struct dm_bufio_client *c) | |
1272 | { | |
1273 | struct dm_buffer *b; | |
1274 | int i; | |
1275 | ||
1276 | BUG_ON(dm_bufio_in_request()); | |
1277 | ||
1278 | /* | |
1279 | * An optimization so that the buffers are not written one-by-one. | |
1280 | */ | |
1281 | dm_bufio_write_dirty_buffers_async(c); | |
1282 | ||
1283 | dm_bufio_lock(c); | |
1284 | ||
1285 | while ((b = __get_unclaimed_buffer(c))) | |
1286 | __free_buffer_wake(b); | |
1287 | ||
1288 | for (i = 0; i < LIST_SIZE; i++) | |
1289 | list_for_each_entry(b, &c->lru[i], lru_list) | |
1290 | DMERR("leaked buffer %llx, hold count %u, list %d", | |
1291 | (unsigned long long)b->block, b->hold_count, i); | |
1292 | ||
1293 | for (i = 0; i < LIST_SIZE; i++) | |
1294 | BUG_ON(!list_empty(&c->lru[i])); | |
1295 | ||
1296 | dm_bufio_unlock(c); | |
1297 | } | |
1298 | ||
1299 | /* | |
1300 | * Test if the buffer is unused and too old, and commit it. | |
1301 | * At if noio is set, we must not do any I/O because we hold | |
1302 | * dm_bufio_clients_lock and we would risk deadlock if the I/O gets rerouted to | |
1303 | * different bufio client. | |
1304 | */ | |
1305 | static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp, | |
1306 | unsigned long max_jiffies) | |
1307 | { | |
1308 | if (jiffies - b->last_accessed < max_jiffies) | |
1309 | return 1; | |
1310 | ||
1311 | if (!(gfp & __GFP_IO)) { | |
1312 | if (test_bit(B_READING, &b->state) || | |
1313 | test_bit(B_WRITING, &b->state) || | |
1314 | test_bit(B_DIRTY, &b->state)) | |
1315 | return 1; | |
1316 | } | |
1317 | ||
1318 | if (b->hold_count) | |
1319 | return 1; | |
1320 | ||
1321 | __make_buffer_clean(b); | |
1322 | __unlink_buffer(b); | |
1323 | __free_buffer_wake(b); | |
1324 | ||
1325 | return 0; | |
1326 | } | |
1327 | ||
1328 | static void __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, | |
1329 | struct shrink_control *sc) | |
1330 | { | |
1331 | int l; | |
1332 | struct dm_buffer *b, *tmp; | |
1333 | ||
1334 | for (l = 0; l < LIST_SIZE; l++) { | |
1335 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) | |
1336 | if (!__cleanup_old_buffer(b, sc->gfp_mask, 0) && | |
1337 | !--nr_to_scan) | |
1338 | return; | |
1339 | dm_bufio_cond_resched(); | |
1340 | } | |
1341 | } | |
1342 | ||
1343 | static int shrink(struct shrinker *shrinker, struct shrink_control *sc) | |
1344 | { | |
1345 | struct dm_bufio_client *c = | |
1346 | container_of(shrinker, struct dm_bufio_client, shrinker); | |
1347 | unsigned long r; | |
1348 | unsigned long nr_to_scan = sc->nr_to_scan; | |
1349 | ||
1350 | if (sc->gfp_mask & __GFP_IO) | |
1351 | dm_bufio_lock(c); | |
1352 | else if (!dm_bufio_trylock(c)) | |
1353 | return !nr_to_scan ? 0 : -1; | |
1354 | ||
1355 | if (nr_to_scan) | |
1356 | __scan(c, nr_to_scan, sc); | |
1357 | ||
1358 | r = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; | |
1359 | if (r > INT_MAX) | |
1360 | r = INT_MAX; | |
1361 | ||
1362 | dm_bufio_unlock(c); | |
1363 | ||
1364 | return r; | |
1365 | } | |
1366 | ||
1367 | /* | |
1368 | * Create the buffering interface | |
1369 | */ | |
1370 | struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size, | |
1371 | unsigned reserved_buffers, unsigned aux_size, | |
1372 | void (*alloc_callback)(struct dm_buffer *), | |
1373 | void (*write_callback)(struct dm_buffer *)) | |
1374 | { | |
1375 | int r; | |
1376 | struct dm_bufio_client *c; | |
1377 | unsigned i; | |
1378 | ||
1379 | BUG_ON(block_size < 1 << SECTOR_SHIFT || | |
1380 | (block_size & (block_size - 1))); | |
1381 | ||
1382 | c = kmalloc(sizeof(*c), GFP_KERNEL); | |
1383 | if (!c) { | |
1384 | r = -ENOMEM; | |
1385 | goto bad_client; | |
1386 | } | |
1387 | c->cache_hash = vmalloc(sizeof(struct hlist_head) << DM_BUFIO_HASH_BITS); | |
1388 | if (!c->cache_hash) { | |
1389 | r = -ENOMEM; | |
1390 | goto bad_hash; | |
1391 | } | |
1392 | ||
1393 | c->bdev = bdev; | |
1394 | c->block_size = block_size; | |
1395 | c->sectors_per_block_bits = ffs(block_size) - 1 - SECTOR_SHIFT; | |
1396 | c->pages_per_block_bits = (ffs(block_size) - 1 >= PAGE_SHIFT) ? | |
1397 | ffs(block_size) - 1 - PAGE_SHIFT : 0; | |
1398 | c->blocks_per_page_bits = (ffs(block_size) - 1 < PAGE_SHIFT ? | |
1399 | PAGE_SHIFT - (ffs(block_size) - 1) : 0); | |
1400 | ||
1401 | c->aux_size = aux_size; | |
1402 | c->alloc_callback = alloc_callback; | |
1403 | c->write_callback = write_callback; | |
1404 | ||
1405 | for (i = 0; i < LIST_SIZE; i++) { | |
1406 | INIT_LIST_HEAD(&c->lru[i]); | |
1407 | c->n_buffers[i] = 0; | |
1408 | } | |
1409 | ||
1410 | for (i = 0; i < 1 << DM_BUFIO_HASH_BITS; i++) | |
1411 | INIT_HLIST_HEAD(&c->cache_hash[i]); | |
1412 | ||
1413 | mutex_init(&c->lock); | |
1414 | INIT_LIST_HEAD(&c->reserved_buffers); | |
1415 | c->need_reserved_buffers = reserved_buffers; | |
1416 | ||
1417 | init_waitqueue_head(&c->free_buffer_wait); | |
1418 | c->async_write_error = 0; | |
1419 | ||
1420 | c->dm_io = dm_io_client_create(); | |
1421 | if (IS_ERR(c->dm_io)) { | |
1422 | r = PTR_ERR(c->dm_io); | |
1423 | goto bad_dm_io; | |
1424 | } | |
1425 | ||
1426 | mutex_lock(&dm_bufio_clients_lock); | |
1427 | if (c->blocks_per_page_bits) { | |
1428 | if (!DM_BUFIO_CACHE_NAME(c)) { | |
1429 | DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size); | |
1430 | if (!DM_BUFIO_CACHE_NAME(c)) { | |
1431 | r = -ENOMEM; | |
1432 | mutex_unlock(&dm_bufio_clients_lock); | |
1433 | goto bad_cache; | |
1434 | } | |
1435 | } | |
1436 | ||
1437 | if (!DM_BUFIO_CACHE(c)) { | |
1438 | DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c), | |
1439 | c->block_size, | |
1440 | c->block_size, 0, NULL); | |
1441 | if (!DM_BUFIO_CACHE(c)) { | |
1442 | r = -ENOMEM; | |
1443 | mutex_unlock(&dm_bufio_clients_lock); | |
1444 | goto bad_cache; | |
1445 | } | |
1446 | } | |
1447 | } | |
1448 | mutex_unlock(&dm_bufio_clients_lock); | |
1449 | ||
1450 | while (c->need_reserved_buffers) { | |
1451 | struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); | |
1452 | ||
1453 | if (!b) { | |
1454 | r = -ENOMEM; | |
1455 | goto bad_buffer; | |
1456 | } | |
1457 | __free_buffer_wake(b); | |
1458 | } | |
1459 | ||
1460 | mutex_lock(&dm_bufio_clients_lock); | |
1461 | dm_bufio_client_count++; | |
1462 | list_add(&c->client_list, &dm_bufio_all_clients); | |
1463 | __cache_size_refresh(); | |
1464 | mutex_unlock(&dm_bufio_clients_lock); | |
1465 | ||
1466 | c->shrinker.shrink = shrink; | |
1467 | c->shrinker.seeks = 1; | |
1468 | c->shrinker.batch = 0; | |
1469 | register_shrinker(&c->shrinker); | |
1470 | ||
1471 | return c; | |
1472 | ||
1473 | bad_buffer: | |
1474 | bad_cache: | |
1475 | while (!list_empty(&c->reserved_buffers)) { | |
1476 | struct dm_buffer *b = list_entry(c->reserved_buffers.next, | |
1477 | struct dm_buffer, lru_list); | |
1478 | list_del(&b->lru_list); | |
1479 | free_buffer(b); | |
1480 | } | |
1481 | dm_io_client_destroy(c->dm_io); | |
1482 | bad_dm_io: | |
1483 | vfree(c->cache_hash); | |
1484 | bad_hash: | |
1485 | kfree(c); | |
1486 | bad_client: | |
1487 | return ERR_PTR(r); | |
1488 | } | |
1489 | EXPORT_SYMBOL_GPL(dm_bufio_client_create); | |
1490 | ||
1491 | /* | |
1492 | * Free the buffering interface. | |
1493 | * It is required that there are no references on any buffers. | |
1494 | */ | |
1495 | void dm_bufio_client_destroy(struct dm_bufio_client *c) | |
1496 | { | |
1497 | unsigned i; | |
1498 | ||
1499 | drop_buffers(c); | |
1500 | ||
1501 | unregister_shrinker(&c->shrinker); | |
1502 | ||
1503 | mutex_lock(&dm_bufio_clients_lock); | |
1504 | ||
1505 | list_del(&c->client_list); | |
1506 | dm_bufio_client_count--; | |
1507 | __cache_size_refresh(); | |
1508 | ||
1509 | mutex_unlock(&dm_bufio_clients_lock); | |
1510 | ||
1511 | for (i = 0; i < 1 << DM_BUFIO_HASH_BITS; i++) | |
1512 | BUG_ON(!hlist_empty(&c->cache_hash[i])); | |
1513 | ||
1514 | BUG_ON(c->need_reserved_buffers); | |
1515 | ||
1516 | while (!list_empty(&c->reserved_buffers)) { | |
1517 | struct dm_buffer *b = list_entry(c->reserved_buffers.next, | |
1518 | struct dm_buffer, lru_list); | |
1519 | list_del(&b->lru_list); | |
1520 | free_buffer(b); | |
1521 | } | |
1522 | ||
1523 | for (i = 0; i < LIST_SIZE; i++) | |
1524 | if (c->n_buffers[i]) | |
1525 | DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]); | |
1526 | ||
1527 | for (i = 0; i < LIST_SIZE; i++) | |
1528 | BUG_ON(c->n_buffers[i]); | |
1529 | ||
1530 | dm_io_client_destroy(c->dm_io); | |
1531 | vfree(c->cache_hash); | |
1532 | kfree(c); | |
1533 | } | |
1534 | EXPORT_SYMBOL_GPL(dm_bufio_client_destroy); | |
1535 | ||
1536 | static void cleanup_old_buffers(void) | |
1537 | { | |
1538 | unsigned long max_age = dm_bufio_max_age; | |
1539 | struct dm_bufio_client *c; | |
1540 | ||
1541 | barrier(); | |
1542 | ||
1543 | if (max_age > ULONG_MAX / HZ) | |
1544 | max_age = ULONG_MAX / HZ; | |
1545 | ||
1546 | mutex_lock(&dm_bufio_clients_lock); | |
1547 | list_for_each_entry(c, &dm_bufio_all_clients, client_list) { | |
1548 | if (!dm_bufio_trylock(c)) | |
1549 | continue; | |
1550 | ||
1551 | while (!list_empty(&c->lru[LIST_CLEAN])) { | |
1552 | struct dm_buffer *b; | |
1553 | b = list_entry(c->lru[LIST_CLEAN].prev, | |
1554 | struct dm_buffer, lru_list); | |
1555 | if (__cleanup_old_buffer(b, 0, max_age * HZ)) | |
1556 | break; | |
1557 | dm_bufio_cond_resched(); | |
1558 | } | |
1559 | ||
1560 | dm_bufio_unlock(c); | |
1561 | dm_bufio_cond_resched(); | |
1562 | } | |
1563 | mutex_unlock(&dm_bufio_clients_lock); | |
1564 | } | |
1565 | ||
1566 | static struct workqueue_struct *dm_bufio_wq; | |
1567 | static struct delayed_work dm_bufio_work; | |
1568 | ||
1569 | static void work_fn(struct work_struct *w) | |
1570 | { | |
1571 | cleanup_old_buffers(); | |
1572 | ||
1573 | queue_delayed_work(dm_bufio_wq, &dm_bufio_work, | |
1574 | DM_BUFIO_WORK_TIMER_SECS * HZ); | |
1575 | } | |
1576 | ||
1577 | /*---------------------------------------------------------------- | |
1578 | * Module setup | |
1579 | *--------------------------------------------------------------*/ | |
1580 | ||
1581 | /* | |
1582 | * This is called only once for the whole dm_bufio module. | |
1583 | * It initializes memory limit. | |
1584 | */ | |
1585 | static int __init dm_bufio_init(void) | |
1586 | { | |
1587 | __u64 mem; | |
1588 | ||
1589 | memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches); | |
1590 | memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names); | |
1591 | ||
1592 | mem = (__u64)((totalram_pages - totalhigh_pages) * | |
1593 | DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT; | |
1594 | ||
1595 | if (mem > ULONG_MAX) | |
1596 | mem = ULONG_MAX; | |
1597 | ||
1598 | #ifdef CONFIG_MMU | |
1599 | /* | |
1600 | * Get the size of vmalloc space the same way as VMALLOC_TOTAL | |
1601 | * in fs/proc/internal.h | |
1602 | */ | |
1603 | if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100) | |
1604 | mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100; | |
1605 | #endif | |
1606 | ||
1607 | dm_bufio_default_cache_size = mem; | |
1608 | ||
1609 | mutex_lock(&dm_bufio_clients_lock); | |
1610 | __cache_size_refresh(); | |
1611 | mutex_unlock(&dm_bufio_clients_lock); | |
1612 | ||
1613 | dm_bufio_wq = create_singlethread_workqueue("dm_bufio_cache"); | |
1614 | if (!dm_bufio_wq) | |
1615 | return -ENOMEM; | |
1616 | ||
1617 | INIT_DELAYED_WORK(&dm_bufio_work, work_fn); | |
1618 | queue_delayed_work(dm_bufio_wq, &dm_bufio_work, | |
1619 | DM_BUFIO_WORK_TIMER_SECS * HZ); | |
1620 | ||
1621 | return 0; | |
1622 | } | |
1623 | ||
1624 | /* | |
1625 | * This is called once when unloading the dm_bufio module. | |
1626 | */ | |
1627 | static void __exit dm_bufio_exit(void) | |
1628 | { | |
1629 | int bug = 0; | |
1630 | int i; | |
1631 | ||
1632 | cancel_delayed_work_sync(&dm_bufio_work); | |
1633 | destroy_workqueue(dm_bufio_wq); | |
1634 | ||
1635 | for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) { | |
1636 | struct kmem_cache *kc = dm_bufio_caches[i]; | |
1637 | ||
1638 | if (kc) | |
1639 | kmem_cache_destroy(kc); | |
1640 | } | |
1641 | ||
1642 | for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++) | |
1643 | kfree(dm_bufio_cache_names[i]); | |
1644 | ||
1645 | if (dm_bufio_client_count) { | |
1646 | DMCRIT("%s: dm_bufio_client_count leaked: %d", | |
1647 | __func__, dm_bufio_client_count); | |
1648 | bug = 1; | |
1649 | } | |
1650 | ||
1651 | if (dm_bufio_current_allocated) { | |
1652 | DMCRIT("%s: dm_bufio_current_allocated leaked: %lu", | |
1653 | __func__, dm_bufio_current_allocated); | |
1654 | bug = 1; | |
1655 | } | |
1656 | ||
1657 | if (dm_bufio_allocated_get_free_pages) { | |
1658 | DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu", | |
1659 | __func__, dm_bufio_allocated_get_free_pages); | |
1660 | bug = 1; | |
1661 | } | |
1662 | ||
1663 | if (dm_bufio_allocated_vmalloc) { | |
1664 | DMCRIT("%s: dm_bufio_vmalloc leaked: %lu", | |
1665 | __func__, dm_bufio_allocated_vmalloc); | |
1666 | bug = 1; | |
1667 | } | |
1668 | ||
1669 | if (bug) | |
1670 | BUG(); | |
1671 | } | |
1672 | ||
1673 | module_init(dm_bufio_init) | |
1674 | module_exit(dm_bufio_exit) | |
1675 | ||
1676 | module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR); | |
1677 | MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); | |
1678 | ||
1679 | module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR); | |
1680 | MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds"); | |
1681 | ||
1682 | module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR); | |
1683 | MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory"); | |
1684 | ||
1685 | module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO); | |
1686 | MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc"); | |
1687 | ||
1688 | module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO); | |
1689 | MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages"); | |
1690 | ||
1691 | module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO); | |
1692 | MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc"); | |
1693 | ||
1694 | module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO); | |
1695 | MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache"); | |
1696 | ||
1697 | MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>"); | |
1698 | MODULE_DESCRIPTION(DM_NAME " buffered I/O library"); | |
1699 | MODULE_LICENSE("GPL"); |