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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 <linux/dm-bufio.h> | |
10 | ||
11 | #include <linux/device-mapper.h> | |
12 | #include <linux/dm-io.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/sched/mm.h> | |
15 | #include <linux/jiffies.h> | |
16 | #include <linux/vmalloc.h> | |
17 | #include <linux/shrinker.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/rbtree.h> | |
20 | #include <linux/stacktrace.h> | |
21 | ||
22 | #define DM_MSG_PREFIX "bufio" | |
23 | ||
24 | /* | |
25 | * Memory management policy: | |
26 | * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory | |
27 | * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower). | |
28 | * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers. | |
29 | * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT | |
30 | * dirty buffers. | |
31 | */ | |
32 | #define DM_BUFIO_MIN_BUFFERS 8 | |
33 | ||
34 | #define DM_BUFIO_MEMORY_PERCENT 2 | |
35 | #define DM_BUFIO_VMALLOC_PERCENT 25 | |
36 | #define DM_BUFIO_WRITEBACK_PERCENT 75 | |
37 | ||
38 | /* | |
39 | * Check buffer ages in this interval (seconds) | |
40 | */ | |
41 | #define DM_BUFIO_WORK_TIMER_SECS 30 | |
42 | ||
43 | /* | |
44 | * Free buffers when they are older than this (seconds) | |
45 | */ | |
46 | #define DM_BUFIO_DEFAULT_AGE_SECS 300 | |
47 | ||
48 | /* | |
49 | * The nr of bytes of cached data to keep around. | |
50 | */ | |
51 | #define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024) | |
52 | ||
53 | /* | |
54 | * Align buffer writes to this boundary. | |
55 | * Tests show that SSDs have the highest IOPS when using 4k writes. | |
56 | */ | |
57 | #define DM_BUFIO_WRITE_ALIGN 4096 | |
58 | ||
59 | /* | |
60 | * dm_buffer->list_mode | |
61 | */ | |
62 | #define LIST_CLEAN 0 | |
63 | #define LIST_DIRTY 1 | |
64 | #define LIST_SIZE 2 | |
65 | ||
66 | /* | |
67 | * Linking of buffers: | |
68 | * All buffers are linked to cache_hash with their hash_list field. | |
69 | * | |
70 | * Clean buffers that are not being written (B_WRITING not set) | |
71 | * are linked to lru[LIST_CLEAN] with their lru_list field. | |
72 | * | |
73 | * Dirty and clean buffers that are being written are linked to | |
74 | * lru[LIST_DIRTY] with their lru_list field. When the write | |
75 | * finishes, the buffer cannot be relinked immediately (because we | |
76 | * are in an interrupt context and relinking requires process | |
77 | * context), so some clean-not-writing buffers can be held on | |
78 | * dirty_lru too. They are later added to lru in the process | |
79 | * context. | |
80 | */ | |
81 | struct dm_bufio_client { | |
82 | struct mutex lock; | |
83 | ||
84 | struct list_head lru[LIST_SIZE]; | |
85 | unsigned long n_buffers[LIST_SIZE]; | |
86 | ||
87 | struct block_device *bdev; | |
88 | unsigned block_size; | |
89 | s8 sectors_per_block_bits; | |
90 | void (*alloc_callback)(struct dm_buffer *); | |
91 | void (*write_callback)(struct dm_buffer *); | |
92 | ||
93 | struct kmem_cache *slab_buffer; | |
94 | struct kmem_cache *slab_cache; | |
95 | struct dm_io_client *dm_io; | |
96 | ||
97 | struct list_head reserved_buffers; | |
98 | unsigned need_reserved_buffers; | |
99 | ||
100 | unsigned minimum_buffers; | |
101 | ||
102 | struct rb_root buffer_tree; | |
103 | wait_queue_head_t free_buffer_wait; | |
104 | ||
105 | sector_t start; | |
106 | ||
107 | int async_write_error; | |
108 | ||
109 | struct list_head client_list; | |
110 | struct shrinker shrinker; | |
111 | }; | |
112 | ||
113 | /* | |
114 | * Buffer state bits. | |
115 | */ | |
116 | #define B_READING 0 | |
117 | #define B_WRITING 1 | |
118 | #define B_DIRTY 2 | |
119 | ||
120 | /* | |
121 | * Describes how the block was allocated: | |
122 | * kmem_cache_alloc(), __get_free_pages() or vmalloc(). | |
123 | * See the comment at alloc_buffer_data. | |
124 | */ | |
125 | enum data_mode { | |
126 | DATA_MODE_SLAB = 0, | |
127 | DATA_MODE_GET_FREE_PAGES = 1, | |
128 | DATA_MODE_VMALLOC = 2, | |
129 | DATA_MODE_LIMIT = 3 | |
130 | }; | |
131 | ||
132 | struct dm_buffer { | |
133 | struct rb_node node; | |
134 | struct list_head lru_list; | |
135 | sector_t block; | |
136 | void *data; | |
137 | unsigned char data_mode; /* DATA_MODE_* */ | |
138 | unsigned char list_mode; /* LIST_* */ | |
139 | blk_status_t read_error; | |
140 | blk_status_t write_error; | |
141 | unsigned hold_count; | |
142 | unsigned long state; | |
143 | unsigned long last_accessed; | |
144 | unsigned dirty_start; | |
145 | unsigned dirty_end; | |
146 | unsigned write_start; | |
147 | unsigned write_end; | |
148 | struct dm_bufio_client *c; | |
149 | struct list_head write_list; | |
150 | void (*end_io)(struct dm_buffer *, blk_status_t); | |
151 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
152 | #define MAX_STACK 10 | |
153 | struct stack_trace stack_trace; | |
154 | unsigned long stack_entries[MAX_STACK]; | |
155 | #endif | |
156 | }; | |
157 | ||
158 | /*----------------------------------------------------------------*/ | |
159 | ||
160 | #define dm_bufio_in_request() (!!current->bio_list) | |
161 | ||
162 | static void dm_bufio_lock(struct dm_bufio_client *c) | |
163 | { | |
164 | mutex_lock_nested(&c->lock, dm_bufio_in_request()); | |
165 | } | |
166 | ||
167 | static int dm_bufio_trylock(struct dm_bufio_client *c) | |
168 | { | |
169 | return mutex_trylock(&c->lock); | |
170 | } | |
171 | ||
172 | static void dm_bufio_unlock(struct dm_bufio_client *c) | |
173 | { | |
174 | mutex_unlock(&c->lock); | |
175 | } | |
176 | ||
177 | /*----------------------------------------------------------------*/ | |
178 | ||
179 | /* | |
180 | * Default cache size: available memory divided by the ratio. | |
181 | */ | |
182 | static unsigned long dm_bufio_default_cache_size; | |
183 | ||
184 | /* | |
185 | * Total cache size set by the user. | |
186 | */ | |
187 | static unsigned long dm_bufio_cache_size; | |
188 | ||
189 | /* | |
190 | * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change | |
191 | * at any time. If it disagrees, the user has changed cache size. | |
192 | */ | |
193 | static unsigned long dm_bufio_cache_size_latch; | |
194 | ||
195 | static DEFINE_SPINLOCK(param_spinlock); | |
196 | ||
197 | /* | |
198 | * Buffers are freed after this timeout | |
199 | */ | |
200 | static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS; | |
201 | static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES; | |
202 | ||
203 | static unsigned long dm_bufio_peak_allocated; | |
204 | static unsigned long dm_bufio_allocated_kmem_cache; | |
205 | static unsigned long dm_bufio_allocated_get_free_pages; | |
206 | static unsigned long dm_bufio_allocated_vmalloc; | |
207 | static unsigned long dm_bufio_current_allocated; | |
208 | ||
209 | /*----------------------------------------------------------------*/ | |
210 | ||
211 | /* | |
212 | * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count | |
213 | */ | |
214 | static unsigned long dm_bufio_cache_size_per_client; | |
215 | ||
216 | /* | |
217 | * The current number of clients. | |
218 | */ | |
219 | static int dm_bufio_client_count; | |
220 | ||
221 | /* | |
222 | * The list of all clients. | |
223 | */ | |
224 | static LIST_HEAD(dm_bufio_all_clients); | |
225 | ||
226 | /* | |
227 | * This mutex protects dm_bufio_cache_size_latch, | |
228 | * dm_bufio_cache_size_per_client and dm_bufio_client_count | |
229 | */ | |
230 | static DEFINE_MUTEX(dm_bufio_clients_lock); | |
231 | ||
232 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
233 | static void buffer_record_stack(struct dm_buffer *b) | |
234 | { | |
235 | b->stack_trace.nr_entries = 0; | |
236 | b->stack_trace.max_entries = MAX_STACK; | |
237 | b->stack_trace.entries = b->stack_entries; | |
238 | b->stack_trace.skip = 2; | |
239 | save_stack_trace(&b->stack_trace); | |
240 | } | |
241 | #endif | |
242 | ||
243 | /*---------------------------------------------------------------- | |
244 | * A red/black tree acts as an index for all the buffers. | |
245 | *--------------------------------------------------------------*/ | |
246 | static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) | |
247 | { | |
248 | struct rb_node *n = c->buffer_tree.rb_node; | |
249 | struct dm_buffer *b; | |
250 | ||
251 | while (n) { | |
252 | b = container_of(n, struct dm_buffer, node); | |
253 | ||
254 | if (b->block == block) | |
255 | return b; | |
256 | ||
257 | n = (b->block < block) ? n->rb_left : n->rb_right; | |
258 | } | |
259 | ||
260 | return NULL; | |
261 | } | |
262 | ||
263 | static void __insert(struct dm_bufio_client *c, struct dm_buffer *b) | |
264 | { | |
265 | struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL; | |
266 | struct dm_buffer *found; | |
267 | ||
268 | while (*new) { | |
269 | found = container_of(*new, struct dm_buffer, node); | |
270 | ||
271 | if (found->block == b->block) { | |
272 | BUG_ON(found != b); | |
273 | return; | |
274 | } | |
275 | ||
276 | parent = *new; | |
277 | new = (found->block < b->block) ? | |
278 | &((*new)->rb_left) : &((*new)->rb_right); | |
279 | } | |
280 | ||
281 | rb_link_node(&b->node, parent, new); | |
282 | rb_insert_color(&b->node, &c->buffer_tree); | |
283 | } | |
284 | ||
285 | static void __remove(struct dm_bufio_client *c, struct dm_buffer *b) | |
286 | { | |
287 | rb_erase(&b->node, &c->buffer_tree); | |
288 | } | |
289 | ||
290 | /*----------------------------------------------------------------*/ | |
291 | ||
292 | static void adjust_total_allocated(unsigned char data_mode, long diff) | |
293 | { | |
294 | static unsigned long * const class_ptr[DATA_MODE_LIMIT] = { | |
295 | &dm_bufio_allocated_kmem_cache, | |
296 | &dm_bufio_allocated_get_free_pages, | |
297 | &dm_bufio_allocated_vmalloc, | |
298 | }; | |
299 | ||
300 | spin_lock(¶m_spinlock); | |
301 | ||
302 | *class_ptr[data_mode] += diff; | |
303 | ||
304 | dm_bufio_current_allocated += diff; | |
305 | ||
306 | if (dm_bufio_current_allocated > dm_bufio_peak_allocated) | |
307 | dm_bufio_peak_allocated = dm_bufio_current_allocated; | |
308 | ||
309 | spin_unlock(¶m_spinlock); | |
310 | } | |
311 | ||
312 | /* | |
313 | * Change the number of clients and recalculate per-client limit. | |
314 | */ | |
315 | static void __cache_size_refresh(void) | |
316 | { | |
317 | BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock)); | |
318 | BUG_ON(dm_bufio_client_count < 0); | |
319 | ||
320 | dm_bufio_cache_size_latch = READ_ONCE(dm_bufio_cache_size); | |
321 | ||
322 | /* | |
323 | * Use default if set to 0 and report the actual cache size used. | |
324 | */ | |
325 | if (!dm_bufio_cache_size_latch) { | |
326 | (void)cmpxchg(&dm_bufio_cache_size, 0, | |
327 | dm_bufio_default_cache_size); | |
328 | dm_bufio_cache_size_latch = dm_bufio_default_cache_size; | |
329 | } | |
330 | ||
331 | dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch / | |
332 | (dm_bufio_client_count ? : 1); | |
333 | } | |
334 | ||
335 | /* | |
336 | * Allocating buffer data. | |
337 | * | |
338 | * Small buffers are allocated with kmem_cache, to use space optimally. | |
339 | * | |
340 | * For large buffers, we choose between get_free_pages and vmalloc. | |
341 | * Each has advantages and disadvantages. | |
342 | * | |
343 | * __get_free_pages can randomly fail if the memory is fragmented. | |
344 | * __vmalloc won't randomly fail, but vmalloc space is limited (it may be | |
345 | * as low as 128M) so using it for caching is not appropriate. | |
346 | * | |
347 | * If the allocation may fail we use __get_free_pages. Memory fragmentation | |
348 | * won't have a fatal effect here, but it just causes flushes of some other | |
349 | * buffers and more I/O will be performed. Don't use __get_free_pages if it | |
350 | * always fails (i.e. order >= MAX_ORDER). | |
351 | * | |
352 | * If the allocation shouldn't fail we use __vmalloc. This is only for the | |
353 | * initial reserve allocation, so there's no risk of wasting all vmalloc | |
354 | * space. | |
355 | */ | |
356 | static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, | |
357 | unsigned char *data_mode) | |
358 | { | |
359 | if (unlikely(c->slab_cache != NULL)) { | |
360 | *data_mode = DATA_MODE_SLAB; | |
361 | return kmem_cache_alloc(c->slab_cache, gfp_mask); | |
362 | } | |
363 | ||
364 | if (c->block_size <= KMALLOC_MAX_SIZE && | |
365 | gfp_mask & __GFP_NORETRY) { | |
366 | *data_mode = DATA_MODE_GET_FREE_PAGES; | |
367 | return (void *)__get_free_pages(gfp_mask, | |
368 | c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT)); | |
369 | } | |
370 | ||
371 | *data_mode = DATA_MODE_VMALLOC; | |
372 | ||
373 | /* | |
374 | * __vmalloc allocates the data pages and auxiliary structures with | |
375 | * gfp_flags that were specified, but pagetables are always allocated | |
376 | * with GFP_KERNEL, no matter what was specified as gfp_mask. | |
377 | * | |
378 | * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that | |
379 | * all allocations done by this process (including pagetables) are done | |
380 | * as if GFP_NOIO was specified. | |
381 | */ | |
382 | if (gfp_mask & __GFP_NORETRY) { | |
383 | unsigned noio_flag = memalloc_noio_save(); | |
384 | void *ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); | |
385 | ||
386 | memalloc_noio_restore(noio_flag); | |
387 | return ptr; | |
388 | } | |
389 | ||
390 | return __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); | |
391 | } | |
392 | ||
393 | /* | |
394 | * Free buffer's data. | |
395 | */ | |
396 | static void free_buffer_data(struct dm_bufio_client *c, | |
397 | void *data, unsigned char data_mode) | |
398 | { | |
399 | switch (data_mode) { | |
400 | case DATA_MODE_SLAB: | |
401 | kmem_cache_free(c->slab_cache, data); | |
402 | break; | |
403 | ||
404 | case DATA_MODE_GET_FREE_PAGES: | |
405 | free_pages((unsigned long)data, | |
406 | c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT)); | |
407 | break; | |
408 | ||
409 | case DATA_MODE_VMALLOC: | |
410 | vfree(data); | |
411 | break; | |
412 | ||
413 | default: | |
414 | DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d", | |
415 | data_mode); | |
416 | BUG(); | |
417 | } | |
418 | } | |
419 | ||
420 | /* | |
421 | * Allocate buffer and its data. | |
422 | */ | |
423 | static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) | |
424 | { | |
425 | struct dm_buffer *b = kmem_cache_alloc(c->slab_buffer, gfp_mask); | |
426 | ||
427 | if (!b) | |
428 | return NULL; | |
429 | ||
430 | b->c = c; | |
431 | ||
432 | b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); | |
433 | if (!b->data) { | |
434 | kmem_cache_free(c->slab_buffer, b); | |
435 | return NULL; | |
436 | } | |
437 | ||
438 | adjust_total_allocated(b->data_mode, (long)c->block_size); | |
439 | ||
440 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
441 | memset(&b->stack_trace, 0, sizeof(b->stack_trace)); | |
442 | #endif | |
443 | return b; | |
444 | } | |
445 | ||
446 | /* | |
447 | * Free buffer and its data. | |
448 | */ | |
449 | static void free_buffer(struct dm_buffer *b) | |
450 | { | |
451 | struct dm_bufio_client *c = b->c; | |
452 | ||
453 | adjust_total_allocated(b->data_mode, -(long)c->block_size); | |
454 | ||
455 | free_buffer_data(c, b->data, b->data_mode); | |
456 | kmem_cache_free(c->slab_buffer, b); | |
457 | } | |
458 | ||
459 | /* | |
460 | * Link buffer to the hash list and clean or dirty queue. | |
461 | */ | |
462 | static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty) | |
463 | { | |
464 | struct dm_bufio_client *c = b->c; | |
465 | ||
466 | c->n_buffers[dirty]++; | |
467 | b->block = block; | |
468 | b->list_mode = dirty; | |
469 | list_add(&b->lru_list, &c->lru[dirty]); | |
470 | __insert(b->c, b); | |
471 | b->last_accessed = jiffies; | |
472 | } | |
473 | ||
474 | /* | |
475 | * Unlink buffer from the hash list and dirty or clean queue. | |
476 | */ | |
477 | static void __unlink_buffer(struct dm_buffer *b) | |
478 | { | |
479 | struct dm_bufio_client *c = b->c; | |
480 | ||
481 | BUG_ON(!c->n_buffers[b->list_mode]); | |
482 | ||
483 | c->n_buffers[b->list_mode]--; | |
484 | __remove(b->c, b); | |
485 | list_del(&b->lru_list); | |
486 | } | |
487 | ||
488 | /* | |
489 | * Place the buffer to the head of dirty or clean LRU queue. | |
490 | */ | |
491 | static void __relink_lru(struct dm_buffer *b, int dirty) | |
492 | { | |
493 | struct dm_bufio_client *c = b->c; | |
494 | ||
495 | BUG_ON(!c->n_buffers[b->list_mode]); | |
496 | ||
497 | c->n_buffers[b->list_mode]--; | |
498 | c->n_buffers[dirty]++; | |
499 | b->list_mode = dirty; | |
500 | list_move(&b->lru_list, &c->lru[dirty]); | |
501 | b->last_accessed = jiffies; | |
502 | } | |
503 | ||
504 | /*---------------------------------------------------------------- | |
505 | * Submit I/O on the buffer. | |
506 | * | |
507 | * Bio interface is faster but it has some problems: | |
508 | * the vector list is limited (increasing this limit increases | |
509 | * memory-consumption per buffer, so it is not viable); | |
510 | * | |
511 | * the memory must be direct-mapped, not vmalloced; | |
512 | * | |
513 | * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and | |
514 | * it is not vmalloced, try using the bio interface. | |
515 | * | |
516 | * If the buffer is big, if it is vmalloced or if the underlying device | |
517 | * rejects the bio because it is too large, use dm-io layer to do the I/O. | |
518 | * The dm-io layer splits the I/O into multiple requests, avoiding the above | |
519 | * shortcomings. | |
520 | *--------------------------------------------------------------*/ | |
521 | ||
522 | /* | |
523 | * dm-io completion routine. It just calls b->bio.bi_end_io, pretending | |
524 | * that the request was handled directly with bio interface. | |
525 | */ | |
526 | static void dmio_complete(unsigned long error, void *context) | |
527 | { | |
528 | struct dm_buffer *b = context; | |
529 | ||
530 | b->end_io(b, unlikely(error != 0) ? BLK_STS_IOERR : 0); | |
531 | } | |
532 | ||
533 | static void use_dmio(struct dm_buffer *b, int rw, sector_t sector, | |
534 | unsigned n_sectors, unsigned offset) | |
535 | { | |
536 | int r; | |
537 | struct dm_io_request io_req = { | |
538 | .bi_op = rw, | |
539 | .bi_op_flags = 0, | |
540 | .notify.fn = dmio_complete, | |
541 | .notify.context = b, | |
542 | .client = b->c->dm_io, | |
543 | }; | |
544 | struct dm_io_region region = { | |
545 | .bdev = b->c->bdev, | |
546 | .sector = sector, | |
547 | .count = n_sectors, | |
548 | }; | |
549 | ||
550 | if (b->data_mode != DATA_MODE_VMALLOC) { | |
551 | io_req.mem.type = DM_IO_KMEM; | |
552 | io_req.mem.ptr.addr = (char *)b->data + offset; | |
553 | } else { | |
554 | io_req.mem.type = DM_IO_VMA; | |
555 | io_req.mem.ptr.vma = (char *)b->data + offset; | |
556 | } | |
557 | ||
558 | r = dm_io(&io_req, 1, ®ion, NULL); | |
559 | if (unlikely(r)) | |
560 | b->end_io(b, errno_to_blk_status(r)); | |
561 | } | |
562 | ||
563 | static void bio_complete(struct bio *bio) | |
564 | { | |
565 | struct dm_buffer *b = bio->bi_private; | |
566 | blk_status_t status = bio->bi_status; | |
567 | bio_put(bio); | |
568 | b->end_io(b, status); | |
569 | } | |
570 | ||
571 | static void use_bio(struct dm_buffer *b, int rw, sector_t sector, | |
572 | unsigned n_sectors, unsigned offset) | |
573 | { | |
574 | struct bio *bio; | |
575 | char *ptr; | |
576 | unsigned vec_size, len; | |
577 | ||
578 | vec_size = b->c->block_size >> PAGE_SHIFT; | |
579 | if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT)) | |
580 | vec_size += 2; | |
581 | ||
582 | bio = bio_kmalloc(GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN, vec_size); | |
583 | if (!bio) { | |
584 | dmio: | |
585 | use_dmio(b, rw, sector, n_sectors, offset); | |
586 | return; | |
587 | } | |
588 | ||
589 | bio->bi_iter.bi_sector = sector; | |
590 | bio_set_dev(bio, b->c->bdev); | |
591 | bio_set_op_attrs(bio, rw, 0); | |
592 | bio->bi_end_io = bio_complete; | |
593 | bio->bi_private = b; | |
594 | ||
595 | ptr = (char *)b->data + offset; | |
596 | len = n_sectors << SECTOR_SHIFT; | |
597 | ||
598 | do { | |
599 | unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len); | |
600 | if (!bio_add_page(bio, virt_to_page(ptr), this_step, | |
601 | offset_in_page(ptr))) { | |
602 | bio_put(bio); | |
603 | goto dmio; | |
604 | } | |
605 | ||
606 | len -= this_step; | |
607 | ptr += this_step; | |
608 | } while (len > 0); | |
609 | ||
610 | submit_bio(bio); | |
611 | } | |
612 | ||
613 | static void submit_io(struct dm_buffer *b, int rw, void (*end_io)(struct dm_buffer *, blk_status_t)) | |
614 | { | |
615 | unsigned n_sectors; | |
616 | sector_t sector; | |
617 | unsigned offset, end; | |
618 | ||
619 | b->end_io = end_io; | |
620 | ||
621 | if (likely(b->c->sectors_per_block_bits >= 0)) | |
622 | sector = b->block << b->c->sectors_per_block_bits; | |
623 | else | |
624 | sector = b->block * (b->c->block_size >> SECTOR_SHIFT); | |
625 | sector += b->c->start; | |
626 | ||
627 | if (rw != REQ_OP_WRITE) { | |
628 | n_sectors = b->c->block_size >> SECTOR_SHIFT; | |
629 | offset = 0; | |
630 | } else { | |
631 | if (b->c->write_callback) | |
632 | b->c->write_callback(b); | |
633 | offset = b->write_start; | |
634 | end = b->write_end; | |
635 | offset &= -DM_BUFIO_WRITE_ALIGN; | |
636 | end += DM_BUFIO_WRITE_ALIGN - 1; | |
637 | end &= -DM_BUFIO_WRITE_ALIGN; | |
638 | if (unlikely(end > b->c->block_size)) | |
639 | end = b->c->block_size; | |
640 | ||
641 | sector += offset >> SECTOR_SHIFT; | |
642 | n_sectors = (end - offset) >> SECTOR_SHIFT; | |
643 | } | |
644 | ||
645 | if (b->data_mode != DATA_MODE_VMALLOC) | |
646 | use_bio(b, rw, sector, n_sectors, offset); | |
647 | else | |
648 | use_dmio(b, rw, sector, n_sectors, offset); | |
649 | } | |
650 | ||
651 | /*---------------------------------------------------------------- | |
652 | * Writing dirty buffers | |
653 | *--------------------------------------------------------------*/ | |
654 | ||
655 | /* | |
656 | * The endio routine for write. | |
657 | * | |
658 | * Set the error, clear B_WRITING bit and wake anyone who was waiting on | |
659 | * it. | |
660 | */ | |
661 | static void write_endio(struct dm_buffer *b, blk_status_t status) | |
662 | { | |
663 | b->write_error = status; | |
664 | if (unlikely(status)) { | |
665 | struct dm_bufio_client *c = b->c; | |
666 | ||
667 | (void)cmpxchg(&c->async_write_error, 0, | |
668 | blk_status_to_errno(status)); | |
669 | } | |
670 | ||
671 | BUG_ON(!test_bit(B_WRITING, &b->state)); | |
672 | ||
673 | smp_mb__before_atomic(); | |
674 | clear_bit(B_WRITING, &b->state); | |
675 | smp_mb__after_atomic(); | |
676 | ||
677 | wake_up_bit(&b->state, B_WRITING); | |
678 | } | |
679 | ||
680 | /* | |
681 | * Initiate a write on a dirty buffer, but don't wait for it. | |
682 | * | |
683 | * - If the buffer is not dirty, exit. | |
684 | * - If there some previous write going on, wait for it to finish (we can't | |
685 | * have two writes on the same buffer simultaneously). | |
686 | * - Submit our write and don't wait on it. We set B_WRITING indicating | |
687 | * that there is a write in progress. | |
688 | */ | |
689 | static void __write_dirty_buffer(struct dm_buffer *b, | |
690 | struct list_head *write_list) | |
691 | { | |
692 | if (!test_bit(B_DIRTY, &b->state)) | |
693 | return; | |
694 | ||
695 | clear_bit(B_DIRTY, &b->state); | |
696 | wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); | |
697 | ||
698 | b->write_start = b->dirty_start; | |
699 | b->write_end = b->dirty_end; | |
700 | ||
701 | if (!write_list) | |
702 | submit_io(b, REQ_OP_WRITE, write_endio); | |
703 | else | |
704 | list_add_tail(&b->write_list, write_list); | |
705 | } | |
706 | ||
707 | static void __flush_write_list(struct list_head *write_list) | |
708 | { | |
709 | struct blk_plug plug; | |
710 | blk_start_plug(&plug); | |
711 | while (!list_empty(write_list)) { | |
712 | struct dm_buffer *b = | |
713 | list_entry(write_list->next, struct dm_buffer, write_list); | |
714 | list_del(&b->write_list); | |
715 | submit_io(b, REQ_OP_WRITE, write_endio); | |
716 | cond_resched(); | |
717 | } | |
718 | blk_finish_plug(&plug); | |
719 | } | |
720 | ||
721 | /* | |
722 | * Wait until any activity on the buffer finishes. Possibly write the | |
723 | * buffer if it is dirty. When this function finishes, there is no I/O | |
724 | * running on the buffer and the buffer is not dirty. | |
725 | */ | |
726 | static void __make_buffer_clean(struct dm_buffer *b) | |
727 | { | |
728 | BUG_ON(b->hold_count); | |
729 | ||
730 | if (!b->state) /* fast case */ | |
731 | return; | |
732 | ||
733 | wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); | |
734 | __write_dirty_buffer(b, NULL); | |
735 | wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); | |
736 | } | |
737 | ||
738 | /* | |
739 | * Find some buffer that is not held by anybody, clean it, unlink it and | |
740 | * return it. | |
741 | */ | |
742 | static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) | |
743 | { | |
744 | struct dm_buffer *b; | |
745 | ||
746 | list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) { | |
747 | BUG_ON(test_bit(B_WRITING, &b->state)); | |
748 | BUG_ON(test_bit(B_DIRTY, &b->state)); | |
749 | ||
750 | if (!b->hold_count) { | |
751 | __make_buffer_clean(b); | |
752 | __unlink_buffer(b); | |
753 | return b; | |
754 | } | |
755 | cond_resched(); | |
756 | } | |
757 | ||
758 | list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { | |
759 | BUG_ON(test_bit(B_READING, &b->state)); | |
760 | ||
761 | if (!b->hold_count) { | |
762 | __make_buffer_clean(b); | |
763 | __unlink_buffer(b); | |
764 | return b; | |
765 | } | |
766 | cond_resched(); | |
767 | } | |
768 | ||
769 | return NULL; | |
770 | } | |
771 | ||
772 | /* | |
773 | * Wait until some other threads free some buffer or release hold count on | |
774 | * some buffer. | |
775 | * | |
776 | * This function is entered with c->lock held, drops it and regains it | |
777 | * before exiting. | |
778 | */ | |
779 | static void __wait_for_free_buffer(struct dm_bufio_client *c) | |
780 | { | |
781 | DECLARE_WAITQUEUE(wait, current); | |
782 | ||
783 | add_wait_queue(&c->free_buffer_wait, &wait); | |
784 | set_current_state(TASK_UNINTERRUPTIBLE); | |
785 | dm_bufio_unlock(c); | |
786 | ||
787 | io_schedule(); | |
788 | ||
789 | remove_wait_queue(&c->free_buffer_wait, &wait); | |
790 | ||
791 | dm_bufio_lock(c); | |
792 | } | |
793 | ||
794 | enum new_flag { | |
795 | NF_FRESH = 0, | |
796 | NF_READ = 1, | |
797 | NF_GET = 2, | |
798 | NF_PREFETCH = 3 | |
799 | }; | |
800 | ||
801 | /* | |
802 | * Allocate a new buffer. If the allocation is not possible, wait until | |
803 | * some other thread frees a buffer. | |
804 | * | |
805 | * May drop the lock and regain it. | |
806 | */ | |
807 | static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) | |
808 | { | |
809 | struct dm_buffer *b; | |
810 | bool tried_noio_alloc = false; | |
811 | ||
812 | /* | |
813 | * dm-bufio is resistant to allocation failures (it just keeps | |
814 | * one buffer reserved in cases all the allocations fail). | |
815 | * So set flags to not try too hard: | |
816 | * GFP_NOWAIT: don't wait; if we need to sleep we'll release our | |
817 | * mutex and wait ourselves. | |
818 | * __GFP_NORETRY: don't retry and rather return failure | |
819 | * __GFP_NOMEMALLOC: don't use emergency reserves | |
820 | * __GFP_NOWARN: don't print a warning in case of failure | |
821 | * | |
822 | * For debugging, if we set the cache size to 1, no new buffers will | |
823 | * be allocated. | |
824 | */ | |
825 | while (1) { | |
826 | if (dm_bufio_cache_size_latch != 1) { | |
827 | b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
828 | if (b) | |
829 | return b; | |
830 | } | |
831 | ||
832 | if (nf == NF_PREFETCH) | |
833 | return NULL; | |
834 | ||
835 | if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { | |
836 | dm_bufio_unlock(c); | |
837 | b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
838 | dm_bufio_lock(c); | |
839 | if (b) | |
840 | return b; | |
841 | tried_noio_alloc = true; | |
842 | } | |
843 | ||
844 | if (!list_empty(&c->reserved_buffers)) { | |
845 | b = list_entry(c->reserved_buffers.next, | |
846 | struct dm_buffer, lru_list); | |
847 | list_del(&b->lru_list); | |
848 | c->need_reserved_buffers++; | |
849 | ||
850 | return b; | |
851 | } | |
852 | ||
853 | b = __get_unclaimed_buffer(c); | |
854 | if (b) | |
855 | return b; | |
856 | ||
857 | __wait_for_free_buffer(c); | |
858 | } | |
859 | } | |
860 | ||
861 | static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf) | |
862 | { | |
863 | struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf); | |
864 | ||
865 | if (!b) | |
866 | return NULL; | |
867 | ||
868 | if (c->alloc_callback) | |
869 | c->alloc_callback(b); | |
870 | ||
871 | return b; | |
872 | } | |
873 | ||
874 | /* | |
875 | * Free a buffer and wake other threads waiting for free buffers. | |
876 | */ | |
877 | static void __free_buffer_wake(struct dm_buffer *b) | |
878 | { | |
879 | struct dm_bufio_client *c = b->c; | |
880 | ||
881 | if (!c->need_reserved_buffers) | |
882 | free_buffer(b); | |
883 | else { | |
884 | list_add(&b->lru_list, &c->reserved_buffers); | |
885 | c->need_reserved_buffers--; | |
886 | } | |
887 | ||
888 | wake_up(&c->free_buffer_wait); | |
889 | } | |
890 | ||
891 | static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, | |
892 | struct list_head *write_list) | |
893 | { | |
894 | struct dm_buffer *b, *tmp; | |
895 | ||
896 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { | |
897 | BUG_ON(test_bit(B_READING, &b->state)); | |
898 | ||
899 | if (!test_bit(B_DIRTY, &b->state) && | |
900 | !test_bit(B_WRITING, &b->state)) { | |
901 | __relink_lru(b, LIST_CLEAN); | |
902 | continue; | |
903 | } | |
904 | ||
905 | if (no_wait && test_bit(B_WRITING, &b->state)) | |
906 | return; | |
907 | ||
908 | __write_dirty_buffer(b, write_list); | |
909 | cond_resched(); | |
910 | } | |
911 | } | |
912 | ||
913 | /* | |
914 | * Get writeback threshold and buffer limit for a given client. | |
915 | */ | |
916 | static void __get_memory_limit(struct dm_bufio_client *c, | |
917 | unsigned long *threshold_buffers, | |
918 | unsigned long *limit_buffers) | |
919 | { | |
920 | unsigned long buffers; | |
921 | ||
922 | if (unlikely(READ_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch)) { | |
923 | if (mutex_trylock(&dm_bufio_clients_lock)) { | |
924 | __cache_size_refresh(); | |
925 | mutex_unlock(&dm_bufio_clients_lock); | |
926 | } | |
927 | } | |
928 | ||
929 | buffers = dm_bufio_cache_size_per_client; | |
930 | if (likely(c->sectors_per_block_bits >= 0)) | |
931 | buffers >>= c->sectors_per_block_bits + SECTOR_SHIFT; | |
932 | else | |
933 | buffers /= c->block_size; | |
934 | ||
935 | if (buffers < c->minimum_buffers) | |
936 | buffers = c->minimum_buffers; | |
937 | ||
938 | *limit_buffers = buffers; | |
939 | *threshold_buffers = mult_frac(buffers, | |
940 | DM_BUFIO_WRITEBACK_PERCENT, 100); | |
941 | } | |
942 | ||
943 | /* | |
944 | * Check if we're over watermark. | |
945 | * If we are over threshold_buffers, start freeing buffers. | |
946 | * If we're over "limit_buffers", block until we get under the limit. | |
947 | */ | |
948 | static void __check_watermark(struct dm_bufio_client *c, | |
949 | struct list_head *write_list) | |
950 | { | |
951 | unsigned long threshold_buffers, limit_buffers; | |
952 | ||
953 | __get_memory_limit(c, &threshold_buffers, &limit_buffers); | |
954 | ||
955 | while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] > | |
956 | limit_buffers) { | |
957 | ||
958 | struct dm_buffer *b = __get_unclaimed_buffer(c); | |
959 | ||
960 | if (!b) | |
961 | return; | |
962 | ||
963 | __free_buffer_wake(b); | |
964 | cond_resched(); | |
965 | } | |
966 | ||
967 | if (c->n_buffers[LIST_DIRTY] > threshold_buffers) | |
968 | __write_dirty_buffers_async(c, 1, write_list); | |
969 | } | |
970 | ||
971 | /*---------------------------------------------------------------- | |
972 | * Getting a buffer | |
973 | *--------------------------------------------------------------*/ | |
974 | ||
975 | static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, | |
976 | enum new_flag nf, int *need_submit, | |
977 | struct list_head *write_list) | |
978 | { | |
979 | struct dm_buffer *b, *new_b = NULL; | |
980 | ||
981 | *need_submit = 0; | |
982 | ||
983 | b = __find(c, block); | |
984 | if (b) | |
985 | goto found_buffer; | |
986 | ||
987 | if (nf == NF_GET) | |
988 | return NULL; | |
989 | ||
990 | new_b = __alloc_buffer_wait(c, nf); | |
991 | if (!new_b) | |
992 | return NULL; | |
993 | ||
994 | /* | |
995 | * We've had a period where the mutex was unlocked, so need to | |
996 | * recheck the hash table. | |
997 | */ | |
998 | b = __find(c, block); | |
999 | if (b) { | |
1000 | __free_buffer_wake(new_b); | |
1001 | goto found_buffer; | |
1002 | } | |
1003 | ||
1004 | __check_watermark(c, write_list); | |
1005 | ||
1006 | b = new_b; | |
1007 | b->hold_count = 1; | |
1008 | b->read_error = 0; | |
1009 | b->write_error = 0; | |
1010 | __link_buffer(b, block, LIST_CLEAN); | |
1011 | ||
1012 | if (nf == NF_FRESH) { | |
1013 | b->state = 0; | |
1014 | return b; | |
1015 | } | |
1016 | ||
1017 | b->state = 1 << B_READING; | |
1018 | *need_submit = 1; | |
1019 | ||
1020 | return b; | |
1021 | ||
1022 | found_buffer: | |
1023 | if (nf == NF_PREFETCH) | |
1024 | return NULL; | |
1025 | /* | |
1026 | * Note: it is essential that we don't wait for the buffer to be | |
1027 | * read if dm_bufio_get function is used. Both dm_bufio_get and | |
1028 | * dm_bufio_prefetch can be used in the driver request routine. | |
1029 | * If the user called both dm_bufio_prefetch and dm_bufio_get on | |
1030 | * the same buffer, it would deadlock if we waited. | |
1031 | */ | |
1032 | if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state))) | |
1033 | return NULL; | |
1034 | ||
1035 | b->hold_count++; | |
1036 | __relink_lru(b, test_bit(B_DIRTY, &b->state) || | |
1037 | test_bit(B_WRITING, &b->state)); | |
1038 | return b; | |
1039 | } | |
1040 | ||
1041 | /* | |
1042 | * The endio routine for reading: set the error, clear the bit and wake up | |
1043 | * anyone waiting on the buffer. | |
1044 | */ | |
1045 | static void read_endio(struct dm_buffer *b, blk_status_t status) | |
1046 | { | |
1047 | b->read_error = status; | |
1048 | ||
1049 | BUG_ON(!test_bit(B_READING, &b->state)); | |
1050 | ||
1051 | smp_mb__before_atomic(); | |
1052 | clear_bit(B_READING, &b->state); | |
1053 | smp_mb__after_atomic(); | |
1054 | ||
1055 | wake_up_bit(&b->state, B_READING); | |
1056 | } | |
1057 | ||
1058 | /* | |
1059 | * A common routine for dm_bufio_new and dm_bufio_read. Operation of these | |
1060 | * functions is similar except that dm_bufio_new doesn't read the | |
1061 | * buffer from the disk (assuming that the caller overwrites all the data | |
1062 | * and uses dm_bufio_mark_buffer_dirty to write new data back). | |
1063 | */ | |
1064 | static void *new_read(struct dm_bufio_client *c, sector_t block, | |
1065 | enum new_flag nf, struct dm_buffer **bp) | |
1066 | { | |
1067 | int need_submit; | |
1068 | struct dm_buffer *b; | |
1069 | ||
1070 | LIST_HEAD(write_list); | |
1071 | ||
1072 | dm_bufio_lock(c); | |
1073 | b = __bufio_new(c, block, nf, &need_submit, &write_list); | |
1074 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
1075 | if (b && b->hold_count == 1) | |
1076 | buffer_record_stack(b); | |
1077 | #endif | |
1078 | dm_bufio_unlock(c); | |
1079 | ||
1080 | __flush_write_list(&write_list); | |
1081 | ||
1082 | if (!b) | |
1083 | return NULL; | |
1084 | ||
1085 | if (need_submit) | |
1086 | submit_io(b, REQ_OP_READ, read_endio); | |
1087 | ||
1088 | wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); | |
1089 | ||
1090 | if (b->read_error) { | |
1091 | int error = blk_status_to_errno(b->read_error); | |
1092 | ||
1093 | dm_bufio_release(b); | |
1094 | ||
1095 | return ERR_PTR(error); | |
1096 | } | |
1097 | ||
1098 | *bp = b; | |
1099 | ||
1100 | return b->data; | |
1101 | } | |
1102 | ||
1103 | void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, | |
1104 | struct dm_buffer **bp) | |
1105 | { | |
1106 | return new_read(c, block, NF_GET, bp); | |
1107 | } | |
1108 | EXPORT_SYMBOL_GPL(dm_bufio_get); | |
1109 | ||
1110 | void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, | |
1111 | struct dm_buffer **bp) | |
1112 | { | |
1113 | BUG_ON(dm_bufio_in_request()); | |
1114 | ||
1115 | return new_read(c, block, NF_READ, bp); | |
1116 | } | |
1117 | EXPORT_SYMBOL_GPL(dm_bufio_read); | |
1118 | ||
1119 | void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, | |
1120 | struct dm_buffer **bp) | |
1121 | { | |
1122 | BUG_ON(dm_bufio_in_request()); | |
1123 | ||
1124 | return new_read(c, block, NF_FRESH, bp); | |
1125 | } | |
1126 | EXPORT_SYMBOL_GPL(dm_bufio_new); | |
1127 | ||
1128 | void dm_bufio_prefetch(struct dm_bufio_client *c, | |
1129 | sector_t block, unsigned n_blocks) | |
1130 | { | |
1131 | struct blk_plug plug; | |
1132 | ||
1133 | LIST_HEAD(write_list); | |
1134 | ||
1135 | BUG_ON(dm_bufio_in_request()); | |
1136 | ||
1137 | blk_start_plug(&plug); | |
1138 | dm_bufio_lock(c); | |
1139 | ||
1140 | for (; n_blocks--; block++) { | |
1141 | int need_submit; | |
1142 | struct dm_buffer *b; | |
1143 | b = __bufio_new(c, block, NF_PREFETCH, &need_submit, | |
1144 | &write_list); | |
1145 | if (unlikely(!list_empty(&write_list))) { | |
1146 | dm_bufio_unlock(c); | |
1147 | blk_finish_plug(&plug); | |
1148 | __flush_write_list(&write_list); | |
1149 | blk_start_plug(&plug); | |
1150 | dm_bufio_lock(c); | |
1151 | } | |
1152 | if (unlikely(b != NULL)) { | |
1153 | dm_bufio_unlock(c); | |
1154 | ||
1155 | if (need_submit) | |
1156 | submit_io(b, REQ_OP_READ, read_endio); | |
1157 | dm_bufio_release(b); | |
1158 | ||
1159 | cond_resched(); | |
1160 | ||
1161 | if (!n_blocks) | |
1162 | goto flush_plug; | |
1163 | dm_bufio_lock(c); | |
1164 | } | |
1165 | } | |
1166 | ||
1167 | dm_bufio_unlock(c); | |
1168 | ||
1169 | flush_plug: | |
1170 | blk_finish_plug(&plug); | |
1171 | } | |
1172 | EXPORT_SYMBOL_GPL(dm_bufio_prefetch); | |
1173 | ||
1174 | void dm_bufio_release(struct dm_buffer *b) | |
1175 | { | |
1176 | struct dm_bufio_client *c = b->c; | |
1177 | ||
1178 | dm_bufio_lock(c); | |
1179 | ||
1180 | BUG_ON(!b->hold_count); | |
1181 | ||
1182 | b->hold_count--; | |
1183 | if (!b->hold_count) { | |
1184 | wake_up(&c->free_buffer_wait); | |
1185 | ||
1186 | /* | |
1187 | * If there were errors on the buffer, and the buffer is not | |
1188 | * to be written, free the buffer. There is no point in caching | |
1189 | * invalid buffer. | |
1190 | */ | |
1191 | if ((b->read_error || b->write_error) && | |
1192 | !test_bit(B_READING, &b->state) && | |
1193 | !test_bit(B_WRITING, &b->state) && | |
1194 | !test_bit(B_DIRTY, &b->state)) { | |
1195 | __unlink_buffer(b); | |
1196 | __free_buffer_wake(b); | |
1197 | } | |
1198 | } | |
1199 | ||
1200 | dm_bufio_unlock(c); | |
1201 | } | |
1202 | EXPORT_SYMBOL_GPL(dm_bufio_release); | |
1203 | ||
1204 | void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, | |
1205 | unsigned start, unsigned end) | |
1206 | { | |
1207 | struct dm_bufio_client *c = b->c; | |
1208 | ||
1209 | BUG_ON(start >= end); | |
1210 | BUG_ON(end > b->c->block_size); | |
1211 | ||
1212 | dm_bufio_lock(c); | |
1213 | ||
1214 | BUG_ON(test_bit(B_READING, &b->state)); | |
1215 | ||
1216 | if (!test_and_set_bit(B_DIRTY, &b->state)) { | |
1217 | b->dirty_start = start; | |
1218 | b->dirty_end = end; | |
1219 | __relink_lru(b, LIST_DIRTY); | |
1220 | } else { | |
1221 | if (start < b->dirty_start) | |
1222 | b->dirty_start = start; | |
1223 | if (end > b->dirty_end) | |
1224 | b->dirty_end = end; | |
1225 | } | |
1226 | ||
1227 | dm_bufio_unlock(c); | |
1228 | } | |
1229 | EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty); | |
1230 | ||
1231 | void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) | |
1232 | { | |
1233 | dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size); | |
1234 | } | |
1235 | EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty); | |
1236 | ||
1237 | void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) | |
1238 | { | |
1239 | LIST_HEAD(write_list); | |
1240 | ||
1241 | BUG_ON(dm_bufio_in_request()); | |
1242 | ||
1243 | dm_bufio_lock(c); | |
1244 | __write_dirty_buffers_async(c, 0, &write_list); | |
1245 | dm_bufio_unlock(c); | |
1246 | __flush_write_list(&write_list); | |
1247 | } | |
1248 | EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); | |
1249 | ||
1250 | /* | |
1251 | * For performance, it is essential that the buffers are written asynchronously | |
1252 | * and simultaneously (so that the block layer can merge the writes) and then | |
1253 | * waited upon. | |
1254 | * | |
1255 | * Finally, we flush hardware disk cache. | |
1256 | */ | |
1257 | int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) | |
1258 | { | |
1259 | int a, f; | |
1260 | unsigned long buffers_processed = 0; | |
1261 | struct dm_buffer *b, *tmp; | |
1262 | ||
1263 | LIST_HEAD(write_list); | |
1264 | ||
1265 | dm_bufio_lock(c); | |
1266 | __write_dirty_buffers_async(c, 0, &write_list); | |
1267 | dm_bufio_unlock(c); | |
1268 | __flush_write_list(&write_list); | |
1269 | dm_bufio_lock(c); | |
1270 | ||
1271 | again: | |
1272 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { | |
1273 | int dropped_lock = 0; | |
1274 | ||
1275 | if (buffers_processed < c->n_buffers[LIST_DIRTY]) | |
1276 | buffers_processed++; | |
1277 | ||
1278 | BUG_ON(test_bit(B_READING, &b->state)); | |
1279 | ||
1280 | if (test_bit(B_WRITING, &b->state)) { | |
1281 | if (buffers_processed < c->n_buffers[LIST_DIRTY]) { | |
1282 | dropped_lock = 1; | |
1283 | b->hold_count++; | |
1284 | dm_bufio_unlock(c); | |
1285 | wait_on_bit_io(&b->state, B_WRITING, | |
1286 | TASK_UNINTERRUPTIBLE); | |
1287 | dm_bufio_lock(c); | |
1288 | b->hold_count--; | |
1289 | } else | |
1290 | wait_on_bit_io(&b->state, B_WRITING, | |
1291 | TASK_UNINTERRUPTIBLE); | |
1292 | } | |
1293 | ||
1294 | if (!test_bit(B_DIRTY, &b->state) && | |
1295 | !test_bit(B_WRITING, &b->state)) | |
1296 | __relink_lru(b, LIST_CLEAN); | |
1297 | ||
1298 | cond_resched(); | |
1299 | ||
1300 | /* | |
1301 | * If we dropped the lock, the list is no longer consistent, | |
1302 | * so we must restart the search. | |
1303 | * | |
1304 | * In the most common case, the buffer just processed is | |
1305 | * relinked to the clean list, so we won't loop scanning the | |
1306 | * same buffer again and again. | |
1307 | * | |
1308 | * This may livelock if there is another thread simultaneously | |
1309 | * dirtying buffers, so we count the number of buffers walked | |
1310 | * and if it exceeds the total number of buffers, it means that | |
1311 | * someone is doing some writes simultaneously with us. In | |
1312 | * this case, stop, dropping the lock. | |
1313 | */ | |
1314 | if (dropped_lock) | |
1315 | goto again; | |
1316 | } | |
1317 | wake_up(&c->free_buffer_wait); | |
1318 | dm_bufio_unlock(c); | |
1319 | ||
1320 | a = xchg(&c->async_write_error, 0); | |
1321 | f = dm_bufio_issue_flush(c); | |
1322 | if (a) | |
1323 | return a; | |
1324 | ||
1325 | return f; | |
1326 | } | |
1327 | EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers); | |
1328 | ||
1329 | /* | |
1330 | * Use dm-io to send and empty barrier flush the device. | |
1331 | */ | |
1332 | int dm_bufio_issue_flush(struct dm_bufio_client *c) | |
1333 | { | |
1334 | struct dm_io_request io_req = { | |
1335 | .bi_op = REQ_OP_WRITE, | |
1336 | .bi_op_flags = REQ_PREFLUSH | REQ_SYNC, | |
1337 | .mem.type = DM_IO_KMEM, | |
1338 | .mem.ptr.addr = NULL, | |
1339 | .client = c->dm_io, | |
1340 | }; | |
1341 | struct dm_io_region io_reg = { | |
1342 | .bdev = c->bdev, | |
1343 | .sector = 0, | |
1344 | .count = 0, | |
1345 | }; | |
1346 | ||
1347 | BUG_ON(dm_bufio_in_request()); | |
1348 | ||
1349 | return dm_io(&io_req, 1, &io_reg, NULL); | |
1350 | } | |
1351 | EXPORT_SYMBOL_GPL(dm_bufio_issue_flush); | |
1352 | ||
1353 | /* | |
1354 | * We first delete any other buffer that may be at that new location. | |
1355 | * | |
1356 | * Then, we write the buffer to the original location if it was dirty. | |
1357 | * | |
1358 | * Then, if we are the only one who is holding the buffer, relink the buffer | |
1359 | * in the hash queue for the new location. | |
1360 | * | |
1361 | * If there was someone else holding the buffer, we write it to the new | |
1362 | * location but not relink it, because that other user needs to have the buffer | |
1363 | * at the same place. | |
1364 | */ | |
1365 | void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block) | |
1366 | { | |
1367 | struct dm_bufio_client *c = b->c; | |
1368 | struct dm_buffer *new; | |
1369 | ||
1370 | BUG_ON(dm_bufio_in_request()); | |
1371 | ||
1372 | dm_bufio_lock(c); | |
1373 | ||
1374 | retry: | |
1375 | new = __find(c, new_block); | |
1376 | if (new) { | |
1377 | if (new->hold_count) { | |
1378 | __wait_for_free_buffer(c); | |
1379 | goto retry; | |
1380 | } | |
1381 | ||
1382 | /* | |
1383 | * FIXME: Is there any point waiting for a write that's going | |
1384 | * to be overwritten in a bit? | |
1385 | */ | |
1386 | __make_buffer_clean(new); | |
1387 | __unlink_buffer(new); | |
1388 | __free_buffer_wake(new); | |
1389 | } | |
1390 | ||
1391 | BUG_ON(!b->hold_count); | |
1392 | BUG_ON(test_bit(B_READING, &b->state)); | |
1393 | ||
1394 | __write_dirty_buffer(b, NULL); | |
1395 | if (b->hold_count == 1) { | |
1396 | wait_on_bit_io(&b->state, B_WRITING, | |
1397 | TASK_UNINTERRUPTIBLE); | |
1398 | set_bit(B_DIRTY, &b->state); | |
1399 | b->dirty_start = 0; | |
1400 | b->dirty_end = c->block_size; | |
1401 | __unlink_buffer(b); | |
1402 | __link_buffer(b, new_block, LIST_DIRTY); | |
1403 | } else { | |
1404 | sector_t old_block; | |
1405 | wait_on_bit_lock_io(&b->state, B_WRITING, | |
1406 | TASK_UNINTERRUPTIBLE); | |
1407 | /* | |
1408 | * Relink buffer to "new_block" so that write_callback | |
1409 | * sees "new_block" as a block number. | |
1410 | * After the write, link the buffer back to old_block. | |
1411 | * All this must be done in bufio lock, so that block number | |
1412 | * change isn't visible to other threads. | |
1413 | */ | |
1414 | old_block = b->block; | |
1415 | __unlink_buffer(b); | |
1416 | __link_buffer(b, new_block, b->list_mode); | |
1417 | submit_io(b, REQ_OP_WRITE, write_endio); | |
1418 | wait_on_bit_io(&b->state, B_WRITING, | |
1419 | TASK_UNINTERRUPTIBLE); | |
1420 | __unlink_buffer(b); | |
1421 | __link_buffer(b, old_block, b->list_mode); | |
1422 | } | |
1423 | ||
1424 | dm_bufio_unlock(c); | |
1425 | dm_bufio_release(b); | |
1426 | } | |
1427 | EXPORT_SYMBOL_GPL(dm_bufio_release_move); | |
1428 | ||
1429 | /* | |
1430 | * Free the given buffer. | |
1431 | * | |
1432 | * This is just a hint, if the buffer is in use or dirty, this function | |
1433 | * does nothing. | |
1434 | */ | |
1435 | void dm_bufio_forget(struct dm_bufio_client *c, sector_t block) | |
1436 | { | |
1437 | struct dm_buffer *b; | |
1438 | ||
1439 | dm_bufio_lock(c); | |
1440 | ||
1441 | b = __find(c, block); | |
1442 | if (b && likely(!b->hold_count) && likely(!b->state)) { | |
1443 | __unlink_buffer(b); | |
1444 | __free_buffer_wake(b); | |
1445 | } | |
1446 | ||
1447 | dm_bufio_unlock(c); | |
1448 | } | |
1449 | EXPORT_SYMBOL_GPL(dm_bufio_forget); | |
1450 | ||
1451 | void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n) | |
1452 | { | |
1453 | c->minimum_buffers = n; | |
1454 | } | |
1455 | EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers); | |
1456 | ||
1457 | unsigned dm_bufio_get_block_size(struct dm_bufio_client *c) | |
1458 | { | |
1459 | return c->block_size; | |
1460 | } | |
1461 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_size); | |
1462 | ||
1463 | sector_t dm_bufio_get_device_size(struct dm_bufio_client *c) | |
1464 | { | |
1465 | sector_t s = i_size_read(c->bdev->bd_inode) >> SECTOR_SHIFT; | |
1466 | if (likely(c->sectors_per_block_bits >= 0)) | |
1467 | s >>= c->sectors_per_block_bits; | |
1468 | else | |
1469 | sector_div(s, c->block_size >> SECTOR_SHIFT); | |
1470 | return s; | |
1471 | } | |
1472 | EXPORT_SYMBOL_GPL(dm_bufio_get_device_size); | |
1473 | ||
1474 | sector_t dm_bufio_get_block_number(struct dm_buffer *b) | |
1475 | { | |
1476 | return b->block; | |
1477 | } | |
1478 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_number); | |
1479 | ||
1480 | void *dm_bufio_get_block_data(struct dm_buffer *b) | |
1481 | { | |
1482 | return b->data; | |
1483 | } | |
1484 | EXPORT_SYMBOL_GPL(dm_bufio_get_block_data); | |
1485 | ||
1486 | void *dm_bufio_get_aux_data(struct dm_buffer *b) | |
1487 | { | |
1488 | return b + 1; | |
1489 | } | |
1490 | EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data); | |
1491 | ||
1492 | struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) | |
1493 | { | |
1494 | return b->c; | |
1495 | } | |
1496 | EXPORT_SYMBOL_GPL(dm_bufio_get_client); | |
1497 | ||
1498 | static void drop_buffers(struct dm_bufio_client *c) | |
1499 | { | |
1500 | struct dm_buffer *b; | |
1501 | int i; | |
1502 | bool warned = false; | |
1503 | ||
1504 | BUG_ON(dm_bufio_in_request()); | |
1505 | ||
1506 | /* | |
1507 | * An optimization so that the buffers are not written one-by-one. | |
1508 | */ | |
1509 | dm_bufio_write_dirty_buffers_async(c); | |
1510 | ||
1511 | dm_bufio_lock(c); | |
1512 | ||
1513 | while ((b = __get_unclaimed_buffer(c))) | |
1514 | __free_buffer_wake(b); | |
1515 | ||
1516 | for (i = 0; i < LIST_SIZE; i++) | |
1517 | list_for_each_entry(b, &c->lru[i], lru_list) { | |
1518 | WARN_ON(!warned); | |
1519 | warned = true; | |
1520 | DMERR("leaked buffer %llx, hold count %u, list %d", | |
1521 | (unsigned long long)b->block, b->hold_count, i); | |
1522 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
1523 | print_stack_trace(&b->stack_trace, 1); | |
1524 | b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */ | |
1525 | #endif | |
1526 | } | |
1527 | ||
1528 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
1529 | while ((b = __get_unclaimed_buffer(c))) | |
1530 | __free_buffer_wake(b); | |
1531 | #endif | |
1532 | ||
1533 | for (i = 0; i < LIST_SIZE; i++) | |
1534 | BUG_ON(!list_empty(&c->lru[i])); | |
1535 | ||
1536 | dm_bufio_unlock(c); | |
1537 | } | |
1538 | ||
1539 | /* | |
1540 | * We may not be able to evict this buffer if IO pending or the client | |
1541 | * is still using it. Caller is expected to know buffer is too old. | |
1542 | * | |
1543 | * And if GFP_NOFS is used, we must not do any I/O because we hold | |
1544 | * dm_bufio_clients_lock and we would risk deadlock if the I/O gets | |
1545 | * rerouted to different bufio client. | |
1546 | */ | |
1547 | static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) | |
1548 | { | |
1549 | if (!(gfp & __GFP_FS)) { | |
1550 | if (test_bit(B_READING, &b->state) || | |
1551 | test_bit(B_WRITING, &b->state) || | |
1552 | test_bit(B_DIRTY, &b->state)) | |
1553 | return false; | |
1554 | } | |
1555 | ||
1556 | if (b->hold_count) | |
1557 | return false; | |
1558 | ||
1559 | __make_buffer_clean(b); | |
1560 | __unlink_buffer(b); | |
1561 | __free_buffer_wake(b); | |
1562 | ||
1563 | return true; | |
1564 | } | |
1565 | ||
1566 | static unsigned long get_retain_buffers(struct dm_bufio_client *c) | |
1567 | { | |
1568 | unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes); | |
1569 | if (likely(c->sectors_per_block_bits >= 0)) | |
1570 | retain_bytes >>= c->sectors_per_block_bits + SECTOR_SHIFT; | |
1571 | else | |
1572 | retain_bytes /= c->block_size; | |
1573 | return retain_bytes; | |
1574 | } | |
1575 | ||
1576 | static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, | |
1577 | gfp_t gfp_mask) | |
1578 | { | |
1579 | int l; | |
1580 | struct dm_buffer *b, *tmp; | |
1581 | unsigned long freed = 0; | |
1582 | unsigned long count = c->n_buffers[LIST_CLEAN] + | |
1583 | c->n_buffers[LIST_DIRTY]; | |
1584 | unsigned long retain_target = get_retain_buffers(c); | |
1585 | ||
1586 | for (l = 0; l < LIST_SIZE; l++) { | |
1587 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { | |
1588 | if (__try_evict_buffer(b, gfp_mask)) | |
1589 | freed++; | |
1590 | if (!--nr_to_scan || ((count - freed) <= retain_target)) | |
1591 | return freed; | |
1592 | cond_resched(); | |
1593 | } | |
1594 | } | |
1595 | return freed; | |
1596 | } | |
1597 | ||
1598 | static unsigned long | |
1599 | dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) | |
1600 | { | |
1601 | struct dm_bufio_client *c; | |
1602 | unsigned long freed; | |
1603 | ||
1604 | c = container_of(shrink, struct dm_bufio_client, shrinker); | |
1605 | if (sc->gfp_mask & __GFP_FS) | |
1606 | dm_bufio_lock(c); | |
1607 | else if (!dm_bufio_trylock(c)) | |
1608 | return SHRINK_STOP; | |
1609 | ||
1610 | freed = __scan(c, sc->nr_to_scan, sc->gfp_mask); | |
1611 | dm_bufio_unlock(c); | |
1612 | return freed; | |
1613 | } | |
1614 | ||
1615 | static unsigned long | |
1616 | dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc) | |
1617 | { | |
1618 | struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker); | |
1619 | unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) + | |
1620 | READ_ONCE(c->n_buffers[LIST_DIRTY]); | |
1621 | unsigned long retain_target = get_retain_buffers(c); | |
1622 | ||
1623 | return (count < retain_target) ? 0 : (count - retain_target); | |
1624 | } | |
1625 | ||
1626 | /* | |
1627 | * Create the buffering interface | |
1628 | */ | |
1629 | struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size, | |
1630 | unsigned reserved_buffers, unsigned aux_size, | |
1631 | void (*alloc_callback)(struct dm_buffer *), | |
1632 | void (*write_callback)(struct dm_buffer *)) | |
1633 | { | |
1634 | int r; | |
1635 | struct dm_bufio_client *c; | |
1636 | unsigned i; | |
1637 | char slab_name[27]; | |
1638 | ||
1639 | if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) { | |
1640 | DMERR("%s: block size not specified or is not multiple of 512b", __func__); | |
1641 | r = -EINVAL; | |
1642 | goto bad_client; | |
1643 | } | |
1644 | ||
1645 | c = kzalloc(sizeof(*c), GFP_KERNEL); | |
1646 | if (!c) { | |
1647 | r = -ENOMEM; | |
1648 | goto bad_client; | |
1649 | } | |
1650 | c->buffer_tree = RB_ROOT; | |
1651 | ||
1652 | c->bdev = bdev; | |
1653 | c->block_size = block_size; | |
1654 | if (is_power_of_2(block_size)) | |
1655 | c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT; | |
1656 | else | |
1657 | c->sectors_per_block_bits = -1; | |
1658 | ||
1659 | c->alloc_callback = alloc_callback; | |
1660 | c->write_callback = write_callback; | |
1661 | ||
1662 | for (i = 0; i < LIST_SIZE; i++) { | |
1663 | INIT_LIST_HEAD(&c->lru[i]); | |
1664 | c->n_buffers[i] = 0; | |
1665 | } | |
1666 | ||
1667 | mutex_init(&c->lock); | |
1668 | INIT_LIST_HEAD(&c->reserved_buffers); | |
1669 | c->need_reserved_buffers = reserved_buffers; | |
1670 | ||
1671 | dm_bufio_set_minimum_buffers(c, DM_BUFIO_MIN_BUFFERS); | |
1672 | ||
1673 | init_waitqueue_head(&c->free_buffer_wait); | |
1674 | c->async_write_error = 0; | |
1675 | ||
1676 | c->dm_io = dm_io_client_create(); | |
1677 | if (IS_ERR(c->dm_io)) { | |
1678 | r = PTR_ERR(c->dm_io); | |
1679 | goto bad_dm_io; | |
1680 | } | |
1681 | ||
1682 | if (block_size <= KMALLOC_MAX_SIZE && | |
1683 | (block_size < PAGE_SIZE || !is_power_of_2(block_size))) { | |
1684 | unsigned align = min(1U << __ffs(block_size), (unsigned)PAGE_SIZE); | |
1685 | snprintf(slab_name, sizeof slab_name, "dm_bufio_cache-%u", block_size); | |
1686 | c->slab_cache = kmem_cache_create(slab_name, block_size, align, | |
1687 | SLAB_RECLAIM_ACCOUNT, NULL); | |
1688 | if (!c->slab_cache) { | |
1689 | r = -ENOMEM; | |
1690 | goto bad; | |
1691 | } | |
1692 | } | |
1693 | if (aux_size) | |
1694 | snprintf(slab_name, sizeof slab_name, "dm_bufio_buffer-%u", aux_size); | |
1695 | else | |
1696 | snprintf(slab_name, sizeof slab_name, "dm_bufio_buffer"); | |
1697 | c->slab_buffer = kmem_cache_create(slab_name, sizeof(struct dm_buffer) + aux_size, | |
1698 | 0, SLAB_RECLAIM_ACCOUNT, NULL); | |
1699 | if (!c->slab_buffer) { | |
1700 | r = -ENOMEM; | |
1701 | goto bad; | |
1702 | } | |
1703 | ||
1704 | while (c->need_reserved_buffers) { | |
1705 | struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); | |
1706 | ||
1707 | if (!b) { | |
1708 | r = -ENOMEM; | |
1709 | goto bad; | |
1710 | } | |
1711 | __free_buffer_wake(b); | |
1712 | } | |
1713 | ||
1714 | c->shrinker.count_objects = dm_bufio_shrink_count; | |
1715 | c->shrinker.scan_objects = dm_bufio_shrink_scan; | |
1716 | c->shrinker.seeks = 1; | |
1717 | c->shrinker.batch = 0; | |
1718 | r = register_shrinker(&c->shrinker); | |
1719 | if (r) | |
1720 | goto bad; | |
1721 | ||
1722 | mutex_lock(&dm_bufio_clients_lock); | |
1723 | dm_bufio_client_count++; | |
1724 | list_add(&c->client_list, &dm_bufio_all_clients); | |
1725 | __cache_size_refresh(); | |
1726 | mutex_unlock(&dm_bufio_clients_lock); | |
1727 | ||
1728 | return c; | |
1729 | ||
1730 | bad: | |
1731 | while (!list_empty(&c->reserved_buffers)) { | |
1732 | struct dm_buffer *b = list_entry(c->reserved_buffers.next, | |
1733 | struct dm_buffer, lru_list); | |
1734 | list_del(&b->lru_list); | |
1735 | free_buffer(b); | |
1736 | } | |
1737 | kmem_cache_destroy(c->slab_cache); | |
1738 | kmem_cache_destroy(c->slab_buffer); | |
1739 | dm_io_client_destroy(c->dm_io); | |
1740 | bad_dm_io: | |
1741 | mutex_destroy(&c->lock); | |
1742 | kfree(c); | |
1743 | bad_client: | |
1744 | return ERR_PTR(r); | |
1745 | } | |
1746 | EXPORT_SYMBOL_GPL(dm_bufio_client_create); | |
1747 | ||
1748 | /* | |
1749 | * Free the buffering interface. | |
1750 | * It is required that there are no references on any buffers. | |
1751 | */ | |
1752 | void dm_bufio_client_destroy(struct dm_bufio_client *c) | |
1753 | { | |
1754 | unsigned i; | |
1755 | ||
1756 | drop_buffers(c); | |
1757 | ||
1758 | unregister_shrinker(&c->shrinker); | |
1759 | ||
1760 | mutex_lock(&dm_bufio_clients_lock); | |
1761 | ||
1762 | list_del(&c->client_list); | |
1763 | dm_bufio_client_count--; | |
1764 | __cache_size_refresh(); | |
1765 | ||
1766 | mutex_unlock(&dm_bufio_clients_lock); | |
1767 | ||
1768 | BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree)); | |
1769 | BUG_ON(c->need_reserved_buffers); | |
1770 | ||
1771 | while (!list_empty(&c->reserved_buffers)) { | |
1772 | struct dm_buffer *b = list_entry(c->reserved_buffers.next, | |
1773 | struct dm_buffer, lru_list); | |
1774 | list_del(&b->lru_list); | |
1775 | free_buffer(b); | |
1776 | } | |
1777 | ||
1778 | for (i = 0; i < LIST_SIZE; i++) | |
1779 | if (c->n_buffers[i]) | |
1780 | DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]); | |
1781 | ||
1782 | for (i = 0; i < LIST_SIZE; i++) | |
1783 | BUG_ON(c->n_buffers[i]); | |
1784 | ||
1785 | kmem_cache_destroy(c->slab_cache); | |
1786 | kmem_cache_destroy(c->slab_buffer); | |
1787 | dm_io_client_destroy(c->dm_io); | |
1788 | mutex_destroy(&c->lock); | |
1789 | kfree(c); | |
1790 | } | |
1791 | EXPORT_SYMBOL_GPL(dm_bufio_client_destroy); | |
1792 | ||
1793 | void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start) | |
1794 | { | |
1795 | c->start = start; | |
1796 | } | |
1797 | EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset); | |
1798 | ||
1799 | static unsigned get_max_age_hz(void) | |
1800 | { | |
1801 | unsigned max_age = READ_ONCE(dm_bufio_max_age); | |
1802 | ||
1803 | if (max_age > UINT_MAX / HZ) | |
1804 | max_age = UINT_MAX / HZ; | |
1805 | ||
1806 | return max_age * HZ; | |
1807 | } | |
1808 | ||
1809 | static bool older_than(struct dm_buffer *b, unsigned long age_hz) | |
1810 | { | |
1811 | return time_after_eq(jiffies, b->last_accessed + age_hz); | |
1812 | } | |
1813 | ||
1814 | static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) | |
1815 | { | |
1816 | struct dm_buffer *b, *tmp; | |
1817 | unsigned long retain_target = get_retain_buffers(c); | |
1818 | unsigned long count; | |
1819 | LIST_HEAD(write_list); | |
1820 | ||
1821 | dm_bufio_lock(c); | |
1822 | ||
1823 | __check_watermark(c, &write_list); | |
1824 | if (unlikely(!list_empty(&write_list))) { | |
1825 | dm_bufio_unlock(c); | |
1826 | __flush_write_list(&write_list); | |
1827 | dm_bufio_lock(c); | |
1828 | } | |
1829 | ||
1830 | count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; | |
1831 | list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { | |
1832 | if (count <= retain_target) | |
1833 | break; | |
1834 | ||
1835 | if (!older_than(b, age_hz)) | |
1836 | break; | |
1837 | ||
1838 | if (__try_evict_buffer(b, 0)) | |
1839 | count--; | |
1840 | ||
1841 | cond_resched(); | |
1842 | } | |
1843 | ||
1844 | dm_bufio_unlock(c); | |
1845 | } | |
1846 | ||
1847 | static void cleanup_old_buffers(void) | |
1848 | { | |
1849 | unsigned long max_age_hz = get_max_age_hz(); | |
1850 | struct dm_bufio_client *c; | |
1851 | ||
1852 | mutex_lock(&dm_bufio_clients_lock); | |
1853 | ||
1854 | __cache_size_refresh(); | |
1855 | ||
1856 | list_for_each_entry(c, &dm_bufio_all_clients, client_list) | |
1857 | __evict_old_buffers(c, max_age_hz); | |
1858 | ||
1859 | mutex_unlock(&dm_bufio_clients_lock); | |
1860 | } | |
1861 | ||
1862 | static struct workqueue_struct *dm_bufio_wq; | |
1863 | static struct delayed_work dm_bufio_work; | |
1864 | ||
1865 | static void work_fn(struct work_struct *w) | |
1866 | { | |
1867 | cleanup_old_buffers(); | |
1868 | ||
1869 | queue_delayed_work(dm_bufio_wq, &dm_bufio_work, | |
1870 | DM_BUFIO_WORK_TIMER_SECS * HZ); | |
1871 | } | |
1872 | ||
1873 | /*---------------------------------------------------------------- | |
1874 | * Module setup | |
1875 | *--------------------------------------------------------------*/ | |
1876 | ||
1877 | /* | |
1878 | * This is called only once for the whole dm_bufio module. | |
1879 | * It initializes memory limit. | |
1880 | */ | |
1881 | static int __init dm_bufio_init(void) | |
1882 | { | |
1883 | __u64 mem; | |
1884 | ||
1885 | dm_bufio_allocated_kmem_cache = 0; | |
1886 | dm_bufio_allocated_get_free_pages = 0; | |
1887 | dm_bufio_allocated_vmalloc = 0; | |
1888 | dm_bufio_current_allocated = 0; | |
1889 | ||
1890 | mem = (__u64)mult_frac(totalram_pages - totalhigh_pages, | |
1891 | DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT; | |
1892 | ||
1893 | if (mem > ULONG_MAX) | |
1894 | mem = ULONG_MAX; | |
1895 | ||
1896 | #ifdef CONFIG_MMU | |
1897 | if (mem > mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100)) | |
1898 | mem = mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100); | |
1899 | #endif | |
1900 | ||
1901 | dm_bufio_default_cache_size = mem; | |
1902 | ||
1903 | mutex_lock(&dm_bufio_clients_lock); | |
1904 | __cache_size_refresh(); | |
1905 | mutex_unlock(&dm_bufio_clients_lock); | |
1906 | ||
1907 | dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0); | |
1908 | if (!dm_bufio_wq) | |
1909 | return -ENOMEM; | |
1910 | ||
1911 | INIT_DELAYED_WORK(&dm_bufio_work, work_fn); | |
1912 | queue_delayed_work(dm_bufio_wq, &dm_bufio_work, | |
1913 | DM_BUFIO_WORK_TIMER_SECS * HZ); | |
1914 | ||
1915 | return 0; | |
1916 | } | |
1917 | ||
1918 | /* | |
1919 | * This is called once when unloading the dm_bufio module. | |
1920 | */ | |
1921 | static void __exit dm_bufio_exit(void) | |
1922 | { | |
1923 | int bug = 0; | |
1924 | ||
1925 | cancel_delayed_work_sync(&dm_bufio_work); | |
1926 | destroy_workqueue(dm_bufio_wq); | |
1927 | ||
1928 | if (dm_bufio_client_count) { | |
1929 | DMCRIT("%s: dm_bufio_client_count leaked: %d", | |
1930 | __func__, dm_bufio_client_count); | |
1931 | bug = 1; | |
1932 | } | |
1933 | ||
1934 | if (dm_bufio_current_allocated) { | |
1935 | DMCRIT("%s: dm_bufio_current_allocated leaked: %lu", | |
1936 | __func__, dm_bufio_current_allocated); | |
1937 | bug = 1; | |
1938 | } | |
1939 | ||
1940 | if (dm_bufio_allocated_get_free_pages) { | |
1941 | DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu", | |
1942 | __func__, dm_bufio_allocated_get_free_pages); | |
1943 | bug = 1; | |
1944 | } | |
1945 | ||
1946 | if (dm_bufio_allocated_vmalloc) { | |
1947 | DMCRIT("%s: dm_bufio_vmalloc leaked: %lu", | |
1948 | __func__, dm_bufio_allocated_vmalloc); | |
1949 | bug = 1; | |
1950 | } | |
1951 | ||
1952 | BUG_ON(bug); | |
1953 | } | |
1954 | ||
1955 | module_init(dm_bufio_init) | |
1956 | module_exit(dm_bufio_exit) | |
1957 | ||
1958 | module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR); | |
1959 | MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); | |
1960 | ||
1961 | module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR); | |
1962 | MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds"); | |
1963 | ||
1964 | module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR); | |
1965 | MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory"); | |
1966 | ||
1967 | module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR); | |
1968 | MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory"); | |
1969 | ||
1970 | module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO); | |
1971 | MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc"); | |
1972 | ||
1973 | module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO); | |
1974 | MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages"); | |
1975 | ||
1976 | module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO); | |
1977 | MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc"); | |
1978 | ||
1979 | module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO); | |
1980 | MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache"); | |
1981 | ||
1982 | MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>"); | |
1983 | MODULE_DESCRIPTION(DM_NAME " buffered I/O library"); | |
1984 | MODULE_LICENSE("GPL"); |