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Mikulas Patocka95d402f2011-10-31 20:19:09 +00001/*
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>
Mikulas Patocka95d402f2011-10-31 20:19:09 +000015#include <linux/shrinker.h>
Stephen Rothwell6f662632011-11-01 18:30:49 +110016#include <linux/module.h>
Mikulas Patocka95d402f2011-10-31 20:19:09 +000017
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 */
87struct 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
Mikulas Patocka55b082e2014-01-13 19:13:05 -0500107 unsigned minimum_buffers;
108
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000109 struct hlist_head *cache_hash;
110 wait_queue_head_t free_buffer_wait;
111
112 int async_write_error;
113
114 struct list_head client_list;
115 struct shrinker shrinker;
116};
117
118/*
119 * Buffer state bits.
120 */
121#define B_READING 0
122#define B_WRITING 1
123#define B_DIRTY 2
124
125/*
126 * Describes how the block was allocated:
127 * kmem_cache_alloc(), __get_free_pages() or vmalloc().
128 * See the comment at alloc_buffer_data.
129 */
130enum data_mode {
131 DATA_MODE_SLAB = 0,
132 DATA_MODE_GET_FREE_PAGES = 1,
133 DATA_MODE_VMALLOC = 2,
134 DATA_MODE_LIMIT = 3
135};
136
137struct dm_buffer {
138 struct hlist_node hash_list;
139 struct list_head lru_list;
140 sector_t block;
141 void *data;
142 enum data_mode data_mode;
143 unsigned char list_mode; /* LIST_* */
144 unsigned hold_count;
145 int read_error;
146 int write_error;
147 unsigned long state;
148 unsigned long last_accessed;
149 struct dm_bufio_client *c;
Mikulas Patocka24809452013-07-10 23:41:18 +0100150 struct list_head write_list;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000151 struct bio bio;
152 struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
153};
154
155/*----------------------------------------------------------------*/
156
157static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
158static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
159
160static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
161{
162 unsigned ret = c->blocks_per_page_bits - 1;
163
164 BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
165
166 return ret;
167}
168
169#define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)])
170#define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)])
171
172#define dm_bufio_in_request() (!!current->bio_list)
173
174static void dm_bufio_lock(struct dm_bufio_client *c)
175{
176 mutex_lock_nested(&c->lock, dm_bufio_in_request());
177}
178
179static int dm_bufio_trylock(struct dm_bufio_client *c)
180{
181 return mutex_trylock(&c->lock);
182}
183
184static void dm_bufio_unlock(struct dm_bufio_client *c)
185{
186 mutex_unlock(&c->lock);
187}
188
189/*
190 * FIXME Move to sched.h?
191 */
192#ifdef CONFIG_PREEMPT_VOLUNTARY
193# define dm_bufio_cond_resched() \
194do { \
195 if (unlikely(need_resched())) \
196 _cond_resched(); \
197} while (0)
198#else
199# define dm_bufio_cond_resched() do { } while (0)
200#endif
201
202/*----------------------------------------------------------------*/
203
204/*
205 * Default cache size: available memory divided by the ratio.
206 */
207static unsigned long dm_bufio_default_cache_size;
208
209/*
210 * Total cache size set by the user.
211 */
212static unsigned long dm_bufio_cache_size;
213
214/*
215 * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
216 * at any time. If it disagrees, the user has changed cache size.
217 */
218static unsigned long dm_bufio_cache_size_latch;
219
220static DEFINE_SPINLOCK(param_spinlock);
221
222/*
223 * Buffers are freed after this timeout
224 */
225static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
226
227static unsigned long dm_bufio_peak_allocated;
228static unsigned long dm_bufio_allocated_kmem_cache;
229static unsigned long dm_bufio_allocated_get_free_pages;
230static unsigned long dm_bufio_allocated_vmalloc;
231static unsigned long dm_bufio_current_allocated;
232
233/*----------------------------------------------------------------*/
234
235/*
236 * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
237 */
238static unsigned long dm_bufio_cache_size_per_client;
239
240/*
241 * The current number of clients.
242 */
243static int dm_bufio_client_count;
244
245/*
246 * The list of all clients.
247 */
248static LIST_HEAD(dm_bufio_all_clients);
249
250/*
251 * This mutex protects dm_bufio_cache_size_latch,
252 * dm_bufio_cache_size_per_client and dm_bufio_client_count
253 */
254static DEFINE_MUTEX(dm_bufio_clients_lock);
255
256/*----------------------------------------------------------------*/
257
258static void adjust_total_allocated(enum data_mode data_mode, long diff)
259{
260 static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
261 &dm_bufio_allocated_kmem_cache,
262 &dm_bufio_allocated_get_free_pages,
263 &dm_bufio_allocated_vmalloc,
264 };
265
266 spin_lock(&param_spinlock);
267
268 *class_ptr[data_mode] += diff;
269
270 dm_bufio_current_allocated += diff;
271
272 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
273 dm_bufio_peak_allocated = dm_bufio_current_allocated;
274
275 spin_unlock(&param_spinlock);
276}
277
278/*
279 * Change the number of clients and recalculate per-client limit.
280 */
281static void __cache_size_refresh(void)
282{
283 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
284 BUG_ON(dm_bufio_client_count < 0);
285
Mikulas Patockafe5fe902012-10-12 16:59:46 +0100286 dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000287
288 /*
289 * Use default if set to 0 and report the actual cache size used.
290 */
291 if (!dm_bufio_cache_size_latch) {
292 (void)cmpxchg(&dm_bufio_cache_size, 0,
293 dm_bufio_default_cache_size);
294 dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
295 }
296
297 dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
298 (dm_bufio_client_count ? : 1);
299}
300
301/*
302 * Allocating buffer data.
303 *
304 * Small buffers are allocated with kmem_cache, to use space optimally.
305 *
306 * For large buffers, we choose between get_free_pages and vmalloc.
307 * Each has advantages and disadvantages.
308 *
309 * __get_free_pages can randomly fail if the memory is fragmented.
310 * __vmalloc won't randomly fail, but vmalloc space is limited (it may be
311 * as low as 128M) so using it for caching is not appropriate.
312 *
313 * If the allocation may fail we use __get_free_pages. Memory fragmentation
314 * won't have a fatal effect here, but it just causes flushes of some other
315 * buffers and more I/O will be performed. Don't use __get_free_pages if it
316 * always fails (i.e. order >= MAX_ORDER).
317 *
318 * If the allocation shouldn't fail we use __vmalloc. This is only for the
319 * initial reserve allocation, so there's no risk of wasting all vmalloc
320 * space.
321 */
322static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
323 enum data_mode *data_mode)
324{
Mikulas Patocka502624b2013-05-10 14:37:15 +0100325 unsigned noio_flag;
326 void *ptr;
327
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000328 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
329 *data_mode = DATA_MODE_SLAB;
330 return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
331 }
332
333 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
334 gfp_mask & __GFP_NORETRY) {
335 *data_mode = DATA_MODE_GET_FREE_PAGES;
336 return (void *)__get_free_pages(gfp_mask,
337 c->pages_per_block_bits);
338 }
339
340 *data_mode = DATA_MODE_VMALLOC;
Mikulas Patocka502624b2013-05-10 14:37:15 +0100341
342 /*
343 * __vmalloc allocates the data pages and auxiliary structures with
344 * gfp_flags that were specified, but pagetables are always allocated
345 * with GFP_KERNEL, no matter what was specified as gfp_mask.
346 *
347 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
348 * all allocations done by this process (including pagetables) are done
349 * as if GFP_NOIO was specified.
350 */
351
352 if (gfp_mask & __GFP_NORETRY)
353 noio_flag = memalloc_noio_save();
354
Mikulas Patocka220cd052013-07-10 23:41:16 +0100355 ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
Mikulas Patocka502624b2013-05-10 14:37:15 +0100356
357 if (gfp_mask & __GFP_NORETRY)
358 memalloc_noio_restore(noio_flag);
359
360 return ptr;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000361}
362
363/*
364 * Free buffer's data.
365 */
366static void free_buffer_data(struct dm_bufio_client *c,
367 void *data, enum data_mode data_mode)
368{
369 switch (data_mode) {
370 case DATA_MODE_SLAB:
371 kmem_cache_free(DM_BUFIO_CACHE(c), data);
372 break;
373
374 case DATA_MODE_GET_FREE_PAGES:
375 free_pages((unsigned long)data, c->pages_per_block_bits);
376 break;
377
378 case DATA_MODE_VMALLOC:
379 vfree(data);
380 break;
381
382 default:
383 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
384 data_mode);
385 BUG();
386 }
387}
388
389/*
390 * Allocate buffer and its data.
391 */
392static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
393{
394 struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
395 gfp_mask);
396
397 if (!b)
398 return NULL;
399
400 b->c = c;
401
402 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
403 if (!b->data) {
404 kfree(b);
405 return NULL;
406 }
407
408 adjust_total_allocated(b->data_mode, (long)c->block_size);
409
410 return b;
411}
412
413/*
414 * Free buffer and its data.
415 */
416static void free_buffer(struct dm_buffer *b)
417{
418 struct dm_bufio_client *c = b->c;
419
420 adjust_total_allocated(b->data_mode, -(long)c->block_size);
421
422 free_buffer_data(c, b->data, b->data_mode);
423 kfree(b);
424}
425
426/*
427 * Link buffer to the hash list and clean or dirty queue.
428 */
429static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
430{
431 struct dm_bufio_client *c = b->c;
432
433 c->n_buffers[dirty]++;
434 b->block = block;
435 b->list_mode = dirty;
436 list_add(&b->lru_list, &c->lru[dirty]);
437 hlist_add_head(&b->hash_list, &c->cache_hash[DM_BUFIO_HASH(block)]);
438 b->last_accessed = jiffies;
439}
440
441/*
442 * Unlink buffer from the hash list and dirty or clean queue.
443 */
444static void __unlink_buffer(struct dm_buffer *b)
445{
446 struct dm_bufio_client *c = b->c;
447
448 BUG_ON(!c->n_buffers[b->list_mode]);
449
450 c->n_buffers[b->list_mode]--;
451 hlist_del(&b->hash_list);
452 list_del(&b->lru_list);
453}
454
455/*
456 * Place the buffer to the head of dirty or clean LRU queue.
457 */
458static void __relink_lru(struct dm_buffer *b, int dirty)
459{
460 struct dm_bufio_client *c = b->c;
461
462 BUG_ON(!c->n_buffers[b->list_mode]);
463
464 c->n_buffers[b->list_mode]--;
465 c->n_buffers[dirty]++;
466 b->list_mode = dirty;
Wei Yongjun54499af2012-10-12 16:59:44 +0100467 list_move(&b->lru_list, &c->lru[dirty]);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000468}
469
470/*----------------------------------------------------------------
471 * Submit I/O on the buffer.
472 *
473 * Bio interface is faster but it has some problems:
474 * the vector list is limited (increasing this limit increases
475 * memory-consumption per buffer, so it is not viable);
476 *
477 * the memory must be direct-mapped, not vmalloced;
478 *
479 * the I/O driver can reject requests spuriously if it thinks that
480 * the requests are too big for the device or if they cross a
481 * controller-defined memory boundary.
482 *
483 * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
484 * it is not vmalloced, try using the bio interface.
485 *
486 * If the buffer is big, if it is vmalloced or if the underlying device
487 * rejects the bio because it is too large, use dm-io layer to do the I/O.
488 * The dm-io layer splits the I/O into multiple requests, avoiding the above
489 * shortcomings.
490 *--------------------------------------------------------------*/
491
492/*
493 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
494 * that the request was handled directly with bio interface.
495 */
496static void dmio_complete(unsigned long error, void *context)
497{
498 struct dm_buffer *b = context;
499
500 b->bio.bi_end_io(&b->bio, error ? -EIO : 0);
501}
502
503static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
504 bio_end_io_t *end_io)
505{
506 int r;
507 struct dm_io_request io_req = {
508 .bi_rw = rw,
509 .notify.fn = dmio_complete,
510 .notify.context = b,
511 .client = b->c->dm_io,
512 };
513 struct dm_io_region region = {
514 .bdev = b->c->bdev,
515 .sector = block << b->c->sectors_per_block_bits,
516 .count = b->c->block_size >> SECTOR_SHIFT,
517 };
518
519 if (b->data_mode != DATA_MODE_VMALLOC) {
520 io_req.mem.type = DM_IO_KMEM;
521 io_req.mem.ptr.addr = b->data;
522 } else {
523 io_req.mem.type = DM_IO_VMA;
524 io_req.mem.ptr.vma = b->data;
525 }
526
527 b->bio.bi_end_io = end_io;
528
529 r = dm_io(&io_req, 1, &region, NULL);
530 if (r)
531 end_io(&b->bio, r);
532}
533
534static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
535 bio_end_io_t *end_io)
536{
537 char *ptr;
538 int len;
539
540 bio_init(&b->bio);
541 b->bio.bi_io_vec = b->bio_vec;
542 b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
Kent Overstreet4f024f32013-10-11 15:44:27 -0700543 b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000544 b->bio.bi_bdev = b->c->bdev;
545 b->bio.bi_end_io = end_io;
546
547 /*
548 * We assume that if len >= PAGE_SIZE ptr is page-aligned.
549 * If len < PAGE_SIZE the buffer doesn't cross page boundary.
550 */
551 ptr = b->data;
552 len = b->c->block_size;
553
554 if (len >= PAGE_SIZE)
555 BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
556 else
557 BUG_ON((unsigned long)ptr & (len - 1));
558
559 do {
560 if (!bio_add_page(&b->bio, virt_to_page(ptr),
561 len < PAGE_SIZE ? len : PAGE_SIZE,
562 virt_to_phys(ptr) & (PAGE_SIZE - 1))) {
563 BUG_ON(b->c->block_size <= PAGE_SIZE);
564 use_dmio(b, rw, block, end_io);
565 return;
566 }
567
568 len -= PAGE_SIZE;
569 ptr += PAGE_SIZE;
570 } while (len > 0);
571
572 submit_bio(rw, &b->bio);
573}
574
575static void submit_io(struct dm_buffer *b, int rw, sector_t block,
576 bio_end_io_t *end_io)
577{
578 if (rw == WRITE && b->c->write_callback)
579 b->c->write_callback(b);
580
581 if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
582 b->data_mode != DATA_MODE_VMALLOC)
583 use_inline_bio(b, rw, block, end_io);
584 else
585 use_dmio(b, rw, block, end_io);
586}
587
588/*----------------------------------------------------------------
589 * Writing dirty buffers
590 *--------------------------------------------------------------*/
591
592/*
593 * The endio routine for write.
594 *
595 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
596 * it.
597 */
598static void write_endio(struct bio *bio, int error)
599{
600 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
601
602 b->write_error = error;
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100603 if (unlikely(error)) {
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000604 struct dm_bufio_client *c = b->c;
605 (void)cmpxchg(&c->async_write_error, 0, error);
606 }
607
608 BUG_ON(!test_bit(B_WRITING, &b->state));
609
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100610 smp_mb__before_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000611 clear_bit(B_WRITING, &b->state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100612 smp_mb__after_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000613
614 wake_up_bit(&b->state, B_WRITING);
615}
616
617/*
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000618 * Initiate a write on a dirty buffer, but don't wait for it.
619 *
620 * - If the buffer is not dirty, exit.
621 * - If there some previous write going on, wait for it to finish (we can't
622 * have two writes on the same buffer simultaneously).
623 * - Submit our write and don't wait on it. We set B_WRITING indicating
624 * that there is a write in progress.
625 */
Mikulas Patocka24809452013-07-10 23:41:18 +0100626static void __write_dirty_buffer(struct dm_buffer *b,
627 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000628{
629 if (!test_bit(B_DIRTY, &b->state))
630 return;
631
632 clear_bit(B_DIRTY, &b->state);
NeilBrown74316202014-07-07 15:16:04 +1000633 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000634
Mikulas Patocka24809452013-07-10 23:41:18 +0100635 if (!write_list)
636 submit_io(b, WRITE, b->block, write_endio);
637 else
638 list_add_tail(&b->write_list, write_list);
639}
640
641static void __flush_write_list(struct list_head *write_list)
642{
643 struct blk_plug plug;
644 blk_start_plug(&plug);
645 while (!list_empty(write_list)) {
646 struct dm_buffer *b =
647 list_entry(write_list->next, struct dm_buffer, write_list);
648 list_del(&b->write_list);
649 submit_io(b, WRITE, b->block, write_endio);
650 dm_bufio_cond_resched();
651 }
652 blk_finish_plug(&plug);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000653}
654
655/*
656 * Wait until any activity on the buffer finishes. Possibly write the
657 * buffer if it is dirty. When this function finishes, there is no I/O
658 * running on the buffer and the buffer is not dirty.
659 */
660static void __make_buffer_clean(struct dm_buffer *b)
661{
662 BUG_ON(b->hold_count);
663
664 if (!b->state) /* fast case */
665 return;
666
NeilBrown74316202014-07-07 15:16:04 +1000667 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka24809452013-07-10 23:41:18 +0100668 __write_dirty_buffer(b, NULL);
NeilBrown74316202014-07-07 15:16:04 +1000669 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000670}
671
672/*
673 * Find some buffer that is not held by anybody, clean it, unlink it and
674 * return it.
675 */
676static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
677{
678 struct dm_buffer *b;
679
680 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
681 BUG_ON(test_bit(B_WRITING, &b->state));
682 BUG_ON(test_bit(B_DIRTY, &b->state));
683
684 if (!b->hold_count) {
685 __make_buffer_clean(b);
686 __unlink_buffer(b);
687 return b;
688 }
689 dm_bufio_cond_resched();
690 }
691
692 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
693 BUG_ON(test_bit(B_READING, &b->state));
694
695 if (!b->hold_count) {
696 __make_buffer_clean(b);
697 __unlink_buffer(b);
698 return b;
699 }
700 dm_bufio_cond_resched();
701 }
702
703 return NULL;
704}
705
706/*
707 * Wait until some other threads free some buffer or release hold count on
708 * some buffer.
709 *
710 * This function is entered with c->lock held, drops it and regains it
711 * before exiting.
712 */
713static void __wait_for_free_buffer(struct dm_bufio_client *c)
714{
715 DECLARE_WAITQUEUE(wait, current);
716
717 add_wait_queue(&c->free_buffer_wait, &wait);
718 set_task_state(current, TASK_UNINTERRUPTIBLE);
719 dm_bufio_unlock(c);
720
721 io_schedule();
722
723 set_task_state(current, TASK_RUNNING);
724 remove_wait_queue(&c->free_buffer_wait, &wait);
725
726 dm_bufio_lock(c);
727}
728
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100729enum new_flag {
730 NF_FRESH = 0,
731 NF_READ = 1,
732 NF_GET = 2,
733 NF_PREFETCH = 3
734};
735
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000736/*
737 * Allocate a new buffer. If the allocation is not possible, wait until
738 * some other thread frees a buffer.
739 *
740 * May drop the lock and regain it.
741 */
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100742static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000743{
744 struct dm_buffer *b;
745
746 /*
747 * dm-bufio is resistant to allocation failures (it just keeps
748 * one buffer reserved in cases all the allocations fail).
749 * So set flags to not try too hard:
750 * GFP_NOIO: don't recurse into the I/O layer
751 * __GFP_NORETRY: don't retry and rather return failure
752 * __GFP_NOMEMALLOC: don't use emergency reserves
753 * __GFP_NOWARN: don't print a warning in case of failure
754 *
755 * For debugging, if we set the cache size to 1, no new buffers will
756 * be allocated.
757 */
758 while (1) {
759 if (dm_bufio_cache_size_latch != 1) {
760 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
761 if (b)
762 return b;
763 }
764
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100765 if (nf == NF_PREFETCH)
766 return NULL;
767
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000768 if (!list_empty(&c->reserved_buffers)) {
769 b = list_entry(c->reserved_buffers.next,
770 struct dm_buffer, lru_list);
771 list_del(&b->lru_list);
772 c->need_reserved_buffers++;
773
774 return b;
775 }
776
777 b = __get_unclaimed_buffer(c);
778 if (b)
779 return b;
780
781 __wait_for_free_buffer(c);
782 }
783}
784
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100785static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000786{
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100787 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
788
789 if (!b)
790 return NULL;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000791
792 if (c->alloc_callback)
793 c->alloc_callback(b);
794
795 return b;
796}
797
798/*
799 * Free a buffer and wake other threads waiting for free buffers.
800 */
801static void __free_buffer_wake(struct dm_buffer *b)
802{
803 struct dm_bufio_client *c = b->c;
804
805 if (!c->need_reserved_buffers)
806 free_buffer(b);
807 else {
808 list_add(&b->lru_list, &c->reserved_buffers);
809 c->need_reserved_buffers--;
810 }
811
812 wake_up(&c->free_buffer_wait);
813}
814
Mikulas Patocka24809452013-07-10 23:41:18 +0100815static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
816 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000817{
818 struct dm_buffer *b, *tmp;
819
820 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
821 BUG_ON(test_bit(B_READING, &b->state));
822
823 if (!test_bit(B_DIRTY, &b->state) &&
824 !test_bit(B_WRITING, &b->state)) {
825 __relink_lru(b, LIST_CLEAN);
826 continue;
827 }
828
829 if (no_wait && test_bit(B_WRITING, &b->state))
830 return;
831
Mikulas Patocka24809452013-07-10 23:41:18 +0100832 __write_dirty_buffer(b, write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000833 dm_bufio_cond_resched();
834 }
835}
836
837/*
838 * Get writeback threshold and buffer limit for a given client.
839 */
840static void __get_memory_limit(struct dm_bufio_client *c,
841 unsigned long *threshold_buffers,
842 unsigned long *limit_buffers)
843{
844 unsigned long buffers;
845
Mikulas Patockafe5fe902012-10-12 16:59:46 +0100846 if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000847 mutex_lock(&dm_bufio_clients_lock);
848 __cache_size_refresh();
849 mutex_unlock(&dm_bufio_clients_lock);
850 }
851
852 buffers = dm_bufio_cache_size_per_client >>
853 (c->sectors_per_block_bits + SECTOR_SHIFT);
854
Mikulas Patocka55b082e2014-01-13 19:13:05 -0500855 if (buffers < c->minimum_buffers)
856 buffers = c->minimum_buffers;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000857
858 *limit_buffers = buffers;
859 *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
860}
861
862/*
863 * Check if we're over watermark.
864 * If we are over threshold_buffers, start freeing buffers.
865 * If we're over "limit_buffers", block until we get under the limit.
866 */
Mikulas Patocka24809452013-07-10 23:41:18 +0100867static void __check_watermark(struct dm_bufio_client *c,
868 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000869{
870 unsigned long threshold_buffers, limit_buffers;
871
872 __get_memory_limit(c, &threshold_buffers, &limit_buffers);
873
874 while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] >
875 limit_buffers) {
876
877 struct dm_buffer *b = __get_unclaimed_buffer(c);
878
879 if (!b)
880 return;
881
882 __free_buffer_wake(b);
883 dm_bufio_cond_resched();
884 }
885
886 if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
Mikulas Patocka24809452013-07-10 23:41:18 +0100887 __write_dirty_buffers_async(c, 1, write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000888}
889
890/*
891 * Find a buffer in the hash.
892 */
893static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
894{
895 struct dm_buffer *b;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000896
Sasha Levinb67bfe02013-02-27 17:06:00 -0800897 hlist_for_each_entry(b, &c->cache_hash[DM_BUFIO_HASH(block)],
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000898 hash_list) {
899 dm_bufio_cond_resched();
900 if (b->block == block)
901 return b;
902 }
903
904 return NULL;
905}
906
907/*----------------------------------------------------------------
908 * Getting a buffer
909 *--------------------------------------------------------------*/
910
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000911static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
Mikulas Patocka24809452013-07-10 23:41:18 +0100912 enum new_flag nf, int *need_submit,
913 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000914{
915 struct dm_buffer *b, *new_b = NULL;
916
917 *need_submit = 0;
918
919 b = __find(c, block);
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100920 if (b)
921 goto found_buffer;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000922
923 if (nf == NF_GET)
924 return NULL;
925
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100926 new_b = __alloc_buffer_wait(c, nf);
927 if (!new_b)
928 return NULL;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000929
930 /*
931 * We've had a period where the mutex was unlocked, so need to
932 * recheck the hash table.
933 */
934 b = __find(c, block);
935 if (b) {
936 __free_buffer_wake(new_b);
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100937 goto found_buffer;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000938 }
939
Mikulas Patocka24809452013-07-10 23:41:18 +0100940 __check_watermark(c, write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000941
942 b = new_b;
943 b->hold_count = 1;
944 b->read_error = 0;
945 b->write_error = 0;
946 __link_buffer(b, block, LIST_CLEAN);
947
948 if (nf == NF_FRESH) {
949 b->state = 0;
950 return b;
951 }
952
953 b->state = 1 << B_READING;
954 *need_submit = 1;
955
956 return b;
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100957
958found_buffer:
959 if (nf == NF_PREFETCH)
960 return NULL;
961 /*
962 * Note: it is essential that we don't wait for the buffer to be
963 * read if dm_bufio_get function is used. Both dm_bufio_get and
964 * dm_bufio_prefetch can be used in the driver request routine.
965 * If the user called both dm_bufio_prefetch and dm_bufio_get on
966 * the same buffer, it would deadlock if we waited.
967 */
968 if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state)))
969 return NULL;
970
971 b->hold_count++;
972 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
973 test_bit(B_WRITING, &b->state));
974 return b;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000975}
976
977/*
978 * The endio routine for reading: set the error, clear the bit and wake up
979 * anyone waiting on the buffer.
980 */
981static void read_endio(struct bio *bio, int error)
982{
983 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
984
985 b->read_error = error;
986
987 BUG_ON(!test_bit(B_READING, &b->state));
988
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100989 smp_mb__before_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000990 clear_bit(B_READING, &b->state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100991 smp_mb__after_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000992
993 wake_up_bit(&b->state, B_READING);
994}
995
996/*
997 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
998 * functions is similar except that dm_bufio_new doesn't read the
999 * buffer from the disk (assuming that the caller overwrites all the data
1000 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1001 */
1002static void *new_read(struct dm_bufio_client *c, sector_t block,
1003 enum new_flag nf, struct dm_buffer **bp)
1004{
1005 int need_submit;
1006 struct dm_buffer *b;
1007
Mikulas Patocka24809452013-07-10 23:41:18 +01001008 LIST_HEAD(write_list);
1009
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001010 dm_bufio_lock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001011 b = __bufio_new(c, block, nf, &need_submit, &write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001012 dm_bufio_unlock(c);
1013
Mikulas Patocka24809452013-07-10 23:41:18 +01001014 __flush_write_list(&write_list);
1015
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001016 if (!b)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001017 return b;
1018
1019 if (need_submit)
1020 submit_io(b, READ, b->block, read_endio);
1021
NeilBrown74316202014-07-07 15:16:04 +10001022 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001023
1024 if (b->read_error) {
1025 int error = b->read_error;
1026
1027 dm_bufio_release(b);
1028
1029 return ERR_PTR(error);
1030 }
1031
1032 *bp = b;
1033
1034 return b->data;
1035}
1036
1037void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1038 struct dm_buffer **bp)
1039{
1040 return new_read(c, block, NF_GET, bp);
1041}
1042EXPORT_SYMBOL_GPL(dm_bufio_get);
1043
1044void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1045 struct dm_buffer **bp)
1046{
1047 BUG_ON(dm_bufio_in_request());
1048
1049 return new_read(c, block, NF_READ, bp);
1050}
1051EXPORT_SYMBOL_GPL(dm_bufio_read);
1052
1053void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1054 struct dm_buffer **bp)
1055{
1056 BUG_ON(dm_bufio_in_request());
1057
1058 return new_read(c, block, NF_FRESH, bp);
1059}
1060EXPORT_SYMBOL_GPL(dm_bufio_new);
1061
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001062void dm_bufio_prefetch(struct dm_bufio_client *c,
1063 sector_t block, unsigned n_blocks)
1064{
1065 struct blk_plug plug;
1066
Mikulas Patocka24809452013-07-10 23:41:18 +01001067 LIST_HEAD(write_list);
1068
Mikulas Patocka3b6b7812013-03-20 17:21:25 +00001069 BUG_ON(dm_bufio_in_request());
1070
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001071 blk_start_plug(&plug);
1072 dm_bufio_lock(c);
1073
1074 for (; n_blocks--; block++) {
1075 int need_submit;
1076 struct dm_buffer *b;
Mikulas Patocka24809452013-07-10 23:41:18 +01001077 b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
1078 &write_list);
1079 if (unlikely(!list_empty(&write_list))) {
1080 dm_bufio_unlock(c);
1081 blk_finish_plug(&plug);
1082 __flush_write_list(&write_list);
1083 blk_start_plug(&plug);
1084 dm_bufio_lock(c);
1085 }
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001086 if (unlikely(b != NULL)) {
1087 dm_bufio_unlock(c);
1088
1089 if (need_submit)
1090 submit_io(b, READ, b->block, read_endio);
1091 dm_bufio_release(b);
1092
1093 dm_bufio_cond_resched();
1094
1095 if (!n_blocks)
1096 goto flush_plug;
1097 dm_bufio_lock(c);
1098 }
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001099 }
1100
1101 dm_bufio_unlock(c);
1102
1103flush_plug:
1104 blk_finish_plug(&plug);
1105}
1106EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1107
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001108void dm_bufio_release(struct dm_buffer *b)
1109{
1110 struct dm_bufio_client *c = b->c;
1111
1112 dm_bufio_lock(c);
1113
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001114 BUG_ON(!b->hold_count);
1115
1116 b->hold_count--;
1117 if (!b->hold_count) {
1118 wake_up(&c->free_buffer_wait);
1119
1120 /*
1121 * If there were errors on the buffer, and the buffer is not
1122 * to be written, free the buffer. There is no point in caching
1123 * invalid buffer.
1124 */
1125 if ((b->read_error || b->write_error) &&
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001126 !test_bit(B_READING, &b->state) &&
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001127 !test_bit(B_WRITING, &b->state) &&
1128 !test_bit(B_DIRTY, &b->state)) {
1129 __unlink_buffer(b);
1130 __free_buffer_wake(b);
1131 }
1132 }
1133
1134 dm_bufio_unlock(c);
1135}
1136EXPORT_SYMBOL_GPL(dm_bufio_release);
1137
1138void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1139{
1140 struct dm_bufio_client *c = b->c;
1141
1142 dm_bufio_lock(c);
1143
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001144 BUG_ON(test_bit(B_READING, &b->state));
1145
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001146 if (!test_and_set_bit(B_DIRTY, &b->state))
1147 __relink_lru(b, LIST_DIRTY);
1148
1149 dm_bufio_unlock(c);
1150}
1151EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1152
1153void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1154{
Mikulas Patocka24809452013-07-10 23:41:18 +01001155 LIST_HEAD(write_list);
1156
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001157 BUG_ON(dm_bufio_in_request());
1158
1159 dm_bufio_lock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001160 __write_dirty_buffers_async(c, 0, &write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001161 dm_bufio_unlock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001162 __flush_write_list(&write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001163}
1164EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1165
1166/*
1167 * For performance, it is essential that the buffers are written asynchronously
1168 * and simultaneously (so that the block layer can merge the writes) and then
1169 * waited upon.
1170 *
1171 * Finally, we flush hardware disk cache.
1172 */
1173int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1174{
1175 int a, f;
1176 unsigned long buffers_processed = 0;
1177 struct dm_buffer *b, *tmp;
1178
Mikulas Patocka24809452013-07-10 23:41:18 +01001179 LIST_HEAD(write_list);
1180
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001181 dm_bufio_lock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001182 __write_dirty_buffers_async(c, 0, &write_list);
1183 dm_bufio_unlock(c);
1184 __flush_write_list(&write_list);
1185 dm_bufio_lock(c);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001186
1187again:
1188 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1189 int dropped_lock = 0;
1190
1191 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1192 buffers_processed++;
1193
1194 BUG_ON(test_bit(B_READING, &b->state));
1195
1196 if (test_bit(B_WRITING, &b->state)) {
1197 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1198 dropped_lock = 1;
1199 b->hold_count++;
1200 dm_bufio_unlock(c);
NeilBrown74316202014-07-07 15:16:04 +10001201 wait_on_bit_io(&b->state, B_WRITING,
1202 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001203 dm_bufio_lock(c);
1204 b->hold_count--;
1205 } else
NeilBrown74316202014-07-07 15:16:04 +10001206 wait_on_bit_io(&b->state, B_WRITING,
1207 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001208 }
1209
1210 if (!test_bit(B_DIRTY, &b->state) &&
1211 !test_bit(B_WRITING, &b->state))
1212 __relink_lru(b, LIST_CLEAN);
1213
1214 dm_bufio_cond_resched();
1215
1216 /*
1217 * If we dropped the lock, the list is no longer consistent,
1218 * so we must restart the search.
1219 *
1220 * In the most common case, the buffer just processed is
1221 * relinked to the clean list, so we won't loop scanning the
1222 * same buffer again and again.
1223 *
1224 * This may livelock if there is another thread simultaneously
1225 * dirtying buffers, so we count the number of buffers walked
1226 * and if it exceeds the total number of buffers, it means that
1227 * someone is doing some writes simultaneously with us. In
1228 * this case, stop, dropping the lock.
1229 */
1230 if (dropped_lock)
1231 goto again;
1232 }
1233 wake_up(&c->free_buffer_wait);
1234 dm_bufio_unlock(c);
1235
1236 a = xchg(&c->async_write_error, 0);
1237 f = dm_bufio_issue_flush(c);
1238 if (a)
1239 return a;
1240
1241 return f;
1242}
1243EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1244
1245/*
1246 * Use dm-io to send and empty barrier flush the device.
1247 */
1248int dm_bufio_issue_flush(struct dm_bufio_client *c)
1249{
1250 struct dm_io_request io_req = {
Mikulas Patocka3daec3b2013-03-01 22:45:45 +00001251 .bi_rw = WRITE_FLUSH,
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001252 .mem.type = DM_IO_KMEM,
1253 .mem.ptr.addr = NULL,
1254 .client = c->dm_io,
1255 };
1256 struct dm_io_region io_reg = {
1257 .bdev = c->bdev,
1258 .sector = 0,
1259 .count = 0,
1260 };
1261
1262 BUG_ON(dm_bufio_in_request());
1263
1264 return dm_io(&io_req, 1, &io_reg, NULL);
1265}
1266EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1267
1268/*
1269 * We first delete any other buffer that may be at that new location.
1270 *
1271 * Then, we write the buffer to the original location if it was dirty.
1272 *
1273 * Then, if we are the only one who is holding the buffer, relink the buffer
1274 * in the hash queue for the new location.
1275 *
1276 * If there was someone else holding the buffer, we write it to the new
1277 * location but not relink it, because that other user needs to have the buffer
1278 * at the same place.
1279 */
1280void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1281{
1282 struct dm_bufio_client *c = b->c;
1283 struct dm_buffer *new;
1284
1285 BUG_ON(dm_bufio_in_request());
1286
1287 dm_bufio_lock(c);
1288
1289retry:
1290 new = __find(c, new_block);
1291 if (new) {
1292 if (new->hold_count) {
1293 __wait_for_free_buffer(c);
1294 goto retry;
1295 }
1296
1297 /*
1298 * FIXME: Is there any point waiting for a write that's going
1299 * to be overwritten in a bit?
1300 */
1301 __make_buffer_clean(new);
1302 __unlink_buffer(new);
1303 __free_buffer_wake(new);
1304 }
1305
1306 BUG_ON(!b->hold_count);
1307 BUG_ON(test_bit(B_READING, &b->state));
1308
Mikulas Patocka24809452013-07-10 23:41:18 +01001309 __write_dirty_buffer(b, NULL);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001310 if (b->hold_count == 1) {
NeilBrown74316202014-07-07 15:16:04 +10001311 wait_on_bit_io(&b->state, B_WRITING,
1312 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001313 set_bit(B_DIRTY, &b->state);
1314 __unlink_buffer(b);
1315 __link_buffer(b, new_block, LIST_DIRTY);
1316 } else {
1317 sector_t old_block;
NeilBrown74316202014-07-07 15:16:04 +10001318 wait_on_bit_lock_io(&b->state, B_WRITING,
1319 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001320 /*
1321 * Relink buffer to "new_block" so that write_callback
1322 * sees "new_block" as a block number.
1323 * After the write, link the buffer back to old_block.
1324 * All this must be done in bufio lock, so that block number
1325 * change isn't visible to other threads.
1326 */
1327 old_block = b->block;
1328 __unlink_buffer(b);
1329 __link_buffer(b, new_block, b->list_mode);
1330 submit_io(b, WRITE, new_block, write_endio);
NeilBrown74316202014-07-07 15:16:04 +10001331 wait_on_bit_io(&b->state, B_WRITING,
1332 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001333 __unlink_buffer(b);
1334 __link_buffer(b, old_block, b->list_mode);
1335 }
1336
1337 dm_bufio_unlock(c);
1338 dm_bufio_release(b);
1339}
1340EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1341
Mikulas Patocka55494bf2014-01-13 19:12:36 -05001342/*
1343 * Free the given buffer.
1344 *
1345 * This is just a hint, if the buffer is in use or dirty, this function
1346 * does nothing.
1347 */
1348void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
1349{
1350 struct dm_buffer *b;
1351
1352 dm_bufio_lock(c);
1353
1354 b = __find(c, block);
1355 if (b && likely(!b->hold_count) && likely(!b->state)) {
1356 __unlink_buffer(b);
1357 __free_buffer_wake(b);
1358 }
1359
1360 dm_bufio_unlock(c);
1361}
1362EXPORT_SYMBOL(dm_bufio_forget);
1363
Mikulas Patocka55b082e2014-01-13 19:13:05 -05001364void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
1365{
1366 c->minimum_buffers = n;
1367}
1368EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
1369
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001370unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1371{
1372 return c->block_size;
1373}
1374EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1375
1376sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1377{
1378 return i_size_read(c->bdev->bd_inode) >>
1379 (SECTOR_SHIFT + c->sectors_per_block_bits);
1380}
1381EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1382
1383sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1384{
1385 return b->block;
1386}
1387EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1388
1389void *dm_bufio_get_block_data(struct dm_buffer *b)
1390{
1391 return b->data;
1392}
1393EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1394
1395void *dm_bufio_get_aux_data(struct dm_buffer *b)
1396{
1397 return b + 1;
1398}
1399EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1400
1401struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1402{
1403 return b->c;
1404}
1405EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1406
1407static void drop_buffers(struct dm_bufio_client *c)
1408{
1409 struct dm_buffer *b;
1410 int i;
1411
1412 BUG_ON(dm_bufio_in_request());
1413
1414 /*
1415 * An optimization so that the buffers are not written one-by-one.
1416 */
1417 dm_bufio_write_dirty_buffers_async(c);
1418
1419 dm_bufio_lock(c);
1420
1421 while ((b = __get_unclaimed_buffer(c)))
1422 __free_buffer_wake(b);
1423
1424 for (i = 0; i < LIST_SIZE; i++)
1425 list_for_each_entry(b, &c->lru[i], lru_list)
1426 DMERR("leaked buffer %llx, hold count %u, list %d",
1427 (unsigned long long)b->block, b->hold_count, i);
1428
1429 for (i = 0; i < LIST_SIZE; i++)
1430 BUG_ON(!list_empty(&c->lru[i]));
1431
1432 dm_bufio_unlock(c);
1433}
1434
1435/*
1436 * Test if the buffer is unused and too old, and commit it.
1437 * At if noio is set, we must not do any I/O because we hold
1438 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets rerouted to
1439 * different bufio client.
1440 */
1441static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp,
1442 unsigned long max_jiffies)
1443{
1444 if (jiffies - b->last_accessed < max_jiffies)
Dave Chinner7dc19d52013-08-28 10:18:11 +10001445 return 0;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001446
1447 if (!(gfp & __GFP_IO)) {
1448 if (test_bit(B_READING, &b->state) ||
1449 test_bit(B_WRITING, &b->state) ||
1450 test_bit(B_DIRTY, &b->state))
Dave Chinner7dc19d52013-08-28 10:18:11 +10001451 return 0;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001452 }
1453
1454 if (b->hold_count)
Dave Chinner7dc19d52013-08-28 10:18:11 +10001455 return 0;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001456
1457 __make_buffer_clean(b);
1458 __unlink_buffer(b);
1459 __free_buffer_wake(b);
1460
Dave Chinner7dc19d52013-08-28 10:18:11 +10001461 return 1;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001462}
1463
Dave Chinner7dc19d52013-08-28 10:18:11 +10001464static long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
1465 gfp_t gfp_mask)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001466{
1467 int l;
1468 struct dm_buffer *b, *tmp;
Dave Chinner7dc19d52013-08-28 10:18:11 +10001469 long freed = 0;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001470
1471 for (l = 0; l < LIST_SIZE; l++) {
Dave Chinner7dc19d52013-08-28 10:18:11 +10001472 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
1473 freed += __cleanup_old_buffer(b, gfp_mask, 0);
1474 if (!--nr_to_scan)
1475 break;
1476 }
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001477 dm_bufio_cond_resched();
1478 }
Dave Chinner7dc19d52013-08-28 10:18:11 +10001479 return freed;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001480}
1481
Dave Chinner7dc19d52013-08-28 10:18:11 +10001482static unsigned long
1483dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001484{
Dave Chinner7dc19d52013-08-28 10:18:11 +10001485 struct dm_bufio_client *c;
1486 unsigned long freed;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001487
Dave Chinner7dc19d52013-08-28 10:18:11 +10001488 c = container_of(shrink, struct dm_bufio_client, shrinker);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001489 if (sc->gfp_mask & __GFP_IO)
1490 dm_bufio_lock(c);
1491 else if (!dm_bufio_trylock(c))
Dave Chinner7dc19d52013-08-28 10:18:11 +10001492 return SHRINK_STOP;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001493
Dave Chinner7dc19d52013-08-28 10:18:11 +10001494 freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001495 dm_bufio_unlock(c);
Dave Chinner7dc19d52013-08-28 10:18:11 +10001496 return freed;
1497}
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001498
Dave Chinner7dc19d52013-08-28 10:18:11 +10001499static unsigned long
1500dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1501{
1502 struct dm_bufio_client *c;
1503 unsigned long count;
1504
1505 c = container_of(shrink, struct dm_bufio_client, shrinker);
1506 if (sc->gfp_mask & __GFP_IO)
1507 dm_bufio_lock(c);
1508 else if (!dm_bufio_trylock(c))
1509 return 0;
1510
1511 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1512 dm_bufio_unlock(c);
1513 return count;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001514}
1515
1516/*
1517 * Create the buffering interface
1518 */
1519struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1520 unsigned reserved_buffers, unsigned aux_size,
1521 void (*alloc_callback)(struct dm_buffer *),
1522 void (*write_callback)(struct dm_buffer *))
1523{
1524 int r;
1525 struct dm_bufio_client *c;
1526 unsigned i;
1527
1528 BUG_ON(block_size < 1 << SECTOR_SHIFT ||
1529 (block_size & (block_size - 1)));
1530
Greg Thelend8c712e2014-07-31 09:07:19 -07001531 c = kzalloc(sizeof(*c), GFP_KERNEL);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001532 if (!c) {
1533 r = -ENOMEM;
1534 goto bad_client;
1535 }
1536 c->cache_hash = vmalloc(sizeof(struct hlist_head) << DM_BUFIO_HASH_BITS);
1537 if (!c->cache_hash) {
1538 r = -ENOMEM;
1539 goto bad_hash;
1540 }
1541
1542 c->bdev = bdev;
1543 c->block_size = block_size;
1544 c->sectors_per_block_bits = ffs(block_size) - 1 - SECTOR_SHIFT;
1545 c->pages_per_block_bits = (ffs(block_size) - 1 >= PAGE_SHIFT) ?
1546 ffs(block_size) - 1 - PAGE_SHIFT : 0;
1547 c->blocks_per_page_bits = (ffs(block_size) - 1 < PAGE_SHIFT ?
1548 PAGE_SHIFT - (ffs(block_size) - 1) : 0);
1549
1550 c->aux_size = aux_size;
1551 c->alloc_callback = alloc_callback;
1552 c->write_callback = write_callback;
1553
1554 for (i = 0; i < LIST_SIZE; i++) {
1555 INIT_LIST_HEAD(&c->lru[i]);
1556 c->n_buffers[i] = 0;
1557 }
1558
1559 for (i = 0; i < 1 << DM_BUFIO_HASH_BITS; i++)
1560 INIT_HLIST_HEAD(&c->cache_hash[i]);
1561
1562 mutex_init(&c->lock);
1563 INIT_LIST_HEAD(&c->reserved_buffers);
1564 c->need_reserved_buffers = reserved_buffers;
1565
Mikulas Patocka55b082e2014-01-13 19:13:05 -05001566 c->minimum_buffers = DM_BUFIO_MIN_BUFFERS;
1567
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001568 init_waitqueue_head(&c->free_buffer_wait);
1569 c->async_write_error = 0;
1570
1571 c->dm_io = dm_io_client_create();
1572 if (IS_ERR(c->dm_io)) {
1573 r = PTR_ERR(c->dm_io);
1574 goto bad_dm_io;
1575 }
1576
1577 mutex_lock(&dm_bufio_clients_lock);
1578 if (c->blocks_per_page_bits) {
1579 if (!DM_BUFIO_CACHE_NAME(c)) {
1580 DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
1581 if (!DM_BUFIO_CACHE_NAME(c)) {
1582 r = -ENOMEM;
1583 mutex_unlock(&dm_bufio_clients_lock);
1584 goto bad_cache;
1585 }
1586 }
1587
1588 if (!DM_BUFIO_CACHE(c)) {
1589 DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
1590 c->block_size,
1591 c->block_size, 0, NULL);
1592 if (!DM_BUFIO_CACHE(c)) {
1593 r = -ENOMEM;
1594 mutex_unlock(&dm_bufio_clients_lock);
1595 goto bad_cache;
1596 }
1597 }
1598 }
1599 mutex_unlock(&dm_bufio_clients_lock);
1600
1601 while (c->need_reserved_buffers) {
1602 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1603
1604 if (!b) {
1605 r = -ENOMEM;
1606 goto bad_buffer;
1607 }
1608 __free_buffer_wake(b);
1609 }
1610
1611 mutex_lock(&dm_bufio_clients_lock);
1612 dm_bufio_client_count++;
1613 list_add(&c->client_list, &dm_bufio_all_clients);
1614 __cache_size_refresh();
1615 mutex_unlock(&dm_bufio_clients_lock);
1616
Dave Chinner7dc19d52013-08-28 10:18:11 +10001617 c->shrinker.count_objects = dm_bufio_shrink_count;
1618 c->shrinker.scan_objects = dm_bufio_shrink_scan;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001619 c->shrinker.seeks = 1;
1620 c->shrinker.batch = 0;
1621 register_shrinker(&c->shrinker);
1622
1623 return c;
1624
1625bad_buffer:
1626bad_cache:
1627 while (!list_empty(&c->reserved_buffers)) {
1628 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1629 struct dm_buffer, lru_list);
1630 list_del(&b->lru_list);
1631 free_buffer(b);
1632 }
1633 dm_io_client_destroy(c->dm_io);
1634bad_dm_io:
1635 vfree(c->cache_hash);
1636bad_hash:
1637 kfree(c);
1638bad_client:
1639 return ERR_PTR(r);
1640}
1641EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1642
1643/*
1644 * Free the buffering interface.
1645 * It is required that there are no references on any buffers.
1646 */
1647void dm_bufio_client_destroy(struct dm_bufio_client *c)
1648{
1649 unsigned i;
1650
1651 drop_buffers(c);
1652
1653 unregister_shrinker(&c->shrinker);
1654
1655 mutex_lock(&dm_bufio_clients_lock);
1656
1657 list_del(&c->client_list);
1658 dm_bufio_client_count--;
1659 __cache_size_refresh();
1660
1661 mutex_unlock(&dm_bufio_clients_lock);
1662
1663 for (i = 0; i < 1 << DM_BUFIO_HASH_BITS; i++)
1664 BUG_ON(!hlist_empty(&c->cache_hash[i]));
1665
1666 BUG_ON(c->need_reserved_buffers);
1667
1668 while (!list_empty(&c->reserved_buffers)) {
1669 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1670 struct dm_buffer, lru_list);
1671 list_del(&b->lru_list);
1672 free_buffer(b);
1673 }
1674
1675 for (i = 0; i < LIST_SIZE; i++)
1676 if (c->n_buffers[i])
1677 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1678
1679 for (i = 0; i < LIST_SIZE; i++)
1680 BUG_ON(c->n_buffers[i]);
1681
1682 dm_io_client_destroy(c->dm_io);
1683 vfree(c->cache_hash);
1684 kfree(c);
1685}
1686EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1687
1688static void cleanup_old_buffers(void)
1689{
Mikulas Patockafe5fe902012-10-12 16:59:46 +01001690 unsigned long max_age = ACCESS_ONCE(dm_bufio_max_age);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001691 struct dm_bufio_client *c;
1692
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001693 if (max_age > ULONG_MAX / HZ)
1694 max_age = ULONG_MAX / HZ;
1695
1696 mutex_lock(&dm_bufio_clients_lock);
1697 list_for_each_entry(c, &dm_bufio_all_clients, client_list) {
1698 if (!dm_bufio_trylock(c))
1699 continue;
1700
1701 while (!list_empty(&c->lru[LIST_CLEAN])) {
1702 struct dm_buffer *b;
1703 b = list_entry(c->lru[LIST_CLEAN].prev,
1704 struct dm_buffer, lru_list);
Dave Chinner7dc19d52013-08-28 10:18:11 +10001705 if (!__cleanup_old_buffer(b, 0, max_age * HZ))
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001706 break;
1707 dm_bufio_cond_resched();
1708 }
1709
1710 dm_bufio_unlock(c);
1711 dm_bufio_cond_resched();
1712 }
1713 mutex_unlock(&dm_bufio_clients_lock);
1714}
1715
1716static struct workqueue_struct *dm_bufio_wq;
1717static struct delayed_work dm_bufio_work;
1718
1719static void work_fn(struct work_struct *w)
1720{
1721 cleanup_old_buffers();
1722
1723 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1724 DM_BUFIO_WORK_TIMER_SECS * HZ);
1725}
1726
1727/*----------------------------------------------------------------
1728 * Module setup
1729 *--------------------------------------------------------------*/
1730
1731/*
1732 * This is called only once for the whole dm_bufio module.
1733 * It initializes memory limit.
1734 */
1735static int __init dm_bufio_init(void)
1736{
1737 __u64 mem;
1738
Mikulas Patocka4cb57ab2013-12-05 17:33:29 -05001739 dm_bufio_allocated_kmem_cache = 0;
1740 dm_bufio_allocated_get_free_pages = 0;
1741 dm_bufio_allocated_vmalloc = 0;
1742 dm_bufio_current_allocated = 0;
1743
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001744 memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
1745 memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
1746
1747 mem = (__u64)((totalram_pages - totalhigh_pages) *
1748 DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
1749
1750 if (mem > ULONG_MAX)
1751 mem = ULONG_MAX;
1752
1753#ifdef CONFIG_MMU
1754 /*
1755 * Get the size of vmalloc space the same way as VMALLOC_TOTAL
1756 * in fs/proc/internal.h
1757 */
1758 if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
1759 mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100;
1760#endif
1761
1762 dm_bufio_default_cache_size = mem;
1763
1764 mutex_lock(&dm_bufio_clients_lock);
1765 __cache_size_refresh();
1766 mutex_unlock(&dm_bufio_clients_lock);
1767
1768 dm_bufio_wq = create_singlethread_workqueue("dm_bufio_cache");
1769 if (!dm_bufio_wq)
1770 return -ENOMEM;
1771
1772 INIT_DELAYED_WORK(&dm_bufio_work, work_fn);
1773 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1774 DM_BUFIO_WORK_TIMER_SECS * HZ);
1775
1776 return 0;
1777}
1778
1779/*
1780 * This is called once when unloading the dm_bufio module.
1781 */
1782static void __exit dm_bufio_exit(void)
1783{
1784 int bug = 0;
1785 int i;
1786
1787 cancel_delayed_work_sync(&dm_bufio_work);
1788 destroy_workqueue(dm_bufio_wq);
1789
1790 for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) {
1791 struct kmem_cache *kc = dm_bufio_caches[i];
1792
1793 if (kc)
1794 kmem_cache_destroy(kc);
1795 }
1796
1797 for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
1798 kfree(dm_bufio_cache_names[i]);
1799
1800 if (dm_bufio_client_count) {
1801 DMCRIT("%s: dm_bufio_client_count leaked: %d",
1802 __func__, dm_bufio_client_count);
1803 bug = 1;
1804 }
1805
1806 if (dm_bufio_current_allocated) {
1807 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
1808 __func__, dm_bufio_current_allocated);
1809 bug = 1;
1810 }
1811
1812 if (dm_bufio_allocated_get_free_pages) {
1813 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
1814 __func__, dm_bufio_allocated_get_free_pages);
1815 bug = 1;
1816 }
1817
1818 if (dm_bufio_allocated_vmalloc) {
1819 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
1820 __func__, dm_bufio_allocated_vmalloc);
1821 bug = 1;
1822 }
1823
1824 if (bug)
1825 BUG();
1826}
1827
1828module_init(dm_bufio_init)
1829module_exit(dm_bufio_exit)
1830
1831module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
1832MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
1833
1834module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
1835MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
1836
1837module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
1838MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
1839
1840module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
1841MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
1842
1843module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
1844MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
1845
1846module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
1847MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
1848
1849module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
1850MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
1851
1852MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
1853MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
1854MODULE_LICENSE("GPL");