Loading...
Note: File does not exist in v3.1.
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#include <linux/jump_label.h>
22
23#define DM_MSG_PREFIX "bufio"
24
25/*
26 * Memory management policy:
27 * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
28 * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
29 * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
30 * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
31 * dirty buffers.
32 */
33#define DM_BUFIO_MIN_BUFFERS 8
34
35#define DM_BUFIO_MEMORY_PERCENT 2
36#define DM_BUFIO_VMALLOC_PERCENT 25
37#define DM_BUFIO_WRITEBACK_RATIO 3
38#define DM_BUFIO_LOW_WATERMARK_RATIO 16
39
40/*
41 * Check buffer ages in this interval (seconds)
42 */
43#define DM_BUFIO_WORK_TIMER_SECS 30
44
45/*
46 * Free buffers when they are older than this (seconds)
47 */
48#define DM_BUFIO_DEFAULT_AGE_SECS 300
49
50/*
51 * The nr of bytes of cached data to keep around.
52 */
53#define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
54
55/*
56 * Align buffer writes to this boundary.
57 * Tests show that SSDs have the highest IOPS when using 4k writes.
58 */
59#define DM_BUFIO_WRITE_ALIGN 4096
60
61/*
62 * dm_buffer->list_mode
63 */
64#define LIST_CLEAN 0
65#define LIST_DIRTY 1
66#define LIST_SIZE 2
67
68/*
69 * Linking of buffers:
70 * All buffers are linked to buffer_tree with their node field.
71 *
72 * Clean buffers that are not being written (B_WRITING not set)
73 * are linked to lru[LIST_CLEAN] with their lru_list field.
74 *
75 * Dirty and clean buffers that are being written are linked to
76 * lru[LIST_DIRTY] with their lru_list field. When the write
77 * finishes, the buffer cannot be relinked immediately (because we
78 * are in an interrupt context and relinking requires process
79 * context), so some clean-not-writing buffers can be held on
80 * dirty_lru too. They are later added to lru in the process
81 * context.
82 */
83struct dm_bufio_client {
84 struct mutex lock;
85 spinlock_t spinlock;
86 bool no_sleep;
87
88 struct list_head lru[LIST_SIZE];
89 unsigned long n_buffers[LIST_SIZE];
90
91 struct block_device *bdev;
92 unsigned block_size;
93 s8 sectors_per_block_bits;
94 void (*alloc_callback)(struct dm_buffer *);
95 void (*write_callback)(struct dm_buffer *);
96 struct kmem_cache *slab_buffer;
97 struct kmem_cache *slab_cache;
98 struct dm_io_client *dm_io;
99
100 struct list_head reserved_buffers;
101 unsigned need_reserved_buffers;
102
103 unsigned minimum_buffers;
104
105 struct rb_root buffer_tree;
106 wait_queue_head_t free_buffer_wait;
107
108 sector_t start;
109
110 int async_write_error;
111
112 struct list_head client_list;
113
114 struct shrinker shrinker;
115 struct work_struct shrink_work;
116 atomic_long_t need_shrink;
117};
118
119/*
120 * Buffer state bits.
121 */
122#define B_READING 0
123#define B_WRITING 1
124#define B_DIRTY 2
125
126/*
127 * Describes how the block was allocated:
128 * kmem_cache_alloc(), __get_free_pages() or vmalloc().
129 * See the comment at alloc_buffer_data.
130 */
131enum data_mode {
132 DATA_MODE_SLAB = 0,
133 DATA_MODE_GET_FREE_PAGES = 1,
134 DATA_MODE_VMALLOC = 2,
135 DATA_MODE_LIMIT = 3
136};
137
138struct dm_buffer {
139 struct rb_node node;
140 struct list_head lru_list;
141 struct list_head global_list;
142 sector_t block;
143 void *data;
144 unsigned char data_mode; /* DATA_MODE_* */
145 unsigned char list_mode; /* LIST_* */
146 blk_status_t read_error;
147 blk_status_t write_error;
148 unsigned accessed;
149 unsigned hold_count;
150 unsigned long state;
151 unsigned long last_accessed;
152 unsigned dirty_start;
153 unsigned dirty_end;
154 unsigned write_start;
155 unsigned write_end;
156 struct dm_bufio_client *c;
157 struct list_head write_list;
158 void (*end_io)(struct dm_buffer *, blk_status_t);
159#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
160#define MAX_STACK 10
161 unsigned int stack_len;
162 unsigned long stack_entries[MAX_STACK];
163#endif
164};
165
166static DEFINE_STATIC_KEY_FALSE(no_sleep_enabled);
167
168/*----------------------------------------------------------------*/
169
170#define dm_bufio_in_request() (!!current->bio_list)
171
172static void dm_bufio_lock(struct dm_bufio_client *c)
173{
174 if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
175 spin_lock_bh(&c->spinlock);
176 else
177 mutex_lock_nested(&c->lock, dm_bufio_in_request());
178}
179
180static int dm_bufio_trylock(struct dm_bufio_client *c)
181{
182 if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
183 return spin_trylock_bh(&c->spinlock);
184 else
185 return mutex_trylock(&c->lock);
186}
187
188static void dm_bufio_unlock(struct dm_bufio_client *c)
189{
190 if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
191 spin_unlock_bh(&c->spinlock);
192 else
193 mutex_unlock(&c->lock);
194}
195
196/*----------------------------------------------------------------*/
197
198/*
199 * Default cache size: available memory divided by the ratio.
200 */
201static unsigned long dm_bufio_default_cache_size;
202
203/*
204 * Total cache size set by the user.
205 */
206static unsigned long dm_bufio_cache_size;
207
208/*
209 * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
210 * at any time. If it disagrees, the user has changed cache size.
211 */
212static unsigned long dm_bufio_cache_size_latch;
213
214static DEFINE_SPINLOCK(global_spinlock);
215
216static LIST_HEAD(global_queue);
217
218static unsigned long global_num = 0;
219
220/*
221 * Buffers are freed after this timeout
222 */
223static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
224static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
225
226static unsigned long dm_bufio_peak_allocated;
227static unsigned long dm_bufio_allocated_kmem_cache;
228static unsigned long dm_bufio_allocated_get_free_pages;
229static unsigned long dm_bufio_allocated_vmalloc;
230static unsigned long dm_bufio_current_allocated;
231
232/*----------------------------------------------------------------*/
233
234/*
235 * The current number of clients.
236 */
237static int dm_bufio_client_count;
238
239/*
240 * The list of all clients.
241 */
242static LIST_HEAD(dm_bufio_all_clients);
243
244/*
245 * This mutex protects dm_bufio_cache_size_latch and dm_bufio_client_count
246 */
247static DEFINE_MUTEX(dm_bufio_clients_lock);
248
249static struct workqueue_struct *dm_bufio_wq;
250static struct delayed_work dm_bufio_cleanup_old_work;
251static struct work_struct dm_bufio_replacement_work;
252
253
254#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
255static void buffer_record_stack(struct dm_buffer *b)
256{
257 b->stack_len = stack_trace_save(b->stack_entries, MAX_STACK, 2);
258}
259#endif
260
261/*----------------------------------------------------------------
262 * A red/black tree acts as an index for all the buffers.
263 *--------------------------------------------------------------*/
264static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
265{
266 struct rb_node *n = c->buffer_tree.rb_node;
267 struct dm_buffer *b;
268
269 while (n) {
270 b = container_of(n, struct dm_buffer, node);
271
272 if (b->block == block)
273 return b;
274
275 n = block < b->block ? n->rb_left : n->rb_right;
276 }
277
278 return NULL;
279}
280
281static struct dm_buffer *__find_next(struct dm_bufio_client *c, sector_t block)
282{
283 struct rb_node *n = c->buffer_tree.rb_node;
284 struct dm_buffer *b;
285 struct dm_buffer *best = NULL;
286
287 while (n) {
288 b = container_of(n, struct dm_buffer, node);
289
290 if (b->block == block)
291 return b;
292
293 if (block <= b->block) {
294 n = n->rb_left;
295 best = b;
296 } else {
297 n = n->rb_right;
298 }
299 }
300
301 return best;
302}
303
304static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
305{
306 struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
307 struct dm_buffer *found;
308
309 while (*new) {
310 found = container_of(*new, struct dm_buffer, node);
311
312 if (found->block == b->block) {
313 BUG_ON(found != b);
314 return;
315 }
316
317 parent = *new;
318 new = b->block < found->block ?
319 &found->node.rb_left : &found->node.rb_right;
320 }
321
322 rb_link_node(&b->node, parent, new);
323 rb_insert_color(&b->node, &c->buffer_tree);
324}
325
326static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
327{
328 rb_erase(&b->node, &c->buffer_tree);
329}
330
331/*----------------------------------------------------------------*/
332
333static void adjust_total_allocated(struct dm_buffer *b, bool unlink)
334{
335 unsigned char data_mode;
336 long diff;
337
338 static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
339 &dm_bufio_allocated_kmem_cache,
340 &dm_bufio_allocated_get_free_pages,
341 &dm_bufio_allocated_vmalloc,
342 };
343
344 data_mode = b->data_mode;
345 diff = (long)b->c->block_size;
346 if (unlink)
347 diff = -diff;
348
349 spin_lock(&global_spinlock);
350
351 *class_ptr[data_mode] += diff;
352
353 dm_bufio_current_allocated += diff;
354
355 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
356 dm_bufio_peak_allocated = dm_bufio_current_allocated;
357
358 b->accessed = 1;
359
360 if (!unlink) {
361 list_add(&b->global_list, &global_queue);
362 global_num++;
363 if (dm_bufio_current_allocated > dm_bufio_cache_size)
364 queue_work(dm_bufio_wq, &dm_bufio_replacement_work);
365 } else {
366 list_del(&b->global_list);
367 global_num--;
368 }
369
370 spin_unlock(&global_spinlock);
371}
372
373/*
374 * Change the number of clients and recalculate per-client limit.
375 */
376static void __cache_size_refresh(void)
377{
378 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
379 BUG_ON(dm_bufio_client_count < 0);
380
381 dm_bufio_cache_size_latch = READ_ONCE(dm_bufio_cache_size);
382
383 /*
384 * Use default if set to 0 and report the actual cache size used.
385 */
386 if (!dm_bufio_cache_size_latch) {
387 (void)cmpxchg(&dm_bufio_cache_size, 0,
388 dm_bufio_default_cache_size);
389 dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
390 }
391}
392
393/*
394 * Allocating buffer data.
395 *
396 * Small buffers are allocated with kmem_cache, to use space optimally.
397 *
398 * For large buffers, we choose between get_free_pages and vmalloc.
399 * Each has advantages and disadvantages.
400 *
401 * __get_free_pages can randomly fail if the memory is fragmented.
402 * __vmalloc won't randomly fail, but vmalloc space is limited (it may be
403 * as low as 128M) so using it for caching is not appropriate.
404 *
405 * If the allocation may fail we use __get_free_pages. Memory fragmentation
406 * won't have a fatal effect here, but it just causes flushes of some other
407 * buffers and more I/O will be performed. Don't use __get_free_pages if it
408 * always fails (i.e. order >= MAX_ORDER).
409 *
410 * If the allocation shouldn't fail we use __vmalloc. This is only for the
411 * initial reserve allocation, so there's no risk of wasting all vmalloc
412 * space.
413 */
414static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
415 unsigned char *data_mode)
416{
417 if (unlikely(c->slab_cache != NULL)) {
418 *data_mode = DATA_MODE_SLAB;
419 return kmem_cache_alloc(c->slab_cache, gfp_mask);
420 }
421
422 if (c->block_size <= KMALLOC_MAX_SIZE &&
423 gfp_mask & __GFP_NORETRY) {
424 *data_mode = DATA_MODE_GET_FREE_PAGES;
425 return (void *)__get_free_pages(gfp_mask,
426 c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
427 }
428
429 *data_mode = DATA_MODE_VMALLOC;
430
431 /*
432 * __vmalloc allocates the data pages and auxiliary structures with
433 * gfp_flags that were specified, but pagetables are always allocated
434 * with GFP_KERNEL, no matter what was specified as gfp_mask.
435 *
436 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
437 * all allocations done by this process (including pagetables) are done
438 * as if GFP_NOIO was specified.
439 */
440 if (gfp_mask & __GFP_NORETRY) {
441 unsigned noio_flag = memalloc_noio_save();
442 void *ptr = __vmalloc(c->block_size, gfp_mask);
443
444 memalloc_noio_restore(noio_flag);
445 return ptr;
446 }
447
448 return __vmalloc(c->block_size, gfp_mask);
449}
450
451/*
452 * Free buffer's data.
453 */
454static void free_buffer_data(struct dm_bufio_client *c,
455 void *data, unsigned char data_mode)
456{
457 switch (data_mode) {
458 case DATA_MODE_SLAB:
459 kmem_cache_free(c->slab_cache, data);
460 break;
461
462 case DATA_MODE_GET_FREE_PAGES:
463 free_pages((unsigned long)data,
464 c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
465 break;
466
467 case DATA_MODE_VMALLOC:
468 vfree(data);
469 break;
470
471 default:
472 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
473 data_mode);
474 BUG();
475 }
476}
477
478/*
479 * Allocate buffer and its data.
480 */
481static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
482{
483 struct dm_buffer *b = kmem_cache_alloc(c->slab_buffer, gfp_mask);
484
485 if (!b)
486 return NULL;
487
488 b->c = c;
489
490 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
491 if (!b->data) {
492 kmem_cache_free(c->slab_buffer, b);
493 return NULL;
494 }
495
496#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
497 b->stack_len = 0;
498#endif
499 return b;
500}
501
502/*
503 * Free buffer and its data.
504 */
505static void free_buffer(struct dm_buffer *b)
506{
507 struct dm_bufio_client *c = b->c;
508
509 free_buffer_data(c, b->data, b->data_mode);
510 kmem_cache_free(c->slab_buffer, b);
511}
512
513/*
514 * Link buffer to the buffer tree and clean or dirty queue.
515 */
516static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
517{
518 struct dm_bufio_client *c = b->c;
519
520 c->n_buffers[dirty]++;
521 b->block = block;
522 b->list_mode = dirty;
523 list_add(&b->lru_list, &c->lru[dirty]);
524 __insert(b->c, b);
525 b->last_accessed = jiffies;
526
527 adjust_total_allocated(b, false);
528}
529
530/*
531 * Unlink buffer from the buffer tree and dirty or clean queue.
532 */
533static void __unlink_buffer(struct dm_buffer *b)
534{
535 struct dm_bufio_client *c = b->c;
536
537 BUG_ON(!c->n_buffers[b->list_mode]);
538
539 c->n_buffers[b->list_mode]--;
540 __remove(b->c, b);
541 list_del(&b->lru_list);
542
543 adjust_total_allocated(b, true);
544}
545
546/*
547 * Place the buffer to the head of dirty or clean LRU queue.
548 */
549static void __relink_lru(struct dm_buffer *b, int dirty)
550{
551 struct dm_bufio_client *c = b->c;
552
553 b->accessed = 1;
554
555 BUG_ON(!c->n_buffers[b->list_mode]);
556
557 c->n_buffers[b->list_mode]--;
558 c->n_buffers[dirty]++;
559 b->list_mode = dirty;
560 list_move(&b->lru_list, &c->lru[dirty]);
561 b->last_accessed = jiffies;
562}
563
564/*----------------------------------------------------------------
565 * Submit I/O on the buffer.
566 *
567 * Bio interface is faster but it has some problems:
568 * the vector list is limited (increasing this limit increases
569 * memory-consumption per buffer, so it is not viable);
570 *
571 * the memory must be direct-mapped, not vmalloced;
572 *
573 * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
574 * it is not vmalloced, try using the bio interface.
575 *
576 * If the buffer is big, if it is vmalloced or if the underlying device
577 * rejects the bio because it is too large, use dm-io layer to do the I/O.
578 * The dm-io layer splits the I/O into multiple requests, avoiding the above
579 * shortcomings.
580 *--------------------------------------------------------------*/
581
582/*
583 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
584 * that the request was handled directly with bio interface.
585 */
586static void dmio_complete(unsigned long error, void *context)
587{
588 struct dm_buffer *b = context;
589
590 b->end_io(b, unlikely(error != 0) ? BLK_STS_IOERR : 0);
591}
592
593static void use_dmio(struct dm_buffer *b, enum req_op op, sector_t sector,
594 unsigned n_sectors, unsigned offset)
595{
596 int r;
597 struct dm_io_request io_req = {
598 .bi_opf = op,
599 .notify.fn = dmio_complete,
600 .notify.context = b,
601 .client = b->c->dm_io,
602 };
603 struct dm_io_region region = {
604 .bdev = b->c->bdev,
605 .sector = sector,
606 .count = n_sectors,
607 };
608
609 if (b->data_mode != DATA_MODE_VMALLOC) {
610 io_req.mem.type = DM_IO_KMEM;
611 io_req.mem.ptr.addr = (char *)b->data + offset;
612 } else {
613 io_req.mem.type = DM_IO_VMA;
614 io_req.mem.ptr.vma = (char *)b->data + offset;
615 }
616
617 r = dm_io(&io_req, 1, ®ion, NULL);
618 if (unlikely(r))
619 b->end_io(b, errno_to_blk_status(r));
620}
621
622static void bio_complete(struct bio *bio)
623{
624 struct dm_buffer *b = bio->bi_private;
625 blk_status_t status = bio->bi_status;
626 bio_uninit(bio);
627 kfree(bio);
628 b->end_io(b, status);
629}
630
631static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector,
632 unsigned n_sectors, unsigned offset)
633{
634 struct bio *bio;
635 char *ptr;
636 unsigned vec_size, len;
637
638 vec_size = b->c->block_size >> PAGE_SHIFT;
639 if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT))
640 vec_size += 2;
641
642 bio = bio_kmalloc(vec_size, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN);
643 if (!bio) {
644dmio:
645 use_dmio(b, op, sector, n_sectors, offset);
646 return;
647 }
648 bio_init(bio, b->c->bdev, bio->bi_inline_vecs, vec_size, op);
649 bio->bi_iter.bi_sector = sector;
650 bio->bi_end_io = bio_complete;
651 bio->bi_private = b;
652
653 ptr = (char *)b->data + offset;
654 len = n_sectors << SECTOR_SHIFT;
655
656 do {
657 unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len);
658 if (!bio_add_page(bio, virt_to_page(ptr), this_step,
659 offset_in_page(ptr))) {
660 bio_put(bio);
661 goto dmio;
662 }
663
664 len -= this_step;
665 ptr += this_step;
666 } while (len > 0);
667
668 submit_bio(bio);
669}
670
671static inline sector_t block_to_sector(struct dm_bufio_client *c, sector_t block)
672{
673 sector_t sector;
674
675 if (likely(c->sectors_per_block_bits >= 0))
676 sector = block << c->sectors_per_block_bits;
677 else
678 sector = block * (c->block_size >> SECTOR_SHIFT);
679 sector += c->start;
680
681 return sector;
682}
683
684static void submit_io(struct dm_buffer *b, enum req_op op,
685 void (*end_io)(struct dm_buffer *, blk_status_t))
686{
687 unsigned n_sectors;
688 sector_t sector;
689 unsigned offset, end;
690
691 b->end_io = end_io;
692
693 sector = block_to_sector(b->c, b->block);
694
695 if (op != REQ_OP_WRITE) {
696 n_sectors = b->c->block_size >> SECTOR_SHIFT;
697 offset = 0;
698 } else {
699 if (b->c->write_callback)
700 b->c->write_callback(b);
701 offset = b->write_start;
702 end = b->write_end;
703 offset &= -DM_BUFIO_WRITE_ALIGN;
704 end += DM_BUFIO_WRITE_ALIGN - 1;
705 end &= -DM_BUFIO_WRITE_ALIGN;
706 if (unlikely(end > b->c->block_size))
707 end = b->c->block_size;
708
709 sector += offset >> SECTOR_SHIFT;
710 n_sectors = (end - offset) >> SECTOR_SHIFT;
711 }
712
713 if (b->data_mode != DATA_MODE_VMALLOC)
714 use_bio(b, op, sector, n_sectors, offset);
715 else
716 use_dmio(b, op, sector, n_sectors, offset);
717}
718
719/*----------------------------------------------------------------
720 * Writing dirty buffers
721 *--------------------------------------------------------------*/
722
723/*
724 * The endio routine for write.
725 *
726 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
727 * it.
728 */
729static void write_endio(struct dm_buffer *b, blk_status_t status)
730{
731 b->write_error = status;
732 if (unlikely(status)) {
733 struct dm_bufio_client *c = b->c;
734
735 (void)cmpxchg(&c->async_write_error, 0,
736 blk_status_to_errno(status));
737 }
738
739 BUG_ON(!test_bit(B_WRITING, &b->state));
740
741 smp_mb__before_atomic();
742 clear_bit(B_WRITING, &b->state);
743 smp_mb__after_atomic();
744
745 wake_up_bit(&b->state, B_WRITING);
746}
747
748/*
749 * Initiate a write on a dirty buffer, but don't wait for it.
750 *
751 * - If the buffer is not dirty, exit.
752 * - If there some previous write going on, wait for it to finish (we can't
753 * have two writes on the same buffer simultaneously).
754 * - Submit our write and don't wait on it. We set B_WRITING indicating
755 * that there is a write in progress.
756 */
757static void __write_dirty_buffer(struct dm_buffer *b,
758 struct list_head *write_list)
759{
760 if (!test_bit(B_DIRTY, &b->state))
761 return;
762
763 clear_bit(B_DIRTY, &b->state);
764 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
765
766 b->write_start = b->dirty_start;
767 b->write_end = b->dirty_end;
768
769 if (!write_list)
770 submit_io(b, REQ_OP_WRITE, write_endio);
771 else
772 list_add_tail(&b->write_list, write_list);
773}
774
775static void __flush_write_list(struct list_head *write_list)
776{
777 struct blk_plug plug;
778 blk_start_plug(&plug);
779 while (!list_empty(write_list)) {
780 struct dm_buffer *b =
781 list_entry(write_list->next, struct dm_buffer, write_list);
782 list_del(&b->write_list);
783 submit_io(b, REQ_OP_WRITE, write_endio);
784 cond_resched();
785 }
786 blk_finish_plug(&plug);
787}
788
789/*
790 * Wait until any activity on the buffer finishes. Possibly write the
791 * buffer if it is dirty. When this function finishes, there is no I/O
792 * running on the buffer and the buffer is not dirty.
793 */
794static void __make_buffer_clean(struct dm_buffer *b)
795{
796 BUG_ON(b->hold_count);
797
798 /* smp_load_acquire() pairs with read_endio()'s smp_mb__before_atomic() */
799 if (!smp_load_acquire(&b->state)) /* fast case */
800 return;
801
802 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
803 __write_dirty_buffer(b, NULL);
804 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
805}
806
807/*
808 * Find some buffer that is not held by anybody, clean it, unlink it and
809 * return it.
810 */
811static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
812{
813 struct dm_buffer *b;
814
815 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
816 BUG_ON(test_bit(B_WRITING, &b->state));
817 BUG_ON(test_bit(B_DIRTY, &b->state));
818
819 if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep &&
820 unlikely(test_bit_acquire(B_READING, &b->state)))
821 continue;
822
823 if (!b->hold_count) {
824 __make_buffer_clean(b);
825 __unlink_buffer(b);
826 return b;
827 }
828 cond_resched();
829 }
830
831 if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
832 return NULL;
833
834 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
835 BUG_ON(test_bit(B_READING, &b->state));
836
837 if (!b->hold_count) {
838 __make_buffer_clean(b);
839 __unlink_buffer(b);
840 return b;
841 }
842 cond_resched();
843 }
844
845 return NULL;
846}
847
848/*
849 * Wait until some other threads free some buffer or release hold count on
850 * some buffer.
851 *
852 * This function is entered with c->lock held, drops it and regains it
853 * before exiting.
854 */
855static void __wait_for_free_buffer(struct dm_bufio_client *c)
856{
857 DECLARE_WAITQUEUE(wait, current);
858
859 add_wait_queue(&c->free_buffer_wait, &wait);
860 set_current_state(TASK_UNINTERRUPTIBLE);
861 dm_bufio_unlock(c);
862
863 io_schedule();
864
865 remove_wait_queue(&c->free_buffer_wait, &wait);
866
867 dm_bufio_lock(c);
868}
869
870enum new_flag {
871 NF_FRESH = 0,
872 NF_READ = 1,
873 NF_GET = 2,
874 NF_PREFETCH = 3
875};
876
877/*
878 * Allocate a new buffer. If the allocation is not possible, wait until
879 * some other thread frees a buffer.
880 *
881 * May drop the lock and regain it.
882 */
883static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
884{
885 struct dm_buffer *b;
886 bool tried_noio_alloc = false;
887
888 /*
889 * dm-bufio is resistant to allocation failures (it just keeps
890 * one buffer reserved in cases all the allocations fail).
891 * So set flags to not try too hard:
892 * GFP_NOWAIT: don't wait; if we need to sleep we'll release our
893 * mutex and wait ourselves.
894 * __GFP_NORETRY: don't retry and rather return failure
895 * __GFP_NOMEMALLOC: don't use emergency reserves
896 * __GFP_NOWARN: don't print a warning in case of failure
897 *
898 * For debugging, if we set the cache size to 1, no new buffers will
899 * be allocated.
900 */
901 while (1) {
902 if (dm_bufio_cache_size_latch != 1) {
903 b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
904 if (b)
905 return b;
906 }
907
908 if (nf == NF_PREFETCH)
909 return NULL;
910
911 if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) {
912 dm_bufio_unlock(c);
913 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
914 dm_bufio_lock(c);
915 if (b)
916 return b;
917 tried_noio_alloc = true;
918 }
919
920 if (!list_empty(&c->reserved_buffers)) {
921 b = list_entry(c->reserved_buffers.next,
922 struct dm_buffer, lru_list);
923 list_del(&b->lru_list);
924 c->need_reserved_buffers++;
925
926 return b;
927 }
928
929 b = __get_unclaimed_buffer(c);
930 if (b)
931 return b;
932
933 __wait_for_free_buffer(c);
934 }
935}
936
937static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
938{
939 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
940
941 if (!b)
942 return NULL;
943
944 if (c->alloc_callback)
945 c->alloc_callback(b);
946
947 return b;
948}
949
950/*
951 * Free a buffer and wake other threads waiting for free buffers.
952 */
953static void __free_buffer_wake(struct dm_buffer *b)
954{
955 struct dm_bufio_client *c = b->c;
956
957 if (!c->need_reserved_buffers)
958 free_buffer(b);
959 else {
960 list_add(&b->lru_list, &c->reserved_buffers);
961 c->need_reserved_buffers--;
962 }
963
964 wake_up(&c->free_buffer_wait);
965}
966
967static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
968 struct list_head *write_list)
969{
970 struct dm_buffer *b, *tmp;
971
972 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
973 BUG_ON(test_bit(B_READING, &b->state));
974
975 if (!test_bit(B_DIRTY, &b->state) &&
976 !test_bit(B_WRITING, &b->state)) {
977 __relink_lru(b, LIST_CLEAN);
978 continue;
979 }
980
981 if (no_wait && test_bit(B_WRITING, &b->state))
982 return;
983
984 __write_dirty_buffer(b, write_list);
985 cond_resched();
986 }
987}
988
989/*
990 * Check if we're over watermark.
991 * If we are over threshold_buffers, start freeing buffers.
992 * If we're over "limit_buffers", block until we get under the limit.
993 */
994static void __check_watermark(struct dm_bufio_client *c,
995 struct list_head *write_list)
996{
997 if (c->n_buffers[LIST_DIRTY] > c->n_buffers[LIST_CLEAN] * DM_BUFIO_WRITEBACK_RATIO)
998 __write_dirty_buffers_async(c, 1, write_list);
999}
1000
1001/*----------------------------------------------------------------
1002 * Getting a buffer
1003 *--------------------------------------------------------------*/
1004
1005static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
1006 enum new_flag nf, int *need_submit,
1007 struct list_head *write_list)
1008{
1009 struct dm_buffer *b, *new_b = NULL;
1010
1011 *need_submit = 0;
1012
1013 b = __find(c, block);
1014 if (b)
1015 goto found_buffer;
1016
1017 if (nf == NF_GET)
1018 return NULL;
1019
1020 new_b = __alloc_buffer_wait(c, nf);
1021 if (!new_b)
1022 return NULL;
1023
1024 /*
1025 * We've had a period where the mutex was unlocked, so need to
1026 * recheck the buffer tree.
1027 */
1028 b = __find(c, block);
1029 if (b) {
1030 __free_buffer_wake(new_b);
1031 goto found_buffer;
1032 }
1033
1034 __check_watermark(c, write_list);
1035
1036 b = new_b;
1037 b->hold_count = 1;
1038 b->read_error = 0;
1039 b->write_error = 0;
1040 __link_buffer(b, block, LIST_CLEAN);
1041
1042 if (nf == NF_FRESH) {
1043 b->state = 0;
1044 return b;
1045 }
1046
1047 b->state = 1 << B_READING;
1048 *need_submit = 1;
1049
1050 return b;
1051
1052found_buffer:
1053 if (nf == NF_PREFETCH)
1054 return NULL;
1055 /*
1056 * Note: it is essential that we don't wait for the buffer to be
1057 * read if dm_bufio_get function is used. Both dm_bufio_get and
1058 * dm_bufio_prefetch can be used in the driver request routine.
1059 * If the user called both dm_bufio_prefetch and dm_bufio_get on
1060 * the same buffer, it would deadlock if we waited.
1061 */
1062 if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state)))
1063 return NULL;
1064
1065 b->hold_count++;
1066 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
1067 test_bit(B_WRITING, &b->state));
1068 return b;
1069}
1070
1071/*
1072 * The endio routine for reading: set the error, clear the bit and wake up
1073 * anyone waiting on the buffer.
1074 */
1075static void read_endio(struct dm_buffer *b, blk_status_t status)
1076{
1077 b->read_error = status;
1078
1079 BUG_ON(!test_bit(B_READING, &b->state));
1080
1081 smp_mb__before_atomic();
1082 clear_bit(B_READING, &b->state);
1083 smp_mb__after_atomic();
1084
1085 wake_up_bit(&b->state, B_READING);
1086}
1087
1088/*
1089 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
1090 * functions is similar except that dm_bufio_new doesn't read the
1091 * buffer from the disk (assuming that the caller overwrites all the data
1092 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1093 */
1094static void *new_read(struct dm_bufio_client *c, sector_t block,
1095 enum new_flag nf, struct dm_buffer **bp)
1096{
1097 int need_submit;
1098 struct dm_buffer *b;
1099
1100 LIST_HEAD(write_list);
1101
1102 dm_bufio_lock(c);
1103 b = __bufio_new(c, block, nf, &need_submit, &write_list);
1104#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1105 if (b && b->hold_count == 1)
1106 buffer_record_stack(b);
1107#endif
1108 dm_bufio_unlock(c);
1109
1110 __flush_write_list(&write_list);
1111
1112 if (!b)
1113 return NULL;
1114
1115 if (need_submit)
1116 submit_io(b, REQ_OP_READ, read_endio);
1117
1118 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
1119
1120 if (b->read_error) {
1121 int error = blk_status_to_errno(b->read_error);
1122
1123 dm_bufio_release(b);
1124
1125 return ERR_PTR(error);
1126 }
1127
1128 *bp = b;
1129
1130 return b->data;
1131}
1132
1133void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1134 struct dm_buffer **bp)
1135{
1136 return new_read(c, block, NF_GET, bp);
1137}
1138EXPORT_SYMBOL_GPL(dm_bufio_get);
1139
1140void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1141 struct dm_buffer **bp)
1142{
1143 BUG_ON(dm_bufio_in_request());
1144
1145 return new_read(c, block, NF_READ, bp);
1146}
1147EXPORT_SYMBOL_GPL(dm_bufio_read);
1148
1149void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1150 struct dm_buffer **bp)
1151{
1152 BUG_ON(dm_bufio_in_request());
1153
1154 return new_read(c, block, NF_FRESH, bp);
1155}
1156EXPORT_SYMBOL_GPL(dm_bufio_new);
1157
1158void dm_bufio_prefetch(struct dm_bufio_client *c,
1159 sector_t block, unsigned n_blocks)
1160{
1161 struct blk_plug plug;
1162
1163 LIST_HEAD(write_list);
1164
1165 BUG_ON(dm_bufio_in_request());
1166
1167 blk_start_plug(&plug);
1168 dm_bufio_lock(c);
1169
1170 for (; n_blocks--; block++) {
1171 int need_submit;
1172 struct dm_buffer *b;
1173 b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
1174 &write_list);
1175 if (unlikely(!list_empty(&write_list))) {
1176 dm_bufio_unlock(c);
1177 blk_finish_plug(&plug);
1178 __flush_write_list(&write_list);
1179 blk_start_plug(&plug);
1180 dm_bufio_lock(c);
1181 }
1182 if (unlikely(b != NULL)) {
1183 dm_bufio_unlock(c);
1184
1185 if (need_submit)
1186 submit_io(b, REQ_OP_READ, read_endio);
1187 dm_bufio_release(b);
1188
1189 cond_resched();
1190
1191 if (!n_blocks)
1192 goto flush_plug;
1193 dm_bufio_lock(c);
1194 }
1195 }
1196
1197 dm_bufio_unlock(c);
1198
1199flush_plug:
1200 blk_finish_plug(&plug);
1201}
1202EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1203
1204void dm_bufio_release(struct dm_buffer *b)
1205{
1206 struct dm_bufio_client *c = b->c;
1207
1208 dm_bufio_lock(c);
1209
1210 BUG_ON(!b->hold_count);
1211
1212 b->hold_count--;
1213 if (!b->hold_count) {
1214 wake_up(&c->free_buffer_wait);
1215
1216 /*
1217 * If there were errors on the buffer, and the buffer is not
1218 * to be written, free the buffer. There is no point in caching
1219 * invalid buffer.
1220 */
1221 if ((b->read_error || b->write_error) &&
1222 !test_bit_acquire(B_READING, &b->state) &&
1223 !test_bit(B_WRITING, &b->state) &&
1224 !test_bit(B_DIRTY, &b->state)) {
1225 __unlink_buffer(b);
1226 __free_buffer_wake(b);
1227 }
1228 }
1229
1230 dm_bufio_unlock(c);
1231}
1232EXPORT_SYMBOL_GPL(dm_bufio_release);
1233
1234void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
1235 unsigned start, unsigned end)
1236{
1237 struct dm_bufio_client *c = b->c;
1238
1239 BUG_ON(start >= end);
1240 BUG_ON(end > b->c->block_size);
1241
1242 dm_bufio_lock(c);
1243
1244 BUG_ON(test_bit(B_READING, &b->state));
1245
1246 if (!test_and_set_bit(B_DIRTY, &b->state)) {
1247 b->dirty_start = start;
1248 b->dirty_end = end;
1249 __relink_lru(b, LIST_DIRTY);
1250 } else {
1251 if (start < b->dirty_start)
1252 b->dirty_start = start;
1253 if (end > b->dirty_end)
1254 b->dirty_end = end;
1255 }
1256
1257 dm_bufio_unlock(c);
1258}
1259EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty);
1260
1261void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1262{
1263 dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size);
1264}
1265EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1266
1267void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1268{
1269 LIST_HEAD(write_list);
1270
1271 BUG_ON(dm_bufio_in_request());
1272
1273 dm_bufio_lock(c);
1274 __write_dirty_buffers_async(c, 0, &write_list);
1275 dm_bufio_unlock(c);
1276 __flush_write_list(&write_list);
1277}
1278EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1279
1280/*
1281 * For performance, it is essential that the buffers are written asynchronously
1282 * and simultaneously (so that the block layer can merge the writes) and then
1283 * waited upon.
1284 *
1285 * Finally, we flush hardware disk cache.
1286 */
1287int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1288{
1289 int a, f;
1290 unsigned long buffers_processed = 0;
1291 struct dm_buffer *b, *tmp;
1292
1293 LIST_HEAD(write_list);
1294
1295 dm_bufio_lock(c);
1296 __write_dirty_buffers_async(c, 0, &write_list);
1297 dm_bufio_unlock(c);
1298 __flush_write_list(&write_list);
1299 dm_bufio_lock(c);
1300
1301again:
1302 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1303 int dropped_lock = 0;
1304
1305 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1306 buffers_processed++;
1307
1308 BUG_ON(test_bit(B_READING, &b->state));
1309
1310 if (test_bit(B_WRITING, &b->state)) {
1311 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1312 dropped_lock = 1;
1313 b->hold_count++;
1314 dm_bufio_unlock(c);
1315 wait_on_bit_io(&b->state, B_WRITING,
1316 TASK_UNINTERRUPTIBLE);
1317 dm_bufio_lock(c);
1318 b->hold_count--;
1319 } else
1320 wait_on_bit_io(&b->state, B_WRITING,
1321 TASK_UNINTERRUPTIBLE);
1322 }
1323
1324 if (!test_bit(B_DIRTY, &b->state) &&
1325 !test_bit(B_WRITING, &b->state))
1326 __relink_lru(b, LIST_CLEAN);
1327
1328 cond_resched();
1329
1330 /*
1331 * If we dropped the lock, the list is no longer consistent,
1332 * so we must restart the search.
1333 *
1334 * In the most common case, the buffer just processed is
1335 * relinked to the clean list, so we won't loop scanning the
1336 * same buffer again and again.
1337 *
1338 * This may livelock if there is another thread simultaneously
1339 * dirtying buffers, so we count the number of buffers walked
1340 * and if it exceeds the total number of buffers, it means that
1341 * someone is doing some writes simultaneously with us. In
1342 * this case, stop, dropping the lock.
1343 */
1344 if (dropped_lock)
1345 goto again;
1346 }
1347 wake_up(&c->free_buffer_wait);
1348 dm_bufio_unlock(c);
1349
1350 a = xchg(&c->async_write_error, 0);
1351 f = dm_bufio_issue_flush(c);
1352 if (a)
1353 return a;
1354
1355 return f;
1356}
1357EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1358
1359/*
1360 * Use dm-io to send an empty barrier to flush the device.
1361 */
1362int dm_bufio_issue_flush(struct dm_bufio_client *c)
1363{
1364 struct dm_io_request io_req = {
1365 .bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC,
1366 .mem.type = DM_IO_KMEM,
1367 .mem.ptr.addr = NULL,
1368 .client = c->dm_io,
1369 };
1370 struct dm_io_region io_reg = {
1371 .bdev = c->bdev,
1372 .sector = 0,
1373 .count = 0,
1374 };
1375
1376 BUG_ON(dm_bufio_in_request());
1377
1378 return dm_io(&io_req, 1, &io_reg, NULL);
1379}
1380EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1381
1382/*
1383 * Use dm-io to send a discard request to flush the device.
1384 */
1385int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count)
1386{
1387 struct dm_io_request io_req = {
1388 .bi_opf = REQ_OP_DISCARD | REQ_SYNC,
1389 .mem.type = DM_IO_KMEM,
1390 .mem.ptr.addr = NULL,
1391 .client = c->dm_io,
1392 };
1393 struct dm_io_region io_reg = {
1394 .bdev = c->bdev,
1395 .sector = block_to_sector(c, block),
1396 .count = block_to_sector(c, count),
1397 };
1398
1399 BUG_ON(dm_bufio_in_request());
1400
1401 return dm_io(&io_req, 1, &io_reg, NULL);
1402}
1403EXPORT_SYMBOL_GPL(dm_bufio_issue_discard);
1404
1405/*
1406 * We first delete any other buffer that may be at that new location.
1407 *
1408 * Then, we write the buffer to the original location if it was dirty.
1409 *
1410 * Then, if we are the only one who is holding the buffer, relink the buffer
1411 * in the buffer tree for the new location.
1412 *
1413 * If there was someone else holding the buffer, we write it to the new
1414 * location but not relink it, because that other user needs to have the buffer
1415 * at the same place.
1416 */
1417void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1418{
1419 struct dm_bufio_client *c = b->c;
1420 struct dm_buffer *new;
1421
1422 BUG_ON(dm_bufio_in_request());
1423
1424 dm_bufio_lock(c);
1425
1426retry:
1427 new = __find(c, new_block);
1428 if (new) {
1429 if (new->hold_count) {
1430 __wait_for_free_buffer(c);
1431 goto retry;
1432 }
1433
1434 /*
1435 * FIXME: Is there any point waiting for a write that's going
1436 * to be overwritten in a bit?
1437 */
1438 __make_buffer_clean(new);
1439 __unlink_buffer(new);
1440 __free_buffer_wake(new);
1441 }
1442
1443 BUG_ON(!b->hold_count);
1444 BUG_ON(test_bit(B_READING, &b->state));
1445
1446 __write_dirty_buffer(b, NULL);
1447 if (b->hold_count == 1) {
1448 wait_on_bit_io(&b->state, B_WRITING,
1449 TASK_UNINTERRUPTIBLE);
1450 set_bit(B_DIRTY, &b->state);
1451 b->dirty_start = 0;
1452 b->dirty_end = c->block_size;
1453 __unlink_buffer(b);
1454 __link_buffer(b, new_block, LIST_DIRTY);
1455 } else {
1456 sector_t old_block;
1457 wait_on_bit_lock_io(&b->state, B_WRITING,
1458 TASK_UNINTERRUPTIBLE);
1459 /*
1460 * Relink buffer to "new_block" so that write_callback
1461 * sees "new_block" as a block number.
1462 * After the write, link the buffer back to old_block.
1463 * All this must be done in bufio lock, so that block number
1464 * change isn't visible to other threads.
1465 */
1466 old_block = b->block;
1467 __unlink_buffer(b);
1468 __link_buffer(b, new_block, b->list_mode);
1469 submit_io(b, REQ_OP_WRITE, write_endio);
1470 wait_on_bit_io(&b->state, B_WRITING,
1471 TASK_UNINTERRUPTIBLE);
1472 __unlink_buffer(b);
1473 __link_buffer(b, old_block, b->list_mode);
1474 }
1475
1476 dm_bufio_unlock(c);
1477 dm_bufio_release(b);
1478}
1479EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1480
1481static void forget_buffer_locked(struct dm_buffer *b)
1482{
1483 if (likely(!b->hold_count) && likely(!smp_load_acquire(&b->state))) {
1484 __unlink_buffer(b);
1485 __free_buffer_wake(b);
1486 }
1487}
1488
1489/*
1490 * Free the given buffer.
1491 *
1492 * This is just a hint, if the buffer is in use or dirty, this function
1493 * does nothing.
1494 */
1495void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
1496{
1497 struct dm_buffer *b;
1498
1499 dm_bufio_lock(c);
1500
1501 b = __find(c, block);
1502 if (b)
1503 forget_buffer_locked(b);
1504
1505 dm_bufio_unlock(c);
1506}
1507EXPORT_SYMBOL_GPL(dm_bufio_forget);
1508
1509void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks)
1510{
1511 struct dm_buffer *b;
1512 sector_t end_block = block + n_blocks;
1513
1514 while (block < end_block) {
1515 dm_bufio_lock(c);
1516
1517 b = __find_next(c, block);
1518 if (b) {
1519 block = b->block + 1;
1520 forget_buffer_locked(b);
1521 }
1522
1523 dm_bufio_unlock(c);
1524
1525 if (!b)
1526 break;
1527 }
1528
1529}
1530EXPORT_SYMBOL_GPL(dm_bufio_forget_buffers);
1531
1532void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
1533{
1534 c->minimum_buffers = n;
1535}
1536EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers);
1537
1538unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1539{
1540 return c->block_size;
1541}
1542EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1543
1544sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1545{
1546 sector_t s = bdev_nr_sectors(c->bdev);
1547 if (s >= c->start)
1548 s -= c->start;
1549 else
1550 s = 0;
1551 if (likely(c->sectors_per_block_bits >= 0))
1552 s >>= c->sectors_per_block_bits;
1553 else
1554 sector_div(s, c->block_size >> SECTOR_SHIFT);
1555 return s;
1556}
1557EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1558
1559struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c)
1560{
1561 return c->dm_io;
1562}
1563EXPORT_SYMBOL_GPL(dm_bufio_get_dm_io_client);
1564
1565sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1566{
1567 return b->block;
1568}
1569EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1570
1571void *dm_bufio_get_block_data(struct dm_buffer *b)
1572{
1573 return b->data;
1574}
1575EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1576
1577void *dm_bufio_get_aux_data(struct dm_buffer *b)
1578{
1579 return b + 1;
1580}
1581EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1582
1583struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1584{
1585 return b->c;
1586}
1587EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1588
1589static void drop_buffers(struct dm_bufio_client *c)
1590{
1591 struct dm_buffer *b;
1592 int i;
1593 bool warned = false;
1594
1595 BUG_ON(dm_bufio_in_request());
1596
1597 /*
1598 * An optimization so that the buffers are not written one-by-one.
1599 */
1600 dm_bufio_write_dirty_buffers_async(c);
1601
1602 dm_bufio_lock(c);
1603
1604 while ((b = __get_unclaimed_buffer(c)))
1605 __free_buffer_wake(b);
1606
1607 for (i = 0; i < LIST_SIZE; i++)
1608 list_for_each_entry(b, &c->lru[i], lru_list) {
1609 WARN_ON(!warned);
1610 warned = true;
1611 DMERR("leaked buffer %llx, hold count %u, list %d",
1612 (unsigned long long)b->block, b->hold_count, i);
1613#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1614 stack_trace_print(b->stack_entries, b->stack_len, 1);
1615 /* mark unclaimed to avoid BUG_ON below */
1616 b->hold_count = 0;
1617#endif
1618 }
1619
1620#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1621 while ((b = __get_unclaimed_buffer(c)))
1622 __free_buffer_wake(b);
1623#endif
1624
1625 for (i = 0; i < LIST_SIZE; i++)
1626 BUG_ON(!list_empty(&c->lru[i]));
1627
1628 dm_bufio_unlock(c);
1629}
1630
1631/*
1632 * We may not be able to evict this buffer if IO pending or the client
1633 * is still using it. Caller is expected to know buffer is too old.
1634 *
1635 * And if GFP_NOFS is used, we must not do any I/O because we hold
1636 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
1637 * rerouted to different bufio client.
1638 */
1639static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
1640{
1641 if (!(gfp & __GFP_FS) ||
1642 (static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) {
1643 if (test_bit_acquire(B_READING, &b->state) ||
1644 test_bit(B_WRITING, &b->state) ||
1645 test_bit(B_DIRTY, &b->state))
1646 return false;
1647 }
1648
1649 if (b->hold_count)
1650 return false;
1651
1652 __make_buffer_clean(b);
1653 __unlink_buffer(b);
1654 __free_buffer_wake(b);
1655
1656 return true;
1657}
1658
1659static unsigned long get_retain_buffers(struct dm_bufio_client *c)
1660{
1661 unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes);
1662 if (likely(c->sectors_per_block_bits >= 0))
1663 retain_bytes >>= c->sectors_per_block_bits + SECTOR_SHIFT;
1664 else
1665 retain_bytes /= c->block_size;
1666 return retain_bytes;
1667}
1668
1669static void __scan(struct dm_bufio_client *c)
1670{
1671 int l;
1672 struct dm_buffer *b, *tmp;
1673 unsigned long freed = 0;
1674 unsigned long count = c->n_buffers[LIST_CLEAN] +
1675 c->n_buffers[LIST_DIRTY];
1676 unsigned long retain_target = get_retain_buffers(c);
1677
1678 for (l = 0; l < LIST_SIZE; l++) {
1679 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
1680 if (count - freed <= retain_target)
1681 atomic_long_set(&c->need_shrink, 0);
1682 if (!atomic_long_read(&c->need_shrink))
1683 return;
1684 if (__try_evict_buffer(b, GFP_KERNEL)) {
1685 atomic_long_dec(&c->need_shrink);
1686 freed++;
1687 }
1688 cond_resched();
1689 }
1690 }
1691}
1692
1693static void shrink_work(struct work_struct *w)
1694{
1695 struct dm_bufio_client *c = container_of(w, struct dm_bufio_client, shrink_work);
1696
1697 dm_bufio_lock(c);
1698 __scan(c);
1699 dm_bufio_unlock(c);
1700}
1701
1702static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1703{
1704 struct dm_bufio_client *c;
1705
1706 c = container_of(shrink, struct dm_bufio_client, shrinker);
1707 atomic_long_add(sc->nr_to_scan, &c->need_shrink);
1708 queue_work(dm_bufio_wq, &c->shrink_work);
1709
1710 return sc->nr_to_scan;
1711}
1712
1713static unsigned long dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1714{
1715 struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker);
1716 unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) +
1717 READ_ONCE(c->n_buffers[LIST_DIRTY]);
1718 unsigned long retain_target = get_retain_buffers(c);
1719 unsigned long queued_for_cleanup = atomic_long_read(&c->need_shrink);
1720
1721 if (unlikely(count < retain_target))
1722 count = 0;
1723 else
1724 count -= retain_target;
1725
1726 if (unlikely(count < queued_for_cleanup))
1727 count = 0;
1728 else
1729 count -= queued_for_cleanup;
1730
1731 return count;
1732}
1733
1734/*
1735 * Create the buffering interface
1736 */
1737struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1738 unsigned reserved_buffers, unsigned aux_size,
1739 void (*alloc_callback)(struct dm_buffer *),
1740 void (*write_callback)(struct dm_buffer *),
1741 unsigned int flags)
1742{
1743 int r;
1744 struct dm_bufio_client *c;
1745 unsigned i;
1746 char slab_name[27];
1747
1748 if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) {
1749 DMERR("%s: block size not specified or is not multiple of 512b", __func__);
1750 r = -EINVAL;
1751 goto bad_client;
1752 }
1753
1754 c = kzalloc(sizeof(*c), GFP_KERNEL);
1755 if (!c) {
1756 r = -ENOMEM;
1757 goto bad_client;
1758 }
1759 c->buffer_tree = RB_ROOT;
1760
1761 c->bdev = bdev;
1762 c->block_size = block_size;
1763 if (is_power_of_2(block_size))
1764 c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
1765 else
1766 c->sectors_per_block_bits = -1;
1767
1768 c->alloc_callback = alloc_callback;
1769 c->write_callback = write_callback;
1770
1771 if (flags & DM_BUFIO_CLIENT_NO_SLEEP) {
1772 c->no_sleep = true;
1773 static_branch_inc(&no_sleep_enabled);
1774 }
1775
1776 for (i = 0; i < LIST_SIZE; i++) {
1777 INIT_LIST_HEAD(&c->lru[i]);
1778 c->n_buffers[i] = 0;
1779 }
1780
1781 mutex_init(&c->lock);
1782 spin_lock_init(&c->spinlock);
1783 INIT_LIST_HEAD(&c->reserved_buffers);
1784 c->need_reserved_buffers = reserved_buffers;
1785
1786 dm_bufio_set_minimum_buffers(c, DM_BUFIO_MIN_BUFFERS);
1787
1788 init_waitqueue_head(&c->free_buffer_wait);
1789 c->async_write_error = 0;
1790
1791 c->dm_io = dm_io_client_create();
1792 if (IS_ERR(c->dm_io)) {
1793 r = PTR_ERR(c->dm_io);
1794 goto bad_dm_io;
1795 }
1796
1797 if (block_size <= KMALLOC_MAX_SIZE &&
1798 (block_size < PAGE_SIZE || !is_power_of_2(block_size))) {
1799 unsigned align = min(1U << __ffs(block_size), (unsigned)PAGE_SIZE);
1800 snprintf(slab_name, sizeof slab_name, "dm_bufio_cache-%u", block_size);
1801 c->slab_cache = kmem_cache_create(slab_name, block_size, align,
1802 SLAB_RECLAIM_ACCOUNT, NULL);
1803 if (!c->slab_cache) {
1804 r = -ENOMEM;
1805 goto bad;
1806 }
1807 }
1808 if (aux_size)
1809 snprintf(slab_name, sizeof slab_name, "dm_bufio_buffer-%u", aux_size);
1810 else
1811 snprintf(slab_name, sizeof slab_name, "dm_bufio_buffer");
1812 c->slab_buffer = kmem_cache_create(slab_name, sizeof(struct dm_buffer) + aux_size,
1813 0, SLAB_RECLAIM_ACCOUNT, NULL);
1814 if (!c->slab_buffer) {
1815 r = -ENOMEM;
1816 goto bad;
1817 }
1818
1819 while (c->need_reserved_buffers) {
1820 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1821
1822 if (!b) {
1823 r = -ENOMEM;
1824 goto bad;
1825 }
1826 __free_buffer_wake(b);
1827 }
1828
1829 INIT_WORK(&c->shrink_work, shrink_work);
1830 atomic_long_set(&c->need_shrink, 0);
1831
1832 c->shrinker.count_objects = dm_bufio_shrink_count;
1833 c->shrinker.scan_objects = dm_bufio_shrink_scan;
1834 c->shrinker.seeks = 1;
1835 c->shrinker.batch = 0;
1836 r = register_shrinker(&c->shrinker, "md-%s:(%u:%u)", slab_name,
1837 MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev));
1838 if (r)
1839 goto bad;
1840
1841 mutex_lock(&dm_bufio_clients_lock);
1842 dm_bufio_client_count++;
1843 list_add(&c->client_list, &dm_bufio_all_clients);
1844 __cache_size_refresh();
1845 mutex_unlock(&dm_bufio_clients_lock);
1846
1847 return c;
1848
1849bad:
1850 while (!list_empty(&c->reserved_buffers)) {
1851 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1852 struct dm_buffer, lru_list);
1853 list_del(&b->lru_list);
1854 free_buffer(b);
1855 }
1856 kmem_cache_destroy(c->slab_cache);
1857 kmem_cache_destroy(c->slab_buffer);
1858 dm_io_client_destroy(c->dm_io);
1859bad_dm_io:
1860 mutex_destroy(&c->lock);
1861 if (c->no_sleep)
1862 static_branch_dec(&no_sleep_enabled);
1863 kfree(c);
1864bad_client:
1865 return ERR_PTR(r);
1866}
1867EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1868
1869/*
1870 * Free the buffering interface.
1871 * It is required that there are no references on any buffers.
1872 */
1873void dm_bufio_client_destroy(struct dm_bufio_client *c)
1874{
1875 unsigned i;
1876
1877 drop_buffers(c);
1878
1879 unregister_shrinker(&c->shrinker);
1880 flush_work(&c->shrink_work);
1881
1882 mutex_lock(&dm_bufio_clients_lock);
1883
1884 list_del(&c->client_list);
1885 dm_bufio_client_count--;
1886 __cache_size_refresh();
1887
1888 mutex_unlock(&dm_bufio_clients_lock);
1889
1890 BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
1891 BUG_ON(c->need_reserved_buffers);
1892
1893 while (!list_empty(&c->reserved_buffers)) {
1894 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1895 struct dm_buffer, lru_list);
1896 list_del(&b->lru_list);
1897 free_buffer(b);
1898 }
1899
1900 for (i = 0; i < LIST_SIZE; i++)
1901 if (c->n_buffers[i])
1902 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1903
1904 for (i = 0; i < LIST_SIZE; i++)
1905 BUG_ON(c->n_buffers[i]);
1906
1907 kmem_cache_destroy(c->slab_cache);
1908 kmem_cache_destroy(c->slab_buffer);
1909 dm_io_client_destroy(c->dm_io);
1910 mutex_destroy(&c->lock);
1911 if (c->no_sleep)
1912 static_branch_dec(&no_sleep_enabled);
1913 kfree(c);
1914}
1915EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1916
1917void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start)
1918{
1919 c->start = start;
1920}
1921EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset);
1922
1923static unsigned get_max_age_hz(void)
1924{
1925 unsigned max_age = READ_ONCE(dm_bufio_max_age);
1926
1927 if (max_age > UINT_MAX / HZ)
1928 max_age = UINT_MAX / HZ;
1929
1930 return max_age * HZ;
1931}
1932
1933static bool older_than(struct dm_buffer *b, unsigned long age_hz)
1934{
1935 return time_after_eq(jiffies, b->last_accessed + age_hz);
1936}
1937
1938static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
1939{
1940 struct dm_buffer *b, *tmp;
1941 unsigned long retain_target = get_retain_buffers(c);
1942 unsigned long count;
1943 LIST_HEAD(write_list);
1944
1945 dm_bufio_lock(c);
1946
1947 __check_watermark(c, &write_list);
1948 if (unlikely(!list_empty(&write_list))) {
1949 dm_bufio_unlock(c);
1950 __flush_write_list(&write_list);
1951 dm_bufio_lock(c);
1952 }
1953
1954 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1955 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) {
1956 if (count <= retain_target)
1957 break;
1958
1959 if (!older_than(b, age_hz))
1960 break;
1961
1962 if (__try_evict_buffer(b, 0))
1963 count--;
1964
1965 cond_resched();
1966 }
1967
1968 dm_bufio_unlock(c);
1969}
1970
1971static void do_global_cleanup(struct work_struct *w)
1972{
1973 struct dm_bufio_client *locked_client = NULL;
1974 struct dm_bufio_client *current_client;
1975 struct dm_buffer *b;
1976 unsigned spinlock_hold_count;
1977 unsigned long threshold = dm_bufio_cache_size -
1978 dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO;
1979 unsigned long loops = global_num * 2;
1980
1981 mutex_lock(&dm_bufio_clients_lock);
1982
1983 while (1) {
1984 cond_resched();
1985
1986 spin_lock(&global_spinlock);
1987 if (unlikely(dm_bufio_current_allocated <= threshold))
1988 break;
1989
1990 spinlock_hold_count = 0;
1991get_next:
1992 if (!loops--)
1993 break;
1994 if (unlikely(list_empty(&global_queue)))
1995 break;
1996 b = list_entry(global_queue.prev, struct dm_buffer, global_list);
1997
1998 if (b->accessed) {
1999 b->accessed = 0;
2000 list_move(&b->global_list, &global_queue);
2001 if (likely(++spinlock_hold_count < 16))
2002 goto get_next;
2003 spin_unlock(&global_spinlock);
2004 continue;
2005 }
2006
2007 current_client = b->c;
2008 if (unlikely(current_client != locked_client)) {
2009 if (locked_client)
2010 dm_bufio_unlock(locked_client);
2011
2012 if (!dm_bufio_trylock(current_client)) {
2013 spin_unlock(&global_spinlock);
2014 dm_bufio_lock(current_client);
2015 locked_client = current_client;
2016 continue;
2017 }
2018
2019 locked_client = current_client;
2020 }
2021
2022 spin_unlock(&global_spinlock);
2023
2024 if (unlikely(!__try_evict_buffer(b, GFP_KERNEL))) {
2025 spin_lock(&global_spinlock);
2026 list_move(&b->global_list, &global_queue);
2027 spin_unlock(&global_spinlock);
2028 }
2029 }
2030
2031 spin_unlock(&global_spinlock);
2032
2033 if (locked_client)
2034 dm_bufio_unlock(locked_client);
2035
2036 mutex_unlock(&dm_bufio_clients_lock);
2037}
2038
2039static void cleanup_old_buffers(void)
2040{
2041 unsigned long max_age_hz = get_max_age_hz();
2042 struct dm_bufio_client *c;
2043
2044 mutex_lock(&dm_bufio_clients_lock);
2045
2046 __cache_size_refresh();
2047
2048 list_for_each_entry(c, &dm_bufio_all_clients, client_list)
2049 __evict_old_buffers(c, max_age_hz);
2050
2051 mutex_unlock(&dm_bufio_clients_lock);
2052}
2053
2054static void work_fn(struct work_struct *w)
2055{
2056 cleanup_old_buffers();
2057
2058 queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work,
2059 DM_BUFIO_WORK_TIMER_SECS * HZ);
2060}
2061
2062/*----------------------------------------------------------------
2063 * Module setup
2064 *--------------------------------------------------------------*/
2065
2066/*
2067 * This is called only once for the whole dm_bufio module.
2068 * It initializes memory limit.
2069 */
2070static int __init dm_bufio_init(void)
2071{
2072 __u64 mem;
2073
2074 dm_bufio_allocated_kmem_cache = 0;
2075 dm_bufio_allocated_get_free_pages = 0;
2076 dm_bufio_allocated_vmalloc = 0;
2077 dm_bufio_current_allocated = 0;
2078
2079 mem = (__u64)mult_frac(totalram_pages() - totalhigh_pages(),
2080 DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT;
2081
2082 if (mem > ULONG_MAX)
2083 mem = ULONG_MAX;
2084
2085#ifdef CONFIG_MMU
2086 if (mem > mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100))
2087 mem = mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100);
2088#endif
2089
2090 dm_bufio_default_cache_size = mem;
2091
2092 mutex_lock(&dm_bufio_clients_lock);
2093 __cache_size_refresh();
2094 mutex_unlock(&dm_bufio_clients_lock);
2095
2096 dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0);
2097 if (!dm_bufio_wq)
2098 return -ENOMEM;
2099
2100 INIT_DELAYED_WORK(&dm_bufio_cleanup_old_work, work_fn);
2101 INIT_WORK(&dm_bufio_replacement_work, do_global_cleanup);
2102 queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work,
2103 DM_BUFIO_WORK_TIMER_SECS * HZ);
2104
2105 return 0;
2106}
2107
2108/*
2109 * This is called once when unloading the dm_bufio module.
2110 */
2111static void __exit dm_bufio_exit(void)
2112{
2113 int bug = 0;
2114
2115 cancel_delayed_work_sync(&dm_bufio_cleanup_old_work);
2116 destroy_workqueue(dm_bufio_wq);
2117
2118 if (dm_bufio_client_count) {
2119 DMCRIT("%s: dm_bufio_client_count leaked: %d",
2120 __func__, dm_bufio_client_count);
2121 bug = 1;
2122 }
2123
2124 if (dm_bufio_current_allocated) {
2125 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
2126 __func__, dm_bufio_current_allocated);
2127 bug = 1;
2128 }
2129
2130 if (dm_bufio_allocated_get_free_pages) {
2131 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
2132 __func__, dm_bufio_allocated_get_free_pages);
2133 bug = 1;
2134 }
2135
2136 if (dm_bufio_allocated_vmalloc) {
2137 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
2138 __func__, dm_bufio_allocated_vmalloc);
2139 bug = 1;
2140 }
2141
2142 BUG_ON(bug);
2143}
2144
2145module_init(dm_bufio_init)
2146module_exit(dm_bufio_exit)
2147
2148module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
2149MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
2150
2151module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
2152MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
2153
2154module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR);
2155MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");
2156
2157module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
2158MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
2159
2160module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
2161MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
2162
2163module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
2164MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
2165
2166module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
2167MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
2168
2169module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
2170MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
2171
2172MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
2173MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
2174MODULE_LICENSE("GPL");