Merge remote-tracking branch 'omap_dss2/for-next'
[deliverable/linux.git] / drivers / md / dm-bufio.c
CommitLineData
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1/*
2 * Copyright (C) 2009-2011 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * This file is released under the GPL.
7 */
8
9#include "dm-bufio.h"
10
11#include <linux/device-mapper.h>
12#include <linux/dm-io.h>
13#include <linux/slab.h>
f495339c 14#include <linux/jiffies.h>
95d402f0 15#include <linux/vmalloc.h>
95d402f0 16#include <linux/shrinker.h>
6f66263f 17#include <linux/module.h>
4e420c45 18#include <linux/rbtree.h>
86bad0c7 19#include <linux/stacktrace.h>
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20
21#define DM_MSG_PREFIX "bufio"
22
23/*
24 * Memory management policy:
25 * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
26 * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
27 * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
28 * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
29 * dirty buffers.
30 */
31#define DM_BUFIO_MIN_BUFFERS 8
32
33#define DM_BUFIO_MEMORY_PERCENT 2
34#define DM_BUFIO_VMALLOC_PERCENT 25
35#define DM_BUFIO_WRITEBACK_PERCENT 75
36
37/*
38 * Check buffer ages in this interval (seconds)
39 */
33096a78 40#define DM_BUFIO_WORK_TIMER_SECS 30
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41
42/*
43 * Free buffers when they are older than this (seconds)
44 */
33096a78 45#define DM_BUFIO_DEFAULT_AGE_SECS 300
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46
47/*
33096a78 48 * The nr of bytes of cached data to keep around.
95d402f0 49 */
33096a78 50#define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
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51
52/*
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53 * The number of bvec entries that are embedded directly in the buffer.
54 * If the chunk size is larger, dm-io is used to do the io.
95d402f0 55 */
95d402f0 56#define DM_BUFIO_INLINE_VECS 16
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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
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107 unsigned minimum_buffers;
108
4e420c45 109 struct rb_root buffer_tree;
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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 {
4e420c45 138 struct rb_node node;
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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;
2480945c 150 struct list_head write_list;
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151 struct bio bio;
152 struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
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153#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
154#define MAX_STACK 10
155 struct stack_trace stack_trace;
156 unsigned long stack_entries[MAX_STACK];
157#endif
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158};
159
160/*----------------------------------------------------------------*/
161
162static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
163static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
164
165static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
166{
167 unsigned ret = c->blocks_per_page_bits - 1;
168
169 BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
170
171 return ret;
172}
173
174#define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)])
175#define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)])
176
177#define dm_bufio_in_request() (!!current->bio_list)
178
179static void dm_bufio_lock(struct dm_bufio_client *c)
180{
181 mutex_lock_nested(&c->lock, dm_bufio_in_request());
182}
183
184static int dm_bufio_trylock(struct dm_bufio_client *c)
185{
186 return mutex_trylock(&c->lock);
187}
188
189static void dm_bufio_unlock(struct dm_bufio_client *c)
190{
191 mutex_unlock(&c->lock);
192}
193
194/*
195 * FIXME Move to sched.h?
196 */
197#ifdef CONFIG_PREEMPT_VOLUNTARY
198# define dm_bufio_cond_resched() \
199do { \
200 if (unlikely(need_resched())) \
201 _cond_resched(); \
202} while (0)
203#else
204# define dm_bufio_cond_resched() do { } while (0)
205#endif
206
207/*----------------------------------------------------------------*/
208
209/*
210 * Default cache size: available memory divided by the ratio.
211 */
212static unsigned long dm_bufio_default_cache_size;
213
214/*
215 * Total cache size set by the user.
216 */
217static unsigned long dm_bufio_cache_size;
218
219/*
220 * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
221 * at any time. If it disagrees, the user has changed cache size.
222 */
223static unsigned long dm_bufio_cache_size_latch;
224
225static DEFINE_SPINLOCK(param_spinlock);
226
227/*
228 * Buffers are freed after this timeout
229 */
230static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
33096a78 231static unsigned dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
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232
233static unsigned long dm_bufio_peak_allocated;
234static unsigned long dm_bufio_allocated_kmem_cache;
235static unsigned long dm_bufio_allocated_get_free_pages;
236static unsigned long dm_bufio_allocated_vmalloc;
237static unsigned long dm_bufio_current_allocated;
238
239/*----------------------------------------------------------------*/
240
241/*
242 * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
243 */
244static unsigned long dm_bufio_cache_size_per_client;
245
246/*
247 * The current number of clients.
248 */
249static int dm_bufio_client_count;
250
251/*
252 * The list of all clients.
253 */
254static LIST_HEAD(dm_bufio_all_clients);
255
256/*
257 * This mutex protects dm_bufio_cache_size_latch,
258 * dm_bufio_cache_size_per_client and dm_bufio_client_count
259 */
260static DEFINE_MUTEX(dm_bufio_clients_lock);
261
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262#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
263static void buffer_record_stack(struct dm_buffer *b)
264{
265 b->stack_trace.nr_entries = 0;
266 b->stack_trace.max_entries = MAX_STACK;
267 b->stack_trace.entries = b->stack_entries;
268 b->stack_trace.skip = 2;
269 save_stack_trace(&b->stack_trace);
270}
271#endif
272
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273/*----------------------------------------------------------------
274 * A red/black tree acts as an index for all the buffers.
275 *--------------------------------------------------------------*/
276static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
277{
278 struct rb_node *n = c->buffer_tree.rb_node;
279 struct dm_buffer *b;
280
281 while (n) {
282 b = container_of(n, struct dm_buffer, node);
283
284 if (b->block == block)
285 return b;
286
287 n = (b->block < block) ? n->rb_left : n->rb_right;
288 }
289
290 return NULL;
291}
292
293static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
294{
295 struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
296 struct dm_buffer *found;
297
298 while (*new) {
299 found = container_of(*new, struct dm_buffer, node);
300
301 if (found->block == b->block) {
302 BUG_ON(found != b);
303 return;
304 }
305
306 parent = *new;
307 new = (found->block < b->block) ?
308 &((*new)->rb_left) : &((*new)->rb_right);
309 }
310
311 rb_link_node(&b->node, parent, new);
312 rb_insert_color(&b->node, &c->buffer_tree);
313}
314
315static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
316{
317 rb_erase(&b->node, &c->buffer_tree);
318}
319
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320/*----------------------------------------------------------------*/
321
322static void adjust_total_allocated(enum data_mode data_mode, long diff)
323{
324 static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
325 &dm_bufio_allocated_kmem_cache,
326 &dm_bufio_allocated_get_free_pages,
327 &dm_bufio_allocated_vmalloc,
328 };
329
330 spin_lock(&param_spinlock);
331
332 *class_ptr[data_mode] += diff;
333
334 dm_bufio_current_allocated += diff;
335
336 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
337 dm_bufio_peak_allocated = dm_bufio_current_allocated;
338
339 spin_unlock(&param_spinlock);
340}
341
342/*
343 * Change the number of clients and recalculate per-client limit.
344 */
345static void __cache_size_refresh(void)
346{
347 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
348 BUG_ON(dm_bufio_client_count < 0);
349
fe5fe906 350 dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
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351
352 /*
353 * Use default if set to 0 and report the actual cache size used.
354 */
355 if (!dm_bufio_cache_size_latch) {
356 (void)cmpxchg(&dm_bufio_cache_size, 0,
357 dm_bufio_default_cache_size);
358 dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
359 }
360
361 dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
362 (dm_bufio_client_count ? : 1);
363}
364
365/*
366 * Allocating buffer data.
367 *
368 * Small buffers are allocated with kmem_cache, to use space optimally.
369 *
370 * For large buffers, we choose between get_free_pages and vmalloc.
371 * Each has advantages and disadvantages.
372 *
373 * __get_free_pages can randomly fail if the memory is fragmented.
374 * __vmalloc won't randomly fail, but vmalloc space is limited (it may be
375 * as low as 128M) so using it for caching is not appropriate.
376 *
377 * If the allocation may fail we use __get_free_pages. Memory fragmentation
378 * won't have a fatal effect here, but it just causes flushes of some other
379 * buffers and more I/O will be performed. Don't use __get_free_pages if it
380 * always fails (i.e. order >= MAX_ORDER).
381 *
382 * If the allocation shouldn't fail we use __vmalloc. This is only for the
383 * initial reserve allocation, so there's no risk of wasting all vmalloc
384 * space.
385 */
386static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
387 enum data_mode *data_mode)
388{
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389 unsigned noio_flag;
390 void *ptr;
391
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392 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
393 *data_mode = DATA_MODE_SLAB;
394 return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
395 }
396
397 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
398 gfp_mask & __GFP_NORETRY) {
399 *data_mode = DATA_MODE_GET_FREE_PAGES;
400 return (void *)__get_free_pages(gfp_mask,
401 c->pages_per_block_bits);
402 }
403
404 *data_mode = DATA_MODE_VMALLOC;
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405
406 /*
407 * __vmalloc allocates the data pages and auxiliary structures with
408 * gfp_flags that were specified, but pagetables are always allocated
409 * with GFP_KERNEL, no matter what was specified as gfp_mask.
410 *
411 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
412 * all allocations done by this process (including pagetables) are done
413 * as if GFP_NOIO was specified.
414 */
415
416 if (gfp_mask & __GFP_NORETRY)
417 noio_flag = memalloc_noio_save();
418
220cd058 419 ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
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420
421 if (gfp_mask & __GFP_NORETRY)
422 memalloc_noio_restore(noio_flag);
423
424 return ptr;
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425}
426
427/*
428 * Free buffer's data.
429 */
430static void free_buffer_data(struct dm_bufio_client *c,
431 void *data, enum data_mode data_mode)
432{
433 switch (data_mode) {
434 case DATA_MODE_SLAB:
435 kmem_cache_free(DM_BUFIO_CACHE(c), data);
436 break;
437
438 case DATA_MODE_GET_FREE_PAGES:
439 free_pages((unsigned long)data, c->pages_per_block_bits);
440 break;
441
442 case DATA_MODE_VMALLOC:
443 vfree(data);
444 break;
445
446 default:
447 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
448 data_mode);
449 BUG();
450 }
451}
452
453/*
454 * Allocate buffer and its data.
455 */
456static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
457{
458 struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
459 gfp_mask);
460
461 if (!b)
462 return NULL;
463
464 b->c = c;
465
466 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
467 if (!b->data) {
468 kfree(b);
469 return NULL;
470 }
471
472 adjust_total_allocated(b->data_mode, (long)c->block_size);
473
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474#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
475 memset(&b->stack_trace, 0, sizeof(b->stack_trace));
476#endif
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477 return b;
478}
479
480/*
481 * Free buffer and its data.
482 */
483static void free_buffer(struct dm_buffer *b)
484{
485 struct dm_bufio_client *c = b->c;
486
487 adjust_total_allocated(b->data_mode, -(long)c->block_size);
488
489 free_buffer_data(c, b->data, b->data_mode);
490 kfree(b);
491}
492
493/*
494 * Link buffer to the hash list and clean or dirty queue.
495 */
496static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
497{
498 struct dm_bufio_client *c = b->c;
499
500 c->n_buffers[dirty]++;
501 b->block = block;
502 b->list_mode = dirty;
503 list_add(&b->lru_list, &c->lru[dirty]);
4e420c45 504 __insert(b->c, b);
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505 b->last_accessed = jiffies;
506}
507
508/*
509 * Unlink buffer from the hash list and dirty or clean queue.
510 */
511static void __unlink_buffer(struct dm_buffer *b)
512{
513 struct dm_bufio_client *c = b->c;
514
515 BUG_ON(!c->n_buffers[b->list_mode]);
516
517 c->n_buffers[b->list_mode]--;
4e420c45 518 __remove(b->c, b);
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519 list_del(&b->lru_list);
520}
521
522/*
523 * Place the buffer to the head of dirty or clean LRU queue.
524 */
525static void __relink_lru(struct dm_buffer *b, int dirty)
526{
527 struct dm_bufio_client *c = b->c;
528
529 BUG_ON(!c->n_buffers[b->list_mode]);
530
531 c->n_buffers[b->list_mode]--;
532 c->n_buffers[dirty]++;
533 b->list_mode = dirty;
54499afb 534 list_move(&b->lru_list, &c->lru[dirty]);
eb76faf5 535 b->last_accessed = jiffies;
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536}
537
538/*----------------------------------------------------------------
539 * Submit I/O on the buffer.
540 *
541 * Bio interface is faster but it has some problems:
542 * the vector list is limited (increasing this limit increases
543 * memory-consumption per buffer, so it is not viable);
544 *
545 * the memory must be direct-mapped, not vmalloced;
546 *
547 * the I/O driver can reject requests spuriously if it thinks that
548 * the requests are too big for the device or if they cross a
549 * controller-defined memory boundary.
550 *
551 * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
552 * it is not vmalloced, try using the bio interface.
553 *
554 * If the buffer is big, if it is vmalloced or if the underlying device
555 * rejects the bio because it is too large, use dm-io layer to do the I/O.
556 * The dm-io layer splits the I/O into multiple requests, avoiding the above
557 * shortcomings.
558 *--------------------------------------------------------------*/
559
560/*
561 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
562 * that the request was handled directly with bio interface.
563 */
564static void dmio_complete(unsigned long error, void *context)
565{
566 struct dm_buffer *b = context;
567
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568 b->bio.bi_error = error ? -EIO : 0;
569 b->bio.bi_end_io(&b->bio);
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570}
571
572static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
573 bio_end_io_t *end_io)
574{
575 int r;
576 struct dm_io_request io_req = {
e6047149
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577 .bi_op = rw,
578 .bi_op_flags = 0,
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579 .notify.fn = dmio_complete,
580 .notify.context = b,
581 .client = b->c->dm_io,
582 };
583 struct dm_io_region region = {
584 .bdev = b->c->bdev,
585 .sector = block << b->c->sectors_per_block_bits,
586 .count = b->c->block_size >> SECTOR_SHIFT,
587 };
588
589 if (b->data_mode != DATA_MODE_VMALLOC) {
590 io_req.mem.type = DM_IO_KMEM;
591 io_req.mem.ptr.addr = b->data;
592 } else {
593 io_req.mem.type = DM_IO_VMA;
594 io_req.mem.ptr.vma = b->data;
595 }
596
597 b->bio.bi_end_io = end_io;
598
599 r = dm_io(&io_req, 1, &region, NULL);
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600 if (r) {
601 b->bio.bi_error = r;
602 end_io(&b->bio);
603 }
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604}
605
4246a0b6 606static void inline_endio(struct bio *bio)
445559cd
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607{
608 bio_end_io_t *end_fn = bio->bi_private;
4246a0b6 609 int error = bio->bi_error;
445559cd
DW
610
611 /*
612 * Reset the bio to free any attached resources
613 * (e.g. bio integrity profiles).
614 */
615 bio_reset(bio);
616
4246a0b6
CH
617 bio->bi_error = error;
618 end_fn(bio);
445559cd
DW
619}
620
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621static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
622 bio_end_io_t *end_io)
623{
624 char *ptr;
625 int len;
626
627 bio_init(&b->bio);
628 b->bio.bi_io_vec = b->bio_vec;
629 b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
4f024f37 630 b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
95d402f0 631 b->bio.bi_bdev = b->c->bdev;
445559cd
DW
632 b->bio.bi_end_io = inline_endio;
633 /*
634 * Use of .bi_private isn't a problem here because
635 * the dm_buffer's inline bio is local to bufio.
636 */
637 b->bio.bi_private = end_io;
e6047149 638 bio_set_op_attrs(&b->bio, rw, 0);
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639
640 /*
641 * We assume that if len >= PAGE_SIZE ptr is page-aligned.
642 * If len < PAGE_SIZE the buffer doesn't cross page boundary.
643 */
644 ptr = b->data;
645 len = b->c->block_size;
646
647 if (len >= PAGE_SIZE)
648 BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
649 else
650 BUG_ON((unsigned long)ptr & (len - 1));
651
652 do {
653 if (!bio_add_page(&b->bio, virt_to_page(ptr),
654 len < PAGE_SIZE ? len : PAGE_SIZE,
756d097b 655 offset_in_page(ptr))) {
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656 BUG_ON(b->c->block_size <= PAGE_SIZE);
657 use_dmio(b, rw, block, end_io);
658 return;
659 }
660
661 len -= PAGE_SIZE;
662 ptr += PAGE_SIZE;
663 } while (len > 0);
664
4e49ea4a 665 submit_bio(&b->bio);
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666}
667
668static void submit_io(struct dm_buffer *b, int rw, sector_t block,
669 bio_end_io_t *end_io)
670{
671 if (rw == WRITE && b->c->write_callback)
672 b->c->write_callback(b);
673
674 if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
675 b->data_mode != DATA_MODE_VMALLOC)
676 use_inline_bio(b, rw, block, end_io);
677 else
678 use_dmio(b, rw, block, end_io);
679}
680
681/*----------------------------------------------------------------
682 * Writing dirty buffers
683 *--------------------------------------------------------------*/
684
685/*
686 * The endio routine for write.
687 *
688 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
689 * it.
690 */
4246a0b6 691static void write_endio(struct bio *bio)
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692{
693 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
694
4246a0b6
CH
695 b->write_error = bio->bi_error;
696 if (unlikely(bio->bi_error)) {
95d402f0 697 struct dm_bufio_client *c = b->c;
4246a0b6 698 int error = bio->bi_error;
95d402f0
MP
699 (void)cmpxchg(&c->async_write_error, 0, error);
700 }
701
702 BUG_ON(!test_bit(B_WRITING, &b->state));
703
4e857c58 704 smp_mb__before_atomic();
95d402f0 705 clear_bit(B_WRITING, &b->state);
4e857c58 706 smp_mb__after_atomic();
95d402f0
MP
707
708 wake_up_bit(&b->state, B_WRITING);
709}
710
95d402f0
MP
711/*
712 * Initiate a write on a dirty buffer, but don't wait for it.
713 *
714 * - If the buffer is not dirty, exit.
715 * - If there some previous write going on, wait for it to finish (we can't
716 * have two writes on the same buffer simultaneously).
717 * - Submit our write and don't wait on it. We set B_WRITING indicating
718 * that there is a write in progress.
719 */
2480945c
MP
720static void __write_dirty_buffer(struct dm_buffer *b,
721 struct list_head *write_list)
95d402f0
MP
722{
723 if (!test_bit(B_DIRTY, &b->state))
724 return;
725
726 clear_bit(B_DIRTY, &b->state);
74316201 727 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
95d402f0 728
2480945c
MP
729 if (!write_list)
730 submit_io(b, WRITE, b->block, write_endio);
731 else
732 list_add_tail(&b->write_list, write_list);
733}
734
735static void __flush_write_list(struct list_head *write_list)
736{
737 struct blk_plug plug;
738 blk_start_plug(&plug);
739 while (!list_empty(write_list)) {
740 struct dm_buffer *b =
741 list_entry(write_list->next, struct dm_buffer, write_list);
742 list_del(&b->write_list);
743 submit_io(b, WRITE, b->block, write_endio);
744 dm_bufio_cond_resched();
745 }
746 blk_finish_plug(&plug);
95d402f0
MP
747}
748
749/*
750 * Wait until any activity on the buffer finishes. Possibly write the
751 * buffer if it is dirty. When this function finishes, there is no I/O
752 * running on the buffer and the buffer is not dirty.
753 */
754static void __make_buffer_clean(struct dm_buffer *b)
755{
756 BUG_ON(b->hold_count);
757
758 if (!b->state) /* fast case */
759 return;
760
74316201 761 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
2480945c 762 __write_dirty_buffer(b, NULL);
74316201 763 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
95d402f0
MP
764}
765
766/*
767 * Find some buffer that is not held by anybody, clean it, unlink it and
768 * return it.
769 */
770static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
771{
772 struct dm_buffer *b;
773
774 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
775 BUG_ON(test_bit(B_WRITING, &b->state));
776 BUG_ON(test_bit(B_DIRTY, &b->state));
777
778 if (!b->hold_count) {
779 __make_buffer_clean(b);
780 __unlink_buffer(b);
781 return b;
782 }
783 dm_bufio_cond_resched();
784 }
785
786 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
787 BUG_ON(test_bit(B_READING, &b->state));
788
789 if (!b->hold_count) {
790 __make_buffer_clean(b);
791 __unlink_buffer(b);
792 return b;
793 }
794 dm_bufio_cond_resched();
795 }
796
797 return NULL;
798}
799
800/*
801 * Wait until some other threads free some buffer or release hold count on
802 * some buffer.
803 *
804 * This function is entered with c->lock held, drops it and regains it
805 * before exiting.
806 */
807static void __wait_for_free_buffer(struct dm_bufio_client *c)
808{
809 DECLARE_WAITQUEUE(wait, current);
810
811 add_wait_queue(&c->free_buffer_wait, &wait);
812 set_task_state(current, TASK_UNINTERRUPTIBLE);
813 dm_bufio_unlock(c);
814
815 io_schedule();
816
95d402f0
MP
817 remove_wait_queue(&c->free_buffer_wait, &wait);
818
819 dm_bufio_lock(c);
820}
821
a66cc28f
MP
822enum new_flag {
823 NF_FRESH = 0,
824 NF_READ = 1,
825 NF_GET = 2,
826 NF_PREFETCH = 3
827};
828
95d402f0
MP
829/*
830 * Allocate a new buffer. If the allocation is not possible, wait until
831 * some other thread frees a buffer.
832 *
833 * May drop the lock and regain it.
834 */
a66cc28f 835static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
95d402f0
MP
836{
837 struct dm_buffer *b;
838
839 /*
840 * dm-bufio is resistant to allocation failures (it just keeps
841 * one buffer reserved in cases all the allocations fail).
842 * So set flags to not try too hard:
843 * GFP_NOIO: don't recurse into the I/O layer
844 * __GFP_NORETRY: don't retry and rather return failure
845 * __GFP_NOMEMALLOC: don't use emergency reserves
846 * __GFP_NOWARN: don't print a warning in case of failure
847 *
848 * For debugging, if we set the cache size to 1, no new buffers will
849 * be allocated.
850 */
851 while (1) {
852 if (dm_bufio_cache_size_latch != 1) {
853 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
854 if (b)
855 return b;
856 }
857
a66cc28f
MP
858 if (nf == NF_PREFETCH)
859 return NULL;
860
95d402f0
MP
861 if (!list_empty(&c->reserved_buffers)) {
862 b = list_entry(c->reserved_buffers.next,
863 struct dm_buffer, lru_list);
864 list_del(&b->lru_list);
865 c->need_reserved_buffers++;
866
867 return b;
868 }
869
870 b = __get_unclaimed_buffer(c);
871 if (b)
872 return b;
873
874 __wait_for_free_buffer(c);
875 }
876}
877
a66cc28f 878static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
95d402f0 879{
a66cc28f
MP
880 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
881
882 if (!b)
883 return NULL;
95d402f0
MP
884
885 if (c->alloc_callback)
886 c->alloc_callback(b);
887
888 return b;
889}
890
891/*
892 * Free a buffer and wake other threads waiting for free buffers.
893 */
894static void __free_buffer_wake(struct dm_buffer *b)
895{
896 struct dm_bufio_client *c = b->c;
897
898 if (!c->need_reserved_buffers)
899 free_buffer(b);
900 else {
901 list_add(&b->lru_list, &c->reserved_buffers);
902 c->need_reserved_buffers--;
903 }
904
905 wake_up(&c->free_buffer_wait);
906}
907
2480945c
MP
908static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
909 struct list_head *write_list)
95d402f0
MP
910{
911 struct dm_buffer *b, *tmp;
912
913 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
914 BUG_ON(test_bit(B_READING, &b->state));
915
916 if (!test_bit(B_DIRTY, &b->state) &&
917 !test_bit(B_WRITING, &b->state)) {
918 __relink_lru(b, LIST_CLEAN);
919 continue;
920 }
921
922 if (no_wait && test_bit(B_WRITING, &b->state))
923 return;
924
2480945c 925 __write_dirty_buffer(b, write_list);
95d402f0
MP
926 dm_bufio_cond_resched();
927 }
928}
929
930/*
931 * Get writeback threshold and buffer limit for a given client.
932 */
933static void __get_memory_limit(struct dm_bufio_client *c,
934 unsigned long *threshold_buffers,
935 unsigned long *limit_buffers)
936{
937 unsigned long buffers;
938
fe5fe906 939 if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
95d402f0
MP
940 mutex_lock(&dm_bufio_clients_lock);
941 __cache_size_refresh();
942 mutex_unlock(&dm_bufio_clients_lock);
943 }
944
945 buffers = dm_bufio_cache_size_per_client >>
946 (c->sectors_per_block_bits + SECTOR_SHIFT);
947
55b082e6
MP
948 if (buffers < c->minimum_buffers)
949 buffers = c->minimum_buffers;
95d402f0
MP
950
951 *limit_buffers = buffers;
952 *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
953}
954
955/*
956 * Check if we're over watermark.
957 * If we are over threshold_buffers, start freeing buffers.
958 * If we're over "limit_buffers", block until we get under the limit.
959 */
2480945c
MP
960static void __check_watermark(struct dm_bufio_client *c,
961 struct list_head *write_list)
95d402f0
MP
962{
963 unsigned long threshold_buffers, limit_buffers;
964
965 __get_memory_limit(c, &threshold_buffers, &limit_buffers);
966
967 while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] >
968 limit_buffers) {
969
970 struct dm_buffer *b = __get_unclaimed_buffer(c);
971
972 if (!b)
973 return;
974
975 __free_buffer_wake(b);
976 dm_bufio_cond_resched();
977 }
978
979 if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
2480945c 980 __write_dirty_buffers_async(c, 1, write_list);
95d402f0
MP
981}
982
95d402f0
MP
983/*----------------------------------------------------------------
984 * Getting a buffer
985 *--------------------------------------------------------------*/
986
95d402f0 987static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
2480945c
MP
988 enum new_flag nf, int *need_submit,
989 struct list_head *write_list)
95d402f0
MP
990{
991 struct dm_buffer *b, *new_b = NULL;
992
993 *need_submit = 0;
994
995 b = __find(c, block);
a66cc28f
MP
996 if (b)
997 goto found_buffer;
95d402f0
MP
998
999 if (nf == NF_GET)
1000 return NULL;
1001
a66cc28f
MP
1002 new_b = __alloc_buffer_wait(c, nf);
1003 if (!new_b)
1004 return NULL;
95d402f0
MP
1005
1006 /*
1007 * We've had a period where the mutex was unlocked, so need to
1008 * recheck the hash table.
1009 */
1010 b = __find(c, block);
1011 if (b) {
1012 __free_buffer_wake(new_b);
a66cc28f 1013 goto found_buffer;
95d402f0
MP
1014 }
1015
2480945c 1016 __check_watermark(c, write_list);
95d402f0
MP
1017
1018 b = new_b;
1019 b->hold_count = 1;
1020 b->read_error = 0;
1021 b->write_error = 0;
1022 __link_buffer(b, block, LIST_CLEAN);
1023
1024 if (nf == NF_FRESH) {
1025 b->state = 0;
1026 return b;
1027 }
1028
1029 b->state = 1 << B_READING;
1030 *need_submit = 1;
1031
1032 return b;
a66cc28f
MP
1033
1034found_buffer:
1035 if (nf == NF_PREFETCH)
1036 return NULL;
1037 /*
1038 * Note: it is essential that we don't wait for the buffer to be
1039 * read if dm_bufio_get function is used. Both dm_bufio_get and
1040 * dm_bufio_prefetch can be used in the driver request routine.
1041 * If the user called both dm_bufio_prefetch and dm_bufio_get on
1042 * the same buffer, it would deadlock if we waited.
1043 */
1044 if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state)))
1045 return NULL;
1046
1047 b->hold_count++;
1048 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
1049 test_bit(B_WRITING, &b->state));
1050 return b;
95d402f0
MP
1051}
1052
1053/*
1054 * The endio routine for reading: set the error, clear the bit and wake up
1055 * anyone waiting on the buffer.
1056 */
4246a0b6 1057static void read_endio(struct bio *bio)
95d402f0
MP
1058{
1059 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
1060
4246a0b6 1061 b->read_error = bio->bi_error;
95d402f0
MP
1062
1063 BUG_ON(!test_bit(B_READING, &b->state));
1064
4e857c58 1065 smp_mb__before_atomic();
95d402f0 1066 clear_bit(B_READING, &b->state);
4e857c58 1067 smp_mb__after_atomic();
95d402f0
MP
1068
1069 wake_up_bit(&b->state, B_READING);
1070}
1071
1072/*
1073 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
1074 * functions is similar except that dm_bufio_new doesn't read the
1075 * buffer from the disk (assuming that the caller overwrites all the data
1076 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1077 */
1078static void *new_read(struct dm_bufio_client *c, sector_t block,
1079 enum new_flag nf, struct dm_buffer **bp)
1080{
1081 int need_submit;
1082 struct dm_buffer *b;
1083
2480945c
MP
1084 LIST_HEAD(write_list);
1085
95d402f0 1086 dm_bufio_lock(c);
2480945c 1087 b = __bufio_new(c, block, nf, &need_submit, &write_list);
86bad0c7
MP
1088#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1089 if (b && b->hold_count == 1)
1090 buffer_record_stack(b);
1091#endif
95d402f0
MP
1092 dm_bufio_unlock(c);
1093
2480945c
MP
1094 __flush_write_list(&write_list);
1095
a66cc28f 1096 if (!b)
f98c8f79 1097 return NULL;
95d402f0
MP
1098
1099 if (need_submit)
1100 submit_io(b, READ, b->block, read_endio);
1101
74316201 1102 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
95d402f0
MP
1103
1104 if (b->read_error) {
1105 int error = b->read_error;
1106
1107 dm_bufio_release(b);
1108
1109 return ERR_PTR(error);
1110 }
1111
1112 *bp = b;
1113
1114 return b->data;
1115}
1116
1117void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1118 struct dm_buffer **bp)
1119{
1120 return new_read(c, block, NF_GET, bp);
1121}
1122EXPORT_SYMBOL_GPL(dm_bufio_get);
1123
1124void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1125 struct dm_buffer **bp)
1126{
1127 BUG_ON(dm_bufio_in_request());
1128
1129 return new_read(c, block, NF_READ, bp);
1130}
1131EXPORT_SYMBOL_GPL(dm_bufio_read);
1132
1133void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1134 struct dm_buffer **bp)
1135{
1136 BUG_ON(dm_bufio_in_request());
1137
1138 return new_read(c, block, NF_FRESH, bp);
1139}
1140EXPORT_SYMBOL_GPL(dm_bufio_new);
1141
a66cc28f
MP
1142void dm_bufio_prefetch(struct dm_bufio_client *c,
1143 sector_t block, unsigned n_blocks)
1144{
1145 struct blk_plug plug;
1146
2480945c
MP
1147 LIST_HEAD(write_list);
1148
3b6b7813
MP
1149 BUG_ON(dm_bufio_in_request());
1150
a66cc28f
MP
1151 blk_start_plug(&plug);
1152 dm_bufio_lock(c);
1153
1154 for (; n_blocks--; block++) {
1155 int need_submit;
1156 struct dm_buffer *b;
2480945c
MP
1157 b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
1158 &write_list);
1159 if (unlikely(!list_empty(&write_list))) {
1160 dm_bufio_unlock(c);
1161 blk_finish_plug(&plug);
1162 __flush_write_list(&write_list);
1163 blk_start_plug(&plug);
1164 dm_bufio_lock(c);
1165 }
a66cc28f
MP
1166 if (unlikely(b != NULL)) {
1167 dm_bufio_unlock(c);
1168
1169 if (need_submit)
1170 submit_io(b, READ, b->block, read_endio);
1171 dm_bufio_release(b);
1172
1173 dm_bufio_cond_resched();
1174
1175 if (!n_blocks)
1176 goto flush_plug;
1177 dm_bufio_lock(c);
1178 }
a66cc28f
MP
1179 }
1180
1181 dm_bufio_unlock(c);
1182
1183flush_plug:
1184 blk_finish_plug(&plug);
1185}
1186EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1187
95d402f0
MP
1188void dm_bufio_release(struct dm_buffer *b)
1189{
1190 struct dm_bufio_client *c = b->c;
1191
1192 dm_bufio_lock(c);
1193
95d402f0
MP
1194 BUG_ON(!b->hold_count);
1195
1196 b->hold_count--;
1197 if (!b->hold_count) {
1198 wake_up(&c->free_buffer_wait);
1199
1200 /*
1201 * If there were errors on the buffer, and the buffer is not
1202 * to be written, free the buffer. There is no point in caching
1203 * invalid buffer.
1204 */
1205 if ((b->read_error || b->write_error) &&
a66cc28f 1206 !test_bit(B_READING, &b->state) &&
95d402f0
MP
1207 !test_bit(B_WRITING, &b->state) &&
1208 !test_bit(B_DIRTY, &b->state)) {
1209 __unlink_buffer(b);
1210 __free_buffer_wake(b);
1211 }
1212 }
1213
1214 dm_bufio_unlock(c);
1215}
1216EXPORT_SYMBOL_GPL(dm_bufio_release);
1217
1218void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1219{
1220 struct dm_bufio_client *c = b->c;
1221
1222 dm_bufio_lock(c);
1223
a66cc28f
MP
1224 BUG_ON(test_bit(B_READING, &b->state));
1225
95d402f0
MP
1226 if (!test_and_set_bit(B_DIRTY, &b->state))
1227 __relink_lru(b, LIST_DIRTY);
1228
1229 dm_bufio_unlock(c);
1230}
1231EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1232
1233void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1234{
2480945c
MP
1235 LIST_HEAD(write_list);
1236
95d402f0
MP
1237 BUG_ON(dm_bufio_in_request());
1238
1239 dm_bufio_lock(c);
2480945c 1240 __write_dirty_buffers_async(c, 0, &write_list);
95d402f0 1241 dm_bufio_unlock(c);
2480945c 1242 __flush_write_list(&write_list);
95d402f0
MP
1243}
1244EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1245
1246/*
1247 * For performance, it is essential that the buffers are written asynchronously
1248 * and simultaneously (so that the block layer can merge the writes) and then
1249 * waited upon.
1250 *
1251 * Finally, we flush hardware disk cache.
1252 */
1253int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1254{
1255 int a, f;
1256 unsigned long buffers_processed = 0;
1257 struct dm_buffer *b, *tmp;
1258
2480945c
MP
1259 LIST_HEAD(write_list);
1260
1261 dm_bufio_lock(c);
1262 __write_dirty_buffers_async(c, 0, &write_list);
1263 dm_bufio_unlock(c);
1264 __flush_write_list(&write_list);
95d402f0 1265 dm_bufio_lock(c);
95d402f0
MP
1266
1267again:
1268 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1269 int dropped_lock = 0;
1270
1271 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1272 buffers_processed++;
1273
1274 BUG_ON(test_bit(B_READING, &b->state));
1275
1276 if (test_bit(B_WRITING, &b->state)) {
1277 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1278 dropped_lock = 1;
1279 b->hold_count++;
1280 dm_bufio_unlock(c);
74316201
N
1281 wait_on_bit_io(&b->state, B_WRITING,
1282 TASK_UNINTERRUPTIBLE);
95d402f0
MP
1283 dm_bufio_lock(c);
1284 b->hold_count--;
1285 } else
74316201
N
1286 wait_on_bit_io(&b->state, B_WRITING,
1287 TASK_UNINTERRUPTIBLE);
95d402f0
MP
1288 }
1289
1290 if (!test_bit(B_DIRTY, &b->state) &&
1291 !test_bit(B_WRITING, &b->state))
1292 __relink_lru(b, LIST_CLEAN);
1293
1294 dm_bufio_cond_resched();
1295
1296 /*
1297 * If we dropped the lock, the list is no longer consistent,
1298 * so we must restart the search.
1299 *
1300 * In the most common case, the buffer just processed is
1301 * relinked to the clean list, so we won't loop scanning the
1302 * same buffer again and again.
1303 *
1304 * This may livelock if there is another thread simultaneously
1305 * dirtying buffers, so we count the number of buffers walked
1306 * and if it exceeds the total number of buffers, it means that
1307 * someone is doing some writes simultaneously with us. In
1308 * this case, stop, dropping the lock.
1309 */
1310 if (dropped_lock)
1311 goto again;
1312 }
1313 wake_up(&c->free_buffer_wait);
1314 dm_bufio_unlock(c);
1315
1316 a = xchg(&c->async_write_error, 0);
1317 f = dm_bufio_issue_flush(c);
1318 if (a)
1319 return a;
1320
1321 return f;
1322}
1323EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1324
1325/*
1326 * Use dm-io to send and empty barrier flush the device.
1327 */
1328int dm_bufio_issue_flush(struct dm_bufio_client *c)
1329{
1330 struct dm_io_request io_req = {
e6047149
MC
1331 .bi_op = REQ_OP_WRITE,
1332 .bi_op_flags = WRITE_FLUSH,
95d402f0
MP
1333 .mem.type = DM_IO_KMEM,
1334 .mem.ptr.addr = NULL,
1335 .client = c->dm_io,
1336 };
1337 struct dm_io_region io_reg = {
1338 .bdev = c->bdev,
1339 .sector = 0,
1340 .count = 0,
1341 };
1342
1343 BUG_ON(dm_bufio_in_request());
1344
1345 return dm_io(&io_req, 1, &io_reg, NULL);
1346}
1347EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1348
1349/*
1350 * We first delete any other buffer that may be at that new location.
1351 *
1352 * Then, we write the buffer to the original location if it was dirty.
1353 *
1354 * Then, if we are the only one who is holding the buffer, relink the buffer
1355 * in the hash queue for the new location.
1356 *
1357 * If there was someone else holding the buffer, we write it to the new
1358 * location but not relink it, because that other user needs to have the buffer
1359 * at the same place.
1360 */
1361void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1362{
1363 struct dm_bufio_client *c = b->c;
1364 struct dm_buffer *new;
1365
1366 BUG_ON(dm_bufio_in_request());
1367
1368 dm_bufio_lock(c);
1369
1370retry:
1371 new = __find(c, new_block);
1372 if (new) {
1373 if (new->hold_count) {
1374 __wait_for_free_buffer(c);
1375 goto retry;
1376 }
1377
1378 /*
1379 * FIXME: Is there any point waiting for a write that's going
1380 * to be overwritten in a bit?
1381 */
1382 __make_buffer_clean(new);
1383 __unlink_buffer(new);
1384 __free_buffer_wake(new);
1385 }
1386
1387 BUG_ON(!b->hold_count);
1388 BUG_ON(test_bit(B_READING, &b->state));
1389
2480945c 1390 __write_dirty_buffer(b, NULL);
95d402f0 1391 if (b->hold_count == 1) {
74316201
N
1392 wait_on_bit_io(&b->state, B_WRITING,
1393 TASK_UNINTERRUPTIBLE);
95d402f0
MP
1394 set_bit(B_DIRTY, &b->state);
1395 __unlink_buffer(b);
1396 __link_buffer(b, new_block, LIST_DIRTY);
1397 } else {
1398 sector_t old_block;
74316201
N
1399 wait_on_bit_lock_io(&b->state, B_WRITING,
1400 TASK_UNINTERRUPTIBLE);
95d402f0
MP
1401 /*
1402 * Relink buffer to "new_block" so that write_callback
1403 * sees "new_block" as a block number.
1404 * After the write, link the buffer back to old_block.
1405 * All this must be done in bufio lock, so that block number
1406 * change isn't visible to other threads.
1407 */
1408 old_block = b->block;
1409 __unlink_buffer(b);
1410 __link_buffer(b, new_block, b->list_mode);
1411 submit_io(b, WRITE, new_block, write_endio);
74316201
N
1412 wait_on_bit_io(&b->state, B_WRITING,
1413 TASK_UNINTERRUPTIBLE);
95d402f0
MP
1414 __unlink_buffer(b);
1415 __link_buffer(b, old_block, b->list_mode);
1416 }
1417
1418 dm_bufio_unlock(c);
1419 dm_bufio_release(b);
1420}
1421EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1422
55494bf2
MP
1423/*
1424 * Free the given buffer.
1425 *
1426 * This is just a hint, if the buffer is in use or dirty, this function
1427 * does nothing.
1428 */
1429void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
1430{
1431 struct dm_buffer *b;
1432
1433 dm_bufio_lock(c);
1434
1435 b = __find(c, block);
1436 if (b && likely(!b->hold_count) && likely(!b->state)) {
1437 __unlink_buffer(b);
1438 __free_buffer_wake(b);
1439 }
1440
1441 dm_bufio_unlock(c);
1442}
1443EXPORT_SYMBOL(dm_bufio_forget);
1444
55b082e6
MP
1445void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
1446{
1447 c->minimum_buffers = n;
1448}
1449EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
1450
95d402f0
MP
1451unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1452{
1453 return c->block_size;
1454}
1455EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1456
1457sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1458{
1459 return i_size_read(c->bdev->bd_inode) >>
1460 (SECTOR_SHIFT + c->sectors_per_block_bits);
1461}
1462EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1463
1464sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1465{
1466 return b->block;
1467}
1468EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1469
1470void *dm_bufio_get_block_data(struct dm_buffer *b)
1471{
1472 return b->data;
1473}
1474EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1475
1476void *dm_bufio_get_aux_data(struct dm_buffer *b)
1477{
1478 return b + 1;
1479}
1480EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1481
1482struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1483{
1484 return b->c;
1485}
1486EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1487
1488static void drop_buffers(struct dm_bufio_client *c)
1489{
1490 struct dm_buffer *b;
1491 int i;
86bad0c7 1492 bool warned = false;
95d402f0
MP
1493
1494 BUG_ON(dm_bufio_in_request());
1495
1496 /*
1497 * An optimization so that the buffers are not written one-by-one.
1498 */
1499 dm_bufio_write_dirty_buffers_async(c);
1500
1501 dm_bufio_lock(c);
1502
1503 while ((b = __get_unclaimed_buffer(c)))
1504 __free_buffer_wake(b);
1505
1506 for (i = 0; i < LIST_SIZE; i++)
86bad0c7
MP
1507 list_for_each_entry(b, &c->lru[i], lru_list) {
1508 WARN_ON(!warned);
1509 warned = true;
95d402f0
MP
1510 DMERR("leaked buffer %llx, hold count %u, list %d",
1511 (unsigned long long)b->block, b->hold_count, i);
86bad0c7
MP
1512#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1513 print_stack_trace(&b->stack_trace, 1);
1514 b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */
1515#endif
1516 }
1517
1518#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1519 while ((b = __get_unclaimed_buffer(c)))
1520 __free_buffer_wake(b);
1521#endif
95d402f0
MP
1522
1523 for (i = 0; i < LIST_SIZE; i++)
1524 BUG_ON(!list_empty(&c->lru[i]));
1525
1526 dm_bufio_unlock(c);
1527}
1528
1529/*
33096a78
JT
1530 * We may not be able to evict this buffer if IO pending or the client
1531 * is still using it. Caller is expected to know buffer is too old.
1532 *
9d28eb12
MP
1533 * And if GFP_NOFS is used, we must not do any I/O because we hold
1534 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
1535 * rerouted to different bufio client.
95d402f0 1536 */
33096a78 1537static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
95d402f0 1538{
9d28eb12 1539 if (!(gfp & __GFP_FS)) {
95d402f0
MP
1540 if (test_bit(B_READING, &b->state) ||
1541 test_bit(B_WRITING, &b->state) ||
1542 test_bit(B_DIRTY, &b->state))
33096a78 1543 return false;
95d402f0
MP
1544 }
1545
1546 if (b->hold_count)
33096a78 1547 return false;
95d402f0
MP
1548
1549 __make_buffer_clean(b);
1550 __unlink_buffer(b);
1551 __free_buffer_wake(b);
1552
33096a78 1553 return true;
95d402f0
MP
1554}
1555
33096a78
JT
1556static unsigned get_retain_buffers(struct dm_bufio_client *c)
1557{
1558 unsigned retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);
1559 return retain_bytes / c->block_size;
1560}
1561
1562static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
1563 gfp_t gfp_mask)
95d402f0
MP
1564{
1565 int l;
1566 struct dm_buffer *b, *tmp;
33096a78
JT
1567 unsigned long freed = 0;
1568 unsigned long count = nr_to_scan;
1569 unsigned retain_target = get_retain_buffers(c);
95d402f0
MP
1570
1571 for (l = 0; l < LIST_SIZE; l++) {
7dc19d5a 1572 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
33096a78
JT
1573 if (__try_evict_buffer(b, gfp_mask))
1574 freed++;
1575 if (!--nr_to_scan || ((count - freed) <= retain_target))
0e825862
MP
1576 return freed;
1577 dm_bufio_cond_resched();
7dc19d5a 1578 }
95d402f0 1579 }
7dc19d5a 1580 return freed;
95d402f0
MP
1581}
1582
7dc19d5a
DC
1583static unsigned long
1584dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
95d402f0 1585{
7dc19d5a
DC
1586 struct dm_bufio_client *c;
1587 unsigned long freed;
95d402f0 1588
7dc19d5a 1589 c = container_of(shrink, struct dm_bufio_client, shrinker);
9d28eb12 1590 if (sc->gfp_mask & __GFP_FS)
95d402f0
MP
1591 dm_bufio_lock(c);
1592 else if (!dm_bufio_trylock(c))
7dc19d5a 1593 return SHRINK_STOP;
95d402f0 1594
7dc19d5a
DC
1595 freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);
1596 dm_bufio_unlock(c);
1597 return freed;
1598}
95d402f0 1599
7dc19d5a
DC
1600static unsigned long
1601dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1602{
1603 struct dm_bufio_client *c;
1604 unsigned long count;
95d402f0 1605
7dc19d5a 1606 c = container_of(shrink, struct dm_bufio_client, shrinker);
9d28eb12 1607 if (sc->gfp_mask & __GFP_FS)
7dc19d5a
DC
1608 dm_bufio_lock(c);
1609 else if (!dm_bufio_trylock(c))
1610 return 0;
95d402f0 1611
7dc19d5a
DC
1612 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1613 dm_bufio_unlock(c);
1614 return count;
95d402f0
MP
1615}
1616
1617/*
1618 * Create the buffering interface
1619 */
1620struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1621 unsigned reserved_buffers, unsigned aux_size,
1622 void (*alloc_callback)(struct dm_buffer *),
1623 void (*write_callback)(struct dm_buffer *))
1624{
1625 int r;
1626 struct dm_bufio_client *c;
1627 unsigned i;
1628
1629 BUG_ON(block_size < 1 << SECTOR_SHIFT ||
1630 (block_size & (block_size - 1)));
1631
d8c712ea 1632 c = kzalloc(sizeof(*c), GFP_KERNEL);
95d402f0
MP
1633 if (!c) {
1634 r = -ENOMEM;
1635 goto bad_client;
1636 }
4e420c45 1637 c->buffer_tree = RB_ROOT;
95d402f0
MP
1638
1639 c->bdev = bdev;
1640 c->block_size = block_size;
a3d939ae
MP
1641 c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
1642 c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ?
1643 __ffs(block_size) - PAGE_SHIFT : 0;
1644 c->blocks_per_page_bits = (__ffs(block_size) < PAGE_SHIFT ?
1645 PAGE_SHIFT - __ffs(block_size) : 0);
95d402f0
MP
1646
1647 c->aux_size = aux_size;
1648 c->alloc_callback = alloc_callback;
1649 c->write_callback = write_callback;
1650
1651 for (i = 0; i < LIST_SIZE; i++) {
1652 INIT_LIST_HEAD(&c->lru[i]);
1653 c->n_buffers[i] = 0;
1654 }
1655
95d402f0
MP
1656 mutex_init(&c->lock);
1657 INIT_LIST_HEAD(&c->reserved_buffers);
1658 c->need_reserved_buffers = reserved_buffers;
1659
55b082e6
MP
1660 c->minimum_buffers = DM_BUFIO_MIN_BUFFERS;
1661
95d402f0
MP
1662 init_waitqueue_head(&c->free_buffer_wait);
1663 c->async_write_error = 0;
1664
1665 c->dm_io = dm_io_client_create();
1666 if (IS_ERR(c->dm_io)) {
1667 r = PTR_ERR(c->dm_io);
1668 goto bad_dm_io;
1669 }
1670
1671 mutex_lock(&dm_bufio_clients_lock);
1672 if (c->blocks_per_page_bits) {
1673 if (!DM_BUFIO_CACHE_NAME(c)) {
1674 DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
1675 if (!DM_BUFIO_CACHE_NAME(c)) {
1676 r = -ENOMEM;
1677 mutex_unlock(&dm_bufio_clients_lock);
1678 goto bad_cache;
1679 }
1680 }
1681
1682 if (!DM_BUFIO_CACHE(c)) {
1683 DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
1684 c->block_size,
1685 c->block_size, 0, NULL);
1686 if (!DM_BUFIO_CACHE(c)) {
1687 r = -ENOMEM;
1688 mutex_unlock(&dm_bufio_clients_lock);
1689 goto bad_cache;
1690 }
1691 }
1692 }
1693 mutex_unlock(&dm_bufio_clients_lock);
1694
1695 while (c->need_reserved_buffers) {
1696 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1697
1698 if (!b) {
1699 r = -ENOMEM;
1700 goto bad_buffer;
1701 }
1702 __free_buffer_wake(b);
1703 }
1704
1705 mutex_lock(&dm_bufio_clients_lock);
1706 dm_bufio_client_count++;
1707 list_add(&c->client_list, &dm_bufio_all_clients);
1708 __cache_size_refresh();
1709 mutex_unlock(&dm_bufio_clients_lock);
1710
7dc19d5a
DC
1711 c->shrinker.count_objects = dm_bufio_shrink_count;
1712 c->shrinker.scan_objects = dm_bufio_shrink_scan;
95d402f0
MP
1713 c->shrinker.seeks = 1;
1714 c->shrinker.batch = 0;
1715 register_shrinker(&c->shrinker);
1716
1717 return c;
1718
1719bad_buffer:
1720bad_cache:
1721 while (!list_empty(&c->reserved_buffers)) {
1722 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1723 struct dm_buffer, lru_list);
1724 list_del(&b->lru_list);
1725 free_buffer(b);
1726 }
1727 dm_io_client_destroy(c->dm_io);
1728bad_dm_io:
95d402f0
MP
1729 kfree(c);
1730bad_client:
1731 return ERR_PTR(r);
1732}
1733EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1734
1735/*
1736 * Free the buffering interface.
1737 * It is required that there are no references on any buffers.
1738 */
1739void dm_bufio_client_destroy(struct dm_bufio_client *c)
1740{
1741 unsigned i;
1742
1743 drop_buffers(c);
1744
1745 unregister_shrinker(&c->shrinker);
1746
1747 mutex_lock(&dm_bufio_clients_lock);
1748
1749 list_del(&c->client_list);
1750 dm_bufio_client_count--;
1751 __cache_size_refresh();
1752
1753 mutex_unlock(&dm_bufio_clients_lock);
1754
4e420c45 1755 BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
95d402f0
MP
1756 BUG_ON(c->need_reserved_buffers);
1757
1758 while (!list_empty(&c->reserved_buffers)) {
1759 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1760 struct dm_buffer, lru_list);
1761 list_del(&b->lru_list);
1762 free_buffer(b);
1763 }
1764
1765 for (i = 0; i < LIST_SIZE; i++)
1766 if (c->n_buffers[i])
1767 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1768
1769 for (i = 0; i < LIST_SIZE; i++)
1770 BUG_ON(c->n_buffers[i]);
1771
1772 dm_io_client_destroy(c->dm_io);
95d402f0
MP
1773 kfree(c);
1774}
1775EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1776
33096a78 1777static unsigned get_max_age_hz(void)
95d402f0 1778{
33096a78 1779 unsigned max_age = ACCESS_ONCE(dm_bufio_max_age);
95d402f0 1780
33096a78
JT
1781 if (max_age > UINT_MAX / HZ)
1782 max_age = UINT_MAX / HZ;
95d402f0 1783
33096a78
JT
1784 return max_age * HZ;
1785}
95d402f0 1786
33096a78
JT
1787static bool older_than(struct dm_buffer *b, unsigned long age_hz)
1788{
f495339c 1789 return time_after_eq(jiffies, b->last_accessed + age_hz);
33096a78
JT
1790}
1791
1792static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
1793{
1794 struct dm_buffer *b, *tmp;
1795 unsigned retain_target = get_retain_buffers(c);
1796 unsigned count;
1797
1798 dm_bufio_lock(c);
1799
1800 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1801 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) {
1802 if (count <= retain_target)
1803 break;
1804
1805 if (!older_than(b, age_hz))
1806 break;
1807
1808 if (__try_evict_buffer(b, 0))
1809 count--;
95d402f0 1810
95d402f0
MP
1811 dm_bufio_cond_resched();
1812 }
33096a78
JT
1813
1814 dm_bufio_unlock(c);
1815}
1816
1817static void cleanup_old_buffers(void)
1818{
1819 unsigned long max_age_hz = get_max_age_hz();
1820 struct dm_bufio_client *c;
1821
1822 mutex_lock(&dm_bufio_clients_lock);
1823
1824 list_for_each_entry(c, &dm_bufio_all_clients, client_list)
1825 __evict_old_buffers(c, max_age_hz);
1826
95d402f0
MP
1827 mutex_unlock(&dm_bufio_clients_lock);
1828}
1829
1830static struct workqueue_struct *dm_bufio_wq;
1831static struct delayed_work dm_bufio_work;
1832
1833static void work_fn(struct work_struct *w)
1834{
1835 cleanup_old_buffers();
1836
1837 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1838 DM_BUFIO_WORK_TIMER_SECS * HZ);
1839}
1840
1841/*----------------------------------------------------------------
1842 * Module setup
1843 *--------------------------------------------------------------*/
1844
1845/*
1846 * This is called only once for the whole dm_bufio module.
1847 * It initializes memory limit.
1848 */
1849static int __init dm_bufio_init(void)
1850{
1851 __u64 mem;
1852
4cb57ab4
MP
1853 dm_bufio_allocated_kmem_cache = 0;
1854 dm_bufio_allocated_get_free_pages = 0;
1855 dm_bufio_allocated_vmalloc = 0;
1856 dm_bufio_current_allocated = 0;
1857
95d402f0
MP
1858 memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
1859 memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
1860
1861 mem = (__u64)((totalram_pages - totalhigh_pages) *
1862 DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
1863
1864 if (mem > ULONG_MAX)
1865 mem = ULONG_MAX;
1866
1867#ifdef CONFIG_MMU
1868 /*
1869 * Get the size of vmalloc space the same way as VMALLOC_TOTAL
1870 * in fs/proc/internal.h
1871 */
1872 if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
1873 mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100;
1874#endif
1875
1876 dm_bufio_default_cache_size = mem;
1877
1878 mutex_lock(&dm_bufio_clients_lock);
1879 __cache_size_refresh();
1880 mutex_unlock(&dm_bufio_clients_lock);
1881
edd1ea2a 1882 dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0);
95d402f0
MP
1883 if (!dm_bufio_wq)
1884 return -ENOMEM;
1885
1886 INIT_DELAYED_WORK(&dm_bufio_work, work_fn);
1887 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1888 DM_BUFIO_WORK_TIMER_SECS * HZ);
1889
1890 return 0;
1891}
1892
1893/*
1894 * This is called once when unloading the dm_bufio module.
1895 */
1896static void __exit dm_bufio_exit(void)
1897{
1898 int bug = 0;
1899 int i;
1900
1901 cancel_delayed_work_sync(&dm_bufio_work);
1902 destroy_workqueue(dm_bufio_wq);
1903
6f65985e
JL
1904 for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++)
1905 kmem_cache_destroy(dm_bufio_caches[i]);
95d402f0
MP
1906
1907 for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
1908 kfree(dm_bufio_cache_names[i]);
1909
1910 if (dm_bufio_client_count) {
1911 DMCRIT("%s: dm_bufio_client_count leaked: %d",
1912 __func__, dm_bufio_client_count);
1913 bug = 1;
1914 }
1915
1916 if (dm_bufio_current_allocated) {
1917 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
1918 __func__, dm_bufio_current_allocated);
1919 bug = 1;
1920 }
1921
1922 if (dm_bufio_allocated_get_free_pages) {
1923 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
1924 __func__, dm_bufio_allocated_get_free_pages);
1925 bug = 1;
1926 }
1927
1928 if (dm_bufio_allocated_vmalloc) {
1929 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
1930 __func__, dm_bufio_allocated_vmalloc);
1931 bug = 1;
1932 }
1933
86a49e2d 1934 BUG_ON(bug);
95d402f0
MP
1935}
1936
1937module_init(dm_bufio_init)
1938module_exit(dm_bufio_exit)
1939
1940module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
1941MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
1942
1943module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
1944MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
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1945
1946module_param_named(retain_bytes, dm_bufio_retain_bytes, uint, S_IRUGO | S_IWUSR);
1947MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");
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1948
1949module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
1950MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
1951
1952module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
1953MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
1954
1955module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
1956MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
1957
1958module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
1959MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
1960
1961module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
1962MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
1963
1964MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
1965MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
1966MODULE_LICENSE("GPL");
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