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Mikulas Patocka95d402f2011-10-31 20:19:09 +00001/*
2 * Copyright (C) 2009-2011 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * This file is released under the GPL.
7 */
8
9#include "dm-bufio.h"
10
11#include <linux/device-mapper.h>
12#include <linux/dm-io.h>
13#include <linux/slab.h>
Asaf Vertzf4953392015-01-06 15:44:15 +020014#include <linux/jiffies.h>
Mikulas Patocka95d402f2011-10-31 20:19:09 +000015#include <linux/vmalloc.h>
Mikulas Patocka95d402f2011-10-31 20:19:09 +000016#include <linux/shrinker.h>
Stephen Rothwell6f662632011-11-01 18:30:49 +110017#include <linux/module.h>
Joe Thornber4e420c42014-10-06 13:48:51 +010018#include <linux/rbtree.h>
Mikulas Patocka95d402f2011-10-31 20:19:09 +000019
20#define DM_MSG_PREFIX "bufio"
21
22/*
23 * Memory management policy:
24 * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
25 * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
26 * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
27 * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
28 * dirty buffers.
29 */
30#define DM_BUFIO_MIN_BUFFERS 8
31
32#define DM_BUFIO_MEMORY_PERCENT 2
33#define DM_BUFIO_VMALLOC_PERCENT 25
34#define DM_BUFIO_WRITEBACK_PERCENT 75
35
36/*
37 * Check buffer ages in this interval (seconds)
38 */
Joe Thornber33096a72014-10-09 11:10:25 +010039#define DM_BUFIO_WORK_TIMER_SECS 30
Mikulas Patocka95d402f2011-10-31 20:19:09 +000040
41/*
42 * Free buffers when they are older than this (seconds)
43 */
Joe Thornber33096a72014-10-09 11:10:25 +010044#define DM_BUFIO_DEFAULT_AGE_SECS 300
45
46/*
47 * The nr of bytes of cached data to keep around.
48 */
49#define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
Mikulas Patocka95d402f2011-10-31 20:19:09 +000050
51/*
52 * The number of bvec entries that are embedded directly in the buffer.
53 * If the chunk size is larger, dm-io is used to do the io.
54 */
55#define DM_BUFIO_INLINE_VECS 16
56
57/*
Mikulas Patocka95d402f2011-10-31 20:19:09 +000058 * Don't try to use kmem_cache_alloc for blocks larger than this.
59 * For explanation, see alloc_buffer_data below.
60 */
61#define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1)
62#define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1))
63
64/*
65 * dm_buffer->list_mode
66 */
67#define LIST_CLEAN 0
68#define LIST_DIRTY 1
69#define LIST_SIZE 2
70
71/*
72 * Linking of buffers:
73 * All buffers are linked to cache_hash with their hash_list field.
74 *
75 * Clean buffers that are not being written (B_WRITING not set)
76 * are linked to lru[LIST_CLEAN] with their lru_list field.
77 *
78 * Dirty and clean buffers that are being written are linked to
79 * lru[LIST_DIRTY] with their lru_list field. When the write
80 * finishes, the buffer cannot be relinked immediately (because we
81 * are in an interrupt context and relinking requires process
82 * context), so some clean-not-writing buffers can be held on
83 * dirty_lru too. They are later added to lru in the process
84 * context.
85 */
86struct dm_bufio_client {
87 struct mutex lock;
88
89 struct list_head lru[LIST_SIZE];
90 unsigned long n_buffers[LIST_SIZE];
91
92 struct block_device *bdev;
93 unsigned block_size;
94 unsigned char sectors_per_block_bits;
95 unsigned char pages_per_block_bits;
96 unsigned char blocks_per_page_bits;
97 unsigned aux_size;
98 void (*alloc_callback)(struct dm_buffer *);
99 void (*write_callback)(struct dm_buffer *);
100
101 struct dm_io_client *dm_io;
102
103 struct list_head reserved_buffers;
104 unsigned need_reserved_buffers;
105
Mikulas Patocka55b082e2014-01-13 19:13:05 -0500106 unsigned minimum_buffers;
107
Joe Thornber4e420c42014-10-06 13:48:51 +0100108 struct rb_root buffer_tree;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000109 wait_queue_head_t free_buffer_wait;
110
111 int async_write_error;
112
113 struct list_head client_list;
114 struct shrinker shrinker;
115};
116
117/*
118 * Buffer state bits.
119 */
120#define B_READING 0
121#define B_WRITING 1
122#define B_DIRTY 2
123
124/*
125 * Describes how the block was allocated:
126 * kmem_cache_alloc(), __get_free_pages() or vmalloc().
127 * See the comment at alloc_buffer_data.
128 */
129enum data_mode {
130 DATA_MODE_SLAB = 0,
131 DATA_MODE_GET_FREE_PAGES = 1,
132 DATA_MODE_VMALLOC = 2,
133 DATA_MODE_LIMIT = 3
134};
135
136struct dm_buffer {
Joe Thornber4e420c42014-10-06 13:48:51 +0100137 struct rb_node node;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000138 struct list_head lru_list;
139 sector_t block;
140 void *data;
141 enum data_mode data_mode;
142 unsigned char list_mode; /* LIST_* */
143 unsigned hold_count;
144 int read_error;
145 int write_error;
146 unsigned long state;
147 unsigned long last_accessed;
148 struct dm_bufio_client *c;
Mikulas Patocka24809452013-07-10 23:41:18 +0100149 struct list_head write_list;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000150 struct bio bio;
151 struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
152};
153
154/*----------------------------------------------------------------*/
155
156static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
157static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
158
159static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
160{
161 unsigned ret = c->blocks_per_page_bits - 1;
162
163 BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
164
165 return ret;
166}
167
168#define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)])
169#define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)])
170
171#define dm_bufio_in_request() (!!current->bio_list)
172
173static void dm_bufio_lock(struct dm_bufio_client *c)
174{
175 mutex_lock_nested(&c->lock, dm_bufio_in_request());
176}
177
178static int dm_bufio_trylock(struct dm_bufio_client *c)
179{
180 return mutex_trylock(&c->lock);
181}
182
183static void dm_bufio_unlock(struct dm_bufio_client *c)
184{
185 mutex_unlock(&c->lock);
186}
187
188/*
189 * FIXME Move to sched.h?
190 */
191#ifdef CONFIG_PREEMPT_VOLUNTARY
192# define dm_bufio_cond_resched() \
193do { \
194 if (unlikely(need_resched())) \
195 _cond_resched(); \
196} while (0)
197#else
198# define dm_bufio_cond_resched() do { } while (0)
199#endif
200
201/*----------------------------------------------------------------*/
202
203/*
204 * Default cache size: available memory divided by the ratio.
205 */
206static unsigned long dm_bufio_default_cache_size;
207
208/*
209 * Total cache size set by the user.
210 */
211static unsigned long dm_bufio_cache_size;
212
213/*
214 * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
215 * at any time. If it disagrees, the user has changed cache size.
216 */
217static unsigned long dm_bufio_cache_size_latch;
218
219static DEFINE_SPINLOCK(param_spinlock);
220
221/*
222 * Buffers are freed after this timeout
223 */
224static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
Joe Thornber33096a72014-10-09 11:10:25 +0100225static unsigned dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000226
227static unsigned long dm_bufio_peak_allocated;
228static unsigned long dm_bufio_allocated_kmem_cache;
229static unsigned long dm_bufio_allocated_get_free_pages;
230static unsigned long dm_bufio_allocated_vmalloc;
231static unsigned long dm_bufio_current_allocated;
232
233/*----------------------------------------------------------------*/
234
235/*
236 * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
237 */
238static unsigned long dm_bufio_cache_size_per_client;
239
240/*
241 * The current number of clients.
242 */
243static int dm_bufio_client_count;
244
245/*
246 * The list of all clients.
247 */
248static LIST_HEAD(dm_bufio_all_clients);
249
250/*
251 * This mutex protects dm_bufio_cache_size_latch,
252 * dm_bufio_cache_size_per_client and dm_bufio_client_count
253 */
254static DEFINE_MUTEX(dm_bufio_clients_lock);
255
Joe Thornber4e420c42014-10-06 13:48:51 +0100256/*----------------------------------------------------------------
257 * A red/black tree acts as an index for all the buffers.
258 *--------------------------------------------------------------*/
259static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
260{
261 struct rb_node *n = c->buffer_tree.rb_node;
262 struct dm_buffer *b;
263
264 while (n) {
265 b = container_of(n, struct dm_buffer, node);
266
267 if (b->block == block)
268 return b;
269
270 n = (b->block < block) ? n->rb_left : n->rb_right;
271 }
272
273 return NULL;
274}
275
276static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
277{
278 struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
279 struct dm_buffer *found;
280
281 while (*new) {
282 found = container_of(*new, struct dm_buffer, node);
283
284 if (found->block == b->block) {
285 BUG_ON(found != b);
286 return;
287 }
288
289 parent = *new;
290 new = (found->block < b->block) ?
291 &((*new)->rb_left) : &((*new)->rb_right);
292 }
293
294 rb_link_node(&b->node, parent, new);
295 rb_insert_color(&b->node, &c->buffer_tree);
296}
297
298static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
299{
300 rb_erase(&b->node, &c->buffer_tree);
301}
302
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000303/*----------------------------------------------------------------*/
304
305static void adjust_total_allocated(enum data_mode data_mode, long diff)
306{
307 static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
308 &dm_bufio_allocated_kmem_cache,
309 &dm_bufio_allocated_get_free_pages,
310 &dm_bufio_allocated_vmalloc,
311 };
312
313 spin_lock(&param_spinlock);
314
315 *class_ptr[data_mode] += diff;
316
317 dm_bufio_current_allocated += diff;
318
319 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
320 dm_bufio_peak_allocated = dm_bufio_current_allocated;
321
322 spin_unlock(&param_spinlock);
323}
324
325/*
326 * Change the number of clients and recalculate per-client limit.
327 */
328static void __cache_size_refresh(void)
329{
330 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
331 BUG_ON(dm_bufio_client_count < 0);
332
Mikulas Patockafe5fe902012-10-12 16:59:46 +0100333 dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000334
335 /*
336 * Use default if set to 0 and report the actual cache size used.
337 */
338 if (!dm_bufio_cache_size_latch) {
339 (void)cmpxchg(&dm_bufio_cache_size, 0,
340 dm_bufio_default_cache_size);
341 dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
342 }
343
344 dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
345 (dm_bufio_client_count ? : 1);
346}
347
348/*
349 * Allocating buffer data.
350 *
351 * Small buffers are allocated with kmem_cache, to use space optimally.
352 *
353 * For large buffers, we choose between get_free_pages and vmalloc.
354 * Each has advantages and disadvantages.
355 *
356 * __get_free_pages can randomly fail if the memory is fragmented.
357 * __vmalloc won't randomly fail, but vmalloc space is limited (it may be
358 * as low as 128M) so using it for caching is not appropriate.
359 *
360 * If the allocation may fail we use __get_free_pages. Memory fragmentation
361 * won't have a fatal effect here, but it just causes flushes of some other
362 * buffers and more I/O will be performed. Don't use __get_free_pages if it
363 * always fails (i.e. order >= MAX_ORDER).
364 *
365 * If the allocation shouldn't fail we use __vmalloc. This is only for the
366 * initial reserve allocation, so there's no risk of wasting all vmalloc
367 * space.
368 */
369static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
370 enum data_mode *data_mode)
371{
Mikulas Patocka502624b2013-05-10 14:37:15 +0100372 unsigned noio_flag;
373 void *ptr;
374
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000375 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
376 *data_mode = DATA_MODE_SLAB;
377 return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
378 }
379
380 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
381 gfp_mask & __GFP_NORETRY) {
382 *data_mode = DATA_MODE_GET_FREE_PAGES;
383 return (void *)__get_free_pages(gfp_mask,
384 c->pages_per_block_bits);
385 }
386
387 *data_mode = DATA_MODE_VMALLOC;
Mikulas Patocka502624b2013-05-10 14:37:15 +0100388
389 /*
390 * __vmalloc allocates the data pages and auxiliary structures with
391 * gfp_flags that were specified, but pagetables are always allocated
392 * with GFP_KERNEL, no matter what was specified as gfp_mask.
393 *
394 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
395 * all allocations done by this process (including pagetables) are done
396 * as if GFP_NOIO was specified.
397 */
398
399 if (gfp_mask & __GFP_NORETRY)
400 noio_flag = memalloc_noio_save();
401
Mikulas Patocka220cd052013-07-10 23:41:16 +0100402 ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
Mikulas Patocka502624b2013-05-10 14:37:15 +0100403
404 if (gfp_mask & __GFP_NORETRY)
405 memalloc_noio_restore(noio_flag);
406
407 return ptr;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000408}
409
410/*
411 * Free buffer's data.
412 */
413static void free_buffer_data(struct dm_bufio_client *c,
414 void *data, enum data_mode data_mode)
415{
416 switch (data_mode) {
417 case DATA_MODE_SLAB:
418 kmem_cache_free(DM_BUFIO_CACHE(c), data);
419 break;
420
421 case DATA_MODE_GET_FREE_PAGES:
422 free_pages((unsigned long)data, c->pages_per_block_bits);
423 break;
424
425 case DATA_MODE_VMALLOC:
426 vfree(data);
427 break;
428
429 default:
430 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
431 data_mode);
432 BUG();
433 }
434}
435
436/*
437 * Allocate buffer and its data.
438 */
439static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
440{
441 struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
442 gfp_mask);
443
444 if (!b)
445 return NULL;
446
447 b->c = c;
448
449 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
450 if (!b->data) {
451 kfree(b);
452 return NULL;
453 }
454
455 adjust_total_allocated(b->data_mode, (long)c->block_size);
456
457 return b;
458}
459
460/*
461 * Free buffer and its data.
462 */
463static void free_buffer(struct dm_buffer *b)
464{
465 struct dm_bufio_client *c = b->c;
466
467 adjust_total_allocated(b->data_mode, -(long)c->block_size);
468
469 free_buffer_data(c, b->data, b->data_mode);
470 kfree(b);
471}
472
473/*
474 * Link buffer to the hash list and clean or dirty queue.
475 */
476static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
477{
478 struct dm_bufio_client *c = b->c;
479
480 c->n_buffers[dirty]++;
481 b->block = block;
482 b->list_mode = dirty;
483 list_add(&b->lru_list, &c->lru[dirty]);
Joe Thornber4e420c42014-10-06 13:48:51 +0100484 __insert(b->c, b);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000485 b->last_accessed = jiffies;
486}
487
488/*
489 * Unlink buffer from the hash list and dirty or clean queue.
490 */
491static void __unlink_buffer(struct dm_buffer *b)
492{
493 struct dm_bufio_client *c = b->c;
494
495 BUG_ON(!c->n_buffers[b->list_mode]);
496
497 c->n_buffers[b->list_mode]--;
Joe Thornber4e420c42014-10-06 13:48:51 +0100498 __remove(b->c, b);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000499 list_del(&b->lru_list);
500}
501
502/*
503 * Place the buffer to the head of dirty or clean LRU queue.
504 */
505static void __relink_lru(struct dm_buffer *b, int dirty)
506{
507 struct dm_bufio_client *c = b->c;
508
509 BUG_ON(!c->n_buffers[b->list_mode]);
510
511 c->n_buffers[b->list_mode]--;
512 c->n_buffers[dirty]++;
513 b->list_mode = dirty;
Wei Yongjun54499af2012-10-12 16:59:44 +0100514 list_move(&b->lru_list, &c->lru[dirty]);
Joe Thornbereb76faf2014-09-30 09:32:46 +0100515 b->last_accessed = jiffies;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000516}
517
518/*----------------------------------------------------------------
519 * Submit I/O on the buffer.
520 *
521 * Bio interface is faster but it has some problems:
522 * the vector list is limited (increasing this limit increases
523 * memory-consumption per buffer, so it is not viable);
524 *
525 * the memory must be direct-mapped, not vmalloced;
526 *
527 * the I/O driver can reject requests spuriously if it thinks that
528 * the requests are too big for the device or if they cross a
529 * controller-defined memory boundary.
530 *
531 * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
532 * it is not vmalloced, try using the bio interface.
533 *
534 * If the buffer is big, if it is vmalloced or if the underlying device
535 * rejects the bio because it is too large, use dm-io layer to do the I/O.
536 * The dm-io layer splits the I/O into multiple requests, avoiding the above
537 * shortcomings.
538 *--------------------------------------------------------------*/
539
540/*
541 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
542 * that the request was handled directly with bio interface.
543 */
544static void dmio_complete(unsigned long error, void *context)
545{
546 struct dm_buffer *b = context;
547
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200548 b->bio.bi_error = error ? -EIO : 0;
549 b->bio.bi_end_io(&b->bio);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000550}
551
552static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
553 bio_end_io_t *end_io)
554{
555 int r;
556 struct dm_io_request io_req = {
557 .bi_rw = rw,
558 .notify.fn = dmio_complete,
559 .notify.context = b,
560 .client = b->c->dm_io,
561 };
562 struct dm_io_region region = {
563 .bdev = b->c->bdev,
564 .sector = block << b->c->sectors_per_block_bits,
565 .count = b->c->block_size >> SECTOR_SHIFT,
566 };
567
568 if (b->data_mode != DATA_MODE_VMALLOC) {
569 io_req.mem.type = DM_IO_KMEM;
570 io_req.mem.ptr.addr = b->data;
571 } else {
572 io_req.mem.type = DM_IO_VMA;
573 io_req.mem.ptr.vma = b->data;
574 }
575
576 b->bio.bi_end_io = end_io;
577
578 r = dm_io(&io_req, 1, &region, NULL);
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200579 if (r) {
580 b->bio.bi_error = r;
581 end_io(&b->bio);
582 }
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000583}
584
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200585static void inline_endio(struct bio *bio)
Darrick J. Wong445559c2014-11-25 17:45:15 -0800586{
587 bio_end_io_t *end_fn = bio->bi_private;
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200588 int error = bio->bi_error;
Darrick J. Wong445559c2014-11-25 17:45:15 -0800589
590 /*
591 * Reset the bio to free any attached resources
592 * (e.g. bio integrity profiles).
593 */
594 bio_reset(bio);
595
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200596 bio->bi_error = error;
597 end_fn(bio);
Darrick J. Wong445559c2014-11-25 17:45:15 -0800598}
599
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000600static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
601 bio_end_io_t *end_io)
602{
603 char *ptr;
604 int len;
605
606 bio_init(&b->bio);
607 b->bio.bi_io_vec = b->bio_vec;
608 b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
Kent Overstreet4f024f32013-10-11 15:44:27 -0700609 b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000610 b->bio.bi_bdev = b->c->bdev;
Darrick J. Wong445559c2014-11-25 17:45:15 -0800611 b->bio.bi_end_io = inline_endio;
612 /*
613 * Use of .bi_private isn't a problem here because
614 * the dm_buffer's inline bio is local to bufio.
615 */
616 b->bio.bi_private = end_io;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000617
618 /*
619 * We assume that if len >= PAGE_SIZE ptr is page-aligned.
620 * If len < PAGE_SIZE the buffer doesn't cross page boundary.
621 */
622 ptr = b->data;
623 len = b->c->block_size;
624
625 if (len >= PAGE_SIZE)
626 BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
627 else
628 BUG_ON((unsigned long)ptr & (len - 1));
629
630 do {
631 if (!bio_add_page(&b->bio, virt_to_page(ptr),
632 len < PAGE_SIZE ? len : PAGE_SIZE,
633 virt_to_phys(ptr) & (PAGE_SIZE - 1))) {
634 BUG_ON(b->c->block_size <= PAGE_SIZE);
635 use_dmio(b, rw, block, end_io);
636 return;
637 }
638
639 len -= PAGE_SIZE;
640 ptr += PAGE_SIZE;
641 } while (len > 0);
642
643 submit_bio(rw, &b->bio);
644}
645
646static void submit_io(struct dm_buffer *b, int rw, sector_t block,
647 bio_end_io_t *end_io)
648{
649 if (rw == WRITE && b->c->write_callback)
650 b->c->write_callback(b);
651
652 if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
653 b->data_mode != DATA_MODE_VMALLOC)
654 use_inline_bio(b, rw, block, end_io);
655 else
656 use_dmio(b, rw, block, end_io);
657}
658
659/*----------------------------------------------------------------
660 * Writing dirty buffers
661 *--------------------------------------------------------------*/
662
663/*
664 * The endio routine for write.
665 *
666 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
667 * it.
668 */
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200669static void write_endio(struct bio *bio)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000670{
671 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
672
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200673 b->write_error = bio->bi_error;
674 if (unlikely(bio->bi_error)) {
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000675 struct dm_bufio_client *c = b->c;
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200676 int error = bio->bi_error;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000677 (void)cmpxchg(&c->async_write_error, 0, error);
678 }
679
680 BUG_ON(!test_bit(B_WRITING, &b->state));
681
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100682 smp_mb__before_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000683 clear_bit(B_WRITING, &b->state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100684 smp_mb__after_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000685
686 wake_up_bit(&b->state, B_WRITING);
687}
688
689/*
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000690 * Initiate a write on a dirty buffer, but don't wait for it.
691 *
692 * - If the buffer is not dirty, exit.
693 * - If there some previous write going on, wait for it to finish (we can't
694 * have two writes on the same buffer simultaneously).
695 * - Submit our write and don't wait on it. We set B_WRITING indicating
696 * that there is a write in progress.
697 */
Mikulas Patocka24809452013-07-10 23:41:18 +0100698static void __write_dirty_buffer(struct dm_buffer *b,
699 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000700{
701 if (!test_bit(B_DIRTY, &b->state))
702 return;
703
704 clear_bit(B_DIRTY, &b->state);
NeilBrown74316202014-07-07 15:16:04 +1000705 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000706
Mikulas Patocka24809452013-07-10 23:41:18 +0100707 if (!write_list)
708 submit_io(b, WRITE, b->block, write_endio);
709 else
710 list_add_tail(&b->write_list, write_list);
711}
712
713static void __flush_write_list(struct list_head *write_list)
714{
715 struct blk_plug plug;
716 blk_start_plug(&plug);
717 while (!list_empty(write_list)) {
718 struct dm_buffer *b =
719 list_entry(write_list->next, struct dm_buffer, write_list);
720 list_del(&b->write_list);
721 submit_io(b, WRITE, b->block, write_endio);
722 dm_bufio_cond_resched();
723 }
724 blk_finish_plug(&plug);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000725}
726
727/*
728 * Wait until any activity on the buffer finishes. Possibly write the
729 * buffer if it is dirty. When this function finishes, there is no I/O
730 * running on the buffer and the buffer is not dirty.
731 */
732static void __make_buffer_clean(struct dm_buffer *b)
733{
734 BUG_ON(b->hold_count);
735
736 if (!b->state) /* fast case */
737 return;
738
NeilBrown74316202014-07-07 15:16:04 +1000739 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka24809452013-07-10 23:41:18 +0100740 __write_dirty_buffer(b, NULL);
NeilBrown74316202014-07-07 15:16:04 +1000741 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000742}
743
744/*
745 * Find some buffer that is not held by anybody, clean it, unlink it and
746 * return it.
747 */
748static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
749{
750 struct dm_buffer *b;
751
752 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
753 BUG_ON(test_bit(B_WRITING, &b->state));
754 BUG_ON(test_bit(B_DIRTY, &b->state));
755
756 if (!b->hold_count) {
757 __make_buffer_clean(b);
758 __unlink_buffer(b);
759 return b;
760 }
761 dm_bufio_cond_resched();
762 }
763
764 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
765 BUG_ON(test_bit(B_READING, &b->state));
766
767 if (!b->hold_count) {
768 __make_buffer_clean(b);
769 __unlink_buffer(b);
770 return b;
771 }
772 dm_bufio_cond_resched();
773 }
774
775 return NULL;
776}
777
778/*
779 * Wait until some other threads free some buffer or release hold count on
780 * some buffer.
781 *
782 * This function is entered with c->lock held, drops it and regains it
783 * before exiting.
784 */
785static void __wait_for_free_buffer(struct dm_bufio_client *c)
786{
787 DECLARE_WAITQUEUE(wait, current);
788
789 add_wait_queue(&c->free_buffer_wait, &wait);
790 set_task_state(current, TASK_UNINTERRUPTIBLE);
791 dm_bufio_unlock(c);
792
793 io_schedule();
794
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000795 remove_wait_queue(&c->free_buffer_wait, &wait);
796
797 dm_bufio_lock(c);
798}
799
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100800enum new_flag {
801 NF_FRESH = 0,
802 NF_READ = 1,
803 NF_GET = 2,
804 NF_PREFETCH = 3
805};
806
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000807/*
808 * Allocate a new buffer. If the allocation is not possible, wait until
809 * some other thread frees a buffer.
810 *
811 * May drop the lock and regain it.
812 */
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100813static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000814{
815 struct dm_buffer *b;
816
817 /*
818 * dm-bufio is resistant to allocation failures (it just keeps
819 * one buffer reserved in cases all the allocations fail).
820 * So set flags to not try too hard:
821 * GFP_NOIO: don't recurse into the I/O layer
822 * __GFP_NORETRY: don't retry and rather return failure
823 * __GFP_NOMEMALLOC: don't use emergency reserves
824 * __GFP_NOWARN: don't print a warning in case of failure
825 *
826 * For debugging, if we set the cache size to 1, no new buffers will
827 * be allocated.
828 */
829 while (1) {
830 if (dm_bufio_cache_size_latch != 1) {
831 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
832 if (b)
833 return b;
834 }
835
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100836 if (nf == NF_PREFETCH)
837 return NULL;
838
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000839 if (!list_empty(&c->reserved_buffers)) {
840 b = list_entry(c->reserved_buffers.next,
841 struct dm_buffer, lru_list);
842 list_del(&b->lru_list);
843 c->need_reserved_buffers++;
844
845 return b;
846 }
847
848 b = __get_unclaimed_buffer(c);
849 if (b)
850 return b;
851
852 __wait_for_free_buffer(c);
853 }
854}
855
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100856static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000857{
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100858 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
859
860 if (!b)
861 return NULL;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000862
863 if (c->alloc_callback)
864 c->alloc_callback(b);
865
866 return b;
867}
868
869/*
870 * Free a buffer and wake other threads waiting for free buffers.
871 */
872static void __free_buffer_wake(struct dm_buffer *b)
873{
874 struct dm_bufio_client *c = b->c;
875
876 if (!c->need_reserved_buffers)
877 free_buffer(b);
878 else {
879 list_add(&b->lru_list, &c->reserved_buffers);
880 c->need_reserved_buffers--;
881 }
882
883 wake_up(&c->free_buffer_wait);
884}
885
Mikulas Patocka24809452013-07-10 23:41:18 +0100886static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
887 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000888{
889 struct dm_buffer *b, *tmp;
890
891 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
892 BUG_ON(test_bit(B_READING, &b->state));
893
894 if (!test_bit(B_DIRTY, &b->state) &&
895 !test_bit(B_WRITING, &b->state)) {
896 __relink_lru(b, LIST_CLEAN);
897 continue;
898 }
899
900 if (no_wait && test_bit(B_WRITING, &b->state))
901 return;
902
Mikulas Patocka24809452013-07-10 23:41:18 +0100903 __write_dirty_buffer(b, write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000904 dm_bufio_cond_resched();
905 }
906}
907
908/*
909 * Get writeback threshold and buffer limit for a given client.
910 */
911static void __get_memory_limit(struct dm_bufio_client *c,
912 unsigned long *threshold_buffers,
913 unsigned long *limit_buffers)
914{
915 unsigned long buffers;
916
Mikulas Patockafe5fe902012-10-12 16:59:46 +0100917 if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000918 mutex_lock(&dm_bufio_clients_lock);
919 __cache_size_refresh();
920 mutex_unlock(&dm_bufio_clients_lock);
921 }
922
923 buffers = dm_bufio_cache_size_per_client >>
924 (c->sectors_per_block_bits + SECTOR_SHIFT);
925
Mikulas Patocka55b082e2014-01-13 19:13:05 -0500926 if (buffers < c->minimum_buffers)
927 buffers = c->minimum_buffers;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000928
929 *limit_buffers = buffers;
930 *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
931}
932
933/*
934 * Check if we're over watermark.
935 * If we are over threshold_buffers, start freeing buffers.
936 * If we're over "limit_buffers", block until we get under the limit.
937 */
Mikulas Patocka24809452013-07-10 23:41:18 +0100938static void __check_watermark(struct dm_bufio_client *c,
939 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000940{
941 unsigned long threshold_buffers, limit_buffers;
942
943 __get_memory_limit(c, &threshold_buffers, &limit_buffers);
944
945 while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] >
946 limit_buffers) {
947
948 struct dm_buffer *b = __get_unclaimed_buffer(c);
949
950 if (!b)
951 return;
952
953 __free_buffer_wake(b);
954 dm_bufio_cond_resched();
955 }
956
957 if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
Mikulas Patocka24809452013-07-10 23:41:18 +0100958 __write_dirty_buffers_async(c, 1, write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000959}
960
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000961/*----------------------------------------------------------------
962 * Getting a buffer
963 *--------------------------------------------------------------*/
964
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000965static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
Mikulas Patocka24809452013-07-10 23:41:18 +0100966 enum new_flag nf, int *need_submit,
967 struct list_head *write_list)
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000968{
969 struct dm_buffer *b, *new_b = NULL;
970
971 *need_submit = 0;
972
973 b = __find(c, block);
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100974 if (b)
975 goto found_buffer;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000976
977 if (nf == NF_GET)
978 return NULL;
979
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100980 new_b = __alloc_buffer_wait(c, nf);
981 if (!new_b)
982 return NULL;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000983
984 /*
985 * We've had a period where the mutex was unlocked, so need to
986 * recheck the hash table.
987 */
988 b = __find(c, block);
989 if (b) {
990 __free_buffer_wake(new_b);
Mikulas Patockaa66cc282012-03-28 18:41:29 +0100991 goto found_buffer;
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000992 }
993
Mikulas Patocka24809452013-07-10 23:41:18 +0100994 __check_watermark(c, write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +0000995
996 b = new_b;
997 b->hold_count = 1;
998 b->read_error = 0;
999 b->write_error = 0;
1000 __link_buffer(b, block, LIST_CLEAN);
1001
1002 if (nf == NF_FRESH) {
1003 b->state = 0;
1004 return b;
1005 }
1006
1007 b->state = 1 << B_READING;
1008 *need_submit = 1;
1009
1010 return b;
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001011
1012found_buffer:
1013 if (nf == NF_PREFETCH)
1014 return NULL;
1015 /*
1016 * Note: it is essential that we don't wait for the buffer to be
1017 * read if dm_bufio_get function is used. Both dm_bufio_get and
1018 * dm_bufio_prefetch can be used in the driver request routine.
1019 * If the user called both dm_bufio_prefetch and dm_bufio_get on
1020 * the same buffer, it would deadlock if we waited.
1021 */
1022 if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state)))
1023 return NULL;
1024
1025 b->hold_count++;
1026 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
1027 test_bit(B_WRITING, &b->state));
1028 return b;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001029}
1030
1031/*
1032 * The endio routine for reading: set the error, clear the bit and wake up
1033 * anyone waiting on the buffer.
1034 */
Christoph Hellwig4246a0b2015-07-20 15:29:37 +02001035static void read_endio(struct bio *bio)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001036{
1037 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
1038
Christoph Hellwig4246a0b2015-07-20 15:29:37 +02001039 b->read_error = bio->bi_error;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001040
1041 BUG_ON(!test_bit(B_READING, &b->state));
1042
Peter Zijlstra4e857c52014-03-17 18:06:10 +01001043 smp_mb__before_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001044 clear_bit(B_READING, &b->state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +01001045 smp_mb__after_atomic();
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001046
1047 wake_up_bit(&b->state, B_READING);
1048}
1049
1050/*
1051 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
1052 * functions is similar except that dm_bufio_new doesn't read the
1053 * buffer from the disk (assuming that the caller overwrites all the data
1054 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1055 */
1056static void *new_read(struct dm_bufio_client *c, sector_t block,
1057 enum new_flag nf, struct dm_buffer **bp)
1058{
1059 int need_submit;
1060 struct dm_buffer *b;
1061
Mikulas Patocka24809452013-07-10 23:41:18 +01001062 LIST_HEAD(write_list);
1063
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001064 dm_bufio_lock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001065 b = __bufio_new(c, block, nf, &need_submit, &write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001066 dm_bufio_unlock(c);
1067
Mikulas Patocka24809452013-07-10 23:41:18 +01001068 __flush_write_list(&write_list);
1069
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001070 if (!b)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001071 return b;
1072
1073 if (need_submit)
1074 submit_io(b, READ, b->block, read_endio);
1075
NeilBrown74316202014-07-07 15:16:04 +10001076 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001077
1078 if (b->read_error) {
1079 int error = b->read_error;
1080
1081 dm_bufio_release(b);
1082
1083 return ERR_PTR(error);
1084 }
1085
1086 *bp = b;
1087
1088 return b->data;
1089}
1090
1091void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1092 struct dm_buffer **bp)
1093{
1094 return new_read(c, block, NF_GET, bp);
1095}
1096EXPORT_SYMBOL_GPL(dm_bufio_get);
1097
1098void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1099 struct dm_buffer **bp)
1100{
1101 BUG_ON(dm_bufio_in_request());
1102
1103 return new_read(c, block, NF_READ, bp);
1104}
1105EXPORT_SYMBOL_GPL(dm_bufio_read);
1106
1107void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1108 struct dm_buffer **bp)
1109{
1110 BUG_ON(dm_bufio_in_request());
1111
1112 return new_read(c, block, NF_FRESH, bp);
1113}
1114EXPORT_SYMBOL_GPL(dm_bufio_new);
1115
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001116void dm_bufio_prefetch(struct dm_bufio_client *c,
1117 sector_t block, unsigned n_blocks)
1118{
1119 struct blk_plug plug;
1120
Mikulas Patocka24809452013-07-10 23:41:18 +01001121 LIST_HEAD(write_list);
1122
Mikulas Patocka3b6b7812013-03-20 17:21:25 +00001123 BUG_ON(dm_bufio_in_request());
1124
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001125 blk_start_plug(&plug);
1126 dm_bufio_lock(c);
1127
1128 for (; n_blocks--; block++) {
1129 int need_submit;
1130 struct dm_buffer *b;
Mikulas Patocka24809452013-07-10 23:41:18 +01001131 b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
1132 &write_list);
1133 if (unlikely(!list_empty(&write_list))) {
1134 dm_bufio_unlock(c);
1135 blk_finish_plug(&plug);
1136 __flush_write_list(&write_list);
1137 blk_start_plug(&plug);
1138 dm_bufio_lock(c);
1139 }
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001140 if (unlikely(b != NULL)) {
1141 dm_bufio_unlock(c);
1142
1143 if (need_submit)
1144 submit_io(b, READ, b->block, read_endio);
1145 dm_bufio_release(b);
1146
1147 dm_bufio_cond_resched();
1148
1149 if (!n_blocks)
1150 goto flush_plug;
1151 dm_bufio_lock(c);
1152 }
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001153 }
1154
1155 dm_bufio_unlock(c);
1156
1157flush_plug:
1158 blk_finish_plug(&plug);
1159}
1160EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1161
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001162void dm_bufio_release(struct dm_buffer *b)
1163{
1164 struct dm_bufio_client *c = b->c;
1165
1166 dm_bufio_lock(c);
1167
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001168 BUG_ON(!b->hold_count);
1169
1170 b->hold_count--;
1171 if (!b->hold_count) {
1172 wake_up(&c->free_buffer_wait);
1173
1174 /*
1175 * If there were errors on the buffer, and the buffer is not
1176 * to be written, free the buffer. There is no point in caching
1177 * invalid buffer.
1178 */
1179 if ((b->read_error || b->write_error) &&
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001180 !test_bit(B_READING, &b->state) &&
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001181 !test_bit(B_WRITING, &b->state) &&
1182 !test_bit(B_DIRTY, &b->state)) {
1183 __unlink_buffer(b);
1184 __free_buffer_wake(b);
1185 }
1186 }
1187
1188 dm_bufio_unlock(c);
1189}
1190EXPORT_SYMBOL_GPL(dm_bufio_release);
1191
1192void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1193{
1194 struct dm_bufio_client *c = b->c;
1195
1196 dm_bufio_lock(c);
1197
Mikulas Patockaa66cc282012-03-28 18:41:29 +01001198 BUG_ON(test_bit(B_READING, &b->state));
1199
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001200 if (!test_and_set_bit(B_DIRTY, &b->state))
1201 __relink_lru(b, LIST_DIRTY);
1202
1203 dm_bufio_unlock(c);
1204}
1205EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1206
1207void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1208{
Mikulas Patocka24809452013-07-10 23:41:18 +01001209 LIST_HEAD(write_list);
1210
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001211 BUG_ON(dm_bufio_in_request());
1212
1213 dm_bufio_lock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001214 __write_dirty_buffers_async(c, 0, &write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001215 dm_bufio_unlock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001216 __flush_write_list(&write_list);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001217}
1218EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1219
1220/*
1221 * For performance, it is essential that the buffers are written asynchronously
1222 * and simultaneously (so that the block layer can merge the writes) and then
1223 * waited upon.
1224 *
1225 * Finally, we flush hardware disk cache.
1226 */
1227int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1228{
1229 int a, f;
1230 unsigned long buffers_processed = 0;
1231 struct dm_buffer *b, *tmp;
1232
Mikulas Patocka24809452013-07-10 23:41:18 +01001233 LIST_HEAD(write_list);
1234
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001235 dm_bufio_lock(c);
Mikulas Patocka24809452013-07-10 23:41:18 +01001236 __write_dirty_buffers_async(c, 0, &write_list);
1237 dm_bufio_unlock(c);
1238 __flush_write_list(&write_list);
1239 dm_bufio_lock(c);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001240
1241again:
1242 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1243 int dropped_lock = 0;
1244
1245 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1246 buffers_processed++;
1247
1248 BUG_ON(test_bit(B_READING, &b->state));
1249
1250 if (test_bit(B_WRITING, &b->state)) {
1251 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1252 dropped_lock = 1;
1253 b->hold_count++;
1254 dm_bufio_unlock(c);
NeilBrown74316202014-07-07 15:16:04 +10001255 wait_on_bit_io(&b->state, B_WRITING,
1256 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001257 dm_bufio_lock(c);
1258 b->hold_count--;
1259 } else
NeilBrown74316202014-07-07 15:16:04 +10001260 wait_on_bit_io(&b->state, B_WRITING,
1261 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001262 }
1263
1264 if (!test_bit(B_DIRTY, &b->state) &&
1265 !test_bit(B_WRITING, &b->state))
1266 __relink_lru(b, LIST_CLEAN);
1267
1268 dm_bufio_cond_resched();
1269
1270 /*
1271 * If we dropped the lock, the list is no longer consistent,
1272 * so we must restart the search.
1273 *
1274 * In the most common case, the buffer just processed is
1275 * relinked to the clean list, so we won't loop scanning the
1276 * same buffer again and again.
1277 *
1278 * This may livelock if there is another thread simultaneously
1279 * dirtying buffers, so we count the number of buffers walked
1280 * and if it exceeds the total number of buffers, it means that
1281 * someone is doing some writes simultaneously with us. In
1282 * this case, stop, dropping the lock.
1283 */
1284 if (dropped_lock)
1285 goto again;
1286 }
1287 wake_up(&c->free_buffer_wait);
1288 dm_bufio_unlock(c);
1289
1290 a = xchg(&c->async_write_error, 0);
1291 f = dm_bufio_issue_flush(c);
1292 if (a)
1293 return a;
1294
1295 return f;
1296}
1297EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1298
1299/*
1300 * Use dm-io to send and empty barrier flush the device.
1301 */
1302int dm_bufio_issue_flush(struct dm_bufio_client *c)
1303{
1304 struct dm_io_request io_req = {
Mikulas Patocka3daec3b2013-03-01 22:45:45 +00001305 .bi_rw = WRITE_FLUSH,
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001306 .mem.type = DM_IO_KMEM,
1307 .mem.ptr.addr = NULL,
1308 .client = c->dm_io,
1309 };
1310 struct dm_io_region io_reg = {
1311 .bdev = c->bdev,
1312 .sector = 0,
1313 .count = 0,
1314 };
1315
1316 BUG_ON(dm_bufio_in_request());
1317
1318 return dm_io(&io_req, 1, &io_reg, NULL);
1319}
1320EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1321
1322/*
1323 * We first delete any other buffer that may be at that new location.
1324 *
1325 * Then, we write the buffer to the original location if it was dirty.
1326 *
1327 * Then, if we are the only one who is holding the buffer, relink the buffer
1328 * in the hash queue for the new location.
1329 *
1330 * If there was someone else holding the buffer, we write it to the new
1331 * location but not relink it, because that other user needs to have the buffer
1332 * at the same place.
1333 */
1334void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1335{
1336 struct dm_bufio_client *c = b->c;
1337 struct dm_buffer *new;
1338
1339 BUG_ON(dm_bufio_in_request());
1340
1341 dm_bufio_lock(c);
1342
1343retry:
1344 new = __find(c, new_block);
1345 if (new) {
1346 if (new->hold_count) {
1347 __wait_for_free_buffer(c);
1348 goto retry;
1349 }
1350
1351 /*
1352 * FIXME: Is there any point waiting for a write that's going
1353 * to be overwritten in a bit?
1354 */
1355 __make_buffer_clean(new);
1356 __unlink_buffer(new);
1357 __free_buffer_wake(new);
1358 }
1359
1360 BUG_ON(!b->hold_count);
1361 BUG_ON(test_bit(B_READING, &b->state));
1362
Mikulas Patocka24809452013-07-10 23:41:18 +01001363 __write_dirty_buffer(b, NULL);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001364 if (b->hold_count == 1) {
NeilBrown74316202014-07-07 15:16:04 +10001365 wait_on_bit_io(&b->state, B_WRITING,
1366 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001367 set_bit(B_DIRTY, &b->state);
1368 __unlink_buffer(b);
1369 __link_buffer(b, new_block, LIST_DIRTY);
1370 } else {
1371 sector_t old_block;
NeilBrown74316202014-07-07 15:16:04 +10001372 wait_on_bit_lock_io(&b->state, B_WRITING,
1373 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001374 /*
1375 * Relink buffer to "new_block" so that write_callback
1376 * sees "new_block" as a block number.
1377 * After the write, link the buffer back to old_block.
1378 * All this must be done in bufio lock, so that block number
1379 * change isn't visible to other threads.
1380 */
1381 old_block = b->block;
1382 __unlink_buffer(b);
1383 __link_buffer(b, new_block, b->list_mode);
1384 submit_io(b, WRITE, new_block, write_endio);
NeilBrown74316202014-07-07 15:16:04 +10001385 wait_on_bit_io(&b->state, B_WRITING,
1386 TASK_UNINTERRUPTIBLE);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001387 __unlink_buffer(b);
1388 __link_buffer(b, old_block, b->list_mode);
1389 }
1390
1391 dm_bufio_unlock(c);
1392 dm_bufio_release(b);
1393}
1394EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1395
Mikulas Patocka55494bf2014-01-13 19:12:36 -05001396/*
1397 * Free the given buffer.
1398 *
1399 * This is just a hint, if the buffer is in use or dirty, this function
1400 * does nothing.
1401 */
1402void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
1403{
1404 struct dm_buffer *b;
1405
1406 dm_bufio_lock(c);
1407
1408 b = __find(c, block);
1409 if (b && likely(!b->hold_count) && likely(!b->state)) {
1410 __unlink_buffer(b);
1411 __free_buffer_wake(b);
1412 }
1413
1414 dm_bufio_unlock(c);
1415}
1416EXPORT_SYMBOL(dm_bufio_forget);
1417
Mikulas Patocka55b082e2014-01-13 19:13:05 -05001418void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
1419{
1420 c->minimum_buffers = n;
1421}
1422EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
1423
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001424unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1425{
1426 return c->block_size;
1427}
1428EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1429
1430sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1431{
1432 return i_size_read(c->bdev->bd_inode) >>
1433 (SECTOR_SHIFT + c->sectors_per_block_bits);
1434}
1435EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1436
1437sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1438{
1439 return b->block;
1440}
1441EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1442
1443void *dm_bufio_get_block_data(struct dm_buffer *b)
1444{
1445 return b->data;
1446}
1447EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1448
1449void *dm_bufio_get_aux_data(struct dm_buffer *b)
1450{
1451 return b + 1;
1452}
1453EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1454
1455struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1456{
1457 return b->c;
1458}
1459EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1460
1461static void drop_buffers(struct dm_bufio_client *c)
1462{
1463 struct dm_buffer *b;
1464 int i;
1465
1466 BUG_ON(dm_bufio_in_request());
1467
1468 /*
1469 * An optimization so that the buffers are not written one-by-one.
1470 */
1471 dm_bufio_write_dirty_buffers_async(c);
1472
1473 dm_bufio_lock(c);
1474
1475 while ((b = __get_unclaimed_buffer(c)))
1476 __free_buffer_wake(b);
1477
1478 for (i = 0; i < LIST_SIZE; i++)
1479 list_for_each_entry(b, &c->lru[i], lru_list)
1480 DMERR("leaked buffer %llx, hold count %u, list %d",
1481 (unsigned long long)b->block, b->hold_count, i);
1482
1483 for (i = 0; i < LIST_SIZE; i++)
1484 BUG_ON(!list_empty(&c->lru[i]));
1485
1486 dm_bufio_unlock(c);
1487}
1488
1489/*
Joe Thornber33096a72014-10-09 11:10:25 +01001490 * We may not be able to evict this buffer if IO pending or the client
1491 * is still using it. Caller is expected to know buffer is too old.
1492 *
Mikulas Patocka9d28eb12014-10-16 14:45:20 -04001493 * And if GFP_NOFS is used, we must not do any I/O because we hold
1494 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
1495 * rerouted to different bufio client.
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001496 */
Joe Thornber33096a72014-10-09 11:10:25 +01001497static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001498{
Mikulas Patocka9d28eb12014-10-16 14:45:20 -04001499 if (!(gfp & __GFP_FS)) {
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001500 if (test_bit(B_READING, &b->state) ||
1501 test_bit(B_WRITING, &b->state) ||
1502 test_bit(B_DIRTY, &b->state))
Joe Thornber33096a72014-10-09 11:10:25 +01001503 return false;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001504 }
1505
1506 if (b->hold_count)
Joe Thornber33096a72014-10-09 11:10:25 +01001507 return false;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001508
1509 __make_buffer_clean(b);
1510 __unlink_buffer(b);
1511 __free_buffer_wake(b);
1512
Joe Thornber33096a72014-10-09 11:10:25 +01001513 return true;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001514}
1515
Joe Thornber33096a72014-10-09 11:10:25 +01001516static unsigned get_retain_buffers(struct dm_bufio_client *c)
1517{
1518 unsigned retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);
1519 return retain_bytes / c->block_size;
1520}
1521
1522static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
1523 gfp_t gfp_mask)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001524{
1525 int l;
1526 struct dm_buffer *b, *tmp;
Joe Thornber33096a72014-10-09 11:10:25 +01001527 unsigned long freed = 0;
1528 unsigned long count = nr_to_scan;
1529 unsigned retain_target = get_retain_buffers(c);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001530
1531 for (l = 0; l < LIST_SIZE; l++) {
Dave Chinner7dc19d52013-08-28 10:18:11 +10001532 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
Joe Thornber33096a72014-10-09 11:10:25 +01001533 if (__try_evict_buffer(b, gfp_mask))
1534 freed++;
1535 if (!--nr_to_scan || ((count - freed) <= retain_target))
Mikulas Patocka0e825862014-10-01 13:29:48 -04001536 return freed;
1537 dm_bufio_cond_resched();
Dave Chinner7dc19d52013-08-28 10:18:11 +10001538 }
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001539 }
Dave Chinner7dc19d52013-08-28 10:18:11 +10001540 return freed;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001541}
1542
Dave Chinner7dc19d52013-08-28 10:18:11 +10001543static unsigned long
1544dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001545{
Dave Chinner7dc19d52013-08-28 10:18:11 +10001546 struct dm_bufio_client *c;
1547 unsigned long freed;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001548
Dave Chinner7dc19d52013-08-28 10:18:11 +10001549 c = container_of(shrink, struct dm_bufio_client, shrinker);
Mikulas Patocka9d28eb12014-10-16 14:45:20 -04001550 if (sc->gfp_mask & __GFP_FS)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001551 dm_bufio_lock(c);
1552 else if (!dm_bufio_trylock(c))
Dave Chinner7dc19d52013-08-28 10:18:11 +10001553 return SHRINK_STOP;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001554
Dave Chinner7dc19d52013-08-28 10:18:11 +10001555 freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001556 dm_bufio_unlock(c);
Dave Chinner7dc19d52013-08-28 10:18:11 +10001557 return freed;
1558}
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001559
Dave Chinner7dc19d52013-08-28 10:18:11 +10001560static unsigned long
1561dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1562{
1563 struct dm_bufio_client *c;
1564 unsigned long count;
1565
1566 c = container_of(shrink, struct dm_bufio_client, shrinker);
Mikulas Patocka9d28eb12014-10-16 14:45:20 -04001567 if (sc->gfp_mask & __GFP_FS)
Dave Chinner7dc19d52013-08-28 10:18:11 +10001568 dm_bufio_lock(c);
1569 else if (!dm_bufio_trylock(c))
1570 return 0;
1571
1572 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1573 dm_bufio_unlock(c);
1574 return count;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001575}
1576
1577/*
1578 * Create the buffering interface
1579 */
1580struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1581 unsigned reserved_buffers, unsigned aux_size,
1582 void (*alloc_callback)(struct dm_buffer *),
1583 void (*write_callback)(struct dm_buffer *))
1584{
1585 int r;
1586 struct dm_bufio_client *c;
1587 unsigned i;
1588
1589 BUG_ON(block_size < 1 << SECTOR_SHIFT ||
1590 (block_size & (block_size - 1)));
1591
Greg Thelend8c712e2014-07-31 09:07:19 -07001592 c = kzalloc(sizeof(*c), GFP_KERNEL);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001593 if (!c) {
1594 r = -ENOMEM;
1595 goto bad_client;
1596 }
Joe Thornber4e420c42014-10-06 13:48:51 +01001597 c->buffer_tree = RB_ROOT;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001598
1599 c->bdev = bdev;
1600 c->block_size = block_size;
Mikulas Patockaa3d939a2015-10-02 11:21:24 -04001601 c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
1602 c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ?
1603 __ffs(block_size) - PAGE_SHIFT : 0;
1604 c->blocks_per_page_bits = (__ffs(block_size) < PAGE_SHIFT ?
1605 PAGE_SHIFT - __ffs(block_size) : 0);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001606
1607 c->aux_size = aux_size;
1608 c->alloc_callback = alloc_callback;
1609 c->write_callback = write_callback;
1610
1611 for (i = 0; i < LIST_SIZE; i++) {
1612 INIT_LIST_HEAD(&c->lru[i]);
1613 c->n_buffers[i] = 0;
1614 }
1615
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001616 mutex_init(&c->lock);
1617 INIT_LIST_HEAD(&c->reserved_buffers);
1618 c->need_reserved_buffers = reserved_buffers;
1619
Mikulas Patocka55b082e2014-01-13 19:13:05 -05001620 c->minimum_buffers = DM_BUFIO_MIN_BUFFERS;
1621
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001622 init_waitqueue_head(&c->free_buffer_wait);
1623 c->async_write_error = 0;
1624
1625 c->dm_io = dm_io_client_create();
1626 if (IS_ERR(c->dm_io)) {
1627 r = PTR_ERR(c->dm_io);
1628 goto bad_dm_io;
1629 }
1630
1631 mutex_lock(&dm_bufio_clients_lock);
1632 if (c->blocks_per_page_bits) {
1633 if (!DM_BUFIO_CACHE_NAME(c)) {
1634 DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
1635 if (!DM_BUFIO_CACHE_NAME(c)) {
1636 r = -ENOMEM;
1637 mutex_unlock(&dm_bufio_clients_lock);
1638 goto bad_cache;
1639 }
1640 }
1641
1642 if (!DM_BUFIO_CACHE(c)) {
1643 DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
1644 c->block_size,
1645 c->block_size, 0, NULL);
1646 if (!DM_BUFIO_CACHE(c)) {
1647 r = -ENOMEM;
1648 mutex_unlock(&dm_bufio_clients_lock);
1649 goto bad_cache;
1650 }
1651 }
1652 }
1653 mutex_unlock(&dm_bufio_clients_lock);
1654
1655 while (c->need_reserved_buffers) {
1656 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1657
1658 if (!b) {
1659 r = -ENOMEM;
1660 goto bad_buffer;
1661 }
1662 __free_buffer_wake(b);
1663 }
1664
1665 mutex_lock(&dm_bufio_clients_lock);
1666 dm_bufio_client_count++;
1667 list_add(&c->client_list, &dm_bufio_all_clients);
1668 __cache_size_refresh();
1669 mutex_unlock(&dm_bufio_clients_lock);
1670
Dave Chinner7dc19d52013-08-28 10:18:11 +10001671 c->shrinker.count_objects = dm_bufio_shrink_count;
1672 c->shrinker.scan_objects = dm_bufio_shrink_scan;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001673 c->shrinker.seeks = 1;
1674 c->shrinker.batch = 0;
1675 register_shrinker(&c->shrinker);
1676
1677 return c;
1678
1679bad_buffer:
1680bad_cache:
1681 while (!list_empty(&c->reserved_buffers)) {
1682 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1683 struct dm_buffer, lru_list);
1684 list_del(&b->lru_list);
1685 free_buffer(b);
1686 }
1687 dm_io_client_destroy(c->dm_io);
1688bad_dm_io:
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001689 kfree(c);
1690bad_client:
1691 return ERR_PTR(r);
1692}
1693EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1694
1695/*
1696 * Free the buffering interface.
1697 * It is required that there are no references on any buffers.
1698 */
1699void dm_bufio_client_destroy(struct dm_bufio_client *c)
1700{
1701 unsigned i;
1702
1703 drop_buffers(c);
1704
1705 unregister_shrinker(&c->shrinker);
1706
1707 mutex_lock(&dm_bufio_clients_lock);
1708
1709 list_del(&c->client_list);
1710 dm_bufio_client_count--;
1711 __cache_size_refresh();
1712
1713 mutex_unlock(&dm_bufio_clients_lock);
1714
Joe Thornber4e420c42014-10-06 13:48:51 +01001715 BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001716 BUG_ON(c->need_reserved_buffers);
1717
1718 while (!list_empty(&c->reserved_buffers)) {
1719 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1720 struct dm_buffer, lru_list);
1721 list_del(&b->lru_list);
1722 free_buffer(b);
1723 }
1724
1725 for (i = 0; i < LIST_SIZE; i++)
1726 if (c->n_buffers[i])
1727 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1728
1729 for (i = 0; i < LIST_SIZE; i++)
1730 BUG_ON(c->n_buffers[i]);
1731
1732 dm_io_client_destroy(c->dm_io);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001733 kfree(c);
1734}
1735EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1736
Joe Thornber33096a72014-10-09 11:10:25 +01001737static unsigned get_max_age_hz(void)
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001738{
Joe Thornber33096a72014-10-09 11:10:25 +01001739 unsigned max_age = ACCESS_ONCE(dm_bufio_max_age);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001740
Joe Thornber33096a72014-10-09 11:10:25 +01001741 if (max_age > UINT_MAX / HZ)
1742 max_age = UINT_MAX / HZ;
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001743
Joe Thornber33096a72014-10-09 11:10:25 +01001744 return max_age * HZ;
1745}
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001746
Joe Thornber33096a72014-10-09 11:10:25 +01001747static bool older_than(struct dm_buffer *b, unsigned long age_hz)
1748{
Asaf Vertzf4953392015-01-06 15:44:15 +02001749 return time_after_eq(jiffies, b->last_accessed + age_hz);
Joe Thornber33096a72014-10-09 11:10:25 +01001750}
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001751
Joe Thornber33096a72014-10-09 11:10:25 +01001752static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
1753{
1754 struct dm_buffer *b, *tmp;
1755 unsigned retain_target = get_retain_buffers(c);
1756 unsigned count;
1757
1758 dm_bufio_lock(c);
1759
1760 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1761 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) {
1762 if (count <= retain_target)
1763 break;
1764
1765 if (!older_than(b, age_hz))
1766 break;
1767
1768 if (__try_evict_buffer(b, 0))
1769 count--;
1770
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001771 dm_bufio_cond_resched();
1772 }
Joe Thornber33096a72014-10-09 11:10:25 +01001773
1774 dm_bufio_unlock(c);
1775}
1776
1777static void cleanup_old_buffers(void)
1778{
1779 unsigned long max_age_hz = get_max_age_hz();
1780 struct dm_bufio_client *c;
1781
1782 mutex_lock(&dm_bufio_clients_lock);
1783
1784 list_for_each_entry(c, &dm_bufio_all_clients, client_list)
1785 __evict_old_buffers(c, max_age_hz);
1786
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001787 mutex_unlock(&dm_bufio_clients_lock);
1788}
1789
1790static struct workqueue_struct *dm_bufio_wq;
1791static struct delayed_work dm_bufio_work;
1792
1793static void work_fn(struct work_struct *w)
1794{
1795 cleanup_old_buffers();
1796
1797 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1798 DM_BUFIO_WORK_TIMER_SECS * HZ);
1799}
1800
1801/*----------------------------------------------------------------
1802 * Module setup
1803 *--------------------------------------------------------------*/
1804
1805/*
1806 * This is called only once for the whole dm_bufio module.
1807 * It initializes memory limit.
1808 */
1809static int __init dm_bufio_init(void)
1810{
1811 __u64 mem;
1812
Mikulas Patocka4cb57ab2013-12-05 17:33:29 -05001813 dm_bufio_allocated_kmem_cache = 0;
1814 dm_bufio_allocated_get_free_pages = 0;
1815 dm_bufio_allocated_vmalloc = 0;
1816 dm_bufio_current_allocated = 0;
1817
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001818 memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
1819 memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
1820
1821 mem = (__u64)((totalram_pages - totalhigh_pages) *
1822 DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
1823
1824 if (mem > ULONG_MAX)
1825 mem = ULONG_MAX;
1826
1827#ifdef CONFIG_MMU
1828 /*
1829 * Get the size of vmalloc space the same way as VMALLOC_TOTAL
1830 * in fs/proc/internal.h
1831 */
1832 if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
1833 mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100;
1834#endif
1835
1836 dm_bufio_default_cache_size = mem;
1837
1838 mutex_lock(&dm_bufio_clients_lock);
1839 __cache_size_refresh();
1840 mutex_unlock(&dm_bufio_clients_lock);
1841
1842 dm_bufio_wq = create_singlethread_workqueue("dm_bufio_cache");
1843 if (!dm_bufio_wq)
1844 return -ENOMEM;
1845
1846 INIT_DELAYED_WORK(&dm_bufio_work, work_fn);
1847 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1848 DM_BUFIO_WORK_TIMER_SECS * HZ);
1849
1850 return 0;
1851}
1852
1853/*
1854 * This is called once when unloading the dm_bufio module.
1855 */
1856static void __exit dm_bufio_exit(void)
1857{
1858 int bug = 0;
1859 int i;
1860
1861 cancel_delayed_work_sync(&dm_bufio_work);
1862 destroy_workqueue(dm_bufio_wq);
1863
Julia Lawall6f659852015-09-13 14:15:05 +02001864 for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++)
1865 kmem_cache_destroy(dm_bufio_caches[i]);
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001866
1867 for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
1868 kfree(dm_bufio_cache_names[i]);
1869
1870 if (dm_bufio_client_count) {
1871 DMCRIT("%s: dm_bufio_client_count leaked: %d",
1872 __func__, dm_bufio_client_count);
1873 bug = 1;
1874 }
1875
1876 if (dm_bufio_current_allocated) {
1877 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
1878 __func__, dm_bufio_current_allocated);
1879 bug = 1;
1880 }
1881
1882 if (dm_bufio_allocated_get_free_pages) {
1883 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
1884 __func__, dm_bufio_allocated_get_free_pages);
1885 bug = 1;
1886 }
1887
1888 if (dm_bufio_allocated_vmalloc) {
1889 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
1890 __func__, dm_bufio_allocated_vmalloc);
1891 bug = 1;
1892 }
1893
1894 if (bug)
1895 BUG();
1896}
1897
1898module_init(dm_bufio_init)
1899module_exit(dm_bufio_exit)
1900
1901module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
1902MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
1903
1904module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
1905MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
1906
Joe Thornber33096a72014-10-09 11:10:25 +01001907module_param_named(retain_bytes, dm_bufio_retain_bytes, uint, S_IRUGO | S_IWUSR);
1908MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");
1909
Mikulas Patocka95d402f2011-10-31 20:19:09 +00001910module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
1911MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
1912
1913module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
1914MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
1915
1916module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
1917MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
1918
1919module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
1920MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
1921
1922module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
1923MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
1924
1925MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
1926MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
1927MODULE_LICENSE("GPL");