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