2 * Copyright (C) 2009-2011 Red Hat, Inc.
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 * This file is released under the GPL.
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 #include <linux/rbtree.h>
19 #define DM_MSG_PREFIX "bufio"
22 * Memory management policy:
23 * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
24 * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
25 * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
26 * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
29 #define DM_BUFIO_MIN_BUFFERS 8
31 #define DM_BUFIO_MEMORY_PERCENT 2
32 #define DM_BUFIO_VMALLOC_PERCENT 25
33 #define DM_BUFIO_WRITEBACK_PERCENT 75
36 * Check buffer ages in this interval (seconds)
38 #define DM_BUFIO_WORK_TIMER_SECS 30
41 * Free buffers when they are older than this (seconds)
43 #define DM_BUFIO_DEFAULT_AGE_SECS 300
46 * The nr of bytes of cached data to keep around.
48 #define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
51 * The number of bvec entries that are embedded directly in the buffer.
52 * If the chunk size is larger, dm-io is used to do the io.
54 #define DM_BUFIO_INLINE_VECS 16
57 * Don't try to use kmem_cache_alloc for blocks larger than this.
58 * For explanation, see alloc_buffer_data below.
60 #define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1)
61 #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1))
64 * dm_buffer->list_mode
72 * All buffers are linked to cache_hash with their hash_list field.
74 * Clean buffers that are not being written (B_WRITING not set)
75 * are linked to lru[LIST_CLEAN] with their lru_list field.
77 * Dirty and clean buffers that are being written are linked to
78 * lru[LIST_DIRTY] with their lru_list field. When the write
79 * finishes, the buffer cannot be relinked immediately (because we
80 * are in an interrupt context and relinking requires process
81 * context), so some clean-not-writing buffers can be held on
82 * dirty_lru too. They are later added to lru in the process
85 struct dm_bufio_client {
88 struct list_head lru[LIST_SIZE];
89 unsigned long n_buffers[LIST_SIZE];
91 struct block_device *bdev;
93 unsigned char sectors_per_block_bits;
94 unsigned char pages_per_block_bits;
95 unsigned char blocks_per_page_bits;
97 void (*alloc_callback)(struct dm_buffer *);
98 void (*write_callback)(struct dm_buffer *);
100 struct dm_io_client *dm_io;
102 struct list_head reserved_buffers;
103 unsigned need_reserved_buffers;
105 unsigned minimum_buffers;
107 struct rb_root buffer_tree;
108 wait_queue_head_t free_buffer_wait;
110 int async_write_error;
112 struct list_head client_list;
113 struct shrinker shrinker;
124 * Describes how the block was allocated:
125 * kmem_cache_alloc(), __get_free_pages() or vmalloc().
126 * See the comment at alloc_buffer_data.
130 DATA_MODE_GET_FREE_PAGES = 1,
131 DATA_MODE_VMALLOC = 2,
137 struct list_head lru_list;
140 enum data_mode data_mode;
141 unsigned char list_mode; /* LIST_* */
146 unsigned long last_accessed;
147 struct dm_bufio_client *c;
148 struct list_head write_list;
150 struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
153 /*----------------------------------------------------------------*/
155 static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
156 static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
158 static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
160 unsigned ret = c->blocks_per_page_bits - 1;
162 BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
167 #define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)])
168 #define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)])
170 #define dm_bufio_in_request() (!!current->bio_list)
172 static void dm_bufio_lock(struct dm_bufio_client *c)
174 mutex_lock_nested(&c->lock, dm_bufio_in_request());
177 static int dm_bufio_trylock(struct dm_bufio_client *c)
179 return mutex_trylock(&c->lock);
182 static void dm_bufio_unlock(struct dm_bufio_client *c)
184 mutex_unlock(&c->lock);
188 * FIXME Move to sched.h?
190 #ifdef CONFIG_PREEMPT_VOLUNTARY
191 # define dm_bufio_cond_resched() \
193 if (unlikely(need_resched())) \
197 # define dm_bufio_cond_resched() do { } while (0)
200 /*----------------------------------------------------------------*/
203 * Default cache size: available memory divided by the ratio.
205 static unsigned long dm_bufio_default_cache_size;
208 * Total cache size set by the user.
210 static unsigned long dm_bufio_cache_size;
213 * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
214 * at any time. If it disagrees, the user has changed cache size.
216 static unsigned long dm_bufio_cache_size_latch;
218 static DEFINE_SPINLOCK(param_spinlock);
221 * Buffers are freed after this timeout
223 static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
224 static unsigned dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
226 static unsigned long dm_bufio_peak_allocated;
227 static unsigned long dm_bufio_allocated_kmem_cache;
228 static unsigned long dm_bufio_allocated_get_free_pages;
229 static unsigned long dm_bufio_allocated_vmalloc;
230 static unsigned long dm_bufio_current_allocated;
232 /*----------------------------------------------------------------*/
235 * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
237 static unsigned long dm_bufio_cache_size_per_client;
240 * The current number of clients.
242 static int dm_bufio_client_count;
245 * The list of all clients.
247 static LIST_HEAD(dm_bufio_all_clients);
250 * This mutex protects dm_bufio_cache_size_latch,
251 * dm_bufio_cache_size_per_client and dm_bufio_client_count
253 static DEFINE_MUTEX(dm_bufio_clients_lock);
255 /*----------------------------------------------------------------
256 * A red/black tree acts as an index for all the buffers.
257 *--------------------------------------------------------------*/
258 static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
260 struct rb_node *n = c->buffer_tree.rb_node;
264 b = container_of(n, struct dm_buffer, node);
266 if (b->block == block)
269 n = (b->block < block) ? n->rb_left : n->rb_right;
275 static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
277 struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
278 struct dm_buffer *found;
281 found = container_of(*new, struct dm_buffer, node);
283 if (found->block == b->block) {
289 new = (found->block < b->block) ?
290 &((*new)->rb_left) : &((*new)->rb_right);
293 rb_link_node(&b->node, parent, new);
294 rb_insert_color(&b->node, &c->buffer_tree);
297 static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
299 rb_erase(&b->node, &c->buffer_tree);
302 /*----------------------------------------------------------------*/
304 static void adjust_total_allocated(enum data_mode data_mode, long diff)
306 static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
307 &dm_bufio_allocated_kmem_cache,
308 &dm_bufio_allocated_get_free_pages,
309 &dm_bufio_allocated_vmalloc,
312 spin_lock(¶m_spinlock);
314 *class_ptr[data_mode] += diff;
316 dm_bufio_current_allocated += diff;
318 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
319 dm_bufio_peak_allocated = dm_bufio_current_allocated;
321 spin_unlock(¶m_spinlock);
325 * Change the number of clients and recalculate per-client limit.
327 static void __cache_size_refresh(void)
329 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
330 BUG_ON(dm_bufio_client_count < 0);
332 dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
335 * Use default if set to 0 and report the actual cache size used.
337 if (!dm_bufio_cache_size_latch) {
338 (void)cmpxchg(&dm_bufio_cache_size, 0,
339 dm_bufio_default_cache_size);
340 dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
343 dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
344 (dm_bufio_client_count ? : 1);
348 * Allocating buffer data.
350 * Small buffers are allocated with kmem_cache, to use space optimally.
352 * For large buffers, we choose between get_free_pages and vmalloc.
353 * Each has advantages and disadvantages.
355 * __get_free_pages can randomly fail if the memory is fragmented.
356 * __vmalloc won't randomly fail, but vmalloc space is limited (it may be
357 * as low as 128M) so using it for caching is not appropriate.
359 * If the allocation may fail we use __get_free_pages. Memory fragmentation
360 * won't have a fatal effect here, but it just causes flushes of some other
361 * buffers and more I/O will be performed. Don't use __get_free_pages if it
362 * always fails (i.e. order >= MAX_ORDER).
364 * If the allocation shouldn't fail we use __vmalloc. This is only for the
365 * initial reserve allocation, so there's no risk of wasting all vmalloc
368 static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
369 enum data_mode *data_mode)
374 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
375 *data_mode = DATA_MODE_SLAB;
376 return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
379 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
380 gfp_mask & __GFP_NORETRY) {
381 *data_mode = DATA_MODE_GET_FREE_PAGES;
382 return (void *)__get_free_pages(gfp_mask,
383 c->pages_per_block_bits);
386 *data_mode = DATA_MODE_VMALLOC;
389 * __vmalloc allocates the data pages and auxiliary structures with
390 * gfp_flags that were specified, but pagetables are always allocated
391 * with GFP_KERNEL, no matter what was specified as gfp_mask.
393 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
394 * all allocations done by this process (including pagetables) are done
395 * as if GFP_NOIO was specified.
398 if (gfp_mask & __GFP_NORETRY)
399 noio_flag = memalloc_noio_save();
401 ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
403 if (gfp_mask & __GFP_NORETRY)
404 memalloc_noio_restore(noio_flag);
410 * Free buffer's data.
412 static void free_buffer_data(struct dm_bufio_client *c,
413 void *data, enum data_mode data_mode)
417 kmem_cache_free(DM_BUFIO_CACHE(c), data);
420 case DATA_MODE_GET_FREE_PAGES:
421 free_pages((unsigned long)data, c->pages_per_block_bits);
424 case DATA_MODE_VMALLOC:
429 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
436 * Allocate buffer and its data.
438 static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
440 struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
448 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
454 adjust_total_allocated(b->data_mode, (long)c->block_size);
460 * Free buffer and its data.
462 static void free_buffer(struct dm_buffer *b)
464 struct dm_bufio_client *c = b->c;
466 adjust_total_allocated(b->data_mode, -(long)c->block_size);
468 free_buffer_data(c, b->data, b->data_mode);
473 * Link buffer to the hash list and clean or dirty queue.
475 static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
477 struct dm_bufio_client *c = b->c;
479 c->n_buffers[dirty]++;
481 b->list_mode = dirty;
482 list_add(&b->lru_list, &c->lru[dirty]);
484 b->last_accessed = jiffies;
488 * Unlink buffer from the hash list and dirty or clean queue.
490 static void __unlink_buffer(struct dm_buffer *b)
492 struct dm_bufio_client *c = b->c;
494 BUG_ON(!c->n_buffers[b->list_mode]);
496 c->n_buffers[b->list_mode]--;
498 list_del(&b->lru_list);
502 * Place the buffer to the head of dirty or clean LRU queue.
504 static void __relink_lru(struct dm_buffer *b, int dirty)
506 struct dm_bufio_client *c = b->c;
508 BUG_ON(!c->n_buffers[b->list_mode]);
510 c->n_buffers[b->list_mode]--;
511 c->n_buffers[dirty]++;
512 b->list_mode = dirty;
513 list_move(&b->lru_list, &c->lru[dirty]);
514 b->last_accessed = jiffies;
517 /*----------------------------------------------------------------
518 * Submit I/O on the buffer.
520 * Bio interface is faster but it has some problems:
521 * the vector list is limited (increasing this limit increases
522 * memory-consumption per buffer, so it is not viable);
524 * the memory must be direct-mapped, not vmalloced;
526 * the I/O driver can reject requests spuriously if it thinks that
527 * the requests are too big for the device or if they cross a
528 * controller-defined memory boundary.
530 * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
531 * it is not vmalloced, try using the bio interface.
533 * If the buffer is big, if it is vmalloced or if the underlying device
534 * rejects the bio because it is too large, use dm-io layer to do the I/O.
535 * The dm-io layer splits the I/O into multiple requests, avoiding the above
537 *--------------------------------------------------------------*/
540 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
541 * that the request was handled directly with bio interface.
543 static void dmio_complete(unsigned long error, void *context)
545 struct dm_buffer *b = context;
547 b->bio.bi_end_io(&b->bio, error ? -EIO : 0);
550 static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
551 bio_end_io_t *end_io)
554 struct dm_io_request io_req = {
556 .notify.fn = dmio_complete,
558 .client = b->c->dm_io,
560 struct dm_io_region region = {
562 .sector = block << b->c->sectors_per_block_bits,
563 .count = b->c->block_size >> SECTOR_SHIFT,
566 if (b->data_mode != DATA_MODE_VMALLOC) {
567 io_req.mem.type = DM_IO_KMEM;
568 io_req.mem.ptr.addr = b->data;
570 io_req.mem.type = DM_IO_VMA;
571 io_req.mem.ptr.vma = b->data;
574 b->bio.bi_end_io = end_io;
576 r = dm_io(&io_req, 1, ®ion, NULL);
581 static void inline_endio(struct bio *bio, int error)
583 bio_end_io_t *end_fn = bio->bi_private;
586 * Reset the bio to free any attached resources
587 * (e.g. bio integrity profiles).
594 static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
595 bio_end_io_t *end_io)
601 b->bio.bi_io_vec = b->bio_vec;
602 b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
603 b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
604 b->bio.bi_bdev = b->c->bdev;
605 b->bio.bi_end_io = inline_endio;
607 * Use of .bi_private isn't a problem here because
608 * the dm_buffer's inline bio is local to bufio.
610 b->bio.bi_private = end_io;
613 * We assume that if len >= PAGE_SIZE ptr is page-aligned.
614 * If len < PAGE_SIZE the buffer doesn't cross page boundary.
617 len = b->c->block_size;
619 if (len >= PAGE_SIZE)
620 BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
622 BUG_ON((unsigned long)ptr & (len - 1));
625 if (!bio_add_page(&b->bio, virt_to_page(ptr),
626 len < PAGE_SIZE ? len : PAGE_SIZE,
627 virt_to_phys(ptr) & (PAGE_SIZE - 1))) {
628 BUG_ON(b->c->block_size <= PAGE_SIZE);
629 use_dmio(b, rw, block, end_io);
637 submit_bio(rw, &b->bio);
640 static void submit_io(struct dm_buffer *b, int rw, sector_t block,
641 bio_end_io_t *end_io)
643 if (rw == WRITE && b->c->write_callback)
644 b->c->write_callback(b);
646 if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
647 b->data_mode != DATA_MODE_VMALLOC)
648 use_inline_bio(b, rw, block, end_io);
650 use_dmio(b, rw, block, end_io);
653 /*----------------------------------------------------------------
654 * Writing dirty buffers
655 *--------------------------------------------------------------*/
658 * The endio routine for write.
660 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
663 static void write_endio(struct bio *bio, int error)
665 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
667 b->write_error = error;
668 if (unlikely(error)) {
669 struct dm_bufio_client *c = b->c;
670 (void)cmpxchg(&c->async_write_error, 0, error);
673 BUG_ON(!test_bit(B_WRITING, &b->state));
675 smp_mb__before_atomic();
676 clear_bit(B_WRITING, &b->state);
677 smp_mb__after_atomic();
679 wake_up_bit(&b->state, B_WRITING);
683 * Initiate a write on a dirty buffer, but don't wait for it.
685 * - If the buffer is not dirty, exit.
686 * - If there some previous write going on, wait for it to finish (we can't
687 * have two writes on the same buffer simultaneously).
688 * - Submit our write and don't wait on it. We set B_WRITING indicating
689 * that there is a write in progress.
691 static void __write_dirty_buffer(struct dm_buffer *b,
692 struct list_head *write_list)
694 if (!test_bit(B_DIRTY, &b->state))
697 clear_bit(B_DIRTY, &b->state);
698 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
701 submit_io(b, WRITE, b->block, write_endio);
703 list_add_tail(&b->write_list, write_list);
706 static void __flush_write_list(struct list_head *write_list)
708 struct blk_plug plug;
709 blk_start_plug(&plug);
710 while (!list_empty(write_list)) {
711 struct dm_buffer *b =
712 list_entry(write_list->next, struct dm_buffer, write_list);
713 list_del(&b->write_list);
714 submit_io(b, WRITE, b->block, write_endio);
715 dm_bufio_cond_resched();
717 blk_finish_plug(&plug);
721 * Wait until any activity on the buffer finishes. Possibly write the
722 * buffer if it is dirty. When this function finishes, there is no I/O
723 * running on the buffer and the buffer is not dirty.
725 static void __make_buffer_clean(struct dm_buffer *b)
727 BUG_ON(b->hold_count);
729 if (!b->state) /* fast case */
732 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
733 __write_dirty_buffer(b, NULL);
734 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
738 * Find some buffer that is not held by anybody, clean it, unlink it and
741 static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
745 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
746 BUG_ON(test_bit(B_WRITING, &b->state));
747 BUG_ON(test_bit(B_DIRTY, &b->state));
749 if (!b->hold_count) {
750 __make_buffer_clean(b);
754 dm_bufio_cond_resched();
757 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
758 BUG_ON(test_bit(B_READING, &b->state));
760 if (!b->hold_count) {
761 __make_buffer_clean(b);
765 dm_bufio_cond_resched();
772 * Wait until some other threads free some buffer or release hold count on
775 * This function is entered with c->lock held, drops it and regains it
778 static void __wait_for_free_buffer(struct dm_bufio_client *c)
780 DECLARE_WAITQUEUE(wait, current);
782 add_wait_queue(&c->free_buffer_wait, &wait);
783 set_task_state(current, TASK_UNINTERRUPTIBLE);
788 remove_wait_queue(&c->free_buffer_wait, &wait);
801 * Allocate a new buffer. If the allocation is not possible, wait until
802 * some other thread frees a buffer.
804 * May drop the lock and regain it.
806 static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
811 * dm-bufio is resistant to allocation failures (it just keeps
812 * one buffer reserved in cases all the allocations fail).
813 * So set flags to not try too hard:
814 * GFP_NOIO: don't recurse into the I/O layer
815 * __GFP_NORETRY: don't retry and rather return failure
816 * __GFP_NOMEMALLOC: don't use emergency reserves
817 * __GFP_NOWARN: don't print a warning in case of failure
819 * For debugging, if we set the cache size to 1, no new buffers will
823 if (dm_bufio_cache_size_latch != 1) {
824 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
829 if (nf == NF_PREFETCH)
832 if (!list_empty(&c->reserved_buffers)) {
833 b = list_entry(c->reserved_buffers.next,
834 struct dm_buffer, lru_list);
835 list_del(&b->lru_list);
836 c->need_reserved_buffers++;
841 b = __get_unclaimed_buffer(c);
845 __wait_for_free_buffer(c);
849 static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
851 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
856 if (c->alloc_callback)
857 c->alloc_callback(b);
863 * Free a buffer and wake other threads waiting for free buffers.
865 static void __free_buffer_wake(struct dm_buffer *b)
867 struct dm_bufio_client *c = b->c;
869 if (!c->need_reserved_buffers)
872 list_add(&b->lru_list, &c->reserved_buffers);
873 c->need_reserved_buffers--;
876 wake_up(&c->free_buffer_wait);
879 static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
880 struct list_head *write_list)
882 struct dm_buffer *b, *tmp;
884 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
885 BUG_ON(test_bit(B_READING, &b->state));
887 if (!test_bit(B_DIRTY, &b->state) &&
888 !test_bit(B_WRITING, &b->state)) {
889 __relink_lru(b, LIST_CLEAN);
893 if (no_wait && test_bit(B_WRITING, &b->state))
896 __write_dirty_buffer(b, write_list);
897 dm_bufio_cond_resched();
902 * Get writeback threshold and buffer limit for a given client.
904 static void __get_memory_limit(struct dm_bufio_client *c,
905 unsigned long *threshold_buffers,
906 unsigned long *limit_buffers)
908 unsigned long buffers;
910 if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
911 mutex_lock(&dm_bufio_clients_lock);
912 __cache_size_refresh();
913 mutex_unlock(&dm_bufio_clients_lock);
916 buffers = dm_bufio_cache_size_per_client >>
917 (c->sectors_per_block_bits + SECTOR_SHIFT);
919 if (buffers < c->minimum_buffers)
920 buffers = c->minimum_buffers;
922 *limit_buffers = buffers;
923 *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
927 * Check if we're over watermark.
928 * If we are over threshold_buffers, start freeing buffers.
929 * If we're over "limit_buffers", block until we get under the limit.
931 static void __check_watermark(struct dm_bufio_client *c,
932 struct list_head *write_list)
934 unsigned long threshold_buffers, limit_buffers;
936 __get_memory_limit(c, &threshold_buffers, &limit_buffers);
938 while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] >
941 struct dm_buffer *b = __get_unclaimed_buffer(c);
946 __free_buffer_wake(b);
947 dm_bufio_cond_resched();
950 if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
951 __write_dirty_buffers_async(c, 1, write_list);
954 /*----------------------------------------------------------------
956 *--------------------------------------------------------------*/
958 static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
959 enum new_flag nf, int *need_submit,
960 struct list_head *write_list)
962 struct dm_buffer *b, *new_b = NULL;
966 b = __find(c, block);
973 new_b = __alloc_buffer_wait(c, nf);
978 * We've had a period where the mutex was unlocked, so need to
979 * recheck the hash table.
981 b = __find(c, block);
983 __free_buffer_wake(new_b);
987 __check_watermark(c, write_list);
993 __link_buffer(b, block, LIST_CLEAN);
995 if (nf == NF_FRESH) {
1000 b->state = 1 << B_READING;
1006 if (nf == NF_PREFETCH)
1009 * Note: it is essential that we don't wait for the buffer to be
1010 * read if dm_bufio_get function is used. Both dm_bufio_get and
1011 * dm_bufio_prefetch can be used in the driver request routine.
1012 * If the user called both dm_bufio_prefetch and dm_bufio_get on
1013 * the same buffer, it would deadlock if we waited.
1015 if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state)))
1019 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
1020 test_bit(B_WRITING, &b->state));
1025 * The endio routine for reading: set the error, clear the bit and wake up
1026 * anyone waiting on the buffer.
1028 static void read_endio(struct bio *bio, int error)
1030 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
1032 b->read_error = error;
1034 BUG_ON(!test_bit(B_READING, &b->state));
1036 smp_mb__before_atomic();
1037 clear_bit(B_READING, &b->state);
1038 smp_mb__after_atomic();
1040 wake_up_bit(&b->state, B_READING);
1044 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
1045 * functions is similar except that dm_bufio_new doesn't read the
1046 * buffer from the disk (assuming that the caller overwrites all the data
1047 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1049 static void *new_read(struct dm_bufio_client *c, sector_t block,
1050 enum new_flag nf, struct dm_buffer **bp)
1053 struct dm_buffer *b;
1055 LIST_HEAD(write_list);
1058 b = __bufio_new(c, block, nf, &need_submit, &write_list);
1061 __flush_write_list(&write_list);
1067 submit_io(b, READ, b->block, read_endio);
1069 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
1071 if (b->read_error) {
1072 int error = b->read_error;
1074 dm_bufio_release(b);
1076 return ERR_PTR(error);
1084 void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1085 struct dm_buffer **bp)
1087 return new_read(c, block, NF_GET, bp);
1089 EXPORT_SYMBOL_GPL(dm_bufio_get);
1091 void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1092 struct dm_buffer **bp)
1094 BUG_ON(dm_bufio_in_request());
1096 return new_read(c, block, NF_READ, bp);
1098 EXPORT_SYMBOL_GPL(dm_bufio_read);
1100 void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1101 struct dm_buffer **bp)
1103 BUG_ON(dm_bufio_in_request());
1105 return new_read(c, block, NF_FRESH, bp);
1107 EXPORT_SYMBOL_GPL(dm_bufio_new);
1109 void dm_bufio_prefetch(struct dm_bufio_client *c,
1110 sector_t block, unsigned n_blocks)
1112 struct blk_plug plug;
1114 LIST_HEAD(write_list);
1116 BUG_ON(dm_bufio_in_request());
1118 blk_start_plug(&plug);
1121 for (; n_blocks--; block++) {
1123 struct dm_buffer *b;
1124 b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
1126 if (unlikely(!list_empty(&write_list))) {
1128 blk_finish_plug(&plug);
1129 __flush_write_list(&write_list);
1130 blk_start_plug(&plug);
1133 if (unlikely(b != NULL)) {
1137 submit_io(b, READ, b->block, read_endio);
1138 dm_bufio_release(b);
1140 dm_bufio_cond_resched();
1151 blk_finish_plug(&plug);
1153 EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1155 void dm_bufio_release(struct dm_buffer *b)
1157 struct dm_bufio_client *c = b->c;
1161 BUG_ON(!b->hold_count);
1164 if (!b->hold_count) {
1165 wake_up(&c->free_buffer_wait);
1168 * If there were errors on the buffer, and the buffer is not
1169 * to be written, free the buffer. There is no point in caching
1172 if ((b->read_error || b->write_error) &&
1173 !test_bit(B_READING, &b->state) &&
1174 !test_bit(B_WRITING, &b->state) &&
1175 !test_bit(B_DIRTY, &b->state)) {
1177 __free_buffer_wake(b);
1183 EXPORT_SYMBOL_GPL(dm_bufio_release);
1185 void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1187 struct dm_bufio_client *c = b->c;
1191 BUG_ON(test_bit(B_READING, &b->state));
1193 if (!test_and_set_bit(B_DIRTY, &b->state))
1194 __relink_lru(b, LIST_DIRTY);
1198 EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1200 void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1202 LIST_HEAD(write_list);
1204 BUG_ON(dm_bufio_in_request());
1207 __write_dirty_buffers_async(c, 0, &write_list);
1209 __flush_write_list(&write_list);
1211 EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1214 * For performance, it is essential that the buffers are written asynchronously
1215 * and simultaneously (so that the block layer can merge the writes) and then
1218 * Finally, we flush hardware disk cache.
1220 int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1223 unsigned long buffers_processed = 0;
1224 struct dm_buffer *b, *tmp;
1226 LIST_HEAD(write_list);
1229 __write_dirty_buffers_async(c, 0, &write_list);
1231 __flush_write_list(&write_list);
1235 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1236 int dropped_lock = 0;
1238 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1239 buffers_processed++;
1241 BUG_ON(test_bit(B_READING, &b->state));
1243 if (test_bit(B_WRITING, &b->state)) {
1244 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1248 wait_on_bit_io(&b->state, B_WRITING,
1249 TASK_UNINTERRUPTIBLE);
1253 wait_on_bit_io(&b->state, B_WRITING,
1254 TASK_UNINTERRUPTIBLE);
1257 if (!test_bit(B_DIRTY, &b->state) &&
1258 !test_bit(B_WRITING, &b->state))
1259 __relink_lru(b, LIST_CLEAN);
1261 dm_bufio_cond_resched();
1264 * If we dropped the lock, the list is no longer consistent,
1265 * so we must restart the search.
1267 * In the most common case, the buffer just processed is
1268 * relinked to the clean list, so we won't loop scanning the
1269 * same buffer again and again.
1271 * This may livelock if there is another thread simultaneously
1272 * dirtying buffers, so we count the number of buffers walked
1273 * and if it exceeds the total number of buffers, it means that
1274 * someone is doing some writes simultaneously with us. In
1275 * this case, stop, dropping the lock.
1280 wake_up(&c->free_buffer_wait);
1283 a = xchg(&c->async_write_error, 0);
1284 f = dm_bufio_issue_flush(c);
1290 EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1293 * Use dm-io to send and empty barrier flush the device.
1295 int dm_bufio_issue_flush(struct dm_bufio_client *c)
1297 struct dm_io_request io_req = {
1298 .bi_rw = WRITE_FLUSH,
1299 .mem.type = DM_IO_KMEM,
1300 .mem.ptr.addr = NULL,
1303 struct dm_io_region io_reg = {
1309 BUG_ON(dm_bufio_in_request());
1311 return dm_io(&io_req, 1, &io_reg, NULL);
1313 EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1316 * We first delete any other buffer that may be at that new location.
1318 * Then, we write the buffer to the original location if it was dirty.
1320 * Then, if we are the only one who is holding the buffer, relink the buffer
1321 * in the hash queue for the new location.
1323 * If there was someone else holding the buffer, we write it to the new
1324 * location but not relink it, because that other user needs to have the buffer
1325 * at the same place.
1327 void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1329 struct dm_bufio_client *c = b->c;
1330 struct dm_buffer *new;
1332 BUG_ON(dm_bufio_in_request());
1337 new = __find(c, new_block);
1339 if (new->hold_count) {
1340 __wait_for_free_buffer(c);
1345 * FIXME: Is there any point waiting for a write that's going
1346 * to be overwritten in a bit?
1348 __make_buffer_clean(new);
1349 __unlink_buffer(new);
1350 __free_buffer_wake(new);
1353 BUG_ON(!b->hold_count);
1354 BUG_ON(test_bit(B_READING, &b->state));
1356 __write_dirty_buffer(b, NULL);
1357 if (b->hold_count == 1) {
1358 wait_on_bit_io(&b->state, B_WRITING,
1359 TASK_UNINTERRUPTIBLE);
1360 set_bit(B_DIRTY, &b->state);
1362 __link_buffer(b, new_block, LIST_DIRTY);
1365 wait_on_bit_lock_io(&b->state, B_WRITING,
1366 TASK_UNINTERRUPTIBLE);
1368 * Relink buffer to "new_block" so that write_callback
1369 * sees "new_block" as a block number.
1370 * After the write, link the buffer back to old_block.
1371 * All this must be done in bufio lock, so that block number
1372 * change isn't visible to other threads.
1374 old_block = b->block;
1376 __link_buffer(b, new_block, b->list_mode);
1377 submit_io(b, WRITE, new_block, write_endio);
1378 wait_on_bit_io(&b->state, B_WRITING,
1379 TASK_UNINTERRUPTIBLE);
1381 __link_buffer(b, old_block, b->list_mode);
1385 dm_bufio_release(b);
1387 EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1390 * Free the given buffer.
1392 * This is just a hint, if the buffer is in use or dirty, this function
1395 void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
1397 struct dm_buffer *b;
1401 b = __find(c, block);
1402 if (b && likely(!b->hold_count) && likely(!b->state)) {
1404 __free_buffer_wake(b);
1409 EXPORT_SYMBOL(dm_bufio_forget);
1411 void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
1413 c->minimum_buffers = n;
1415 EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
1417 unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1419 return c->block_size;
1421 EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1423 sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1425 return i_size_read(c->bdev->bd_inode) >>
1426 (SECTOR_SHIFT + c->sectors_per_block_bits);
1428 EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1430 sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1434 EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1436 void *dm_bufio_get_block_data(struct dm_buffer *b)
1440 EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1442 void *dm_bufio_get_aux_data(struct dm_buffer *b)
1446 EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1448 struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1452 EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1454 static void drop_buffers(struct dm_bufio_client *c)
1456 struct dm_buffer *b;
1459 BUG_ON(dm_bufio_in_request());
1462 * An optimization so that the buffers are not written one-by-one.
1464 dm_bufio_write_dirty_buffers_async(c);
1468 while ((b = __get_unclaimed_buffer(c)))
1469 __free_buffer_wake(b);
1471 for (i = 0; i < LIST_SIZE; i++)
1472 list_for_each_entry(b, &c->lru[i], lru_list)
1473 DMERR("leaked buffer %llx, hold count %u, list %d",
1474 (unsigned long long)b->block, b->hold_count, i);
1476 for (i = 0; i < LIST_SIZE; i++)
1477 BUG_ON(!list_empty(&c->lru[i]));
1483 * We may not be able to evict this buffer if IO pending or the client
1484 * is still using it. Caller is expected to know buffer is too old.
1486 * And if GFP_NOFS is used, we must not do any I/O because we hold
1487 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
1488 * rerouted to different bufio client.
1490 static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
1492 if (!(gfp & __GFP_FS)) {
1493 if (test_bit(B_READING, &b->state) ||
1494 test_bit(B_WRITING, &b->state) ||
1495 test_bit(B_DIRTY, &b->state))
1502 __make_buffer_clean(b);
1504 __free_buffer_wake(b);
1509 static unsigned get_retain_buffers(struct dm_bufio_client *c)
1511 unsigned retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);
1512 return retain_bytes / c->block_size;
1515 static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
1519 struct dm_buffer *b, *tmp;
1520 unsigned long freed = 0;
1521 unsigned long count = nr_to_scan;
1522 unsigned retain_target = get_retain_buffers(c);
1524 for (l = 0; l < LIST_SIZE; l++) {
1525 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
1526 if (__try_evict_buffer(b, gfp_mask))
1528 if (!--nr_to_scan || ((count - freed) <= retain_target))
1530 dm_bufio_cond_resched();
1536 static unsigned long
1537 dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1539 struct dm_bufio_client *c;
1540 unsigned long freed;
1542 c = container_of(shrink, struct dm_bufio_client, shrinker);
1543 if (sc->gfp_mask & __GFP_FS)
1545 else if (!dm_bufio_trylock(c))
1548 freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);
1553 static unsigned long
1554 dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1556 struct dm_bufio_client *c;
1557 unsigned long count;
1559 c = container_of(shrink, struct dm_bufio_client, shrinker);
1560 if (sc->gfp_mask & __GFP_FS)
1562 else if (!dm_bufio_trylock(c))
1565 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1571 * Create the buffering interface
1573 struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1574 unsigned reserved_buffers, unsigned aux_size,
1575 void (*alloc_callback)(struct dm_buffer *),
1576 void (*write_callback)(struct dm_buffer *))
1579 struct dm_bufio_client *c;
1582 BUG_ON(block_size < 1 << SECTOR_SHIFT ||
1583 (block_size & (block_size - 1)));
1585 c = kzalloc(sizeof(*c), GFP_KERNEL);
1590 c->buffer_tree = RB_ROOT;
1593 c->block_size = block_size;
1594 c->sectors_per_block_bits = ffs(block_size) - 1 - SECTOR_SHIFT;
1595 c->pages_per_block_bits = (ffs(block_size) - 1 >= PAGE_SHIFT) ?
1596 ffs(block_size) - 1 - PAGE_SHIFT : 0;
1597 c->blocks_per_page_bits = (ffs(block_size) - 1 < PAGE_SHIFT ?
1598 PAGE_SHIFT - (ffs(block_size) - 1) : 0);
1600 c->aux_size = aux_size;
1601 c->alloc_callback = alloc_callback;
1602 c->write_callback = write_callback;
1604 for (i = 0; i < LIST_SIZE; i++) {
1605 INIT_LIST_HEAD(&c->lru[i]);
1606 c->n_buffers[i] = 0;
1609 mutex_init(&c->lock);
1610 INIT_LIST_HEAD(&c->reserved_buffers);
1611 c->need_reserved_buffers = reserved_buffers;
1613 c->minimum_buffers = DM_BUFIO_MIN_BUFFERS;
1615 init_waitqueue_head(&c->free_buffer_wait);
1616 c->async_write_error = 0;
1618 c->dm_io = dm_io_client_create();
1619 if (IS_ERR(c->dm_io)) {
1620 r = PTR_ERR(c->dm_io);
1624 mutex_lock(&dm_bufio_clients_lock);
1625 if (c->blocks_per_page_bits) {
1626 if (!DM_BUFIO_CACHE_NAME(c)) {
1627 DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
1628 if (!DM_BUFIO_CACHE_NAME(c)) {
1630 mutex_unlock(&dm_bufio_clients_lock);
1635 if (!DM_BUFIO_CACHE(c)) {
1636 DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
1638 c->block_size, 0, NULL);
1639 if (!DM_BUFIO_CACHE(c)) {
1641 mutex_unlock(&dm_bufio_clients_lock);
1646 mutex_unlock(&dm_bufio_clients_lock);
1648 while (c->need_reserved_buffers) {
1649 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1655 __free_buffer_wake(b);
1658 mutex_lock(&dm_bufio_clients_lock);
1659 dm_bufio_client_count++;
1660 list_add(&c->client_list, &dm_bufio_all_clients);
1661 __cache_size_refresh();
1662 mutex_unlock(&dm_bufio_clients_lock);
1664 c->shrinker.count_objects = dm_bufio_shrink_count;
1665 c->shrinker.scan_objects = dm_bufio_shrink_scan;
1666 c->shrinker.seeks = 1;
1667 c->shrinker.batch = 0;
1668 register_shrinker(&c->shrinker);
1674 while (!list_empty(&c->reserved_buffers)) {
1675 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1676 struct dm_buffer, lru_list);
1677 list_del(&b->lru_list);
1680 dm_io_client_destroy(c->dm_io);
1686 EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1689 * Free the buffering interface.
1690 * It is required that there are no references on any buffers.
1692 void dm_bufio_client_destroy(struct dm_bufio_client *c)
1698 unregister_shrinker(&c->shrinker);
1700 mutex_lock(&dm_bufio_clients_lock);
1702 list_del(&c->client_list);
1703 dm_bufio_client_count--;
1704 __cache_size_refresh();
1706 mutex_unlock(&dm_bufio_clients_lock);
1708 BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
1709 BUG_ON(c->need_reserved_buffers);
1711 while (!list_empty(&c->reserved_buffers)) {
1712 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1713 struct dm_buffer, lru_list);
1714 list_del(&b->lru_list);
1718 for (i = 0; i < LIST_SIZE; i++)
1719 if (c->n_buffers[i])
1720 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1722 for (i = 0; i < LIST_SIZE; i++)
1723 BUG_ON(c->n_buffers[i]);
1725 dm_io_client_destroy(c->dm_io);
1728 EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1730 static unsigned get_max_age_hz(void)
1732 unsigned max_age = ACCESS_ONCE(dm_bufio_max_age);
1734 if (max_age > UINT_MAX / HZ)
1735 max_age = UINT_MAX / HZ;
1737 return max_age * HZ;
1740 static bool older_than(struct dm_buffer *b, unsigned long age_hz)
1742 return (jiffies - b->last_accessed) >= age_hz;
1745 static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
1747 struct dm_buffer *b, *tmp;
1748 unsigned retain_target = get_retain_buffers(c);
1753 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1754 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) {
1755 if (count <= retain_target)
1758 if (!older_than(b, age_hz))
1761 if (__try_evict_buffer(b, 0))
1764 dm_bufio_cond_resched();
1770 static void cleanup_old_buffers(void)
1772 unsigned long max_age_hz = get_max_age_hz();
1773 struct dm_bufio_client *c;
1775 mutex_lock(&dm_bufio_clients_lock);
1777 list_for_each_entry(c, &dm_bufio_all_clients, client_list)
1778 __evict_old_buffers(c, max_age_hz);
1780 mutex_unlock(&dm_bufio_clients_lock);
1783 static struct workqueue_struct *dm_bufio_wq;
1784 static struct delayed_work dm_bufio_work;
1786 static void work_fn(struct work_struct *w)
1788 cleanup_old_buffers();
1790 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1791 DM_BUFIO_WORK_TIMER_SECS * HZ);
1794 /*----------------------------------------------------------------
1796 *--------------------------------------------------------------*/
1799 * This is called only once for the whole dm_bufio module.
1800 * It initializes memory limit.
1802 static int __init dm_bufio_init(void)
1806 dm_bufio_allocated_kmem_cache = 0;
1807 dm_bufio_allocated_get_free_pages = 0;
1808 dm_bufio_allocated_vmalloc = 0;
1809 dm_bufio_current_allocated = 0;
1811 memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
1812 memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
1814 mem = (__u64)((totalram_pages - totalhigh_pages) *
1815 DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
1817 if (mem > ULONG_MAX)
1822 * Get the size of vmalloc space the same way as VMALLOC_TOTAL
1823 * in fs/proc/internal.h
1825 if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
1826 mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100;
1829 dm_bufio_default_cache_size = mem;
1831 mutex_lock(&dm_bufio_clients_lock);
1832 __cache_size_refresh();
1833 mutex_unlock(&dm_bufio_clients_lock);
1835 dm_bufio_wq = create_singlethread_workqueue("dm_bufio_cache");
1839 INIT_DELAYED_WORK(&dm_bufio_work, work_fn);
1840 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1841 DM_BUFIO_WORK_TIMER_SECS * HZ);
1847 * This is called once when unloading the dm_bufio module.
1849 static void __exit dm_bufio_exit(void)
1854 cancel_delayed_work_sync(&dm_bufio_work);
1855 destroy_workqueue(dm_bufio_wq);
1857 for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) {
1858 struct kmem_cache *kc = dm_bufio_caches[i];
1861 kmem_cache_destroy(kc);
1864 for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
1865 kfree(dm_bufio_cache_names[i]);
1867 if (dm_bufio_client_count) {
1868 DMCRIT("%s: dm_bufio_client_count leaked: %d",
1869 __func__, dm_bufio_client_count);
1873 if (dm_bufio_current_allocated) {
1874 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
1875 __func__, dm_bufio_current_allocated);
1879 if (dm_bufio_allocated_get_free_pages) {
1880 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
1881 __func__, dm_bufio_allocated_get_free_pages);
1885 if (dm_bufio_allocated_vmalloc) {
1886 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
1887 __func__, dm_bufio_allocated_vmalloc);
1895 module_init(dm_bufio_init)
1896 module_exit(dm_bufio_exit)
1898 module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
1899 MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
1901 module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
1902 MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
1904 module_param_named(retain_bytes, dm_bufio_retain_bytes, uint, S_IRUGO | S_IWUSR);
1905 MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");
1907 module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
1908 MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
1910 module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
1911 MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
1913 module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
1914 MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
1916 module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
1917 MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
1919 module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
1920 MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
1922 MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
1923 MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
1924 MODULE_LICENSE("GPL");