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/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>
21 #define DM_MSG_PREFIX "bufio"
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
31 #define DM_BUFIO_MIN_BUFFERS 8
33 #define DM_BUFIO_MEMORY_PERCENT 2
34 #define DM_BUFIO_VMALLOC_PERCENT 25
35 #define DM_BUFIO_WRITEBACK_PERCENT 75
38 * Check buffer ages in this interval (seconds)
40 #define DM_BUFIO_WORK_TIMER_SECS 30
43 * Free buffers when they are older than this (seconds)
45 #define DM_BUFIO_DEFAULT_AGE_SECS 300
48 * The nr of bytes of cached data to keep around.
50 #define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
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.
56 #define DM_BUFIO_INLINE_VECS 16
59 * Don't try to use kmem_cache_alloc for blocks larger than this.
60 * For explanation, see alloc_buffer_data below.
62 #define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT (PAGE_SIZE >> 1)
63 #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1))
66 * dm_buffer->list_mode
74 * All buffers are linked to cache_hash with their hash_list field.
76 * Clean buffers that are not being written (B_WRITING not set)
77 * are linked to lru[LIST_CLEAN] with their lru_list field.
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
87 struct dm_bufio_client {
90 struct list_head lru[LIST_SIZE];
91 unsigned long n_buffers[LIST_SIZE];
93 struct block_device *bdev;
95 unsigned char sectors_per_block_bits;
96 unsigned char pages_per_block_bits;
97 unsigned char blocks_per_page_bits;
99 void (*alloc_callback)(struct dm_buffer *);
100 void (*write_callback)(struct dm_buffer *);
102 struct dm_io_client *dm_io;
104 struct list_head reserved_buffers;
105 unsigned need_reserved_buffers;
107 unsigned minimum_buffers;
109 struct rb_root buffer_tree;
110 wait_queue_head_t free_buffer_wait;
112 int async_write_error;
114 struct list_head client_list;
115 struct shrinker shrinker;
126 * Describes how the block was allocated:
127 * kmem_cache_alloc(), __get_free_pages() or vmalloc().
128 * See the comment at alloc_buffer_data.
132 DATA_MODE_GET_FREE_PAGES = 1,
133 DATA_MODE_VMALLOC = 2,
139 struct list_head lru_list;
142 enum data_mode data_mode;
143 unsigned char list_mode; /* LIST_* */
148 unsigned long last_accessed;
149 struct dm_bufio_client *c;
150 struct list_head write_list;
152 struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
153 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
155 struct stack_trace stack_trace;
156 unsigned long stack_entries[MAX_STACK];
160 /*----------------------------------------------------------------*/
162 static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
163 static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
165 static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
167 unsigned ret = c->blocks_per_page_bits - 1;
169 BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
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)])
177 #define dm_bufio_in_request() (!!current->bio_list)
179 static void dm_bufio_lock(struct dm_bufio_client *c)
181 mutex_lock_nested(&c->lock, dm_bufio_in_request());
184 static int dm_bufio_trylock(struct dm_bufio_client *c)
186 return mutex_trylock(&c->lock);
189 static void dm_bufio_unlock(struct dm_bufio_client *c)
191 mutex_unlock(&c->lock);
195 * FIXME Move to sched.h?
197 #ifdef CONFIG_PREEMPT_VOLUNTARY
198 # define dm_bufio_cond_resched() \
200 if (unlikely(need_resched())) \
204 # define dm_bufio_cond_resched() do { } while (0)
207 /*----------------------------------------------------------------*/
210 * Default cache size: available memory divided by the ratio.
212 static unsigned long dm_bufio_default_cache_size;
215 * Total cache size set by the user.
217 static unsigned long dm_bufio_cache_size;
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.
223 static unsigned long dm_bufio_cache_size_latch;
225 static DEFINE_SPINLOCK(param_spinlock);
228 * Buffers are freed after this timeout
230 static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
231 static unsigned dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
233 static unsigned long dm_bufio_peak_allocated;
234 static unsigned long dm_bufio_allocated_kmem_cache;
235 static unsigned long dm_bufio_allocated_get_free_pages;
236 static unsigned long dm_bufio_allocated_vmalloc;
237 static unsigned long dm_bufio_current_allocated;
239 /*----------------------------------------------------------------*/
242 * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
244 static unsigned long dm_bufio_cache_size_per_client;
247 * The current number of clients.
249 static int dm_bufio_client_count;
252 * The list of all clients.
254 static LIST_HEAD(dm_bufio_all_clients);
257 * This mutex protects dm_bufio_cache_size_latch,
258 * dm_bufio_cache_size_per_client and dm_bufio_client_count
260 static DEFINE_MUTEX(dm_bufio_clients_lock);
262 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
263 static void buffer_record_stack(struct dm_buffer *b)
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);
273 /*----------------------------------------------------------------
274 * A red/black tree acts as an index for all the buffers.
275 *--------------------------------------------------------------*/
276 static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
278 struct rb_node *n = c->buffer_tree.rb_node;
282 b = container_of(n, struct dm_buffer, node);
284 if (b->block == block)
287 n = (b->block < block) ? n->rb_left : n->rb_right;
293 static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
295 struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
296 struct dm_buffer *found;
299 found = container_of(*new, struct dm_buffer, node);
301 if (found->block == b->block) {
307 new = (found->block < b->block) ?
308 &((*new)->rb_left) : &((*new)->rb_right);
311 rb_link_node(&b->node, parent, new);
312 rb_insert_color(&b->node, &c->buffer_tree);
315 static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
317 rb_erase(&b->node, &c->buffer_tree);
320 /*----------------------------------------------------------------*/
322 static void adjust_total_allocated(enum data_mode data_mode, long diff)
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,
330 spin_lock(¶m_spinlock);
332 *class_ptr[data_mode] += diff;
334 dm_bufio_current_allocated += diff;
336 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
337 dm_bufio_peak_allocated = dm_bufio_current_allocated;
339 spin_unlock(¶m_spinlock);
343 * Change the number of clients and recalculate per-client limit.
345 static void __cache_size_refresh(void)
347 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
348 BUG_ON(dm_bufio_client_count < 0);
350 dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
353 * Use default if set to 0 and report the actual cache size used.
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;
361 dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
362 (dm_bufio_client_count ? : 1);
366 * Allocating buffer data.
368 * Small buffers are allocated with kmem_cache, to use space optimally.
370 * For large buffers, we choose between get_free_pages and vmalloc.
371 * Each has advantages and disadvantages.
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.
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).
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
386 static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
387 enum data_mode *data_mode)
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);
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);
404 *data_mode = DATA_MODE_VMALLOC;
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.
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.
416 if (gfp_mask & __GFP_NORETRY)
417 noio_flag = memalloc_noio_save();
419 ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
421 if (gfp_mask & __GFP_NORETRY)
422 memalloc_noio_restore(noio_flag);
428 * Free buffer's data.
430 static void free_buffer_data(struct dm_bufio_client *c,
431 void *data, enum data_mode data_mode)
435 kmem_cache_free(DM_BUFIO_CACHE(c), data);
438 case DATA_MODE_GET_FREE_PAGES:
439 free_pages((unsigned long)data, c->pages_per_block_bits);
442 case DATA_MODE_VMALLOC:
447 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
454 * Allocate buffer and its data.
456 static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
458 struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
466 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
472 adjust_total_allocated(b->data_mode, (long)c->block_size);
474 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
475 memset(&b->stack_trace, 0, sizeof(b->stack_trace));
481 * Free buffer and its data.
483 static void free_buffer(struct dm_buffer *b)
485 struct dm_bufio_client *c = b->c;
487 adjust_total_allocated(b->data_mode, -(long)c->block_size);
489 free_buffer_data(c, b->data, b->data_mode);
494 * Link buffer to the hash list and clean or dirty queue.
496 static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
498 struct dm_bufio_client *c = b->c;
500 c->n_buffers[dirty]++;
502 b->list_mode = dirty;
503 list_add(&b->lru_list, &c->lru[dirty]);
505 b->last_accessed = jiffies;
509 * Unlink buffer from the hash list and dirty or clean queue.
511 static void __unlink_buffer(struct dm_buffer *b)
513 struct dm_bufio_client *c = b->c;
515 BUG_ON(!c->n_buffers[b->list_mode]);
517 c->n_buffers[b->list_mode]--;
519 list_del(&b->lru_list);
523 * Place the buffer to the head of dirty or clean LRU queue.
525 static void __relink_lru(struct dm_buffer *b, int dirty)
527 struct dm_bufio_client *c = b->c;
529 BUG_ON(!c->n_buffers[b->list_mode]);
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;
538 /*----------------------------------------------------------------
539 * Submit I/O on the buffer.
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);
545 * the memory must be direct-mapped, not vmalloced;
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.
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.
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
558 *--------------------------------------------------------------*/
561 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
562 * that the request was handled directly with bio interface.
564 static void dmio_complete(unsigned long error, void *context)
566 struct dm_buffer *b = context;
568 b->bio.bi_error = error ? -EIO : 0;
569 b->bio.bi_end_io(&b->bio);
572 static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
573 bio_end_io_t *end_io)
576 struct dm_io_request io_req = {
578 .notify.fn = dmio_complete,
580 .client = b->c->dm_io,
582 struct dm_io_region region = {
584 .sector = block << b->c->sectors_per_block_bits,
585 .count = b->c->block_size >> SECTOR_SHIFT,
588 if (b->data_mode != DATA_MODE_VMALLOC) {
589 io_req.mem.type = DM_IO_KMEM;
590 io_req.mem.ptr.addr = b->data;
592 io_req.mem.type = DM_IO_VMA;
593 io_req.mem.ptr.vma = b->data;
596 b->bio.bi_end_io = end_io;
598 r = dm_io(&io_req, 1, ®ion, NULL);
605 static void inline_endio(struct bio *bio)
607 bio_end_io_t *end_fn = bio->bi_private;
608 int error = bio->bi_error;
611 * Reset the bio to free any attached resources
612 * (e.g. bio integrity profiles).
616 bio->bi_error = error;
620 static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
621 bio_end_io_t *end_io)
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;
633 * Use of .bi_private isn't a problem here because
634 * the dm_buffer's inline bio is local to bufio.
636 b->bio.bi_private = end_io;
640 * We assume that if len >= PAGE_SIZE ptr is page-aligned.
641 * If len < PAGE_SIZE the buffer doesn't cross page boundary.
644 len = b->c->block_size;
646 if (len >= PAGE_SIZE)
647 BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
649 BUG_ON((unsigned long)ptr & (len - 1));
652 if (!bio_add_page(&b->bio, virt_to_page(ptr),
653 len < PAGE_SIZE ? len : PAGE_SIZE,
654 offset_in_page(ptr))) {
655 BUG_ON(b->c->block_size <= PAGE_SIZE);
656 use_dmio(b, rw, block, end_io);
667 static void submit_io(struct dm_buffer *b, int rw, sector_t block,
668 bio_end_io_t *end_io)
670 if (rw == WRITE && b->c->write_callback)
671 b->c->write_callback(b);
673 if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
674 b->data_mode != DATA_MODE_VMALLOC)
675 use_inline_bio(b, rw, block, end_io);
677 use_dmio(b, rw, block, end_io);
680 /*----------------------------------------------------------------
681 * Writing dirty buffers
682 *--------------------------------------------------------------*/
685 * The endio routine for write.
687 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
690 static void write_endio(struct bio *bio)
692 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
694 b->write_error = bio->bi_error;
695 if (unlikely(bio->bi_error)) {
696 struct dm_bufio_client *c = b->c;
697 int error = bio->bi_error;
698 (void)cmpxchg(&c->async_write_error, 0, error);
701 BUG_ON(!test_bit(B_WRITING, &b->state));
703 smp_mb__before_atomic();
704 clear_bit(B_WRITING, &b->state);
705 smp_mb__after_atomic();
707 wake_up_bit(&b->state, B_WRITING);
711 * Initiate a write on a dirty buffer, but don't wait for it.
713 * - If the buffer is not dirty, exit.
714 * - If there some previous write going on, wait for it to finish (we can't
715 * have two writes on the same buffer simultaneously).
716 * - Submit our write and don't wait on it. We set B_WRITING indicating
717 * that there is a write in progress.
719 static void __write_dirty_buffer(struct dm_buffer *b,
720 struct list_head *write_list)
722 if (!test_bit(B_DIRTY, &b->state))
725 clear_bit(B_DIRTY, &b->state);
726 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
729 submit_io(b, WRITE, b->block, write_endio);
731 list_add_tail(&b->write_list, write_list);
734 static void __flush_write_list(struct list_head *write_list)
736 struct blk_plug plug;
737 blk_start_plug(&plug);
738 while (!list_empty(write_list)) {
739 struct dm_buffer *b =
740 list_entry(write_list->next, struct dm_buffer, write_list);
741 list_del(&b->write_list);
742 submit_io(b, WRITE, b->block, write_endio);
743 dm_bufio_cond_resched();
745 blk_finish_plug(&plug);
749 * Wait until any activity on the buffer finishes. Possibly write the
750 * buffer if it is dirty. When this function finishes, there is no I/O
751 * running on the buffer and the buffer is not dirty.
753 static void __make_buffer_clean(struct dm_buffer *b)
755 BUG_ON(b->hold_count);
757 if (!b->state) /* fast case */
760 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
761 __write_dirty_buffer(b, NULL);
762 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
766 * Find some buffer that is not held by anybody, clean it, unlink it and
769 static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
773 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
774 BUG_ON(test_bit(B_WRITING, &b->state));
775 BUG_ON(test_bit(B_DIRTY, &b->state));
777 if (!b->hold_count) {
778 __make_buffer_clean(b);
782 dm_bufio_cond_resched();
785 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
786 BUG_ON(test_bit(B_READING, &b->state));
788 if (!b->hold_count) {
789 __make_buffer_clean(b);
793 dm_bufio_cond_resched();
800 * Wait until some other threads free some buffer or release hold count on
803 * This function is entered with c->lock held, drops it and regains it
806 static void __wait_for_free_buffer(struct dm_bufio_client *c)
808 DECLARE_WAITQUEUE(wait, current);
810 add_wait_queue(&c->free_buffer_wait, &wait);
811 set_task_state(current, TASK_UNINTERRUPTIBLE);
816 remove_wait_queue(&c->free_buffer_wait, &wait);
829 * Allocate a new buffer. If the allocation is not possible, wait until
830 * some other thread frees a buffer.
832 * May drop the lock and regain it.
834 static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
839 * dm-bufio is resistant to allocation failures (it just keeps
840 * one buffer reserved in cases all the allocations fail).
841 * So set flags to not try too hard:
842 * GFP_NOIO: don't recurse into the I/O layer
843 * __GFP_NORETRY: don't retry and rather return failure
844 * __GFP_NOMEMALLOC: don't use emergency reserves
845 * __GFP_NOWARN: don't print a warning in case of failure
847 * For debugging, if we set the cache size to 1, no new buffers will
851 if (dm_bufio_cache_size_latch != 1) {
852 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
857 if (nf == NF_PREFETCH)
860 if (!list_empty(&c->reserved_buffers)) {
861 b = list_entry(c->reserved_buffers.next,
862 struct dm_buffer, lru_list);
863 list_del(&b->lru_list);
864 c->need_reserved_buffers++;
869 b = __get_unclaimed_buffer(c);
873 __wait_for_free_buffer(c);
877 static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
879 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
884 if (c->alloc_callback)
885 c->alloc_callback(b);
891 * Free a buffer and wake other threads waiting for free buffers.
893 static void __free_buffer_wake(struct dm_buffer *b)
895 struct dm_bufio_client *c = b->c;
897 if (!c->need_reserved_buffers)
900 list_add(&b->lru_list, &c->reserved_buffers);
901 c->need_reserved_buffers--;
904 wake_up(&c->free_buffer_wait);
907 static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
908 struct list_head *write_list)
910 struct dm_buffer *b, *tmp;
912 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
913 BUG_ON(test_bit(B_READING, &b->state));
915 if (!test_bit(B_DIRTY, &b->state) &&
916 !test_bit(B_WRITING, &b->state)) {
917 __relink_lru(b, LIST_CLEAN);
921 if (no_wait && test_bit(B_WRITING, &b->state))
924 __write_dirty_buffer(b, write_list);
925 dm_bufio_cond_resched();
930 * Get writeback threshold and buffer limit for a given client.
932 static void __get_memory_limit(struct dm_bufio_client *c,
933 unsigned long *threshold_buffers,
934 unsigned long *limit_buffers)
936 unsigned long buffers;
938 if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
939 mutex_lock(&dm_bufio_clients_lock);
940 __cache_size_refresh();
941 mutex_unlock(&dm_bufio_clients_lock);
944 buffers = dm_bufio_cache_size_per_client >>
945 (c->sectors_per_block_bits + SECTOR_SHIFT);
947 if (buffers < c->minimum_buffers)
948 buffers = c->minimum_buffers;
950 *limit_buffers = buffers;
951 *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
955 * Check if we're over watermark.
956 * If we are over threshold_buffers, start freeing buffers.
957 * If we're over "limit_buffers", block until we get under the limit.
959 static void __check_watermark(struct dm_bufio_client *c,
960 struct list_head *write_list)
962 unsigned long threshold_buffers, limit_buffers;
964 __get_memory_limit(c, &threshold_buffers, &limit_buffers);
966 while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] >
969 struct dm_buffer *b = __get_unclaimed_buffer(c);
974 __free_buffer_wake(b);
975 dm_bufio_cond_resched();
978 if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
979 __write_dirty_buffers_async(c, 1, write_list);
982 /*----------------------------------------------------------------
984 *--------------------------------------------------------------*/
986 static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
987 enum new_flag nf, int *need_submit,
988 struct list_head *write_list)
990 struct dm_buffer *b, *new_b = NULL;
994 b = __find(c, block);
1001 new_b = __alloc_buffer_wait(c, nf);
1006 * We've had a period where the mutex was unlocked, so need to
1007 * recheck the hash table.
1009 b = __find(c, block);
1011 __free_buffer_wake(new_b);
1015 __check_watermark(c, write_list);
1021 __link_buffer(b, block, LIST_CLEAN);
1023 if (nf == NF_FRESH) {
1028 b->state = 1 << B_READING;
1034 if (nf == NF_PREFETCH)
1037 * Note: it is essential that we don't wait for the buffer to be
1038 * read if dm_bufio_get function is used. Both dm_bufio_get and
1039 * dm_bufio_prefetch can be used in the driver request routine.
1040 * If the user called both dm_bufio_prefetch and dm_bufio_get on
1041 * the same buffer, it would deadlock if we waited.
1043 if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state)))
1047 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
1048 test_bit(B_WRITING, &b->state));
1053 * The endio routine for reading: set the error, clear the bit and wake up
1054 * anyone waiting on the buffer.
1056 static void read_endio(struct bio *bio)
1058 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
1060 b->read_error = bio->bi_error;
1062 BUG_ON(!test_bit(B_READING, &b->state));
1064 smp_mb__before_atomic();
1065 clear_bit(B_READING, &b->state);
1066 smp_mb__after_atomic();
1068 wake_up_bit(&b->state, B_READING);
1072 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
1073 * functions is similar except that dm_bufio_new doesn't read the
1074 * buffer from the disk (assuming that the caller overwrites all the data
1075 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1077 static void *new_read(struct dm_bufio_client *c, sector_t block,
1078 enum new_flag nf, struct dm_buffer **bp)
1081 struct dm_buffer *b;
1083 LIST_HEAD(write_list);
1086 b = __bufio_new(c, block, nf, &need_submit, &write_list);
1087 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1088 if (b && b->hold_count == 1)
1089 buffer_record_stack(b);
1093 __flush_write_list(&write_list);
1099 submit_io(b, READ, b->block, read_endio);
1101 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
1103 if (b->read_error) {
1104 int error = b->read_error;
1106 dm_bufio_release(b);
1108 return ERR_PTR(error);
1116 void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1117 struct dm_buffer **bp)
1119 return new_read(c, block, NF_GET, bp);
1121 EXPORT_SYMBOL_GPL(dm_bufio_get);
1123 void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1124 struct dm_buffer **bp)
1126 BUG_ON(dm_bufio_in_request());
1128 return new_read(c, block, NF_READ, bp);
1130 EXPORT_SYMBOL_GPL(dm_bufio_read);
1132 void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1133 struct dm_buffer **bp)
1135 BUG_ON(dm_bufio_in_request());
1137 return new_read(c, block, NF_FRESH, bp);
1139 EXPORT_SYMBOL_GPL(dm_bufio_new);
1141 void dm_bufio_prefetch(struct dm_bufio_client *c,
1142 sector_t block, unsigned n_blocks)
1144 struct blk_plug plug;
1146 LIST_HEAD(write_list);
1148 BUG_ON(dm_bufio_in_request());
1150 blk_start_plug(&plug);
1153 for (; n_blocks--; block++) {
1155 struct dm_buffer *b;
1156 b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
1158 if (unlikely(!list_empty(&write_list))) {
1160 blk_finish_plug(&plug);
1161 __flush_write_list(&write_list);
1162 blk_start_plug(&plug);
1165 if (unlikely(b != NULL)) {
1169 submit_io(b, READ, b->block, read_endio);
1170 dm_bufio_release(b);
1172 dm_bufio_cond_resched();
1183 blk_finish_plug(&plug);
1185 EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1187 void dm_bufio_release(struct dm_buffer *b)
1189 struct dm_bufio_client *c = b->c;
1193 BUG_ON(!b->hold_count);
1196 if (!b->hold_count) {
1197 wake_up(&c->free_buffer_wait);
1200 * If there were errors on the buffer, and the buffer is not
1201 * to be written, free the buffer. There is no point in caching
1204 if ((b->read_error || b->write_error) &&
1205 !test_bit(B_READING, &b->state) &&
1206 !test_bit(B_WRITING, &b->state) &&
1207 !test_bit(B_DIRTY, &b->state)) {
1209 __free_buffer_wake(b);
1215 EXPORT_SYMBOL_GPL(dm_bufio_release);
1217 void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1219 struct dm_bufio_client *c = b->c;
1223 BUG_ON(test_bit(B_READING, &b->state));
1225 if (!test_and_set_bit(B_DIRTY, &b->state))
1226 __relink_lru(b, LIST_DIRTY);
1230 EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1232 void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1234 LIST_HEAD(write_list);
1236 BUG_ON(dm_bufio_in_request());
1239 __write_dirty_buffers_async(c, 0, &write_list);
1241 __flush_write_list(&write_list);
1243 EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1246 * For performance, it is essential that the buffers are written asynchronously
1247 * and simultaneously (so that the block layer can merge the writes) and then
1250 * Finally, we flush hardware disk cache.
1252 int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1255 unsigned long buffers_processed = 0;
1256 struct dm_buffer *b, *tmp;
1258 LIST_HEAD(write_list);
1261 __write_dirty_buffers_async(c, 0, &write_list);
1263 __flush_write_list(&write_list);
1267 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1268 int dropped_lock = 0;
1270 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1271 buffers_processed++;
1273 BUG_ON(test_bit(B_READING, &b->state));
1275 if (test_bit(B_WRITING, &b->state)) {
1276 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1280 wait_on_bit_io(&b->state, B_WRITING,
1281 TASK_UNINTERRUPTIBLE);
1285 wait_on_bit_io(&b->state, B_WRITING,
1286 TASK_UNINTERRUPTIBLE);
1289 if (!test_bit(B_DIRTY, &b->state) &&
1290 !test_bit(B_WRITING, &b->state))
1291 __relink_lru(b, LIST_CLEAN);
1293 dm_bufio_cond_resched();
1296 * If we dropped the lock, the list is no longer consistent,
1297 * so we must restart the search.
1299 * In the most common case, the buffer just processed is
1300 * relinked to the clean list, so we won't loop scanning the
1301 * same buffer again and again.
1303 * This may livelock if there is another thread simultaneously
1304 * dirtying buffers, so we count the number of buffers walked
1305 * and if it exceeds the total number of buffers, it means that
1306 * someone is doing some writes simultaneously with us. In
1307 * this case, stop, dropping the lock.
1312 wake_up(&c->free_buffer_wait);
1315 a = xchg(&c->async_write_error, 0);
1316 f = dm_bufio_issue_flush(c);
1322 EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1325 * Use dm-io to send and empty barrier flush the device.
1327 int dm_bufio_issue_flush(struct dm_bufio_client *c)
1329 struct dm_io_request io_req = {
1330 .bi_rw = WRITE_FLUSH,
1331 .mem.type = DM_IO_KMEM,
1332 .mem.ptr.addr = NULL,
1335 struct dm_io_region io_reg = {
1341 BUG_ON(dm_bufio_in_request());
1343 return dm_io(&io_req, 1, &io_reg, NULL);
1345 EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1348 * We first delete any other buffer that may be at that new location.
1350 * Then, we write the buffer to the original location if it was dirty.
1352 * Then, if we are the only one who is holding the buffer, relink the buffer
1353 * in the hash queue for the new location.
1355 * If there was someone else holding the buffer, we write it to the new
1356 * location but not relink it, because that other user needs to have the buffer
1357 * at the same place.
1359 void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1361 struct dm_bufio_client *c = b->c;
1362 struct dm_buffer *new;
1364 BUG_ON(dm_bufio_in_request());
1369 new = __find(c, new_block);
1371 if (new->hold_count) {
1372 __wait_for_free_buffer(c);
1377 * FIXME: Is there any point waiting for a write that's going
1378 * to be overwritten in a bit?
1380 __make_buffer_clean(new);
1381 __unlink_buffer(new);
1382 __free_buffer_wake(new);
1385 BUG_ON(!b->hold_count);
1386 BUG_ON(test_bit(B_READING, &b->state));
1388 __write_dirty_buffer(b, NULL);
1389 if (b->hold_count == 1) {
1390 wait_on_bit_io(&b->state, B_WRITING,
1391 TASK_UNINTERRUPTIBLE);
1392 set_bit(B_DIRTY, &b->state);
1394 __link_buffer(b, new_block, LIST_DIRTY);
1397 wait_on_bit_lock_io(&b->state, B_WRITING,
1398 TASK_UNINTERRUPTIBLE);
1400 * Relink buffer to "new_block" so that write_callback
1401 * sees "new_block" as a block number.
1402 * After the write, link the buffer back to old_block.
1403 * All this must be done in bufio lock, so that block number
1404 * change isn't visible to other threads.
1406 old_block = b->block;
1408 __link_buffer(b, new_block, b->list_mode);
1409 submit_io(b, WRITE, new_block, write_endio);
1410 wait_on_bit_io(&b->state, B_WRITING,
1411 TASK_UNINTERRUPTIBLE);
1413 __link_buffer(b, old_block, b->list_mode);
1417 dm_bufio_release(b);
1419 EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1422 * Free the given buffer.
1424 * This is just a hint, if the buffer is in use or dirty, this function
1427 void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
1429 struct dm_buffer *b;
1433 b = __find(c, block);
1434 if (b && likely(!b->hold_count) && likely(!b->state)) {
1436 __free_buffer_wake(b);
1441 EXPORT_SYMBOL(dm_bufio_forget);
1443 void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
1445 c->minimum_buffers = n;
1447 EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
1449 unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1451 return c->block_size;
1453 EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1455 sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1457 return i_size_read(c->bdev->bd_inode) >>
1458 (SECTOR_SHIFT + c->sectors_per_block_bits);
1460 EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1462 sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1466 EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1468 void *dm_bufio_get_block_data(struct dm_buffer *b)
1472 EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1474 void *dm_bufio_get_aux_data(struct dm_buffer *b)
1478 EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1480 struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1484 EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1486 static void drop_buffers(struct dm_bufio_client *c)
1488 struct dm_buffer *b;
1490 bool warned = false;
1492 BUG_ON(dm_bufio_in_request());
1495 * An optimization so that the buffers are not written one-by-one.
1497 dm_bufio_write_dirty_buffers_async(c);
1501 while ((b = __get_unclaimed_buffer(c)))
1502 __free_buffer_wake(b);
1504 for (i = 0; i < LIST_SIZE; i++)
1505 list_for_each_entry(b, &c->lru[i], lru_list) {
1508 DMERR("leaked buffer %llx, hold count %u, list %d",
1509 (unsigned long long)b->block, b->hold_count, i);
1510 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1511 print_stack_trace(&b->stack_trace, 1);
1512 b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */
1516 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
1517 while ((b = __get_unclaimed_buffer(c)))
1518 __free_buffer_wake(b);
1521 for (i = 0; i < LIST_SIZE; i++)
1522 BUG_ON(!list_empty(&c->lru[i]));
1528 * We may not be able to evict this buffer if IO pending or the client
1529 * is still using it. Caller is expected to know buffer is too old.
1531 * And if GFP_NOFS is used, we must not do any I/O because we hold
1532 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
1533 * rerouted to different bufio client.
1535 static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
1537 if (!(gfp & __GFP_FS)) {
1538 if (test_bit(B_READING, &b->state) ||
1539 test_bit(B_WRITING, &b->state) ||
1540 test_bit(B_DIRTY, &b->state))
1547 __make_buffer_clean(b);
1549 __free_buffer_wake(b);
1554 static unsigned get_retain_buffers(struct dm_bufio_client *c)
1556 unsigned retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);
1557 return retain_bytes / c->block_size;
1560 static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
1564 struct dm_buffer *b, *tmp;
1565 unsigned long freed = 0;
1566 unsigned long count = nr_to_scan;
1567 unsigned retain_target = get_retain_buffers(c);
1569 for (l = 0; l < LIST_SIZE; l++) {
1570 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
1571 if (__try_evict_buffer(b, gfp_mask))
1573 if (!--nr_to_scan || ((count - freed) <= retain_target))
1575 dm_bufio_cond_resched();
1581 static unsigned long
1582 dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1584 struct dm_bufio_client *c;
1585 unsigned long freed;
1587 c = container_of(shrink, struct dm_bufio_client, shrinker);
1588 if (sc->gfp_mask & __GFP_FS)
1590 else if (!dm_bufio_trylock(c))
1593 freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);
1598 static unsigned long
1599 dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1601 struct dm_bufio_client *c;
1602 unsigned long count;
1604 c = container_of(shrink, struct dm_bufio_client, shrinker);
1605 if (sc->gfp_mask & __GFP_FS)
1607 else if (!dm_bufio_trylock(c))
1610 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1616 * Create the buffering interface
1618 struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1619 unsigned reserved_buffers, unsigned aux_size,
1620 void (*alloc_callback)(struct dm_buffer *),
1621 void (*write_callback)(struct dm_buffer *))
1624 struct dm_bufio_client *c;
1627 BUG_ON(block_size < 1 << SECTOR_SHIFT ||
1628 (block_size & (block_size - 1)));
1630 c = kzalloc(sizeof(*c), GFP_KERNEL);
1635 c->buffer_tree = RB_ROOT;
1638 c->block_size = block_size;
1639 c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
1640 c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ?
1641 __ffs(block_size) - PAGE_SHIFT : 0;
1642 c->blocks_per_page_bits = (__ffs(block_size) < PAGE_SHIFT ?
1643 PAGE_SHIFT - __ffs(block_size) : 0);
1645 c->aux_size = aux_size;
1646 c->alloc_callback = alloc_callback;
1647 c->write_callback = write_callback;
1649 for (i = 0; i < LIST_SIZE; i++) {
1650 INIT_LIST_HEAD(&c->lru[i]);
1651 c->n_buffers[i] = 0;
1654 mutex_init(&c->lock);
1655 INIT_LIST_HEAD(&c->reserved_buffers);
1656 c->need_reserved_buffers = reserved_buffers;
1658 c->minimum_buffers = DM_BUFIO_MIN_BUFFERS;
1660 init_waitqueue_head(&c->free_buffer_wait);
1661 c->async_write_error = 0;
1663 c->dm_io = dm_io_client_create();
1664 if (IS_ERR(c->dm_io)) {
1665 r = PTR_ERR(c->dm_io);
1669 mutex_lock(&dm_bufio_clients_lock);
1670 if (c->blocks_per_page_bits) {
1671 if (!DM_BUFIO_CACHE_NAME(c)) {
1672 DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
1673 if (!DM_BUFIO_CACHE_NAME(c)) {
1675 mutex_unlock(&dm_bufio_clients_lock);
1680 if (!DM_BUFIO_CACHE(c)) {
1681 DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
1683 c->block_size, 0, NULL);
1684 if (!DM_BUFIO_CACHE(c)) {
1686 mutex_unlock(&dm_bufio_clients_lock);
1691 mutex_unlock(&dm_bufio_clients_lock);
1693 while (c->need_reserved_buffers) {
1694 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1700 __free_buffer_wake(b);
1703 mutex_lock(&dm_bufio_clients_lock);
1704 dm_bufio_client_count++;
1705 list_add(&c->client_list, &dm_bufio_all_clients);
1706 __cache_size_refresh();
1707 mutex_unlock(&dm_bufio_clients_lock);
1709 c->shrinker.count_objects = dm_bufio_shrink_count;
1710 c->shrinker.scan_objects = dm_bufio_shrink_scan;
1711 c->shrinker.seeks = 1;
1712 c->shrinker.batch = 0;
1713 register_shrinker(&c->shrinker);
1719 while (!list_empty(&c->reserved_buffers)) {
1720 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1721 struct dm_buffer, lru_list);
1722 list_del(&b->lru_list);
1725 dm_io_client_destroy(c->dm_io);
1731 EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1734 * Free the buffering interface.
1735 * It is required that there are no references on any buffers.
1737 void dm_bufio_client_destroy(struct dm_bufio_client *c)
1743 unregister_shrinker(&c->shrinker);
1745 mutex_lock(&dm_bufio_clients_lock);
1747 list_del(&c->client_list);
1748 dm_bufio_client_count--;
1749 __cache_size_refresh();
1751 mutex_unlock(&dm_bufio_clients_lock);
1753 BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
1754 BUG_ON(c->need_reserved_buffers);
1756 while (!list_empty(&c->reserved_buffers)) {
1757 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1758 struct dm_buffer, lru_list);
1759 list_del(&b->lru_list);
1763 for (i = 0; i < LIST_SIZE; i++)
1764 if (c->n_buffers[i])
1765 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1767 for (i = 0; i < LIST_SIZE; i++)
1768 BUG_ON(c->n_buffers[i]);
1770 dm_io_client_destroy(c->dm_io);
1773 EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1775 static unsigned get_max_age_hz(void)
1777 unsigned max_age = ACCESS_ONCE(dm_bufio_max_age);
1779 if (max_age > UINT_MAX / HZ)
1780 max_age = UINT_MAX / HZ;
1782 return max_age * HZ;
1785 static bool older_than(struct dm_buffer *b, unsigned long age_hz)
1787 return time_after_eq(jiffies, b->last_accessed + age_hz);
1790 static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
1792 struct dm_buffer *b, *tmp;
1793 unsigned retain_target = get_retain_buffers(c);
1798 count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1799 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) {
1800 if (count <= retain_target)
1803 if (!older_than(b, age_hz))
1806 if (__try_evict_buffer(b, 0))
1809 dm_bufio_cond_resched();
1815 static void cleanup_old_buffers(void)
1817 unsigned long max_age_hz = get_max_age_hz();
1818 struct dm_bufio_client *c;
1820 mutex_lock(&dm_bufio_clients_lock);
1822 list_for_each_entry(c, &dm_bufio_all_clients, client_list)
1823 __evict_old_buffers(c, max_age_hz);
1825 mutex_unlock(&dm_bufio_clients_lock);
1828 static struct workqueue_struct *dm_bufio_wq;
1829 static struct delayed_work dm_bufio_work;
1831 static void work_fn(struct work_struct *w)
1833 cleanup_old_buffers();
1835 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1836 DM_BUFIO_WORK_TIMER_SECS * HZ);
1839 /*----------------------------------------------------------------
1841 *--------------------------------------------------------------*/
1844 * This is called only once for the whole dm_bufio module.
1845 * It initializes memory limit.
1847 static int __init dm_bufio_init(void)
1851 dm_bufio_allocated_kmem_cache = 0;
1852 dm_bufio_allocated_get_free_pages = 0;
1853 dm_bufio_allocated_vmalloc = 0;
1854 dm_bufio_current_allocated = 0;
1856 memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
1857 memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
1859 mem = (__u64)((totalram_pages - totalhigh_pages) *
1860 DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
1862 if (mem > ULONG_MAX)
1867 * Get the size of vmalloc space the same way as VMALLOC_TOTAL
1868 * in fs/proc/internal.h
1870 if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
1871 mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100;
1874 dm_bufio_default_cache_size = mem;
1876 mutex_lock(&dm_bufio_clients_lock);
1877 __cache_size_refresh();
1878 mutex_unlock(&dm_bufio_clients_lock);
1880 dm_bufio_wq = create_singlethread_workqueue("dm_bufio_cache");
1884 INIT_DELAYED_WORK(&dm_bufio_work, work_fn);
1885 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1886 DM_BUFIO_WORK_TIMER_SECS * HZ);
1892 * This is called once when unloading the dm_bufio module.
1894 static void __exit dm_bufio_exit(void)
1899 cancel_delayed_work_sync(&dm_bufio_work);
1900 destroy_workqueue(dm_bufio_wq);
1902 for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++)
1903 kmem_cache_destroy(dm_bufio_caches[i]);
1905 for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
1906 kfree(dm_bufio_cache_names[i]);
1908 if (dm_bufio_client_count) {
1909 DMCRIT("%s: dm_bufio_client_count leaked: %d",
1910 __func__, dm_bufio_client_count);
1914 if (dm_bufio_current_allocated) {
1915 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
1916 __func__, dm_bufio_current_allocated);
1920 if (dm_bufio_allocated_get_free_pages) {
1921 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
1922 __func__, dm_bufio_allocated_get_free_pages);
1926 if (dm_bufio_allocated_vmalloc) {
1927 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
1928 __func__, dm_bufio_allocated_vmalloc);
1935 module_init(dm_bufio_init)
1936 module_exit(dm_bufio_exit)
1938 module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
1939 MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
1941 module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
1942 MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
1944 module_param_named(retain_bytes, dm_bufio_retain_bytes, uint, S_IRUGO | S_IWUSR);
1945 MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");
1947 module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
1948 MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
1950 module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
1951 MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
1953 module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
1954 MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
1956 module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
1957 MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
1959 module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
1960 MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
1962 MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
1963 MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
1964 MODULE_LICENSE("GPL");