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>
18 #define DM_MSG_PREFIX "bufio"
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
28 #define DM_BUFIO_MIN_BUFFERS 8
30 #define DM_BUFIO_MEMORY_PERCENT 2
31 #define DM_BUFIO_VMALLOC_PERCENT 25
32 #define DM_BUFIO_WRITEBACK_PERCENT 75
35 * Check buffer ages in this interval (seconds)
37 #define DM_BUFIO_WORK_TIMER_SECS 10
40 * Free buffers when they are older than this (seconds)
42 #define DM_BUFIO_DEFAULT_AGE_SECS 60
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.
48 #define DM_BUFIO_INLINE_VECS 16
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))
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 struct hlist_head *cache_hash;
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,
136 struct hlist_node hash_list;
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;
149 struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
152 /*----------------------------------------------------------------*/
154 static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];
155 static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];
157 static inline int dm_bufio_cache_index(struct dm_bufio_client *c)
159 unsigned ret = c->blocks_per_page_bits - 1;
161 BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches));
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)])
169 #define dm_bufio_in_request() (!!current->bio_list)
171 static void dm_bufio_lock(struct dm_bufio_client *c)
173 mutex_lock_nested(&c->lock, dm_bufio_in_request());
176 static int dm_bufio_trylock(struct dm_bufio_client *c)
178 return mutex_trylock(&c->lock);
181 static void dm_bufio_unlock(struct dm_bufio_client *c)
183 mutex_unlock(&c->lock);
187 * FIXME Move to sched.h?
189 #ifdef CONFIG_PREEMPT_VOLUNTARY
190 # define dm_bufio_cond_resched() \
192 if (unlikely(need_resched())) \
196 # define dm_bufio_cond_resched() do { } while (0)
199 /*----------------------------------------------------------------*/
202 * Default cache size: available memory divided by the ratio.
204 static unsigned long dm_bufio_default_cache_size;
207 * Total cache size set by the user.
209 static unsigned long dm_bufio_cache_size;
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.
215 static unsigned long dm_bufio_cache_size_latch;
217 static DEFINE_SPINLOCK(param_spinlock);
220 * Buffers are freed after this timeout
222 static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
224 static unsigned long dm_bufio_peak_allocated;
225 static unsigned long dm_bufio_allocated_kmem_cache;
226 static unsigned long dm_bufio_allocated_get_free_pages;
227 static unsigned long dm_bufio_allocated_vmalloc;
228 static unsigned long dm_bufio_current_allocated;
230 /*----------------------------------------------------------------*/
233 * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count
235 static unsigned long dm_bufio_cache_size_per_client;
238 * The current number of clients.
240 static int dm_bufio_client_count;
243 * The list of all clients.
245 static LIST_HEAD(dm_bufio_all_clients);
248 * This mutex protects dm_bufio_cache_size_latch,
249 * dm_bufio_cache_size_per_client and dm_bufio_client_count
251 static DEFINE_MUTEX(dm_bufio_clients_lock);
253 /*----------------------------------------------------------------*/
255 static void adjust_total_allocated(enum data_mode data_mode, long diff)
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,
263 spin_lock(¶m_spinlock);
265 *class_ptr[data_mode] += diff;
267 dm_bufio_current_allocated += diff;
269 if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
270 dm_bufio_peak_allocated = dm_bufio_current_allocated;
272 spin_unlock(¶m_spinlock);
276 * Change the number of clients and recalculate per-client limit.
278 static void __cache_size_refresh(void)
280 BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
281 BUG_ON(dm_bufio_client_count < 0);
283 dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
286 * Use default if set to 0 and report the actual cache size used.
288 if (!dm_bufio_cache_size_latch) {
289 (void)cmpxchg(&dm_bufio_cache_size, 0,
290 dm_bufio_default_cache_size);
291 dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
294 dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch /
295 (dm_bufio_client_count ? : 1);
299 * Allocating buffer data.
301 * Small buffers are allocated with kmem_cache, to use space optimally.
303 * For large buffers, we choose between get_free_pages and vmalloc.
304 * Each has advantages and disadvantages.
306 * __get_free_pages can randomly fail if the memory is fragmented.
307 * __vmalloc won't randomly fail, but vmalloc space is limited (it may be
308 * as low as 128M) so using it for caching is not appropriate.
310 * If the allocation may fail we use __get_free_pages. Memory fragmentation
311 * won't have a fatal effect here, but it just causes flushes of some other
312 * buffers and more I/O will be performed. Don't use __get_free_pages if it
313 * always fails (i.e. order >= MAX_ORDER).
315 * If the allocation shouldn't fail we use __vmalloc. This is only for the
316 * initial reserve allocation, so there's no risk of wasting all vmalloc
319 static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
320 enum data_mode *data_mode)
325 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
326 *data_mode = DATA_MODE_SLAB;
327 return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
330 if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
331 gfp_mask & __GFP_NORETRY) {
332 *data_mode = DATA_MODE_GET_FREE_PAGES;
333 return (void *)__get_free_pages(gfp_mask,
334 c->pages_per_block_bits);
337 *data_mode = DATA_MODE_VMALLOC;
340 * __vmalloc allocates the data pages and auxiliary structures with
341 * gfp_flags that were specified, but pagetables are always allocated
342 * with GFP_KERNEL, no matter what was specified as gfp_mask.
344 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
345 * all allocations done by this process (including pagetables) are done
346 * as if GFP_NOIO was specified.
349 if (gfp_mask & __GFP_NORETRY)
350 noio_flag = memalloc_noio_save();
352 ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL);
354 if (gfp_mask & __GFP_NORETRY)
355 memalloc_noio_restore(noio_flag);
361 * Free buffer's data.
363 static void free_buffer_data(struct dm_bufio_client *c,
364 void *data, enum data_mode data_mode)
368 kmem_cache_free(DM_BUFIO_CACHE(c), data);
371 case DATA_MODE_GET_FREE_PAGES:
372 free_pages((unsigned long)data, c->pages_per_block_bits);
375 case DATA_MODE_VMALLOC:
380 DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
387 * Allocate buffer and its data.
389 static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
391 struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size,
399 b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
405 adjust_total_allocated(b->data_mode, (long)c->block_size);
411 * Free buffer and its data.
413 static void free_buffer(struct dm_buffer *b)
415 struct dm_bufio_client *c = b->c;
417 adjust_total_allocated(b->data_mode, -(long)c->block_size);
419 free_buffer_data(c, b->data, b->data_mode);
424 * Link buffer to the hash list and clean or dirty queue.
426 static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
428 struct dm_bufio_client *c = b->c;
430 c->n_buffers[dirty]++;
432 b->list_mode = dirty;
433 list_add(&b->lru_list, &c->lru[dirty]);
434 hlist_add_head(&b->hash_list, &c->cache_hash[DM_BUFIO_HASH(block)]);
435 b->last_accessed = jiffies;
439 * Unlink buffer from the hash list and dirty or clean queue.
441 static void __unlink_buffer(struct dm_buffer *b)
443 struct dm_bufio_client *c = b->c;
445 BUG_ON(!c->n_buffers[b->list_mode]);
447 c->n_buffers[b->list_mode]--;
448 hlist_del(&b->hash_list);
449 list_del(&b->lru_list);
453 * Place the buffer to the head of dirty or clean LRU queue.
455 static void __relink_lru(struct dm_buffer *b, int dirty)
457 struct dm_bufio_client *c = b->c;
459 BUG_ON(!c->n_buffers[b->list_mode]);
461 c->n_buffers[b->list_mode]--;
462 c->n_buffers[dirty]++;
463 b->list_mode = dirty;
464 list_move(&b->lru_list, &c->lru[dirty]);
465 b->last_accessed = jiffies;
468 /*----------------------------------------------------------------
469 * Submit I/O on the buffer.
471 * Bio interface is faster but it has some problems:
472 * the vector list is limited (increasing this limit increases
473 * memory-consumption per buffer, so it is not viable);
475 * the memory must be direct-mapped, not vmalloced;
477 * the I/O driver can reject requests spuriously if it thinks that
478 * the requests are too big for the device or if they cross a
479 * controller-defined memory boundary.
481 * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
482 * it is not vmalloced, try using the bio interface.
484 * If the buffer is big, if it is vmalloced or if the underlying device
485 * rejects the bio because it is too large, use dm-io layer to do the I/O.
486 * The dm-io layer splits the I/O into multiple requests, avoiding the above
488 *--------------------------------------------------------------*/
491 * dm-io completion routine. It just calls b->bio.bi_end_io, pretending
492 * that the request was handled directly with bio interface.
494 static void dmio_complete(unsigned long error, void *context)
496 struct dm_buffer *b = context;
498 b->bio.bi_end_io(&b->bio, error ? -EIO : 0);
501 static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
502 bio_end_io_t *end_io)
505 struct dm_io_request io_req = {
507 .notify.fn = dmio_complete,
509 .client = b->c->dm_io,
511 struct dm_io_region region = {
513 .sector = block << b->c->sectors_per_block_bits,
514 .count = b->c->block_size >> SECTOR_SHIFT,
517 if (b->data_mode != DATA_MODE_VMALLOC) {
518 io_req.mem.type = DM_IO_KMEM;
519 io_req.mem.ptr.addr = b->data;
521 io_req.mem.type = DM_IO_VMA;
522 io_req.mem.ptr.vma = b->data;
525 b->bio.bi_end_io = end_io;
527 r = dm_io(&io_req, 1, ®ion, NULL);
532 static void inline_endio(struct bio *bio, int error)
534 bio_end_io_t *end_fn = bio->bi_private;
537 * Reset the bio to free any attached resources
538 * (e.g. bio integrity profiles).
545 static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
546 bio_end_io_t *end_io)
552 b->bio.bi_io_vec = b->bio_vec;
553 b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
554 b->bio.bi_sector = block << b->c->sectors_per_block_bits;
555 b->bio.bi_bdev = b->c->bdev;
556 b->bio.bi_end_io = inline_endio;
558 * Use of .bi_private isn't a problem here because
559 * the dm_buffer's inline bio is local to bufio.
561 b->bio.bi_private = end_io;
564 * We assume that if len >= PAGE_SIZE ptr is page-aligned.
565 * If len < PAGE_SIZE the buffer doesn't cross page boundary.
568 len = b->c->block_size;
570 if (len >= PAGE_SIZE)
571 BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1));
573 BUG_ON((unsigned long)ptr & (len - 1));
576 if (!bio_add_page(&b->bio, virt_to_page(ptr),
577 len < PAGE_SIZE ? len : PAGE_SIZE,
578 virt_to_phys(ptr) & (PAGE_SIZE - 1))) {
579 BUG_ON(b->c->block_size <= PAGE_SIZE);
580 use_dmio(b, rw, block, end_io);
588 submit_bio(rw, &b->bio);
591 static void submit_io(struct dm_buffer *b, int rw, sector_t block,
592 bio_end_io_t *end_io)
594 if (rw == WRITE && b->c->write_callback)
595 b->c->write_callback(b);
597 if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
598 b->data_mode != DATA_MODE_VMALLOC)
599 use_inline_bio(b, rw, block, end_io);
601 use_dmio(b, rw, block, end_io);
604 /*----------------------------------------------------------------
605 * Writing dirty buffers
606 *--------------------------------------------------------------*/
609 * The endio routine for write.
611 * Set the error, clear B_WRITING bit and wake anyone who was waiting on
614 static void write_endio(struct bio *bio, int error)
616 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
618 b->write_error = error;
619 if (unlikely(error)) {
620 struct dm_bufio_client *c = b->c;
621 (void)cmpxchg(&c->async_write_error, 0, error);
624 BUG_ON(!test_bit(B_WRITING, &b->state));
626 smp_mb__before_clear_bit();
627 clear_bit(B_WRITING, &b->state);
628 smp_mb__after_clear_bit();
630 wake_up_bit(&b->state, B_WRITING);
634 * This function is called when wait_on_bit is actually waiting.
636 static int do_io_schedule(void *word)
644 * Initiate a write on a dirty buffer, but don't wait for it.
646 * - If the buffer is not dirty, exit.
647 * - If there some previous write going on, wait for it to finish (we can't
648 * have two writes on the same buffer simultaneously).
649 * - Submit our write and don't wait on it. We set B_WRITING indicating
650 * that there is a write in progress.
652 static void __write_dirty_buffer(struct dm_buffer *b)
654 if (!test_bit(B_DIRTY, &b->state))
657 clear_bit(B_DIRTY, &b->state);
658 wait_on_bit_lock(&b->state, B_WRITING,
659 do_io_schedule, TASK_UNINTERRUPTIBLE);
661 submit_io(b, WRITE, b->block, write_endio);
665 * Wait until any activity on the buffer finishes. Possibly write the
666 * buffer if it is dirty. When this function finishes, there is no I/O
667 * running on the buffer and the buffer is not dirty.
669 static void __make_buffer_clean(struct dm_buffer *b)
671 BUG_ON(b->hold_count);
673 if (!b->state) /* fast case */
676 wait_on_bit(&b->state, B_READING, do_io_schedule, TASK_UNINTERRUPTIBLE);
677 __write_dirty_buffer(b);
678 wait_on_bit(&b->state, B_WRITING, do_io_schedule, TASK_UNINTERRUPTIBLE);
682 * Find some buffer that is not held by anybody, clean it, unlink it and
685 static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
689 list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
690 BUG_ON(test_bit(B_WRITING, &b->state));
691 BUG_ON(test_bit(B_DIRTY, &b->state));
693 if (!b->hold_count) {
694 __make_buffer_clean(b);
698 dm_bufio_cond_resched();
701 list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
702 BUG_ON(test_bit(B_READING, &b->state));
704 if (!b->hold_count) {
705 __make_buffer_clean(b);
709 dm_bufio_cond_resched();
716 * Wait until some other threads free some buffer or release hold count on
719 * This function is entered with c->lock held, drops it and regains it
722 static void __wait_for_free_buffer(struct dm_bufio_client *c)
724 DECLARE_WAITQUEUE(wait, current);
726 add_wait_queue(&c->free_buffer_wait, &wait);
727 set_task_state(current, TASK_UNINTERRUPTIBLE);
732 set_task_state(current, TASK_RUNNING);
733 remove_wait_queue(&c->free_buffer_wait, &wait);
746 * Allocate a new buffer. If the allocation is not possible, wait until
747 * some other thread frees a buffer.
749 * May drop the lock and regain it.
751 static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
756 * dm-bufio is resistant to allocation failures (it just keeps
757 * one buffer reserved in cases all the allocations fail).
758 * So set flags to not try too hard:
759 * GFP_NOIO: don't recurse into the I/O layer
760 * __GFP_NORETRY: don't retry and rather return failure
761 * __GFP_NOMEMALLOC: don't use emergency reserves
762 * __GFP_NOWARN: don't print a warning in case of failure
764 * For debugging, if we set the cache size to 1, no new buffers will
768 if (dm_bufio_cache_size_latch != 1) {
769 b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
774 if (nf == NF_PREFETCH)
777 if (!list_empty(&c->reserved_buffers)) {
778 b = list_entry(c->reserved_buffers.next,
779 struct dm_buffer, lru_list);
780 list_del(&b->lru_list);
781 c->need_reserved_buffers++;
786 b = __get_unclaimed_buffer(c);
790 __wait_for_free_buffer(c);
794 static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
796 struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
801 if (c->alloc_callback)
802 c->alloc_callback(b);
808 * Free a buffer and wake other threads waiting for free buffers.
810 static void __free_buffer_wake(struct dm_buffer *b)
812 struct dm_bufio_client *c = b->c;
814 if (!c->need_reserved_buffers)
817 list_add(&b->lru_list, &c->reserved_buffers);
818 c->need_reserved_buffers--;
821 wake_up(&c->free_buffer_wait);
824 static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait)
826 struct dm_buffer *b, *tmp;
828 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
829 BUG_ON(test_bit(B_READING, &b->state));
831 if (!test_bit(B_DIRTY, &b->state) &&
832 !test_bit(B_WRITING, &b->state)) {
833 __relink_lru(b, LIST_CLEAN);
837 if (no_wait && test_bit(B_WRITING, &b->state))
840 __write_dirty_buffer(b);
841 dm_bufio_cond_resched();
846 * Get writeback threshold and buffer limit for a given client.
848 static void __get_memory_limit(struct dm_bufio_client *c,
849 unsigned long *threshold_buffers,
850 unsigned long *limit_buffers)
852 unsigned long buffers;
854 if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
855 mutex_lock(&dm_bufio_clients_lock);
856 __cache_size_refresh();
857 mutex_unlock(&dm_bufio_clients_lock);
860 buffers = dm_bufio_cache_size_per_client >>
861 (c->sectors_per_block_bits + SECTOR_SHIFT);
863 if (buffers < DM_BUFIO_MIN_BUFFERS)
864 buffers = DM_BUFIO_MIN_BUFFERS;
866 *limit_buffers = buffers;
867 *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
871 * Check if we're over watermark.
872 * If we are over threshold_buffers, start freeing buffers.
873 * If we're over "limit_buffers", block until we get under the limit.
875 static void __check_watermark(struct dm_bufio_client *c)
877 unsigned long threshold_buffers, limit_buffers;
879 __get_memory_limit(c, &threshold_buffers, &limit_buffers);
881 while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] >
884 struct dm_buffer *b = __get_unclaimed_buffer(c);
889 __free_buffer_wake(b);
890 dm_bufio_cond_resched();
893 if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
894 __write_dirty_buffers_async(c, 1);
898 * Find a buffer in the hash.
900 static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
904 hlist_for_each_entry(b, &c->cache_hash[DM_BUFIO_HASH(block)],
906 dm_bufio_cond_resched();
907 if (b->block == block)
914 /*----------------------------------------------------------------
916 *--------------------------------------------------------------*/
918 static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
919 enum new_flag nf, int *need_submit)
921 struct dm_buffer *b, *new_b = NULL;
925 b = __find(c, block);
932 new_b = __alloc_buffer_wait(c, nf);
937 * We've had a period where the mutex was unlocked, so need to
938 * recheck the hash table.
940 b = __find(c, block);
942 __free_buffer_wake(new_b);
946 __check_watermark(c);
952 __link_buffer(b, block, LIST_CLEAN);
954 if (nf == NF_FRESH) {
959 b->state = 1 << B_READING;
965 if (nf == NF_PREFETCH)
968 * Note: it is essential that we don't wait for the buffer to be
969 * read if dm_bufio_get function is used. Both dm_bufio_get and
970 * dm_bufio_prefetch can be used in the driver request routine.
971 * If the user called both dm_bufio_prefetch and dm_bufio_get on
972 * the same buffer, it would deadlock if we waited.
974 if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state)))
978 __relink_lru(b, test_bit(B_DIRTY, &b->state) ||
979 test_bit(B_WRITING, &b->state));
984 * The endio routine for reading: set the error, clear the bit and wake up
985 * anyone waiting on the buffer.
987 static void read_endio(struct bio *bio, int error)
989 struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
991 b->read_error = error;
993 BUG_ON(!test_bit(B_READING, &b->state));
995 smp_mb__before_clear_bit();
996 clear_bit(B_READING, &b->state);
997 smp_mb__after_clear_bit();
999 wake_up_bit(&b->state, B_READING);
1003 * A common routine for dm_bufio_new and dm_bufio_read. Operation of these
1004 * functions is similar except that dm_bufio_new doesn't read the
1005 * buffer from the disk (assuming that the caller overwrites all the data
1006 * and uses dm_bufio_mark_buffer_dirty to write new data back).
1008 static void *new_read(struct dm_bufio_client *c, sector_t block,
1009 enum new_flag nf, struct dm_buffer **bp)
1012 struct dm_buffer *b;
1015 b = __bufio_new(c, block, nf, &need_submit);
1022 submit_io(b, READ, b->block, read_endio);
1024 wait_on_bit(&b->state, B_READING, do_io_schedule, TASK_UNINTERRUPTIBLE);
1026 if (b->read_error) {
1027 int error = b->read_error;
1029 dm_bufio_release(b);
1031 return ERR_PTR(error);
1039 void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
1040 struct dm_buffer **bp)
1042 return new_read(c, block, NF_GET, bp);
1044 EXPORT_SYMBOL_GPL(dm_bufio_get);
1046 void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
1047 struct dm_buffer **bp)
1049 BUG_ON(dm_bufio_in_request());
1051 return new_read(c, block, NF_READ, bp);
1053 EXPORT_SYMBOL_GPL(dm_bufio_read);
1055 void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
1056 struct dm_buffer **bp)
1058 BUG_ON(dm_bufio_in_request());
1060 return new_read(c, block, NF_FRESH, bp);
1062 EXPORT_SYMBOL_GPL(dm_bufio_new);
1064 void dm_bufio_prefetch(struct dm_bufio_client *c,
1065 sector_t block, unsigned n_blocks)
1067 struct blk_plug plug;
1069 BUG_ON(dm_bufio_in_request());
1071 blk_start_plug(&plug);
1074 for (; n_blocks--; block++) {
1076 struct dm_buffer *b;
1077 b = __bufio_new(c, block, NF_PREFETCH, &need_submit);
1078 if (unlikely(b != NULL)) {
1082 submit_io(b, READ, b->block, read_endio);
1083 dm_bufio_release(b);
1085 dm_bufio_cond_resched();
1097 blk_finish_plug(&plug);
1099 EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
1101 void dm_bufio_release(struct dm_buffer *b)
1103 struct dm_bufio_client *c = b->c;
1107 BUG_ON(!b->hold_count);
1110 if (!b->hold_count) {
1111 wake_up(&c->free_buffer_wait);
1114 * If there were errors on the buffer, and the buffer is not
1115 * to be written, free the buffer. There is no point in caching
1118 if ((b->read_error || b->write_error) &&
1119 !test_bit(B_READING, &b->state) &&
1120 !test_bit(B_WRITING, &b->state) &&
1121 !test_bit(B_DIRTY, &b->state)) {
1123 __free_buffer_wake(b);
1129 EXPORT_SYMBOL_GPL(dm_bufio_release);
1131 void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
1133 struct dm_bufio_client *c = b->c;
1137 BUG_ON(test_bit(B_READING, &b->state));
1139 if (!test_and_set_bit(B_DIRTY, &b->state))
1140 __relink_lru(b, LIST_DIRTY);
1144 EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
1146 void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
1148 BUG_ON(dm_bufio_in_request());
1151 __write_dirty_buffers_async(c, 0);
1154 EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
1157 * For performance, it is essential that the buffers are written asynchronously
1158 * and simultaneously (so that the block layer can merge the writes) and then
1161 * Finally, we flush hardware disk cache.
1163 int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
1166 unsigned long buffers_processed = 0;
1167 struct dm_buffer *b, *tmp;
1170 __write_dirty_buffers_async(c, 0);
1173 list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
1174 int dropped_lock = 0;
1176 if (buffers_processed < c->n_buffers[LIST_DIRTY])
1177 buffers_processed++;
1179 BUG_ON(test_bit(B_READING, &b->state));
1181 if (test_bit(B_WRITING, &b->state)) {
1182 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1186 wait_on_bit(&b->state, B_WRITING,
1188 TASK_UNINTERRUPTIBLE);
1192 wait_on_bit(&b->state, B_WRITING,
1194 TASK_UNINTERRUPTIBLE);
1197 if (!test_bit(B_DIRTY, &b->state) &&
1198 !test_bit(B_WRITING, &b->state))
1199 __relink_lru(b, LIST_CLEAN);
1201 dm_bufio_cond_resched();
1204 * If we dropped the lock, the list is no longer consistent,
1205 * so we must restart the search.
1207 * In the most common case, the buffer just processed is
1208 * relinked to the clean list, so we won't loop scanning the
1209 * same buffer again and again.
1211 * This may livelock if there is another thread simultaneously
1212 * dirtying buffers, so we count the number of buffers walked
1213 * and if it exceeds the total number of buffers, it means that
1214 * someone is doing some writes simultaneously with us. In
1215 * this case, stop, dropping the lock.
1220 wake_up(&c->free_buffer_wait);
1223 a = xchg(&c->async_write_error, 0);
1224 f = dm_bufio_issue_flush(c);
1230 EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
1233 * Use dm-io to send and empty barrier flush the device.
1235 int dm_bufio_issue_flush(struct dm_bufio_client *c)
1237 struct dm_io_request io_req = {
1238 .bi_rw = WRITE_FLUSH,
1239 .mem.type = DM_IO_KMEM,
1240 .mem.ptr.addr = NULL,
1243 struct dm_io_region io_reg = {
1249 BUG_ON(dm_bufio_in_request());
1251 return dm_io(&io_req, 1, &io_reg, NULL);
1253 EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
1256 * We first delete any other buffer that may be at that new location.
1258 * Then, we write the buffer to the original location if it was dirty.
1260 * Then, if we are the only one who is holding the buffer, relink the buffer
1261 * in the hash queue for the new location.
1263 * If there was someone else holding the buffer, we write it to the new
1264 * location but not relink it, because that other user needs to have the buffer
1265 * at the same place.
1267 void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
1269 struct dm_bufio_client *c = b->c;
1270 struct dm_buffer *new;
1272 BUG_ON(dm_bufio_in_request());
1277 new = __find(c, new_block);
1279 if (new->hold_count) {
1280 __wait_for_free_buffer(c);
1285 * FIXME: Is there any point waiting for a write that's going
1286 * to be overwritten in a bit?
1288 __make_buffer_clean(new);
1289 __unlink_buffer(new);
1290 __free_buffer_wake(new);
1293 BUG_ON(!b->hold_count);
1294 BUG_ON(test_bit(B_READING, &b->state));
1296 __write_dirty_buffer(b);
1297 if (b->hold_count == 1) {
1298 wait_on_bit(&b->state, B_WRITING,
1299 do_io_schedule, TASK_UNINTERRUPTIBLE);
1300 set_bit(B_DIRTY, &b->state);
1302 __link_buffer(b, new_block, LIST_DIRTY);
1305 wait_on_bit_lock(&b->state, B_WRITING,
1306 do_io_schedule, TASK_UNINTERRUPTIBLE);
1308 * Relink buffer to "new_block" so that write_callback
1309 * sees "new_block" as a block number.
1310 * After the write, link the buffer back to old_block.
1311 * All this must be done in bufio lock, so that block number
1312 * change isn't visible to other threads.
1314 old_block = b->block;
1316 __link_buffer(b, new_block, b->list_mode);
1317 submit_io(b, WRITE, new_block, write_endio);
1318 wait_on_bit(&b->state, B_WRITING,
1319 do_io_schedule, TASK_UNINTERRUPTIBLE);
1321 __link_buffer(b, old_block, b->list_mode);
1325 dm_bufio_release(b);
1327 EXPORT_SYMBOL_GPL(dm_bufio_release_move);
1329 unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
1331 return c->block_size;
1333 EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
1335 sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
1337 return i_size_read(c->bdev->bd_inode) >>
1338 (SECTOR_SHIFT + c->sectors_per_block_bits);
1340 EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
1342 sector_t dm_bufio_get_block_number(struct dm_buffer *b)
1346 EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
1348 void *dm_bufio_get_block_data(struct dm_buffer *b)
1352 EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
1354 void *dm_bufio_get_aux_data(struct dm_buffer *b)
1358 EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
1360 struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
1364 EXPORT_SYMBOL_GPL(dm_bufio_get_client);
1366 static void drop_buffers(struct dm_bufio_client *c)
1368 struct dm_buffer *b;
1371 BUG_ON(dm_bufio_in_request());
1374 * An optimization so that the buffers are not written one-by-one.
1376 dm_bufio_write_dirty_buffers_async(c);
1380 while ((b = __get_unclaimed_buffer(c)))
1381 __free_buffer_wake(b);
1383 for (i = 0; i < LIST_SIZE; i++)
1384 list_for_each_entry(b, &c->lru[i], lru_list)
1385 DMERR("leaked buffer %llx, hold count %u, list %d",
1386 (unsigned long long)b->block, b->hold_count, i);
1388 for (i = 0; i < LIST_SIZE; i++)
1389 BUG_ON(!list_empty(&c->lru[i]));
1395 * Test if the buffer is unused and too old, and commit it.
1396 * At if noio is set, we must not do any I/O because we hold
1397 * dm_bufio_clients_lock and we would risk deadlock if the I/O gets rerouted to
1398 * different bufio client.
1400 static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp,
1401 unsigned long max_jiffies)
1403 if (jiffies - b->last_accessed < max_jiffies)
1406 if (!(gfp & __GFP_IO)) {
1407 if (test_bit(B_READING, &b->state) ||
1408 test_bit(B_WRITING, &b->state) ||
1409 test_bit(B_DIRTY, &b->state))
1416 __make_buffer_clean(b);
1418 __free_buffer_wake(b);
1423 static void __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
1424 struct shrink_control *sc)
1427 struct dm_buffer *b, *tmp;
1429 for (l = 0; l < LIST_SIZE; l++) {
1430 list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list)
1431 if (!__cleanup_old_buffer(b, sc->gfp_mask, 0) &&
1434 dm_bufio_cond_resched();
1438 static int shrink(struct shrinker *shrinker, struct shrink_control *sc)
1440 struct dm_bufio_client *c =
1441 container_of(shrinker, struct dm_bufio_client, shrinker);
1443 unsigned long nr_to_scan = sc->nr_to_scan;
1445 if (sc->gfp_mask & __GFP_IO)
1447 else if (!dm_bufio_trylock(c))
1448 return !nr_to_scan ? 0 : -1;
1451 __scan(c, nr_to_scan, sc);
1453 r = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
1463 * Create the buffering interface
1465 struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
1466 unsigned reserved_buffers, unsigned aux_size,
1467 void (*alloc_callback)(struct dm_buffer *),
1468 void (*write_callback)(struct dm_buffer *))
1471 struct dm_bufio_client *c;
1474 BUG_ON(block_size < 1 << SECTOR_SHIFT ||
1475 (block_size & (block_size - 1)));
1477 c = kmalloc(sizeof(*c), GFP_KERNEL);
1482 c->cache_hash = vmalloc(sizeof(struct hlist_head) << DM_BUFIO_HASH_BITS);
1483 if (!c->cache_hash) {
1489 c->block_size = block_size;
1490 c->sectors_per_block_bits = ffs(block_size) - 1 - SECTOR_SHIFT;
1491 c->pages_per_block_bits = (ffs(block_size) - 1 >= PAGE_SHIFT) ?
1492 ffs(block_size) - 1 - PAGE_SHIFT : 0;
1493 c->blocks_per_page_bits = (ffs(block_size) - 1 < PAGE_SHIFT ?
1494 PAGE_SHIFT - (ffs(block_size) - 1) : 0);
1496 c->aux_size = aux_size;
1497 c->alloc_callback = alloc_callback;
1498 c->write_callback = write_callback;
1500 for (i = 0; i < LIST_SIZE; i++) {
1501 INIT_LIST_HEAD(&c->lru[i]);
1502 c->n_buffers[i] = 0;
1505 for (i = 0; i < 1 << DM_BUFIO_HASH_BITS; i++)
1506 INIT_HLIST_HEAD(&c->cache_hash[i]);
1508 mutex_init(&c->lock);
1509 INIT_LIST_HEAD(&c->reserved_buffers);
1510 c->need_reserved_buffers = reserved_buffers;
1512 init_waitqueue_head(&c->free_buffer_wait);
1513 c->async_write_error = 0;
1515 c->dm_io = dm_io_client_create();
1516 if (IS_ERR(c->dm_io)) {
1517 r = PTR_ERR(c->dm_io);
1521 mutex_lock(&dm_bufio_clients_lock);
1522 if (c->blocks_per_page_bits) {
1523 if (!DM_BUFIO_CACHE_NAME(c)) {
1524 DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size);
1525 if (!DM_BUFIO_CACHE_NAME(c)) {
1527 mutex_unlock(&dm_bufio_clients_lock);
1532 if (!DM_BUFIO_CACHE(c)) {
1533 DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c),
1535 c->block_size, 0, NULL);
1536 if (!DM_BUFIO_CACHE(c)) {
1538 mutex_unlock(&dm_bufio_clients_lock);
1543 mutex_unlock(&dm_bufio_clients_lock);
1545 while (c->need_reserved_buffers) {
1546 struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
1552 __free_buffer_wake(b);
1555 mutex_lock(&dm_bufio_clients_lock);
1556 dm_bufio_client_count++;
1557 list_add(&c->client_list, &dm_bufio_all_clients);
1558 __cache_size_refresh();
1559 mutex_unlock(&dm_bufio_clients_lock);
1561 c->shrinker.shrink = shrink;
1562 c->shrinker.seeks = 1;
1563 c->shrinker.batch = 0;
1564 register_shrinker(&c->shrinker);
1570 while (!list_empty(&c->reserved_buffers)) {
1571 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1572 struct dm_buffer, lru_list);
1573 list_del(&b->lru_list);
1576 dm_io_client_destroy(c->dm_io);
1578 vfree(c->cache_hash);
1584 EXPORT_SYMBOL_GPL(dm_bufio_client_create);
1587 * Free the buffering interface.
1588 * It is required that there are no references on any buffers.
1590 void dm_bufio_client_destroy(struct dm_bufio_client *c)
1596 unregister_shrinker(&c->shrinker);
1598 mutex_lock(&dm_bufio_clients_lock);
1600 list_del(&c->client_list);
1601 dm_bufio_client_count--;
1602 __cache_size_refresh();
1604 mutex_unlock(&dm_bufio_clients_lock);
1606 for (i = 0; i < 1 << DM_BUFIO_HASH_BITS; i++)
1607 BUG_ON(!hlist_empty(&c->cache_hash[i]));
1609 BUG_ON(c->need_reserved_buffers);
1611 while (!list_empty(&c->reserved_buffers)) {
1612 struct dm_buffer *b = list_entry(c->reserved_buffers.next,
1613 struct dm_buffer, lru_list);
1614 list_del(&b->lru_list);
1618 for (i = 0; i < LIST_SIZE; i++)
1619 if (c->n_buffers[i])
1620 DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
1622 for (i = 0; i < LIST_SIZE; i++)
1623 BUG_ON(c->n_buffers[i]);
1625 dm_io_client_destroy(c->dm_io);
1626 vfree(c->cache_hash);
1629 EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
1631 static void cleanup_old_buffers(void)
1633 unsigned long max_age = ACCESS_ONCE(dm_bufio_max_age);
1634 struct dm_bufio_client *c;
1636 if (max_age > ULONG_MAX / HZ)
1637 max_age = ULONG_MAX / HZ;
1639 mutex_lock(&dm_bufio_clients_lock);
1640 list_for_each_entry(c, &dm_bufio_all_clients, client_list) {
1641 if (!dm_bufio_trylock(c))
1644 while (!list_empty(&c->lru[LIST_CLEAN])) {
1645 struct dm_buffer *b;
1646 b = list_entry(c->lru[LIST_CLEAN].prev,
1647 struct dm_buffer, lru_list);
1648 if (__cleanup_old_buffer(b, 0, max_age * HZ))
1650 dm_bufio_cond_resched();
1654 dm_bufio_cond_resched();
1656 mutex_unlock(&dm_bufio_clients_lock);
1659 static struct workqueue_struct *dm_bufio_wq;
1660 static struct delayed_work dm_bufio_work;
1662 static void work_fn(struct work_struct *w)
1664 cleanup_old_buffers();
1666 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1667 DM_BUFIO_WORK_TIMER_SECS * HZ);
1670 /*----------------------------------------------------------------
1672 *--------------------------------------------------------------*/
1675 * This is called only once for the whole dm_bufio module.
1676 * It initializes memory limit.
1678 static int __init dm_bufio_init(void)
1682 dm_bufio_allocated_kmem_cache = 0;
1683 dm_bufio_allocated_get_free_pages = 0;
1684 dm_bufio_allocated_vmalloc = 0;
1685 dm_bufio_current_allocated = 0;
1687 memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
1688 memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
1690 mem = (__u64)((totalram_pages - totalhigh_pages) *
1691 DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT;
1693 if (mem > ULONG_MAX)
1698 * Get the size of vmalloc space the same way as VMALLOC_TOTAL
1699 * in fs/proc/internal.h
1701 if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100)
1702 mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100;
1705 dm_bufio_default_cache_size = mem;
1707 mutex_lock(&dm_bufio_clients_lock);
1708 __cache_size_refresh();
1709 mutex_unlock(&dm_bufio_clients_lock);
1711 dm_bufio_wq = create_singlethread_workqueue("dm_bufio_cache");
1715 INIT_DELAYED_WORK(&dm_bufio_work, work_fn);
1716 queue_delayed_work(dm_bufio_wq, &dm_bufio_work,
1717 DM_BUFIO_WORK_TIMER_SECS * HZ);
1723 * This is called once when unloading the dm_bufio module.
1725 static void __exit dm_bufio_exit(void)
1730 cancel_delayed_work_sync(&dm_bufio_work);
1731 destroy_workqueue(dm_bufio_wq);
1733 for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) {
1734 struct kmem_cache *kc = dm_bufio_caches[i];
1737 kmem_cache_destroy(kc);
1740 for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
1741 kfree(dm_bufio_cache_names[i]);
1743 if (dm_bufio_client_count) {
1744 DMCRIT("%s: dm_bufio_client_count leaked: %d",
1745 __func__, dm_bufio_client_count);
1749 if (dm_bufio_current_allocated) {
1750 DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
1751 __func__, dm_bufio_current_allocated);
1755 if (dm_bufio_allocated_get_free_pages) {
1756 DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
1757 __func__, dm_bufio_allocated_get_free_pages);
1761 if (dm_bufio_allocated_vmalloc) {
1762 DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
1763 __func__, dm_bufio_allocated_vmalloc);
1771 module_init(dm_bufio_init)
1772 module_exit(dm_bufio_exit)
1774 module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR);
1775 MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
1777 module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);
1778 MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
1780 module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);
1781 MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
1783 module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO);
1784 MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
1786 module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO);
1787 MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
1789 module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO);
1790 MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
1792 module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO);
1793 MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
1795 MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
1796 MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
1797 MODULE_LICENSE("GPL");