diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 9daff9b77cee..1e000ec73bd6 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -321,37 +321,42 @@ enum data_mode {
 };
 
 struct dm_buffer {
+	/* protected by the locks in dm_buffer_cache */
 	struct rb_node node;
-	struct list_head lru_list;
-	struct list_head global_list;
 
+	/* immutable, so don't need protecting */
 	sector_t block;
 	void *data;
 	unsigned char data_mode;		/* DATA_MODE_* */
 
-	unsigned int accessed;
-	unsigned int __hold_count;
+	/*
+	 * These two fields are used in isolation, so do not need
+	 * a surrounding lock.
+	 */
+	atomic_t hold_count;
 	unsigned long last_accessed;
 
+	/*
+	 * Everything else is protected by the mutex in
+	 * dm_bufio_client
+	 */
+	unsigned long state;
+	struct lru_entry lru;
 	unsigned char list_mode;		/* LIST_* */
 	blk_status_t read_error;
 	blk_status_t write_error;
-	unsigned long state;
 	unsigned int dirty_start;
 	unsigned int dirty_end;
 	unsigned int write_start;
 	unsigned int write_end;
-	struct dm_bufio_client *c;
 	struct list_head write_list;
+	struct dm_bufio_client *c;
 	void (*end_io)(struct dm_buffer *b, blk_status_t bs);
 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
 #define MAX_STACK 10
 	unsigned int stack_len;
 	unsigned long stack_entries[MAX_STACK];
 #endif
-	/* Temp members to allow dm_buffer_cache code to compile */
-	atomic_t hold_count;
-	struct lru_entry lru;
 };
 
 /*--------------------------------------------------------------*/
@@ -814,7 +819,7 @@ static void cache_remove_range(struct dm_buffer_cache *bc,
 
 /*
  * Linking of buffers:
- *	All buffers are linked to buffer_tree with their node field.
+ *	All buffers are linked to buffer_cache with their node field.
  *
  *	Clean buffers that are not being written (B_WRITING not set)
  *	are linked to lru[LIST_CLEAN] with their lru_list field.
@@ -832,9 +837,6 @@ struct dm_bufio_client {
 	spinlock_t spinlock;
 	bool no_sleep;
 
-	struct list_head lru[LIST_SIZE];
-	unsigned long n_buffers[LIST_SIZE];
-
 	struct block_device *bdev;
 	unsigned int block_size;
 	s8 sectors_per_block_bits;
@@ -849,7 +851,7 @@ struct dm_bufio_client {
 
 	unsigned int minimum_buffers;
 
-	struct rb_root buffer_tree;
+	struct dm_buffer_cache cache;
 	wait_queue_head_t free_buffer_wait;
 
 	sector_t start;
@@ -861,6 +863,11 @@ struct dm_bufio_client {
 	struct shrinker shrinker;
 	struct work_struct shrink_work;
 	atomic_long_t need_shrink;
+
+	/*
+	 * Used by global_cleanup to sort the clients list.
+	 */
+	unsigned long oldest_buffer;
 };
 
 static DEFINE_STATIC_KEY_FALSE(no_sleep_enabled);
@@ -877,14 +884,6 @@ static void dm_bufio_lock(struct dm_bufio_client *c)
 		mutex_lock_nested(&c->lock, dm_bufio_in_request());
 }
 
-static int dm_bufio_trylock(struct dm_bufio_client *c)
-{
-	if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
-		return spin_trylock_bh(&c->spinlock);
-	else
-		return mutex_trylock(&c->lock);
-}
-
 static void dm_bufio_unlock(struct dm_bufio_client *c)
 {
 	if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
@@ -913,10 +912,6 @@ static unsigned long dm_bufio_cache_size_latch;
 
 static DEFINE_SPINLOCK(global_spinlock);
 
-static LIST_HEAD(global_queue);
-
-static unsigned long global_num;
-
 /*
  * Buffers are freed after this timeout
  */
@@ -958,78 +953,6 @@ static void buffer_record_stack(struct dm_buffer *b)
 }
 #endif
 
-/*
- *----------------------------------------------------------------
- * A red/black tree acts as an index for all the buffers.
- *----------------------------------------------------------------
- */
-static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
-{
-	struct rb_node *n = c->buffer_tree.rb_node;
-	struct dm_buffer *b;
-
-	while (n) {
-		b = container_of(n, struct dm_buffer, node);
-
-		if (b->block == block)
-			return b;
-
-		n = block < b->block ? n->rb_left : n->rb_right;
-	}
-
-	return NULL;
-}
-
-static struct dm_buffer *__find_next_old(struct dm_bufio_client *c, sector_t block)
-{
-	struct rb_node *n = c->buffer_tree.rb_node;
-	struct dm_buffer *b;
-	struct dm_buffer *best = NULL;
-
-	while (n) {
-		b = container_of(n, struct dm_buffer, node);
-
-		if (b->block == block)
-			return b;
-
-		if (block <= b->block) {
-			n = n->rb_left;
-			best = b;
-		} else {
-			n = n->rb_right;
-		}
-	}
-
-	return best;
-}
-
-static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
-{
-	struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL;
-	struct dm_buffer *found;
-
-	while (*new) {
-		found = container_of(*new, struct dm_buffer, node);
-
-		if (found->block == b->block) {
-			BUG_ON(found != b);
-			return;
-		}
-
-		parent = *new;
-		new = b->block < found->block ?
-			&found->node.rb_left : &found->node.rb_right;
-	}
-
-	rb_link_node(&b->node, parent, new);
-	rb_insert_color(&b->node, &c->buffer_tree);
-}
-
-static void __remove(struct dm_bufio_client *c, struct dm_buffer *b)
-{
-	rb_erase(&b->node, &c->buffer_tree);
-}
-
 /*----------------------------------------------------------------*/
 
 static void adjust_total_allocated(struct dm_buffer *b, bool unlink)
@@ -1057,16 +980,9 @@ static void adjust_total_allocated(struct dm_buffer *b, bool unlink)
 	if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
 		dm_bufio_peak_allocated = dm_bufio_current_allocated;
 
-	b->accessed = 1;
-
 	if (!unlink) {
-		list_add(&b->global_list, &global_queue);
-		global_num++;
 		if (dm_bufio_current_allocated > dm_bufio_cache_size)
 			queue_work(dm_bufio_wq, &dm_bufio_replacement_work);
-	} else {
-		list_del(&b->global_list);
-		global_num--;
 	}
 
 	spin_unlock(&global_spinlock);
@@ -1196,6 +1112,7 @@ static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
 		kmem_cache_free(c->slab_buffer, b);
 		return NULL;
 	}
+	adjust_total_allocated(b, false);
 
 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
 	b->stack_len = 0;
@@ -1210,61 +1127,11 @@ static void free_buffer(struct dm_buffer *b)
 {
 	struct dm_bufio_client *c = b->c;
 
+	adjust_total_allocated(b, true);
 	free_buffer_data(c, b->data, b->data_mode);
 	kmem_cache_free(c->slab_buffer, b);
 }
 
-/*
- * Link buffer to the buffer tree and clean or dirty queue.
- */
-static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
-{
-	struct dm_bufio_client *c = b->c;
-
-	c->n_buffers[dirty]++;
-	b->block = block;
-	b->list_mode = dirty;
-	list_add(&b->lru_list, &c->lru[dirty]);
-	__insert(b->c, b);
-	b->last_accessed = jiffies;
-
-	adjust_total_allocated(b, false);
-}
-
-/*
- * Unlink buffer from the buffer tree and dirty or clean queue.
- */
-static void __unlink_buffer(struct dm_buffer *b)
-{
-	struct dm_bufio_client *c = b->c;
-
-	BUG_ON(!c->n_buffers[b->list_mode]);
-
-	c->n_buffers[b->list_mode]--;
-	__remove(b->c, b);
-	list_del(&b->lru_list);
-
-	adjust_total_allocated(b, true);
-}
-
-/*
- * Place the buffer to the head of dirty or clean LRU queue.
- */
-static void __relink_lru(struct dm_buffer *b, int dirty)
-{
-	struct dm_bufio_client *c = b->c;
-
-	b->accessed = 1;
-
-	BUG_ON(!c->n_buffers[b->list_mode]);
-
-	c->n_buffers[b->list_mode]--;
-	c->n_buffers[dirty]++;
-	b->list_mode = dirty;
-	list_move(&b->lru_list, &c->lru[dirty]);
-	b->last_accessed = jiffies;
-}
-
 /*
  *--------------------------------------------------------------------------
  * Submit I/O on the buffer.
@@ -1504,7 +1371,7 @@ static void __flush_write_list(struct list_head *write_list)
  */
 static void __make_buffer_clean(struct dm_buffer *b)
 {
-	BUG_ON(b->__hold_count);
+	BUG_ON(atomic_read(&b->hold_count));
 
 	/* smp_load_acquire() pairs with read_endio()'s smp_mb__before_atomic() */
 	if (!smp_load_acquire(&b->state))	/* fast case */
@@ -1515,6 +1382,36 @@ static void __make_buffer_clean(struct dm_buffer *b)
 	wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
 }
 
+static enum evict_result is_clean(struct dm_buffer *b, void *context)
+{
+	struct dm_bufio_client *c = context;
+
+	/* These should never happen */
+	if (WARN_ON_ONCE(test_bit(B_WRITING, &b->state)))
+		return ER_DONT_EVICT;
+	if (WARN_ON_ONCE(test_bit(B_DIRTY, &b->state)))
+		return ER_DONT_EVICT;
+	if (WARN_ON_ONCE(b->list_mode != LIST_CLEAN))
+		return ER_DONT_EVICT;
+
+	if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep &&
+	    unlikely(test_bit(B_READING, &b->state)))
+		return ER_DONT_EVICT;
+
+	return ER_EVICT;
+}
+
+static enum evict_result is_dirty(struct dm_buffer *b, void *context)
+{
+	/* These should never happen */
+	if (WARN_ON_ONCE(test_bit(B_READING, &b->state)))
+		return ER_DONT_EVICT;
+	if (WARN_ON_ONCE(b->list_mode != LIST_DIRTY))
+		return ER_DONT_EVICT;
+
+	return ER_EVICT;
+}
+
 /*
  * Find some buffer that is not held by anybody, clean it, unlink it and
  * return it.
@@ -1523,34 +1420,20 @@ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
 {
 	struct dm_buffer *b;
 
-	list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) {
-		BUG_ON(test_bit(B_WRITING, &b->state));
-		BUG_ON(test_bit(B_DIRTY, &b->state));
-
-		if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep &&
-		    unlikely(test_bit_acquire(B_READING, &b->state)))
-			continue;
-
-		if (!b->__hold_count) {
-			__make_buffer_clean(b);
-			__unlink_buffer(b);
-			return b;
-		}
-		cond_resched();
+	b = cache_evict(&c->cache, LIST_CLEAN, is_clean, c);
+	if (b) {
+		/* this also waits for pending reads */
+		__make_buffer_clean(b);
+		return b;
 	}
 
 	if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
 		return NULL;
 
-	list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
-		BUG_ON(test_bit(B_READING, &b->state));
-
-		if (!b->__hold_count) {
-			__make_buffer_clean(b);
-			__unlink_buffer(b);
-			return b;
-		}
-		cond_resched();
+	b = cache_evict(&c->cache, LIST_DIRTY, is_dirty, NULL);
+	if (b) {
+		__make_buffer_clean(b);
+		return b;
 	}
 
 	return NULL;
@@ -1571,7 +1454,12 @@ static void __wait_for_free_buffer(struct dm_bufio_client *c)
 	set_current_state(TASK_UNINTERRUPTIBLE);
 	dm_bufio_unlock(c);
 
-	io_schedule();
+	/*
+	 * It's possible to miss a wake up event since we don't always
+	 * hold c->lock when wake_up is called.  So we have a timeout here,
+	 * just in case.
+	 */
+	io_schedule_timeout(5 * HZ);
 
 	remove_wait_queue(&c->free_buffer_wait, &wait);
 
@@ -1629,9 +1517,8 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client
 		}
 
 		if (!list_empty(&c->reserved_buffers)) {
-			b = list_entry(c->reserved_buffers.next,
-				       struct dm_buffer, lru_list);
-			list_del(&b->lru_list);
+			b = list_to_buffer(c->reserved_buffers.next);
+			list_del(&b->lru.list);
 			c->need_reserved_buffers++;
 
 			return b;
@@ -1665,36 +1552,56 @@ static void __free_buffer_wake(struct dm_buffer *b)
 {
 	struct dm_bufio_client *c = b->c;
 
+	b->block = -1;
 	if (!c->need_reserved_buffers)
 		free_buffer(b);
 	else {
-		list_add(&b->lru_list, &c->reserved_buffers);
+		list_add(&b->lru.list, &c->reserved_buffers);
 		c->need_reserved_buffers--;
 	}
 
 	wake_up(&c->free_buffer_wait);
 }
 
+static enum evict_result cleaned(struct dm_buffer *b, void *context)
+{
+	if (WARN_ON_ONCE(test_bit(B_READING, &b->state)))
+		return ER_DONT_EVICT; /* should never happen */
+
+	if (test_bit(B_DIRTY, &b->state) || test_bit(B_WRITING, &b->state))
+		return ER_DONT_EVICT;
+	else
+		return ER_EVICT;
+}
+
+static void __move_clean_buffers(struct dm_bufio_client *c)
+{
+	cache_mark_many(&c->cache, LIST_DIRTY, LIST_CLEAN, cleaned, NULL);
+}
+
+struct write_context {
+	int no_wait;
+	struct list_head *write_list;
+};
+
+static enum it_action write_one(struct dm_buffer *b, void *context)
+{
+	struct write_context *wc = context;
+
+	if (wc->no_wait && test_bit(B_WRITING, &b->state))
+		return IT_COMPLETE;
+
+	__write_dirty_buffer(b, wc->write_list);
+	return IT_NEXT;
+}
+
 static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
 					struct list_head *write_list)
 {
-	struct dm_buffer *b, *tmp;
+	struct write_context wc = {.no_wait = no_wait, .write_list = write_list};
 
-	list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
-		BUG_ON(test_bit(B_READING, &b->state));
-
-		if (!test_bit(B_DIRTY, &b->state) &&
-		    !test_bit(B_WRITING, &b->state)) {
-			__relink_lru(b, LIST_CLEAN);
-			continue;
-		}
-
-		if (no_wait && test_bit(B_WRITING, &b->state))
-			return;
-
-		__write_dirty_buffer(b, write_list);
-		cond_resched();
-	}
+	__move_clean_buffers(c);
+	cache_iterate(&c->cache, LIST_DIRTY, write_one, &wc);
 }
 
 /*
@@ -1705,7 +1612,8 @@ static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
 static void __check_watermark(struct dm_bufio_client *c,
 			      struct list_head *write_list)
 {
-	if (c->n_buffers[LIST_DIRTY] > c->n_buffers[LIST_CLEAN] * DM_BUFIO_WRITEBACK_RATIO)
+	if (cache_count(&c->cache, LIST_DIRTY) >
+	    cache_count(&c->cache, LIST_CLEAN) * DM_BUFIO_WRITEBACK_RATIO)
 		__write_dirty_buffers_async(c, 1, write_list);
 }
 
@@ -1715,6 +1623,21 @@ static void __check_watermark(struct dm_bufio_client *c,
  *--------------------------------------------------------------
  */
 
+static void cache_put_and_wake(struct dm_bufio_client *c, struct dm_buffer *b)
+{
+	/*
+	 * Relying on waitqueue_active() is racey, but we sleep
+	 * with schedule_timeout anyway.
+	 */
+	if (cache_put(&c->cache, b) &&
+	    unlikely(waitqueue_active(&c->free_buffer_wait)))
+		wake_up(&c->free_buffer_wait);
+}
+
+/*
+ * This assumes you have already checked the cache to see if the buffer
+ * is already present (it will recheck after dropping the lock for allocation).
+ */
 static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
 				     enum new_flag nf, int *need_submit,
 				     struct list_head *write_list)
@@ -1723,11 +1646,8 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
 
 	*need_submit = 0;
 
-	b = __find(c, block);
-	if (b)
-		goto found_buffer;
-
-	if (nf == NF_GET)
+	/* This can't be called with NF_GET */
+	if (WARN_ON_ONCE(nf == NF_GET))
 		return NULL;
 
 	new_b = __alloc_buffer_wait(c, nf);
@@ -1738,7 +1658,7 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
 	 * We've had a period where the mutex was unlocked, so need to
 	 * recheck the buffer tree.
 	 */
-	b = __find(c, block);
+	b = cache_get(&c->cache, block);
 	if (b) {
 		__free_buffer_wake(new_b);
 		goto found_buffer;
@@ -1747,24 +1667,35 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
 	__check_watermark(c, write_list);
 
 	b = new_b;
-	b->__hold_count = 1;
+	atomic_set(&b->hold_count, 1);
+	WRITE_ONCE(b->last_accessed, jiffies);
+	b->block = block;
 	b->read_error = 0;
 	b->write_error = 0;
-	__link_buffer(b, block, LIST_CLEAN);
+	b->list_mode = LIST_CLEAN;
 
-	if (nf == NF_FRESH) {
+	if (nf == NF_FRESH)
 		b->state = 0;
-		return b;
+	else {
+		b->state = 1 << B_READING;
+		*need_submit = 1;
 	}
 
-	b->state = 1 << B_READING;
-	*need_submit = 1;
+	/*
+	 * We mustn't insert into the cache until the B_READING state
+	 * is set.  Otherwise another thread could get it and use
+	 * it before it had been read.
+	 */
+	cache_insert(&c->cache, b);
 
 	return b;
 
 found_buffer:
-	if (nf == NF_PREFETCH)
+	if (nf == NF_PREFETCH) {
+		cache_put_and_wake(c, b);
 		return NULL;
+	}
+
 	/*
 	 * Note: it is essential that we don't wait for the buffer to be
 	 * read if dm_bufio_get function is used. Both dm_bufio_get and
@@ -1772,12 +1703,11 @@ found_buffer:
 	 * If the user called both dm_bufio_prefetch and dm_bufio_get on
 	 * the same buffer, it would deadlock if we waited.
 	 */
-	if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state)))
+	if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) {
+		cache_put_and_wake(c, b);
 		return NULL;
+	}
 
-	b->__hold_count++;
-	__relink_lru(b, test_bit(B_DIRTY, &b->state) ||
-		     test_bit(B_WRITING, &b->state));
 	return b;
 }
 
@@ -1807,18 +1737,50 @@ static void read_endio(struct dm_buffer *b, blk_status_t status)
 static void *new_read(struct dm_bufio_client *c, sector_t block,
 		      enum new_flag nf, struct dm_buffer **bp)
 {
-	int need_submit;
+	int need_submit = 0;
 	struct dm_buffer *b;
 
 	LIST_HEAD(write_list);
 
-	dm_bufio_lock(c);
-	b = __bufio_new(c, block, nf, &need_submit, &write_list);
+	*bp = NULL;
+
+	/*
+	 * Fast path, hopefully the block is already in the cache.  No need
+	 * to get the client lock for this.
+	 */
+	b = cache_get(&c->cache, block);
+	if (b) {
+		if (nf == NF_PREFETCH) {
+			cache_put_and_wake(c, b);
+			return NULL;
+		}
+
+		/*
+		 * Note: it is essential that we don't wait for the buffer to be
+		 * read if dm_bufio_get function is used. Both dm_bufio_get and
+		 * dm_bufio_prefetch can be used in the driver request routine.
+		 * If the user called both dm_bufio_prefetch and dm_bufio_get on
+		 * the same buffer, it would deadlock if we waited.
+		 */
+		if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) {
+			cache_put_and_wake(c, b);
+			return NULL;
+		}
+	}
+
+	if (!b) {
+		if (nf == NF_GET)
+			return NULL;
+
+		dm_bufio_lock(c);
+		b = __bufio_new(c, block, nf, &need_submit, &write_list);
+		dm_bufio_unlock(c);
+	}
+
 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
-	if (b && b->hold_count == 1)
+	if (b && (atomic_read(&b->hold_count) == 1))
 		buffer_record_stack(b);
 #endif
-	dm_bufio_unlock(c);
 
 	__flush_write_list(&write_list);
 
@@ -1881,12 +1843,19 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 		return; /* should never happen */
 
 	blk_start_plug(&plug);
-	dm_bufio_lock(c);
 
 	for (; n_blocks--; block++) {
 		int need_submit;
 		struct dm_buffer *b;
 
+		b = cache_get(&c->cache, block);
+		if (b) {
+			/* already in cache */
+			cache_put_and_wake(c, b);
+			continue;
+		}
+
+		dm_bufio_lock(c);
 		b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
 				&write_list);
 		if (unlikely(!list_empty(&write_list))) {
@@ -1909,10 +1878,9 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 				goto flush_plug;
 			dm_bufio_lock(c);
 		}
+		dm_bufio_unlock(c);
 	}
 
-	dm_bufio_unlock(c);
-
 flush_plug:
 	blk_finish_plug(&plug);
 }
@@ -1922,29 +1890,28 @@ void dm_bufio_release(struct dm_buffer *b)
 {
 	struct dm_bufio_client *c = b->c;
 
-	dm_bufio_lock(c);
+	/*
+	 * If there were errors on the buffer, and the buffer is not
+	 * to be written, free the buffer. There is no point in caching
+	 * invalid buffer.
+	 */
+	if ((b->read_error || b->write_error) &&
+	    !test_bit_acquire(B_READING, &b->state) &&
+	    !test_bit(B_WRITING, &b->state) &&
+	    !test_bit(B_DIRTY, &b->state)) {
+		dm_bufio_lock(c);
 
-	BUG_ON(!b->__hold_count);
-
-	b->__hold_count--;
-	if (!b->__hold_count) {
-		wake_up(&c->free_buffer_wait);
-
-		/*
-		 * If there were errors on the buffer, and the buffer is not
-		 * to be written, free the buffer. There is no point in caching
-		 * invalid buffer.
-		 */
-		if ((b->read_error || b->write_error) &&
-		    !test_bit_acquire(B_READING, &b->state) &&
-		    !test_bit(B_WRITING, &b->state) &&
-		    !test_bit(B_DIRTY, &b->state)) {
-			__unlink_buffer(b);
+		/* cache remove can fail if there are other holders */
+		if (cache_remove(&c->cache, b)) {
 			__free_buffer_wake(b);
+			dm_bufio_unlock(c);
+			return;
 		}
+
+		dm_bufio_unlock(c);
 	}
 
-	dm_bufio_unlock(c);
+	cache_put_and_wake(c, b);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_release);
 
@@ -1963,7 +1930,7 @@ void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
 	if (!test_and_set_bit(B_DIRTY, &b->state)) {
 		b->dirty_start = start;
 		b->dirty_end = end;
-		__relink_lru(b, LIST_DIRTY);
+		cache_mark(&c->cache, b, LIST_DIRTY);
 	} else {
 		if (start < b->dirty_start)
 			b->dirty_start = start;
@@ -2002,11 +1969,19 @@ EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
  *
  * Finally, we flush hardware disk cache.
  */
+static bool is_writing(struct lru_entry *e, void *context)
+{
+	struct dm_buffer *b = le_to_buffer(e);
+
+	return test_bit(B_WRITING, &b->state);
+}
+
 int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
 {
 	int a, f;
-	unsigned long buffers_processed = 0;
-	struct dm_buffer *b, *tmp;
+	unsigned long nr_buffers;
+	struct lru_entry *e;
+	struct lru_iter it;
 
 	LIST_HEAD(write_list);
 
@@ -2016,52 +1991,32 @@ int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
 	__flush_write_list(&write_list);
 	dm_bufio_lock(c);
 
-again:
-	list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) {
-		int dropped_lock = 0;
-
-		if (buffers_processed < c->n_buffers[LIST_DIRTY])
-			buffers_processed++;
+	nr_buffers = cache_count(&c->cache, LIST_DIRTY);
+	lru_iter_begin(&c->cache.lru[LIST_DIRTY], &it);
+	while ((e = lru_iter_next(&it, is_writing, c))) {
+		struct dm_buffer *b = le_to_buffer(e);
+		__cache_inc_buffer(b);
 
 		BUG_ON(test_bit(B_READING, &b->state));
 
-		if (test_bit(B_WRITING, &b->state)) {
-			if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
-				dropped_lock = 1;
-				b->__hold_count++;
-				dm_bufio_unlock(c);
-				wait_on_bit_io(&b->state, B_WRITING,
-					       TASK_UNINTERRUPTIBLE);
-				dm_bufio_lock(c);
-				b->__hold_count--;
-			} else
-				wait_on_bit_io(&b->state, B_WRITING,
-					       TASK_UNINTERRUPTIBLE);
+		if (nr_buffers) {
+			nr_buffers--;
+			dm_bufio_unlock(c);
+			wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
+			dm_bufio_lock(c);
+		} else {
+			wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
 		}
 
-		if (!test_bit(B_DIRTY, &b->state) &&
-		    !test_bit(B_WRITING, &b->state))
-			__relink_lru(b, LIST_CLEAN);
+		if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state))
+			cache_mark(&c->cache, b, LIST_CLEAN);
+
+		cache_put_and_wake(c, b);
 
 		cond_resched();
-
-		/*
-		 * If we dropped the lock, the list is no longer consistent,
-		 * so we must restart the search.
-		 *
-		 * In the most common case, the buffer just processed is
-		 * relinked to the clean list, so we won't loop scanning the
-		 * same buffer again and again.
-		 *
-		 * This may livelock if there is another thread simultaneously
-		 * dirtying buffers, so we count the number of buffers walked
-		 * and if it exceeds the total number of buffers, it means that
-		 * someone is doing some writes simultaneously with us.  In
-		 * this case, stop, dropping the lock.
-		 */
-		if (dropped_lock)
-			goto again;
 	}
+	lru_iter_end(&it);
+
 	wake_up(&c->free_buffer_wait);
 	dm_bufio_unlock(c);
 
@@ -2122,12 +2077,23 @@ int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t c
 }
 EXPORT_SYMBOL_GPL(dm_bufio_issue_discard);
 
-static void forget_buffer_locked(struct dm_buffer *b)
+static bool forget_buffer(struct dm_bufio_client *c, sector_t block)
 {
-	if (likely(!b->__hold_count) && likely(!smp_load_acquire(&b->state))) {
-		__unlink_buffer(b);
-		__free_buffer_wake(b);
+	struct dm_buffer *b;
+
+	b = cache_get(&c->cache, block);
+	if (b) {
+		if (likely(!smp_load_acquire(&b->state))) {
+			if (cache_remove(&c->cache, b))
+				__free_buffer_wake(b);
+			else
+				cache_put_and_wake(c, b);
+		} else {
+			cache_put_and_wake(c, b);
+		}
 	}
+
+	return b ? true : false;
 }
 
 /*
@@ -2138,38 +2104,22 @@ static void forget_buffer_locked(struct dm_buffer *b)
  */
 void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
 {
-	struct dm_buffer *b;
-
 	dm_bufio_lock(c);
-
-	b = __find(c, block);
-	if (b)
-		forget_buffer_locked(b);
-
+	forget_buffer(c, block);
 	dm_bufio_unlock(c);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_forget);
 
+static enum evict_result idle(struct dm_buffer *b, void *context)
+{
+	return b->state ? ER_DONT_EVICT : ER_EVICT;
+}
+
 void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks)
 {
-	struct dm_buffer *b;
-	sector_t end_block = block + n_blocks;
-
-	while (block < end_block) {
-		dm_bufio_lock(c);
-
-		b = __find_next_old(c, block);
-		if (b) {
-			block = b->block + 1;
-			forget_buffer_locked(b);
-		}
-
-		dm_bufio_unlock(c);
-
-		if (!b)
-			break;
-	}
-
+	dm_bufio_lock(c);
+	cache_remove_range(&c->cache, block, block + n_blocks, idle, __free_buffer_wake);
+	dm_bufio_unlock(c);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_forget_buffers);
 
@@ -2231,11 +2181,26 @@ struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
 }
 EXPORT_SYMBOL_GPL(dm_bufio_get_client);
 
+static enum it_action warn_leak(struct dm_buffer *b, void *context)
+{
+	bool *warned = context;
+
+	WARN_ON(!(*warned));
+	*warned = true;
+	DMERR("leaked buffer %llx, hold count %u, list %d",
+	      (unsigned long long)b->block, atomic_read(&b->hold_count), b->list_mode);
+#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
+	stack_trace_print(b->stack_entries, b->stack_len, 1);
+	/* mark unclaimed to avoid WARN_ON at end of drop_buffers() */
+	atomic_set(&b->hold_count, 0);
+#endif
+	return IT_NEXT;
+}
+
 static void drop_buffers(struct dm_bufio_client *c)
 {
-	struct dm_buffer *b;
 	int i;
-	bool warned = false;
+	struct dm_buffer *b;
 
 	if (WARN_ON(dm_bufio_in_request()))
 		return; /* should never happen */
@@ -2250,18 +2215,11 @@ static void drop_buffers(struct dm_bufio_client *c)
 	while ((b = __get_unclaimed_buffer(c)))
 		__free_buffer_wake(b);
 
-	for (i = 0; i < LIST_SIZE; i++)
-		list_for_each_entry(b, &c->lru[i], lru_list) {
-			WARN_ON(!warned);
-			warned = true;
-			DMERR("leaked buffer %llx, hold count %u, list %d",
-			      (unsigned long long)b->block, b->__hold_count, i);
-#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
-			stack_trace_print(b->stack_entries, b->stack_len, 1);
-			/* mark unclaimed to avoid WARN_ON below */
-			b->hold_count = 0;
-#endif
-		}
+	for (i = 0; i < LIST_SIZE; i++) {
+		bool warned = false;
+
+		cache_iterate(&c->cache, i, warn_leak, &warned);
+	}
 
 #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
 	while ((b = __get_unclaimed_buffer(c)))
@@ -2269,39 +2227,11 @@ static void drop_buffers(struct dm_bufio_client *c)
 #endif
 
 	for (i = 0; i < LIST_SIZE; i++)
-		WARN_ON(!list_empty(&c->lru[i]));
+		WARN_ON(cache_count(&c->cache, i));
 
 	dm_bufio_unlock(c);
 }
 
-/*
- * We may not be able to evict this buffer if IO pending or the client
- * is still using it.  Caller is expected to know buffer is too old.
- *
- * And if GFP_NOFS is used, we must not do any I/O because we hold
- * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
- * rerouted to different bufio client.
- */
-static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
-{
-	if (!(gfp & __GFP_FS) ||
-	    (static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) {
-		if (test_bit_acquire(B_READING, &b->state) ||
-		    test_bit(B_WRITING, &b->state) ||
-		    test_bit(B_DIRTY, &b->state))
-			return false;
-	}
-
-	if (b->__hold_count)
-		return false;
-
-	__make_buffer_clean(b);
-	__unlink_buffer(b);
-	__free_buffer_wake(b);
-
-	return true;
-}
-
 static unsigned long get_retain_buffers(struct dm_bufio_client *c)
 {
 	unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes);
@@ -2317,22 +2247,28 @@ static unsigned long get_retain_buffers(struct dm_bufio_client *c)
 static void __scan(struct dm_bufio_client *c)
 {
 	int l;
-	struct dm_buffer *b, *tmp;
+	struct dm_buffer *b;
 	unsigned long freed = 0;
-	unsigned long count = c->n_buffers[LIST_CLEAN] +
-			      c->n_buffers[LIST_DIRTY];
 	unsigned long retain_target = get_retain_buffers(c);
+	unsigned long count = cache_total(&c->cache);
 
 	for (l = 0; l < LIST_SIZE; l++) {
-		list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
+		while (true) {
 			if (count - freed <= retain_target)
 				atomic_long_set(&c->need_shrink, 0);
 			if (!atomic_long_read(&c->need_shrink))
-				return;
-			if (__try_evict_buffer(b, GFP_KERNEL)) {
-				atomic_long_dec(&c->need_shrink);
-				freed++;
-			}
+				break;
+
+			b = cache_evict(&c->cache, l,
+					l == LIST_CLEAN ? is_clean : is_dirty, c);
+			if (!b)
+				break;
+
+			__make_buffer_clean(b);
+			__free_buffer_wake(b);
+
+			atomic_long_dec(&c->need_shrink);
+			freed++;
 			cond_resched();
 		}
 	}
@@ -2361,8 +2297,7 @@ static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink
 static unsigned long dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
 {
 	struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker);
-	unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) +
-			      READ_ONCE(c->n_buffers[LIST_DIRTY]);
+	unsigned long count = cache_total(&c->cache);
 	unsigned long retain_target = get_retain_buffers(c);
 	unsigned long queued_for_cleanup = atomic_long_read(&c->need_shrink);
 
@@ -2390,7 +2325,6 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 {
 	int r;
 	struct dm_bufio_client *c;
-	unsigned int i;
 	char slab_name[27];
 
 	if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) {
@@ -2404,7 +2338,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 		r = -ENOMEM;
 		goto bad_client;
 	}
-	c->buffer_tree = RB_ROOT;
+	cache_init(&c->cache);
 
 	c->bdev = bdev;
 	c->block_size = block_size;
@@ -2421,11 +2355,6 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 		static_branch_inc(&no_sleep_enabled);
 	}
 
-	for (i = 0; i < LIST_SIZE; i++) {
-		INIT_LIST_HEAD(&c->lru[i]);
-		c->n_buffers[i] = 0;
-	}
-
 	mutex_init(&c->lock);
 	spin_lock_init(&c->spinlock);
 	INIT_LIST_HEAD(&c->reserved_buffers);
@@ -2497,9 +2426,9 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
 
 bad:
 	while (!list_empty(&c->reserved_buffers)) {
-		struct dm_buffer *b = list_entry(c->reserved_buffers.next,
-						 struct dm_buffer, lru_list);
-		list_del(&b->lru_list);
+		struct dm_buffer *b = list_to_buffer(c->reserved_buffers.next);
+
+		list_del(&b->lru.list);
 		free_buffer(b);
 	}
 	kmem_cache_destroy(c->slab_cache);
@@ -2536,23 +2465,23 @@ void dm_bufio_client_destroy(struct dm_bufio_client *c)
 
 	mutex_unlock(&dm_bufio_clients_lock);
 
-	WARN_ON(!RB_EMPTY_ROOT(&c->buffer_tree));
 	WARN_ON(c->need_reserved_buffers);
 
 	while (!list_empty(&c->reserved_buffers)) {
-		struct dm_buffer *b = list_entry(c->reserved_buffers.next,
-						 struct dm_buffer, lru_list);
-		list_del(&b->lru_list);
+		struct dm_buffer *b = list_to_buffer(c->reserved_buffers.next);
+
+		list_del(&b->lru.list);
 		free_buffer(b);
 	}
 
 	for (i = 0; i < LIST_SIZE; i++)
-		if (c->n_buffers[i])
-			DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]);
+		if (cache_count(&c->cache, i))
+			DMERR("leaked buffer count %d: %lu", i, cache_count(&c->cache, i));
 
 	for (i = 0; i < LIST_SIZE; i++)
-		WARN_ON(c->n_buffers[i]);
+		WARN_ON(cache_count(&c->cache, i));
 
+	cache_destroy(&c->cache);
 	kmem_cache_destroy(c->slab_cache);
 	kmem_cache_destroy(c->slab_buffer);
 	dm_io_client_destroy(c->dm_io);
@@ -2569,6 +2498,8 @@ void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start)
 }
 EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset);
 
+/*--------------------------------------------------------------*/
+
 static unsigned int get_max_age_hz(void)
 {
 	unsigned int max_age = READ_ONCE(dm_bufio_max_age);
@@ -2581,13 +2512,74 @@ static unsigned int get_max_age_hz(void)
 
 static bool older_than(struct dm_buffer *b, unsigned long age_hz)
 {
-	return time_after_eq(jiffies, b->last_accessed + age_hz);
+	return time_after_eq(jiffies, READ_ONCE(b->last_accessed) + age_hz);
 }
 
-static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
+struct evict_params {
+	gfp_t gfp;
+	unsigned long age_hz;
+
+	/*
+	 * This gets updated with the largest last_accessed (ie. most
+	 * recently used) of the evicted buffers.  It will not be reinitialised
+	 * by __evict_many(), so you can use it across multiple invocations.
+	 */
+	unsigned long last_accessed;
+};
+
+/*
+ * We may not be able to evict this buffer if IO pending or the client
+ * is still using it.
+ *
+ * And if GFP_NOFS is used, we must not do any I/O because we hold
+ * dm_bufio_clients_lock and we would risk deadlock if the I/O gets
+ * rerouted to different bufio client.
+ */
+static enum evict_result select_for_evict(struct dm_buffer *b, void *context)
 {
-	struct dm_buffer *b, *tmp;
-	unsigned long retain_target = get_retain_buffers(c);
+	struct evict_params *params = context;
+
+	if (!(params->gfp & __GFP_FS) ||
+	    (static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) {
+		if (test_bit_acquire(B_READING, &b->state) ||
+		    test_bit(B_WRITING, &b->state) ||
+		    test_bit(B_DIRTY, &b->state))
+			return ER_DONT_EVICT;
+	}
+
+	return older_than(b, params->age_hz) ? ER_EVICT : ER_STOP;
+}
+
+static unsigned long __evict_many(struct dm_bufio_client *c,
+				  struct evict_params *params,
+				  int list_mode, unsigned long max_count)
+{
+	unsigned long count;
+	unsigned long last_accessed;
+	struct dm_buffer *b;
+
+	for (count = 0; count < max_count; count++) {
+		b = cache_evict(&c->cache, list_mode, select_for_evict, params);
+		if (!b)
+			break;
+
+		last_accessed = READ_ONCE(b->last_accessed);
+		if (time_after_eq(params->last_accessed, last_accessed))
+			params->last_accessed = last_accessed;
+
+		__make_buffer_clean(b);
+		__free_buffer_wake(b);
+
+		cond_resched();
+	}
+
+	return count;
+}
+
+static void evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
+{
+	struct evict_params params = {.gfp = 0, .age_hz = age_hz, .last_accessed = 0};
+	unsigned long retain = get_retain_buffers(c);
 	unsigned long count;
 	LIST_HEAD(write_list);
 
@@ -2600,91 +2592,13 @@ static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
 		dm_bufio_lock(c);
 	}
 
-	count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
-	list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) {
-		if (count <= retain_target)
-			break;
-
-		if (!older_than(b, age_hz))
-			break;
-
-		if (__try_evict_buffer(b, 0))
-			count--;
-
-		cond_resched();
-	}
+	count = cache_total(&c->cache);
+	if (count > retain)
+		__evict_many(c, &params, LIST_CLEAN, count - retain);
 
 	dm_bufio_unlock(c);
 }
 
-static void do_global_cleanup(struct work_struct *w)
-{
-	struct dm_bufio_client *locked_client = NULL;
-	struct dm_bufio_client *current_client;
-	struct dm_buffer *b;
-	unsigned int spinlock_hold_count;
-	unsigned long threshold = dm_bufio_cache_size -
-		dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO;
-	unsigned long loops = global_num * 2;
-
-	mutex_lock(&dm_bufio_clients_lock);
-
-	while (1) {
-		cond_resched();
-
-		spin_lock(&global_spinlock);
-		if (unlikely(dm_bufio_current_allocated <= threshold))
-			break;
-
-		spinlock_hold_count = 0;
-get_next:
-		if (!loops--)
-			break;
-		if (unlikely(list_empty(&global_queue)))
-			break;
-		b = list_entry(global_queue.prev, struct dm_buffer, global_list);
-
-		if (b->accessed) {
-			b->accessed = 0;
-			list_move(&b->global_list, &global_queue);
-			if (likely(++spinlock_hold_count < 16))
-				goto get_next;
-			spin_unlock(&global_spinlock);
-			continue;
-		}
-
-		current_client = b->c;
-		if (unlikely(current_client != locked_client)) {
-			if (locked_client)
-				dm_bufio_unlock(locked_client);
-
-			if (!dm_bufio_trylock(current_client)) {
-				spin_unlock(&global_spinlock);
-				dm_bufio_lock(current_client);
-				locked_client = current_client;
-				continue;
-			}
-
-			locked_client = current_client;
-		}
-
-		spin_unlock(&global_spinlock);
-
-		if (unlikely(!__try_evict_buffer(b, GFP_KERNEL))) {
-			spin_lock(&global_spinlock);
-			list_move(&b->global_list, &global_queue);
-			spin_unlock(&global_spinlock);
-		}
-	}
-
-	spin_unlock(&global_spinlock);
-
-	if (locked_client)
-		dm_bufio_unlock(locked_client);
-
-	mutex_unlock(&dm_bufio_clients_lock);
-}
-
 static void cleanup_old_buffers(void)
 {
 	unsigned long max_age_hz = get_max_age_hz();
@@ -2695,7 +2609,7 @@ static void cleanup_old_buffers(void)
 	__cache_size_refresh();
 
 	list_for_each_entry(c, &dm_bufio_all_clients, client_list)
-		__evict_old_buffers(c, max_age_hz);
+		evict_old_buffers(c, max_age_hz);
 
 	mutex_unlock(&dm_bufio_clients_lock);
 }
@@ -2708,6 +2622,107 @@ static void work_fn(struct work_struct *w)
 			   DM_BUFIO_WORK_TIMER_SECS * HZ);
 }
 
+/*--------------------------------------------------------------*/
+
+/*
+ * Global cleanup tries to evict the oldest buffers from across _all_
+ * the clients.  It does this by repeatedly evicting a few buffers from
+ * the client that holds the oldest buffer.  It's approximate, but hopefully
+ * good enough.
+ */
+static struct dm_bufio_client *__pop_client(void)
+{
+	struct list_head *h;
+
+	if (list_empty(&dm_bufio_all_clients))
+		return NULL;
+
+	h = dm_bufio_all_clients.next;
+	list_del(h);
+	return container_of(h, struct dm_bufio_client, client_list);
+}
+
+/*
+ * Inserts the client in the global client list based on its
+ * 'oldest_buffer' field.
+ */
+static void __insert_client(struct dm_bufio_client *new_client)
+{
+	struct dm_bufio_client *c;
+	struct list_head *h = dm_bufio_all_clients.next;
+
+	while (h != &dm_bufio_all_clients) {
+		c = container_of(h, struct dm_bufio_client, client_list);
+		if (time_after_eq(c->oldest_buffer, new_client->oldest_buffer))
+			break;
+		h = h->next;
+	}
+
+	list_add_tail(&new_client->client_list, h);
+}
+
+static unsigned long __evict_a_few(unsigned long nr_buffers)
+{
+	unsigned long count;
+	struct dm_bufio_client *c;
+	struct evict_params params = {
+		.gfp = GFP_KERNEL,
+		.age_hz = 0,
+		/* set to jiffies in case there are no buffers in this client */
+		.last_accessed = jiffies
+	};
+
+	c = __pop_client();
+	if (!c)
+		return 0;
+
+	dm_bufio_lock(c);
+	count = __evict_many(c, &params, LIST_CLEAN, nr_buffers);
+	dm_bufio_unlock(c);
+
+	if (count)
+		c->oldest_buffer = params.last_accessed;
+	__insert_client(c);
+
+	return count;
+}
+
+static void check_watermarks(void)
+{
+	LIST_HEAD(write_list);
+	struct dm_bufio_client *c;
+
+	mutex_lock(&dm_bufio_clients_lock);
+	list_for_each_entry(c, &dm_bufio_all_clients, client_list) {
+		dm_bufio_lock(c);
+		__check_watermark(c, &write_list);
+		dm_bufio_unlock(c);
+	}
+	mutex_unlock(&dm_bufio_clients_lock);
+
+	__flush_write_list(&write_list);
+}
+
+static void evict_old(void)
+{
+	unsigned long threshold = dm_bufio_cache_size -
+		dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO;
+
+	mutex_lock(&dm_bufio_clients_lock);
+	while (dm_bufio_current_allocated > threshold) {
+		if (!__evict_a_few(64))
+			break;
+		cond_resched();
+	}
+	mutex_unlock(&dm_bufio_clients_lock);
+}
+
+static void do_global_cleanup(struct work_struct *w)
+{
+	check_watermarks();
+	evict_old();
+}
+
 /*
  *--------------------------------------------------------------
  * Module setup