6 files changed, 439 insertions, 124 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0cbf3491bb7..42b03c4ee49 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -691,6 +691,7 @@ struct btrfs_space_info {
 	struct list_head block_groups;
 	spinlock_t lock;
 	struct rw_semaphore groups_sem;
+	atomic_t caching_threads;
 };
 
 /*
@@ -721,11 +722,17 @@ struct btrfs_free_cluster {
 	struct list_head block_group_list;
 };
 
+enum btrfs_caching_type {
+	BTRFS_CACHE_NO		= 0,
+	BTRFS_CACHE_STARTED	= 1,
+	BTRFS_CACHE_FINISHED	= 2,
+};
+
 struct btrfs_block_group_cache {
 	struct btrfs_key key;
 	struct btrfs_block_group_item item;
+	struct btrfs_fs_info *fs_info;
 	spinlock_t lock;
-	struct mutex cache_mutex;
 	u64 pinned;
 	u64 reserved;
 	u64 flags;
@@ -733,15 +740,19 @@ struct btrfs_block_group_cache {
 	int extents_thresh;
 	int free_extents;
 	int total_bitmaps;
-	int cached;
 	int ro;
 	int dirty;
 
+	/* cache tracking stuff */
+	wait_queue_head_t caching_q;
+	int cached;
+
 	struct btrfs_space_info *space_info;
 
 	/* free space cache stuff */
 	spinlock_t tree_lock;
 	struct rb_root free_space_offset;
+	u64 free_space;
 
 	/* block group cache stuff */
 	struct rb_node cache_node;
@@ -834,6 +845,7 @@ struct btrfs_fs_info {
 	atomic_t async_submit_draining;
 	atomic_t nr_async_bios;
 	atomic_t async_delalloc_pages;
+	atomic_t async_caching_threads;
 
 	/*
 	 * this is used by the balancing code to wait for all the pending
@@ -950,6 +962,9 @@ struct btrfs_root {
 	/* the node lock is held while changing the node pointer */
 	spinlock_t node_lock;
 
+	/* taken when updating the commit root */
+	struct rw_semaphore commit_root_sem;
+
 	struct extent_buffer *commit_root;
 	struct btrfs_root *log_root;
 	struct btrfs_root *reloc_root;
@@ -1911,7 +1926,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 			   struct btrfs_root *root, unsigned long count);
 int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len);
 int btrfs_update_pinned_extents(struct btrfs_root *root,
-				u64 bytenr, u64 num, int pin);
+				u64 bytenr, u64 num, int pin, int mark_free);
 int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct extent_buffer *leaf);
 int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
@@ -1996,6 +2011,7 @@ void btrfs_delalloc_reserve_space(struct btrfs_root *root, struct inode *inode,
 				 u64 bytes);
 void btrfs_delalloc_free_space(struct btrfs_root *root, struct inode *inode,
 			      u64 bytes);
+void btrfs_free_super_mirror_extents(struct btrfs_fs_info *info);
 /* ctree.c */
 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 		     int level, int *slot);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 55d9d188e69..ec2c915f7f4 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -907,6 +907,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 	spin_lock_init(&root->inode_lock);
 	mutex_init(&root->objectid_mutex);
 	mutex_init(&root->log_mutex);
+	init_rwsem(&root->commit_root_sem);
 	init_waitqueue_head(&root->log_writer_wait);
 	init_waitqueue_head(&root->log_commit_wait[0]);
 	init_waitqueue_head(&root->log_commit_wait[1]);
@@ -1566,6 +1567,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 	atomic_set(&fs_info->async_delalloc_pages, 0);
 	atomic_set(&fs_info->async_submit_draining, 0);
 	atomic_set(&fs_info->nr_async_bios, 0);
+	atomic_set(&fs_info->async_caching_threads, 0);
 	fs_info->sb = sb;
 	fs_info->max_extent = (u64)-1;
 	fs_info->max_inline = 8192 * 1024;
@@ -2337,6 +2339,7 @@ int close_ctree(struct btrfs_root *root)
 	free_extent_buffer(root->fs_info->csum_root->commit_root);
 
 	btrfs_free_block_groups(root->fs_info);
+	btrfs_free_super_mirror_extents(root->fs_info);
 
 	del_fs_roots(fs_info);
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 98697be6bdd..9a489cc89fd 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -21,6 +21,7 @@
 #include <linux/blkdev.h>
 #include <linux/sort.h>
 #include <linux/rcupdate.h>
+#include <linux/kthread.h>
 #include "compat.h"
 #include "hash.h"
 #include "ctree.h"
@@ -61,6 +62,13 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *extent_root, u64 alloc_bytes,
 			  u64 flags, int force);
 
+static noinline int
+block_group_cache_done(struct btrfs_block_group_cache *cache)
+{
+	smp_mb();
+	return cache->cached == BTRFS_CACHE_FINISHED;
+}
+
 static int block_group_bits(struct btrfs_block_group_cache *cache, u64 bits)
 {
 	return (cache->flags & bits) == bits;
@@ -145,21 +153,64 @@ block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr,
 	return ret;
 }
 
+void btrfs_free_super_mirror_extents(struct btrfs_fs_info *info)
+{
+	u64 start, end, last = 0;
+	int ret;
+
+	while (1) {
+		ret = find_first_extent_bit(&info->pinned_extents, last,
+					    &start, &end, EXTENT_LOCKED);
+		if (ret)
+			break;
+
+		unlock_extent(&info->pinned_extents, start, end, GFP_NOFS);
+		last = end+1;
+	}
+}
+
+static int remove_sb_from_cache(struct btrfs_root *root,
+				struct btrfs_block_group_cache *cache)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u64 bytenr;
+	u64 *logical;
+	int stripe_len;
+	int i, nr, ret;
+
+	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+		bytenr = btrfs_sb_offset(i);
+		ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
+				       cache->key.objectid, bytenr,
+				       0, &logical, &nr, &stripe_len);
+		BUG_ON(ret);
+		while (nr--) {
+			try_lock_extent(&fs_info->pinned_extents,
+					logical[nr],
+					logical[nr] + stripe_len - 1, GFP_NOFS);
+		}
+		kfree(logical);
+	}
+
+	return 0;
+}
+
 /*
  * this is only called by cache_block_group, since we could have freed extents
  * we need to check the pinned_extents for any extents that can't be used yet
  * since their free space will be released as soon as the transaction commits.
  */
-static int add_new_free_space(struct btrfs_block_group_cache *block_group,
+static u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
 			      struct btrfs_fs_info *info, u64 start, u64 end)
 {
-	u64 extent_start, extent_end, size;
+	u64 extent_start, extent_end, size, total_added = 0;
 	int ret;
 
 	while (start < end) {
 		ret = find_first_extent_bit(&info->pinned_extents, start,
 					    &extent_start, &extent_end,
-					    EXTENT_DIRTY);
+					    EXTENT_DIRTY|EXTENT_LOCKED|
+					    EXTENT_DELALLOC);
 		if (ret)
 			break;
 
@@ -167,6 +218,7 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
 			start = extent_end + 1;
 		} else if (extent_start > start && extent_start < end) {
 			size = extent_start - start;
+			total_added += size;
 			ret = btrfs_add_free_space(block_group, start,
 						   size);
 			BUG_ON(ret);
@@ -178,84 +230,139 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
 
 	if (start < end) {
 		size = end - start;
+		total_added += size;
 		ret = btrfs_add_free_space(block_group, start, size);
 		BUG_ON(ret);
 	}
 
-	return 0;
+	return total_added;
 }
 
-static int remove_sb_from_cache(struct btrfs_root *root,
-				struct btrfs_block_group_cache *cache)
+DEFINE_MUTEX(discard_mutex);
+
+/*
+ * if async kthreads are running when we cross transactions, we mark any pinned
+ * extents with EXTENT_DELALLOC and then let the caching kthreads clean up those
+ * extents when they are done.  Also we run this from btrfs_finish_extent_commit
+ * in case there were some pinned extents that were missed because we had
+ * already cached that block group.
+ */
+static void btrfs_discard_pinned_extents(struct btrfs_fs_info *fs_info,
+					 struct btrfs_block_group_cache *cache)
 {
-	u64 bytenr;
-	u64 *logical;
-	int stripe_len;
-	int i, nr, ret;
+	u64 start, end, last;
+	int ret;
 
-	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
-		bytenr = btrfs_sb_offset(i);
-		ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
-				       cache->key.objectid, bytenr, 0,
-				       &logical, &nr, &stripe_len);
-		BUG_ON(ret);
-		while (nr--) {
-			btrfs_remove_free_space(cache, logical[nr],
-						stripe_len);
+	if (!cache)
+		last = 0;
+	else
+		last = cache->key.objectid;
+
+	mutex_lock(&discard_mutex);
+	while (1) {
+		ret = find_first_extent_bit(&fs_info->pinned_extents, last,
+					    &start, &end, EXTENT_DELALLOC);
+		if (ret)
+			break;
+
+		if (cache && start >= cache->key.objectid + cache->key.offset)
+			break;
+
+
+		if (!cache) {
+			cache = btrfs_lookup_block_group(fs_info, start);
+			BUG_ON(!cache);
+
+			start = max(start, cache->key.objectid);
+			end = min(end, cache->key.objectid + cache->key.offset - 1);
+
+			if (block_group_cache_done(cache))
+				btrfs_add_free_space(cache, start,
+						     end - start + 1);
+			cache = NULL;
+		} else {
+			start = max(start, cache->key.objectid);
+			end = min(end, cache->key.objectid + cache->key.offset - 1);
+			btrfs_add_free_space(cache, start, end - start + 1);
+		}
+
+		clear_extent_bits(&fs_info->pinned_extents, start, end,
+				  EXTENT_DELALLOC, GFP_NOFS);
+		last = end + 1;
+
+		if (need_resched()) {
+			mutex_unlock(&discard_mutex);
+			cond_resched();
+			mutex_lock(&discard_mutex);
 		}
-		kfree(logical);
 	}
-	return 0;
+	mutex_unlock(&discard_mutex);
 }
 
-static int cache_block_group(struct btrfs_root *root,
-			     struct btrfs_block_group_cache *block_group)
+static int caching_kthread(void *data)
 {
+	struct btrfs_block_group_cache *block_group = data;
+	struct btrfs_fs_info *fs_info = block_group->fs_info;
+	u64 last = 0;
 	struct btrfs_path *path;
 	int ret = 0;
 	struct btrfs_key key;
 	struct extent_buffer *leaf;
 	int slot;
-	u64 last;
-
-	if (!block_group)
-		return 0;
+	u64 total_found = 0;
 
-	root = root->fs_info->extent_root;
-
-	if (block_group->cached)
-		return 0;
+	BUG_ON(!fs_info);
 
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
 
-	path->reada = 2;
+	atomic_inc(&fs_info->async_caching_threads);
+	atomic_inc(&block_group->space_info->caching_threads);
+	last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
+again:
+	/* need to make sure the commit_root doesn't disappear */
+	down_read(&fs_info->extent_root->commit_root_sem);
+
 	/*
-	 * we get into deadlocks with paths held by callers of this function.
-	 * since the alloc_mutex is protecting things right now, just
-	 * skip the locking here
+	 * We don't want to deadlock with somebody trying to allocate a new
+	 * extent for the extent root while also trying to search the extent
+	 * root to add free space.  So we skip locking and search the commit
+	 * root, since its read-only
 	 */
 	path->skip_locking = 1;
-	last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
+	path->search_commit_root = 1;
+	path->reada = 2;
+
 	key.objectid = last;
 	key.offset = 0;
 	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
 	if (ret < 0)
 		goto err;
 
 	while (1) {
+		smp_mb();
+		if (block_group->fs_info->closing)
+			break;
+
 		leaf = path->nodes[0];
 		slot = path->slots[0];
 		if (slot >= btrfs_header_nritems(leaf)) {
-			ret = btrfs_next_leaf(root, path);
+			ret = btrfs_next_leaf(fs_info->extent_root, path);
 			if (ret < 0)
 				goto err;
-			if (ret == 0)
-				continue;
-			else
+			else if (ret)
 				break;
+
+			if (need_resched()) {
+				btrfs_release_path(fs_info->extent_root, path);
+				up_read(&fs_info->extent_root->commit_root_sem);
+				cond_resched();
+				goto again;
+			}
+
+			continue;
 		}
 		btrfs_item_key_to_cpu(leaf, &key, slot);
 		if (key.objectid < block_group->key.objectid)
@@ -266,24 +373,63 @@ static int cache_block_group(struct btrfs_root *root,
 			break;
 
 		if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
-			add_new_free_space(block_group, root->fs_info, last,
-					   key.objectid);
-
+			total_found += add_new_free_space(block_group,
+							  fs_info, last,
+							  key.objectid);
 			last = key.objectid + key.offset;
 		}
+
+		if (total_found > (1024 * 1024 * 2)) {
+			total_found = 0;
+			wake_up(&block_group->caching_q);
+		}
 next:
 		path->slots[0]++;
 	}
+	ret = 0;
 
-	add_new_free_space(block_group, root->fs_info, last,
-			   block_group->key.objectid +
-			   block_group->key.offset);
+	total_found += add_new_free_space(block_group, fs_info, last,
+					  block_group->key.objectid +
+					  block_group->key.offset);
+
+	spin_lock(&block_group->lock);
+	block_group->cached = BTRFS_CACHE_FINISHED;
+	spin_unlock(&block_group->lock);
 
-	block_group->cached = 1;
-	remove_sb_from_cache(root, block_group);
-	ret = 0;
 err:
 	btrfs_free_path(path);
+	up_read(&fs_info->extent_root->commit_root_sem);
+	atomic_dec(&fs_info->async_caching_threads);
+	atomic_dec(&block_group->space_info->caching_threads);
+	wake_up(&block_group->caching_q);
+
+	if (!ret)
+		btrfs_discard_pinned_extents(fs_info, block_group);
+
+	return 0;
+}
+
+static int cache_block_group(struct btrfs_block_group_cache *cache)
+{
+	struct task_struct *tsk;
+	int ret = 0;
+
+	spin_lock(&cache->lock);
+	if (cache->cached != BTRFS_CACHE_NO) {
+		spin_unlock(&cache->lock);
+		return ret;
+	}
+	cache->cached = BTRFS_CACHE_STARTED;
+	spin_unlock(&cache->lock);
+
+	tsk = kthread_run(caching_kthread, cache, "btrfs-cache-%llu\n",
+			  cache->key.objectid);
+	if (IS_ERR(tsk)) {
+		ret = PTR_ERR(tsk);
+		printk(KERN_ERR "error running thread %d\n", ret);
+		BUG();
+	}
+
 	return ret;
 }
 
@@ -1721,7 +1867,7 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
 				BUG_ON(ret);
 			}
 			btrfs_update_pinned_extents(root, node->bytenr,
-						    node->num_bytes, 1);
+						    node->num_bytes, 1, 0);
 			update_reserved_extents(root, node->bytenr,
 						node->num_bytes, 0);
 		}
@@ -2496,6 +2642,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
 	found->force_alloc = 0;
 	*space_info = found;
 	list_add_rcu(&found->list, &info->space_info);
+	atomic_set(&found->caching_threads, 0);
 	return 0;
 }
 
@@ -2953,7 +3100,7 @@ static u64 first_logical_byte(struct btrfs_root *root, u64 search_start)
 }
 
 int btrfs_update_pinned_extents(struct btrfs_root *root,
-				u64 bytenr, u64 num, int pin)
+				u64 bytenr, u64 num, int pin, int mark_free)
 {
 	u64 len;
 	struct btrfs_block_group_cache *cache;
@@ -2988,7 +3135,7 @@ int btrfs_update_pinned_extents(struct btrfs_root *root,
 			spin_unlock(&cache->lock);
 			spin_unlock(&cache->space_info->lock);
 			fs_info->total_pinned -= len;
-			if (cache->cached)
+			if (block_group_cache_done(cache) && mark_free)
 				btrfs_add_free_space(cache, bytenr, len);
 		}
 		btrfs_put_block_group(cache);
@@ -3034,14 +3181,27 @@ int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy)
 	u64 last = 0;
 	u64 start;
 	u64 end;
+	bool caching_kthreads = false;
 	struct extent_io_tree *pinned_extents = &root->fs_info->pinned_extents;
 	int ret;
 
+	if (atomic_read(&root->fs_info->async_caching_threads))
+		caching_kthreads = true;
+
 	while (1) {
 		ret = find_first_extent_bit(pinned_extents, last,
 					    &start, &end, EXTENT_DIRTY);
 		if (ret)
 			break;
+
+		/*
+		 * we need to make sure that the pinned extents don't go away
+		 * while we are caching block groups
+		 */
+		if (unlikely(caching_kthreads))
+			set_extent_delalloc(pinned_extents, start, end,
+					    GFP_NOFS);
+
 		set_extent_dirty(copy, start, end, GFP_NOFS);
 		last = end + 1;
 	}
@@ -3055,6 +3215,12 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 	u64 start;
 	u64 end;
 	int ret;
+	int mark_free = 1;
+
+	ret = find_first_extent_bit(&root->fs_info->pinned_extents, 0,
+				    &start, &end, EXTENT_DELALLOC);
+	if (!ret)
+		mark_free = 0;
 
 	while (1) {
 		ret = find_first_extent_bit(unpin, 0, &start, &end,
@@ -3065,11 +3231,16 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 		ret = btrfs_discard_extent(root, start, end + 1 - start);
 
 		/* unlocks the pinned mutex */
-		btrfs_update_pinned_extents(root, start, end + 1 - start, 0);
+		btrfs_update_pinned_extents(root, start, end + 1 - start, 0,
+					    mark_free);
 		clear_extent_dirty(unpin, start, end, GFP_NOFS);
 
 		cond_resched();
 	}
+
+	if (unlikely(!mark_free))
+		btrfs_discard_pinned_extents(root->fs_info, NULL);
+
 	return ret;
 }
 
@@ -3110,7 +3281,7 @@ static int pin_down_bytes(struct btrfs_trans_handle *trans,
 pinit:
 	btrfs_set_path_blocking(path);
 	/* unlocks the pinned mutex */
-	btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
+	btrfs_update_pinned_extents(root, bytenr, num_bytes, 1, 0);
 
 	BUG_ON(err < 0);
 	return 0;
@@ -3421,7 +3592,7 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans,
 	if (root_objectid == BTRFS_TREE_LOG_OBJECTID) {
 		WARN_ON(owner >= BTRFS_FIRST_FREE_OBJECTID);
 		/* unlocks the pinned mutex */
-		btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
+		btrfs_update_pinned_extents(root, bytenr, num_bytes, 1, 0);
 		update_reserved_extents(root, bytenr, num_bytes, 0);
 		ret = 0;
 	} else if (owner < BTRFS_FIRST_FREE_OBJECTID) {
@@ -3448,6 +3619,45 @@ static u64 stripe_align(struct btrfs_root *root, u64 val)
 }
 
 /*
+ * when we wait for progress in the block group caching, its because
+ * our allocation attempt failed at least once.  So, we must sleep
+ * and let some progress happen before we try again.
+ *
+ * This function will sleep at least once waiting for new free space to
+ * show up, and then it will check the block group free space numbers
+ * for our min num_bytes.  Another option is to have it go ahead
+ * and look in the rbtree for a free extent of a given size, but this
+ * is a good start.
+ */
+static noinline int
+wait_block_group_cache_progress(struct btrfs_block_group_cache *cache,
+				u64 num_bytes)
+{
+	DEFINE_WAIT(wait);
+
+	prepare_to_wait(&cache->caching_q, &wait, TASK_UNINTERRUPTIBLE);
+
+	if (block_group_cache_done(cache)) {
+		finish_wait(&cache->caching_q, &wait);
+		return 0;
+	}
+	schedule();
+	finish_wait(&cache->caching_q, &wait);
+
+	wait_event(cache->caching_q, block_group_cache_done(cache) ||
+		   (cache->free_space >= num_bytes));
+	return 0;
+}
+
+enum btrfs_loop_type {
+	LOOP_CACHED_ONLY = 0,
+	LOOP_CACHING_NOWAIT = 1,
+	LOOP_CACHING_WAIT = 2,
+	LOOP_ALLOC_CHUNK = 3,
+	LOOP_NO_EMPTY_SIZE = 4,
+};
+
+/*
  * walks the btree of allocated extents and find a hole of a given size.
  * The key ins is changed to record the hole:
  * ins->objectid == block start
@@ -3472,6 +3682,7 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
 	struct btrfs_space_info *space_info;
 	int last_ptr_loop = 0;
 	int loop = 0;
+	bool found_uncached_bg = false;
 
 	WARN_ON(num_bytes < root->sectorsize);
 	btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
@@ -3503,15 +3714,18 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
 	search_start = max(search_start, first_logical_byte(root, 0));
 	search_start = max(search_start, hint_byte);
 
-	if (!last_ptr) {
+	if (!last_ptr)
 		empty_cluster = 0;
-		loop = 1;
-	}
 
 	if (search_start == hint_byte) {
 		block_group = btrfs_lookup_block_group(root->fs_info,
 						       search_start);
-		if (block_group && block_group_bits(block_group, data)) {
+		/*
+		 * we don't want to use the block group if it doesn't match our
+		 * allocation bits, or if its not cached.
+		 */
+		if (block_group && block_group_bits(block_group, data) &&
+		    block_group_cache_done(block_group)) {
 			down_read(&space_info->groups_sem);
 			if (list_empty(&block_group->list) ||
 			    block_group->ro) {
@@ -3534,21 +3748,35 @@ search:
 	down_read(&space_info->groups_sem);
 	list_for_each_entry(block_group, &space_info->block_groups, list) {
 		u64 offset;
+		int cached;
 
 		atomic_inc(&block_group->count);
 		search_start = block_group->key.objectid;
 
 have_block_group:
-		if (unlikely(!block_group->cached)) {
-			mutex_lock(&block_group->cache_mutex);
-			ret = cache_block_group(root, block_group);
-			mutex_unlock(&block_group->cache_mutex);
-			if (ret) {
-				btrfs_put_block_group(block_group);
-				break;
+		if (unlikely(block_group->cached == BTRFS_CACHE_NO)) {
+			/*
+			 * we want to start caching kthreads, but not too many
+			 * right off the bat so we don't overwhelm the system,
+			 * so only start them if there are less than 2 and we're
+			 * in the initial allocation phase.
+			 */
+			if (loop > LOOP_CACHING_NOWAIT ||
+			    atomic_read(&space_info->caching_threads) < 2) {
+				ret = cache_block_group(block_group);
+				BUG_ON(ret);
 			}
 		}
 
+		cached = block_group_cache_done(block_group);
+		if (unlikely(!cached)) {
+			found_uncached_bg = true;
+
+			/* if we only want cached bgs, loop */
+			if (loop == LOOP_CACHED_ONLY)
+				goto loop;
+		}
+
 		if (unlikely(block_group->ro))
 			goto loop;
 
@@ -3627,14 +3855,21 @@ refill_cluster:
 					spin_unlock(&last_ptr->refill_lock);
 					goto checks;
 				}
+			} else if (!cached && loop > LOOP_CACHING_NOWAIT) {
+				spin_unlock(&last_ptr->refill_lock);
+
+				wait_block_group_cache_progress(block_group,
+				       num_bytes + empty_cluster + empty_size);
+				goto have_block_group;
 			}
+
 			/*
 			 * at this point we either didn't find a cluster
 			 * or we weren't able to allocate a block from our
 			 * cluster.  Free the cluster we've been trying
 			 * to use, and go to the next block group
 			 */
-			if (loop < 2) {
+			if (loop < LOOP_NO_EMPTY_SIZE) {
 				btrfs_return_cluster_to_free_space(NULL,
 								   last_ptr);
 				spin_unlock(&last_ptr->refill_lock);
@@ -3645,8 +3880,15 @@ refill_cluster:
 
 		offset = btrfs_find_space_for_alloc(block_group, search_start,
 						    num_bytes, empty_size);
-		if (!offset)
+		if (!offset && (cached || (!cached &&
+					   loop == LOOP_CACHING_NOWAIT))) {
 			goto loop;
+		} else if (!offset && (!cached &&
+				       loop > LOOP_CACHING_NOWAIT)) {
+			wait_block_group_cache_progress(block_group,
+					num_bytes + empty_size);
+			goto have_block_group;
+		}
 checks:
 		search_start = stripe_align(root, offset);
 		/* move on to the next group */
@@ -3694,13 +3936,26 @@ loop:
 	}
 	up_read(&space_info->groups_sem);
 
-	/* loop == 0, try to find a clustered alloc in every block group
-	 * loop == 1, try again after forcing a chunk allocation
-	 * loop == 2, set empty_size and empty_cluster to 0 and try again
+	/* LOOP_CACHED_ONLY, only search fully cached block groups
+	 * LOOP_CACHING_NOWAIT, search partially cached block groups, but
+	 *			dont wait foR them to finish caching
+	 * LOOP_CACHING_WAIT, search everything, and wait if our bg is caching
+	 * LOOP_ALLOC_CHUNK, force a chunk allocation and try again
+	 * LOOP_NO_EMPTY_SIZE, set empty_size and empty_cluster to 0 and try
+	 *			again
 	 */
-	if (!ins->objectid && loop < 3 &&
-	    (empty_size || empty_cluster || allowed_chunk_alloc)) {
-		if (loop >= 2) {
+	if (!ins->objectid && loop < LOOP_NO_EMPTY_SIZE &&
+	    (found_uncached_bg || empty_size || empty_cluster ||
+	     allowed_chunk_alloc)) {
+		if (found_uncached_bg) {
+			found_uncached_bg = false;
+			if (loop < LOOP_CACHING_WAIT) {
+				loop++;
+				goto search;
+			}
+		}
+
+		if (loop == LOOP_ALLOC_CHUNK) {
 			empty_size = 0;
 			empty_cluster = 0;
 		}
@@ -3713,7 +3968,7 @@ loop:
 			space_info->force_alloc = 1;
 		}
 
-		if (loop < 3) {
+		if (loop < LOOP_NO_EMPTY_SIZE) {
 			loop++;
 			goto search;
 		}
@@ -3809,7 +4064,7 @@ again:
 			       num_bytes, data, 1);
 		goto again;
 	}
-	if (ret) {
+	if (ret == -ENOSPC) {
 		struct btrfs_space_info *sinfo;
 
 		sinfo = __find_space_info(root->fs_info, data);
@@ -3817,7 +4072,6 @@ again:
 		       "wanted %llu\n", (unsigned long long)data,
 		       (unsigned long long)num_bytes);
 		dump_space_info(sinfo, num_bytes);
-		BUG();
 	}
 
 	return ret;
@@ -3855,7 +4109,9 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
 	ret = __btrfs_reserve_extent(trans, root, num_bytes, min_alloc_size,
 				     empty_size, hint_byte, search_end, ins,
 				     data);
-	update_reserved_extents(root, ins->objectid, ins->offset, 1);
+	if (!ret)
+		update_reserved_extents(root, ins->objectid, ins->offset, 1);
+
 	return ret;
 }
 
@@ -4017,9 +4273,9 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
 	struct btrfs_block_group_cache *block_group;
 
 	block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);
-	mutex_lock(&block_group->cache_mutex);
-	cache_block_group(root, block_group);
-	mutex_unlock(&block_group->cache_mutex);
+	cache_block_group(block_group);
+	wait_event(block_group->caching_q,
+		   block_group_cache_done(block_group));
 
 	ret = btrfs_remove_free_space(block_group, ins->objectid,
 				      ins->offset);
@@ -4050,7 +4306,8 @@ static int alloc_tree_block(struct btrfs_trans_handle *trans,
 	ret = __btrfs_reserve_extent(trans, root, num_bytes, num_bytes,
 				     empty_size, hint_byte, search_end,
 				     ins, 0);
-	BUG_ON(ret);
+	if (ret)
+		return ret;
 
 	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
 		if (parent == 0)
@@ -6966,11 +7223,16 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
 			 &info->block_group_cache_tree);
 		spin_unlock(&info->block_group_cache_lock);
 
-		btrfs_remove_free_space_cache(block_group);
 		down_write(&block_group->space_info->groups_sem);
 		list_del(&block_group->list);
 		up_write(&block_group->space_info->groups_sem);
 
+		if (block_group->cached == BTRFS_CACHE_STARTED)
+			wait_event(block_group->caching_q,
+				   block_group_cache_done(block_group));
+
+		btrfs_remove_free_space_cache(block_group);
+
 		WARN_ON(atomic_read(&block_group->count) != 1);
 		kfree(block_group);
 
@@ -7036,10 +7298,10 @@ int btrfs_read_block_groups(struct btrfs_root *root)
 		atomic_set(&cache->count, 1);
 		spin_lock_init(&cache->lock);
 		spin_lock_init(&cache->tree_lock);
-		mutex_init(&cache->cache_mutex);
+		cache->fs_info = info;
+		init_waitqueue_head(&cache->caching_q);
 		INIT_LIST_HEAD(&cache->list);
 		INIT_LIST_HEAD(&cache->cluster_list);
-		cache->sectorsize = root->sectorsize;
 
 		/*
 		 * we only want to have 32k of ram per block group for keeping
@@ -7057,6 +7319,26 @@ int btrfs_read_block_groups(struct btrfs_root *root)
 		key.objectid = found_key.objectid + found_key.offset;
 		btrfs_release_path(root, path);
 		cache->flags = btrfs_block_group_flags(&cache->item);
+		cache->sectorsize = root->sectorsize;
+
+		remove_sb_from_cache(root, cache);
+
+		/*
+		 * check for two cases, either we are full, and therefore
+		 * don't need to bother with the caching work since we won't
+		 * find any space, or we are empty, and we can just add all
+		 * the space in and be done with it.  This saves us _alot_ of
+		 * time, particularly in the full case.
+		 */
+		if (found_key.offset == btrfs_block_group_used(&cache->item)) {
+			cache->cached = BTRFS_CACHE_FINISHED;
+		} else if (btrfs_block_group_used(&cache->item) == 0) {
+			cache->cached = BTRFS_CACHE_FINISHED;
+			add_new_free_space(cache, root->fs_info,
+					   found_key.objectid,
+					   found_key.objectid +
+					   found_key.offset);
+		}
 
 		ret = update_space_info(info, cache->flags, found_key.offset,
 					btrfs_block_group_used(&cache->item),
@@ -7112,7 +7394,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 	atomic_set(&cache->count, 1);
 	spin_lock_init(&cache->lock);
 	spin_lock_init(&cache->tree_lock);
-	mutex_init(&cache->cache_mutex);
+	init_waitqueue_head(&cache->caching_q);
 	INIT_LIST_HEAD(&cache->list);
 	INIT_LIST_HEAD(&cache->cluster_list);
 
@@ -7121,11 +7403,12 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 	cache->flags = type;
 	btrfs_set_block_group_flags(&cache->item, type);
 
-	cache->cached = 1;
-	ret = btrfs_add_free_space(cache, chunk_offset, size);
-	BUG_ON(ret);
+	cache->cached = BTRFS_CACHE_FINISHED;
 	remove_sb_from_cache(root, cache);
 
+	add_new_free_space(cache, root->fs_info, chunk_offset,
+			   chunk_offset + size);
+
 	ret = update_space_info(root->fs_info, cache->flags, size, bytes_used,
 				&cache->space_info);
 	BUG_ON(ret);
@@ -7184,7 +7467,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 	rb_erase(&block_group->cache_node,
 		 &root->fs_info->block_group_cache_tree);
 	spin_unlock(&root->fs_info->block_group_cache_lock);
-	btrfs_remove_free_space_cache(block_group);
+
 	down_write(&block_group->space_info->groups_sem);
 	/*
 	 * we must use list_del_init so people can check to see if they
@@ -7193,6 +7476,12 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 	list_del_init(&block_group->list);
 	up_write(&block_group->space_info->groups_sem);
 
+	if (block_group->cached == BTRFS_CACHE_STARTED)
+		wait_event(block_group->caching_q,
+			   block_group_cache_done(block_group));
+
+	btrfs_remove_free_space_cache(block_group);
+
 	spin_lock(&block_group->space_info->lock);
 	block_group->space_info->total_bytes -= block_group->key.offset;
 	block_group->space_info->bytes_readonly -= block_group->key.offset;
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index ab8cad8b46c..af99b78b288 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -238,6 +238,7 @@ static void unlink_free_space(struct btrfs_block_group_cache *block_group,
 {
 	rb_erase(&info->offset_index, &block_group->free_space_offset);
 	block_group->free_extents--;
+	block_group->free_space -= info->bytes;
 }
 
 static int link_free_space(struct btrfs_block_group_cache *block_group,
@@ -251,6 +252,7 @@ static int link_free_space(struct btrfs_block_group_cache *block_group,
 	if (ret)
 		return ret;
 
+	block_group->free_space += info->bytes;
 	block_group->free_extents++;
 	return ret;
 }
@@ -285,36 +287,40 @@ static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
 	}
 }
 
-static void bitmap_clear_bits(struct btrfs_free_space *info, u64 offset, u64 bytes,
-			      u64 sectorsize)
+static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
+			      struct btrfs_free_space *info, u64 offset,
+			      u64 bytes)
 {
 	unsigned long start, end;
 	unsigned long i;
 
-	start = offset_to_bit(info->offset, sectorsize, offset);
-	end = start + bytes_to_bits(bytes, sectorsize);
+	start = offset_to_bit(info->offset, block_group->sectorsize, offset);
+	end = start + bytes_to_bits(bytes, block_group->sectorsize);
 	BUG_ON(end > BITS_PER_BITMAP);
 
 	for (i = start; i < end; i++)
 		clear_bit(i, info->bitmap);
 
 	info->bytes -= bytes;
+	block_group->free_space -= bytes;
 }
 
-static void bitmap_set_bits(struct btrfs_free_space *info, u64 offset, u64 bytes,
-			    u64 sectorsize)
+static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
+			    struct btrfs_free_space *info, u64 offset,
+			    u64 bytes)
 {
 	unsigned long start, end;
 	unsigned long i;
 
-	start = offset_to_bit(info->offset, sectorsize, offset);
-	end = start + bytes_to_bits(bytes, sectorsize);
+	start = offset_to_bit(info->offset, block_group->sectorsize, offset);
+	end = start + bytes_to_bits(bytes, block_group->sectorsize);
 	BUG_ON(end > BITS_PER_BITMAP);
 
 	for (i = start; i < end; i++)
 		set_bit(i, info->bitmap);
 
 	info->bytes += bytes;
+	block_group->free_space += bytes;
 }
 
 static int search_bitmap(struct btrfs_block_group_cache *block_group,
@@ -414,13 +420,12 @@ again:
 		(u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
 
 	if (*offset > bitmap_info->offset && *offset + *bytes > end) {
-		bitmap_clear_bits(bitmap_info, *offset,
-				  end - *offset + 1, block_group->sectorsize);
+		bitmap_clear_bits(block_group, bitmap_info, *offset,
+				  end - *offset + 1);
 		*bytes -= end - *offset + 1;
 		*offset = end + 1;
 	} else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
-		bitmap_clear_bits(bitmap_info, *offset,
-				  *bytes, block_group->sectorsize);
+		bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
 		*bytes = 0;
 	}
 
@@ -495,14 +500,13 @@ again:
 		(u64)(BITS_PER_BITMAP * block_group->sectorsize);
 
 	if (offset >= bitmap_info->offset && offset + bytes > end) {
-		bitmap_set_bits(bitmap_info, offset, end - offset,
-				block_group->sectorsize);
+		bitmap_set_bits(block_group, bitmap_info, offset,
+				end - offset);
 		bytes -= end - offset;
 		offset = end;
 		added = 0;
 	} else if (offset >= bitmap_info->offset && offset + bytes <= end) {
-		bitmap_set_bits(bitmap_info, offset, bytes,
-				block_group->sectorsize);
+		bitmap_set_bits(block_group, bitmap_info, offset, bytes);
 		bytes = 0;
 	} else {
 		BUG();
@@ -870,8 +874,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
 
 	ret = offset;
 	if (entry->bitmap) {
-		bitmap_clear_bits(entry, offset, bytes,
-				  block_group->sectorsize);
+		bitmap_clear_bits(block_group, entry, offset, bytes);
 		if (!entry->bytes) {
 			unlink_free_space(block_group, entry);
 			kfree(entry->bitmap);
@@ -891,6 +894,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
 
 out:
 	spin_unlock(&block_group->tree_lock);
+
 	return ret;
 }
 
@@ -967,7 +971,7 @@ static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
 		goto out;
 
 	ret = search_start;
-	bitmap_clear_bits(entry, ret, bytes, block_group->sectorsize);
+	bitmap_clear_bits(block_group, entry, ret, bytes);
 out:
 	spin_unlock(&cluster->lock);
 	spin_unlock(&block_group->tree_lock);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 81f7124c305..32454d1c566 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -40,6 +40,14 @@ static noinline void put_transaction(struct btrfs_transaction *transaction)
 	}
 }
 
+static noinline void switch_commit_root(struct btrfs_root *root)
+{
+	down_write(&root->commit_root_sem);
+	free_extent_buffer(root->commit_root);
+	root->commit_root = btrfs_root_node(root);
+	up_write(&root->commit_root_sem);
+}
+
 /*
  * either allocate a new transaction or hop into the existing one
  */
@@ -458,8 +466,7 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
 		ret = btrfs_write_dirty_block_groups(trans, root);
 		BUG_ON(ret);
 	}
-	free_extent_buffer(root->commit_root);
-	root->commit_root = btrfs_root_node(root);
+	switch_commit_root(root);
 	return 0;
 }
 
@@ -537,8 +544,7 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 			btrfs_update_reloc_root(trans, root);
 
 			if (root->commit_root != root->node) {
-				free_extent_buffer(root->commit_root);
-				root->commit_root = btrfs_root_node(root);
+				switch_commit_root(root);
 				btrfs_set_root_node(&root->root_item,
 						    root->node);
 			}
@@ -1002,15 +1008,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
 	btrfs_set_root_node(&root->fs_info->tree_root->root_item,
 			    root->fs_info->tree_root->node);
-	free_extent_buffer(root->fs_info->tree_root->commit_root);
-	root->fs_info->tree_root->commit_root =
-				btrfs_root_node(root->fs_info->tree_root);
+	switch_commit_root(root->fs_info->tree_root);
 
 	btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
 			    root->fs_info->chunk_root->node);
-	free_extent_buffer(root->fs_info->chunk_root->commit_root);
-	root->fs_info->chunk_root->commit_root =
-				btrfs_root_node(root->fs_info->chunk_root);
+	switch_commit_root(root->fs_info->chunk_root);
 
 	update_super_roots(root);
 
@@ -1050,6 +1052,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	cur_trans->commit_done = 1;
 
 	root->fs_info->last_trans_committed = cur_trans->transid;
+
 	wake_up(&cur_trans->commit_wait);
 
 	put_transaction(cur_trans);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c13922206d1..19560686261 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -264,7 +264,7 @@ static int process_one_buffer(struct btrfs_root *log,
 {
 	if (wc->pin)
 		btrfs_update_pinned_extents(log->fs_info->extent_root,
-					    eb->start, eb->len, 1);
+					    eb->start, eb->len, 1, 0);
 
 	if (btrfs_buffer_uptodate(eb, gen)) {
 		if (wc->write)