diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index d243128..0ad48e7 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -54,8 +54,13 @@
 {
 	int i;
 	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
-		if (p->nodes[i] && p->locks[i])
-			btrfs_set_lock_blocking(p->nodes[i]);
+		if (!p->nodes[i] || !p->locks[i])
+			continue;
+		btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
+		if (p->locks[i] == BTRFS_READ_LOCK)
+			p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
+		else if (p->locks[i] == BTRFS_WRITE_LOCK)
+			p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
 	}
 }
 
@@ -68,7 +73,7 @@
  * for held
  */
 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
-					struct extent_buffer *held)
+					struct extent_buffer *held, int held_rw)
 {
 	int i;
 
@@ -79,19 +84,29 @@
 	 * really sure by forcing the path to blocking before we clear
 	 * the path blocking.
 	 */
-	if (held)
-		btrfs_set_lock_blocking(held);
+	if (held) {
+		btrfs_set_lock_blocking_rw(held, held_rw);
+		if (held_rw == BTRFS_WRITE_LOCK)
+			held_rw = BTRFS_WRITE_LOCK_BLOCKING;
+		else if (held_rw == BTRFS_READ_LOCK)
+			held_rw = BTRFS_READ_LOCK_BLOCKING;
+	}
 	btrfs_set_path_blocking(p);
 #endif
 
 	for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
-		if (p->nodes[i] && p->locks[i])
-			btrfs_clear_lock_blocking(p->nodes[i]);
+		if (p->nodes[i] && p->locks[i]) {
+			btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
+			if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
+				p->locks[i] = BTRFS_WRITE_LOCK;
+			else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
+				p->locks[i] = BTRFS_READ_LOCK;
+		}
 	}
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	if (held)
-		btrfs_clear_lock_blocking(held);
+		btrfs_clear_lock_blocking_rw(held, held_rw);
 #endif
 }
 
@@ -119,7 +134,7 @@
 		if (!p->nodes[i])
 			continue;
 		if (p->locks[i]) {
-			btrfs_tree_unlock(p->nodes[i]);
+			btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 			p->locks[i] = 0;
 		}
 		free_extent_buffer(p->nodes[i]);
@@ -167,6 +182,25 @@
 	return eb;
 }
 
+/* loop around taking references on and locking the root node of the
+ * tree until you end up with a lock on the root.  A locked buffer
+ * is returned, with a reference held.
+ */
+struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
+{
+	struct extent_buffer *eb;
+
+	while (1) {
+		eb = btrfs_root_node(root);
+		btrfs_tree_read_lock(eb);
+		if (eb == root->node)
+			break;
+		btrfs_tree_read_unlock(eb);
+		free_extent_buffer(eb);
+	}
+	return eb;
+}
+
 /* cowonly root (everything not a reference counted cow subvolume), just get
  * put onto a simple dirty list.  transaction.c walks this to make sure they
  * get properly updated on disk.
@@ -862,7 +896,8 @@
 
 	mid = path->nodes[level];
 
-	WARN_ON(!path->locks[level]);
+	WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
+		path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
 	WARN_ON(btrfs_header_generation(mid) != trans->transid);
 
 	orig_ptr = btrfs_node_blockptr(mid, orig_slot);
@@ -1360,7 +1395,7 @@
 
 		t = path->nodes[i];
 		if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
-			btrfs_tree_unlock(t);
+			btrfs_tree_unlock_rw(t, path->locks[i]);
 			path->locks[i] = 0;
 		}
 	}
@@ -1387,7 +1422,7 @@
 			continue;
 		if (!path->locks[i])
 			continue;
-		btrfs_tree_unlock(path->nodes[i]);
+		btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
 		path->locks[i] = 0;
 	}
 }
@@ -1436,6 +1471,8 @@
 			 * we can trust our generation number
 			 */
 			free_extent_buffer(tmp);
+			btrfs_set_path_blocking(p);
+
 			tmp = read_tree_block(root, blocknr, blocksize, gen);
 			if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
 				*eb_ret = tmp;
@@ -1491,20 +1528,27 @@
 static int
 setup_nodes_for_search(struct btrfs_trans_handle *trans,
 		       struct btrfs_root *root, struct btrfs_path *p,
-		       struct extent_buffer *b, int level, int ins_len)
+		       struct extent_buffer *b, int level, int ins_len,
+		       int *write_lock_level)
 {
 	int ret;
 	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
 	    BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
 		int sret;
 
+		if (*write_lock_level < level + 1) {
+			*write_lock_level = level + 1;
+			btrfs_release_path(p);
+			goto again;
+		}
+
 		sret = reada_for_balance(root, p, level);
 		if (sret)
 			goto again;
 
 		btrfs_set_path_blocking(p);
 		sret = split_node(trans, root, p, level);
-		btrfs_clear_path_blocking(p, NULL);
+		btrfs_clear_path_blocking(p, NULL, 0);
 
 		BUG_ON(sret > 0);
 		if (sret) {
@@ -1516,13 +1560,19 @@
 		   BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
 		int sret;
 
+		if (*write_lock_level < level + 1) {
+			*write_lock_level = level + 1;
+			btrfs_release_path(p);
+			goto again;
+		}
+
 		sret = reada_for_balance(root, p, level);
 		if (sret)
 			goto again;
 
 		btrfs_set_path_blocking(p);
 		sret = balance_level(trans, root, p, level);
-		btrfs_clear_path_blocking(p, NULL);
+		btrfs_clear_path_blocking(p, NULL, 0);
 
 		if (sret) {
 			ret = sret;
@@ -1566,27 +1616,78 @@
 	int err;
 	int level;
 	int lowest_unlock = 1;
+	int root_lock;
+	/* everything at write_lock_level or lower must be write locked */
+	int write_lock_level = 0;
 	u8 lowest_level = 0;
 
 	lowest_level = p->lowest_level;
 	WARN_ON(lowest_level && ins_len > 0);
 	WARN_ON(p->nodes[0] != NULL);
 
-	if (ins_len < 0)
+	if (ins_len < 0) {
 		lowest_unlock = 2;
 
+		/* when we are removing items, we might have to go up to level
+		 * two as we update tree pointers  Make sure we keep write
+		 * for those levels as well
+		 */
+		write_lock_level = 2;
+	} else if (ins_len > 0) {
+		/*
+		 * for inserting items, make sure we have a write lock on
+		 * level 1 so we can update keys
+		 */
+		write_lock_level = 1;
+	}
+
+	if (!cow)
+		write_lock_level = -1;
+
+	if (cow && (p->keep_locks || p->lowest_level))
+		write_lock_level = BTRFS_MAX_LEVEL;
+
 again:
+	/*
+	 * we try very hard to do read locks on the root
+	 */
+	root_lock = BTRFS_READ_LOCK;
+	level = 0;
 	if (p->search_commit_root) {
+		/*
+		 * the commit roots are read only
+		 * so we always do read locks
+		 */
 		b = root->commit_root;
 		extent_buffer_get(b);
+		level = btrfs_header_level(b);
 		if (!p->skip_locking)
-			btrfs_tree_lock(b);
+			btrfs_tree_read_lock(b);
 	} else {
-		if (p->skip_locking)
+		if (p->skip_locking) {
 			b = btrfs_root_node(root);
-		else
-			b = btrfs_lock_root_node(root);
+			level = btrfs_header_level(b);
+		} else {
+			/* we don't know the level of the root node
+			 * until we actually have it read locked
+			 */
+			b = btrfs_read_lock_root_node(root);
+			level = btrfs_header_level(b);
+			if (level <= write_lock_level) {
+				/* whoops, must trade for write lock */
+				btrfs_tree_read_unlock(b);
+				free_extent_buffer(b);
+				b = btrfs_lock_root_node(root);
+				root_lock = BTRFS_WRITE_LOCK;
+
+				/* the level might have changed, check again */
+				level = btrfs_header_level(b);
+			}
+		}
 	}
+	p->nodes[level] = b;
+	if (!p->skip_locking)
+		p->locks[level] = root_lock;
 
 	while (b) {
 		level = btrfs_header_level(b);
@@ -1595,10 +1696,6 @@
 		 * setup the path here so we can release it under lock
 		 * contention with the cow code
 		 */
-		p->nodes[level] = b;
-		if (!p->skip_locking)
-			p->locks[level] = 1;
-
 		if (cow) {
 			/*
 			 * if we don't really need to cow this block
@@ -1610,6 +1707,16 @@
 
 			btrfs_set_path_blocking(p);
 
+			/*
+			 * must have write locks on this node and the
+			 * parent
+			 */
+			if (level + 1 > write_lock_level) {
+				write_lock_level = level + 1;
+				btrfs_release_path(p);
+				goto again;
+			}
+
 			err = btrfs_cow_block(trans, root, b,
 					      p->nodes[level + 1],
 					      p->slots[level + 1], &b);
@@ -1622,10 +1729,7 @@
 		BUG_ON(!cow && ins_len);
 
 		p->nodes[level] = b;
-		if (!p->skip_locking)
-			p->locks[level] = 1;
-
-		btrfs_clear_path_blocking(p, NULL);
+		btrfs_clear_path_blocking(p, NULL, 0);
 
 		/*
 		 * we have a lock on b and as long as we aren't changing
@@ -1651,7 +1755,7 @@
 			}
 			p->slots[level] = slot;
 			err = setup_nodes_for_search(trans, root, p, b, level,
-						     ins_len);
+					     ins_len, &write_lock_level);
 			if (err == -EAGAIN)
 				goto again;
 			if (err) {
@@ -1661,6 +1765,19 @@
 			b = p->nodes[level];
 			slot = p->slots[level];
 
+			/*
+			 * slot 0 is special, if we change the key
+			 * we have to update the parent pointer
+			 * which means we must have a write lock
+			 * on the parent
+			 */
+			if (slot == 0 && cow &&
+			    write_lock_level < level + 1) {
+				write_lock_level = level + 1;
+				btrfs_release_path(p);
+				goto again;
+			}
+
 			unlock_up(p, level, lowest_unlock);
 
 			if (level == lowest_level) {
@@ -1679,23 +1796,42 @@
 			}
 
 			if (!p->skip_locking) {
-				btrfs_clear_path_blocking(p, NULL);
-				err = btrfs_try_spin_lock(b);
-
-				if (!err) {
-					btrfs_set_path_blocking(p);
-					btrfs_tree_lock(b);
-					btrfs_clear_path_blocking(p, b);
+				level = btrfs_header_level(b);
+				if (level <= write_lock_level) {
+					err = btrfs_try_tree_write_lock(b);
+					if (!err) {
+						btrfs_set_path_blocking(p);
+						btrfs_tree_lock(b);
+						btrfs_clear_path_blocking(p, b,
+								  BTRFS_WRITE_LOCK);
+					}
+					p->locks[level] = BTRFS_WRITE_LOCK;
+				} else {
+					err = btrfs_try_tree_read_lock(b);
+					if (!err) {
+						btrfs_set_path_blocking(p);
+						btrfs_tree_read_lock(b);
+						btrfs_clear_path_blocking(p, b,
+								  BTRFS_READ_LOCK);
+					}
+					p->locks[level] = BTRFS_READ_LOCK;
 				}
+				p->nodes[level] = b;
 			}
 		} else {
 			p->slots[level] = slot;
 			if (ins_len > 0 &&
 			    btrfs_leaf_free_space(root, b) < ins_len) {
+				if (write_lock_level < 1) {
+					write_lock_level = 1;
+					btrfs_release_path(p);
+					goto again;
+				}
+
 				btrfs_set_path_blocking(p);
 				err = split_leaf(trans, root, key,
 						 p, ins_len, ret == 0);
-				btrfs_clear_path_blocking(p, NULL);
+				btrfs_clear_path_blocking(p, NULL, 0);
 
 				BUG_ON(err > 0);
 				if (err) {
@@ -1976,7 +2112,7 @@
 	add_root_to_dirty_list(root);
 	extent_buffer_get(c);
 	path->nodes[level] = c;
-	path->locks[level] = 1;
+	path->locks[level] = BTRFS_WRITE_LOCK;
 	path->slots[level] = 0;
 	return 0;
 }
@@ -3819,11 +3955,11 @@
 
 	WARN_ON(!path->keep_locks);
 again:
-	cur = btrfs_lock_root_node(root);
+	cur = btrfs_read_lock_root_node(root);
 	level = btrfs_header_level(cur);
 	WARN_ON(path->nodes[level]);
 	path->nodes[level] = cur;
-	path->locks[level] = 1;
+	path->locks[level] = BTRFS_READ_LOCK;
 
 	if (btrfs_header_generation(cur) < min_trans) {
 		ret = 1;
@@ -3913,12 +4049,12 @@
 		cur = read_node_slot(root, cur, slot);
 		BUG_ON(!cur);
 
-		btrfs_tree_lock(cur);
+		btrfs_tree_read_lock(cur);
 
-		path->locks[level - 1] = 1;
+		path->locks[level - 1] = BTRFS_READ_LOCK;
 		path->nodes[level - 1] = cur;
 		unlock_up(path, level, 1);
-		btrfs_clear_path_blocking(path, NULL);
+		btrfs_clear_path_blocking(path, NULL, 0);
 	}
 out:
 	if (ret == 0)
@@ -4034,6 +4170,7 @@
 	int ret;
 	int old_spinning = path->leave_spinning;
 	int force_blocking = 0;
+	int next_rw_lock = 0;
 
 	nritems = btrfs_header_nritems(path->nodes[0]);
 	if (nritems == 0)
@@ -4051,6 +4188,7 @@
 again:
 	level = 1;
 	next = NULL;
+	next_rw_lock = 0;
 	btrfs_release_path(path);
 
 	path->keep_locks = 1;
@@ -4096,11 +4234,12 @@
 		}
 
 		if (next) {
-			btrfs_tree_unlock(next);
+			btrfs_tree_unlock_rw(next, next_rw_lock);
 			free_extent_buffer(next);
 		}
 
 		next = c;
+		next_rw_lock = path->locks[level];
 		ret = read_block_for_search(NULL, root, path, &next, level,
 					    slot, &key);
 		if (ret == -EAGAIN)
@@ -4112,15 +4251,22 @@
 		}
 
 		if (!path->skip_locking) {
-			ret = btrfs_try_spin_lock(next);
+			ret = btrfs_try_tree_read_lock(next);
 			if (!ret) {
 				btrfs_set_path_blocking(path);
-				btrfs_tree_lock(next);
-				if (!force_blocking)
-					btrfs_clear_path_blocking(path, next);
+				btrfs_tree_read_lock(next);
+				if (!force_blocking) {
+					btrfs_clear_path_blocking(path, next,
+							  BTRFS_READ_LOCK);
+				}
 			}
-			if (force_blocking)
-				btrfs_set_lock_blocking(next);
+			if (force_blocking) {
+				btrfs_set_lock_blocking_rw(next,
+							   BTRFS_READ_LOCK);
+				next_rw_lock = BTRFS_READ_LOCK_BLOCKING;
+			} else {
+				next_rw_lock = BTRFS_READ_LOCK;
+			}
 		}
 		break;
 	}
@@ -4129,14 +4275,13 @@
 		level--;
 		c = path->nodes[level];
 		if (path->locks[level])
-			btrfs_tree_unlock(c);
+			btrfs_tree_unlock_rw(c, path->locks[level]);
 
 		free_extent_buffer(c);
 		path->nodes[level] = next;
 		path->slots[level] = 0;
 		if (!path->skip_locking)
-			path->locks[level] = 1;
-
+			path->locks[level] = next_rw_lock;
 		if (!level)
 			break;
 
@@ -4151,16 +4296,21 @@
 		}
 
 		if (!path->skip_locking) {
-			btrfs_assert_tree_locked(path->nodes[level]);
-			ret = btrfs_try_spin_lock(next);
+			ret = btrfs_try_tree_read_lock(next);
 			if (!ret) {
 				btrfs_set_path_blocking(path);
-				btrfs_tree_lock(next);
+				btrfs_tree_read_lock(next);
 				if (!force_blocking)
-					btrfs_clear_path_blocking(path, next);
+					btrfs_clear_path_blocking(path, next,
+							  BTRFS_READ_LOCK);
 			}
-			if (force_blocking)
-				btrfs_set_lock_blocking(next);
+			if (force_blocking) {
+				btrfs_set_lock_blocking_rw(next,
+						   BTRFS_READ_LOCK);
+				next_rw_lock = BTRFS_READ_LOCK_BLOCKING;
+			} else {
+				next_rw_lock = BTRFS_READ_LOCK;
+			}
 		}
 	}
 	ret = 0;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3063f21..40235e1 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2333,7 +2333,7 @@
 void btrfs_free_path(struct btrfs_path *p);
 void btrfs_set_path_blocking(struct btrfs_path *p);
 void btrfs_clear_path_blocking(struct btrfs_path *p,
-			       struct extent_buffer *held);
+			       struct extent_buffer *held, int held_rw);
 void btrfs_unlock_up_safe(struct btrfs_path *p, int level);
 
 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 98c68e6..b52c672 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -735,7 +735,7 @@
 	}
 
 	/* reset all the locked nodes in the patch to spinning locks. */
-	btrfs_clear_path_blocking(path, NULL);
+	btrfs_clear_path_blocking(path, NULL, 0);
 
 	/* insert the keys of the items */
 	ret = setup_items_for_insert(trans, root, path, keys, data_size,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7021dde..2a782c2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5912,7 +5912,7 @@
 			return 1;
 
 		if (path->locks[level] && !wc->keep_locks) {
-			btrfs_tree_unlock(eb);
+			btrfs_tree_unlock_rw(eb, path->locks[level]);
 			path->locks[level] = 0;
 		}
 		return 0;
@@ -5936,7 +5936,7 @@
 	 * keep the tree lock
 	 */
 	if (path->locks[level] && level > 0) {
-		btrfs_tree_unlock(eb);
+		btrfs_tree_unlock_rw(eb, path->locks[level]);
 		path->locks[level] = 0;
 	}
 	return 0;
@@ -6049,7 +6049,7 @@
 	BUG_ON(level != btrfs_header_level(next));
 	path->nodes[level] = next;
 	path->slots[level] = 0;
-	path->locks[level] = 1;
+	path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 	wc->level = level;
 	if (wc->level == 1)
 		wc->reada_slot = 0;
@@ -6120,7 +6120,7 @@
 			BUG_ON(level == 0);
 			btrfs_tree_lock(eb);
 			btrfs_set_lock_blocking(eb);
-			path->locks[level] = 1;
+			path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 
 			ret = btrfs_lookup_extent_info(trans, root,
 						       eb->start, eb->len,
@@ -6129,8 +6129,7 @@
 			BUG_ON(ret);
 			BUG_ON(wc->refs[level] == 0);
 			if (wc->refs[level] == 1) {
-				btrfs_tree_unlock(eb);
-				path->locks[level] = 0;
+				btrfs_tree_unlock_rw(eb, path->locks[level]);
 				return 1;
 			}
 		}
@@ -6152,7 +6151,7 @@
 		    btrfs_header_generation(eb) == trans->transid) {
 			btrfs_tree_lock(eb);
 			btrfs_set_lock_blocking(eb);
-			path->locks[level] = 1;
+			path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 		}
 		clean_tree_block(trans, root, eb);
 	}
@@ -6231,7 +6230,8 @@
 				return 0;
 
 			if (path->locks[level]) {
-				btrfs_tree_unlock(path->nodes[level]);
+				btrfs_tree_unlock_rw(path->nodes[level],
+						     path->locks[level]);
 				path->locks[level] = 0;
 			}
 			free_extent_buffer(path->nodes[level]);
@@ -6283,7 +6283,7 @@
 		path->nodes[level] = btrfs_lock_root_node(root);
 		btrfs_set_lock_blocking(path->nodes[level]);
 		path->slots[level] = 0;
-		path->locks[level] = 1;
+		path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 		memset(&wc->update_progress, 0,
 		       sizeof(wc->update_progress));
 	} else {
@@ -6451,7 +6451,7 @@
 	level = btrfs_header_level(node);
 	path->nodes[level] = node;
 	path->slots[level] = 0;
-	path->locks[level] = 1;
+	path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 
 	wc->refs[parent_level] = 1;
 	wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 76ecbb8..5392c3b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3017,8 +3017,15 @@
 		return NULL;
 	eb->start = start;
 	eb->len = len;
-	spin_lock_init(&eb->lock);
-	init_waitqueue_head(&eb->lock_wq);
+	rwlock_init(&eb->lock);
+	atomic_set(&eb->write_locks, 0);
+	atomic_set(&eb->read_locks, 0);
+	atomic_set(&eb->blocking_readers, 0);
+	atomic_set(&eb->blocking_writers, 0);
+	atomic_set(&eb->spinning_readers, 0);
+	atomic_set(&eb->spinning_writers, 0);
+	init_waitqueue_head(&eb->write_lock_wq);
+	init_waitqueue_head(&eb->read_lock_wq);
 
 #if LEAK_DEBUG
 	spin_lock_irqsave(&leak_lock, flags);
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index b5f120c..21a7ca9 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -128,14 +128,26 @@
 	struct rcu_head rcu_head;
 	atomic_t refs;
 
-	/* the spinlock is used to protect most operations */
-	spinlock_t lock;
+	/* count of read lock holders on the extent buffer */
+	atomic_t write_locks;
+	atomic_t read_locks;
+	atomic_t blocking_writers;
+	atomic_t blocking_readers;
+	atomic_t spinning_readers;
+	atomic_t spinning_writers;
 
-	/*
-	 * when we keep the lock held while blocking, waiters go onto
-	 * the wq
+	/* protects write locks */
+	rwlock_t lock;
+
+	/* readers use lock_wq while they wait for the write
+	 * lock holders to unlock
 	 */
-	wait_queue_head_t lock_wq;
+	wait_queue_head_t write_lock_wq;
+
+	/* writers use read_lock_wq while they wait for readers
+	 * to unlock
+	 */
+	wait_queue_head_t read_lock_wq;
 };
 
 static inline void extent_set_compress_type(unsigned long *bio_flags,
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 66fa43d..d77b67c 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -24,185 +24,197 @@
 #include "extent_io.h"
 #include "locking.h"
 
-static inline void spin_nested(struct extent_buffer *eb)
+void btrfs_assert_tree_read_locked(struct extent_buffer *eb);
+
+/*
+ * if we currently have a spinning reader or writer lock
+ * (indicated by the rw flag) this will bump the count
+ * of blocking holders and drop the spinlock.
+ */
+void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw)
 {
-	spin_lock(&eb->lock);
+	if (rw == BTRFS_WRITE_LOCK) {
+		if (atomic_read(&eb->blocking_writers) == 0) {
+			WARN_ON(atomic_read(&eb->spinning_writers) != 1);
+			atomic_dec(&eb->spinning_writers);
+			btrfs_assert_tree_locked(eb);
+			atomic_inc(&eb->blocking_writers);
+			write_unlock(&eb->lock);
+		}
+	} else if (rw == BTRFS_READ_LOCK) {
+		btrfs_assert_tree_read_locked(eb);
+		atomic_inc(&eb->blocking_readers);
+		WARN_ON(atomic_read(&eb->spinning_readers) == 0);
+		atomic_dec(&eb->spinning_readers);
+		read_unlock(&eb->lock);
+	}
+	return;
 }
 
 /*
- * Setting a lock to blocking will drop the spinlock and set the
- * flag that forces other procs who want the lock to wait.  After
- * this you can safely schedule with the lock held.
+ * if we currently have a blocking lock, take the spinlock
+ * and drop our blocking count
  */
-void btrfs_set_lock_blocking(struct extent_buffer *eb)
+void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
 {
-	if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) {
-		set_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags);
-		spin_unlock(&eb->lock);
+	if (rw == BTRFS_WRITE_LOCK_BLOCKING) {
+		BUG_ON(atomic_read(&eb->blocking_writers) != 1);
+		write_lock(&eb->lock);
+		WARN_ON(atomic_read(&eb->spinning_writers));
+		atomic_inc(&eb->spinning_writers);
+		if (atomic_dec_and_test(&eb->blocking_writers))
+			wake_up(&eb->write_lock_wq);
+	} else if (rw == BTRFS_READ_LOCK_BLOCKING) {
+		BUG_ON(atomic_read(&eb->blocking_readers) == 0);
+		read_lock(&eb->lock);
+		atomic_inc(&eb->spinning_readers);
+		if (atomic_dec_and_test(&eb->blocking_readers))
+			wake_up(&eb->read_lock_wq);
 	}
-	/* exit with the spin lock released and the bit set */
+	return;
 }
 
 /*
- * clearing the blocking flag will take the spinlock again.
- * After this you can't safely schedule
+ * take a spinning read lock.  This will wait for any blocking
+ * writers
  */
-void btrfs_clear_lock_blocking(struct extent_buffer *eb)
+void btrfs_tree_read_lock(struct extent_buffer *eb)
 {
-	if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) {
-		spin_nested(eb);
-		clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags);
-		smp_mb__after_clear_bit();
+again:
+	wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
+	read_lock(&eb->lock);
+	if (atomic_read(&eb->blocking_writers)) {
+		read_unlock(&eb->lock);
+		wait_event(eb->write_lock_wq,
+			   atomic_read(&eb->blocking_writers) == 0);
+		goto again;
 	}
-	/* exit with the spin lock held */
+	atomic_inc(&eb->read_locks);
+	atomic_inc(&eb->spinning_readers);
 }
 
 /*
- * unfortunately, many of the places that currently set a lock to blocking
- * don't end up blocking for very long, and often they don't block
- * at all.  For a dbench 50 run, if we don't spin on the blocking bit
- * at all, the context switch rate can jump up to 400,000/sec or more.
- *
- * So, we're still stuck with this crummy spin on the blocking bit,
- * at least until the most common causes of the short blocks
- * can be dealt with.
+ * returns 1 if we get the read lock and 0 if we don't
+ * this won't wait for blocking writers
  */
-static int btrfs_spin_on_block(struct extent_buffer *eb)
+int btrfs_try_tree_read_lock(struct extent_buffer *eb)
 {
-	int i;
+	if (atomic_read(&eb->blocking_writers))
+		return 0;
 
-	for (i = 0; i < 512; i++) {
-		if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-			return 1;
-		if (need_resched())
-			break;
-		cpu_relax();
+	read_lock(&eb->lock);
+	if (atomic_read(&eb->blocking_writers)) {
+		read_unlock(&eb->lock);
+		return 0;
 	}
-	return 0;
-}
-
-/*
- * This is somewhat different from trylock.  It will take the
- * spinlock but if it finds the lock is set to blocking, it will
- * return without the lock held.
- *
- * returns 1 if it was able to take the lock and zero otherwise
- *
- * After this call, scheduling is not safe without first calling
- * btrfs_set_lock_blocking()
- */
-int btrfs_try_spin_lock(struct extent_buffer *eb)
-{
-	int i;
-
-	if (btrfs_spin_on_block(eb)) {
-		spin_nested(eb);
-		if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-			return 1;
-		spin_unlock(&eb->lock);
-	}
-	/* spin for a bit on the BLOCKING flag */
-	for (i = 0; i < 2; i++) {
-		cpu_relax();
-		if (!btrfs_spin_on_block(eb))
-			break;
-
-		spin_nested(eb);
-		if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-			return 1;
-		spin_unlock(&eb->lock);
-	}
-	return 0;
-}
-
-/*
- * the autoremove wake function will return 0 if it tried to wake up
- * a process that was already awake, which means that process won't
- * count as an exclusive wakeup.  The waitq code will continue waking
- * procs until it finds one that was actually sleeping.
- *
- * For btrfs, this isn't quite what we want.  We want a single proc
- * to be notified that the lock is ready for taking.  If that proc
- * already happen to be awake, great, it will loop around and try for
- * the lock.
- *
- * So, btrfs_wake_function always returns 1, even when the proc that we
- * tried to wake up was already awake.
- */
-static int btrfs_wake_function(wait_queue_t *wait, unsigned mode,
-			       int sync, void *key)
-{
-	autoremove_wake_function(wait, mode, sync, key);
+	atomic_inc(&eb->read_locks);
+	atomic_inc(&eb->spinning_readers);
 	return 1;
 }
 
 /*
- * returns with the extent buffer spinlocked.
- *
- * This will spin and/or wait as required to take the lock, and then
- * return with the spinlock held.
- *
- * After this call, scheduling is not safe without first calling
- * btrfs_set_lock_blocking()
+ * returns 1 if we get the read lock and 0 if we don't
+ * this won't wait for blocking writers or readers
+ */
+int btrfs_try_tree_write_lock(struct extent_buffer *eb)
+{
+	if (atomic_read(&eb->blocking_writers) ||
+	    atomic_read(&eb->blocking_readers))
+		return 0;
+	write_lock(&eb->lock);
+	if (atomic_read(&eb->blocking_writers) ||
+	    atomic_read(&eb->blocking_readers)) {
+		write_unlock(&eb->lock);
+		return 0;
+	}
+	atomic_inc(&eb->write_locks);
+	atomic_inc(&eb->spinning_writers);
+	return 1;
+}
+
+/*
+ * drop a spinning read lock
+ */
+void btrfs_tree_read_unlock(struct extent_buffer *eb)
+{
+	btrfs_assert_tree_read_locked(eb);
+	WARN_ON(atomic_read(&eb->spinning_readers) == 0);
+	atomic_dec(&eb->spinning_readers);
+	atomic_dec(&eb->read_locks);
+	read_unlock(&eb->lock);
+}
+
+/*
+ * drop a blocking read lock
+ */
+void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
+{
+	btrfs_assert_tree_read_locked(eb);
+	WARN_ON(atomic_read(&eb->blocking_readers) == 0);
+	if (atomic_dec_and_test(&eb->blocking_readers))
+		wake_up(&eb->read_lock_wq);
+	atomic_dec(&eb->read_locks);
+}
+
+/*
+ * take a spinning write lock.  This will wait for both
+ * blocking readers or writers
  */
 int btrfs_tree_lock(struct extent_buffer *eb)
 {
-	DEFINE_WAIT(wait);
-	wait.func = btrfs_wake_function;
-
-	if (!btrfs_spin_on_block(eb))
-		goto sleep;
-
-	while(1) {
-		spin_nested(eb);
-
-		/* nobody is blocking, exit with the spinlock held */
-		if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-			return 0;
-
-		/*
-		 * we have the spinlock, but the real owner is blocking.
-		 * wait for them
-		 */
-		spin_unlock(&eb->lock);
-
-		/*
-		 * spin for a bit, and if the blocking flag goes away,
-		 * loop around
-		 */
-		cpu_relax();
-		if (btrfs_spin_on_block(eb))
-			continue;
-sleep:
-		prepare_to_wait_exclusive(&eb->lock_wq, &wait,
-					  TASK_UNINTERRUPTIBLE);
-
-		if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-			schedule();
-
-		finish_wait(&eb->lock_wq, &wait);
+again:
+	wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
+	wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
+	write_lock(&eb->lock);
+	if (atomic_read(&eb->blocking_readers)) {
+		write_unlock(&eb->lock);
+		wait_event(eb->read_lock_wq,
+			   atomic_read(&eb->blocking_readers) == 0);
+		goto again;
 	}
+	if (atomic_read(&eb->blocking_writers)) {
+		write_unlock(&eb->lock);
+		wait_event(eb->write_lock_wq,
+			   atomic_read(&eb->blocking_writers) == 0);
+		goto again;
+	}
+	WARN_ON(atomic_read(&eb->spinning_writers));
+	atomic_inc(&eb->spinning_writers);
+	atomic_inc(&eb->write_locks);
 	return 0;
 }
 
+/*
+ * drop a spinning or a blocking write lock.
+ */
 int btrfs_tree_unlock(struct extent_buffer *eb)
 {
-	/*
-	 * if we were a blocking owner, we don't have the spinlock held
-	 * just clear the bit and look for waiters
-	 */
-	if (test_and_clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-		smp_mb__after_clear_bit();
-	else
-		spin_unlock(&eb->lock);
+	int blockers = atomic_read(&eb->blocking_writers);
 
-	if (waitqueue_active(&eb->lock_wq))
-		wake_up(&eb->lock_wq);
+	BUG_ON(blockers > 1);
+
+	btrfs_assert_tree_locked(eb);
+	atomic_dec(&eb->write_locks);
+
+	if (blockers) {
+		WARN_ON(atomic_read(&eb->spinning_writers));
+		atomic_dec(&eb->blocking_writers);
+		smp_wmb();
+		wake_up(&eb->write_lock_wq);
+	} else {
+		WARN_ON(atomic_read(&eb->spinning_writers) != 1);
+		atomic_dec(&eb->spinning_writers);
+		write_unlock(&eb->lock);
+	}
 	return 0;
 }
 
 void btrfs_assert_tree_locked(struct extent_buffer *eb)
 {
-	if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-		assert_spin_locked(&eb->lock);
+	BUG_ON(!atomic_read(&eb->write_locks));
+}
+
+void btrfs_assert_tree_read_locked(struct extent_buffer *eb)
+{
+	BUG_ON(!atomic_read(&eb->read_locks));
 }
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index 5c33a56..17247dd 100644
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -19,11 +19,43 @@
 #ifndef __BTRFS_LOCKING_
 #define __BTRFS_LOCKING_
 
+#define BTRFS_WRITE_LOCK 1
+#define BTRFS_READ_LOCK 2
+#define BTRFS_WRITE_LOCK_BLOCKING 3
+#define BTRFS_READ_LOCK_BLOCKING 4
+
 int btrfs_tree_lock(struct extent_buffer *eb);
 int btrfs_tree_unlock(struct extent_buffer *eb);
 int btrfs_try_spin_lock(struct extent_buffer *eb);
 
-void btrfs_set_lock_blocking(struct extent_buffer *eb);
-void btrfs_clear_lock_blocking(struct extent_buffer *eb);
+void btrfs_tree_read_lock(struct extent_buffer *eb);
+void btrfs_tree_read_unlock(struct extent_buffer *eb);
+void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb);
+void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw);
+void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw);
 void btrfs_assert_tree_locked(struct extent_buffer *eb);
+int btrfs_try_tree_read_lock(struct extent_buffer *eb);
+int btrfs_try_tree_write_lock(struct extent_buffer *eb);
+
+static inline void btrfs_tree_unlock_rw(struct extent_buffer *eb, int rw)
+{
+	if (rw == BTRFS_WRITE_LOCK || rw == BTRFS_WRITE_LOCK_BLOCKING)
+		btrfs_tree_unlock(eb);
+	else if (rw == BTRFS_READ_LOCK_BLOCKING)
+		btrfs_tree_read_unlock_blocking(eb);
+	else if (rw == BTRFS_READ_LOCK)
+		btrfs_tree_read_unlock(eb);
+	else
+		BUG();
+}
+
+static inline void btrfs_set_lock_blocking(struct extent_buffer *eb)
+{
+	btrfs_set_lock_blocking_rw(eb, BTRFS_WRITE_LOCK);
+}
+
+static inline void btrfs_clear_lock_blocking(struct extent_buffer *eb)
+{
+	btrfs_clear_lock_blocking_rw(eb, BTRFS_WRITE_LOCK_BLOCKING);
+}
 #endif
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 4ce8a9f..ac278dd 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1730,8 +1730,8 @@
 				btrfs_read_buffer(next, ptr_gen);
 
 				btrfs_tree_lock(next);
-				clean_tree_block(trans, root, next);
 				btrfs_set_lock_blocking(next);
+				clean_tree_block(trans, root, next);
 				btrfs_wait_tree_block_writeback(next);
 				btrfs_tree_unlock(next);
 
@@ -1796,8 +1796,8 @@
 				next = path->nodes[*level];
 
 				btrfs_tree_lock(next);
-				clean_tree_block(trans, root, next);
 				btrfs_set_lock_blocking(next);
+				clean_tree_block(trans, root, next);
 				btrfs_wait_tree_block_writeback(next);
 				btrfs_tree_unlock(next);
 
@@ -1864,8 +1864,8 @@
 			next = path->nodes[orig_level];
 
 			btrfs_tree_lock(next);
-			clean_tree_block(trans, log, next);
 			btrfs_set_lock_blocking(next);
+			clean_tree_block(trans, log, next);
 			btrfs_wait_tree_block_writeback(next);
 			btrfs_tree_unlock(next);