diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e4a7489..891a583 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3129,6 +3129,8 @@ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, int delay_iput,
 			       int nr);
 int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end,
 			      struct extent_state **cached_state, int dedupe);
+int btrfs_set_extent_defrag(struct inode *inode, u64 start, u64 end,
+			    struct extent_state **cached_state);
 int btrfs_create_subvol_root(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *new_root,
 			     struct btrfs_root *parent_root,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ed37204..ef6abb2 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1750,11 +1750,15 @@ static void btrfs_split_extent_hook(void *private_data,
 {
 	struct inode *inode = private_data;
 	u64 size;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
 
 	/* not delalloc, ignore it */
 	if (!(orig->state & EXTENT_DELALLOC))
 		return;
 
+	if (root == root->fs_info->tree_root)
+		return;
+
 	size = orig->end - orig->start + 1;
 	if (size > BTRFS_MAX_EXTENT_SIZE) {
 		u64 num_extents;
@@ -1793,11 +1797,15 @@ static void btrfs_merge_extent_hook(void *private_data,
 	struct inode *inode = private_data;
 	u64 new_size, old_size;
 	u64 num_extents;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
 
 	/* not delalloc, ignore it */
 	if (!(other->state & EXTENT_DELALLOC))
 		return;
 
+	if (root == root->fs_info->tree_root)
+		return;
+
 	if (new->start > other->start)
 		new_size = new->end - other->start + 1;
 	else
@@ -1905,13 +1913,16 @@ static void btrfs_set_bit_hook(void *private_data,
 	if (!(state->state & EXTENT_DELALLOC) && (*bits & EXTENT_DELALLOC)) {
 		struct btrfs_root *root = BTRFS_I(inode)->root;
 		u64 len = state->end + 1 - state->start;
+		u64 num_extents = div64_u64(len + BTRFS_MAX_EXTENT_SIZE - 1,
+					    BTRFS_MAX_EXTENT_SIZE);
 		bool do_list = !btrfs_is_free_space_inode(inode);
 
-		if (*bits & EXTENT_FIRST_DELALLOC) {
+		if (*bits & EXTENT_FIRST_DELALLOC)
 			*bits &= ~EXTENT_FIRST_DELALLOC;
-		} else {
+
+		if (root != root->fs_info->tree_root) {
 			spin_lock(&BTRFS_I(inode)->lock);
-			BTRFS_I(inode)->outstanding_extents++;
+			BTRFS_I(inode)->outstanding_extents += num_extents;
 			spin_unlock(&BTRFS_I(inode)->lock);
 		}
 
@@ -1961,7 +1972,7 @@ static void btrfs_clear_bit_hook(void *private_data,
 
 		if (*bits & EXTENT_FIRST_DELALLOC) {
 			*bits &= ~EXTENT_FIRST_DELALLOC;
-		} else if (!(*bits & EXTENT_DO_ACCOUNTING)) {
+		} else if (!(*bits & EXTENT_DO_ACCOUNTING) && do_list) {
 			spin_lock(&BTRFS_I(inode)->lock);
 			BTRFS_I(inode)->outstanding_extents -= num_extents;
 			spin_unlock(&BTRFS_I(inode)->lock);
@@ -2162,9 +2173,54 @@ static noinline int add_pending_csums(struct btrfs_trans_handle *trans,
 int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end,
 			      struct extent_state **cached_state, int dedupe)
 {
+	int ret;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	u64 num_extents = div64_u64(end - start + BTRFS_MAX_EXTENT_SIZE,
+				    BTRFS_MAX_EXTENT_SIZE);
+
 	WARN_ON((end & (PAGE_SIZE - 1)) == 0);
-	return set_extent_delalloc(&BTRFS_I(inode)->io_tree, start, end,
-				   cached_state);
+	ret = set_extent_delalloc(&BTRFS_I(inode)->io_tree, start, end,
+				  cached_state);
+
+	/*
+	 * btrfs_delalloc_reserve_metadata() will first add number of
+	 * outstanding extents according to data length, which is inaccurate
+	 * for case like dirtying already dirty pages.
+	 * so here we will decrease such inaccurate numbers, to make
+	 * outstanding_extents only rely on the correct values added by
+	 * set_bit_hook()
+	 *
+	 * Also, we skipped the metadata space reserve for space cache inodes,
+	 * so don't modify the outstanding_extents value.
+	 */
+	if (ret == 0 && root != root->fs_info->tree_root) {
+		spin_lock(&BTRFS_I(inode)->lock);
+		BTRFS_I(inode)->outstanding_extents -= num_extents;
+		spin_unlock(&BTRFS_I(inode)->lock);
+	}
+
+	return ret;
+}
+
+int btrfs_set_extent_defrag(struct inode *inode, u64 start, u64 end,
+			    struct extent_state **cached_state)
+{
+	int ret;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	u64 num_extents = div64_u64(end - start + BTRFS_MAX_EXTENT_SIZE,
+				    BTRFS_MAX_EXTENT_SIZE);
+
+	WARN_ON((end & (PAGE_SIZE - 1)) == 0);
+	ret = set_extent_defrag(&BTRFS_I(inode)->io_tree, start, end,
+				cached_state);
+
+	if (ret == 0 && root != root->fs_info->tree_root) {
+		spin_lock(&BTRFS_I(inode)->lock);
+		BTRFS_I(inode)->outstanding_extents -= num_extents;
+		spin_unlock(&BTRFS_I(inode)->lock);
+	}
+
+	return ret;
 }
 
 /* see btrfs_writepage_start_hook for details on why this is required */
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index dc295a7..0cb76a4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1236,10 +1236,8 @@ again:
 				(page_cnt - i_done) << PAGE_SHIFT);
 	}
 
-
-	set_extent_defrag(&BTRFS_I(inode)->io_tree, page_start, page_end - 1,
-			  &cached_state);
-
+	btrfs_set_extent_defrag(inode, page_start,
+				page_end - 1, &cached_state);
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 			     page_start, page_end - 1, &cached_state,
 			     GFP_NOFS);
