[054/111] Btrfs: Fix per root used space accounting

[Greg KH <gregkh@suse.de>]

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Yan, Zheng <zheng.yan@oracle.com>

commit 86b9f2eca5e0984145e3c7698a7cd6dd65c2a93f upstream.

The bytes_used field in root item was originally planned to
trace the amount of used data and tree blocks. But it never
worked right since we can't trace freeing of data accurately.
This patch changes it to only trace the amount of tree blocks.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Acked-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/btrfs/ctree.c       |   31 ++++++++++++++-----------------
 fs/btrfs/ctree.h       |    4 ++++
 fs/btrfs/extent-tree.c |   31 +++++++++++++++++++++++--------
 fs/btrfs/ioctl.c       |    2 +-
 fs/btrfs/transaction.c |    6 +++++-
 5 files changed, 47 insertions(+), 27 deletions(-)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -456,9 +456,8 @@ static noinline int __btrfs_cow_block(st
 		extent_buffer_get(cow);
 		spin_unlock(&root->node_lock);
 
-		btrfs_free_extent(trans, root, buf->start, buf->len,
-				  parent_start, root->root_key.objectid,
-				  level, 0);
+		btrfs_free_tree_block(trans, root, buf->start, buf->len,
+				parent_start, root->root_key.objectid, level);
 		free_extent_buffer(buf);
 		add_root_to_dirty_list(root);
 	} else {
@@ -473,9 +472,8 @@ static noinline int __btrfs_cow_block(st
 		btrfs_set_node_ptr_generation(parent, parent_slot,
 					      trans->transid);
 		btrfs_mark_buffer_dirty(parent);
-		btrfs_free_extent(trans, root, buf->start, buf->len,
-				  parent_start, root->root_key.objectid,
-				  level, 0);
+		btrfs_free_tree_block(trans, root, buf->start, buf->len,
+				parent_start, root->root_key.objectid, level);
 	}
 	if (unlock_orig)
 		btrfs_tree_unlock(buf);
@@ -1035,8 +1033,8 @@ static noinline int balance_level(struct
 		btrfs_tree_unlock(mid);
 		/* once for the path */
 		free_extent_buffer(mid);
-		ret = btrfs_free_extent(trans, root, mid->start, mid->len,
-					0, root->root_key.objectid, level, 1);
+		ret = btrfs_free_tree_block(trans, root, mid->start, mid->len,
+					    0, root->root_key.objectid, level);
 		/* once for the root ptr */
 		free_extent_buffer(mid);
 		return ret;
@@ -1100,10 +1098,10 @@ static noinline int balance_level(struct
 				       1);
 			if (wret)
 				ret = wret;
-			wret = btrfs_free_extent(trans, root, bytenr,
-						 blocksize, 0,
-						 root->root_key.objectid,
-						 level, 0);
+			wret = btrfs_free_tree_block(trans, root,
+						     bytenr, blocksize, 0,
+						     root->root_key.objectid,
+						     level);
 			if (wret)
 				ret = wret;
 		} else {
@@ -1148,9 +1146,8 @@ static noinline int balance_level(struct
 		wret = del_ptr(trans, root, path, level + 1, pslot);
 		if (wret)
 			ret = wret;
-		wret = btrfs_free_extent(trans, root, bytenr, blocksize,
-					 0, root->root_key.objectid,
-					 level, 0);
+		wret = btrfs_free_tree_block(trans, root, bytenr, blocksize,
+					 0, root->root_key.objectid, level);
 		if (wret)
 			ret = wret;
 	} else {
@@ -3794,8 +3791,8 @@ static noinline int btrfs_del_leaf(struc
 	 */
 	btrfs_unlock_up_safe(path, 0);
 
-	ret = btrfs_free_extent(trans, root, leaf->start, leaf->len,
-				0, root->root_key.objectid, 0, 0);
+	ret = btrfs_free_tree_block(trans, root, leaf->start, leaf->len,
+				    0, root->root_key.objectid, 0);
 	return ret;
 }
 /*
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1982,6 +1982,10 @@ struct extent_buffer *btrfs_alloc_free_b
 					u64 parent, u64 root_objectid,
 					struct btrfs_disk_key *key, int level,
 					u64 hint, u64 empty_size);
+int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  u64 bytenr, u32 blocksize,
+			  u64 parent, u64 root_objectid, int level);
 struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
 					    struct btrfs_root *root,
 					    u64 bytenr, u32 blocksize,
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3454,14 +3454,6 @@ static int update_block_group(struct btr
 	else
 		old_val -= num_bytes;
 	btrfs_set_super_bytes_used(&info->super_copy, old_val);
-
-	/* block accounting for root item */
-	old_val = btrfs_root_used(&root->root_item);
-	if (alloc)
-		old_val += num_bytes;
-	else
-		old_val -= num_bytes;
-	btrfs_set_root_used(&root->root_item, old_val);
 	spin_unlock(&info->delalloc_lock);
 
 	while (total) {
@@ -4049,6 +4041,21 @@ int btrfs_free_extent(struct btrfs_trans
 	return ret;
 }
 
+int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  u64 bytenr, u32 blocksize,
+			  u64 parent, u64 root_objectid, int level)
+{
+	u64 used;
+	spin_lock(&root->node_lock);
+	used = btrfs_root_used(&root->root_item) - blocksize;
+	btrfs_set_root_used(&root->root_item, used);
+	spin_unlock(&root->node_lock);
+
+	return btrfs_free_extent(trans, root, bytenr, blocksize,
+				 parent, root_objectid, level, 0);
+}
+
 static u64 stripe_align(struct btrfs_root *root, u64 val)
 {
 	u64 mask = ((u64)root->stripesize - 1);
@@ -4897,6 +4904,14 @@ static int alloc_tree_block(struct btrfs
 					extent_op);
 		BUG_ON(ret);
 	}
+
+	if (root_objectid == root->root_key.objectid) {
+		u64 used;
+		spin_lock(&root->node_lock);
+		used = btrfs_root_used(&root->root_item) + num_bytes;
+		btrfs_set_root_used(&root->root_item, used);
+		spin_unlock(&root->node_lock);
+	}
 	return ret;
 }
 
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -289,7 +289,7 @@ static noinline int create_subvol(struct
 	btrfs_set_root_generation(&root_item, trans->transid);
 	btrfs_set_root_level(&root_item, 0);
 	btrfs_set_root_refs(&root_item, 1);
-	btrfs_set_root_used(&root_item, 0);
+	btrfs_set_root_used(&root_item, leaf->len);
 	btrfs_set_root_last_snapshot(&root_item, 0);
 
 	memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -501,13 +501,16 @@ static int update_cowonly_root(struct bt
 {
 	int ret;
 	u64 old_root_bytenr;
+	u64 old_root_used;
 	struct btrfs_root *tree_root = root->fs_info->tree_root;
 
+	old_root_used = btrfs_root_used(&root->root_item);
 	btrfs_write_dirty_block_groups(trans, root);
 
 	while (1) {
 		old_root_bytenr = btrfs_root_bytenr(&root->root_item);
-		if (old_root_bytenr == root->node->start)
+		if (old_root_bytenr == root->node->start &&
+		    old_root_used == btrfs_root_used(&root->root_item))
 			break;
 
 		btrfs_set_root_node(&root->root_item, root->node);
@@ -516,6 +519,7 @@ static int update_cowonly_root(struct bt
 					&root->root_item);
 		BUG_ON(ret);
 
+		old_root_used = btrfs_root_used(&root->root_item);
 		ret = btrfs_write_dirty_block_groups(trans, root);
 		BUG_ON(ret);
 	}