Btrfs: Fix per root used space accounting

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>

1 files changed, 23 insertions, 8 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index fcdccfa46004..44d7a322ec28 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3454,14 +3454,6 @@ static int update_block_group(struct btrfs_trans_handle *trans,
         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_handle *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_trans_handle *trans,
                                         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;
 }