Btrfs: delay commits during fsync to allow more writers

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index d5f491d..e451783 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -23,6 +23,7 @@
 struct btrfs_transaction {
 	u64 transid;
 	unsigned long num_writers;
+	unsigned long num_joined;
 	int in_commit;
 	int use_count;
 	int commit_done;
@@ -57,6 +58,12 @@
 	BTRFS_I(inode)->block_group = trans->block_group;
 }
 
+static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
+					      struct inode *inode)
+{
+	BTRFS_I(inode)->last_trans = trans->transaction->transid;
+}
+
 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *root);
 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,