Btrfs: Add a write ahead tree log to optimize synchronous operations

File syncs and directory syncs are optimized by copying their
items into a special (copy-on-write) log tree.  There is one log tree per
subvolume and the btrfs super block points to a tree of log tree roots.

After a crash, items are copied out of the log tree and back into the
subvolume.  See tree-log.c for all the details.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 125094617fe8..e4f30090d640 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -96,6 +96,7 @@ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
         btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
         btrfs_set_dir_name_len(leaf, dir_item, name_len);
+        btrfs_set_dir_transid(leaf, dir_item, trans->transid);
         btrfs_set_dir_data_len(leaf, dir_item, data_len);
         name_ptr = (unsigned long)(dir_item + 1);
         data_ptr = (unsigned long)((char *)name_ptr + name_len);
@@ -142,6 +143,7 @@ int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
         btrfs_set_dir_type(leaf, dir_item, type);
         btrfs_set_dir_data_len(leaf, dir_item, 0);
         btrfs_set_dir_name_len(leaf, dir_item, name_len);
+        btrfs_set_dir_transid(leaf, dir_item, trans->transid);
         name_ptr = (unsigned long)(dir_item + 1);
 
         write_extent_buffer(leaf, name, name_ptr, name_len);
@@ -169,6 +171,7 @@ second_insert:
         btrfs_set_dir_type(leaf, dir_item, type);
         btrfs_set_dir_data_len(leaf, dir_item, 0);
         btrfs_set_dir_name_len(leaf, dir_item, name_len);
+        btrfs_set_dir_transid(leaf, dir_item, trans->transid);
         name_ptr = (unsigned long)(dir_item + 1);
         write_extent_buffer(leaf, name, name_ptr, name_len);
         btrfs_mark_buffer_dirty(leaf);