btrfs: pass the dentry to btrfs_log_new_name() instead of the inode

In the next patch in the series, there will be the need to access the old
name, and its length, of an inode when logging the inode during a rename.
So instead of passing the inode to btrfs_log_new_name() pass the dentry,
because from the dentry we can get the inode, the name and its length.

This will avoid passing 3 new parameters to btrfs_log_new_name() in the
next patch - the name, its length and an index number. This way we end
up passing only 1 new parameter, the index number.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -6531,7 +6531,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 				goto fail;
 		}
 		d_instantiate(dentry, inode);
-		btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent);
+		btrfs_log_new_name(trans, old_dentry, NULL, parent);
 	}
 
 fail:
@@ -9211,13 +9211,13 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 		BTRFS_I(new_inode)->dir_index = new_idx;
 
 	if (root_log_pinned) {
-		btrfs_log_new_name(trans, BTRFS_I(old_inode), BTRFS_I(old_dir),
+		btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
 				   new_dentry->d_parent);
 		btrfs_end_log_trans(root);
 		root_log_pinned = false;
 	}
 	if (dest_log_pinned) {
-		btrfs_log_new_name(trans, BTRFS_I(new_inode), BTRFS_I(new_dir),
+		btrfs_log_new_name(trans, new_dentry, BTRFS_I(new_dir),
 				   old_dentry->d_parent);
 		btrfs_end_log_trans(dest);
 		dest_log_pinned = false;
@@ -9498,7 +9498,7 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 		BTRFS_I(old_inode)->dir_index = index;
 
 	if (log_pinned) {
-		btrfs_log_new_name(trans, BTRFS_I(old_inode), BTRFS_I(old_dir),
+		btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
 				   new_dentry->d_parent);
 		btrfs_end_log_trans(root);
 		log_pinned = false;

fs/btrfs/tree-log.c

@@ -6788,14 +6788,25 @@ void btrfs_record_snapshot_destroy(struct btrfs_trans_handle *trans,
 	mutex_unlock(&dir->log_mutex);
 }
 
-/*
- * Call this after adding a new name for a file and it will properly
- * update the log to reflect the new name.
+/**
+ * Update the log after adding a new name for an inode.
+ *
+ * @trans:              Transaction handle.
+ * @old_dentry:         The dentry associated with the old name and the old
+ *                      parent directory.
+ * @old_dir:            The inode of the previous parent directory for the case
+ *                      of a rename. For a link operation, it must be NULL.
+ * @parent:             The dentry associated with the directory under which the
+ *                      new name is located.
+ *
+ * Call this after adding a new name for an inode, as a result of a link or
+ * rename operation, and it will properly update the log to reflect the new name.
  */
 void btrfs_log_new_name(struct btrfs_trans_handle *trans,
-			struct btrfs_inode *inode, struct btrfs_inode *old_dir,
+			struct dentry *old_dentry, struct btrfs_inode *old_dir,
 			struct dentry *parent)
 {
+	struct btrfs_inode *inode = BTRFS_I(d_inode(old_dentry));
 	struct btrfs_log_ctx ctx;
 
 	/*

fs/btrfs/tree-log.h

@@ -86,7 +86,7 @@ void btrfs_record_unlink_dir(struct btrfs_trans_handle *trans,
 void btrfs_record_snapshot_destroy(struct btrfs_trans_handle *trans,
 				   struct btrfs_inode *dir);
 void btrfs_log_new_name(struct btrfs_trans_handle *trans,
-			struct btrfs_inode *inode, struct btrfs_inode *old_dir,
+			struct dentry *old_dentry, struct btrfs_inode *old_dir,
 			struct dentry *parent);
 
 #endif