btrfs: update comments at btrfs_record_unlink_dir() to be more clear

Update the comments at btrfs_record_unlink_dir() so that they mention
where new names are logged and where old names are removed. Also, while
at it make the width of the comments closer to 80 columns and capitalize
the sentences and finish them with punctuation.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -7326,15 +7326,19 @@ void btrfs_record_unlink_dir(struct btrfs_trans_handle *trans,
 	mutex_unlock(&inode->log_mutex);
 
 	/*
-	 * if this directory was already logged any new
-	 * names for this file/dir will get recorded
+	 * If this directory was already logged, any new names will be logged
+	 * with btrfs_log_new_name() and old names will be deleted from the log
+	 * tree with btrfs_del_dir_entries_in_log() or with
+	 * btrfs_del_inode_ref_in_log().
 	 */
 	if (inode_logged(trans, dir, NULL) == 1)
 		return;
 
 	/*
-	 * if the inode we're about to unlink was logged,
-	 * the log will be properly updated for any new names
+	 * If the inode we're about to unlink was logged before, the log will be
+	 * properly updated with the new name with btrfs_log_new_name() and the
+	 * old name removed with btrfs_del_dir_entries_in_log() or with
+	 * btrfs_del_inode_ref_in_log().
 	 */
 	if (inode_logged(trans, inode, NULL) == 1)
 		return;