Abstract: A file-mapped volume is a logical volume in which the data storage of the logical volume is the data storage of a regular file associated with the logical volume. The regular file can be a file of a first file system, and a second file system can be built upon the file-mapped volume. These two file systems can have distinct inode address spaces, yet files of the first file system are easily moved to the second file system by changing pointers to inodes of these files. The second file system can be easily copied, attached, or transported by copying, attaching, or transporting the regular file containing the second file system, yet files in the second file system can be accessed in real time via file access routines of the operating system.

Abstract: To avoid the need for storing a tree quota identifier attribute for every file in a quota tree, a tree quota identifier is included in the file handle returned by the file server to a client in response to a directory lookup request. The file server discovers that the file is in a quota tree when searching along a path specified by the file pathname and finding a directory having a tree quota identifier. The file server responds to a client request for changing the storage resources used by the file by inspecting the file handle and upon finding the tree quota identifier in the file handle, using the tree quota identifier to index a tree quota database to find usage and limits for the tree quota. The file server checks the limits against any increase in the storage resources for the file, and updates the usage.