ReiserFS file system in Linux

ReiserFS file system in Linux

ReiserFS is a very good file system, its developers are very powerful, the entire file system is completely designed from scratch. Currently, ReiserFS can easily manage hundreds of G file systems, which is very important in enterprise applications. ReiserFS is designed based on object-oriented thinking and consists of a semantic layer and a storage layer. The semantic layer is mainly the management of the object namespace and the definition of the object interface to determine the function of the object. The storage layer is mainly the management of disk space. The semantic layer and the storage layer are linked by a key. The semantic layer generates keys by parsing the object names. The storage layer finds the storage space on the disk by the keys, and the key values ​​are globally unique.

Semantic Layer Main Interface

1) File Interface Each file has an interface ID that identifies a method set that contains all the interfaces that access the ReiserFS file.

2) Attribute Interface ReiserFS implements a new interface that treats each attribute of a file as a file. The value of the attribute is the content of the file to enable directory access to the file attributes.

3) hash interface The directory is a mapping table from file name to file. ReiserFS implements this mapping table through B+ tree. Since the file name is variable, and sometimes the file name is very long, the file name is not suitable as a key value, so the Hash function is introduced to generate the key value.

4) Security Interface The security interface handles all security checks, usually triggered by the file interface. Let's take the read file as an example: the read method of the file interface will call the read chech method of the secure interface to check the security before reading the file data, and the latter will call the read method of the property file to read the file attribute for checking. .

5) Item (Item) interface item interface is mainly a method of balancing items, including: item splitting, item evaluation, item overwriting, item addition, item deletion, Insert and find.

6) Key Assignment Interface When a key is assigned to an item, the key assignment interface is triggered. Each item has a corresponding key assignment method.