PNFS

#+TITLE: PNFS #+AUTHOR: Dan Printzell #+EMAIL: me@vild.io

• Introduction This is a filesystem that is designed and implemented for a school assignment. The structure is kinda based on ext2 and runs on a "virtual" HDD. That have 250 blocks, where each block is 512 bytes.

The name PNFS stands for PowerNexFileSystem. But I haven't decided if I want to use this in [[https://github.com/Vild/PowerNex][PowerNex]].

• License Mozilla Public License, version 2.0 - See LICENSE or [[https://www.mozilla.org/en-US/MPL/2.0/][here]].

• Design ** Blocks

• Block 0
  • Header
• Block 1-16
  • Node x8 // Total of 128 Nodes
• Block 17
  • Root DirBlock
  • DirEntries x8

** Class diagram #+begin_src plantuml :file images/classdiagram.png :exports results

class fs_block { This reprecents a block on the disk. --- data: uint8_t[512] }

class fs_blockdevice { This emulates a block device. A block device could for example be a harddrive. --- blocks: fs_block[250]

 clear(): void
 load(char * file): bool
 save(char * file): bool

 read(fs_block_id idx, fs_block * block)
 write(fs_block_id idx, fs_block * block)

} fs_block --o fs_blockdevice

class fs_node { This is a abstract representation of a filesystem node. A node can be either a file or a folder.

 The underlying filesystem should inherit this for its own node structure.
 ---
 id: uint16_t
 type: uint16_t // fs_node_type
 size: uint16_t
 blockCount: uint16_t

 {abstract} readData(void * buffer, uint16_t offset, uint16_t size): uint16_t
 {abstract} writeData(void * buffer, uint16_t offset, uint16_t size): bool

 {abstract} directoryEntries(uint16_t * amount): fs_direntry *
 {abstract} findNode(char * path): fs_node *

 {abstract} getName(struct fs_node * parent): char *
 {abstract} getParent(struct fs_node * node): fs_node *

}

class fs_supernode { This is a abstract representation of a supernode, the node that stores and controls the while filesystem.

 The underlying filesystem should inherit this for its own supernode structure.
 ---
 {abstract} getNode(fs_node_id id): fs_node *
 {abstract} saveNode(struct fs_node * node): void

 {abstract} addNode(struct fs_node * parent, enum fs_node_type type, char * name): fs_node *
 {abstract} removeNode(struct fs_node * parent, fs_node_id id): bool

 {abstract} getFreeNodeID(struct fs_supernode * sn): fs_node_id
 {abstract} getFreeBlockID(struct fs_supernode * sn): fs_block_id

 {abstract} setBlockUsed(fs_block_id id): void
 {abstract} setBlockFree(fs_block_id id): void

}

enum fs_nodes { This contains a few standarized node ids and what they represent. --- Invalid = 0 Root = 1 } fs_nodes -- fs_supernode

enum fs_node_type { This contains the different types that a fs_node can be. --- Invalid File Directory NeverValid } fs_node_type --o fs_node

class fs_direntry { This represents a directory entry. --- id: fs_node_id name: char[62] } fs_direntry -- fs_node

class pnfs_node extends fs_node { This is the node structure for the implementation of PNFS. --- dataBlocks: fs_block_id[27] next: fs_block_id

 runtimeStorage.sn: pnfs_supernode *

 readData(void * buffer, uint16_t offset, uint16_t size): uint16_t
 writeData(void * buffer, uint16_t offset, uint16_t size): bool

 directoryEntries(uint16_t * amount): fs_direntry *
 findNode(char * path): fs_node *

 getName(struct fs_node * parent): char *
 getParent(struct fs_node * node): fs_node *

} pnfs_supernode --o pnfs_node

class pnfs_supernode extends fs_supernode { This is the supernode structure for the implementation of PNFS. --- magic: uint32_t freeBlocksBitmap: uint8_t[32]

 runtimeStorage.bd: fs_blockdevice *

 getNode(fs_node_id id): fs_node *
 saveNode(struct fs_node * node): void

 addNode(struct fs_node * parent, enum fs_node_type type, char * name): fs_node *
 removeNode(struct fs_node * parent, fs_node_id id): bool

 getFreeNodeID(struct fs_supernode * sn): fs_node_id
 getFreeBlockID(struct fs_supernode * sn): fs_block_id

 setBlockUsed(fs_block_id id): void
 setBlockFree(fs_block_id id): void

} fs_blockdevice --o pnfs_supernode

#+end_src

#+RESULTS: [[file:images/classdiagram.png]]

• Tree #+begin_src dot :file tree.png digraph tree { graph [ rankdir = LR, ranksep = 1 ]; node [ fontsize = "16" shape = "ellipse" ]; edge [ ];

    "start" [
    	style=filled,
    	fillcolor=green,
    	label="Filesystem root"
    ];
    "start" -> "root";
  
    "root" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,			
    	label="***fs_node***|id = 1|type = dir"
    ];
    "root" -> "root_direntry":d [
    	shape="record",
    	label = "directoryEntries()"
    ];
  

  "root_direntry" [ shape="record", style=filled, fillcolor=pink, label="<d>*fs_direntry[]|<d0> .(1) | <d1> ..(1) | <d2> bin(2) | <d3> data(3)" ];

    "root_direntry":d0 -> "root" [
    	label="getNode(1)"
    ];
  
    "root_direntry":d1 -> "root" [
    	label="getNode(1)"
    ];
  
    "root_direntry":d2 -> "bin" [
    	label="getNode(2)"
    ];
  
    "root_direntry":d3 -> "data" [
    	label="getNode(3)"
    ];
  
  
  
    "bin" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,
    	label="***fs_node***|id = 2|type = dir"
    ];
    "bin" -> "bin_direntry":d [
    	shape="record",
    	label = "directoryEntries()"
    ];
    "bin_direntry" [
    	shape="record",
    	style=filled,
    	fillcolor=pink,
    	label="<d>***fs_direntry[]***| <d0> .(1) | <d1> ..(1) | <d2> bin(2) | <d3> data(3)"
    ];
  
    "bin_direntry" [
    	shape="record",
    	label="<d>***fs_direntry[]***| <d0> .(2) | <d1> ..(1) | <d2> helloworld(4) | <d3> testprogram(5)"
    ];
  
    "bin_direntry":d0 -> "bin" [
    	label="getNode(2)"
    ];
  
    "bin_direntry":d1 -> "root" [
    	label="getNode(1)"
    ];
  
    "bin_direntry":d2 -> "helloworld" [
    	label="getNode(4)"
    ];
  
    "bin_direntry":d3 -> "testprogram" [
    	label="getNode(5)"
    ];
  
    "data" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,
    	label="***fs_node***|id = 3|type = dir"
    ];
    "data" -> "data_direntry":d [			
    	shape="record",
    	label = "directoryEntries()"
    ];
    "data_direntry" [
    	shape="record",
    	style=filled,
    	fillcolor=pink,
    	label="<d>***fs_direntry[]***| <d0> .(3) | <d1> ..(1) | <d2> image.bmp(6) | <d3> sound.ogg(7)"
    ];
  
    "data_direntry":d0 -> "data" [
    	label="getNode(3)"
    ];
  
    "data_direntry":d1 -> "root" [
    	label="getNode(1)"
    ];
  
    "data_direntry":d2 -> "image.bmp" [
    	label="getNode(6)"
    ];
  
    "data_direntry":d3 -> "sound.ogg" [
    	label="getNode(7)"
    ];
  
  
    "helloworld" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,
    	label="***fs_node***|id = 4|type = file"
    ];
    "testprogram" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,
    	label="***fs_node***|id = 5|type = file"
    ];
    "image.bmp" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,
    	label="***fs_node***|id = 6|type = file"
    ];
    "sound.ogg" [
    	shape="record",
    	style=filled,
    	fillcolor=cyan,
    	label="***fs_node***|id = 7|type = file"
    ];
  

  } #+end_src

#+RESULTS: [[file:tree.png]]