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Final Project: ThreadOS File System

Final Project: ThreadOS File System. Joe McCarthy. ThreadOS Superblock & Inodes. Superblock int totalBlocks; int totalInodes; int freeList;. Block #0. Free Block #x. Free Block #y. Free Block #z. Inode #0 32bytes. Inode #1. Block #1. Inode #15. / root directory. Block #2.

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Final Project: ThreadOS File System

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  1. Final Project:ThreadOS File System Joe McCarthy CSS 430: Operating Systems - ThreadOS File System

  2. ThreadOS Superblock & Inodes Superblock int totalBlocks; int totalInodes; int freeList; Block #0 Free Block #x Free Block #y Free Block #z Inode #0 32bytes Inode #1 Block #1 Inode #15 / root directory Block #2 Inode #inodeBlocks -1 Block #(totalBlocks – 1) CSS 430: Operating Systems - ThreadOS File System

  3. ThreadOS Root Directory (“/”) • Directory() • Initialize “/” directory • bytes2directory( byte[] data ) • Populate directory with byte[] retrieved from disk • directory2bytes() • Converts directory information into byte[] • ialloc( String filename ) • Allocate an iNumber for filename • ifree( short iNumber ) • Deallocate the iNumber • namei( String filename ) • Return filename’s iNumber Entry[] fsizes fnames (iNumber) 0 1 2 3 4 5 6 7 8 9 10 inodeBlock-1 1 4 4 4 4 5 5 6 6 9 6 6 5 / init fsck clri motd mount mknod passwd umount checklist fsdblb config getty CSS 430: Operating Systems - ThreadOS File System

  4. CSS430 ThreadOS File System Thread int fd = SysLib.open(“fileA”, mode); SysLib.read(fd, …); A simplified structure of Unix file system TCB 0 1 2 3 31 stdin stdout Inode: length count 1 direct[11] indirect stderr struct file: count 1 inode Disk ftEnt[32]per-threadfile table Inode FileTable CSS 430: Operating Systems - ThreadOS File System

  5. FileSystem public class FileSystem { private SuperBlock superblock; private Directory directory; private FileTable filetable; public FileSystem( int diskBlocks ) { superblock = new SuperBlock( diskBlocks ); directory = new Directory( superblock.inodeBlocks ); filetable = new FileTable( directory ); FileTableEntry dirEnt = open( "/", "r" ); int dirSize = fsize( dirEnt ); if ( dirSize > 0 ) { byte[] dirData = new byte[dirSize]; read( dirEnt, dirData ); directory.bytes2directory( dirData ); } close( dirEnt ); } ... SuperBlock SysLib.rawread( 0, byte[] ) Directory SysLib.rawread( 1, byte[] ) FileTable Disk CSS 430: Operating Systems - ThreadOS File System

  6. FileSystem public class FileSystem { private SuperBlock superblock; private Directory directory; private FileTable filetable; ... void sync() boolean format( int files ) FileTableEntry open( String filename, String mode ) boolean close( FileTableEntry ftEnt ) int fsize( FileTableEntry ftEnt ) int read( FileTableEntry ftEnt, byte[] buffer ) int write( FileTableEntry ftEnt, byte[] buffer ) boolean delete( String filename ) int seek( FileTableEntry ftEnt, int offset, int whence ) } SuperBlock SysLib.rawread( 0, byte[] ) Directory SysLib.rawread( 1, byte[] ) FileTable Disk CSS 430: Operating Systems - ThreadOS File System

  7. SuperBlock DISK Superblock int totalBlocks; int inodeBlocks; int freeList; public class SuperBlock { private final int defaultInodeBlocks = 64; public int totalBlocks; public int inodeBlocks; public int freeList; public SuperBlock( int diskSize ) { byte[] superBlock = new byte[Disk.blockSize]; SysLib.rawread( 0, superBlock ); totalBlocks = SysLib.bytes2int( superBlock, 0 ); inodeBlocks = SysLib.bytes2int( superBlock, 4 ); freeList = SysLib.bytes2int( superBlock, 8 ); if ( totalBlocks == diskSize && inodeBlocks > 0 && freeList >= 2 ) return; else { totalBlocks = diskSize; SysLib.cerr( "Formatting\n" ); format(); } } ... Block #0 Inode blocks Data blocks CSS 430: Operating Systems - ThreadOS File System

  8. SuperBlock DISK Superblock int totalBlocks; int inodeBlocks; int freeList; public class SuperBlock { private final int defaultInodeBlocks = 64; public int totalBlocks; public int inodeBlocks; public int freeList; ... void sync() /* write totalBlocks, inodeBlocks, freelist to disk */ void format() void format( int numBlocks ) public int getFreeBlock() /* dequeue top block in freelist */ public boolean returnBlock( int oldBlockNumber ) /* enqueue oldBlockNumber to top of freelist */ } Block #0 Inode #0 32bytes … Block #1 Inode #15 … … … Block #(inodeBlocks / 16) + 1 Inode #inodeBlocks-1 … … Data blocks: CSS 430: Operating Systems - ThreadOS File System

  9. SuperBlock.format(16) DISK public class SuperBlock { private final int defaultInodeBlocks = 64; public int totalBlocks; public int inodeBlocks; public int freeList; ... void format() void format( int numBlocks ) /* initialize Inodes, free blocks */ ... } Superblock totalBlocks = 1000 inodeBlocks = 16 freeList = 2 Block #0 Inode #0 32bytes … Block #1 Inode #15 3 Block #2 4 Block #3 … … … -1 Block #999 CSS 430: Operating Systems - ThreadOS File System

  10. Directory public class Directory { private static int maxChars = 30; // the max characters of each file name private int fsizes[]; // the actual size of each file name private char fnames[][]; // file names in characters public Directory ( int maxInumber ) { // a default constructor fsizes = new int[maxInumber]; // maxInumber = max # files for ( int i = 0; i < maxInumber; i++ ) // all file sizes set to 0 fsizes[i] = 0; fnames = new char[maxInumber][maxChars]; String root = "/"; // entry (inode) 0 is "/" fsizes[0] = root.length(); root.getChars( 0, fsizes[0], fnames[0], 0 ); } ... } CSS 430: Operating Systems - ThreadOS File System

  11. Directory public class Directory { private static int maxChars = 30; // the max characters of each file name private int fsizes[]; // the actual size of each file name private char fnames[][]; // file names in characters ... public void bytes2directory( byte[] data ) { int offset = 0; for ( int i = 0; i < fsizes.length; i++, offset += 4 ) fsizes[i] = SysLib.bytes2int( data, offset ); for ( int i = 0; i < fnames.length; i++, offset += maxChars * 2 ) { String fname = new String( data, offset, maxChars * 2 ); fname.getChars( 0, fsizes[i], fnames[i], 0 ); } } public byte[] directory2bytes() public short ialloc ( String filename ) /* allocate Inode for filename (-1 if none) */ public boolean ifree ( short iNumber ) /* deallocate Inode # iNumber */ public short namei( String filename ) /* find Inode for filename (-1 if none) */ } CSS 430: Operating Systems - ThreadOS File System

  12. FileTable public class FileTable { // File Structure Table private Vector table; // the actual entity of File Structure Table private Directory dir; // the root directory public FileTable ( Directory directory ) { // a default constructor table = new Vector(); // instantiate a file table dir = directory; // instantiate the root directory } public synchronized FileTableEntry falloc( String fname, String mode ) // allocate a new file table entry for this file name // allocate/retrieve and register the corresponding inode using dir // increment this inode's count // immediately write back this inode to the disk // return a reference to this file table entry public synchronized boolean ffree( FileTableEntry e ) { // receive a file table entry reference // save the corresponding inode to the disk // free this file table entry. // return true if this file table entry found in table public synchronized boolean fempty() { return table.isEmpty(); // return if table is empty } // should be called before a format } CSS 430: Operating Systems - ThreadOS File System

  13. FileTable public synchronized FileTableEntry falloc( String fname, String mode ) short iNumber = -1; Inode inode = null; while ( true ) { iNumber = ( fname.equals( "/" ) ? 0 : dir.namei( fname ) ); if ( iNumber < 0 ) { // file does not exist // create a new Inode (nothing to retrieve from disk) } else { // file exists inode = new Inode( iNumber ); // retrieve inode from disk if ( mode.compareTo( "r" ) == 0 ) { // mode is "r” // if inode.flag indicates file is not already open for writing // break // else wait until writing is done } else { /* ... */ } // mode is "w", "w+" or "a” } } inode.count++; // a new FileTableEntry points to it inode.toDisk( iNumber ); // reflect this inode to disk FileTableEntry e = new FileTableEntry( inode, iNumber, mode ); table.addElement( e ); // add entry to system-wide FileTable return e; // return this new file table entry } CSS 430: Operating Systems - ThreadOS File System

  14. Inode public class Inode { public final static int iNodeSize = 32; // fixed to 32 bytes public final static int directSize = 11; // # direct pointers public int length; // file size in bytes public short count; // # file-table entries pointing to this public short flag; // how is this file (inode) being used? public short direct[] = new short[directSize]; // direct pointers public short indirect; // an indirect pointer Inode () { // a default constructor (new file) length = 0; count = 0; flag = 1; for ( int i = 0; i < directSize; i++ ) direct[i] = -1; indirect = -1; } CSS 430: Operating Systems - ThreadOS File System

  15. Inode DISK Superblock int totalBlocks; int inodeBlocks; int freeList; public class Inode { ... Inode ( short iNumber ) { int blkNumber = iNumber / 16 + 1; byte[] data = new byte[Disk.blockSize]; SysLib.rawread( blkNumber, data ); int offset = ( iNumber % 16 ) * iNodeSize; length = SysLib.bytes2int( data, offset ); offset += 4; count = SysLib.bytes2short( data, offset ); offset += 2; flag = SysLib.bytes2short( data, offset ); offset += 2; for ( int i = 0; i < directSize; i++ ) { direct[i] = SysLib.bytes2short( data, offset ); offset += 2; } indirect = SysLib.bytes2short( data, offset ); } ... Inode #0 32bytes … Inode #15 … … Inode #inodeBlocks-1 … … CSS 430: Operating Systems - ThreadOS File System

  16. Inode DISK Superblock int totalBlocks; int inodeBlocks; int freeList; public class Inode { ... void toDisk( short iNumber ) int findIndexBlock() boolean registerIndexBlock( short indexBlockNumber ) int findTargetBlock( int offset ) int registerTargetBlock( int offset, short targetBlockNumber ) byte[] unregisterIndexBlock() } Inode #0 32bytes … Inode #15 … … Inode #inodeBlocks-1 … … CSS 430: Operating Systems - ThreadOS File System

  17. Opening a File Test5.java: int fd = SysLib.open( "css430", "w+" ); SysLib.java: public static int open( String filename, String mode ) { String[] args = new String[2]; args[0] = filename; args[1] = mode; return Kernel.interrupt( Kernel.INTERRUPT_SOFTWARE, Kernel.OPEN, 0, args ); }; Kernel.java: case OPEN: if ( ( myTcb = scheduler.getMyTcb() ) == null ) return ERROR; else { String[] s = (String[]) args; FileTableEntry ftEnt = fs.open( s[0], s[1] ); int fd = myTcb.getFd( ftEnt ); return fd; } CSS 430: Operating Systems - ThreadOS File System

  18. Opening a File Kernel.java: case OPEN: if ( ( myTcb = scheduler.getMyTcb() ) == null ) return ERROR; else { String[] s = (String[]) args; FileTableEntry ftEnt = fs.open( s[0], s[1] ); int fd = myTcb.getFd( ftEnt ); return fd; } FileSystem.java: FileTableEntry open( String filename, String mode ) { FileTableEntry ftEnt = filetable.falloc( filename, mode ); if ( mode == "w" ) // release all blocks belonging to this file if ( deallocAllBlocks( ftEnt ) == false ) return null; return ftEnt; } CSS 430: Operating Systems - ThreadOS File System

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