S5FS DISK MAP CODE
S5FS DISK MAP FREE

Size of FS, size of inode list, number of free blocks/inodes, free block/inode list inode list - linear array of 64byte inode structs CS523 – Operating Systems

S5FS DISK MAP CODE

S5fs disk layout data bootarea inode list superblock Boot area - code to initialize bootstrap the system Superblock- metadata for filesystem.

first few blocks are the boot area, which is followed by theinode list (fixed size) CS523 – Operating Systemsĭisk Layout tract sector heads cylinder platters Rotational speed disk seek time CS523 – Operating Systems.

Physical block number is the block’s index in array.

Typical disk block size 512, 1024, 2048 bytes.

FFS/UFS - BSD developed filesystem with optimized disk usage algorithms CS523 – Operating Systems.

uses timestamps to optimize lookups CS523 – Operating Systems.

vnode locking across multiple operations.

May use a Directory Lookup Cache (name to vnode) CS523 – Operating Systems.

vnodes reference counts incremented during lookup.

If component is a symbolic link, then append path.

If a component corresponds to a mount point then locate root vnode of mounted fs.

Otherwise not end and not found then ENOENT error.

if not found and last component return vnode of parent directory.

if component found, return pointer to vnode.

Verify vnode is directory, if not then stop.

Path traversal must, for each path component perform the following:.

locate and initialize root vnode of FS in memory (VFS_ROOT) CS523 – Operating Systems.

SVR5 uses a global virtual file system switch table (vfssw).

mount(spec, dir, flags, type, dataptr, datalen).

POSIX defines library routines / (root) /usr / (mounted fs) CS523 – Operating Systems.

Directory entry for a file is known as a hard link.

files and directories form hierarchical tree structure name space.

Applications requiring more structure must define and implement themselves CS523 – Operating Systems.

Otherwise complete pathnames are required. Running programs have an associated current working directory.kernel provides control operations to name, organize and control access to files but it does not interpret contents.Interface exported abstractions: files, directories, file descriptorsand differentfile systems CS523 – Operating Systems.User interface specifies behavior and semantics of relevant system calls.file system - permits organizing, manipulating and accessing files.file - abstraction for data container, supports sequential and random access.File System Interface and Implementations Fred Kuhns CS523 – Operating Systems

S5fs disk map