REVIEW o Allocation of Frames o Thrashing o Working-Set Model o Copy-on-Write o Memory-Mapped Files o Other Consideration ·Prepaging ·Page Size
REVIEW Allocation of Frames Thrashing Working-Set Model Copy-on-Write Memory-Mapped Files Other Consideration Prepaging Page Size 1
CHAPTER 10:FILE-SYSTEM INTERFACE o File Concept o Access Methods o Directory Structure o File-System Mounting o File Sharing o Protection
CHAPTER 10: FILE-SYSTEM INTERFACE File Concept Access Methods Directory Structure File-System Mounting File Sharing Protection
Symbolic Open Levels of file name file ID abstraction USER File system interface Files/ directories Directory High-level file and FS management directory functions Logical block Basic file IO system Open/close functions Physical device address Device organization Low-level data methods access functions IO system interface Logical block#
3
PROTECTION o File owner/creator should be able to control: ·what can be done ·by whom o Types of access ·Read ·Write 。Execute ·Append ·Delete ·List
PROTECTION File owner/creator should be able to control: what can be done by whom Types of access Read Write Execute Append Delete List
ACCESS LISTS AND GROUPS o Mode of access:read,write,execute o Three classes of users RWX a)owner access 7 → 111 RWX b) group access 6 → 110 RWX c)public access 1 → 001 o Ask manager to create a group (unique name),say G,and add some users to the group. o For a particular file (say game)or subdirectory,define an appropriate access. owner group public chmod 761 game Attach a group to a file chgrp G game
ACCESS LISTS AND GROUPS Mode of access: read, write, execute Three classes of users RWX a) owner access 7 1 1 1 RWX b) group access 6 1 1 0 RWX c) public access 1 0 0 1 Ask manager to create a group (unique name), say G, and add some users to the group. For a particular file (say game) or subdirectory, define an appropriate access. owner group public chmod 761 game Attach a group to a file chgrp G game