Operating System

6

6.1 6.2 6.3 6.4 Linux6.5 Ext26.6 Windows

UNIX

6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6 6.1.7 6.1.8

6.1.1 1. 122.

3. 1/23/

1ASCII23

1234

123// 12I/O

UNIX123

4UNIX5pipe6socketTCPIPsocket1, socket2

6.1.2 1.

2.2(1) (2)

6.1.3 512B1KB2KB4KB

1. 6.1

2. 6.2

ii

FATFile Allocation TableMS-DOSOS/2FAT

6-9

6-10 MS-DOS

3. 6.3

6.4

6.1.4 1.RR+lR+l

2.

3.

6.1.5 1.

6-1

2.ijk=16*i+jKi=k/16j=K%161G1KB1M128(1M/8k)1 1 1 1 0 0 0 0 0 0 1 1 1 1 1 11 1 1 0 0 0 0 0 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 0 0 0 0 0 0 0 00 0 0 0 0 1 1 1 0 0 1 1 1 1 0 015 14 9 8 7 6 5 4 3 2 1 0 0 1 2 3

3.

UNIX

6.1.6 1.

2.3.

4.5. 6.

6.1.7 /

UNIX111 101 001chmod

NTFS NTFS(1)(2)(3)

(4)ABCC(5)(6)

6.1.8 1.

05r=7200/1/r

=++

2.FCFSSSTFSCANCircular SCAN

(1) FCFS (First-Come, First Served) 5-23 FCFS

(2) SSTF (Shortest Seek Time First) 5-24 SSTF

(3) (SCAN) 1) SSTF (Starvation) I/OSSTFSCAN

2) SCAN 5-25 SCAN

6.2 4.2.1 4.2.2 (1)(2)(3)(4)

6.2.1 FCBFile Control Block1.(1)(2)(3)(4)

(5)(6)(7)

2.(1)1K641024/64=16N (N+1) /2

(2)012

6.2.2 1.

2.

3.4-6

/a.out/home/Liu/a.out

(1)B(2)BB /B/B/AA/B

/B/B/AA/B (3)BAA(4)AAB

/usr/ast/mbox (1) usr

(2) 6

.1..1bin4dev7lib14etc9usr6tmp8

1d6d13226d49660f200

/usr/ast/mbox usr(3) 132usrast(4) 26

.6..1are19jkl30hui51ast26lkm45

1d6d13226d49660f200

/usr/ast/mbox ast(5) 496astmbox(6) 60

(7) 200mbox

.26..6gran64book92mbox60mini81scr17

1d6d13226d49660f200

6.3 6.3.1 6.3.2 6.3.3

6.3.1 1.4-7I/O

(1)I/O(2)(3)(4)FCB

2.LinuxUNIXVirtual File System SwitchVFSLinuxDOSExt2

4-8openwritecloseVFS (Virtual File System)VFSVVnodeVVFSvfs-operationsVFSNFS (network file system)

3.WindowsWindows 2000 I/OFile System DriverFSDI/OI/OI/OI/ONTFS

FSDFSDFSDFSDI/OFSDFSDI/OFSDI/OI/OFSDFSDFSD4-9

FSDFSDFSDFSDI/OFSDFSDFSD

6.3.2 primary partitionextended partitionlogical partitionRAID

Format2

UFSNTFSFCBFCBUFSNTFSMFTFCBUFSi(inode)NTFSMFT

FCBFCBFCBI/OI/O

FCBFCBUNIXWindows 2000

6-12

openUFSi

6.3.3 S5FSUnixVFATFile Allocation TableFAT1982MS-DOSFAT12FAT16FAT32NTFSNew Technology File SystemNTFSWindows NTExt2LinuxMinixUnixHPFSHigh Performance File SystemOS/2NFS

6.4 Linux

6.4.1 LinuxUNIXVirtual Filesystem SwitchVFS

VFSread()write()LinuxVFSfile_operations/filefile_operationsf_opf_opLinuxVFS4-11

6.4.2 VFSsuperblock objectinode objectfile object dentry object

6-12

1.Linuxsuper_block

s_listnextprevsuper_blockss_listnextprev6-13

uExt2ext2_sb_infous_opsuper_operationsread_inode(inode)write_inode(inode)put_inode(inode)delete_inode(inode)put_super(super)write_super(super)VFSwrite_inode()VFSsb->s_op->write_inode(inode);sb

2.inodeinode_unusedinode_in_uses_dirtyinode_hashtableuExt2ext2_inode_infoi_op

6-3

3.filefile_operationsinode_operationsdefault_file_ops

file_operationsreadwriteopenioctlreleasereaddir

4. VFSVFSdentry6-5 /usr/local/usr/usrlocal

6-5

5.fs_structfsStruct fs_struct { atomic_t count; fs_struct int umask; umask() struct dentry * root, * pwd; }

files_structfilesfiles_struct6-6 int count int max_fds struct file ** fd struct file * fd_array[32] fdmax_fds32fdmax_fds

file descriptor0126-14Unix

6.4.3 VFS1./open ( )sys_open ( )-1close ( )sys_close ( )

2. /read ( )write ( )///

inoderead ( )write ( )inode6-16

inodepagei_pagespagevirtualpagebuffer_headb_databuffer_headbuffer_headb_data pageinode4buffer_head

read ( )write ( )sys_read ( )sys_write ( )fdbufcountread ( )write ( )-1f_pos

6.5 Ext2LinuxMinixMinix64M14LinuxExt FS1994LinuxSecond Extended File System, Ext2Ext2LinuxExt2Ext2

6.5.1 (1)group descriptor(2)

Ext2Ext2

001108bbs/8bs8GBExt24KB4KB32K128MB64

1.Ext2ext2_super_block6-7 s_inodes_countExt2s_blocks_countExt2s_log_block_size210240102412048 s_blocks_per_group s_inodes_per_group

6-7 Ext2 __u32 s_log_block_size __u32 s_blocks_per_group __u32 s_free_blocks_count __u32 s_inodes_count __u32 s_inodes_per_group __u32 s_free_inodes_count __u32 s_blocks_count __u32 s_creator_os __u16 s_inode_size __u8 [16] s_uuid 128char [16] s_volume_name char [64] s_last_mounted

2.ext2_group_desc

3.bg_inode_table12810248Ext2ext2_inode6-9bg_free_blocks_countbg_free_inodes_countbg_used_dirs_count

6-9 Ext2

0110242048409681921638432768i_sizei_blocks512i_blockEXT2_N_BLOCKS15

6.5.2 Ext2Ext2RAM06-10 Ext2VFS

shrink_mmap( )

1.ext2_sb_infoext2_inode_infoExt2Ext2Ext2ext2_sb_infoExt2VFSuExt2ext2_inode_infoVFSu

ext2_sb_infoVFSs_inode_bitmaps_inode_bitmap_numbers_block_bitmaps_block_bitmap_numbers_sbhs_ess_desc_per_blocks_group_desc

ext2_inode_infoi_block_groupi_alloc_blocki_alloc_counti_osync

2.RAM8GB1KB81928GB/8MB=102420482MBRAMExt2EXT2_MAX_GROUP_LOADED 8

9(a)9(b)9(c)9

ext2_sb_infoExt26-19ext2_sb_infos_group_desc242EXT2_MAX_GROUP_LOADED

6.5.3 Ext2Ext2ext2_sopsVFSclear_inodeumount_beginVFSExt2Ext2ext2_file_inode_operationsext2_dir_inode_operationsioctl(fd, cmd, arg )cmdfdcmdarg

6.5.4 Ext2fffLinuxUnixff4KBf4096f0f40968192f1

1225(b/4)2+(b/4)+12b/4+12(b/4)3+(b/4)2+(b/4)+11i_block012345678910111213144-20 Ext2i_blocki_blockEXT2_N_BLOCKSEXT2_N_BLOCKS154-2015412121212b/4+11b413b/4+12 (b/4)2+(b/4)+1114 (b/4)2+(b/4)+12(b/4)3+(b/4)2+(b/4)+11UNIXV12

6.6 WindowsWindows 2000CDFSUDFFAT12FAT16FAT32NTFSCDFSCDROM File System1988UDFWindows 2000CDFSUDFUniversal Disk Format1995DVD-ROMCDFSFATFile Allocation TableWindows 2000FATFATWindows 2000512B8KBFAT12122124096FAT1616FAT3232Windows 200032GBFAT21Windows NTNTNTFS (New Technology File System)NTFSNTFSIntelNTFSNTFSNTFSNTFSAtomic transactionEncrypted File System, EFSNTFS

6.6.1 NTFS NTFSFATNTFSNTFS22GB4KBNTFSLogical Cluster Number, LCNVirtual Cluster Number, VCNLCNVCNVCNLCN

1.FATNTFSMaster File Table, MFTFATNTFSmetadataMFTNTFSNTFSNTFSNTFSMFTMFTMFT1KBMFT16$16MFT6-12

6-12 MFT

MFT16NTFS4-22MFTMFT166-22 MFTNTFS12%88%MFTWindowsMFTMFTNTFSMFTNTFS$BootMFTVCNLCNMFTNTFSMFTNTFS

2.NTFS64File Reference Number48MFT16NTFS

3.NTFSUnicodeUnicode16VCNLCNVCNVCNMFTstreamNTFSNTFS/

NTFSMFTNTFS NTFSMFTMFT6-231236-24 MFT6-24

1KBMFTNTFSMFTMFTrunextentMFTNTFS

6-25 6-25NTFSVCN-LCNVCN-LCNMFT6-262VCN 8attribute listMFTVCN-LCNVCNLCN67145214531325132613279 11 \48.4-28 VCNLCN012345135 6 712011202120312337.6-27 1 24 5 6 MFT6-27

NTFS4KB6-28VCNVCN4KB20306-27NTFSB+B+B+NTFSB+6-27NTFSVCNLCNVCN

6.6.2 NTFS Win32 I/O APII/OI/OFSDI/OI/O6-29/I/ONTFS

NTFSNTFSSCBSystem Control BlockSCBSCBFCBFCBNTFS6-30