國嵌參考內(nèi)核知識文件系統(tǒng)fs-htang

靜UNIX系統(tǒng)V文件系Ext2文件動VFS文件靜?文件系統(tǒng)操作—mountrootUNIX系統(tǒng)V文件UNIX系統(tǒng)V文件 文件。當/public為NFS時：dcos3:~dcos3:~#ln-d/public/ln:creatinghardlink`/tmp/pub'to`/public/':Invalidcross-devicelinkUNIX系統(tǒng)V文件 nblocks

保存了本組所有的inode。應node描述文件與 件的存取 修改時間、文件類Block將連續(xù)的block分組。為什么盡量將屬于一個文件的block存放于一組內(nèi)，保證 局部性多少個block兩個決定因素：&blockblockbitmapblockXgroupblock大小2XSuperBlock記錄superblockstructext2_super_block每一個block有多大我有多少Inode？多少block？他們中多少 的多少個block被保留每個blockgroup中，有多少個block？多少個我何時mount？mount了幾次？最多可以mount幾次上一次write操作在何時？上一次check操作在何時}GroupDiscriptorstruct{

bg_block_bitmap;/*Blocksbitmapblock*/bg_inode_bitmap;/*Inodesbitmapblock*/bg_inode_table;/*Inodestableblock*/bg__blocks_count;/*blockscount*/bg__inodes_count;/*inodescount }

/*DirectoriescountInode基本“構件”structext2_inode

文件模式表示文件類型atimectime文件模式表示文件類型atime--文件數(shù)據(jù)的最

AccessControlN ile /*N ile }i_mode01Regular23Character4Block5Named67SymbolicEXT2目 i_block[EXT2_N_BLOCKS];/*Pointerstoblocks#defineEXT2_IND_BLOCK#defineEXT2_DIND_BLOCK#defineEXT2_TIND_BLOCK#defineEXT2_N_BLOCKS

EXT2_NDIR_BLOCKS//12(EXT2_IND_BLOCK+1)//13(EXT2_DIND_BLOCK+1)//14(EXT2_TIND_BLOCK+1)//15度大于60時，將占用一個block來。60 u32 4 i_block15X460Named？VFS文件系

VFSVFSI/O設備動MMVFS↓VFS文件系進程的虛進程的虛擬內(nèi)塊設備緩沖VFS文件系 管理緩沖區(qū)(buffer.響應系統(tǒng)調(diào)用fcntl()和 (fcntl.c&映射名字到索引節(jié)點(namei.c,實現(xiàn)select(函數(shù)(select VFS文件系主要三個進程打

inodeFordisk-basedfilesystems,thisobjectusuallycorrespondstoa

,thisfilecontrolblockstoredon dentry FAT(FileAllocationTable)：

VFSstructVFSstruct}}Objectsuper_blockstructsuper_blockstructsuper_blockstructsuper_blockstructsuper_operations}structsuper_operationsvoid(*read_inode)(structinode*);void(*write_inode)(structinode*,int);void(*delete_inode)(structinode*);}為保證文件系統(tǒng)性能，設備的superblock必須駐留內(nèi)存，整個VFS的superblocksuperblock記錄文件系統(tǒng)的具有共性的信息(如:文件同時，擁有著作用于這些信structsuper_block{structlist_heads_list;structfile_system_type structsuper_block{structlist_heads_list;structfile_system_type unsignedchar structsuper_operations*s_op;structdentry union{….}u；}super_blocksuperblock部分數(shù)據(jù)成員連接多個superblock的雙向文件系統(tǒng)類已修改(臟)的標掛載的dentryobjectsuperblock數(shù)據(jù)成員 superblock數(shù)據(jù)成super_blockstructsuper_blocksuper_blockstruct

structmsdos_sb_info}}superblock函數(shù)成員super_blockstructsuper_blockstructsuper_operationsread_inode(inode)dirty_inode(inode)}從磁 信息填寫inode(內(nèi)存當dirty標志被置位時執(zhí)行刪除inode(磁盤操作同put_inode,同時釋放內(nèi)inodeObjectinodestructinodestructinode_operations}structinodestructinodestructinode_operations}structinode_operations{int(*create)int(*link)int(*mkdir)}VFS的inode對數(shù)據(jù)與操作的實現(xiàn)與superblock相inodestructinodestructntfs_inode_info

struct}}inode函數(shù)成員inodestructinode_operations{create(dir,dentry,mode)lookup(dir,dentry)link(old_dentry,dir,new_dentry)unlink(dir,dentry)symlink(dir,dentry,symname)mkdir(dir,dentry,mode)rename(old_dir,old_dentry,}VFS文件filestructfilefilestructfilestruct }structfile_operations{loff_t(*llseek)ssize_t(*read)ssize_t(*write)}fileObject描述了進fileObject在進程打file數(shù)據(jù)成員

filestructunsignedintfilestructunsignedintf_flags; }filestructfile_operations{llseek(file,offset,origin)read(file,buf,count,offset)filestructfile_operations{llseek(file,offset,origin)read(file,buf,count,offset)write(file,buf,count,offset)readdir(dir,dirent,filldir)poll(file,poll_table)open(inode,file) }

VFS文件dentryObjectdentrystructdentrystructdentry*d_parent;structlist_headd_hash;structlist_headd_lru;structlist_headd_child;structlist_headd_subdirs;}structdentry_operationsdentrystructdentrystructdentry*d_parent;structlist_headd_hash;structlist_headd_lru;structlist_headd_child;structlist_headd_subdirs;}structdentry_operations}一級創(chuàng)建一個dentry/tmptest三個VFS文件structdentry_operationsstructdentry_operations}structdentry{atomic_td_count;structinode*}dentry與文件名對應的VFS文件沒有可用//由調(diào)度程序掌0隨時可能被回In內(nèi)核正在不會被回//VFS文件dentry& structfiles_struct{structfile**structfiles_struct{structfile**fd;}structtask_struct/*openfileinformationstructtask_struct/*openfileinformation*/structfiles_struct*files;}parentprocesschildprocesschildprocessotherprocesscount0countf_inodef_count=1f_inodef_count=20counti_count=2VFS文件系 mountrootmountroot一個空 ，將作為最初的掛載內(nèi)核將真正的root掛載到此 start_kernel(setup_32(start_kernel(setup_32(setup(第一階段-setup(rest_init(rest_init(第一階段-

分配superblockblock

start_kernel(setup_32(start_kernel(setup_3