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ComputerKnowledgeandTechnology：714(20115)LinuxEXT4（，310016）：EXT4，EXT3，WRITEEXT4，Linux。：EXT4；；；i：TP391：A：1009-3044(2011)14-3443-04TheAnalysisofLinuxEXT4FileSystemLUYa-wen(HangzhouVocationalCollegeofScienceandTechnology,Hangzhou310016,China)Abstract:ComparedwithEXT3filesystem,thetheoryanddatastructureofEXT4filesystemwasintroduced.ByanalyzingtheWRITEoperation,theprocedcureofEXT4filesystemwasexplained,andthestudywillsupplysomereferencesforuserswhochoosingcoreofLinux.Keywords:EXT4;dailyrecord;handle;inodeEXT4，100%EXT3，EXT3。，,,、，。EXT4(jbd)[1]，，，NVRAM，EXT4。，EXT4e2fsck,，EXT4EXT3[2]。,EXT4,EXT4,EXT4。1EXT42.6.28。1.1super_block/include/linux/EXT4_fs.hstructEXT4_super_block{/*00*/__le32s_inodes_count;/**/__le32s_blocks_count;/**/__le32s_r_blocks_count;/**/__le32s_free_blocks_count;/**//*10*/__le32s_free_inodes_count;/**/__le32s_first_data_block;/**/__le32s_log_block_size;/**/__le32s_log_frag_size;/**//*20*/__le32s_blocks_per_group;/**/__le32s_frags_per_group;/**/__le32s_inodes_per_group;/*#*/__le32s_mtime;/**/…………/*150*/__le32s_blocks_count_hi;/*32*/__le32s_r_blocks_count_hi;/*32*/__le32s_free_blocks_count_hi;}/*32*/，，。EXT4，e2fsck，，，。：2011-03-25：2009（20071302）：（1978-），，，，，。E-mail:kfyj@cccc.net.cn，34723443ComputerKnowledgeandTechnology：714(20115)，EXT4，EXT3，EXT4。1.2GroupDescriptor，。inode，。，，。structEXT4_group_desc{__le32bg_block_bitmap;/**/__le32bg_inode_bitmap;/**/__le32bg_inode_table;/**/__le16bg_free_blocks_count;/**/__le16bg_free_inodes_count;/**/__le16bg_used_dirs_count;/**/__u16bg_flag;/*32*/__u32bg_reserved[3];__le32bg_block_bitmap_hi;/*32*/__le32bg_inode_bitmap_hi;/*32*/__le32bg_inode_table_hi;};/*32*/1.3istructEXT4_inode{__le16i_mode;/*，*/__le16i_uid;/*id16*/__le32i_size;/**/__le32i_atime;/**/__le32i_ctime;/**/__le32i_mtime;/**/__le32i_dtime;/**/__le16i_gid;/*16*/__le16i_links_count;/**/__le32i_blocks;/*I*/__le32i_flags;/**/union{struct{__le32l_i_reserved1;}linux1;struct{__le32h_i_translator;}hurd1;struct{__le32m_i_reserved1;}masix1;}osd1;/*OSdependent1*/__le32i_block[EXT4_N_BLOCKS];/*，15*/__le32i_generation;/*(forNFS)*/__le32i_file_acl;/*ACL*/__le32i_dir_acl;/*ACL*/__le32i_faddr;/**/union{struct{__le8l_i_frag;/**/__le8l_i_fsize;/**/__le16i_pad1;__le16l_i_uid_high;/*Iid*/__le16l_i_gid_high;/*I*/__le32l_i_reserved2;}linux2;//1struct{__le8h_i_frag;/**/__le8h_i_fsize;/**/3444ComputerKnowledgeandTechnology：714(20115)__le16h_i_mode_high;__le16h_i_uid_high;__le16h_i_gid_high;__le32h_i_author;}hurd2;//struct{__le8m_i_frag;/**/__le8m_i_fsize;/**/__le16m_pad1;__le32m_i_reserved2[2];}masix2;//2}osd2;/*OSdependent2*/__le16i_EXTra_isize;__le16i_pad1;__le32i_ctime_EXTra;/*(nsec2|epoch)*/__le32i_mtime_EXTra;/*(nsec2|epoch)*/__le32i_atime_EXTra;/*(nsec2|epoch)*/__le32i_crtime;/**/__le32i_crtime_EXTra;};/*(nsec2|epoch)*/，，i12，13，14，15，，，。EXT3，EXT4，5，，。1.4i，[3]。2.62.4。i。，。i，。i。，EXT4_truncate，0，。。[4]。，。。structEXT4_inode_info{__le32i_data[15];__le32i_flags;//i#ifdefEXT4_FRAGMENTS__le32i_faddr;//__le8i_frag_no;//__le8i_frag_size;//#endif__le32i_file_acl;__le32i_dir_acl;__le32i_dtime;__le32i_block_group;//i__le32i_state;/*EXT3*/__le32i_nEXT_alloc_block;/*i_nEXT_alloc_block。，，。/*__le32i_nEXT_alloc_goal;/*i_nEXT_alloc_goal。。*/structsemaphoretruncate_sem;//，structinodevfs_inode;/*，EXT4linux*/};1.5handle_tEXT4。structhandle_s3445ComputerKnowledgeandTechnology：714(20115){transaction_t*h_transaction;//inth_buffer_credits;//inth_ref;//inth_err;//structlist_headh_jcb;//unsignedinth_sync:1;/*sync-on-close*/unsignedinth_jdata:1;/**/unsignedinth_aborted:1;/**/};transaction_t。。：*RUNNING:*LOCKED:*RUNDOWN:。*FLUSH:。*COMMIT:，*FINISHED:2EXT42.1EXTstructfile_operationsEXT3_file_operations={.llseek=generic_file_llseek,.read=do_sync_read,.write=do_sync_write,.aio_read=generic_file_aio_read,.aio_write=EXT3_file_write,.readv=generic_file_readv,.writev=generic_file_writev,.ioctl=EXT3_ioctl,.mmap=generic_file_mmap,.open=EXT3_open_file,.release=EXT3_release_file,.fsync=EXT3_sync_file,.sendfile=generic_file_sendfile,};EXT4readdo_sync_read，writedo_sync_write，。EXT4。2.2EXT4，：1。①file-f_op-writeEXT4write，opera-tionwritedo_sync_write。②filp-f_op-aio_writeEXT4aio_write，operationaio_writeEXT4_file_write。LINUXsys_write，sys_writefile，vfs_write，file-f_op-write，EXT3write（do_sync_write）aio_write（EXT4_file_write）。EXT4_file_write2。3LinuxEXT4，EXT4（3472）123446ComputerKnowledgeandTechnology：714(20115)（3446），。，。2.6.28EXT42.4，，Htree（），NTFS。EXT4。：[1],.LINUX[M].：,2002.[2],.Linux2.6()EXT3[J].,2004(6):8-10.[3].Ext—[J].,2010(8):133-136.[4],.Linux[M].：,2006.，，，，。，，。，GPS、IMU/GPS、、；GPSIMU/GPS。，，，，。3.3，，。、、，，，，。，（DLG）（、、DVD-ROM），、、，。（DOM）（DEM），、。，，。4，，，，。，。，，。，，。：[1],,.[M].:,2004.[2].、[J].,1999(2).3472