Figure 1: An Inode B+ tree
Record Field Field Size Description
e_cpos 32 bits Offset into the
file, in clusters
e_clusters 32 bits Clusters in this
extent
e_blkno 64 bits Physical disk
offset
Table 1: OCFS2 extent record
When the extent array is full, the file system
will allocate an extent block to hold the current
array. The first extent record in the inode will
be re-written to point to the newly allocated ex-
tent block. The e_clusters and e_cpos
values will refer to the part of the tree under-
neath that extent. Bottom level extent blocks
form a linked list so that queries accross a range
can be done efficiently.
2.2 Directories
Directory layout in OCFS2 is very similar to
Ext3, though unfortunately, htree has yet to be
ported. The only difference in directory en-
try structure is that OCFS2 inode numbers are
64 bits wide. The rest of this section can be
skipped by those already familiar with the di-
rent structure.
Directory inodes hold their data in the same
manner which file inodes do. Directory data
is arranged into an array of "directory en-
tries". Each directory entry holds a 64-bit inode
pointer, a 16-bit record length, an 8-bit name
length, an 8-bit file type enum (this allows us
to avoid reading the inode block for type) and
of course the set of characters which make up
the file name.
2.3 The Super Block
The OCFS2 super block information is con-
tained within an inode block. It contains a
standard set of super block information - block
size, compat/incompat/ro features, root inode
pointer, etc. There are four values which are
somewhat unique to OCFS2.
• s_clustersize_bits - Cluster size
for the file system.
• s_system_dir_blkno - Pointer to the
system directory.
• s_max_slots - Maximum number of
simultaneous mounts.
• s_first_cluster_group - Block
offset of first cluster group descriptor.
s_clustersize_bits is self explanatory.
The reason for the other three fields will be ex-
plained in the next few sections.
2.4 The System Directory
In OCFS2 file system metadata is contained
within a set of system files. There are two types
of system files - global and node local. All sys-
tem files are linked into the file system via the
hidden system directory
2
whose inode number
is pointed to by the superblock. To find a sys-
tem file, a node need only search the system
directory for the name in question. The most
2
debugfs.ocfs2 can list the system dir with the “ls
//” command.
3
剩余12页未读，继续阅读
辉钟
- 粉丝: 0
- 资源: 9
我的内容管理
展开
最新资源
- Unity UGUI性能优化实战：UGUI_BatchDemo示例
- Java实现小游戏飞翔的小鸟教程分享
- Ant Design 4.16.8：企业级React组件库的最新更新
- Windows下MongoDB的安装教程与步骤
- 婚庆公司响应式网站模板源码下载
- 高端旅行推荐：官网模板及移动响应式网页设计
- Java基础教程：类与接口的实现与应用
- 高级版照片排版软件功能介绍与操作指南
- 精品黑色插画设计师作品展示网页模板
- 蓝色互联网科技企业Bootstrap网站模板下载
- MQTTFX 1.7.1版：Windows平台最强Mqtt客户端体验
- 黑色摄影主题响应式网站模板设计案例
- 扁平化风格商业旅游网站模板设计
- 绿色留学H5模板：科研教育机构官网解决方案
- Linux环境下EMQX安装全流程指导
- 可爱卡通儿童APP官网模板_复古绿色动画设计
资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！
点击此处反馈
