📄 043_fs_filesystem_c.html

📁 重读linux 2.4.2o所写的笔记
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      <pre>2007-3-6   <br><span style=COLOR:#3333ff>自己看吧,就这几行代码. filesytem 的精华并不在这个同名文件中.</span><br><br>#ifdef CONFIG_DEVPTS_FS<br>extern int <span style=COLOR:#000099>init_devpts_fs</span>(void);<br>#endif<br><br>void <span style=COLOR:#000099>__init filesystem_setup</span>(void)<br>{<br>	<span style=COLOR:#006600>init_devfs_fs</span>();  /*  Header file may make this empty  */<br><br>#ifdef CONFIG_NFS_FS<br>	<span style=COLOR:#009900>init_nfs_fs</span>();<br>#endif<br><br>#ifdef CONFIG_DEVPTS_FS<br>	<span style=COLOR:#009900>init_devpts_fs</span>();<br>#endif<br>}<br><br>#if defined(CONFIG_NFSD_MODULE)<br>struct nfsd_linkage *nfsd_linkage = NULL;<br><br>long<br><span style=COLOR:#cc0000>asmlinkage</span> <span style=COLOR:#000099>sys_nfsservctl</span>(int cmd, void *argp, void *resp)<br>{<br>	int ret = -ENOSYS;<br>	<br>	lock_kernel();<br><br>	if (nfsd_linkage ||<br>	    (request_module ("nfsd") == 0 &amp;&amp; nfsd_linkage))<br>		ret = <span style=COLOR:#009900>nfsd_linkage-&gt;do_nfsservctl</span>(cmd, argp, resp);<br><br>	unlock_kernel();<br>	return ret;<br>}<br>EXPORT_SYMBOL(nfsd_linkage);<br><br>#elif ! defined (CONFIG_NFSD)<br>asmlinkage int <span style=COLOR:#000099>sys_nfsservctl</span>(int cmd, void *argp, void *resp)<br>{<br>	return -ENOSYS;<br>}<br>#endif /* CONFIG_NFSD */<br><br><br>倒是吧fs type列到这里吧,就像人走过的时候顺笔写上, xxx到此一游.<br>struct <font color=#000099><b>file_system_type</b></font> {<br>	const char *<font color=#000099><b>name</b></font>;<br>	int <font color=#000099><b>fs_flags</b></font>;<br>	struct <font color=#006600>super_block</font> *(*<font color=#006600><b>read_super</b></font>) (struct super_block *, void *, int);<br>	struct <font color=#006600>module </font>*<b>owner</b>;<br>	struct <font color=#006600>vfsmount </font>*<b>kern_mnt</b>; /* For kernel mount, if it's FS_SINGLE fs */<br>	struct <font color=#006600>file_system_type</font> * <b>next</b>;<br>};<br><br>#define <font color=#000099><b>DECLARE_FSTYPE</b></font>(var,type,read,flags) \<br>struct <font color=#006600>file_system_type</font> var = { \<br>	name:		type, \<br>	read_super:	read, \<br>	fs_flags:	flags, \<br>	owner:		<font color=#cc0000>THIS_MODULE</font>, \<br>}<br><br>#define <font color=#000099><b>DECLARE_FSTYPE_DEV</b></font>(var,type,read) \<br>	DECLARE_FSTYPE(var,type,read,<font color=#cc0000>FS_REQUIRES_DEV</font>)<br><br>read_super,是一个文件系统的开始.里边有这个文件系统的根,s_root. mount的时候,才需要做这个动作. do_mount(kern_mount)<br>+read_super构建一颗由vfsmount链接起来的dentry-&gt;mnt-&gt;dentry(root)混合树...<br><br>   由vfsmount, dentry 组成的这棵数, 加上file-&gt;dentry&lt;--&gt;inode&lt;--&gt;super&lt;fs_system_type 所形成的复杂的"网状"结构, 是整个<br>VFS的"组织结构".而组织结构最大的作用,就是互相方便的引用,查找. 同时也提供给user一个以字符串为媒介的接口"path".<br>   光是这庞大的组织,就占去了vfsmount,dentry,inode,super不少的"经费"(空间).然后依附于每个个体,都有一组feature:功能性<br>featrue+底层接口虚拟化.<br>   VFS在这个组织之上,依赖于这些feature,构筑整个VFS的实现,向上提供给user文件系统的统一操作,向下,有一组"标准"接口,可以方便<br>的实现具体的文件系统.<br>struct <font color=#000099><b>file_system_type</b></font> {<br>	const char *<font color=#000099><b>name</b></font>;   <font color=#ff0000><b>/*feature*/</b></font><br>	int <font color=#000099><b>fs_flags</b></font>;       <font color=#cc0000><b>/*feature*/	</b></font><br>        struct <font color=#006600>super_block</font> *(*<font color=#006600><b>read_super</b></font>) (struct super_block *, void *, int); <font color=#ff0000><b>/*featue虚拟化接口*/</b></font><br>	struct <font color=#006600>module </font>*<b>owner</b>;  <font color=#cc0000><b>/*组织*/</b></font><br>	struct <font color=#006600>vfsmount </font>*<b>kern_mnt</b>; <font color=#cc0000><b>/*组织*/	</b></font><br>        struct <font color=#006600>file_system_type</font> * <b>next</b>; <font color=#cc0000><b>/*组织*/</b></font><br>};<br><br>    <br><br><br></pre>
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