{"id":4389,"date":"2014-02-25T20:54:55","date_gmt":"2014-02-25T12:54:55","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=4389"},"modified":"2014-02-26T18:53:21","modified_gmt":"2014-02-26T10:53:21","slug":"linux%e5%86%85%e6%a0%b8%e6%96%87%e4%bb%b6%e7%b3%bb%e7%bb%9f%e6%8c%82%e8%bd%bd%e5%88%86%e6%9e%90","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/4389","title":{"rendered":"Linux\u5185\u6838\u6587\u4ef6\u7cfb\u7edf\u6302\u8f7d\u5206\u6790"},"content":{"rendered":"

\u672c\u6587\u5c06\u9488\u5bf9\u5185\u6838\u7248\u672c3.2.0\u4e2d\u7684mount\u7cfb\u7edf\u8c03\u7528\u5b9e\u73b0\u8fc7\u7a0b\u8fdb\u884c\u7b80\u5355\u8bf4\u660e\u3002<\/p>\n

1.\u6570\u636e\u7ed3\u6784<\/h2>\n

\u4e0b\u9762\u5c06\u5bf9\u6587\u4ef6\u7cfb\u7edf\u6302\u8f7d\u8fc7\u7a0b\u4e2d\u6d89\u53ca\u5230\u7684\u4e24\u4e2a\u4e3b\u8981\u6570\u636e\u7ed3\u6784vfsmount\u548cpath\u8fdb\u884c\u8282\u672c\u8bf4\u660e\u3002<\/p>\n

1.1 struct vfsmount<\/strong><\/p>\n

\u6bcf\u4e2a\u6302\u8f7d\u5728\u5185\u6838\u76ee\u5f55\u6811\u4e2d\u7684\u6587\u4ef6\u7cfb\u7edf\u90fd\u5c06\u5bf9\u5e94\u4e00\u4e2avfsmount\u7ed3\u6784\uff0c\u4e0b\u9762\u5c06\u5bf9\u8be5\u7ed3\u6784\u4e2d\u7684\u90e8\u5206\u5b57\u6bb5\u8fdb\u884c\u8bf4\u660e\u3002\u5047\u8bbe\u8bbe\u5907\/dev\/sdc\u4e3antfs\u6587\u4ef6\u7cfb\u7edf\uff0c\u73b0\u9700\u8981\u5c06\u5176\u6302\u8f7d\u5728\u6587\u4ef6\u7cfb\u7edf\u4e3aext3\u7684\/home\/edsionte\/work\u4e0b\u3002\u56e0\u6b64\uff0c\/home\/edsionte\/work\u53ef\u4ee5\u88ab\u79f0\u4e3antfs\u6587\u4ef6\u7cfb\u7edf\u7684\u6302\u8f7d\u70b9\uff0c\u5e76\u4e14\u79f0ntfs\u6587\u4ef6\u7cfb\u7edf\u4e0eext3\u6587\u4ef6\u7cfb\u7edf\u5f62\u6210\u7236\u5b50\u6587\u4ef6\u6587\u4ef6\u7cfb\u7edf\u5173\u7cfb\u3002\u540c\u65f6ntfs\u4e5f\u53ef\u79f0\u4e3a\u6e90\u6587\u4ef6\u7cfb\u7edf\uff0c\u800cext3\u4e5f\u53ef\u79f0\u4e3a\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u3002<\/p>\n

struct list_head mnt_hash;<\/p>\n

\u5185\u6838\u5c06\u7cfb\u7edf\u5185\u6240\u6709\u5df2\u6302\u8f7d\u7684\u6587\u4ef6\u7cfb\u7edf\u901a\u8fc7\u6563\u5217\u8868\u7684\u5f62\u5f0f\u8fdb\u884c\u7ec4\u7ec7\uff0c\u6bcf\u4e2avfsmount\u5c06\u5904\u4e8e\u5176\u5bf9\u5e94\u54c8\u5e0c\u503c\u7684\u51b2\u7a81\u94fe\u8868\u5f53\u4e2d\u3002mnt_hash\u5b57\u6bb5\u5219\u4e3a\u5177\u4f53\u51b2\u7a81\u94fe\u8868\u7684\u5143\u7d20\u3002<\/p>\n

struct list_head mnt_mounts;<\/p>\n

\u5982\u679c\u5f53\u524d\u6587\u4ef6\u7cfb\u7edf\u4e0b\u6302\u8f7d\u4e86\u5176\u4ed6\u7684\u5b50\u6587\u4ef6\u7cfb\u7edf\uff0c\u90a3\u4e48\u8fd9\u4e9b\u5b50\u6587\u4ef6\u7cfb\u7edf\u5c06\u901a\u8fc7\u81ea\u8eabvfsmount\u4e2d\u7684mnt_child\u5b57\u6bb5\u7ec4\u6210\u4e00\u4e2a\u94fe\u8868\uff0c\u8be5\u94fe\u8868\u5934\u4e3a\u7236\u6587\u4ef6\u7cfb\u7edf\u4e2d\u7684mnt_mounts\u5b57\u6bb5\u3002<\/p>\n

struct list_head mnt_child;<\/p>\n

\u5f53\u524d\u6587\u4ef6\u7cfb\u7edf\u5c06\u901a\u8fc7\u8be5\u5b57\u6bb5\u4e0e\u5176\u4ed6\u7236\u6587\u4ef6\u7cfb\u7edf\u4e0b\u7684\u5b50\u6587\u4ef6\u7cfb\u7edf\u7ec4\u6210\u4e00\u4e2a\u94fe\u8868\u3002<\/p>\n

struct vfsmount *mnt_parent;<\/p>\n

\u8be5\u5b57\u6bb5\u6307\u5411\u7236\u6587\u4ef6\u7cfb\u7edf\u5bf9\u5e94\u7684vfsmount\u7ed3\u6784\u3002\u5373\u6307\u5411ext3\u6587\u4ef6\u7cfb\u7edf\u5bf9\u5e94\u7684vfsmount\u7ed3\u6784\u3002<\/p>\n

struct dentry *mnt_mountpoint;<\/p>\n

\u8be5\u5b57\u6bb5\u8868\u793a\u6e90\u6587\u4ef6\u7cfb\u7edf\u5728\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u4e2d\u6302\u8f7d\u70b9\u5bf9\u5e94\u7684dentry\u7ed3\u6784\u3002\/home\/edsionte\/work\u4e3a\u6302\u8f7d\u70b9\uff0c\u5219\u8be5\u5b57\u6bb5\u6307\u5411\u76ee\u5f55\u9879work\u3002<\/p>\n

struct dentry *mnt_root;<\/p>\n

\u6307\u5411\u5f53\u524d\u6587\u4ef6\u7cfb\u7edf\u7684\u6839\u76ee\u5f55\u9879\u3002\u5bf9\u4e8e\u6e90\u6587\u4ef6\u7cfb\u7edfntfs\u6765\u8bf4\uff0c\u6839\u76ee\u5f55\u9879\u76f8\u5bf9\u4e3a\/\uff0c\u4f46\u5728\u6574\u4e2a\u7cfb\u7edf\u76ee\u5f55\u6811\u4e2d\uff0c\u6839\u76ee\u5f55\u9879\u4e3awork\u3002<\/p>\n

struct super_block *mnt_sb;<\/p>\n

\u6bcf\u4e2a\u6587\u4ef6\u7cfb\u7edf\u90fd\u5c06\u5bf9\u5e94\u4e00\u4e2asuper_block\u7ed3\u6784\uff0c\u8be5\u5b57\u6bb5\u6307\u5411\/dev\/sdc\u8bbe\u5907\u4e0a\u6587\u4ef6\u7cfb\u7edf\u5bf9\u5e94\u7684\u8d85\u7ea7\u5757\u3002<\/p>\n

struct list_head mnt_list;<\/p>\n

\u6240\u6709\u5904\u4e8e\u4e00\u4e2a\u540d\u5b57\u7a7a\u95f4\u7684\u6587\u4ef6\u7cfb\u7edf\u901a\u8fc7mnt_list\u5b57\u6bb5\u94fe\u63a5\u5728\u4e00\u8d77\uff0c\u800c\u8be5\u94fe\u8868\u7684\u8868\u5934\u4e3a\u8be5\u540d\u5b57\u7a7a\u95f4\u7ed3\u6784\u4e2d\u7684list\u5b57\u6bb5\u3002<\/p>\n

struct mnt_namespace *mnt_ns;<\/p>\n

\u8be5\u5b57\u6bb5\u8868\u793a\u5f53\u524dvfsmount\u6240\u5bf9\u5e94\u7684\u540d\u5b57\u7a7a\u95f4\u7ed3\u6784\u3002<\/p>\n

1.2 struct path<\/strong><\/p>\n

path\u7ed3\u6784\u7531vfsmount\u7ed3\u6784\u548cdentry\u7ed3\u6784\u7ec4\u6210\u3002\u8be5\u7ed3\u6784\u5728\u6302\u8f7d\u6587\u4ef6\u7cfb\u7edf\u65f6\u8868\u793a\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u7684vfsmount\u7ed3\u6784\u548c\u6302\u8f7d\u70b9dentry\u3002<\/p>\n

2.\u51fd\u6570\u8c03\u7528\u5173\u7cfb\u56fe<\/h2>\n

\"do_mount\"<\/a><\/h2>\n

3.\u5b9e\u73b0<\/h2>\n

3.1 mount\u7cfb\u7edf\u8c03\u7528\u670d\u52a1\u4f8b\u7a0b<\/strong><\/p>\n

mount()\u7cfb\u7edf\u8c03\u7528\u670d\u52a1\u4f8b\u7a0b\u4e3a\uff1a<\/p>\n

SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, char __user *, type, unsigned long, flags, void __user *, data)<\/p>\n

\u5176\u5185\u90e8\u5b9e\u73b0\u4e3b\u8981\u662f\u5c06\u7528\u6237\u6001\u7684\u53c2\u6570\u4f9d\u6b21\u590d\u5236\u5230\u5185\u6838\u6001\uff0c\u63a5\u7740\u8c03\u7528\u5185\u6838\u51fd\u6570do_mount()\u3002<\/p>\n

3.2 do_mount()<\/strong><\/p>\n

\u8be5\u51fd\u6570\u5185\u90e8\u9996\u5148\u901a\u8fc7kern_path()\u83b7\u53d6\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u7684path\u7ed3\u6784\uff0c\u5373\u6302\u8f7d\u70b9\u76ee\u5f55\u9879\u4ee5\u53ca\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u7684vfsmount\u7ed3\u6784\uff1b\u63a5\u7740\uff0c\u901a\u8fc7\u68c0\u67e5flags\u5bf9\u6302\u8f7d\u64cd\u4f5c\u8fdb\u884c\u4e0d\u540c\u76ee\u7684\u7684\u5206\u53d1\u3002\u8fd9\u91cc\u6211\u4eec\u53ea\u8ba8\u8bba\u6700\u666e\u901a\u7684\u60c5\u5f62\uff0c\u5373\u5c06\u4e00\u4e2a\u6587\u4ef6\u7cfb\u7edf\u6302\u8f7d\u5728\u4e00\u4e2a\u65b0\u7684\u6302\u8f7d\u70b9\u4e2d\uff0c\u8fd9\u79cd\u60c5\u51b5\u8c03\u7528do_new_mount()\u3002<\/p>\n

3.3 do_new_mount()<\/strong><\/p>\n

\u8fd9\u4e2a\u51fd\u6570\u63cf\u8ff0\u7684\u662f\u6302\u8f7d\u4e00\u4e2a\u65b0\u6587\u4ef6\u7cfb\u7edf\u6700\u666e\u904d\u7684\u60c5\u5f62\uff0c\u4e3b\u8981\u5305\u62ec\u4ee5\u4e0b\u51e0\u70b9\uff1a<\/p>\n

1.\u6587\u4ef6\u7cfb\u7edf\u7c7b\u578b\u3001\u64cd\u7eb5\u6743\u9650\u68c0\u67e5\u7b49\uff1b<\/p>\n

2.\u901a\u8fc7do_kern_mount()\u83b7\u53d6\u6e90\u6587\u4ef6\u7cfb\u7edf\u7684vfsmount\u7ed3\u6784\uff1b<\/p>\n

3.\u901a\u8fc7do_add_mount()\u5c06\u6e90\u6587\u4ef6\u7cfb\u7edf\u589e\u52a0\u5230\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u4e2d\uff1b<\/p>\n

3.4 do_add_mount()<\/strong><\/p>\n

1.flags\u53c2\u6570\u5408\u6cd5\u6027\u68c0\u67e5\uff1b<\/p>\n

2.\u68c0\u67e5\u6307\u5b9a\u7684\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u662f\u5426\u4e3a\u5f53\u524d\u6587\u4ef6\u7cfb\u7edf\u3002\u5982\u679c\u662f\uff0c\u5219\u5931\u8d25\uff1b<\/p>\n

3.\u68c0\u67e5\u6e90\u6587\u4ef6\u7cfb\u7edf\u7684\u6839inode\u662f\u5426\u4e3a\u94fe\u63a5\u6587\u4ef6\u3002\u5982\u679c\u662f\uff0c\u5219\u5931\u8d25\uff1b<\/p>\n

4.\u901a\u8fc7graft_tree()\u5c06\u6e90\u6587\u4ef6\u7cfb\u7edf\u88c5\u8f7d\u5230\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u4e2d\u3002\u5176\u5185\u90e8graft\u53c8\u5c01\u88c5\u4e86attach_recursive_mnt()\uff1b<\/p>\n

3.5 attach_recursive_mnt()<\/strong><\/p>\n

\u8be5\u51fd\u6570\u7684\u4e3b\u8981\u4f5c\u7528\u662f\u8bbe\u7f6e\u7236\u5b50\u6587\u4ef6\u7cfb\u7edf\u7684\u6620\u5c04\u5173\u7cfb\u3002\u5177\u4f53\u64cd\u4f5c\u4e3a\uff1a<\/p>\n

1.\u901a\u8fc7mnt_set_mountpoint()\u5c06\u5b50vfsmount\u4e2d\u7684mnt_parent\u6307\u5411\u7236vfsmount\uff0c\u5c06\u5b50vfsmount\u7684mnt_mountpoint\u6307\u5411\u4f4d\u4e8e\u7236\u6587\u4ef6\u7cfb\u7edf\u4e2d\u7684\u6302\u8f7d\u70b9dentry\uff1b<\/p>\n

2.\u901a\u8fc7commit_tree()\u5c06\u5b50\u6587\u4ef6\u7cfb\u7edf\u6dfb\u52a0\u5230\u5185\u6838\u7684\u6587\u4ef6\u7cfb\u7edf\u54c8\u5e0c\u8868\u4e2d\uff0c\u5e76\u5c06\u5b50\u6587\u4ef6\u7cfb\u7edf\u6dfb\u52a0\u5230\u7236\u6587\u4ef6\u7cfb\u7edf\u5bf9\u5e94\u7684\u5b50\u6587\u4ef6\u7cfb\u7edf\u94fe\u8868\u4e2d\uff1b<\/p>\n

3.6 commit_tree()<\/strong><\/p>\n

1.\u5c06\u5f53\u524d\u6587\u4ef6\u7cfb\u7edf\u7684\u540d\u5b57\u7a7a\u95f4\u8bbe\u7f6e\u4e3a\u7236\u540d\u5b57\u7a7a\u95f4\uff0c\u7236vfsmount\u901a\u8fc7\u5f53\u524dvfsmount\u4e2d\u7684mnt_parent\u83b7\u53d6\uff1b\u518d\u5c06\u5176\u8fde\u63a5\u5230\u7236\u540d\u5b57\u7a7a\u95f4\u94fe\u8868\u4e2d\u3002<\/p>\n

2.\u5c06\u5f53\u524dvfsmount\u52a0\u5165\u5230\u5bf9\u5e94\u54c8\u5e0c\u503c\u7684\u51b2\u7a81\u94fe\u8868\u5f53\u4e2d,\u54c8\u5e0c\u503c\u901a\u8fc7hash()\u8ba1\u7b97\u3002\u5176\u4e2d\uff0cmnt_hash\u4f5c\u4e3a\u94fe\u8868\u5143\u7d20\u3002<\/p>\n

3.\u5c06\u5f53\u524dvfsmount\u52a0\u5165\u5230\u7236vfsmount\u5bf9\u5e94\u7684\u5b50\u6587\u4ef6\u7cfb\u7edf\u94fe\u8868mnt_mounts\u4e2d\u3002\u5176\u4e2d\uff0cmnt_child\u4f5c\u4e3a\u94fe\u8868\u5143\u7d20\u3002<\/p>\n

\u4ece\u6574\u4e2a\u6302\u8f7d\u7684\u5904\u7406\u6d41\u7a0b\u4e0a\u770b\uff0c\u6302\u8f7d\u7684\u672c\u8d28\u5c31\u662f\u5c06\u6e90\u6587\u4ef6\u7cfb\u7edf\u7684vfsmount\u7ed3\u6784\u8fde\u63a5\u5230\u76ee\u7684\u6587\u4ef6\u7cfb\u7edf\u5bf9\u5e94\u7684vfsmount\u7ed3\u6784\u4e2d\uff0c\u5373\u5177\u4f53\u6d89\u53ca\u5230\u4e24\u4e2avfsmount\u4e2d\u5b57\u6bb5\u7684\u6307\u5411\u95ee\u9898\u3002\u4e24\u4e2avfsmount\u5177\u4f53\u7236\u5b50\u7b49\u7ea7\u5173\u7cfb\uff0c\u8fd9\u4e5f\u5bf9\u5e94\u7740\u5185\u6838\u4e2d\u76ee\u5f55\u6811\u7684\u7236\u5b50\u7b49\u7ea7\u5173\u7cfb\u3002<\/p>\n

\u53c2\u8003\u8d44\u6599\uff1a<\/strong><\/p>\n

1.\u6df1\u5165\u7406\u89e3Linux\u5185\u6838\uff1ahttp:\/\/book.douban.com\/subject\/2287506\/\uff1b<\/strong><\/p>\n

2.\u6df1\u5165Linux\u5185\u6838\u67b6\u6784\uff1ahttp:\/\/book.douban.com\/subject\/4843567\/\uff1b<\/strong><\/p>\n

3.Linux\u5185\u6838\u63a2\u79d8\uff1ahttp:\/\/book.douban.com\/subject\/25817503\/\uff1b<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

\u672c\u6587\u5c06\u9488\u5bf9\u5185\u6838\u7248\u672c3.2.0\u4e2d\u7684mount\u7cfb\u7edf\u8c03\u7528\u5b9e\u73b0\u8fc7\u7a0b\u8fdb\u884c\u7b80\u5355\u8bf4\u660e\u3002 1.\u6570\u636e\u7ed3\u6784 \u4e0b\u9762\u5c06\u5bf9\u6587\u4ef6\u7cfb\u7edf\u6302\u8f7d\u8fc7 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[110,175],"tags":[381,181,380,404],"class_list":["post-4389","post","type-post","status-publish","format-standard","hentry","category-linux","category-175","tag-mount","tag-181","tag-380","tag-404"],"views":17468,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/4389","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=4389"}],"version-history":[{"count":12,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/4389\/revisions"}],"predecessor-version":[{"id":4404,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/4389\/revisions\/4404"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=4389"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=4389"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=4389"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}