{"id":208383,"date":"2025-08-26T10:24:31","date_gmt":"2025-08-26T02:24:31","guid":{"rendered":"https:\/\/www.server.hk\/blog\/?p=208383"},"modified":"2025-08-26T10:24:31","modified_gmt":"2025-08-26T02:24:31","slug":"%e6%b7%b1%e5%85%a5%e7%90%86%e8%a7%a3linux%e6%96%87%e4%bb%b6%e7%b3%bb%e7%bb%9f%ef%bc%9aext4%e4%b8%8e%e5%86%85%e6%a0%b8%e6%93%8d%e4%bd%9c%e7%9a%84%e5%85%a8%e9%9d%a2%e6%8c%87%e5%8d%97","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/208383\/","title":{"rendered":"\u6df1\u5165\u7406\u89e3Linux\u6587\u4ef6\u7cfb\u7edf\uff1aEXT4\u4e0e\u5185\u6838\u64cd\u4f5c\u7684\u5168\u9762\u6307\u5357"},"content":{"rendered":"<p>Linux\u6587\u4ef6\u7cfb\u7edf\u662f\u64cd\u4f5c\u7cfb\u7edf\u7684\u6838\u5fc3\u7ec4\u6210\u90e8\u5206\uff0c\u4e3a\u6570\u636e\u7684\u5b58\u50a8\u3001\u7ec4\u7ec7\u548c\u8bbf\u95ee\u63d0\u4f9b\u4e86\u4e00\u79cd\u7ed3\u6784\u5316\u7684\u65b9\u5f0f\u3002\u672c\u6587\u6df1\u5165\u63a2\u8ba8\u4e86EXT4\u6587\u4ef6\u7cfb\u7edf\u7684\u7ed3\u6784\u4ee5\u53caLinux\u5185\u6838\u5982\u4f55\u7ba1\u7406\u6587\u4ef6\u64cd\u4f5c\uff0c\u6ce8\u91cd\u6280\u672f\u51c6\u786e\u6027\u548c\u5bf9IT\u4e13\u4e1a\u4eba\u58eb\u53ca\u5f00\u53d1\u8005\u7684\u5b9e\u7528\u89c1\u89e3\u3002\u65e0\u8bba\u60a8\u662f\u4f18\u5316\u5b58\u50a8\u8fd8\u662f\u6392\u67e5\u6027\u80fd\u95ee\u9898\uff0c\u672c\u6307\u5357\u90fd\u63d0\u4f9b\u4e86\u6e05\u6670\u4e14\u8be6\u7ec6\u7684\u6982\u8ff0\u3002<\/p>\n<h2>Linux\u6587\u4ef6\u7cfb\u7edf\u7684\u6838\u5fc3\u7279\u6027<\/h2>\n<p>Linux\u6587\u4ef6\u7cfb\u7edf\u65e8\u5728\u5e73\u8861\u6027\u80fd\u3001\u53ef\u9760\u6027\u548c\u7075\u6d3b\u6027\u3002\u5176\u4e3b\u8981\u7279\u6027\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><strong>\u57fa\u4e8e\u5757\u7684\u5b58\u50a8<\/strong>\uff1a\u6587\u4ef6\u4ee5\u56fa\u5b9a\u5927\u5c0f\u7684\u5757\uff08\u901a\u5e38\u4e3a4KB\uff09\u5b58\u50a8\uff0c\u6709\u6548\u5229\u7528\u78c1\u76d8\u7a7a\u95f4\u3002<\/li>\n<li><strong>\u7d22\u5f15\u8282\u70b9\uff08Inode\uff09<\/strong>\uff1a\u6bcf\u4e2a\u6587\u4ef6\u6216\u76ee\u5f55\u4e0e\u4e00\u4e2a\u7d22\u5f15\u8282\u70b9\uff08inode\uff09\u76f8\u5173\u8054\uff0c\u7528\u4e8e\u8ddf\u8e2a\u5143\u6570\u636e\u548c\u5757\u4f4d\u7f6e\u3002<\/li>\n<li><strong>\u7f13\u5b58\u5c42<\/strong>\uff1a\u7ecf\u5e38\u8bbf\u95ee\u7684\u6587\u4ef6\u4f1a\u88ab\u7f13\u5b58\u5230\u5185\u5b58\u4e2d\uff0c\u4ee5\u51cf\u5c11\u78c1\u76d8I\/O\u5e76\u63d0\u5347\u6027\u80fd\u3002<\/li>\n<li><strong>\u5c42\u6b21\u7ed3\u6784\u7ec4\u7ec7<\/strong>\uff1a\u6587\u4ef6\u901a\u8fc7\u76ee\u5f55\u7ec4\u7ec7\uff0c\u4fbf\u4e8e\u7ba1\u7406\u548c\u67e5\u8be2\u3002<\/li>\n<li><strong>\u8fdb\u7a0b\u8ddf\u8e2a<\/strong>\uff1a\u5185\u6838\u7ef4\u62a4\u6570\u636e\u7ed3\u6784\uff0c\u8bb0\u5f55\u54ea\u4e9b\u8fdb\u7a0b\u6b63\u5728\u8bbf\u95ee\u54ea\u4e9b\u6587\u4ef6\u3002<\/li>\n<\/ul>\n<p>\u8fd9\u4e9b\u7279\u6027\u786e\u4fddLinux\u6587\u4ef6\u7cfb\u7edf\u80fd\u591f\u7a33\u5065\u5730\u5e94\u5bf9\u591a\u6837\u5316\u7684\u5de5\u4f5c\u8d1f\u8f7d\u3002<\/p>\n<h2>EXT4\u6587\u4ef6\u7cfb\u7edf\u7ed3\u6784<\/h2>\n<p>EXT4\u6587\u4ef6\u7cfb\u7edf\u662fEXT2\u548cEXT3\u7684\u8fdb\u5316\u7248\u672c\uff0c\u56e0\u5176\u9ad8\u6027\u80fd\u548c\u53ef\u9760\u6027\u5728Linux\u53d1\u884c\u7248\u4e2d\u5e7f\u6cdb\u4f7f\u7528\u3002\u4ee5\u4e0b\u6211\u4eec\u5c06\u63a2\u8ba8\u5176\u6838\u5fc3\u7ec4\u4ef6\uff1a\u7d22\u5f15\u8282\u70b9\u3001\u6570\u636e\u5757\u3001\u6269\u5c55\u533a\uff08extents\uff09\u548c\u4f4d\u56fe\u3002<\/p>\n<h3>\u7d22\u5f15\u8282\u70b9\u4e0e\u6570\u636e\u5757<\/h3>\n<p>\u5728EXT4\u4e2d\uff0c\u78c1\u76d8\u88ab\u5212\u5206\u4e3a\u56fa\u5b9a\u5927\u5c0f\u7684\u5757\uff08\u9ed8\u8ba44KB\uff0c\u683c\u5f0f\u5316\u65f6\u53ef\u914d\u7f6e\uff09\u3002\u6587\u4ef6\u88ab\u5206\u5272\u6210\u8fd9\u4e9b\u5757\u8fdb\u884c\u5b58\u50a8\uff0c\u5141\u8bb8\u7075\u6d3b\u5206\u914d\u800c\u65e0\u9700\u8fde\u7eed\u7a7a\u95f4\u3002\u6bcf\u4e2a\u6587\u4ef6\u6216\u76ee\u5f55\u7531\u4e00\u4e2a**\u7d22\u5f15\u8282\u70b9\uff08inode\uff09**\u8868\u793a\uff0c\u5176\u5305\u542b\u4ee5\u4e0b\u5143\u6570\u636e\uff1a<\/p>\n<ul>\n<li>\u6587\u4ef6\u6743\u9650\uff08<code>i_mode<\/code>\uff09<\/li>\n<li>\u6240\u6709\u8005\u548c\u7ec4ID\uff08<code>i_uid<\/code>, <code>i_gid<\/code>\uff09<\/li>\n<li>\u6587\u4ef6\u5927\u5c0f\uff08<code>i_size_lo<\/code>, <code>i_size_high<\/code>\uff09<\/li>\n<li>\u65f6\u95f4\u6233\uff08<code>i_atime<\/code>\u8868\u793a\u6700\u8fd1\u8bbf\u95ee\u65f6\u95f4\uff0c<code>i_mtime<\/code>\u8868\u793a\u6700\u8fd1\u4fee\u6539\u65f6\u95f4\uff0c<code>i_ctime<\/code>\u8868\u793a\u7d22\u5f15\u8282\u70b9\u6700\u8fd1\u66f4\u6539\u65f6\u95f4\uff0c<code>i_dtime<\/code>\u8868\u793a\u5220\u9664\u65f6\u95f4\uff09<\/li>\n<li>\u5757\u6307\u9488\uff08<code>i_block<\/code>\uff09<\/li>\n<\/ul>\n<p>\u7d22\u5f15\u8282\u70b9\u7ed3\u6784\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-c\">struct ext4_inode {\r\n    __le16  i_mode;         \/* \u6587\u4ef6\u6a21\u5f0f *\/\r\n    __le16  i_uid;          \/* \u6240\u6709\u8005UID\u4f4e16\u4f4d *\/\r\n    __le32  i_size_lo;      \/* \u6587\u4ef6\u5927\u5c0f\uff08\u5b57\u8282\uff09 *\/\r\n    __le32  i_atime;        \/* \u8bbf\u95ee\u65f6\u95f4 *\/\r\n    __le32  i_ctime;        \/* \u7d22\u5f15\u8282\u70b9\u66f4\u6539\u65f6\u95f4 *\/\r\n    __le32  i_mtime;        \/* \u6587\u4ef6\u4fee\u6539\u65f6\u95f4 *\/\r\n    __le32  i_dtime;        \/* \u5220\u9664\u65f6\u95f4 *\/\r\n    __le16  i_gid;          \/* \u7ec4ID\u4f4e16\u4f4d *\/\r\n    __le16  i_links_count;  \/* \u94fe\u63a5\u8ba1\u6570 *\/\r\n    __le32  i_blocks_lo;    \/* \u5757\u8ba1\u6570 *\/\r\n    __le32  i_flags;        \/* \u6587\u4ef6\u6807\u5fd7 *\/\r\n    __le32  i_block[15];    \/* \u6570\u636e\u5757\u6307\u9488 *\/\r\n    __le32  i_generation;   \/* \u6587\u4ef6\u7248\u672c\uff08\u7528\u4e8eNFS\uff09 *\/\r\n    __le32  i_file_acl_lo;  \/* \u6587\u4ef6ACL *\/\r\n    __le32  i_size_high;    \/* \u6587\u4ef6\u5927\u5c0f\u9ad832\u4f4d *\/\r\n    ...\r\n};\r\n<\/code><\/pre>\n<p>\u5728EXT2\/EXT3\u4e2d\uff0c<code>i_block<\/code>\u6570\u7ec4\u76f4\u63a5\u6307\u5411\u5c0f\u6587\u4ef6\u7684\u6570\u636e\u5757\uff08\u6700\u591a12\u4e2a\u5757\uff09\u3002\u5bf9\u4e8e\u5927\u6587\u4ef6\uff0c\u4f7f\u7528<strong>\u95f4\u63a5\u5757<\/strong>\uff1a<\/p>\n<ul>\n<li><strong>\u76f4\u63a5\u5757<\/strong>\uff1a<code>i_block[0-11]<\/code>\u76f4\u63a5\u6307\u5411\u6570\u636e\u5757\u3002<\/li>\n<li><strong>\u5355\u95f4\u63a5\u5757<\/strong>\uff1a<code>i_block[12]<\/code>\u6307\u5411\u5305\u542b\u6570\u636e\u5757\u5730\u5740\u7684\u5757\u3002<\/li>\n<li><strong>\u53cc\u95f4\u63a5\u5757<\/strong>\uff1a<code>i_block[13]<\/code>\u6307\u5411\u5305\u542b\u95f4\u63a5\u5757\u5730\u5740\u7684\u5757\u3002<\/li>\n<li><strong>\u4e09\u95f4\u63a5\u5757<\/strong>\uff1a<code>i_block[14]<\/code>\u8fdb\u4e00\u6b65\u6269\u5c55\u4ee5\u652f\u6301\u8d85\u5927\u6587\u4ef6\u3002<\/li>\n<\/ul>\n<p>\u8fd9\u79cd\u65b9\u5f0f\u867d\u7136\u7075\u6d3b\uff0c\u4f46\u5bf9\u4e8e\u5927\u6587\u4ef6\uff0c\u591a\u6b21\u78c1\u76d8\u8bfb\u53d6\u53ef\u80fd\u5bfc\u81f4\u6027\u80fd\u4e0b\u964d\u3002<\/p>\n<h3>EXT4\u4e2d\u7684\u6269\u5c55\u533a\uff08Extents\uff09<\/h3>\n<p>\u4e3a\u4e86\u89e3\u51b3\u95f4\u63a5\u5757\u7684\u5c40\u9650\u6027\uff0cEXT4\u5f15\u5165\u4e86<strong>\u6269\u5c55\u533a\uff08extents\uff09<\/strong>\uff0c\u5141\u8bb8\u8fde\u7eed\u5757\u5206\u914d\uff0c\u4ece\u800c\u63d0\u5347\u6027\u80fd\u5e76\u51cf\u5c11\u788e\u7247\u3002\u6269\u5c55\u533a\u662f\u4e00\u7ec4\u8fde\u7eed\u7684\u5757\uff0cEXT4\u901a\u8fc7\u6811\u72b6\u7ed3\u6784\u7ec4\u7ec7\u5b83\u4eec\uff0c\u7531<code>ext4_extent_header<\/code>\u7ba1\u7406\uff1a<\/p>\n<pre><code class=\"language-c\">struct ext4_extent_header {\r\n    __le16  eh_magic;      \/* \u683c\u5f0f\u6807\u8bc6 *\/\r\n    __le16  eh_entries;    \/* \u6709\u6548\u6761\u76ee\u6570 *\/\r\n    __le16  eh_max;        \/* \u8282\u70b9\u53ef\u5bb9\u7eb3\u7684\u6700\u5927\u6761\u76ee\u6570 *\/\r\n    __le16  eh_depth;      \/* \u6811\u6df1\u5ea6 *\/\r\n    __le32  eh_generation; \/* \u6811\u751f\u6210\u7f16\u53f7 *\/\r\n};\r\n<\/code><\/pre>\n<ul>\n<li><strong>\u53f6\u5b50\u8282\u70b9<\/strong>\uff08<code>eh_depth = 0<\/code>\uff09\uff1a\u5305\u542b<code>ext4_extent<\/code>\u7ed3\u6784\uff0c\u6307\u5411\u8fde\u7eed\u7684\u6570\u636e\u5757\u3002<\/li>\n<li><strong>\u7d22\u5f15\u8282\u70b9<\/strong>\uff08<code>eh_depth &gt; 0<\/code>\uff09\uff1a\u6307\u5411\u4e0b\u5c42\u7684\u53f6\u5b50\u8282\u70b9\u6216\u7d22\u5f15\u8282\u70b9\u3002<\/li>\n<\/ul>\n<pre><code class=\"language-c\">struct ext4_extent {\r\n    __le32  ee_block;      \/* \u7b2c\u4e00\u4e2a\u903b\u8f91\u5757 *\/\r\n    __le16  ee_len;        \/* \u5757\u6570\u91cf *\/\r\n    __le16  ee_start_hi;   \/* \u7269\u7406\u5757\u9ad816\u4f4d *\/\r\n    __le32  ee_start_lo;   \/* \u7269\u7406\u5757\u4f4e32\u4f4d *\/\r\n};\r\n\r\nstruct ext4_extent_idx {\r\n    __le32  ei_block;      \/* \u8986\u76d6\u7684\u903b\u8f91\u5757 *\/\r\n    __le32  ei_leaf_lo;    \/* \u4e0b\u4e00\u5c42\u5757\u7684\u6307\u9488 *\/\r\n    __le16  ei_leaf_hi;    \/* \u4e0b\u4e00\u5c42\u5757\u9ad816\u4f4d *\/\r\n    __u16   ei_unused;\r\n};\r\n<\/code><\/pre>\n<p>\u5bf9\u4e8e\u5c0f\u6587\u4ef6\uff0c\u7d22\u5f15\u8282\u70b9\u7684<code>i_block<\/code>\u53ef\u4ee5\u5b58\u50a8\u4e00\u4e2a<code>ext4_extent_header<\/code>\u548c\u6700\u591a\u56db\u4e2a<code>ext4_extent<\/code>\u6761\u76ee\uff0c\u8868\u793a\u9ad8\u8fbe512MB\u7684\u6570\u636e\uff084\u4e2a\u6269\u5c55\u533a\u00d7\u6bcf\u4e2a128MB\uff09\u3002\u5bf9\u4e8e\u5927\u6587\u4ef6\uff0c\u6269\u5c55\u533a\u6811\u4f1a\u6269\u5c55\uff0c\u4e00\u4e2a4KB\u5757\u53ef\u5bb9\u7eb3340\u4e2a\u6269\u5c55\u533a\uff0c\u652f\u6301\u9ad8\u8fbe42.5GB\u7684\u6587\u4ef6\u3002<\/p>\n<h3>\u7d22\u5f15\u8282\u70b9\u4e0e\u5757\u4f4d\u56fe<\/h3>\n<p>EXT4\u4f7f\u7528\u4f4d\u56fe\u8ddf\u8e2a\u7d22\u5f15\u8282\u70b9\u548c\u5757\u7684\u5206\u914d\u72b6\u6001\uff1a<\/p>\n<ul>\n<li><strong>\u7d22\u5f15\u8282\u70b9\u4f4d\u56fe<\/strong>\uff1a\u4e00\u4e2a4KB\u5757\uff0c\u6bcf\u4f4d\u8868\u793a\u4e00\u4e2a\u7d22\u5f15\u8282\u70b9\u662f\u5426\u88ab\u5206\u914d\uff081\u8868\u793a\u5df2\u7528\uff0c0\u8868\u793a\u7a7a\u95f2\uff09\u3002<\/li>\n<li><strong>\u5757\u4f4d\u56fe<\/strong>\uff1a\u7c7b\u4f3c\u5730\u8ddf\u8e2a\u5757\u5206\u914d\u72b6\u6001\u3002<\/li>\n<\/ul>\n<p>\u521b\u5efa\u6587\u4ef6\uff08\u4f8b\u5982\uff0c\u4f7f\u7528<code>open<\/code>\u51fd\u6570\u5e76\u5e26<code>O_CREAT<\/code>\u53c2\u6570\uff09\u65f6\uff0c\u5185\u6838\u626b\u63cf\u7d22\u5f15\u8282\u70b9\u4f4d\u56fe\u4ee5\u627e\u5230\u7a7a\u95f2\u7684\u7d22\u5f15\u8282\u70b9\uff0c\u5e76\u626b\u63cf\u5757\u4f4d\u56fe\u4ee5\u5206\u914d\u6570\u636e\u5757\u3002<\/p>\n<h3>\u6587\u4ef6\u7cfb\u7edf\u5e03\u5c40<\/h3>\n<p>EXT4\u6587\u4ef6\u7cfb\u7edf\u901a\u8fc7<strong>\u5757\u7ec4<\/strong>\u7ec4\u7ec7\u5927\u78c1\u76d8\uff0c\u6bcf\u4e2a\u5757\u7ec4\u5305\u542b\uff1a<\/p>\n<ul>\n<li><strong>\u8d85\u7ea7\u5757<\/strong>\uff1a\u5b58\u50a8\u5168\u5c40\u6587\u4ef6\u7cfb\u7edf\u5143\u6570\u636e\uff08\u4f8b\u5982\uff0c\u603b\u7d22\u5f15\u8282\u70b9\u6570\u3001\u5757\u6570\u548c\u6bcf\u7ec4\u8ba1\u6570\uff09\u3002<\/li>\n<li><strong>\u5757\u7ec4\u63cf\u8ff0\u7b26\u8868<\/strong>\uff1a\u5217\u51fa\u6bcf\u4e2a\u5757\u7ec4\u7684\u5143\u6570\u636e\uff0c\u5305\u62ec\u7d22\u5f15\u8282\u70b9\u548c\u5757\u4f4d\u56fe\u4f4d\u7f6e\u3002<\/li>\n<li><strong>\u7d22\u5f15\u8282\u70b9\u8868<\/strong>\uff1a\u5b58\u50a8\u7d22\u5f15\u8282\u70b9\u7ed3\u6784\u3002<\/li>\n<li><strong>\u6570\u636e\u5757<\/strong>\uff1a\u5b58\u50a8\u6587\u4ef6\u6570\u636e\u3002<\/li>\n<\/ul>\n<p><code>ext4_group_desc<\/code>\u7ed3\u6784\u5b9a\u4e49\u5757\u7ec4\u5143\u6570\u636e\uff1a<\/p>\n<pre><code class=\"language-c\">struct ext4_group_desc {\r\n    __le32  bg_block_bitmap_lo; \/* \u5757\u4f4d\u56fe\u4f4d\u7f6e *\/\r\n    __le32  bg_inode_bitmap_lo; \/* \u7d22\u5f15\u8282\u70b9\u4f4d\u56fe\u4f4d\u7f6e *\/\r\n    __le32  bg_inode_table_lo;  \/* \u7d22\u5f15\u8282\u70b9\u8868\u4f4d\u7f6e *\/\r\n    ...\r\n};\r\n<\/code><\/pre>\n<p>\u4e3a\u9632\u6b62\u6570\u636e\u4e22\u5931\uff0c\u8d85\u7ea7\u5757\u548c\u5757\u7ec4\u63cf\u8ff0\u7b26\u8868\u5728\u591a\u4e2a\u5757\u7ec4\u4e2d\u5b58\u50a8\u526f\u672c\u3002<strong>sparse_super<\/strong>\u7279\u6027\u901a\u8fc7\u4ec5\u5728\u7d22\u5f15\u4e3a0\u30013\u30015\u30017\u7b49\u7684\u5757\u7ec4\u4e2d\u5b58\u50a8\u526f\u672c\u6765\u51cf\u5c11\u5197\u4f59\u3002<\/p>\n<p>**\u5143\u5757\u7ec4\uff08Meta Block Group\uff09**\u7279\u6027\u8fdb\u4e00\u6b65\u4f18\u5316\uff0c\u901a\u8fc7\u5c06\u5757\u7ec4\u5206\u4e3a\u6bcf\u7ec464\u4e2a\u7684\u96c6\u5408\uff0c\u6bcf\u4e2a\u96c6\u5408\u7ef4\u62a4\u81ea\u5df1\u7684\u63cf\u8ff0\u7b26\u8868\uff0c\u51cf\u5c11\u7a7a\u95f4\u5360\u7528\u5e76\u63d0\u9ad8\u6269\u5c55\u6027\u3002<\/p>\n<h2>\u76ee\u5f55\u5b58\u50a8<\/h2>\n<p>EXT4\u4e2d\u7684\u76ee\u5f55\u88ab\u89c6\u4e3a\u5177\u6709\u7d22\u5f15\u8282\u70b9\u7684\u6587\u4ef6\uff0c\u4f46\u5176\u6570\u636e\u5757\u5b58\u50a8\u7684\u662f<code>ext4_dir_entry<\/code>\u7ed3\u6784\u5217\u8868\uff0c\u6bcf\u4e2a\u7ed3\u6784\u5305\u542b\u6587\u4ef6\u540d\u53ca\u5176\u5bf9\u5e94\u7684\u7d22\u5f15\u8282\u70b9\u7f16\u53f7\uff1a<\/p>\n<ul>\n<li><strong>&#8220;.&#8221;<\/strong>\uff1a\u5f53\u524d\u76ee\u5f55\u3002<\/li>\n<li><strong>&#8220;..&#8221;<\/strong>\uff1a\u7236\u76ee\u5f55\u3002<\/li>\n<li><strong>\u5176\u4ed6\u6761\u76ee<\/strong>\uff1a\u6587\u4ef6\u6216\u5b50\u76ee\u5f55\u7684\u6587\u4ef6\u540d\u548c\u7d22\u5f15\u8282\u70b9\u3002<\/li>\n<\/ul>\n<p>\u5bf9\u4e8e\u5927\u578b\u76ee\u5f55\uff0c\u8bbe\u7f6e<code>EXT4_INDEX_FL<\/code>\u6807\u5fd7\u542f\u7528\u57fa\u4e8e\u54c8\u5e0c\u7684\u7d22\u5f15\uff0c\u5c06\u6761\u76ee\u7ec4\u7ec7\u6210\u6811\u4ee5\u52a0\u5feb\u67e5\u627e\u901f\u5ea6\u3002\u54c8\u5e0c\u5c06\u6587\u4ef6\u540d\u6620\u5c04\u5230\u6570\u636e\u5757\uff0c\u53f6\u5b50\u8282\u70b9\u5305\u542b<code>ext4_dir_entry<\/code>\u5217\u8868\u3002<\/p>\n<h2>Linux\u4e2d\u7684\u6587\u4ef6\u7f13\u5b58<\/h2>\n<p>Linux\u5185\u6838\u901a\u8fc7\u7f13\u5b58\u4f18\u5316\u6587\u4ef6I\/O\uff0cEXT4\u6587\u4ef6\u64cd\u4f5c\u7531<code>ext4_file_operations<\/code>\u5b9e\u73b0\uff1a<\/p>\n<pre><code class=\"language-c\">const struct file_operations ext4_file_operations = {\r\n    .read_iter  = ext4_file_read_iter,\r\n    .write_iter = ext4_file_write_iter,\r\n    ...\r\n};\r\n<\/code><\/pre>\n<h3>\u7f13\u5b58I\/O\u4e0e\u76f4\u63a5I\/O<\/h3>\n<p>Linux\u652f\u6301\u4e24\u79cdI\/O\u6a21\u5f0f\uff1a<\/p>\n<ol>\n<li><strong>\u7f13\u5b58I\/O<\/strong>\uff1a\n<ul>\n<li><strong>\u8bfb\u53d6<\/strong>\uff1a\u68c0\u67e5\u5185\u6838\u9875\u9762\u7f13\u5b58\u3002\u5982\u679c\u6570\u636e\u5df2\u7f13\u5b58\uff0c\u76f4\u63a5\u8fd4\u56de\uff1b\u5426\u5219\uff0c\u4ece\u78c1\u76d8\u8bfb\u53d6\u5e76\u7f13\u5b58\u3002<\/li>\n<li><strong>\u5199\u5165<\/strong>\uff1a\u5c06\u6570\u636e\u590d\u5236\u5230\u5185\u6838\u9875\u9762\u7f13\u5b58\uff0c\u6807\u8bb0\u4e3a\u810f\u9875\u3002\u5185\u6838\u7a0d\u540e\u5c06\u810f\u9875\u5199\u5165\u78c1\u76d8\uff08\u4f8b\u5982\uff0c\u901a\u8fc7<code>sync<\/code>\u6216\u5185\u5b58\u4e0d\u8db3\u65f6\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u76f4\u63a5I\/O<\/strong>\uff1a\n<ul>\n<li>\u7ed5\u8fc7\u7f13\u5b58\uff0c\u76f4\u63a5\u8bfb\u5199\u78c1\u76d8\uff0c\u51cf\u5c11\u5185\u6838\u7f13\u5b58\u4e0e\u7528\u6237\u7a0b\u5e8f\u4e4b\u95f4\u7684\u6570\u636e\u590d\u5236\u5f00\u9500\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<h3>\u7f13\u5b58\u5199\u5165\u64cd\u4f5c<\/h3>\n<p><code>generic_perform_write<\/code>\u51fd\u6570\u5904\u7406\u7f13\u5b58\u5199\u5165\uff1a<\/p>\n<ol>\n<li><strong>\u51c6\u5907<\/strong>\uff1a\u8c03\u7528<code>ext4_write_begin<\/code>\u521d\u59cb\u5316\u65e5\u5fd7\u5e76\u5206\u914d\u7f13\u5b58\u9875\u9762\u3002<\/li>\n<li><strong>\u590d\u5236<\/strong>\uff1a\u4f7f\u7528<code>iov_iter_copy_from_user_atomic<\/code>\u5c06\u6570\u636e\u4ece\u7528\u6237\u7a7a\u95f4\u590d\u5236\u5230\u5185\u6838\u9875\u9762\u7f13\u5b58\u3002<\/li>\n<li><strong>\u5b8c\u6210<\/strong>\uff1a\u8c03\u7528<code>ext4_write_end<\/code>\u5b8c\u6210\u65e5\u5fd7\u8bb0\u5f55\u5e76\u6807\u8bb0\u9875\u9762\u4e3a\u810f\u9875\u3002<\/li>\n<li><strong>\u5e73\u8861<\/strong>\uff1a\u8c03\u7528<code>balance_dirty_pages_ratelimited<\/code>\u7ba1\u7406\u810f\u9875\uff0c\u8d85\u8fc7\u9608\u503c\u65f6\u89e6\u53d1\u56de\u5199\u3002<\/li>\n<\/ol>\n<p>EXT4\u652f\u6301\u4e09\u79cd<strong>\u65e5\u5fd7\u6a21\u5f0f<\/strong>\u4ee5\u786e\u4fdd\u53ef\u9760\u6027\uff1a<\/p>\n<ul>\n<li><strong>\u65e5\u5fd7\u6a21\u5f0f<\/strong>\uff1a\u5728\u5199\u5165\u6587\u4ef6\u7cfb\u7edf\u4e4b\u524d\u8bb0\u5f55\u5143\u6570\u636e\u548c\u6570\u636e\u7684\u65e5\u5fd7\uff0c\u5b89\u5168\u6027\u6700\u9ad8\u4f46\u6027\u80fd\u8f83\u4f4e\u3002<\/li>\n<li><strong>\u6709\u5e8f\u6a21\u5f0f<\/strong>\uff08\u9ed8\u8ba4\uff09\uff1a\u4ec5\u8bb0\u5f55\u5143\u6570\u636e\u65e5\u5fd7\uff0c\u786e\u4fdd\u6570\u636e\u5728\u5143\u6570\u636e\u4e4b\u524d\u5199\u5165\u78c1\u76d8\u3002<\/li>\n<li><strong>\u5199\u56de\u6a21\u5f0f<\/strong>\uff1a\u4ec5\u8bb0\u5f55\u5143\u6570\u636e\u65e5\u5fd7\uff0c\u4e0d\u4fdd\u8bc1\u6570\u636e\u5148\u4e8e\u5143\u6570\u636e\u5199\u5165\uff0c\u6027\u80fd\u6700\u9ad8\u4f46\u5b89\u5168\u6027\u6700\u4f4e\u3002<\/li>\n<\/ul>\n<h3>\u7f13\u5b58\u8bfb\u53d6\u64cd\u4f5c<\/h3>\n<p><code>generic_file_buffered_read<\/code>\u51fd\u6570\u5904\u7406\u7f13\u5b58\u8bfb\u53d6\uff1a<\/p>\n<ol>\n<li><strong>\u68c0\u67e5\u7f13\u5b58<\/strong>\uff1a\u4f7f\u7528<code>find_get_page<\/code>\u67e5\u627e\u9875\u9762\u7f13\u5b58\u3002<\/li>\n<li><strong>\u9884\u8bfb<\/strong>\uff1a\u5982\u679c\u672a\u627e\u5230\u7f13\u5b58\uff0c\u89e6\u53d1\u540c\u6b65\u9884\u8bfb\uff08<code>page_cache_sync_readahead<\/code>\uff09\u52a0\u8f7d\u6570\u636e\u53ca\u76f8\u90bb\u5757\u3002<\/li>\n<li><strong>\u5f02\u6b65\u9884\u8bfb<\/strong>\uff1a\u5bf9\u4e8e\u6807\u8bb0\u4e3a\u9884\u8bfb\u7684\u7f13\u5b58\u9875\u9762\uff0c\u542f\u52a8\u5f02\u6b65\u9884\u8bfb\uff08<code>page_cache_async_readahead<\/code>\uff09\u3002<\/li>\n<li><strong>\u590d\u5236<\/strong>\uff1a\u4f7f\u7528<code>copy_page_to_iter<\/code>\u5c06\u6570\u636e\u4ece\u5185\u6838\u7f13\u5b58\u590d\u5236\u5230\u7528\u6237\u7a7a\u95f4\u3002<\/li>\n<\/ol>\n<h2>\u7ed3\u8bba<\/h2>\n<p>EXT4\u6587\u4ef6\u7cfb\u7edf\u51ed\u501f\u5176\u57fa\u4e8e\u7d22\u5f15\u8282\u70b9\u7684\u7ed3\u6784\u3001\u6269\u5c55\u533a\u6811\u548c\u5f3a\u5927\u7684\u65e5\u5fd7\u529f\u80fd\uff0c\u4e3aLinux\u5b58\u50a8\u63d0\u4f9b\u4e86\u53ef\u9760\u4e14\u9ad8\u6548\u7684\u89e3\u51b3\u65b9\u6848\u3002\u901a\u8fc7\u5229\u7528\u7f13\u5b58\u548c\u4f18\u5316\u7684I\/O\u64cd\u4f5c\uff0cLinux\u5185\u6838\u786e\u4fdd\u4e86\u5c0f\u578b\u548c\u5927\u578b\u6587\u4ef6\u7684\u9ad8\u6027\u80fd\u3002\u4e86\u89e3\u8fd9\u4e9b\u7ec4\u4ef6\u5bf9\u4e8e\u7cfb\u7edf\u7ba1\u7406\u5458\u548c\u5f00\u53d1\u8005\u4f18\u5316\u5b58\u50a8\u6027\u80fd\u6216\u6392\u67e5\u6587\u4ef6\u7cfb\u7edf\u95ee\u9898\u81f3\u5173\u91cd\u8981\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linux\u6587\u4ef6\u7cfb\u7edf\u662f\u64cd\u4f5c\u7cfb\u7edf\u7684\u6838&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4924],"tags":[],"class_list":["post-208383","post","type-post","status-publish","format-standard","hent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