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pcmfs初始化过程

此文是基于基于minxfs修改的文件系统得到的,不过文件系统大体的流程是大同小异的,故初始化过程其实与ext2,ext3是通用的

inode.c中有模块的入口。即module_init(init_pcmfs_fs).初始化这儿主要分析的pcmfs_fill_super函数。该函数即mount时从磁盘读取数据,填充内存超级块字段信息。该函数主要做了如下三件事情

1.sbi = kzalloc(sizeof(struct pcmfs_sb_info), GFP_KERNEL);申请内存超级快的空间,然后把磁盘超级块的内容拷贝到其中。在此处需要把VFS的 s->s_fs_info = sbi;赋值,即全局有很多文件系统数据结构,如ext2,ext3等。此处即指定当前为该sb代表的文件系统

2.申请bitmap表的空间。然后根据bitmap使用情况算出s_used_inode以及s_used_block

i = (sbi->s_imap_blocks + sbi->s_zmap_blocks) * sizeof(bh);

map = kzalloc(i, GFP_KERNEL);//step2:申请空间2 bitmap位
 
3.获取根目录的信息。即根目录所指向的数据块的dentry信息。root结点的数据信息为第一个数据块中的信息
root_inode = pcmfs_iget(s, PCMFS_ROOT_INO);
Category: 文件系统 | Tags: | Read Count: 593
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