Messages in this thread | | | Date | Tue, 18 Dec 2007 15:10:50 +0800 | From | wit <> | Subject | About mounting the sysfs |
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Hi all, Currently, I'm studying the code of the sysfs. But I got the following questions:
1. What is the d_alloc_root used for? Actually, the question should be: why we have to call d_alloc_root. I think the root already has its dentry, why we have to allocate another while we mounting a file system?
2. Why we call d_alloc_root to allocate a dentry for the mount point while the usual mount point of sysfs is defined by the user (something like /sysfs but not /). See below: root = d_alloc_root(inode); if (!root) { pr_debug("%s: could not get root dentry!\n",__FUNCTION__); iput(inode); return -ENOMEM; } root->d_fsdata = &sysfs_root; sb->s_root = root;
does this means settting the sysfs' mount point to "/" but not "/sysfs".
Thanks.
--Zhanhua
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