Messages in this thread | | | Date | Tue, 18 Dec 2007 13:39:29 +0100 (CET) | From | Jan Engelhardt <> | Subject | Re: About mounting the sysfs |
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On Dec 18 2007 15:10, wit wrote: > >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,
It does not.
>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 /).
/sys is a dentry that belongs to the / vfsmount, but we need a / that belongs to the <whatever you are going to mount> vfsmount.
> 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".
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