Re: [PATCH 4/9] vfs: introduce clone_private_mount()

[Miklos Szeredi]

On Wed, Mar 13, 2013 at 11:48 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 13 Mar 2013 15:16:28 +0100 Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>
>> From: Miklos Szeredi <mszeredi@xxxxxxx>
>>
>> Overlayfs needs a private clone of the mount, so create a function for
>> this and export to modules.
>>
>> ...
>>
>> +struct vfsmount *clone_private_mount(struct path *path)
>> +{
>> +     struct mount *old_mnt = real_mount(path->mnt);
>> +     struct mount *new_mnt;
>> +
>> +     if (IS_MNT_UNBINDABLE(old_mnt))
>> +             return ERR_PTR(-EINVAL);
>> +
>> +     down_read(&namespace_sem);
>> +     new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
>> +     up_read(&namespace_sem);
>> +     if (!new_mnt)
>> +             return ERR_PTR(-ENOMEM);
>> +
>> +     return &new_mnt->mnt;
>> +}
>> +EXPORT_SYMBOL_GPL(clone_private_mount);
>
> So this one gets the _GPL?
>
> This is a new, exported-to-modules kernel interface function.  And it
> is undocumented?

Following documentation added:

/**
 * clone_private_mount - create a private clone of a path
 *
 * This creates a new vfsmount, which will be the clone of @path.  The new will
 * not be attached anywhere in the namespace and will be private (i.e. changes
 * to the originating mount won't be propagated into this).
 *
 * Release with mntput().
 */
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