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SubjectRe: [PATCH 02/11] kernfs: use idr instead of ida to manage inode number
Hello,

On Fri, Jun 02, 2017 at 02:53:55PM -0700, Shaohua Li wrote:
> @@ -630,7 +633,11 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
> if (!kn)
> goto err_out1;
>
> - ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
> + idr_preload(GFP_KERNEL);
> + spin_lock(&kernfs_idr_lock);
> + ret = idr_alloc(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
> + spin_unlock(&kernfs_idr_lock);
> + idr_preload_end();

So, this ends up populating the idr w/ a kn which isn't fully
initialized yet, which can lead to bugs which are difficult to hunt
down as we're gonna allow kn's to be looked up through ino / gen. We
probably should allocate with NULL here and populate the actual
pointer with idr_replace() after the kn is fully initialized / online.

Thanks.

--
tejun

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