Re: [PATCH 02/11] kernfs: use idr instead of ida to manage inode number
From: Tejun Heo <tj@kernel.org>
Date: 2017-06-12 18:14:52
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Hello, On Fri, Jun 02, 2017 at 02:53:55PM -0700, Shaohua Li wrote:
quoted hunk ↗ jump to hunk
@@ -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