On Thu, Jun 12, 2014 at 11:43:14AM +0100, Al Viro wrote:
> On Mon, Jun 09, 2014 at 02:06:07PM -0400, Steven Rostedt wrote:
>
> > When these are called, the d_entry and inode locks need to be released
> > to call the instance creation and deletion code. That code has its own
> > accounting and locking to serialize everything to prevent multiple
> > users from causing harm. As the parent "instance" directory can not
> > be modified this simplifies things.
>
> Yecchhh... Looking at debugfs:
>
> static inline int debugfs_positive(struct dentry *dentry)
> {
> return dentry->d_inode && !d_unhashed(dentry);
> }
>
> ...
> if (debugfs_positive(dentry)) {
> if (dentry->d_inode) {
> What the hell?
>
> parent = dentry->d_parent;
> if (!parent || !parent->d_inode)
> return;
> Huh? First of all, ->d_parent is *never* NULL. Moreover, it can't be a
> negative dentry.
>
> What's more, if debugfs_rename() is ever used for cross-directory renames,
> this tree-walker is buggered - it'll happily walk up "back" into a directory
> it has never visited...
All of that code has been there since before 2.11, I really don't
remember how I came up with it at all, sorry.
I'm working on converting debugfs to use kernfs, so all of the debugfs
mess and problems should go away soon.
thanks,
greg k-h
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