On Wed, May 28, 2014 at 8:11 PM, Al Viro <v...@zeniv.linux.org.uk> wrote:
>
> Here's an updated patch, hopefully slightly less vomit-inducing.
Hmm. Less vomit-inducing, except for this part:
> dentry = list_entry(list->prev, struct dentry, d_lru);
> +
> + parent = NULL;
> spin_lock(&dentry->d_lock);
> + if (!IS_ROOT(dentry)) {
> + parent = dentry->d_parent;
> + if (unlikely(!spin_trylock(&parent->d_lock))) {
> + spin_unlock(&dentry->d_lock);
> + parent = NULL;
> + read_seqlock_excl(&rename_lock);
> + if (!IS_ROOT(dentry)) {
> + parent = dentry->d_parent;
> + spin_lock(&parent->d_lock);
> + }
> + read_sequnlock_excl(&rename_lock);
> + spin_lock(&dentry->d_lock);
> + }
> + }
Ugh, that just *screams* for a helper function. Something like
parent = get_parent_and_lock(dentry);
or whatever, with that trylock/renamelock dance separated out. The
rule would be that it would lock the "dentry", and return the
(similarly locked) parent. Or NULL for a root dentry, of course.
Please?
Linus
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