Re: [PATCH] Fix of dcache race leading to busy inodes on umount

[Kirill Korotaev]

> > This patch fixes dcache race between shrink_dcache_XXX functions
> > and dput().
>
>
>
> > -void dput(struct dentry *dentry)
> > +static void dput_recursive(struct dentry *dentry, struct dcache_shrinker *ds)
> > {
> > -	if (!dentry)
> > -		return;
> > -
> > -repeat:
> > 	if (atomic_read(&dentry->d_count) == 1)
> > 		might_sleep();
> > 	if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock))
> > 		return;
> > +	dcache_shrinker_del(ds);
> >
> > +repeat:
> > 	spin_lock(&dentry->d_lock);
> > 	if (atomic_read(&dentry->d_count)) {
> > 		spin_unlock(&dentry->d_lock);
> > @@ -182,6 +253,7 @@ unhash_it:
> >
> > kill_it: {
> > 		struct dentry *parent;
> > +		struct dcache_shrinker lds;
> >
> > 		/* If dentry was on d_lru list
> > 		 * delete it from there
> > @@ -191,18 +263,43 @@ kill_it: {
> >   			dentry_stat.nr_unused--;
> >   		}
> >   		list_del(&dentry->d_child);
> > +		parent = dentry->d_parent;
> > +		dcache_shrinker_add(&lds, parent, dentry);
> > 		dentry_stat.nr_dentry--;	/* For d_free, below */
> > 		/*drops the locks, at that point nobody can reach this dentry */
> > 		dentry_iput(dentry);
> > -		parent = dentry->d_parent;
> > 		d_free(dentry);
> > 		if (dentry == parent)
>
>
> Aren't we leaving local variable `lds' on the global list here?
yup, my fault.
You patch solves this.

Kirill

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/