On Mon, 21 Apr 2008, Paul E. McKenney wrote: > > I did take a quick look for improperly freeing dentries -- unhashed > dentries are freed directly, so if there is a code path that somehow > unhashes dentries and then d_free()s them without a grace period, we > have a problem. No, not even then. We *always* unhash the dentries before freeing them, but we very consciously use "hlist_del_rcu()" on them, not "hlist_del_init()". That, in turn, will mean that the "pprev" pointer will still be set, so the "hlist_unhashed()" thing will *not* trigger. IOW, when we do that direct-free with: if (hlist_unhashed(&dentry->d_hash)) __d_free(dentry); the "hlist_unhashed()" will literally guarantee that i has *never* been on a hash-list at all! (If you want to test whether it is currently unhashed or not, you actually have to use "d_unhashed()" on the dentry under the dentry lock, which tests the DCACHE_UNHASHED bit). Of course, there could be some bug in there, but the thing is, none of this has even changed in a long time, certainly not since 2.6.25. Which is why I think the dcache code is all fine, and the bug comes from somewhere else corrupting the data structures. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
