Re: [PATCH 2/3] FS-Cache: Reduce cookie ref count if submit fails.

From: David Howells
Date: Tue Aug 12 2014 - 08:47:59 EST


Milosz Tanski <milosz@xxxxxxxxx> wrote:

> The honest answer is I don't know if it know if needs to be unlocked
> before or after. I saw a same pattern with unlocking order inside of
> __fscache_attr_changed in the failure case.

Following the enomem label, I'm calling fscache_unuse_cookie() which does this
without holding the lock in the same function.

I don't think the lock is required because:

(1) We hold a ref on cookie->n_active so the cookie cannot go away until we
release it, so calling __fscache_unuse_cookie() without the lock held
should be fine.

(2) wake_up_atomic_t() does not access cookie->n_active. The address is
merely needed as a key for the waiters to match on.

David
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