afs: Make vnode->cb_interest RCU safe
Use RCU-based freeing for afs_cb_interest struct objects and use RCU on
vnode->cb_interest. Use that change to allow afs_check_validity() to use
read_seqbegin_or_lock() instead of read_seqlock_excl().
This also requires the caller of afs_check_validity() to hold the RCU read
lock across the call.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/afs/security.c b/fs/afs/security.c
index 857f09d..5d8ece9 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -146,7 +146,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
}
if (afs_cb_is_broken(cb_break, vnode,
- vnode->cb_interest)) {
+ rcu_dereference(vnode->cb_interest))) {
changed = true;
break;
}
@@ -176,7 +176,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
}
}
- if (afs_cb_is_broken(cb_break, vnode, vnode->cb_interest))
+ if (afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)))
goto someone_else_changed_it;
/* We need a ref on any permits list we want to copy as we'll have to
@@ -253,14 +253,16 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
kfree(new);
+ rcu_read_lock();
spin_lock(&vnode->lock);
zap = rcu_access_pointer(vnode->permit_cache);
- if (!afs_cb_is_broken(cb_break, vnode, vnode->cb_interest) &&
+ if (!afs_cb_is_broken(cb_break, vnode, rcu_dereference(vnode->cb_interest)) &&
zap == permits)
rcu_assign_pointer(vnode->permit_cache, replacement);
else
zap = replacement;
spin_unlock(&vnode->lock);
+ rcu_read_unlock();
afs_put_permits(zap);
out_put:
afs_put_permits(permits);