We should never block when holding a spin lock, but zfs_inode_update can block in the critical section of a spin lock in zfs_inode_update: zfs_inode_update -> dmu_object_size_from_db -> zrl_add -> mutex_enter Signed-off-by: Richard Yao <ryao@gentoo.org> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #3858