Hi Jens, this series fixes how we update i_size for the block device inodes (and thus the block device). Different helpers use two different locks (bd_mutex and i_rwsem) to protect the update, and it appears device mapper uses yet another internal lock. A lot of the drivers do the update handcrafted in often crufty ways. And in addition to that mess it turns out that the "main" lock, bd_mutex is pretty dead lock prone vs other spots in the block layer that acquire it during revalidation operations, as reported by Xianting. Fix all that by adding a dedicated spinlock just for the size updates.
