Lock gofer.dentry.dataMu before SetAttr RPC modifying file size.
Lock gofer.dentry.dataMu before SetAttr RPC modifying file size.

PiperOrigin-RevId: 387427887

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor