Make removing disk devices with mounted filesystems on them safe.

Project Status: Completed

FreeBSD Developer: Edward Tomasz Napierala

The project is to make FreeBSD tolerate the removal of active disk devices, such as when a USB flash device with a mounted filesystems is physically detached by a user. Currently the system may panic in this situation. The work involves adding proper reference counting to strategic portions of the kernel and modifying filesystems to properly handle “device lost” errors.