TODO

What needs to be done before this branch can even be considered for merging back into the master branch:

• refactor mhash.c, rhash.c, list.c to make locking support more unobtrusive as was done with ptree.c — remove the *_r versions of calls, they are rarely used anyway
• introduce the new locking mechanism to tlist.c
• special handling of mmap’d files, msync(2) possibly mprotect(2)
• verify other execution paths in server.c implement correct locking
• introduce a compile-time define, FS_MULTICLIENT to select the new locking behaviour instead of the old “lock and forget”
• merge back in the mistakenly removed transaction stub in backend.c and lock.c
• sync documentation at Lockable File Type with the code, update to reflect practices followed in ptree.c