JFFS2 LOCKING DOCUMENTATION
---------------------------
-At least theoretically, JFFS2 does not require the Big Kernel Lock
-(BKL), which was always helpfully obtained for it by Linux 2.4 VFS
-code. It has its own locking, as described below.
-
This document attempts to describe the existing locking rules for
JFFS2. It is not expected to remain perfectly up to date, but ought to
be fairly close.
any f->sem held.
2. Never attempt to lock two file mutexes in one thread.
No ordering rules have been made for doing so.
+ 3. Never lock a page cache page with f->sem held.
erase_completion_lock spinlock