fatfs: use a seperate lock to protect nodehash

Previously, fatfs used diskfs_node_refcnt_lock to serialize access to
the nodehash.

Use a separate lock to protect nodehash.  Adjust the reference
counting accordingly.  Every node in the nodehash carries a light
reference.  When we are asked to give up that light reference, we
reacquire our lock momentarily to check whether someone else
reacquired a reference through the nodehash.

* fatfs/inode.c (nodecache_lock): New lock.
(diskfs_cached_lookup): Use a separate lock to protect nodehash.
Adjust the reference counting accordingly.
(ifind): Likewise.
(diskfs_node_iterate): Likewise.
(diskfs_node_norefs): Move the code removing the node from nodehash...
(diskfs_try_dropping_softrefs): ... here, where we check whether
someone reacquired a reference, and if so hold on to our light
reference.

0 files changed, 0 insertions, 0 deletions