[ davec added to cc incase I've said something incorrect about list_lru Changes in this version: - no _bh locking - add name for a magic constant - remove unnecessary race-handling code - give a more meaningfule name for a lock for /proc/lock_stat - minor cleanups suggested by Jeff ] The nfsd filecache currently uses list_lru for tracking files recently used in NFSv3 requests which need to be "garbage collected" when they have becoming idle - unused for 2-4 seconds. I do not believe list_lru is a good tool for this. It does not allow the timeout which filecache requires so we have to add a timeout mechanism which holds the list_lru lock while the whole list is scanned looking for entries that haven't been recently accessed. When the list is largish (even a few hundred) this can block new requests noticably which need the lock to remove a file to access it. This patch removes the list_lru and instead uses 2 simple linked lists. When a file is accessed it is removed from whichever list it is on, then added to the tail of the first list. Every 2 seconds the second list is moved to the "freeme" list and the first list is moved to the second list. This avoids any need to walk a list to find old entries. These lists are per-netns rather than global as the freeme list is per-netns as the actual freeing is done in nfsd threads which are per-netns. Thanks, NeilBrown [PATCH 1/7] nfsd: filecache: remove race handling. [PATCH 2/7] nfsd: filecache: use nfsd_file_dispose_list() in [PATCH 3/7] nfsd: filecache: move globals nfsd_file_lru and [PATCH 4/7] nfsd: filecache: change garbage collection list [PATCH 5/7] nfsd: filecache: document the arbitrary limit on [PATCH 6/7] nfsd: filecache: change garbage collection to a timer. [PATCH 7/7] nfsd: filecache: give disposal lock a unique class name.
