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 no allow the timeout which filecache requires so we have to add a timeout mechanism which holds the list_lru for 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 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 one, 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. This should not be applied until we resolve how to handle the race-detection code in nfsd_file_put(). However I'm posting it now to get any feedback so that a final version can be posted as soon as that issue is resolved. Thanks, NeilBrown [PATCH 1/4] nfsd: filecache: use nfsd_file_dispose_list() in [PATCH 2/4] nfsd: filecache: move globals nfsd_file_lru and [PATCH 3/4] nfsd: filecache: change garbage collection list [PATCH 4/4] nfsd: filecache: change garbage collection to a timer.
