From cdf262f29488e6c3432911ec487ea41918fcbcd7 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 11 Nov 2021 23:14:29 +0000 Subject: fscache: Count data storage objects in a cache Count the data storage objects that are currently allocated in a cache. This is used to pin certain cache structures until cache withdrawal is complete. Three helpers are provided to manage and make use of the count: (1) void fscache_count_object(struct fscache_cache *cache); This should be called by the cache backend to note that an object has been allocated and attached to the cache. (2) void fscache_uncount_object(struct fscache_cache *cache); This should be called by the backend to note that an object has been destroyed. This sends a wakeup event that allows cache withdrawal to proceed if it was waiting for that object. (3) void fscache_wait_for_objects(struct fscache_cache *cache); This can be used by the backend to wait for all outstanding cache object to be destroyed. Each cache's counter is displayed as part of /proc/fs/fscache/caches. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819608594.215744.1812706538117388252.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906911646.143852.168184059935530127.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967111846.1823006.9868154941573671255.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021516219.640689.4934796654308958158.stgit@warthog.procyon.org.uk/ # v4 --- fs/fscache/cache.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/fscache') diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c index 25eac61f1c29..2749933852a9 100644 --- a/fs/fscache/cache.c +++ b/fs/fscache/cache.c @@ -13,6 +13,8 @@ static LIST_HEAD(fscache_caches); DECLARE_RWSEM(fscache_addremove_sem); EXPORT_SYMBOL(fscache_addremove_sem); +DECLARE_WAIT_QUEUE_HEAD(fscache_clearance_waiters); +EXPORT_SYMBOL(fscache_clearance_waiters); static atomic_t fscache_cache_debug_id; -- cgit v1.2.3