From e6435f1e02f410e3507f02a37c0fbb17971ddc7c Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 6 Dec 2021 15:54:04 +0000 Subject: fscache: Add a tracepoint for cookie use/unuse Add a tracepoint to track fscache_use/unuse_cookie(). Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164021588628.640689.12942919367404043608.stgit@warthog.procyon.org.uk/ # v4 --- fs/fscache/cookie.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) (limited to 'fs/fscache') diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c index a7ea7d1db032..9bb1ab5fe5ed 100644 --- a/fs/fscache/cookie.c +++ b/fs/fscache/cookie.c @@ -556,6 +556,7 @@ void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify) { enum fscache_cookie_state state; bool queue = false; + int n_active; _enter("c=%08x", cookie->debug_id); @@ -565,7 +566,11 @@ void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify) spin_lock(&cookie->lock); - atomic_inc(&cookie->n_active); + n_active = atomic_inc_return(&cookie->n_active); + trace_fscache_active(cookie->debug_id, refcount_read(&cookie->ref), + n_active, atomic_read(&cookie->n_accesses), + will_modify ? + fscache_active_use_modify : fscache_active_use); again: state = fscache_cookie_state(cookie); @@ -638,13 +643,29 @@ static void fscache_unuse_cookie_locked(struct fscache_cookie *cookie) void __fscache_unuse_cookie(struct fscache_cookie *cookie, const void *aux_data, const loff_t *object_size) { + unsigned int debug_id = cookie->debug_id; + unsigned int r = refcount_read(&cookie->ref); + unsigned int a = atomic_read(&cookie->n_accesses); + unsigned int c; + if (aux_data || object_size) __fscache_update_cookie(cookie, aux_data, object_size); - if (atomic_dec_and_lock(&cookie->n_active, &cookie->lock)) { - fscache_unuse_cookie_locked(cookie); - spin_unlock(&cookie->lock); + /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ + c = atomic_fetch_add_unless(&cookie->n_active, -1, 1); + if (c != 1) { + trace_fscache_active(debug_id, r, c - 1, a, fscache_active_unuse); + return; } + + spin_lock(&cookie->lock); + r = refcount_read(&cookie->ref); + a = atomic_read(&cookie->n_accesses); + c = atomic_dec_return(&cookie->n_active); + trace_fscache_active(debug_id, r, c, a, fscache_active_unuse); + if (c == 0) + fscache_unuse_cookie_locked(cookie); + spin_unlock(&cookie->lock); } EXPORT_SYMBOL(__fscache_unuse_cookie); -- cgit v1.2.3