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authorDavid Howells <dhowells@redhat.com>2021-12-06 15:54:04 +0000
committerDavid Howells <dhowells@redhat.com>2022-01-11 22:13:01 +0000
commite6435f1e02f410e3507f02a37c0fbb17971ddc7c (patch)
tree43f0de2be43650ee17d48abf7a337f164395ff2a /fs/fscache
parente0484344c0413e1fcd5642b77d49c7648fb194ec (diff)
fscache: Add a tracepoint for cookie use/unuse
Add a tracepoint to track fscache_use/unuse_cookie(). Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164021588628.640689.12942919367404043608.stgit@warthog.procyon.org.uk/ # v4
Diffstat (limited to 'fs/fscache')
-rw-r--r--fs/fscache/cookie.c29
1 files changed, 25 insertions, 4 deletions
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);