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fscache: Add a tracepoint for cookie use/unuse

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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
This commit is contained in:
David Howells
2021-12-06 15:54:04 +00:00
parent e0484344c0
commit e6435f1e02
2 changed files with 69 additions and 4 deletions
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29
fs/fscache/cookie.c
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@@ -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);