[PATCH 12/12] fscache: Use refcount_t for the cookie refcount instead of atomic_t
From: David Howells
Date: Mon Jun 21 2021 - 17:47:53 EST
Use refcount_t for the fscache_cookie refcount instead of atomic_t and
rename the 'usage' member to 'ref' in such cases. The tracepoints that
reference it change from showing "u=%d" to "r=%d".
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
fs/fscache/cache.c | 2 +-
fs/fscache/cookie.c | 31 +++++++++++++++++++---------
fs/fscache/fsdef.c | 2 +-
fs/fscache/internal.h | 17 ++++++++-------
include/linux/fscache.h | 2 +-
include/trace/events/fscache.h | 44 ++++++++++++++++++++--------------------
6 files changed, 55 insertions(+), 43 deletions(-)
diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c
index e7a5d7ab4085..bd4f44c1cce0 100644
--- a/fs/fscache/cache.c
+++ b/fs/fscache/cache.c
@@ -269,7 +269,7 @@ int fscache_add_cache(struct fscache_cache *cache,
hlist_add_head(&ifsdef->cookie_link,
&fscache_fsdef_index.backing_objects);
- atomic_inc(&fscache_fsdef_index.usage);
+ refcount_inc(&fscache_fsdef_index.ref);
/* done */
spin_unlock(&fscache_fsdef_index.lock);
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 6df3732cf1b4..cd42be646ed3 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -164,7 +164,7 @@ struct fscache_cookie *fscache_alloc_cookie(
goto nomem;
}
- atomic_set(&cookie->usage, 1);
+ refcount_set(&cookie->ref, 1);
atomic_set(&cookie->n_children, 0);
cookie->debug_id = atomic_inc_return(&fscache_cookie_debug_id);
@@ -225,7 +225,7 @@ struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *candidate)
collision:
if (test_and_set_bit(FSCACHE_COOKIE_ACQUIRED, &cursor->flags)) {
- trace_fscache_cookie(cursor->debug_id, atomic_read(&cursor->usage),
+ trace_fscache_cookie(cursor->debug_id, refcount_read(&cursor->ref),
fscache_cookie_collision);
pr_err("Duplicate cookie detected\n");
fscache_print_cookie(cursor, 'O');
@@ -826,13 +826,12 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
BUG_ON(!radix_tree_empty(&cookie->stores));
if (cookie->parent) {
- ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
+ ASSERTCMP(refcount_read(&cookie->parent->ref), >, 0);
ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
atomic_dec(&cookie->parent->n_children);
}
/* Dispose of the netfs's link to the cookie */
- ASSERTCMP(atomic_read(&cookie->usage), >, 0);
fscache_cookie_put(cookie, fscache_cookie_put_relinquish);
_leave("");
@@ -862,18 +861,17 @@ void fscache_cookie_put(struct fscache_cookie *cookie,
enum fscache_cookie_trace where)
{
struct fscache_cookie *parent;
- int usage;
+ int ref;
_enter("%x", cookie->debug_id);
do {
unsigned int cookie_debug_id = cookie->debug_id;
- usage = atomic_dec_return(&cookie->usage);
- trace_fscache_cookie(cookie_debug_id, usage, where);
+ bool zero = __refcount_dec_and_test(&cookie->ref, &ref);
- if (usage > 0)
+ trace_fscache_cookie(cookie_debug_id, ref - 1, where);
+ if (!zero)
return;
- BUG_ON(usage < 0);
parent = cookie->parent;
fscache_unhash_cookie(cookie);
@@ -886,6 +884,19 @@ void fscache_cookie_put(struct fscache_cookie *cookie,
_leave("");
}
+/*
+ * Get a reference to a cookie.
+ */
+struct fscache_cookie *fscache_cookie_get(struct fscache_cookie *cookie,
+ enum fscache_cookie_trace where)
+{
+ int ref;
+
+ __refcount_inc(&cookie->ref, &ref);
+ trace_fscache_cookie(cookie->debug_id, ref + 1, where);
+ return cookie;
+}
+
/*
* check the consistency between the netfs inode and the backing cache
*
@@ -1003,7 +1014,7 @@ static int fscache_cookies_seq_show(struct seq_file *m, void *v)
"%08x %08x %5u %5u %3u %s %03lx %-16s %px",
cookie->debug_id,
cookie->parent ? cookie->parent->debug_id : 0,
- atomic_read(&cookie->usage),
+ refcount_read(&cookie->ref),
atomic_read(&cookie->n_children),
atomic_read(&cookie->n_active),
type,
diff --git a/fs/fscache/fsdef.c b/fs/fscache/fsdef.c
index 5f8f6fe243fe..0402673c680e 100644
--- a/fs/fscache/fsdef.c
+++ b/fs/fscache/fsdef.c
@@ -46,7 +46,7 @@ static struct fscache_cookie_def fscache_fsdef_index_def = {
struct fscache_cookie fscache_fsdef_index = {
.debug_id = 1,
- .usage = ATOMIC_INIT(1),
+ .ref = REFCOUNT_INIT(1),
.n_active = ATOMIC_INIT(1),
.lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
.backing_objects = HLIST_HEAD_INIT,
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 345105dbbfd1..c3e4804b8fcb 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -54,9 +54,18 @@ extern struct fscache_cookie *fscache_alloc_cookie(struct fscache_cookie *,
const void *, size_t,
void *, loff_t);
extern struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *);
+extern struct fscache_cookie *fscache_cookie_get(struct fscache_cookie *,
+ enum fscache_cookie_trace);
extern void fscache_cookie_put(struct fscache_cookie *,
enum fscache_cookie_trace);
+static inline void fscache_cookie_see(struct fscache_cookie *cookie,
+ enum fscache_cookie_trace where)
+{
+ trace_fscache_cookie(cookie->debug_id, refcount_read(&cookie->ref),
+ where);
+}
+
/*
* fsdef.c
*/
@@ -286,14 +295,6 @@ static inline void fscache_raise_event(struct fscache_object *object,
fscache_enqueue_object(object);
}
-static inline void fscache_cookie_get(struct fscache_cookie *cookie,
- enum fscache_cookie_trace where)
-{
- int usage = atomic_inc_return(&cookie->usage);
-
- trace_fscache_cookie(cookie->debug_id, usage, where);
-}
-
/*
* get an extra reference to a netfs retrieval context
*/
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index ea61e54a6bc5..a4dab5998613 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -123,7 +123,7 @@ struct fscache_netfs {
* - indices are created on disk just-in-time
*/
struct fscache_cookie {
- atomic_t usage; /* number of users of this cookie */
+ refcount_t ref; /* number of users of this cookie */
atomic_t n_children; /* number of children of this cookie */
atomic_t n_active; /* number of active users of netfs ptrs */
unsigned int debug_id;
diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
index 55b8802740fa..51f2b492b9eb 100644
--- a/include/trace/events/fscache.h
+++ b/include/trace/events/fscache.h
@@ -161,26 +161,26 @@ fscache_cookie_traces;
TRACE_EVENT(fscache_cookie,
TP_PROTO(unsigned int cookie_debug_id,
- int usage,
+ int ref,
enum fscache_cookie_trace where),
- TP_ARGS(cookie_debug_id, usage, where),
+ TP_ARGS(cookie_debug_id, ref, where),
TP_STRUCT__entry(
__field(unsigned int, cookie )
__field(enum fscache_cookie_trace, where )
- __field(int, usage )
+ __field(int, ref )
),
TP_fast_assign(
__entry->cookie = cookie_debug_id;
__entry->where = where;
- __entry->usage = usage;
+ __entry->ref = ref;
),
- TP_printk("%s c=%08x u=%d",
+ TP_printk("%s c=%08x r=%d",
__print_symbolic(__entry->where, fscache_cookie_traces),
- __entry->cookie, __entry->usage)
+ __entry->cookie, __entry->ref)
);
TRACE_EVENT(fscache_netfs,
@@ -212,7 +212,7 @@ TRACE_EVENT(fscache_acquire,
__field(unsigned int, cookie )
__field(unsigned int, parent )
__array(char, name, 8 )
- __field(int, p_usage )
+ __field(int, p_ref )
__field(int, p_n_children )
__field(u8, p_flags )
),
@@ -220,15 +220,15 @@ TRACE_EVENT(fscache_acquire,
TP_fast_assign(
__entry->cookie = cookie->debug_id;
__entry->parent = cookie->parent->debug_id;
- __entry->p_usage = atomic_read(&cookie->parent->usage);
+ __entry->p_ref = refcount_read(&cookie->parent->ref);
__entry->p_n_children = atomic_read(&cookie->parent->n_children);
__entry->p_flags = cookie->parent->flags;
memcpy(__entry->name, cookie->def->name, 8);
__entry->name[7] = 0;
),
- TP_printk("c=%08x p=%08x pu=%d pc=%d pf=%02x n=%s",
- __entry->cookie, __entry->parent, __entry->p_usage,
+ TP_printk("c=%08x p=%08x pr=%d pc=%d pf=%02x n=%s",
+ __entry->cookie, __entry->parent, __entry->p_ref,
__entry->p_n_children, __entry->p_flags, __entry->name)
);
@@ -240,7 +240,7 @@ TRACE_EVENT(fscache_relinquish,
TP_STRUCT__entry(
__field(unsigned int, cookie )
__field(unsigned int, parent )
- __field(int, usage )
+ __field(int, ref )
__field(int, n_children )
__field(int, n_active )
__field(u8, flags )
@@ -250,15 +250,15 @@ TRACE_EVENT(fscache_relinquish,
TP_fast_assign(
__entry->cookie = cookie->debug_id;
__entry->parent = cookie->parent->debug_id;
- __entry->usage = atomic_read(&cookie->usage);
+ __entry->ref = refcount_read(&cookie->ref);
__entry->n_children = atomic_read(&cookie->n_children);
__entry->n_active = atomic_read(&cookie->n_active);
__entry->flags = cookie->flags;
__entry->retire = retire;
),
- TP_printk("c=%08x u=%d p=%08x Nc=%d Na=%d f=%02x r=%u",
- __entry->cookie, __entry->usage,
+ TP_printk("c=%08x r=%d p=%08x Nc=%d Na=%d f=%02x r=%u",
+ __entry->cookie, __entry->ref,
__entry->parent, __entry->n_children, __entry->n_active,
__entry->flags, __entry->retire)
);
@@ -270,7 +270,7 @@ TRACE_EVENT(fscache_enable,
TP_STRUCT__entry(
__field(unsigned int, cookie )
- __field(int, usage )
+ __field(int, ref )
__field(int, n_children )
__field(int, n_active )
__field(u8, flags )
@@ -278,14 +278,14 @@ TRACE_EVENT(fscache_enable,
TP_fast_assign(
__entry->cookie = cookie->debug_id;
- __entry->usage = atomic_read(&cookie->usage);
+ __entry->ref = refcount_read(&cookie->ref);
__entry->n_children = atomic_read(&cookie->n_children);
__entry->n_active = atomic_read(&cookie->n_active);
__entry->flags = cookie->flags;
),
- TP_printk("c=%08x u=%d Nc=%d Na=%d f=%02x",
- __entry->cookie, __entry->usage,
+ TP_printk("c=%08x r=%d Nc=%d Na=%d f=%02x",
+ __entry->cookie, __entry->ref,
__entry->n_children, __entry->n_active, __entry->flags)
);
@@ -296,7 +296,7 @@ TRACE_EVENT(fscache_disable,
TP_STRUCT__entry(
__field(unsigned int, cookie )
- __field(int, usage )
+ __field(int, ref )
__field(int, n_children )
__field(int, n_active )
__field(u8, flags )
@@ -304,14 +304,14 @@ TRACE_EVENT(fscache_disable,
TP_fast_assign(
__entry->cookie = cookie->debug_id;
- __entry->usage = atomic_read(&cookie->usage);
+ __entry->ref = refcount_read(&cookie->ref);
__entry->n_children = atomic_read(&cookie->n_children);
__entry->n_active = atomic_read(&cookie->n_active);
__entry->flags = cookie->flags;
),
- TP_printk("c=%08x u=%d Nc=%d Na=%d f=%02x",
- __entry->cookie, __entry->usage,
+ TP_printk("c=%08x r=%d Nc=%d Na=%d f=%02x",
+ __entry->cookie, __entry->ref,
__entry->n_children, __entry->n_active, __entry->flags)
);