FS-Cache: Add use/unuse/wake cookie wrappers
Add wrapper functions for dealing with cookie->n_active:
(*) __fscache_use_cookie() to increment it.
(*) __fscache_unuse_cookie() to decrement and test against zero.
(*) __fscache_wake_unused_cookie() to wake up anyone waiting for it to reach
zero.
The second and third are split so that the third can be done after cookie->lock
has been released in case the waiter wakes up whilst we're still holding it and
tries to get it.
We will need to wake-on-zero once the cookie disablement patch is applied
because it will then be possible to see n_active become zero without the cookie
being relinquished.
Also move the cookie usement out of fscache_attr_changed_op() and into
fscache_attr_changed() and the operation struct so that cookie disablement
will be able to track it.
Whilst we're at it, only increment n_active if we're about to do
fscache_submit_op() so that we don't have to deal with undoing it if anything
earlier fails. Possibly this should be moved into fscache_submit_op() which
could look at FSCACHE_OP_UNUSE_COOKIE.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 7823e9e..96a2b66 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -511,6 +511,11 @@
op->end_io_func(page, op->context, error);
}
+static inline void __fscache_use_cookie(struct fscache_cookie *cookie)
+{
+ atomic_inc(&cookie->n_active);
+}
+
/**
* fscache_use_cookie - Request usage of cookie attached to an object
* @object: Object description
@@ -524,6 +529,16 @@
return atomic_inc_not_zero(&cookie->n_active) != 0;
}
+static inline bool __fscache_unuse_cookie(struct fscache_cookie *cookie)
+{
+ return atomic_dec_and_test(&cookie->n_active);
+}
+
+static inline void __fscache_wake_unused_cookie(struct fscache_cookie *cookie)
+{
+ wake_up_atomic_t(&cookie->n_active);
+}
+
/**
* fscache_unuse_cookie - Cease usage of cookie attached to an object
* @object: Object description
@@ -534,8 +549,8 @@
static inline void fscache_unuse_cookie(struct fscache_object *object)
{
struct fscache_cookie *cookie = object->cookie;
- if (atomic_dec_and_test(&cookie->n_active))
- wake_up_atomic_t(&cookie->n_active);
+ if (__fscache_unuse_cookie(cookie))
+ __fscache_wake_unused_cookie(cookie);
}
/*