1 files changed, 81 insertions, 1 deletions

diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 4450d17c11e8..e6c321e5bf73 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -22,12 +22,14 @@
 #define fscache_available() (1)
 #define fscache_volume_valid(volume) (volume)
 #define fscache_cookie_valid(cookie) (cookie)
-#define fscache_cookie_enabled(cookie) (cookie)
+#define fscache_resources_valid(cres) ((cres)->cache_priv)
+#define fscache_cookie_enabled(cookie) (cookie && !test_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags))
 #else
 #define __fscache_available (0)
 #define fscache_available() (0)
 #define fscache_volume_valid(volume) (0)
 #define fscache_cookie_valid(cookie) (0)
+#define fscache_resources_valid(cres) (false)
 #define fscache_cookie_enabled(cookie) (0)
 #endif
 
@@ -46,6 +48,7 @@ enum fscache_cookie_state {
 	FSCACHE_COOKIE_STATE_CREATING,		/* The cache object is being created */
 	FSCACHE_COOKIE_STATE_ACTIVE,		/* The cache is active, readable and writable */
 	FSCACHE_COOKIE_STATE_FAILED,		/* The cache failed, withdraw to clear */
+	FSCACHE_COOKIE_STATE_LRU_DISCARDING,	/* The cookie is being discarded by the LRU */
 	FSCACHE_COOKIE_STATE_WITHDRAWING,	/* The cookie is being withdrawn */
 	FSCACHE_COOKIE_STATE_RELINQUISHING,	/* The cookie is being relinquished */
 	FSCACHE_COOKIE_STATE_DROPPED,		/* The cookie has been dropped */
@@ -147,6 +150,8 @@ extern struct fscache_cookie *__fscache_acquire_cookie(
 	const void *, size_t,
 	const void *, size_t,
 	loff_t);
+extern void __fscache_use_cookie(struct fscache_cookie *, bool);
+extern void __fscache_unuse_cookie(struct fscache_cookie *, const void *, const loff_t *);
 extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
 
 /**
@@ -229,6 +234,39 @@ struct fscache_cookie *fscache_acquire_cookie(struct fscache_volume *volume,
 }
 
 /**
+ * fscache_use_cookie - Request usage of cookie attached to an object
+ * @object: Object description
+ * @will_modify: If cache is expected to be modified locally
+ *
+ * Request usage of the cookie attached to an object.  The caller should tell
+ * the cache if the object's contents are about to be modified locally and then
+ * the cache can apply the policy that has been set to handle this case.
+ */
+static inline void fscache_use_cookie(struct fscache_cookie *cookie,
+				      bool will_modify)
+{
+	if (fscache_cookie_valid(cookie))
+		__fscache_use_cookie(cookie, will_modify);
+}
+
+/**
+ * fscache_unuse_cookie - Cease usage of cookie attached to an object
+ * @object: Object description
+ * @aux_data: Updated auxiliary data (or NULL)
+ * @object_size: Revised size of the object (or NULL)
+ *
+ * Cease usage of the cookie attached to an object.  When the users count
+ * reaches zero then the cookie relinquishment will be permitted to proceed.
+ */
+static inline void fscache_unuse_cookie(struct fscache_cookie *cookie,
+					const void *aux_data,
+					const loff_t *object_size)
+{
+	if (fscache_cookie_valid(cookie))
+		__fscache_unuse_cookie(cookie, aux_data, object_size);
+}
+
+/**
  * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
  * it
  * @cookie: The cookie being returned
@@ -247,4 +285,46 @@ void fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
 		__fscache_relinquish_cookie(cookie, retire);
 }
 
+/*
+ * Find the auxiliary data on a cookie.
+ */
+static inline void *fscache_get_aux(struct fscache_cookie *cookie)
+{
+	if (cookie->aux_len <= sizeof(cookie->inline_aux))
+		return cookie->inline_aux;
+	else
+		return cookie->aux;
+}
+
+/*
+ * Update the auxiliary data on a cookie.
+ */
+static inline
+void fscache_update_aux(struct fscache_cookie *cookie,
+			const void *aux_data, const loff_t *object_size)
+{
+	void *p = fscache_get_aux(cookie);
+
+	if (aux_data && p)
+		memcpy(p, aux_data, cookie->aux_len);
+	if (object_size)
+		cookie->object_size = *object_size;
+}
+
+#ifdef CONFIG_FSCACHE_STATS
+extern atomic_t fscache_n_updates;
+#endif
+
+static inline
+void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data,
+			     const loff_t *object_size)
+{
+#ifdef CONFIG_FSCACHE_STATS
+	atomic_inc(&fscache_n_updates);
+#endif
+	fscache_update_aux(cookie, aux_data, object_size);
+	smp_wmb();
+	set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
+}
+
 #endif /* _LINUX_FSCACHE_H */