1 files changed, 72 insertions, 0 deletions
diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
new file mode 100644
index 000000000..97e641847
--- /dev/null
+++ b/include/linux/mbcache.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_MBCACHE_H
+#define _LINUX_MBCACHE_H
+
+#include <linux/hash.h>
+#include <linux/list_bl.h>
+#include <linux/list.h>
+#include <linux/atomic.h>
+#include <linux/fs.h>
+
+struct mb_cache;
+
+/* Cache entry flags */
+enum {
+	MBE_REFERENCED_B = 0,
+	MBE_REUSABLE_B
+};
+
+struct mb_cache_entry {
+	/* List of entries in cache - protected by cache->c_list_lock */
+	struct list_head	e_list;
+	/*
+	 * Hash table list - protected by hash chain bitlock. The entry is
+	 * guaranteed to be hashed while e_refcnt > 0.
+	 */
+	struct hlist_bl_node	e_hash_list;
+	/*
+	 * Entry refcount. Once it reaches zero, entry is unhashed and freed.
+	 * While refcount > 0, the entry is guaranteed to stay in the hash and
+	 * e.g. mb_cache_entry_try_delete() will fail.
+	 */
+	atomic_t		e_refcnt;
+	/* Key in hash - stable during lifetime of the entry */
+	u32			e_key;
+	unsigned long		e_flags;
+	/* User provided value - stable during lifetime of the entry */
+	u64			e_value;
+};
+
+struct mb_cache *mb_cache_create(int bucket_bits);
+void mb_cache_destroy(struct mb_cache *cache);
+
+int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
+			  u64 value, bool reusable);
+void __mb_cache_entry_free(struct mb_cache *cache,
+			   struct mb_cache_entry *entry);
+void mb_cache_entry_wait_unused(struct mb_cache_entry *entry);
+static inline void mb_cache_entry_put(struct mb_cache *cache,
+				      struct mb_cache_entry *entry)
+{
+	unsigned int cnt = atomic_dec_return(&entry->e_refcnt);
+
+	if (cnt > 0) {
+		if (cnt <= 2)
+			wake_up_var(&entry->e_refcnt);
+		return;
+	}
+	__mb_cache_entry_free(cache, entry);
+}
+
+struct mb_cache_entry *mb_cache_entry_delete_or_get(struct mb_cache *cache,
+						    u32 key, u64 value);
+struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
+					  u64 value);
+struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
+						 u32 key);
+struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
+						struct mb_cache_entry *entry);
+void mb_cache_entry_touch(struct mb_cache *cache,
+			  struct mb_cache_entry *entry);
+
+#endif	/* _LINUX_MBCACHE_H */