1 files changed, 85 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/indexer/index-session.h b/drivers/md/dm-vdo/indexer/index-session.h
new file mode 100644
index 000000000000..066648f6e062
--- /dev/null
+++ b/drivers/md/dm-vdo/indexer/index-session.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef UDS_INDEX_SESSION_H
+#define UDS_INDEX_SESSION_H
+
+#include <linux/atomic.h>
+#include <linux/cache.h>
+
+#include "thread-utils.h"
+
+#include "config.h"
+#include "indexer.h"
+
+/*
+ * The index session mediates all interactions with a UDS index. Once the index session is created,
+ * it can be used to open, close, suspend, or recreate an index. It implements the majority of the
+ * functions in the top-level UDS API.
+ *
+ * If any deduplication request fails due to an internal error, the index is marked disabled. It
+ * will not accept any further requests and can only be closed. Closing the index will clear the
+ * disabled flag, and the index can then be reopened and recovered using the same index session.
+ */
+
+struct __aligned(L1_CACHE_BYTES) session_stats {
+	/* Post requests that found an entry */
+	u64 posts_found;
+	/* Post requests found in the open chapter */
+	u64 posts_found_open_chapter;
+	/* Post requests found in the dense index */
+	u64 posts_found_dense;
+	/* Post requests found in the sparse index */
+	u64 posts_found_sparse;
+	/* Post requests that did not find an entry */
+	u64 posts_not_found;
+	/* Update requests that found an entry */
+	u64 updates_found;
+	/* Update requests that did not find an entry */
+	u64 updates_not_found;
+	/* Delete requests that found an entry */
+	u64 deletions_found;
+	/* Delete requests that did not find an entry */
+	u64 deletions_not_found;
+	/* Query requests that found an entry */
+	u64 queries_found;
+	/* Query requests that did not find an entry */
+	u64 queries_not_found;
+	/* Total number of requests */
+	u64 requests;
+};
+
+enum index_suspend_status {
+	/* An index load has started but the index is not ready for use. */
+	INDEX_OPENING = 0,
+	/* The index is able to handle requests. */
+	INDEX_READY,
+	/* The index is attempting to suspend a rebuild. */
+	INDEX_SUSPENDING,
+	/* An index rebuild has been suspended. */
+	INDEX_SUSPENDED,
+	/* An index rebuild is being stopped in order to shut down. */
+	INDEX_FREEING,
+};
+
+struct index_load_context {
+	struct mutex mutex;
+	struct cond_var cond;
+	enum index_suspend_status status;
+};
+
+struct uds_index_session {
+	unsigned int state;
+	struct uds_index *index;
+	struct uds_request_queue *callback_queue;
+	struct uds_parameters parameters;
+	struct index_load_context load_context;
+	struct mutex request_mutex;
+	struct cond_var request_cond;
+	int request_count;
+	struct session_stats stats;
+};
+
+#endif /* UDS_INDEX_SESSION_H */