1 files changed, 130 insertions, 0 deletions

diff --git a/drivers/md/dm-log.h b/drivers/md/dm-log.h
new file mode 100644
index 000000000000..5ae5309ebf28
--- /dev/null
+++ b/drivers/md/dm-log.h
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2003 Sistina Software
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef DM_DIRTY_LOG
+#define DM_DIRTY_LOG
+
+#include "dm.h"
+
+typedef sector_t region_t;
+
+struct dirty_log_type;
+
+struct dirty_log {
+        struct dirty_log_type *type;
+        void *context;
+};
+
+struct dirty_log_type {
+        struct list_head list;
+        const char *name;
+        struct module *module;
+        unsigned int use_count;
+
+        int (*ctr)(struct dirty_log *log, struct dm_target *ti,
+                   unsigned int argc, char **argv);
+        void (*dtr)(struct dirty_log *log);
+
+        /*
+         * There are times when we don't want the log to touch
+         * the disk.
+         */
+        int (*suspend)(struct dirty_log *log);
+        int (*resume)(struct dirty_log *log);
+
+        /*
+         * Retrieves the smallest size of region that the log can
+         * deal with.
+         */
+        uint32_t (*get_region_size)(struct dirty_log *log);
+
+        /*
+         * A predicate to say whether a region is clean or not.
+         * May block.
+         */
+        int (*is_clean)(struct dirty_log *log, region_t region);
+
+        /*
+         *  Returns: 0, 1, -EWOULDBLOCK, < 0
+         *
+         * A predicate function to check the area given by
+         * [sector, sector + len) is in sync.
+         *
+         * If -EWOULDBLOCK is returned the state of the region is
+         * unknown, typically this will result in a read being
+         * passed to a daemon to deal with, since a daemon is
+         * allowed to block.
+         */
+        int (*in_sync)(struct dirty_log *log, region_t region, int can_block);
+
+        /*
+         * Flush the current log state (eg, to disk).  This
+         * function may block.
+         */
+        int (*flush)(struct dirty_log *log);
+
+        /*
+         * Mark an area as clean or dirty.  These functions may
+         * block, though for performance reasons blocking should
+         * be extremely rare (eg, allocating another chunk of
+         * memory for some reason).
+         */
+        void (*mark_region)(struct dirty_log *log, region_t region);
+        void (*clear_region)(struct dirty_log *log, region_t region);
+
+        /*
+         * Returns: <0 (error), 0 (no region), 1 (region)
+         *
+         * The mirrord will need perform recovery on regions of
+         * the mirror that are in the NOSYNC state.  This
+         * function asks the log to tell the caller about the
+         * next region that this machine should recover.
+         *
+         * Do not confuse this function with 'in_sync()', one
+         * tells you if an area is synchronised, the other
+         * assigns recovery work.
+        */
+        int (*get_resync_work)(struct dirty_log *log, region_t *region);
+
+        /*
+         * This notifies the log that the resync of an area has
+         * been completed.  The log should then mark this region
+         * as CLEAN.
+         */
+        void (*complete_resync_work)(struct dirty_log *log,
+                                     region_t region, int success);
+
+        /*
+         * Returns the number of regions that are in sync.
+         */
+        region_t (*get_sync_count)(struct dirty_log *log);
+
+        /*
+         * Support function for mirror status requests.
+         */
+        int (*status)(struct dirty_log *log, status_type_t status_type,
+                      char *result, unsigned int maxlen);
+};
+
+int dm_register_dirty_log_type(struct dirty_log_type *type);
+int dm_unregister_dirty_log_type(struct dirty_log_type *type);
+
+
+/*
+ * Make sure you use these two functions, rather than calling
+ * type->constructor/destructor() directly.
+ */
+struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
+                                      unsigned int argc, char **argv);
+void dm_destroy_dirty_log(struct dirty_log *log);
+
+/*
+ * init/exit functions.
+ */
+int dm_dirty_log_init(void);
+void dm_dirty_log_exit(void);
+
+#endif