v4.19.13 snapshot.
diff --git a/include/linux/dm-dirty-log.h b/include/linux/dm-dirty-log.h
new file mode 100644
index 0000000..7084503
--- /dev/null
+++ b/include/linux/dm-dirty-log.h
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2003 Sistina Software
+ * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
+ *
+ * Device-Mapper dirty region log.
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef _LINUX_DM_DIRTY_LOG
+#define _LINUX_DM_DIRTY_LOG
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include <linux/device-mapper.h>
+
+typedef sector_t region_t;
+
+struct dm_dirty_log_type;
+
+struct dm_dirty_log {
+ struct dm_dirty_log_type *type;
+ int (*flush_callback_fn)(struct dm_target *ti);
+ void *context;
+};
+
+struct dm_dirty_log_type {
+ const char *name;
+ struct module *module;
+
+ /* For internal device-mapper use */
+ struct list_head list;
+
+ int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
+ unsigned argc, char **argv);
+ void (*dtr)(struct dm_dirty_log *log);
+
+ /*
+ * There are times when we don't want the log to touch
+ * the disk.
+ */
+ int (*presuspend)(struct dm_dirty_log *log);
+ int (*postsuspend)(struct dm_dirty_log *log);
+ int (*resume)(struct dm_dirty_log *log);
+
+ /*
+ * Retrieves the smallest size of region that the log can
+ * deal with.
+ */
+ uint32_t (*get_region_size)(struct dm_dirty_log *log);
+
+ /*
+ * A predicate to say whether a region is clean or not.
+ * May block.
+ */
+ int (*is_clean)(struct dm_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 dm_dirty_log *log, region_t region,
+ int can_block);
+
+ /*
+ * Flush the current log state (eg, to disk). This
+ * function may block.
+ */
+ int (*flush)(struct dm_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 dm_dirty_log *log, region_t region);
+ void (*clear_region)(struct dm_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 dm_dirty_log *log, region_t *region);
+
+ /*
+ * This notifies the log that the resync status of a region
+ * has changed. It also clears the region from the recovering
+ * list (if present).
+ */
+ void (*set_region_sync)(struct dm_dirty_log *log,
+ region_t region, int in_sync);
+
+ /*
+ * Returns the number of regions that are in sync.
+ */
+ region_t (*get_sync_count)(struct dm_dirty_log *log);
+
+ /*
+ * Support function for mirror status requests.
+ */
+ int (*status)(struct dm_dirty_log *log, status_type_t status_type,
+ char *result, unsigned maxlen);
+
+ /*
+ * is_remote_recovering is necessary for cluster mirroring. It provides
+ * a way to detect recovery on another node, so we aren't writing
+ * concurrently. This function is likely to block (when a cluster log
+ * is used).
+ *
+ * Returns: 0, 1
+ */
+ int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
+};
+
+int dm_dirty_log_type_register(struct dm_dirty_log_type *type);
+int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type);
+
+/*
+ * Make sure you use these two functions, rather than calling
+ * type->constructor/destructor() directly.
+ */
+struct dm_dirty_log *dm_dirty_log_create(const char *type_name,
+ struct dm_target *ti,
+ int (*flush_callback_fn)(struct dm_target *ti),
+ unsigned argc, char **argv);
+void dm_dirty_log_destroy(struct dm_dirty_log *log);
+
+#endif /* __KERNEL__ */
+#endif /* _LINUX_DM_DIRTY_LOG_H */