[PATCH] Device-mapper: mirroring

Add mirror target.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/Kconfig

@@ -186,5 +186,12 @@ config DM_SNAPSHOT
        ---help---
          Allow volume managers to take writeable snapshots of a device.
 
+config DM_MIRROR
+       tristate "Mirror target (EXPERIMENTAL)"
+       depends on BLK_DEV_DM && EXPERIMENTAL
+       ---help---
+         Allow volume managers to mirror logical volumes, also
+         needed for live data migration tools such as 'pvmove'.
+
 endmenu
 

drivers/md/Makefile

@@ -5,6 +5,7 @@
 dm-mod-objs	:= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
 		   dm-ioctl.o dm-io.o kcopyd.o
 dm-snapshot-objs := dm-snap.o dm-exception-store.o
+dm-mirror-objs	:= dm-log.o dm-raid1.o
 raid6-objs	:= raid6main.o raid6algos.o raid6recov.o raid6tables.o \
 		   raid6int1.o raid6int2.o raid6int4.o \
 		   raid6int8.o raid6int16.o raid6int32.o \
@@ -26,6 +27,7 @@ obj-$(CONFIG_BLK_DEV_MD)	+= md.o
 obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
 obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o
 obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
+obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o
 
 quiet_cmd_unroll = UNROLL  $@
       cmd_unroll = $(PERL) $(srctree)/$(src)/unroll.pl $(UNROLL) \

drivers/md/dm-log.h

+/*
+ * 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.
+	 */
+	sector_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);
+};
+
+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