[PATCH] Device-mapper: kcopyd

Add kcopyd - a daemon for copying regions of block devices around in an
efficient manner.  Multiple destinations can be specified for a copy.
Designed to perform well both with many small chunks or few large chunks.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/Makefile

@@ -3,7 +3,7 @@
 #
 
 dm-mod-objs	:= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
-		   dm-ioctl.o dm-io.o
+		   dm-ioctl.o dm-io.o kcopyd.o
 raid6-objs	:= raid6main.o raid6algos.o raid6recov.o raid6tables.o \
 		   raid6int1.o raid6int2.o raid6int4.o \
 		   raid6int8.o raid6int16.o raid6int32.o \

drivers/md/dm.c

@@ -153,6 +153,7 @@ static struct {
 	xx(dm_target)
 	xx(dm_linear)
 	xx(dm_stripe)
+	xx(kcopyd)
 	xx(dm_interface)
 #undef xx
 };

drivers/md/dm.h

@@ -177,6 +177,9 @@ void dm_linear_exit(void);
 int dm_stripe_init(void);
 void dm_stripe_exit(void);
 
+int kcopyd_init(void);
+void kcopyd_exit(void);
+
 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 
 #endif

drivers/md/kcopyd.h

+/*
+ * Copyright (C) 2001 Sistina Software
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_KCOPYD_H
+#define DM_KCOPYD_H
+
+#include "dm-io.h"
+
+int kcopyd_init(void);
+void kcopyd_exit(void);
+
+/* FIXME: make this configurable */
+#define KCOPYD_MAX_REGIONS 8
+
+#define KCOPYD_IGNORE_ERROR 1
+
+/*
+ * To use kcopyd you must first create a kcopyd client object.
+ */
+struct kcopyd_client;
+int kcopyd_client_create(unsigned int num_pages, struct kcopyd_client **result);
+void kcopyd_client_destroy(struct kcopyd_client *kc);
+
+/*
+ * Submit a copy job to kcopyd.  This is built on top of the
+ * previous three fns.
+ *
+ * read_err is a boolean,
+ * write_err is a bitset, with 1 bit for each destination region
+ */
+typedef void (*kcopyd_notify_fn)(int read_err,
+				 unsigned int write_err, void *context);
+
+int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from,
+		unsigned int num_dests, struct io_region *dests,
+		unsigned int flags, kcopyd_notify_fn fn, void *context);
+
+#endif