Allow the map method to pass some context to the endio method.
--- diff/drivers/md/dm-linear.c	2002-11-29 09:44:59.000000000 +0000
+++ source/drivers/md/dm-linear.c	2003-01-10 11:49:27.000000000 +0000
@@ -64,7 +64,8 @@
 	kfree(lc);
 }
 
-static int linear_map(struct dm_target *ti, struct buffer_head *bh, int rw)
+static int linear_map(struct dm_target *ti, struct buffer_head *bh, int rw,
+		      void **map_context)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
 
--- diff/drivers/md/dm-snapshot.c	2003-01-10 10:47:54.000000000 +0000
+++ source/drivers/md/dm-snapshot.c	2003-01-10 11:49:27.000000000 +0000
@@ -785,7 +785,8 @@
 	    (bh->b_rsector & s->chunk_mask);
 }
 
-static int snapshot_map(struct dm_target *ti, struct buffer_head *bh, int rw)
+static int snapshot_map(struct dm_target *ti, struct buffer_head *bh, int rw,
+			void **map_context)
 {
 	struct exception *e;
 	struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
@@ -1028,7 +1029,8 @@
 	dm_put_device(ti, dev);
 }
 
-static int origin_map(struct dm_target *ti, struct buffer_head *bh, int rw)
+static int origin_map(struct dm_target *ti, struct buffer_head *bh, int rw,
+		      void **map_context)
 {
 	struct dm_dev *dev = (struct dm_dev *) ti->private;
 	bh->b_rdev = dev->dev;
--- diff/drivers/md/dm-stripe.c	2002-11-29 09:46:30.000000000 +0000
+++ source/drivers/md/dm-stripe.c	2003-01-10 11:49:27.000000000 +0000
@@ -186,7 +186,8 @@
 	kfree(sc);
 }
 
-static int stripe_map(struct dm_target *ti, struct buffer_head *bh, int rw)
+static int stripe_map(struct dm_target *ti, struct buffer_head *bh, int rw,
+		      void **context)
 {
 	struct stripe_c *sc = (struct stripe_c *) ti->private;
 
--- diff/drivers/md/dm-target.c	2003-01-10 10:20:03.000000000 +0000
+++ source/drivers/md/dm-target.c	2003-01-10 11:49:27.000000000 +0000
@@ -159,7 +159,8 @@
 	/* empty */
 }
 
-static int io_err_map(struct dm_target *ti, struct buffer_head *bh, int rw)
+static int io_err_map(struct dm_target *ti, struct buffer_head *bh, int rw,
+		      void **map_context)
 {
 	return -EIO;
 }
--- diff/drivers/md/dm.c	2003-01-10 11:43:50.000000000 +0000
+++ source/drivers/md/dm.c	2003-01-10 11:49:27.000000000 +0000
@@ -30,6 +30,7 @@
 
 	struct dm_target *ti;
 	int rw;
+	void *map_context;
 	void (*end_io) (struct buffer_head * bh, int uptodate);
 	void *context;
 };
@@ -320,7 +321,8 @@
 	dm_endio_fn endio = io->ti->type->end_io;
 
 	if (endio) {
-		r = endio(io->ti, bh, io->rw, uptodate ? 0 : -EIO);
+		r = endio(io->ti, bh, io->rw, uptodate ? 0 : -EIO,
+			  io->map_context);
 		if (r < 0)
 			uptodate = 0;
 
@@ -354,7 +356,7 @@
 	if (!ti)
 		return -EINVAL;
 
-	r = ti->type->map(ti, bh, rw);
+	r = ti->type->map(ti, bh, rw, &io->map_context);
 
 	if (r >= 0) {
 		/* hook the end io request fn */
@@ -469,6 +471,7 @@
 {
 	struct buffer_head bh;
 	struct dm_target *ti;
+	void *map_context;
 	int r;
 
 	if (test_bit(DMF_BLOCK_IO, &md->flags)) {
@@ -490,7 +493,8 @@
 	ti = dm_table_find_target(md->map, bh.b_rsector);
 
 	/* do the mapping */
-	r = ti->type->map(ti, &bh, READ);
+	r = ti->type->map(ti, &bh, READ, &map_context);
+	ti->type->end_io(ti, &bh, READ, 0, map_context);
 
 	if (!r) {
 		*r_dev = bh.b_rdev;
--- diff/include/linux/device-mapper.h	2003-01-10 11:36:08.000000000 +0000
+++ source/include/linux/device-mapper.h	2003-01-10 11:49:27.000000000 +0000
@@ -33,7 +33,8 @@
  * = 0: The target will handle the io by resubmitting it later
  * > 0: simple remap complete
  */
-typedef int (*dm_map_fn) (struct dm_target *ti, struct buffer_head *bh, int rw);
+typedef int (*dm_map_fn) (struct dm_target *ti, struct buffer_head *bh, int rw,
+			  void **map_context);
 
 /*
  * Returns:
@@ -43,7 +44,8 @@
  *       multipath target might want to requeue a failed io).
  */
 typedef int (*dm_endio_fn) (struct dm_target *ti,
-			    struct buffer_head *bh, int rw, int error);
+			    struct buffer_head *bh, int rw, int error,
+			    void *map_context);
 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
 			     char *result, int maxlen);