[RFC][PATCH 3/10] I/O context inheritance

[Hirokazu Takahashi <taka@valinux.co.jp>]

Make every bio points the iocontext of the process which originally
generated an I/O request. (part 2)

 - Assign the iocontext which the source bio has to a bio when it is
   allocated as a bounce buffer.
 - Assign the iocontext which the source bio has to bios when the source
   bio is split into several ones, which some device mapper modules require.

Signed-off-by: Hirokazu Takahashi <taka@valinux.co.jp>


--- linux-2.6.25.bio0/mm/bounce.c	2008-04-22 15:48:32.000000000 +0900
+++ linux-2.6.25/mm/bounce.c	2008-04-22 15:51:33.000000000 +0900
@@ -195,8 +195,11 @@ static void __blk_queue_bounce(struct re
 		/*
 		 * irk, bounce it
 		 */
-		if (!bio)
+		if (!bio) {
 			bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
+			put_io_context(bio->bi_io_context);
+			bio->bi_io_context = ioc_object_link((*bio_orig)->bi_io_context);
+		}
 
 		to = bio->bi_io_vec + i;
 
--- linux-2.6.25.bio0/drivers/md/dm.c	2008-04-22 15:48:33.000000000 +0900
+++ linux-2.6.25/drivers/md/dm.c	2008-04-22 17:16:49.000000000 +0900
@@ -665,6 +665,7 @@ static struct bio *split_bvec(struct bio
 	clone->bi_size = to_bytes(len);
 	clone->bi_io_vec->bv_offset = offset;
 	clone->bi_io_vec->bv_len = clone->bi_size;
+	clone->bi_io_context = ioc_object_link(bio->bi_io_context);
 
 	return clone;
 }