[PATCH] md: remove extra loop from copy_data

copy_data currently loops over bio's in a list, but the caller also does the
same looping, sometimes with extra work.  So remove the loop from copy_data.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/raid5.c

@@ -612,11 +612,10 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
 
 
 /*
- * Copy data between a page in the stripe cache, and one or more bion
- * The page could align with the middle of the bio, or there could be 
- * several bion, each with several bio_vecs, which cover part of the page
- * Multiple bion are linked together on bi_next.  There may be extras
- * at the end of this list.  We ignore them.
+ * Copy data between a page in the stripe cache, and a bio.
+ * There are no alignment or size guarantees between the page or the
+ * bio except that there is some overlap.
+ * All iovecs in the bio must be considered.
  */
 static void copy_data(int frombio, struct bio *bio,
 		     struct page *page,
@@ -625,10 +624,8 @@ static void copy_data(int frombio, struct bio *bio,
 	char *pa = page_address(page);
 	struct bio_vec *bvl;
 	int i;
-
-	for (;bio && bio->bi_sector < sector+STRIPE_SECTORS;
-	      bio = r5_next_bio(bio, sector) ) {
 	int page_offset;
+
 	if (bio->bi_sector >= sector)
 		page_offset = (signed)(bio->bi_sector - sector) * 512;
 	else
@@ -660,7 +657,6 @@ static void copy_data(int frombio, struct bio *bio,
 			break;
 		page_offset +=  len;
 	}
-	}
 }
 
 #define check_xor() 	do { 						\

drivers/md/raid6main.c

@@ -670,10 +670,8 @@ static void copy_data(int frombio, struct bio *bio,
 	char *pa = page_address(page);
 	struct bio_vec *bvl;
 	int i;
-
-	for (;bio && bio->bi_sector < sector+STRIPE_SECTORS;
-	      bio = r5_next_bio(bio, sector) ) {
 	int page_offset;
+
 	if (bio->bi_sector >= sector)
 		page_offset = (signed)(bio->bi_sector - sector) * 512;
 	else
@@ -705,7 +703,6 @@ static void copy_data(int frombio, struct bio *bio,
 			break;
 		page_offset +=  len;
 	}
-	}
 }
 
 #define check_xor() 	do { 						\