md/raid10: simplify the splitting of requests.
raid10 splits requests in two different ways for two different
reasons.
First, bio_split() is used to ensure the bio fits with a chunk.
Second, multiple r10bio structures are allocated to represent the
different sections that need to go to different devices, to avoid
known bad blocks.
This can be simplified to just use bio_split() once, and not to use
multiple r10bios.
We delay the split until we know a maximum bio size that can
be handled with a single r10bio, and then split the bio and queue
the remainder for later handling.
As with raid1, we allocate a new bio_set to help with the splitting.
It is not correct to use fs_bio_set in a device driver.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
index 3162615..735ce1a 100644
--- a/drivers/md/raid10.h
+++ b/drivers/md/raid10.h
@@ -82,6 +82,7 @@ struct r10conf {
mempool_t *r10bio_pool;
mempool_t *r10buf_pool;
struct page *tmppage;
+ struct bio_set *bio_split;
/* When taking over an array from a different personality, we store
* the new thread here until we fully activate the array.