md/raid1: improve handling of pages allocated for write-behind.

The current handling and freeing of these pages is a bit fragile.
We only keep the list of allocated pages in each bio, so we need to
still have a valid bio when freeing the pages, which is a bit clumsy.

So simply store the allocated page list in the r1_bio so it can easily
be found and freed when we are finished with the r1_bio.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index cbfdf1a6acd9..5fc4ca1af863 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -94,7 +94,9 @@ struct r1bio_s {
         int                     read_disk;
 
         struct list_head        retry_list;
-        struct bitmap_update    *bitmap_update;
+        /* Next two are only valid when R1BIO_BehindIO is set */
+        struct page             **behind_pages;
+        int                     behind_page_count;
         /*
          * if the IO is in WRITE direction, then multiple bios are used.
          * We choose the number when they are allocated.