[PATCH] md: attempt to auto-correct read errors in raid1

On a read-error we suspend the array, then synchronously read the block from
other arrays until we find one where we can read it.  Then we try writing the
good data back everywhere and make sure it works.  If any write or subsequent
read fails, only then do we fail the device out of the array.

To be able to suspend the array, we need to also keep track of how many
requests are queued for handling by raid1d.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/raid/raid1.h b/include/linux/raid/raid1.h
index c55674252533..cbe4238d3f9f 100644
--- a/include/linux/raid/raid1.h
+++ b/include/linux/raid/raid1.h
@@ -46,6 +46,7 @@ struct r1_private_data_s {
         spinlock_t              resync_lock;
         int                     nr_pending;
         int                     nr_waiting;
+        int                     nr_queued;
         int                     barrier;
         sector_t                next_resync;
         int                     fullsync;  /* set to 1 if a full sync is needed,
@@ -57,6 +58,8 @@ struct r1_private_data_s {
 
         struct pool_info        *poolinfo;
 
+        struct page             *tmppage;
+
         mempool_t *r1bio_pool;
         mempool_t *r1buf_pool;
 };