[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, 1 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 64e7da3701a5..1364a1c97e6f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -461,6 +461,7 @@ int sync_page_io(struct block_device *bdev, sector_t sector, int size,
         bio_put(bio);
         return ret;
 }
+EXPORT_SYMBOL(sync_page_io);
 
 static int read_disk_sb(mdk_rdev_t * rdev, int size)
 {