From 671488cc25f7c194c7c7a9f258bab1df17a6ff69 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 23 Dec 2011 10:17:52 +1100 Subject: [PATCH] md/raid5: allow each slot to have an extra replacement device Just enhance data structures to record a second device per slot to be used as a 'replacement' device, replacing the original. We also have a second bio in each slot in each stripe_head. This will only be used when writing to the array - we need to write to both the original and the replacement at the same time, so will need two bios. For now, only try using the replacement drive for aligned-reads. In this case, we prefer the replacement if it has been recovered far enough, otherwise use the original. This includes a small enhancement. Previously we would only do aligned reads if the target device was fully recovered. Now we also do them if it has recovered far enough. Reviewed-by: Dan Williams Signed-off-by: NeilBrown --- Reading git-format-patch failed