[PATCH] FIX: delta_disk can have UnSet value

Delta_disk can be set to UnSet value.
This can a cause to pass wrong parameter to reshape_super().

Signed-off-by: Adam Kwolek <redacted>
---

 Grow.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/Grow.c b/Grow.c
index daf310b..bc015c6 100644
--- a/Grow.c
+++ b/Grow.c

@@ -1575,7 +1575,9 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 
 		if (reshape_super(st, info.component_size, info.new_level,
 				  info.new_layout, info.new_chunk,
-				  info.array.raid_disks + info.delta_disks,
+				  info.delta_disks == UnSet ?
+				     info.array.raid_disks :
+				     info.array.raid_disks + info.delta_disks,
 				  backup_file, devname, quiet)) {
 			rv = 1;
 			goto release;

On Thu, 27 Jan 2011 10:28:28 +0100
Adam Kwolek [off-list ref] wrote:

This is clearly a problem, but I think it is the wrong fix.
If delta_disks is unset, then the new raid_disks number could vary
depending on other values.
E.g. if you has a 4-disk raid5 and ask to convert it to RAID6 without
specifying the number of devices, then it should assume a 5-disk RAID6.
Your change would make it look like a 4-disk RAID6 was requested.

So I think we need to change reshape_super to take a 'delta_disks'
parameter rather than a 'raid_disks' parameter. 
Either that, or figure out the preferred default in advance.
analyse_change does that I think, but it is called later, so we cannot
really use what it produces.

I'm not sure what the best answer is just now - hopefully I'll be able
to look properly on Monday.

NeilBrown