Bug#628667: mdadm: Write-mostly flag set when adding device

[Anders Boström]

Package: mdadm
Version: 3.1.4-1+8efb9d1
Severity: normal

If I add a device to an degraded raid1 where the write-mostly flag is
set on the only active device in the array, the write-mostly flag is
also set on the added device. The result is that write-mostly is set
on both devices. The write-mostly flag should *not* be copied to the
metadata of an added device.

The use-case it an raid1 array with two devices, A and B. A is much
faster than B, and B is therefore set to write-mostly. Then A breaks
and is replaced with a new fast device, C. C is added to the degraded
array, and get the write-mostly flag set.

/ Anders