md/raid1: fix test for 'was read error from last working device'.
md/raid1: fix test for 'was read error from last working device'.

When we get a read error from the last working device, we don't
try to repair it, and don't fail the device.  We simple report a
read error to the caller.

However the current test for 'is this the last working device' is
wrong.
When there is only one fully working device, it assumes that a
non-faulty device is that device.  However a spare which is rebuilding
would be non-faulty but so not the only working device.

So change the test from "!Faulty" to "In_sync".  If ->degraded says
there is only one fully working device and this device is in_sync,
this must be the one.

This bug has existed since we allowed read_balance to read from
a recovering spare in v3.0

Reported-and-tested-by: Alexander Lyakas <dd9708ec40e6f738e4ae235182bdaf2321900767@gmail.com>
Fixes: 76073054c95b ("md/raid1: clean up read_balance.")
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org (v3.0+)
Signed-off-by: NeilBrown <1c00aa603bb92d594c03cff60ecf8e63b2a5bcb1@suse.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs