From d1901ef099c38afd11add4cfb3312c02ef21ec4a Mon Sep 17 00:00:00 2001 From: =?utf8?q?Tom=C3=A1=C5=A1=20Hodek?= Date: Mon, 23 Feb 2015 11:00:38 +1100 Subject: [PATCH] md/raid1: fix read balance when a drive is write-mostly. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When a drive is marked write-mostly it should only be the target of reads if there is no other option. This behaviour was broken by commit 9dedf60313fa4dddfd5b9b226a0ef12a512bf9dc md/raid1: read balance chooses idlest disk for SSD which causes a write-mostly device to be *preferred* is some cases. Restore correct behaviour by checking and setting best_dist_disk and best_pending_disk rather than best_disk. We only need to test one of these as they are both changed from -1 or >=0 at the same time. As we leave min_pending and best_dist unchanged, any non-write-mostly device will appear better than the write-mostly device. Reported-by: Tomáš Hodek Reported-by: Dark Penguin Signed-off-by: NeilBrown Link: http://marc.info/?l=linux-raid&m=135982797322422 Fixes: 9dedf60313fa4dddfd5b9b226a0ef12a512bf9dc Cc: stable@vger.kernel.org (3.6+) --- Reading git-format-patch failed