aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorTomáš Hodek <tomas.hodek@volny.cz>2015-02-23 11:00:38 +1100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-06 14:40:53 -0800
commitb581e762b1a452ac94d452117a6c953f4d011767 (patch)
treebfaa0d05b640d08e5501854e69cbb0ba2cc799e5
parent58f0e96a4358f164f3857ee0d609d1b75a3ccf7d (diff)
downloadlinux-linaro-stable-b581e762b1a452ac94d452117a6c953f4d011767.tar.gz
md/raid1: fix read balance when a drive is write-mostly.
commit d1901ef099c38afd11add4cfb3312c02ef21ec4a upstream. 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 <tomas.hodek@volny.cz> Reported-by: Dark Penguin <darkpenguin@yandex.ru> Signed-off-by: NeilBrown <neilb@suse.de> Link: http://marc.info/?l=linux-raid&m=135982797322422 Fixes: 9dedf60313fa4dddfd5b9b226a0ef12a512bf9dc Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/md/raid1.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index e885dbf08c40..86ac4a4ccc01 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -557,7 +557,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
if (test_bit(WriteMostly, &rdev->flags)) {
/* Don't balance among write-mostly, just
* use the first as a last resort */
- if (best_disk < 0) {
+ if (best_dist_disk < 0) {
if (is_badblock(rdev, this_sector, sectors,
&first_bad, &bad_sectors)) {
if (first_bad < this_sector)
@@ -566,7 +566,8 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
best_good_sectors = first_bad - this_sector;
} else
best_good_sectors = sectors;
- best_disk = disk;
+ best_dist_disk = disk;
+ best_pending_disk = disk;
}
continue;
}