dm raid: add discard support for RAID levels 1 and 10
Discard support is not enabled for RAID levels 4, 5, and 6 at this time
due to concerns about unreliable discard_zeroes_data support on some
hardware. Otherwise, discards could cause stripe data corruption
(classic example of bad apples spoiling the bunch).
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 4880b69..030e2d6 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1,6 +1,6 @@
/*
* Copyright (C) 2010-2011 Neil Brown
- * Copyright (C) 2010-2011 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2010-2014 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
@@ -1150,6 +1150,27 @@
}
/*
+ * Enable/disable discard support on RAID set depending on RAID level.
+ */
+static void configure_discard_support(struct dm_target *ti, struct raid_set *rs)
+{
+ /* Assume discards not supported until after checks below. */
+ ti->discards_supported = false;
+
+ /* RAID level 4,5,6 require discard_zeroes_data for data integrity! */
+ if (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6)
+ return; /* discard_zeroes_data cannot be trusted as reliable */
+
+ ti->discards_supported = true;
+
+ /*
+ * RAID1 and RAID10 personalities require bio splitting,
+ */
+ ti->split_discard_bios = true;
+ ti->num_discard_bios = 1;
+}
+
+/*
* Construct a RAID4/5/6 mapping:
* Args:
* <raid_type> <#raid_params> <raid_params> \
@@ -1231,6 +1252,11 @@
ti->private = rs;
ti->num_flush_bios = 1;
+ /*
+ * Disable/enable discard support on RAID set.
+ */
+ configure_discard_support(ti, rs);
+
mutex_lock(&rs->md.reconfig_mutex);
ret = md_run(&rs->md);
rs->md.in_sync = 0; /* Assume already marked dirty */
@@ -1652,7 +1678,7 @@
static struct target_type raid_target = {
.name = "raid",
- .version = {1, 5, 2},
+ .version = {1, 6, 0},
.module = THIS_MODULE,
.ctr = raid_ctr,
.dtr = raid_dtr,