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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>
This commit is contained in:
Heinz Mauelshagen 2014-09-24 17:47:18 +02:00 committed by Mike Snitzer
parent 86f1152b11
commit 75b8e04bbf
1 changed files with 28 additions and 2 deletions
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30
drivers/md/dm-raid.c
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@ -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.
*/
@ -1149,6 +1149,27 @@ static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
return 0;
}
/*
* 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:
@ -1231,6 +1252,11 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
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 void raid_resume(struct dm_target *ti)
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,