Commit 75b8e04b authored by Heinz Mauelshagen's avatar Heinz Mauelshagen Committed by Mike Snitzer
Browse files

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: default avatarHeinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 86f1152b

drivers/md/dm-raid.c

+28 −2
Original line number Diff line number Diff line 
/*

 * 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,

CRA Git | Maintained and supported by SUSTech CRA and CCSE