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DM RAID: Add rebuild capability for RAID10

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DM RAID:  Add code to validate replacement slots for RAID10 arrays

RAID10 can handle 'copies - 1' failures for each mirror group.  This code
ensures the user has provided a valid array - one whose devices specified for
rebuild do not exceed the amount of redundancy available.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Jonathan Brassow 2012-10-11 13:40:24 +11:00 committed by NeilBrown
parent eb6491236f
commit 4ec1e369af
2 changed files with 42 additions and 1 deletions
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9
Documentation/device-mapper/dm-raid.txt
View file

@ -132,3 +132,12 @@ Here we can see the RAID type is raid4, there are 5 devices - all of
which are 'A'live, and the array is 2/490221568 complete with recovery.
Faulty or missing devices are marked 'D'. Devices that are out-of-sync
are marked 'a'.
Version History
---------------
1.0.0 Initial version. Support for RAID 4/5/6
1.1.0 Added support for RAID 1
1.2.0 Handle creation of arrays that contain failed devices.
1.3.0 Added support for RAID 10
1.3.1 Allow device replacement/rebuild for RAID 10

34
drivers/md/dm-raid.c
View file

@ -349,6 +349,7 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
static int validate_rebuild_devices(struct raid_set *rs)
{
unsigned i, rebuild_cnt = 0;
unsigned rebuilds_per_group, copies, d;
if (!(rs->print_flags & DMPF_REBUILD))
return 0;
@ -369,6 +370,37 @@ static int validate_rebuild_devices(struct raid_set *rs)
goto too_many;
break;
case 10:
copies = raid10_md_layout_to_copies(rs->md.layout);
if (rebuild_cnt < copies)
break;
/*
* It is possible to have a higher rebuild count for RAID10,
* as long as the failed devices occur in different mirror
* groups (i.e. different stripes).
*
* Right now, we only allow for "near" copies. When other
* formats are added, we will have to check those too.
*
* When checking "near" format, make sure no adjacent devices
* have failed beyond what can be handled. In addition to the
* simple case where the number of devices is a multiple of the
* number of copies, we must also handle cases where the number
* of devices is not a multiple of the number of copies.
* E.g. dev1 dev2 dev3 dev4 dev5
* A A B B C
* C D D E E
*/
rebuilds_per_group = 0;
for (i = 0; i < rs->md.raid_disks * copies; i++) {
d = i % rs->md.raid_disks;
if (!test_bit(In_sync, &rs->dev[d].rdev.flags) &&
(++rebuilds_per_group >= copies))
goto too_many;
if (!((i + 1) % copies))
rebuilds_per_group = 0;
}
break;
default:
DMERR("The rebuild parameter is not supported for %s",
rs->raid_type->name);
@ -1385,7 +1417,7 @@ static void raid_resume(struct dm_target *ti)
static struct target_type raid_target = {
.name = "raid",
.version = {1, 3, 0},
.version = {1, 3, 1},
.module = THIS_MODULE,
.ctr = raid_ctr,
.dtr = raid_dtr,