dm raid: add region_size parameter
Allow the user to specify the region_size.
Ensures that the supplied value meets md's constraints, viz. the number of
regions does not exceed 2^21.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 4f9dd3c..be4419a 100644
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -52,6 +52,10 @@
[max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
[max_write_behind <sectors>] See '-write-behind=' (man mdadm)
[stripe_cache <sectors>] Stripe cache size (higher RAIDs only)
+ [region_size <sectors>]
+ The region_size multiplied by the number of regions is the
+ logical size of the array. The bitmap records the device
+ synchronisation state for each region.
<#raid_devs>: The number of devices composing the array.
Each device consists of two entries. The first is the device
