• Jonathan Brassow's avatar
    DM RAID: Add support for MD's RAID10 "far" and "offset" algorithms · fe5d2f4a
    Jonathan Brassow authored
    
    
    DM RAID:  Add support for MD's RAID10 "far" and "offset" algorithms
    
    Until now, dm-raid.c only supported the "near" algorthm of MD's RAID10
    implementation.  This patch adds support for the "far" and "offset"
    algorithms, but only with the improved redundancy that is brought with
    the introduction of the 'use_far_sets' bit, which shifts copied stripes
    according to smaller sets vs the entire array.  That is, the 17th bit
    of the 'layout' variable that defines the RAID10 implementation will
    always be set.   (More information on how the 'layout' variable selects
    the RAID10 algorithm can be found in the opening comments of
    drivers/md/raid10.c.)
    
    Signed-off-by: default avatarJonathan Brassow <jbrassow@redhat.com>
    Signed-off-by: default avatarNeilBrown <neilb@suse.de>
    fe5d2f4a