• Heinz Mauelshagen's avatar
    dm raid: add raid4/5/6 journal write-back support via journal_mode option · 6e53636f
    Heinz Mauelshagen authored
    Commit 63c32ed4 ("dm raid: add raid4/5/6 journaling support") added
    journal support to close the raid4/5/6 "write hole" -- in terms of
    writethrough caching.
    
    Introduce a "journal_mode" feature and use the new
    r5c_journal_mode_set() API to add support for switching the journal
    device's cache mode between write-through (the current default) and
    write-back.
    
    NOTE: If the journal device is not layered on resilent storage and it
    fails, write-through mode will cause the "write hole" to reoccur.  But
    if the journal fails while in write-back mode it will cause data loss
    for any dirty cache entries unless resilent storage is used for the
    journal.
    Signed-off-by: default avatarHeinz Mauelshagen <heinzm@redhat.com>
    Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
    6e53636f
dm-raid.c 112 KB