• NeilBrown's avatar
    [PATCH] md: Split disks array out of raid5 conf structure so it is easier to grow · b55e6bfc
    NeilBrown authored
    The remainder of this batch implements raid5 reshaping.  Currently the only
    shape change that is supported is added a device, but it is envisioned that
    changing the chunksize and layout will also be supported, as well as changing
    the level (e.g.  1->5, 5->6).
    
    The reshape process naturally has to move all of the data in the array, and so
    should be used with caution.  It is believed to work, and some testing does
    support this, but wider testing would be great for increasing my confidence.
    
    You will need a version of mdadm newer than 2.3.1 to make use of raid5 growth.
     This is because mdadm need to take a copy of a 'critical section' at the
    start of the array incase there is a crash at an awkward moment.  On restart,
    mdadm will restore the critical section and allow reshape to continue.
    
    I hope to release a 2.4-pre by early next week - it still needs a little more
    polishing.
    
    This patch:
    
    Previously the array of disk information was included in the raid5 'conf'
    structure which was allocated to an appropriate size.  This makes it awkward
    to change the size of that array.  So we split it off into a separate
    kmalloced array which will require a little extra indexing, but is much easier
    to grow.
    Signed-off-by: default avatarNeil Brown <neilb@suse.de>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    b55e6bfc
raid5.c 59.8 KB