[Bugs] [Bug 1190734] Enhancement to readdir for tiered volumes

bugzilla at redhat.com bugzilla at redhat.com
Wed Mar 18 11:47:47 UTC 2015


https://bugzilla.redhat.com/show_bug.cgi?id=1190734



--- Comment #8 from Anand Avati <aavati at redhat.com> ---
COMMIT: http://review.gluster.org/9688 committed in master by Vijay Bellur
(vbellur at redhat.com) 
------
commit a216745e5db3fdb4fa8d625c971e70f8d0e34d23
Author: Dan Lambright <dlambrig at redhat.com>
Date:   Wed Feb 18 14:49:50 2015 -0500

    cluster/dht: Change the subvolume encoding in d_off to be a "global"
    position in the graph rather than relative (local) to a particular
    translator.

    Encoding the volume in this way allows a single translator to manage
    which brick is currently being scanned for directory entries. Using a
    single translator minimizes allocated bits in the d_off. It also allows
    multiple DHT translators in the same graph to have a common frame of
    reference (the graph position) for which brick is being read. Multiple
    DHT translators are needed for the Tiering feature.

    The fix builds off a previous change (9332) which removed subvolume
    encoding from AFR. The fix makes an equivalent change to the EC
    translator.

    More background can be found in fix 9332 and gluster-dev discussions [1].

    DHT and AFR/EC are responsibile (as before) for choosing which brick to
    enumerate directory entries in over the readdir lifecycle.

    The client translator receiving the readdir fop encodes the dht_t. It
    is referred to as the "leaf node" in the graph and corresponds to the
    brick being scanned.

    When DHT decodes the d_off, it translates the leaf node to a local
    subvolume, which represents the next node in the graph leading to
    the brick.

    Tracking of leaf nodes is done in common utility functions. Leaf nodes
    counts and positional information are updated on a graph switch.

    [1] www.gluster.org/pipermail/gluster-devel/2015-January/043592.html

    Change-Id: Iaf0ea86d7046b1ceadbad69d88707b243077ebc8
    BUG: 1190734
    Signed-off-by: Dan Lambright <dlambrig at redhat.com>
    Reviewed-on: http://review.gluster.org/9688
    Reviewed-by: Xavier Hernandez <xhernandez at datalab.es>
    Reviewed-by: Krishnan Parthasarathi <kparthas at redhat.com>
    Reviewed-by: Vijay Bellur <vbellur at redhat.com>
    Tested-by: Vijay Bellur <vbellur at redhat.com>

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