• Benjamin Marzinski's avatar
    GFS2: Use lvbs for storing rgrp information with mount option · 90306c41
    Benjamin Marzinski authored
    Instead of reading in the resource groups when gfs2 is checking
    for free space to allocate from, gfs2 can store the necessary infromation
    in the resource group's lvb.  Also, instead of searching for unlinked
    inodes in every resource group that's checked for free space, gfs2 can
    store the number of unlinked but inodes in the lvb, and only check for
    unlinked inodes if it will find some.
    The first time a resource group is locked, the lvb must initialized.
    Since this involves counting the unlinked inodes in the resource group,
    this takes a little extra time.  But after that, if the resource group
    is locked with GL_SKIP, the buffer head won't be read in unless it's
    actually needed.
    Enabling the resource groups lvbs is done via the rgrplvb mount option.  If
    this option isn't set, the lvbs will still be set and updated, but they won't
    be verfied or used by the filesystem.  To safely turn on this option, all of
    the nodes mounting the filesystem must be running code with this patch, and
    the filesystem must have been completely unmounted since they were updated.
    Signed-off-by: default avatarBenjamin Marzinski <bmarzins@redhat.com>
    Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>