1. 05 9月, 2009 1 次提交
  2. 22 6月, 2009 1 次提交
    • J
      dm raid1: add userspace log · f5db4af4
      Jonthan Brassow 提交于
      This patch contains a device-mapper mirror log module that forwards
      requests to userspace for processing.
      
      The structures used for communication between kernel and userspace are
      located in include/linux/dm-log-userspace.h.  Due to the frequency,
      diversity, and 2-way communication nature of the exchanges between
      kernel and userspace, 'connector' was chosen as the interface for
      communication.
      
      The first log implementations written in userspace - "clustered-disk"
      and "clustered-core" - support clustered shared storage.   A userspace
      daemon (in the LVM2 source code repository) uses openAIS/corosync to
      process requests in an ordered fashion with the rest of the nodes in the
      cluster so as to prevent log state corruption.  Other implementations
      with no association to LVM or openAIS/corosync, are certainly possible.
      
      (Imagine if two machines are writing to the same region of a mirror.
      They would both mark the region dirty, but you need a cluster-aware
      entity that can handle properly marking the region clean when they are
      done.  Otherwise, you might clear the region when the first machine is
      done, not the second.)
      Signed-off-by: NJonathan Brassow <jbrassow@redhat.com>
      Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      f5db4af4