1. 18 Aug, 2014 2 commits
    • NeilBrown's avatar
      md/raid6: avoid data corruption during recovery of double-degraded RAID6 · 9c4bdf69
      NeilBrown authored
      During recovery of a double-degraded RAID6 it is possible for
      some blocks not to be recovered properly, leading to corruption.
      
      If a write happens to one block in a stripe that would be written to a
      missing device, and at the same time that stripe is recovering data
      to the other missing device, then that recovered data may not be written.
      
      This patch skips, in the double-degraded case, an optimisation that is
      only safe for single-degraded arrays.
      
      Bug was introduced in 2.6.32 and fix is suitable for any kernel since
      then.  In an older kernel with separate handle_stripe5() and
      handle_stripe6() functions the patch must change handle_stripe6().
      
      Cc: stable@vger.kernel.org (2.6.32+)
      Fixes: 6c0069c0
      Cc: Yuri Tikhonov <yur@emcraft.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Reported-by: default avatar"Manibalan P" <pmanibalan@amiindia.co.in>
      Tested-by: default avatar"Manibalan P" <pmanibalan@amiindia.co.in>
      Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1090423Signed-off-by: default avatarNeilBrown <neilb@suse.de>
      Acked-by: default avatarDan Williams <dan.j.williams@intel.com>
      9c4bdf69
    • NeilBrown's avatar
      md/raid5: avoid livelock caused by non-aligned writes. · a40687ff
      NeilBrown authored
      If a stripe in a raid6 array received a write to each data block while
      the array is degraded, and if any of these writes to a missing device
      are not page-aligned, then a live-lock happens.
      
      In this case the P and Q blocks need to be read so that the part of
      the missing block which is *not* being updated by the write can be
      constructed.  Due to a logic error, these blocks are not loaded, so
      the update cannot proceed and the stripe is 'handled' repeatedly in an
      infinite loop.
      
      This bug is unlikely as most writes are page aligned.  However as it
      can lead to a livelock it is suitable for -stable.  It was introduced
      in 3.16.
      
      Cc: stable@vger.kernel.org (v3.16)
      Fixed: 67f45548Signed-off-by: default avatarNeilBrown <neilb@suse.de>
      a40687ff
  2. 16 Aug, 2014 38 commits