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  1. 26 Mar, 2018 6 commits
  2. 01 Mar, 2018 1 commit
    • Hans van Kranenburg's avatar
      btrfs: alloc_chunk: fix DUP stripe size handling · 92e222df
      Hans van Kranenburg authored
      In case of using DUP, we search for enough unallocated disk space on a
      device to hold two stripes.
      
      The devices_info[ndevs-1].max_avail that holds the amount of unallocated
      space found is directly assigned to stripe_size, while it's actually
      twice the stripe size.
      
      Later on in the code, an unconditional division of stripe_size by
      dev_stripes corrects the value, but in the meantime there's a check to
      see if the stripe_size does not exceed max_chunk_size. Since during this
      check stripe_size is twice the amount as intended, the check will reduce
      the stripe_size to max_chunk_size if the actual correct to be used
      stripe_size is more than half the amount of max_chunk_size.
      
      The unconditional division later tries to correct stripe_size, but will
      actually make sure we can't allocate more than half the max_chunk_size.
      
      Fix this by moving the division by dev_stripes before the max chunk size
      check, so it always contains the right value, instead of putting a duct
      tape division in further on to get it fixed again.
      
      Since in all other cases than DUP, dev_stripes is 1, this change only
      affects DUP.
      
      Other attempts in the past were made to fix this:
      * 37db63a4 "Btrfs: fix max chunk size check in chunk allocator" tried
      to fix the same problem, but still resulted in part of the code acting
      on a wrongly doubled stripe_size value.
      * 86db2578 "Btrfs: fix max chunk size on raid5/6" unintentionally
      broke this fix again.
      
      The real problem was already introduced with the rest of the code in
      73c5de00.
      
      The user visible result however will be that the max chunk size for DUP
      will suddenly double, while it's actually acting according to the limits
      in the code again like it was 5 years ago.
      Reported-by: default avatarNaohiro Aota <naohiro.aota@wdc.com>
      Link: https://www.spinics.net/lists/linux-btrfs/msg69752.html
      Fixes: 73c5de00 ("btrfs: quasi-round-robin for chunk allocation")
      Fixes: 86db2578 ("Btrfs: fix max chunk size on raid5/6")
      Signed-off-by: default avatarHans van Kranenburg <hans.van.kranenburg@mendix.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
      [ update comment ]
      Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      92e222df
  3. 05 Feb, 2018 1 commit
  4. 29 Jan, 2018 2 commits
  5. 22 Jan, 2018 30 commits