Buddy allocator request normalization

Request normalization(ext4_mb_normalize_request()) is key buddy allocator step. Required range size is decided at this moment.

Request is not normalised:

  • for metadata
  • is exact block requested
  • caller ask not normalise

Based on file size (offset + requested size) block count is round to the nearest large from list: 16k, 32k, 64k, 128k, 256k, 512k, 1M, 2M, 4M, 8M.

Already allocated and preallocated ranges are excluded.

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