This adds the block allocator performance enhancement introduced in LU-12103 to CentOS 7.7, RHEL 8.x, Ubuntu 5.0 and 5.4 mainline kernels.

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Block allocator uses some heuristic while choosing a group to allocate new blocks. This works good in most cases, but take a time for large low-free-space partition. The algorithm should be adjusted for this special case.