bcachefs: remove heap-related macros and switch to generic min_heap

bcachefs: remove heap-related macros and switch to generic min_heap

Drop the heap-related macros from bcachefs and replacing them with the
generic min_heap implementation from include/linux.  By doing so, code
readability is improved by using functions instead of macros.  Moreover,
the min_heap implementation in include/linux adopts a bottom-up variation
compared to the textbook version currently used in bcachefs.  This
bottom-up variation allows for approximately 50% reduction in the number
of comparison operations during heap siftdown, without changing the number
of swaps, thus making it more efficient.

[visitorckw@gmail.com: fix missing assignment of minimum element]
Link: https://lkml.kernel.org/r/20240602174828.1955320-1-visitorckw@gmail.com
Link: https://lkml.kernel.org/ioyfizrzq7w7mjrqcadtzsfgpuntowtjdw5pgn4qhvsdp4mqqg@nrlek5vmisbu
Link: https://lkml.kernel.org/r/20240524152958.919343-17-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Acked-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Coly Li <colyli@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Sakai <msakai@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>