Date: Mon, 21 Aug 2023 18:44:07 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Justin Pryzby <pryzby@telsasoft.com>,
	Thomas Munro <thomas.munro@gmail.com>,
	David Steele <david@pgmasters.net>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	Bruce Momjian <bruce@momjian.us>, Tom Lane <tgl@sss.pgh.pa.us>,
	Michael Brown <michael.brown@discourse.org>,
	pgsql-hackers@postgresql.org
Subject: Re: should frontend tools use syncfs() ?
Message-ID: <20230822014407.GA449131@nathanxps13>
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On Tue, Aug 22, 2023 at 08:56:26AM +0900, Michael Paquier wrote:
> --- a/src/include/storage/fd.h
> +++ b/src/include/storage/fd.h
> @@ -43,15 +43,11 @@
>  #ifndef FD_H
>  #define FD_H
>  
> +#ifndef FRONTEND
> +
>  #include <dirent.h>
>  #include <fcntl.h>
>  
> Ugh.  So you need this part because pg_rewind's filemap.c includes
> fd.h, and pg_rewind also needs file_utils.h.  This is not the fault of
> your patch, but this does not make the situation better, either..  It
> looks like we need to think harder about this layer.  An improvement
> would be to split file_utils.c so as its frontend-only code is moved
> to OBJS_FRONTEND in a new file with a new header?  It should be OK to
> keep DataDirSyncMethod in file_utils.h as long as the split is clean.

I'm hoping there's a simpler path forward here.  pg_rewind only needs the
following lines from fd.h:

	/* Filename components */
	#define PG_TEMP_FILES_DIR "pgsql_tmp"
	#define PG_TEMP_FILE_PREFIX "pgsql_tmp"

Maybe we could move these to file_utils.h instead.  WDYT?

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com