linux-kernel - Re: [PATCH RFC] gen_init_cpio: Do fsync() only on regular files

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Message-ID: <20251007172556.3e57b0c8.ddiss@suse.de>
Date: Tue, 7 Oct 2025 17:25:56 +1100
From: David Disseldorp <ddiss@...e.de>
To: Christoph Hellwig <hch@...radead.org>
Cc: dima@...sta.com, Nathan Chancellor <nathan@...nel.org>, Nicolas Schier
 <nicolas.schier@...ux.dev>, linux-kbuild@...r.kernel.org,
 linux-kernel@...r.kernel.org, Nicolas Schier <nsc@...nel.org>
Subject: Re: [PATCH RFC] gen_init_cpio: Do fsync() only on regular files

On Mon, 6 Oct 2025 23:03:57 -0700, Christoph Hellwig wrote:

> On Tue, Oct 07, 2025 at 04:57:32PM +1100, David Disseldorp wrote:
> > I should have explained why in the commit, sorry. The intention was to
> > catch any FS I/O errors during output archive writeback. fsync() is
> > called only once as the final I/O.  
> 
> I don't parse this.  What does 'as the final I/O' mean?

fsync() is called once after all buffered writes and copy_file_range()
calls for the initramfs archive have completed.

> If you want
> to catch writeback errors, a single syncfs should be enough.

gen_init_cpio should only be concerned that the output archive file is
flushed to storage, rather than the entire filesystem. Why would syncfs
be more suitable?