linux-kernel - Re: [PATCH] scripts: recordmcount: break hardlinks

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Message-ID: <20151211093125.50b72639@gandalf.local.home>
Date:	Fri, 11 Dec 2015 09:31:25 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Russell King <rmk+kernel@....linux.org.uk>
Cc:	Michal Marek <mmarek@...e.cz>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Måns Rullgård <mans@...sr.com>,
	Arnd Bergmann <arnd@...db.de>, linux-kbuild@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, Nicolas Pitre <nico@...xnic.net>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] scripts: recordmcount: break hardlinks

On Fri, 11 Dec 2015 12:09:03 +0000
Russell King <rmk+kernel@....linux.org.uk> wrote:

> recordmcount edits the file in-place, which can cause problems when
> using ccache in hardlink mode.  Arrange for recordmcount to break a
> hardlinked object.
> 
> Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
> ---
> Steven, sorry it took a while to get this out...

Should this be for stable, or is it fine to just add this to my 4.5
queue?

-- Steve

> 
>  scripts/recordmcount.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
> index 698768bdc581..91705ef30402 100644
> --- a/scripts/recordmcount.c
> +++ b/scripts/recordmcount.c
> @@ -211,6 +211,20 @@ static void *mmap_file(char const *fname)
>  		addr = umalloc(sb.st_size);
>  		uread(fd_map, addr, sb.st_size);
>  	}
> +	if (sb.st_nlink != 1) {
> +		/* file is hard-linked, break the hard link */
> +		close(fd_map);
> +		if (unlink(fname) < 0) {
> +			perror(fname);
> +			fail_file();
> +		}
> +		fd_map = open(fname, O_RDWR | O_CREAT, sb.st_mode);
> +		if (fd_map < 0) {
> +			perror(fname);
> +			fail_file();
> +		}
> +		uwrite(fd_map, addr, sb.st_size);
> +	}
>  	return addr;
>  }
>  

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