linux-kernel - [PATCH 3.2 16/70] scripts: recordmcount: break hardlinks

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Message-ID: <lsq.1453087115.627604942@decadent.org.uk>
Date:	Mon, 18 Jan 2016 03:18:35 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Steven Rostedt" <rostedt@...dmis.org>,
	"Russell King" <rmk+kernel@....linux.org.uk>
Subject: [PATCH 3.2 16/70] scripts: recordmcount: break hardlinks

3.2.76-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Russell King <rmk+kernel@....linux.org.uk>

commit dd39a26538e37f6c6131e829a4a510787e43c783 upstream.

recordmcount edits the file in-place, which can cause problems when
using ccache in hardlink mode.  Arrange for recordmcount to break a
hardlinked object.

Link: http://lkml.kernel.org/r/E1a7MVT-0000et-62@rmk-PC.arm.linux.org.uk

Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 scripts/recordmcount.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -182,6 +182,20 @@ 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;
 }