linux-kernel - [PATCH 3.18 14/25] scripts: recordmcount: break hardlinks

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Date:   Fri, 16 Mar 2018 16:23:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Russell King <rmk+kernel@....linux.org.uk>,
        Steven Rostedt <rostedt@...dmis.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 3.18 14/25] scripts: recordmcount: break hardlinks

3.18-stable 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

Cc: stable@...r.kernel.org # 2.6.37+
Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Cc: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 scripts/recordmcount.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -201,6 +201,20 @@ 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;
 }