[PATCH 3.16.y-ckt 100/128] scripts: recordmcount: break hardlinks

[Luis Henriques]

3.16.7-ckt23 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Russell King <rmk+kernel at arm.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 at arm.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 scripts/recordmcount.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 650ecc83d7d7..26f0cd2c8e9a 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -194,6 +194,20 @@ 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;
 }