From: Darrick J. Wong <djwong@kernel.org>
Date: Mon, 8 Jun 2026 17:17:09 +0000 (-0700)
Subject: mkfs: fix hardlink detection in directory import code
X-Git-Tag: v7.1.0~9
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=63a4a9d6966ce0850089954f88a517fc68ddce98;p=thirdparty%2Fxfsprogs-dev.git

mkfs: fix hardlink detection in directory import code

There's a serious problem in the hardlink detection code in the new mkfs
protofile functionality that copies a directory tree into the new
filesystem.  It's been long established that hardlinks can only be
detected by comparing st_ino *and* st_dev, but the new code doesn't do
that.  Fix the detector.

Cc: <linux-xfs@vger.kernel.org> # v6.17.0
Fixes: 8a4ea72724930c ("proto: add ability to populate a filesystem from a directory")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---

diff --git a/mkfs/proto.c b/mkfs/proto.c
index e435f2e6d..dd47e41d8 100644
--- a/mkfs/proto.c
+++ b/mkfs/proto.c
@@ -1314,6 +1314,7 @@ writetimestamps(
 }
 
 struct hardlink {
+	dev_t		src_dev;
 	ino_t		src_ino;
 	xfs_ino_t	dst_ino;
 };
@@ -1368,7 +1369,8 @@ get_hardlink_dst_inode(
 	size_t			i = 0;
 
 	for (; i < hardlink_tracker.count; i++, h++) {
-		if (h->src_ino == filestat->st_ino)
+		if (h->src_dev == filestat->st_dev &&
+		    h->src_ino == filestat->st_ino)
 			return h->dst_ino;
 	}
 	return 0;
@@ -1406,6 +1408,7 @@ track_hardlink_inode(
 	}
 
 	h = &hardlink_tracker.entries[hardlink_tracker.count];
+	h->src_dev = filestat->st_dev;
 	h->src_ino = filestat->st_ino;
 	h->dst_ino = dst_ino;
 	hardlink_tracker.count++;