[PATCH master 2/2] fs: fix resolving paths when directory name repeats

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

d_same_name() used to only check if the name exists in any of the
directory's children.

In order to fix lookup of /, the function was changed to also compare
the name against the parent. This is obviously wrong, when the parent
and child have the same name: Resolution of the child would always
return the parent dentry triggering unexpected behavior.

Fix this by effectively reverting the functional change in commit
3a478ff3e1e6 ("fs: support opening /"). This breaks opening /, but that
currently only affects dirfd usage and will be fixed separately.

Fixes: 3a478ff3e1e6 ("fs: support opening /")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 fs/fs.c           | 3 ---
 test/self/dirfd.c | 7 ++++++-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/fs.c b/fs/fs.c
index 57bd781025f9..235fb8f8e9ef 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1536,9 +1536,6 @@ static struct dentry *d_lookup(struct dentry *parent, const struct qstr *name)
 {
 	struct dentry *dentry;
 
-	if (d_same_name(parent, name))
-		return dget(parent);
-
 	list_for_each_entry(dentry, &parent->d_subdirs, d_child) {
 		if (d_same_name(dentry, name))
 			return dget(dentry);
diff --git a/test/self/dirfd.c b/test/self/dirfd.c
index 20b54258715a..644ff214fb37 100644
--- a/test/self/dirfd.c
+++ b/test/self/dirfd.c
@@ -100,8 +100,13 @@ static void test_dirfd(void)
 	int fd;
 
 	fd = open("/", O_PATH);
-	if (expect(fd < 0, false, "open(/, O_PATH) = %d", fd))
+	if (expect(fd < 0, false, "open(/, O_PATH) = %d", fd)) {
 		close(fd);
+	} else {
+		pr_info("\tIgnoring expected failure\n");
+		failed_tests--;
+		skipped_tests++;
+	}
 
 #define B(dot, dotdot, zero, dev) 0b##dev##zero##dotdot##dot
 	/* We do fiften tests for every configuration
-- 
2.39.5