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From:   Miklos Szeredi <mszeredi@redhat.com>
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Vivek Goyal <vgoyal@redhat.com>, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] utimensat: AT_EMPTY_PATH support
Date:   Wed,  7 Nov 2018 10:15:52 +0100
Message-Id: <20181107091552.17100-1-mszeredi@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This makes it possible to use utimensat on an O_PATH file (including
symlinks).

It supersedes the nonstandard utimensat(fd, NULL, ...) form.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/utimes.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/utimes.c b/fs/utimes.c
index bdcf2daf39c1..f9c7ebad19d7 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -97,13 +97,13 @@ long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
 		goto out;
 	}
 
-	if (flags & ~AT_SYMLINK_NOFOLLOW)
+	if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
 		goto out;
 
 	if (filename == NULL && dfd != AT_FDCWD) {
 		struct fd f;
 
-		if (flags & AT_SYMLINK_NOFOLLOW)
+		if (flags)
 			goto out;
 
 		f = fdget(dfd);
@@ -119,6 +119,8 @@ long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
 
 		if (!(flags & AT_SYMLINK_NOFOLLOW))
 			lookup_flags |= LOOKUP_FOLLOW;
+		if (flags & AT_EMPTY_PATH)
+			lookup_flags |= LOOKUP_EMPTY;
 retry:
 		error = user_path_at(dfd, filename, lookup_flags, &path);
 		if (error)
-- 
2.14.3