vfs: Undo an overly zealous MS_RDONLY -> SB_RDONLY conversion

[ Upstream commit a9e5b732 ]

In do_mount() when the MS_* flags are being converted to MNT_* flags,
MS_RDONLY got accidentally convered to SB_RDONLY.

Undo this change.

Fixes: e462ec50 ("VFS: Differentiate mount flags (MS_*) from internal superblock flags")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/namespace.c

@@ -2810,7 +2810,7 @@ long do_mount(const char *dev_name, const char __user *dir_name,
 		mnt_flags |= MNT_NODIRATIME;
 	if (flags & MS_STRICTATIME)
 		mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
-	if (flags & SB_RDONLY)
+	if (flags & MS_RDONLY)
 		mnt_flags |= MNT_READONLY;
 
 	/* The default atime for remount is preservation */