ANDROID: sdcardfs: Set s_root to NULL after putting

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Keith <javelinanddart@gmail.com>
Bug: 77923821
Change-Id: I1705bfd146009561d2d1da5f0e6a342ec6932a1c

fs/sdcardfs/main.c

@@ -368,6 +368,7 @@ static int sdcardfs_read_super(struct vfsmount *mnt, struct super_block *sb,
 	/* no longer needed: free_dentry_private_data(sb->s_root); */
 out_freeroot:
 	dput(sb->s_root);
+	sb->s_root = NULL;
 out_sput:
 	/* drop refs we took earlier */
 	atomic_dec(&lower_sb->s_active);