[bug report] fsnotify: pass dir and inode arguments to fsnotify()

[<dan.carpenter@oracle.com>]

Hello Amir Goldstein,

This is a semi-automatic email about new static checker warnings.

The patch 40a100d3adc1: "fsnotify: pass dir and inode arguments to
fsnotify()" from Jul 22, 2020, leads to the following Smatch
complaint:

    fs/notify/fsnotify.c:460 fsnotify()
    warn: variable dereferenced before check 'inode' (see line 449)

fs/notify/fsnotify.c
   448		}
   449		sb = inode->i_sb;
                     ^^^^^^^^^^^
New dreference.

   450	
   451		/*
   452		 * Optimization: srcu_read_lock() has a memory barrier which can
   453		 * be expensive.  It protects walking the *_fsnotify_marks lists.
   454		 * However, if we do not walk the lists, we do not have to do
   455		 * SRCU because we have no references to any objects and do not
   456		 * need SRCU to keep them "alive".
   457		 */
   458		if (!sb->s_fsnotify_marks &&
   459		    (!mnt || !mnt->mnt_fsnotify_marks) &&
   460		    (!inode || !inode->i_fsnotify_marks) &&
                     ^^^^^^
Check too late.  Presumably this check can be removed?

   461		    (!child || !child->i_fsnotify_marks))
   462			return 0;

regards,
dan carpenter