linux-kernel - Re: [PATCH v2 1/1] FS: cifs, remove unneeded NULL tests

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Message-ID: <20101103100012.GA19804@ZenIV.linux.org.uk>
Date:	Wed, 3 Nov 2010 10:00:12 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	sfrench@...ba.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, jirislaby@...il.com,
	linux-cifs@...r.kernel.org, Jeff Layton <jlayton@...hat.com>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v2 1/1] FS: cifs, remove unneeded NULL tests

On Mon, Nov 01, 2010 at 04:08:55PM +0100, Jiri Slaby wrote:
> Stanse found that pSMBFile in cifs_ioctl and file->f_path.dentry in
> cifs_user_write are dereferenced prior their test to NULL.

file->f_path.dentry is never NULL for an opened file, neither is
file->f_path.dentry->d_inode (which cannot change for the entire
lifetime of dentry, BTW).  IOW,

> -	/* since the write may have blocked check these pointers again */
> -	if ((file->f_path.dentry) && (file->f_path.dentry->d_inode)) {
> -		struct inode *inode = file->f_path.dentry->d_inode;

in there had always been junk.  So yes, losing these tests is the right
thing to do.
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