Message-ID: <51B8C639.7060500@redhat.com>
Date: Wed, 12 Jun 2013 12:04:25 -0700
From: Anand Avati <avati@redhat.com>
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To: Maxim Patlasov <MPatlasov@parallels.com>
CC: miklos@szeredi.hu, fuse-devel@lists.sourceforge.net, bfoster@redhat.com,
        linux-kernel@vger.kernel.org, devel@openvz.org
Subject: Re: [PATCH] fuse: hold i_mutex in fuse_file_fallocate()
References: <20130611105714.24455.38409.stgit@maximpc.sw.ru>
In-Reply-To: <20130611105714.24455.38409.stgit@maximpc.sw.ru>
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On 6/11/13 3:59 AM, Maxim Patlasov wrote:

> -	if (mode & FALLOC_FL_PUNCH_HOLE) {
> +	if (lock_inode)
>   		mutex_lock(&inode->i_mutex);

> +	if (mode & FALLOC_FL_PUNCH_HOLE)
>   		fuse_set_nowrite(inode);
> -	}

Just for clarity, can you make the condition to check 
FALLOC_FL_PUNCH_HOLE and call to fuse_set_nowrite() nested within the 
larger if (lock_inode) { .. } block? fuse_set_nowrite() should not be 
called without i_mutex acquired. The current style of calling 
mutex_lock() and fuse_set_nowrite() in separate conditions can 
potentially cause bugs in the future if they were to get re-ordered due 
to some unrelated patch. Nesting them makes the relation more explicit 
and clear.

Thanks,
Avati

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