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Date:   Thu, 12 Jul 2018 22:35:55 -0400
From:   "Theodore Y. Ts'o" <tytso@mit.edu>
To:     David Howells <dhowells@redhat.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Lutomirski <luto@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux API <linux-api@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jann Horn <jannh@google.com>
Subject: Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for
 superblock creation [ver #9]
Message-ID: <20180713023555.GE28610@thunk.org>
Mail-Followup-To: "Theodore Y. Ts'o" <tytso@mit.edu>,
        David Howells <dhowells@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Lutomirski <luto@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux API <linux-api@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jann Horn <jannh@google.com>
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On Thu, Jul 12, 2018 at 11:54:41PM +0100, David Howells wrote:
> 
> Would that mean then that doing:
> 
> 	mount /dev/sda3 /a
> 	mount /dev/sda3 /b
> 
> would then fail on the second command because /dev/sda3 is already open
> exclusively?

Good point.  One workaround would be to require an open with O_PATH instead.

     	     	 	    	     	- Ted