Date: Mon, 5 Mar 2018 10:42:33 -0800 From: Christoph Hellwig <hch@infradead.org> To: Konstantin Belousov <kib@freebsd.org> Cc: Christoph Hellwig <hch@infradead.org>, "Robert N. M. Watson" <robert.watson@cl.cam.ac.uk>, "<cl-capsicum-discuss@lists.cam.ac.uk>" <cl-capsicum-discuss@lists.cam.ac.uk>, Mariusz Zaborski <oshogbo@freebsd.org>, Justin Cormack <justin@specialbusservice.com>, freebsd-hackers@freebsd.org Subject: Re: [capsicum] unlinkfd Message-ID: <20180305184233.GA11236@infradead.org> In-Reply-To: <20180305161508.GE76926@kib.kiev.ua> References: <20180302183514.GA99279@x-wing> <CAK4o1Wyk54chHobhUkb2PBUtaWOF2rDv6tkX_bFGY6D331xUqw@mail.gmail.com> <17DE0BFF-42A2-4CD7-B09C-ABA2606C4041@cl.cam.ac.uk> <20180305155550.GA22789@infradead.org> <20180305161508.GE76926@kib.kiev.ua>
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On Mon, Mar 05, 2018 at 06:15:08PM +0200, Konstantin Belousov wrote: > It is not clear from the FreeBSD PR, how unlinkat() is supposed to work. > Do you mean that unlinkat(AT_EMPTY_PATH) removes the name entry for > given fd, which was used for open(2) ? It removes the current name for the open fd, including tracking renames that might have happened since open. > If yes, this is not possible to > implement in the current FreeBSD VFS. > > Also, does linkat(AT_EMPTY_PATH) supposed to link the inode referenced > only by the file descriptor ? I believe this feature is objected to. linkat(..., AT_EMPTY_PATH) in Linux creates a new link to inode reference by the fd. It is a privileged operation, and requires the inode to already have a non-zero link count, or be opened using the Linux-specific O_TMPFILE flag, which creates and open by unlinked file.
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