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From: Ameer Hamza <ahamza@ixsystems.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	"jlayton@kernel.org" <jlayton@kernel.org>,
	"chuck.lever@oracle.com" <chuck.lever@oracle.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"guoren@kernel.org" <guoren@kernel.org>,
	"palmer@rivosinc.com" <palmer@rivosinc.com>,
	"f.fainelli@gmail.com" <f.fainelli@gmail.com>,
	"slark_xiao@163.com" <slark_xiao@163.com>,
	"richard.henderson@linaro.org" <richard.henderson@linaro.org>,
	"ink@jurassic.park.msu.ru" <ink@jurassic.park.msu.ru>,
	"mattst88@gmail.com" <mattst88@gmail.com>,
	"James.Bottomley@HansenPartnership.com" 
	<James.Bottomley@HansenPartnership.com>,
	"deller@gmx.de" <deller@gmx.de>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"awalker@ixsystems.com" <awalker@ixsystems.com>,
	"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
	"linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
	"linux-alpha@vger.kernel.org" <linux-alpha@vger.kernel.org>
Subject: Re: [PATCH v2] Add new open(2) flag - O_EMPTY_PATH
Date: Mon, 2 Jan 2023 19:35:38 +0500	[thread overview]
Message-ID: <20230102143538.GA8886@hamza-HP-ZBook-15-G3> (raw)
In-Reply-To: <4b39cf528148470c934fb5823b35e9d5@AcuMS.aculab.com>

On Mon, Jan 02, 2023 at 02:01:38PM +0000, David Laight wrote:
> From: Ameer Hamza
> > Sent: 31 December 2022 23:56
> > 
> > This patch adds a new flag O_EMPTY_PATH that allows openat and open
> > system calls to open a file referenced by fd if the path is empty,
> > and it is very similar to the FreeBSD O_EMPTY_PATH flag. This can be
> > beneficial in some cases since it would avoid having to grant /proc
> > access to things like samba containers for reopening files to change
> > flags in a race-free way.
> > 
> 
> But what does it do?
> (Apart from add code to a common kernel code path.)
> 
> 	David
It can convert an O_PATH descriptor to one suitable for r/w work.
If we already have a file descriptor: {opath_fd = open(&lt;path&gt;, O_PATH);}, we can call {openat(opath_fd, "", O_EMPTY_PATH | O_RDWR)} instead of going through procfs {open(/proc/self/fd/&lt;opath_fd&gt;, O_RDWR)}.
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
> 

  reply	other threads:[~2023-01-02 14:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-28 16:02 [PATCH] Add new open(2) flag - O_EMPTY_PATH Ameer Hamza
2022-12-31  0:15 ` kernel test robot
2022-12-31 23:56   ` [PATCH v2] " Ameer Hamza
2023-01-01 11:16     ` kernel test robot
2023-01-01 15:37       ` [PATCH v3] " Ameer Hamza
2023-01-02 14:01     ` [PATCH v2] " David Laight
2023-01-02 14:35       ` Ameer Hamza [this message]
2023-01-06  9:21         ` David Laight
2023-01-06 13:06 ` [PATCH] " Christian Brauner
2023-04-19  1:15   ` Ameer Hamza
     [not found]     ` <7454A798-1277-411A-853C-635B33439029@gmail.com>
2023-04-19  9:18       ` Christian Brauner
2023-04-19 21:29     ` David Laight
2023-04-26 13:10       ` Andrew Walker

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