From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jonathan Nieder <jrnieder@gmail.com>
Subject: Re: git update-ref --stdin : too many open files
Date: Mon, 22 Dec 2014 19:22:28 -0800
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References: <54954E44.1080906@dachary.org>
 <xmqqoaqv8jmi.fsf@gitster.dls.corp.google.com>
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Cc: Junio C Hamano <gitster@pobox.com>,
	Stefan Beller <sbeller@google.com>, git@vger.kernel.org,
	Loic Dachary <loic@dachary.org>
To: Stefan Beller <stefanbeller@gmail.com>
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Hi Stefan,

Stefan Beller wrote:
> On 22.12.2014 13:22, Junio C Hamano wrote:
>> Loic Dachary <loic@dachary.org> writes:

>>> fatal: Unable to create /home/gitmirror/repositories/Ceph/ceph/refs/heads/pull/1917.lock': Too many open files
[...]
>> Stefan, want to take a look?  I think we do need to keep the .lock
>> files without renaming while in transaction, but we do not have to
>> keep them open, so I suspect that a fix may be to split the commit
>> function into two (one to close but not rename, the other to
>> finalize by renaming) or something.

Makes sense.

> Sounds reasonable. Though by closing the file we're giving up again a
> bit of safety. If we close the file everyone could tamper with the lock
> file. (Sure they are not supposed to touch it, but they could)

At least on Linux, keeping a file open doesn't offer any protection
against someone else deleting it.  (It also doesn't offer any
protection against someone updating the ref directly. ;-)  Opening the
corresponding .lock file with O_EXCL is part of the contract for
updating refs.)

Thanks,
Jonathan