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From: Richard Weinberger <richard.weinberger@gmail.com>
To: "Pali Rohár" <pali.rohar@gmail.com>
Cc: Chris Murphy <lists@colorremedies.com>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: Is rename(2) atomic on FAT?
Date: Wed, 23 Oct 2019 23:21:44 +0200	[thread overview]
Message-ID: <CAFLxGvxCVNy0yj8SQmtOyk5xcmYag1rxe3v7GtbEj8fF1iPp5g@mail.gmail.com> (raw)
In-Reply-To: <20191023171611.qfcwfce2roe3k3qw@pali>

On Wed, Oct 23, 2019 at 7:16 PM Pali Rohár <pali.rohar@gmail.com> wrote:
> On Wednesday 23 October 2019 16:21:19 Chris Murphy wrote:
> > On Wed, Oct 23, 2019 at 1:50 PM Pali Rohár <pali.rohar@gmail.com> wrote:
> > > I do not think that kernel guarantee for any filesystem that rename
> > > operation would be atomic on underlying disk storage.
> > >
> > > But somebody else should confirm it.
> >
> > I don't know either or how to confirm it.
>
> Somebody who is watching linuxfs-devel and has deep knowledge in this
> area... could provide more information.

This is filesystem specific.
For example on UBIFS we make sure that the rename operation is atomic.
Changing multiple directory entries is one journal commit, so either it happened
completely or not at all.
On JFFS2, on the other hand, rename can degrade to a hard link.

I'd go so far and claim that any modern Linux filesystem guarantees
that rename is atomic.
But bugs still happen, crashmonkey found some interesting issues in
this area[0].

[0] http://www.cs.utexas.edu/~vijay/papers/osdi18-crashmonkey.pdf

-- 
Thanks,
//richard

  parent reply	other threads:[~2019-10-23 21:21 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-21 19:57 Is rename(2) atomic on FAT? Chris Murphy
2019-10-21 21:44 ` Richard Weinberger
2019-10-22 10:54   ` Pali Rohár
2019-10-23  0:10     ` Chris Murphy
2019-10-23 11:50       ` Pali Rohár
2019-10-23 14:21         ` Chris Murphy
2019-10-23 17:16           ` Pali Rohár
2019-10-23 19:18             ` Chris Murphy
2019-10-23 21:21             ` Richard Weinberger [this message]
2019-10-23 21:56               ` Chris Murphy
2019-10-23 22:22                 ` Richard Weinberger
2019-10-24 21:46                   ` Chris Murphy
2019-10-24 21:57                     ` Pali Rohár
2019-10-24 22:19                       ` Chris Murphy
2019-10-24 22:16                     ` Richard Weinberger
2019-10-24 22:26                       ` Chris Murphy
2019-10-24 22:33                         ` Richard Weinberger
2019-10-25  9:22                           ` Chris Murphy
2019-10-25  9:50                             ` Richard Weinberger
2019-10-23 12:53       ` Colin Walters
2019-10-23 14:24         ` Chris Murphy
2019-10-23 17:26           ` Colin Walters

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