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Re: file born 30 seconds after its creation on ext4 - bug?

From Vincent Lefevre <vincent@vinc17.net>
Newsgroups linux.debian.user
Subject Re: file born 30 seconds after its creation on ext4 - bug?
Date 2022-04-28 10:40 +0200
Message-ID <Eh7QR-bJNA-7@gated-at.bofh.it> (permalink)
References (1 earlier) <EgMjn-bwbC-1@gated-at.bofh.it> <EgPKh-bykw-1@gated-at.bofh.it> <EgPTX-bynS-3@gated-at.bofh.it> <EgQwF-byR7-5@gated-at.bofh.it> <Eh2o9-bG8w-1@gated-at.bofh.it>
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On 2022-04-27 22:45:09 -0400, Stefan Monnier wrote:
> Another option might be that your system's time was "reset".
> This shouldn't happen, but it can happen if your NTP was down, the
> machine got out-of-sync over time and you restart the NTP server at
> which point it may(!) decide to jump the clock if the difference is
> large enough (i.e. too large to catch up gradually).
> Can't remember how large is "large enough".

I don't think that systemd does that. Anyway, even if this were
possible, that would make the output inconsistent. I recall:

cventin:~/software/mpfr[1]> lt|head                                   <14:43:42
total 7016
-rw-r--r--  1  188644 2022-04-26 14:43:42 config.log
-rw-r--r--  1    2861 2022-04-26 14:43:42 conftest.c
-rw-r--r--  1       0 2022-04-26 14:43:42 conftest.err
-rw-r--r--  1    1907 2022-04-26 14:43:42 confdefs.h
-rwxr-xr-x  1  632161 2022-04-26 14:43:16 configure.lineno*
drwxr-xr-x  2    4096 2022-04-26 14:43:11 doc/
drwxr-xr-x  3    4096 2022-04-26 14:43:11 tune/
-rwxr-xr-x  1   23568 2022-04-26 14:43:11 depcomp*
drwxr-xr-x  5   36864 2022-04-26 14:43:11 tests/
cventin:~/software/mpfr> lt|head                                      <14:43:47
total 6416
-rw-r--r--  1   19436 2022-04-26 14:43:47 config.log
-rw-r--r--  1     561 2022-04-26 14:43:47 conftest.c
-rw-r--r--  1       0 2022-04-26 14:43:47 conftest.err
-rw-r--r--  1    4138 2022-04-26 14:43:47 mpfrtests.cfgout
-rw-r--r--  1     500 2022-04-26 14:43:47 confdefs.h
-rwxr-xr-x  1  632161 2022-04-26 14:43:45 configure.lineno*
-rw-r--r--  1     878 2022-04-26 14:43:45 mpfrtests.cventin.lip.ens-lyon.fr.out
drwxr-xr-x  3    4096 2022-04-26 14:43:44 tune/
drwxr-xr-x  4   36864 2022-04-26 14:43:44 tests/

where mpfrtests.cventin.lip.ens-lyon.fr.out was actually created
a fraction of second before configure.lineno in the script.

"14:43:42" is the time I ran the first "lt|head" and "14:43:47"
is the time I ran the second "lt|head", where "lt" is ls with
various options, including "-t" to sort in decreasing date order.

With time jumps, this is theoretically possible, but this would
mean that the time jumped at least 3 times:
  1. To make the birth time as 14:43:45.
  2. To make the last modified time earlier than 14:43:11 (so that
     mpfrtests.cventin.lip.ens-lyon.fr.out doesn't appear in the
     first "lt|head" output).
  3. To go back after 14:43:42.

And this would not explain the

cventin:~/software/mpfr> tail -n 30 mpfrtests.*.out; ll mpfrtests.*.out
zsh: no match
zsh: no match
cventin:~/software/mpfr[1]> tail -n 30 mpfrtests.*.out; ll mpfrtests.*.out
zsh: no match
zsh: no match

which I did a few seconds before 14:43:42.

If the time did not jump, then the birth time 14:43:45.537241731
matches the behavior I've observed in the above commands, i.e. as if
this file were created at this time.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

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Thread

file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-26 15:50 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-26 19:10 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 04:40 +0200
      Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-27 09:10 +0200
        Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 10:30 +0200
          Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-27 11:40 +0200
            Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 15:20 +0200
              Re: file born 30 seconds after its creation on ext4 - bug? Greg Wooledge <greg@wooledge.org> - 2022-04-27 15:30 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 16:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Stefan Monnier <monnier@iro.umontreal.ca> - 2022-04-28 04:50 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Greg Wooledge <greg@wooledge.org> - 2022-04-28 05:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? duh <fill_in_the_blanks@email.com> - 2022-04-29 16:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Marc Auslander <marcausl@gmail.com> - 2022-04-29 20:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? "sp007@caiway.net" <sp007@caiway.net> - 2022-04-29 22:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-04-30 07:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-30 10:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-04-30 14:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-05-02 01:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-05-02 07:30 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Curt <curty@free.fr> - 2022-04-30 14:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-04-30 15:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-30 15:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-05-02 01:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Greg Wooledge <greg@wooledge.org> - 2022-05-02 01:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? David Wright <deblis@lionunicorn.co.uk> - 2022-05-02 17:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-05-02 18:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-28 10:40 +0200
            Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-28 11:40 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? Nicholas Geovanis <nickgeovanis@gmail.com> - 2022-04-26 19:40 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Nicholas Geovanis <nickgeovanis@gmail.com> - 2022-04-26 19:50 +0200
      Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 04:50 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? Stefan Monnier <monnier@iro.umontreal.ca> - 2022-04-26 20:20 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 05:10 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-28 11:30 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-28 12:20 +0200

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