Re: coreutils-8.2 misc/ls-time test failure

[Eric Blake]

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According to John Stanley on 12/15/2009 4:42 PM:
> Basically, what's happening is that 'touch -a ..' updated ctime in
> coreutils-7.6,
> but does not update ctime in coreutils-8.2 (hence misc/ls-time fails).

Ouch.  That's a bug in the kernel; I can reproduce it:

$ uname -a
Linux fencepost 2.6.26-2-xen-amd64 #1 SMP Thu Nov 5 04:27:12 UTC 2009
x86_64 GNU/Linux
$ touch q
$ stat -c '%x %z' q
2009-12-15 21:46:33.186677568 -0500 2009-12-15 21:46:33.186677568 -0500
$ touch -a q
$ stat -c '%x %z' q
2009-12-15 21:47:15.157175384 -0500 2009-12-15 21:46:33.186677568 -0500
$

> I believe that an atime update in an
> inode should
> not result in a ctime update.

Unfortunately, you got it backwards.  POSIX requires that any modification
to inode metadata, such as calling utimensat, must update the ctime to the
point at which the modification was done.

> For coreutils-7.6, this gives:
> 
> -rw-r--r-- 1 root root 0 2009-12-15 18:17:58.935039372 -0500 a
> -rw-r--r-- 1 root root 0 2009-12-15 18:17:58.941039579 -0500 c
> 
> -rw-r--r-- 1 root root 0 2009-12-15 18:18:00.949039236 -0500 a
> -rw-r--r-- 1 root root 0 2009-12-15 18:17:58.944039683 -0500 c

Correct - the ctime for both files were updated.  But coreutils 7.6 didn't
use utimensat.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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