Re: touch

[ctrn3e8]

On 12/28/2009 07:10 AM, Eric Blake wrote:
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> According to ctrn3e8 on 12/20/2009 10:04 PM:
>    
> > > > >     touch -m no longer seems to modify the file modification date.  Archlinux,
> > > > >     coreutils-8.2 (package coreutils-8.2-1-i686).  Works if use coreutils-7.6.
> > > > >
> > > > >            
> > What kernel version on which architecture (uname -a)?  Can you send an
> > strace?  We recently fixed a bug with kernel 2.6.32 failing to change
> > ctime when you use 'touch -a'; I wonder if there is another kernel bug we
> > need to be aware of.
> >
> > execve("/bin/touch", ["touch", "-m", "startTimidity"], [/* 56 vars */]) = 0
> > utimensat(0, NULL, {UTIME_OMIT, UTIME_NOW}, 0) = 0
> >      
> It now appears from lkml traffic that this issue has been fixed for most
> file systems in concert with kernel 2.6.32 or newer, if you are running a
> bleeding-edge ntfs-3g file system.  However, gnulib should keep a
> workaround for the next couple years or so, until we can be reasonably
> sure that it is easier to tell people to update their file systems than to
> keep the workaround that (slightly) penalizes working file systems (the
> lkml list pointed out that our most common use of the utimensat syscall is
> via the futimens interface, where the kernel already has the file metadata
> in cache because of the open() and/or fstat()).
>
> But I still need a couple more pieces of information, before I know
> whether the workaround requires a gettime() or whether it is cheaper and
> only requires fstat().  We have proven the bug you reported against
> ntfs-3g occurs with UTIME_OMIT/UTIME_NOW.  Does your unpatched ntfs-3g
> file system also exhibit the bug with UTIME_OMIT/valid (test this by using
> 'touch --ref file1 -m file2', and report whether file2 changed mtime and
> ctime).  Also, does the bug occur with valid/UTIME_NOW (this is harder to
> test; touch does not expose that interface.  I'm not even sure that the
> gnulib test exercised this; but you could at least report the results of
> 'make -k check' from your coreutils source directory, if you have built
> from source.  If you need help writing a simple C program that tests this,
> let me know).
>
> - --
> Don't work too hard, make some time for fun as well!
>
> Eric Blake             address@hidden
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>    

Re: touch --ref file1 -m file2   or touch -m file1 --ref file2
Does not work on ntfs-3g.  See attached

valid/UTIME_NOW , make -k stuff
I did not build coreutils from source.  I have been using the Archlinux 
packages which are pre-built binaries.  I can build and make install from 
source, but if I do that I probably prefer to set up a 'sandbox', just to be 
safe..I know I can use make --uninstall to revert....but really don't want to 
get crazy if something goes wrong trying to removing all the little pieces left 
splattered around. It's probably a couple of hours to set up a sandbox, so if 
you really need it, just let me know and I will see what I can come up with.   
Also would need how to get 'valid' ..I asumme coding something like 
utimensat(0, NULL, { {1262110412, 0},UTIME_OMIT}, 0) = 0  would work.

shellOut
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