[Pvfs2-developers] Long file names

[Phil Carns]

Bart and I worked through this some off-list and found the problem.  The 
fix is in cvs trunk now, but I attached the patch in case anyone needs it.

There was an off by one error in a path length test that could cause a 
buffer overrun when attempting to access file names that are too long. 
I'm not sure what kernel versions it affected.  I did not see any side 
affects from the bug on newer kernels, but I haven't confirmed if the 
vfs added a generic check for this or if I was just lucky.  The rhel4 
2.6.9 kernel can definitely trigger this condition.

-Phil

Bart Taylor wrote:
> It did not seem to make a difference. I do not see any log message, 
> client or kernel, that indicate what is happening. The pvfs2-client-core 
> does die after the long file name commands run though.
> 
> Bart.
> 
> 
> 
> On Mon, Jun 30, 2008 at 2:10 PM, Phil Carns <carns at mcs.anl.gov 
> <mailto:carns at mcs.anl.gov>> wrote:
> 
>     Hi Bart,
> 
>     Does the attached patch help this issue any?
> 
>     -Phil
> 
> 
>     Phil Carns wrote:
> 
>         Hi Bart,
> 
>         I can't get those specific commands to cause a problem for me
>         (using trunk at least, I haven't tried 2.7.1 yet).  However, I
>         definitely see some problems in LTP.  For me it eventually hangs
>         on the rename06 test, but valgrind is complaining about some
>         memory problems in the pvfs2-client-core symlink path as well
>         before reaching that point.
> 
>         I'll look into it and let you know what turns up.
> 
>         I might also see if I can cook up a script to include LTP in our
>         nightly tinderbox builds as well; there are some good tests in here.
> 
>         -Phil
> 
>         Bart Taylor wrote:
> 
>             Hello all,
> 
>             I have run into a few problems when running some tests
>             against the 2.7.1 release on RHEL4. They all seem to hinge
>             around large file names of 256 characters or greater. The
>             commands fail gracefully - reporting an error that the file
>             names are too long - but the next access of PVFS (an 'ls'
>             for instance) hangs the system so that it has to be
>             rebooted. I ran into them using the LTP test suite, but they
>             can be reliably repeated with simple commands. Create, open,
>             rename, and stat are the operations that fail, and some
>             example commands are provided below. The file does not need
>             to exist for the open or stat commands. Occasionally it
>             takes a few seconds after command has been executed for the
>             problem to show itself. Do these commands cause problems for
>             anyone else, or is it something unique to my setup or
>             environment?
> 
>             Bart.
> 
> 
> 
>             create:  $echo "Hello World" >
>             1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
> 
> 
>             open:  $cat
>             1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
> 
> 
>             rename:  $mv test.file
>             1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
> 
> 
>             stat:  $stat -f
>             /mnt/pvfs2/test/1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
> 
> 
> 
> 
>             ------------------------------------------------------------------------
> 
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> 
> 

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