[OpenAFS-devel] 1.3.86 LINUX largefile-support broken

[Hartmut Reuter]

Rainer Toebbicke wrote:
> chas williams - CONTRACTOR wrote:
> 
>> In message <42EE0716.4000102@rzg.mpg.de>,Hartmut Reuter writes:
>>
>>> 3 gb is under the 32bit line! if you try to write a 5 gb file you 
>>> will see that this doesn't work correctly. It overwrites the begin of 
>>> the file with the part beyond the 4gb-line!
>>
>>
>>
>> try this patch.  it looks like shifting pp->index is an unsigned long.
>> the shift is probably wrapping.  page_offset() casts it to loff_t before
>> shifting.  not sure when page_offset() came into existence.
>>
>> Index: src/afs/LINUX/osi_vnodeops.c
>> ===================================================================
>> RCS file: /cvs/openafs/src/afs/LINUX/osi_vnodeops.c,v
>> retrieving revision 1.112
>> diff -u -u -r1.112 osi_vnodeops.c
>> --- src/afs/LINUX/osi_vnodeops.c    26 Jul 2005 17:39:00 -0000    1.112
>> +++ src/afs/LINUX/osi_vnodeops.c    1 Aug 2005 13:36:33 -0000
>> @@ -1263,7 +1267,7 @@
>>      cred_t *credp = crref();
>>  #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
>>      char *address;
>> -    afs_offs_t offset = pp->index << PAGE_CACHE_SHIFT;
>> +    afs_offs_t offset = page_offset(pp);
>>  #else
>>      ulong address = afs_linux_page_address(pp);
>>      afs_offs_t offset = pageoff(pp);
>> @@ -1359,7 +1362,7 @@
>>      int f_flags = 0;
>>  
>>      buffer = kmap(pp) + offset;
>> -    base = (pp->index << PAGE_CACHE_SHIFT) + offset;
>> +    base = page_offset(pp) + offset;
>>  
>>      credp = crref();
>>      lock_kernel();
> 
> 
> On my 2.6.9-11.ELsmp x86_64 test machine this just leads to "kernel: 
> libafs: Unknown symbol page_offset" when loading.
> 
> page_offset is defined in linux/nfs_fs.h (and yes the BIG difference 
> seems to be the loff_t cast) which should probably be included - but 
> does it exist for all kernels?
> 
> --- openafs/src/afs/LINUX/osi_vnodeops.c.old   2005-08-02 
> 10:42:25.000000000 +0200
> +++ openafs/src/afs/LINUX/osi_vnodeops.c    2005-08-02 
> 13:00:50.000000000 +0200
> @@ -34,6 +34,7 @@
>  #include "h/pagemap.h"
>  #if defined(AFS_LINUX24_ENV)
>  #include "h/smp_lock.h"
> +#include "linux/nfs_fs.h"
>  #endif
>  #if defined(AFS_LINUX26_ENV)
>  #include "h/writeback.h"
> 
> (no time to test the 3G, 5G cases yet, though...)
> 

Well, I have now after Rainer's patch been able to write and read a 5 gb 
file and it seems to work. But I am not sure that all kernel versions 
support this. Therefor 5 years ago I chose this - may be ugly or 
complicated - code to have large file support under linux which always 
worked.

Hartmut
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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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