Re: extended attributes wiredness

[David Arendt <admin@prnet.org>]

Hi,

based on my observations and debugging of the cp command, I have written
the following code to reproduce the problem:

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/acl.h>

int main(int argc, char *argv[])
{
 acl_t acl;

 mkdir("test1", S_IRWXU);
 mkdir("test2", S_IRWXU);

 acl = acl_get_file("test1", ACL_TYPE_DEFAULT);

 if (acl == NULL)
 {
   perror("acl_get_file");

   return 1;
 }

 if (acl_set_file("test2", ACL_TYPE_DEFAULT, acl) < 0)
 {
   perror("acl_set_file");

   return 1;
 }

 return 0;
}

The code runs without any error.
On btrfs, attribute system.posix_acl_default is set but it contains no data.
On ext4, attribute system.posix_acl_default is not set.

Thanks in advance,
David Arendt

On 11/27/12 08:46, Liu Bo wrote:
> Hi,  
>  
> (cc btrfs Mailing list to notify others.)
>
> Thanks for the helpful test.img.
>
> Well...after deeper debug, I'm sure that it's not a btrfs bug,
> at least not a btrfs acl/xattr bug. 
>  
> The debug tree shows 
>  
> item 10 key (257 INODE_ITEM 0) itemoff 3387 itemsize 160 
>         inode generation 6 transid 6 size 102 block group 0 mode 40755 links 1 
> item 11 key (257 INODE_REF 256) itemoff 3372 itemsize 15 
>         inode ref index 2 namelen 5 name: test1 
> item 12 key (257 XATTR_ITEM 367492571) itemoff 3318 itemsize 54 
>         location key (0 UNKNOWN.0 0) type 8 
>         namelen 24 datalen 0 name: system.posix_acl_default 
>                   ^^^^^^^^^^^ 
> item 13 key (257 XATTR_ITEM 2038346239) itemoff 3237 itemsize 81 
>         location key (0 UNKNOWN.0 0) type 8 
>         namelen 23 datalen 28 name: system.posix_acl_access 
>         data ^B 
>  
> ========== 
>
> so extended attribute "system.posix_acl_default" here has not data, which'll
> make filesystems(not just btrfs) return -ENODATA. 
>  
> I guess some userspace applications may make it like that. 
>  
> thanks, 
> liubo
>
> On Mon, Nov 26, 2012 at 06:38:06AM +0100, David Arendt wrote:
>> Hi,
>>
>> I don't know if your xattr patch was meant to fix this issue, but I have
>> just tested kernel 3.7-rc7 with your patch applied on another directory
>> having the problem and I still have the weird behaviour.
>>
>> Thanks in advance,
>> David Arendt