[PATCH] nfsd: revoking of suid/sgid bits after chown() in a consistent way

[Stanislav Kholmanskikh]

On 12/11/2013 02:16 PM, Stanislav Kholmanskikh wrote:
[cut off]
>
> This patch makes NFS to behave like local file systems.
>
[cut off]

This patch allows to run generic/193 without any issues with NFSv3.

With NFSv4 generic/193 fails (but with the other issues, which existed 
even before the patch).

generic/193 expects that suid/sgid bits are cleared after the file 
truncation:

touch file
chown fsgqa:fsgqa file
chmod u+s file
echo 'xyz' > file
ls -l file
su fsgqa -c 'echo > file'
ls -l file

With ext4 (for example), we have expectable results:
-rwSr--r-- 1 fsgqa fsgqa 4 Dec 11 05:21 file
-rw-r--r-- 1 fsgqa fsgqa 1 Dec 11 05:22 file

With NFSv3 as well:
-rwSr--r-- 1 fsgqa fsgqa 4 Dec 11 05:24 file
-rw-r--r-- 1 fsgqa fsgqa 1 Dec 11 05:25 file

But with NFSv4 the bits are not cleared:
-rwSr--r-- 1 fsgqa fsgqa 1 Dec 11 05:19 file
-rwSr--r-- 1 fsgqa fsgqa 1 Dec 11 05:21 file

'echo > file' issues:

open("file", O_WRONLY|O_CREAT|O_TRUNC, 0666)

Can it be because of design differences between NFSv3 and NFSv4?

Thank you.