Here is a transcript of the test session, in which I compare the 
behavior of the ramfs mounted on /tmp with that of YAFFS.

root@ts-7250:~ $ cd /tmp
root@ts-7250:/tmp $ mkdir testsgid
root@ts-7250:/tmp $ chgrp bin testsgid
root@ts-7250:/tmp $ chmod g+s testsgid
root@ts-7250:/tmp $ cd testsgid
root@ts-7250:/tmp/testsgid $ ls -Fla
drwxrwsr-x    1 root     bin             0 May  8 12:18 ./
drwxrwxrwt    1 root     root            0 Dec 31  1969 ../
root@ts-7250:/tmp/testsgid $ touch testfile
root@ts-7250:/tmp/testsgid $ ls -Fla
drwxrwsr-x    1 root     bin             0 May  8 12:18 ./
drwxrwxrwt    1 root     root            0 Dec 31  1969 ../
-rw-rw-r--    1 root     bin             0 May  8 12:19 testfile
root@ts-7250:/tmp/testsgid $ cd
root@ts-7250:~ $ mkdir testsgid
root@ts-7250:~ $ chgrp bin testsgid
root@ts-7250:~ $ chmod g+s testsgid
root@ts-7250:~ $ cd testsgid
root@ts-7250:~/testsgid $ ls -Fla
drwxrwsr-x    1 root     bin           512 May  8 12:19 ./
drwxr-xr-x    1 root     root          512 Oct 26  2005 ../
root@ts-7250:~/testsgid $ touch testfile
root@ts-7250:~/testsgid $ ls -Fla
drwxrwsr-x    1 root     bin           512 May  8 12:19 ./
drwxr-xr-x    1 root     root          512 Oct 26  2005 ../
-rw-rw-r--    1 root     root            0 May  8 12:20 testfile
root@ts-7250:~/testsgid $

You can see that the new "testfile" has a group ID of "bin" in the first 
example, but retains "root" in the second.

Here is the output from /proc/yaffs:

$Id: yaffs_fs.c,v 1.3 2005/01/25 00:38:25 eddie Exp $
$Id: yaffs_guts.c,v 1.2 2005/01/10 18:27:13 eddie Exp $

Device yaffs
startBlock......... 1
endBlock........... 1855
chunkGroupBits..... 0
chunkGroupSize..... 1
nErasedBlocks...... 7
nTnodesCreated..... 7600
nFreeTnodes........ 2513
nObjectsCreated.... 4600
nFreeObjects....... 2511
nFreeChunks........ 2273
nPageWrites........ 1036366
nPageReads......... 2450159
nBlockErasures..... 17124
nGCCopies.......... 393757
garbageCollections. 17122
passiveGCs......... 18
nRetriedWrites..... 0
nRetireBlocks...... 0
eccFixed........... 0
eccUnfixed......... 0
tagsEccFixed....... 0
tagsEccUnfixed..... 8
cacheHits.......... 0
nDeletedFiles...... 7751
nUnlinkedFiles..... 10282
nBackgroudDeletions 0
useNANDECC......... 1

Also, my /etc/fstab:

proc    /proc   proc    defaults        0 0
/dev/mtdblock/1 / yaffs defaults,noatime,grpid 0 0
ramfs /tmp ramfs mode=1777 0 0



Charles Manning wrote:
> On Thursday 27 April 2006 22:25, Tom Hansen wrote:
>   
>> I'm using YAFFS with the 2.4.26-ts9 kernel on a Technologics TS-7250.
>>     
>
> Is that YAFFS2?
>
>   
>> When I set the SGID bit on a directory, files created under it do not
>> inherit the group ID, and directories created under it inherit neither
>> the group ID nor the SGID bit.
>>
>> I have a ramfs mount active at the same time (on /tmp), and the correct
>> SGID behavior occurs there, so it does seem to be a filesystem-specific
>> issue.
>>
>> Is there some mount option I should be using?  I tried the 'grpid'
>> mount option, but it had no effect on the problem.
>>     
>
> Could you send a bash script that can demo the problem?
>
> YAFFS does not listen to any mount options itself, but the VFS can be doing 
> things on its behalf.
>
> -- Charles
>   

-- 
Tom Hansen
Senior Information Processing Consultant
Great Lakes WATER Institute
tomh@uwm.edu
www.glwi.uwm.edu