The following has be reported by IBM LTC:  
statfs() fills in statfs struct with zero'ed f_fsid (0-0 pair)
Hardware Environment: Dual Pentium III 1266 MHz, 2G RAM

Software Environment: Red Hat Linux release 7.2, kernel 2.4.9-31enterprise
(Also RHAS 3.0)

Steps to Reproduce:
1. call statfs() passing any filename and an empty statfs struct
2. dump filled-in statfs struct
3. f_fsid always (0,0) valued integer pair while f_type, f_bsize, etc. valid

Actual Results: f_fsid always (0,0) pair rather than file system ID

Expected Results: valid file system ID that can be passed to sysfs() to
determine file system identifier (e.g. /home, /, etc.) 

Additional Information:
Attached test code to demonstrate this issue.  Simply compile and run passing a
valid file name.Created an attachment (id=1150)
bug-reproducing test program
Vincent,
Does problem occur for all file system types ?
What is the file system type you are using when you hit the problem ?
ThanksIn my limited testing, ext2 and ext3 so far.

Vincent
Hi Vincent,
Thanks.  Also please append the output of 
  rpm -qa | grep -i glibc
so we know which level of glibc you have.
We need to re-create problem here to debug.   Thanks.
$ rpm -qa | grep -i glibc
glibc-2.2.4-13
glibc-common-2.2.4-13
compat-glibc-6.2-2.1.3.2
glibc-devel-2.2.4-13

VincentInstalled RH 7.2 - testcase returns 0 for __fsid_t.

This is also 0 on SLES 8  - on IA32 and PowerPC.

I did man statfs, I did not get any info about what fsid is supposed to return.

I am checking with Steve Best ( jfs team lead ) about whether or not anything 
valid is even put into the fsid field.  
I will also check with Mark Brown ( glibc standard, LTC lead ) tomorrow about 
what the standard says.

Vincent, why do you need the fsid field.  What do you expect to do with it ?
Went to talk to David Kleikamp ( jfs development ).   He told me jfs currently 
does not do anything with that field either.  He told me it is easy enough to 
add something like device number into that field like bfs.

checking into the kernel source tree, bfs_statfs in 
  /usr/src/linux-2.4/fs/bfs/inode.c sets the fsid field to device number
-------------------------------------------------------------------------

static int bfs_statfs(struct super_block *s, struct statfs *buf)
{
        buf->f_type = BFS_MAGIC;
        buf->f_bsize = s->s_blocksize;
        buf->f_blocks = s->su_blocks;
        buf->f_bfree = buf->f_bavail = s->su_freeb;
        buf->f_files = s->su_lasti + 1 - BFS_ROOT_INO;
        buf->f_ffree = s->su_freei;
        buf->f_fsid.val[0] = kdev_t_to_nr(s->s_dev);    ----> this is the code
        buf->f_namelen = BFS_NAMELEN;
        return 0;
}
------------------------------------------------------------------------

It should be easy enough to add to
  for ext2, ext2_statfs is in /usr/src/linux-2.4/fs/ext2/super.c
  for ext3, ext3_statfs is in /usr/src/linux-2.4/fs/ext3/super.c
  for reiserfs, reiserfs_statfs is in /usr/src/linux-2.4/fs/reiserfs/super.c
  
I am not sure this should be done on all filesystems on Linux yet.

Mark Brown checked into the standards. fsid of 0 is perfectly legit.
LSB does not mention anything about what fsid should be.

I'll talk to Mark again next week to see the best way to pursue this.

Vincent,  please let us know why DB2 needs that fsid field and what do you 
expect it to be.

 
We'd like a unique way of identifying the file system containing a specified
file.  This can be accomplished either by obtaining a file system ID value (and
pass it to sysfs() to get the file system name) or alternatively, by obtaining
the file system name directly.

VincentAdded Mark Brown to cc list so he can add comments to this problem.  Thanks 
Mark.Opened problem #3436 against jfs so David Kleikamp can put the changes into 
jfs_statfs. I'll try to get RedHat AS 3.0 alpha and re-create on there.
Salina

Additionally, we'd entertain any suggestions on workarounds to getting a file
system identifier from the system.  However, only APIs calls are satisfactory...
invoking other programs (e.g. df <filename>) would not be an option.

Thanks,
Vincent
Glen,
I borrowed machine that has RHAS 3.0 alpha from LTC test, this problem is still 
there, so you can report that to RedHat.  Thanks.
----------------------------------------------------------------------
[root@nortel salina]# uname -a
Linux nortel.ltc.austin.ibm.com 2.4.20-1.1931.2.231.2.11.entbigmem #1 SMP Tue 
Jun 17 14:35:18 EDT 2003 i686 i686 i386 GNU/Linux
[root@nortel salina]# ./test_statfs /skyline/sglass

f_fsid.__val[0] = 0
f_fsid.__val[1] = 0
f_type          = 6969
f_bsize         = 4096
[root@nortel salina]# ./test_statfs /var/log/messages

f_fsid.__val[0] = 0
f_fsid.__val[1] = 0
f_type          = EF53
f_bsize         = 4096

----------------------------------------------------------------