Initial mount with inode32 option

[Ben Myers]

Hi Harry,

On Thu, Jan 24, 2013 at 08:27:32AM -0800, Harry Edmon wrote:
> I see that some of the discussion on the mailing list has to do with
> smaller disk partition. 

Dave showed that filesystems which are too small to create 64 bit inodes will
report still report an inode allocation policy of inode64 even when inode32 is
specified in the mount options.  This doesn't mean that 64 bit inodes will be
created.

> I would like this option for big partisions
> (i.e. 2 TB and greater)

Lets try a 2TB filesystem:

## create a sparse file by writing a byte at 2 terabyte offset 
# xfs_io -c "pwrite 2t 1" -f 2t
wrote 1/1 bytes at offset 2199023255552

## make a filesystem in that sparse file
# mkfs.xfs 2t
meta-data=2t                     isize=256    agcount=4, agsize=134217728 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=536870912, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=262144, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

## mount it up with the loop device
# mount -o loop,inode32 2t /mnt2

# grep /mnt2 /proc/mounts
/dev/loop0 /mnt2 xfs rw,relatime,attr2,inode32,noquota 0 0
				       ^^^^^^^

It looks like it works as expected on a 2tb filesystem.  We specified the
inode32 mount option and it reports an inode allocation policy of inode32 on a
filesystem that is big enough to create 64 bit inodes.  In this situation no 64
bit inodes will be created. 

> so I can have the option to continue
> compatibility with Networker as I could with older Linux kernels.

Based upon Dave's comments and the above I think you're in good shape.  Looks
like I prematurely jumped to the conclusion that we have a problem.

Have you run into a compatability issue that you can describe?

Thanks,
Ben