Re: What to do about subvolumes?

[Josef Bacik <josef@redhat.com>]

On Wed, Dec 01, 2010 at 03:00:08PM -0500, J. Bruce Fields wrote:
> On Wed, Dec 01, 2010 at 02:54:33PM -0500, Josef Bacik wrote:
> > Oh well crud, I was hoping that I could leave the inode numbers as 256 for
> > everything, but I forgot about readdir.  So the inode item in the parent would
> > have to have a unique inode number that would get spit out in readdir, but then
> > if we stat'ed the directory we'd get 256 for the inode number.  Oh well,
> > incompat flag it is then.
> 
> I think you're already fine:
> 
> 	# mkdir TMP
> 	# dd if=/dev/zero of=TMP-image bs=1M count=512
> 	# mkfs.btrfs TMP-image
> 	# mount -oloop TMP-image TMP/
> 	# btrfs subvolume create sub-a
> 	# btrfs subvolume create sub-b
> 	../readdir-inos .
> 	. 256 256
> 	.. 256 4130609
> 	sub-a 256 256
> 	sub-b 257 256
> 
> Where readdir-inos is my silly test program below, and the first number is from
> readdir, the second from stat.
>

Heh as soon as I typed my email I went and actually looked at the code, looks
like for readdir we fill in the root id, which will be unique, so hotdamn we are
good and I don't have to use a stupid incompat flag.  Thanks for checking that
:),

Josef