Re: btrfs subvolume list: what is the meaning of "top level"

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Nov 9, 2013, at 11:10 AM, Goffredo Baroncelli <kreijack@xxxxxxxxx> wrote:
> 
>     1	ID 256 gen 5 top level 5 path sub1
>     2	ID 257 gen 6 top level 5 path dir/sub2
>     3	ID 258 gen 8 top level 5 path dir/sub3
>     4	ID 259 gen 8 top level 5 path dir/sub3/sub4
>     5	ID 260 gen 10 top level 5 path sub5
>     6	ID 261 gen 10 top level 5 path sub5/sub6

> 
> 
> I expected that in the line 4, the top level should be 258; the same for
> the line 6: top level should be 260. So my question is: what is the
> meaning of the "top level" value ?

If you mount -o subvol=sub5 and then create a new subvolume, and then do a listing, you'll see something like what you describe. It would look something like:

6	ID 262 gen 4 top level 260 path sub6

The "top level" is in a sense a prefix. So top level 5 means there is no prefix, the path listed is the full path. Whereas if the top level is e.g. 260, the implied prefix is sub5/.

If you were to mount subvolid=259 and create a subvolume in at the root of the mountpoint, then do a subvolume listing, it would be listed with top level 259 and a path of merely "newname" rather than dir/sub3/sub4/newname.

So just consider the top level a prefix for the listed path, and if the top level is 5, there is no prefix for path, the path is the full path.


Chris Murphy--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Filesystem Development]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux