On Wed, Dec 03, 2014 at 08:02:31AM +0530, Shriramana Sharma wrote: > On Tue, Dec 2, 2014 at 2:04 PM, Hugo Mills <hugo@xxxxxxxxxxxxx> wrote: > > > >> Is that correct: what btr sub list shows as "top level" is indeed the > >> parent subvolume? > > > > No, it's the top-level subvolume. (See my earlier mail about > > nomenclature). "Parent subvolume" has a number of meanings, none of > > which should be "the subvolume with subvolid 5". > > Um I searched my inbox but didn't find a specific definition from you > for "top-level". You only said it's better to avoid calling it "root" > to avoid confounding it with the subvol that may be mounted at root > i.e. /. It was the first line I wrote in my first reply to your thread about subvol 5 vs subvol 0. I had hoped to be both definitive and comprehensive. > IIUC the "top-level subvolume" can only be subvolid 5 which accords > with your later comment: > > > that putting files in the top-level subvol can't do what most people > > want to do with it. Hence the recommended subvol management layout at > > [1] https://btrfs.wiki.kernel.org/index.php/SysadminGuide#Subvolumes > > ... which means that I am not able to understand the output of btr sub > list which gives the subvolid of whichever subvol is currently the > "parent" (as in outer nesting) subvol. Observe: > > $ btr sub list . > ID 257 gen 10 top level 5 path test1 > ID 258 gen 10 top level 5 path test2 > ID 259 gen 9 top level 258 path test2/foo > $ sudo mv test2/foo test1/ > $ btr sub list . > ID 257 gen 10 top level 5 path test1 > ID 258 gen 10 top level 5 path test2 > ID 259 gen 9 top level 257 path test1/foo > $ > > So now what is the meaning of "top level"? Urgh. I haven't seriously looked at that piece of output in a while. That's broken, in my opinion. Here, "top level" means "containing subvolume ID". Hugo. -- Hugo Mills | "I don't like the look of it, I tell you." "Well, hugo@... carfax.org.uk | stop looking at it, then." http://carfax.org.uk/ | PGP: 65E74AC0 | The Goons
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