* "@" prefix in subvolume paths
@ 2015-06-09 17:55 pubny
2015-06-10 23:10 ` Hugo Mills
0 siblings, 1 reply; 6+ messages in thread
From: pubny @ 2015-06-09 17:55 UTC (permalink / raw)
To: linux-btrfs
Hi,
I've noticed this "@" sign in the subvolume's path with SLES12. I'm
wondering what is its purpose. openSUSE 13.2 doesn't seem to be using
it.
Thanks,
Gábor
SLES12:
# btrfs sub list /
ID 257 gen 2270 top level 5 path @
ID 258 gen 1655 top level 257 path @/boot/grub2/i386-pc
ID 259 gen 4263 top level 257 path @/boot/grub2/x86_64-efi
ID 260 gen 4037 top level 257 path @/opt
ID 261 gen 2553 top level 257 path @/srv
ID 262 gen 4521 top level 257 path @/tmp
ID 263 gen 4492 top level 257 path @/usr/local
ID 264 gen 1655 top level 257 path @/var/crash
ID 265 gen 1655 top level 257 path @/var/lib/mailman
ID 266 gen 1655 top level 257 path @/var/lib/named
ID 267 gen 1655 top level 257 path @/var/lib/pgsql
ID 268 gen 4523 top level 257 path @/var/log
ID 269 gen 1655 top level 257 path @/var/opt
ID 270 gen 4524 top level 257 path @/var/spool
ID 271 gen 4521 top level 257 path @/var/tmp
ID 275 gen 4505 top level 257 path @/.snapshots
openSUSE 13.2:
# btrfs subvol list /
ID 257 gen 3481911 top level 5 path boot/grub2/i386-pc
ID 258 gen 3481911 top level 5 path boot/grub2/x86_64-efi
ID 259 gen 3517714 top level 5 path home
ID 260 gen 3515789 top level 5 path opt
ID 261 gen 3513493 top level 5 path srv
ID 262 gen 3513372 top level 5 path tmp
ID 263 gen 3517660 top level 5 path usr/local
ID 264 gen 3513372 top level 5 path var/crash
ID 265 gen 3513372 top level 5 path var/lib/mailman
ID 266 gen 3513372 top level 5 path var/lib/named
ID 267 gen 3513372 top level 5 path var/lib/pgsql
ID 268 gen 3517714 top level 5 path var/log
ID 269 gen 3513372 top level 5 path var/opt
ID 270 gen 3517714 top level 5 path var/spool
ID 271 gen 3517706 top level 5 path var/tmp
ID 276 gen 3517669 top level 5 path .snapshots
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: "@" prefix in subvolume paths
2015-06-09 17:55 "@" prefix in subvolume paths pubny
@ 2015-06-10 23:10 ` Hugo Mills
2015-06-10 23:37 ` gny
2015-06-11 1:50 ` Jeff Mahoney
0 siblings, 2 replies; 6+ messages in thread
From: Hugo Mills @ 2015-06-10 23:10 UTC (permalink / raw)
To: pubny; +Cc: linux-btrfs
[-- Attachment #1: Type: text/plain, Size: 2517 bytes --]
On Tue, Jun 09, 2015 at 07:55:05PM +0200, pubny@xs4all.nl wrote:
> Hi,
>
> I've noticed this "@" sign in the subvolume's path with SLES12. I'm
> wondering what is its purpose. openSUSE 13.2 doesn't seem to be using
> it.
They created a subvolume called "@" and then put all the other
subvolumes under there. There's nothing special about it.
The @ is often used as a prefix on subvolumes (e.g. in Ubuntu) to
indicate that they're subvolumes, but it's not required, and doesn't
have any extra meaning beyond being a useful naming convention.
Hugo.
> Thanks,
> Gábor
>
>
> SLES12:
> # btrfs sub list /
> ID 257 gen 2270 top level 5 path @
> ID 258 gen 1655 top level 257 path @/boot/grub2/i386-pc
> ID 259 gen 4263 top level 257 path @/boot/grub2/x86_64-efi
> ID 260 gen 4037 top level 257 path @/opt
> ID 261 gen 2553 top level 257 path @/srv
> ID 262 gen 4521 top level 257 path @/tmp
> ID 263 gen 4492 top level 257 path @/usr/local
> ID 264 gen 1655 top level 257 path @/var/crash
> ID 265 gen 1655 top level 257 path @/var/lib/mailman
> ID 266 gen 1655 top level 257 path @/var/lib/named
> ID 267 gen 1655 top level 257 path @/var/lib/pgsql
> ID 268 gen 4523 top level 257 path @/var/log
> ID 269 gen 1655 top level 257 path @/var/opt
> ID 270 gen 4524 top level 257 path @/var/spool
> ID 271 gen 4521 top level 257 path @/var/tmp
> ID 275 gen 4505 top level 257 path @/.snapshots
>
>
> openSUSE 13.2:
>
> # btrfs subvol list /
> ID 257 gen 3481911 top level 5 path boot/grub2/i386-pc
> ID 258 gen 3481911 top level 5 path boot/grub2/x86_64-efi
> ID 259 gen 3517714 top level 5 path home
> ID 260 gen 3515789 top level 5 path opt
> ID 261 gen 3513493 top level 5 path srv
> ID 262 gen 3513372 top level 5 path tmp
> ID 263 gen 3517660 top level 5 path usr/local
> ID 264 gen 3513372 top level 5 path var/crash
> ID 265 gen 3513372 top level 5 path var/lib/mailman
> ID 266 gen 3513372 top level 5 path var/lib/named
> ID 267 gen 3513372 top level 5 path var/lib/pgsql
> ID 268 gen 3517714 top level 5 path var/log
> ID 269 gen 3513372 top level 5 path var/opt
> ID 270 gen 3517714 top level 5 path var/spool
> ID 271 gen 3517706 top level 5 path var/tmp
> ID 276 gen 3517669 top level 5 path .snapshots
--
Hugo Mills | ... one ping(1) to rule them all, and in the
hugo@... carfax.org.uk | darkness bind(2) them.
http://carfax.org.uk/ |
PGP: E2AB1DE4 | Illiad
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: "@" prefix in subvolume paths
2015-06-10 23:10 ` Hugo Mills
@ 2015-06-10 23:37 ` gny
2015-06-11 1:50 ` Jeff Mahoney
1 sibling, 0 replies; 6+ messages in thread
From: gny @ 2015-06-10 23:37 UTC (permalink / raw)
To: Hugo Mills; +Cc: linux-btrfs
I see... quite underwhelming explanation :-) I thought there is some
special trick here.
Thanks,
Gábor
On Wed, 10 Jun 2015 23:10:14 +0000
Hugo Mills <hugo@carfax.org.uk> wrote:
> On Tue, Jun 09, 2015 at 07:55:05PM +0200, pubny@xs4all.nl wrote:
> > Hi,
> >
> > I've noticed this "@" sign in the subvolume's path with SLES12. I'm
> > wondering what is its purpose. openSUSE 13.2 doesn't seem to be
> > using it.
>
> They created a subvolume called "@" and then put all the other
> subvolumes under there. There's nothing special about it.
>
> The @ is often used as a prefix on subvolumes (e.g. in Ubuntu) to
> indicate that they're subvolumes, but it's not required, and doesn't
> have any extra meaning beyond being a useful naming convention.
>
> Hugo.
>
> > Thanks,
> > Gábor
> >
> >
> > SLES12:
> > # btrfs sub list /
> > ID 257 gen 2270 top level 5 path @
> > ID 258 gen 1655 top level 257 path @/boot/grub2/i386-pc
> > ID 259 gen 4263 top level 257 path @/boot/grub2/x86_64-efi
> > ID 260 gen 4037 top level 257 path @/opt
> > ID 261 gen 2553 top level 257 path @/srv
> > ID 262 gen 4521 top level 257 path @/tmp
> > ID 263 gen 4492 top level 257 path @/usr/local
> > ID 264 gen 1655 top level 257 path @/var/crash
> > ID 265 gen 1655 top level 257 path @/var/lib/mailman
> > ID 266 gen 1655 top level 257 path @/var/lib/named
> > ID 267 gen 1655 top level 257 path @/var/lib/pgsql
> > ID 268 gen 4523 top level 257 path @/var/log
> > ID 269 gen 1655 top level 257 path @/var/opt
> > ID 270 gen 4524 top level 257 path @/var/spool
> > ID 271 gen 4521 top level 257 path @/var/tmp
> > ID 275 gen 4505 top level 257 path @/.snapshots
> >
> >
> > openSUSE 13.2:
> >
> > # btrfs subvol list /
> > ID 257 gen 3481911 top level 5 path boot/grub2/i386-pc
> > ID 258 gen 3481911 top level 5 path boot/grub2/x86_64-efi
> > ID 259 gen 3517714 top level 5 path home
> > ID 260 gen 3515789 top level 5 path opt
> > ID 261 gen 3513493 top level 5 path srv
> > ID 262 gen 3513372 top level 5 path tmp
> > ID 263 gen 3517660 top level 5 path usr/local
> > ID 264 gen 3513372 top level 5 path var/crash
> > ID 265 gen 3513372 top level 5 path var/lib/mailman
> > ID 266 gen 3513372 top level 5 path var/lib/named
> > ID 267 gen 3513372 top level 5 path var/lib/pgsql
> > ID 268 gen 3517714 top level 5 path var/log
> > ID 269 gen 3513372 top level 5 path var/opt
> > ID 270 gen 3517714 top level 5 path var/spool
> > ID 271 gen 3517706 top level 5 path var/tmp
> > ID 276 gen 3517669 top level 5 path .snapshots
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: "@" prefix in subvolume paths
2015-06-10 23:10 ` Hugo Mills
2015-06-10 23:37 ` gny
@ 2015-06-11 1:50 ` Jeff Mahoney
2015-06-11 9:02 ` Dimitri John Ledkov
2015-06-15 8:53 ` Gábor Nyers
1 sibling, 2 replies; 6+ messages in thread
From: Jeff Mahoney @ 2015-06-11 1:50 UTC (permalink / raw)
To: Hugo Mills, pubny, linux-btrfs
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 6/10/15 7:10 PM, Hugo Mills wrote:
> On Tue, Jun 09, 2015 at 07:55:05PM +0200, pubny@xs4all.nl wrote:
>> Hi,
>>
>> I've noticed this "@" sign in the subvolume's path with SLES12.
>> I'm wondering what is its purpose. openSUSE 13.2 doesn't seem to
>> be using it.
>
> They created a subvolume called "@" and then put all the other
> subvolumes under there. There's nothing special about it.
>
> The @ is often used as a prefix on subvolumes (e.g. in Ubuntu) to
> indicate that they're subvolumes, but it's not required, and
> doesn't have any extra meaning beyond being a useful naming
> convention.
Yep. That explanation is accurate but is missing the rest of the
story. The choice of @ is probably due to following the convention
started by the Ubuntu folks but also because it's the least
complicated of the alternative names we could have used. The @
subvolume is set as the default subvolume. As you'd expect, it's
mounted at / and used as such. The reason we use a separate subvolume
is so we can easily implement our boot-and-rollback-from-snapshot
functionality in SLE12. Having the root file system as a separate
subvolume means we can move one of the snapshot subvolumes into the fs
tree root, move the other @ subvolumes into that subvolume, and we
have a rolled back system from which we can easily remove the
now-unused root. If we didn't use a separate subvolume for it, it
would make the rollback very complicated. It's used in concert with
our GRUB implementation that iterates and presents possible snapshots
to use as a root file system in lieu of the "real" one should a
problem occur.
- -Jeff
>>
>> SLES12: # btrfs sub list / ID 257 gen 2270 top level 5 path @ ID
>> 258 gen 1655 top level 257 path @/boot/grub2/i386-pc ID 259 gen
>> 4263 top level 257 path @/boot/grub2/x86_64-efi ID 260 gen 4037
>> top level 257 path @/opt ID 261 gen 2553 top level 257 path
>> @/srv ID 262 gen 4521 top level 257 path @/tmp ID 263 gen 4492
>> top level 257 path @/usr/local ID 264 gen 1655 top level 257 path
>> @/var/crash ID 265 gen 1655 top level 257 path @/var/lib/mailman
>> ID 266 gen 1655 top level 257 path @/var/lib/named ID 267 gen
>> 1655 top level 257 path @/var/lib/pgsql ID 268 gen 4523 top level
>> 257 path @/var/log ID 269 gen 1655 top level 257 path @/var/opt
>> ID 270 gen 4524 top level 257 path @/var/spool ID 271 gen 4521
>> top level 257 path @/var/tmp ID 275 gen 4505 top level 257 path
>> @/.snapshots
>>
>>
>> openSUSE 13.2:
>>
>> # btrfs subvol list / ID 257 gen 3481911 top level 5 path
>> boot/grub2/i386-pc ID 258 gen 3481911 top level 5 path
>> boot/grub2/x86_64-efi ID 259 gen 3517714 top level 5 path home ID
>> 260 gen 3515789 top level 5 path opt ID 261 gen 3513493 top level
>> 5 path srv ID 262 gen 3513372 top level 5 path tmp ID 263 gen
>> 3517660 top level 5 path usr/local ID 264 gen 3513372 top level 5
>> path var/crash ID 265 gen 3513372 top level 5 path
>> var/lib/mailman ID 266 gen 3513372 top level 5 path
>> var/lib/named ID 267 gen 3513372 top level 5 path var/lib/pgsql
>> ID 268 gen 3517714 top level 5 path var/log ID 269 gen 3513372
>> top level 5 path var/opt ID 270 gen 3517714 top level 5 path
>> var/spool ID 271 gen 3517706 top level 5 path var/tmp ID 276 gen
>> 3517669 top level 5 path .snapshots
>
- --
Jeff Mahoney
SUSE Labs
-----BEGIN PGP SIGNATURE-----
Version: GnuPG/MacGPG2 v2.0.19 (Darwin)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=lO/K
-----END PGP SIGNATURE-----
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: "@" prefix in subvolume paths
2015-06-11 1:50 ` Jeff Mahoney
@ 2015-06-11 9:02 ` Dimitri John Ledkov
2015-06-15 8:53 ` Gábor Nyers
1 sibling, 0 replies; 6+ messages in thread
From: Dimitri John Ledkov @ 2015-06-11 9:02 UTC (permalink / raw)
To: Jeff Mahoney; +Cc: Hugo Mills, pubny, linux-btrfs
On 11 June 2015 at 02:50, Jeff Mahoney <jeffm@suse.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 6/10/15 7:10 PM, Hugo Mills wrote:
>> On Tue, Jun 09, 2015 at 07:55:05PM +0200, pubny@xs4all.nl wrote:
>>> Hi,
>>>
>>> I've noticed this "@" sign in the subvolume's path with SLES12.
>>> I'm wondering what is its purpose. openSUSE 13.2 doesn't seem to
>>> be using it.
>>
>> They created a subvolume called "@" and then put all the other
>> subvolumes under there. There's nothing special about it.
>>
>> The @ is often used as a prefix on subvolumes (e.g. in Ubuntu) to
>> indicate that they're subvolumes, but it's not required, and
>> doesn't have any extra meaning beyond being a useful naming
>> convention.
>
> Yep. That explanation is accurate but is missing the rest of the
> story. The choice of @ is probably due to following the convention
> started by the Ubuntu folks but also because it's the least
> complicated of the alternative names we could have used. The @
> subvolume is set as the default subvolume. As you'd expect, it's
> mounted at / and used as such. The reason we use a separate subvolume
> is so we can easily implement our boot-and-rollback-from-snapshot
> functionality in SLE12. Having the root file system as a separate
> subvolume means we can move one of the snapshot subvolumes into the fs
> tree root, move the other @ subvolumes into that subvolume, and we
> have a rolled back system from which we can easily remove the
> now-unused root. If we didn't use a separate subvolume for it, it
> would make the rollback very complicated. It's used in concert with
> our GRUB implementation that iterates and presents possible snapshots
> to use as a root file system in lieu of the "real" one should a
> problem occur.
>
Interesting, can you point out to that GRUB implementation bits? On at
least Ubuntu i believe we currently require to boot off @ subvolume,
and don't offer the option to boot into a snapshot.
But that would be very disarable, since e.g. with apt-snapshot
installed we do generate checkpoint snapshot before each upgrade.
Getting easy option to roll back to that would be awesome.
Regards,
Dimitri.
> - -Jeff
>
>>>
>>> SLES12: # btrfs sub list / ID 257 gen 2270 top level 5 path @ ID
>>> 258 gen 1655 top level 257 path @/boot/grub2/i386-pc ID 259 gen
>>> 4263 top level 257 path @/boot/grub2/x86_64-efi ID 260 gen 4037
>>> top level 257 path @/opt ID 261 gen 2553 top level 257 path
>>> @/srv ID 262 gen 4521 top level 257 path @/tmp ID 263 gen 4492
>>> top level 257 path @/usr/local ID 264 gen 1655 top level 257 path
>>> @/var/crash ID 265 gen 1655 top level 257 path @/var/lib/mailman
>>> ID 266 gen 1655 top level 257 path @/var/lib/named ID 267 gen
>>> 1655 top level 257 path @/var/lib/pgsql ID 268 gen 4523 top level
>>> 257 path @/var/log ID 269 gen 1655 top level 257 path @/var/opt
>>> ID 270 gen 4524 top level 257 path @/var/spool ID 271 gen 4521
>>> top level 257 path @/var/tmp ID 275 gen 4505 top level 257 path
>>> @/.snapshots
>>>
>>>
>>> openSUSE 13.2:
>>>
>>> # btrfs subvol list / ID 257 gen 3481911 top level 5 path
>>> boot/grub2/i386-pc ID 258 gen 3481911 top level 5 path
>>> boot/grub2/x86_64-efi ID 259 gen 3517714 top level 5 path home ID
>>> 260 gen 3515789 top level 5 path opt ID 261 gen 3513493 top level
>>> 5 path srv ID 262 gen 3513372 top level 5 path tmp ID 263 gen
>>> 3517660 top level 5 path usr/local ID 264 gen 3513372 top level 5
>>> path var/crash ID 265 gen 3513372 top level 5 path
>>> var/lib/mailman ID 266 gen 3513372 top level 5 path
>>> var/lib/named ID 267 gen 3513372 top level 5 path var/lib/pgsql
>>> ID 268 gen 3517714 top level 5 path var/log ID 269 gen 3513372
>>> top level 5 path var/opt ID 270 gen 3517714 top level 5 path
>>> var/spool ID 271 gen 3517706 top level 5 path var/tmp ID 276 gen
>>> 3517669 top level 5 path .snapshots
>>
>
>
> - --
> Jeff Mahoney
> SUSE Labs
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG/MacGPG2 v2.0.19 (Darwin)
>
> iQIcBAEBAgAGBQJVeOlbAAoJEB57S2MheeWy0JYP/1mbM5ybHNcwEB21CbS+5ujv
> omBmiVhX6nAcTDAJ2OJG7MsrE4L1j93R8gv/xRkPjBLuaiqJ+wr88VaG/AcKvtSZ
> qMF64PJCNzsXFd0FFPi8CNXxhVbJyEKF+m8Xl+tfRsMhsNIKdbqkMHInMc99qWJH
> dMLTSYObvdo9AYIkOj8PM6nBjeQ4zEBQY9uOf9M9HL8Ulc1VQgzSu1giuvHg8/Cf
> Ela2iZJi2APZeNisQtQcJssMyBaDTbSH0RhQh8kcdfG6GCruSDR8AWbyuY36OeaG
> 5Ifp4J7oSS+eUwlTtvLFfZl079VmJWZbF/KEy8GfY++kp+BVB95Z8QOKVOVTEA8A
> 4AvkMfdGvtykZJNRskXGaIsUIX07iTmT2f+VyN7jbfp2J5FyBALp+i4Ub5fyjUZG
> +OWcAIkTC9z2AQW77ZMdA4DdkHk5bi3aRSCNV1gSPGDib5CH5ZLyMY/KKtxCLSnO
> syNdcZmQs4bb7FZBfcM4CQraUYsnBl4ArGechkMWpJCrMx2dtRrGlKlh+7KmG+m8
> 60xBKU3ApmZrcKUTAcWvN2cy72xmc8GZaOPnNepAUhMLduarsEtyCemOkGCZxRiu
> c0QRGhGBgK91MBF1KxXzrnO0cm1ijdjMAbwmol6vEYRzXItXK3AeD74IeY6Abqr/
> U2lTFYlKYpkTmzhk0gM8
> =lO/K
> -----END PGP SIGNATURE-----
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Regards,
Dimitri.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: "@" prefix in subvolume paths
2015-06-11 1:50 ` Jeff Mahoney
2015-06-11 9:02 ` Dimitri John Ledkov
@ 2015-06-15 8:53 ` Gábor Nyers
1 sibling, 0 replies; 6+ messages in thread
From: Gábor Nyers @ 2015-06-15 8:53 UTC (permalink / raw)
To: Jeff Mahoney; +Cc: Hugo Mills, linux-btrfs
Jeff,
Thanks for elaborating on this. I'm wondering where in the
SLES/openSUSE documentation these considerations are documented. Do you
have a pointer?
Thanks,
Gábor
On Wed, 10 Jun 2015 21:50:19 -0400
Jeff Mahoney <jeffm@suse.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 6/10/15 7:10 PM, Hugo Mills wrote:
> > On Tue, Jun 09, 2015 at 07:55:05PM +0200, pubny@xs4all.nl wrote:
> >> Hi,
> >>
> >> I've noticed this "@" sign in the subvolume's path with SLES12.
> >> I'm wondering what is its purpose. openSUSE 13.2 doesn't seem to
> >> be using it.
> >
> > They created a subvolume called "@" and then put all the other
> > subvolumes under there. There's nothing special about it.
> >
> > The @ is often used as a prefix on subvolumes (e.g. in Ubuntu) to
> > indicate that they're subvolumes, but it's not required, and
> > doesn't have any extra meaning beyond being a useful naming
> > convention.
>
> Yep. That explanation is accurate but is missing the rest of the
> story. The choice of @ is probably due to following the convention
> started by the Ubuntu folks but also because it's the least
> complicated of the alternative names we could have used. The @
> subvolume is set as the default subvolume. As you'd expect, it's
> mounted at / and used as such. The reason we use a separate subvolume
> is so we can easily implement our boot-and-rollback-from-snapshot
> functionality in SLE12. Having the root file system as a separate
> subvolume means we can move one of the snapshot subvolumes into the fs
> tree root, move the other @ subvolumes into that subvolume, and we
> have a rolled back system from which we can easily remove the
> now-unused root. If we didn't use a separate subvolume for it, it
> would make the rollback very complicated. It's used in concert with
> our GRUB implementation that iterates and presents possible snapshots
> to use as a root file system in lieu of the "real" one should a
> problem occur.
>
> - -Jeff
>
> >>
> >> SLES12: # btrfs sub list / ID 257 gen 2270 top level 5 path @ ID
> >> 258 gen 1655 top level 257 path @/boot/grub2/i386-pc ID 259 gen
> >> 4263 top level 257 path @/boot/grub2/x86_64-efi ID 260 gen 4037
> >> top level 257 path @/opt ID 261 gen 2553 top level 257 path
> >> @/srv ID 262 gen 4521 top level 257 path @/tmp ID 263 gen 4492
> >> top level 257 path @/usr/local ID 264 gen 1655 top level 257 path
> >> @/var/crash ID 265 gen 1655 top level 257 path @/var/lib/mailman
> >> ID 266 gen 1655 top level 257 path @/var/lib/named ID 267 gen
> >> 1655 top level 257 path @/var/lib/pgsql ID 268 gen 4523 top level
> >> 257 path @/var/log ID 269 gen 1655 top level 257 path @/var/opt
> >> ID 270 gen 4524 top level 257 path @/var/spool ID 271 gen 4521
> >> top level 257 path @/var/tmp ID 275 gen 4505 top level 257 path
> >> @/.snapshots
> >>
> >>
> >> openSUSE 13.2:
> >>
> >> # btrfs subvol list / ID 257 gen 3481911 top level 5 path
> >> boot/grub2/i386-pc ID 258 gen 3481911 top level 5 path
> >> boot/grub2/x86_64-efi ID 259 gen 3517714 top level 5 path home ID
> >> 260 gen 3515789 top level 5 path opt ID 261 gen 3513493 top level
> >> 5 path srv ID 262 gen 3513372 top level 5 path tmp ID 263 gen
> >> 3517660 top level 5 path usr/local ID 264 gen 3513372 top level 5
> >> path var/crash ID 265 gen 3513372 top level 5 path
> >> var/lib/mailman ID 266 gen 3513372 top level 5 path
> >> var/lib/named ID 267 gen 3513372 top level 5 path var/lib/pgsql
> >> ID 268 gen 3517714 top level 5 path var/log ID 269 gen 3513372
> >> top level 5 path var/opt ID 270 gen 3517714 top level 5 path
> >> var/spool ID 271 gen 3517706 top level 5 path var/tmp ID 276 gen
> >> 3517669 top level 5 path .snapshots
> >
>
>
> - --
> Jeff Mahoney
> SUSE Labs
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG/MacGPG2 v2.0.19 (Darwin)
>
> iQIcBAEBAgAGBQJVeOlbAAoJEB57S2MheeWy0JYP/1mbM5ybHNcwEB21CbS+5ujv
> omBmiVhX6nAcTDAJ2OJG7MsrE4L1j93R8gv/xRkPjBLuaiqJ+wr88VaG/AcKvtSZ
> qMF64PJCNzsXFd0FFPi8CNXxhVbJyEKF+m8Xl+tfRsMhsNIKdbqkMHInMc99qWJH
> dMLTSYObvdo9AYIkOj8PM6nBjeQ4zEBQY9uOf9M9HL8Ulc1VQgzSu1giuvHg8/Cf
> Ela2iZJi2APZeNisQtQcJssMyBaDTbSH0RhQh8kcdfG6GCruSDR8AWbyuY36OeaG
> 5Ifp4J7oSS+eUwlTtvLFfZl079VmJWZbF/KEy8GfY++kp+BVB95Z8QOKVOVTEA8A
> 4AvkMfdGvtykZJNRskXGaIsUIX07iTmT2f+VyN7jbfp2J5FyBALp+i4Ub5fyjUZG
> +OWcAIkTC9z2AQW77ZMdA4DdkHk5bi3aRSCNV1gSPGDib5CH5ZLyMY/KKtxCLSnO
> syNdcZmQs4bb7FZBfcM4CQraUYsnBl4ArGechkMWpJCrMx2dtRrGlKlh+7KmG+m8
> 60xBKU3ApmZrcKUTAcWvN2cy72xmc8GZaOPnNepAUhMLduarsEtyCemOkGCZxRiu
> c0QRGhGBgK91MBF1KxXzrnO0cm1ijdjMAbwmol6vEYRzXItXK3AeD74IeY6Abqr/
> U2lTFYlKYpkTmzhk0gM8
> =lO/K
> -----END PGP SIGNATURE-----
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-btrfs" in the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2015-06-15 8:52 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-06-09 17:55 "@" prefix in subvolume paths pubny
2015-06-10 23:10 ` Hugo Mills
2015-06-10 23:37 ` gny
2015-06-11 1:50 ` Jeff Mahoney
2015-06-11 9:02 ` Dimitri John Ledkov
2015-06-15 8:53 ` Gábor Nyers
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.