Re: btrfs filesystem show confused when label is same as mountpoint

Re: btrfs filesystem show confused when label is same as mountpoint

[Anand Jain]

I don't see that in 4.0, could you upgrade/try. thanks

---------------
mount /dev/sdf /data/Multimedia

btrfs fi show /data/Multimedia
Label: 'MULTIMEDIA'  uuid: 9b49bcc9-66d9-4f76-a57a-a60e2a16f15d
	Total devices 1 FS bytes used 192.00KiB
	devid    1 size 2.90GiB used 333.12MiB path /dev/sdf

btrfs-progs v4.0.1-2-ge8ceb61

btrfs fi show MULTIMEDIA
Label: 'MULTIMEDIA'  uuid: 9b49bcc9-66d9-4f76-a57a-a60e2a16f15d
	Total devices 1 FS bytes used 192.00KiB
	devid    1 size 2.90GiB used 333.12MiB path /dev/sdf

btrfs-progs v4.0.1-2-ge8ceb61
---------------

Anand


On 06/13/2015 03:20 PM, Sjoerd wrote:> Hi,
 >
 > I've a btrfs partition with label 'MULTIMEDIA' (all capitals) and 
mounted it
 > on /data/Multimedia (only M capital) and see the following when doing 
a btrfs
 > fi show:
 >
 > for mountpoint:
 > btrfs fi show /data/Multimedia
 > Btrfs v3.17
 >
 > versus for label:
 > btrfs fi show MULTIMEDIA
 > Label: 'MULTIMEDIA'  uuid: ce5d23cd-73a4-4f7c-83cd-2c40d12f6697
 >          Total devices 4 FS bytes used 5.04TiB
 >          devid    1 size 1.48TiB used 1.26TiB path /dev/sda2
 >          devid    2 size 1.48TiB used 1.26TiB path /dev/sdc2
 >          devid    3 size 1.48TiB used 1.26TiB path /dev/sdd2
 >          devid    4 size 1.48TiB used 1.26TiB path /dev/sde2
 >
 >
 > So in the latter case I get the results I was looking for.
 >
 >
 > It's not realy a question, but I couldn't find anything on the 
bugtracker (if
 > it's a bug in the first place) or a known something, so just to let you
 > know,cause I took me awhile to figure out why I didn't get results 
for this
 > particular mountpoint, while for others I did ;)
 >
 > Cheers,
 > Sjoerd
 >
 > --
 > 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
 >

Re: btrfs filesystem show confused when label is same as mountpoint

[Sjoerd]

On Saturday 13 June 2015 17:50:05 Anand Jain wrote:
> I don't see that in 4.0, could you upgrade/try. thanks
> 

That works fine indeed! Thanks....Could have thought to try that first myself ;)


> ---------------
> mount /dev/sdf /data/Multimedia
> 
> btrfs fi show /data/Multimedia
> Label: 'MULTIMEDIA'  uuid: 9b49bcc9-66d9-4f76-a57a-a60e2a16f15d
> 	Total devices 1 FS bytes used 192.00KiB
> 	devid    1 size 2.90GiB used 333.12MiB path /dev/sdf
> 
> btrfs-progs v4.0.1-2-ge8ceb61
> 
> btrfs fi show MULTIMEDIA
> Label: 'MULTIMEDIA'  uuid: 9b49bcc9-66d9-4f76-a57a-a60e2a16f15d
> 	Total devices 1 FS bytes used 192.00KiB
> 	devid    1 size 2.90GiB used 333.12MiB path /dev/sdf
> 
> btrfs-progs v4.0.1-2-ge8ceb61
> ---------------
> 
> Anand
> 
> 
> On 06/13/2015 03:20 PM, Sjoerd wrote:> Hi,
> 
>  > I've a btrfs partition with label 'MULTIMEDIA' (all capitals) and
> 
> mounted it
> 
>  > on /data/Multimedia (only M capital) and see the following when doing
> 
> a btrfs
> 
>  > fi show:
>  > 
>  > for mountpoint:
>  > btrfs fi show /data/Multimedia
>  > Btrfs v3.17
>  > 
>  > versus for label:
>  > btrfs fi show MULTIMEDIA
>  > Label: 'MULTIMEDIA'  uuid: ce5d23cd-73a4-4f7c-83cd-2c40d12f6697
>  > 
>  >          Total devices 4 FS bytes used 5.04TiB
>  >          devid    1 size 1.48TiB used 1.26TiB path /dev/sda2
>  >          devid    2 size 1.48TiB used 1.26TiB path /dev/sdc2
>  >          devid    3 size 1.48TiB used 1.26TiB path /dev/sdd2
>  >          devid    4 size 1.48TiB used 1.26TiB path /dev/sde2
>  > 
>  > So in the latter case I get the results I was looking for.
>  > 
>  > 
>  > It's not realy a question, but I couldn't find anything on the
> 
> bugtracker (if
> 
>  > it's a bug in the first place) or a known something, so just to let you
>  > know,cause I took me awhile to figure out why I didn't get results
> 
> for this
> 
>  > particular mountpoint, while for others I did ;)
>  > 
>  > Cheers,
>  > Sjoerd
>  > 
>  > --
>  > 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

[survey] BTRFS_IOC_DEVICES_READY return status

[Anand Jain]

BTRFS_IOC_DEVICES_READY is to check if all the required devices
are known by the btrfs kernel, so that admin/system-application
could mount the FS. It is checked against a device in the argument.

However the actual implementation is bit more than just that,
in the way that it would also scan and register the device
provided in the argument (same as btrfs device scan subcommand
or BTRFS_IOC_SCAN_DEV ioctl).

So BTRFS_IOC_DEVICES_READY ioctl isn't a read/view only ioctl,
but its a write command as well.

Next, since in the kernel we only check if total_devices
(read from SB)  is equal to num_devices (counted in the list)
to state the status as 0 (ready) or 1 (not ready). But this
does not work in rest of the device pool state like missing,
seeding, replacing since total_devices is actually not equal
to num_devices in these state but device pool is ready for
the mount and its a bug which is not part of this discussions.


Questions:

  - Do we want BTRFS_IOC_DEVICES_READY ioctl to also scan and
    register the device provided (same as btrfs device scan
    command or the BTRFS_IOC_SCAN_DEV ioctl)
    OR can BTRFS_IOC_DEVICES_READY be read-only ioctl interface
    to check the state of the device pool. ?

  - If the the device in the argument is already mounted,
    can it straightaway return 0 (ready) ? (as of now it would
    again independently read the SB determine total_devices
    and check against num_devices.

  - What should be the expected return when the FS is mounted
    and there is a missing device.


Thanks, Anand

btrfs filesystem show confused when label is same as mountpoint

[Sjoerd]

Hi,

I've a btrfs partition with label 'MULTIMEDIA' (all capitals) and mounted it 
on /data/Multimedia (only M capital) and see the following when doing a btrfs 
fi show:

for mountpoint:
btrfs fi show /data/Multimedia
Btrfs v3.17

versus for label:
btrfs fi show MULTIMEDIA
Label: 'MULTIMEDIA'  uuid: ce5d23cd-73a4-4f7c-83cd-2c40d12f6697
        Total devices 4 FS bytes used 5.04TiB
        devid    1 size 1.48TiB used 1.26TiB path /dev/sda2
        devid    2 size 1.48TiB used 1.26TiB path /dev/sdc2
        devid    3 size 1.48TiB used 1.26TiB path /dev/sdd2
        devid    4 size 1.48TiB used 1.26TiB path /dev/sde2


So in the latter case I get the results I was looking for.


It's not realy a question, but I couldn't find anything on the bugtracker (if 
it's a bug in the first place) or a known something, so just to let you 
know,cause I took me awhile to figure out why I didn't get results for this 
particular mountpoint, while for others I did ;)

Cheers,
Sjoerd

Re: btrfs filesystem show confused when label is same as mountpoint

[Duncan]

Sjoerd posted on Sat, 13 Jun 2015 09:20:12 +0200 as excerpted:

> versus for label:
> btrfs fi show MULTIMEDIA
> Label: 'MULTIMEDIA'  uuid: ce5d23cd-73a4-4f7c-83cd-2c40d12f6697

Hmm... I wasn't even aware that you could /use/ label!  But sure enough, 
it works here, too:

btrfs fi show rt0238gcnx+35l0
Label: 'rt0238gcnx+35l0'  uuid: 8f8d79ef-a86f-4306-a255-e0519e0f6132
        Total devices 2 FS bytes used 1.94GiB
        devid    1 size 8.00GiB used 3.78GiB path /dev/sda5
        devid    2 size 8.00GiB used 3.78GiB path /dev/sdb5

btrfs-progs v4.0.1


It works for UUID as well...

btrfs fi show 8f8d79ef-a86f-4306-a255-e0519e0f6132
Label: 'rt0238gcnx+35l0'  uuid: 8f8d79ef-a86f-4306-a255-e0519e0f6132
        Total devices 2 FS bytes used 1.94GiB
        devid    1 size 8.00GiB used 3.78GiB path /dev/sda5
        devid    2 size 8.00GiB used 3.78GiB path /dev/sdb5

btrfs-progs v4.0.1

... but that's a lot of arbitrary typing.

Doesn't work with partlabel or id (see /dev/disk/by-*), however. =:^(

Anyway, thanks!  Learned something new about btrfs fi show, today! =:^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

Re: btrfs filesystem show confused when label is same as mountpoint

[David Sterba]

On Sat, Jun 13, 2015 at 09:51:41AM +0000, Duncan wrote:
> Sjoerd posted on Sat, 13 Jun 2015 09:20:12 +0200 as excerpted:
> 
> > versus for label:
> > btrfs fi show MULTIMEDIA
> > Label: 'MULTIMEDIA'  uuid: ce5d23cd-73a4-4f7c-83cd-2c40d12f6697
> 
> Hmm... I wasn't even aware that you could /use/ label!  But sure enough, 
> it works here, too:
> 
> btrfs fi show rt0238gcnx+35l0
> Label: 'rt0238gcnx+35l0'  uuid: 8f8d79ef-a86f-4306-a255-e0519e0f6132
>         Total devices 2 FS bytes used 1.94GiB
>         devid    1 size 8.00GiB used 3.78GiB path /dev/sda5
>         devid    2 size 8.00GiB used 3.78GiB path /dev/sdb5
> 
> btrfs-progs v4.0.1
> 
> 
> It works for UUID as well...
> 
> btrfs fi show 8f8d79ef-a86f-4306-a255-e0519e0f6132
> Label: 'rt0238gcnx+35l0'  uuid: 8f8d79ef-a86f-4306-a255-e0519e0f6132
>         Total devices 2 FS bytes used 1.94GiB
>         devid    1 size 8.00GiB used 3.78GiB path /dev/sda5
>         devid    2 size 8.00GiB used 3.78GiB path /dev/sdb5
> 
> btrfs-progs v4.0.1
> 
> ... but that's a lot of arbitrary typing.
> 
> Doesn't work with partlabel or id (see /dev/disk/by-*), however. =:^(

The commandline tries to guess if it's label/uuid/path. If we want to
add support for partlabel and/or partuuid, we can't use the bare string,
but possibly the blkid tags, like

 $ btrfs fi show PARTUUID="8f8d79ef-a86f-4306-a255-e0519e0f6132"