Re: Btrfs-progs release 3.17

[Gui Hecheng <guihc.fnst@cn.fujitsu.com>]

On Thu, 2014-10-23 at 21:36 +0800, Anand Jain wrote:
> 
>   there is no point in re-creating so many btrfs kernel's logic in user
>   space. its just unnecessary, when kernel is already doing it. use
>   some interface to get info from kernel after device is registered,
>   (not necessarily mounted). so progs can be as sleek as possible.
>   to me it started as just one more bug now we have fixed so many many.
>   It all needs one good interface for kernel which provides anything
>   anything from the kernel.
> 

Oh, the interface for kernel you described is really interesting.
But how to store the seed/sprout relationships so that we can fetch them
correctly for umounted btrfs?

-Gui 

> 
> On 10/23/14 16:52, Gui Hecheng wrote:
> > On Thu, 2014-10-23 at 16:13 +0800, Anand Jain wrote:
> >>
> >> Some of the disks on my system were missing and I was able to hit
> >> this issue.
> >>
> >>
> >> ----------------
> >> Check tree block failed, want=12582912, have=0
> >> read block failed check_tree_block
> >> Couldn't read chunk root
> >> warning devid 2 not found already
> >> Check tree block failed, want=143360, have=0
> >> read block failed check_tree_block
> >> Couldn't read chunk root
> >> warning, device 4 is missing
> >> warning, device 3 is missing
> >> warning, device 2 is missing
> >> warning, device 1 is missing
> >> ----------------
> >>
> >>
> >> Did a bisect and it leads to this following patch.
> >>
> >> ----------------
> >> commit 915902c5002485fb13d27c4b699a73fb66cc0f09
> >>
> >>       btrfs-progs: fix device missing of btrfs fi show with seed devices
> >> ----------------
> >>
> >>    Also this patch stalls ~2sec in the cmd btrfs fi show, on my system
> >>    with 48 disks.
> >>
> >> Also a simple test case hits some warnings...
> >>
> >> ----------------
> >>    mkfs.btrfs -draid1 -mraid1 /dev/sdb /dev/sdc
> >>    mount /dev/sdb /btrfs && fillfs /btrfs 100 && umount /btrfs
> >>    wipefs -a /dev/sdb
> >>    modprobe -r btrfs && modprobe btrfs
> >>    mount -o degraded /dev/sdb /btrfs
> >>    btrfs fi show
> >> Label: none  uuid: 9844cd05-1c8c-473e-a84b-bac95aab7bc9
> >>           Total devices 2 FS bytes used 1.59MiB
> >>           devid    2 size 967.87MiB used 104.75MiB path /dev/sdc
> >>           *** Some devices missing
> >>
> >> warning, device 1 is missing
> >> warning, device 1 is missing
> >> warning devid 1 not found already
> >> ----------------
> >>
> >
> > Hi Anand and Petr,
> >
> > Oh, it seems that there are btrfs with missing devs that are bringing
> > troubles to the @open_ctree_... function.
> > This should be a missing case of the patch above which should only take
> > effects when seeding devices are present.
> > I will try my best to follow this case, suggestions are welcome, Thanks!
> >
> > -Gui
> >
> >>
> >>
> >>
> >> On 10/23/14 14:57, Petr Janecek wrote:
> >>> Hello,
> >>>
> >>>>    You have mentioned two issues when balance and fi show running
> >>>>    concurrently
> >>>
> >>>     my mail was a bit chaotic, but I get the stalls even on idle system.
> >>> Today I got
> >>>
> >>> parent transid verify failed on 1559973888000 wanted 1819 found 1821
> >>> parent transid verify failed on 1559973888000 wanted 1819 found 1821
> >>> parent transid verify failed on 1559973888000 wanted 1819 found 1821
> >>> parent transid verify failed on 1559973888000 wanted 1819 found 1821
> >>> Ignoring transid failure
> >>> leaf parent key incorrect 1559973888000
> >>>
> >>> from 'btrfs fi sh' while I was just copying something, no balance running.
> >>>
> >>> [...]
> >>>> [PATCH 1/1] btrfs-progs: code optimize cmd_scan_dev() use
> >>>> btrfs_register_one_device()
> >>>> [PATCH 1/2] btrfs-progs: introduce btrfs_register_all_device()
> >>>> [PATCH 2/2] btrfs-progs: optimize btrfs_scan_lblkid() for multiple calls
> >>>>
> >>>> If you could, pls..
> >>>>    Now on 3.17 apply above 3 patches and see if you see any better
> >>>>    performance for the stalling issue.
> >>>
> >>>     no perceptible change: takes ~40 seconds both before and after
> >>> applying. Old version <1 sec.
> >>>
> >>>>    can you do same steps on 3.16 and report what you observe
> >>>
> >>>     So many rejects -- do you have older versions of these patches?
> >>>
> >>>
> >>> Thanks,
> >>>
> >>> Petr
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> >
> >
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