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From: Martin Steigerwald <Martin@lichtvoll.de>
To: linux-btrfs@vger.kernel.org
Subject: Re: kernel got struck while scrubbing BTRFS with node- and leafsize 32768
Date: Sat, 16 Jun 2012 22:38:23 +0200
References: <201206162223.20392.Martin@lichtvoll.de> (sfid-20120616_222349_638324_6A19C7C9)
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Am Samstag, 16. Juni 2012 schrieb Martin Steigerwald:
> merkaba:~> date ; btrfs scrub status /mnt/amazon-daten
> Sa 16. Jun 22:06:33 CEST 2012
> scrub status for bd94ea73-6e77-4c81-b053-2401b4f52b3e
>         scrub started at Sat Jun 16 21:44:09 2012, running for 1341
> seconds total bytes scrubbed: 90.30GB with 0 errors
> merkaba:~> date ; btrfs scrub cancel /mnt/amazon-daten
> Sa 16. Jun 22:06:47 CEST 2012
> [… hangs here …]

btrfs-readahead is stuck:

merkaba:~> ps aux | egrep "(USER| D)" 
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root     11920  0.0  0.0      0     0 ?        D    21:46   0:00 [btrfs-readahead]
root     13649  0.0  0.0  10544   396 pts/0    D+   22:06   0:00 btrfs scrub cancel /mnt/amazon-daten
root     16309  0.0  0.0   9816   948 pts/1    S+   22:24   0:00 egrep (USER| D)

I created a bug report with a

kern.log including echo t > /proc/sysrq-trigger with stuck readahead

I will no be redoing the backup drive as 4K node and leaf size.

The production one I will leave at 32K for now, so I might be able to
reproduce this hang.

But first checksum error free redundancy minus the few affected files
that are not that important to me.

Thanks,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7