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From: Christoph Anton Mitterer <>
To: Johannes Thumshirn <>,
	linux-btrfs <>
Subject: Re: delayed_refs has NO entry / btrfs_update_root:136: Aborting unused transaction(No space left).
Date: Sat, 13 Apr 2019 00:46:28 +0200
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, 2019-03-20 at 10:59 +0100, Johannes Thumshirn wrote:
> First of all, have you tried a more recent kernel than the Debian
> kernels you referenced? E.g. Linus' current master or David's misc-
> next
> branch? Just so we don't try to hunt down a bug that's already fixed.

I haven't and that's a bit difficult for me unless it's packaged by the
distro (policy reasons).

Also giving out the image is a bit problematic as it's huge (8TB).

> Also if you can still reproduce the bug, please activate tracing in
> btrfs and send the trace output.

How would I do that?

In the meantime, I think I can reproduce it with fresh images so could
you try the following:

# truncate --size 1G image
# mkfs.btrfs image

# mount -o compress image /mnt
# cd /mnt

# # create some data e.g.:
# tar xaf /usr/src/linux-source-4.19.tar.xz
# cd
# umount /mnt

# losetup -r -f image
# mount -o compress /dev/loop0 /mnt

# find /mnt -type f -exec filefrag -v {} \;

And there your kernel log will explode ;-)

The culprit seems to be the device itself being read-only i.e.
losetup's -r, respectively blockdev --setro DEVICE which I've used

If you repeat the above from the losetup point, but with -r ...
everything works fine.
Haven't checked whether -o compress actually makes a difference.


  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-17  3:42 Christoph Anton Mitterer
2019-03-20  0:59 ` Christoph Anton Mitterer
2019-03-20  9:59   ` Johannes Thumshirn
2019-04-12 22:46     ` Christoph Anton Mitterer [this message]
2019-04-12 22:52       ` Christoph Anton Mitterer
2019-04-15  8:42       ` Johannes Thumshirn
2019-05-03  2:42       ` Christoph Anton Mitterer
2019-05-16  9:12 ` Christoph Anton Mitterer
2019-05-29 13:55 ` Patch "Btrfs: do not start a transaction during fiemap" Christoph Anton Mitterer

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