[Bug 1735046] Re: mkfs.btrfs error checking mount status of loop device backing_file
Ryan Harper
1735046 at bugs.launchpad.net
Thu Jan 11 21:14:18 UTC 2018
I tested the proposed package and it works as expected.
root at t-unsubsidized-piper:~# lsb_release -rd
Description: Ubuntu 14.04.5 LTS
Release: 14.04
root at t-unsubsidized-piper:~# uname -r
3.13.0-137-generic
First, I confirmed it still fails on 3.12-1ubuntu0.1
root at t-unsubsidized-piper:~# truncate -s 1G testloop.img
root at t-unsubsidized-piper:~# losetup /dev/loop0 testloop.img
root at t-unsubsidized-piper:~# mkfs.ext4 /dev/loop0
mke2fs 1.42.9 (4-Feb-2014)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
root at t-unsubsidized-piper:~# mount /dev/loop0 /mnt
root at t-unsubsidized-piper:~# rm testloop.img
root at t-unsubsidized-piper:~# mkfs.btrfs --force /dev/vdb
Error: error checking /dev/vdb mount status
root at t-unsubsidized-piper:~# echo $?
1
Next I added trusty-proposed and updated
root at t-unsubsidized-piper:~# apt-cache policy btrfs-tools
btrfs-tools:
Installed: 3.12-1ubuntu0.1
Candidate: 3.12-1ubuntu0.2
Version table:
3.12-1ubuntu0.2 0
500 http://nova.clouds.archive.ubuntu.com/ubuntu/ trusty-proposed/main amd64 Packages
*** 3.12-1ubuntu0.1 0
500 http://nova.clouds.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
100 /var/lib/dpkg/status
3.12-1 0
500 http://nova.clouds.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
After installing the upgrade, I repeated the mkfs.btrfs command, but
this time it succeeds
# sudo apt install btrfs-tools
sudo: unable to resolve host t-unsubsidized-piper
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
btrfs-tools
1 upgraded, 0 newly installed, 0 to remove and 7 not upgraded.
Need to get 332 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://nova.clouds.archive.ubuntu.com/ubuntu/ trusty-proposed/main btrfs-tools amd64 3.12-1ubuntu0.2 [332 kB]
Fetched 332 kB in 0s (827 kB/s)
(Reading database ... 51345 files and directories currently installed.)
Preparing to unpack .../btrfs-tools_3.12-1ubuntu0.2_amd64.deb ...
Unpacking btrfs-tools (3.12-1ubuntu0.2) over (3.12-1ubuntu0.1) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Setting up btrfs-tools (3.12-1ubuntu0.2) ...
update-initramfs: deferring update (trigger activated)
Processing triggers for initramfs-tools (0.103ubuntu4.10) ...
update-initramfs: Generating /boot/initrd.img-3.13.0-137-generic
Processing triggers for libc-bin (2.19-0ubuntu6.13) ...
root at t-unsubsidized-piper:~# mkfs.btrfs --force /dev/vdb
WARNING! - Btrfs v3.12 IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
Turning ON incompat feature 'extref': increased hardlink limit per file to 65536
fs created label (null) on /dev/vdb
nodesize 16384 leafsize 16384 sectorsize 4096 size 40.00GiB
Btrfs v3.12
root at t-unsubsidized-piper:~# echo $?
0
** Tags removed: verification-needed-trusty
** Tags added: verification-done-trusty
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https://bugs.launchpad.net/bugs/1735046
Title:
mkfs.btrfs error checking mount status of loop device backing_file
Status in btrfs-tools package in Ubuntu:
Fix Released
Status in btrfs-tools source package in Trusty:
Fix Committed
Status in btrfs-tools source package in Xenial:
Fix Released
Bug description:
SRU Template
[Impact]
* Users may be unable to successfully create a btrfs filesystem on
block devices when a loop device is mounted and the backing file
no longer exists. This typically happens in the precense of
overlayroot but may be encountered in other situations.
This affects the btrfs-tools package prior to the 3.13 release.
* Backporting the fix from the upstream repository is required to
allow Trusty MAAS/Cloud images which use overlayrootfs to create
btrfs filesystems in the presence of a loopdevice with a missing
backing file.
* All patches applied are already accepted upstream. Xenial, Artful,
and Bionic are not affected.
[Test Case]
* On a Trusty 14.04 system with a secondary disk (vdb)
- apt-get install btrfs-tools
- truncate -s 1G testloop.img
- losetup /dev/loop0 testloop.img
- mkfs.ext4 /dev/loop0
- mount /dev/loop0 /mnt
- rm testloop.img
- mkfs.btrfs --force /dev/vdb
PASS if mkfs.btrfs returns 0 and /dev/vdb has a btrfs filesystem
FAIL if mkfs.btrfs returns non-zero and /dev/vdb does not have a
btrfs filesystem. mkfs.btrfs returns the error message:
Error: error checking /dev/vdb mount status
[Regression Potential]
* mkfs.btrfs fails to detect that the target device is already mounted
and an existing btrfs filesystem is destroyed.
[Original Description]
# lsb_release -rd
Description: Ubuntu 14.04.5 LTS
Release: 14.04
# apt-cache policy btrfs-tools
btrfs-tools:
Installed: 3.12-1ubuntu0.1
Candidate: 3.12-1ubuntu0.1
Version table:
*** 3.12-1ubuntu0.1 0
500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
100 /var/lib/dpkg/status
3.12-1 0
500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
# mkfs.btrfs --force /dev/vdd succeeds
# # mkfs.btrfs --force /dev/vdd
Error: error checking /dev/vdd mount status
# strace -f mkfs.btrfs --force /dev/vdd
<snip>
stat("/dev/loop0", {st_mode=S_IFBLK|0660, st_rdev=makedev(7, 0), ...}) = 0
lstat("/dev", {st_mode=S_IFDIR|0755, st_size=4180, ...}) = 0
lstat("/dev/loop0", {st_mode=S_IFBLK|0660, st_rdev=makedev(7, 0), ...}) = 0
open("/sys/block//loop0/loop/backing_file", O_RDONLY) = 5
fstat(5, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe8bd73c000
read(5, "/root.tmp.img (deleted)\n", 4096) = 24
close(5) = 0
munmap(0x7fe8bd73c000, 4096) = 0
lstat("/dev", {st_mode=S_IFDIR|0755, st_size=4180, ...}) = 0
lstat("/dev/vdd", {st_mode=S_IFBLK|0660, st_rdev=makedev(253, 48), ...}) = 0
lstat("/root.tmp.img (deleted)", 0x7ffeaa3f0bf0) = -1 ENOENT (No such file or directory)
close(4) = 0
munmap(0x7fe8bd73d000, 4096) = 0
close(3) = 0
write(2, "Error: error checking /dev/vdd m"..., 44Error: error checking /dev/vdd mount status
) = 44
exit_group(1) = ?
+++ exited with 1 +++
It appears that mkfs.btrfs doesn't like the loop device, /dev/loop0
which has a deleted backing file.
root at ubuntu:~# cat /sys/block/loop0/loop/backing_file
/root.tmp.img (deleted)
root at ubuntu:~# ls -al /root.tmp.img
ls: cannot access /root.tmp.img: No such file or directory
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: btrfs-tools 3.12-1ubuntu0.1
ProcVersionSignature: Ubuntu 3.13.0-135.184-generic 3.13.11-ckt39
Uname: Linux 3.13.0-135-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.27
Architecture: amd64
Date: Wed Nov 29 02:58:04 2017
ProcEnviron:
TERM=vt102
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: btrfs-tools
UpgradeStatus: No upgrade log present (probably fresh install)
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