On 08/04/2021 14:09, Ha, Son Hai wrote:
Hi everyone,
We encountered an issue with KRBD mounting after mapping it to the host with read-only option.
We try to pinpoint where the problem is, but not able to do it.
See my reply down below.
The image is mounted well if we map it without the "read-only" option.
This leads to an issue that the pod in k8s cannot use the snapshotted persistent volume created by ceph-csi rbd provisioner.
Thank you for reading.
I have reported the bug here: Bug #50234: krbd failed to mount after map image with read-only option - Ceph - Ceph<https://tracker.ceph.com/issues/50234>
Context
- Using admin keyring
- Linux Kernel: 3.10.0-1160.15.2.el7.x86_64
- Linux Distribution: Red Hat Enterprise Linux Server 7.8 (Maipo)
- Ceph version: "ceph version 14.2.8 (2d095e947a02261ce61424021bb43bd3022d35cb) nautilus (stable)"
rbd image 'csi-vol-85919409-9797-11eb-80ba-720b2b57c790':
size 10 GiB in 2560 objects
order 22 (4 MiB objects)
snapshot_count: 0
id: 533a03bba388ea
block_name_prefix: rbd_data.533a03bba388ea
format: 2
features: layering
op_features:
flags:
create_timestamp: Wed Apr 7 13:51:02 2021
access_timestamp: Wed Apr 7 13:51:02 2021
modify_timestamp: Wed Apr 7 13:51:02 2021
Bug Reproduction
# Map RBD image WITH read-only option, CANNOT mount with both readonly or readwrite option
sudo rbd device map -p k8s-sharedpool csi-vol-85919409-9797-11eb-80ba-720b2b57c790 -ro
/dev/rbd0
sudo mount -v -r -t ext4 /dev/rbd0 /mnt/test1
mount: cannot mount /dev/rbd0 read-only
sudo mount -v -r -t ext4 /dev/rbd0 /mnt/test1
mount: /dev/rbd0 is write-protected, mounting read-only
mount: cannot mount /dev/rbd0 read-only
ext4 will always try to recover it's journal during mount and this means
it wants to write. That fails.
Try this with mounting:
sudo mount -t ext4 -o norecover /dev/rbd0 /mnt/test1
or
sudo mount -t ext4 -o noload /dev/rbd0 /mnt/test1
Wido
# Map RBD image WITHOUT read-only option, CAN mount with both readonly or readwrite option
sudo rbd device map -p k8s-sharedpool csi-vol-85919409-9797-11eb-80ba-720b2b57c790
/dev/rbd0
sudo mount -v -r -t ext4 /dev/rbd0 /mnt/test1
mount: /mnt/test1 does not contain SELinux labels.
You just mounted an file system that supports labels which does not
contain labels, onto an SELinux box. It is likely that confined
applications will generate AVC messages and not be allowed access to
this file system. For more details see restorecon(8) and mount(8).
mount: /dev/rbd0 mounted on /mnt/test1.
sudo mount -v -t ext4 /dev/rbd0 /mnt/test1
mount: /mnt/test1 does not contain SELinux labels.
You just mounted an file system that supports labels which does not
contain labels, onto an SELinux box. It is likely that confined
applications will generate AVC messages and not be allowed access to
this file system. For more details see restorecon(8) and mount(8).
mount: /dev/rbd0 mounted on /mnt/test1.
With my best regards,
Son Hai Ha
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