Hello Viacheslav, thanks for your review. On 14/01/2025 20:17, Viacheslav Dubeyko wrote:
Does it exist any way to reproduce the issue in stable manner? Could you please share any steps to repeat it? It will be great to have this description in the patch comment.
This issue can probably be reproduced by having a CephFS subvolumegroup be mounted to a kernel Ceph client (version 6.12.8), where the auth credentials are scoped to a specific path:
client.services:
key: REDACTED
caps: [mds] allow rw fsname=cephfs path=/volumes/
caps: [mon] allow r fsname=cephfs
caps: [osd] allow rw tag cephfs data=cephfs
Then, you simply need to trigger a lot of file permission check (either
by using the FS for long or doing LOSF I/O). This could be probably be
done by doing:
seq 1 100000 | xargs -P32 --replace touch /path/to/your/cephfs/mount/file-{} seq 1 100000 | xargs -P32 --replace cat /path/to/your/cephfs/mount/file-{}
The idea is to place yourself in a situation where the target path being matched by ceph_mds_auth_match does not contain your credential (auth) path AT ALL. This can be done when mounting a subvolumegroup, for instance:
services@00000000-0000-0000-0000-000000000000.cephfs=/volumes/containers ceph rw,noatime,name=services,secret=<hidden>,ms_mode=prefer-crc,mount_timeout=300,acl,mon_addr=[REDACTED]Since you never enter https://elixir.bootlin.com/linux/v6.13-rc3/source/fs/ceph/mds_client.c#L5697 or https://elixir.bootlin.com/linux/v6.13-rc3/source/fs/ceph/mds_client.c#L5703, you never free _tpath (whatever free_tpath's value might be).
As far as I can see, we have several kfree() calls in the logic of this method: (1) https://elixir.bootlin.com/linux/v6.13-rc3/source/fs/ceph/mds_client.c#L5697 (2) https://elixir.bootlin.com/linux/v6.13-rc3/source/fs/ceph/mds_client.c#L5703 And you are adding the third call. I believe that it will be much cleaner solution if we have only one kfree() call and goto from all other places. Could you please rework your fix?
I absolutely agree, and was thinking the same thing. I'll rework my patch to simplify this kfree path.
Thanks, Slava.
Thank you, Antoine Viallon
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