Date:   Tue, 8 Aug 2023 08:45:05 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
Cc:     brauner@...nel.org, stgraber@...ntu.com,
        linux-fsdevel@...r.kernel.org, Ilya Dryomov <idryomov@...il.com>,
        Jeff Layton <jlayton@...nel.org>, ceph-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 00/12] ceph: support idmapped mounts

LGTM.

Reviewed-by: Xiubo Li <xiubli@...hat.com>

I will queue this to the 'testing' branch and then we will run ceph qa 
tests.

Thanks Alex.

- Xiubo

On 8/7/23 21:26, Alexander Mikhalitsyn wrote:
> Dear friends,
>
> This patchset was originally developed by Christian Brauner but I'll continue
> to push it forward. Christian allowed me to do that :)
>
> This feature is already actively used/tested with LXD/LXC project.
>
> Git tree (based on https://github.com/ceph/ceph-client.git testing):
> v10: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v10
> current: https://github.com/mihalicyn/linux/tree/fs.idmapped.ceph
>
> In the version 3 I've changed only two commits:
> - fs: export mnt_idmap_get/mnt_idmap_put
> - ceph: allow idmapped setattr inode op
> and added a new one:
> - ceph: pass idmap to __ceph_setattr
>
> In the version 4 I've reworked the ("ceph: stash idmapping in mdsc request")
> commit. Now we take idmap refcounter just in place where req->r_mnt_idmap
> is filled. It's more safer approach and prevents possible refcounter underflow
> on error paths where __register_request wasn't called but ceph_mdsc_release_request is
> called.
>
> Changelog for version 5:
> - a few commits were squashed into one (as suggested by Xiubo Li)
> - started passing an idmapping everywhere (if possible), so a caller
> UID/GID-s will be mapped almost everywhere (as suggested by Xiubo Li)
>
> Changelog for version 6:
> - rebased on top of testing branch
> - passed an idmapping in a few places (readdir, ceph_netfs_issue_op_inline)
>
> Changelog for version 7:
> - rebased on top of testing branch
> - this thing now requires a new cephfs protocol extension CEPHFS_FEATURE_HAS_OWNER_UIDGID
> https://github.com/ceph/ceph/pull/52575
>
> Changelog for version 8:
> - rebased on top of testing branch
> - added enable_unsafe_idmap module parameter to make idmapped mounts
> work with old MDS server versions
> - properly handled case when old MDS used with new kernel client
>
> Changelog for version 9:
> - added "struct_len" field in struct ceph_mds_request_head as requested by Xiubo Li
>
> Changelog for version 10:
> - fill struct_len field properly (use cpu_to_le32)
> - add extra checks IS_CEPH_MDS_OP_NEWINODE(..) as requested by Xiubo to match
>    userspace client behavior
> - do not set req->r_mnt_idmap for MKSNAP operation
> - atomic_open: set req->r_mnt_idmap only for CEPH_MDS_OP_CREATE as userspace client does
>
> I can confirm that this version passes xfstests and
> tested with old MDS (without CEPHFS_FEATURE_HAS_OWNER_UIDGID)
> and with recent MDS version.
>
> Links to previous versions:
> v1: https://lore.kernel.org/all/20220104140414.155198-1-brauner@kernel.org/
> v2: https://lore.kernel.org/lkml/20230524153316.476973-1-aleksandr.mikhalitsyn@canonical.com/
> tree: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v2
> v3: https://lore.kernel.org/lkml/20230607152038.469739-1-aleksandr.mikhalitsyn@canonical.com/#t
> v4: https://lore.kernel.org/lkml/20230607180958.645115-1-aleksandr.mikhalitsyn@canonical.com/#t
> tree: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v4
> v5: https://lore.kernel.org/lkml/20230608154256.562906-1-aleksandr.mikhalitsyn@canonical.com/#t
> tree: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v5
> v6: https://lore.kernel.org/lkml/20230609093125.252186-1-aleksandr.mikhalitsyn@canonical.com/
> tree: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v6
> v7: https://lore.kernel.org/all/20230726141026.307690-1-aleksandr.mikhalitsyn@canonical.com/
> tree: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v7
> v8: https://lore.kernel.org/all/20230803135955.230449-1-aleksandr.mikhalitsyn@canonical.com/
> tree: -
> v9: https://lore.kernel.org/all/20230804084858.126104-1-aleksandr.mikhalitsyn@canonical.com/
> tree: https://github.com/mihalicyn/linux/commits/fs.idmapped.ceph.v9
>
> Kind regards,
> Alex
>
> Original description from Christian:
> ========================================================================
> This patch series enables cephfs to support idmapped mounts, i.e. the
> ability to alter ownership information on a per-mount basis.
>
> Container managers such as LXD support sharaing data via cephfs between
> the host and unprivileged containers and between unprivileged containers.
> They may all use different idmappings. Idmapped mounts can be used to
> create mounts with the idmapping used for the container (or a different
> one specific to the use-case).
>
> There are in fact more use-cases such as remapping ownership for
> mountpoints on the host itself to grant or restrict access to different
> users or to make it possible to enforce that programs running as root
> will write with a non-zero {g,u}id to disk.
>
> The patch series is simple overall and few changes are needed to cephfs.
> There is one cephfs specific issue that I would like to discuss and
> solve which I explain in detail in:
>
> [PATCH 02/12] ceph: handle idmapped mounts in create_request_message()
>
> It has to do with how to handle mds serves which have id-based access
> restrictions configured. I would ask you to please take a look at the
> explanation in the aforementioned patch.
>
> The patch series passes the vfs and idmapped mount testsuite as part of
> xfstests. To run it you will need a config like:
>
> [ceph]
> export FSTYP=ceph
> export TEST_DIR=/mnt/test
> export TEST_DEV=10.103.182.10:6789:/
> export TEST_FS_MOUNT_OPTS="-o name=admin,secret=$password
>
> and then simply call
>
> sudo ./check -g idmapped
>
> ========================================================================
>
> Alexander Mikhalitsyn (3):
>    fs: export mnt_idmap_get/mnt_idmap_put
>    ceph: add enable_unsafe_idmap module parameter
>    ceph: pass idmap to __ceph_setattr
>
> Christian Brauner (9):
>    ceph: stash idmapping in mdsc request
>    ceph: handle idmapped mounts in create_request_message()
>    ceph: pass an idmapping to mknod/symlink/mkdir
>    ceph: allow idmapped getattr inode op
>    ceph: allow idmapped permission inode op
>    ceph: allow idmapped setattr inode op
>    ceph/acl: allow idmapped set_acl inode op
>    ceph/file: allow idmapped atomic_open inode op
>    ceph: allow idmapped mounts
>
>   fs/ceph/acl.c                 |  6 +--
>   fs/ceph/crypto.c              |  2 +-
>   fs/ceph/dir.c                 |  4 ++
>   fs/ceph/file.c                | 11 ++++-
>   fs/ceph/inode.c               | 29 +++++++------
>   fs/ceph/mds_client.c          | 78 ++++++++++++++++++++++++++++++++---
>   fs/ceph/mds_client.h          |  8 +++-
>   fs/ceph/super.c               |  7 +++-
>   fs/ceph/super.h               |  3 +-
>   fs/mnt_idmapping.c            |  2 +
>   include/linux/ceph/ceph_fs.h  | 10 ++++-
>   include/linux/mnt_idmapping.h |  3 ++
>   12 files changed, 136 insertions(+), 27 deletions(-)
>

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