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Message-ID: <8b22fc1e-595a-b729-dd21-2714f22a28a7@redhat.com>
Date:   Thu, 8 Jun 2023 11:00:59 +0800
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Subject: Re: [PATCH v4 00/14] ceph: support idmapped mounts
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To:     Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Cc:     brauner@kernel.org, stgraber@ubuntu.com,
        linux-fsdevel@vger.kernel.org, Ilya Dryomov <idryomov@gmail.com>,
        Jeff Layton <jlayton@kernel.org>, ceph-devel@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230607180958.645115-1-aleksandr.mikhalitsyn@canonical.com>
From:   Xiubo Li <xiubli@redhat.com>
In-Reply-To: <20230607180958.645115-1-aleksandr.mikhalitsyn@canonical.com>
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Hi Alexander,

As I mentioned in V2 thread 
https://www.spinics.net/lists/kernel/msg4810994.html, we should use the 
'idmap' for all the requests below, because MDS will do the 
'check_access()' for all the requests by using the caller uid/gid, 
please see 
https://github.com/ceph/ceph/blob/main/src/mds/Server.cc#L3294-L3310.


Cscope tag: ceph_mdsc_do_request
    #   line  filename / context / line
    1    321  fs/ceph/addr.c <<ceph_netfs_issue_op_inline>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
    2    443  fs/ceph/dir.c <<ceph_readdir>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
    3    838  fs/ceph/dir.c <<ceph_lookup>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
    4    933  fs/ceph/dir.c <<ceph_mknod>>
              err = ceph_mdsc_do_request(mdsc, dir, req);
    5   1045  fs/ceph/dir.c <<ceph_symlink>>
              err = ceph_mdsc_do_request(mdsc, dir, req);
    6   1120  fs/ceph/dir.c <<ceph_mkdir>>
              err = ceph_mdsc_do_request(mdsc, dir, req);
    7   1180  fs/ceph/dir.c <<ceph_link>>
              err = ceph_mdsc_do_request(mdsc, dir, req);
    8   1365  fs/ceph/dir.c <<ceph_unlink>>
              err = ceph_mdsc_do_request(mdsc, dir, req);
    9   1431  fs/ceph/dir.c <<ceph_rename>>
              err = ceph_mdsc_do_request(mdsc, old_dir, req);
   10   1927  fs/ceph/dir.c <<ceph_d_revalidate>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   11    154  fs/ceph/export.c <<__lookup_inode>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   12    262  fs/ceph/export.c <<__snapfh_to_dentry>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   13    347  fs/ceph/export.c <<__get_parent>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   14    490  fs/ceph/export.c <<__get_snap_name>>
              err = ceph_mdsc_do_request(fsc->mdsc, NULL, req);
   15    561  fs/ceph/export.c <<ceph_get_name>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   16    339  fs/ceph/file.c <<ceph_renew_caps>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   17    434  fs/ceph/file.c <<ceph_open>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   18    855  fs/ceph/file.c <<ceph_atomic_open>>
              err = ceph_mdsc_do_request(mdsc, (flags & O_CREAT) ? dir : 
NULL, req);
   19   2715  fs/ceph/inode.c <<__ceph_setattr>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   20   2839  fs/ceph/inode.c <<__ceph_do_getattr>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   21   2883  fs/ceph/inode.c <<ceph_do_getvxattr>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   22    126  fs/ceph/ioctl.c <<ceph_ioctl_set_layout>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   23    171  fs/ceph/ioctl.c <<ceph_ioctl_set_layout_policy>>
              err = ceph_mdsc_do_request(mdsc, inode, req);
   24    216  fs/ceph/locks.c <<ceph_lock_wait_for_completion>>
              err = ceph_mdsc_do_request(mdsc, inode, intr_req);
   25   1091  fs/ceph/super.c <<open_root_dentry>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);
   26   1151  fs/ceph/xattr.c <<ceph_sync_setxattr>>
              err = ceph_mdsc_do_request(mdsc, NULL, req);


And also could you squash the similar commit into one ?


Thanks

- Xiubo


On 6/8/23 02:09, 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 master):
> 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.
>
> I can confirm that this version passes xfstests.
>
> 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/
> v3: https://lore.kernel.org/lkml/20230607152038.469739-1-aleksandr.mikhalitsyn@canonical.com/#t
>
> 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 (2):
>    fs: export mnt_idmap_get/mnt_idmap_put
>    ceph: pass idmap to __ceph_setattr
>
> Christian Brauner (12):
>    ceph: stash idmapping in mdsc request
>    ceph: handle idmapped mounts in create_request_message()
>    ceph: allow idmapped mknod inode op
>    ceph: allow idmapped symlink inode op
>    ceph: allow idmapped mkdir inode op
>    ceph: allow idmapped rename inode op
>    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/dir.c                 |  4 ++++
>   fs/ceph/file.c                | 10 ++++++++--
>   fs/ceph/inode.c               | 29 +++++++++++++++++------------
>   fs/ceph/mds_client.c          | 27 +++++++++++++++++++++++----
>   fs/ceph/mds_client.h          |  1 +
>   fs/ceph/super.c               |  2 +-
>   fs/ceph/super.h               |  3 ++-
>   fs/mnt_idmapping.c            |  2 ++
>   include/linux/mnt_idmapping.h |  3 +++
>   10 files changed, 64 insertions(+), 23 deletions(-)
>