Re: [RFC PATCH v3 0/3] ceph: kernel client cephfs quota support

[Luis Henriques <lhenriques@suse.com>]

"Yan, Zheng" <ukernel@gmail.com> writes:

> On Wed, Dec 20, 2017 at 11:18 PM, Luis Henriques <lhenriques@suse.com> wrote:
>> A cephfs-specific quota implementation has been available in the
>> user-space fuse client for a while.  This quota implementation allows an
>> administrator to restrict the number of bytes and/or the number of files
>> in a filesystem subtree.  This quota implementation, however, is
>> supported at the client-level only, which means that cooperation is
>> required between different clients accessing the system.
>>
>> This obviously assumes that all clients are trusted entities and will
>> respect the quotas, preventing users from exceeding the quota limits.
>> Since the kernel client doesn't support quotas, it has not been possible
>> to use it in a cluster where quotas are a requirement.
>>
>> This patchset is an RFC that adds kernel client support for cephfs
>> quotas as it is currently implemented in the ceph fuse client.  Note
>> however that this patchset is not yet feature complete, as it only
>> implements the max_files quota (max_bytes is still missing).
>>
>> ** Changes since v2 **
>>
>> Rework after review from Yan, Zheng:
>>
>> - Dropped patch 0001 ("ceph: add seqlock for snaprealm hierarchy change
>>   detection") and use mdsc->snap_rwsem for walking the snaprealm
>>   hierarchy instead of adding a seqlock.  This means that patches 0003
>>   and 0004 needed to be reworked.
>>
>> - Added a NULL check in ceph_handle_quota() after the inode lookup with
>>   ceph_find_inode().
>>
>> ** Changes since v1 **
>>
>> Instead of trying to do a reverse path walk to find the "quota realm"
>> for a given directory, this patchset is now using snaprealms.  Thus, for
>> testing it, a modified MDS is required:
>>
>>   https://github.com/ukernel/ceph/tree/wip-cephfs-quota-realm
>>
>> This modified MDS creates a snaprealm when a quota is set in a
>> directory.  This means that a client needs only to walk up the snaprealm
>> hierarchy to find a directory that has quotas instead of doing the full
>> reverse path walking.
>>
>> Note however that this requires an extra patch that adds a seqlock (1st
>> patch in series) to detect changes in the snaprealm hierarchy.
>>
>> Luis Henriques (3):
>>   ceph: quota: add initial infrastructure to support cephfs quotas
>>   ceph: quotas: support for ceph.quota.max_files
>>   ceph: quota: don't allow cross-quota renames
>>
>>  fs/ceph/Makefile                   |   2 +-
>>  fs/ceph/dir.c                      |  16 ++++
>>  fs/ceph/file.c                     |   4 +-
>>  fs/ceph/inode.c                    |   6 ++
>>  fs/ceph/mds_client.c               |  23 +++++
>>  fs/ceph/mds_client.h               |   2 +
>>  fs/ceph/quota.c                    | 190 +++++++++++++++++++++++++++++++++++++
>>  fs/ceph/super.h                    |  10 ++
>>  fs/ceph/xattr.c                    |  44 +++++++++
>>  include/linux/ceph/ceph_features.h |   3 +-
>>  include/linux/ceph/ceph_fs.h       |  17 ++++
>>  11 files changed, 314 insertions(+), 3 deletions(-)
>>  create mode 100644 fs/ceph/quota.c
>>
>
> a few minor comments, otherwise this series looks good.

Thanks a lot for your review, I'll incorporate all those changes for the
next version (which hopefully will include already the max_bytes
implementation).

Cheers,
-- 
Luis


>
> Regards
> Yan, Zheng
>
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