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From:   Richard Weinberger <richard@nod.at>
To:     linux-nfs@vger.kernel.org
Cc:     david@sigma-star.at, bfields@fieldses.org,
        luis.turcitu@appsbroker.com, david.young@appsbroker.com,
        david.oberhollenzer@sigma-star.at, trond.myklebust@hammerspace.com,
        anna.schumaker@netapp.com, steved@redhat.com,
        chris.chilvers@appsbroker.com, Richard Weinberger <richard@nod.at>
Subject: [PATCH 0/5] nfs-utils: Improving NFS re-exports 
Date:   Mon,  2 May 2022 10:50:40 +0200
Message-Id: <20220502085045.13038-1-richard@nod.at>
MIME-Version: 1.0
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This is the first non-RFC iteration of the NFS re-export
improvement series for nfs-utils.
While the kernel side[0] didn't change at all and is still small,
the userspace side saw much more changes.

The core idea is adding new export option: reeport=3D
Using reexport=3D it is possible to mark an export entry in the exports
file explicitly as NFS re-export and select a strategy how unique
identifiers should be provided.
Currently two strategies are supported, "auto-fsidnum" and
"predefined-fsidnum", both use a SQLite database as backend to keep
track of generated ids.
For a more detailed description see patch "exports: Implement new export =
option reexport=3D".
I choose SQLite because nfs-utils already uses it and using SQL ids can n=
icely
generated and maintained. It will also scale for large setups where the a=
mount
of subvolumes is high.

Beside of id generation this series also addresses the reboot problem.
If the re-exporting NFS server reboots, uncovered NFS subvolumes are not =
yet
mounted and file handles become stale.
Now mountd/exportd keeps track of uncovered subvolumes and makes sure the=
y get
uncovered while nfsd starts.

The whole set of features is currently opt-in via --enable-reexport.
I'm also not sure about the rearrangement of the reexport code,
currently it is a helper library.

A typical export entry on a re-exporting server looks like:
	/nfs *(rw,no_root_squash,no_subtree_check,crossmnt,reexport=3Dauto-fsidn=
um)
reexport=3Dauto-fsidnum will automatically assign an fsid=3D to /nfs and =
all
uncovered subvolumes.

Richard Weinberger (5):
  Implement reexport helper library
  exports: Implement new export option reexport=3D
  export: Implement logic behind reexport=3D
  export: Avoid fsid=3D conflicts
  reexport: Make state database location configurable

[0] https://git.kernel.org/pub/scm/linux/kernel/git/rw/misc.git/log/?h=3D=
nfs_reexport_clean

 configure.ac                   |  12 ++
 nfs.conf                       |   3 +
 support/Makefile.am            |   4 +
 support/export/Makefile.am     |   2 +
 support/export/cache.c         |  71 ++++++-
 support/export/export.c        |  27 ++-
 support/include/nfslib.h       |   1 +
 support/nfs/Makefile.am        |   1 +
 support/nfs/exports.c          |  68 +++++++
 support/reexport/Makefile.am   |   6 +
 support/reexport/reexport.c    | 354 +++++++++++++++++++++++++++++++++
 support/reexport/reexport.h    |  39 ++++
 systemd/Makefile.am            |   4 +
 systemd/nfs-server-generator.c |  14 +-
 systemd/nfs.conf.man           |   6 +
 utils/exportd/Makefile.am      |   8 +-
 utils/exportd/exportd.c        |   5 +
 utils/exportfs/Makefile.am     |   6 +
 utils/exportfs/exportfs.c      |  21 +-
 utils/exportfs/exports.man     |  31 +++
 utils/mount/Makefile.am        |   7 +
 utils/mountd/Makefile.am       |   6 +
 utils/mountd/mountd.c          |   1 +
 utils/mountd/svc_run.c         |   6 +
 24 files changed, 690 insertions(+), 13 deletions(-)
 create mode 100644 support/reexport/Makefile.am
 create mode 100644 support/reexport/reexport.c
 create mode 100644 support/reexport/reexport.h

--=20
2.31.1