| Message ID | 20221207084309.8499-1-richard@nod.at (mailing list archive) |
|---|---|
| Headers | show |
| Series | NFS: NFSD: Allow crossing mounts when re-exporting | expand |
> On Dec 7, 2022, at 3:43 AM, Richard Weinberger <richard@nod.at> wrote: > > Currently when re-exporting a NFS share the NFS cross mount feature does > not work [0]. > This patch series outlines an approach to address the problem. > > Crossing mounts does not work for two reasons: > > 1. As soon the NFS client (on the re-exporting server) sees a different > filesystem id, it installs an automount. That way the other filesystem > will be mounted automatically when someone enters the directory. > But the cross mount logic of KNFS does not know about automount. > This patch series addresses the problem and teach both KNFSD > and the exportfs logic of NFS to deal with automount. > > 2. When KNFSD detects crossing of a mount point, it asks rpc.mountd to install > a new export for the target mount point. Beside of authentication rpc.mountd > also has to find a filesystem id for the new export. Is the to be exported > filesystem a NFS share, rpc.mountd cannot derive a filesystem id from it and > refuses to export. In the logs you'll see errors such as: > > mountd: Cannot export /srv/nfs/vol0, possibly unsupported filesystem or fsid= required > > To deal with that I've changed rpc.mountd to use generate and store fsids [1]. > Since the kernel side of my changes did change for a long time I decided to > try upstreaming it first. > A 3rd iteration of my rpc.mountd will happen soon. > > [0] https://marc.info/?l=linux-nfs&m=161653016627277&w=2 > [1] https://lore.kernel.org/linux-nfs/20220217131531.2890-1-richard@nod.at/ > > Changes since v1: > https://lore.kernel.org/linux-nfs/20221117191151.14262-1-richard@nod.at/ > > - Use LOOKUP_AUTOMOUNT only when NFSEXP_CROSSMOUNT is set (Jeff Layton) > > Richard Weinberger (3): > NFSD: Teach nfsd_mountpoint() auto mounts > fs: namei: Allow follow_down() to uncover auto mounts > NFS: nfs_encode_fh: Remove S_AUTOMOUNT check > > fs/namei.c | 6 +++--- > fs/nfs/export.c | 2 +- > fs/nfsd/vfs.c | 8 ++++++-- > include/linux/namei.h | 2 +- > 4 files changed, 11 insertions(+), 7 deletions(-) > > -- > 2.26.2 > This series is a bit late for inclusion in v6.2. The next opportunity will be v6.3 in a couple of months. I prefer to have a "final" version of patches by -rc5. I'm waiting for review comments on v2 of this series. -- Chuck Lever
----- Ursprüngliche Mail ----- > Von: "chuck lever" <chuck.lever@oracle.com> >> Richard Weinberger (3): >> NFSD: Teach nfsd_mountpoint() auto mounts >> fs: namei: Allow follow_down() to uncover auto mounts >> NFS: nfs_encode_fh: Remove S_AUTOMOUNT check >> >> fs/namei.c | 6 +++--- >> fs/nfs/export.c | 2 +- >> fs/nfsd/vfs.c | 8 ++++++-- >> include/linux/namei.h | 2 +- >> 4 files changed, 11 insertions(+), 7 deletions(-) >> >> -- >> 2.26.2 >> > > This series is a bit late for inclusion in v6.2. The next opportunity > will be v6.3 in a couple of months. I prefer to have a "final" version > of patches by -rc5. > > I'm waiting for review comments on v2 of this series. Ok! Do you want me to resend the series in any case by v6.2-rc5 or only if new comments arise? Thanks, //richard
> On Dec 10, 2022, at 4:52 PM, Richard Weinberger <richard@nod.at> wrote: > > ----- Ursprüngliche Mail ----- >> Von: "chuck lever" <chuck.lever@oracle.com> >>> Richard Weinberger (3): >>> NFSD: Teach nfsd_mountpoint() auto mounts >>> fs: namei: Allow follow_down() to uncover auto mounts >>> NFS: nfs_encode_fh: Remove S_AUTOMOUNT check >>> >>> fs/namei.c | 6 +++--- >>> fs/nfs/export.c | 2 +- >>> fs/nfsd/vfs.c | 8 ++++++-- >>> include/linux/namei.h | 2 +- >>> 4 files changed, 11 insertions(+), 7 deletions(-) >>> >>> -- >>> 2.26.2 >>> >> >> This series is a bit late for inclusion in v6.2. The next opportunity >> will be v6.3 in a couple of months. I prefer to have a "final" version >> of patches by -rc5. >> >> I'm waiting for review comments on v2 of this series. > > Ok! Do you want me to resend the series in any case by v6.2-rc5 or only > if new comments arise? If v2 garners no new comments, then send a reminder with a URL to this thread on lore.kernel.org. I will pull the series from there. -- Chuck Lever
On Wed, 2022-12-07 at 09:43 +0100, Richard Weinberger wrote: > Currently when re-exporting a NFS share the NFS cross mount feature does > not work [0]. > This patch series outlines an approach to address the problem. > > Crossing mounts does not work for two reasons: > > 1. As soon the NFS client (on the re-exporting server) sees a different > filesystem id, it installs an automount. That way the other filesystem > will be mounted automatically when someone enters the directory. > But the cross mount logic of KNFS does not know about automount. > This patch series addresses the problem and teach both KNFSD > and the exportfs logic of NFS to deal with automount. > > 2. When KNFSD detects crossing of a mount point, it asks rpc.mountd to install > a new export for the target mount point. Beside of authentication rpc.mountd > also has to find a filesystem id for the new export. Is the to be exported > filesystem a NFS share, rpc.mountd cannot derive a filesystem id from it and > refuses to export. In the logs you'll see errors such as: > > mountd: Cannot export /srv/nfs/vol0, possibly unsupported filesystem or fsid= required > > To deal with that I've changed rpc.mountd to use generate and store fsids [1]. > Since the kernel side of my changes did change for a long time I decided to > try upstreaming it first. > A 3rd iteration of my rpc.mountd will happen soon. > > [0] https://marc.info/?l=linux-nfs&m=161653016627277&w=2 > [1] https://lore.kernel.org/linux-nfs/20220217131531.2890-1-richard@nod.at/ > > Changes since v1: > https://lore.kernel.org/linux-nfs/20221117191151.14262-1-richard@nod.at/ > > - Use LOOKUP_AUTOMOUNT only when NFSEXP_CROSSMOUNT is set (Jeff Layton) > > Richard Weinberger (3): > NFSD: Teach nfsd_mountpoint() auto mounts > fs: namei: Allow follow_down() to uncover auto mounts > NFS: nfs_encode_fh: Remove S_AUTOMOUNT check > > fs/namei.c | 6 +++--- > fs/nfs/export.c | 2 +- > fs/nfsd/vfs.c | 8 ++++++-- > include/linux/namei.h | 2 +- > 4 files changed, 11 insertions(+), 7 deletions(-) > This set looks reasonable to me. Reviewed-by: Jeff Layton <jlayton@kernel.org>
On 13/12/22 01:06, Jeff Layton wrote: > On Wed, 2022-12-07 at 09:43 +0100, Richard Weinberger wrote: >> Currently when re-exporting a NFS share the NFS cross mount feature does >> not work [0]. >> This patch series outlines an approach to address the problem. >> >> Crossing mounts does not work for two reasons: >> >> 1. As soon the NFS client (on the re-exporting server) sees a different >> filesystem id, it installs an automount. That way the other filesystem >> will be mounted automatically when someone enters the directory. >> But the cross mount logic of KNFS does not know about automount. >> This patch series addresses the problem and teach both KNFSD >> and the exportfs logic of NFS to deal with automount. >> >> 2. When KNFSD detects crossing of a mount point, it asks rpc.mountd to install >> a new export for the target mount point. Beside of authentication rpc.mountd >> also has to find a filesystem id for the new export. Is the to be exported >> filesystem a NFS share, rpc.mountd cannot derive a filesystem id from it and >> refuses to export. In the logs you'll see errors such as: >> >> mountd: Cannot export /srv/nfs/vol0, possibly unsupported filesystem or fsid= required >> >> To deal with that I've changed rpc.mountd to use generate and store fsids [1]. >> Since the kernel side of my changes did change for a long time I decided to >> try upstreaming it first. >> A 3rd iteration of my rpc.mountd will happen soon. >> >> [0] https://marc.info/?l=linux-nfs&m=161653016627277&w=2 >> [1] https://lore.kernel.org/linux-nfs/20220217131531.2890-1-richard@nod.at/ >> >> Changes since v1: >> https://lore.kernel.org/linux-nfs/20221117191151.14262-1-richard@nod.at/ >> >> - Use LOOKUP_AUTOMOUNT only when NFSEXP_CROSSMOUNT is set (Jeff Layton) >> >> Richard Weinberger (3): >> NFSD: Teach nfsd_mountpoint() auto mounts >> fs: namei: Allow follow_down() to uncover auto mounts >> NFS: nfs_encode_fh: Remove S_AUTOMOUNT check >> >> fs/namei.c | 6 +++--- >> fs/nfs/export.c | 2 +- >> fs/nfsd/vfs.c | 8 ++++++-- >> include/linux/namei.h | 2 +- >> 4 files changed, 11 insertions(+), 7 deletions(-) >> > This set looks reasonable to me. > > Reviewed-by: Jeff Layton <jlayton@kernel.org> Right, looks ok to me too, at least from the POV of that follow_down() change. Reviewed-by: Ian Kent <raven@themaw.net> Ian