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From: "Frank Filz" <ffilzlnx@mindspring.com>
To: "'NeilBrown'" <neilb@suse.de>
Cc: "'J. Bruce Fields'" <bfields@fieldses.org>,
	"'Chuck Lever'" <chuck.lever@oracle.com>,
	<linux-nfs@vger.kernel.org>,
	"'Josef Bacik'" <josef@toxicpanda.com>
Subject: RE: [PATCH v2] BTRFS/NFSD: provide more unique inode number for btrfs export
Date: Fri, 27 Aug 2021 16:46:12 -0700	[thread overview]
Message-ID: <005801d79b9d$b8437b80$28ca7280$@mindspring.com> (raw)
In-Reply-To: <163010502766.7591.10398654528737145909@noble.neil.brown.name>

> On Sat, 28 Aug 2021, Frank Filz wrote:
> >
> > Changing the fsid for sub-volumes is Ganesha's solution (before adding
> > that, we couldn't even export the sub-volumes at all).
> 
> What does Ganesha use for the mounted-on-fileid? There doesn't seem to be an
> "obvious" answer so I wonder what was chosen.

We only make mounted_on_fileid different from fileid on our export boundaries, and even then, it's not a terribly correct thing for FSAL_VFS (our module for interfacing with kernel filesystems) since user space to my knowledge has no way to get any information on an inode that serves as a mount point.

What clients actually do anything with mounted_on_fileid, and what sorts of things do they do with it? I know the AIX client was interested in it (from having worked on security negotiation back in 2006), but I have never been able to test Ganesha with an AIX client. For normal Linux client operations, what Ganesha does seems to work OK.

> >
> > Mangling the fileid is definitely the best solution if there will be lots of sub-
> volumes. For a few sub-volumes changing fsid does create additional mount
> points on the client with some issues, but does guarantee there will be no fileid
> collision.
> >
> > My gut feel is your solution is the best one and Ganesha may need to switch to
> that solution.
> 
> Thanks for the encouragement.  Changing the fsid does seem easier is many
> ways, but I don't really like the consequences or implications.

Yea, there really isn't a good solution here.

Probably really client applications need to do something different to detect infinite loops and not care so much about unique fileids.

Frank


  reply	other threads:[~2021-08-27 23:46 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26  4:28 [PATCH] NFSD: drop support for ancient file-handles NeilBrown
2021-08-26  6:03 ` [PATCH v2] BTRFS/NFSD: provide more unique inode number for btrfs export NeilBrown
2021-08-26 20:19   ` J.  Bruce Fields
2021-08-26 22:10     ` NeilBrown
2021-08-27 14:53       ` Frank Filz
2021-08-27 22:57         ` NeilBrown
2021-08-27 23:46           ` Frank Filz [this message]
2021-08-27 23:55             ` NeilBrown
2021-08-28  2:21               ` Frank Filz
2021-08-27 18:32       ` J.  Bruce Fields
2021-08-27 23:01         ` NeilBrown
2021-08-27 16:20   ` Christoph Hellwig
2021-08-27 23:05     ` NeilBrown
2021-08-28  7:09       ` Christoph Hellwig
2021-08-31  4:59         ` NeilBrown
2021-09-01  7:20           ` Christoph Hellwig
2021-09-01 15:22             ` J. Bruce Fields
2021-09-02  4:14               ` NeilBrown
2021-09-05 16:07                 ` J. Bruce Fields
2021-09-06  1:29                   ` NeilBrown
2021-09-11 14:12                     ` Amir Goldstein
2021-09-13  0:43                       ` NeilBrown
2021-09-13 10:04                         ` Amir Goldstein
2021-09-13 22:59                           ` NeilBrown
2021-09-14  5:45                             ` Amir Goldstein
2021-09-20 22:09                               ` NeilBrown
2021-09-02  7:11               ` Christoph Hellwig
2021-09-02  4:06             ` NeilBrown
2021-09-02  7:16               ` Christoph Hellwig
2021-09-02  7:53                 ` Miklos Szeredi
2021-09-02 14:16                   ` Frank Filz
2021-09-02 23:02                     ` NeilBrown
2021-08-26 14:10 ` [PATCH] NFSD: drop support for ancient file-handles Chuck Lever III
2021-08-26 21:38   ` NeilBrown
2021-08-26 14:51 ` J.  Bruce Fields
2021-08-26 21:41   ` NeilBrown
2021-08-27 15:15 ` Christoph Hellwig
2021-08-27 23:24   ` NeilBrown
2021-08-31  4:41   ` [PATCH 1/2 v2] NFSD: drop support for ancient filehandles NeilBrown
2021-08-31  4:42     ` [PATCH 2/2] NFSD: simplify struct nfsfh NeilBrown
2021-09-01  7:44       ` Christoph Hellwig
2021-09-01  7:44     ` [PATCH 1/2 v2] NFSD: drop support for ancient filehandles Christoph Hellwig
2021-09-01 14:21       ` Chuck Lever III
2021-09-02  1:14         ` [PATCH 1/3 v3] NFSD: move filehandle format declarations out of "uapi" NeilBrown
2021-09-02  1:15           ` [PATCH 2/3 v3] NFSD: drop support for ancient filehandles NeilBrown
2021-09-02  1:16             ` [PATCH 3/3 v3] NFSD: simplify struct nfsfh NeilBrown
2021-09-02  7:22             ` [PATCH 2/3 v3] NFSD: drop support for ancient filehandles Christoph Hellwig
2021-09-02  7:21           ` [PATCH 1/3 v3] NFSD: move filehandle format declarations out of "uapi" Christoph Hellwig
2021-09-23 21:21           ` Bruce Fields
2021-09-25  4:21             ` NeilBrown
  -- strict thread matches above, loose matches on Subject: below --
2021-07-27 22:37 [PATCH/RFC 00/11] expose btrfs subvols in mount table correctly NeilBrown
2021-08-13  1:45 ` [PATCH] VFS/BTRFS/NFSD: provide more unique inode number for btrfs export NeilBrown
2021-08-15  7:39   ` Goffredo Baroncelli
2021-08-15 19:35     ` Roman Mamedov
2021-08-15 22:17       ` NeilBrown
2021-08-23  4:05         ` [PATCH v2] BTRFS/NFSD: " NeilBrown

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