Date: Fri, 19 Aug 2011 22:43:10 +0900 (JST) From: Hiroki Sato <hrs@FreeBSD.org> To: current@FreeBSD.org Cc: pjd@FreeBSD.org Subject: Re: fsid change of ZFS? Message-ID: <20110819.224310.740411147168584392.hrs@allbsd.org> In-Reply-To: <20110819.002046.908756241495481148.hrs@allbsd.org> References: <20110819.002046.908756241495481148.hrs@allbsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
----Security_Multipart(Fri_Aug_19_22_43_10_2011_991)-- Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hiroki Sato <hrs@freebsd.org> wrote in <20110819.002046.908756241495481148.hrs@allbsd.org>: hr> Hi, hr> hr> I have experienced "Stale NFS file handle" issue when switching hr> between oldnfs and newnfs on a CURRENT box (NFS server exporting ZFS hr> mountpoints). The cause was that fsid was changed in the following hr> conditions and not in the NFS subsystem itself, but I am wondering if hr> these are expected behavior... hr> hr> First, I tried the following configurations of NFS and ZFS, and saw hr> if fsid of the same mountpoint (a mounted ZFS dataset) changed or hr> not by using statfs(2): hr> hr> compile opts kld module fsid[0:1] kld loaded by hr> ---------------------------------------------------------------------------- hr> NFSSERVER+NFSCLIENT zfs 865798fa:8346ef02 loader hr> hr> NFSSERVER+NFSCLIENT zfs 865798fa:8346ef07 kldload(8) hr> hr> NFSSERVER+NFSCLIENT+ hr> NFSD+NFSCL zfs 865798fa:8346ef03 loader hr> hr> NFSSERVER+NFSCLIENT+ hr> NFSD+NFSCL zfs 865798fa:8346ef08 kldload(8) hr> hr> NFSSERVER+NFSCLIENT nfsd+nfscl+zfs 865798fa:8346ef08 loader hr> ---------------------------------------------------------------------------- Ah, I found why this happened: /* * The fsid is 64 bits, composed of an 8-bit fs type, which * separates our fsid from any other filesystem types, and a * 56-bit objset unique ID. The objset unique ID is unique to * all objsets open on this system, provided by unique_create(). * The 8-bit fs type must be put in the low bits of fsid[1] * because that's where other Solaris filesystems put it. */ fsid_guid = dmu_objset_fsid_guid(zfsvfs->z_os); ASSERT((fsid_guid & ~((1ULL<<56)-1)) == 0); vfsp->vfs_fsid.val[0] = fsid_guid; vfsp->vfs_fsid.val[1] = ((fsid_guid>>32) << 8) | vfsp->mnt_vfc->vfc_typenum & 0xFF; Since the vfc_typenum variable is incremented every time a new vfs is installed, loading order of modules that call vfs_register() affects ZFS's fsid. Anyway, possibility of fsid change is troublesome especially for an NFS server with a lot of clients running. Can zeroing or setting a fixed value to the lowest 8-bit of vfs_fsid.val[1] be harmful? -- Hiroki ----Security_Multipart(Fri_Aug_19_22_43_10_2011_991)-- Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEABECAAYFAk5OaG4ACgkQTyzT2CeTzy0QsQCg22UdyvrWFV2QW/VxO4oqAz7v uNIAoIxRDfUCNBcPGrCWC8pj8dma7rHy =kBne -----END PGP SIGNATURE----- ----Security_Multipart(Fri_Aug_19_22_43_10_2011_991)----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20110819.224310.740411147168584392.hrs>