fsid change of ZFS?

[Hiroki Sato]

Hi Rick,

Rick Macklem <rmacklem at uoguelph.ca> wrote
  in <468764384.310026.1314219682612.JavaMail.root at erie.cs.uoguelph.ca>:

rm> It sounds like people have agreed that this is a reasonable solution.
rm> If hrs@ can confirm that testing shows it fixes the original problem
rm> (the ZFS file handles don't change when it's loaded at different times),
rm> I'll pass it along to re at .

 I am sorry for the delay, but I tried the patch on several boxes and
 it worked fine:

 [old (fixed array) patch]
 % lsvfs
 Filesystem                       Num  Refs Flags
 -------------------------------- --- ----- ---------------
 ufs                                2     3
 oldnfs                            15     0 network
 zfs                                7     4 jail, delegated-administration
 nfs                                6     1 network
 cd9660                             1     0 read-only
 procfs                             3     0 synthetic
 devfs                              4     1 synthetic
 msdosfs                            5     0

 [new (hash-based) patch]
 Filesystem                       Num  Refs Flags
 -------------------------------- --- ----- ---------------
 ufs                               53     3
 oldnfs                            77     0 network
 zfs                              222     4 jail, delegated-administration
 nfs                               58     0 network
 cd9660                           189     0 read-only
 procfs                             2     0 synthetic
 devfs                            113     1 synthetic
 msdosfs                           50     0

 [new patch, different loading order of kld modules]
 Filesystem                       Num  Refs Flags
 -------------------------------- --- ----- ---------------
 ufs                               53     3
 zfs                              222     4 jail, delegated-administration
 cd9660                           189     0 read-only
 procfs                             2     0 synthetic
 devfs                            113     1 synthetic
 msdosfs                           50     0
 nfs                               58     0 network

 Thanks a lot for the patch.  I think it should be committed before
 9.0R is released.

 Even for 8-STABLE this is useful but there is a problem that it will
 make an incomptibility of the fsid calculation between 8.N and
 8.(N+1).  What do you think about adding a loader tunable (something
 like vfs.fsidhash) to control this and making it disable by default?
 It would help sysadmins who will try a upgrade from 8.X to 9.X in the
 future, I think.

-- Hiroki
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