NFSv4.1: Use seqid returned by EXCHANGE_ID after state migration
authorChuck Lever <chuck.lever@oracle.com>
Thu, 8 Jun 2017 15:52:52 +0000 (11:52 -0400)
committerAnna Schumaker <Anna.Schumaker@Netapp.com>
Thu, 13 Jul 2017 20:00:12 +0000 (16:00 -0400)
commit838edb94977b96f191800d7ce39b2505419aac4a
tree9abfbd6316c599430f91398bb681390f46afc986
parent8dcbec6d20eb881ba368d0aebc3a8a678aebb1da
NFSv4.1: Use seqid returned by EXCHANGE_ID after state migration

Transparent State Migration copies a client's lease state from the
server where a filesystem used to reside to the server where it now
resides. When an NFSv4.1 client first contacts that destination
server, it uses EXCHANGE_ID to detect trunking relationships.

The lease that was copied there is returned to that client, but the
destination server sets EXCHGID4_FLAG_CONFIRMED_R when replying to
the client. This is because the lease was confirmed on the source
server (before it was copied).

When CONFIRMED_R is set, the client throws away the sequence ID
returned by the server. During a Transparent State Migration, however
there's no other way for the client to know what sequence ID to use
with a lease that's been migrated.

Therefore, the client must save and use the contrived slot sequence
value returned by the destination server even when CONFIRMED_R is
set.

Note that some servers always return a seqid of 1 after a migration.

Reported-by: Xuan Qi <xuan.qi@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Xuan Qi <xuan.qi@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
fs/nfs/nfs4proc.c