On Mon, 2012-04-23 at 16:54 -0400, Chuck Lever wrote:
> A SETCLIENTID boot verifier is nothing more than a boot timestamp.
> An NFSv4 server is obligated to wipe all NFSv4 state for an NFS client
> when the client presents an updated SETCLIENTID boot verifier. This
> is how servers detect client reboots.
>
> nfs4_reset_all_state() forces a boot verifier refresh to cause a
> server to wipe state as part of recovering from a server reporting
> that it has revoked some or all of a client's NFSv4 state. This wipes
> the slate for full state recovery.
>
> Soon we want to get rid of the per-nfs_client cl_boot_time field,
> however. Without cl_boot_time, the NFS client will need to find a
> different way to force the server to purge the client's NFSv4 state.
>
> Because these verifiers are opaque (ie, the server doesn't know or
> care that they are timestamps), we can do this by using the same
> trick we use now, but then afterwards establish a fresh client ID
> using the old boot verifier again.
>
> Hopefully there are no extra paranoid server implementations that keep
> track of the client's boot verifiers and prevent clients from reusing
> a previous one.
>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
>
> fs/nfs/nfs4_fs.h | 1 +
> fs/nfs/nfs4proc.c | 9 +++++++--
> fs/nfs/nfs4state.c | 7 ++++++-
> 3 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
> index d8c2d39..2953f2c 100644
> --- a/fs/nfs/nfs4_fs.h
> +++ b/fs/nfs/nfs4_fs.h
> @@ -24,6 +24,7 @@ enum nfs4_client_state {
> NFS4CLNT_RECALL_SLOT,
> NFS4CLNT_LEASE_CONFIRM,
> NFS4CLNT_SERVER_SCOPE_MISMATCH,
> + NFS4CLNT_PURGE_STATE,
> };
>
> enum nfs4_session_state {
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 84a26d9..b19cf81 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -3878,8 +3878,13 @@ static void nfs4_construct_boot_verifier(struct nfs_client *clp,
> {
> __be32 verf[2];
>
> - verf[0] = (__be32)clp->cl_boot_time.tv_sec;
> - verf[1] = (__be32)clp->cl_boot_time.tv_nsec;
> + if (test_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state)) {
> + verf[0] = (__be32)CURRENT_TIME.tv_sec;
> + verf[1] = (__be32)CURRENT_TIME.tv_nsec;
> + } else {
> + verf[0] = (__be32)clp->cl_boot_time.tv_sec;
> + verf[1] = (__be32)clp->cl_boot_time.tv_nsec;
> + }
> memcpy(bootverf->data, verf, sizeof(bootverf->data));
> }
>
> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> index cbef366..7f56502 100644
> --- a/fs/nfs/nfs4state.c
> +++ b/fs/nfs/nfs4state.c
> @@ -1612,7 +1612,7 @@ void nfs41_handle_recall_slot(struct nfs_client *clp)
> static void nfs4_reset_all_state(struct nfs_client *clp)
> {
> if (test_and_set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0) {
> - clp->cl_boot_time = CURRENT_TIME;
> + set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
> nfs4_state_start_reclaim_nograce(clp);
> nfs4_schedule_state_manager(clp);
> }
> @@ -1759,6 +1759,11 @@ static void nfs4_state_manager(struct nfs_client *clp)
>
> /* Ensure exclusive access to NFSv4 state */
> do {
> + if (test_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state)) {
> + nfs4_reclaim_lease(clp);
> + clear_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
This needs to set NFS4CLNT_LEASE_EXPIRED, so that we do a second
SETCLIENTID after the state has been cleared. Otherwise we end up with a
lease with the wrong verifier.
> + }
> +
> if (test_and_clear_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state)) {
> /* We're going to have to re-establish a clientid */
> status = nfs4_reclaim_lease(clp);
>
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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