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NFSD: Async COPY result needs to return a write verifier

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Currently, when NFSD handles an asynchronous COPY, it returns a
zero write verifier, relying on the subsequent CB_OFFLOAD callback
to pass the write verifier and a stable_how4 value to the client.

However, if the CB_OFFLOAD never arrives at the client (for example,
if a network partition occurs just as the server sends the
CB_OFFLOAD operation), the client will never receive this verifier.
Thus, if the client sends a follow-up COMMIT, there is no way for
the client to assess the COMMIT result.

The usual recovery for a missing CB_OFFLOAD is for the client to
send an OFFLOAD_STATUS operation, but that operation does not carry
a write verifier in its result. Neither does it carry a stable_how4
value, so the client /must/ send a COMMIT in this case -- which will
always fail because currently there's still no write verifier in the
COPY result.

Thus the server needs to return a normal write verifier in its COPY
result even if the COPY operation is to be performed asynchronously.

If the server recognizes the callback stateid in subsequent
OFFLOAD_STATUS operations, then obviously it has not restarted, and
the write verifier the client received in the COPY result is still
valid and can be used to assess a COMMIT of the copied data, if one
is needed.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2024-08-28 13:40:03 -04:00
parent 15392c8cd1
commit 9ed666eba4
1 changed files with 9 additions and 16 deletions
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25
fs/nfsd/nfs4proc.c
View File

@ -752,15 +752,6 @@ nfsd4_access(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
&access->ac_supported);
}
static void gen_boot_verifier(nfs4_verifier *verifier, struct net *net)
{
__be32 *verf = (__be32 *)verifier->data;
BUILD_BUG_ON(2*sizeof(*verf) != sizeof(verifier->data));
nfsd_copy_write_verifier(verf, net_generic(net, nfsd_net_id));
}
static __be32
nfsd4_commit(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
union nfsd4_op_u *u)
@ -1632,7 +1623,6 @@ static void nfsd4_init_copy_res(struct nfsd4_copy *copy, bool sync)
test_bit(NFSD4_COPY_F_COMMITTED, &copy->cp_flags) ?
NFS_FILE_SYNC : NFS_UNSTABLE;
nfsd4_copy_set_sync(copy, sync);
gen_boot_verifier(&copy->cp_res.wr_verifier, copy->cp_clp->net);
}
static ssize_t _nfsd_copy_file_range(struct nfsd4_copy *copy,
@ -1805,9 +1795,11 @@ static __be32
nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
union nfsd4_op_u *u)
{
struct nfsd4_copy *copy = &u->copy;
__be32 status;
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
struct nfsd4_copy *async_copy = NULL;
struct nfsd4_copy *copy = &u->copy;
struct nfsd42_write_res *result;
__be32 status;
/*
* Currently, async COPY is not reliable. Force all COPY
@ -1816,6 +1808,9 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
*/
nfsd4_copy_set_sync(copy, true);
result = &copy->cp_res;
nfsd_copy_write_verifier((__be32 *)&result->wr_verifier.data, nn);
copy->cp_clp = cstate->clp;
if (nfsd4_ssc_is_inter(copy)) {
trace_nfsd_copy_inter(copy);
@ -1840,8 +1835,6 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
memcpy(&copy->fh, &cstate->current_fh.fh_handle,
sizeof(struct knfsd_fh));
if (nfsd4_copy_is_async(copy)) {
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
status = nfserrno(-ENOMEM);
async_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
if (!async_copy)
@ -1853,8 +1846,8 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
goto out_err;
if (!nfs4_init_copy_state(nn, copy))
goto out_err;
memcpy(&copy->cp_res.cb_stateid, &copy->cp_stateid.cs_stid,
sizeof(copy->cp_res.cb_stateid));
memcpy(&result->cb_stateid, &copy->cp_stateid.cs_stid,
sizeof(result->cb_stateid));
dup_copy_fields(copy, async_copy);
async_copy->copy_task = kthread_create(nfsd4_do_async_copy,
async_copy, "%s", "copy thread");