Re: [PATCH v4 05/10] NFSD first draft of async copy

["J. Bruce Fields" <bfields@redhat.com>]

On Thu, Sep 28, 2017 at 01:29:40PM -0400, Olga Kornievskaia wrote:
> Asynchronous copies are handled by a single threaded workqueue.
> If we get asynchronous request, make sure to copy the needed
> arguments/state from the stack before starting the copy.

I'm worried by those copies--I suspect you want to be taking actual
references (so, bumping reference counts) to the clp and the
filehandles, not just copying pointers.

--b.

> Then
> queue work and reply back to the client indicating copy is
> asynchronous.
> 
> nfsd_copy_file_range() will copy in 4MBchunk so do a loop over
> the total number of bytes need to copy. In case a failure
> happens in the middle, we can return an error as well as how
> much we copied so far. Once done creating a workitem for the
> callback workqueue and send CB_OFFLOAD with the results.
> 
> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> ---
>  fs/nfsd/nfs4proc.c  | 164 ++++++++++++++++++++++++++++++++++++++++++++++------
>  fs/nfsd/nfs4state.c |   9 ++-
>  fs/nfsd/state.h     |   2 +
>  fs/nfsd/xdr4.h      |   7 +++
>  4 files changed, 162 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 11ade90..de21b1a 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -76,6 +76,21 @@
>  { }
>  #endif
>  
> +static struct workqueue_struct *copy_wq;
> +
> +int nfsd4_create_copy_queue(void)
> +{
> +	copy_wq = create_singlethread_workqueue("nfsd4_copy");
> +	if (!copy_wq)
> +		return -ENOMEM;
> +	return 0;
> +}
> +
> +void nfsd4_destroy_copy_queue(void)
> +{
> +	destroy_workqueue(copy_wq);
> +}
> +
>  #define NFSDDBG_FACILITY		NFSDDBG_PROC
>  
>  static u32 nfsd_attrmask[] = {
> @@ -1085,37 +1100,148 @@ static int fill_in_write_vector(struct kvec *vec, struct nfsd4_write *write)
>  out:
>  	return status;
>  }
> +static void nfsd4_cb_offload_release(struct nfsd4_callback *cb)
> +{
> +	struct nfsd4_copy *copy = container_of(cb, struct nfsd4_copy, cp_cb);
> +
> +	kfree(copy);
> +}
> +
> +static int nfsd4_cb_offload_done(struct nfsd4_callback *cb,
> +				 struct rpc_task *task)
> +{
> +	return 1;
> +}
> +
> +static const struct nfsd4_callback_ops nfsd4_cb_offload_ops = {
> +	.release = nfsd4_cb_offload_release,
> +	.done = nfsd4_cb_offload_done
> +};
> +
> +static int nfsd4_init_copy_res(struct nfsd4_copy *copy, bool sync)
> +{
> +	memcpy(&copy->cp_res.cb_stateid, &copy->cp_dst_stateid,
> +		sizeof(copy->cp_dst_stateid));
> +	copy->cp_res.wr_stable_how = NFS_UNSTABLE;
> +	copy->cp_consecutive = 1;
> +	copy->cp_synchronous = sync;
> +	gen_boot_verifier(&copy->cp_res.wr_verifier, copy->net);
> +
> +	return nfs_ok;
> +}
> +
> +static int _nfsd_copy_file_range(struct nfsd4_copy *copy)
> +{
> +	ssize_t bytes_copied = 0;
> +	size_t bytes_total = copy->cp_count;
> +	size_t bytes_to_copy;
> +	u64 src_pos = copy->cp_src_pos;
> +	u64 dst_pos = copy->cp_dst_pos;
> +
> +	do {
> +		bytes_to_copy = min_t(u64, bytes_total, MAX_RW_COUNT);
> +		bytes_copied = nfsd_copy_file_range(copy->fh_src, src_pos,
> +					copy->fh_dst, dst_pos, bytes_to_copy);
> +		if (bytes_copied <= 0)
> +			break;
> +		bytes_total -= bytes_copied;
> +		copy->cp_res.wr_bytes_written += bytes_copied;
> +		src_pos += bytes_copied;
> +		dst_pos += bytes_copied;
> +	} while (bytes_total > 0 && !copy->cp_synchronous);
> +	return bytes_copied;
> +}
> +
> +static int nfsd4_do_copy(struct nfsd4_copy *copy, bool sync)
> +{
> +	__be32 status;
> +	ssize_t bytes;
> +
> +	bytes = _nfsd_copy_file_range(copy);
> +	if (bytes < 0)
> +		status = nfserrno(bytes);
> +	else
> +		status = nfsd4_init_copy_res(copy, sync);
> +
> +	fput(copy->fh_src);
> +	fput(copy->fh_dst);
> +	return status;
> +}
> +
> +static void dup_copy_fields(struct nfsd4_copy *src, struct nfsd4_copy *dst)
> +{
> +	memcpy(&dst->cp_src_stateid, &src->cp_src_stateid, sizeof(stateid_t));
> +	memcpy(&dst->cp_dst_stateid, &src->cp_dst_stateid, sizeof(stateid_t));
> +	dst->cp_src_pos = src->cp_src_pos;
> +	dst->cp_dst_pos = src->cp_dst_pos;
> +	dst->cp_count = src->cp_count;
> +	dst->cp_consecutive = src->cp_consecutive;
> +	dst->cp_synchronous = src->cp_synchronous;
> +	memcpy(&dst->cp_res, &src->cp_res, sizeof(src->cp_res));
> +	/* skipping nfsd4_callback */
> +	memcpy(&dst->fh, &src->fh, sizeof(src->fh));
> +	dst->fh = src->fh;
> +	dst->cp_clp = src->cp_clp;
> +	dst->fh_src = src->fh_src;
> +	dst->fh_dst = src->fh_dst;
> +	dst->net = src->net;
> +}
> +
> +static void nfsd4_do_async_copy(struct work_struct *work)
> +{
> +	struct nfsd4_copy *copy =
> +		container_of(work, struct nfsd4_copy, cp_work);
> +	struct nfsd4_copy *cb_copy;
> +
> +	copy->nfserr = nfsd4_do_copy(copy, 0);
> +	cb_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
> +	if (!cb_copy)
> +		goto out;
> +	memcpy(&cb_copy->cp_res, &copy->cp_res, sizeof(copy->cp_res));
> +	cb_copy->cp_clp = copy->cp_clp;
> +	cb_copy->nfserr = copy->nfserr;
> +	memcpy(&cb_copy->fh, &copy->fh, sizeof(copy->fh));
> +	nfsd4_init_cb(&cb_copy->cp_cb, cb_copy->cp_clp,
> +			&nfsd4_cb_offload_ops, NFSPROC4_CLNT_CB_OFFLOAD);
> +	nfsd4_run_cb(&cb_copy->cp_cb);
> +out:
> +	kfree(copy);
> +}
>  
>  static __be32
>  nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  		union nfsd4_op_u *u)
>  {
>  	struct nfsd4_copy *copy = &u->copy;
> -	struct file *src, *dst;
>  	__be32 status;
> -	ssize_t bytes;
>  
> -	status = nfsd4_verify_copy(rqstp, cstate, &copy->cp_src_stateid, &src,
> -				   &copy->cp_dst_stateid, &dst);
> +	status = nfsd4_verify_copy(rqstp, cstate, &copy->cp_src_stateid,
> +				   &copy->fh_src, &copy->cp_dst_stateid,
> +				   &copy->fh_dst);
>  	if (status)
>  		goto out;
>  
> -	bytes = nfsd_copy_file_range(src, copy->cp_src_pos,
> -			dst, copy->cp_dst_pos, copy->cp_count);
> -
> -	if (bytes < 0)
> -		status = nfserrno(bytes);
> -	else {
> -		copy->cp_res.wr_bytes_written = bytes;
> -		copy->cp_res.wr_stable_how = NFS_UNSTABLE;
> -		copy->cp_consecutive = 1;
> -		copy->cp_synchronous = 1;
> -		gen_boot_verifier(&copy->cp_res.wr_verifier, SVC_NET(rqstp));
> -		status = nfs_ok;
> +	copy->cp_clp = cstate->clp;
> +	memcpy(&copy->fh, &cstate->current_fh.fh_handle,
> +		sizeof(struct knfsd_fh));
> +	copy->net = SVC_NET(rqstp);
> +	if (!copy->cp_synchronous) {
> +		struct nfsd4_copy *async_copy;
> +
> +		status = nfsd4_init_copy_res(copy, 0);
> +		async_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
> +		if (!async_copy) {
> +			status = nfserrno(-ENOMEM);
> +			goto out;
> +		}
> +		dup_copy_fields(copy, async_copy);
> +		memcpy(&copy->cp_res.cb_stateid, &copy->cp_dst_stateid,
> +			sizeof(copy->cp_dst_stateid));
> +		INIT_WORK(&async_copy->cp_work, nfsd4_do_async_copy);
> +		queue_work(copy_wq, &async_copy->cp_work);
> +	} else {
> +		status = nfsd4_do_copy(copy, 1);
>  	}
> -
> -	fput(src);
> -	fput(dst);
>  out:
>  	return status;
>  }
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 0c04f81..fe6f275 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7033,8 +7033,14 @@ static int nfs4_state_create_net(struct net *net)
>  		goto out_free_laundry;
>  
>  	set_max_delegations();
> -	return 0;
>  
> +	ret = nfsd4_create_copy_queue();
> +	if (ret)
> +		goto out_free_callback;
> +
> +	return 0;
> +out_free_callback:
> +	nfsd4_destroy_callback_queue();
>  out_free_laundry:
>  	destroy_workqueue(laundry_wq);
>  out_cleanup_cred:
> @@ -7097,6 +7103,7 @@ static int nfs4_state_create_net(struct net *net)
>  	destroy_workqueue(laundry_wq);
>  	nfsd4_destroy_callback_queue();
>  	cleanup_callback_cred();
> +	nfsd4_destroy_copy_queue();
>  }
>  
>  static void
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index f8b0210..b5358cf 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -630,6 +630,8 @@ extern void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
>  extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name,
>  							struct nfsd_net *nn);
>  extern bool nfs4_has_reclaimed_state(const char *name, struct nfsd_net *nn);
> +extern int nfsd4_create_copy_queue(void);
> +extern void nfsd4_destroy_copy_queue(void);
>  
>  struct nfs4_file *find_file(struct knfsd_fh *fh);
>  void put_nfs4_file(struct nfs4_file *fi);
> diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
> index 9b0c099..f7a94d3 100644
> --- a/fs/nfsd/xdr4.h
> +++ b/fs/nfsd/xdr4.h
> @@ -529,6 +529,13 @@ struct nfsd4_copy {
>  	struct nfsd4_callback	cp_cb;
>  	__be32			nfserr;
>  	struct knfsd_fh		fh;
> +
> +	struct work_struct      cp_work;
> +	struct nfs4_client      *cp_clp;
> +
> +	struct file             *fh_src;
> +	struct file             *fh_dst;
> +	struct net              *net;
>  };
>  
>  struct nfsd4_seek {
> -- 
> 1.8.3.1
>