[PATCH v6 08/10] NFSD handle OFFLOAD_CANCEL op

[Olga Kornievskaia <kolga@xxxxxxxxxx>]

Upon receiving OFFLOAD_CANCEL search the list of copy stateids,
if found then set the SIGPENDING signal so that do_splice stops
copying and also send kthread_stop to the copy thread to stop
and wait for it. Take a reference on the copy from the
offload_cancel thread so that it won't go away while we are
trying to process it. Server won't be sending CB_OFFLOAD to the
client since it received a cancel.

Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
---
 fs/nfsd/nfs4proc.c | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 fs/nfsd/xdr4.h     |  1 +
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 6876080..3b0bb54 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1097,6 +1097,14 @@ static int fill_in_write_vector(struct kvec *vec, struct nfsd4_write *write)
 out:
 	return status;
 }
+
+static void nfs4_put_copy(struct nfsd4_copy *copy)
+{
+	if (!atomic_dec_and_test(&copy->refcount))
+		return;
+	kfree(copy);
+}
+
 static void nfsd4_cb_offload_release(struct nfsd4_callback *cb)
 {
 	struct nfsd4_copy *copy = container_of(cb, struct nfsd4_copy, cp_cb);
@@ -1134,6 +1142,8 @@ static int _nfsd_copy_file_range(struct nfsd4_copy *copy)
 	u64 dst_pos = copy->cp_dst_pos;
 
 	do {
+		if (signalled() || kthread_should_stop())
+			return -1;
 		bytes_copied = nfsd_copy_file_range(copy->fh_src, src_pos,
 				copy->fh_dst, dst_pos, bytes_total);
 		if (bytes_copied <= 0)
@@ -1152,11 +1162,16 @@ static int nfsd4_do_copy(struct nfsd4_copy *copy, bool sync)
 	ssize_t bytes;
 
 	bytes = _nfsd_copy_file_range(copy);
+	if (signalled() || kthread_should_stop()) {
+		status = -1;
+		goto cleanup;
+	}
 	if (bytes < 0 && !copy->cp_res.wr_bytes_written)
 		status = nfserrno(bytes);
 	else
 		status = nfsd4_init_copy_res(copy, sync);
 
+cleanup:
 	fput(copy->fh_src);
 	fput(copy->fh_dst);
 	return status;
@@ -1194,7 +1209,7 @@ static void cleanup_async_copy(struct nfsd4_copy *copy)
 	list_del(&copy->copies);
 	spin_unlock(&copy->cp_clp->async_lock);
 	atomic_dec(&copy->cp_clp->cl_refcount);
-	kfree(copy);
+	nfs4_put_copy(copy);
 }
 
 static int nfsd4_do_async_copy(void *data)
@@ -1203,6 +1218,9 @@ static int nfsd4_do_async_copy(void *data)
 	struct nfsd4_copy *cb_copy;
 
 	copy->nfserr = nfsd4_do_copy(copy, 0);
+	if (signalled() || kthread_should_stop())
+		goto out;
+
 	cb_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
 	if (!cb_copy)
 		goto out;
@@ -1259,6 +1277,7 @@ static int nfsd4_do_async_copy(void *data)
 		memcpy(&copy->cp_res.cb_stateid, &copy->cps->cp_stateid,
 			sizeof(copy->cps->cp_stateid));
 		dup_copy_fields(copy, async_copy);
+		atomic_set(&async_copy->refcount, 1);
 		spin_lock(&async_copy->cp_clp->async_lock);
 		list_add(&async_copy->copies,
 				&async_copy->cp_clp->async_copies);
@@ -1285,7 +1304,30 @@ static int nfsd4_do_async_copy(void *data)
 		     struct nfsd4_compound_state *cstate,
 		     union nfsd4_op_u *u)
 {
-	return 0;
+	struct nfsd4_offload_status *os = &u->offload_status;
+	__be32 status = 0;
+	struct nfsd4_copy *copy;
+	bool found = false;
+	struct nfs4_client *clp = cstate->clp;
+
+	spin_lock(&clp->async_lock);
+	list_for_each_entry(copy, &clp->async_copies, copies) {
+		if (memcmp(&copy->cps->cp_stateid, &os->stateid,
+				NFS4_STATEID_SIZE))
+			continue;
+		found = true;
+		atomic_inc(&copy->refcount);
+		break;
+	}
+	spin_unlock(&clp->async_lock);
+	if (found) {
+		set_tsk_thread_flag(copy->copy_task, TIF_SIGPENDING);
+		kthread_stop(copy->copy_task);
+		nfs4_put_copy(copy);
+	} else
+		status = nfserr_bad_stateid;
+
+	return status;
 }
 
 static __be32
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 27bac6a..3127b58 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -540,6 +540,7 @@ struct nfsd4_copy {
 
 	struct list_head	copies;
 	struct task_struct	*copy_task;
+	atomic_t		refcount;
 };
 
 struct nfsd4_seek {
-- 
1.8.3.1

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