v4.19.13 snapshot.
diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c
new file mode 100644
index 0000000..3c15a99
--- /dev/null
+++ b/net/sunrpc/backchannel_rqst.c
@@ -0,0 +1,364 @@
+/******************************************************************************
+
+(c) 2007 Network Appliance, Inc. All Rights Reserved.
+(c) 2009 NetApp. All Rights Reserved.
+
+NetApp provides this source code under the GPL v2 License.
+The GPL v2 license is available at
+http://opensource.org/licenses/gpl-license.php.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+******************************************************************************/
+
+#include <linux/tcp.h>
+#include <linux/slab.h>
+#include <linux/sunrpc/xprt.h>
+#include <linux/export.h>
+#include <linux/sunrpc/bc_xprt.h>
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+#define RPCDBG_FACILITY RPCDBG_TRANS
+#endif
+
+/*
+ * Helper routines that track the number of preallocation elements
+ * on the transport.
+ */
+static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
+{
+ return xprt->bc_alloc_count < atomic_read(&xprt->bc_free_slots);
+}
+
+static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
+{
+ atomic_add(n, &xprt->bc_free_slots);
+ xprt->bc_alloc_count += n;
+}
+
+static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
+{
+ atomic_sub(n, &xprt->bc_free_slots);
+ return xprt->bc_alloc_count -= n;
+}
+
+/*
+ * Free the preallocated rpc_rqst structure and the memory
+ * buffers hanging off of it.
+ */
+static void xprt_free_allocation(struct rpc_rqst *req)
+{
+ struct xdr_buf *xbufp;
+
+ dprintk("RPC: free allocations for req= %p\n", req);
+ WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
+ xbufp = &req->rq_rcv_buf;
+ free_page((unsigned long)xbufp->head[0].iov_base);
+ xbufp = &req->rq_snd_buf;
+ free_page((unsigned long)xbufp->head[0].iov_base);
+ kfree(req);
+}
+
+static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
+{
+ struct page *page;
+ /* Preallocate one XDR receive buffer */
+ page = alloc_page(gfp_flags);
+ if (page == NULL)
+ return -ENOMEM;
+ xdr_buf_init(buf, page_address(page), PAGE_SIZE);
+ return 0;
+}
+
+static
+struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
+{
+ struct rpc_rqst *req;
+
+ /* Pre-allocate one backchannel rpc_rqst */
+ req = kzalloc(sizeof(*req), gfp_flags);
+ if (req == NULL)
+ return NULL;
+
+ req->rq_xprt = xprt;
+ INIT_LIST_HEAD(&req->rq_list);
+ INIT_LIST_HEAD(&req->rq_bc_list);
+
+ /* Preallocate one XDR receive buffer */
+ if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
+ printk(KERN_ERR "Failed to create bc receive xbuf\n");
+ goto out_free;
+ }
+ req->rq_rcv_buf.len = PAGE_SIZE;
+
+ /* Preallocate one XDR send buffer */
+ if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
+ printk(KERN_ERR "Failed to create bc snd xbuf\n");
+ goto out_free;
+ }
+ return req;
+out_free:
+ xprt_free_allocation(req);
+ return NULL;
+}
+
+/*
+ * Preallocate up to min_reqs structures and related buffers for use
+ * by the backchannel. This function can be called multiple times
+ * when creating new sessions that use the same rpc_xprt. The
+ * preallocated buffers are added to the pool of resources used by
+ * the rpc_xprt. Anyone of these resources may be used used by an
+ * incoming callback request. It's up to the higher levels in the
+ * stack to enforce that the maximum number of session slots is not
+ * being exceeded.
+ *
+ * Some callback arguments can be large. For example, a pNFS server
+ * using multiple deviceids. The list can be unbound, but the client
+ * has the ability to tell the server the maximum size of the callback
+ * requests. Each deviceID is 16 bytes, so allocate one page
+ * for the arguments to have enough room to receive a number of these
+ * deviceIDs. The NFS client indicates to the pNFS server that its
+ * callback requests can be up to 4096 bytes in size.
+ */
+int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
+{
+ if (!xprt->ops->bc_setup)
+ return 0;
+ return xprt->ops->bc_setup(xprt, min_reqs);
+}
+EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
+
+int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
+{
+ struct rpc_rqst *req;
+ struct list_head tmp_list;
+ int i;
+
+ dprintk("RPC: setup backchannel transport\n");
+
+ /*
+ * We use a temporary list to keep track of the preallocated
+ * buffers. Once we're done building the list we splice it
+ * into the backchannel preallocation list off of the rpc_xprt
+ * struct. This helps minimize the amount of time the list
+ * lock is held on the rpc_xprt struct. It also makes cleanup
+ * easier in case of memory allocation errors.
+ */
+ INIT_LIST_HEAD(&tmp_list);
+ for (i = 0; i < min_reqs; i++) {
+ /* Pre-allocate one backchannel rpc_rqst */
+ req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
+ if (req == NULL) {
+ printk(KERN_ERR "Failed to create bc rpc_rqst\n");
+ goto out_free;
+ }
+
+ /* Add the allocated buffer to the tmp list */
+ dprintk("RPC: adding req= %p\n", req);
+ list_add(&req->rq_bc_pa_list, &tmp_list);
+ }
+
+ /*
+ * Add the temporary list to the backchannel preallocation list
+ */
+ spin_lock(&xprt->bc_pa_lock);
+ list_splice(&tmp_list, &xprt->bc_pa_list);
+ xprt_inc_alloc_count(xprt, min_reqs);
+ spin_unlock(&xprt->bc_pa_lock);
+
+ dprintk("RPC: setup backchannel transport done\n");
+ return 0;
+
+out_free:
+ /*
+ * Memory allocation failed, free the temporary list
+ */
+ while (!list_empty(&tmp_list)) {
+ req = list_first_entry(&tmp_list,
+ struct rpc_rqst,
+ rq_bc_pa_list);
+ list_del(&req->rq_bc_pa_list);
+ xprt_free_allocation(req);
+ }
+
+ dprintk("RPC: setup backchannel transport failed\n");
+ return -ENOMEM;
+}
+
+/**
+ * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
+ * @xprt: the transport holding the preallocated strucures
+ * @max_reqs the maximum number of preallocated structures to destroy
+ *
+ * Since these structures may have been allocated by multiple calls
+ * to xprt_setup_backchannel, we only destroy up to the maximum number
+ * of reqs specified by the caller.
+ */
+void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
+{
+ if (xprt->ops->bc_destroy)
+ xprt->ops->bc_destroy(xprt, max_reqs);
+}
+EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
+
+void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
+{
+ struct rpc_rqst *req = NULL, *tmp = NULL;
+
+ dprintk("RPC: destroy backchannel transport\n");
+
+ if (max_reqs == 0)
+ goto out;
+
+ spin_lock_bh(&xprt->bc_pa_lock);
+ xprt_dec_alloc_count(xprt, max_reqs);
+ list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
+ dprintk("RPC: req=%p\n", req);
+ list_del(&req->rq_bc_pa_list);
+ xprt_free_allocation(req);
+ if (--max_reqs == 0)
+ break;
+ }
+ spin_unlock_bh(&xprt->bc_pa_lock);
+
+out:
+ dprintk("RPC: backchannel list empty= %s\n",
+ list_empty(&xprt->bc_pa_list) ? "true" : "false");
+}
+
+static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid)
+{
+ struct rpc_rqst *req = NULL;
+
+ dprintk("RPC: allocate a backchannel request\n");
+ if (atomic_read(&xprt->bc_free_slots) <= 0)
+ goto not_found;
+ if (list_empty(&xprt->bc_pa_list)) {
+ req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
+ if (!req)
+ goto not_found;
+ list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
+ xprt->bc_alloc_count++;
+ }
+ req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
+ rq_bc_pa_list);
+ req->rq_reply_bytes_recvd = 0;
+ req->rq_bytes_sent = 0;
+ memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
+ sizeof(req->rq_private_buf));
+ req->rq_xid = xid;
+ req->rq_connect_cookie = xprt->connect_cookie;
+not_found:
+ dprintk("RPC: backchannel req=%p\n", req);
+ return req;
+}
+
+/*
+ * Return the preallocated rpc_rqst structure and XDR buffers
+ * associated with this rpc_task.
+ */
+void xprt_free_bc_request(struct rpc_rqst *req)
+{
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ xprt->ops->bc_free_rqst(req);
+}
+
+void xprt_free_bc_rqst(struct rpc_rqst *req)
+{
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ dprintk("RPC: free backchannel req=%p\n", req);
+
+ req->rq_connect_cookie = xprt->connect_cookie - 1;
+ smp_mb__before_atomic();
+ clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
+ smp_mb__after_atomic();
+
+ /*
+ * Return it to the list of preallocations so that it
+ * may be reused by a new callback request.
+ */
+ spin_lock_bh(&xprt->bc_pa_lock);
+ if (xprt_need_to_requeue(xprt)) {
+ list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
+ xprt->bc_alloc_count++;
+ req = NULL;
+ }
+ spin_unlock_bh(&xprt->bc_pa_lock);
+ if (req != NULL) {
+ /*
+ * The last remaining session was destroyed while this
+ * entry was in use. Free the entry and don't attempt
+ * to add back to the list because there is no need to
+ * have anymore preallocated entries.
+ */
+ dprintk("RPC: Last session removed req=%p\n", req);
+ xprt_free_allocation(req);
+ return;
+ }
+}
+
+/*
+ * One or more rpc_rqst structure have been preallocated during the
+ * backchannel setup. Buffer space for the send and private XDR buffers
+ * has been preallocated as well. Use xprt_alloc_bc_request to allocate
+ * to this request. Use xprt_free_bc_request to return it.
+ *
+ * We know that we're called in soft interrupt context, grab the spin_lock
+ * since there is no need to grab the bottom half spin_lock.
+ *
+ * Return an available rpc_rqst, otherwise NULL if non are available.
+ */
+struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
+{
+ struct rpc_rqst *req;
+
+ spin_lock(&xprt->bc_pa_lock);
+ list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
+ if (req->rq_connect_cookie != xprt->connect_cookie)
+ continue;
+ if (req->rq_xid == xid)
+ goto found;
+ }
+ req = xprt_alloc_bc_request(xprt, xid);
+found:
+ spin_unlock(&xprt->bc_pa_lock);
+ return req;
+}
+
+/*
+ * Add callback request to callback list. The callback
+ * service sleeps on the sv_cb_waitq waiting for new
+ * requests. Wake it up after adding enqueing the
+ * request.
+ */
+void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
+{
+ struct rpc_xprt *xprt = req->rq_xprt;
+ struct svc_serv *bc_serv = xprt->bc_serv;
+
+ spin_lock(&xprt->bc_pa_lock);
+ list_del(&req->rq_bc_pa_list);
+ xprt_dec_alloc_count(xprt, 1);
+ spin_unlock(&xprt->bc_pa_lock);
+
+ req->rq_private_buf.len = copied;
+ set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
+
+ dprintk("RPC: add callback request to list\n");
+ spin_lock(&bc_serv->sv_cb_lock);
+ list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
+ wake_up(&bc_serv->sv_cb_waitq);
+ spin_unlock(&bc_serv->sv_cb_lock);
+}