xprtrdma: Explicitly resetting MRs is no longer necessary

When a memory operation fails, the MR's driver state might not match
its hardware state. The only reliable recourse is to dereg the MR.
This is done in ->ro_recover_mr, which then attempts to allocate a
fresh MR to replace the released MR.

Since commit e2ac236 ("xprtrdma: Allocate MRs on demand"),
xprtrdma dynamically allocates MRs. It can add more MRs whenever
they are needed.

That makes it possible to simply release an MR when a memory
operation fails, instead of "recovering" it. It will automatically
be replaced by the on-demand MR allocator.

This commit is a little larger than I wanted, but it replaces
->ro_recover_mr, rb_recovery_lock, rb_recovery_worker, and the
rb_stale_mrs list with a generic work queue.

Since MRs are no longer orphaned, the mrs_orphaned metric is no
longer used.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/trace/events/rpcrdma.h

@@ -655,7 +655,7 @@ DEFINE_MR_EVENT(xprtrdma_localinv);
 DEFINE_MR_EVENT(xprtrdma_dma_map);
 DEFINE_MR_EVENT(xprtrdma_dma_unmap);
 DEFINE_MR_EVENT(xprtrdma_remoteinv);
-DEFINE_MR_EVENT(xprtrdma_recover_mr);
+DEFINE_MR_EVENT(xprtrdma_mr_recycle);
 
 /**
  ** Reply events

net/sunrpc/xprtrdma/fmr_ops.c

@@ -49,46 +49,7 @@ fmr_is_supported(struct rpcrdma_ia *ia)
 	return true;
 }
 
-static int
-fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
-{
-	static struct ib_fmr_attr fmr_attr = {
-		.max_pages	= RPCRDMA_MAX_FMR_SGES,
-		.max_maps	= 1,
-		.page_shift	= PAGE_SHIFT
-	};
-
-	mr->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
-				       sizeof(u64), GFP_KERNEL);
-	if (!mr->fmr.fm_physaddrs)
-		goto out_free;
-
-	mr->mr_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
-			    sizeof(*mr->mr_sg), GFP_KERNEL);
-	if (!mr->mr_sg)
-		goto out_free;
-
-	sg_init_table(mr->mr_sg, RPCRDMA_MAX_FMR_SGES);
-
-	mr->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
-				     &fmr_attr);
-	if (IS_ERR(mr->fmr.fm_mr))
-		goto out_fmr_err;
-
-	INIT_LIST_HEAD(&mr->mr_list);
-	return 0;
-
-out_fmr_err:
-	dprintk("RPC:       %s: ib_alloc_fmr returned %ld\n", __func__,
-		PTR_ERR(mr->fmr.fm_mr));
-
-out_free:
-	kfree(mr->mr_sg);
-	kfree(mr->fmr.fm_physaddrs);
-	return -ENOMEM;
-}
-
-static int
+static void
 __fmr_unmap(struct rpcrdma_mr *mr)
 {
 	LIST_HEAD(l);
@@ -97,13 +58,16 @@ __fmr_unmap(struct rpcrdma_mr *mr)
 	list_add(&mr->fmr.fm_mr->list, &l);
 	rc = ib_unmap_fmr(&l);
 	list_del(&mr->fmr.fm_mr->list);
-	return rc;
+	if (rc)
+		pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
+		       mr, rc);
 }
 
+/* Release an MR.
+ */
 static void
 fmr_op_release_mr(struct rpcrdma_mr *mr)
 {
-	LIST_HEAD(unmap_list);
 	int rc;
 
 	kfree(mr->fmr.fm_physaddrs);
@@ -112,10 +76,7 @@ fmr_op_release_mr(struct rpcrdma_mr *mr)
 	/* In case this one was left mapped, try to unmap it
 	 * to prevent dealloc_fmr from failing with EBUSY
 	 */
-	rc = __fmr_unmap(mr);
-	if (rc)
-		pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
-		       mr, rc);
+	__fmr_unmap(mr);
 
 	rc = ib_dealloc_fmr(mr->fmr.fm_mr);
 	if (rc)
@@ -125,40 +86,68 @@ fmr_op_release_mr(struct rpcrdma_mr *mr)
 	kfree(mr);
 }
 
-/* Reset of a single FMR.
+/* MRs are dynamically allocated, so simply clean up and release the MR.
+ * A replacement MR will subsequently be allocated on demand.
  */
 static void
-fmr_op_recover_mr(struct rpcrdma_mr *mr)
+fmr_mr_recycle_worker(struct work_struct *work)
 {
+	struct rpcrdma_mr *mr = container_of(work, struct rpcrdma_mr, mr_recycle);
 	struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
-	int rc;
 
-	/* ORDER: invalidate first */
-	rc = __fmr_unmap(mr);
-	if (rc)
-		goto out_release;
-
-	/* ORDER: then DMA unmap */
-	rpcrdma_mr_unmap_and_put(mr);
-
-	r_xprt->rx_stats.mrs_recovered++;
-	return;
-
-out_release:
-	pr_err("rpcrdma: FMR reset failed (%d), %p released\n", rc, mr);
-	r_xprt->rx_stats.mrs_orphaned++;
+	trace_xprtrdma_mr_recycle(mr);
 
 	trace_xprtrdma_dma_unmap(mr);
 	ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
 			mr->mr_sg, mr->mr_nents, mr->mr_dir);
 
 	spin_lock(&r_xprt->rx_buf.rb_mrlock);
 	list_del(&mr->mr_all);
+	r_xprt->rx_stats.mrs_recycled++;
 	spin_unlock(&r_xprt->rx_buf.rb_mrlock);
-
 	fmr_op_release_mr(mr);
 }
 
+static int
+fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
+{
+	static struct ib_fmr_attr fmr_attr = {
+		.max_pages	= RPCRDMA_MAX_FMR_SGES,
+		.max_maps	= 1,
+		.page_shift	= PAGE_SHIFT
+	};
+
+	mr->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
+				       sizeof(u64), GFP_KERNEL);
+	if (!mr->fmr.fm_physaddrs)
+		goto out_free;
+
+	mr->mr_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
+			    sizeof(*mr->mr_sg), GFP_KERNEL);
+	if (!mr->mr_sg)
+		goto out_free;
+
+	sg_init_table(mr->mr_sg, RPCRDMA_MAX_FMR_SGES);
+
+	mr->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
+				     &fmr_attr);
+	if (IS_ERR(mr->fmr.fm_mr))
+		goto out_fmr_err;
+
+	INIT_LIST_HEAD(&mr->mr_list);
+	INIT_WORK(&mr->mr_recycle, fmr_mr_recycle_worker);
+	return 0;
+
+out_fmr_err:
+	dprintk("RPC:       %s: ib_alloc_fmr returned %ld\n", __func__,
+		PTR_ERR(mr->fmr.fm_mr));
+
+out_free:
+	kfree(mr->mr_sg);
+	kfree(mr->fmr.fm_physaddrs);
+	return -ENOMEM;
+}
+
 /* On success, sets:
  *	ep->rep_attr.cap.max_send_wr
  *	ep->rep_attr.cap.max_recv_wr
@@ -312,7 +301,7 @@ fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
 	r_xprt->rx_stats.local_inv_needed++;
 	rc = ib_unmap_fmr(&unmap_list);
 	if (rc)
-		goto out_reset;
+		goto out_release;
 
 	/* ORDER: Now DMA unmap all of the req's MRs, and return
 	 * them to the free MW list.
@@ -325,21 +314,20 @@ fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
 
 	return;
 
-out_reset:
+out_release:
 	pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
 
 	while (!list_empty(mrs)) {
 		mr = rpcrdma_mr_pop(mrs);
 		list_del(&mr->fmr.fm_mr->list);
-		fmr_op_recover_mr(mr);
+		rpcrdma_mr_recycle(mr);
 	}
 }
 
 const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
 	.ro_map				= fmr_op_map,
 	.ro_send			= fmr_op_send,
 	.ro_unmap_sync			= fmr_op_unmap_sync,
-	.ro_recover_mr			= fmr_op_recover_mr,
 	.ro_open			= fmr_op_open,
 	.ro_maxpages			= fmr_op_maxpages,
 	.ro_init_mr			= fmr_op_init_mr,