RDS: Add iWARP support

Support for iWARP NICs is implemented as a separate
RDS transport from IB. The code, however, is very
similar to IB (it was forked, basically.) so let's keep
it in one changeset.

The reason for this duplicationis that despite its similarity
to IB, there are a number of places where it has different
semantics. iwarp zcopy support is still under development,
and giving it its own sandbox ensures that IB code isn't
disrupted while iwarp changes. Over time these transports
will re-converge.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 888 insertions, 0 deletions

diff --git a/net/rds/iw_rdma.c b/net/rds/iw_rdma.c
new file mode 100644
index 000000000000..1c02a8f952d0
--- /dev/null
+++ b/net/rds/iw_rdma.c
@@ -0,0 +1,888 @@
+/*
+ * Copyright (c) 2006 Oracle.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+
+#include "rds.h"
+#include "rdma.h"
+#include "iw.h"
+
+
+/*
+ * This is stored as mr->r_trans_private.
+ */
+struct rds_iw_mr {
+	struct rds_iw_device	*device;
+	struct rds_iw_mr_pool	*pool;
+	struct rdma_cm_id	*cm_id;
+
+	struct ib_mr	*mr;
+	struct ib_fast_reg_page_list *page_list;
+
+	struct rds_iw_mapping	mapping;
+	unsigned char		remap_count;
+};
+
+/*
+ * Our own little MR pool
+ */
+struct rds_iw_mr_pool {
+	struct rds_iw_device	*device;		/* back ptr to the device that owns us */
+
+	struct mutex		flush_lock;		/* serialize fmr invalidate */
+	struct work_struct	flush_worker;		/* flush worker */
+
+	spinlock_t		list_lock;		/* protect variables below */
+	atomic_t		item_count;		/* total # of MRs */
+	atomic_t		dirty_count;		/* # dirty of MRs */
+	struct list_head	dirty_list;		/* dirty mappings */
+	struct list_head	clean_list;		/* unused & unamapped MRs */
+	atomic_t		free_pinned;		/* memory pinned by free MRs */
+	unsigned long		max_message_size;	/* in pages */
+	unsigned long		max_items;
+	unsigned long		max_items_soft;
+	unsigned long		max_free_pinned;
+	int			max_pages;
+};
+
+static int rds_iw_flush_mr_pool(struct rds_iw_mr_pool *pool, int free_all);
+static void rds_iw_mr_pool_flush_worker(struct work_struct *work);
+static int rds_iw_init_fastreg(struct rds_iw_mr_pool *pool, struct rds_iw_mr *ibmr);
+static int rds_iw_map_fastreg(struct rds_iw_mr_pool *pool,
+			  struct rds_iw_mr *ibmr,
+			  struct scatterlist *sg, unsigned int nents);
+static void rds_iw_free_fastreg(struct rds_iw_mr_pool *pool, struct rds_iw_mr *ibmr);
+static unsigned int rds_iw_unmap_fastreg_list(struct rds_iw_mr_pool *pool,
+			struct list_head *unmap_list,
+			struct list_head *kill_list);
+static void rds_iw_destroy_fastreg(struct rds_iw_mr_pool *pool, struct rds_iw_mr *ibmr);
+
+static int rds_iw_get_device(struct rds_sock *rs, struct rds_iw_device **rds_iwdev, struct rdma_cm_id **cm_id)
+{
+	struct rds_iw_device *iwdev;
+	struct rds_iw_cm_id *i_cm_id;
+
+	*rds_iwdev = NULL;
+	*cm_id = NULL;
+
+	list_for_each_entry(iwdev, &rds_iw_devices, list) {
+		spin_lock_irq(&iwdev->spinlock);
+		list_for_each_entry(i_cm_id, &iwdev->cm_id_list, list) {
+			struct sockaddr_in *src_addr, *dst_addr;
+
+			src_addr = (struct sockaddr_in *)&i_cm_id->cm_id->route.addr.src_addr;
+			dst_addr = (struct sockaddr_in *)&i_cm_id->cm_id->route.addr.dst_addr;
+
+			rdsdebug("local ipaddr = %x port %d, "
+				 "remote ipaddr = %x port %d"
+				 "..looking for %x port %d, "
+				 "remote ipaddr = %x port %d\n",
+				src_addr->sin_addr.s_addr,
+				src_addr->sin_port,
+				dst_addr->sin_addr.s_addr,
+				dst_addr->sin_port,
+				rs->rs_bound_addr,
+				rs->rs_bound_port,
+				rs->rs_conn_addr,
+				rs->rs_conn_port);
+#ifdef WORKING_TUPLE_DETECTION
+			if (src_addr->sin_addr.s_addr == rs->rs_bound_addr &&
+			    src_addr->sin_port == rs->rs_bound_port &&
+			    dst_addr->sin_addr.s_addr == rs->rs_conn_addr &&
+			    dst_addr->sin_port == rs->rs_conn_port) {
+#else
+			/* FIXME - needs to compare the local and remote
+			 * ipaddr/port tuple, but the ipaddr is the only
+			 * available infomation in the rds_sock (as the rest are
+			 * zero'ed.  It doesn't appear to be properly populated
+			 * during connection setup...
+			 */
+			if (src_addr->sin_addr.s_addr == rs->rs_bound_addr) {
+#endif
+				spin_unlock_irq(&iwdev->spinlock);
+				*rds_iwdev = iwdev;
+				*cm_id = i_cm_id->cm_id;
+				return 0;
+			}
+		}
+		spin_unlock_irq(&iwdev->spinlock);
+	}
+
+	return 1;
+}
+
+static int rds_iw_add_cm_id(struct rds_iw_device *rds_iwdev, struct rdma_cm_id *cm_id)
+{
+	struct rds_iw_cm_id *i_cm_id;
+
+	i_cm_id = kmalloc(sizeof *i_cm_id, GFP_KERNEL);
+	if (!i_cm_id)
+		return -ENOMEM;
+
+	i_cm_id->cm_id = cm_id;
+
+	spin_lock_irq(&rds_iwdev->spinlock);
+	list_add_tail(&i_cm_id->list, &rds_iwdev->cm_id_list);
+	spin_unlock_irq(&rds_iwdev->spinlock);
+
+	return 0;
+}
+
+void rds_iw_remove_cm_id(struct rds_iw_device *rds_iwdev, struct rdma_cm_id *cm_id)
+{
+	struct rds_iw_cm_id *i_cm_id;
+
+	spin_lock_irq(&rds_iwdev->spinlock);
+	list_for_each_entry(i_cm_id, &rds_iwdev->cm_id_list, list) {
+		if (i_cm_id->cm_id == cm_id) {
+			list_del(&i_cm_id->list);
+			kfree(i_cm_id);
+			break;
+		}
+	}
+	spin_unlock_irq(&rds_iwdev->spinlock);
+}
+
+
+int rds_iw_update_cm_id(struct rds_iw_device *rds_iwdev, struct rdma_cm_id *cm_id)
+{
+	struct sockaddr_in *src_addr, *dst_addr;
+	struct rds_iw_device *rds_iwdev_old;
+	struct rds_sock rs;
+	struct rdma_cm_id *pcm_id;
+	int rc;
+
+	src_addr = (struct sockaddr_in *)&cm_id->route.addr.src_addr;
+	dst_addr = (struct sockaddr_in *)&cm_id->route.addr.dst_addr;
+
+	rs.rs_bound_addr = src_addr->sin_addr.s_addr;
+	rs.rs_bound_port = src_addr->sin_port;
+	rs.rs_conn_addr = dst_addr->sin_addr.s_addr;
+	rs.rs_conn_port = dst_addr->sin_port;
+
+	rc = rds_iw_get_device(&rs, &rds_iwdev_old, &pcm_id);
+	if (rc)
+		rds_iw_remove_cm_id(rds_iwdev, cm_id);
+
+	return rds_iw_add_cm_id(rds_iwdev, cm_id);
+}
+
+int rds_iw_add_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn)
+{
+	struct rds_iw_connection *ic = conn->c_transport_data;
+
+	/* conn was previously on the nodev_conns_list */
+	spin_lock_irq(&iw_nodev_conns_lock);
+	BUG_ON(list_empty(&iw_nodev_conns));
+	BUG_ON(list_empty(&ic->iw_node));
+	list_del(&ic->iw_node);
+	spin_unlock_irq(&iw_nodev_conns_lock);
+
+	spin_lock_irq(&rds_iwdev->spinlock);
+	list_add_tail(&ic->iw_node, &rds_iwdev->conn_list);
+	spin_unlock_irq(&rds_iwdev->spinlock);
+
+	ic->rds_iwdev = rds_iwdev;
+
+	return 0;
+}
+
+void rds_iw_remove_nodev_conns(void)
+{
+	struct rds_iw_connection *ic, *_ic;
+	LIST_HEAD(tmp_list);
+
+	/* avoid calling conn_destroy with irqs off */
+	spin_lock_irq(&iw_nodev_conns_lock);
+	list_splice(&iw_nodev_conns, &tmp_list);
+	INIT_LIST_HEAD(&iw_nodev_conns);
+	spin_unlock_irq(&iw_nodev_conns_lock);
+
+	list_for_each_entry_safe(ic, _ic, &tmp_list, iw_node) {
+		if (ic->conn->c_passive)
+			rds_conn_destroy(ic->conn->c_passive);
+		rds_conn_destroy(ic->conn);
+	}
+}
+
+void rds_iw_remove_conns(struct rds_iw_device *rds_iwdev)
+{
+	struct rds_iw_connection *ic, *_ic;
+	LIST_HEAD(tmp_list);
+
+	/* avoid calling conn_destroy with irqs off */
+	spin_lock_irq(&rds_iwdev->spinlock);
+	list_splice(&rds_iwdev->conn_list, &tmp_list);
+	INIT_LIST_HEAD(&rds_iwdev->conn_list);
+	spin_unlock_irq(&rds_iwdev->spinlock);
+
+	list_for_each_entry_safe(ic, _ic, &tmp_list, iw_node) {
+		if (ic->conn->c_passive)
+			rds_conn_destroy(ic->conn->c_passive);
+		rds_conn_destroy(ic->conn);
+	}
+}
+
+static void rds_iw_set_scatterlist(struct rds_iw_scatterlist *sg,
+		struct scatterlist *list, unsigned int sg_len)
+{
+	sg->list = list;
+	sg->len = sg_len;
+	sg->dma_len = 0;
+	sg->dma_npages = 0;
+	sg->bytes = 0;
+}
+
+static u64 *rds_iw_map_scatterlist(struct rds_iw_device *rds_iwdev,
+			struct rds_iw_scatterlist *sg,
+			unsigned int dma_page_shift)
+{
+	struct ib_device *dev = rds_iwdev->dev;
+	u64 *dma_pages = NULL;
+	u64 dma_mask;
+	unsigned int dma_page_size;
+	int i, j, ret;
+
+	dma_page_size = 1 << dma_page_shift;
+	dma_mask = dma_page_size - 1;
+
+	WARN_ON(sg->dma_len);
+
+	sg->dma_len = ib_dma_map_sg(dev, sg->list, sg->len, DMA_BIDIRECTIONAL);
+	if (unlikely(!sg->dma_len)) {
+		printk(KERN_WARNING "RDS/IW: dma_map_sg failed!\n");
+		return ERR_PTR(-EBUSY);
+	}
+
+	sg->bytes = 0;
+	sg->dma_npages = 0;
+
+	ret = -EINVAL;
+	for (i = 0; i < sg->dma_len; ++i) {
+		unsigned int dma_len = ib_sg_dma_len(dev, &sg->list[i]);
+		u64 dma_addr = ib_sg_dma_address(dev, &sg->list[i]);
+		u64 end_addr;
+
+		sg->bytes += dma_len;
+
+		end_addr = dma_addr + dma_len;
+		if (dma_addr & dma_mask) {
+			if (i > 0)
+				goto out_unmap;
+			dma_addr &= ~dma_mask;
+		}
+		if (end_addr & dma_mask) {
+			if (i < sg->dma_len - 1)
+				goto out_unmap;
+			end_addr = (end_addr + dma_mask) & ~dma_mask;
+		}
+
+		sg->dma_npages += (end_addr - dma_addr) >> dma_page_shift;
+	}
+
+	/* Now gather the dma addrs into one list */
+	if (sg->dma_npages > fastreg_message_size)
+		goto out_unmap;
+
+	dma_pages = kmalloc(sizeof(u64) * sg->dma_npages, GFP_ATOMIC);
+	if (!dma_pages) {
+		ret = -ENOMEM;
+		goto out_unmap;
+	}
+
+	for (i = j = 0; i < sg->dma_len; ++i) {
+		unsigned int dma_len = ib_sg_dma_len(dev, &sg->list[i]);
+		u64 dma_addr = ib_sg_dma_address(dev, &sg->list[i]);
+		u64 end_addr;
+
+		end_addr = dma_addr + dma_len;
+		dma_addr &= ~dma_mask;
+		for (; dma_addr < end_addr; dma_addr += dma_page_size)
+			dma_pages[j++] = dma_addr;
+		BUG_ON(j > sg->dma_npages);
+	}
+
+	return dma_pages;
+
+out_unmap:
+	ib_dma_unmap_sg(rds_iwdev->dev, sg->list, sg->len, DMA_BIDIRECTIONAL);
+	sg->dma_len = 0;
+	kfree(dma_pages);
+	return ERR_PTR(ret);
+}
+
+
+struct rds_iw_mr_pool *rds_iw_create_mr_pool(struct rds_iw_device *rds_iwdev)
+{
+	struct rds_iw_mr_pool *pool;
+
+	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+	if (!pool) {
+		printk(KERN_WARNING "RDS/IW: rds_iw_create_mr_pool alloc error\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	pool->device = rds_iwdev;
+	INIT_LIST_HEAD(&pool->dirty_list);
+	INIT_LIST_HEAD(&pool->clean_list);
+	mutex_init(&pool->flush_lock);
+	spin_lock_init(&pool->list_lock);
+	INIT_WORK(&pool->flush_worker, rds_iw_mr_pool_flush_worker);
+
+	pool->max_message_size = fastreg_message_size;
+	pool->max_items = fastreg_pool_size;
+	pool->max_free_pinned = pool->max_items * pool->max_message_size / 4;
+	pool->max_pages = fastreg_message_size;
+
+	/* We never allow more than max_items MRs to be allocated.
+	 * When we exceed more than max_items_soft, we start freeing
+	 * items more aggressively.
+	 * Make sure that max_items > max_items_soft > max_items / 2
+	 */
+	pool->max_items_soft = pool->max_items * 3 / 4;
+
+	return pool;
+}
+
+void rds_iw_get_mr_info(struct rds_iw_device *rds_iwdev, struct rds_info_rdma_connection *iinfo)
+{
+	struct rds_iw_mr_pool *pool = rds_iwdev->mr_pool;
+
+	iinfo->rdma_mr_max = pool->max_items;
+	iinfo->rdma_mr_size = pool->max_pages;
+}
+
+void rds_iw_destroy_mr_pool(struct rds_iw_mr_pool *pool)
+{
+	flush_workqueue(rds_wq);
+	rds_iw_flush_mr_pool(pool, 1);
+	BUG_ON(atomic_read(&pool->item_count));
+	BUG_ON(atomic_read(&pool->free_pinned));
+	kfree(pool);
+}
+
+static inline struct rds_iw_mr *rds_iw_reuse_fmr(struct rds_iw_mr_pool *pool)
+{
+	struct rds_iw_mr *ibmr = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pool->list_lock, flags);
+	if (!list_empty(&pool->clean_list)) {
+		ibmr = list_entry(pool->clean_list.next, struct rds_iw_mr, mapping.m_list);
+		list_del_init(&ibmr->mapping.m_list);
+	}
+	spin_unlock_irqrestore(&pool->list_lock, flags);
+
+	return ibmr;
+}
+
+static struct rds_iw_mr *rds_iw_alloc_mr(struct rds_iw_device *rds_iwdev)
+{
+	struct rds_iw_mr_pool *pool = rds_iwdev->mr_pool;
+	struct rds_iw_mr *ibmr = NULL;
+	int err = 0, iter = 0;
+
+	while (1) {
+		ibmr = rds_iw_reuse_fmr(pool);
+		if (ibmr)
+			return ibmr;
+
+		/* No clean MRs - now we have the choice of either
+		 * allocating a fresh MR up to the limit imposed by the
+		 * driver, or flush any dirty unused MRs.
+		 * We try to avoid stalling in the send path if possible,
+		 * so we allocate as long as we're allowed to.
+		 *
+		 * We're fussy with enforcing the FMR limit, though. If the driver
+		 * tells us we can't use more than N fmrs, we shouldn't start
+		 * arguing with it */
+		if (atomic_inc_return(&pool->item_count) <= pool->max_items)
+			break;
+
+		atomic_dec(&pool->item_count);
+
+		if (++iter > 2) {
+			rds_iw_stats_inc(s_iw_rdma_mr_pool_depleted);
+			return ERR_PTR(-EAGAIN);
+		}
+
+		/* We do have some empty MRs. Flush them out. */
+		rds_iw_stats_inc(s_iw_rdma_mr_pool_wait);
+		rds_iw_flush_mr_pool(pool, 0);
+	}
+
+	ibmr = kzalloc(sizeof(*ibmr), GFP_KERNEL);
+	if (!ibmr) {
+		err = -ENOMEM;
+		goto out_no_cigar;
+	}
+
+	spin_lock_init(&ibmr->mapping.m_lock);
+	INIT_LIST_HEAD(&ibmr->mapping.m_list);
+	ibmr->mapping.m_mr = ibmr;
+
+	err = rds_iw_init_fastreg(pool, ibmr);
+	if (err)
+		goto out_no_cigar;
+
+	rds_iw_stats_inc(s_iw_rdma_mr_alloc);
+	return ibmr;
+
+out_no_cigar:
+	if (ibmr) {
+		rds_iw_destroy_fastreg(pool, ibmr);
+		kfree(ibmr);
+	}
+	atomic_dec(&pool->item_count);
+	return ERR_PTR(err);
+}
+
+void rds_iw_sync_mr(void *trans_private, int direction)
+{
+	struct rds_iw_mr *ibmr = trans_private;
+	struct rds_iw_device *rds_iwdev = ibmr->device;
+
+	switch (direction) {
+	case DMA_FROM_DEVICE:
+		ib_dma_sync_sg_for_cpu(rds_iwdev->dev, ibmr->mapping.m_sg.list,
+			ibmr->mapping.m_sg.dma_len, DMA_BIDIRECTIONAL);
+		break;
+	case DMA_TO_DEVICE:
+		ib_dma_sync_sg_for_device(rds_iwdev->dev, ibmr->mapping.m_sg.list,
+			ibmr->mapping.m_sg.dma_len, DMA_BIDIRECTIONAL);
+		break;
+	}
+}
+
+static inline unsigned int rds_iw_flush_goal(struct rds_iw_mr_pool *pool, int free_all)
+{
+	unsigned int item_count;
+
+	item_count = atomic_read(&pool->item_count);
+	if (free_all)
+		return item_count;
+
+	return 0;
+}
+
+/*
+ * Flush our pool of MRs.
+ * At a minimum, all currently unused MRs are unmapped.
+ * If the number of MRs allocated exceeds the limit, we also try
+ * to free as many MRs as needed to get back to this limit.
+ */
+static int rds_iw_flush_mr_pool(struct rds_iw_mr_pool *pool, int free_all)
+{
+	struct rds_iw_mr *ibmr, *next;
+	LIST_HEAD(unmap_list);
+	LIST_HEAD(kill_list);
+	unsigned long flags;
+	unsigned int nfreed = 0, ncleaned = 0, free_goal;
+	int ret = 0;
+
+	rds_iw_stats_inc(s_iw_rdma_mr_pool_flush);
+
+	mutex_lock(&pool->flush_lock);
+
+	spin_lock_irqsave(&pool->list_lock, flags);
+	/* Get the list of all mappings to be destroyed */
+	list_splice_init(&pool->dirty_list, &unmap_list);
+	if (free_all)
+		list_splice_init(&pool->clean_list, &kill_list);
+	spin_unlock_irqrestore(&pool->list_lock, flags);
+
+	free_goal = rds_iw_flush_goal(pool, free_all);
+
+	/* Batched invalidate of dirty MRs.
+	 * For FMR based MRs, the mappings on the unmap list are
+	 * actually members of an ibmr (ibmr->mapping). They either
+	 * migrate to the kill_list, or have been cleaned and should be
+	 * moved to the clean_list.
+	 * For fastregs, they will be dynamically allocated, and
+	 * will be destroyed by the unmap function.
+	 */
+	if (!list_empty(&unmap_list)) {
+		ncleaned = rds_iw_unmap_fastreg_list(pool, &unmap_list, &kill_list);
+		/* If we've been asked to destroy all MRs, move those
+		 * that were simply cleaned to the kill list */
+		if (free_all)
+			list_splice_init(&unmap_list, &kill_list);
+	}
+
+	/* Destroy any MRs that are past their best before date */
+	list_for_each_entry_safe(ibmr, next, &kill_list, mapping.m_list) {
+		rds_iw_stats_inc(s_iw_rdma_mr_free);
+		list_del(&ibmr->mapping.m_list);
+		rds_iw_destroy_fastreg(pool, ibmr);
+		kfree(ibmr);
+		nfreed++;
+	}
+
+	/* Anything that remains are laundered ibmrs, which we can add
+	 * back to the clean list. */
+	if (!list_empty(&unmap_list)) {
+		spin_lock_irqsave(&pool->list_lock, flags);
+		list_splice(&unmap_list, &pool->clean_list);
+		spin_unlock_irqrestore(&pool->list_lock, flags);
+	}
+
+	atomic_sub(ncleaned, &pool->dirty_count);
+	atomic_sub(nfreed, &pool->item_count);
+
+	mutex_unlock(&pool->flush_lock);
+	return ret;
+}
+
+static void rds_iw_mr_pool_flush_worker(struct work_struct *work)
+{
+	struct rds_iw_mr_pool *pool = container_of(work, struct rds_iw_mr_pool, flush_worker);
+
+	rds_iw_flush_mr_pool(pool, 0);
+}
+
+void rds_iw_free_mr(void *trans_private, int invalidate)
+{
+	struct rds_iw_mr *ibmr = trans_private;
+	struct rds_iw_mr_pool *pool = ibmr->device->mr_pool;
+
+	rdsdebug("RDS/IW: free_mr nents %u\n", ibmr->mapping.m_sg.len);
+	if (!pool)
+		return;
+
+	/* Return it to the pool's free list */
+	rds_iw_free_fastreg(pool, ibmr);
+
+	/* If we've pinned too many pages, request a flush */
+	if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned
+	 || atomic_read(&pool->dirty_count) >= pool->max_items / 10)
+		queue_work(rds_wq, &pool->flush_worker);
+
+	if (invalidate) {
+		if (likely(!in_interrupt())) {
+			rds_iw_flush_mr_pool(pool, 0);
+		} else {
+			/* We get here if the user created a MR marked
+			 * as use_once and invalidate at the same time. */
+			queue_work(rds_wq, &pool->flush_worker);
+		}
+	}
+}
+
+void rds_iw_flush_mrs(void)
+{
+	struct rds_iw_device *rds_iwdev;
+
+	list_for_each_entry(rds_iwdev, &rds_iw_devices, list) {
+		struct rds_iw_mr_pool *pool = rds_iwdev->mr_pool;
+
+		if (pool)
+			rds_iw_flush_mr_pool(pool, 0);
+	}
+}
+
+void *rds_iw_get_mr(struct scatterlist *sg, unsigned long nents,
+		    struct rds_sock *rs, u32 *key_ret)
+{
+	struct rds_iw_device *rds_iwdev;
+	struct rds_iw_mr *ibmr = NULL;
+	struct rdma_cm_id *cm_id;
+	int ret;
+
+	ret = rds_iw_get_device(rs, &rds_iwdev, &cm_id);
+	if (ret || !cm_id) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (!rds_iwdev->mr_pool) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ibmr = rds_iw_alloc_mr(rds_iwdev);
+	if (IS_ERR(ibmr))
+		return ibmr;
+
+	ibmr->cm_id = cm_id;
+	ibmr->device = rds_iwdev;
+
+	ret = rds_iw_map_fastreg(rds_iwdev->mr_pool, ibmr, sg, nents);
+	if (ret == 0)
+		*key_ret = ibmr->mr->rkey;
+	else
+		printk(KERN_WARNING "RDS/IW: failed to map mr (errno=%d)\n", ret);
+
+out:
+	if (ret) {
+		if (ibmr)
+			rds_iw_free_mr(ibmr, 0);
+		ibmr = ERR_PTR(ret);
+	}
+	return ibmr;
+}
+
+/*
+ * iWARP fastreg handling
+ *
+ * The life cycle of a fastreg registration is a bit different from
+ * FMRs.
+ * The idea behind fastreg is to have one MR, to which we bind different
+ * mappings over time. To avoid stalling on the expensive map and invalidate
+ * operations, these operations are pipelined on the same send queue on
+ * which we want to send the message containing the r_key.
+ *
+ * This creates a bit of a problem for us, as we do not have the destination
+ * IP in GET_MR, so the connection must be setup prior to the GET_MR call for
+ * RDMA to be correctly setup.  If a fastreg request is present, rds_iw_xmit
+ * will try to queue a LOCAL_INV (if needed) and a FAST_REG_MR work request
+ * before queuing the SEND. When completions for these arrive, they are
+ * dispatched to the MR has a bit set showing that RDMa can be performed.
+ *
+ * There is another interesting aspect that's related to invalidation.
+ * The application can request that a mapping is invalidated in FREE_MR.
+ * The expectation there is that this invalidation step includes ALL
+ * PREVIOUSLY FREED MRs.
+ */
+static int rds_iw_init_fastreg(struct rds_iw_mr_pool *pool,
+				struct rds_iw_mr *ibmr)
+{
+	struct rds_iw_device *rds_iwdev = pool->device;
+	struct ib_fast_reg_page_list *page_list = NULL;
+	struct ib_mr *mr;
+	int err;
+
+	mr = ib_alloc_fast_reg_mr(rds_iwdev->pd, pool->max_message_size);
+	if (IS_ERR(mr)) {
+		err = PTR_ERR(mr);
+
+		printk(KERN_WARNING "RDS/IW: ib_alloc_fast_reg_mr failed (err=%d)\n", err);
+		return err;
+	}
+
+	/* FIXME - this is overkill, but mapping->m_sg.dma_len/mapping->m_sg.dma_npages
+	 * is not filled in.
+	 */
+	page_list = ib_alloc_fast_reg_page_list(rds_iwdev->dev, pool->max_message_size);
+	if (IS_ERR(page_list)) {
+		err = PTR_ERR(page_list);
+
+		printk(KERN_WARNING "RDS/IW: ib_alloc_fast_reg_page_list failed (err=%d)\n", err);
+		ib_dereg_mr(mr);
+		return err;
+	}
+
+	ibmr->page_list = page_list;
+	ibmr->mr = mr;
+	return 0;
+}
+
+static int rds_iw_rdma_build_fastreg(struct rds_iw_mapping *mapping)
+{
+	struct rds_iw_mr *ibmr = mapping->m_mr;
+	struct ib_send_wr f_wr, *failed_wr;
+	int ret;
+
+	/*
+	 * Perform a WR for the fast_reg_mr. Each individual page
+	 * in the sg list is added to the fast reg page list and placed
+	 * inside the fast_reg_mr WR.  The key used is a rolling 8bit
+	 * counter, which should guarantee uniqueness.
+	 */
+	ib_update_fast_reg_key(ibmr->mr, ibmr->remap_count++);
+	mapping->m_rkey = ibmr->mr->rkey;
+
+	memset(&f_wr, 0, sizeof(f_wr));
+	f_wr.wr_id = RDS_IW_FAST_REG_WR_ID;
+	f_wr.opcode = IB_WR_FAST_REG_MR;
+	f_wr.wr.fast_reg.length = mapping->m_sg.bytes;
+	f_wr.wr.fast_reg.rkey = mapping->m_rkey;
+	f_wr.wr.fast_reg.page_list = ibmr->page_list;
+	f_wr.wr.fast_reg.page_list_len = mapping->m_sg.dma_len;
+	f_wr.wr.fast_reg.page_shift = ibmr->device->page_shift;
+	f_wr.wr.fast_reg.access_flags = IB_ACCESS_LOCAL_WRITE |
+				IB_ACCESS_REMOTE_READ |
+				IB_ACCESS_REMOTE_WRITE;
+	f_wr.wr.fast_reg.iova_start = 0;
+	f_wr.send_flags = IB_SEND_SIGNALED;
+
+	failed_wr = &f_wr;
+	ret = ib_post_send(ibmr->cm_id->qp, &f_wr, &failed_wr);
+	BUG_ON(failed_wr != &f_wr);
+	if (ret && printk_ratelimit())
+		printk(KERN_WARNING "RDS/IW: %s:%d ib_post_send returned %d\n",
+			__func__, __LINE__, ret);
+	return ret;
+}
+
+static int rds_iw_rdma_fastreg_inv(struct rds_iw_mr *ibmr)
+{
+	struct ib_send_wr s_wr, *failed_wr;
+	int ret = 0;
+
+	if (!ibmr->cm_id->qp || !ibmr->mr)
+		goto out;
+
+	memset(&s_wr, 0, sizeof(s_wr));
+	s_wr.wr_id = RDS_IW_LOCAL_INV_WR_ID;
+	s_wr.opcode = IB_WR_LOCAL_INV;
+	s_wr.ex.invalidate_rkey = ibmr->mr->rkey;
+	s_wr.send_flags = IB_SEND_SIGNALED;
+
+	failed_wr = &s_wr;
+	ret = ib_post_send(ibmr->cm_id->qp, &s_wr, &failed_wr);
+	if (ret && printk_ratelimit()) {
+		printk(KERN_WARNING "RDS/IW: %s:%d ib_post_send returned %d\n",
+			__func__, __LINE__, ret);
+		goto out;
+	}
+out:
+	return ret;
+}
+
+static int rds_iw_map_fastreg(struct rds_iw_mr_pool *pool,
+			struct rds_iw_mr *ibmr,
+			struct scatterlist *sg,
+			unsigned int sg_len)
+{
+	struct rds_iw_device *rds_iwdev = pool->device;
+	struct rds_iw_mapping *mapping = &ibmr->mapping;
+	u64 *dma_pages;
+	int i, ret = 0;
+
+	rds_iw_set_scatterlist(&mapping->m_sg, sg, sg_len);
+
+	dma_pages = rds_iw_map_scatterlist(rds_iwdev,
+				&mapping->m_sg,
+				rds_iwdev->page_shift);
+	if (IS_ERR(dma_pages)) {
+		ret = PTR_ERR(dma_pages);
+		dma_pages = NULL;
+		goto out;
+	}
+
+	if (mapping->m_sg.dma_len > pool->max_message_size) {
+		ret = -EMSGSIZE;
+		goto out;
+	}
+
+	for (i = 0; i < mapping->m_sg.dma_npages; ++i)
+		ibmr->page_list->page_list[i] = dma_pages[i];
+
+	ret = rds_iw_rdma_build_fastreg(mapping);
+	if (ret)
+		goto out;
+
+	rds_iw_stats_inc(s_iw_rdma_mr_used);
+
+out:
+	kfree(dma_pages);
+
+	return ret;
+}
+
+/*
+ * "Free" a fastreg MR.
+ */
+static void rds_iw_free_fastreg(struct rds_iw_mr_pool *pool,
+		struct rds_iw_mr *ibmr)
+{
+	unsigned long flags;
+	int ret;
+
+	if (!ibmr->mapping.m_sg.dma_len)
+		return;
+
+	ret = rds_iw_rdma_fastreg_inv(ibmr);
+	if (ret)
+		return;
+
+	/* Try to post the LOCAL_INV WR to the queue. */
+	spin_lock_irqsave(&pool->list_lock, flags);
+
+	list_add_tail(&ibmr->mapping.m_list, &pool->dirty_list);
+	atomic_add(ibmr->mapping.m_sg.len, &pool->free_pinned);
+	atomic_inc(&pool->dirty_count);
+
+	spin_unlock_irqrestore(&pool->list_lock, flags);
+}
+
+static unsigned int rds_iw_unmap_fastreg_list(struct rds_iw_mr_pool *pool,
+				struct list_head *unmap_list,
+				struct list_head *kill_list)
+{
+	struct rds_iw_mapping *mapping, *next;
+	unsigned int ncleaned = 0;
+	LIST_HEAD(laundered);
+
+	/* Batched invalidation of fastreg MRs.
+	 * Why do we do it this way, even though we could pipeline unmap
+	 * and remap? The reason is the application semantics - when the
+	 * application requests an invalidation of MRs, it expects all
+	 * previously released R_Keys to become invalid.
+	 *
+	 * If we implement MR reuse naively, we risk memory corruption
+	 * (this has actually been observed). So the default behavior
+	 * requires that a MR goes through an explicit unmap operation before
+	 * we can reuse it again.
+	 *
+	 * We could probably improve on this a little, by allowing immediate
+	 * reuse of a MR on the same socket (eg you could add small
+	 * cache of unused MRs to strct rds_socket - GET_MR could grab one
+	 * of these without requiring an explicit invalidate).
+	 */
+	while (!list_empty(unmap_list)) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&pool->list_lock, flags);
+		list_for_each_entry_safe(mapping, next, unmap_list, m_list) {
+			list_move(&mapping->m_list, &laundered);
+			ncleaned++;
+		}
+		spin_unlock_irqrestore(&pool->list_lock, flags);
+	}
+
+	/* Move all laundered mappings back to the unmap list.
+	 * We do not kill any WRs right now - it doesn't seem the
+	 * fastreg API has a max_remap limit. */
+	list_splice_init(&laundered, unmap_list);
+
+	return ncleaned;
+}
+
+static void rds_iw_destroy_fastreg(struct rds_iw_mr_pool *pool,
+		struct rds_iw_mr *ibmr)
+{
+	if (ibmr->page_list)
+		ib_free_fast_reg_page_list(ibmr->page_list);
+	if (ibmr->mr)
+		ib_dereg_mr(ibmr->mr);
+}