net/rds/ib_frmr.c - third_party/linux - Git at Google

 /*
  * Copyright (c) 2016 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 "ib_mr.h"

 static inline void
 rds_transition_frwr_state(struct rds_ib_mr *ibmr,
 			  enum rds_ib_fr_state old_state,
 			  enum rds_ib_fr_state new_state)
 {
 	if (cmpxchg(&ibmr->u.frmr.fr_state,
 		    old_state, new_state) == old_state &&
 	    old_state == FRMR_IS_INUSE) {
 		/* enforce order of ibmr->u.frmr.fr_state update
 		 * before decrementing i_fastreg_inuse_count
 		 */
 		smp_mb__before_atomic();
 		atomic_dec(&ibmr->ic->i_fastreg_inuse_count);
 		if (waitqueue_active(&rds_ib_ring_empty_wait))
 			wake_up(&rds_ib_ring_empty_wait);
 	}
 }

 static struct rds_ib_mr *rds_ib_alloc_frmr(struct rds_ib_device *rds_ibdev,
 					   int npages)
 {
 	struct rds_ib_mr_pool *pool;
 	struct rds_ib_mr *ibmr = NULL;
 	struct rds_ib_frmr *frmr;
 	int err = 0;

 	if (npages <= RDS_MR_8K_MSG_SIZE)
 		pool = rds_ibdev->mr_8k_pool;
 	else
 		pool = rds_ibdev->mr_1m_pool;

 	ibmr = rds_ib_try_reuse_ibmr(pool);
 	if (ibmr)
 		return ibmr;

 	ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL,
 			    rdsibdev_to_node(rds_ibdev));
 	if (!ibmr) {
 		err = -ENOMEM;
 		goto out_no_cigar;
 	}

 	frmr = &ibmr->u.frmr;
 	frmr->mr = ib_alloc_mr(rds_ibdev->pd, IB_MR_TYPE_MEM_REG,
 			 pool->fmr_attr.max_pages);
 	if (IS_ERR(frmr->mr)) {
 		pr_warn("RDS/IB: %s failed to allocate MR", __func__);
 		err = PTR_ERR(frmr->mr);
 		goto out_no_cigar;
 	}

 	ibmr->pool = pool;
 	if (pool->pool_type == RDS_IB_MR_8K_POOL)
 		rds_ib_stats_inc(s_ib_rdma_mr_8k_alloc);
 	else
 		rds_ib_stats_inc(s_ib_rdma_mr_1m_alloc);

 	if (atomic_read(&pool->item_count) > pool->max_items_soft)
 		pool->max_items_soft = pool->max_items;

 	frmr->fr_state = FRMR_IS_FREE;
 	init_waitqueue_head(&frmr->fr_inv_done);
 	init_waitqueue_head(&frmr->fr_reg_done);
 	return ibmr;

 out_no_cigar:
 	kfree(ibmr);
 	atomic_dec(&pool->item_count);
 	return ERR_PTR(err);
 }

 static void rds_ib_free_frmr(struct rds_ib_mr *ibmr, bool drop)
 {
 	struct rds_ib_mr_pool *pool = ibmr->pool;

 	if (drop)
 		llist_add(&ibmr->llnode, &pool->drop_list);
 	else
 		llist_add(&ibmr->llnode, &pool->free_list);
 	atomic_add(ibmr->sg_len, &pool->free_pinned);
 	atomic_inc(&pool->dirty_count);

 	/* 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 / 5)
 		queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
 }

 static int rds_ib_post_reg_frmr(struct rds_ib_mr *ibmr)
 {
 	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
 	struct ib_reg_wr reg_wr;
 	int ret, off = 0;

 	while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
 		atomic_inc(&ibmr->ic->i_fastreg_wrs);
 		cpu_relax();
 	}

 	ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_dma_len,
 				&off, PAGE_SIZE);
 	if (unlikely(ret != ibmr->sg_dma_len))
 		return ret < 0 ? ret : -EINVAL;

 	if (cmpxchg(&frmr->fr_state,
 		    FRMR_IS_FREE, FRMR_IS_INUSE) != FRMR_IS_FREE)
 		return -EBUSY;

 	atomic_inc(&ibmr->ic->i_fastreg_inuse_count);

 	/* 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(frmr->mr, ibmr->remap_count++);
 	frmr->fr_reg = true;

 	memset(&reg_wr, 0, sizeof(reg_wr));
 	reg_wr.wr.wr_id = (unsigned long)(void *)ibmr;
 	reg_wr.wr.opcode = IB_WR_REG_MR;
 	reg_wr.wr.num_sge = 0;
 	reg_wr.mr = frmr->mr;
 	reg_wr.key = frmr->mr->rkey;
 	reg_wr.access = IB_ACCESS_LOCAL_WRITE |
 			IB_ACCESS_REMOTE_READ |
 			IB_ACCESS_REMOTE_WRITE;
 	reg_wr.wr.send_flags = IB_SEND_SIGNALED;

 	ret = ib_post_send(ibmr->ic->i_cm_id->qp, &reg_wr.wr, NULL);
 	if (unlikely(ret)) {
 		/* Failure here can be because of -ENOMEM as well */
 		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);

 		atomic_inc(&ibmr->ic->i_fastreg_wrs);
 		if (printk_ratelimit())
 			pr_warn("RDS/IB: %s returned error(%d)\n",
 				__func__, ret);
 		goto out;
 	}

 	/* Wait for the registration to complete in order to prevent an invalid
 	 * access error resulting from a race between the memory region already
 	 * being accessed while registration is still pending.
 	 */
 	wait_event(frmr->fr_reg_done, !frmr->fr_reg);

 out:

 	return ret;
 }

 static int rds_ib_map_frmr(struct rds_ib_device *rds_ibdev,
 			   struct rds_ib_mr_pool *pool,
 			   struct rds_ib_mr *ibmr,
 			   struct scatterlist *sg, unsigned int sg_len)
 {
 	struct ib_device *dev = rds_ibdev->dev;
 	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
 	int i;
 	u32 len;
 	int ret = 0;

 	/* We want to teardown old ibmr values here and fill it up with
 	 * new sg values
 	 */
 	rds_ib_teardown_mr(ibmr);

 	ibmr->sg = sg;
 	ibmr->sg_len = sg_len;
 	ibmr->sg_dma_len = 0;
 	frmr->sg_byte_len = 0;
 	WARN_ON(ibmr->sg_dma_len);
 	ibmr->sg_dma_len = ib_dma_map_sg(dev, ibmr->sg, ibmr->sg_len,
 					 DMA_BIDIRECTIONAL);
 	if (unlikely(!ibmr->sg_dma_len)) {
 		pr_warn("RDS/IB: %s failed!\n", __func__);
 		return -EBUSY;
 	}

 	frmr->sg_byte_len = 0;
 	frmr->dma_npages = 0;
 	len = 0;

 	ret = -EINVAL;
 	for (i = 0; i < ibmr->sg_dma_len; ++i) {
 		unsigned int dma_len = sg_dma_len(&ibmr->sg[i]);
 		u64 dma_addr = sg_dma_address(&ibmr->sg[i]);

 		frmr->sg_byte_len += dma_len;
 		if (dma_addr & ~PAGE_MASK) {
 			if (i > 0)
 				goto out_unmap;
 			else
 				++frmr->dma_npages;
 		}

 		if ((dma_addr + dma_len) & ~PAGE_MASK) {
 			if (i < ibmr->sg_dma_len - 1)
 				goto out_unmap;
 			else
 				++frmr->dma_npages;
 		}

 		len += dma_len;
 	}
 	frmr->dma_npages += len >> PAGE_SHIFT;

 	if (frmr->dma_npages > ibmr->pool->fmr_attr.max_pages) {
 		ret = -EMSGSIZE;
 		goto out_unmap;
 	}

 	ret = rds_ib_post_reg_frmr(ibmr);
 	if (ret)
 		goto out_unmap;

 	if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
 		rds_ib_stats_inc(s_ib_rdma_mr_8k_used);
 	else
 		rds_ib_stats_inc(s_ib_rdma_mr_1m_used);

 	return ret;

 out_unmap:
 	ib_dma_unmap_sg(rds_ibdev->dev, ibmr->sg, ibmr->sg_len,
 			DMA_BIDIRECTIONAL);
 	ibmr->sg_dma_len = 0;
 	return ret;
 }

 static int rds_ib_post_inv(struct rds_ib_mr *ibmr)
 {
 	struct ib_send_wr *s_wr;
 	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
 	struct rdma_cm_id *i_cm_id = ibmr->ic->i_cm_id;
 	int ret = -EINVAL;

 	if (!i_cm_id || !i_cm_id->qp || !frmr->mr)
 		goto out;

 	if (frmr->fr_state != FRMR_IS_INUSE)
 		goto out;

 	while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
 		atomic_inc(&ibmr->ic->i_fastreg_wrs);
 		cpu_relax();
 	}

 	frmr->fr_inv = true;
 	s_wr = &frmr->fr_wr;

 	memset(s_wr, 0, sizeof(*s_wr));
 	s_wr->wr_id = (unsigned long)(void *)ibmr;
 	s_wr->opcode = IB_WR_LOCAL_INV;
 	s_wr->ex.invalidate_rkey = frmr->mr->rkey;
 	s_wr->send_flags = IB_SEND_SIGNALED;

 	ret = ib_post_send(i_cm_id->qp, s_wr, NULL);
 	if (unlikely(ret)) {
 		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);
 		frmr->fr_inv = false;
 		/* enforce order of frmr->fr_inv update
 		 * before incrementing i_fastreg_wrs
 		 */
 		smp_mb__before_atomic();
 		atomic_inc(&ibmr->ic->i_fastreg_wrs);
 		pr_err("RDS/IB: %s returned error(%d)\n", __func__, ret);
 		goto out;
 	}

 	/* Wait for the FRMR_IS_FREE (or FRMR_IS_STALE) transition in order to
 	 * 1) avoid a silly bouncing between "clean_list" and "drop_list"
 	 *    triggered by function "rds_ib_reg_frmr" as it is releases frmr
 	 *    regions whose state is not "FRMR_IS_FREE" right away.
 	 * 2) prevents an invalid access error in a race
 	 *    from a pending "IB_WR_LOCAL_INV" operation
 	 *    with a teardown ("dma_unmap_sg", "put_page")
 	 *    and de-registration ("ib_dereg_mr") of the corresponding
 	 *    memory region.
 	 */
 	wait_event(frmr->fr_inv_done, frmr->fr_state != FRMR_IS_INUSE);

 out:
 	return ret;
 }

 void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
 {
 	struct rds_ib_mr *ibmr = (void *)(unsigned long)wc->wr_id;
 	struct rds_ib_frmr *frmr = &ibmr->u.frmr;

 	if (wc->status != IB_WC_SUCCESS) {
 		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);
 		if (rds_conn_up(ic->conn))
 			rds_ib_conn_error(ic->conn,
 					  "frmr completion <%pI4,%pI4> status %u(%s), vendor_err 0x%x, disconnecting and reconnecting\n",
 					  &ic->conn->c_laddr,
 					  &ic->conn->c_faddr,
 					  wc->status,
 					  ib_wc_status_msg(wc->status),
 					  wc->vendor_err);
 	}

 	if (frmr->fr_inv) {
 		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_FREE);
 		frmr->fr_inv = false;
 		wake_up(&frmr->fr_inv_done);
 	}

 	if (frmr->fr_reg) {
 		frmr->fr_reg = false;
 		wake_up(&frmr->fr_reg_done);
 	}

 	/* enforce order of frmr->{fr_reg,fr_inv} update
 	 * before incrementing i_fastreg_wrs
 	 */
 	smp_mb__before_atomic();
 	atomic_inc(&ic->i_fastreg_wrs);
 }

 void rds_ib_unreg_frmr(struct list_head *list, unsigned int *nfreed,
 		       unsigned long *unpinned, unsigned int goal)
 {
 	struct rds_ib_mr *ibmr, *next;
 	struct rds_ib_frmr *frmr;
 	int ret = 0, ret2;
 	unsigned int freed = *nfreed;

 	/* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
 	list_for_each_entry(ibmr, list, unmap_list) {
 		if (ibmr->sg_dma_len) {
 			ret2 = rds_ib_post_inv(ibmr);
 			if (ret2 && !ret)
 				ret = ret2;
 		}
 	}

 	if (ret)
 		pr_warn("RDS/IB: %s failed (err=%d)\n", __func__, ret);

 	/* Now we can destroy the DMA mapping and unpin any pages */
 	list_for_each_entry_safe(ibmr, next, list, unmap_list) {
 		*unpinned += ibmr->sg_len;
 		frmr = &ibmr->u.frmr;
 		__rds_ib_teardown_mr(ibmr);
 		if (freed < goal || frmr->fr_state == FRMR_IS_STALE) {
 			/* Don't de-allocate if the MR is not free yet */
 			if (frmr->fr_state == FRMR_IS_INUSE)
 				continue;

 			if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
 				rds_ib_stats_inc(s_ib_rdma_mr_8k_free);
 			else
 				rds_ib_stats_inc(s_ib_rdma_mr_1m_free);
 			list_del(&ibmr->unmap_list);
 			if (frmr->mr)
 				ib_dereg_mr(frmr->mr);
 			kfree(ibmr);
 			freed++;
 		}
 	}
 	*nfreed = freed;
 }

 struct rds_ib_mr *rds_ib_reg_frmr(struct rds_ib_device *rds_ibdev,
 				  struct rds_ib_connection *ic,
 				  struct scatterlist *sg,
 				  unsigned long nents, u32 *key)
 {
 	struct rds_ib_mr *ibmr = NULL;
 	struct rds_ib_frmr *frmr;
 	int ret;

 	if (!ic) {
 		/* TODO: Add FRWR support for RDS_GET_MR using proxy qp*/
 		return ERR_PTR(-EOPNOTSUPP);
 	}

 	do {
 		if (ibmr)
 			rds_ib_free_frmr(ibmr, true);
 		ibmr = rds_ib_alloc_frmr(rds_ibdev, nents);
 		if (IS_ERR(ibmr))
 			return ibmr;
 		frmr = &ibmr->u.frmr;
 	} while (frmr->fr_state != FRMR_IS_FREE);

 	ibmr->ic = ic;
 	ibmr->device = rds_ibdev;
 	ret = rds_ib_map_frmr(rds_ibdev, ibmr->pool, ibmr, sg, nents);
 	if (ret == 0) {
 		*key = frmr->mr->rkey;
 	} else {
 		rds_ib_free_frmr(ibmr, false);
 		ibmr = ERR_PTR(ret);
 	}

 	return ibmr;
 }

 void rds_ib_free_frmr_list(struct rds_ib_mr *ibmr)
 {
 	struct rds_ib_mr_pool *pool = ibmr->pool;
 	struct rds_ib_frmr *frmr = &ibmr->u.frmr;

 	if (frmr->fr_state == FRMR_IS_STALE)
 		llist_add(&ibmr->llnode, &pool->drop_list);
 	else
 		llist_add(&ibmr->llnode, &pool->free_list);
 }
	/*
	* Copyright (c) 2016 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 "ib_mr.h"

	static inline void
	rds_transition_frwr_state(struct rds_ib_mr *ibmr,
	enum rds_ib_fr_state old_state,
	enum rds_ib_fr_state new_state)
	{
	if (cmpxchg(&ibmr->u.frmr.fr_state,
	old_state, new_state) == old_state &&
	old_state == FRMR_IS_INUSE) {
	/* enforce order of ibmr->u.frmr.fr_state update
	* before decrementing i_fastreg_inuse_count
	*/
	smp_mb__before_atomic();
	atomic_dec(&ibmr->ic->i_fastreg_inuse_count);
	if (waitqueue_active(&rds_ib_ring_empty_wait))
	wake_up(&rds_ib_ring_empty_wait);
	}
	}

	static struct rds_ib_mr rds_ib_alloc_frmr(struct rds_ib_device rds_ibdev,
	int npages)
	{
	struct rds_ib_mr_pool *pool;
	struct rds_ib_mr *ibmr = NULL;
	struct rds_ib_frmr *frmr;
	int err = 0;

	if (npages <= RDS_MR_8K_MSG_SIZE)
	pool = rds_ibdev->mr_8k_pool;
	else
	pool = rds_ibdev->mr_1m_pool;

	ibmr = rds_ib_try_reuse_ibmr(pool);
	if (ibmr)
	return ibmr;

	ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL,
	rdsibdev_to_node(rds_ibdev));
	if (!ibmr) {
	err = -ENOMEM;
	goto out_no_cigar;
	}

	frmr = &ibmr->u.frmr;
	frmr->mr = ib_alloc_mr(rds_ibdev->pd, IB_MR_TYPE_MEM_REG,
	pool->fmr_attr.max_pages);
	if (IS_ERR(frmr->mr)) {
	pr_warn("RDS/IB: %s failed to allocate MR", __func__);
	err = PTR_ERR(frmr->mr);
	goto out_no_cigar;
	}

	ibmr->pool = pool;
	if (pool->pool_type == RDS_IB_MR_8K_POOL)
	rds_ib_stats_inc(s_ib_rdma_mr_8k_alloc);
	else
	rds_ib_stats_inc(s_ib_rdma_mr_1m_alloc);

	if (atomic_read(&pool->item_count) > pool->max_items_soft)
	pool->max_items_soft = pool->max_items;

	frmr->fr_state = FRMR_IS_FREE;
	init_waitqueue_head(&frmr->fr_inv_done);
	init_waitqueue_head(&frmr->fr_reg_done);
	return ibmr;

	out_no_cigar:
	kfree(ibmr);
	atomic_dec(&pool->item_count);
	return ERR_PTR(err);
	}

	static void rds_ib_free_frmr(struct rds_ib_mr *ibmr, bool drop)
	{
	struct rds_ib_mr_pool *pool = ibmr->pool;

	if (drop)
	llist_add(&ibmr->llnode, &pool->drop_list);
	else
	llist_add(&ibmr->llnode, &pool->free_list);
	atomic_add(ibmr->sg_len, &pool->free_pinned);
	atomic_inc(&pool->dirty_count);

	/* 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 / 5)
	queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
	}

	static int rds_ib_post_reg_frmr(struct rds_ib_mr *ibmr)
	{
	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
	struct ib_reg_wr reg_wr;
	int ret, off = 0;

	while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
	atomic_inc(&ibmr->ic->i_fastreg_wrs);
	cpu_relax();
	}

	ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_dma_len,
	&off, PAGE_SIZE);
	if (unlikely(ret != ibmr->sg_dma_len))
	return ret < 0 ? ret : -EINVAL;

	if (cmpxchg(&frmr->fr_state,
	FRMR_IS_FREE, FRMR_IS_INUSE) != FRMR_IS_FREE)
	return -EBUSY;

	atomic_inc(&ibmr->ic->i_fastreg_inuse_count);

	/* 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(frmr->mr, ibmr->remap_count++);
	frmr->fr_reg = true;

	memset(&reg_wr, 0, sizeof(reg_wr));
	reg_wr.wr.wr_id = (unsigned long)(void *)ibmr;
	reg_wr.wr.opcode = IB_WR_REG_MR;
	reg_wr.wr.num_sge = 0;
	reg_wr.mr = frmr->mr;
	reg_wr.key = frmr->mr->rkey;
	reg_wr.access = IB_ACCESS_LOCAL_WRITE \|
	IB_ACCESS_REMOTE_READ \|
	IB_ACCESS_REMOTE_WRITE;
	reg_wr.wr.send_flags = IB_SEND_SIGNALED;

	ret = ib_post_send(ibmr->ic->i_cm_id->qp, &reg_wr.wr, NULL);
	if (unlikely(ret)) {
	/* Failure here can be because of -ENOMEM as well */
	rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);

	atomic_inc(&ibmr->ic->i_fastreg_wrs);
	if (printk_ratelimit())
	pr_warn("RDS/IB: %s returned error(%d)\n",
	__func__, ret);
	goto out;
	}

	/* Wait for the registration to complete in order to prevent an invalid
	* access error resulting from a race between the memory region already
	* being accessed while registration is still pending.
	*/
	wait_event(frmr->fr_reg_done, !frmr->fr_reg);

	out:

	return ret;
	}

	static int rds_ib_map_frmr(struct rds_ib_device *rds_ibdev,
	struct rds_ib_mr_pool *pool,
	struct rds_ib_mr *ibmr,
	struct scatterlist *sg, unsigned int sg_len)
	{
	struct ib_device *dev = rds_ibdev->dev;
	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
	int i;
	u32 len;
	int ret = 0;

	/* We want to teardown old ibmr values here and fill it up with
	* new sg values
	*/
	rds_ib_teardown_mr(ibmr);

	ibmr->sg = sg;
	ibmr->sg_len = sg_len;
	ibmr->sg_dma_len = 0;
	frmr->sg_byte_len = 0;
	WARN_ON(ibmr->sg_dma_len);
	ibmr->sg_dma_len = ib_dma_map_sg(dev, ibmr->sg, ibmr->sg_len,
	DMA_BIDIRECTIONAL);
	if (unlikely(!ibmr->sg_dma_len)) {
	pr_warn("RDS/IB: %s failed!\n", __func__);
	return -EBUSY;
	}

	frmr->sg_byte_len = 0;
	frmr->dma_npages = 0;
	len = 0;

	ret = -EINVAL;
	for (i = 0; i < ibmr->sg_dma_len; ++i) {
	unsigned int dma_len = sg_dma_len(&ibmr->sg[i]);
	u64 dma_addr = sg_dma_address(&ibmr->sg[i]);

	frmr->sg_byte_len += dma_len;
	if (dma_addr & ~PAGE_MASK) {
	if (i > 0)
	goto out_unmap;
	else
	++frmr->dma_npages;
	}

	if ((dma_addr + dma_len) & ~PAGE_MASK) {
	if (i < ibmr->sg_dma_len - 1)
	goto out_unmap;
	else
	++frmr->dma_npages;
	}

	len += dma_len;
	}
	frmr->dma_npages += len >> PAGE_SHIFT;

	if (frmr->dma_npages > ibmr->pool->fmr_attr.max_pages) {
	ret = -EMSGSIZE;
	goto out_unmap;
	}

	ret = rds_ib_post_reg_frmr(ibmr);
	if (ret)
	goto out_unmap;

	if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
	rds_ib_stats_inc(s_ib_rdma_mr_8k_used);
	else
	rds_ib_stats_inc(s_ib_rdma_mr_1m_used);

	return ret;

	out_unmap:
	ib_dma_unmap_sg(rds_ibdev->dev, ibmr->sg, ibmr->sg_len,
	DMA_BIDIRECTIONAL);
	ibmr->sg_dma_len = 0;
	return ret;
	}

	static int rds_ib_post_inv(struct rds_ib_mr *ibmr)
	{
	struct ib_send_wr *s_wr;
	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
	struct rdma_cm_id *i_cm_id = ibmr->ic->i_cm_id;
	int ret = -EINVAL;

	if (!i_cm_id \|\| !i_cm_id->qp \|\| !frmr->mr)
	goto out;

	if (frmr->fr_state != FRMR_IS_INUSE)
	goto out;

	while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
	atomic_inc(&ibmr->ic->i_fastreg_wrs);
	cpu_relax();
	}

	frmr->fr_inv = true;
	s_wr = &frmr->fr_wr;

	memset(s_wr, 0, sizeof(*s_wr));
	s_wr->wr_id = (unsigned long)(void *)ibmr;
	s_wr->opcode = IB_WR_LOCAL_INV;
	s_wr->ex.invalidate_rkey = frmr->mr->rkey;
	s_wr->send_flags = IB_SEND_SIGNALED;

	ret = ib_post_send(i_cm_id->qp, s_wr, NULL);
	if (unlikely(ret)) {
	rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);
	frmr->fr_inv = false;
	/* enforce order of frmr->fr_inv update
	* before incrementing i_fastreg_wrs
	*/
	smp_mb__before_atomic();
	atomic_inc(&ibmr->ic->i_fastreg_wrs);
	pr_err("RDS/IB: %s returned error(%d)\n", __func__, ret);
	goto out;
	}

	/* Wait for the FRMR_IS_FREE (or FRMR_IS_STALE) transition in order to
	* 1) avoid a silly bouncing between "clean_list" and "drop_list"
	* triggered by function "rds_ib_reg_frmr" as it is releases frmr
	* regions whose state is not "FRMR_IS_FREE" right away.
	* 2) prevents an invalid access error in a race
	* from a pending "IB_WR_LOCAL_INV" operation
	* with a teardown ("dma_unmap_sg", "put_page")
	* and de-registration ("ib_dereg_mr") of the corresponding
	* memory region.
	*/
	wait_event(frmr->fr_inv_done, frmr->fr_state != FRMR_IS_INUSE);

	out:
	return ret;
	}

	void rds_ib_mr_cqe_handler(struct rds_ib_connection ic, struct ib_wc wc)
	{
	struct rds_ib_mr ibmr = (void )(unsigned long)wc->wr_id;
	struct rds_ib_frmr *frmr = &ibmr->u.frmr;

	if (wc->status != IB_WC_SUCCESS) {
	rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);
	if (rds_conn_up(ic->conn))
	rds_ib_conn_error(ic->conn,
	"frmr completion <%pI4,%pI4> status %u(%s), vendor_err 0x%x, disconnecting and reconnecting\n",
	&ic->conn->c_laddr,
	&ic->conn->c_faddr,
	wc->status,
	ib_wc_status_msg(wc->status),
	wc->vendor_err);
	}

	if (frmr->fr_inv) {
	rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_FREE);
	frmr->fr_inv = false;
	wake_up(&frmr->fr_inv_done);
	}

	if (frmr->fr_reg) {
	frmr->fr_reg = false;
	wake_up(&frmr->fr_reg_done);
	}

	/* enforce order of frmr->{fr_reg,fr_inv} update
	* before incrementing i_fastreg_wrs
	*/
	smp_mb__before_atomic();
	atomic_inc(&ic->i_fastreg_wrs);
	}

	void rds_ib_unreg_frmr(struct list_head list, unsigned int nfreed,
	unsigned long *unpinned, unsigned int goal)
	{
	struct rds_ib_mr ibmr, next;
	struct rds_ib_frmr *frmr;
	int ret = 0, ret2;
	unsigned int freed = *nfreed;

	/* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
	list_for_each_entry(ibmr, list, unmap_list) {
	if (ibmr->sg_dma_len) {
	ret2 = rds_ib_post_inv(ibmr);
	if (ret2 && !ret)
	ret = ret2;
	}
	}

	if (ret)
	pr_warn("RDS/IB: %s failed (err=%d)\n", __func__, ret);

	/* Now we can destroy the DMA mapping and unpin any pages */
	list_for_each_entry_safe(ibmr, next, list, unmap_list) {
	*unpinned += ibmr->sg_len;
	frmr = &ibmr->u.frmr;
	__rds_ib_teardown_mr(ibmr);
	if (freed < goal \|\| frmr->fr_state == FRMR_IS_STALE) {
	/* Don't de-allocate if the MR is not free yet */
	if (frmr->fr_state == FRMR_IS_INUSE)
	continue;

	if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
	rds_ib_stats_inc(s_ib_rdma_mr_8k_free);
	else
	rds_ib_stats_inc(s_ib_rdma_mr_1m_free);
	list_del(&ibmr->unmap_list);
	if (frmr->mr)
	ib_dereg_mr(frmr->mr);
	kfree(ibmr);
	freed++;
	}
	}
	*nfreed = freed;
	}

	struct rds_ib_mr rds_ib_reg_frmr(struct rds_ib_device rds_ibdev,
	struct rds_ib_connection *ic,
	struct scatterlist *sg,
	unsigned long nents, u32 *key)
	{
	struct rds_ib_mr *ibmr = NULL;
	struct rds_ib_frmr *frmr;
	int ret;

	if (!ic) {
	/* TODO: Add FRWR support for RDS_GET_MR using proxy qp*/
	return ERR_PTR(-EOPNOTSUPP);
	}

	do {
	if (ibmr)
	rds_ib_free_frmr(ibmr, true);
	ibmr = rds_ib_alloc_frmr(rds_ibdev, nents);
	if (IS_ERR(ibmr))
	return ibmr;
	frmr = &ibmr->u.frmr;
	} while (frmr->fr_state != FRMR_IS_FREE);

	ibmr->ic = ic;
	ibmr->device = rds_ibdev;
	ret = rds_ib_map_frmr(rds_ibdev, ibmr->pool, ibmr, sg, nents);
	if (ret == 0) {
	*key = frmr->mr->rkey;
	} else {
	rds_ib_free_frmr(ibmr, false);
	ibmr = ERR_PTR(ret);
	}

	return ibmr;
	}

	void rds_ib_free_frmr_list(struct rds_ib_mr *ibmr)
	{
	struct rds_ib_mr_pool *pool = ibmr->pool;
	struct rds_ib_frmr *frmr = &ibmr->u.frmr;

	if (frmr->fr_state == FRMR_IS_STALE)
	llist_add(&ibmr->llnode, &pool->drop_list);
	else
	llist_add(&ibmr->llnode, &pool->free_list);
	}