/*
   * 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 <linux/slab.h>
  #include <linux/ratelimit.h>
  
  #include "rds.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,
  			int *unpinned);
  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
  ",
  				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 information 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;
  }
  
  static 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);
  }
  
  void 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_lock(&rds_iwdev->spinlock);
  	list_add_tail(&ic->iw_node, &rds_iwdev->conn_list);
  	spin_unlock(&rds_iwdev->spinlock);
  	spin_unlock_irq(&iw_nodev_conns_lock);
  
  	ic->rds_iwdev = rds_iwdev;
  }
  
  void rds_iw_remove_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn)
  {
  	struct rds_iw_connection *ic = conn->c_transport_data;
  
  	/* place conn on nodev_conns_list */
  	spin_lock(&iw_nodev_conns_lock);
  
  	spin_lock_irq(&rds_iwdev->spinlock);
  	BUG_ON(list_empty(&ic->iw_node));
  	list_del(&ic->iw_node);
  	spin_unlock_irq(&rds_iwdev->spinlock);
  
  	list_add_tail(&ic->iw_node, &iw_nodev_conns);
  
  	spin_unlock(&iw_nodev_conns_lock);
  
  	rds_iw_remove_cm_id(ic->rds_iwdev, ic->i_cm_id);
  	ic->rds_iwdev = NULL;
  }
  
  void __rds_iw_destroy_conns(struct list_head *list, spinlock_t *list_lock)
  {
  	struct rds_iw_connection *ic, *_ic;
  	LIST_HEAD(tmp_list);
  
  	/* avoid calling conn_destroy with irqs off */
  	spin_lock_irq(list_lock);
  	list_splice(list, &tmp_list);
  	INIT_LIST_HEAD(list);
  	spin_unlock_irq(list_lock);
  
  	list_for_each_entry_safe(ic, _ic, &tmp_list, iw_node)
  		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)
  {
  	struct ib_device *dev = rds_iwdev->dev;
  	u64 *dma_pages = NULL;
  	int i, j, ret;
  
  	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!
  ");
  		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 & PAGE_MASK) {
  			if (i > 0)
  				goto out_unmap;
  			dma_addr &= ~PAGE_MASK;
  		}
  		if (end_addr & PAGE_MASK) {
  			if (i < sg->dma_len - 1)
  				goto out_unmap;
  			end_addr = (end_addr + PAGE_MASK) & ~PAGE_MASK;
  		}
  
  		sg->dma_npages += (end_addr - dma_addr) >> 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 &= ~PAGE_MASK;
  		for (; dma_addr < end_addr; dma_addr += 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
  ");
  		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;
  	}
  }
  
  /*
   * 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, unpinned = 0;
  	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);
  
  	/* 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, &unpinned);
  		/* 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(unpinned, &pool->free_pinned);
  	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
  ", 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)
  ", 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)
  ", 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)
  ", 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 = 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_ratelimited(KERN_WARNING "RDS/IW: %s:%d ib_post_send returned %d
  ",
  			__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_ratelimited(KERN_WARNING "RDS/IW: %s:%d ib_post_send returned %d
  ",
  			__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);
  	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,
  				int *unpinned)
  {
  	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) {
  			*unpinned += mapping->m_sg.len;
  			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);
  }