/*
   * Copyright (c) 2007 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/pagemap.h>

  #include <linux/slab.h>

  #include <linux/rbtree.h>
  #include <linux/dma-mapping.h> /* for DMA_*_DEVICE */

  #include "rds.h"

  
  /*
   * XXX
   *  - build with sparse
   *  - should we limit the size of a mr region?  let transport return failure?
   *  - should we detect duplicate keys on a socket?  hmm.
   *  - an rdma is an mlock, apply rlimit?
   */
  
  /*
   * get the number of pages by looking at the page indices that the start and
   * end addresses fall in.
   *
   * Returns 0 if the vec is invalid.  It is invalid if the number of bytes
   * causes the address to wrap or overflows an unsigned int.  This comes
   * from being stored in the 'length' member of 'struct scatterlist'.
   */
  static unsigned int rds_pages_in_vec(struct rds_iovec *vec)
  {
  	if ((vec->addr + vec->bytes <= vec->addr) ||
  	    (vec->bytes > (u64)UINT_MAX))
  		return 0;
  
  	return ((vec->addr + vec->bytes + PAGE_SIZE - 1) >> PAGE_SHIFT) -
  		(vec->addr >> PAGE_SHIFT);
  }
  
  static struct rds_mr *rds_mr_tree_walk(struct rb_root *root, u64 key,
  				       struct rds_mr *insert)
  {
  	struct rb_node **p = &root->rb_node;
  	struct rb_node *parent = NULL;
  	struct rds_mr *mr;
  
  	while (*p) {
  		parent = *p;
  		mr = rb_entry(parent, struct rds_mr, r_rb_node);
  
  		if (key < mr->r_key)
  			p = &(*p)->rb_left;
  		else if (key > mr->r_key)
  			p = &(*p)->rb_right;
  		else
  			return mr;
  	}
  
  	if (insert) {
  		rb_link_node(&insert->r_rb_node, parent, p);
  		rb_insert_color(&insert->r_rb_node, root);
  		atomic_inc(&insert->r_refcount);
  	}
  	return NULL;
  }
  
  /*
   * Destroy the transport-specific part of a MR.
   */
  static void rds_destroy_mr(struct rds_mr *mr)
  {
  	struct rds_sock *rs = mr->r_sock;
  	void *trans_private = NULL;
  	unsigned long flags;
  
  	rdsdebug("RDS: destroy mr key is %x refcnt %u
  ",
  			mr->r_key, atomic_read(&mr->r_refcount));
  
  	if (test_and_set_bit(RDS_MR_DEAD, &mr->r_state))
  		return;
  
  	spin_lock_irqsave(&rs->rs_rdma_lock, flags);
  	if (!RB_EMPTY_NODE(&mr->r_rb_node))
  		rb_erase(&mr->r_rb_node, &rs->rs_rdma_keys);
  	trans_private = mr->r_trans_private;
  	mr->r_trans_private = NULL;
  	spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  
  	if (trans_private)
  		mr->r_trans->free_mr(trans_private, mr->r_invalidate);
  }
  
  void __rds_put_mr_final(struct rds_mr *mr)
  {
  	rds_destroy_mr(mr);
  	kfree(mr);
  }
  
  /*
   * By the time this is called we can't have any more ioctls called on
   * the socket so we don't need to worry about racing with others.
   */
  void rds_rdma_drop_keys(struct rds_sock *rs)
  {
  	struct rds_mr *mr;
  	struct rb_node *node;

  	unsigned long flags;

  
  	/* Release any MRs associated with this socket */

  	spin_lock_irqsave(&rs->rs_rdma_lock, flags);

  	while ((node = rb_first(&rs->rs_rdma_keys))) {
  		mr = container_of(node, struct rds_mr, r_rb_node);
  		if (mr->r_trans == rs->rs_transport)
  			mr->r_invalidate = 0;

  		rb_erase(&mr->r_rb_node, &rs->rs_rdma_keys);
  		RB_CLEAR_NODE(&mr->r_rb_node);
  		spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  		rds_destroy_mr(mr);

  		rds_mr_put(mr);

  		spin_lock_irqsave(&rs->rs_rdma_lock, flags);

  	}

  	spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);

  
  	if (rs->rs_transport && rs->rs_transport->flush_mrs)
  		rs->rs_transport->flush_mrs();
  }
  
  /*
   * Helper function to pin user pages.
   */
  static int rds_pin_pages(unsigned long user_addr, unsigned int nr_pages,
  			struct page **pages, int write)
  {
  	int ret;

  	ret = get_user_pages_fast(user_addr, nr_pages, write, pages);

  	if (ret >= 0 && ret < nr_pages) {

  		while (ret--)
  			put_page(pages[ret]);
  		ret = -EFAULT;
  	}
  
  	return ret;
  }
  
  static int __rds_rdma_map(struct rds_sock *rs, struct rds_get_mr_args *args,
  				u64 *cookie_ret, struct rds_mr **mr_ret)
  {
  	struct rds_mr *mr = NULL, *found;
  	unsigned int nr_pages;
  	struct page **pages = NULL;
  	struct scatterlist *sg;
  	void *trans_private;
  	unsigned long flags;
  	rds_rdma_cookie_t cookie;
  	unsigned int nents;
  	long i;
  	int ret;
  
  	if (rs->rs_bound_addr == 0) {
  		ret = -ENOTCONN; /* XXX not a great errno */
  		goto out;
  	}

  	if (!rs->rs_transport->get_mr) {

  		ret = -EOPNOTSUPP;
  		goto out;
  	}
  
  	nr_pages = rds_pages_in_vec(&args->vec);
  	if (nr_pages == 0) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	rdsdebug("RDS: get_mr addr %llx len %llu nr_pages %u
  ",
  		args->vec.addr, args->vec.bytes, nr_pages);
  
  	/* XXX clamp nr_pages to limit the size of this alloc? */
  	pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);

  	if (!pages) {

  		ret = -ENOMEM;
  		goto out;
  	}
  
  	mr = kzalloc(sizeof(struct rds_mr), GFP_KERNEL);

  	if (!mr) {

  		ret = -ENOMEM;
  		goto out;
  	}
  
  	atomic_set(&mr->r_refcount, 1);
  	RB_CLEAR_NODE(&mr->r_rb_node);
  	mr->r_trans = rs->rs_transport;
  	mr->r_sock = rs;
  
  	if (args->flags & RDS_RDMA_USE_ONCE)
  		mr->r_use_once = 1;
  	if (args->flags & RDS_RDMA_INVALIDATE)
  		mr->r_invalidate = 1;
  	if (args->flags & RDS_RDMA_READWRITE)
  		mr->r_write = 1;
  
  	/*
  	 * Pin the pages that make up the user buffer and transfer the page
  	 * pointers to the mr's sg array.  We check to see if we've mapped
  	 * the whole region after transferring the partial page references
  	 * to the sg array so that we can have one page ref cleanup path.
  	 *
  	 * For now we have no flag that tells us whether the mapping is
  	 * r/o or r/w. We need to assume r/w, or we'll do a lot of RDMA to
  	 * the zero page.
  	 */

  	ret = rds_pin_pages(args->vec.addr, nr_pages, pages, 1);

  	if (ret < 0)
  		goto out;
  
  	nents = ret;
  	sg = kcalloc(nents, sizeof(*sg), GFP_KERNEL);

  	if (!sg) {

  		ret = -ENOMEM;
  		goto out;
  	}
  	WARN_ON(!nents);
  	sg_init_table(sg, nents);
  
  	/* Stick all pages into the scatterlist */
  	for (i = 0 ; i < nents; i++)
  		sg_set_page(&sg[i], pages[i], PAGE_SIZE, 0);
  
  	rdsdebug("RDS: trans_private nents is %u
  ", nents);
  
  	/* Obtain a transport specific MR. If this succeeds, the
  	 * s/g list is now owned by the MR.
  	 * Note that dma_map() implies that pending writes are
  	 * flushed to RAM, so no dma_sync is needed here. */
  	trans_private = rs->rs_transport->get_mr(sg, nents, rs,
  						 &mr->r_key);
  
  	if (IS_ERR(trans_private)) {
  		for (i = 0 ; i < nents; i++)
  			put_page(sg_page(&sg[i]));
  		kfree(sg);
  		ret = PTR_ERR(trans_private);
  		goto out;
  	}
  
  	mr->r_trans_private = trans_private;
  
  	rdsdebug("RDS: get_mr put_user key is %x cookie_addr %p
  ",
  	       mr->r_key, (void *)(unsigned long) args->cookie_addr);
  
  	/* The user may pass us an unaligned address, but we can only
  	 * map page aligned regions. So we keep the offset, and build
  	 * a 64bit cookie containing <R_Key, offset> and pass that
  	 * around. */
  	cookie = rds_rdma_make_cookie(mr->r_key, args->vec.addr & ~PAGE_MASK);
  	if (cookie_ret)
  		*cookie_ret = cookie;
  
  	if (args->cookie_addr && put_user(cookie, (u64 __user *)(unsigned long) args->cookie_addr)) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  	/* Inserting the new MR into the rbtree bumps its
  	 * reference count. */
  	spin_lock_irqsave(&rs->rs_rdma_lock, flags);
  	found = rds_mr_tree_walk(&rs->rs_rdma_keys, mr->r_key, mr);
  	spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  
  	BUG_ON(found && found != mr);
  
  	rdsdebug("RDS: get_mr key is %x
  ", mr->r_key);
  	if (mr_ret) {
  		atomic_inc(&mr->r_refcount);
  		*mr_ret = mr;
  	}
  
  	ret = 0;
  out:
  	kfree(pages);
  	if (mr)
  		rds_mr_put(mr);
  	return ret;
  }
  
  int rds_get_mr(struct rds_sock *rs, char __user *optval, int optlen)
  {
  	struct rds_get_mr_args args;
  
  	if (optlen != sizeof(struct rds_get_mr_args))
  		return -EINVAL;
  
  	if (copy_from_user(&args, (struct rds_get_mr_args __user *)optval,
  			   sizeof(struct rds_get_mr_args)))
  		return -EFAULT;
  
  	return __rds_rdma_map(rs, &args, NULL, NULL);
  }

  int rds_get_mr_for_dest(struct rds_sock *rs, char __user *optval, int optlen)
  {
  	struct rds_get_mr_for_dest_args args;
  	struct rds_get_mr_args new_args;
  
  	if (optlen != sizeof(struct rds_get_mr_for_dest_args))
  		return -EINVAL;
  
  	if (copy_from_user(&args, (struct rds_get_mr_for_dest_args __user *)optval,
  			   sizeof(struct rds_get_mr_for_dest_args)))
  		return -EFAULT;
  
  	/*
  	 * Initially, just behave like get_mr().
  	 * TODO: Implement get_mr as wrapper around this
  	 *	 and deprecate it.
  	 */
  	new_args.vec = args.vec;
  	new_args.cookie_addr = args.cookie_addr;
  	new_args.flags = args.flags;
  
  	return __rds_rdma_map(rs, &new_args, NULL, NULL);
  }

  /*
   * Free the MR indicated by the given R_Key
   */
  int rds_free_mr(struct rds_sock *rs, char __user *optval, int optlen)
  {
  	struct rds_free_mr_args args;
  	struct rds_mr *mr;
  	unsigned long flags;
  
  	if (optlen != sizeof(struct rds_free_mr_args))
  		return -EINVAL;
  
  	if (copy_from_user(&args, (struct rds_free_mr_args __user *)optval,
  			   sizeof(struct rds_free_mr_args)))
  		return -EFAULT;
  
  	/* Special case - a null cookie means flush all unused MRs */
  	if (args.cookie == 0) {
  		if (!rs->rs_transport || !rs->rs_transport->flush_mrs)
  			return -EINVAL;
  		rs->rs_transport->flush_mrs();
  		return 0;
  	}
  
  	/* Look up the MR given its R_key and remove it from the rbtree
  	 * so nobody else finds it.
  	 * This should also prevent races with rds_rdma_unuse.
  	 */
  	spin_lock_irqsave(&rs->rs_rdma_lock, flags);
  	mr = rds_mr_tree_walk(&rs->rs_rdma_keys, rds_rdma_cookie_key(args.cookie), NULL);
  	if (mr) {
  		rb_erase(&mr->r_rb_node, &rs->rs_rdma_keys);
  		RB_CLEAR_NODE(&mr->r_rb_node);
  		if (args.flags & RDS_RDMA_INVALIDATE)
  			mr->r_invalidate = 1;
  	}
  	spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  
  	if (!mr)
  		return -EINVAL;
  
  	/*
  	 * call rds_destroy_mr() ourselves so that we're sure it's done by the time
  	 * we return.  If we let rds_mr_put() do it it might not happen until
  	 * someone else drops their ref.
  	 */
  	rds_destroy_mr(mr);
  	rds_mr_put(mr);
  	return 0;
  }
  
  /*
   * This is called when we receive an extension header that
   * tells us this MR was used. It allows us to implement
   * use_once semantics
   */
  void rds_rdma_unuse(struct rds_sock *rs, u32 r_key, int force)
  {
  	struct rds_mr *mr;
  	unsigned long flags;
  	int zot_me = 0;
  
  	spin_lock_irqsave(&rs->rs_rdma_lock, flags);
  	mr = rds_mr_tree_walk(&rs->rs_rdma_keys, r_key, NULL);

  	if (!mr) {
  		printk(KERN_ERR "rds: trying to unuse MR with unknown r_key %u!
  ", r_key);
  		spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  		return;
  	}
  
  	if (mr->r_use_once || force) {

  		rb_erase(&mr->r_rb_node, &rs->rs_rdma_keys);
  		RB_CLEAR_NODE(&mr->r_rb_node);
  		zot_me = 1;

  	}

  	spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  
  	/* May have to issue a dma_sync on this memory region.
  	 * Note we could avoid this if the operation was a RDMA READ,
  	 * but at this point we can't tell. */

  	if (mr->r_trans->sync_mr)
  		mr->r_trans->sync_mr(mr->r_trans_private, DMA_FROM_DEVICE);

  	/* If the MR was marked as invalidate, this will
  	 * trigger an async flush. */
  	if (zot_me)
  		rds_destroy_mr(mr);
  	rds_mr_put(mr);

  }

  void rds_rdma_free_op(struct rm_rdma_op *ro)

  {
  	unsigned int i;

  	for (i = 0; i < ro->op_nents; i++) {
  		struct page *page = sg_page(&ro->op_sg[i]);

  
  		/* Mark page dirty if it was possibly modified, which
  		 * is the case for a RDMA_READ which copies from remote
  		 * to local memory */

  		if (!ro->op_write) {

  			BUG_ON(irqs_disabled());

  			set_page_dirty(page);

  		}

  		put_page(page);
  	}

  	kfree(ro->op_notifier);
  	ro->op_notifier = NULL;
  	ro->op_active = 0;

  }

  void rds_atomic_free_op(struct rm_atomic_op *ao)
  {
  	struct page *page = sg_page(ao->op_sg);
  
  	/* Mark page dirty if it was possibly modified, which
  	 * is the case for a RDMA_READ which copies from remote
  	 * to local memory */
  	set_page_dirty(page);
  	put_page(page);
  
  	kfree(ao->op_notifier);
  	ao->op_notifier = NULL;
  	ao->op_active = 0;
  }

  /*

   * Count the number of pages needed to describe an incoming iovec array.

   */

  static int rds_rdma_pages(struct rds_iovec iov[], int nr_iovecs)
  {
  	int tot_pages = 0;
  	unsigned int nr_pages;
  	unsigned int i;
  
  	/* figure out the number of pages in the vector */
  	for (i = 0; i < nr_iovecs; i++) {
  		nr_pages = rds_pages_in_vec(&iov[i]);
  		if (nr_pages == 0)
  			return -EINVAL;
  
  		tot_pages += nr_pages;
  
  		/*
  		 * nr_pages for one entry is limited to (UINT_MAX>>PAGE_SHIFT)+1,
  		 * so tot_pages cannot overflow without first going negative.
  		 */
  		if (tot_pages < 0)
  			return -EINVAL;
  	}
  
  	return tot_pages;
  }
  
  int rds_rdma_extra_size(struct rds_rdma_args *args)

  {
  	struct rds_iovec vec;
  	struct rds_iovec __user *local_vec;

  	int tot_pages = 0;

  	unsigned int nr_pages;
  	unsigned int i;
  
  	local_vec = (struct rds_iovec __user *)(unsigned long) args->local_vec_addr;
  
  	/* figure out the number of pages in the vector */
  	for (i = 0; i < args->nr_local; i++) {
  		if (copy_from_user(&vec, &local_vec[i],
  				   sizeof(struct rds_iovec)))
  			return -EFAULT;
  
  		nr_pages = rds_pages_in_vec(&vec);
  		if (nr_pages == 0)
  			return -EINVAL;
  
  		tot_pages += nr_pages;

  
  		/*
  		 * nr_pages for one entry is limited to (UINT_MAX>>PAGE_SHIFT)+1,
  		 * so tot_pages cannot overflow without first going negative.
  		 */

  		if (tot_pages < 0)

  			return -EINVAL;

  	}

  	return tot_pages * sizeof(struct scatterlist);

  }
  
  /*

   * The application asks for a RDMA transfer.
   * Extract all arguments and set up the rdma_op

   */

  int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
  			  struct cmsghdr *cmsg)

  {

  	struct rds_rdma_args *args;

  	struct rm_rdma_op *op = &rm->rdma;

  	int nr_pages;

  	unsigned int nr_bytes;
  	struct page **pages = NULL;

  	struct rds_iovec iovstack[UIO_FASTIOV], *iovs = iovstack;
  	int iov_size;

  	unsigned int i, j;

  	int ret = 0;

  	if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct rds_rdma_args))

  	    || rm->rdma.op_active)

  		return -EINVAL;
  
  	args = CMSG_DATA(cmsg);

  
  	if (rs->rs_bound_addr == 0) {
  		ret = -ENOTCONN; /* XXX not a great errno */

  		goto out_ret;

  	}

  	if (args->nr_local > UIO_MAXIOV) {

  		ret = -EMSGSIZE;

  		goto out_ret;

  	}

  	/* Check whether to allocate the iovec area */
  	iov_size = args->nr_local * sizeof(struct rds_iovec);
  	if (args->nr_local > UIO_FASTIOV) {
  		iovs = sock_kmalloc(rds_rs_to_sk(rs), iov_size, GFP_KERNEL);
  		if (!iovs) {
  			ret = -ENOMEM;

  			goto out_ret;

  		}
  	}
  
  	if (copy_from_user(iovs, (struct rds_iovec __user *)(unsigned long) args->local_vec_addr, iov_size)) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  	nr_pages = rds_rdma_pages(iovs, args->nr_local);

  	if (nr_pages < 0) {
  		ret = -EINVAL;

  		goto out;

  	}

  	pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
  	if (!pages) {

  		ret = -ENOMEM;
  		goto out;
  	}

  	op->op_write = !!(args->flags & RDS_RDMA_READWRITE);
  	op->op_fence = !!(args->flags & RDS_RDMA_FENCE);
  	op->op_notify = !!(args->flags & RDS_RDMA_NOTIFY_ME);

  	op->op_silent = !!(args->flags & RDS_RDMA_SILENT);

  	op->op_active = 1;
  	op->op_recverr = rs->rs_recverr;

  	WARN_ON(!nr_pages);

  	op->op_sg = rds_message_alloc_sgs(rm, nr_pages);

  	if (!op->op_sg) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	if (op->op_notify || op->op_recverr) {

  		/* We allocate an uninitialized notifier here, because
  		 * we don't want to do that in the completion handler. We
  		 * would have to use GFP_ATOMIC there, and don't want to deal
  		 * with failed allocations.
  		 */

  		op->op_notifier = kmalloc(sizeof(struct rds_notifier), GFP_KERNEL);
  		if (!op->op_notifier) {

  			ret = -ENOMEM;
  			goto out;
  		}

  		op->op_notifier->n_user_token = args->user_token;
  		op->op_notifier->n_status = RDS_RDMA_SUCCESS;

  	}
  
  	/* The cookie contains the R_Key of the remote memory region, and
  	 * optionally an offset into it. This is how we implement RDMA into
  	 * unaligned memory.
  	 * When setting up the RDMA, we need to add that offset to the
  	 * destination address (which is really an offset into the MR)
  	 * FIXME: We may want to move this into ib_rdma.c
  	 */

  	op->op_rkey = rds_rdma_cookie_key(args->cookie);
  	op->op_remote_addr = args->remote_vec.addr + rds_rdma_cookie_offset(args->cookie);

  
  	nr_bytes = 0;
  
  	rdsdebug("RDS: rdma prepare nr_local %llu rva %llx rkey %x
  ",
  	       (unsigned long long)args->nr_local,
  	       (unsigned long long)args->remote_vec.addr,

  	       op->op_rkey);

  
  	for (i = 0; i < args->nr_local; i++) {

  		struct rds_iovec *iov = &iovs[i];
  		/* don't need to check, rds_rdma_pages() verified nr will be +nonzero */
  		unsigned int nr = rds_pages_in_vec(iov);

  		rs->rs_user_addr = iov->addr;
  		rs->rs_user_bytes = iov->bytes;

  		/* If it's a WRITE operation, we want to pin the pages for reading.
  		 * If it's a READ operation, we need to pin the pages for writing.
  		 */

  		ret = rds_pin_pages(iov->addr, nr, pages, !op->op_write);

  		if (ret < 0)
  			goto out;

  		rdsdebug("RDS: nr_bytes %u nr %u iov->bytes %llu iov->addr %llx
  ",
  			 nr_bytes, nr, iov->bytes, iov->addr);

  		nr_bytes += iov->bytes;

  
  		for (j = 0; j < nr; j++) {

  			unsigned int offset = iov->addr & ~PAGE_MASK;

  			struct scatterlist *sg;

  			sg = &op->op_sg[op->op_nents + j];

  			sg_set_page(sg, pages[j],

  					min_t(unsigned int, iov->bytes, PAGE_SIZE - offset),

  					offset);

  			rdsdebug("RDS: sg->offset %x sg->len %x iov->addr %llx iov->bytes %llu
  ",
  			       sg->offset, sg->length, iov->addr, iov->bytes);

  			iov->addr += sg->length;
  			iov->bytes -= sg->length;

  		}

  		op->op_nents += nr;

  	}

  	if (nr_bytes > args->remote_vec.bytes) {
  		rdsdebug("RDS nr_bytes %u remote_bytes %u do not match
  ",
  				nr_bytes,
  				(unsigned int) args->remote_vec.bytes);
  		ret = -EINVAL;
  		goto out;
  	}

  	op->op_bytes = nr_bytes;

  out:

  	if (iovs != iovstack)
  		sock_kfree_s(rds_rs_to_sk(rs), iovs, iov_size);

  	kfree(pages);

  out_ret:

  	if (ret)
  		rds_rdma_free_op(op);

  	else
  		rds_stats_inc(s_send_rdma);

  
  	return ret;

  }
  
  /*
   * The application wants us to pass an RDMA destination (aka MR)
   * to the remote
   */
  int rds_cmsg_rdma_dest(struct rds_sock *rs, struct rds_message *rm,
  			  struct cmsghdr *cmsg)
  {
  	unsigned long flags;
  	struct rds_mr *mr;
  	u32 r_key;
  	int err = 0;

  	if (cmsg->cmsg_len < CMSG_LEN(sizeof(rds_rdma_cookie_t)) ||
  	    rm->m_rdma_cookie != 0)

  		return -EINVAL;
  
  	memcpy(&rm->m_rdma_cookie, CMSG_DATA(cmsg), sizeof(rm->m_rdma_cookie));
  
  	/* We are reusing a previously mapped MR here. Most likely, the
  	 * application has written to the buffer, so we need to explicitly
  	 * flush those writes to RAM. Otherwise the HCA may not see them
  	 * when doing a DMA from that buffer.
  	 */
  	r_key = rds_rdma_cookie_key(rm->m_rdma_cookie);
  
  	spin_lock_irqsave(&rs->rs_rdma_lock, flags);
  	mr = rds_mr_tree_walk(&rs->rs_rdma_keys, r_key, NULL);

  	if (!mr)

  		err = -EINVAL;	/* invalid r_key */
  	else
  		atomic_inc(&mr->r_refcount);
  	spin_unlock_irqrestore(&rs->rs_rdma_lock, flags);
  
  	if (mr) {
  		mr->r_trans->sync_mr(mr->r_trans_private, DMA_TO_DEVICE);

  		rm->rdma.op_rdma_mr = mr;

  	}
  	return err;
  }
  
  /*
   * The application passes us an address range it wants to enable RDMA
   * to/from. We map the area, and save the <R_Key,offset> pair
   * in rm->m_rdma_cookie. This causes it to be sent along to the peer
   * in an extension header.
   */
  int rds_cmsg_rdma_map(struct rds_sock *rs, struct rds_message *rm,
  			  struct cmsghdr *cmsg)
  {

  	if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct rds_get_mr_args)) ||
  	    rm->m_rdma_cookie != 0)

  		return -EINVAL;

  	return __rds_rdma_map(rs, CMSG_DATA(cmsg), &rm->m_rdma_cookie, &rm->rdma.op_rdma_mr);

  }

  
  /*
   * Fill in rds_message for an atomic request.
   */
  int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
  		    struct cmsghdr *cmsg)
  {
  	struct page *page = NULL;
  	struct rds_atomic_args *args;
  	int ret = 0;
  
  	if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct rds_atomic_args))
  	 || rm->atomic.op_active)
  		return -EINVAL;
  
  	args = CMSG_DATA(cmsg);

  	/* Nonmasked & masked cmsg ops converted to masked hw ops */
  	switch (cmsg->cmsg_type) {
  	case RDS_CMSG_ATOMIC_FADD:
  		rm->atomic.op_type = RDS_ATOMIC_TYPE_FADD;
  		rm->atomic.op_m_fadd.add = args->fadd.add;
  		rm->atomic.op_m_fadd.nocarry_mask = 0;
  		break;
  	case RDS_CMSG_MASKED_ATOMIC_FADD:

  		rm->atomic.op_type = RDS_ATOMIC_TYPE_FADD;

  		rm->atomic.op_m_fadd.add = args->m_fadd.add;
  		rm->atomic.op_m_fadd.nocarry_mask = args->m_fadd.nocarry_mask;
  		break;
  	case RDS_CMSG_ATOMIC_CSWP:
  		rm->atomic.op_type = RDS_ATOMIC_TYPE_CSWP;
  		rm->atomic.op_m_cswp.compare = args->cswp.compare;
  		rm->atomic.op_m_cswp.swap = args->cswp.swap;
  		rm->atomic.op_m_cswp.compare_mask = ~0;
  		rm->atomic.op_m_cswp.swap_mask = ~0;
  		break;
  	case RDS_CMSG_MASKED_ATOMIC_CSWP:
  		rm->atomic.op_type = RDS_ATOMIC_TYPE_CSWP;
  		rm->atomic.op_m_cswp.compare = args->m_cswp.compare;
  		rm->atomic.op_m_cswp.swap = args->m_cswp.swap;
  		rm->atomic.op_m_cswp.compare_mask = args->m_cswp.compare_mask;
  		rm->atomic.op_m_cswp.swap_mask = args->m_cswp.swap_mask;
  		break;
  	default:
  		BUG(); /* should never happen */

  	}

  	rm->atomic.op_notify = !!(args->flags & RDS_RDMA_NOTIFY_ME);

  	rm->atomic.op_silent = !!(args->flags & RDS_RDMA_SILENT);

  	rm->atomic.op_active = 1;

  	rm->atomic.op_recverr = rs->rs_recverr;
  	rm->atomic.op_sg = rds_message_alloc_sgs(rm, 1);

  	if (!rm->atomic.op_sg) {
  		ret = -ENOMEM;
  		goto err;
  	}

  
  	/* verify 8 byte-aligned */
  	if (args->local_addr & 0x7) {
  		ret = -EFAULT;
  		goto err;
  	}
  
  	ret = rds_pin_pages(args->local_addr, 1, &page, 1);
  	if (ret != 1)
  		goto err;
  	ret = 0;
  
  	sg_set_page(rm->atomic.op_sg, page, 8, offset_in_page(args->local_addr));
  
  	if (rm->atomic.op_notify || rm->atomic.op_recverr) {
  		/* We allocate an uninitialized notifier here, because
  		 * we don't want to do that in the completion handler. We
  		 * would have to use GFP_ATOMIC there, and don't want to deal
  		 * with failed allocations.
  		 */
  		rm->atomic.op_notifier = kmalloc(sizeof(*rm->atomic.op_notifier), GFP_KERNEL);
  		if (!rm->atomic.op_notifier) {
  			ret = -ENOMEM;
  			goto err;
  		}
  
  		rm->atomic.op_notifier->n_user_token = args->user_token;
  		rm->atomic.op_notifier->n_status = RDS_RDMA_SUCCESS;
  	}

  	rm->atomic.op_rkey = rds_rdma_cookie_key(args->cookie);

  	rm->atomic.op_remote_addr = args->remote_addr + rds_rdma_cookie_offset(args->cookie);

  	return ret;
  err:
  	if (page)
  		put_page(page);
  	kfree(rm->atomic.op_notifier);
  
  	return ret;
  }