rdma.c

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/*
 * 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\n",
            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\n",
        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\n", 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\n",
           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\n", 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!\n", 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;
    }

    if (args->nr_local > UIO_MAXIOV) {
        ret = -EMSGSIZE;
        goto out;
    }

    /* 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;
        }
    }

    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\n",
           (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\n",
             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\n",
                   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\n",
                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);
    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;
}