trans_rdma.c

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/*
 * linux/fs/9p/trans_rdma.c
 *
 * RDMA transport layer based on the trans_fd.c implementation.
 *
 *  Copyright (C) 2008 by Tom Tucker <[email protected]>
 *  Copyright (C) 2006 by Russ Cox <[email protected]>
 *  Copyright (C) 2004-2005 by Latchesar Ionkov <[email protected]>
 *  Copyright (C) 2004-2008 by Eric Van Hensbergen <[email protected]>
 *  Copyright (C) 1997-2002 by Ron Minnich <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/in.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/ipv6.h>
#include <linux/kthread.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/un.h>
#include <linux/uaccess.h>
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/file.h>
#include <linux/parser.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>

#define P9_PORT         5640
#define P9_RDMA_SQ_DEPTH    32
#define P9_RDMA_RQ_DEPTH    32
#define P9_RDMA_SEND_SGE    4
#define P9_RDMA_RECV_SGE    4
#define P9_RDMA_IRD     0
#define P9_RDMA_ORD     0
#define P9_RDMA_TIMEOUT     30000       /* 30 seconds */
#define P9_RDMA_MAXSIZE     (4*4096)    /* Min SGE is 4, so we can
                         * safely advertise a maxsize
                         * of 64k */

struct p9_trans_rdma {
    enum {
        P9_RDMA_INIT,
        P9_RDMA_ADDR_RESOLVED,
        P9_RDMA_ROUTE_RESOLVED,
        P9_RDMA_CONNECTED,
        P9_RDMA_FLUSHING,
        P9_RDMA_CLOSING,
        P9_RDMA_CLOSED,
    } state;
    struct rdma_cm_id *cm_id;
    struct ib_pd *pd;
    struct ib_qp *qp;
    struct ib_cq *cq;
    struct ib_mr *dma_mr;
    u32 lkey;
    long timeout;
    int sq_depth;
    struct semaphore sq_sem;
    int rq_depth;
    atomic_t rq_count;
    struct sockaddr_in addr;
    spinlock_t req_lock;

    struct completion cm_done;
};

struct p9_rdma_req;
struct p9_rdma_context {
    enum ib_wc_opcode wc_op;
    dma_addr_t busa;
    union {
        struct p9_req_t *req;
        struct p9_fcall *rc;
    };
};

struct p9_rdma_opts {
    short port;
    int sq_depth;
    int rq_depth;
    long timeout;
};

/*
 * Option Parsing (code inspired by NFS code)
 */
enum {
    /* Options that take integer arguments */
    Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout, Opt_err,
};

static match_table_t tokens = {
    {Opt_port, "port=%u"},
    {Opt_sq_depth, "sq=%u"},
    {Opt_rq_depth, "rq=%u"},
    {Opt_timeout, "timeout=%u"},
    {Opt_err, NULL},
};

static int parse_opts(char *params, struct p9_rdma_opts *opts)
{
    char *p;
    substring_t args[MAX_OPT_ARGS];
    int option;
    char *options, *tmp_options;

    opts->port = P9_PORT;
    opts->sq_depth = P9_RDMA_SQ_DEPTH;
    opts->rq_depth = P9_RDMA_RQ_DEPTH;
    opts->timeout = P9_RDMA_TIMEOUT;

    if (!params)
        return 0;

    tmp_options = kstrdup(params, GFP_KERNEL);
    if (!tmp_options) {
        p9_debug(P9_DEBUG_ERROR,
             "failed to allocate copy of option string\n");
        return -ENOMEM;
    }
    options = tmp_options;

    while ((p = strsep(&options, ",")) != NULL) {
        int token;
        int r;
        if (!*p)
            continue;
        token = match_token(p, tokens, args);
        r = match_int(&args[0], &option);
        if (r < 0) {
            p9_debug(P9_DEBUG_ERROR,
                 "integer field, but no integer?\n");
            continue;
        }
        switch (token) {
        case Opt_port:
            opts->port = option;
            break;
        case Opt_sq_depth:
            opts->sq_depth = option;
            break;
        case Opt_rq_depth:
            opts->rq_depth = option;
            break;
        case Opt_timeout:
            opts->timeout = option;
            break;
        default:
            continue;
        }
    }
    /* RQ must be at least as large as the SQ */
    opts->rq_depth = max(opts->rq_depth, opts->sq_depth);
    kfree(tmp_options);
    return 0;
}

static int
p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
{
    struct p9_client *c = id->context;
    struct p9_trans_rdma *rdma = c->trans;
    switch (event->event) {
    case RDMA_CM_EVENT_ADDR_RESOLVED:
        BUG_ON(rdma->state != P9_RDMA_INIT);
        rdma->state = P9_RDMA_ADDR_RESOLVED;
        break;

    case RDMA_CM_EVENT_ROUTE_RESOLVED:
        BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED);
        rdma->state = P9_RDMA_ROUTE_RESOLVED;
        break;

    case RDMA_CM_EVENT_ESTABLISHED:
        BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED);
        rdma->state = P9_RDMA_CONNECTED;
        break;

    case RDMA_CM_EVENT_DISCONNECTED:
        if (rdma)
            rdma->state = P9_RDMA_CLOSED;
        if (c)
            c->status = Disconnected;
        break;

    case RDMA_CM_EVENT_TIMEWAIT_EXIT:
        break;

    case RDMA_CM_EVENT_ADDR_CHANGE:
    case RDMA_CM_EVENT_ROUTE_ERROR:
    case RDMA_CM_EVENT_DEVICE_REMOVAL:
    case RDMA_CM_EVENT_MULTICAST_JOIN:
    case RDMA_CM_EVENT_MULTICAST_ERROR:
    case RDMA_CM_EVENT_REJECTED:
    case RDMA_CM_EVENT_CONNECT_REQUEST:
    case RDMA_CM_EVENT_CONNECT_RESPONSE:
    case RDMA_CM_EVENT_CONNECT_ERROR:
    case RDMA_CM_EVENT_ADDR_ERROR:
    case RDMA_CM_EVENT_UNREACHABLE:
        c->status = Disconnected;
        rdma_disconnect(rdma->cm_id);
        break;
    default:
        BUG();
    }
    complete(&rdma->cm_done);
    return 0;
}

static void
handle_recv(struct p9_client *client, struct p9_trans_rdma *rdma,
        struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
{
    struct p9_req_t *req;
    int err = 0;
    int16_t tag;

    req = NULL;
    ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize,
                             DMA_FROM_DEVICE);

    if (status != IB_WC_SUCCESS)
        goto err_out;

    err = p9_parse_header(c->rc, NULL, NULL, &tag, 1);
    if (err)
        goto err_out;

    req = p9_tag_lookup(client, tag);
    if (!req)
        goto err_out;

    req->rc = c->rc;
    req->status = REQ_STATUS_RCVD;
    p9_client_cb(client, req);

    return;

 err_out:
    p9_debug(P9_DEBUG_ERROR, "req %p err %d status %d\n", req, err, status);
    rdma->state = P9_RDMA_FLUSHING;
    client->status = Disconnected;
}

static void
handle_send(struct p9_client *client, struct p9_trans_rdma *rdma,
        struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
{
    ib_dma_unmap_single(rdma->cm_id->device,
                c->busa, c->req->tc->size,
                DMA_TO_DEVICE);
}

static void qp_event_handler(struct ib_event *event, void *context)
{
    p9_debug(P9_DEBUG_ERROR, "QP event %d context %p\n",
         event->event, context);
}

static void cq_comp_handler(struct ib_cq *cq, void *cq_context)
{
    struct p9_client *client = cq_context;
    struct p9_trans_rdma *rdma = client->trans;
    int ret;
    struct ib_wc wc;

    ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
    while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
        struct p9_rdma_context *c = (void *) (unsigned long) wc.wr_id;

        switch (c->wc_op) {
        case IB_WC_RECV:
            atomic_dec(&rdma->rq_count);
            handle_recv(client, rdma, c, wc.status, wc.byte_len);
            break;

        case IB_WC_SEND:
            handle_send(client, rdma, c, wc.status, wc.byte_len);
            up(&rdma->sq_sem);
            break;

        default:
            pr_err("unexpected completion type, c->wc_op=%d, wc.opcode=%d, status=%d\n",
                   c->wc_op, wc.opcode, wc.status);
            break;
        }
        kfree(c);
    }
}

static void cq_event_handler(struct ib_event *e, void *v)
{
    p9_debug(P9_DEBUG_ERROR, "CQ event %d context %p\n", e->event, v);
}

static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
{
    if (!rdma)
        return;

    if (rdma->dma_mr && !IS_ERR(rdma->dma_mr))
        ib_dereg_mr(rdma->dma_mr);

    if (rdma->qp && !IS_ERR(rdma->qp))
        ib_destroy_qp(rdma->qp);

    if (rdma->pd && !IS_ERR(rdma->pd))
        ib_dealloc_pd(rdma->pd);

    if (rdma->cq && !IS_ERR(rdma->cq))
        ib_destroy_cq(rdma->cq);

    if (rdma->cm_id && !IS_ERR(rdma->cm_id))
        rdma_destroy_id(rdma->cm_id);

    kfree(rdma);
}

static int
post_recv(struct p9_client *client, struct p9_rdma_context *c)
{
    struct p9_trans_rdma *rdma = client->trans;
    struct ib_recv_wr wr, *bad_wr;
    struct ib_sge sge;

    c->busa = ib_dma_map_single(rdma->cm_id->device,
                    c->rc->sdata, client->msize,
                    DMA_FROM_DEVICE);
    if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
        goto error;

    sge.addr = c->busa;
    sge.length = client->msize;
    sge.lkey = rdma->lkey;

    wr.next = NULL;
    c->wc_op = IB_WC_RECV;
    wr.wr_id = (unsigned long) c;
    wr.sg_list = &sge;
    wr.num_sge = 1;
    return ib_post_recv(rdma->qp, &wr, &bad_wr);

 error:
    p9_debug(P9_DEBUG_ERROR, "EIO\n");
    return -EIO;
}

static int rdma_request(struct p9_client *client, struct p9_req_t *req)
{
    struct p9_trans_rdma *rdma = client->trans;
    struct ib_send_wr wr, *bad_wr;
    struct ib_sge sge;
    int err = 0;
    unsigned long flags;
    struct p9_rdma_context *c = NULL;
    struct p9_rdma_context *rpl_context = NULL;

    /* Allocate an fcall for the reply */
    rpl_context = kmalloc(sizeof *rpl_context, GFP_NOFS);
    if (!rpl_context) {
        err = -ENOMEM;
        goto err_close;
    }

    /*
     * If the request has a buffer, steal it, otherwise
     * allocate a new one.  Typically, requests should already
     * have receive buffers allocated and just swap them around
     */
    if (!req->rc) {
        req->rc = kmalloc(sizeof(struct p9_fcall)+client->msize,
                  GFP_NOFS);
        if (req->rc) {
            req->rc->sdata = (char *) req->rc +
                        sizeof(struct p9_fcall);
            req->rc->capacity = client->msize;
        }
    }
    rpl_context->rc = req->rc;
    if (!rpl_context->rc) {
        err = -ENOMEM;
        goto err_free2;
    }

    /*
     * Post a receive buffer for this request. We need to ensure
     * there is a reply buffer available for every outstanding
     * request. A flushed request can result in no reply for an
     * outstanding request, so we must keep a count to avoid
     * overflowing the RQ.
     */
    if (atomic_inc_return(&rdma->rq_count) <= rdma->rq_depth) {
        err = post_recv(client, rpl_context);
        if (err)
            goto err_free1;
    } else
        atomic_dec(&rdma->rq_count);

    /* remove posted receive buffer from request structure */
    req->rc = NULL;

    /* Post the request */
    c = kmalloc(sizeof *c, GFP_NOFS);
    if (!c) {
        err = -ENOMEM;
        goto err_free1;
    }
    c->req = req;

    c->busa = ib_dma_map_single(rdma->cm_id->device,
                    c->req->tc->sdata, c->req->tc->size,
                    DMA_TO_DEVICE);
    if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
        goto error;

    sge.addr = c->busa;
    sge.length = c->req->tc->size;
    sge.lkey = rdma->lkey;

    wr.next = NULL;
    c->wc_op = IB_WC_SEND;
    wr.wr_id = (unsigned long) c;
    wr.opcode = IB_WR_SEND;
    wr.send_flags = IB_SEND_SIGNALED;
    wr.sg_list = &sge;
    wr.num_sge = 1;

    if (down_interruptible(&rdma->sq_sem))
        goto error;

    return ib_post_send(rdma->qp, &wr, &bad_wr);

 error:
    kfree(c);
    kfree(rpl_context->rc);
    kfree(rpl_context);
    p9_debug(P9_DEBUG_ERROR, "EIO\n");
    return -EIO;
 err_free1:
    kfree(rpl_context->rc);
 err_free2:
    kfree(rpl_context);
 err_close:
    spin_lock_irqsave(&rdma->req_lock, flags);
    if (rdma->state < P9_RDMA_CLOSING) {
        rdma->state = P9_RDMA_CLOSING;
        spin_unlock_irqrestore(&rdma->req_lock, flags);
        rdma_disconnect(rdma->cm_id);
    } else
        spin_unlock_irqrestore(&rdma->req_lock, flags);
    return err;
}

static void rdma_close(struct p9_client *client)
{
    struct p9_trans_rdma *rdma;

    if (!client)
        return;

    rdma = client->trans;
    if (!rdma)
        return;

    client->status = Disconnected;
    rdma_disconnect(rdma->cm_id);
    rdma_destroy_trans(rdma);
}

static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts)
{
    struct p9_trans_rdma *rdma;

    rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL);
    if (!rdma)
        return NULL;

    rdma->sq_depth = opts->sq_depth;
    rdma->rq_depth = opts->rq_depth;
    rdma->timeout = opts->timeout;
    spin_lock_init(&rdma->req_lock);
    init_completion(&rdma->cm_done);
    sema_init(&rdma->sq_sem, rdma->sq_depth);
    atomic_set(&rdma->rq_count, 0);

    return rdma;
}

/* its not clear to me we can do anything after send has been posted */
static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
{
    return 1;
}

static int
rdma_create_trans(struct p9_client *client, const char *addr, char *args)
{
    int err;
    struct p9_rdma_opts opts;
    struct p9_trans_rdma *rdma;
    struct rdma_conn_param conn_param;
    struct ib_qp_init_attr qp_attr;
    struct ib_device_attr devattr;

    /* Parse the transport specific mount options */
    err = parse_opts(args, &opts);
    if (err < 0)
        return err;

    /* Create and initialize the RDMA transport structure */
    rdma = alloc_rdma(&opts);
    if (!rdma)
        return -ENOMEM;

    /* Create the RDMA CM ID */
    rdma->cm_id = rdma_create_id(p9_cm_event_handler, client, RDMA_PS_TCP,
                     IB_QPT_RC);
    if (IS_ERR(rdma->cm_id))
        goto error;

    /* Associate the client with the transport */
    client->trans = rdma;

    /* Resolve the server's address */
    rdma->addr.sin_family = AF_INET;
    rdma->addr.sin_addr.s_addr = in_aton(addr);
    rdma->addr.sin_port = htons(opts.port);
    err = rdma_resolve_addr(rdma->cm_id, NULL,
                (struct sockaddr *)&rdma->addr,
                rdma->timeout);
    if (err)
        goto error;
    err = wait_for_completion_interruptible(&rdma->cm_done);
    if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED))
        goto error;

    /* Resolve the route to the server */
    err = rdma_resolve_route(rdma->cm_id, rdma->timeout);
    if (err)
        goto error;
    err = wait_for_completion_interruptible(&rdma->cm_done);
    if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED))
        goto error;

    /* Query the device attributes */
    err = ib_query_device(rdma->cm_id->device, &devattr);
    if (err)
        goto error;

    /* Create the Completion Queue */
    rdma->cq = ib_create_cq(rdma->cm_id->device, cq_comp_handler,
                cq_event_handler, client,
                opts.sq_depth + opts.rq_depth + 1, 0);
    if (IS_ERR(rdma->cq))
        goto error;
    ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);

    /* Create the Protection Domain */
    rdma->pd = ib_alloc_pd(rdma->cm_id->device);
    if (IS_ERR(rdma->pd))
        goto error;

    /* Cache the DMA lkey in the transport */
    rdma->dma_mr = NULL;
    if (devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
        rdma->lkey = rdma->cm_id->device->local_dma_lkey;
    else {
        rdma->dma_mr = ib_get_dma_mr(rdma->pd, IB_ACCESS_LOCAL_WRITE);
        if (IS_ERR(rdma->dma_mr))
            goto error;
        rdma->lkey = rdma->dma_mr->lkey;
    }

    /* Create the Queue Pair */
    memset(&qp_attr, 0, sizeof qp_attr);
    qp_attr.event_handler = qp_event_handler;
    qp_attr.qp_context = client;
    qp_attr.cap.max_send_wr = opts.sq_depth;
    qp_attr.cap.max_recv_wr = opts.rq_depth;
    qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE;
    qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE;
    qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
    qp_attr.qp_type = IB_QPT_RC;
    qp_attr.send_cq = rdma->cq;
    qp_attr.recv_cq = rdma->cq;
    err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr);
    if (err)
        goto error;
    rdma->qp = rdma->cm_id->qp;

    /* Request a connection */
    memset(&conn_param, 0, sizeof(conn_param));
    conn_param.private_data = NULL;
    conn_param.private_data_len = 0;
    conn_param.responder_resources = P9_RDMA_IRD;
    conn_param.initiator_depth = P9_RDMA_ORD;
    err = rdma_connect(rdma->cm_id, &conn_param);
    if (err)
        goto error;
    err = wait_for_completion_interruptible(&rdma->cm_done);
    if (err || (rdma->state != P9_RDMA_CONNECTED))
        goto error;

    client->status = Connected;

    return 0;

error:
    rdma_destroy_trans(rdma);
    return -ENOTCONN;
}

static struct p9_trans_module p9_rdma_trans = {
    .name = "rdma",
    .maxsize = P9_RDMA_MAXSIZE,
    .def = 0,
    .owner = THIS_MODULE,
    .create = rdma_create_trans,
    .close = rdma_close,
    .request = rdma_request,
    .cancel = rdma_cancel,
};

static int __init p9_trans_rdma_init(void)
{
    v9fs_register_trans(&p9_rdma_trans);
    return 0;
}

static void __exit p9_trans_rdma_exit(void)
{
    v9fs_unregister_trans(&p9_rdma_trans);
}

module_init(p9_trans_rdma_init);
module_exit(p9_trans_rdma_exit);

MODULE_AUTHOR("Tom Tucker <[email protected]>");
MODULE_DESCRIPTION("RDMA Transport for 9P");
MODULE_LICENSE("Dual BSD/GPL");