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svcrdma: Introduce local rdma_rw API helpers

The plan is to replace the local bespoke code that constructs and
posts RDMA Read and Write Work Requests with calls to the rdma_rw
API. This shares code with other RDMA-enabled ULPs that manages the
gory details of buffer registration and posting Work Requests.

Some design notes:

 o The structure of RPC-over-RDMA transport headers is flexible,
   allowing multiple segments per Reply with arbitrary alignment,
   each with a unique R_key. Write and Send WRs continue to be
   built and posted in separate code paths. However, one whole
   chunk (with one or more RDMA segments apiece) gets exactly
   one ib_post_send and one work completion.

 o svc_xprt reference counting is modified, since a chain of
   rdma_rw_ctx structs generates one completion, no matter how
   many Write WRs are posted.

 o The current code builds the transport header as it is construct-
   ing Write WRs. I've replaced that with marshaling of transport
   header data items in a separate step. This is because the exact
   structure of client-provided segments may not align with the
   components of the server's reply xdr_buf, or the pages in the
   page list. Thus parts of each client-provided segment may be
   written at different points in the send path.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
zero-colors
Chuck Lever 2017-04-09 13:06:16 -04:00 committed by J. Bruce Fields
parent c238c4c034
commit f13193f50b
5 changed files with 529 additions and 1 deletions

View File

@ -145,12 +145,15 @@ struct svcxprt_rdma {
u32 sc_max_requests; /* Max requests */ u32 sc_max_requests; /* Max requests */
u32 sc_max_bc_requests;/* Backward credits */ u32 sc_max_bc_requests;/* Backward credits */
int sc_max_req_size; /* Size of each RQ WR buf */ int sc_max_req_size; /* Size of each RQ WR buf */
u8 sc_port_num;
struct ib_pd *sc_pd; struct ib_pd *sc_pd;
spinlock_t sc_ctxt_lock; spinlock_t sc_ctxt_lock;
struct list_head sc_ctxts; struct list_head sc_ctxts;
int sc_ctxt_used; int sc_ctxt_used;
spinlock_t sc_rw_ctxt_lock;
struct list_head sc_rw_ctxts;
spinlock_t sc_map_lock; spinlock_t sc_map_lock;
struct list_head sc_maps; struct list_head sc_maps;
@ -224,6 +227,14 @@ extern int rdma_read_chunk_frmr(struct svcxprt_rdma *, struct svc_rqst *,
struct svc_rdma_op_ctxt *, int *, u32 *, struct svc_rdma_op_ctxt *, int *, u32 *,
u32, u32, u64, bool); u32, u32, u64, bool);
/* svc_rdma_rw.c */
extern void svc_rdma_destroy_rw_ctxts(struct svcxprt_rdma *rdma);
extern int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma,
__be32 *wr_ch, struct xdr_buf *xdr);
extern int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma,
__be32 *rp_ch, bool writelist,
struct xdr_buf *xdr);
/* svc_rdma_sendto.c */ /* svc_rdma_sendto.c */
extern int svc_rdma_map_xdr(struct svcxprt_rdma *, struct xdr_buf *, extern int svc_rdma_map_xdr(struct svcxprt_rdma *, struct xdr_buf *,
struct svc_rdma_req_map *, bool); struct svc_rdma_req_map *, bool);

View File

@ -52,6 +52,7 @@ config SUNRPC_XPRT_RDMA
tristate "RPC-over-RDMA transport" tristate "RPC-over-RDMA transport"
depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS
default SUNRPC && INFINIBAND default SUNRPC && INFINIBAND
select SG_POOL
help help
This option allows the NFS client and server to use RDMA This option allows the NFS client and server to use RDMA
transports (InfiniBand, iWARP, or RoCE). transports (InfiniBand, iWARP, or RoCE).

View File

@ -4,5 +4,5 @@ rpcrdma-y := transport.o rpc_rdma.o verbs.o \
fmr_ops.o frwr_ops.o \ fmr_ops.o frwr_ops.o \
svc_rdma.o svc_rdma_backchannel.o svc_rdma_transport.o \ svc_rdma.o svc_rdma_backchannel.o svc_rdma_transport.o \
svc_rdma_marshal.o svc_rdma_sendto.o svc_rdma_recvfrom.o \ svc_rdma_marshal.o svc_rdma_sendto.o svc_rdma_recvfrom.o \
module.o svc_rdma_rw.o module.o
rpcrdma-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel.o rpcrdma-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel.o

View File

@ -0,0 +1,512 @@
/*
* Copyright (c) 2016 Oracle. All rights reserved.
*
* Use the core R/W API to move RPC-over-RDMA Read and Write chunks.
*/
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>
#include <linux/sunrpc/debug.h>
#include <rdma/rw.h>
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
/* Each R/W context contains state for one chain of RDMA Read or
* Write Work Requests.
*
* Each WR chain handles a single contiguous server-side buffer,
* because scatterlist entries after the first have to start on
* page alignment. xdr_buf iovecs cannot guarantee alignment.
*
* Each WR chain handles only one R_key. Each RPC-over-RDMA segment
* from a client may contain a unique R_key, so each WR chain moves
* up to one segment at a time.
*
* The scatterlist makes this data structure over 4KB in size. To
* make it less likely to fail, and to handle the allocation for
* smaller I/O requests without disabling bottom-halves, these
* contexts are created on demand, but cached and reused until the
* controlling svcxprt_rdma is destroyed.
*/
struct svc_rdma_rw_ctxt {
struct list_head rw_list;
struct rdma_rw_ctx rw_ctx;
int rw_nents;
struct sg_table rw_sg_table;
struct scatterlist rw_first_sgl[0];
};
static inline struct svc_rdma_rw_ctxt *
svc_rdma_next_ctxt(struct list_head *list)
{
return list_first_entry_or_null(list, struct svc_rdma_rw_ctxt,
rw_list);
}
static struct svc_rdma_rw_ctxt *
svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
{
struct svc_rdma_rw_ctxt *ctxt;
spin_lock(&rdma->sc_rw_ctxt_lock);
ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts);
if (ctxt) {
list_del(&ctxt->rw_list);
spin_unlock(&rdma->sc_rw_ctxt_lock);
} else {
spin_unlock(&rdma->sc_rw_ctxt_lock);
ctxt = kmalloc(sizeof(*ctxt) +
SG_CHUNK_SIZE * sizeof(struct scatterlist),
GFP_KERNEL);
if (!ctxt)
goto out;
INIT_LIST_HEAD(&ctxt->rw_list);
}
ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl;
if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges,
ctxt->rw_sg_table.sgl)) {
kfree(ctxt);
ctxt = NULL;
}
out:
return ctxt;
}
static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
struct svc_rdma_rw_ctxt *ctxt)
{
sg_free_table_chained(&ctxt->rw_sg_table, true);
spin_lock(&rdma->sc_rw_ctxt_lock);
list_add(&ctxt->rw_list, &rdma->sc_rw_ctxts);
spin_unlock(&rdma->sc_rw_ctxt_lock);
}
/**
* svc_rdma_destroy_rw_ctxts - Free accumulated R/W contexts
* @rdma: transport about to be destroyed
*
*/
void svc_rdma_destroy_rw_ctxts(struct svcxprt_rdma *rdma)
{
struct svc_rdma_rw_ctxt *ctxt;
while ((ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts)) != NULL) {
list_del(&ctxt->rw_list);
kfree(ctxt);
}
}
/* A chunk context tracks all I/O for moving one Read or Write
* chunk. This is a a set of rdma_rw's that handle data movement
* for all segments of one chunk.
*
* These are small, acquired with a single allocator call, and
* no more than one is needed per chunk. They are allocated on
* demand, and not cached.
*/
struct svc_rdma_chunk_ctxt {
struct ib_cqe cc_cqe;
struct svcxprt_rdma *cc_rdma;
struct list_head cc_rwctxts;
int cc_sqecount;
enum dma_data_direction cc_dir;
};
static void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
struct svc_rdma_chunk_ctxt *cc,
enum dma_data_direction dir)
{
cc->cc_rdma = rdma;
svc_xprt_get(&rdma->sc_xprt);
INIT_LIST_HEAD(&cc->cc_rwctxts);
cc->cc_sqecount = 0;
cc->cc_dir = dir;
}
static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc)
{
struct svcxprt_rdma *rdma = cc->cc_rdma;
struct svc_rdma_rw_ctxt *ctxt;
while ((ctxt = svc_rdma_next_ctxt(&cc->cc_rwctxts)) != NULL) {
list_del(&ctxt->rw_list);
rdma_rw_ctx_destroy(&ctxt->rw_ctx, rdma->sc_qp,
rdma->sc_port_num, ctxt->rw_sg_table.sgl,
ctxt->rw_nents, cc->cc_dir);
svc_rdma_put_rw_ctxt(rdma, ctxt);
}
svc_xprt_put(&rdma->sc_xprt);
}
/* State for sending a Write or Reply chunk.
* - Tracks progress of writing one chunk over all its segments
* - Stores arguments for the SGL constructor functions
*/
struct svc_rdma_write_info {
/* write state of this chunk */
unsigned int wi_seg_off;
unsigned int wi_seg_no;
unsigned int wi_nsegs;
__be32 *wi_segs;
/* SGL constructor arguments */
struct xdr_buf *wi_xdr;
unsigned char *wi_base;
unsigned int wi_next_off;
struct svc_rdma_chunk_ctxt wi_cc;
};
static struct svc_rdma_write_info *
svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma, __be32 *chunk)
{
struct svc_rdma_write_info *info;
info = kmalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return info;
info->wi_seg_off = 0;
info->wi_seg_no = 0;
info->wi_nsegs = be32_to_cpup(++chunk);
info->wi_segs = ++chunk;
svc_rdma_cc_init(rdma, &info->wi_cc, DMA_TO_DEVICE);
return info;
}
static void svc_rdma_write_info_free(struct svc_rdma_write_info *info)
{
svc_rdma_cc_release(&info->wi_cc);
kfree(info);
}
/**
* svc_rdma_write_done - Write chunk completion
* @cq: controlling Completion Queue
* @wc: Work Completion
*
* Pages under I/O are freed by a subsequent Send completion.
*/
static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc)
{
struct ib_cqe *cqe = wc->wr_cqe;
struct svc_rdma_chunk_ctxt *cc =
container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
struct svcxprt_rdma *rdma = cc->cc_rdma;
struct svc_rdma_write_info *info =
container_of(cc, struct svc_rdma_write_info, wi_cc);
atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
wake_up(&rdma->sc_send_wait);
if (unlikely(wc->status != IB_WC_SUCCESS)) {
set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
if (wc->status != IB_WC_WR_FLUSH_ERR)
pr_err("svcrdma: write ctx: %s (%u/0x%x)\n",
ib_wc_status_msg(wc->status),
wc->status, wc->vendor_err);
}
svc_rdma_write_info_free(info);
}
/* This function sleeps when the transport's Send Queue is congested.
*
* Assumptions:
* - If ib_post_send() succeeds, only one completion is expected,
* even if one or more WRs are flushed. This is true when posting
* an rdma_rw_ctx or when posting a single signaled WR.
*/
static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
{
struct svcxprt_rdma *rdma = cc->cc_rdma;
struct svc_xprt *xprt = &rdma->sc_xprt;
struct ib_send_wr *first_wr, *bad_wr;
struct list_head *tmp;
struct ib_cqe *cqe;
int ret;
first_wr = NULL;
cqe = &cc->cc_cqe;
list_for_each(tmp, &cc->cc_rwctxts) {
struct svc_rdma_rw_ctxt *ctxt;
ctxt = list_entry(tmp, struct svc_rdma_rw_ctxt, rw_list);
first_wr = rdma_rw_ctx_wrs(&ctxt->rw_ctx, rdma->sc_qp,
rdma->sc_port_num, cqe, first_wr);
cqe = NULL;
}
do {
if (atomic_sub_return(cc->cc_sqecount,
&rdma->sc_sq_avail) > 0) {
ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
if (ret)
break;
return 0;
}
atomic_inc(&rdma_stat_sq_starve);
atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
wait_event(rdma->sc_send_wait,
atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
} while (1);
pr_err("svcrdma: ib_post_send failed (%d)\n", ret);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
/* If even one was posted, there will be a completion. */
if (bad_wr != first_wr)
return 0;
atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
wake_up(&rdma->sc_send_wait);
return -ENOTCONN;
}
/* Build and DMA-map an SGL that covers one kvec in an xdr_buf
*/
static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info,
unsigned int len,
struct svc_rdma_rw_ctxt *ctxt)
{
struct scatterlist *sg = ctxt->rw_sg_table.sgl;
sg_set_buf(&sg[0], info->wi_base, len);
info->wi_base += len;
ctxt->rw_nents = 1;
}
/* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist.
*/
static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info,
unsigned int remaining,
struct svc_rdma_rw_ctxt *ctxt)
{
unsigned int sge_no, sge_bytes, page_off, page_no;
struct xdr_buf *xdr = info->wi_xdr;
struct scatterlist *sg;
struct page **page;
page_off = (info->wi_next_off + xdr->page_base) & ~PAGE_MASK;
page_no = (info->wi_next_off + xdr->page_base) >> PAGE_SHIFT;
page = xdr->pages + page_no;
info->wi_next_off += remaining;
sg = ctxt->rw_sg_table.sgl;
sge_no = 0;
do {
sge_bytes = min_t(unsigned int, remaining,
PAGE_SIZE - page_off);
sg_set_page(sg, *page, sge_bytes, page_off);
remaining -= sge_bytes;
sg = sg_next(sg);
page_off = 0;
sge_no++;
page++;
} while (remaining);
ctxt->rw_nents = sge_no;
}
/* Construct RDMA Write WRs to send a portion of an xdr_buf containing
* an RPC Reply.
*/
static int
svc_rdma_build_writes(struct svc_rdma_write_info *info,
void (*constructor)(struct svc_rdma_write_info *info,
unsigned int len,
struct svc_rdma_rw_ctxt *ctxt),
unsigned int remaining)
{
struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
struct svcxprt_rdma *rdma = cc->cc_rdma;
struct svc_rdma_rw_ctxt *ctxt;
__be32 *seg;
int ret;
cc->cc_cqe.done = svc_rdma_write_done;
seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz;
do {
unsigned int write_len;
u32 seg_length, seg_handle;
u64 seg_offset;
if (info->wi_seg_no >= info->wi_nsegs)
goto out_overflow;
seg_handle = be32_to_cpup(seg);
seg_length = be32_to_cpup(seg + 1);
xdr_decode_hyper(seg + 2, &seg_offset);
seg_offset += info->wi_seg_off;
write_len = min(remaining, seg_length - info->wi_seg_off);
ctxt = svc_rdma_get_rw_ctxt(rdma,
(write_len >> PAGE_SHIFT) + 2);
if (!ctxt)
goto out_noctx;
constructor(info, write_len, ctxt);
ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp,
rdma->sc_port_num, ctxt->rw_sg_table.sgl,
ctxt->rw_nents, 0, seg_offset,
seg_handle, DMA_TO_DEVICE);
if (ret < 0)
goto out_initerr;
list_add(&ctxt->rw_list, &cc->cc_rwctxts);
cc->cc_sqecount += ret;
if (write_len == seg_length - info->wi_seg_off) {
seg += 4;
info->wi_seg_no++;
info->wi_seg_off = 0;
} else {
info->wi_seg_off += write_len;
}
remaining -= write_len;
} while (remaining);
return 0;
out_overflow:
dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
info->wi_nsegs);
return -E2BIG;
out_noctx:
dprintk("svcrdma: no R/W ctxs available\n");
return -ENOMEM;
out_initerr:
svc_rdma_put_rw_ctxt(rdma, ctxt);
pr_err("svcrdma: failed to map pagelist (%d)\n", ret);
return -EIO;
}
/* Send one of an xdr_buf's kvecs by itself. To send a Reply
* chunk, the whole RPC Reply is written back to the client.
* This function writes either the head or tail of the xdr_buf
* containing the Reply.
*/
static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
struct kvec *vec)
{
info->wi_base = vec->iov_base;
return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
vec->iov_len);
}
/* Send an xdr_buf's page list by itself. A Write chunk is
* just the page list. a Reply chunk is the head, page list,
* and tail. This function is shared between the two types
* of chunk.
*/
static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
struct xdr_buf *xdr)
{
info->wi_xdr = xdr;
info->wi_next_off = 0;
return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
xdr->page_len);
}
/**
* svc_rdma_send_write_chunk - Write all segments in a Write chunk
* @rdma: controlling RDMA transport
* @wr_ch: Write chunk provided by client
* @xdr: xdr_buf containing the data payload
*
* Returns a non-negative number of bytes the chunk consumed, or
* %-E2BIG if the payload was larger than the Write chunk,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
*/
int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
struct xdr_buf *xdr)
{
struct svc_rdma_write_info *info;
int ret;
if (!xdr->page_len)
return 0;
info = svc_rdma_write_info_alloc(rdma, wr_ch);
if (!info)
return -ENOMEM;
ret = svc_rdma_send_xdr_pagelist(info, xdr);
if (ret < 0)
goto out_err;
ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
if (ret < 0)
goto out_err;
return xdr->page_len;
out_err:
svc_rdma_write_info_free(info);
return ret;
}
/**
* svc_rdma_send_reply_chunk - Write all segments in the Reply chunk
* @rdma: controlling RDMA transport
* @rp_ch: Reply chunk provided by client
* @writelist: true if client provided a Write list
* @xdr: xdr_buf containing an RPC Reply
*
* Returns a non-negative number of bytes the chunk consumed, or
* %-E2BIG if the payload was larger than the Reply chunk,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
*/
int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch,
bool writelist, struct xdr_buf *xdr)
{
struct svc_rdma_write_info *info;
int consumed, ret;
info = svc_rdma_write_info_alloc(rdma, rp_ch);
if (!info)
return -ENOMEM;
ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
if (ret < 0)
goto out_err;
consumed = xdr->head[0].iov_len;
/* Send the page list in the Reply chunk only if the
* client did not provide Write chunks.
*/
if (!writelist && xdr->page_len) {
ret = svc_rdma_send_xdr_pagelist(info, xdr);
if (ret < 0)
goto out_err;
consumed += xdr->page_len;
}
if (xdr->tail[0].iov_len) {
ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
if (ret < 0)
goto out_err;
consumed += xdr->tail[0].iov_len;
}
ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
if (ret < 0)
goto out_err;
return consumed;
out_err:
svc_rdma_write_info_free(info);
return ret;
}

View File

@ -561,6 +561,7 @@ static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q); INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q);
INIT_LIST_HEAD(&cma_xprt->sc_frmr_q); INIT_LIST_HEAD(&cma_xprt->sc_frmr_q);
INIT_LIST_HEAD(&cma_xprt->sc_ctxts); INIT_LIST_HEAD(&cma_xprt->sc_ctxts);
INIT_LIST_HEAD(&cma_xprt->sc_rw_ctxts);
INIT_LIST_HEAD(&cma_xprt->sc_maps); INIT_LIST_HEAD(&cma_xprt->sc_maps);
init_waitqueue_head(&cma_xprt->sc_send_wait); init_waitqueue_head(&cma_xprt->sc_send_wait);
@ -568,6 +569,7 @@ static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
spin_lock_init(&cma_xprt->sc_rq_dto_lock); spin_lock_init(&cma_xprt->sc_rq_dto_lock);
spin_lock_init(&cma_xprt->sc_frmr_q_lock); spin_lock_init(&cma_xprt->sc_frmr_q_lock);
spin_lock_init(&cma_xprt->sc_ctxt_lock); spin_lock_init(&cma_xprt->sc_ctxt_lock);
spin_lock_init(&cma_xprt->sc_rw_ctxt_lock);
spin_lock_init(&cma_xprt->sc_map_lock); spin_lock_init(&cma_xprt->sc_map_lock);
/* /*
@ -999,6 +1001,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
newxprt, newxprt->sc_cm_id); newxprt, newxprt->sc_cm_id);
dev = newxprt->sc_cm_id->device; dev = newxprt->sc_cm_id->device;
newxprt->sc_port_num = newxprt->sc_cm_id->port_num;
/* Qualify the transport resource defaults with the /* Qualify the transport resource defaults with the
* capabilities of this particular device */ * capabilities of this particular device */
@ -1248,6 +1251,7 @@ static void __svc_rdma_free(struct work_struct *work)
} }
rdma_dealloc_frmr_q(rdma); rdma_dealloc_frmr_q(rdma);
svc_rdma_destroy_rw_ctxts(rdma);
svc_rdma_destroy_ctxts(rdma); svc_rdma_destroy_ctxts(rdma);
svc_rdma_destroy_maps(rdma); svc_rdma_destroy_maps(rdma);