xprtrdma: Place registered MWs on a per-req list

Instead of placing registered MWs sparsely into the rl_segments
array, place these MWs on a per-req list.

ro_unmap_{sync,safe} can then simply pull those MWs off the list
instead of walking through the array.

This change significantly reduces the size of struct rpcrdma_req
by removing nsegs and rl_mw from every array element.

As an additional clean-up, chunk co-ordinates are returned in the
"*mw" output argument so they are no longer needed in every
array element.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2016-06-29 13:54:16 -04:00 committed by Anna Schumaker
parent 2ffc871a57
commit 9d6b040978
6 changed files with 94 additions and 139 deletions

View File

@ -101,6 +101,10 @@ fmr_op_release_mr(struct rpcrdma_mw *r)
LIST_HEAD(unmap_list);
int rc;
/* Ensure MW is not on any rl_registered list */
if (!list_empty(&r->mw_list))
list_del(&r->mw_list);
kfree(r->fmr.fm_physaddrs);
kfree(r->mw_sg);
@ -176,17 +180,13 @@ fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
*/
static int
fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
int nsegs, bool writing)
int nsegs, bool writing, struct rpcrdma_mw **out)
{
struct rpcrdma_mr_seg *seg1 = seg;
int len, pageoff, i, rc;
struct rpcrdma_mw *mw;
u64 *dma_pages;
mw = seg1->rl_mw;
seg1->rl_mw = NULL;
if (mw)
rpcrdma_defer_mr_recovery(mw);
mw = rpcrdma_get_mw(r_xprt);
if (!mw)
return -ENOBUFS;
@ -230,11 +230,11 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
if (rc)
goto out_maperr;
seg1->rl_mw = mw;
seg1->mr_rkey = mw->fmr.fm_mr->rkey;
seg1->mr_base = dma_pages[0] + pageoff;
seg1->mr_nsegs = mw->mw_nents;
seg1->mr_len = len;
mw->mw_handle = mw->fmr.fm_mr->rkey;
mw->mw_length = len;
mw->mw_offset = dma_pages[0] + pageoff;
*out = mw;
return mw->mw_nents;
out_dmamap_err:
@ -255,13 +255,13 @@ out_maperr:
*
* Sleeps until it is safe for the host CPU to access the
* previously mapped memory regions.
*
* Caller ensures that req->rl_registered is not empty.
*/
static void
fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
{
struct rpcrdma_mr_seg *seg;
unsigned int i, nchunks;
struct rpcrdma_mw *mw;
struct rpcrdma_mw *mw, *tmp;
LIST_HEAD(unmap_list);
int rc;
@ -272,14 +272,8 @@ fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
* ib_unmap_fmr() is slow, so use a single call instead
* of one call per mapped FMR.
*/
for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
list_for_each_entry(mw, &req->rl_registered, mw_list)
list_add_tail(&mw->fmr.fm_mr->list, &unmap_list);
i += seg->mr_nsegs;
}
rc = ib_unmap_fmr(&unmap_list);
if (rc)
goto out_reset;
@ -287,34 +281,22 @@ fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
/* ORDER: Now DMA unmap all of the req's MRs, and return
* them to the free MW list.
*/
for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
list_del_init(&mw->mw_list);
list_del_init(&mw->fmr.fm_mr->list);
ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
mw->mw_sg, mw->mw_nents, mw->mw_dir);
rpcrdma_put_mw(r_xprt, mw);
i += seg->mr_nsegs;
seg->mr_nsegs = 0;
seg->rl_mw = NULL;
}
req->rl_nchunks = 0;
return;
out_reset:
pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
list_del_init(&mw->fmr.fm_mr->list);
fmr_op_recover_mr(mw);
i += seg->mr_nsegs;
}
}
@ -325,22 +307,17 @@ static void
fmr_op_unmap_safe(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
bool sync)
{
struct rpcrdma_mr_seg *seg;
struct rpcrdma_mw *mw;
unsigned int i;
for (i = 0; req->rl_nchunks; req->rl_nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
while (!list_empty(&req->rl_registered)) {
mw = list_first_entry(&req->rl_registered,
struct rpcrdma_mw, mw_list);
list_del_init(&mw->mw_list);
if (sync)
fmr_op_recover_mr(mw);
else
rpcrdma_defer_mr_recovery(mw);
i += seg->mr_nsegs;
seg->mr_nsegs = 0;
seg->rl_mw = NULL;
}
}

View File

@ -128,6 +128,10 @@ frwr_op_release_mr(struct rpcrdma_mw *r)
{
int rc;
/* Ensure MW is not on any rl_registered list */
if (!list_empty(&r->mw_list))
list_del(&r->mw_list);
rc = ib_dereg_mr(r->frmr.fr_mr);
if (rc)
pr_err("rpcrdma: final ib_dereg_mr for %p returned %i\n",
@ -333,10 +337,9 @@ frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
*/
static int
frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
int nsegs, bool writing)
int nsegs, bool writing, struct rpcrdma_mw **out)
{
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
struct rpcrdma_mr_seg *seg1 = seg;
struct rpcrdma_mw *mw;
struct rpcrdma_frmr *frmr;
struct ib_mr *mr;
@ -345,8 +348,7 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
int rc, i, n, dma_nents;
u8 key;
mw = seg1->rl_mw;
seg1->rl_mw = NULL;
mw = NULL;
do {
if (mw)
rpcrdma_defer_mr_recovery(mw);
@ -416,12 +418,11 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
if (rc)
goto out_senderr;
seg1->rl_mw = mw;
seg1->mr_rkey = mr->rkey;
seg1->mr_base = mr->iova;
seg1->mr_nsegs = mw->mw_nents;
seg1->mr_len = mr->length;
mw->mw_handle = mr->rkey;
mw->mw_length = mr->length;
mw->mw_offset = mr->iova;
*out = mw;
return mw->mw_nents;
out_dmamap_err:
@ -443,9 +444,8 @@ out_senderr:
}
static struct ib_send_wr *
__frwr_prepare_linv_wr(struct rpcrdma_mr_seg *seg)
__frwr_prepare_linv_wr(struct rpcrdma_mw *mw)
{
struct rpcrdma_mw *mw = seg->rl_mw;
struct rpcrdma_frmr *f = &mw->frmr;
struct ib_send_wr *invalidate_wr;
@ -465,16 +465,16 @@ __frwr_prepare_linv_wr(struct rpcrdma_mr_seg *seg)
*
* Sleeps until it is safe for the host CPU to access the
* previously mapped memory regions.
*
* Caller ensures that req->rl_registered is not empty.
*/
static void
frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
{
struct ib_send_wr *invalidate_wrs, *pos, *prev, *bad_wr;
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
struct rpcrdma_mr_seg *seg;
unsigned int i, nchunks;
struct rpcrdma_mw *mw, *tmp;
struct rpcrdma_frmr *f;
struct rpcrdma_mw *mw;
int rc;
dprintk("RPC: %s: req %p\n", __func__, req);
@ -484,22 +484,18 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
* Chain the LOCAL_INV Work Requests and post them with
* a single ib_post_send() call.
*/
f = NULL;
invalidate_wrs = pos = prev = NULL;
seg = NULL;
for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
seg = &req->rl_segments[i];
pos = __frwr_prepare_linv_wr(seg);
list_for_each_entry(mw, &req->rl_registered, mw_list) {
pos = __frwr_prepare_linv_wr(mw);
if (!invalidate_wrs)
invalidate_wrs = pos;
else
prev->next = pos;
prev = pos;
i += seg->mr_nsegs;
f = &mw->frmr;
}
f = &seg->rl_mw->frmr;
/* Strong send queue ordering guarantees that when the
* last WR in the chain completes, all WRs in the chain
@ -524,20 +520,12 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
* them to the free MW list.
*/
unmap:
for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
seg->rl_mw = NULL;
list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
list_del_init(&mw->mw_list);
ib_dma_unmap_sg(ia->ri_device,
mw->mw_sg, mw->mw_nents, mw->mw_dir);
rpcrdma_put_mw(r_xprt, mw);
i += seg->mr_nsegs;
seg->mr_nsegs = 0;
}
req->rl_nchunks = 0;
return;
reset_mrs:
@ -547,17 +535,12 @@ reset_mrs:
/* Find and reset the MRs in the LOCAL_INV WRs that did not
* get posted. This is synchronous, and slow.
*/
for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
list_for_each_entry(mw, &req->rl_registered, mw_list) {
f = &mw->frmr;
if (mw->frmr.fr_mr->rkey == bad_wr->ex.invalidate_rkey) {
__frwr_reset_mr(ia, mw);
bad_wr = bad_wr->next;
}
i += seg->mr_nsegs;
}
goto unmap;
}
@ -569,22 +552,17 @@ static void
frwr_op_unmap_safe(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
bool sync)
{
struct rpcrdma_mr_seg *seg;
struct rpcrdma_mw *mw;
unsigned int i;
for (i = 0; req->rl_nchunks; req->rl_nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
while (!list_empty(&req->rl_registered)) {
mw = list_first_entry(&req->rl_registered,
struct rpcrdma_mw, mw_list);
list_del_init(&mw->mw_list);
if (sync)
frwr_op_recover_mr(mw);
else
rpcrdma_defer_mr_recovery(mw);
i += seg->mr_nsegs;
seg->mr_nsegs = 0;
seg->rl_mw = NULL;
}
}

View File

@ -286,11 +286,11 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
}
static inline __be32 *
xdr_encode_rdma_segment(__be32 *iptr, struct rpcrdma_mr_seg *seg)
xdr_encode_rdma_segment(__be32 *iptr, struct rpcrdma_mw *mw)
{
*iptr++ = cpu_to_be32(seg->mr_rkey);
*iptr++ = cpu_to_be32(seg->mr_len);
return xdr_encode_hyper(iptr, seg->mr_base);
*iptr++ = cpu_to_be32(mw->mw_handle);
*iptr++ = cpu_to_be32(mw->mw_length);
return xdr_encode_hyper(iptr, mw->mw_offset);
}
/* XDR-encode the Read list. Supports encoding a list of read
@ -311,6 +311,7 @@ rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt,
__be32 *iptr, enum rpcrdma_chunktype rtype)
{
struct rpcrdma_mr_seg *seg = req->rl_nextseg;
struct rpcrdma_mw *mw;
unsigned int pos;
int n, nsegs;
@ -328,9 +329,11 @@ rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt,
return ERR_PTR(nsegs);
do {
n = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs, false);
n = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
false, &mw);
if (n < 0)
return ERR_PTR(n);
list_add(&mw->mw_list, &req->rl_registered);
*iptr++ = xdr_one; /* item present */
@ -338,13 +341,12 @@ rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt,
* have the same "position".
*/
*iptr++ = cpu_to_be32(pos);
iptr = xdr_encode_rdma_segment(iptr, seg);
iptr = xdr_encode_rdma_segment(iptr, mw);
dprintk("RPC: %5u %s: read segment pos %u "
"%d@0x%016llx:0x%08x (%s)\n",
dprintk("RPC: %5u %s: pos %u %u@0x%016llx:0x%08x (%s)\n",
rqst->rq_task->tk_pid, __func__, pos,
seg->mr_len, (unsigned long long)seg->mr_base,
seg->mr_rkey, n < nsegs ? "more" : "last");
mw->mw_length, (unsigned long long)mw->mw_offset,
mw->mw_handle, n < nsegs ? "more" : "last");
r_xprt->rx_stats.read_chunk_count++;
req->rl_nchunks++;
@ -376,6 +378,7 @@ rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
enum rpcrdma_chunktype wtype)
{
struct rpcrdma_mr_seg *seg = req->rl_nextseg;
struct rpcrdma_mw *mw;
int n, nsegs, nchunks;
__be32 *segcount;
@ -396,17 +399,18 @@ rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
nchunks = 0;
do {
n = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs, true);
n = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
true, &mw);
if (n < 0)
return ERR_PTR(n);
list_add(&mw->mw_list, &req->rl_registered);
iptr = xdr_encode_rdma_segment(iptr, seg);
iptr = xdr_encode_rdma_segment(iptr, mw);
dprintk("RPC: %5u %s: write segment "
"%d@0x016%llx:0x%08x (%s)\n",
dprintk("RPC: %5u %s: %u@0x016%llx:0x%08x (%s)\n",
rqst->rq_task->tk_pid, __func__,
seg->mr_len, (unsigned long long)seg->mr_base,
seg->mr_rkey, n < nsegs ? "more" : "last");
mw->mw_length, (unsigned long long)mw->mw_offset,
mw->mw_handle, n < nsegs ? "more" : "last");
r_xprt->rx_stats.write_chunk_count++;
r_xprt->rx_stats.total_rdma_request += seg->mr_len;
@ -443,6 +447,7 @@ rpcrdma_encode_reply_chunk(struct rpcrdma_xprt *r_xprt,
__be32 *iptr, enum rpcrdma_chunktype wtype)
{
struct rpcrdma_mr_seg *seg = req->rl_nextseg;
struct rpcrdma_mw *mw;
int n, nsegs, nchunks;
__be32 *segcount;
@ -461,17 +466,18 @@ rpcrdma_encode_reply_chunk(struct rpcrdma_xprt *r_xprt,
nchunks = 0;
do {
n = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs, true);
n = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
true, &mw);
if (n < 0)
return ERR_PTR(n);
list_add(&mw->mw_list, &req->rl_registered);
iptr = xdr_encode_rdma_segment(iptr, seg);
iptr = xdr_encode_rdma_segment(iptr, mw);
dprintk("RPC: %5u %s: reply segment "
"%d@0x%016llx:0x%08x (%s)\n",
dprintk("RPC: %5u %s: %u@0x%016llx:0x%08x (%s)\n",
rqst->rq_task->tk_pid, __func__,
seg->mr_len, (unsigned long long)seg->mr_base,
seg->mr_rkey, n < nsegs ? "more" : "last");
mw->mw_length, (unsigned long long)mw->mw_offset,
mw->mw_handle, n < nsegs ? "more" : "last");
r_xprt->rx_stats.reply_chunk_count++;
r_xprt->rx_stats.total_rdma_request += seg->mr_len;
@ -690,10 +696,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
out_overflow:
pr_err("rpcrdma: send overflow: hdrlen %zd rpclen %zu %s/%s\n",
hdrlen, rpclen, transfertypes[rtype], transfertypes[wtype]);
/* Terminate this RPC. Chunks registered above will be
* released by xprt_release -> xprt_rmda_free .
*/
return -EIO;
iptr = ERR_PTR(-EIO);
out_unmap:
r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);
@ -705,15 +708,13 @@ out_unmap:
* RDMA'd by server. See map at rpcrdma_create_chunks()! :-)
*/
static int
rpcrdma_count_chunks(struct rpcrdma_rep *rep, unsigned int max, int wrchunk, __be32 **iptrp)
rpcrdma_count_chunks(struct rpcrdma_rep *rep, int wrchunk, __be32 **iptrp)
{
unsigned int i, total_len;
struct rpcrdma_write_chunk *cur_wchunk;
char *base = (char *)rdmab_to_msg(rep->rr_rdmabuf);
i = be32_to_cpu(**iptrp);
if (i > max)
return -1;
cur_wchunk = (struct rpcrdma_write_chunk *) (*iptrp + 1);
total_len = 0;
while (i--) {
@ -960,14 +961,13 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
(headerp->rm_body.rm_chunks[1] == xdr_zero &&
headerp->rm_body.rm_chunks[2] != xdr_zero) ||
(headerp->rm_body.rm_chunks[1] != xdr_zero &&
req->rl_nchunks == 0))
list_empty(&req->rl_registered)))
goto badheader;
if (headerp->rm_body.rm_chunks[1] != xdr_zero) {
/* count any expected write chunks in read reply */
/* start at write chunk array count */
iptr = &headerp->rm_body.rm_chunks[2];
rdmalen = rpcrdma_count_chunks(rep,
req->rl_nchunks, 1, &iptr);
rdmalen = rpcrdma_count_chunks(rep, 1, &iptr);
/* check for validity, and no reply chunk after */
if (rdmalen < 0 || *iptr++ != xdr_zero)
goto badheader;
@ -997,11 +997,11 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
if (headerp->rm_body.rm_chunks[0] != xdr_zero ||
headerp->rm_body.rm_chunks[1] != xdr_zero ||
headerp->rm_body.rm_chunks[2] != xdr_one ||
req->rl_nchunks == 0)
list_empty(&req->rl_registered))
goto badheader;
iptr = (__be32 *)((unsigned char *)headerp +
RPCRDMA_HDRLEN_MIN);
rdmalen = rpcrdma_count_chunks(rep, req->rl_nchunks, 0, &iptr);
rdmalen = rpcrdma_count_chunks(rep, 0, &iptr);
if (rdmalen < 0)
goto badheader;
r_xprt->rx_stats.total_rdma_reply += rdmalen;
@ -1014,14 +1014,9 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
badheader:
default:
dprintk("%s: invalid rpcrdma reply header (type %d):"
" chunks[012] == %d %d %d"
" expected chunks <= %d\n",
__func__, be32_to_cpu(headerp->rm_type),
headerp->rm_body.rm_chunks[0],
headerp->rm_body.rm_chunks[1],
headerp->rm_body.rm_chunks[2],
req->rl_nchunks);
dprintk("RPC: %5u %s: invalid rpcrdma reply (type %u)\n",
rqst->rq_task->tk_pid, __func__,
be32_to_cpu(headerp->rm_type));
status = -EIO;
r_xprt->rx_stats.bad_reply_count++;
break;
@ -1035,7 +1030,7 @@ out:
* control: waking the next RPC waits until this RPC has
* relinquished all its Send Queue entries.
*/
if (req->rl_nchunks)
if (!list_empty(&req->rl_registered))
r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt, req);
spin_lock_bh(&xprt->transport_lock);

View File

@ -619,6 +619,9 @@ xprt_rdma_send_request(struct rpc_task *task)
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
int rc = 0;
/* On retransmit, remove any previously registered chunks */
r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);
rc = rpcrdma_marshal_req(rqst);
if (rc < 0)
goto failed_marshal;

View File

@ -847,6 +847,7 @@ rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
spin_unlock(&buffer->rb_reqslock);
req->rl_cqe.done = rpcrdma_wc_send;
req->rl_buffer = &r_xprt->rx_buf;
INIT_LIST_HEAD(&req->rl_registered);
return req;
}

View File

@ -245,6 +245,9 @@ struct rpcrdma_mw {
struct rpcrdma_frmr frmr;
};
struct rpcrdma_xprt *mw_xprt;
u32 mw_handle;
u32 mw_length;
u64 mw_offset;
struct list_head mw_all;
};
@ -272,11 +275,7 @@ struct rpcrdma_mw {
*/
struct rpcrdma_mr_seg { /* chunk descriptors */
struct rpcrdma_mw *rl_mw; /* registered MR */
u64 mr_base; /* registration result */
u32 mr_rkey; /* registration result */
u32 mr_len; /* length of chunk or segment */
int mr_nsegs; /* number of segments in chunk or 0 */
struct page *mr_page; /* owning page, if any */
char *mr_offset; /* kva if no page, else offset */
};
@ -294,6 +293,7 @@ struct rpcrdma_req {
struct ib_sge rl_send_iov[RPCRDMA_MAX_IOVS];
struct rpcrdma_regbuf *rl_rdmabuf;
struct rpcrdma_regbuf *rl_sendbuf;
struct list_head rl_registered; /* registered segments */
struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];
struct rpcrdma_mr_seg *rl_nextseg;
@ -397,7 +397,8 @@ struct rpcrdma_stats {
struct rpcrdma_xprt;
struct rpcrdma_memreg_ops {
int (*ro_map)(struct rpcrdma_xprt *,
struct rpcrdma_mr_seg *, int, bool);
struct rpcrdma_mr_seg *, int, bool,
struct rpcrdma_mw **);
void (*ro_unmap_sync)(struct rpcrdma_xprt *,
struct rpcrdma_req *);
void (*ro_unmap_safe)(struct rpcrdma_xprt *,