// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2016-2018 Oracle. All rights reserved.
*
* Use the core R/W API to move RPC-over-RDMA Read and Write chunks.
*/
#include <rdma/rw.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>
#include <linux/sunrpc/debug.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc);
static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc);
/* 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(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
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,
SG_CHUNK_SIZE)) {
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, SG_CHUNK_SIZE);
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;
};
static void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
struct svc_rdma_chunk_ctxt *cc)
{
cc->cc_rdma = rdma;
svc_xprt_get(&rdma->sc_xprt);
INIT_LIST_HEAD(&cc->cc_rwctxts);
cc->cc_sqecount = 0;
}
static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc,
enum dma_data_direction dir)
{
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, 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);
info->wi_cc.cc_cqe.done = svc_rdma_write_done;
return info;
}
static void svc_rdma_write_info_free(struct svc_rdma_write_info *info)
{
svc_rdma_cc_release(&info->wi_cc, DMA_TO_DEVICE);
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);
trace_svcrdma_wc_write(wc);
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);
svc_rdma_write_info_free(info);
}
/* State for pulling a Read chunk.
*/
struct svc_rdma_read_info {
struct svc_rdma_recv_ctxt *ri_readctxt;
unsigned int ri_position;
unsigned int ri_pageno;
unsigned int ri_pageoff;
unsigned int ri_chunklen;
struct svc_rdma_chunk_ctxt ri_cc;
};
static struct svc_rdma_read_info *
svc_rdma_read_info_alloc(struct svcxprt_rdma *rdma)
{
struct svc_rdma_read_info *info;
info = kmalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return info;
svc_rdma_cc_init(rdma, &info->ri_cc);
info->ri_cc.cc_cqe.done = svc_rdma_wc_read_done;
return info;
}
static void svc_rdma_read_info_free(struct svc_rdma_read_info *info)
{
svc_rdma_cc_release(&info->ri_cc, DMA_FROM_DEVICE);
kfree(info);
}
/**
* svc_rdma_wc_read_done - Handle completion of an RDMA Read ctx
* @cq: controlling Completion Queue
* @wc: Work Completion
*
*/
static void svc_rdma_wc_read_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_read_info *info =
container_of(cc, struct svc_rdma_read_info, ri_cc);
trace_svcrdma_wc_read(wc);
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);
svc_rdma_recv_ctxt_put(rdma, info->ri_readctxt);
} else {
spin_lock(&rdma->sc_rq_dto_lock);
list_add_tail(&info->ri_readctxt->rc_list,
&rdma->sc_read_complete_q);
/* Note the unlock pairs with the smp_rmb in svc_xprt_ready: */
set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
spin_unlock(&rdma->sc_rq_dto_lock);
svc_xprt_enqueue(&rdma->sc_xprt);
}
svc_rdma_read_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;
const struct ib_send_wr *bad_wr;
struct list_head *tmp;
struct ib_cqe *cqe;
int ret;
if (cc->cc_sqecount > rdma->sc_sq_depth)
return -EINVAL;
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);
trace_svcrdma_post_rw(&cc->cc_cqe,
cc->cc_sqecount, ret);
if (ret)
break;
return 0;
}
trace_svcrdma_sq_full(rdma);
atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
wait_event(rdma->sc_send_wait,
atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
trace_svcrdma_sq_retry(rdma);
} while (1);
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_no = page_off >> PAGE_SHIFT;
page_off = offset_in_page(page_off);
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;
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;
trace_svcrdma_encode_wseg(seg_handle, write_len, seg_offset);
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);
trace_svcrdma_dma_map_rwctx(rdma, 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,
* %-EINVAL if client provided too many segments,
* %-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;
trace_svcrdma_encode_write(xdr->page_len);
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,
* %-EINVAL if client provided too many segments,
* %-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;
trace_svcrdma_encode_reply(consumed);
return consumed;
out_err:
svc_rdma_write_info_free(info);
return ret;
}
static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
struct svc_rqst *rqstp,
u32 rkey, u32 len, u64 offset)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
struct svc_rdma_chunk_ctxt *cc = &info->ri_cc;
struct svc_rdma_rw_ctxt *ctxt;
unsigned int sge_no, seg_len;
struct scatterlist *sg;
int ret;
sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT;
ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no);
if (!ctxt)
goto out_noctx;
ctxt->rw_nents = sge_no;
sg = ctxt->rw_sg_table.sgl;
for (sge_no = 0; sge_no < ctxt->rw_nents; sge_no++) {
seg_len = min_t(unsigned int, len,
PAGE_SIZE - info->ri_pageoff);
head->rc_arg.pages[info->ri_pageno] =
rqstp->rq_pages[info->ri_pageno];
if (!info->ri_pageoff)
head->rc_page_count++;
sg_set_page(sg, rqstp->rq_pages[info->ri_pageno],
seg_len, info->ri_pageoff);
sg = sg_next(sg);
info->ri_pageoff += seg_len;
if (info->ri_pageoff == PAGE_SIZE) {
info->ri_pageno++;
info->ri_pageoff = 0;
}
len -= seg_len;
/* Safety check */
if (len &&
&rqstp->rq_pages[info->ri_pageno + 1] > rqstp->rq_page_end)
goto out_overrun;
}
ret = rdma_rw_ctx_init(&ctxt->rw_ctx, cc->cc_rdma->sc_qp,
cc->cc_rdma->sc_port_num,
ctxt->rw_sg_table.sgl, ctxt->rw_nents,
0, offset, rkey, DMA_FROM_DEVICE);
if (ret < 0)
goto out_initerr;
list_add(&ctxt->rw_list, &cc->cc_rwctxts);
cc->cc_sqecount += ret;
return 0;
out_noctx:
dprintk("svcrdma: no R/W ctxs available\n");
return -ENOMEM;
out_overrun:
dprintk("svcrdma: request overruns rq_pages\n");
return -EINVAL;
out_initerr:
trace_svcrdma_dma_map_rwctx(cc->cc_rdma, ret);
svc_rdma_put_rw_ctxt(cc->cc_rdma, ctxt);
return -EIO;
}
/* Walk the segments in the Read chunk starting at @p and construct
* RDMA Read operations to pull the chunk to the server.
*/
static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
struct svc_rdma_read_info *info,
__be32 *p)
{
unsigned int i;
int ret;
ret = -EINVAL;
info->ri_chunklen = 0;
while (*p++ != xdr_zero && be32_to_cpup(p++) == info->ri_position) {
u32 rs_handle, rs_length;
u64 rs_offset;
rs_handle = be32_to_cpup(p++);
rs_length = be32_to_cpup(p++);
p = xdr_decode_hyper(p, &rs_offset);
ret = svc_rdma_build_read_segment(info, rqstp,
rs_handle, rs_length,
rs_offset);
if (ret < 0)
break;
trace_svcrdma_encode_rseg(rs_handle, rs_length, rs_offset);
info->ri_chunklen += rs_length;
}
/* Pages under I/O have been copied to head->rc_pages.
* Prevent their premature release by svc_xprt_release() .
*/
for (i = 0; i < info->ri_readctxt->rc_page_count; i++)
rqstp->rq_pages[i] = NULL;
return ret;
}
/* Construct RDMA Reads to pull over a normal Read chunk. The chunk
* data lands in the page list of head->rc_arg.pages.
*
* Currently NFSD does not look at the head->rc_arg.tail[0] iovec.
* Therefore, XDR round-up of the Read chunk and trailing
* inline content must both be added at the end of the pagelist.
*/
static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp,
struct svc_rdma_read_info *info,
__be32 *p)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
int ret;
ret = svc_rdma_build_read_chunk(rqstp, info, p);
if (ret < 0)
goto out;
trace_svcrdma_encode_read(info->ri_chunklen, info->ri_position);
head->rc_hdr_count = 0;
/* Split the Receive buffer between the head and tail
* buffers at Read chunk's position. XDR roundup of the
* chunk is not included in either the pagelist or in
* the tail.
*/
head->rc_arg.tail[0].iov_base =
head->rc_arg.head[0].iov_base + info->ri_position;
head->rc_arg.tail[0].iov_len =
head->rc_arg.head[0].iov_len - info->ri_position;
head->rc_arg.head[0].iov_len = info->ri_position;
/* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2).
*
* If the client already rounded up the chunk length, the
* length does not change. Otherwise, the length of the page
* list is increased to include XDR round-up.
*
* Currently these chunks always start at page offset 0,
* thus the rounded-up length never crosses a page boundary.
*/
info->ri_chunklen = XDR_QUADLEN(info->ri_chunklen) << 2;
head->rc_arg.page_len = info->ri_chunklen;
head->rc_arg.len += info->ri_chunklen;
head->rc_arg.buflen += info->ri_chunklen;
out:
return ret;
}
/* Construct RDMA Reads to pull over a Position Zero Read chunk.
* The start of the data lands in the first page just after
* the Transport header, and the rest lands in the page list of
* head->rc_arg.pages.
*
* Assumptions:
* - A PZRC has an XDR-aligned length (no implicit round-up).
* - There can be no trailing inline content (IOW, we assume
* a PZRC is never sent in an RDMA_MSG message, though it's
* allowed by spec).
*/
static int svc_rdma_build_pz_read_chunk(struct svc_rqst *rqstp,
struct svc_rdma_read_info *info,
__be32 *p)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
int ret;
ret = svc_rdma_build_read_chunk(rqstp, info, p);
if (ret < 0)
goto out;
trace_svcrdma_encode_pzr(info->ri_chunklen);
head->rc_arg.len += info->ri_chunklen;
head->rc_arg.buflen += info->ri_chunklen;
head->rc_hdr_count = 1;
head->rc_arg.head[0].iov_base = page_address(head->rc_pages[0]);
head->rc_arg.head[0].iov_len = min_t(size_t, PAGE_SIZE,
info->ri_chunklen);
head->rc_arg.page_len = info->ri_chunklen -
head->rc_arg.head[0].iov_len;
out:
return ret;
}
/**
* svc_rdma_recv_read_chunk - Pull a Read chunk from the client
* @rdma: controlling RDMA transport
* @rqstp: set of pages to use as Read sink buffers
* @head: pages under I/O collect here
* @p: pointer to start of Read chunk
*
* Returns:
* %0 if all needed RDMA Reads were posted successfully,
* %-EINVAL if client provided too many segments,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
*
* Assumptions:
* - All Read segments in @p have the same Position value.
*/
int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head, __be32 *p)
{
struct svc_rdma_read_info *info;
int ret;
/* The request (with page list) is constructed in
* head->rc_arg. Pages involved with RDMA Read I/O are
* transferred there.
*/
head->rc_arg.head[0] = rqstp->rq_arg.head[0];
head->rc_arg.tail[0] = rqstp->rq_arg.tail[0];
head->rc_arg.pages = head->rc_pages;
head->rc_arg.page_base = 0;
head->rc_arg.page_len = 0;
head->rc_arg.len = rqstp->rq_arg.len;
head->rc_arg.buflen = rqstp->rq_arg.buflen;
info = svc_rdma_read_info_alloc(rdma);
if (!info)
return -ENOMEM;
info->ri_readctxt = head;
info->ri_pageno = 0;
info->ri_pageoff = 0;
info->ri_position = be32_to_cpup(p + 1);
if (info->ri_position)
ret = svc_rdma_build_normal_read_chunk(rqstp, info, p);
else
ret = svc_rdma_build_pz_read_chunk(rqstp, info, p);
if (ret < 0)
goto out_err;
ret = svc_rdma_post_chunk_ctxt(&info->ri_cc);
if (ret < 0)
goto out_err;
return 0;
out_err:
svc_rdma_read_info_free(info);
return ret;
}
