// 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/xdr.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
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 llist_node rw_node;
struct list_head rw_list;
struct rdma_rw_ctx rw_ctx;
unsigned int rw_nents;
unsigned int rw_first_sgl_nents;
struct sg_table rw_sg_table;
struct scatterlist rw_first_sgl[];
};
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 ib_device *dev = rdma->sc_cm_id->device;
unsigned int first_sgl_nents = dev->attrs.max_send_sge;
struct svc_rdma_rw_ctxt *ctxt;
struct llist_node *node;
spin_lock(&rdma->sc_rw_ctxt_lock);
node = llist_del_first(&rdma->sc_rw_ctxts);
spin_unlock(&rdma->sc_rw_ctxt_lock);
if (node) {
ctxt = llist_entry(node, struct svc_rdma_rw_ctxt, rw_node);
} else {
ctxt = kmalloc_node(struct_size(ctxt, rw_first_sgl, first_sgl_nents),
GFP_KERNEL, ibdev_to_node(dev));
if (!ctxt)
goto out_noctx;
INIT_LIST_HEAD(&ctxt->rw_list);
ctxt->rw_first_sgl_nents = first_sgl_nents;
}
ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl;
if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges,
ctxt->rw_sg_table.sgl,
first_sgl_nents))
goto out_free;
return ctxt;
out_free:
kfree(ctxt);
out_noctx:
trace_svcrdma_rwctx_empty(rdma, sges);
return NULL;
}
static void __svc_rdma_put_rw_ctxt(struct svc_rdma_rw_ctxt *ctxt,
struct llist_head *list)
{
sg_free_table_chained(&ctxt->rw_sg_table, ctxt->rw_first_sgl_nents);
llist_add(&ctxt->rw_node, list);
}
static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
struct svc_rdma_rw_ctxt *ctxt)
{
__svc_rdma_put_rw_ctxt(ctxt, &rdma->sc_rw_ctxts);
}
/**
* 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;
struct llist_node *node;
while ((node = llist_del_first(&rdma->sc_rw_ctxts)) != NULL) {
ctxt = llist_entry(node, struct svc_rdma_rw_ctxt, rw_node);
kfree(ctxt);
}
}
/**
* svc_rdma_rw_ctx_init - Prepare a R/W context for I/O
* @rdma: controlling transport instance
* @ctxt: R/W context to prepare
* @offset: RDMA offset
* @handle: RDMA tag/handle
* @direction: I/O direction
*
* Returns on success, the number of WQEs that will be needed
* on the workqueue, or a negative errno.
*/
static int svc_rdma_rw_ctx_init(struct svcxprt_rdma *rdma,
struct svc_rdma_rw_ctxt *ctxt,
u64 offset, u32 handle,
enum dma_data_direction direction)
{
int ret;
ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp, rdma->sc_port_num,
ctxt->rw_sg_table.sgl, ctxt->rw_nents,
0, offset, handle, direction);
if (unlikely(ret < 0)) {
trace_svcrdma_dma_map_rw_err(rdma, offset, handle,
ctxt->rw_nents, ret);
svc_rdma_put_rw_ctxt(rdma, ctxt);
}
return ret;
}
/**
* svc_rdma_cc_init - Initialize an svc_rdma_chunk_ctxt
* @rdma: controlling transport instance
* @cc: svc_rdma_chunk_ctxt to be initialized
*/
void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
struct svc_rdma_chunk_ctxt *cc)
{
struct rpc_rdma_cid *cid = &cc->cc_cid;
if (unlikely(!cid->ci_completion_id))
svc_rdma_send_cid_init(rdma, cid);
INIT_LIST_HEAD(&cc->cc_rwctxts);
cc->cc_sqecount = 0;
}
/**
* svc_rdma_cc_release - Release resources held by a svc_rdma_chunk_ctxt
* @rdma: controlling transport instance
* @cc: svc_rdma_chunk_ctxt to be released
* @dir: DMA direction
*/
void svc_rdma_cc_release(struct svcxprt_rdma *rdma,
struct svc_rdma_chunk_ctxt *cc,
enum dma_data_direction dir)
{
struct llist_node *first, *last;
struct svc_rdma_rw_ctxt *ctxt;
LLIST_HEAD(free);
trace_svcrdma_cc_release(&cc->cc_cid, cc->cc_sqecount);
first = last = NULL;
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(ctxt, &free);
ctxt->rw_node.next = first;
first = &ctxt->rw_node;
if (!last)
last = first;
}
if (first)
llist_add_batch(first, last, &rdma->sc_rw_ctxts);
}
static struct svc_rdma_write_info *
svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma,
const struct svc_rdma_chunk *chunk)
{
struct svc_rdma_write_info *info;
info = kzalloc_node(sizeof(*info), GFP_KERNEL,
ibdev_to_node(rdma->sc_cm_id->device));
if (!info)
return info;
info->wi_rdma = rdma;
info->wi_chunk = 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_async(struct work_struct *work)
{
struct svc_rdma_write_info *info;
info = container_of(work, struct svc_rdma_write_info, wi_work);
svc_rdma_cc_release(info->wi_rdma, &info->wi_cc, DMA_TO_DEVICE);
kfree(info);
}
static void svc_rdma_write_info_free(struct svc_rdma_write_info *info)
{
INIT_WORK(&info->wi_work, svc_rdma_write_info_free_async);
queue_work(svcrdma_wq, &info->wi_work);
}
/**
* svc_rdma_reply_chunk_release - Release Reply chunk I/O resources
* @rdma: controlling transport
* @ctxt: Send context that is being released
*/
void svc_rdma_reply_chunk_release(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt)
{
struct svc_rdma_chunk_ctxt *cc = &ctxt->sc_reply_info.wi_cc;
if (!cc->cc_sqecount)
return;
svc_rdma_cc_release(rdma, cc, DMA_TO_DEVICE);
}
/**
* svc_rdma_reply_done - Reply chunk Write completion handler
* @cq: controlling Completion Queue
* @wc: Work Completion report
*
* Pages under I/O are released by a subsequent Send completion.
*/
static void svc_rdma_reply_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 = cq->cq_context;
switch (wc->status) {
case IB_WC_SUCCESS:
trace_svcrdma_wc_reply(&cc->cc_cid);
return;
case IB_WC_WR_FLUSH_ERR:
trace_svcrdma_wc_reply_flush(wc, &cc->cc_cid);
break;
default:
trace_svcrdma_wc_reply_err(wc, &cc->cc_cid);
}
svc_xprt_deferred_close(&rdma->sc_xprt);
}
/**
* 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 svcxprt_rdma *rdma = cq->cq_context;
struct ib_cqe *cqe = wc->wr_cqe;
struct svc_rdma_chunk_ctxt *cc =
container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
struct svc_rdma_write_info *info =
container_of(cc, struct svc_rdma_write_info, wi_cc);
switch (wc->status) {
case IB_WC_SUCCESS:
trace_svcrdma_wc_write(&cc->cc_cid);
break;
case IB_WC_WR_FLUSH_ERR:
trace_svcrdma_wc_write_flush(wc, &cc->cc_cid);
break;
default:
trace_svcrdma_wc_write_err(wc, &cc->cc_cid);
}
svc_rdma_wake_send_waiters(rdma, cc->cc_sqecount);
if (unlikely(wc->status != IB_WC_SUCCESS))
svc_xprt_deferred_close(&rdma->sc_xprt);
svc_rdma_write_info_free(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 svcxprt_rdma *rdma = cq->cq_context;
struct ib_cqe *cqe = wc->wr_cqe;
struct svc_rdma_chunk_ctxt *cc =
container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
struct svc_rdma_recv_ctxt *ctxt;
svc_rdma_wake_send_waiters(rdma, cc->cc_sqecount);
ctxt = container_of(cc, struct svc_rdma_recv_ctxt, rc_cc);
switch (wc->status) {
case IB_WC_SUCCESS:
trace_svcrdma_wc_read(wc, &cc->cc_cid, ctxt->rc_readbytes,
cc->cc_posttime);
spin_lock(&rdma->sc_rq_dto_lock);
list_add_tail(&ctxt->rc_list, &rdma->sc_read_complete_q);
/* 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);
return;
case IB_WC_WR_FLUSH_ERR:
trace_svcrdma_wc_read_flush(wc, &cc->cc_cid);
break;
default:
trace_svcrdma_wc_read_err(wc, &cc->cc_cid);
}
/* The RDMA Read has flushed, so the incoming RPC message
* cannot be constructed and must be dropped. Signal the
* loss to the client by closing the connection.
*/
svc_rdma_cc_release(rdma, cc, DMA_FROM_DEVICE);
svc_rdma_recv_ctxt_put(rdma, ctxt);
svc_xprt_deferred_close(&rdma->sc_xprt);
}
/*
* 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 svcxprt_rdma *rdma,
struct svc_rdma_chunk_ctxt *cc)
{
struct ib_send_wr *first_wr;
const struct ib_send_wr *bad_wr;
struct list_head *tmp;
struct ib_cqe *cqe;
int ret;
might_sleep();
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) {
cc->cc_posttime = ktime_get();
ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
if (ret)
break;
return 0;
}
percpu_counter_inc(&svcrdma_stat_sq_starve);
trace_svcrdma_sq_full(rdma, &cc->cc_cid);
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, &cc->cc_cid);
} while (1);
trace_svcrdma_sq_post_err(rdma, &cc->cc_cid, ret);
svc_xprt_deferred_close(&rdma->sc_xprt);
/* 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;
const 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 = info->wi_rdma;
const struct svc_rdma_segment *seg;
struct svc_rdma_rw_ctxt *ctxt;
int ret;
do {
unsigned int write_len;
u64 offset;
if (info->wi_seg_no >= info->wi_chunk->ch_segcount)
goto out_overflow;
seg = &info->wi_chunk->ch_segments[info->wi_seg_no];
write_len = min(remaining, seg->rs_length - info->wi_seg_off);
if (!write_len)
goto out_overflow;
ctxt = svc_rdma_get_rw_ctxt(rdma,
(write_len >> PAGE_SHIFT) + 2);
if (!ctxt)
return -ENOMEM;
constructor(info, write_len, ctxt);
offset = seg->rs_offset + info->wi_seg_off;
ret = svc_rdma_rw_ctx_init(rdma, ctxt, offset, seg->rs_handle,
DMA_TO_DEVICE);
if (ret < 0)
return -EIO;
percpu_counter_inc(&svcrdma_stat_write);
list_add(&ctxt->rw_list, &cc->cc_rwctxts);
cc->cc_sqecount += ret;
if (write_len == seg->rs_length - info->wi_seg_off) {
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:
trace_svcrdma_small_wrch_err(&cc->cc_cid, remaining, info->wi_seg_no,
info->wi_chunk->ch_segcount);
return -E2BIG;
}
/**
* svc_rdma_iov_write - Construct RDMA Writes from an iov
* @info: pointer to write arguments
* @iov: kvec to write
*
* Returns:
* On success, returns zero
* %-E2BIG if the client-provided Write chunk is too small
* %-ENOMEM if a resource has been exhausted
* %-EIO if an rdma-rw error occurred
*/
static int svc_rdma_iov_write(struct svc_rdma_write_info *info,
const struct kvec *iov)
{
info->wi_base = iov->iov_base;
return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
iov->iov_len);
}
/**
* svc_rdma_pages_write - Construct RDMA Writes from pages
* @info: pointer to write arguments
* @xdr: xdr_buf with pages to write
* @offset: offset into the content of @xdr
* @length: number of bytes to write
*
* Returns:
* On success, returns zero
* %-E2BIG if the client-provided Write chunk is too small
* %-ENOMEM if a resource has been exhausted
* %-EIO if an rdma-rw error occurred
*/
static int svc_rdma_pages_write(struct svc_rdma_write_info *info,
const struct xdr_buf *xdr,
unsigned int offset,
unsigned long length)
{
info->wi_xdr = xdr;
info->wi_next_off = offset - xdr->head[0].iov_len;
return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
length);
}
/**
* svc_rdma_xb_write - Construct RDMA Writes to write an xdr_buf
* @xdr: xdr_buf to write
* @data: pointer to write arguments
*
* Returns:
* On success, returns zero
* %-E2BIG if the client-provided Write chunk is too small
* %-ENOMEM if a resource has been exhausted
* %-EIO if an rdma-rw error occurred
*/
static int svc_rdma_xb_write(const struct xdr_buf *xdr, void *data)
{
struct svc_rdma_write_info *info = data;
int ret;
if (xdr->head[0].iov_len) {
ret = svc_rdma_iov_write(info, &xdr->head[0]);
if (ret < 0)
return ret;
}
if (xdr->page_len) {
ret = svc_rdma_pages_write(info, xdr, xdr->head[0].iov_len,
xdr->page_len);
if (ret < 0)
return ret;
}
if (xdr->tail[0].iov_len) {
ret = svc_rdma_iov_write(info, &xdr->tail[0]);
if (ret < 0)
return ret;
}
return xdr->len;
}
static int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma,
const struct svc_rdma_chunk *chunk,
const struct xdr_buf *xdr)
{
struct svc_rdma_write_info *info;
struct svc_rdma_chunk_ctxt *cc;
struct xdr_buf payload;
int ret;
if (xdr_buf_subsegment(xdr, &payload, chunk->ch_position,
chunk->ch_payload_length))
return -EMSGSIZE;
info = svc_rdma_write_info_alloc(rdma, chunk);
if (!info)
return -ENOMEM;
cc = &info->wi_cc;
ret = svc_rdma_xb_write(&payload, info);
if (ret != payload.len)
goto out_err;
trace_svcrdma_post_write_chunk(&cc->cc_cid, cc->cc_sqecount);
ret = svc_rdma_post_chunk_ctxt(rdma, cc);
if (ret < 0)
goto out_err;
return 0;
out_err:
svc_rdma_write_info_free(info);
return ret;
}
/**
* svc_rdma_send_write_list - Send all chunks on the Write list
* @rdma: controlling RDMA transport
* @rctxt: Write list provisioned by the client
* @xdr: xdr_buf containing an RPC Reply message
*
* Returns zero on success, or a negative errno if one or more
* Write chunks could not be sent.
*/
int svc_rdma_send_write_list(struct svcxprt_rdma *rdma,
const struct svc_rdma_recv_ctxt *rctxt,
const struct xdr_buf *xdr)
{
struct svc_rdma_chunk *chunk;
int ret;
pcl_for_each_chunk(chunk, &rctxt->rc_write_pcl) {
if (!chunk->ch_payload_length)
break;
ret = svc_rdma_send_write_chunk(rdma, chunk, xdr);
if (ret < 0)
return ret;
}
return 0;
}
/**
* svc_rdma_prepare_reply_chunk - Construct WR chain for writing the Reply chunk
* @rdma: controlling RDMA transport
* @write_pcl: Write chunk list provided by client
* @reply_pcl: Reply chunk provided by client
* @sctxt: Send WR resources
* @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_prepare_reply_chunk(struct svcxprt_rdma *rdma,
const struct svc_rdma_pcl *write_pcl,
const struct svc_rdma_pcl *reply_pcl,
struct svc_rdma_send_ctxt *sctxt,
const struct xdr_buf *xdr)
{
struct svc_rdma_write_info *info = &sctxt->sc_reply_info;
struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
struct ib_send_wr *first_wr;
struct list_head *pos;
struct ib_cqe *cqe;
int ret;
info->wi_rdma = rdma;
info->wi_chunk = pcl_first_chunk(reply_pcl);
info->wi_seg_off = 0;
info->wi_seg_no = 0;
info->wi_cc.cc_cqe.done = svc_rdma_reply_done;
ret = pcl_process_nonpayloads(write_pcl, xdr,
svc_rdma_xb_write, info);
if (ret < 0)
return ret;
first_wr = sctxt->sc_wr_chain;
cqe = &cc->cc_cqe;
list_for_each(pos, &cc->cc_rwctxts) {
struct svc_rdma_rw_ctxt *rwc;
rwc = list_entry(pos, struct svc_rdma_rw_ctxt, rw_list);
first_wr = rdma_rw_ctx_wrs(&rwc->rw_ctx, rdma->sc_qp,
rdma->sc_port_num, cqe, first_wr);
cqe = NULL;
}
sctxt->sc_wr_chain = first_wr;
sctxt->sc_sqecount += cc->cc_sqecount;
trace_svcrdma_post_reply_chunk(&cc->cc_cid, cc->cc_sqecount);
return xdr->len;
}
/**
* svc_rdma_build_read_segment - Build RDMA Read WQEs to pull one RDMA segment
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
* @segment: co-ordinates of remote memory to be read
*
* Returns:
* %0: the Read WR chain was constructed successfully
* %-EINVAL: there were not enough rq_pages to finish
* %-ENOMEM: allocating a local resources failed
* %-EIO: a DMA mapping error occurred
*/
static int svc_rdma_build_read_segment(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head,
const struct svc_rdma_segment *segment)
{
struct svcxprt_rdma *rdma = svc_rdma_rqst_rdma(rqstp);
struct svc_rdma_chunk_ctxt *cc = &head->rc_cc;
unsigned int sge_no, seg_len, len;
struct svc_rdma_rw_ctxt *ctxt;
struct scatterlist *sg;
int ret;
len = segment->rs_length;
sge_no = PAGE_ALIGN(head->rc_pageoff + len) >> PAGE_SHIFT;
ctxt = svc_rdma_get_rw_ctxt(rdma, sge_no);
if (!ctxt)
return -ENOMEM;
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 - head->rc_pageoff);
if (!head->rc_pageoff)
head->rc_page_count++;
sg_set_page(sg, rqstp->rq_pages[head->rc_curpage],
seg_len, head->rc_pageoff);
sg = sg_next(sg);
head->rc_pageoff += seg_len;
if (head->rc_pageoff == PAGE_SIZE) {
head->rc_curpage++;
head->rc_pageoff = 0;
}
len -= seg_len;
if (len && ((head->rc_curpage + 1) > ARRAY_SIZE(rqstp->rq_pages)))
goto out_overrun;
}
ret = svc_rdma_rw_ctx_init(rdma, ctxt, segment->rs_offset,
segment->rs_handle, DMA_FROM_DEVICE);
if (ret < 0)
return -EIO;
percpu_counter_inc(&svcrdma_stat_read);
list_add(&ctxt->rw_list, &cc->cc_rwctxts);
cc->cc_sqecount += ret;
return 0;
out_overrun:
trace_svcrdma_page_overrun_err(&cc->cc_cid, head->rc_curpage);
return -EINVAL;
}
/**
* svc_rdma_build_read_chunk - Build RDMA Read WQEs to pull one RDMA chunk
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
* @chunk: Read chunk to pull
*
* Return values:
* %0: the Read WR chain was constructed successfully
* %-EINVAL: there were not enough resources to finish
* %-ENOMEM: allocating a local resources failed
* %-EIO: a DMA mapping error occurred
*/
static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head,
const struct svc_rdma_chunk *chunk)
{
const struct svc_rdma_segment *segment;
int ret;
ret = -EINVAL;
pcl_for_each_segment(segment, chunk) {
ret = svc_rdma_build_read_segment(rqstp, head, segment);
if (ret < 0)
break;
head->rc_readbytes += segment->rs_length;
}
return ret;
}
/**
* svc_rdma_copy_inline_range - Copy part of the inline content into pages
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
* @offset: offset into the Receive buffer of region to copy
* @remaining: length of region to copy
*
* Take a page at a time from rqstp->rq_pages and copy the inline
* content from the Receive buffer into that page. Update
* head->rc_curpage and head->rc_pageoff so that the next RDMA Read
* result will land contiguously with the copied content.
*
* Return values:
* %0: Inline content was successfully copied
* %-EINVAL: offset or length was incorrect
*/
static int svc_rdma_copy_inline_range(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head,
unsigned int offset,
unsigned int remaining)
{
unsigned char *dst, *src = head->rc_recv_buf;
unsigned int page_no, numpages;
numpages = PAGE_ALIGN(head->rc_pageoff + remaining) >> PAGE_SHIFT;
for (page_no = 0; page_no < numpages; page_no++) {
unsigned int page_len;
page_len = min_t(unsigned int, remaining,
PAGE_SIZE - head->rc_pageoff);
if (!head->rc_pageoff)
head->rc_page_count++;
dst = page_address(rqstp->rq_pages[head->rc_curpage]);
memcpy(dst + head->rc_curpage, src + offset, page_len);
head->rc_readbytes += page_len;
head->rc_pageoff += page_len;
if (head->rc_pageoff == PAGE_SIZE) {
head->rc_curpage++;
head->rc_pageoff = 0;
}
remaining -= page_len;
offset += page_len;
}
return -EINVAL;
}
/**
* svc_rdma_read_multiple_chunks - Construct RDMA Reads to pull data item Read chunks
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
*
* The chunk data lands in rqstp->rq_arg as a series of contiguous pages,
* like an incoming TCP call.
*
* Return values:
* %0: RDMA Read WQEs were successfully built
* %-EINVAL: client provided too many chunks or segments,
* %-ENOMEM: rdma_rw context pool was exhausted,
* %-ENOTCONN: posting failed (connection is lost),
* %-EIO: rdma_rw initialization failed (DMA mapping, etc).
*/
static noinline int
svc_rdma_read_multiple_chunks(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
const struct svc_rdma_pcl *pcl = &head->rc_read_pcl;
struct svc_rdma_chunk *chunk, *next;
unsigned int start, length;
int ret;
start = 0;
chunk = pcl_first_chunk(pcl);
length = chunk->ch_position;
ret = svc_rdma_copy_inline_range(rqstp, head, start, length);
if (ret < 0)
return ret;
pcl_for_each_chunk(chunk, pcl) {
ret = svc_rdma_build_read_chunk(rqstp, head, chunk);
if (ret < 0)
return ret;
next = pcl_next_chunk(pcl, chunk);
if (!next)
break;
start += length;
length = next->ch_position - head->rc_readbytes;
ret = svc_rdma_copy_inline_range(rqstp, head, start, length);
if (ret < 0)
return ret;
}
start += length;
length = head->rc_byte_len - start;
return svc_rdma_copy_inline_range(rqstp, head, start, length);
}
/**
* svc_rdma_read_data_item - Construct RDMA Reads to pull data item Read chunks
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
*
* The chunk data lands in the page list of rqstp->rq_arg.pages.
*
* Currently NFSD does not look at the rqstp->rq_arg.tail[0] kvec.
* Therefore, XDR round-up of the Read chunk and trailing
* inline content must both be added at the end of the pagelist.
*
* Return values:
* %0: RDMA Read WQEs were successfully built
* %-EINVAL: client provided too many chunks or segments,
* %-ENOMEM: rdma_rw context pool was exhausted,
* %-ENOTCONN: posting failed (connection is lost),
* %-EIO: rdma_rw initialization failed (DMA mapping, etc).
*/
static int svc_rdma_read_data_item(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
return svc_rdma_build_read_chunk(rqstp, head,
pcl_first_chunk(&head->rc_read_pcl));
}
/**
* svc_rdma_read_chunk_range - Build RDMA Read WRs for portion of a chunk
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
* @chunk: parsed Call chunk to pull
* @offset: offset of region to pull
* @length: length of region to pull
*
* Return values:
* %0: RDMA Read WQEs were successfully built
* %-EINVAL: there were not enough resources to finish
* %-ENOMEM: rdma_rw context pool was exhausted,
* %-ENOTCONN: posting failed (connection is lost),
* %-EIO: rdma_rw initialization failed (DMA mapping, etc).
*/
static int svc_rdma_read_chunk_range(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head,
const struct svc_rdma_chunk *chunk,
unsigned int offset, unsigned int length)
{
const struct svc_rdma_segment *segment;
int ret;
ret = -EINVAL;
pcl_for_each_segment(segment, chunk) {
struct svc_rdma_segment dummy;
if (offset > segment->rs_length) {
offset -= segment->rs_length;
continue;
}
dummy.rs_handle = segment->rs_handle;
dummy.rs_length = min_t(u32, length, segment->rs_length) - offset;
dummy.rs_offset = segment->rs_offset + offset;
ret = svc_rdma_build_read_segment(rqstp, head, &dummy);
if (ret < 0)
break;
head->rc_readbytes += dummy.rs_length;
length -= dummy.rs_length;
offset = 0;
}
return ret;
}
/**
* svc_rdma_read_call_chunk - Build RDMA Read WQEs to pull a Long Message
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
*
* Return values:
* %0: RDMA Read WQEs were successfully built
* %-EINVAL: there were not enough resources to finish
* %-ENOMEM: rdma_rw context pool was exhausted,
* %-ENOTCONN: posting failed (connection is lost),
* %-EIO: rdma_rw initialization failed (DMA mapping, etc).
*/
static int svc_rdma_read_call_chunk(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
const struct svc_rdma_chunk *call_chunk =
pcl_first_chunk(&head->rc_call_pcl);
const struct svc_rdma_pcl *pcl = &head->rc_read_pcl;
struct svc_rdma_chunk *chunk, *next;
unsigned int start, length;
int ret;
if (pcl_is_empty(pcl))
return svc_rdma_build_read_chunk(rqstp, head, call_chunk);
start = 0;
chunk = pcl_first_chunk(pcl);
length = chunk->ch_position;
ret = svc_rdma_read_chunk_range(rqstp, head, call_chunk,
start, length);
if (ret < 0)
return ret;
pcl_for_each_chunk(chunk, pcl) {
ret = svc_rdma_build_read_chunk(rqstp, head, chunk);
if (ret < 0)
return ret;
next = pcl_next_chunk(pcl, chunk);
if (!next)
break;
start += length;
length = next->ch_position - head->rc_readbytes;
ret = svc_rdma_read_chunk_range(rqstp, head, call_chunk,
start, length);
if (ret < 0)
return ret;
}
start += length;
length = call_chunk->ch_length - start;
return svc_rdma_read_chunk_range(rqstp, head, call_chunk,
start, length);
}
/**
* svc_rdma_read_special - Build RDMA Read WQEs to pull a Long Message
* @rqstp: RPC transaction context
* @head: context for ongoing I/O
*
* The start of the data lands in the first page just after the
* Transport header, and the rest lands in rqstp->rq_arg.pages.
*
* Assumptions:
* - A PZRC is never sent in an RDMA_MSG message, though it's
* allowed by spec.
*
* Return values:
* %0: RDMA Read WQEs were successfully built
* %-EINVAL: client provided too many chunks or segments,
* %-ENOMEM: rdma_rw context pool was exhausted,
* %-ENOTCONN: posting failed (connection is lost),
* %-EIO: rdma_rw initialization failed (DMA mapping, etc).
*/
static noinline int svc_rdma_read_special(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
return svc_rdma_read_call_chunk(rqstp, head);
}
/* Pages under I/O have been copied to head->rc_pages. Ensure that
* svc_xprt_release() does not put them when svc_rdma_recvfrom()
* returns. This has to be done after all Read WRs are constructed
* to properly handle a page that happens to be part of I/O on behalf
* of two different RDMA segments.
*
* Note: if the subsequent post_send fails, these pages have already
* been moved to head->rc_pages and thus will be cleaned up by
* svc_rdma_recv_ctxt_put().
*/
static void svc_rdma_clear_rqst_pages(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
unsigned int i;
for (i = 0; i < head->rc_page_count; i++) {
head->rc_pages[i] = rqstp->rq_pages[i];
rqstp->rq_pages[i] = NULL;
}
}
/**
* svc_rdma_process_read_list - Pull list of Read chunks from the client
* @rdma: controlling RDMA transport
* @rqstp: set of pages to use as Read sink buffers
* @head: pages under I/O collect here
*
* The RPC/RDMA protocol assumes that the upper layer's XDR decoders
* pull each Read chunk as they decode an incoming RPC message.
*
* On Linux, however, the server needs to have a fully-constructed RPC
* message in rqstp->rq_arg when there is a positive return code from
* ->xpo_recvfrom. So the Read list is safety-checked immediately when
* it is received, then here the whole Read list is pulled all at once.
* The ingress RPC message is fully reconstructed once all associated
* RDMA Reads have completed.
*
* Return values:
* %1: all needed RDMA Reads were posted successfully,
* %-EINVAL: client provided too many chunks or segments,
* %-ENOMEM: rdma_rw context pool was exhausted,
* %-ENOTCONN: posting failed (connection is lost),
* %-EIO: rdma_rw initialization failed (DMA mapping, etc).
*/
int svc_rdma_process_read_list(struct svcxprt_rdma *rdma,
struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
struct svc_rdma_chunk_ctxt *cc = &head->rc_cc;
int ret;
cc->cc_cqe.done = svc_rdma_wc_read_done;
cc->cc_sqecount = 0;
head->rc_pageoff = 0;
head->rc_curpage = 0;
head->rc_readbytes = 0;
if (pcl_is_empty(&head->rc_call_pcl)) {
if (head->rc_read_pcl.cl_count == 1)
ret = svc_rdma_read_data_item(rqstp, head);
else
ret = svc_rdma_read_multiple_chunks(rqstp, head);
} else
ret = svc_rdma_read_special(rqstp, head);
svc_rdma_clear_rqst_pages(rqstp, head);
if (ret < 0)
return ret;
trace_svcrdma_post_read_chunk(&cc->cc_cid, cc->cc_sqecount);
ret = svc_rdma_post_chunk_ctxt(rdma, cc);
return ret < 0 ? ret : 1;
}
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