linux-stable/net/sunrpc/xprtrdma/svc_rdma_rw.c
Chuck Lever 07a92d009f svcrdma: Convert rdma->sc_rw_ctxts to llist
Relieve contention on sc_rw_ctxt_lock by converting rdma->sc_rw_ctxts
to an llist.

The goal is to reduce the average overhead of Send completions,
because a transport's completion handlers are single-threaded on
one CPU core. This change reduces CPU utilization of each Send
completion by 2-3% on my server.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
2021-08-17 11:47:53 -04:00

1143 lines
31 KiB
C

// 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;
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 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(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
GFP_KERNEL);
if (!ctxt)
goto out_noctx;
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))
goto out_free;
return ctxt;
out_free:
kfree(ctxt);
out_noctx:
trace_svcrdma_no_rwctx_err(rdma, sges);
return NULL;
}
static void __svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
struct svc_rdma_rw_ctxt *ctxt,
struct llist_head *list)
{
sg_free_table_chained(&ctxt->rw_sg_table, SG_CHUNK_SIZE);
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(rdma, 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)) {
svc_rdma_put_rw_ctxt(rdma, ctxt);
trace_svcrdma_dma_map_rw_err(rdma, ctxt->rw_nents, ret);
}
return ret;
}
/* A chunk context tracks all I/O for moving one Read or Write
* chunk. This is 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 rpc_rdma_cid cc_cid;
struct ib_cqe cc_cqe;
struct svcxprt_rdma *cc_rdma;
struct list_head cc_rwctxts;
int cc_sqecount;
enum ib_wc_status cc_status;
struct completion cc_done;
};
static void svc_rdma_cc_cid_init(struct svcxprt_rdma *rdma,
struct rpc_rdma_cid *cid)
{
cid->ci_queue_id = rdma->sc_sq_cq->res.id;
cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids);
}
static void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
struct svc_rdma_chunk_ctxt *cc)
{
svc_rdma_cc_cid_init(rdma, &cc->cc_cid);
cc->cc_rdma = rdma;
INIT_LIST_HEAD(&cc->cc_rwctxts);
cc->cc_sqecount = 0;
}
/*
* The consumed rw_ctx's are cleaned and placed on a local llist so
* that only one atomic llist operation is needed to put them all
* back on the free list.
*/
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 llist_node *first, *last;
struct svc_rdma_rw_ctxt *ctxt;
LLIST_HEAD(free);
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(rdma, 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);
}
/* 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 {
const struct svc_rdma_chunk *wi_chunk;
/* write state of this chunk */
unsigned int wi_seg_off;
unsigned int wi_seg_no;
/* SGL constructor arguments */
const 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,
const struct svc_rdma_chunk *chunk)
{
struct svc_rdma_write_info *info;
info = kmalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return info;
info->wi_chunk = chunk;
info->wi_seg_off = 0;
info->wi_seg_no = 0;
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, &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);
}
/* State for pulling a Read chunk.
*/
struct svc_rdma_read_info {
struct svc_rqst *ri_rqst;
struct svc_rdma_recv_ctxt *ri_readctxt;
unsigned int ri_pageno;
unsigned int ri_pageoff;
unsigned int ri_totalbytes;
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;
trace_svcrdma_wc_read(wc, &cc->cc_cid);
svc_rdma_wake_send_waiters(rdma, cc->cc_sqecount);
cc->cc_status = wc->status;
complete(&cc->cc_done);
return;
}
/* 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 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);
if (ret)
break;
return 0;
}
percpu_counter_inc(&svcrdma_stat_sq_starve);
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);
trace_svcrdma_sq_post_err(rdma, 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 = cc->cc_rdma;
const struct svc_rdma_segment *seg;
struct svc_rdma_rw_ctxt *ctxt;
int ret;
do {
unsigned int write_len;
u64 offset;
seg = &info->wi_chunk->ch_segments[info->wi_seg_no];
if (!seg)
goto out_overflow;
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(rdma, 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;
}
/**
* svc_rdma_send_write_chunk - Write all segments in a Write chunk
* @rdma: controlling RDMA transport
* @chunk: Write chunk provided by the 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,
const struct svc_rdma_chunk *chunk,
const struct xdr_buf *xdr)
{
struct svc_rdma_write_info *info;
struct svc_rdma_chunk_ctxt *cc;
int ret;
info = svc_rdma_write_info_alloc(rdma, chunk);
if (!info)
return -ENOMEM;
cc = &info->wi_cc;
ret = svc_rdma_xb_write(xdr, info);
if (ret != xdr->len)
goto out_err;
trace_svcrdma_post_write_chunk(&cc->cc_cid, cc->cc_sqecount);
ret = svc_rdma_post_chunk_ctxt(cc);
if (ret < 0)
goto out_err;
return xdr->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
* @rctxt: Write and Reply chunks from client
* @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,
const struct svc_rdma_recv_ctxt *rctxt,
const struct xdr_buf *xdr)
{
struct svc_rdma_write_info *info;
struct svc_rdma_chunk_ctxt *cc;
struct svc_rdma_chunk *chunk;
int ret;
if (pcl_is_empty(&rctxt->rc_reply_pcl))
return 0;
chunk = pcl_first_chunk(&rctxt->rc_reply_pcl);
info = svc_rdma_write_info_alloc(rdma, chunk);
if (!info)
return -ENOMEM;
cc = &info->wi_cc;
ret = pcl_process_nonpayloads(&rctxt->rc_write_pcl, xdr,
svc_rdma_xb_write, info);
if (ret < 0)
goto out_err;
trace_svcrdma_post_reply_chunk(&cc->cc_cid, cc->cc_sqecount);
ret = svc_rdma_post_chunk_ctxt(cc);
if (ret < 0)
goto out_err;
return xdr->len;
out_err:
svc_rdma_write_info_free(info);
return ret;
}
/**
* svc_rdma_build_read_segment - Build RDMA Read WQEs to pull one RDMA segment
* @info: 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_rdma_read_info *info,
const struct svc_rdma_segment *segment)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
struct svc_rdma_chunk_ctxt *cc = &info->ri_cc;
struct svc_rqst *rqstp = info->ri_rqst;
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(info->ri_pageoff + len) >> PAGE_SHIFT;
ctxt = svc_rdma_get_rw_ctxt(cc->cc_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 - info->ri_pageoff);
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 = svc_rdma_rw_ctx_init(cc->cc_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_rdma, rqstp, info->ri_pageno);
return -EINVAL;
}
/**
* svc_rdma_build_read_chunk - Build RDMA Read WQEs to pull one RDMA chunk
* @info: 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_rdma_read_info *info,
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(info, segment);
if (ret < 0)
break;
info->ri_totalbytes += segment->rs_length;
}
return ret;
}
/**
* svc_rdma_copy_inline_range - Copy part of the inline content into pages
* @info: context for RDMA Reads
* @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
* info->ri_pageno and info->ri_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_rdma_read_info *info,
unsigned int offset,
unsigned int remaining)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
unsigned char *dst, *src = head->rc_recv_buf;
struct svc_rqst *rqstp = info->ri_rqst;
unsigned int page_no, numpages;
numpages = PAGE_ALIGN(info->ri_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 - info->ri_pageoff);
if (!info->ri_pageoff)
head->rc_page_count++;
dst = page_address(rqstp->rq_pages[info->ri_pageno]);
memcpy(dst + info->ri_pageno, src + offset, page_len);
info->ri_totalbytes += page_len;
info->ri_pageoff += page_len;
if (info->ri_pageoff == PAGE_SIZE) {
info->ri_pageno++;
info->ri_pageoff = 0;
}
remaining -= page_len;
offset += page_len;
}
return -EINVAL;
}
/**
* svc_rdma_read_multiple_chunks - Construct RDMA Reads to pull data item Read chunks
* @info: context for RDMA Reads
*
* 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_rdma_read_info *info)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
const struct svc_rdma_pcl *pcl = &head->rc_read_pcl;
struct xdr_buf *buf = &info->ri_rqst->rq_arg;
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(info, start, length);
if (ret < 0)
return ret;
pcl_for_each_chunk(chunk, pcl) {
ret = svc_rdma_build_read_chunk(info, chunk);
if (ret < 0)
return ret;
next = pcl_next_chunk(pcl, chunk);
if (!next)
break;
start += length;
length = next->ch_position - info->ri_totalbytes;
ret = svc_rdma_copy_inline_range(info, start, length);
if (ret < 0)
return ret;
}
start += length;
length = head->rc_byte_len - start;
ret = svc_rdma_copy_inline_range(info, start, length);
if (ret < 0)
return ret;
buf->len += info->ri_totalbytes;
buf->buflen += info->ri_totalbytes;
buf->head[0].iov_base = page_address(info->ri_rqst->rq_pages[0]);
buf->head[0].iov_len = min_t(size_t, PAGE_SIZE, info->ri_totalbytes);
buf->pages = &info->ri_rqst->rq_pages[1];
buf->page_len = info->ri_totalbytes - buf->head[0].iov_len;
return 0;
}
/**
* svc_rdma_read_data_item - Construct RDMA Reads to pull data item Read chunks
* @info: context for RDMA Reads
*
* 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_rdma_read_info *info)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
struct xdr_buf *buf = &info->ri_rqst->rq_arg;
struct svc_rdma_chunk *chunk;
unsigned int length;
int ret;
chunk = pcl_first_chunk(&head->rc_read_pcl);
ret = svc_rdma_build_read_chunk(info, chunk);
if (ret < 0)
goto out;
/* 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.
*/
buf->tail[0].iov_base = buf->head[0].iov_base + chunk->ch_position;
buf->tail[0].iov_len = buf->head[0].iov_len - chunk->ch_position;
buf->head[0].iov_len = chunk->ch_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.
*/
buf->pages = &info->ri_rqst->rq_pages[0];
length = xdr_align_size(chunk->ch_length);
buf->page_len = length;
buf->len += length;
buf->buflen += length;
out:
return ret;
}
/**
* svc_rdma_read_chunk_range - Build RDMA Read WQEs for portion of a chunk
* @info: context for RDMA Reads
* @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_rdma_read_info *info,
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(info, &dummy);
if (ret < 0)
break;
info->ri_totalbytes += 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
* @info: context for RDMA Reads
*
* 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_rdma_read_info *info)
{
struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
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(info, call_chunk);
start = 0;
chunk = pcl_first_chunk(pcl);
length = chunk->ch_position;
ret = svc_rdma_read_chunk_range(info, call_chunk, start, length);
if (ret < 0)
return ret;
pcl_for_each_chunk(chunk, pcl) {
ret = svc_rdma_build_read_chunk(info, chunk);
if (ret < 0)
return ret;
next = pcl_next_chunk(pcl, chunk);
if (!next)
break;
start += length;
length = next->ch_position - info->ri_totalbytes;
ret = svc_rdma_read_chunk_range(info, call_chunk,
start, length);
if (ret < 0)
return ret;
}
start += length;
length = call_chunk->ch_length - start;
return svc_rdma_read_chunk_range(info, call_chunk, start, length);
}
/**
* svc_rdma_read_special - Build RDMA Read WQEs to pull a Long Message
* @info: context for RDMA Reads
*
* 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_rdma_read_info *info)
{
struct xdr_buf *buf = &info->ri_rqst->rq_arg;
int ret;
ret = svc_rdma_read_call_chunk(info);
if (ret < 0)
goto out;
buf->len += info->ri_totalbytes;
buf->buflen += info->ri_totalbytes;
buf->head[0].iov_base = page_address(info->ri_rqst->rq_pages[0]);
buf->head[0].iov_len = min_t(size_t, PAGE_SIZE, info->ri_totalbytes);
buf->pages = &info->ri_rqst->rq_pages[1];
buf->page_len = info->ri_totalbytes - buf->head[0].iov_len;
out:
return ret;
}
/**
* 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_read_info *info;
struct svc_rdma_chunk_ctxt *cc;
int ret;
info = svc_rdma_read_info_alloc(rdma);
if (!info)
return -ENOMEM;
cc = &info->ri_cc;
info->ri_rqst = rqstp;
info->ri_readctxt = head;
info->ri_pageno = 0;
info->ri_pageoff = 0;
info->ri_totalbytes = 0;
if (pcl_is_empty(&head->rc_call_pcl)) {
if (head->rc_read_pcl.cl_count == 1)
ret = svc_rdma_read_data_item(info);
else
ret = svc_rdma_read_multiple_chunks(info);
} else
ret = svc_rdma_read_special(info);
if (ret < 0)
goto out_err;
trace_svcrdma_post_read_chunk(&cc->cc_cid, cc->cc_sqecount);
init_completion(&cc->cc_done);
ret = svc_rdma_post_chunk_ctxt(cc);
if (ret < 0)
goto out_err;
ret = 1;
wait_for_completion(&cc->cc_done);
if (cc->cc_status != IB_WC_SUCCESS)
ret = -EIO;
/* rq_respages starts after the last arg page */
rqstp->rq_respages = &rqstp->rq_pages[head->rc_page_count];
rqstp->rq_next_page = rqstp->rq_respages + 1;
/* Ensure svc_rdma_recv_ctxt_put() does not try to release pages */
head->rc_page_count = 0;
out_err:
svc_rdma_read_info_free(info);
return ret;
}