--- /dev/null
+/*
+ * Copyright (c) 2016 Oracle. All rights reserved.
+ *
+ * Use the core R/W API to move RPC-over-RDMA Read and Write chunks.
+ */
+
+#include <linux/sunrpc/rpc_rdma.h>
+#include <linux/sunrpc/svc_rdma.h>
+#include <linux/sunrpc/debug.h>
+
+#include <rdma/rw.h>
+
+#define RPCDBG_FACILITY RPCDBG_SVCXPRT
+
+/* Each R/W context contains state for one chain of RDMA Read or
+ * Write Work Requests.
+ *
+ * Each WR chain handles a single contiguous server-side buffer,
+ * because scatterlist entries after the first have to start on
+ * page alignment. xdr_buf iovecs cannot guarantee alignment.
+ *
+ * Each WR chain handles only one R_key. Each RPC-over-RDMA segment
+ * from a client may contain a unique R_key, so each WR chain moves
+ * up to one segment at a time.
+ *
+ * The scatterlist makes this data structure over 4KB in size. To
+ * make it less likely to fail, and to handle the allocation for
+ * smaller I/O requests without disabling bottom-halves, these
+ * contexts are created on demand, but cached and reused until the
+ * controlling svcxprt_rdma is destroyed.
+ */
+struct svc_rdma_rw_ctxt {
+ struct list_head rw_list;
+ struct rdma_rw_ctx rw_ctx;
+ int rw_nents;
+ struct sg_table rw_sg_table;
+ struct scatterlist rw_first_sgl[0];
+};
+
+static inline struct svc_rdma_rw_ctxt *
+svc_rdma_next_ctxt(struct list_head *list)
+{
+ return list_first_entry_or_null(list, struct svc_rdma_rw_ctxt,
+ rw_list);
+}
+
+static struct svc_rdma_rw_ctxt *
+svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
+{
+ struct svc_rdma_rw_ctxt *ctxt;
+
+ spin_lock(&rdma->sc_rw_ctxt_lock);
+
+ ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts);
+ if (ctxt) {
+ list_del(&ctxt->rw_list);
+ spin_unlock(&rdma->sc_rw_ctxt_lock);
+ } else {
+ spin_unlock(&rdma->sc_rw_ctxt_lock);
+ ctxt = kmalloc(sizeof(*ctxt) +
+ SG_CHUNK_SIZE * sizeof(struct scatterlist),
+ GFP_KERNEL);
+ if (!ctxt)
+ goto out;
+ INIT_LIST_HEAD(&ctxt->rw_list);
+ }
+
+ ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl;
+ if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges,
+ ctxt->rw_sg_table.sgl)) {
+ kfree(ctxt);
+ ctxt = NULL;
+ }
+out:
+ return ctxt;
+}
+
+static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
+ struct svc_rdma_rw_ctxt *ctxt)
+{
+ sg_free_table_chained(&ctxt->rw_sg_table, true);
+
+ spin_lock(&rdma->sc_rw_ctxt_lock);
+ list_add(&ctxt->rw_list, &rdma->sc_rw_ctxts);
+ spin_unlock(&rdma->sc_rw_ctxt_lock);
+}
+
+/**
+ * svc_rdma_destroy_rw_ctxts - Free accumulated R/W contexts
+ * @rdma: transport about to be destroyed
+ *
+ */
+void svc_rdma_destroy_rw_ctxts(struct svcxprt_rdma *rdma)
+{
+ struct svc_rdma_rw_ctxt *ctxt;
+
+ while ((ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts)) != NULL) {
+ list_del(&ctxt->rw_list);
+ kfree(ctxt);
+ }
+}
+
+/* A chunk context tracks all I/O for moving one Read or Write
+ * chunk. This is a a set of rdma_rw's that handle data movement
+ * for all segments of one chunk.
+ *
+ * These are small, acquired with a single allocator call, and
+ * no more than one is needed per chunk. They are allocated on
+ * demand, and not cached.
+ */
+struct svc_rdma_chunk_ctxt {
+ struct ib_cqe cc_cqe;
+ struct svcxprt_rdma *cc_rdma;
+ struct list_head cc_rwctxts;
+ int cc_sqecount;
+ enum dma_data_direction cc_dir;
+};
+
+static void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
+ struct svc_rdma_chunk_ctxt *cc,
+ enum dma_data_direction dir)
+{
+ cc->cc_rdma = rdma;
+ svc_xprt_get(&rdma->sc_xprt);
+
+ INIT_LIST_HEAD(&cc->cc_rwctxts);
+ cc->cc_sqecount = 0;
+ cc->cc_dir = dir;
+}
+
+static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc)
+{
+ struct svcxprt_rdma *rdma = cc->cc_rdma;
+ struct svc_rdma_rw_ctxt *ctxt;
+
+ while ((ctxt = svc_rdma_next_ctxt(&cc->cc_rwctxts)) != NULL) {
+ list_del(&ctxt->rw_list);
+
+ rdma_rw_ctx_destroy(&ctxt->rw_ctx, rdma->sc_qp,
+ rdma->sc_port_num, ctxt->rw_sg_table.sgl,
+ ctxt->rw_nents, cc->cc_dir);
+ svc_rdma_put_rw_ctxt(rdma, ctxt);
+ }
+ svc_xprt_put(&rdma->sc_xprt);
+}
+
+/* State for sending a Write or Reply chunk.
+ * - Tracks progress of writing one chunk over all its segments
+ * - Stores arguments for the SGL constructor functions
+ */
+struct svc_rdma_write_info {
+ /* write state of this chunk */
+ unsigned int wi_seg_off;
+ unsigned int wi_seg_no;
+ unsigned int wi_nsegs;
+ __be32 *wi_segs;
+
+ /* SGL constructor arguments */
+ struct xdr_buf *wi_xdr;
+ unsigned char *wi_base;
+ unsigned int wi_next_off;
+
+ struct svc_rdma_chunk_ctxt wi_cc;
+};
+
+static struct svc_rdma_write_info *
+svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma, __be32 *chunk)
+{
+ struct svc_rdma_write_info *info;
+
+ info = kmalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return info;
+
+ info->wi_seg_off = 0;
+ info->wi_seg_no = 0;
+ info->wi_nsegs = be32_to_cpup(++chunk);
+ info->wi_segs = ++chunk;
+ svc_rdma_cc_init(rdma, &info->wi_cc, DMA_TO_DEVICE);
+ return info;
+}
+
+static void svc_rdma_write_info_free(struct svc_rdma_write_info *info)
+{
+ svc_rdma_cc_release(&info->wi_cc);
+ kfree(info);
+}
+
+/**
+ * svc_rdma_write_done - Write chunk completion
+ * @cq: controlling Completion Queue
+ * @wc: Work Completion
+ *
+ * Pages under I/O are freed by a subsequent Send completion.
+ */
+static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+ struct ib_cqe *cqe = wc->wr_cqe;
+ struct svc_rdma_chunk_ctxt *cc =
+ container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
+ struct svcxprt_rdma *rdma = cc->cc_rdma;
+ struct svc_rdma_write_info *info =
+ container_of(cc, struct svc_rdma_write_info, wi_cc);
+
+ atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
+ wake_up(&rdma->sc_send_wait);
+
+ if (unlikely(wc->status != IB_WC_SUCCESS)) {
+ set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
+ if (wc->status != IB_WC_WR_FLUSH_ERR)
+ pr_err("svcrdma: write ctx: %s (%u/0x%x)\n",
+ ib_wc_status_msg(wc->status),
+ wc->status, wc->vendor_err);
+ }
+
+ svc_rdma_write_info_free(info);
+}
+
+/* This function sleeps when the transport's Send Queue is congested.
+ *
+ * Assumptions:
+ * - If ib_post_send() succeeds, only one completion is expected,
+ * even if one or more WRs are flushed. This is true when posting
+ * an rdma_rw_ctx or when posting a single signaled WR.
+ */
+static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
+{
+ struct svcxprt_rdma *rdma = cc->cc_rdma;
+ struct svc_xprt *xprt = &rdma->sc_xprt;
+ struct ib_send_wr *first_wr, *bad_wr;
+ struct list_head *tmp;
+ struct ib_cqe *cqe;
+ int ret;
+
+ first_wr = NULL;
+ cqe = &cc->cc_cqe;
+ list_for_each(tmp, &cc->cc_rwctxts) {
+ struct svc_rdma_rw_ctxt *ctxt;
+
+ ctxt = list_entry(tmp, struct svc_rdma_rw_ctxt, rw_list);
+ first_wr = rdma_rw_ctx_wrs(&ctxt->rw_ctx, rdma->sc_qp,
+ rdma->sc_port_num, cqe, first_wr);
+ cqe = NULL;
+ }
+
+ do {
+ if (atomic_sub_return(cc->cc_sqecount,
+ &rdma->sc_sq_avail) > 0) {
+ ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
+ if (ret)
+ break;
+ return 0;
+ }
+
+ atomic_inc(&rdma_stat_sq_starve);
+ atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
+ wait_event(rdma->sc_send_wait,
+ atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
+ } while (1);
+
+ pr_err("svcrdma: ib_post_send failed (%d)\n", ret);
+ set_bit(XPT_CLOSE, &xprt->xpt_flags);
+
+ /* If even one was posted, there will be a completion. */
+ if (bad_wr != first_wr)
+ return 0;
+
+ atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
+ wake_up(&rdma->sc_send_wait);
+ return -ENOTCONN;
+}
+
+/* Build and DMA-map an SGL that covers one kvec in an xdr_buf
+ */
+static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info,
+ unsigned int len,
+ struct svc_rdma_rw_ctxt *ctxt)
+{
+ struct scatterlist *sg = ctxt->rw_sg_table.sgl;
+
+ sg_set_buf(&sg[0], info->wi_base, len);
+ info->wi_base += len;
+
+ ctxt->rw_nents = 1;
+}
+
+/* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist.
+ */
+static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info,
+ unsigned int remaining,
+ struct svc_rdma_rw_ctxt *ctxt)
+{
+ unsigned int sge_no, sge_bytes, page_off, page_no;
+ struct xdr_buf *xdr = info->wi_xdr;
+ struct scatterlist *sg;
+ struct page **page;
+
+ page_off = (info->wi_next_off + xdr->page_base) & ~PAGE_MASK;
+ page_no = (info->wi_next_off + xdr->page_base) >> PAGE_SHIFT;
+ page = xdr->pages + page_no;
+ info->wi_next_off += remaining;
+ sg = ctxt->rw_sg_table.sgl;
+ sge_no = 0;
+ do {
+ sge_bytes = min_t(unsigned int, remaining,
+ PAGE_SIZE - page_off);
+ sg_set_page(sg, *page, sge_bytes, page_off);
+
+ remaining -= sge_bytes;
+ sg = sg_next(sg);
+ page_off = 0;
+ sge_no++;
+ page++;
+ } while (remaining);
+
+ ctxt->rw_nents = sge_no;
+}
+
+/* Construct RDMA Write WRs to send a portion of an xdr_buf containing
+ * an RPC Reply.
+ */
+static int
+svc_rdma_build_writes(struct svc_rdma_write_info *info,
+ void (*constructor)(struct svc_rdma_write_info *info,
+ unsigned int len,
+ struct svc_rdma_rw_ctxt *ctxt),
+ unsigned int remaining)
+{
+ struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
+ struct svcxprt_rdma *rdma = cc->cc_rdma;
+ struct svc_rdma_rw_ctxt *ctxt;
+ __be32 *seg;
+ int ret;
+
+ cc->cc_cqe.done = svc_rdma_write_done;
+ seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz;
+ do {
+ unsigned int write_len;
+ u32 seg_length, seg_handle;
+ u64 seg_offset;
+
+ if (info->wi_seg_no >= info->wi_nsegs)
+ goto out_overflow;
+
+ seg_handle = be32_to_cpup(seg);
+ seg_length = be32_to_cpup(seg + 1);
+ xdr_decode_hyper(seg + 2, &seg_offset);
+ seg_offset += info->wi_seg_off;
+
+ write_len = min(remaining, seg_length - info->wi_seg_off);
+ ctxt = svc_rdma_get_rw_ctxt(rdma,
+ (write_len >> PAGE_SHIFT) + 2);
+ if (!ctxt)
+ goto out_noctx;
+
+ constructor(info, write_len, ctxt);
+ ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp,
+ rdma->sc_port_num, ctxt->rw_sg_table.sgl,
+ ctxt->rw_nents, 0, seg_offset,
+ seg_handle, DMA_TO_DEVICE);
+ if (ret < 0)
+ goto out_initerr;
+
+ list_add(&ctxt->rw_list, &cc->cc_rwctxts);
+ cc->cc_sqecount += ret;
+ if (write_len == seg_length - info->wi_seg_off) {
+ seg += 4;
+ info->wi_seg_no++;
+ info->wi_seg_off = 0;
+ } else {
+ info->wi_seg_off += write_len;
+ }
+ remaining -= write_len;
+ } while (remaining);
+
+ return 0;
+
+out_overflow:
+ dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
+ info->wi_nsegs);
+ return -E2BIG;
+
+out_noctx:
+ dprintk("svcrdma: no R/W ctxs available\n");
+ return -ENOMEM;
+
+out_initerr:
+ svc_rdma_put_rw_ctxt(rdma, ctxt);
+ pr_err("svcrdma: failed to map pagelist (%d)\n", ret);
+ return -EIO;
+}
+
+/* Send one of an xdr_buf's kvecs by itself. To send a Reply
+ * chunk, the whole RPC Reply is written back to the client.
+ * This function writes either the head or tail of the xdr_buf
+ * containing the Reply.
+ */
+static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
+ struct kvec *vec)
+{
+ info->wi_base = vec->iov_base;
+ return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
+ vec->iov_len);
+}
+
+/* Send an xdr_buf's page list by itself. A Write chunk is
+ * just the page list. a Reply chunk is the head, page list,
+ * and tail. This function is shared between the two types
+ * of chunk.
+ */
+static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
+ struct xdr_buf *xdr)
+{
+ info->wi_xdr = xdr;
+ info->wi_next_off = 0;
+ return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
+ xdr->page_len);
+}
+
+/**
+ * svc_rdma_send_write_chunk - Write all segments in a Write chunk
+ * @rdma: controlling RDMA transport
+ * @wr_ch: Write chunk provided by client
+ * @xdr: xdr_buf containing the data payload
+ *
+ * Returns a non-negative number of bytes the chunk consumed, or
+ * %-E2BIG if the payload was larger than the Write chunk,
+ * %-ENOMEM if rdma_rw context pool was exhausted,
+ * %-ENOTCONN if posting failed (connection is lost),
+ * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
+ */
+int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
+ struct xdr_buf *xdr)
+{
+ struct svc_rdma_write_info *info;
+ int ret;
+
+ if (!xdr->page_len)
+ return 0;
+
+ info = svc_rdma_write_info_alloc(rdma, wr_ch);
+ if (!info)
+ return -ENOMEM;
+
+ ret = svc_rdma_send_xdr_pagelist(info, xdr);
+ if (ret < 0)
+ goto out_err;
+
+ ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
+ if (ret < 0)
+ goto out_err;
+ return xdr->page_len;
+
+out_err:
+ svc_rdma_write_info_free(info);
+ return ret;
+}
+
+/**
+ * svc_rdma_send_reply_chunk - Write all segments in the Reply chunk
+ * @rdma: controlling RDMA transport
+ * @rp_ch: Reply chunk provided by client
+ * @writelist: true if client provided a Write list
+ * @xdr: xdr_buf containing an RPC Reply
+ *
+ * Returns a non-negative number of bytes the chunk consumed, or
+ * %-E2BIG if the payload was larger than the Reply chunk,
+ * %-ENOMEM if rdma_rw context pool was exhausted,
+ * %-ENOTCONN if posting failed (connection is lost),
+ * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
+ */
+int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch,
+ bool writelist, struct xdr_buf *xdr)
+{
+ struct svc_rdma_write_info *info;
+ int consumed, ret;
+
+ info = svc_rdma_write_info_alloc(rdma, rp_ch);
+ if (!info)
+ return -ENOMEM;
+
+ ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
+ if (ret < 0)
+ goto out_err;
+ consumed = xdr->head[0].iov_len;
+
+ /* Send the page list in the Reply chunk only if the
+ * client did not provide Write chunks.
+ */
+ if (!writelist && xdr->page_len) {
+ ret = svc_rdma_send_xdr_pagelist(info, xdr);
+ if (ret < 0)
+ goto out_err;
+ consumed += xdr->page_len;
+ }
+
+ if (xdr->tail[0].iov_len) {
+ ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
+ if (ret < 0)
+ goto out_err;
+ consumed += xdr->tail[0].iov_len;
+ }
+
+ ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
+ if (ret < 0)
+ goto out_err;
+ return consumed;
+
+out_err:
+ svc_rdma_write_info_free(info);
+ return ret;
+}
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff