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Release 4.11 net/sunrpc/xprtrdma/frwr_ops.c

/*
 * Copyright (c) 2015 Oracle.  All rights reserved.
 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
 */

/* Lightweight memory registration using Fast Registration Work
 * Requests (FRWR). Also referred to sometimes as FRMR mode.
 *
 * FRWR features ordered asynchronous registration and deregistration
 * of arbitrarily sized memory regions. This is the fastest and safest
 * but most complex memory registration mode.
 */

/* Normal operation
 *
 * A Memory Region is prepared for RDMA READ or WRITE using a FAST_REG
 * Work Request (frmr_op_map). When the RDMA operation is finished, this
 * Memory Region is invalidated using a LOCAL_INV Work Request
 * (frmr_op_unmap).
 *
 * Typically these Work Requests are not signaled, and neither are RDMA
 * SEND Work Requests (with the exception of signaling occasionally to
 * prevent provider work queue overflows). This greatly reduces HCA
 * interrupt workload.
 *
 * As an optimization, frwr_op_unmap marks MRs INVALID before the
 * LOCAL_INV WR is posted. If posting succeeds, the MR is placed on
 * rb_mws immediately so that no work (like managing a linked list
 * under a spinlock) is needed in the completion upcall.
 *
 * But this means that frwr_op_map() can occasionally encounter an MR
 * that is INVALID but the LOCAL_INV WR has not completed. Work Queue
 * ordering prevents a subsequent FAST_REG WR from executing against
 * that MR while it is still being invalidated.
 */

/* Transport recovery
 *
 * ->op_map and the transport connect worker cannot run at the same
 * time, but ->op_unmap can fire while the transport connect worker
 * is running. Thus MR recovery is handled in ->op_map, to guarantee
 * that recovered MRs are owned by a sending RPC, and not one where
 * ->op_unmap could fire at the same time transport reconnect is
 * being done.
 *
 * When the underlying transport disconnects, MRs are left in one of
 * four states:
 *
 * INVALID:     The MR was not in use before the QP entered ERROR state.
 *
 * VALID:       The MR was registered before the QP entered ERROR state.
 *
 * FLUSHED_FR:  The MR was being registered when the QP entered ERROR
 *              state, and the pending WR was flushed.
 *
 * FLUSHED_LI:  The MR was being invalidated when the QP entered ERROR
 *              state, and the pending WR was flushed.
 *
 * When frwr_op_map encounters FLUSHED and VALID MRs, they are recovered
 * with ib_dereg_mr and then are re-initialized. Because MR recovery
 * allocates fresh resources, it is deferred to a workqueue, and the
 * recovered MRs are placed back on the rb_mws list when recovery is
 * complete. frwr_op_map allocates another MR for the current RPC while
 * the broken MR is reset.
 *
 * To ensure that frwr_op_map doesn't encounter an MR that is marked
 * INVALID but that is about to be flushed due to a previous transport
 * disconnect, the transport connect worker attempts to drain all
 * pending send queue WRs before the transport is reconnected.
 */

#include <linux/sunrpc/rpc_rdma.h>

#include "xprt_rdma.h"

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)

# define RPCDBG_FACILITY	RPCDBG_TRANS
#endif


bool frwr_is_supported(struct rpcrdma_ia *ia) { struct ib_device_attr *attrs = &ia->ri_device->attrs; if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS)) goto out_not_supported; if (attrs->max_fast_reg_page_list_len == 0) goto out_not_supported; return true; out_not_supported: pr_info("rpcrdma: 'frwr' mode is not supported by device %s\n", ia->ri_device->name); return false; }

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static int frwr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mw *r) { unsigned int depth = ia->ri_max_frmr_depth; struct rpcrdma_frmr *f = &r->frmr; int rc; f->fr_mr = ib_alloc_mr(ia->ri_pd, ia->ri_mrtype, depth); if (IS_ERR(f->fr_mr)) goto out_mr_err; r->mw_sg = kcalloc(depth, sizeof(*r->mw_sg), GFP_KERNEL); if (!r->mw_sg) goto out_list_err; sg_init_table(r->mw_sg, depth); init_completion(&f->fr_linv_done); return 0; out_mr_err: rc = PTR_ERR(f->fr_mr); dprintk("RPC: %s: ib_alloc_mr status %i\n", __func__, rc); return rc; out_list_err: rc = -ENOMEM; dprintk("RPC: %s: sg allocation failure\n", __func__); ib_dereg_mr(f->fr_mr); return rc; }

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static void frwr_op_release_mr(struct rpcrdma_mw *r) { int rc; /* Ensure MW is not on any rl_registered list */ if (!list_empty(&r->mw_list)) list_del(&r->mw_list); rc = ib_dereg_mr(r->frmr.fr_mr); if (rc) pr_err("rpcrdma: final ib_dereg_mr for %p returned %i\n", r, rc); kfree(r->mw_sg); kfree(r); }

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static int __frwr_reset_mr(struct rpcrdma_ia *ia, struct rpcrdma_mw *r) { struct rpcrdma_frmr *f = &r->frmr; int rc; rc = ib_dereg_mr(f->fr_mr); if (rc) { pr_warn("rpcrdma: ib_dereg_mr status %d, frwr %p orphaned\n", rc, r); return rc; } f->fr_mr = ib_alloc_mr(ia->ri_pd, ia->ri_mrtype, ia->ri_max_frmr_depth); if (IS_ERR(f->fr_mr)) { pr_warn("rpcrdma: ib_alloc_mr status %ld, frwr %p orphaned\n", PTR_ERR(f->fr_mr), r); return PTR_ERR(f->fr_mr); } dprintk("RPC: %s: recovered FRMR %p\n", __func__, f); f->fr_state = FRMR_IS_INVALID; return 0; }

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Chuck Lever12498.41%583.33%
Sagi Grimberg21.59%116.67%
Total126100.00%6100.00%

/* Reset of a single FRMR. Generate a fresh rkey by replacing the MR. */
static void frwr_op_recover_mr(struct rpcrdma_mw *mw) { enum rpcrdma_frmr_state state = mw->frmr.fr_state; struct rpcrdma_xprt *r_xprt = mw->mw_xprt; struct rpcrdma_ia *ia = &r_xprt->rx_ia; int rc; rc = __frwr_reset_mr(ia, mw); if (state != FRMR_FLUSHED_LI) ib_dma_unmap_sg(ia->ri_device, mw->mw_sg, mw->mw_nents, mw->mw_dir); if (rc) goto out_release; rpcrdma_put_mw(r_xprt, mw); r_xprt->rx_stats.mrs_recovered++; return; out_release: pr_err("rpcrdma: FRMR reset failed %d, %p release\n", rc, mw); r_xprt->rx_stats.mrs_orphaned++; spin_lock(&r_xprt->rx_buf.rb_mwlock); list_del(&mw->mw_all); spin_unlock(&r_xprt->rx_buf.rb_mwlock); frwr_op_release_mr(mw); }

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Chuck Lever150100.00%7100.00%
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static int frwr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep, struct rpcrdma_create_data_internal *cdata) { struct ib_device_attr *attrs = &ia->ri_device->attrs; int depth, delta; ia->ri_mrtype = IB_MR_TYPE_MEM_REG; if (attrs->device_cap_flags & IB_DEVICE_SG_GAPS_REG) ia->ri_mrtype = IB_MR_TYPE_SG_GAPS; ia->ri_max_frmr_depth = min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS, attrs->max_fast_reg_page_list_len); dprintk("RPC: %s: device's max FR page list len = %u\n", __func__, ia->ri_max_frmr_depth); /* Add room for frmr register and invalidate WRs. * 1. FRMR reg WR for head * 2. FRMR invalidate WR for head * 3. N FRMR reg WRs for pagelist * 4. N FRMR invalidate WRs for pagelist * 5. FRMR reg WR for tail * 6. FRMR invalidate WR for tail * 7. The RDMA_SEND WR */ depth = 7; /* Calculate N if the device max FRMR depth is smaller than * RPCRDMA_MAX_DATA_SEGS. */ if (ia->ri_max_frmr_depth < RPCRDMA_MAX_DATA_SEGS) { delta = RPCRDMA_MAX_DATA_SEGS - ia->ri_max_frmr_depth; do { depth += 2; /* FRMR reg + invalidate */ delta -= ia->ri_max_frmr_depth; } while (delta > 0); } ep->rep_attr.cap.max_send_wr *= depth; if (ep->rep_attr.cap.max_send_wr > attrs->max_qp_wr) { cdata->max_requests = attrs->max_qp_wr / depth; if (!cdata->max_requests) return -EINVAL; ep->rep_attr.cap.max_send_wr = cdata->max_requests * depth; } ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS / ia->ri_max_frmr_depth); return 0; }

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Chuck Lever20299.02%583.33%
Or Gerlitz20.98%116.67%
Total204100.00%6100.00%

/* FRWR mode conveys a list of pages per chunk segment. The * maximum length of that list is the FRWR page list depth. */
static size_t frwr_op_maxpages(struct rpcrdma_xprt *r_xprt) { struct rpcrdma_ia *ia = &r_xprt->rx_ia; return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS, RPCRDMA_MAX_HDR_SEGS * ia->ri_max_frmr_depth); }

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Chuck Lever31100.00%2100.00%
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static void __frwr_sendcompletion_flush(struct ib_wc *wc, const char *wr) { if (wc->status != IB_WC_WR_FLUSH_ERR) pr_err("rpcrdma: %s: %s (%u/0x%x)\n", wr, ib_wc_status_msg(wc->status), wc->status, wc->vendor_err); }

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Chuck Lever46100.00%3100.00%
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/** * frwr_wc_fastreg - Invoked by RDMA provider for each polled FastReg WC * @cq: completion queue (ignored) * @wc: completed WR * */
static void frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc) { struct rpcrdma_frmr *frmr; struct ib_cqe *cqe; /* WARNING: Only wr_cqe and status are reliable at this point */ if (wc->status != IB_WC_SUCCESS) { cqe = wc->wr_cqe; frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe); frmr->fr_state = FRMR_FLUSHED_FR; __frwr_sendcompletion_flush(wc, "fastreg"); } }

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Chuck Lever5783.82%375.00%
Steve Wise1116.18%125.00%
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/** * frwr_wc_localinv - Invoked by RDMA provider for each polled LocalInv WC * @cq: completion queue (ignored) * @wc: completed WR * */
static void frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc) { struct rpcrdma_frmr *frmr; struct ib_cqe *cqe; /* WARNING: Only wr_cqe and status are reliable at this point */ if (wc->status != IB_WC_SUCCESS) { cqe = wc->wr_cqe; frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe); frmr->fr_state = FRMR_FLUSHED_LI; __frwr_sendcompletion_flush(wc, "localinv"); } }

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Chuck Lever6595.59%375.00%
Sagi Grimberg34.41%125.00%
Total68100.00%4100.00%

/** * frwr_wc_localinv - Invoked by RDMA provider for each polled LocalInv WC * @cq: completion queue (ignored) * @wc: completed WR * * Awaken anyone waiting for an MR to finish being fenced. */
static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc) { struct rpcrdma_frmr *frmr; struct ib_cqe *cqe; /* WARNING: Only wr_cqe and status are reliable at this point */ cqe = wc->wr_cqe; frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe); if (wc->status != IB_WC_SUCCESS) { frmr->fr_state = FRMR_FLUSHED_LI; __frwr_sendcompletion_flush(wc, "localinv"); } complete(&frmr->fr_linv_done); }

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Chuck Lever7598.68%480.00%
Daniel Wagner11.32%120.00%
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/* Post a REG_MR Work Request to register a memory region * for remote access via RDMA READ or RDMA WRITE. */
static int frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg, int nsegs, bool writing, struct rpcrdma_mw **out) { struct rpcrdma_ia *ia = &r_xprt->rx_ia; bool holes_ok = ia->ri_mrtype == IB_MR_TYPE_SG_GAPS; struct rpcrdma_mw *mw; struct rpcrdma_frmr *frmr; struct ib_mr *mr; struct ib_reg_wr *reg_wr; struct ib_send_wr *bad_wr; int rc, i, n, dma_nents; u8 key; mw = NULL; do { if (mw) rpcrdma_defer_mr_recovery(mw); mw = rpcrdma_get_mw(r_xprt); if (!mw) return -ENOBUFS; } while (mw->frmr.fr_state != FRMR_IS_INVALID); frmr = &mw->frmr; frmr->fr_state = FRMR_IS_VALID; mr = frmr->fr_mr; reg_wr = &frmr->fr_regwr; if (nsegs > ia->ri_max_frmr_depth) nsegs = ia->ri_max_frmr_depth; for (i = 0; i < nsegs;) { if (seg->mr_page) sg_set_page(&mw->mw_sg[i], seg->mr_page, seg->mr_len, offset_in_page(seg->mr_offset)); else sg_set_buf(&mw->mw_sg[i], seg->mr_offset, seg->mr_len); ++seg; ++i; if (holes_ok) continue; if ((i < nsegs && offset_in_page(seg->mr_offset)) || offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len)) break; } mw->mw_nents = i; mw->mw_dir = rpcrdma_data_dir(writing); if (i == 0) goto out_dmamap_err; dma_nents = ib_dma_map_sg(ia->ri_device, mw->mw_sg, mw->mw_nents, mw->mw_dir); if (!dma_nents) goto out_dmamap_err; n = ib_map_mr_sg(mr, mw->mw_sg, mw->mw_nents, NULL, PAGE_SIZE); if (unlikely(n != mw->mw_nents)) goto out_mapmr_err; dprintk("RPC: %s: Using frmr %p to map %u segments (%u bytes)\n", __func__, frmr, mw->mw_nents, mr->length); key = (u8)(mr->rkey & 0x000000FF); ib_update_fast_reg_key(mr, ++key); reg_wr->wr.next = NULL; reg_wr->wr.opcode = IB_WR_REG_MR; frmr->fr_cqe.done = frwr_wc_fastreg; reg_wr->wr.wr_cqe = &frmr->fr_cqe; reg_wr->wr.num_sge = 0; reg_wr->wr.send_flags = 0; reg_wr->mr = mr; reg_wr->key = mr->rkey; reg_wr->access = writing ? IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE : IB_ACCESS_REMOTE_READ; rpcrdma_set_signaled(&r_xprt->rx_ep, &reg_wr->wr); rc = ib_post_send(ia->ri_id->qp, &reg_wr->wr, &bad_wr); if (rc) goto out_senderr; mw->mw_handle = mr->rkey; mw->mw_length = mr->length; mw->mw_offset = mr->iova; *out = mw; return mw->mw_nents; out_dmamap_err: pr_err("rpcrdma: failed to dma map sg %p sg_nents %u\n", mw->mw_sg, mw->mw_nents); rpcrdma_defer_mr_recovery(mw); return -EIO; out_mapmr_err: pr_err("rpcrdma: failed to map mr %p (%u/%u)\n", frmr->fr_mr, n, mw->mw_nents); rpcrdma_defer_mr_recovery(mw); return -EIO; out_senderr: pr_err("rpcrdma: FRMR registration ib_post_send returned %i\n", rc); rpcrdma_defer_mr_recovery(mw); return -ENOTCONN; }

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Chuck Lever46374.68%1477.78%
Sagi Grimberg14723.71%15.56%
Christoph Hellwig91.45%211.11%
Bart Van Assche10.16%15.56%
Total620100.00%18100.00%

/* Invalidate all memory regions that were registered for "req". * * Sleeps until it is safe for the host CPU to access the * previously mapped memory regions. * * Caller ensures that req->rl_registered is not empty. */
static void frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) { struct ib_send_wr *first, **prev, *last, *bad_wr; struct rpcrdma_rep *rep = req->rl_reply; struct rpcrdma_ia *ia = &r_xprt->rx_ia; struct rpcrdma_frmr *f; struct rpcrdma_mw *mw; int count, rc; dprintk("RPC: %s: req %p\n", __func__, req); /* ORDER: Invalidate all of the req's MRs first * * Chain the LOCAL_INV Work Requests and post them with * a single ib_post_send() call. */ f = NULL; count = 0; prev = &first; list_for_each_entry(mw, &req->rl_registered, mw_list) { mw->frmr.fr_state = FRMR_IS_INVALID; if ((rep->rr_wc_flags & IB_WC_WITH_INVALIDATE) && (mw->mw_handle == rep->rr_inv_rkey)) continue; f = &mw->frmr; dprintk("RPC: %s: invalidating frmr %p\n", __func__, f); f->fr_cqe.done = frwr_wc_localinv; last = &f->fr_invwr; memset(last, 0, sizeof(*last)); last->wr_cqe = &f->fr_cqe; last->opcode = IB_WR_LOCAL_INV; last->ex.invalidate_rkey = mw->mw_handle; count++; *prev = last; prev = &last->next; } if (!f) goto unmap; /* Strong send queue ordering guarantees that when the * last WR in the chain completes, all WRs in the chain * are complete. */ last->send_flags = IB_SEND_SIGNALED; f->fr_cqe.done = frwr_wc_localinv_wake; reinit_completion(&f->fr_linv_done); /* Initialize CQ count, since there is always a signaled * WR being posted here. The new cqcount depends on how * many SQEs are about to be consumed. */ rpcrdma_init_cqcount(&r_xprt->rx_ep, count); /* Transport disconnect drains the receive CQ before it * replaces the QP. The RPC reply handler won't call us * unless ri_id->qp is a valid pointer. */ r_xprt->rx_stats.local_inv_needed++; rc = ib_post_send(ia->ri_id->qp, first, &bad_wr); if (rc) goto reset_mrs; wait_for_completion(&f->fr_linv_done); /* ORDER: Now DMA unmap all of the req's MRs, and return * them to the free MW list. */ unmap: while (!list_empty(&req->rl_registered)) { mw = rpcrdma_pop_mw(&req->rl_registered); dprintk("RPC: %s: DMA unmapping frmr %p\n", __func__, &mw->frmr); ib_dma_unmap_sg(ia->ri_device, mw->mw_sg, mw->mw_nents, mw->mw_dir); rpcrdma_put_mw(r_xprt, mw); } return; reset_mrs: pr_err("rpcrdma: FRMR invalidate ib_post_send returned %i\n", rc); rdma_disconnect(ia->ri_id); /* Find and reset the MRs in the LOCAL_INV WRs that did not * get posted. This is synchronous, and slow. */ list_for_each_entry(mw, &req->rl_registered, mw_list) { f = &mw->frmr; if (mw->mw_handle == bad_wr->ex.invalidate_rkey) { __frwr_reset_mr(ia, mw); bad_wr = bad_wr->next; } } goto unmap; }

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/* Use a slow, safe mechanism to invalidate all memory regions * that were registered for "req". */
static void frwr_op_unmap_safe(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req, bool sync) { struct rpcrdma_mw *mw; while (!list_empty(&req->rl_registered)) { mw = rpcrdma_pop_mw(&req->rl_registered); if (sync) frwr_op_recover_mr(mw); else rpcrdma_defer_mr_recovery(mw); } }

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const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops = { .ro_map = frwr_op_map, .ro_unmap_sync = frwr_op_unmap_sync, .ro_unmap_safe = frwr_op_unmap_safe, .ro_recover_mr = frwr_op_recover_mr, .ro_open = frwr_op_open, .ro_maxpages = frwr_op_maxpages, .ro_init_mr = frwr_op_init_mr, .ro_release_mr = frwr_op_release_mr, .ro_displayname = "frwr", .ro_send_w_inv_ok = RPCRDMA_CMP_F_SND_W_INV_OK, };

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Chuck Lever208192.20%4081.63%
Sagi Grimberg1526.73%36.12%
Steve Wise110.49%12.04%
Christoph Hellwig90.40%24.08%
Or Gerlitz20.09%12.04%
Bart Van Assche10.04%12.04%
Daniel Wagner10.04%12.04%
Total2257100.00%49100.00%
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