87 lines
2.3 KiB
C
87 lines
2.3 KiB
C
/*
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* Copyright (c) 2015 Oracle. All rights reserved.
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* Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
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*/
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/* Lightweight memory registration using Fast Memory Regions (FMR).
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* Referred to sometimes as MTHCAFMR mode.
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*
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* FMR uses synchronous memory registration and deregistration.
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* FMR registration is known to be fast, but FMR deregistration
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* can take tens of usecs to complete.
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*/
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#include "xprt_rdma.h"
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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# define RPCDBG_FACILITY RPCDBG_TRANS
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#endif
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/* Maximum scatter/gather per FMR */
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#define RPCRDMA_MAX_FMR_SGES (64)
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/* FMR mode conveys up to 64 pages of payload per chunk segment.
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*/
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static size_t
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fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
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{
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return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
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rpcrdma_max_segments(r_xprt) * RPCRDMA_MAX_FMR_SGES);
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}
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/* Use the ib_map_phys_fmr() verb to register a memory region
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* for remote access via RDMA READ or RDMA WRITE.
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*/
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static int
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fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
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int nsegs, bool writing)
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{
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struct rpcrdma_ia *ia = &r_xprt->rx_ia;
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struct rpcrdma_mr_seg *seg1 = seg;
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struct rpcrdma_mw *mw = seg1->rl_mw;
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u64 physaddrs[RPCRDMA_MAX_DATA_SEGS];
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int len, pageoff, i, rc;
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pageoff = offset_in_page(seg1->mr_offset);
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seg1->mr_offset -= pageoff; /* start of page */
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seg1->mr_len += pageoff;
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len = -pageoff;
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if (nsegs > RPCRDMA_MAX_FMR_SGES)
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nsegs = RPCRDMA_MAX_FMR_SGES;
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for (i = 0; i < nsegs;) {
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rpcrdma_map_one(ia, seg, writing);
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physaddrs[i] = seg->mr_dma;
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len += seg->mr_len;
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++seg;
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++i;
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/* Check for holes */
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if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
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offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
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break;
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}
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rc = ib_map_phys_fmr(mw->r.fmr, physaddrs, i, seg1->mr_dma);
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if (rc)
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goto out_maperr;
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seg1->mr_rkey = mw->r.fmr->rkey;
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seg1->mr_base = seg1->mr_dma + pageoff;
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seg1->mr_nsegs = i;
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seg1->mr_len = len;
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return i;
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out_maperr:
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dprintk("RPC: %s: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
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__func__, len, (unsigned long long)seg1->mr_dma,
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pageoff, i, rc);
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while (i--)
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rpcrdma_unmap_one(ia, --seg);
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return rc;
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}
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const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
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.ro_map = fmr_op_map,
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.ro_maxpages = fmr_op_maxpages,
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.ro_displayname = "fmr",
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};
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