![Chuck Lever](/assets/img/avatar_default.png)
With FRWR, the client transport can perform memory registration and post a Send with just a single ib_post_send. This reduces contention between the send_request path and the Send Completion handlers, and reduces the overhead of registering a chunk that has multiple segments. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
328 lines
7.7 KiB
C
328 lines
7.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2015, 2017 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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/* Normal operation
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*
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* A Memory Region is prepared for RDMA READ or WRITE using the
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* ib_map_phys_fmr verb (fmr_op_map). When the RDMA operation is
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* finished, the Memory Region is unmapped using the ib_unmap_fmr
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* verb (fmr_op_unmap).
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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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/* Access mode of externally registered pages */
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enum {
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RPCRDMA_FMR_ACCESS_FLAGS = IB_ACCESS_REMOTE_WRITE |
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IB_ACCESS_REMOTE_READ,
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};
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bool
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fmr_is_supported(struct rpcrdma_ia *ia)
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{
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if (!ia->ri_device->alloc_fmr) {
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pr_info("rpcrdma: 'fmr' mode is not supported by device %s\n",
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ia->ri_device->name);
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return false;
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}
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return true;
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}
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static int
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fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
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{
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static struct ib_fmr_attr fmr_attr = {
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.max_pages = RPCRDMA_MAX_FMR_SGES,
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.max_maps = 1,
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.page_shift = PAGE_SHIFT
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};
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mr->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
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sizeof(u64), GFP_KERNEL);
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if (!mr->fmr.fm_physaddrs)
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goto out_free;
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mr->mr_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
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sizeof(*mr->mr_sg), GFP_KERNEL);
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if (!mr->mr_sg)
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goto out_free;
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sg_init_table(mr->mr_sg, RPCRDMA_MAX_FMR_SGES);
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mr->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
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&fmr_attr);
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if (IS_ERR(mr->fmr.fm_mr))
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goto out_fmr_err;
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return 0;
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out_fmr_err:
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dprintk("RPC: %s: ib_alloc_fmr returned %ld\n", __func__,
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PTR_ERR(mr->fmr.fm_mr));
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out_free:
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kfree(mr->mr_sg);
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kfree(mr->fmr.fm_physaddrs);
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return -ENOMEM;
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}
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static int
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__fmr_unmap(struct rpcrdma_mr *mr)
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{
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LIST_HEAD(l);
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int rc;
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list_add(&mr->fmr.fm_mr->list, &l);
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rc = ib_unmap_fmr(&l);
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list_del(&mr->fmr.fm_mr->list);
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return rc;
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}
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static void
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fmr_op_release_mr(struct rpcrdma_mr *mr)
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{
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LIST_HEAD(unmap_list);
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int rc;
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/* Ensure MW is not on any rl_registered list */
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if (!list_empty(&mr->mr_list))
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list_del(&mr->mr_list);
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kfree(mr->fmr.fm_physaddrs);
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kfree(mr->mr_sg);
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/* In case this one was left mapped, try to unmap it
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* to prevent dealloc_fmr from failing with EBUSY
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*/
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rc = __fmr_unmap(mr);
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if (rc)
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pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
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mr, rc);
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rc = ib_dealloc_fmr(mr->fmr.fm_mr);
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if (rc)
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pr_err("rpcrdma: final ib_dealloc_fmr for %p returned %i\n",
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mr, rc);
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kfree(mr);
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}
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/* Reset of a single FMR.
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*/
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static void
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fmr_op_recover_mr(struct rpcrdma_mr *mr)
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{
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struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
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int rc;
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/* ORDER: invalidate first */
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rc = __fmr_unmap(mr);
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if (rc)
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goto out_release;
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/* ORDER: then DMA unmap */
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rpcrdma_mr_unmap_and_put(mr);
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r_xprt->rx_stats.mrs_recovered++;
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return;
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out_release:
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pr_err("rpcrdma: FMR reset failed (%d), %p released\n", rc, mr);
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r_xprt->rx_stats.mrs_orphaned++;
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trace_xprtrdma_dma_unmap(mr);
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ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
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mr->mr_sg, mr->mr_nents, mr->mr_dir);
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spin_lock(&r_xprt->rx_buf.rb_mrlock);
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list_del(&mr->mr_all);
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spin_unlock(&r_xprt->rx_buf.rb_mrlock);
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fmr_op_release_mr(mr);
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}
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static int
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fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
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struct rpcrdma_create_data_internal *cdata)
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{
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ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
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RPCRDMA_MAX_FMR_SGES);
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return 0;
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}
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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_HDR_SEGS * 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 struct rpcrdma_mr_seg *
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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, struct rpcrdma_mr **out)
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{
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struct rpcrdma_mr_seg *seg1 = seg;
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int len, pageoff, i, rc;
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struct rpcrdma_mr *mr;
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u64 *dma_pages;
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mr = rpcrdma_mr_get(r_xprt);
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if (!mr)
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return ERR_PTR(-EAGAIN);
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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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if (seg->mr_page)
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sg_set_page(&mr->mr_sg[i],
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seg->mr_page,
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seg->mr_len,
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offset_in_page(seg->mr_offset));
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else
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sg_set_buf(&mr->mr_sg[i], seg->mr_offset,
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seg->mr_len);
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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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mr->mr_dir = rpcrdma_data_dir(writing);
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mr->mr_nents = ib_dma_map_sg(r_xprt->rx_ia.ri_device,
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mr->mr_sg, i, mr->mr_dir);
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if (!mr->mr_nents)
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goto out_dmamap_err;
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for (i = 0, dma_pages = mr->fmr.fm_physaddrs; i < mr->mr_nents; i++)
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dma_pages[i] = sg_dma_address(&mr->mr_sg[i]);
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rc = ib_map_phys_fmr(mr->fmr.fm_mr, dma_pages, mr->mr_nents,
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dma_pages[0]);
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if (rc)
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goto out_maperr;
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mr->mr_handle = mr->fmr.fm_mr->rkey;
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mr->mr_length = len;
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mr->mr_offset = dma_pages[0] + pageoff;
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*out = mr;
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return seg;
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out_dmamap_err:
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pr_err("rpcrdma: failed to DMA map sg %p sg_nents %d\n",
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mr->mr_sg, i);
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rpcrdma_mr_put(mr);
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return ERR_PTR(-EIO);
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out_maperr:
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pr_err("rpcrdma: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
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len, (unsigned long long)dma_pages[0],
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pageoff, mr->mr_nents, rc);
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rpcrdma_mr_unmap_and_put(mr);
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return ERR_PTR(-EIO);
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}
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/* Post Send WR containing the RPC Call message.
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*/
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static int
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fmr_op_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
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{
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struct ib_send_wr *bad_wr;
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return ib_post_send(ia->ri_id->qp, &req->rl_sendctx->sc_wr, &bad_wr);
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}
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/* Invalidate all memory regions that were registered for "req".
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*
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* Sleeps until it is safe for the host CPU to access the
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* previously mapped memory regions.
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*
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* Caller ensures that @mrs is not empty before the call. This
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* function empties the list.
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*/
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static void
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fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
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{
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struct rpcrdma_mr *mr;
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LIST_HEAD(unmap_list);
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int rc;
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/* ORDER: Invalidate all of the req's MRs first
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*
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* ib_unmap_fmr() is slow, so use a single call instead
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* of one call per mapped FMR.
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*/
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list_for_each_entry(mr, mrs, mr_list) {
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dprintk("RPC: %s: unmapping fmr %p\n",
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__func__, &mr->fmr);
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trace_xprtrdma_localinv(mr);
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list_add_tail(&mr->fmr.fm_mr->list, &unmap_list);
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}
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r_xprt->rx_stats.local_inv_needed++;
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rc = ib_unmap_fmr(&unmap_list);
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if (rc)
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goto out_reset;
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/* ORDER: Now DMA unmap all of the req's MRs, and return
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* them to the free MW list.
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*/
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while (!list_empty(mrs)) {
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mr = rpcrdma_mr_pop(mrs);
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list_del(&mr->fmr.fm_mr->list);
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rpcrdma_mr_unmap_and_put(mr);
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}
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return;
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out_reset:
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pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
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while (!list_empty(mrs)) {
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mr = rpcrdma_mr_pop(mrs);
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list_del(&mr->fmr.fm_mr->list);
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fmr_op_recover_mr(mr);
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}
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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_send = fmr_op_send,
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.ro_unmap_sync = fmr_op_unmap_sync,
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.ro_recover_mr = fmr_op_recover_mr,
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.ro_open = fmr_op_open,
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.ro_maxpages = fmr_op_maxpages,
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.ro_init_mr = fmr_op_init_mr,
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.ro_release_mr = fmr_op_release_mr,
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.ro_displayname = "fmr",
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.ro_send_w_inv_ok = 0,
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};
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