From patchwork Fri Oct 28 15:56:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13023908 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CC63FA3742 for ; Fri, 28 Oct 2022 15:57:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230012AbiJ1P5R (ORCPT ); Fri, 28 Oct 2022 11:57:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbiJ1P5O (ORCPT ); Fri, 28 Oct 2022 11:57:14 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAA1A1F183E for ; Fri, 28 Oct 2022 08:56:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666972575; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RoVW8a8wNo+uPOOsfZeJ7xICN5gX5Q8U3X9+4rP9EmE=; b=IDp4PVrr37lm1cN0Rgh9kikHcJCpYhD+HU0hd4beKwwXaMKXSMWOOHV5vyaDInEJsrIGYB m5xQiZ7aXebaT6vHOHHAUGAE0QI1S5nGu7UG2rWNeCter8zDwPJ1NCN2azOFjuZqxA4+P8 C1eqNfGr3XGciO7n3ltLOUKaRtrgtlk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-191-7HIRKa1DO3yB9igaDjgKbw-1; Fri, 28 Oct 2022 11:56:09 -0400 X-MC-Unique: 7HIRKa1DO3yB9igaDjgKbw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 150ED86EB21; Fri, 28 Oct 2022 15:56:09 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.73]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9FB3E1415102; Fri, 28 Oct 2022 15:56:07 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 3/9] cifs: Add a function to build an RDMA SGE list from an iterator From: David Howells To: Steve French , Al Viro Cc: dhowells@redhat.com, Shyam Prasad N , Rohith Surabattula , Tom Talpey , Christoph Hellwig , Matthew Wilcox , Jeff Layton , linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 28 Oct 2022 16:56:07 +0100 Message-ID: <166697256704.61150.17388516338310645808.stgit@warthog.procyon.org.uk> In-Reply-To: <166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk> References: <166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk> User-Agent: StGit/1.5 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Add a function to add elements onto an RDMA SGE list representing page fragments extracted from a BVEC-, KVEC- or XARRAY-type iterator and DMA mapped until the maximum number of elements is reached. Nothing is done to make sure the pages remain present - that must be done by the caller. Signed-off-by: David Howells --- fs/cifs/smbdirect.c | 224 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 224 insertions(+) diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c index 90789aaa6567..18fb440a02c3 100644 --- a/fs/cifs/smbdirect.c +++ b/fs/cifs/smbdirect.c @@ -44,6 +44,17 @@ static int smbd_post_send_page(struct smbd_connection *info, static void destroy_mr_list(struct smbd_connection *info); static int allocate_mr_list(struct smbd_connection *info); +struct smb_extract_to_rdma { + struct ib_sge *sge; + unsigned int nr_sge; + unsigned int max_sge; + struct ib_device *device; + u32 local_dma_lkey; + enum dma_data_direction direction; +}; +static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len, + struct smb_extract_to_rdma *rdma); + /* SMBD version number */ #define SMBD_V1 0x0100 @@ -2489,3 +2500,216 @@ int smbd_deregister_mr(struct smbd_mr *smbdirect_mr) return rc; } + +static bool smb_set_sge(struct smb_extract_to_rdma *rdma, + struct page *lowest_page, size_t off, size_t len) +{ + struct ib_sge *sge = &rdma->sge[rdma->nr_sge]; + u64 addr; + + addr = ib_dma_map_page(rdma->device, lowest_page, + off, len, rdma->direction); + if (ib_dma_mapping_error(rdma->device, addr)) + return false; + + sge->addr = addr; + sge->length = len; + sge->lkey = rdma->local_dma_lkey; + rdma->nr_sge++; + return true; +} + +/* + * Extract page fragments from a BVEC-class iterator and add them to an RDMA + * element list. The pages are not pinned. + */ +static ssize_t smb_extract_bvec_to_rdma(struct iov_iter *iter, + struct smb_extract_to_rdma *rdma, + ssize_t maxsize) +{ + const struct bio_vec *bv = iter->bvec; + unsigned long start = iter->iov_offset; + unsigned int i, sge_max = rdma->max_sge; + ssize_t ret = 0; + + for (i = 0; i < iter->nr_segs; i++) { + size_t off, len; + + len = bv[i].bv_len; + if (start >= len) { + start -= len; + continue; + } + + len = min_t(size_t, maxsize, len - start); + off = bv[i].bv_offset + start; + + if (!smb_set_sge(rdma, bv[i].bv_page, off, len)) + return -EIO; + sge_max--; + + ret += len; + maxsize -= len; + if (maxsize <= 0 || sge_max == 0) + break; + start = 0; + } + + return ret; +} + +/* + * Extract fragments from a KVEC-class iterator and add them to an RDMA list. + * This can deal with vmalloc'd buffers as well as kmalloc'd or static buffers. + * The pages are not pinned. + */ +static ssize_t smb_extract_kvec_to_rdma(struct iov_iter *iter, + struct smb_extract_to_rdma *rdma, + ssize_t maxsize) +{ + const struct kvec *kv = iter->kvec; + unsigned long start = iter->iov_offset; + unsigned int i, sge_max = rdma->max_sge; + ssize_t ret = 0; + + for (i = 0; i < iter->nr_segs; i++) { + struct page *page; + unsigned long kaddr; + size_t off, len, seg; + + len = kv[i].iov_len; + if (start >= len) { + start -= len; + continue; + } + + kaddr = (unsigned long)kv[i].iov_base + start; + off = kaddr & ~PAGE_MASK; + len = min_t(size_t, maxsize, len - start); + kaddr &= PAGE_MASK; + + maxsize -= len; + ret += len; + do { + seg = min_t(size_t, len, PAGE_SIZE - off); + + if (is_vmalloc_or_module_addr((void *)kaddr)) + page = vmalloc_to_page((void *)kaddr); + else + page = virt_to_page(kaddr); + + if (!smb_set_sge(rdma, page, off, len)) + return -EIO; + sge_max--; + + len -= seg; + kaddr += PAGE_SIZE; + off = 0; + } while (len > 0 && sge_max > 0); + + if (maxsize <= 0 || sge_max == 0) + break; + start = 0; + } + + return ret; +} + +/* + * Extract folio fragments from an XARRAY-class iterator and add them to an + * RDMA list. The folios are not pinned. + */ +static ssize_t smb_extract_xarray_to_rdma(struct iov_iter *iter, + struct smb_extract_to_rdma *rdma, + ssize_t maxsize) +{ + struct xarray *xa = iter->xarray; + struct folio *folio; + unsigned int sge_max = rdma->max_sge; + loff_t start = iter->xarray_start + iter->iov_offset; + pgoff_t index = start / PAGE_SIZE; + ssize_t ret; + size_t off, len; + XA_STATE(xas, xa, index); + + rcu_read_lock(); + + xas_for_each(&xas, folio, ULONG_MAX) { + if (xas_retry(&xas, folio)) + continue; + if (WARN_ON(xa_is_value(folio))) + break; + if (WARN_ON(folio_test_hugetlb(folio))) + break; + + off = offset_in_folio(folio, start); + len = min_t(size_t, maxsize, folio_size(folio) - off); + + if (!smb_set_sge(rdma, folio_page(folio, 0), off, len)) { + rcu_read_lock(); + return -EIO; + } + sge_max--; + + maxsize -= len; + ret += len; + if (maxsize <= 0 || sge_max == 0) + break; + } + + rcu_read_unlock(); + return ret; +} + +/* + * Extract page fragments from up to the given amount of the source iterator + * and build up an RDMA list that refers to all of those bits. The RDMA list + * is appended to, up to the maximum number of elements set in the parameter + * block. + * + * The extracted page fragments are not pinned or ref'd in any way; if an + * IOVEC/UBUF-type iterator is to be used, it should be converted to a + * BVEC-type iterator and the pages pinned, ref'd or otherwise held in some + * way. + */ +static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len, + struct smb_extract_to_rdma *rdma) +{ + ssize_t ret; + int before = rdma->nr_sge; + + if (iov_iter_is_discard(iter) || + iov_iter_is_pipe(iter) || + user_backed_iter(iter)) { + WARN_ON_ONCE(1); + return -EIO; + } + + switch (iov_iter_type(iter)) { + case ITER_BVEC: + ret = smb_extract_bvec_to_rdma(iter, rdma, len); + break; + case ITER_KVEC: + ret = smb_extract_kvec_to_rdma(iter, rdma, len); + break; + case ITER_XARRAY: + ret = smb_extract_xarray_to_rdma(iter, rdma, len); + break; + default: + BUG(); + } + + if (ret > 0) { + iov_iter_advance(iter, ret); + } else if (ret < 0) { + while (rdma->nr_sge > before) { + struct ib_sge *sge = &rdma->sge[rdma->nr_sge--]; + + ib_dma_unmap_single(rdma->device, sge->addr, sge->length, + rdma->direction); + sge->addr = 0; + } + } + + return ret; +}