From patchwork Fri Jul 15 18:44:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anna Schumaker X-Patchwork-Id: 12919579 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 F187DCCA483 for ; Fri, 15 Jul 2022 18:44:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230260AbiGOSom (ORCPT ); Fri, 15 Jul 2022 14:44:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229481AbiGOSol (ORCPT ); Fri, 15 Jul 2022 14:44:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3F5715A04 for ; Fri, 15 Jul 2022 11:44:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 83F8562343 for ; Fri, 15 Jul 2022 18:44:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F2E6C385A5; Fri, 15 Jul 2022 18:44:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657910678; bh=PQTM8iMrLoTIgyAyMUjUCQ5Mi+HWXwf/800xJrzq89E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oIvl5yiL6VWkxNlJ6WqYIfw13uTX35ETAWIo/3aNbZVAhwTXErtEDV6cOBx0R+C4u P77nEcyvOmgZMke0cSwCZ9cibToMyHhAbmFYuuIZbUzvLzz/cyYQ6PXGwXp3SUSgbf 6w+WPuU+sopu0wuG0qqEW0957MUEshoQWhhbm363/UECBjIJYH2gR0WpYvSglq87u5 4AHArnUfLmtEgXWllB2AIXfgapj8Dig2VT9dZLkiyz0ABgUAYmebZqVSj5OAslAVOo 1s0bOPDzKJCA6Y+j/OqXOQ9ARDnHTVqFvZuvUHsWCULNY3l9F86YGOsq1YCeMHjVh9 EoNrRgUM5RX9g== From: Anna Schumaker To: linux-nfs@vger.kernel.org, chuck.lever@oracle.com Cc: anna@kernel.org Subject: [PATCH v3 6/6] NFSD: Repeal and replace the READ_PLUS implementation Date: Fri, 15 Jul 2022 14:44:33 -0400 Message-Id: <20220715184433.838521-7-anna@kernel.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220715184433.838521-1-anna@kernel.org> References: <20220715184433.838521-1-anna@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Anna Schumaker Rather than relying on the underlying filesystem to tell us where hole and data segments are through vfs_llseek(), let's instead do the hole compression ourselves. This has a few advantages over the old implementation: 1) A single call to the underlying filesystem through nfsd_readv() means the file can't change from underneath us in the middle of encoding. 2) A single call to the underlying filestem also means that the underlying filesystem only needs to synchronize cached and on-disk data one time instead of potentially many speeding up the reply. 3) Hole support for filesystems that don't support SEEK_HOLE and SEEK_DATA I also included an optimization where we can cut down on the amount of memory being shifed around by doing the compression as (hole, data) pairs. Signed-off-by: Anna Schumaker --- fs/nfsd/nfs4xdr.c | 219 +++++++++++++++++++++++++--------------------- 1 file changed, 119 insertions(+), 100 deletions(-) diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 61b2aae81abb..df8289fce4ef 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -4731,81 +4731,138 @@ nfsd4_encode_offload_status(struct nfsd4_compoundres *resp, __be32 nfserr, return nfserr; } +struct read_plus_segment { + enum data_content4 rp_type; + u64 rp_offset; + u64 rp_length; + unsigned int rp_page_pos; +}; + static __be32 -nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp, - struct nfsd4_read *read, - unsigned long *maxcount, u32 *eof, - loff_t *pos) +nfsd4_read_plus_readv(struct nfsd4_compoundres *resp, struct nfsd4_read *read, + unsigned long *maxcount, u32 *eof) { struct xdr_stream *xdr = resp->xdr; - struct file *file = read->rd_nf->nf_file; - int starting_len = xdr->buf->len; - loff_t hole_pos; - __be32 nfserr; - __be32 *p, tmp; - __be64 tmp64; - - hole_pos = pos ? *pos : vfs_llseek(file, read->rd_offset, SEEK_HOLE); - if (hole_pos > read->rd_offset) - *maxcount = min_t(unsigned long, *maxcount, hole_pos - read->rd_offset); - *maxcount = min_t(unsigned long, *maxcount, (xdr->buf->buflen - xdr->buf->len)); - - /* Content type, offset, byte count */ - p = xdr_reserve_space(xdr, 4 + 8 + 4); - if (!p) - return nfserr_resource; + unsigned int starting_len = xdr->buf->len; + __be32 nfserr, zero = xdr_zero; + unsigned int pad; + /* + * Reserve the maximum abount of space needed to craft a READ_PLUS + * reply. The call to xdr_reserve_space_vec() switches us to the + * xdr->pages, which we then read file data into before analyzing + * the individual segments. + */ read->rd_vlen = xdr_reserve_space_vec(xdr, resp->rqstp->rq_vec, *maxcount); if (read->rd_vlen < 0) return nfserr_resource; - nfserr = nfsd_readv(resp->rqstp, read->rd_fhp, file, read->rd_offset, - resp->rqstp->rq_vec, read->rd_vlen, maxcount, eof); + nfserr = nfsd_readv(resp->rqstp, read->rd_fhp, read->rd_nf->nf_file, + read->rd_offset, resp->rqstp->rq_vec, read->rd_vlen, + maxcount, eof); if (nfserr) return nfserr; - xdr_truncate_encode(xdr, starting_len + 16 + xdr_align_size(*maxcount)); + xdr_truncate_encode(xdr, starting_len + xdr_align_size(*maxcount)); - tmp = htonl(NFS4_CONTENT_DATA); - write_bytes_to_xdr_buf(xdr->buf, starting_len, &tmp, 4); - tmp64 = cpu_to_be64(read->rd_offset); - write_bytes_to_xdr_buf(xdr->buf, starting_len + 4, &tmp64, 8); - tmp = htonl(*maxcount); - write_bytes_to_xdr_buf(xdr->buf, starting_len + 12, &tmp, 4); - - tmp = xdr_zero; - write_bytes_to_xdr_buf(xdr->buf, starting_len + 16 + *maxcount, &tmp, - xdr_pad_size(*maxcount)); + pad = xdr_pad_size(*maxcount); + write_bytes_to_xdr_buf(xdr->buf, starting_len + *maxcount, &zero, pad); return nfs_ok; } +/** + * nfsd4_encode_read_plus_segment - Encode a single READ_PLUS segment + * @xdr: pointer to an xdr_stream + * @segment: pointer to a single segment + * @bufpos: xdr_stream offset to place the segment + * @segments: pointer to the total number of segments seen + * + * Performs surgery on the xdr_stream to compress out HOLE segments and + * to place DATA segments in the proper place. + */ +static void +nfsd4_encode_read_plus_segment(struct xdr_stream *xdr, + struct read_plus_segment *segment, + unsigned int *bufpos, unsigned int *segments) +{ + struct xdr_buf *buf = xdr->buf; + + xdr_encode_word(buf, *bufpos, segment->rp_type); + xdr_encode_double(buf, *bufpos + XDR_UNIT, segment->rp_offset); + *bufpos += 3 * XDR_UNIT; + + if (segment->rp_type == NFS4_CONTENT_HOLE) { + xdr_encode_double(buf, *bufpos, segment->rp_length); + *bufpos += 2 * XDR_UNIT; + } else { + size_t align = xdr_align_size(segment->rp_length); + xdr_encode_word(buf, *bufpos, segment->rp_length); + if (*segments == 0) + xdr_buf_trim_head(buf, XDR_UNIT); + + xdr_stream_move_subsegment(xdr, + buf->head[0].iov_len + segment->rp_page_pos, + *bufpos + XDR_UNIT, align); + *bufpos += XDR_UNIT + align; + } + + *segments += 1; +} + static __be32 -nfsd4_encode_read_plus_hole(struct nfsd4_compoundres *resp, - struct nfsd4_read *read, - unsigned long *maxcount, u32 *eof) +nfsd4_encode_read_plus_segments(struct nfsd4_compoundres *resp, + struct nfsd4_read *read, + unsigned int *segments, u32 *eof) { - struct file *file = read->rd_nf->nf_file; - loff_t data_pos = vfs_llseek(file, read->rd_offset, SEEK_DATA); - loff_t f_size = i_size_read(file_inode(file)); - unsigned long count; - __be32 *p; + struct xdr_stream *xdr = resp->xdr; + unsigned int bufpos = xdr->buf->len; + u64 offset = read->rd_offset; + struct read_plus_segment segment; + enum data_content4 pagetype; + unsigned long maxcount; + unsigned int pagenum = 0; + unsigned int pagelen; + char *vpage, *p; + __be32 nfserr; - if (data_pos == -ENXIO) - data_pos = f_size; - else if (data_pos <= read->rd_offset || (data_pos < f_size && data_pos % PAGE_SIZE)) - return nfsd4_encode_read_plus_data(resp, read, maxcount, eof, &f_size); - count = data_pos - read->rd_offset; - - /* Content type, offset, byte count */ - p = xdr_reserve_space(resp->xdr, 4 + 8 + 8); - if (!p) + /* enough space for a HOLE segment before we switch to the pages */ + if (!xdr_reserve_space(xdr, 5 * XDR_UNIT)) return nfserr_resource; + xdr_commit_encode(xdr); - *p++ = htonl(NFS4_CONTENT_HOLE); - p = xdr_encode_hyper(p, read->rd_offset); - p = xdr_encode_hyper(p, count); + maxcount = min_t(unsigned long, read->rd_length, + (xdr->buf->buflen - xdr->buf->len)); - *eof = (read->rd_offset + count) >= f_size; - *maxcount = min_t(unsigned long, count, *maxcount); + nfserr = nfsd4_read_plus_readv(resp, read, &maxcount, eof); + if (nfserr) + return nfserr; + + while (maxcount > 0) { + vpage = xdr_buf_nth_page_address(xdr->buf, pagenum, &pagelen); + pagelen = min_t(unsigned int, pagelen, maxcount); + if (!vpage || pagelen == 0) + break; + p = memchr_inv(vpage, 0, pagelen); + pagetype = (p == NULL) ? NFS4_CONTENT_HOLE : NFS4_CONTENT_DATA; + + if (pagetype != segment.rp_type || pagenum == 0) { + if (likely(pagenum > 0)) { + nfsd4_encode_read_plus_segment(xdr, &segment, + &bufpos, segments); + offset += segment.rp_length; + } + segment.rp_type = pagetype; + segment.rp_offset = offset; + segment.rp_length = pagelen; + segment.rp_page_pos = pagenum * PAGE_SIZE; + } else + segment.rp_length += pagelen; + + maxcount -= pagelen; + pagenum++; + } + + nfsd4_encode_read_plus_segment(xdr, &segment, &bufpos, segments); + xdr_truncate_encode(xdr, bufpos); return nfs_ok; } @@ -4813,69 +4870,31 @@ static __be32 nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_read *read) { - unsigned long maxcount, count; struct xdr_stream *xdr = resp->xdr; - struct file *file; int starting_len = xdr->buf->len; - int last_segment = xdr->buf->len; - int segments = 0; - __be32 *p, tmp; - bool is_data; - loff_t pos; + unsigned int segments = 0; u32 eof; if (nfserr) return nfserr; - file = read->rd_nf->nf_file; /* eof flag, segment count */ - p = xdr_reserve_space(xdr, 4 + 4); - if (!p) + if (!xdr_reserve_space(xdr, 2 * XDR_UNIT)) return nfserr_resource; xdr_commit_encode(xdr); - maxcount = min_t(unsigned long, read->rd_length, - (xdr->buf->buflen - xdr->buf->len)); - count = maxcount; - - eof = read->rd_offset >= i_size_read(file_inode(file)); + eof = read->rd_offset >= i_size_read(file_inode(read->rd_nf->nf_file)); if (eof) goto out; - pos = vfs_llseek(file, read->rd_offset, SEEK_HOLE); - is_data = pos > read->rd_offset; - - while (count > 0 && !eof) { - maxcount = count; - if (is_data) - nfserr = nfsd4_encode_read_plus_data(resp, read, &maxcount, &eof, - segments == 0 ? &pos : NULL); - else - nfserr = nfsd4_encode_read_plus_hole(resp, read, &maxcount, &eof); - if (nfserr) - goto out; - count -= maxcount; - read->rd_offset += maxcount; - is_data = !is_data; - last_segment = xdr->buf->len; - segments++; - } - + nfserr = nfsd4_encode_read_plus_segments(resp, read, &segments, &eof); out: - if (nfserr && segments == 0) + if (nfserr) xdr_truncate_encode(xdr, starting_len); else { - if (nfserr) { - xdr_truncate_encode(xdr, last_segment); - nfserr = nfs_ok; - eof = 0; - } - tmp = htonl(eof); - write_bytes_to_xdr_buf(xdr->buf, starting_len, &tmp, 4); - tmp = htonl(segments); - write_bytes_to_xdr_buf(xdr->buf, starting_len + 4, &tmp, 4); + xdr_encode_word(xdr->buf, starting_len, eof); + xdr_encode_word(xdr->buf, starting_len + XDR_UNIT, segments); } - return nfserr; }