From patchwork Mon Feb 21 16:08:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Trond Myklebust X-Patchwork-Id: 12753863 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 B3BC4C433EF for ; Mon, 21 Feb 2022 16:16:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379989AbiBUQP1 (ORCPT ); Mon, 21 Feb 2022 11:15:27 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:40030 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379983AbiBUQPY (ORCPT ); Mon, 21 Feb 2022 11:15:24 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 890E0275E4 for ; Mon, 21 Feb 2022 08:15:01 -0800 (PST) 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 2F0FF612A3 for ; Mon, 21 Feb 2022 16:15:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FCE1C340EC for ; Mon, 21 Feb 2022 16:15:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1645460100; bh=m6sax1/JXMip2aZkM1npxw5hIOe+LLtF9aa7G7CmtEc=; h=From:To:Subject:Date:In-Reply-To:References:From; b=Q+F7vskakNE3txfp/hrUjaQUxwFFuNTCLU05AzpFJeMBiRYowSxPmMZC6+W5Yrtw6 15UathpoDKY6nQ7xmaaxEAKbgYoU/G9Hk+2Y8mKojiFY0SPPaiJt00Bq51IPrdDABE yy4YaTuQ8ZPUVQ3vHhIB4CkLneW73X66AsiDfXLJ0CJYc5wX/9AGpRtCYUvBOTbHEP 99Yzdk/rpdpR5dN+hZ6+J6CDaImUoWbyzTlk3GeceaVx6BJLBsT6m5AnkyFSTGrYiM V1q2zbx9D2Jey3yC20awHgph1kME0TUkkYhAfs9zEChGsiBxa6tY9gpBGWn7NiMCEg snYvWCMbYb1Kw== From: trondmy@kernel.org To: linux-nfs@vger.kernel.org Subject: [PATCH v6 03/13] NFS: Adjust the amount of readahead performed by NFS readdir Date: Mon, 21 Feb 2022 11:08:41 -0500 Message-Id: <20220221160851.15508-4-trondmy@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221160851.15508-3-trondmy@kernel.org> References: <20220221160851.15508-1-trondmy@kernel.org> <20220221160851.15508-2-trondmy@kernel.org> <20220221160851.15508-3-trondmy@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Trond Myklebust The current NFS readdir code will always try to maximise the amount of readahead it performs on the assumption that we can cache anything that isn't immediately read by the process. There are several cases where this assumption breaks down, including when the 'ls -l' heuristic kicks in to try to force use of readdirplus as a batch replacement for lookup/getattr. This patch therefore tries to tone down the amount of readahead we perform, and adjust it to try to match the amount of data being requested by user space. Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 55 +++++++++++++++++++++++++++++++++++++++++- include/linux/nfs_fs.h | 1 + 2 files changed, 55 insertions(+), 1 deletion(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 8e750ef34559..c84a3bbda216 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -69,6 +69,8 @@ const struct address_space_operations nfs_dir_aops = { .freepage = nfs_readdir_clear_array, }; +#define NFS_INIT_DTSIZE PAGE_SIZE + static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir) { struct nfs_inode *nfsi = NFS_I(dir); @@ -80,6 +82,7 @@ static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir ctx->dir_cookie = 0; ctx->dup_cookie = 0; ctx->page_index = 0; + ctx->dtsize = NFS_INIT_DTSIZE; ctx->eof = false; spin_lock(&dir->i_lock); if (list_empty(&nfsi->open_files) && @@ -155,6 +158,7 @@ struct nfs_readdir_descriptor { struct page *page; struct dir_context *ctx; pgoff_t page_index; + pgoff_t page_index_max; u64 dir_cookie; u64 last_cookie; u64 dup_cookie; @@ -167,12 +171,36 @@ struct nfs_readdir_descriptor { unsigned long gencount; unsigned long attr_gencount; unsigned int cache_entry_index; + unsigned int buffer_fills; + unsigned int dtsize; signed char duped; bool plus; bool eob; bool eof; }; +static void nfs_set_dtsize(struct nfs_readdir_descriptor *desc, unsigned int sz) +{ + struct nfs_server *server = NFS_SERVER(file_inode(desc->file)); + unsigned int maxsize = server->dtsize; + + if (sz > maxsize) + sz = maxsize; + if (sz < NFS_MIN_FILE_IO_SIZE) + sz = NFS_MIN_FILE_IO_SIZE; + desc->dtsize = sz; +} + +static void nfs_shrink_dtsize(struct nfs_readdir_descriptor *desc) +{ + nfs_set_dtsize(desc, desc->dtsize >> 1); +} + +static void nfs_grow_dtsize(struct nfs_readdir_descriptor *desc) +{ + nfs_set_dtsize(desc, desc->dtsize << 1); +} + static void nfs_readdir_array_init(struct nfs_cache_array *array) { memset(array, 0, sizeof(struct nfs_cache_array)); @@ -759,6 +787,7 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc, break; arrays++; *arrays = page = new; + desc->page_index_max++; } else { new = nfs_readdir_page_get_next(mapping, page->index + 1, @@ -768,6 +797,7 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc, if (page != *arrays) nfs_readdir_page_unlock_and_put(page); page = new; + desc->page_index_max = new->index; } status = nfs_readdir_add_to_array(entry, page); } while (!status && !entry->eof); @@ -833,7 +863,7 @@ static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc, struct nfs_entry *entry; size_t array_size; struct inode *inode = file_inode(desc->file); - size_t dtsize = NFS_SERVER(inode)->dtsize; + unsigned int dtsize = desc->dtsize; int status = -ENOMEM; entry = kzalloc(sizeof(*entry), GFP_KERNEL); @@ -869,6 +899,7 @@ static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc, status = nfs_readdir_page_filler(desc, entry, pages, pglen, arrays, narrays); + desc->buffer_fills++; } while (!status && nfs_readdir_page_needs_filling(page) && page_mapping(page)); @@ -916,6 +947,7 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc) if (!desc->page) return -ENOMEM; if (nfs_readdir_page_needs_filling(desc->page)) { + desc->page_index_max = desc->page_index; res = nfs_readdir_xdr_to_array(desc, nfsi->cookieverf, verf, &desc->page, 1); if (res < 0) { @@ -1047,6 +1079,7 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc) desc->cache_entry_index = 0; desc->last_cookie = desc->dir_cookie; desc->duped = 0; + desc->page_index_max = 0; status = nfs_readdir_xdr_to_array(desc, desc->verf, verf, arrays, sz); @@ -1056,10 +1089,22 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc) } desc->page = NULL; + /* + * Grow the dtsize if we have to go back for more pages, + * or shrink it if we're reading too many. + */ + if (!desc->eof) { + if (!desc->eob) + nfs_grow_dtsize(desc); + else if (desc->buffer_fills == 1 && + i < (desc->page_index_max >> 1)) + nfs_shrink_dtsize(desc); + } for (i = 0; i < sz && arrays[i]; i++) nfs_readdir_page_array_free(arrays[i]); out: + desc->page_index_max = -1; kfree(arrays); dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status); return status; @@ -1102,6 +1147,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx) desc->file = file; desc->ctx = ctx; desc->plus = nfs_use_readdirplus(inode, ctx); + desc->page_index_max = -1; spin_lock(&file->f_lock); desc->dir_cookie = dir_ctx->dir_cookie; @@ -1110,6 +1156,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx) page_index = dir_ctx->page_index; desc->attr_gencount = dir_ctx->attr_gencount; desc->eof = dir_ctx->eof; + nfs_set_dtsize(desc, dir_ctx->dtsize); memcpy(desc->verf, dir_ctx->verf, sizeof(desc->verf)); spin_unlock(&file->f_lock); @@ -1151,6 +1198,11 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx) nfs_do_filldir(desc, nfsi->cookieverf); nfs_readdir_page_unlock_and_put_cached(desc); + if (desc->eob || desc->eof) + break; + /* Grow the dtsize if we have to go back for more pages */ + if (desc->page_index == desc->page_index_max) + nfs_grow_dtsize(desc); } while (!desc->eob && !desc->eof); spin_lock(&file->f_lock); @@ -1160,6 +1212,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx) dir_ctx->attr_gencount = desc->attr_gencount; dir_ctx->page_index = desc->page_index; dir_ctx->eof = desc->eof; + dir_ctx->dtsize = desc->dtsize; memcpy(dir_ctx->verf, desc->verf, sizeof(dir_ctx->verf)); spin_unlock(&file->f_lock); out_free: diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index 6e10725887d1..d27f7e788624 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -106,6 +106,7 @@ struct nfs_open_dir_context { __u64 dir_cookie; __u64 dup_cookie; pgoff_t page_index; + unsigned int dtsize; signed char duped; bool eof; };