From patchwork Tue Nov 1 14:46:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 13027019 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 638E5C433FE for ; Tue, 1 Nov 2022 14:46:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229511AbiKAOqy (ORCPT ); Tue, 1 Nov 2022 10:46:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57060 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230357AbiKAOqy (ORCPT ); Tue, 1 Nov 2022 10:46:54 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AA211C137 for ; Tue, 1 Nov 2022 07:46:53 -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 ams.source.kernel.org (Postfix) with ESMTPS id C0F89B81DE8 for ; Tue, 1 Nov 2022 14:46:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03FEAC433D6; Tue, 1 Nov 2022 14:46:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667314010; bh=hR4n/WdwUFH1ht7bOelDcd/wkqhBjpnPe5mAmyEPMgs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cVicQ/ar3dKXwx+7HddKhWXw2B2oIQruOKiGxwXYmgvsgnS2G5+nrJv918Q+334lw A1GZXp3SOSe7zzJxRu3l+p6o+J3vmk4de5UQldM1J8qFSkHeZdlpYd7iIyhXg8VNby 0lvYka8BsYEpLdkg5HPA7W+NQV5FD8R8Xm6zftMYBqSeofDzaTggdJshZDQCSBLajF +gk4/8CSMwa+F6x7z3+S4zwDA8XJn8tbPXIR/D2kC0ocs4TvTvfL5E9KJf92/VYghM A/iFtmCayW14gEut9B1sE8XtvrNbGwNEiOalsllmzqwQNi56M/qjXAkqmWdJMPh3h5 3tI4xndQ7EHnw== From: Jeff Layton To: chuck.lever@oracle.com Cc: neilb@suse.de, linux-nfs@vger.kernel.org Subject: [PATCH v5 1/5] nfsd: remove the pages_flushed statistic from filecache Date: Tue, 1 Nov 2022 10:46:43 -0400 Message-Id: <20221101144647.136696-2-jlayton@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221101144647.136696-1-jlayton@kernel.org> References: <20221101144647.136696-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org We're counting mapping->nrpages, but not all of those are necessarily dirty. We don't really have a simple way to count just the dirty pages, so just remove this stat since it's not accurate. Signed-off-by: Jeff Layton --- fs/nfsd/filecache.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index b6b957e25dfd..90e62042d6d6 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -34,7 +34,6 @@ static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits); static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions); static DEFINE_PER_CPU(unsigned long, nfsd_file_releases); static DEFINE_PER_CPU(unsigned long, nfsd_file_total_age); -static DEFINE_PER_CPU(unsigned long, nfsd_file_pages_flushed); static DEFINE_PER_CPU(unsigned long, nfsd_file_evictions); struct nfsd_fcache_disposal { @@ -372,7 +371,6 @@ nfsd_file_flush(struct nfsd_file *nf) if (!file || !(file->f_mode & FMODE_WRITE)) return; - this_cpu_add(nfsd_file_pages_flushed, file->f_mapping->nrpages); if (vfs_fsync(file, 1) != 0) nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id)); } @@ -999,7 +997,6 @@ nfsd_file_cache_shutdown(void) per_cpu(nfsd_file_acquisitions, i) = 0; per_cpu(nfsd_file_releases, i) = 0; per_cpu(nfsd_file_total_age, i) = 0; - per_cpu(nfsd_file_pages_flushed, i) = 0; per_cpu(nfsd_file_evictions, i) = 0; } } @@ -1213,7 +1210,7 @@ nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp, */ int nfsd_file_cache_stats_show(struct seq_file *m, void *v) { - unsigned long releases = 0, pages_flushed = 0, evictions = 0; + unsigned long releases = 0, evictions = 0; unsigned long hits = 0, acquisitions = 0; unsigned int i, count = 0, buckets = 0; unsigned long lru = 0, total_age = 0; @@ -1241,7 +1238,6 @@ int nfsd_file_cache_stats_show(struct seq_file *m, void *v) releases += per_cpu(nfsd_file_releases, i); total_age += per_cpu(nfsd_file_total_age, i); evictions += per_cpu(nfsd_file_evictions, i); - pages_flushed += per_cpu(nfsd_file_pages_flushed, i); } seq_printf(m, "total entries: %u\n", count); @@ -1255,6 +1251,5 @@ int nfsd_file_cache_stats_show(struct seq_file *m, void *v) seq_printf(m, "mean age (ms): %ld\n", total_age / releases); else seq_printf(m, "mean age (ms): -\n"); - seq_printf(m, "pages flushed: %lu\n", pages_flushed); return 0; } From patchwork Tue Nov 1 14:46:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 13027022 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 EA121C4332F for ; Tue, 1 Nov 2022 14:46:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229813AbiKAOq5 (ORCPT ); Tue, 1 Nov 2022 10:46:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230071AbiKAOqz (ORCPT ); Tue, 1 Nov 2022 10:46:55 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDE68175B7 for ; Tue, 1 Nov 2022 07:46:53 -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 ams.source.kernel.org (Postfix) with ESMTPS id 6662DB81DEB for ; Tue, 1 Nov 2022 14:46:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E4C7C4347C; Tue, 1 Nov 2022 14:46:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667314011; bh=0R0EdfCwdJ2DYzMllgvY+2urLzv0HgEqacF/n3IviZE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AZ+FQrl4ex378s+D2TyveBQ4FaSD8X3wBmyQpatRdc3wRAddjMdiQBQF2G4AoVjm6 bYxce5lE5b+ewtaOZgclMdpinYMpuRArsTAbdLVWiRlcVmvJBfVNCT0KK+4GKOPJeU 43Pa3jsbSLahhOJMKXxUiXarWEONo3vhAzS8TF1HzVqktnBdDYIjQM3q1H49pPNGAP 97W7Uvlbj6pJ/RNONG1vApRUvZvALE7y8ehvMbGNKhfVOUI40CfJgzG49xuKdEZuKR 1MZlxBIyPbsN6WZpxcuhrxjLHi/EnoHdfo7cK9TxPC95KLVWxLlOcsiUM9OqyAOrJp mt9HA5l3hOdWg== From: Jeff Layton To: chuck.lever@oracle.com Cc: neilb@suse.de, linux-nfs@vger.kernel.org Subject: [PATCH v5 2/5] nfsd: reorganize filecache.c Date: Tue, 1 Nov 2022 10:46:44 -0400 Message-Id: <20221101144647.136696-3-jlayton@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221101144647.136696-1-jlayton@kernel.org> References: <20221101144647.136696-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org In a coming patch, we're going to rework how the filecache refcounting works. Move some code around in the function to reduce the churn in the later patches, and rename some of the functions with (hopefully) clearer names. This should introduce no functional changes. Signed-off-by: Jeff Layton Reviewed-by: NeilBrown --- fs/nfsd/filecache.c | 135 ++++++++++++++++++++++---------------------- fs/nfsd/trace.h | 4 +- 2 files changed, 70 insertions(+), 69 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 90e62042d6d6..0bf3727455e2 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -311,16 +311,59 @@ nfsd_file_alloc(struct nfsd_file_lookup_key *key, unsigned int may) return nf; } +static void +nfsd_file_fsync(struct nfsd_file *nf) +{ + struct file *file = nf->nf_file; + + if (!file || !(file->f_mode & FMODE_WRITE)) + return; + if (vfs_fsync(file, 1) != 0) + nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id)); +} + +static int +nfsd_file_check_write_error(struct nfsd_file *nf) +{ + struct file *file = nf->nf_file; + + if (!file || !(file->f_mode & FMODE_WRITE)) + return 0; + return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err)); +} + +static void +nfsd_file_hash_remove(struct nfsd_file *nf) +{ + trace_nfsd_file_unhash(nf); + + if (nfsd_file_check_write_error(nf)) + nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id)); + rhashtable_remove_fast(&nfsd_file_rhash_tbl, &nf->nf_rhash, + nfsd_file_rhash_params); +} + +static bool +nfsd_file_unhash(struct nfsd_file *nf) +{ + if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { + nfsd_file_hash_remove(nf); + return true; + } + return false; +} + static bool nfsd_file_free(struct nfsd_file *nf) { s64 age = ktime_to_ms(ktime_sub(ktime_get(), nf->nf_birthtime)); bool flush = false; + trace_nfsd_file_free(nf); + this_cpu_inc(nfsd_file_releases); this_cpu_add(nfsd_file_total_age, age); - trace_nfsd_file_put_final(nf); if (nf->nf_mark) nfsd_file_mark_put(nf->nf_mark); if (nf->nf_file) { @@ -354,27 +397,6 @@ nfsd_file_check_writeback(struct nfsd_file *nf) mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK); } -static int -nfsd_file_check_write_error(struct nfsd_file *nf) -{ - struct file *file = nf->nf_file; - - if (!file || !(file->f_mode & FMODE_WRITE)) - return 0; - return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err)); -} - -static void -nfsd_file_flush(struct nfsd_file *nf) -{ - struct file *file = nf->nf_file; - - if (!file || !(file->f_mode & FMODE_WRITE)) - return; - if (vfs_fsync(file, 1) != 0) - nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id)); -} - static void nfsd_file_lru_add(struct nfsd_file *nf) { set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags); @@ -388,31 +410,18 @@ static void nfsd_file_lru_remove(struct nfsd_file *nf) trace_nfsd_file_lru_del(nf); } -static void -nfsd_file_hash_remove(struct nfsd_file *nf) -{ - trace_nfsd_file_unhash(nf); - - if (nfsd_file_check_write_error(nf)) - nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id)); - rhashtable_remove_fast(&nfsd_file_rhash_tbl, &nf->nf_rhash, - nfsd_file_rhash_params); -} - -static bool -nfsd_file_unhash(struct nfsd_file *nf) +struct nfsd_file * +nfsd_file_get(struct nfsd_file *nf) { - if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { - nfsd_file_hash_remove(nf); - return true; - } - return false; + if (likely(refcount_inc_not_zero(&nf->nf_ref))) + return nf; + return NULL; } static void -nfsd_file_unhash_and_dispose(struct nfsd_file *nf, struct list_head *dispose) +nfsd_file_unhash_and_queue(struct nfsd_file *nf, struct list_head *dispose) { - trace_nfsd_file_unhash_and_dispose(nf); + trace_nfsd_file_unhash_and_queue(nf); if (nfsd_file_unhash(nf)) { /* caller must call nfsd_file_dispose_list() later */ nfsd_file_lru_remove(nf); @@ -450,7 +459,7 @@ nfsd_file_put(struct nfsd_file *nf) nfsd_file_unhash_and_put(nf); if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { - nfsd_file_flush(nf); + nfsd_file_fsync(nf); nfsd_file_put_noref(nf); } else if (nf->nf_file && test_bit(NFSD_FILE_GC, &nf->nf_flags)) { nfsd_file_put_noref(nf); @@ -459,14 +468,6 @@ nfsd_file_put(struct nfsd_file *nf) nfsd_file_put_noref(nf); } -struct nfsd_file * -nfsd_file_get(struct nfsd_file *nf) -{ - if (likely(refcount_inc_not_zero(&nf->nf_ref))) - return nf; - return NULL; -} - static void nfsd_file_dispose_list(struct list_head *dispose) { @@ -475,7 +476,7 @@ nfsd_file_dispose_list(struct list_head *dispose) while(!list_empty(dispose)) { nf = list_first_entry(dispose, struct nfsd_file, nf_lru); list_del_init(&nf->nf_lru); - nfsd_file_flush(nf); + nfsd_file_fsync(nf); nfsd_file_put_noref(nf); } } @@ -489,7 +490,7 @@ nfsd_file_dispose_list_sync(struct list_head *dispose) while(!list_empty(dispose)) { nf = list_first_entry(dispose, struct nfsd_file, nf_lru); list_del_init(&nf->nf_lru); - nfsd_file_flush(nf); + nfsd_file_fsync(nf); if (!refcount_dec_and_test(&nf->nf_ref)) continue; if (nfsd_file_free(nf)) @@ -689,7 +690,7 @@ __nfsd_file_close_inode(struct inode *inode, struct list_head *dispose) nfsd_file_rhash_params); if (!nf) break; - nfsd_file_unhash_and_dispose(nf, dispose); + nfsd_file_unhash_and_queue(nf, dispose); count++; } while (1); rcu_read_unlock(); @@ -697,37 +698,37 @@ __nfsd_file_close_inode(struct inode *inode, struct list_head *dispose) } /** - * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file + * nfsd_file_close_inode - attempt a delayed close of a nfsd_file * @inode: inode of the file to attempt to remove * - * Unhash and put, then flush and fput all cache items associated with @inode. + * Unhash and put all cache item associated with @inode. */ -void -nfsd_file_close_inode_sync(struct inode *inode) +static void +nfsd_file_close_inode(struct inode *inode) { LIST_HEAD(dispose); unsigned int count; count = __nfsd_file_close_inode(inode, &dispose); - trace_nfsd_file_close_inode_sync(inode, count); - nfsd_file_dispose_list_sync(&dispose); + trace_nfsd_file_close_inode(inode, count); + nfsd_file_dispose_list_delayed(&dispose); } /** - * nfsd_file_close_inode - attempt a delayed close of a nfsd_file + * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file * @inode: inode of the file to attempt to remove * - * Unhash and put all cache item associated with @inode. + * Unhash and put, then flush and fput all cache items associated with @inode. */ -static void -nfsd_file_close_inode(struct inode *inode) +void +nfsd_file_close_inode_sync(struct inode *inode) { LIST_HEAD(dispose); unsigned int count; count = __nfsd_file_close_inode(inode, &dispose); - trace_nfsd_file_close_inode(inode, count); - nfsd_file_dispose_list_delayed(&dispose); + trace_nfsd_file_close_inode_sync(inode, count); + nfsd_file_dispose_list_sync(&dispose); } /** @@ -891,7 +892,7 @@ __nfsd_file_cache_purge(struct net *net) nf = rhashtable_walk_next(&iter); while (!IS_ERR_OR_NULL(nf)) { if (!net || nf->nf_net == net) - nfsd_file_unhash_and_dispose(nf, &dispose); + nfsd_file_unhash_and_queue(nf, &dispose); nf = rhashtable_walk_next(&iter); } diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h index b09ab4f92d43..940252482fd4 100644 --- a/fs/nfsd/trace.h +++ b/fs/nfsd/trace.h @@ -903,10 +903,10 @@ DEFINE_EVENT(nfsd_file_class, name, \ TP_PROTO(struct nfsd_file *nf), \ TP_ARGS(nf)) -DEFINE_NFSD_FILE_EVENT(nfsd_file_put_final); +DEFINE_NFSD_FILE_EVENT(nfsd_file_free); DEFINE_NFSD_FILE_EVENT(nfsd_file_unhash); DEFINE_NFSD_FILE_EVENT(nfsd_file_put); -DEFINE_NFSD_FILE_EVENT(nfsd_file_unhash_and_dispose); +DEFINE_NFSD_FILE_EVENT(nfsd_file_unhash_and_queue); TRACE_EVENT(nfsd_file_alloc, TP_PROTO( From patchwork Tue Nov 1 14:46:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 13027023 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 1E664C43219 for ; Tue, 1 Nov 2022 14:46:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230031AbiKAOq5 (ORCPT ); Tue, 1 Nov 2022 10:46:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230364AbiKAOq4 (ORCPT ); Tue, 1 Nov 2022 10:46:56 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E8701B9FA for ; Tue, 1 Nov 2022 07:46:54 -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 ams.source.kernel.org (Postfix) with ESMTPS id 01E0AB81DEA for ; Tue, 1 Nov 2022 14:46:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45718C43142; Tue, 1 Nov 2022 14:46:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667314011; bh=16CGW9LkcVuGXLZPunVfRLLSVAQSW+ztuLHw9u6msV8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UPXr45+I39gR3bfoKcDFp4q5pB1AzhULjtME4UIyzKedO/oAAxiBHsNoYMlhluDx2 u8ApZG8Cx9Pmh4Ue6trx9096meGe4YDXhOuzKwsjbiMOnywebUqhPb71Ix/ZtZIKA4 CYNMcqLX6zguUUE67mRynpdnjhjvxyxScyzt3+Mt+S6V8jMEc8VwVAbiHKKRA40F33 t+9GAS3bdJ9PGzQ1U1XQKrWq/vPqCCnAkcbV6ZwK8QAoC6iVe9y+qX9zCDjYTcIz9f HSGfPF776GA+gw9t3HF0hKDajNKudhe/mNR4suJiI2WzMGQnNyzXnI19qOSRb9AxOo cH0x2BCiyW2Ww== From: Jeff Layton To: chuck.lever@oracle.com Cc: neilb@suse.de, linux-nfs@vger.kernel.org Subject: [PATCH v5 3/5] nfsd: rework refcounting in filecache Date: Tue, 1 Nov 2022 10:46:45 -0400 Message-Id: <20221101144647.136696-4-jlayton@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221101144647.136696-1-jlayton@kernel.org> References: <20221101144647.136696-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org The filecache refcounting is a bit non-standard for something searchable by RCU, in that we maintain a sentinel reference while it's hashed. This in turn requires that we have to do things differently in the "put" depending on whether its hashed, which we believe to have led to races. There are other problems in here too. nfsd_file_close_inode_sync can end up freeing an nfsd_file while there are still outstanding references to it, and there are a number of subtle ToC/ToU races. Rework the code so that the refcount is what drives the lifecycle. When the refcount goes to zero, then unhash and rcu free the object. With this change, the LRU carries a reference. Take special care to deal with it when removing an entry from the list. Signed-off-by: Jeff Layton --- fs/nfsd/filecache.c | 247 ++++++++++++++++++++++---------------------- fs/nfsd/trace.h | 1 + 2 files changed, 123 insertions(+), 125 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 0bf3727455e2..e67297ad12bf 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -303,8 +303,7 @@ nfsd_file_alloc(struct nfsd_file_lookup_key *key, unsigned int may) if (key->gc) __set_bit(NFSD_FILE_GC, &nf->nf_flags); nf->nf_inode = key->inode; - /* nf_ref is pre-incremented for hash table */ - refcount_set(&nf->nf_ref, 2); + refcount_set(&nf->nf_ref, 1); nf->nf_may = key->need; nf->nf_mark = NULL; } @@ -353,24 +352,35 @@ nfsd_file_unhash(struct nfsd_file *nf) return false; } -static bool +static void nfsd_file_free(struct nfsd_file *nf) { s64 age = ktime_to_ms(ktime_sub(ktime_get(), nf->nf_birthtime)); - bool flush = false; trace_nfsd_file_free(nf); this_cpu_inc(nfsd_file_releases); this_cpu_add(nfsd_file_total_age, age); + nfsd_file_unhash(nf); + + /* + * We call fsync here in order to catch writeback errors. It's not + * strictly required by the protocol, but an nfsd_file coule get + * evicted from the cache before a COMMIT comes in. If another + * task were to open that file in the interim and scrape the error, + * then the client may never see it. By calling fsync here, we ensure + * that writeback happens before the entry is freed, and that any + * errors reported result in the write verifier changing. + */ + nfsd_file_fsync(nf); + if (nf->nf_mark) nfsd_file_mark_put(nf->nf_mark); if (nf->nf_file) { get_file(nf->nf_file); filp_close(nf->nf_file, NULL); fput(nf->nf_file); - flush = true; } /* @@ -378,10 +388,9 @@ nfsd_file_free(struct nfsd_file *nf) * WARN and leak it to preserve system stability. */ if (WARN_ON_ONCE(!list_empty(&nf->nf_lru))) - return flush; + return; call_rcu(&nf->nf_rcu, nfsd_file_slab_free); - return flush; } static bool @@ -397,17 +406,23 @@ nfsd_file_check_writeback(struct nfsd_file *nf) mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK); } -static void nfsd_file_lru_add(struct nfsd_file *nf) +static bool nfsd_file_lru_add(struct nfsd_file *nf) { set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags); - if (list_lru_add(&nfsd_file_lru, &nf->nf_lru)) + if (list_lru_add(&nfsd_file_lru, &nf->nf_lru)) { trace_nfsd_file_lru_add(nf); + return true; + } + return false; } -static void nfsd_file_lru_remove(struct nfsd_file *nf) +static bool nfsd_file_lru_remove(struct nfsd_file *nf) { - if (list_lru_del(&nfsd_file_lru, &nf->nf_lru)) + if (list_lru_del(&nfsd_file_lru, &nf->nf_lru)) { trace_nfsd_file_lru_del(nf); + return true; + } + return false; } struct nfsd_file * @@ -418,86 +433,80 @@ nfsd_file_get(struct nfsd_file *nf) return NULL; } -static void +/** + * nfsd_file_unhash_and_queue - unhash a file and queue it to the dispose list + * @nf: nfsd_file to be unhashed and queued + * @dispose: list to which it should be queued + * + * Attempt to unhash a nfsd_file and queue it to the given list. Each file + * will have a reference held on behalf of the list. That reference may come + * from the LRU, or we may need to take one. If we can't get a reference, + * ignore it altogether. + */ +static bool nfsd_file_unhash_and_queue(struct nfsd_file *nf, struct list_head *dispose) { trace_nfsd_file_unhash_and_queue(nf); if (nfsd_file_unhash(nf)) { - /* caller must call nfsd_file_dispose_list() later */ - nfsd_file_lru_remove(nf); + /* + * If we remove it from the LRU, then just use that + * reference for the dispose list. Otherwise, we need + * to take a reference. If that fails, just ignore + * the file altogether. + */ + if (!nfsd_file_lru_remove(nf) && !nfsd_file_get(nf)) + return false; list_add(&nf->nf_lru, dispose); + return true; } + return false; } -static void -nfsd_file_put_noref(struct nfsd_file *nf) -{ - trace_nfsd_file_put(nf); - - if (refcount_dec_and_test(&nf->nf_ref)) { - WARN_ON(test_bit(NFSD_FILE_HASHED, &nf->nf_flags)); - nfsd_file_lru_remove(nf); - nfsd_file_free(nf); - } -} - -static void -nfsd_file_unhash_and_put(struct nfsd_file *nf) -{ - if (nfsd_file_unhash(nf)) - nfsd_file_put_noref(nf); -} - +/** + * nfsd_file_put - put the reference to a nfsd_file + * @nf: nfsd_file of which to put the reference + * + * Put a reference to a nfsd_file. In the v4 case, we just put the + * reference immediately. In the GC case, if the reference would be + * the last one, the put it on the LRU instead to be cleaned up later. + */ void nfsd_file_put(struct nfsd_file *nf) { might_sleep(); + trace_nfsd_file_put(nf); - if (test_bit(NFSD_FILE_GC, &nf->nf_flags)) - nfsd_file_lru_add(nf); - else if (refcount_read(&nf->nf_ref) == 2) - nfsd_file_unhash_and_put(nf); - - if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { - nfsd_file_fsync(nf); - nfsd_file_put_noref(nf); - } else if (nf->nf_file && test_bit(NFSD_FILE_GC, &nf->nf_flags)) { - nfsd_file_put_noref(nf); - nfsd_file_schedule_laundrette(); - } else - nfsd_file_put_noref(nf); -} - -static void -nfsd_file_dispose_list(struct list_head *dispose) -{ - struct nfsd_file *nf; - - while(!list_empty(dispose)) { - nf = list_first_entry(dispose, struct nfsd_file, nf_lru); - list_del_init(&nf->nf_lru); - nfsd_file_fsync(nf); - nfsd_file_put_noref(nf); + /* + * The HASHED check is racy. We may end up with the occasional + * unhashed entry on the LRU, but they should get cleaned up + * like any other. + */ + if (test_bit(NFSD_FILE_GC, &nf->nf_flags) && + test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { + /* + * If this is the last reference (nf_ref == 1), then transfer + * it to the LRU. If the add to the LRU fails, just put it as + * usual. + */ + if (refcount_dec_not_one(&nf->nf_ref) || nfsd_file_lru_add(nf)) { + nfsd_file_schedule_laundrette(); + return; + } } + if (refcount_dec_and_test(&nf->nf_ref)) + nfsd_file_free(nf); } static void -nfsd_file_dispose_list_sync(struct list_head *dispose) +nfsd_file_dispose_list(struct list_head *dispose) { - bool flush = false; struct nfsd_file *nf; while(!list_empty(dispose)) { nf = list_first_entry(dispose, struct nfsd_file, nf_lru); list_del_init(&nf->nf_lru); - nfsd_file_fsync(nf); - if (!refcount_dec_and_test(&nf->nf_ref)) - continue; - if (nfsd_file_free(nf)) - flush = true; + nfsd_file_free(nf); } - if (flush) - flush_delayed_fput(); } static void @@ -567,21 +576,8 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru, struct list_head *head = arg; struct nfsd_file *nf = list_entry(item, struct nfsd_file, nf_lru); - /* - * Do a lockless refcount check. The hashtable holds one reference, so - * we look to see if anything else has a reference, or if any have - * been put since the shrinker last ran. Those don't get unhashed and - * released. - * - * Note that in the put path, we set the flag and then decrement the - * counter. Here we check the counter and then test and clear the flag. - * That order is deliberate to ensure that we can do this locklessly. - */ - if (refcount_read(&nf->nf_ref) > 1) { - list_lru_isolate(lru, &nf->nf_lru); - trace_nfsd_file_gc_in_use(nf); - return LRU_REMOVED; - } + /* We should only be dealing with GC entries here */ + WARN_ON_ONCE(!test_bit(NFSD_FILE_GC, &nf->nf_flags)); /* * Don't throw out files that are still undergoing I/O or @@ -592,40 +588,30 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru, return LRU_SKIP; } + /* If it was recently added to the list, skip it */ if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags)) { trace_nfsd_file_gc_referenced(nf); return LRU_ROTATE; } - if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { - trace_nfsd_file_gc_hashed(nf); - return LRU_SKIP; + /* + * Put the reference held on behalf of the LRU. If it wasn't the last + * one, then just remove it from the LRU and ignore it. + */ + if (!refcount_dec_and_test(&nf->nf_ref)) { + trace_nfsd_file_gc_in_use(nf); + list_lru_isolate(lru, &nf->nf_lru); + return LRU_REMOVED; } + /* Refcount went to zero. Unhash it and queue it to the dispose list */ + nfsd_file_unhash(nf); list_lru_isolate_move(lru, &nf->nf_lru, head); this_cpu_inc(nfsd_file_evictions); trace_nfsd_file_gc_disposed(nf); return LRU_REMOVED; } -/* - * Unhash items on @dispose immediately, then queue them on the - * disposal workqueue to finish releasing them in the background. - * - * cel: Note that between the time list_lru_shrink_walk runs and - * now, these items are in the hash table but marked unhashed. - * Why release these outside of lru_cb ? There's no lock ordering - * problem since lru_cb currently takes no lock. - */ -static void nfsd_file_gc_dispose_list(struct list_head *dispose) -{ - struct nfsd_file *nf; - - list_for_each_entry(nf, dispose, nf_lru) - nfsd_file_hash_remove(nf); - nfsd_file_dispose_list_delayed(dispose); -} - static void nfsd_file_gc(void) { @@ -635,7 +621,7 @@ nfsd_file_gc(void) ret = list_lru_walk(&nfsd_file_lru, nfsd_file_lru_cb, &dispose, list_lru_count(&nfsd_file_lru)); trace_nfsd_file_gc_removed(ret, list_lru_count(&nfsd_file_lru)); - nfsd_file_gc_dispose_list(&dispose); + nfsd_file_dispose_list_delayed(&dispose); } static void @@ -660,7 +646,7 @@ nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc) ret = list_lru_shrink_walk(&nfsd_file_lru, sc, nfsd_file_lru_cb, &dispose); trace_nfsd_file_shrinker_removed(ret, list_lru_count(&nfsd_file_lru)); - nfsd_file_gc_dispose_list(&dispose); + nfsd_file_dispose_list_delayed(&dispose); return ret; } @@ -671,8 +657,11 @@ static struct shrinker nfsd_file_shrinker = { }; /* - * Find all cache items across all net namespaces that match @inode and - * move them to @dispose. The lookup is atomic wrt nfsd_file_acquire(). + * Find all cache items across all net namespaces that match @inode, unhash + * them, take references and then put them on @dispose if that was successful. + * + * The nfsd_file objects on the list will be unhashed, and each will have a + * reference taken. */ static unsigned int __nfsd_file_close_inode(struct inode *inode, struct list_head *dispose) @@ -690,8 +679,9 @@ __nfsd_file_close_inode(struct inode *inode, struct list_head *dispose) nfsd_file_rhash_params); if (!nf) break; - nfsd_file_unhash_and_queue(nf, dispose); - count++; + + if (nfsd_file_unhash_and_queue(nf, dispose)) + count++; } while (1); rcu_read_unlock(); return count; @@ -703,15 +693,23 @@ __nfsd_file_close_inode(struct inode *inode, struct list_head *dispose) * * Unhash and put all cache item associated with @inode. */ -static void +static unsigned int nfsd_file_close_inode(struct inode *inode) { - LIST_HEAD(dispose); + struct nfsd_file *nf; unsigned int count; + LIST_HEAD(dispose); count = __nfsd_file_close_inode(inode, &dispose); trace_nfsd_file_close_inode(inode, count); - nfsd_file_dispose_list_delayed(&dispose); + while(!list_empty(&dispose)) { + nf = list_first_entry(&dispose, struct nfsd_file, nf_lru); + list_del_init(&nf->nf_lru); + trace_nfsd_file_closing(nf); + if (refcount_dec_and_test(&nf->nf_ref)) + nfsd_file_free(nf); + } + return count; } /** @@ -723,19 +721,15 @@ nfsd_file_close_inode(struct inode *inode) void nfsd_file_close_inode_sync(struct inode *inode) { - LIST_HEAD(dispose); - unsigned int count; - - count = __nfsd_file_close_inode(inode, &dispose); - trace_nfsd_file_close_inode_sync(inode, count); - nfsd_file_dispose_list_sync(&dispose); + if (nfsd_file_close_inode(inode)) + flush_delayed_fput(); } /** * nfsd_file_delayed_close - close unused nfsd_files * @work: dummy * - * Walk the LRU list and close any entries that have not been used since + * Walk the LRU list and destroy any entries that have not been used since * the last scan. */ static void @@ -1056,8 +1050,10 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, rcu_read_lock(); nf = rhashtable_lookup(&nfsd_file_rhash_tbl, &key, nfsd_file_rhash_params); - if (nf) - nf = nfsd_file_get(nf); + if (nf) { + if (!nfsd_file_lru_remove(nf)) + nf = nfsd_file_get(nf); + } rcu_read_unlock(); if (nf) goto wait_for_construction; @@ -1092,11 +1088,11 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, goto out; } open_retry = false; - nfsd_file_put_noref(nf); + if (refcount_dec_and_test(&nf->nf_ref)) + nfsd_file_free(nf); goto retry; } - nfsd_file_lru_remove(nf); this_cpu_inc(nfsd_file_cache_hits); status = nfserrno(nfsd_open_break_lease(file_inode(nf->nf_file), may_flags)); @@ -1106,7 +1102,8 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, this_cpu_inc(nfsd_file_acquisitions); *pnf = nf; } else { - nfsd_file_put(nf); + if (refcount_dec_and_test(&nf->nf_ref)) + nfsd_file_free(nf); nf = NULL; } @@ -1133,7 +1130,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, * then unhash. */ if (status != nfs_ok || key.inode->i_nlink == 0) - nfsd_file_unhash_and_put(nf); + nfsd_file_unhash(nf); clear_bit_unlock(NFSD_FILE_PENDING, &nf->nf_flags); smp_mb__after_atomic(); wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING); diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h index 940252482fd4..a44ded06af87 100644 --- a/fs/nfsd/trace.h +++ b/fs/nfsd/trace.h @@ -906,6 +906,7 @@ DEFINE_EVENT(nfsd_file_class, name, \ DEFINE_NFSD_FILE_EVENT(nfsd_file_free); DEFINE_NFSD_FILE_EVENT(nfsd_file_unhash); DEFINE_NFSD_FILE_EVENT(nfsd_file_put); +DEFINE_NFSD_FILE_EVENT(nfsd_file_closing); DEFINE_NFSD_FILE_EVENT(nfsd_file_unhash_and_queue); TRACE_EVENT(nfsd_file_alloc, From patchwork Tue Nov 1 14:46:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 13027021 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 6B1B0C4321E for ; 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d=kernel.org; s=k20201202; t=1667314012; bh=o6UOuYz2auietgT4/1S7eiLYAmRw6I4SWm3wNjnuvMU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AjJVHWfH33pALEtWoSd/2BnCr9sB5dcWzgY/PusUk9btiwIzIVBloc1mj9quGrLgh khfHs1NQUWwS5LQSRKreBRxKeQSM7QqhpA2TlhYyO/Kp4kVESIVlyUdBS2HAzBnk3Y h0hMGl5uwZhYuwCPn/Pij7Y6hgLoM/nbn3qPR1iT3zUzNFmkT1FIrtDUk64/tS4R9h RwJW7arEqLCn/JoUPqXhQGiHQlG63G5pHbwlkbLlT74DmpeIWDD9EVgH3ztvmBxgm3 R4fnSMNoz1NIcuaPZlFuzB5LzpZrnI3CiJINwDSpDRQtPa4WsEhDUGlYPGnq/TMIeH eIOqMzrHwyPgQ== From: Jeff Layton To: chuck.lever@oracle.com Cc: neilb@suse.de, linux-nfs@vger.kernel.org Subject: [PATCH v5 4/5] nfsd: close race between unhashing and LRU addition Date: Tue, 1 Nov 2022 10:46:46 -0400 Message-Id: <20221101144647.136696-5-jlayton@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221101144647.136696-1-jlayton@kernel.org> References: <20221101144647.136696-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org The list_lru_add and list_lru_del functions use list_empty checks to see whether the object is already on the LRU. That's fine in most cases, but we occasionally repurpose nf_lru after unhashing. It's possible for an LRU removal to remove it from a different list altogether if we lose a race. Add a new NFSD_FILE_LRU flag, which indicates that the object actually resides on the LRU and not some other list. Use that when adding and removing it from the LRU instead of just relying on list_empty checks. Add an extra HASHED check after adding the entry to the LRU. If it's now clear, just remove it from the LRU again and put the reference if that remove is successful. Signed-off-by: Jeff Layton --- fs/nfsd/filecache.c | 50 ++++++++++++++++++++++++++++++--------------- fs/nfsd/filecache.h | 1 + 2 files changed, 35 insertions(+), 16 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index e67297ad12bf..bcea201d79c3 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -409,18 +409,22 @@ nfsd_file_check_writeback(struct nfsd_file *nf) static bool nfsd_file_lru_add(struct nfsd_file *nf) { set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags); - if (list_lru_add(&nfsd_file_lru, &nf->nf_lru)) { - trace_nfsd_file_lru_add(nf); - return true; + if (!test_and_set_bit(NFSD_FILE_LRU, &nf->nf_flags)) { + if (list_lru_add(&nfsd_file_lru, &nf->nf_lru)) { + trace_nfsd_file_lru_add(nf); + return true; + } } return false; } static bool nfsd_file_lru_remove(struct nfsd_file *nf) { - if (list_lru_del(&nfsd_file_lru, &nf->nf_lru)) { - trace_nfsd_file_lru_del(nf); - return true; + if (test_and_clear_bit(NFSD_FILE_LRU, &nf->nf_flags)) { + if (list_lru_del(&nfsd_file_lru, &nf->nf_lru)) { + trace_nfsd_file_lru_del(nf); + return true; + } } return false; } @@ -476,21 +480,31 @@ nfsd_file_put(struct nfsd_file *nf) might_sleep(); trace_nfsd_file_put(nf); - /* - * The HASHED check is racy. We may end up with the occasional - * unhashed entry on the LRU, but they should get cleaned up - * like any other. - */ if (test_bit(NFSD_FILE_GC, &nf->nf_flags) && test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { /* - * If this is the last reference (nf_ref == 1), then transfer - * it to the LRU. If the add to the LRU fails, just put it as - * usual. + * If this is the last reference (nf_ref == 1), then try to + * transfer it to the LRU. */ - if (refcount_dec_not_one(&nf->nf_ref) || nfsd_file_lru_add(nf)) { - nfsd_file_schedule_laundrette(); + if (refcount_dec_not_one(&nf->nf_ref)) return; + + /* Try to add it to the LRU. If that fails, decrement. */ + if (nfsd_file_lru_add(nf)) { + /* If it's still hashed, we're done */ + if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { + nfsd_file_schedule_laundrette(); + return; + } + + /* + * We're racing with unhashing, so try to remove it from + * the LRU. If removal fails, then someone else already + * has our reference and we're done. If it succeeds, + * fall through to decrement. + */ + if (!nfsd_file_lru_remove(nf)) + return; } } if (refcount_dec_and_test(&nf->nf_ref)) @@ -594,6 +608,10 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru, return LRU_ROTATE; } + /* Make sure we're not racing with another removal. */ + if (!test_and_clear_bit(NFSD_FILE_LRU, &nf->nf_flags)) + return LRU_SKIP; + /* * Put the reference held on behalf of the LRU. If it wasn't the last * one, then just remove it from the LRU and ignore it. diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h index b7efb2c3ddb1..e52ab7d5a44c 100644 --- a/fs/nfsd/filecache.h +++ b/fs/nfsd/filecache.h @@ -39,6 +39,7 @@ struct nfsd_file { #define NFSD_FILE_PENDING (1) #define NFSD_FILE_REFERENCED (2) #define NFSD_FILE_GC (3) +#define NFSD_FILE_LRU (4) /* file is on LRU */ unsigned long nf_flags; struct inode *nf_inode; /* don't deref */ refcount_t nf_ref; From patchwork Tue Nov 1 14:46:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 13027020 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 3CED0C43217 for ; Tue, 1 Nov 2022 14:46:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230355AbiKAOqz (ORCPT ); Tue, 1 Nov 2022 10:46:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230358AbiKAOqy (ORCPT ); Tue, 1 Nov 2022 10:46:54 -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 EDF181BEA4 for ; Tue, 1 Nov 2022 07:46:53 -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 7DA7E615F5 for ; Tue, 1 Nov 2022 14:46:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85A1EC433D6; Tue, 1 Nov 2022 14:46:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667314012; bh=3xbsnDoLxPF9K/ZVhMDTIHTZ4995bSqZvh7/BGqAvPI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E5HXDTsdjJPd+rmRqJIosAj9y7RgT5GDLYwqpdtvY6I0nHGKU+wBAJGYiIvYdg3UR BHNAnBsoimgrTmDTubVoPVf0uIxGtbnuN6zYXYWy51Wi3Rz/l7xdzrJ68fgz1sf4vu Tz0gaUX2x8VCoTQ5KA7g4NOVnNIdsCOEXJKxcjb3pnBPm84lL9dJgMgKCCc9/FDxuD 68fZpnMUJYgvag7JBBE8w0fubkYO5NSBqNz7UYHr52AHST5wAFzC5v/RzdqY1EQePt 5/2+lV91USJd+QyM6XMYsboJbmFJtwsLbeNkSXMIUJAwy/+RElPQRU8AOaDM/gB6+E XBsO3Ynufi/nA== From: Jeff Layton To: chuck.lever@oracle.com Cc: neilb@suse.de, linux-nfs@vger.kernel.org Subject: [PATCH v5 5/5] nfsd: fix up the filecache laundrette scheduling Date: Tue, 1 Nov 2022 10:46:47 -0400 Message-Id: <20221101144647.136696-6-jlayton@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221101144647.136696-1-jlayton@kernel.org> References: <20221101144647.136696-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org We don't really care whether there are hashed entries when it comes to scheduling the laundrette. They might all be non-gc entries, after all. We only want to schedule it if there are entries on the LRU. Switch to using list_lru_count, and move the check into nfsd_file_gc_worker. The other callsite in nfsd_file_put doesn't need to count entries, since it only schedules the laundrette after adding an entry to the LRU. Signed-off-by: Jeff Layton --- fs/nfsd/filecache.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index bcea201d79c3..a47b5b39111a 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -187,12 +187,9 @@ static const struct rhashtable_params nfsd_file_rhash_params = { static void nfsd_file_schedule_laundrette(void) { - if ((atomic_read(&nfsd_file_rhash_tbl.nelems) == 0) || - test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 0) - return; - - queue_delayed_work(system_wq, &nfsd_filecache_laundrette, - NFSD_LAUNDRETTE_DELAY); + if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags)) + queue_delayed_work(system_wq, &nfsd_filecache_laundrette, + NFSD_LAUNDRETTE_DELAY); } static void @@ -646,7 +643,8 @@ static void nfsd_file_gc_worker(struct work_struct *work) { nfsd_file_gc(); - nfsd_file_schedule_laundrette(); + if (list_lru_count(&nfsd_file_lru)) + nfsd_file_schedule_laundrette(); } static unsigned long