From patchwork Fri May 8 12:23:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Konstantin Khlebnikov X-Patchwork-Id: 11536431 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C9CE2912 for ; Fri, 8 May 2020 12:23:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 86540216FD for ; Fri, 8 May 2020 12:23:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="OOLeXBCf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 86540216FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F3B86900007; Fri, 8 May 2020 08:23:31 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id EC74E900002; Fri, 8 May 2020 08:23:31 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DB811900007; Fri, 8 May 2020 08:23:31 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id C30FF900002 for ; Fri, 8 May 2020 08:23:31 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8CED814545 for ; Fri, 8 May 2020 12:23:31 +0000 (UTC) X-FDA: 76793467422.07.bikes89_58e83e8d86552 X-Spam-Summary: 30,2,0,09725fed0a06db76,d41d8cd98f00b204,khlebnikov@yandex-team.ru,,RULES_HIT:41:152:355:379:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:2198:2199:2393:2559:2562:2898:3138:3139:3140:3141:3142:3353:3867:3870:3872:4321:5007:6119:6120:6261:6653:7901:9207:10010:10400:11026:11473:11658:11914:12043:12048:12296:12297:12438:12517:12519:12555:12760:13255:14096:14097:14181:14394:14687:14721:14922:21080:21324:21433:21451:21627:21990:30054:30070:30075,0,RBL:95.108.205.193:@yandex-team.ru:.lbl8.mailshell.net-66.100.201.201 62.2.3.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:1:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: bikes89_58e83e8d86552 X-Filterd-Recvd-Size: 4835 Received: from forwardcorp1o.mail.yandex.net (forwardcorp1o.mail.yandex.net [95.108.205.193]) by imf31.hostedemail.com (Postfix) with ESMTP for ; Fri, 8 May 2020 12:23:30 +0000 (UTC) Received: from mxbackcorp2j.mail.yandex.net (mxbackcorp2j.mail.yandex.net [IPv6:2a02:6b8:0:1619::119]) by forwardcorp1o.mail.yandex.net (Yandex) with ESMTP id 389F62E1574; Fri, 8 May 2020 15:23:29 +0300 (MSK) Received: from myt4-18a966dbd9be.qloud-c.yandex.net (myt4-18a966dbd9be.qloud-c.yandex.net [2a02:6b8:c00:12ad:0:640:18a9:66db]) by mxbackcorp2j.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id ar427vyawi-NSX4ptWY; Fri, 08 May 2020 15:23:29 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1588940609; bh=liJknFRYDA0nUUv0ro+iQXHRLau6qws9t8QCP/DSyVg=; h=In-Reply-To:Message-ID:References:Date:To:From:Subject:Cc; b=OOLeXBCfwoE6ZufUWCYkDj83HXktllePJsnMsIx9vr5wx0QX2UAsr1HG8rSOu8Omg hCskXJGWC8zlMJECTFy+TE+rgXbOXgjyzOM2bJUMmsZLj+koG8MwVHwzsFZVqOPa1c kb/l7qjGID09yskyKryJGtYdxXnUU4e2bJEkShxc= Authentication-Results: mxbackcorp2j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b080:7008::1:4]) by myt4-18a966dbd9be.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id uFJknMXhLs-NSWiskNQ; Fri, 08 May 2020 15:23:28 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) Subject: [PATCH RFC 6/8] dcache: stop walking siblings if remaining dentries all negative From: Konstantin Khlebnikov To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro Cc: Waiman Long Date: Fri, 08 May 2020 15:23:28 +0300 Message-ID: <158894060799.200862.477468763047350875.stgit@buzz> In-Reply-To: <158893941613.200862.4094521350329937435.stgit@buzz> References: <158893941613.200862.4094521350329937435.stgit@buzz> User-Agent: StGit/0.22-32-g6a05 MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Most walkers are interested only in positive dentries. Changes in simple_* libfs helpers are mostly cosmetic: it shouldn't cache negative dentries unless uses d_delete other than always_delete_dentry(). Signed-off-by: Konstantin Khlebnikov --- fs/dcache.c | 10 ++++++++++ fs/libfs.c | 10 +++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/fs/dcache.c b/fs/dcache.c index 44c6832d21d6..0fd2e02e507b 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1442,6 +1442,9 @@ static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry) struct check_mount *info = data; struct path path = { .mnt = info->mnt, .dentry = dentry }; + if (d_is_tail_negative(dentry)) + return D_WALK_SKIP_SIBLINGS; + if (likely(!d_mountpoint(dentry))) return D_WALK_CONTINUE; if (__path_is_mountpoint(&path)) { @@ -1688,6 +1691,10 @@ void shrink_dcache_for_umount(struct super_block *sb) static enum d_walk_ret find_submount(void *_data, struct dentry *dentry) { struct dentry **victim = _data; + + if (d_is_tail_negative(dentry)) + return D_WALK_SKIP_SIBLINGS; + if (d_mountpoint(dentry)) { __dget_dlock(dentry); *victim = dentry; @@ -3159,6 +3166,9 @@ static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) { struct dentry *root = data; if (dentry != root) { + if (d_is_tail_negative(dentry)) + return D_WALK_SKIP_SIBLINGS; + if (d_unhashed(dentry) || !dentry->d_inode) return D_WALK_SKIP; diff --git a/fs/libfs.c b/fs/libfs.c index 3759fbacf522..de944c241cf0 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -106,6 +106,10 @@ static struct dentry *scan_positives(struct dentry *cursor, spin_lock(&dentry->d_lock); while ((p = p->next) != &dentry->d_subdirs) { struct dentry *d = list_entry(p, struct dentry, d_child); + + if (d_is_tail_negative(d)) + break; + // we must at least skip cursors, to avoid livelocks if (d->d_flags & DCACHE_DENTRY_CURSOR) continue; @@ -255,7 +259,8 @@ static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev spin_unlock(&d->d_lock); if (likely(child)) break; - } + } else if (d_is_tail_negative(d)) + break; } spin_unlock(&parent->d_lock); dput(prev); @@ -408,6 +413,9 @@ int simple_empty(struct dentry *dentry) spin_lock(&dentry->d_lock); list_for_each_entry(child, &dentry->d_subdirs, d_child) { + if (d_is_tail_negative(child)) + break; + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); if (simple_positive(child)) { spin_unlock(&child->d_lock);