From patchwork Thu Nov 7 20:52:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Sandeen X-Patchwork-Id: 11233763 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 55BA5139A for ; Thu, 7 Nov 2019 20:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CD5521D7E for ; Thu, 7 Nov 2019 20:53:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727552AbfKGUxx (ORCPT ); Thu, 7 Nov 2019 15:53:53 -0500 Received: from sandeen.net ([63.231.237.45]:35646 "EHLO sandeen.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727480AbfKGUxp (ORCPT ); Thu, 7 Nov 2019 15:53:45 -0500 Received: by sandeen.net (Postfix, from userid 500) id CD9741911D; Thu, 7 Nov 2019 14:52:35 -0600 (CST) From: Eric Sandeen To: linux-fsdevel@vger.kernel.org Cc: viro@zeniv.linux.org.uk Subject: [PATCH 1/2] fs: avoid softlockups in s_inodes iterators Date: Thu, 7 Nov 2019 14:52:33 -0600 Message-Id: <1573159954-27846-2-git-send-email-sandeen@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1573159954-27846-1-git-send-email-sandeen@redhat.com> References: <1573159954-27846-1-git-send-email-sandeen@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Anything that walks all inodes on sb->s_inodes list without rescheduling risks softlockups. Previous efforts were made in 2 functions, see: c27d82f fs/drop_caches.c: avoid softlockups in drop_pagecache_sb() ac05fbb inode: don't softlockup when evicting inodes but there hasn't been an audit of all walkers, so do that now. This also consistently moves the cond_resched() calls to the bottom of each loop in cases where it already exists. One loop remains: remove_dquot_ref(), because I'm not quite sure how to deal with that one w/o taking the i_lock. Signed-off-by: Eric Sandeen Reviewed-by: Jan Kara --- fs/drop_caches.c | 2 +- fs/inode.c | 7 +++++++ fs/notify/fsnotify.c | 1 + fs/quota/dquot.c | 1 + 4 files changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/drop_caches.c b/fs/drop_caches.c index d31b6c7..dc1a1d5 100644 --- a/fs/drop_caches.c +++ b/fs/drop_caches.c @@ -35,11 +35,11 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused) spin_unlock(&inode->i_lock); spin_unlock(&sb->s_inode_list_lock); - cond_resched(); invalidate_mapping_pages(inode->i_mapping, 0, -1); iput(toput_inode); toput_inode = inode; + cond_resched(); spin_lock(&sb->s_inode_list_lock); } spin_unlock(&sb->s_inode_list_lock); diff --git a/fs/inode.c b/fs/inode.c index fef457a..96d62d9 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -676,6 +676,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) struct inode *inode, *next; LIST_HEAD(dispose); +again: spin_lock(&sb->s_inode_list_lock); list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { spin_lock(&inode->i_lock); @@ -698,6 +699,12 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) inode_lru_list_del(inode); spin_unlock(&inode->i_lock); list_add(&inode->i_lru, &dispose); + if (need_resched()) { + spin_unlock(&sb->s_inode_list_lock); + cond_resched(); + dispose_list(&dispose); + goto again; + } } spin_unlock(&sb->s_inode_list_lock); diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 2ecef61..ac9eb27 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -77,6 +77,7 @@ static void fsnotify_unmount_inodes(struct super_block *sb) iput_inode = inode; + cond_resched(); spin_lock(&sb->s_inode_list_lock); } spin_unlock(&sb->s_inode_list_lock); diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 6e826b4..4a085b3 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -985,6 +985,7 @@ static int add_dquot_ref(struct super_block *sb, int type) * later. */ old_inode = inode; + cond_resched(); spin_lock(&sb->s_inode_list_lock); } spin_unlock(&sb->s_inode_list_lock); From patchwork Thu Nov 7 20:52:34 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Sandeen X-Patchwork-Id: 11233767 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 6228F1864 for ; Thu, 7 Nov 2019 20:53:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FD1221D79 for ; Thu, 7 Nov 2019 20:53:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727543AbfKGUxx (ORCPT ); Thu, 7 Nov 2019 15:53:53 -0500 Received: from sandeen.net ([63.231.237.45]:35652 "EHLO sandeen.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727487AbfKGUxp (ORCPT ); Thu, 7 Nov 2019 15:53:45 -0500 Received: by sandeen.net (Postfix, from userid 500) id DC2F119120; Thu, 7 Nov 2019 14:52:35 -0600 (CST) From: Eric Sandeen To: linux-fsdevel@vger.kernel.org Cc: viro@zeniv.linux.org.uk Subject: [PATCH 2/2] fs: call fsnotify_sb_delete after evict_inodes Date: Thu, 7 Nov 2019 14:52:34 -0600 Message-Id: <1573159954-27846-3-git-send-email-sandeen@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1573159954-27846-1-git-send-email-sandeen@redhat.com> References: <1573159954-27846-1-git-send-email-sandeen@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When a filesystem is unmounted, we currently call fsnotify_sb_delete() before evict_inodes(), which means that fsnotify_unmount_inodes() must iterate over all inodes on the superblock, even though it will only act on inodes with a refcount. This is inefficient and can lead to livelocks as it iterates over many unrefcounted inodes. However, since fsnotify_sb_delete() and evict_inodes() are working on orthogonal sets of inodes (fsnotify_sb_delete() only cares about nonzero refcount, and evict_inodes() only cares about zero refcount), we can swap the order of the calls. The fsnotify call will then have a much smaller list to walk (any refcounted inodes). This should speed things up overall, and avoid livelocks in fsnotify_unmount_inodes(). Signed-off-by: Eric Sandeen Reviewed-by: Jan Kara --- fs/notify/fsnotify.c | 3 +++ fs/super.c | 4 +++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index ac9eb27..f44e39c 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -57,6 +57,9 @@ static void fsnotify_unmount_inodes(struct super_block *sb) * doing an __iget/iput with SB_ACTIVE clear would actually * evict all inodes with zero i_count from icache which is * unnecessarily violent and may in fact be illegal to do. + * However, we should have been called /after/ evict_inodes + * removed all zero refcount inodes, in any case. Test to + * be sure. */ if (!atomic_read(&inode->i_count)) { spin_unlock(&inode->i_lock); diff --git a/fs/super.c b/fs/super.c index cfadab2..cd35253 100644 --- a/fs/super.c +++ b/fs/super.c @@ -448,10 +448,12 @@ void generic_shutdown_super(struct super_block *sb) sync_filesystem(sb); sb->s_flags &= ~SB_ACTIVE; - fsnotify_sb_delete(sb); cgroup_writeback_umount(); + /* evict all inodes with zero refcount */ evict_inodes(sb); + /* only nonzero refcount inodes can have marks */ + fsnotify_sb_delete(sb); if (sb->s_dio_done_wq) { destroy_workqueue(sb->s_dio_done_wq);