From patchwork Tue Oct 27 13:53:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 307303 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95C8CC388F9 for ; Tue, 27 Oct 2020 16:43:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BDC9218AC for ; Tue, 27 Oct 2020 16:43:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603817020; bh=vzAInNGIvcVAoYf6SO9RuuGhQ0XIGZPey4gJ2+u3GV8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=K27W2y/gtT8Pj0hFsET3N8Q+yVLUgxOhEXAZm5TUh5Ii0wZGdND5QTEgy2VejOLc8 rY1XuKnsxGych2Sz5OCuaEyUcqrXJ4IAQpevgagEIG4aLIZRKg/s0ZfbphH5OC2kJD 7+9Naanwoc0USuF9e19uFLHNZ/zxcg9hhICMg+kc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1810978AbgJ0Qgf (ORCPT ); Tue, 27 Oct 2020 12:36:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:40472 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1801839AbgJ0Pob (ORCPT ); Tue, 27 Oct 2020 11:44:31 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2ED312245D; Tue, 27 Oct 2020 15:43:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603813434; bh=vzAInNGIvcVAoYf6SO9RuuGhQ0XIGZPey4gJ2+u3GV8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UmgXhGyRJJKv034CUl40NGgGmQCHAhTceoaMQGZ1ymzIUiAcdPHy8yMDm0leKques lbndPqzzKYpW2UBuFy5+KbHeObcUcoTtgzkj13FAXYk3ysHX4lHFFqk5Om9/5ygjYy EunmGv8FYSHR/AmYC8m/jLH3PSSjoUlP3onkEOZE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kara , Theodore Tso , Sasha Levin Subject: [PATCH 5.9 551/757] ext4: discard preallocations before releasing group lock Date: Tue, 27 Oct 2020 14:53:21 +0100 Message-Id: <20201027135516.336527751@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135450.497324313@linuxfoundation.org> References: <20201027135450.497324313@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jan Kara [ Upstream commit 5b3dc19dda6691e8ab574e8eede1aef6f02a4f1c ] ext4_mb_discard_group_preallocations() can be releasing group lock with preallocations accumulated on its local list. Thus although discard_pa_seq was incremented and concurrent allocating processes will be retrying allocations, it can happen that premature ENOSPC error is returned because blocks used for preallocations are not available for reuse yet. Make sure we always free locally accumulated preallocations before releasing group lock. Fixes: 07b5b8e1ac40 ("ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling") Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20200924150959.4335-1-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/mballoc.c | 33 +++++++++++++-------------------- 1 file changed, 13 insertions(+), 20 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index ff47347012f4b..a8d99f676fb1f 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4160,7 +4160,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, struct ext4_buddy e4b; int err; int busy = 0; - int free = 0; + int free, free_total = 0; mb_debug(sb, "discard preallocation for group %u\n", group); if (list_empty(&grp->bb_prealloc_list)) @@ -4188,6 +4188,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, INIT_LIST_HEAD(&list); repeat: + free = 0; ext4_lock_group(sb, group); list_for_each_entry_safe(pa, tmp, &grp->bb_prealloc_list, pa_group_list) { @@ -4217,22 +4218,6 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, list_add(&pa->u.pa_tmp_list, &list); } - /* if we still need more blocks and some PAs were used, try again */ - if (free < needed && busy) { - busy = 0; - ext4_unlock_group(sb, group); - cond_resched(); - goto repeat; - } - - /* found anything to free? */ - if (list_empty(&list)) { - BUG_ON(free != 0); - mb_debug(sb, "Someone else may have freed PA for this group %u\n", - group); - goto out; - } - /* now free all selected PAs */ list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) { @@ -4250,14 +4235,22 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback); } -out: + free_total += free; + + /* if we still need more blocks and some PAs were used, try again */ + if (free_total < needed && busy) { + ext4_unlock_group(sb, group); + cond_resched(); + busy = 0; + goto repeat; + } ext4_unlock_group(sb, group); ext4_mb_unload_buddy(&e4b); put_bh(bitmap_bh); out_dbg: mb_debug(sb, "discarded (%d) blocks preallocated for group %u bb_free (%d)\n", - free, group, grp->bb_free); - return free; + free_total, group, grp->bb_free); + return free_total; } /*