From mboxrd@z Thu Jan 1 00:00:00 1970 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 41B07C433DB for ; Sun, 7 Mar 2021 13:49:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12B7865100 for ; Sun, 7 Mar 2021 13:49:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231458AbhCGNtQ (ORCPT ); Sun, 7 Mar 2021 08:49:16 -0500 Received: from wforward1-smtp.messagingengine.com ([64.147.123.30]:43737 "EHLO wforward1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231460AbhCGNtE (ORCPT ); Sun, 7 Mar 2021 08:49:04 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailforward.west.internal (Postfix) with ESMTP id EEF0618EA; Sun, 7 Mar 2021 08:49:03 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Sun, 07 Mar 2021 08:49:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=KRrx6v 5Iva7HeBXkAOXPFkd0rrVRpEobdX+hdDIjnvs=; b=O9TkVsR2SWibCdqQuH5wZd adpCTWXFMQCObhsnikv/4kOGqeoRClKDEmLTM0EJ0J12GpmOowEq0MPkOASdLckJ 1DSfwqDQ4cxms9oTYsdTaDgAsbZ4b7h2Q/M0yvF7t3MSJ/z4SQQ5PIs1iPgnhH8Z K6/zPZarwLZ095xLewkruOQgPhYDzOA/pEnUQZeGqanS5X62y4LknhcefJnyrFGz 8QReveJo9AJkomhLQp4zaCxH1cx9Gi6MmhrKtX5v26Kcw8UW9KYi6lpiK7mkJOmX mnPt23VOzDcxEpOvAy9P+Y/TKq8U9Kon0O0+X2BpTZSiW5bX5/MEZdNRv6zXkXNg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledruddutddggeekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuggftrfgrthhtvghrnhepieetveehuedvhfdtgfdvieeiheehfeelveevheejud etveeuveeludejjefgteehnecukfhppeekfedrkeeirdejgedrieegnecuvehluhhsthgv rhfuihiivgepkeenucfrrghrrghmpehmrghilhhfrhhomhepghhrvghgsehkrhhorghhrd gtohhm X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 32E0824005A; Sun, 7 Mar 2021 08:49:03 -0500 (EST) Subject: FAILED: patch "[PATCH] btrfs: fix race between extent freeing/allocation when using" failed to apply to 4.19-stable tree To: nborisov@suse.com, dsterba@suse.com, josef@toxicpanda.com, stable@vger.kernel.org Cc: From: Date: Sun, 07 Mar 2021 14:48:56 +0100 Message-ID: <161512493610514@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 3c17916510428dbccdf657de050c34e208347089 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Mon, 8 Feb 2021 10:26:54 +0200 Subject: [PATCH] btrfs: fix race between extent freeing/allocation when using bitmaps During allocation the allocator will try to allocate an extent using cluster policy. Once the current cluster is exhausted it will remove the entry under btrfs_free_cluster::lock and subsequently acquire btrfs_free_space_ctl::tree_lock to dispose of the already-deleted entry and adjust btrfs_free_space_ctl::total_bitmap. This poses a problem because there exists a race condition between removing the entry under one lock and doing the necessary accounting holding a different lock since extent freeing only uses the 2nd lock. This can result in the following situation: T1: T2: btrfs_alloc_from_cluster insert_into_bitmap if (entry->bytes == 0) if (block_group && !list_empty(&block_group->cluster_list)) { rb_erase(entry) spin_unlock(&cluster->lock); (total_bitmaps is still 4) spin_lock(&cluster->lock); root> spin_lock(&ctl->tree_lock); recalculate_thresholds To fix this ensure that once depleted, the cluster entry is deleted when both cluster lock and tree locks are held in the allocator (T1), this ensures that even if there is a race with a concurrent insert_into_bitmap call it will correctly find the entry in the cluster and add the new space to it. CC: # 4.4+ Reviewed-by: Josef Bacik Signed-off-by: Nikolay Borisov Signed-off-by: David Sterba diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 5400294bd271..abcf951e6b44 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3125,8 +3125,6 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, entry->bytes -= bytes; } - if (entry->bytes == 0) - rb_erase(&entry->offset_index, &cluster->root); break; } out: @@ -3143,7 +3141,10 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, ctl->free_space -= bytes; if (!entry->bitmap && !btrfs_free_space_trimmed(entry)) ctl->discardable_bytes[BTRFS_STAT_CURR] -= bytes; + + spin_lock(&cluster->lock); if (entry->bytes == 0) { + rb_erase(&entry->offset_index, &cluster->root); ctl->free_extents--; if (entry->bitmap) { kmem_cache_free(btrfs_free_space_bitmap_cachep, @@ -3156,6 +3157,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, kmem_cache_free(btrfs_free_space_cachep, entry); } + spin_unlock(&cluster->lock); spin_unlock(&ctl->tree_lock); return ret;