From: Niu Yawei Subject: [PATCH] Fix race in ext4_mb_add_n_trim() Date: Mon, 07 Jan 2013 14:09:34 +0800 Message-ID: <50EA669E.1030008@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit To: linux-ext4@vger.kernel.org, yawei.niu@intel.com, Alex Zhuravlev Return-path: Received: from mail-pa0-f49.google.com ([209.85.220.49]:33525 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750776Ab3AGGJm (ORCPT ); Mon, 7 Jan 2013 01:09:42 -0500 Received: by mail-pa0-f49.google.com with SMTP id bi1so10531544pad.36 for ; Sun, 06 Jan 2013 22:09:41 -0800 (PST) Sender: linux-ext4-owner@vger.kernel.org List-ID: >From 020243735e97f327ecba729ec05d4e3facdddc78 Mon Sep 17 00:00:00 2001 From: Niu Yawei Date: Mon, 7 Jan 2013 01:03:26 -0500 Subject: [PATCH] Fix race in ext4_mb_add_n_trim() In ext4_mb_add_n_trim(), lg_prealloc_lock should be taken when changing the lg_prealloc_list. Signed-off-by: Niu Yawei --- fs/ext4/mballoc.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 1bf6fe7..45d3527 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4136,7 +4136,7 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac) /* The max size of hash table is PREALLOC_TB_SIZE */ order = PREALLOC_TB_SIZE - 1; /* Add the prealloc space to lg */ - rcu_read_lock(); + spin_lock(&lg->lg_prealloc_lock); list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order], pa_inode_list) { spin_lock(&tmp_pa->pa_lock); @@ -4160,7 +4160,7 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac) if (!added) list_add_tail_rcu(&pa->pa_inode_list, &lg->lg_prealloc_list[order]); - rcu_read_unlock(); + spin_unlock(&lg->lg_prealloc_lock); /* Now trim the list to be not more than 8 elements */ if (lg_prealloc_count > 8) { -- 1.7.1