From: Eric Sandeen Subject: Re: [PATCH] ext4: Protect group inode free counting with group lock. Date: Wed, 16 May 2012 08:43:28 -0500 Message-ID: <4FB3AF00.9060704@redhat.com> References: <1337158192-4591-1-git-send-email-tm@tao.ma> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, "Theodore Ts'o" To: Tao Ma Return-path: Received: from mx1.redhat.com ([209.132.183.28]:14324 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932296Ab2EPNnd (ORCPT ); Wed, 16 May 2012 09:43:33 -0400 In-Reply-To: <1337158192-4591-1-git-send-email-tm@tao.ma> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 5/16/12 3:49 AM, Tao Ma wrote: > From: Tao Ma > > Now when we set the group inode free count, we don't have a proper > group lock so that multiple threads may decrease the inode free > count at the same time. And e2fsck will complain something like: This is only in the ! EXT4_FEATURE_RO_COMPAT_GDT_CSUM case I guess? That would be worth mentioning in the summary & changelog. I guess you were testing without that for some reason? -eric > Free inodes count wrong for group #1 (1, counted=0). > Fix? no > > Free inodes count wrong for group #2 (3, counted=0). > Fix? no > > Directories count wrong for group #2 (780, counted=779). > Fix? no > > Free inodes count wrong for group #3 (2272, counted=2273). > Fix? no > > So this patch try to protect it with the ext4_lock_group. > > btw, it is found by xfstests test case 269 and I have run it 100 > times and the error in e2fsck doesn't show up again. > > Cc: Theodore Ts'o > Signed-off-by: Tao Ma > --- > fs/ext4/ialloc.c | 9 +++++---- > 1 files changed, 5 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c > index 409c2ee..25595e2 100644 > --- a/fs/ext4/ialloc.c > +++ b/fs/ext4/ialloc.c > @@ -772,7 +772,9 @@ got: > ext4_itable_unused_set(sb, gdp, > (EXT4_INODES_PER_GROUP(sb) - ino)); > up_read(&grp->alloc_sem); > - } > + } else > + ext4_lock_group(sb, group); > + > ext4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1); > if (S_ISDIR(mode)) { > ext4_used_dirs_set(sb, gdp, ext4_used_dirs_count(sb, gdp) + 1); > @@ -782,10 +784,9 @@ got: > atomic_inc(&sbi->s_flex_groups[f].used_dirs); > } > } > - if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) { > + if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) > gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp); > - ext4_unlock_group(sb, group); > - } > + ext4_unlock_group(sb, group); > > BUFFER_TRACE(inode_bitmap_bh, "call ext4_handle_dirty_metadata"); > err = ext4_handle_dirty_metadata(handle, NULL, inode_bitmap_bh);