From: Tao Ma Subject: Re: [PATCH] ext4: Protect group inode free counting with group lock. Date: Wed, 16 May 2012 22:55:05 +0800 Message-ID: <4FB3BFC9.20901@tao.ma> References: <1337158192-4591-1-git-send-email-tm@tao.ma> <4FB3AF00.9060704@redhat.com> 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: Eric Sandeen Return-path: Received: from oproxy5-pub.bluehost.com ([67.222.38.55]:57520 "HELO oproxy5-pub.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753530Ab2EPOzP (ORCPT ); Wed, 16 May 2012 10:55:15 -0400 In-Reply-To: <4FB3AF00.9060704@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 05/16/2012 09:43 PM, Eric Sandeen wrote: > 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. sure, I will add it in v2. > > I guess you were testing without that for some reason? See my comments below. I found it when running xfstests 269. Thanks Tao > > -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); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html