On 05/16/2012 09:43 PM, Eric Sandeen wrote:
> On 5/16/12 3:49 AM, Tao Ma wrote:
>> From: Tao Ma <boyu.mt@xxxxxxxxxx>
>>
>> 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 <tytso@xxxxxxx>
>> Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx>
>> ---
>> 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);
>
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