[LU-6824] improve error messages for dir htree limit

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.8.0
• Labels: patch
• Assignee: Yang Sheng
• Reporter: Wang Shilong (Inactive)

Description

Currently without large dir feature, ldiskfs directory hash tree will be limited 2 height, this means directory size is limited about 1GB, and in fact users are likely to hit ENOSPC when reaching half of limit because of bad hash.

    
LDISKFS-fs warning (device dm-4): ldiskfs_dx_add_entry: Directory (ino: 614516572) index full, reach max htree level :2
LDISKFS-fs warning (device dm-4): ldiskfs_dx_add_entry: Large directory feature is not enabled on this filesystem

Testing by following scripts:

    
    i=0
    filename="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
    "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbb"
    while [ 1 ]
    do
            touch $filename"$i"
            if [ $? -ne 0 ];then
                    break
            fi
            ((i++))
    done

When directory size grow about 590M, we hit ENOSPC. this patch try to improve error messages to warn users when it is easier to hit ENOSPC (50% of limit).

Issue Links

• is related to: LU-11546 enable large_dir support for MDTs