Debian 8.1 ext4 directory sizes

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

i am riddling about the size of directories in Jessie's ext4,
as listed with ls -ld. They always grow and never shrink, even
if they become completely empty. My record holder had 7.5 MB,
currently i am having an empy one of 1.5 MB.

Command mount reports
  /dev/sd... on /... type ext4 (rw,relatime,data=ordered)

Processing times of programs which interpret the directory
content are very long, as if the directories would contain
tenthousands of files (which they probably once did).
My extreme specimen all have the job to buffer large numbers
of files until they get processed and deleted.


Is this a known property of ext4 directories ?

If so: Are there other means to shrink them except rmdir ?

I read about a hash tree in
  https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Directory_Entries
but this text does not say that such a tree cannot shrink.
Does anybody know how to inquire inode properties like
EXT4_INDEX_FL ?


Have a nice day :)

Thomas