Shrink/reset directory size?

Is there a way to shrink a directory entry?

My dovecot maildir directories have increased in size from the default 4096 to several megs, and it is messing with disk quotas.

The only way that I have found, is to delete and recreate the directory. I am hoping there is a magical function somewhere - I am open to anything, except for hand-coded assembler.

Edit: For posterity, to find dirents>4096:

 find / -type d -size +4k -printf "%s\t%p\t%i\n" | sort -nr

See also rm on a directory with millions of files; tangentially related, but we discuss it there.

As far as I'm aware, at least on ext2/3, no, there's no (online) way to shrink them short of delete + recreate. Unmounted, several sources suggest e2fsck -D might work, though I can claim no personal experience with that option.

Some references for further reading:

• http://linux.derkeiler.com/Mailing-Lists/Kernel/2009-05/threads.html#06569
• http://fedoraforum.org/forum/showthread.php?t=120654

I'd do it like this.

cp -aloldirnewdir&& mvolddirtempname&& mvnewdirolddir&& rm -rtempname

where olddir is the directory you want to shrink newdir and tempname are temporary filenames

cp -al creates links to the content of olddir in newdir and the next three commands swap them with newdir and clean up.