extra readdir operation when writing to a non-existent file

[Alain Knaff]

On 12/05/10 10:16, Zhang Bingjun (Eddy) wrote:
> hi samba fellows,
> 
> It is my first time to ask questions in samba mail list. Very sorry if
> my question is very naive.
> 
> The problem is when I write to
> a non-existent file from windows to a linux export, there will be an
> extra readdir operation triggered. If I write to an existent file, no
> readdir operation will be triggered.

I'm still pretty knew on this list too, but let me take a guess about
what may be going on:

Windows (by default) is case-insensitive, Unix is case-sensitive. So, if
you write to a non existant file (let's call it "test.txt"), the kernel
will tell samba that the file "test.txt" doesn't exist. However, there
could be a file called "Test.txt" or "TEST.TXT", ... The open call won't
tell that, the only way for samba to find out is to do a readdir and
manually go through the list to see whether anything matches in a
case-insensitive way.

> 
> How could I avoid the extra readdir operation in all cases when I am just
> writing to a file?

Switching samba to a case-sensitive mode might help, try putting the
following into your smb.conf:

case sensitive = yes


if that alone doesn't help, you might try setting all 4 of the following:

default case = lower
sensitive = yes
preserve case = no
short preserve case = No

Indeed, the smb.conf says the following:

default case = upper/lower
    controls what the default case is for new filenames (ie. files that
    donŽt currently exist in the filesystem). Default lower. IMPORTANT
    NOTE: This option will be used to modify the case of all incoming
    client filenames, not just new filenames if the options case
    sensitive = yes, preserve case = No, short preserve case = No are
    set. This change is needed as part of the optimisations for
    directories containing large numbers of files.

> 
> Very much appreciate your help!

Regards,

Alain