[users@httpd] Question on FileETag and mod_dav_fs

[Tianyin Xu <ti...@cs.ucsd.edu>]

Hi, all,

I saw the warning message in the manual, the FileETag entry:

-------------------------------------------------------------
Warning Do not change the default for directories or locations that have
WebDAV enabled and use
mod_dav_fs<http://httpd.apache.org/docs/2.4/mod/mod_dav_fs.html>as a
storage provider.
mod_dav_fs <http://httpd.apache.org/docs/2.4/mod/mod_dav_fs.html> uses
MTime Size as a fixed format for ETag comparisons on conditional requests.
These conditional requests will break if the ETag format is changed via
FileETag.

-------------------------------------------------------------

I do not get it. What will happen when I use WebDAV with mod_dav_fs while
setting FileETag as None?

According to the source code point of view, it seems that there's some
relation between dav_fs_getetag() in repos.c and ap_make_etag() in
http_etag.c.

Could some one explain a little bit to me?

Thank you so much!!!
Tianyin