Please see this thread:
http://lists.samba.org/archive/linux-cifs-client/2006-September/001481.html
Summary:
because of the changes in the way the 2.6.18 kernel sets blocksize, cifs mounts
are failing when peforming certain operations.
This is the case on FC6 and on FC5 with the latest kernel update to 2.6.18.
I tried searching bugzilla to see if this bug is already open, but
currently all searches result in a big red:
"You can't see or sort by the 'relevance' field if you aren't also
doing a full text search."
So, I may have created a dupe, sorry:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=211832
--
Konstantin Ryabitsev
Montréal, Québec