file open fails on cifs mount with directio option set

[Carey Underwood]

Binary package hint: gedit

Gedit fails on open files located on cifs mounts when mounted with the directio option. That particular option is used to disable caching on the mount so that legacy databases (i.e., dbase) can be accessed and modified without causing data corruption.

Gedit is otherwise capable of creating and saving files on such a mount (although it gives 'file may have been modified' warnings), giving rise to the confusing situation where one can create a file in gedit, close gedit, and be unable to reopen that file in gedit, even though cat, vim, openoffice and so forth can all open the file without complaint.

I _think_ this may be related to the mmap behaviour mentioned here:
> gedit (2.13.0-0ubuntu1) dapper; urgency=low
> ...
> - Reading and writing of files are now handled in an
> asynchronous way (so the user interface never blocks)
> - Local files are read using mmap (when possible)
as the directio option apparently breaks mmap. Nonetheless, most other apps seem to be handling this fine.

[Sebastien Bacher (seb128)]

Thanks for the bug report. This particular bug has already been reported, but feel free to report any other bugs you find.

[Carey Underwood (cwillu)]

I don't think this is the same bug as #34813: this one only occurs with directio set on the mount, and only relates to being unable to open files. By contrast, 34813 refers to being unable to save edited files, which _were_ able to be opened perfectly fine.

[Sebastien Bacher (seb128)]

there are about cifs not working correctly, somebody with a such setup should probably investigate, we have thousand of desktop bugs and only few people working on them and I don't think we will have free slot to investigage on cifs which is something few people use at the moment