Messages in this thread | | | Date | Fri, 5 Sep 2003 15:56:37 -0400 (EDT) | From | Alan Stern <> | Subject | Re: How can I force a read to hit the disk? |
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On Fri, 5 Sep 2003, Jörn Engel wrote:
> On Fri, 5 September 2003 14:49:15 -0400, Alan Stern wrote: > > On Fri, 5 Sep 2003, Andreas Dilger wrote: > > > > > If you open the file with O_DIRECT, it should read/write directly on the > > > disk, and it will also invalidate any existing cache for the read/written > > > area. > > > > Unfortunately that's not a good solution for me. The file has already > > been opened without O_DIRECT, and O_DIRECT wouldn't be appropriate because > > most of the time I do want I/O to go through the cache. It's just on a > > few rare occasions that I need direct access to the disk. > > > > Maybe simply opening a new struct file using O_DIRECT, for purposes of > > the verification, while keeping the old struct file around for other uses > > later, will work? That would be awkward though -- and there's no > > guarantee that the original filename would still exist. It would be a lot > > nicer to do everything using the original file reference. > > Maybe these help you here: > man 3 fdopen > man 3 fileno > > No filename needed for the second open.
I don't think they will help. Apart from the fact that I'm working on a kernel module, not a user program, neither of these accepts options like O_DIRECT.
Alan Stern
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