Mikael Jansson (mailing lists) wrote:
"Alexander G. M. Smith" <agmsmith@xxxxxxxxxx>:Mikael Jansson wrote on Tue, 9 Aug 2005 12:32:46 +0200 (CEST):Interesting. Is it really _that_ difficult to use the IFS Kit?It's $109 for the IFS KitGone down a bit, from $1000 a few years ago, and with licensing rules that said you had to kept your software proprietary. By the way, a few people want ReiserFS to be useable under Windows too, and they estimate $90K in labour would be needed (about two man-years?).
Also, I'm not at all familiar w/ either BeOS's model or linuxes (for ReiserFS) model, but I suspect they may be very different from the WinNT model.
In Windows NT, if the filesystem driver receives an I/O marked asynchronous that it can't complete IMMEDIATELY, it MUST initiate the request to the lower level driver (for example the storage stack) and return STATUS_PENDING to the calling thread.
The storage stack driver will reenter the filesystem driver (in arbitrary thread / process context) when it has completed it's work, and the filesystem driver can pickup and complete the I/O it was working on.
I don't know, but I suspect that this highly asynchronous model isn't handled by the existing code base for linux / BeOS, and that introducing it would account for much of the estimated time.
I also suspect it would make it pretty difficult to write a BeOS-fs emulation layer.
Unless I'm utterly wrong about filesystem I/O being pretty much synchronous for linux and BeOS?
PS. $90K sounds like about one man year to me. I certainly don't work for $45K a year. And I semi-suspect that for a filesystem of ReiserFS's complexity, it may be an underestimate.