On 4/7/07, Christoph Hellwig <[EMAIL PROTECTED]> wrote:
It's not going to solve anything at all. We can't stop supporting functionality that has been there forever.
Not necessarily. One problem here is that the interface for using readdir() with and without telldir()/seekdir() is the same. A second problem is that the functionality is universally required. Both of these problems can be addressed. For the second problem, I certainly could imagine that making the functionality to to use seekdir()/telldir() optional. It might be hard in POSIX but this does not mean anything about implementations. Implementations just have to provide a way to allow these functions to be used. It does not mean it always and everywhere has to work. What this means is that if, for instance, a filesystem would be (for now) be able to have a mount option to not allow seekdir()/telldir() the system still can conform to POSIX. At the same time we can gather information as to whether seekdir()/telldir() are really needed. I personally think the number of apps which depend on this functionality is miniscule. Using a mount option isn't the nicest solution, though. If a filesystem can support seekdir()/telldir() the better solution from the userlevel API POV would be to provide a better, alternative interface. Maybe an alternative opendir() call (opendir2?) which takes a second parameter as to whether seeking is needed or not. Then this opendir2() function can use a new getdents() syscall and return the entries. The difference would be that if the user wants to use seekdir()/telldir() the userlevel code would cache the old results and the seekdir()/telldir() handling would be entirely at userlevel. It's not a good idea to make this the default behavior for the old opendir() since the vast majority of the current users don't want to seek and therefore the caching would significantly impact the performance. With the extra argument saying when caching is needed this is no problem anymore. Over time people would migrate off of opendir() and towards opendir2() (with some "careful" encouragement) and the whole problem will go away. And the best: this is certainly a path I can see being viable for POSIX. But it requires that we have a) established existing practice b) shown the impact is really low So, I think it would be great to get started writing this new getdents call. Yes, for now it means maintaining two separate versions. If all goes well those filsystems which feel a high burden can simply stop supporting the old syscall or at least the seek functionality. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/