Messages in this thread | | | Date | 21 Sep 2009 23:28:02 -0400 | From | "George Spelvin" <> | Subject | Re: [GIT PULL] ocfs2 changes for 2.6.32 |
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> or make it one level simpler? > Have a "wait for all started copies" call only.... saves a ton of book > keeping, and is likely what people will use it for in the end anyway.
Aieeee! No, no, a thousand times, no!
We do NOT need another blocking primitive that can't play well with others. That would be a HORRIBLE design mistake.
The whole benefit of Linus' scheme is that it returns a file descriptor. Any waiting should be done by the standard event-wait system call, poll(). It should return POLLIN when there's an interesting event (such as copy completion), and should remain valid until explicitly close()d.
There's nothing wrong with a convenience function that waits for all started copies, but I don't see a reason to design a new kernel interface for the purpose.
A few more points: - If the file descriptor returned by copyfile() is guaranteed not to be 0 (even if that is available), perhaps it should be guaranteed to be >= 3. - We might as well make the returned file descriptor O_CLOEXEC by default. You can always change it back if you want to.
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