On Thu, Dec 18, 2008 at 02:12:34PM +0100, Jan Kara wrote: > This is the thing I was wondering about. Why exactly is the spinlock > necessary for blkdev_releasepage()? I understand we have to protect > reading client_releasepage() pointer because it could change but my point > was that it changes only during mount / umount. Hmm.... I suppose we could use RCU, but then we'd have to worry about the race condition where client_releasepage() gets called after the umount has happened. > > I also think we are sad that we cannot implement various > > implementations for client_releasepage(). But now I cannot imagine > > what to do for a client_releasepage() which can sleep, too... My suggestion is that we not worry about making changes to fs/block_dev.c to allow client_releasepage() to sleep until we have filesystems that really need client_releasepage() to sleep. It probably is possible, with appropriate atomic bit sets for flags to indicate an unmount in progress, and client_releasepage in progress, and use of RCU, we could allow client_releasepage. But it might not be worth it unless there is a filesystem that really needs it. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
