Excerpts from Andrew Morton's message of 2010-11-24 17:47:40 -0500: > On Tue, 23 Nov 2010 07:34:07 -0500 > Chris Mason <chris.mason@xxxxxxxxxx> wrote: > > > For btrfs there's only one bdi per SB, but for most everyone else a disk > > with a bunch of partitions is going to have multiple filesystems on the > > same bdi. > > um, please explain why that wasn't idiotic? The BDI is a > representation of a backing device and it's *supposed* to provide > visibility into what's happening against other partitions on the same > device. Creating a BDI per SB (it didn't even occur to me to think > that a filesystem was even able to do this) breaks that. > We don't really have visibility into the other partitions, we all just pretend they aren't there (this patch being the most recent example). Yes, it does help prevent N flushers seeking around on the drive but it does cause problems too. How is the btrfs one-bdi-per-super different from device mapper's one bdi per logical volume? We're all idiots together I suppose. As for having multiple bdis per FS, that was always a long term goal of mine when Jens was setting up the new flushers. I didn't want to confuse the initial implementation with it though. -chris -- 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
