On Wed, 2011-09-28 at 12:34 -0400, Christoph Hellwig wrote: > On Mon, Sep 19, 2011 at 12:33:20PM -0500, Alex Elder wrote: > > On Wed, 2011-09-14 at 10:08 -0400, Christoph Hellwig wrote: > > > The code to flush buffers in the umount code is a bit iffy: we first flush > > > all delwri buffers out, but then might be able to queue up a new one when > > > logging the sb counts. On a normal shutdown that one would get flushed > > > out when doing the synchronous superblock write in xfs_unmountfs_writesb, > > > but we skip that one if the filesystem has been shut down. > > > > > > Fix this by moving the delwri list flushing until just before unmounting > > > the log, and while we're at it also remove the superflous delwri list > > > and buffer lru flusing for the rt and log device that can never have > > > cached or delwri buffers. > > > > What prevents blocks on a realtime device from being cached? > > Note that cached here means using buffers that end up in the rbtree > and/or on the lru. We simply never do that for the rt and log device, > as that would mean complicating the code for no reason - the only > time we ever use buffer on the rt device is for the size check during > mount and the _uncached variant where we free the buffer after the > refcount hits zero is just fine for that, and xfs_zero_remaining_bytes, > which actually operates on a regular file and thus must not use the > rbtree or the lru (and should eventually stop using buffer routines at > all). All actual metadata which the buffer cache is used for resides > on the main device. Log buffers stay alive from mount to unmount so > we're fine with that interface as well. And now that you've said that I see that there are in fact no calls to xfs_buf_get() that specify anything other than the data device. > > > > I haven't looked exhaustively, but it looks like the summary > > and bitmap data are operated on without caching, but the > > realtime data itself is treated no different from "normal" > > data blocks. > > The buffer cache is never used for actual file data. OK, I get it. Your original patch looks good. Reviewed-by: Alex Elder <aelder@xxxxxxx> _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
