On Tue, May 20, 2014 at 07:17:06AM -0400, Brian Foster wrote:
> On Tue, May 20, 2014 at 07:56:58AM +1000, Dave Chinner wrote:
> > On Fri, May 16, 2014 at 02:12:46PM -0400, Brian Foster wrote:
> > > Create sysfs attributes to export the current runtime state of the log
> > > to userspace. Note that the filesystem should be frozen for best
> > > accuracy/consistency when reading these values, but is not required.
> > > This is for testing and debug purposes only.
> > >
> > > Create the following per-mount attributes: log_head_lsn, log_tail_lsn,
> > > reserve_head_lsn and write_head_lsn. These represent the physical log
> >
> > Reserve and write heads are not log sequence numbers (LSNs). A LSN
> > is a cycle:block count tuple, while a grant head is a cycle:byte
> > count tuple....
> >
>
> Yeah, I suppose that's some terminology abuse... ;)
>
> > Calling the reserve_grant_head/write_grant_head would make more
> > sense, I think, as would splitting them into cycle/byte output
> > pairs. Splitting them make sense because if we increase the log size
> > beyond 2GB we're going to need a different in-memory representation
> > for the grant heads (i.e. need more than 32 bits for byte count), so
> > we should probably handle that up front in the sysfs API...
> >
>
> Ok. reserve_grant_head and write_grant_head in the decimal format of
> "cycle:bytes" it is. I'll leave the names of the others and convert them
> to a similar "cycle:blocks" format. Thanks!
FWIW, I think all the sysfs code should be in it's own file, not in
xfs_mount.c...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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