On Fri, May 28, 2010 at 02:40:53PM -0500, Alex Elder wrote:
> On Thu, 2010-05-27 at 15:05 -0400, Christoph Hellwig wrote:
> > Use rwsem_is_locked to make the assertations for shared locks work.
> So you're changing it so it answers "yes it's locked"
> even it it's only a read lock now, right?
If XFS_ILOCK_SHARED/XFS_IOLOCK_SHARED are in the flags we'll answer yes
it's locked for a read lock now, indeed.
> Previously it was basically (once each for ilock and
> iolock): "If the exclusive flag is set, but there is no
> writer, then it is not locked; otherwise it is."
> Now it's "If the exclusive flag is set, but no writer,
> it's not locked. Otherwise if the shared flag is
> set it's locked if rwsem_is_locked() says we are.
> Otherwise (ASSERT(0) and) it is not locked."
Not exactly. Now it's:
- if excl is set but shared isn't return true if mr_writer is
set, else false
- if shared is set either alone or together with excl return
if it is locked in any way (rwsem_is_locked).
Note that xfs_isilocked can be called like:
which means that either excl or shared is fine.
- if either one or both of excl and shared are set and it's
> That last part is wrong I think. It should be OK to
> call xfs_isilocked() with neither flag set, in which
> case the result should be 0.
We can argue about removing the assert, but we currently don't
and should't call xfs_isilocked wit ha 0 argument - it's rather
pointless to do so.
> And if the exclusive
> flag is set, and there *is* a writer, it *is* locked,
> so it should return 1.
We do that right now.