[XFS] streamline init/exit path

Currently the xfs module init/exit code is a mess. It's farmed out over a
lot of function with very little error checking. This patch makes sure we
propagate all initialization failures properly and clean up after them.
Various runtime initializations are replaced with compile-time
initializations where possible to make this easier. The exit path is
similarly consolidated.

There's now split out function to create/destroy the kmem zones and
alloc/free the trace buffers. I've also changed the ktrace allocations to
KM_MAYFAIL and handled errors resulting from that.

And yes, we really should replace the XFS_*_TRACE ifdefs with a single
XFS_TRACE..

SGI-PV: 976035

SGI-Modid: xfs-linux-melb:xfs-kern:31354a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_sysctl.h b/fs/xfs/linux-2.6/xfs_sysctl.h
index 98b97e3..4aadb80 100644
--- a/fs/xfs/linux-2.6/xfs_sysctl.h
+++ b/fs/xfs/linux-2.6/xfs_sysctl.h
@@ -93,10 +93,10 @@
 extern xfs_param_t	xfs_params;
 
 #ifdef CONFIG_SYSCTL
-extern void xfs_sysctl_register(void);
+extern int xfs_sysctl_register(void);
 extern void xfs_sysctl_unregister(void);
 #else
-# define xfs_sysctl_register()		do { } while (0)
+# define xfs_sysctl_register()		(0)
 # define xfs_sysctl_unregister()	do { } while (0)
 #endif /* CONFIG_SYSCTL */