[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 <[email protected]>
Signed-off-by: Niv Sardi <[email protected]>
Signed-off-by: Lachlan McIlroy <[email protected]>

fs/xfs/linux-2.6/xfs_stats.c

@@ -98,12 +98,21 @@ xfs_read_xfsstats(
 	return len;
 }
 
-void
+int
 xfs_init_procfs(void)
 {
 	if (!proc_mkdir("fs/xfs", NULL))
-		return;
-	create_proc_read_entry("fs/xfs/stat", 0, NULL, xfs_read_xfsstats, NULL);
+		goto out;
+
+	if (!create_proc_read_entry("fs/xfs/stat", 0, NULL,
+			xfs_read_xfsstats, NULL))
+		goto out_remove_entry;
+	return 0;
+
+ out_remove_entry:
+	remove_proc_entry("fs/xfs", NULL);
+ out:
+	return -ENOMEM;
 }
 
 void

fs/xfs/linux-2.6/xfs_stats.h

@@ -134,7 +134,7 @@ DECLARE_PER_CPU(struct xfsstats, xfsstats);
 #define XFS_STATS_DEC(v)	(per_cpu(xfsstats, current_cpu()).v--)
 #define XFS_STATS_ADD(v, inc)	(per_cpu(xfsstats, current_cpu()).v += (inc))
 
-extern void xfs_init_procfs(void);
+extern int xfs_init_procfs(void);
 extern void xfs_cleanup_procfs(void);
 
 
@@ -144,8 +144,13 @@ extern void xfs_cleanup_procfs(void);
 # define XFS_STATS_DEC(count)
 # define XFS_STATS_ADD(count, inc)
 
-static inline void xfs_init_procfs(void) { };
-static inline void xfs_cleanup_procfs(void) { };
+static inline int xfs_init_procfs(void)
+{
+	return 0
+};
+static inline void xfs_cleanup_procfs(void)
+{
+};
 
 #endif	/* !CONFIG_PROC_FS */