[XFS] shrink mrlock_t

The writer field is not needed for non_DEBU builds so remove it. While
we're at i also clean up the interface for is locked asserts to go through
and xfs_iget.c helper with an interface like the xfs_ilock routines to
isolated the XFS codebase from mrlock internals. That way we can kill
mrlock_t entirely once rw_semaphores grow an islocked facility. Also
remove unused flags to the ilock family of functions.

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30902a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 24 insertions, 36 deletions

diff --git a/fs/xfs/linux-2.6/mrlock.h b/fs/xfs/linux-2.6/mrlock.h
index c110bb002665..ff6a19873e5c 100644
--- a/fs/xfs/linux-2.6/mrlock.h
+++ b/fs/xfs/linux-2.6/mrlock.h
@@ -20,29 +20,24 @@
 
 #include <linux/rwsem.h>
 
-enum { MR_NONE, MR_ACCESS, MR_UPDATE };
-
 typedef struct {
         struct rw_semaphore     mr_lock;
+#ifdef DEBUG
         int                     mr_writer;
+#endif
 } mrlock_t;
 
+#ifdef DEBUG
 #define mrinit(mrp, name)       \
         do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
+#else
+#define mrinit(mrp, name)       \
+        do { init_rwsem(&(mrp)->mr_lock); } while (0)
+#endif
+
 #define mrlock_init(mrp, t,n,s) mrinit(mrp, n)
 #define mrfree(mrp)             do { } while (0)
 
-static inline void mraccess(mrlock_t *mrp)
-{
-        down_read(&mrp->mr_lock);
-}
-
-static inline void mrupdate(mrlock_t *mrp)
-{
-        down_write(&mrp->mr_lock);
-        mrp->mr_writer = 1;
-}
-
 static inline void mraccess_nested(mrlock_t *mrp, int subclass)
 {
         down_read_nested(&mrp->mr_lock, subclass);
@@ -51,10 +46,11 @@ static inline void mraccess_nested(mrlock_t *mrp, int subclass)
 static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
 {
         down_write_nested(&mrp->mr_lock, subclass);
+#ifdef DEBUG
         mrp->mr_writer = 1;
+#endif
 }
 
-
 static inline int mrtryaccess(mrlock_t *mrp)
 {
         return down_read_trylock(&mrp->mr_lock);
@@ -64,39 +60,31 @@ static inline int mrtryupdate(mrlock_t *mrp)
 {
         if (!down_write_trylock(&mrp->mr_lock))
                 return 0;
+#ifdef DEBUG
         mrp->mr_writer = 1;
+#endif
         return 1;
 }
 
-static inline void mrunlock(mrlock_t *mrp)
+static inline void mrunlock_excl(mrlock_t *mrp)
 {
-        if (mrp->mr_writer) {
-                mrp->mr_writer = 0;
-                up_write(&mrp->mr_lock);
-        } else {
-                up_read(&mrp->mr_lock);
-        }
+#ifdef DEBUG
+        mrp->mr_writer = 0;
+#endif
+        up_write(&mrp->mr_lock);
 }
 
-static inline void mrdemote(mrlock_t *mrp)
+static inline void mrunlock_shared(mrlock_t *mrp)
 {
-        mrp->mr_writer = 0;
-        downgrade_write(&mrp->mr_lock);
+        up_read(&mrp->mr_lock);
 }
 
-#ifdef DEBUG
-/*
- * Debug-only routine, without some platform-specific asm code, we can
- * now only answer requests regarding whether we hold the lock for write
- * (reader state is outside our visibility, we only track writer state).
- * Note: means !ismrlocked would give false positives, so don't do that.
- */
-static inline int ismrlocked(mrlock_t *mrp, int type)
+static inline void mrdemote(mrlock_t *mrp)
 {
-        if (mrp && type == MR_UPDATE)
-                return mrp->mr_writer;
-        return 1;
-}
+#ifdef DEBUG
+        mrp->mr_writer = 0;
 #endif
+        downgrade_write(&mrp->mr_lock);
+}
 
 #endif /* __XFS_SUPPORT_MRLOCK_H__ */