xfs: simplify kmem_{zone_}zalloc

Introduce flag KM_ZERO which is used to alloc zeroed entry, and convert
kmem_{zone_}zalloc to call kmem_{zone_}alloc() with KM_ZERO directly,
in order to avoid the setting to zero step. 
And following Dave's suggestion, make kmem_{zone_}zalloc static inline
into kmem.h as they're now just a simple wrapper.

V2:
  Make kmem_{zone_}zalloc static inline into kmem.h as Dave suggested.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/kmem.c

@@ -62,17 +62,6 @@ kmem_alloc(size_t size, xfs_km_flags_t flags)
 	} while (1);
 }
 
-void *
-kmem_zalloc(size_t size, xfs_km_flags_t flags)
-{
-	void	*ptr;
-
-	ptr = kmem_alloc(size, flags);
-	if (ptr)
-		memset((char *)ptr, 0, (int)size);
-	return ptr;
-}
-
 void *
 kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
 {
@@ -128,14 +117,3 @@ kmem_zone_alloc(kmem_zone_t *zone, xfs_km_flags_t flags)
 		congestion_wait(BLK_RW_ASYNC, HZ/50);
 	} while (1);
 }
-
-void *
-kmem_zone_zalloc(kmem_zone_t *zone, xfs_km_flags_t flags)
-{
-	void	*ptr;
-
-	ptr = kmem_zone_alloc(zone, flags);
-	if (ptr)
-		memset((char *)ptr, 0, kmem_cache_size(zone));
-	return ptr;
-}

fs/xfs/kmem.h

@@ -32,6 +32,7 @@ typedef unsigned __bitwise xfs_km_flags_t;
 #define KM_NOSLEEP	((__force xfs_km_flags_t)0x0002u)
 #define KM_NOFS		((__force xfs_km_flags_t)0x0004u)
 #define KM_MAYFAIL	((__force xfs_km_flags_t)0x0008u)
+#define KM_ZERO		((__force xfs_km_flags_t)0x0010u)
 
 /*
  * We use a special process flag to avoid recursive callbacks into
@@ -43,7 +44,7 @@ kmem_flags_convert(xfs_km_flags_t flags)
 {
 	gfp_t	lflags;
 
-	BUG_ON(flags & ~(KM_SLEEP|KM_NOSLEEP|KM_NOFS|KM_MAYFAIL));
+	BUG_ON(flags & ~(KM_SLEEP|KM_NOSLEEP|KM_NOFS|KM_MAYFAIL|KM_ZERO));
 
 	if (flags & KM_NOSLEEP) {
 		lflags = GFP_ATOMIC | __GFP_NOWARN;
@@ -52,18 +53,27 @@ kmem_flags_convert(xfs_km_flags_t flags)
 		if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
 			lflags &= ~__GFP_FS;
 	}
+
+	if (flags & KM_ZERO)
+		lflags |= __GFP_ZERO;
+
 	return lflags;
 }
 
 extern void *kmem_alloc(size_t, xfs_km_flags_t);
-extern void *kmem_zalloc(size_t, xfs_km_flags_t);
 extern void *kmem_zalloc_large(size_t size, xfs_km_flags_t);
 extern void *kmem_realloc(const void *, size_t, size_t, xfs_km_flags_t);
 extern void  kmem_free(const void *);
 
 
 extern void *kmem_zalloc_greedy(size_t *, size_t, size_t);
 
+static inline void *
+kmem_zalloc(size_t size, xfs_km_flags_t flags)
+{
+	return kmem_alloc(size, flags | KM_ZERO);
+}
+
 /*
  * Zone interfaces
  */
@@ -102,6 +112,11 @@ kmem_zone_destroy(kmem_zone_t *zone)
 }
 
 extern void *kmem_zone_alloc(kmem_zone_t *, xfs_km_flags_t);
-extern void *kmem_zone_zalloc(kmem_zone_t *, xfs_km_flags_t);
+
+static inline void *
+kmem_zone_zalloc(kmem_zone_t *zone, xfs_km_flags_t flags)
+{
+	return kmem_zone_alloc(zone, flags | KM_ZERO);
+}
 
 #endif /* __XFS_SUPPORT_KMEM_H__ */