zio_buf2.patch

diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index 97f2549..05a8749 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -263,7 +263,17 @@ zio_buf_alloc(size_t size)
 	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
 
 	ASSERT(c < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
-
+#ifdef _KERNEL
+	if (size <= 512) {
+		static int index = 0;
+		unsigned long addr = (unsigned long)vmalloc(4096);
+		ASSERT(addr);
+		ASSERT((addr & (PAGE_SIZE-1)) == 0);
+		index = (index+3)%8;
+		memset((void *)addr, 0x5a, PAGE_SIZE);
+		return (void *)(addr + 512*index);
+	}
+#endif
 	return (kmem_cache_alloc(zio_buf_cache[c], KM_PUSHPAGE | KM_NODEBUG));
 }
 
@@ -279,7 +289,17 @@ zio_data_buf_alloc(size_t size)
 	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
 
 	ASSERT(c < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
-
+#ifdef _KERNEL
+	if (size <= 512) {
+		static int index = 0;
+		unsigned long addr = (unsigned long)vmalloc(4096);
+		ASSERT(addr);
+		ASSERT((addr & (PAGE_SIZE-1)) == 0);
+		index = (index+3)%8;
+		memset((void *)addr, 0x5a, PAGE_SIZE);
+		return (void *)(addr + 512*index);
+	}
+#endif
 	return (kmem_cache_alloc(zio_data_buf_cache[c],
 	    KM_PUSHPAGE | KM_NODEBUG));
 }
@@ -290,7 +310,19 @@ zio_buf_free(void *buf, size_t size)
 	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
 
 	ASSERT(c < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
-
+#ifdef _KERNEL
+	if (size <= 512) {
+		unsigned long p;
+		unsigned long baddr = (unsigned long)buf;
+		unsigned long vaddr = baddr & (~(PAGE_SIZE-1));
+		for (p = vaddr; p < baddr; p++)
+			ASSERT(*(char *)p == 0x5a);
+		for (p = baddr+512; p < vaddr+PAGE_SIZE; p++)
+			ASSERT(*(char *)p == 0x5a);
+		vfree((void *)p);
+		return;
+	}
+#endif
 	kmem_cache_free(zio_buf_cache[c], buf);
 }
 
@@ -300,7 +332,19 @@ zio_data_buf_free(void *buf, size_t size)
 	size_t c = (size - 1) >> SPA_MINBLOCKSHIFT;
 
 	ASSERT(c < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
-
+#ifdef _KERNEL
+	if (size <= 512) {
+		unsigned long p;
+		unsigned long baddr = (unsigned long)buf;
+		unsigned long vaddr = baddr & (~(PAGE_SIZE-1));
+		for (p = vaddr; p < baddr; p++)
+			ASSERT(*(char *)p == 0x5a);
+		for (p = baddr+512; p < vaddr+PAGE_SIZE; p++)
+			ASSERT(*(char *)p == 0x5a);
+		vfree((void *)p);
+		return;
+	}
+#endif
 	kmem_cache_free(zio_data_buf_cache[c], buf);
 }