block: always compile-check debug prints

Files with conditional debug statements should ensure that the printf is
always compiled. This prevents bitrot of the format string of the debug
statement. And switch debug output to stderr.
Signed-off-by: NZhou Jie <zhoujie2011@cn.fujitsu.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/curl.c

@@ -36,10 +36,16 @@
 // #define DEBUG_VERBOSE
 
 #ifdef DEBUG_CURL
-#define DPRINTF(fmt, ...) do { printf(fmt, ## __VA_ARGS__); } while (0)
+#define DEBUG_CURL_PRINT 1
 #else
-#define DPRINTF(fmt, ...) do { } while (0)
+#define DEBUG_CURL_PRINT 0
 #endif
+#define DPRINTF(fmt, ...)                                            \
+    do {                                                             \
+        if (DEBUG_CURL_PRINT) {                                      \
+            fprintf(stderr, fmt, ## __VA_ARGS__);                    \
+        }                                                            \
+    } while (0)
 
 #if LIBCURL_VERSION_NUM >= 0x071000
 /* The multi interface timer callback was introduced in 7.16.0 */

block/sheepdog.c

@@ -294,13 +294,16 @@ static inline size_t count_data_objs(const struct SheepdogInode *inode)
 
 #undef DPRINTF
 #ifdef DEBUG_SDOG
-#define DPRINTF(fmt, args...)                                       \
-    do {                                                            \
-        fprintf(stdout, "%s %d: " fmt, __func__, __LINE__, ##args); \
-    } while (0)
+#define DEBUG_SDOG_PRINT 1
 #else
-#define DPRINTF(fmt, args...)
+#define DEBUG_SDOG_PRINT 0
 #endif
+#define DPRINTF(fmt, args...)                                           \
+    do {                                                                \
+        if (DEBUG_SDOG_PRINT) {                                         \
+            fprintf(stderr, "%s %d: " fmt, __func__, __LINE__, ##args); \
+        }                                                               \
+    } while (0)
 
 typedef struct SheepdogAIOCB SheepdogAIOCB;