9pfs: drop useless v9fs_string_null() function

The v9fs_string_null() function just calls v9fs_string_free(). Also it
only has 4 users, whereas v9fs_string_free() has 87.

This patch converts users to call directly v9fs_string_free() and drops
the useless function.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>

fsdev/9p-marshal.c

@@ -25,11 +25,6 @@ void v9fs_string_free(V9fsString *str)
     str->size = 0;
 }
 
-void v9fs_string_null(V9fsString *str)
-{
-    v9fs_string_free(str);
-}
-
 void GCC_FMT_ATTR(2, 3)
 v9fs_string_sprintf(V9fsString *str, const char *fmt, ...)
 {

fsdev/9p-marshal.h

@@ -77,7 +77,6 @@ static inline void v9fs_string_init(V9fsString *str)
     str->size = 0;
 }
 extern void v9fs_string_free(V9fsString *str);
-extern void v9fs_string_null(V9fsString *str);
 extern void v9fs_string_sprintf(V9fsString *str, const char *fmt, ...);
 extern void v9fs_string_copy(V9fsString *lhs, V9fsString *rhs);
 

hw/9pfs/9p.c

@@ -810,15 +810,15 @@ static int stat_to_v9stat(V9fsPDU *pdu, V9fsPath *name,
     v9stat->mtime = stbuf->st_mtime;
     v9stat->length = stbuf->st_size;
 
-    v9fs_string_null(&v9stat->uid);
-    v9fs_string_null(&v9stat->gid);
-    v9fs_string_null(&v9stat->muid);
+    v9fs_string_free(&v9stat->uid);
+    v9fs_string_free(&v9stat->gid);
+    v9fs_string_free(&v9stat->muid);
 
     v9stat->n_uid = stbuf->st_uid;
     v9stat->n_gid = stbuf->st_gid;
     v9stat->n_muid = 0;
 
-    v9fs_string_null(&v9stat->extension);
+    v9fs_string_free(&v9stat->extension);
 
     if (v9stat->mode & P9_STAT_MODE_SYMLINK) {
         err = v9fs_co_readlink(pdu, name, &v9stat->extension);