Improve the success rate when use mkdir() in multiprocessing environm…

…ent (php#7383)

Improve the success rate when use mkdir() in multiprocessing environment

main/streams/plain_wrapper.c

@@ -1414,7 +1414,7 @@ static int php_plain_files_mkdir(php_stream_wrapper *wrapper, const char *dir, i
 	}
 	while (true) {
 		int ret = VCWD_MKDIR(buf, (mode_t) mode);
-		if (ret < 0) {
+		if (ret < 0 && errno != EEXIST) {
 			if (options & REPORT_ERRORS) {
 				php_error_docref(NULL, E_WARNING, "%s", strerror(errno));
 			}
@@ -1433,6 +1433,13 @@ static int php_plain_files_mkdir(php_stream_wrapper *wrapper, const char *dir, i
 		}
 		if (p == e || !replaced_slash) {
 			/* No more directories to create */
+			/* issue a warning to client when the last directory was created failed */
+			if (ret < 0) {
+				if (options & REPORT_ERRORS) {
+					php_error_docref(NULL, E_WARNING, "%s", strerror(errno));
+				}
+				return 0;
+			}
 			return 1;
 		}
 	}