make new_sync_{read,write}() static

[firefly-linux-kernel-4.4.55.git] / Documentation / filesystems / porting

diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index fa2db081505e6d6d581ea4ee6d8f1eaab56a3482..4006483c275fd3b33c6ed9322ea7c22b728de3f6 100644 (file)
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -471,3 +471,12 @@ in your dentry operations instead.
 [mandatory]
        f_dentry is gone; use f_path.dentry, or, better yet, see if you can avoid
        it entirely.
+--
+[mandatory]
+       never call ->read() and ->write() directly; use __vfs_{read,write} or
+       wrappers; instead of checking for ->write or ->read being NULL, look for
+       FMODE_CAN_{WRITE,READ} in file->f_mode.
+--
+[mandatory]
+       do _not_ use new_sync_{read,write} for ->read/->write; leave it NULL
+       instead.