update Documentation/filesystems/ regarding the follow_link/put_link changes

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

diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index e69274de8d0c9c1754cc40b8d99d78a724e63e50..3eae250254d581d253dd035109d568f8ef0c7873 100644 (file)
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -483,3 +483,20 @@ in your dentry operations instead.
 --
 [mandatory]
        ->aio_read/->aio_write are gone.  Use ->read_iter/->write_iter.
+---
+[recommended]
+       for embedded ("fast") symlinks just set inode->i_link to wherever the
+       symlink body is and use simple_follow_link() as ->follow_link().
+--
+[mandatory]
+       calling conventions for ->follow_link() have changed.  Instead of returning
+       cookie and using nd_set_link() to store the body to traverse, we return
+       the body to traverse and store the cookie using explicit void ** argument.
+       nameidata isn't passed at all - nd_jump_link() doesn't need it and
+       nd_[gs]et_link() is gone.
+--
+[mandatory]
+       calling conventions for ->put_link() have changed.  It gets inode instead of
+       dentry,  it does not get nameidata at all and it gets called only when cookie
+       is non-NULL.  Note that link body isn't available anymore, so if you need it,
+       store it as cookie.