On Tue, Mar 16 2021, Fox Chen wrote: > follow_link has been replaced by get_link() which can be > called in RCU mode. > > see commit: commit 6b2553918d8b ("replace ->follow_link() with > new method that could stay in RCU mode") > > Signed-off-by: Fox Chen Reviewed-By: NeilBrown Thanks, NeilBrown > --- > Documentation/filesystems/path-lookup.rst | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/Documentation/filesystems/path-lookup.rst b/Documentation/filesystems/path-lookup.rst > index af5c20fecfef..e6b6c43ff0f6 100644 > --- a/Documentation/filesystems/path-lookup.rst > +++ b/Documentation/filesystems/path-lookup.rst > @@ -1060,13 +1060,11 @@ filesystem cannot successfully get a reference in RCU-walk mode, it > must return ``-ECHILD`` and ``unlazy_walk()`` will be called to return to > REF-walk mode in which the filesystem is allowed to sleep. > > -The place for all this to happen is the ``i_op->follow_link()`` inode > -method. In the present mainline code this is never actually called in > -RCU-walk mode as the rewrite is not quite complete. It is likely that > -in a future release this method will be passed an ``inode`` pointer when > -called in RCU-walk mode so it both (1) knows to be careful, and (2) has the > -validated pointer. Much like the ``i_op->permission()`` method we > -looked at previously, ``->follow_link()`` would need to be careful that > +The place for all this to happen is the ``i_op->get_link()`` inode > +method. This is called both in RCU-walk and REF-walk. In RCU-walk the > +``dentry*`` argument is NULL, ``->get_link()`` can return -ECHILD to drop out of > +RCU-walk. Much like the ``i_op->permission()`` method we > +looked at previously, ``->get_link()`` would need to be careful that > all the data structures it references are safe to be accessed while > holding no counted reference, only the RCU lock. Though getting a > reference with ``->follow_link()`` is not yet done in RCU-walk mode, the > -- > 2.30.2