On Tue, Jan 26 2021, Fox Chen wrote: > follow_link has been replaced by get_link() which can be > called in RCU mode. > > see commit: 6b2553918d8b4e6de9853fd6315bec7271a2e592 > > Signed-off-by: Fox Chen <foxhlchen@xxxxxxxxx> > --- > 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 25d2a5a59f45..0a362849b26f 100644 > --- a/Documentation/filesystems/path-lookup.rst > +++ b/Documentation/filesystems/path-lookup.rst > @@ -1062,13 +1062,11 @@ 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 > +RCU-walk. Much like the ``i_op->permission()`` method we The phrase "drop RCU-walk" isn't consistent with the rest of the text. It talks about "dropping down to REF-walk", so you could write "dropping out of RCU-walk", but not just "dropping RCU-walk". NeilBrown > +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 > -- > 2.30.0
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