linux-kernel - [PATCH 07/12] docs: path-lookup: i_op->follow_link replaced with i_op->get

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Message-Id: <20210126072443.33066-8-foxhlchen@gmail.com>
Date:   Tue, 26 Jan 2021 15:24:38 +0800
From:   Fox Chen <foxhlchen@...il.com>
To:     corbet@....net, vegard.nossum@...cle.com, viro@...iv.linux.org.uk,
        rdunlap@...radead.org, grandmaster@...klimov.de
Cc:     Fox Chen <foxhlchen@...il.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 07/12] docs: path-lookup: i_op->follow_link replaced with i_op->get_link

follow_link has been replaced by get_link() which can be
called in RCU mode.

see commit: 6b2553918d8b4e6de9853fd6315bec7271a2e592

Signed-off-by: Fox Chen <foxhlchen@...il.com>
---
 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
+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