linux-kernel - [PATCH v3 07/13] docs: path-lookup: i_op->follow_link replaced with i_op->get

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Message-Id: <20210527091618.287093-8-foxhlchen@gmail.com>
Date:   Thu, 27 May 2021 17:16:12 +0800
From:   Fox Chen <foxhlchen@...il.com>
To:     neilb@...e.de
Cc:     Fox Chen <foxhlchen@...il.com>, corbet@....net,
        vegard.nossum@...cle.com, viro@...iv.linux.org.uk,
        rdunlap@...radead.org, grandmaster@...klimov.de,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org
Subject: [PATCH v3 07/13] 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follow_link has been replaced by get_link() which can be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: commit 6b2553918d8b ("replace ->follow_link() with
new method that could stay in RCU mode")

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 40b9afec4d60..4650c6427963 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
-- 
2.31.1