lkml.org 
[lkml]   [2021]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 07/12] docs: path-lookup: i_op->follow_link replaced with i_op->get_link
Date
follow_link has been replaced by get_link() which can be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@gmail.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 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
\
 
 \ /
  Last update: 2021-03-16 06:49    [W:0.147 / U:0.400 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site