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authorFox Chen <foxhlchen@gmail.com>2021-05-27 17:16:12 +0800
committerJonathan Corbet <corbet@lwn.net>2021-06-18 11:36:08 -0600
commit4a00e4bd59bbd5eac26f1792eb8d7d60f6cafe9a (patch)
tree9c2ae459c14e0206d1e4baf178fc67b2ddadccb2 /Documentation/filesystems
parentd2d3dd5ecce11ba560ff024e63ddb1640b7b27b0 (diff)
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follow_link has been replaced by get_link() which can be called in RCU mode.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@gmail.com> Reviewed-by: NeilBrown <neilb@suse.de> Link: https://lore.kernel.org/r/20210527091618.287093-8-foxhlchen@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/path-lookup.rst12
1 files 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