From: Fox Chen <foxhlchen@gmail.com>
To: corbet@lwn.net, vegard.nossum@oracle.com,
viro@zeniv.linux.org.uk, rdunlap@infradead.org,
grandmaster@al2klimov.de
Cc: Fox Chen <foxhlchen@gmail.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 07/12] docs: path-lookup: i_op->follow_link replaced with i_op->get_link
Date: Tue, 26 Jan 2021 15:24:38 +0800 [thread overview]
Message-ID: <20210126072443.33066-8-foxhlchen@gmail.com> (raw)
In-Reply-To: <20210126072443.33066-1-foxhlchen@gmail.com>
follow_link has been replaced by get_link() which can be
called in RCU mode.
see commit: 6b2553918d8b4e6de9853fd6315bec7271a2e592
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 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
next prev parent reply other threads:[~2021-01-26 18:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 7:24 [PATCH 00/12] docs: path-lookup: Update pathlookup docs Fox Chen
2021-01-26 7:24 ` [PATCH 01/12] docs: path-lookup: update follow_managed() part Fox Chen
2021-01-26 14:03 ` Greg KH
2021-01-27 1:11 ` Fox Chen
2021-01-28 3:20 ` NeilBrown
2021-01-26 7:24 ` [PATCH 02/12] docs: path-lookup: update path_to_nameidata() parth Fox Chen
2021-01-28 3:24 ` NeilBrown
2021-01-26 7:24 ` [PATCH 03/12] docs: path-lookup: update path_mountpoint() part Fox Chen
2021-01-28 3:28 ` NeilBrown
2021-01-26 7:24 ` [PATCH 04/12] docs: path-lookup: update do_last() part Fox Chen
2021-01-28 3:50 ` NeilBrown
2021-01-26 7:24 ` [PATCH 05/12] docs: path-lookup: remove filename_mountpoint Fox Chen
2021-01-26 7:24 ` [PATCH 06/12] docs: path-lookup: Add macro name to symlink limit description Fox Chen
2021-01-26 7:24 ` Fox Chen [this message]
2021-01-28 3:53 ` [PATCH 07/12] docs: path-lookup: i_op->follow_link replaced with i_op->get_link NeilBrown
2021-01-26 7:24 ` [PATCH 08/12] docs: path-lookup: update i_op->put_link and cookie description Fox Chen
2021-01-28 3:50 ` NeilBrown
2021-01-26 7:24 ` [PATCH 09/12] docs: path-lookup: no get_link() Fox Chen
2021-01-26 7:24 ` [PATCH 10/12] docs: path-lookup: update WALK_GET, WALK_PUT desc Fox Chen
2021-01-26 7:24 ` [PATCH 11/12] docs: path-lookup: update get_link() ->follow_link description Fox Chen
2021-01-26 7:24 ` [PATCH 12/12] docs: path-lookup: update symlink description Fox Chen
2021-01-26 7:30 ` [PATCH 00/12] docs: path-lookup: Update pathlookup docs Fox Chen
2021-01-26 20:31 ` Jonathan Corbet
2021-01-28 1:23 ` Fox Chen
2021-01-28 3:58 ` NeilBrown
2021-01-29 1:29 ` Fox Chen
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