[PATCH v2 12/12] docs: path-lookup: update symlink description

Fox Chen
2021-03-16T05:48:59Z

instead of lookup_real()/vfs_create(), i_op->lookup() and
i_op->create() will be called directly.

update vfs_open() logic

should_follow_link is merged into lookup_last() or open_last_lookup()
which returns symlink name instead of an integer.

Signed-off-by: Fox Chen <foxhlchen@gmail.com>
---
Documentation/filesystems/path-lookup.rst | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/Documentation/filesystems/path-lookup.rst b/Documentation/filesystems/path-lookup.rst
index eef6e9f68fba..adbc714740c2 100644
--- a/Documentation/filesystems/path-lookup.rst
+++ b/Documentation/filesystems/path-lookup.rst
@@ -1202,16 +1202,15 @@ the code.
it. If the file was found in the dcache, then ``vfs_open()`` is used for
this. If not, then ``lookup_open()`` will either call ``atomic_open()`` (if
the filesystem provides it) to combine the final lookup with the open, or
- will perform the separate ``lookup_real()`` and ``vfs_create()`` steps
+ will perform the separate ``i_op->lookup()`` and ``i_op->create()`` steps
directly. In the later case the actual "open" of this newly found or
created file will be performed by ``vfs_open()``, just as if the name
were found in the dcache.

2. ``vfs_open()`` can fail with ``-EOPENSTALE`` if the cached information
- wasn't quite current enough. Rather than restarting the lookup from
- the top with ``LOOKUP_REVAL`` set, ``lookup_open()`` is called instead,
- giving the filesystem a chance to resolve small inconsistencies.
- If that doesn't work, only then is the lookup restarted from the top.
+ wasn't quite current enough. If it's in RCU-walk -ECHILD will be returned
+ otherwise will return -ESTALE. When -ESTALE is returned, the caller may
+ retry with LOOKUP_REVAL flag set.

3. An open with O_CREAT **does** follow a symlink in the final component,
unlike other creation system calls (like ``mkdir``). So the sequence::
@@ -1221,8 +1220,8 @@ the code.

will create a file called ``/tmp/bar``. This is not permitted if
``O_EXCL`` is set but otherwise is handled for an O_CREAT open much
- like for a non-creating open: ``should_follow_link()`` returns ``1``, and
- so does ``do_last()`` so that ``trailing_symlink()`` gets called and the
+ like for a non-creating open: ``lookup_last()`` or ``open_last_lookup()``
+ returns a non ``Null`` value, and ``link_path_walk()`` gets called and the
open process continues on the symlink that was found.

Updating the access time
--
2.30.2