Commit 3c1be84b authored by Fox Chen's avatar Fox Chen Committed by Jonathan Corbet
Browse files

docs: path-lookup: update get_link() ->follow_link description 



get_link() is merged into pick_link(). i_op->follow_link is
replaced with i_op->get_link(). get_link() can return ERR_PTR(0)
which equals NULL.

Signed-off-by: default avatarFox Chen <foxhlchen@gmail.com>
Reviewed-by: default avatarNeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20210527091618.287093-12-foxhlchen@gmail.com


Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent de9414ad

Documentation/filesystems/path-lookup.rst

+6 −7
Original line number Diff line number Diff line
@@ -1136,10 +1136,10 @@ Symlinks with no final component 


A pair of special-case symlinks deserve a little further explanation.

Both result in a new ``struct path`` (with mount and dentry) being set

up in the ``nameidata``, and result in ``get_link()`` returning ``NULL``.

up in the ``nameidata``, and result in ``pick_link()`` returning ``NULL``.



The more obvious case is a symlink to "``/``".  All symlinks starting

with "``/``" are detected in ``get_link()`` which resets the ``nameidata``

with "``/``" are detected in ``pick_link()`` which resets the ``nameidata``

to point to the effective filesystem root.  If the symlink only

contains "``/``" then there is nothing more to do, no components at all,

so ``NULL`` is returned to indicate that the symlink can be released and
@@ -1156,12 +1156,11 @@ something that looks like a symlink. It is really a reference to the 
target file, not just the name of it.  When you ``readlink`` these

objects you get a name that might refer to the same file - unless it

has been unlinked or mounted over.  When ``walk_component()`` follows

one of these, the ``->follow_link()`` method in "procfs" doesn't return

one of these, the ``->get_link()`` method in "procfs" doesn't return

a string name, but instead calls ``nd_jump_link()`` which updates the

``nameidata`` in place to point to that target.  ``->follow_link()`` then

returns ``NULL``.  Again there is no final component and ``get_link()``

reports this by leaving the ``last_type`` field of ``nameidata`` as

``LAST_BIND``.

``nameidata`` in place to point to that target.  ``->get_link()`` then

returns ``NULL``.  Again there is no final component and ``pick_link()``

returns ``NULL``.



Following the symlink in the final component

--------------------------------------------