From: NeilBrown <neilb@suse.de>
To: Fox Chen <foxhlchen@gmail.com>
Cc: Fox Chen <foxhlchen@gmail.com>,
corbet@lwn.net, vegard.nossum@oracle.com,
viro@zeniv.linux.org.uk, rdunlap@infradead.org,
grandmaster@al2klimov.de, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org
Subject: Re: [PATCH v2 12/12] docs: path-lookup: update symlink description
Date: Mon, 19 Apr 2021 11:59:50 +1000 [thread overview]
Message-ID: <87mttv11bd.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20210316054727.25655-13-foxhlchen@gmail.com>
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On Tue, Mar 16 2021, Fox Chen wrote:
> 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
"otherwise -ESTALE is returned".
If you don't like repeating "is returned", then maybe:
"... -ECHILD will be returned, otherwise the result is -ESTALE".
> + 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
"NULL", not "Null".
This those changes,
Reviewed-by: NeilBrown <neilb@suse.de>
Thanks for a lot of all these improvements!! and apologies for the delay
in the review.
Thanks,
NeilBrown
> open process continues on the symlink that was found.
>
> Updating the access time
> --
> 2.30.2
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next prev parent reply other threads:[~2021-04-19 1:59 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 5:47 [PATCH v2 00/12] docs: path-lookup: Update pathlookup docs Fox Chen
2021-03-16 5:47 ` [PATCH v2 01/12] docs: path-lookup: update follow_managed() part Fox Chen
2021-04-19 0:52 ` NeilBrown
2021-04-19 2:17 ` Matthew Wilcox
2021-04-19 2:33 ` Fox Chen
2021-04-19 3:25 ` Matthew Wilcox
2021-04-19 3:33 ` Fox Chen
2021-04-19 19:22 ` Jonathan Corbet
2021-04-20 1:12 ` Fox Chen
2021-03-16 5:47 ` [PATCH v2 02/12] docs: path-lookup: update path_to_nameidata() part Fox Chen
2021-04-19 1:00 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 03/12] docs: path-lookup: update path_mountpoint() part Fox Chen
2021-04-19 1:03 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 04/12] docs: path-lookup: update do_last() part Fox Chen
2021-04-19 1:17 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 05/12] docs: path-lookup: remove filename_mountpoint Fox Chen
2021-04-19 1:20 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 06/12] docs: path-lookup: Add macro name to symlink limit description Fox Chen
2021-04-19 1:22 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 07/12] docs: path-lookup: i_op->follow_link replaced with i_op->get_link Fox Chen
2021-04-19 1:28 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 08/12] docs: path-lookup: update i_op->put_link and cookie description Fox Chen
2021-04-19 1:37 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 09/12] docs: path-lookup: no get_link() Fox Chen
2021-04-19 1:41 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 10/12] docs: path-lookup: update WALK_GET, WALK_PUT desc Fox Chen
2021-04-19 1:47 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 11/12] docs: path-lookup: update get_link() ->follow_link description Fox Chen
2021-04-19 1:54 ` NeilBrown
2021-03-16 5:47 ` [PATCH v2 12/12] docs: path-lookup: update symlink description Fox Chen
2021-04-19 1:59 ` NeilBrown [this message]
2021-04-19 2:34 ` Fox Chen
2021-04-13 21:18 ` [PATCH v2 00/12] docs: path-lookup: Update pathlookup docs Jonathan Corbet
2021-04-13 22:26 ` NeilBrown
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