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From: Fox Chen <foxhlchen@gmail.com>
To: NeilBrown <neilb@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>,
	vegard.nossum@oracle.com, Al Viro <viro@zeniv.linux.org.uk>,
	rdunlap@infradead.org, grandmaster@al2klimov.de,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v2 12/12] docs: path-lookup: update symlink description
Date: Mon, 19 Apr 2021 10:34:54 +0800
Message-ID: <CAC2o3DJ6o6w9WO=QwsZjTG7TU+Jvr_My9Mxp+WR5y3EeTLmdDQ@mail.gmail.com> (raw)
In-Reply-To: <87mttv11bd.fsf@notabene.neil.brown.name>

On Mon, Apr 19, 2021 at 9:59 AM NeilBrown <neilb@suse.de> wrote:
>
> 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 for the review, I will fix them and send the next version back.


> Thanks,
> NeilBrown
>
>
> >     open process continues on the symlink that was found.
> >
> >  Updating the access time
> > --
> > 2.30.2


thanks,
fox

  reply index

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
2021-04-19  2:34     ` Fox Chen [this message]
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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