linux-kernel - Re: [PATCH] docs: fs: Refactor directory-locking.rst for better reading

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Date:   Tue, 7 Sep 2021 10:43:42 +0300
From:   Kari Argillander <kari.argillander@...il.com>
To:     Jonathan Corbet <corbet@....net>
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] docs: fs: Refactor directory-locking.rst for better
 reading

On Tue, Aug 17, 2021 at 01:26:39AM +0300, Kari Argillander wrote:
> Reorganize classes so that it is easier to read. Before number 4 was
> written in one lenghty paragraph. It is as long as number 6 and it is
> basically same kind of class (rename()). Also old number 5 was list and
> it is as short as 1, 2, 3 so it can be converted non list.
> 
> This makes file now much readible.

Gently ping for this one.

> 
> Signed-off-by: Kari Argillander <kari.argillander@...il.com>
> ---
>  .../filesystems/directory-locking.rst         | 31 +++++++++----------
>  1 file changed, 15 insertions(+), 16 deletions(-)
> 
> diff --git a/Documentation/filesystems/directory-locking.rst b/Documentation/filesystems/directory-locking.rst
> index 504ba940c36c..33921dff7af4 100644
> --- a/Documentation/filesystems/directory-locking.rst
> +++ b/Documentation/filesystems/directory-locking.rst
> @@ -11,7 +11,7 @@ When taking the i_rwsem on multiple non-directory objects, we
>  always acquire the locks in order by increasing address.  We'll call
>  that "inode pointer" order in the following.
>  
> -For our purposes all operations fall in 5 classes:
> +For our purposes all operations fall in 6 classes:
>  
>  1) read access.  Locking rules: caller locks directory we are accessing.
>  The lock is taken shared.
> @@ -22,26 +22,25 @@ exclusive.
>  3) object removal.  Locking rules: caller locks parent, finds victim,
>  locks victim and calls the method.  Locks are exclusive.
>  
> -4) rename() that is _not_ cross-directory.  Locking rules: caller locks
> -the parent and finds source and target.  In case of exchange (with
> -RENAME_EXCHANGE in flags argument) lock both.  In any case,
> -if the target already exists, lock it.  If the source is a non-directory,
> -lock it.  If we need to lock both, lock them in inode pointer order.
> -Then call the method.  All locks are exclusive.
> -NB: we might get away with locking the source (and target in exchange
> -case) shared.
> +4) link creation.  Locking rules: lock parent, check that source is not
> +a directory, lock source and call the method.  Locks are exclusive.
>  
> -5) link creation.  Locking rules:
> +5) rename() that is _not_ cross-directory.
> +Locking rules:
>  
> -	* lock parent
> -	* check that source is not a directory
> -	* lock source
> -	* call the method.
> +	* Caller locks the parent and finds source and target.
> +	* In case of exchange (with RENAME_EXCHANGE in flags argument)
> +	  lock both the source and the target.
> +	* If the target exists, lock it,  If the source is a non-directory,
> +	  lock it. If we need to lock both, do so in inode pointer order.
> +	* Call the method.
>  
>  All locks are exclusive.
> +NB: we might get away with locking the source (and target in exchange
> +case) shared.
>  
> -6) cross-directory rename.  The trickiest in the whole bunch.  Locking
> -rules:
> +6) rename() that _is_ cross-directory.  The trickiest in the whole bunch.
> +Locking rules:
>  
>  	* lock the filesystem
>  	* lock parents in "ancestors first" order.
> -- 
> 2.30.2
>