linux-kernel - Re: [PATCH] Add FS_CLOSE_READ and FS_CLOSE

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Message-ID: <1443033122.2524.15.camel@gmail.com>
Date:	Wed, 23 Sep 2015 20:32:02 +0200
From:	Patrick Puzik <p.puzik91@...il.com>
To:	Jan Kara <jack@...e.cz>
Cc:	Jan Kara <jack@...e.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Josef Bacik <jbacik@...com>,
	Dave Chinner <dchinner@...hat.com>,
	Nikolay Borisov <kernel@...p.com>,
	linux-kernel@...r.kernel.org, Patrick Puzik <p.puzi91@...il.com>
Subject: Re: [PATCH] Add FS_CLOSE_READ and FS_CLOSE_NOREAD flag to fsnotify

1)They should be additionly sent. But at this point in time, there is
no possibility to get directly notified if a readable writable was
closed. Using these flags in combination with the existing ones is a
way to handle this lack of functionality.

2) I currently don't have an application that uses this new
functionality, but it may come to an aid in the future for some
developers who would find it avaiable whenever they need it.
They can spare time and effort, don't you think?

In my opinion it would be better to have a:
        1- CLOSE_READ
        2- CLOSE_WRITE
        3- CLOSE_READ_WRITE
flag or so but I guess this wouldn't be possible because of compability
issues. right?


--
Best Regards
Patrick Puzik


On Tue, 2015-09-22 at 11:06 +0200, Jan Kara wrote:
> On Sun 20-09-15 23:07:35, Patrick Puzik wrote:
> > Attached is a patch which is a preparation for the later support of
> > an
> > event notification, when an unreadable or readable file was closed.
> 
> So I'm missing two things in this patch (or rather changelog):
> 
> 1) When should these events be generated? I can kind of infer this
> from the
> comment and event name but for example FS_CLOSE_WRITE and
> FS_CLOSE_NOWRITE
> are exclusive. I suppose we will generate FS_CLOSE_READ or
> FS_CLOSE_NOREAD
> in addition to that?
> 
> 2) What is the use case? I.e. what is your application doing that
> current
> notification events are not enough?
> 
> 								Honza
> > 
> > Signed-off-by: Patrick Puzik <p.puzik91@...il.com>
> > ---
> >  include/linux/fsnotify_backend.h | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> > 
> > diff --git a/include/linux/fsnotify_backend.h
> > b/include/linux/fsnotify_backend.h
> > index 533c440..7563679 100644
> > --- a/include/linux/fsnotify_backend.h
> > +++ b/include/linux/fsnotify_backend.h
> > @@ -28,6 +28,8 @@
> >  #define FS_ATTRIB		0x00000004	/* Metadata
> > changed */
> >  #define FS_CLOSE_WRITE		0x00000008	/*
> > Writtable file was closed */
> >  #define FS_CLOSE_NOWRITE	0x00000010	/* Unwrittable
> > file closed */
> > +#define FS_CLOSE_READ           0x00000011      /* Unreadable file
> > closed */
> > +#define FS_CLOSE_NOREAD         0x00000012      /* Readable file
> > was closed */
> >  #define FS_OPEN			0x00000020	/* File
> > was opened */
> >  #define FS_MOVED_FROM		0x00000040	/* File was
> > moved from X */
> >  #define FS_MOVED_TO		0x00000080	/* File was
> > moved to Y */
> > @@ -56,9 +58,10 @@
> >  
> >  /* This is a list of all events that may get sent to a parernt
> > based on fs event
> >   * happening to inodes inside that directory */
> > -#define FS_EVENTS_POSS_ON_CHILD   (FS_ACCESS | FS_MODIFY |
> > FS_ATTRIB |\
> > -				   FS_CLOSE_WRITE |
> > FS_CLOSE_NOWRITE | FS_OPEN |\
> > -				   FS_MOVED_FROM | FS_MOVED_TO |
> > FS_CREATE |\
> > +#define FS_EVENTS_POSS_ON_CHILD   (FS_ACCESS | FS_MODIFY |
> > FS_ATTRIB | \
> > +				   FS_CLOSE_WRITE |
> > FS_CLOSE_NOWRITE | \
> > +				   FS_CLOSE_READ | FS_CLOSE_NOREAD
> > | FS_OPEN | \
> > +				   FS_MOVED_FROM | FS_MOVED_TO |
> > FS_CREATE | \
> >  				   FS_DELETE | FS_OPEN_PERM |
> > FS_ACCESS_PERM)
> >  
> >  #define FS_MOVE			(FS_MOVED_FROM |
> > FS_MOVED_TO)
> > @@ -66,7 +69,8 @@
> >  #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
> >  
> >  #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
> > -			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE |
> > FS_OPEN | \
> > +			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
> > +			     FS_CLOSE_READ | FS_CLOSE_NOREAD |
> > FS_OPEN | \
> >  			     FS_MOVED_FROM | FS_MOVED_TO |
> > FS_CREATE | \
> >  			     FS_DELETE | FS_DELETE_SELF |
> > FS_MOVE_SELF | \
> >  			     FS_UNMOUNT | FS_Q_OVERFLOW |
> > FS_IN_IGNORED | \
> > -- 
> > 2.4.3
> > 
> > 
--
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