linux-ext4 - Re: [PATCH v6 04/21] fsnotify: Reserve mark flag bits for backends

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Date:   Mon, 16 Aug 2021 15:15:36 +0200
From:   Jan Kara <jack@...e.cz>
To:     Amir Goldstein <amir73il@...il.com>
Cc:     Gabriel Krisman Bertazi <krisman@...labora.com>,
        Jan Kara <jack@...e.com>,
        Linux API <linux-api@...r.kernel.org>,
        Ext4 <linux-ext4@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Khazhismel Kumykov <khazhy@...gle.com>,
        David Howells <dhowells@...hat.com>,
        Dave Chinner <david@...morbit.com>,
        Theodore Tso <tytso@....edu>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Matthew Bobrowski <repnop@...gle.com>, kernel@...labora.com
Subject: Re: [PATCH v6 04/21] fsnotify: Reserve mark flag bits for backends

On Fri 13-08-21 10:28:27, Amir Goldstein wrote:
> On Fri, Aug 13, 2021 at 12:40 AM Gabriel Krisman Bertazi
> <krisman@...labora.com> wrote:
> >
> > Split out the final bits of struct fsnotify_mark->flags for use by a
> > backend.
> >
> > Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
> >
> > Changes since v1:
> >   - turn consts into defines (jan)
> > ---
> >  include/linux/fsnotify_backend.h | 18 +++++++++++++++---
> >  1 file changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> > index 1ce66748a2d2..ae1bd9f06808 100644
> > --- a/include/linux/fsnotify_backend.h
> > +++ b/include/linux/fsnotify_backend.h
> > @@ -363,6 +363,20 @@ struct fsnotify_mark_connector {
> >         struct hlist_head list;
> >  };
> >
> > +enum fsnotify_mark_bits {
> > +       FSN_MARK_FL_BIT_IGNORED_SURV_MODIFY,
> > +       FSN_MARK_FL_BIT_ALIVE,
> > +       FSN_MARK_FL_BIT_ATTACHED,
> > +       FSN_MARK_PRIVATE_FLAGS,
> > +};
> > +
> > +#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY \
> > +       (1 << FSN_MARK_FL_BIT_IGNORED_SURV_MODIFY)
> > +#define FSNOTIFY_MARK_FLAG_ALIVE \
> > +       (1 << FSN_MARK_FL_BIT_ALIVE)
> > +#define FSNOTIFY_MARK_FLAG_ATTACHED \
> > +       (1 << FSN_MARK_FL_BIT_ATTACHED)
> > +
> >  /*
> >   * A mark is simply an object attached to an in core inode which allows an
> >   * fsnotify listener to indicate they are either no longer interested in events
> > @@ -398,9 +412,7 @@ struct fsnotify_mark {
> >         struct fsnotify_mark_connector *connector;
> >         /* Events types to ignore [mark->lock, group->mark_mutex] */
> >         __u32 ignored_mask;
> > -#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x01
> > -#define FSNOTIFY_MARK_FLAG_ALIVE               0x02
> > -#define FSNOTIFY_MARK_FLAG_ATTACHED            0x04
> > +       /* Upper bits [31:PRIVATE_FLAGS] are reserved for backend usage */
> 
> I don't understand what [31:PRIVATE_FLAGS] means

I think it should be [FSN_MARK_PRIVATE_FLAGS:31] (identifying a range of
bits). I'd maybe write just "Bits starting from FSN_MARK_PRIVATE_FLAGS are
reserved for backend usage". With this fixed feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR