linux-kernel - Re: [PATCH 15/79] bfs: switch to new ctime accessors

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Date:   Thu, 22 Jun 2023 08:51:58 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Jan Kara <jack@...e.cz>
Cc:     Christian Brauner <brauner@...nel.org>,
        "Tigran A. Aivazian" <aivazian.tigran@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        linux-kernel@...r.kernel.org,
        "damien.lemoal" <damien.lemoal@...nsource.wdc.com>
Subject: Re: [PATCH 15/79] bfs: switch to new ctime accessors

On Thu, 2023-06-22 at 14:30 +0200, Jan Kara wrote:
> On Wed 21-06-23 12:57:19, Jeff Layton wrote:
> > On Wed, 2023-06-21 at 18:48 +0200, Jan Kara wrote:
> > > On Wed 21-06-23 10:45:28, Jeff Layton wrote:
> > > > In later patches, we're going to change how the ctime.tv_nsec field is
> > > > utilized. Switch to using accessor functions instead of raw accesses of
> > > > inode->i_ctime.
> > > > 
> > > > Signed-off-by: Jeff Layton <jlayton@...nel.org>
> > > 
> > > ...
> > > 
> > > > diff --git a/fs/bfs/inode.c b/fs/bfs/inode.c
> > > > index 1926bec2c850..c964316be32b 100644
> > > > --- a/fs/bfs/inode.c
> > > > +++ b/fs/bfs/inode.c
> > > > @@ -82,10 +82,10 @@ struct inode *bfs_iget(struct super_block *sb, unsigned long ino)
> > > >  	inode->i_blocks = BFS_FILEBLOCKS(di);
> > > >  	inode->i_atime.tv_sec =  le32_to_cpu(di->i_atime);
> > > >  	inode->i_mtime.tv_sec =  le32_to_cpu(di->i_mtime);
> > > > -	inode->i_ctime.tv_sec =  le32_to_cpu(di->i_ctime);
> > > > +	inode_ctime_set_sec(inode, le32_to_cpu(di->i_ctime));
> > > >  	inode->i_atime.tv_nsec = 0;
> > > >  	inode->i_mtime.tv_nsec = 0;
> > > > -	inode->i_ctime.tv_nsec = 0;
> > > > +	inode_ctime_set_nsec(inode, 0);
> > > 
> > > So I'm somewhat wondering here - in other filesystem you construct
> > > timespec64 and then use inode_ctime_set(). Here you use
> > > inode_ctime_set_sec() + inode_ctime_set_nsec(). What's the benefit? It
> > > seems these two functions are not used that much some maybe we could just
> > > live with just inode_ctime_set() and constructing timespec64 when needed?
> > > 
> > > 								Honza
> > 
> > The main advantage is that by using that, I didn't need to do quite so
> > much of this conversion by hand. My coccinelle skills are pretty
> > primitive. I went with whatever conversion was going to give minimal
> > changes, to the existing accesses for the most part.
> > 
> > We could certainly do it the way you suggest, it just means having to
> > re-touch a lot of this code by hand, or someone with better coccinelle
> > chops suggesting a way to declare a temporary variables in place.
> 
> Well, maybe temporary variables aren't that convenient but we could provide
> function setting ctime from sec & nsec value without having to declare
> temporary timespec64? Attached is a semantic patch that should deal with
> that - at least it seems to handle all the cases I've found.
> 

Ok, let me try respinning this with your cocci script and see how it
looks.

Damien also suggested in a reply to the zonefs patch a preference for
the naming style you have above. Should I also rename these like?

    inode_ctime_peek -> inode_get_ctime
    inode_ctime_set -> inode_set_ctime

This would be the time to change it if that's preferred.
-- 
Jeff Layton <jlayton@...nel.org>