linux-kernel - Re: [PATCH 00/18] new API for FS_IOC_[GS]ETFLAGS/FS_IOC

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Date:   Mon, 8 Feb 2021 09:25:22 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Dave Chinner <david@...morbit.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Miklos Szeredi <mszeredi@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Al Viro <viro@...iv.linux.org.uk>,
        Andreas Dilger <adilger@...ger.ca>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Christoph Hellwig <hch@....de>,
        "Darrick J . Wong" <djwong@...nel.org>,
        Dave Kleikamp <shaggy@...nel.org>,
        David Sterba <dsterba@...e.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>, Jan Kara <jack@...e.cz>,
        Joel Becker <jlbec@...lplan.org>,
        Mike Marshall <hubcap@...ibond.com>,
        Richard Weinberger <richard@....at>,
        Ryusuke Konishi <konishi.ryusuke@...il.com>,
        "Theodore Ts'o" <tytso@....edu>, Tyler Hicks <code@...icks.com>
Subject: Re: [PATCH 00/18] new API for FS_IOC_[GS]ETFLAGS/FS_IOC_FS[GS]ETXATTR

On Mon, Feb 8, 2021 at 3:00 AM Dave Chinner <david@...morbit.com> wrote:
>
> On Wed, Feb 03, 2021 at 04:03:06PM +0100, Miklos Szeredi wrote:
> > On Wed, Feb 3, 2021 at 3:56 PM Matthew Wilcox <willy@...radead.org> wrote:
> >
> > > But let's talk specifics.  What does CIFS need to contact the server for?
> > > Could it be cached earlier?
> >
> > I don't understand what CIFS is doing, and I don't really care.   This
> > is the sort of operation where adding a couple of network roundtrips
> > so that the client can obtain the credentials required to perform the
> > operation doesn't really matter.  We won't have thousands of chattr(1)
> > calls per second.
>
> Incorrect.

Okay, I was wrong.

Still, CIFS may very well be able to perform these operations without
a struct file.   But even if it can't, I'd still only add the file
pointer as an *optional hint* from the VFS, not as the primary object
as Matthew suggested.

I stand by my choice of /struct dentry/ as the object to pass to these
operations.

Thanks,
Miklos