linux-kernel - Re: [PATCH v3 3/3] fs: fuse: add more information to fdinfo

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Message-ID: <CAOQ4uxj09fwcrSmx674M2yivGF5hqCdHEbS4yXx+YnGSm-Z=-A@mail.gmail.com>
Date: Fri, 9 May 2025 09:13:52 +0200
From: Amir Goldstein <amir73il@...il.com>
To: Chen Linxuan <chenlinxuan@...ontech.com>
Cc: Miklos Szeredi <miklos@...redi.hu>, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] fs: fuse: add more information to fdinfo

On Fri, May 9, 2025 at 8:40 AM Chen Linxuan <chenlinxuan@...ontech.com> wrote:
>
> On Fri, May 9, 2025 at 2:34 PM Chen Linxuan via B4 Relay
> <devnull+chenlinxuan.uniontech.com@...nel.org> wrote:
> >
> > From: Chen Linxuan <chenlinxuan@...ontech.com>
> >
> > This commit add fuse connection device id, open_flags and backing
> > files, to fdinfo of opened fuse files.
> >
> > Related discussions can be found at links below.
> >
> > Link: https://lore.kernel.org/all/CAOQ4uxgS3OUy9tpphAJKCQFRAn2zTERXXa0QN_KvP6ZOe2KVBw@mail.gmail.com/
> > Link: https://lore.kernel.org/all/CAOQ4uxgkg0uOuAWO2wOPNkMmD9wqd5wMX+gTfCT-zVHBC8CkZg@mail.gmail.com/
> > Cc: Amir Goldstein <amir73il@...il.com>
> > Signed-off-by: Chen Linxuan <chenlinxuan@...ontech.com>
> > ---
> >  fs/fuse/file.c | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> > index 754378dd9f7159f20fde6376962d45c4c706b868..1e54965780e9d625918c22a3dea48ba5a9a5ed1b 100644
> > --- a/fs/fuse/file.c
> > +++ b/fs/fuse/file.c
> > @@ -8,6 +8,8 @@
> >
> >  #include "fuse_i.h"
> >
> > +#include "linux/idr.h"
> > +#include "linux/rcupdate.h"

These are not needed.

> >  #include <linux/pagemap.h>
> >  #include <linux/slab.h>
> >  #include <linux/kernel.h>
> > @@ -3392,6 +3394,21 @@ static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
> >         return ret;
> >  }
> >
> > +static void fuse_file_show_fdinfo(struct seq_file *seq, struct file *f)
> > +{
> > +       struct fuse_file *ff = f->private_data;
> > +       struct fuse_conn *fc = ff->fm->fc;
> > +       struct file *backing_file = fuse_file_passthrough(ff);
> > +
> > +       seq_printf(seq, "fuse conn:%u open_flags:%u\n", fc->dev, ff->open_flags);
>
> Note: The fc->dev is already accessible to userspace.
> The mnt_id field in /proc/PID/fdinfo/FD references a mount,
> which can be found in /proc/PID/mountinfo.
>
> And this file includes the device ID.
>

True, but the direct reference to conn here does not hurt.

> > +
> > +       if (backing_file) {
> > +               seq_puts(seq, "fuse backing_file: ");
> > +               seq_file_path(seq, backing_file, " \t\n\\");
> > +               seq_puts(seq, "\n");
> > +       }
> > +}
> > +

With unneeded includes fixed feel free to add:
Reviewed-by: Amir Goldstein <amir73il@...il.com>

Please wait before posting v4 to give other developers and Miklos
a chance to review v3.

Thanks,
Amir.