Re: [PATCH -next] bcache: Convert to DEFINE_SHOW_ATTRIBUTE

[miaoqinglang]

在 2020/7/17 10:22, Coly Li 写道:
> On 2020/7/16 17:54, Coly Li wrote:
> > On 2020/7/16 17:03, Qinglang Miao wrote:
> > > From: Yongqiang Liu <liuyongqiang13@xxxxxxxxxx>
> >
> > Hi Qianlang and Yongqiang,
> >
> > > Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.
> > >
> > > Signed-off-by: Yongqiang Liu <liuyongqiang13@xxxxxxxxxx>
> > > ---
> > >   drivers/md/bcache/closure.c | 16 +++-------------
> > >   1 file changed, 3 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/md/bcache/closure.c b/drivers/md/bcache/closure.c
> > > index 99222aa5d..37b9c5d49 100644
> > > --- a/drivers/md/bcache/closure.c
> > > +++ b/drivers/md/bcache/closure.c
> > > @@ -159,7 +159,7 @@ void closure_debug_destroy(struct closure *cl)
> > >   
> > >   static struct dentry *closure_debug;
> > >   
> > > -static int debug_seq_show(struct seq_file *f, void *data)
> > > +static int debug_show(struct seq_file *f, void *data)
> > >   {
> > >   	struct closure *cl;
> > >   
> > > @@ -188,17 +188,7 @@ static int debug_seq_show(struct seq_file *f, void *data)
> > >   	return 0;
> > >   }
> > >   
> > > -static int debug_seq_open(struct inode *inode, struct file *file)
> > > -{
> > > -	return single_open(file, debug_seq_show, NULL);
> > > -}
> > > -
> >
> > Here NULL is sent to single_open(), in DEFINE_SHOW_ATTRIBUTE()
> > inode->i_private is sent into single_open(). I don't see the commit log
> > mentions or estimates such change.
>
> Still this change modifies original code logic, I need to know the exact
> effect before taking this patch.
>
It's equivalent to original code logic, because inode->iprivate equals 
to third parameter of debugfs_create_file() which is NULL.
> > > -static const struct file_operations debug_ops = {
> > > -	.owner		= THIS_MODULE,
> > > -	.open		= debug_seq_open,
> > > -	.read_iter		= seq_read_iter,
> >
> > I doubt this patch applies to Linux v5.8-rc, this is how debug_ops is
> > defined in Linux v5.8-rc5,
>
> I realize your patch is against linux-next, which is ahead of both
> linux-block and mainline tree. So this patch does not apply to
> linux-block tree, which is my upstream for bcache going to upstream.
>
> I suggest to generate the patch against latest mainline kernel, or
> linux-block branch for next merge window (for 5.9 it is branch
> remotes/origin/for-5.9/drivers).
I've sent a new patch against latest mainline kernel. Thanks.
> > 196 static const struct file_operations debug_ops = {
> > 197         .owner          = THIS_MODULE,
> > 198         .open           = debug_seq_open,
> > 199         .read           = seq_read,
> > 200         .release        = single_release
> > 201 };
> >
> > > -	.release	= single_release
> > > -};
> > > +DEFINE_SHOW_ATTRIBUTE(debug);
> > >   
> > >   void  __init closure_debug_init(void)
> > >   {
> > > @@ -209,7 +199,7 @@ void  __init closure_debug_init(void)
> > >   		 * about this.
> > >   		 */
> > >   		closure_debug = debugfs_create_file(
> > > -			"closures", 0400, bcache_debug, NULL, &debug_ops);
> > > +				"closures", 0400, bcache_debug, NULL, &debug_fops);
> > >   }
> > >   #endif
> >
> > Do you test your change with upstream kernel ? Or at least you should
> > try to apply and compile the patch with latest upstream kernel.
>
> I withdraw the above wrong word, the -next tag in patch subject was
> overlooked by me. Next time I will try to avoid such mistake.
>
> Coly Li
>
>
> .