linux-kernel - Re: [RESEND] [PATCH] eventfs: Have inodes have unique inode numbers

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Date: Fri, 26 Jan 2024 16:27:28 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Christian Brauner <brauner@...nel.org>, Ajay Kaher
 <ajay.kaher@...adcom.com>, Geert Uytterhoeven <geert@...ux-m68k.org>,
 linux-fsdevel <linux-fsdevel@...r.kernel.org>, Linus Torvalds
 <torvalds@...ux-foundation.org>
Subject: Re: [RESEND] [PATCH] eventfs: Have inodes have unique inode numbers

On Fri, 26 Jan 2024 15:24:17 -0500
Mathieu Desnoyers <mathieu.desnoyers@...icios.com> wrote:

> On 2024-01-26 15:12, Steven Rostedt wrote:
> [...]
> > diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
> > index e1b172c0e091..2187be6d7b23 100644
> > --- a/fs/tracefs/inode.c
> > +++ b/fs/tracefs/inode.c
> > @@ -223,13 +223,41 @@ static const struct inode_operations tracefs_file_inode_operations = {
> >   	.setattr	= tracefs_setattr,
> >   };
> >   
> > +/* Copied from get_next_ino() but adds allocation for multiple inodes */
> > +#define LAST_INO_BATCH 1024
> > +#define LAST_INO_MASK (~(LAST_INO_BATCH - 1))
> > +static DEFINE_PER_CPU(unsigned int, last_ino);
> > +
> > +unsigned int tracefs_get_next_ino(int files)
> > +{
> > +	unsigned int *p = &get_cpu_var(last_ino);
> > +	unsigned int res = *p;
> > +
> > +#ifdef CONFIG_SMP
> > +	/* Check if adding files+1 overflows */  
> 
> How does it handle a @files input where:
> 
> * (files+1 > LAST_INO_BATCH) ?
> 
> * (files+1 == LAST_INO_BATCH) ?

Well, this is moot anyway, as Linus hates it.

-- Steve