Re: [RFC PATCH 07/20] famfs: Add include/linux/famfs_ioctl.h

From: John Groves <John@groves.net>
To: Randy Dunlap <rdunlap@infradead.org>
Cc: John Groves <jgroves@micron.com>,
	Jonathan Corbet <corbet@lwn.net>,
	 Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	 Dave Jiang <dave.jiang@intel.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	 Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	Matthew Wilcox <willy@infradead.org>,
	 linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-doc@vger.kernel.org,  linux-kernel@vger.kernel.org,
	nvdimm@lists.linux.dev, john@jagalactic.com,
	 Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@infradead.org>,
	 dave.hansen@linux.intel.com, gregory.price@memverge.com
Subject: Re: [RFC PATCH 07/20] famfs: Add include/linux/famfs_ioctl.h
Date: Sat, 24 Feb 2024 17:32:34 -0600	[thread overview]
Message-ID: <7rkmolss5vkdljnh6uksfkepklwofe3bkdsf36qhokyltjoxlx@xqgef734pidg> (raw)
In-Reply-To: <97cde8f6-21ed-45b9-9618-568933102f05@infradead.org>

On 24/02/23 07:27PM, Randy Dunlap wrote:
> Hi John,
> 
> On 2/23/24 18:23, John Groves wrote:
> >>> +
> >>> +#define FAMFSIOC_MAGIC 'u'
> >> This 'u' value should be documented in
> >> Documentation/userspace-api/ioctl/ioctl-number.rst.
> >>
> >> and if possible, you might want to use values like 0x5x or 0x8x
> >> that don't conflict with the ioctl numbers that are already used
> >> in the 'u' space.
> > Will do. I was trying to be too clever there, invoking "mu" for
> > micron. 
> 
> I might have been unclear about this one.
> It's OK to use 'u' but the values 1-4 below conflict in the 'u' space:
> 
> 'u'   00-1F  linux/smb_fs.h                                          gone
> 'u'   20-3F  linux/uvcvideo.h                                        USB video class host driver
> 'u'   40-4f  linux/udmabuf.h
> 
> so if you could use
> 'u'   50-5f
> or
> 'u'   80-8f
> 
> then those conflicts wouldn't be there.
> HTH.
> 
> >>> +
> >>> +/* famfs file ioctl opcodes */
> >>> +#define FAMFSIOC_MAP_CREATE    _IOW(FAMFSIOC_MAGIC, 1, struct famfs_ioc_map)
> >>> +#define FAMFSIOC_MAP_GET       _IOR(FAMFSIOC_MAGIC, 2, struct famfs_ioc_map)
> >>> +#define FAMFSIOC_MAP_GETEXT    _IOR(FAMFSIOC_MAGIC, 3, struct famfs_extent)
> >>> +#define FAMFSIOC_NOP           _IO(FAMFSIOC_MAGIC,  4)
> 
> -- 
> #Randy

Thanks Randy; I think I'm the one that didn't read carefully enough.

Does this look right?

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 457e16f06e04..44a44809657b 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -288,6 +288,7 @@ Code  Seq#    Include File                                           Comments
 'u'   00-1F  linux/smb_fs.h                                          gone
 'u'   20-3F  linux/uvcvideo.h                                        USB video class host driver
 'u'   40-4f  linux/udmabuf.h                                         userspace dma-buf misc device
+'u'   50-5F  linux/famfs_ioctl.h                                     famfs shared memory file system
 'v'   00-1F  linux/ext2_fs.h                                         conflict!
 'v'   00-1F  linux/fs.h                                              conflict!
 'v'   00-0F  linux/sonypi.h                                          conflict!
diff --git a/include/uapi/linux/famfs_ioctl.h b/include/uapi/linux/famfs_ioctl.h
index 6b3e6452d02f..57521898ed57 100644
--- a/include/uapi/linux/famfs_ioctl.h
+++ b/include/uapi/linux/famfs_ioctl.h
@@ -48,9 +48,9 @@ struct famfs_ioc_map {
 #define FAMFSIOC_MAGIC 'u'

 /* famfs file ioctl opcodes */
-#define FAMFSIOC_MAP_CREATE    _IOW(FAMFSIOC_MAGIC, 1, struct famfs_ioc_map)
-#define FAMFSIOC_MAP_GET       _IOR(FAMFSIOC_MAGIC, 2, struct famfs_ioc_map)
-#define FAMFSIOC_MAP_GETEXT    _IOR(FAMFSIOC_MAGIC, 3, struct famfs_extent)
-#define FAMFSIOC_NOP           _IO(FAMFSIOC_MAGIC,  4)
+#define FAMFSIOC_MAP_CREATE    _IOW(FAMFSIOC_MAGIC, 0x50, struct famfs_ioc_map)
+#define FAMFSIOC_MAP_GET       _IOR(FAMFSIOC_MAGIC, 0x51, struct famfs_ioc_map)
+#define FAMFSIOC_MAP_GETEXT    _IOR(FAMFSIOC_MAGIC, 0x52, struct famfs_extent)
+#define FAMFSIOC_NOP           _IO(FAMFSIOC_MAGIC,  0x53)

Thank you!
John

