From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A6A534D11B; Mon, 5 Feb 2024 23:59:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707177571; cv=none; b=kjNHYwySgcbyr8dRlWWPjuDhoUwRmVwltvWdm88m6BLrqOxOPCzGq6S7R8YfF4AwRfGtKBdrwsE0b4PTfsq2EP2Wj9rdX0mkcAax4FriehceUOKVn6hBZJhMSmMQ0aQoNIqEmY52aJ2DBjLm3XIEaYlEF3cCymwgl+PTRbnfEDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707177571; c=relaxed/simple; bh=311rEKidzYaFW4/d84Q1AgvS1KB7if5JdpM6hqvaaio=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fSJMce713LXnE7uatxXyCKB6LoJWOFlySBQfO+azOt/OReGcYHoGlU+p/eHX81juVeNuAMirU+FdfotGAalVE8Qncef2cDwHiXuaoQfJN9OO+M0ez7Sl2xMI8lUYV7mrp60DOOtziRL2qwdKv8J8CgeVTfwKBUrf4d1YZWzUWNI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Va3lu6Nc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Va3lu6Nc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2906AC433C7; Mon, 5 Feb 2024 23:59:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707177571; bh=311rEKidzYaFW4/d84Q1AgvS1KB7if5JdpM6hqvaaio=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Va3lu6NcfuOkDZ0rurlc66h9UYINPbbON9v32BDL6fLEOoCWixiQbP/GsoYWNOA9c WrfJ/1yk5q56bec70Pyx1deQVXeDTBl+jUu1HDjn1HjncpMvRYfEKTomPG8oxuGgVy MnYK+k5MrGBa5pvBhh3dWjIlh5rTAwtrwOkVehDO9qJHq5osMC9cLHgN9AzIEgmpAE /o7koH7OJOFk3JuAMj2OHiCiHYE/DSNlok7ASCCWyGxrMRLslbDkzf2HjCepbaYLaE qrLHrMjXHSVC0YFmuyK+1Vr6HcFZWCwZ9yddbnpvxWPuxKSQ+cyyHMPEqzTLlO3h69 nA1nhIf9FgNRA== Date: Mon, 5 Feb 2024 15:59:30 -0800 From: "Darrick J. Wong" To: Kent Overstreet Cc: Dave Chinner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, Christian Brauner , Jan Kara , Dave Chinner , Theodore Ts'o , linux-fsdevel@vger.kernel.or Subject: Re: [PATCH 2/6] fs: FS_IOC_GETUUID Message-ID: <20240205235930.GP616564@frogsfrogsfrogs> References: <20240205200529.546646-1-kent.overstreet@linux.dev> <20240205200529.546646-3-kent.overstreet@linux.dev> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Feb 05, 2024 at 05:49:30PM -0500, Kent Overstreet wrote: > On Tue, Feb 06, 2024 at 09:17:58AM +1100, Dave Chinner wrote: > > On Mon, Feb 05, 2024 at 03:05:13PM -0500, Kent Overstreet wrote: > > > Add a new generic ioctls for querying the filesystem UUID. > > > > > > These are lifted versions of the ext4 ioctls, with one change: we're not > > > using a flexible array member, because UUIDs will never be more than 16 > > > bytes. > > > > > > This patch adds a generic implementation of FS_IOC_GETFSUUID, which > > > reads from super_block->s_uuid; FS_IOC_SETFSUUID is left for individual > > > filesystems to implement. > > > > > > Signed-off-by: Kent Overstreet > > > Cc: Christian Brauner > > > Cc: Jan Kara > > > Cc: Dave Chinner > > > Cc: "Darrick J. Wong" > > > Cc: Theodore Ts'o > > > Cc: linux-fsdevel@vger.kernel.or > > > Signed-off-by: Kent Overstreet > > > --- > > > fs/ioctl.c | 16 ++++++++++++++++ > > > include/uapi/linux/fs.h | 16 ++++++++++++++++ > > > 2 files changed, 32 insertions(+) > > > > > > diff --git a/fs/ioctl.c b/fs/ioctl.c > > > index 76cf22ac97d7..858801060408 100644 > > > --- a/fs/ioctl.c > > > +++ b/fs/ioctl.c > > > @@ -763,6 +763,19 @@ static int ioctl_fssetxattr(struct file *file, void __user *argp) > > > return err; > > > } > > > > > > +static int ioctl_getfsuuid(struct file *file, void __user *argp) > > > +{ > > > + struct super_block *sb = file_inode(file)->i_sb; > > > + > > > + if (WARN_ON(sb->s_uuid_len > sizeof(sb->s_uuid))) > > > + sb->s_uuid_len = sizeof(sb->s_uuid); > > > > A "get"/read only ioctl should not be change superblock fields - > > this is not the place for enforcing superblock filed constraints. > > Make a helper function super_set_uuid(sb, uuid, uuid_len) for the > > filesystems to call that does all the validity checking and then > > sets the superblock fields appropriately. > > *nod* good thought... > > > > +struct fsuuid2 { > > > + __u32 fsu_len; > > > + __u32 fsu_flags; > > > + __u8 fsu_uuid[16]; > > > +}; > > > > Nobody in userspace will care that this is "version 2" of the ext4 > > ioctl. I'd just name it "fs_uuid" as though the ext4 version didn't > > ever exist. > > I considered that - but I decided I wanted the explicit versioning, > because too often we live with unfixed mistakes because versioning is > ugly, or something? > > Doing a new revision of an API should be a normal, frequent thing, and I > want to start making it a convention. > > > > > > + > > > /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */ > > > #define FILE_DEDUPE_RANGE_SAME 0 > > > #define FILE_DEDUPE_RANGE_DIFFERS 1 > > > @@ -215,6 +229,8 @@ struct fsxattr { > > > #define FS_IOC_FSSETXATTR _IOW('X', 32, struct fsxattr) > > > #define FS_IOC_GETFSLABEL _IOR(0x94, 49, char[FSLABEL_MAX]) > > > #define FS_IOC_SETFSLABEL _IOW(0x94, 50, char[FSLABEL_MAX]) > > > +#define FS_IOC_GETFSUUID _IOR(0x94, 51, struct fsuuid2) > > > +#define FS_IOC_SETFSUUID _IOW(0x94, 52, struct fsuuid2) > > > > 0x94 is the btrfs ioctl space, not the VFS space - why did you > > choose that? That said, what is the VFS ioctl space identifier? 'v', > > perhaps? > > "Promoting ioctls from fs to vfs without revising and renaming > considered harmful"... this is a mess that could have been avoided if we > weren't taking the lazy route. > > And 'v' doesn't look like it to me, I really have no idea what to use > here. Does anyone? I thought it was 'f' but apparently that's ext? --D