From patchwork Wed Feb 7 02:56:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kent Overstreet X-Patchwork-Id: 13548073 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (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 E7599FC0E for ; Wed, 7 Feb 2024 02:56:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707274601; cv=none; b=tmur1cJYypWh71jzQe5+yyFsyDCRR/vxGRES42f7Z187DxS3QMG9toeCsw6Am5M81Ns0+1PaB5nH3lUpHyd6sADBlD9kzYj1OLbra9aHBu2L78Q/ZP48HTcte0JKLpKK0DqCQ/Xv3mY2WiinvVWmzUVr5cjlFBY1JAB5AkYytyQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707274601; c=relaxed/simple; bh=MS0WbqtVgIe8M1NZp32269Ki857UQEJAVjcpeaNthFw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hG5NGCQu4cYRHgfgAWCbU8BkSTzA3FZPoqC9PVgCpt1dYvxyqzFxC3njQocw7asK/NKgpkKZS+KQzAohjUPuNkJ3w8XLbuBuckgtNic+aeLIF+Sh/AP5LKnJZDDWZQMq8vLIW3yOHz9t/YThFcbQtOWA5H11lI1Im7mHbhGLFVg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Ye+QLjw/; arc=none smtp.client-ip=95.215.58.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Ye+QLjw/" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1707274598; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=p6CyvyH0tYATCrucslrTDjNjg0PrSUtOo7EHe4oQc5I=; b=Ye+QLjw/NWQqtmBsgOqlE1WDn0+jPGYYi/5PfOEo6x68cSdmQR3gcWWVVXAolYXm69/sfi /3V67CihVSAGRpPnRt5vurk6dxswUQQaYS3YMBEIv4TX1IczIUWkf2xtQ5/rfNVz24r4+F nd/mMoWB2rggmsdvd4Z5u/zuqpsOg+Q= From: Kent Overstreet To: linux-fsdevel@vger.kernel.org, brauner@kernel.org Cc: Kent Overstreet , linux-btrfs@vger.kernel.org, Jan Kara , Dave Chinner , "Darrick J. Wong" , Theodore Ts'o , linux-fsdevel@vger.kernel.or Subject: [PATCH v3 3/7] fs: FS_IOC_GETUUID Date: Tue, 6 Feb 2024 21:56:17 -0500 Message-ID: <20240207025624.1019754-4-kent.overstreet@linux.dev> In-Reply-To: <20240207025624.1019754-1-kent.overstreet@linux.dev> References: <20240207025624.1019754-1-kent.overstreet@linux.dev> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT 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. We're not lifting SETFSUUID from ext4 - that can be done on offline filesystems by the people who need it, trying to do it online is just asking for too much trouble. 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 --- .../userspace-api/ioctl/ioctl-number.rst | 3 ++- fs/ioctl.c | 16 ++++++++++++++++ include/uapi/linux/fs.h | 16 ++++++++++++++++ 3 files changed, 34 insertions(+), 1 deletion(-) diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst index 457e16f06e04..3731ecf1e437 100644 --- a/Documentation/userspace-api/ioctl/ioctl-number.rst +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst @@ -82,8 +82,9 @@ Code Seq# Include File Comments 0x10 00-0F drivers/char/s390/vmcp.h 0x10 10-1F arch/s390/include/uapi/sclp_ctl.h 0x10 20-2F arch/s390/include/uapi/asm/hypfs.h -0x12 all linux/fs.h +0x12 all linux/fs.h BLK* ioctls linux/blkpg.h +0x15 all linux/fs.h FS_IOC_* ioctls 0x1b all InfiniBand Subsystem 0x20 all drivers/cdrom/cm206.h diff --git a/fs/ioctl.c b/fs/ioctl.c index 76cf22ac97d7..74eab9549383 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; + struct fsuuid2 u = { .len = sb->s_uuid_len, }; + + if (!sb->s_uuid_len) + return -ENOIOCTLCMD; + + memcpy(&u.uuid[0], &sb->s_uuid, sb->s_uuid_len); + + return copy_to_user(argp, &u, sizeof(u)) ? -EFAULT : 0; +} + /* * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d. * It's just a simple helper for sys_ioctl and compat_sys_ioctl. @@ -845,6 +858,9 @@ static int do_vfs_ioctl(struct file *filp, unsigned int fd, case FS_IOC_FSSETXATTR: return ioctl_fssetxattr(filp, argp); + case FS_IOC_GETFSUUID: + return ioctl_getfsuuid(filp, argp); + default: if (S_ISREG(inode->i_mode)) return file_ioctl(filp, cmd, argp); diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 48ad69f7722e..d459f816cd50 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -64,6 +64,19 @@ struct fstrim_range { __u64 minlen; }; +/* + * We include a length field because some filesystems (vfat) have an identifier + * that we do want to expose as a UUID, but doesn't have the standard length. + * + * We use a fixed size buffer beacuse this interface will, by fiat, never + * support "UUIDs" longer than 16 bytes; we don't want to force all downstream + * users to have to deal with that. + */ +struct fsuuid2 { + __u8 len; + __u8 uuid[16]; +}; + /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */ #define FILE_DEDUPE_RANGE_SAME 0 #define FILE_DEDUPE_RANGE_DIFFERS 1 @@ -190,6 +203,9 @@ struct fsxattr { * (see uapi/linux/blkzoned.h) */ +/* Returns the external filesystem UUID, the same one blkid returns */ +#define FS_IOC_GETFSUUID _IOR(0x15, 0, struct fsuuid2) + #define BMAP_IOCTL 1 /* obsolete - kept for compatibility */ #define FIBMAP _IO(0x00,1) /* bmap access */ #define FIGETBSZ _IO(0x00,2) /* get the block size used for bmap */